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  • Biochemistry and Biotechnology  (3,415)
  • Deutschland
  • 2015-2019  (16)
  • 1995-1999  (3,416)
  • 1940-1944  (3)
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  • 1
    Call number: PIK C 329-19-92388
    Keywords: Deutschland ; Vergaberecht ; Deutschland ; Vergaberecht
    Type of Medium: Monograph available for loan
    Pages: LXIV, 614 Seiten , 20 cm
    Edition: 20. Auflage, Stand: 1. Januar 2018, Sonderausgabe
    ISBN: 9783423055956 , 9783406722059
    Series Statement: dtv 5595
    Language: German
    Branch Library: PIK Library
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  • 2
    Unknown
    Koblenz : Bundesanstalt für Gewässerkunde (BfG)
    Keywords: Germany ; hydrology ; Deutschland ; Hydrologie ; Atlas
    Description / Table of Contents: Der Atlas liefert kartographische Übersichten zu gewässerkundlichen Grunddaten sowie zu den Themenbereichen Hydrometeorologie, oberirdische Gewässer, Bodenwasser, Grundwasser, Wasserhaushalt und dem Themenkomplex Hydrologie-Ökologie-Mensch.
    Language: German
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  • 3
    Publication Date: 2021-03-29
    Description: Abstract: Current information on the potential distribution and condition of peatland soils are of great importance. This applies notably for actions with respect to climate and environmental protection. The Ministry of infrastructure and agriculture in the federal state of Brandenburg (MIL) therefore initiated a project to provide a complete and updated map of peatland soils for the federal state of Brandenburg, Germany, for the year 2013. Extensive legacy data on both, areal extent of peatland soils as well as soil profile information where made digitally available in a homogeneous map and a consistent database. Approximately 7.725 sites were randomly selected from legacy soil data and currently reinvestigated to draw inference on the current condition of peatland soils. Statistically derived peatland subsidence rates at grassland sites of 0.50 cm/yr and 0.57 cm/yr at arable sites fit well with published values in comparable regions of central Europe. Our results prove the great dynamics of soil development on agriculturally used peatlands. Concerning Brandenburg, the area of peatland soils decreased from 270.000 ha in the early 20th century (Prussian geological map) to actually 163.000 ha.
    Description: Zusammenfassung: Aktuelle Informationen zur Verbreitung und zum Zustand der Moorböden sind vor dem Hintergrund der geplanten Einführung von Agrarumwelt- und Klimamaßnahmen in der Landwirtschaft von besonderer Bedeutung. Das Ministerium für Infrastruktur und Landwirtschaft des Landes Brandenburg (MIL) hat hierzu das Projekt „Schaffung einer Datengrundlage für die Ableitung von Agrarumwelt- und Klimamaßnahmen auf Moorstandorten in Brandenburg“ initiiert. Mit dem Ziel der Bereitstellung einer auf das Jahr 2013 bezogenen Moorkarte wurden umfangreiche, bis dato nicht genutzte Datenbestände zur Verbreitung von Moorböden in Brandenburg zu einer überschneidungsfreien Karte und umfassenden Datenbank moorbodenkundlicher Bodenprofile verarbeitet. Um den aktuellen Zustand der Moorböden zu erfassen, wurden flächenrepräsentativ und zufällig an 7.725 Standorten mit ausreichender Datenbasis erneut bodenkundliche Erhebungen durchgeführt und statistisch ausgewertet. Im Ergebnis konnten Mächtigkeitsverlustraten für landwirtschaftlich genutzte Moorstandorte in Brandenburg abgeleitet werden. Für flachgründige Niedermoorstandorte unter Grünland liegen sie bei 0,50 cm/a, vergleichbare ackerbaulich genutzte Standorte liegen mit 0,57 cm/a darüber. Dies deckt sich gut mit publizierten Werten an vergleichbaren Standorten in Zentraleuropa. Die Fläche der Moorböden in Brandenburg hat sich von Anfang des 20. Jahrhunderts von 270.000 ha, ausgewiesen auf Basis der Preußisch geologisch-agronomische Karte (PGK), auf heute noch 163.000 ha reduziert.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; peatland ; Brandenburg ; Deutschland ; Germany ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
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  • 4
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    Unknown
    Inst. f. Physische Geographie, FU, Berlin
    In:  Herausgeberexemplar (FU Berlin) | ZB 20559:47
    Publication Date: 2021-03-29
    Description: Inhaltsverzeichnis : EHLERS, J. & MENSCHING, H.: Küstenversatz und Prielverlagerungen an der Nordseeküste. S. 9-22 ; FRÄNZLE, O.: Periglaziäre Formung der Altmoränengebiete Schleswig-Holsteins. S. 23-35 ; HEMPEL, L.: Rezente und fossile Mesoformen der Abtragung und Aufschüttung in Ausräumen von Schichtkammlandschaften im Teutoburger Wald. S. 37-47 ; LEHMEIER, F.: Zum Formenschatz der Schichtkammlandschaft im Niedersächsischen Bergland. S. 49-61 ; GARLEFF, K., BRUNOTTE, E. & STINGL, H.: Fußflächen im zentralen Teil der Hessischen Senke. S. 63-76 ; MÖLLER, K.: Das Eschweger Becken und seine Randbereiche — Ergebnisse geomorphographischer und hydrochemischer Analysen. S. 77-92 ; GLATTHAAR, D.: Vertikalbewegungen und ihre Bedeutung für die Formenentwicklung im Westerwald. S. 93-106 ; MÜLLER, M.J.: Periglaziärfluviale, solifluidale und abluale Formung im westlichen Hunsrück und am Ostrand der Trier-Bitburger Mulde. S. 107-118 ; BARSCH, D. & MÄUSBACHER, R.: Zur fluvialen Dynamik beim Aufbau des Neckarschwemmfächers. S. 119-128 ; LESER, H.: Schichtstufen und Talrandstufen in Südwestdeutschland. S. 129-147 ; FARRENKOPF, D.: Relief und Wasserhaushalt im Eyachtal, Nordschwarzwald. S. 149-154 ; LESER, H. & METZ, B.: Vergletscherungen im Hochschwarzwald. S. 155-175 ; HABBE, K.A.: Was kann eine geomorphologische Vollkartierung für die Stratigraphie des Quartärs leisten? S. 177-196 ; RATHJENS, C.: Jungglaziale Formung und spätglazialer Eisabbau im Chiemgau. S. 197-205 ; FISCHER, K.: Die würmzeitliche und stadiale Vergletscherung der Berchtesgadener Alpen. S. 207-225 ;
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910.02 ; Deutschland ; Geologie ; Geomorphologie ; Glazial ; Gletscher ; Küste ; FID-GEO-DE-7
    Language: German
    Type: anthology_digi
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  • 5
    facet.materialart.
    Unknown
    Im Selbstverlag des Institutes für Physische Geographie der Freien Universität Berlin
    In:  Herausgeberexemplar (FU Berlin) | FB 23640:2
    Publication Date: 2021-03-29
    Description: Zur Vereinfachung wird die Vielfalt der Karstformenbezeichnungen bereinigt. Erdfall wird als Form, die in nicht verkarstungsfähigen Serien liegt, aber auf Tiefensubrosion zurückgeht, der Doline, einer Form, die in verkarstungsfähigem Material liegt, gegenübergestellt. Als Grundlage der Arbeit wurde eine detaillierte Kartierung der Auslaugungsformen durchgeführt. Hinsichtlich rezenter Subrosion erwies es sich als notwendig, die in Oberflächenwässern und wasserwirtschaftlich erfaßten Wässern gelösten Bestandteile von Chlorid, Sulfat und Karbonat zu ermitteln. Die Auswertung der gewonnenen Daten zeigt, daß ein Zusammenhang mit Gebieten besteht, die durch aktuelle Erdfälle und Dolineneinbrüche gekennzeichnet sind. Als Voraussetzung zur Reliefgenese gilt, daß das Gebiet des Unterwerra-Sattels entscheidend durch die saxonische Gebirgsbildung an der Wende Jura/Kreide und die nachfolgende klimageomorphologische Entwicklung geprägt ist. Anhand der geomorphographischen Analyse wird der Einfluß der Salz-, aber auch der Sulfatauslaugung auf die Landschaftsgenese belegt. Die Auslaugung des Salzes (Nal), dessen Mächtigkeit im Untersuchungsgebiet mit mindestens 120 m angenommen wird, und der unterlagernden ca. 130 m nächtigen Zechsteingipse (A 1 - A 3) zerrüttet die überlagernden triassischen Schichten weiter. Darüber hinaus wirkt die Subrosion von mehr als 30 m Rötgipsen und 50 m Gipsen des Mittleren Muschelkalkes im Hangenden des Zechsteins reliefformend. Die ermittelten Ergebnisse - rezente und subrezente Formen, Lösungswerte – werden zunächst in kleineren Gebietseinheiten analysiert. Die Ergebnisse der Nasseranalysen bestätigen das geomorphographische Ergebnis, so daß in Anlehnung an die Gipshorizonte von Stockwerkssubrosion gesprochen werden kann. Entscheidend geprägt ist die heutige Situation jedoch durch vorangegangene Zechsteinsalzauslaugung im tieferen Untergrund. Diese hat in den Hangendserien die Wasserwegsamkeit verstärkt, so daß die nachfolgende Sulfatsubrosion den Kleinformenschatz vor der Schichtstufe des Mittleren Buntsandsteins steuern konnte. Aufgrund ihrer für Auslaugungsgebiete typischen Ausprägung wird die Lage der Schichtstufe in weiten Teilen des Untersuchungsgebietes an das in Auslaugung befindliche Salz geknüpft. Das Auftreten von Subrosionsformen vor der Landstufe des Kaufunger Waldes, den östlichen Meißnerhängen, dem Anstieg des Schlierbachswaldes sowie vor dem Anstieg des Buntsandsteins zwischen Heldra, Frieda und Bad Sooden-Allendorf untermauert diese Interpretation. In der südlichen und südöstlichen Umrahmung des Untersuchungsgebietes wird der Salzhang aufgrund geomorphographischer Kriterien unter dem Steilanstieg des Unteren Muschelkalkes ausgewiesen. Aufgrund dieser Befunde wird die primäre Salzverbreitung als über den Unterwerra-Sattel reichend angenommen, womit sich, abgesehen von den Einflüssen der saxonischen Tektonik, alle Reliefentwicklungsprozesse allein durch Auslaugung und folgende geomorphologische Überprägung erklären lassen. Darüber hinaus ist dieses Gebiet in Nordhessen nicht nur durch eine über alle Schichten hinweggreifende Rumpfflächenbildung gekennzeichnet, sondern die Resistenzunterschiede wurden - unabhängig vom Klima - beständig herausgearbeitet. Aus diesen Ergebnissen wurde ein übergeordnetes Modell zur Reliefentwicklung erstellt. Danach existieren im Untersuchungsgebiet fünf Reliefgenerationen, wobei die postsaxonische Reliefentwicklung mit zerstörtem, die Auslaugung begünstigendem Hangendverband nach der Landhebung bzw. dem Einbruch der das Gebiet begrenzenden Grabenstrukturen, die bis ins Alttertiär reicht, nicht erfaßt werden konnte. [...]
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910.02 ; Hessisch-thüringisches Bergland {Geologie} ; Morphogenese einzelner Regionen {Geomorphologie} ; Deutschland ; Hessen ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 196
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  • 6
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    Unknown
    Im Selbstverlag des Institutes für Physische Geographie der Freien Universität Berlin
    In:  Herausgeberexemplar (FU Berlin) | ZB 20559:60
    Publication Date: 2021-03-29
    Description: In der vorliegenden Arbeit wurden Ergebnisse hydrologischer und stratigraphischer Studien zur Entwicklungsgeschichte von Brandenburger Kesselmooren vorgestellt. Für die Erfassung der aktuellen und historischen biotischen und abiotischen Standortfaktoren wurden verschiedene Methoden angewandt: floristische und vegetationskundliche Untersuchungen sowie hydrologische, hydrochemische, geochemische, geophysikalische und sedimentologische Untersuchungen und Makrorest-‚ Mikrorest- und Pollenanalyse. Der zeitlichen Einordnung der entwicklungsgeschichtlichen Prozesse dienten Radiocarbondatierungen und die pollenanalytischen Untersuchungen. Ziel der Arbeit war es, Entwicklungsstadien auszuscheiden, die von den untersuchten Mooren seit ihrer Entstehung durchlaufen wurden. Aufgrund der stratigraphischen Untersuchungen wurden Aussagen zur Beckengenese und zu den einzelnen See- und Moorentwicklungsphasen getroffen, zum Verlandungsvorgang, zu Moorbildungsbedingungen und Sukzessionsstadien. Den Entwicklungsstadien konnten über geochemische und -physikalische Untersuchungen abiotische Standortfaktoren zugeordnet werden. Die aktuellen Standortveränderungen wurden erfaßt und die vorgenommenen Erhaltungs- und Wiedervernässungsmaßnahmen dokumentiert und bewertet.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; Teilfragen zu Brandenburg {Geographie} ; Moorkunde {Geomorphologie} ; Ostdeutschland, Berlin, Brandenburg {Hydrologie} ; Moorkunde {Geologie} ; Brandenburg ; Kessel-Moor ; Stratigraphie ; Hydrologie ; Geschichte ; Hochschulschrift ; Deutschland ; C/N ; Moor ; Pollen ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 159
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  • 7
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    Unknown
    Friedr. Vieweg & Sohn, Braunschweig
    In:  SUB Göttingen | 8 GEOGR PHYS 203:10
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 63 Artikel zu Themengebieten der Physik der festen Erde, zu magnetischen und elektrischen Feldern der Erde, zu der Physik der Atmophäre und der angewandten Geophysik veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in dem Jahr 1934.
    Description: 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0004.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0005.pdf"〉Autorenverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0006.pdf"〉Sachverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0007.pdf"〉Karl Mack †〈/a〉〈br〉(Hiller, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0008.pdf"〉Die südalbanischen Erdbeben 1930/31〈/a〉〈br〉(Nowack, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0009.pdf"〉Seismische Untersuchungen des Geophysikalischen Instituts in Göttingen〈/a〉〈br〉(Gräfe, H., v. zur Mühlen, W., Müller, H. K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0017.pdf"〉Horizontalsicht bei örtlich veränderlicher Trübung und Beleuchtung〈/a〉〈br〉(Steinhäusser, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0018.pdf"〉Referate und Mitteilungen〈/a〉〈br〉(Haase, H., Köhler, R., Berroth, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0019.pdf"〉Beitrag zur Berechnung von Minimum-Stabpendeln〈/a〉〈br〉(Graf, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0020.pdf"〉Zur Theorie elastischer Pendel mit besonderer Berücksichtigung des Holweck-Lejayschen Stabpendels〈/a〉〈br〉(Graf, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0021.pdf"〉Eine neue Methode für sehr präzise magnetische Messungen〈/a〉〈br〉(Koulomzine, T., Bondaletoff, N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0022.pdf"〉Zur Frage der mit dem temperaturkompensierten Magnetsystem erreichbaren Meßgenauigkeit〈/a〉〈br〉(Kohl, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0023.pdf"〉Die Höhenverteilung der Erd-, Luft- und Höhenstrahlung〈/a〉〈br〉(Suckstorff, G. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0024.pdf"〉Erdstrahlungsmessungen in Bad Nauheim nach der Gammastrahlenmethode〈/a〉〈br〉(Masuch, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0025.pdf"〉Referate〈/a〉〈br〉(Jung, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0026.pdf"〉Abschnitt〈/a〉〈br〉(Angenheister, G., Kohlschütter, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0027.pdf"〉Hergesell geb. 29. Mai 1859〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0028.pdf"〉Hecker geb. 21. Mai 1864〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0029.pdf"〉Sprengungen zur Forschungszwecken mit Unterstützung der Notgemeinschaft der Deutschen〈/a〉〈br〉(Duckert, P.)〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0037.pdf"〉Beiträge zu den Luftschallmessungen〈/a〉〈br〉(Meißer, O., Martin, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0039.pdf"〉Seismische Untersuchungen des Geophysikalischen Instituts in Göttingen〈/a〉〈br〉(Regula, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0042.pdf"〉Berechnung der Laufzeitkurven des anormalen Schalles für windstille Atmosphäre und Vergleich mit der Laufzeitkurve der Oldebroek-Sprengung vom 15. Dezember 1932〈/a〉〈br〉(Jung, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0043.pdf"〉Ergebisse der Registrierungen von Schallwellen an kreisförmig um den Sprengherd angeordneten Stationen〈/a〉〈br〉(Duckert, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0044.pdf"〉Beobachtungsergebnisse über den Einfluß der "akustischen Umkehrschicht" auf die Schallausbreitung〈/a〉〈br〉(Sandmann, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0045.pdf"〉Zur Frage der anomalen Schallausbreitung〈/a〉〈br〉(Kölzer, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0046.pdf"〉Schalluntersuchungen im Polargebiet〈/a〉〈br〉(Wölcken, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0049.pdf"〉Betrachtungen über ebene Pendel〈/a〉〈br〉(Hahnkamm, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0051.pdf"〉Außenraum und Innenraum (Schlichtung des Streites um die Schwerkraftreduktion)〈/a〉〈br〉(Schwinner, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0052.pdf"〉Bemerkungen zu den Geoiden von Ackerl und Hirvonen〈/a〉〈br〉(Ledersteger, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0053.pdf"〉Auto-Radio als Hilfsmittel geologischer Kartierung〈/a〉〈br〉(Cloos, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0054.pdf"〉Zur photographischen Registrierung von Stationsseismometern〈/a〉〈br〉(Meißer, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0056.pdf"〉Ein Horizontalseismometer für die Aufzeichnung von starken Orts- und Nahbeben〈/a〉〈br〉(Critikos, N. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0059.pdf"〉Die Bedeutung der Unstetigkeiten im Verlauf der Schallgeschwindigkeit mit der Höhe für die normale und anomale〈/a〉〈br〉(Sandmann, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0060.pdf"〉Referate und Mitteilungen〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0061.pdf"〉Die Relativität der Undulationen〈/a〉〈br〉(Hopfner, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0062.pdf"〉Ein detonierendes Meteor über dem Weserbergland am 2. Januar 1934〈/a〉〈br〉(Hartmann, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0063.pdf"〉Der Meteorfall bei Stadt Rehburg am 2. Januar 1934〈/a〉〈br〉(Trommsdorff, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0064.pdf"〉Vergleich zwischen der Intensität der kosmischen Ultrastrahlung über Grönland und über Deutschland〈/a〉〈br〉(Wölcken, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0065.pdf"〉Das Grundeis〈/a〉〈br〉(Jakuschoff, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0066.pdf"〉Le problème des microséismes et le déferlement des vagues〈/a〉〈br〉(Gherzi, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0067.pdf"〉Note on the Hayford-Bowie tables for calculation 〈i〉g〈/i〉〈/a〉〈br〉(Bullard, E. C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0068.pdf"〉Kann die Laplacesche Differentialgleichung für das Schwerkraftpotential auch innerhalb der Erdkruste als erfüllt angesehen werden?〈/a〉〈br〉(Grabowski, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0069.pdf"〉Vorträge, gehalten auf der XI. Tagung der Deutschen Geophysikalischen Gesellschaft, am 13. bis 15. September 1934 in Pyrmont〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0072.pdf"〉Der geophysikalische Nachweis des Zechsteindolomits〈/a〉〈br〉(Müller, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0073.pdf"〉Berichtigung〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0074.pdf"〉Vorträge, gehalten auf der XI. Tagung der Deutschen Geophysikalischen Gesellschaft, am 13. bis 15. September 1934 in Pyrmont〈/a〉〈br〉(von Seidlitz, W., Sieberg, A., Linke, F., Gerlach, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0079.pdf"〉Zur Frage der Geländekorrektion bei Drehwaagemessungen〈/a〉〈br〉(Tuchel, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0080.pdf"〉Emanation in Boden- und Freiluft〈/a〉〈br〉(Israël, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0081.pdf"〉Die Energie der Heliokathodenstrahlen in ihrer Beziehung zur fortschreitenden Bewegung der Elektronen in den Polarlichtstrahlen〈/a〉〈br〉(Rudolph, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0082.pdf"〉Weitere Untersuchungen mit dem Sanford-Elektrometer〈/a〉〈br〉(Stoppel, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0083.pdf"〉Das Strömungssystem der Luft über Mogadischu〈/a〉〈br〉(Bossolasco, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0084.pdf"〉Messungen mit transportablen statischen Schweremessern〈/a〉〈br〉(Schleusener, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0086.pdf"〉Über den Energietransport bei der Sprengseismik〈/a〉〈br〉(v. Schmidt, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0087.pdf"〉Formen der Bodenschwingung bei sinusförmiger Anregung〈/a〉〈br〉(Köhler, R.)〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0088.pdf"〉Die Ausbreitungsgeschwindigkeit sinusförmiger elastischer Wellen im Boden〈/a〉〈br〉(Ramspeck, A.)〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0089.pdf"〉Referate und Mitteilungen〈/a〉〈br〉(Haase, H.)〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0090.pdf"〉Bericht über die elfte Tagung der Deutschen Geophysikalischen Gesellschaft vom 13. bis 15. September 1934 in Bad Pyrmont〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0091.pdf"〉Berichtigung〈/a〉〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0092.pdf"〉Geophysikalische Berichte〈/a〉〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0093.pdf.pdf"〉Register der Geophysikalischen Berichte〈/a〉〈/li〉 〈li〉〈a href=" https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0010/LOG_0094.pdf"〉Mitgliederverzeichnis der Deutschen Geophysikalischen Gesellschaft nach dem Stande vom 1. Dezember 1934〈/a〉〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DGG, DFG, SUB Göttingen
    Keywords: 550 ; Geophysik ; Geomagnetismus ; Magnetismus ; Seismik ; Atmosphäre ; Gravitation ; Wellen ; Ionosphäre ; Strahlung ; Radioaktivität ; Erdbeben ; Waves ; Deformation ; Pendel ; Boden ; Deutschland ; Grönland ; FID-GEO-DE-7
    Language: German , English , French
    Type: anthology_digi
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  • 8
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    Jena G. Neuenhahn, G.m.b.H., Universitäts-Buchdruckerei
    In:  SUB Göttingen | 8 MIN III, 8552:3
    Publication Date: 2021-07-16
    Description: Deutschlands Erdbebentätigkeit pflegt unterschätzt zu werden, weil sie gewöhnlich so harmlos erscheint. Zwar bringt der Jahresverlauf nur wenige Beben, abgesehen von gelegentlichen Schwärmen mit vielen hunderten von Einzelstößen, wie sie besonders dem Vogtland eigentümlich sind. Zudem handelt es sich dabei vorwiegend um schadlose Erderschütterungen, die kaum Beobachtung finden. Aber der Fachmann kennt daneben auch bis in die neueste Zeit hinein Erdbeben mit erheblichen Schäden und selbst Zerstörungen, die für längere Zeit das öffentliche Leben völlig beherrscht haben; mitunter wurde fast Großbebencharakter erreicht.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 551.2 ; Seismologie {Geophysik} ; Wissenschaftsorganisation und -pflege {Geophysik} ; Erdbeben ; Seismologie ; Deutschland ; Schwarmbeben ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 12
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  • 9
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    Akad. Verl.-Ges., Leipzig
    In:  SUB Göttingenr | 8 MIN III, 8549:23
    Publication Date: 2021-03-29
    Description: Die nachstehenden neueren Untersuchungen auf verschiedenen Gebieten geophysikalischer Forschung, die von Mitgliedern der Reichsanstalt für Erdbebenforschung in Jena durchgeführt sind, wurden erstmalig in der Festschrift zum 70. Geburtstage des früheren Direktors der Reichsanstalt, Herrn Geheimrat Professor Dr. Oskar Hecker (Beitrage zur Angewandten Geophysik, Band 4, Heft 3, Leipzig 1934) veröffentlicht. Sämtliche Arbeiten, ausgenommen diejenigen von Krumbach, gehören zu den von der Notgemeinschaft der Deutschen Wissenschaft unterstützten geophysikalischen Forschungen. A. Sieberg
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 551.22 ; Geophysik ; Seismologie {Geophysik} ; Deutschland ; Seismik ; Pendel ; Schweremessung ; Erdbeben ; FID-GEO-DE-7
    Language: German
    Type: anthology_digi
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  • 10
    Publication Date: 2021-03-29
    Description: Abstract: Peatlands are intensively exchanging greenhouse gases with the free atmosphere. Natural peatlands, mires, sequester carbon dioxide as carbon in the peat and emit methane. Peatlands under agriculture or forest are mostly drained and emit carbon dioxide due to peat mineralization and nitrous oxide due to fertilization and nitrogen mineralization. In order to characterize the actual situation and to evaluate measures for the reduction of greenhouse gas emissions measured values on gas exchange are needed. Within two national projects direct measurements of the greenhouse gas exchange have been conducted on a wide range of sites, covering different peatland types, land use forms and hydrological situations and using a standardized methodology. Between 2007 and 2012 22 sites have been studied in Lower Saxony over at least two years using the closed cover method. An overview on sites and results is given. Moreover, approaches to estimate the greenhouse gas emissions due to peat excavation and horticultural peat use are presented. Own emission factors and data from literature are used to estimate the contribution of peatlands and peat use to the greenhouse gas emissions of Lower Saxony. Finally measures for the reduction of greenhouse gas emissions are discussed and estimates on reduction costs are given from examples.
    Description: Zusammenfassung: Moore stehen in einem intensiven Gasaustausch mit der Atmosphäre. Natürliche Moore haben über Jahrtausende Kohlendioxid aufgenommen und den Kohlenstoff als Torf gespeichert. Dabei haben sie Methan abgegeben. Entwässerte und genutzte Moore setzen den Kohlenstoff als Kohlendioxid wieder frei und emittieren zudem klimarelevantes Lachgas als Ergebnis der Stickstoffdüngung und der Torfmineralisation. Zur Charakterisierung der Ist-Situation und zur Beurteilung von Maßnahmen ist es erforderlich, belastbare Daten über die Treibhausgasemissionen der Moore zu haben. Im Rahmen von zwei bundesweit angelegten Verbundvorhaben wurden an einer Vielzahl von Standorten unterschiedlichen Moortyps, unterschiedlicher Nutzung und unterschiedlicher Klima- und Wasserregime mit einer abgestimmten Methodik die Flüsse der wesentlichen Treibhausgase direkt gemessen. Im Rahmen dieser Verbundvorhaben wurden in Niedersachsen zwischen 2007 und 2012 an 22 Standorten mindestens zweijährige Messungen mit der Haubentechnik vorgenommen. Dieser Beitrag gibt einen Überblick über untersuchte Standorte und Messergebnisse. Darüber hinaus werden Ansätze zur Ermittlung der Treibhausgasemissionen aus der industriellen Torfgewinnung dargestellt. Unter Verwendung eigener Ergebnisse und von Literaturdaten wird eine Abschätzung der Treibhausgasemissionen aus Moor und Torfgewinnung für das Land Niedersachsen vorgenommen. Abschließend geht der Beitrag auf Maßnahmen zur Verminderung der Treibhausgasemissionen aus Mooren sowie beispielhaft auf Emissionsminderungskosten ein.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; mire ; peatland ; emission ; CO2 ; N2O ; Germany ; Deutschland ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
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  • 11
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    Inst. für Phys. Geogr., Freie Univ., Berlin
    In:  Herausgeberexemplar (FU Berlin) | ZB 20559:36
    Publication Date: 2021-03-29
    Description: STÄBLEIN, G.: Regionale Geomorphologie ; KERTESZ, A.: Geomorphologische Kartierung in der Bundesrepublik Deutschland und in Ungarn. Ein Vergleich der Methodik ; BOLLMANN, I.: Geomorphologische Daten und kartographische Darstellung ; PACHUR, H.-J. & RÖPER, H.-P.: Geolimnologische Befunde des Berliner Raumes ; REMMELE, G.: Holozäne Morphodynamik an Schichtstufenhängen — Untersuchungen in Nordwest-Irland ; MÜLLER, MJ. & STRASSER, R.: Holozäne Geomorphodynamik und Landschaftsentwicklung am Ostrand der Trier-Luxemburger Mulde ; KLEBER, A.: Zur jungtertiären Reliefentwicklung im Vorland der südlichen Frankenalb ; HAMANN, C.: Windwurf als Ursache der Bodenbuckelung am Südrand des Tennengebirges, ein Beitrag zur Genese der Buckelwiesen ; ZÖLLER, L.: Neotektonik am Hunsrückrand ; SEPPÄLÄ, M.: Glazialhydrologie des Inlandeises, eine geomorphologische Interpretation der Verhältnisse in Finnland ; JÄKEL, D.: Untersuchungen und Analysen zur Entstehung der Hamada ; GARLEFF, K. & STINGL, H.: Neue Befunde zur jungquartären Vergletscherung in Cuyo und Patagonien ; STINGL, H. & GARLBFF, K.: Tertiäre und pleistozäne Reliefentwicklung an der interozeanischen Wasserscheide in Südpatagonien (Gebiet von Rio Turbio, Argentinien) ; SCHMIDT, K.H.: Nachweis junger Krustenbewegungen auf dem Colorado Plateau, USA ; KUHLE, M.: Zur Geomorphologie Tibets, Bortensander als Kennformen semiarider Vorlandvergletscherung . ; STÄBLEIN, G.: Deutscher Arbeitskreis für Geomorphologie ;
    Description: research
    Description: DFG, SUB Göttingen, FU Berlin
    Keywords: 550 ; 910.02 ; Geomorphologie ; Kartierung ; Holocene ; Irland ; Hunsrück ; Frankenalb ; Finnland ; Hamada ; Patagonien ; Cuyo ; Colorado ; Tektonik ; Gletscher ; glacier ; Tibet ; Deutschland ; Sahara ; Tibesti ; Darfur ; Sudan ; Libyen ; FID-GEO-DE-7
    Language: German
    Type: anthology_digi
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  • 12
    Publication Date: 2021-03-29
    Description: Abstract: In addition to the widespread use of peatlands for agricultural purposes, which is also common in other German states, the raised bogs in Lower Saxony are still also used up to the present day for housing, as well as for industrial peat extraction. The Peatland Conservation Programme in Lower Saxony launched in 1981 therefore only covered raised bogs to disentangle the different uses, and to systematise the nature protection activities in raised bogs. The priority areas for the extraction of peat defined in the Federal State Regional Planning Programme are to be rescinded. The new State Development Programme being formulated will not only include the nature conservation of peatlands, but also for the first time, deal with the climate protection afforded by these very important storage areas for carbon. An important aspect in this regard is the incorporation of fens, and the discharge from peatlands into underlying water bodies. The database and the conclusions which contribute to the implementation of climate protection in peatland conservation programmes, will be discussed and compared with the peatland conservation previously implemented pursuant to the Peatland Conservation Programme in Lower Saxony. An overview describes various approaches for peatland and climate protection implemented by private initiatives, nature conservation societies, EU-Life-Projects, contractual nature protection, publicly owned businesses and authorities in Lower Saxony, research projects on alternative uses, and climate certificate trading. These varied instruments are compared to highlight their relative areal effectiveness, and relevance, followed by an estimate of the potential for future peatland and climate protection in Lower Saxony.
    Description: Zusammenfassung: Neben der auch in anderen Bundesländern weit verbreiteten landwirtschaftlichen Nutzung von Mooren werden die niedersächsischen Hochmoore bis heute auch als Siedlungsraum und zur industriellen Torfgewinnung genutzt. Daher umfasste das niedersächsische Moorschutzprogramm von 1981 nur die Hochmoore, um diese verschiedenen Nutzungen zu entflechten und den Naturschutz in Hochmooren zu systematisieren. Die bisher im Landesraumordnungsprogramm ausgewiesenen Vorranggebiete für die Rohstoffgewinnung von Torf sollen gestrichen werden. In ein neu aufzustellendes Landesentwicklungsprogramm soll neben dem Naturschutz von Mooren erstmalig auch der Klimaschutz dieser wichtigen Kohlenstoffspeicher eingehen. Von besonderer Bedeutung sind hierbei die Einbeziehung der Niedermoore und der Stoffaustrag aus Mooren in unterliegende Gewässer. Die Datengrundlagen und Schlussfolgerungen, die zur Implementierung des Klimaschutzes in den Moorschutz beitragen, werden diskutiert und mit dem bisher umgesetzten Moorschutz nach dem niedersächsischen Moorschutzprogramm verglichen. Ein Überblick beschreibt verschiedene Ansätze zum Moor- und Klimaschutz von Privatinitiativen, von Naturschutzverbänden, mit EU-Life-Projekten, im Vertragsnaturschutz, von niedersächsischen Landesbetrieben und Behörden, von Forschungsprojekten zu alternativen Nutzungen und beim Handel mit Klima-Zertifikaten. Diese unterschiedlichen Instrumente werden in ihrer Flächenwirksamkeit und Relevanz in Beziehung gesetzt und das Potenzial für den künftigen Moor- und Klimaschutz in Niedersachsen abgeschätzt.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; peatland ; mire ; nature conservation ; Germany ; Deutschland ; emission ; bog ; Niedersachsen ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
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  • 13
    Publication Date: 2021-03-29
    Description: Am Beispiel des "Leegmoores" im Timpemoor - einem ehemaligen "Heidemoor" - wurde auf Grund von boden- und moorkundlichen Untersuchungen sowie von landeskundlich-historischen Recherchen die Entwicklung der Heidemoore überprüft. Dazu wurden erstmalig die flächenhaften Verluste an Moorsubstanz durch - wiederholte Moorbrandkultur, - Entnahme von Heidesoden (Abplaggen) und - Winderosion qualitativ und quantitativ erfaßt, dazu die Moorsackung errechnet. Aus den vorhandenen moorkundlichen Fakten konnte das natürliche Moorrelief des Timpemoores rekonstruiert werden. Die Autoren weisen nach, daß die von JONAS (1934, 1935) beschriebenen Heidemoore "durch den Menschen beeinflußte Moore" darstellen. Das untersuchte Timpemoor hat sich danach im Verlauf mehrerer Jahrhunderte aus einem natürlichen gewölbten Hochmoor gebildet.
    Description: On the basis of pedological, peatland and historical investigations the origin of raised bogs with heather vegetation ("Heidemoore")was examined at the example "Leegmoor", a part of the "Timpemoor". In addition to that for the first time the loss of peat substance by - burnt-over peatland cultivation, - cutaway heather sods, - erosion by wind and - bog subsidence was calculated. With the available peatland facts it was possible to reconstruct the natural bog relief. The authors are able to demonstrate that the "Heidemoore" described by JONAS (1934, 1935) are bogs influenced by man. During the last centuries the Timpemoor developed from a natural raised bog (with convex centre) to a raised bog with heather vegetation.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 553.21 ; bog ; Deutschland ; Germany ; Hochmoor ; land-use ; mire ; Moor ; Niedersachsen ; palaeoenvironment ; peat mining ; peatland ; Torfabbau ; FID-GEO-DE-7
    Language: German
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  • 14
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    Reimer, Berlin
    In:  Herausgeberexemplar (FU Berlin) | 4 Z GEOGR 107:3
    Publication Date: 2021-03-29
    Description: Vergleichende Darstellung und Analyse der Arbeitsvorgänge in den Agrarlandschaften der Erde. Dieser Aufgabe unterzieht sich in einem ersten Schritt die vorliegende Studie. Sie strebt an, mit der Darstellung und Analyse des jährlichen Arbeitsvorganges die bisher wenig berücksichtigte dynamische Seite der Agrarlandschaft – ihre Rhythmik nämlich – in exakter Weise erfassen zu können. Im Vordergrund steht zunächst weniger die regionale als vielmehr die sachliche Erörterung, auf der Beispielsgrundlage jedoch einer regionalen Kontrastierung innerhalb Deutschlands bzw. aus naheliegenden Gründen der Bundesrepublik Deutschland. Späteren großräumigen Untersuchungen erst kann es vorbehalten sein, von der hier geschaffenen Plattform aus auf eine speziell regionale Betrachtungsweise überzugehen.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 910 ; Kulturgeographie der Bundesrepublik Deutschland ; Agrar- und Forstgeographie {Wirtschaftsgeographie} ; Agrarlandschaft ; Arbeitsvorgang ; Deutschland ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 129
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  • 15
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    Gustav Fischer Verlag Jena
    In:  SUB Göttingen | 8 MIN III, 8549:12
    Publication Date: 2021-03-29
    Description: An der Hand von Erdbeben, die im Boden Deutschlands entstanden sind, sollen folgende Fragen untersucht werden: 1) Die Wirkungsweise der einzelnen Bebenherde, von denen anzunehmen ist, dass sie verschiedenartige Charaktereigenschaften haben. Hierfür ist es notwendig, festzustellen einmal Lage und geometrisches Bild des Herdes als geologische Störungsstelle, andererseits den das Erdbeben auslösenden Bewegungsvorgang in der Herdstörung. 2) Die Abhängigkeit der scheinbaren Bebenstarken innerhalb des Schüttergebietes von Bodenbeschaffenheit und Tektonik.
    Description: research
    Description: DFG, SUB Göttingen
    Keywords: 551.22 ; Europa {Seismologie} ; Deutschland {Geophysik} ; Erdbeben ; Deutschland ; Tektonik ; geol ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 44
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  • 16
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    Friedr. Vieweg & Sohn, Braunschweig
    In:  SUB Göttingen | 8 GEOGR PHYS 203
    Publication Date: 2021-03-29
    Description: Dieser Band enthält 77 Beiträge zu Themengebieten der Physik der festen Erde, des magnetischen und elektrischen Felds der Erde, der Physik der Atmosphäre sowie der Angewandten Geophysik, veröffentlicht durch die Deutsche Geophysikalische Gesellschaft in den Jahren 1930.
    Description: 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0004.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0005.pdf"〉Ein neuer Vierpendelapparat für relative Schweremessungen〈/a〉〈br〉(Meisser, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0007.pdf"〉Geophysikalische Messungen unter Tage〈/a〉〈br〉(Meisser, O., Wolf, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0008.pdf"〉Die ersten Dickenmessungen des grönländischen Inlandeises〈/a〉〈br〉(Sorge, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0010.pdf"〉Die seismische Bodenunruhe in Hamburg und ihr Zusammenhang mit der Brandung〈/a〉〈br〉(Mendel, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0012.pdf"〉Die sonnenbelichteten Nordlichtstrahlen und die Konstitution der höheren Atmosphärenschichten〈/a〉〈br〉(Vegard, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0013.pdf"〉Nochmals: Zur Frage der Laufzeitkurven〈/a〉〈br〉(Gutenberg, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0014.pdf"〉Erwiderung zur vorstehenden Arbeit von Herrn Prof. Gutenberg〈/a〉〈br〉(Krumbach, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0015.pdf"〉Bemerkungen zu der vorstehenden Erwiderung〈/a〉〈br〉(Gutenberg, B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0016.pdf"〉Einfluß des Mondes auf die erdmagnetischen Elemente in Samoa〈/a〉〈br〉(Fanselau, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0017.pdf"〉Ein Diagramm zur Bestimmung der Differenz der Schwerestörung 〈i〉Δg〈/i〉 in zwei Beobachtungspunkten〈/a〉〈br〉(Oserezky, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0018.pdf"〉Zur Ermittlung ausgedehnter Schichten verschiedener Leitfähigkeit〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0019.pdf"〉Über tägliche erdmagnetische Variationen in zwei Alpentälern〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0020.pdf"〉Die Wirkung der obersten Erdschicht auf die Anfangsbewegung einer Erdbebenwelle〈/a〉〈br〉(Hasegawa, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0021.pdf"〉Über die Elastizität von Gesteinen〈/a〉〈br〉(Breyer, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0023.pdf"〉Über den Horizontalabstand von Pendelstationen〈/a〉〈br〉(Schwinner, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0024.pdf"〉Die Belowsche Methode zur Bestimmung der Wirkung gegebener Massen auf Krümmungsgröße und Gradient, ihre Verallgemeinerung für beliebige Massenformen und ihre Anwendung auf "zweidimensionale" Massenanordnungen〈/a〉〈br〉(Jung, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0028.pdf"〉Harmonische Schwingungen des Untergrundes〈/a〉〈br〉(Köhler, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0029.pdf"〉Mitteilungen〈/a〉〈br〉(Fleming, I. A., Linke, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0030.pdf"〉Über die Ursache der erdmagnetischen Störung im Gebiet der Freien Stadt Danzig〈/a〉〈br〉(Haalck, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0031.pdf"〉Die kontinentalen Verschiebungen von Amerika und Madagaskar〈/a〉〈br〉(Livländer, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0032.pdf"〉Magnetische Vermessung einiger tertiärer Eruptivgänge und -stöcke im sächsischen Elbsandsteingebirge〈/a〉〈br〉(Schulze, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0033.pdf"〉Über die Existenz einer mondentägigen Variation in den Erdströmen〈/a〉〈br〉(Egedal, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0034.pdf"〉Zum Trübungsfaktor〈/a〉〈br〉(Feussner, K., Friedrichs, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0035.pdf"〉Temperature changes between Torsion balance readings in the State of Texas〈/a〉〈br〉(Harris, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0036.pdf"〉Über isostatische Schwereanomalien und deren Beziehung zu den totalen Anomalien〈/a〉〈br〉(Jung, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0037.pdf"〉Bemerkungen zu den Ausführungen von H. Jung〈/a〉〈br〉(Ansel, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0038.pdf"〉Mitteilungen〈/a〉〈br〉(Linke, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0040.pdf"〉Wesensgleiche und wesensverschiedene Darstellungen〈/a〉〈br〉(Nippoldt, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0041.pdf"〉Die Säkularvariation in der Rheinpfalz in den Jahren 1850 bis 1928〈/a〉〈br〉(Burmeister, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0042.pdf"〉Größenverhältnis von remanentem zu induziertem Magnetismus in Gesteinen; Größe und Richtung des remanenten Magnetismus〈/a〉〈br〉(Koenigsberger, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0043.pdf"〉Über eine magnetische Anomalie am Lebasee in Ostpommern〈/a〉〈br〉(Reich, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0045.pdf"〉Die Ergebnisse der magnetischen Messungen in der Ostsee in den Jahren 1924 bis 1929〈/a〉〈br〉(v. Gernet-Reval, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0047.pdf"〉Erdmagnetische Messungen in Bulgarien, Mazedonien, Trazien und in der Dobrudja〈/a〉〈br〉(Popoff, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0048.pdf"〉Einige Bemerkungen über erdmagnetische Messungen, welche in Feodossia ausgeführt wurden〈/a〉〈br〉(Palazzo, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0049.pdf"〉Possible causes of abnormal polarizations of magnetic formations〈/a〉〈br〉(Heiland, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0050.pdf"〉Die geologische Bedeutung der Schaffung einer Isanomalenkarte der magnetischen Vertikalintensität von Deutschland〈/a〉〈br〉(Schuh, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0051.pdf"〉Die innere Genauigkeit von Inklinationsmessungen mit dem Erdinduktor〈/a〉〈br〉(Venske, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0052.pdf"〉Theorie einer neuen galvanischen Waage〈/a〉〈br〉(Bock, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0053.pdf"〉Messungen im Luftschiff〈/a〉〈br〉(Haussmann, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0054.pdf"〉Une modification de l'enregistreur à marche rapide et à petite consommation de papier de Ad. Schmidt pour l'application aux stations de l'Anneé Polaire 1932–1933〈/a〉〈br〉(la Cour, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0056.pdf"〉Was sagen uns die Parameter eines Magneten?〈/a〉〈br〉(Fanselau, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0057.pdf"〉Über die Herleitung des Potentials des täglichen erdmagnetischen Variationsfeldes〈/a〉〈br〉(Egedal, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0058.pdf"〉Über den Vektor der magnetischen Störungen im aperiodischen Verlauf〈/a〉〈br〉(Keränen, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0059.pdf"〉Forschungsmethode über den Zusammenhang zwischen der Sonnenfleckentätigkeit und den erdmagnetischen Störungen〈/a〉〈br〉(Gehlinsch, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0060.pdf"〉Der Temperaturverlauf im Sandboden〈/a〉〈br〉(Süring, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0061.pdf"〉Die dominierende Luftdruckwelle des strengen Winters 1928/29〈/a〉〈br〉(Weickmann, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0063.pdf"〉Über einige meteorologische Begriffe〈/a〉〈br〉(Tetens, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0066.pdf"〉Über die Feinstruktur des Temperaturgradienten längs Berghängen〈/a〉〈br〉(Wagner, A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0067.pdf"〉Das unperiodische Element im Tropenklima〈/a〉〈br〉(Knoch, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0068.pdf"〉Zur Theorie der Maxwellschen Geschwindigkeitsverteilung in turbulenten Strömungen〈/a〉〈br〉(Ertel, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0069.pdf"〉Wie tief dringen die Polarlichter in die Erdatmosphäre ein?〈/a〉〈br〉(Störmer, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0072.pdf"〉Gammastrahlen an Kaliumsalzen〈/a〉〈br〉(Kolhörster, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0073.pdf"〉Über die Form der Fernschallwelle〈/a〉〈br〉(Kühl, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0074.pdf"〉Die Seismizität des Südantillenbogens〈/a〉〈br〉(Tams, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0076.pdf"〉Eine neue württembergische Erdbebenwarte〈/a〉〈br〉(Kleinschmidt, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0077.pdf"〉Über den Zusammenhang zwischen Typhusmorbidität (bzw. Typhusmortalität) und Niederschlagsschwankungen nebst einer Kritik der Brücknerschen Klimaperiode〈/a〉〈br〉(Wenzel Pollak, L.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0079.pdf"〉Über die Abhängikeit der Schwerkraft vom Zwischenmedium〈/a〉〈br〉(Schlomka, T.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0080.pdf"〉On the Determination of the Lunar Atmospheric Tide〈/a〉〈br〉(Chapman, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0081.pdf"〉Die Wärmeumsatz durch die Wärmestrahlung des Wasserdampfes in der Atmosphäre〈/a〉〈br〉(Albrecht, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0082.pdf"〉Ein Universal-Induktionsmagnetometer〈/a〉〈br〉(Uljanin, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0083.pdf"〉Der große Staubfall vom 26. bis 29. April 1928 in Südosteuropa〈/a〉〈br〉(Stenz, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0085.pdf"〉Ein neues Verfahren der luftelektrischen Raumladungsmessung〈/a〉〈br〉(Wigand, A., Schubert, J., Frankenberger, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0086.pdf"〉Kurze Erwiderung auf Vegards Bemerkungen über sonnenbelichtete Nordlichtstrahlen〈/a〉〈br〉(Störmer, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0088.pdf"〉Die Invariabilität und Abstimmung von Minimumpendeln〈/a〉〈br〉(Kohlschütter, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0089.pdf"〉Bemerkung zu der Arbeit "Die Invariabilität und Abstimmung von Minimumpendeln" von E. Kohlschütter〈/a〉〈br〉(Meisser, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0090.pdf"〉Erwiderung〈/a〉〈br〉(Kohlschütter, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0091.pdf"〉Bemerkungen zu der Arbeit von Herrn Dr. O. Meisser: "Ein neuer Vierpendelapparat für relative Schweremessungen"〈/a〉〈br〉(Heiland, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0092.pdf"〉Bemerkungen zu den vorstehenden Ausführungen von Herrn Prof. Dr. C. A. Heiland〈/a〉〈br〉(Meisser, O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0093.pdf"〉Das Epizentrum des südatlantischen Großbebens vom 27. Juni 1929〈/a〉〈br〉(Tams, E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0094.pdf"〉Seismische Untersuchungen auf dem Pasterzegletscher. I〈/a〉〈br〉(Brockamp, B., Mothes, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0096.pdf"〉Bericht über die neunte Tagung der Deutschen Geophysikalischen Gesellschaft vom 11. bis 14. September 1930 in Potsdam〈/a〉〈br〉(Mügge, Linke, F.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0097.pdf"〉Autorenverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0098.pdf"〉Sachverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0099.pdf"〉Literaturverzeichnis〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0100.pdf"〉Geophysikalische Berichte〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0101.pdf"〉Register der Geophysikalischen Berichte〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN101433392X_0006/LOG_0102.pdf"〉Mitgliederverzeichnis der Deutschen Geophysikalischen Gesellschaft nach dem Stande vom 1. Oktober 1930〈/a〉〈/li〉 〈/body〉 〈/html〉
    Description: research
    Description: DGG, DFG, SUB Göttingen
    Keywords: 550 ; Geophysik ; Physische Geografie ; Atmosphäre ; Aurora ; Deutschland ; Erdbeben ; Geoelektrik ; Geologie ; Geomagnetismus ; Gravimetrie ; Gravitation ; Ionosphäre ; Magnetismus ; Pendel ; Seismik ; Tiden ; USA ; FID-GEO-DE-7
    Language: German , English , French
    Type: anthology_digi
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 590-599 
    ISSN: 0006-3592
    Keywords: protein refolding ; hollow-fibre membrane ; dialysis ; carbonic anhydrase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have used a cellulose acetate, hollow-fibre (HF) ultrafiltration membrane to refold bovine carbonic anhydrase, loaded into the lumen space, by removing the denaturant through controlled dialysis via the shell side space. When challenged with GdnHCl-denatured carbonic anhydrase, 70% of the loaded protein reptated through the membrane into the circulating dialysis buffer. Reptation occurred because the protein, in its fully unfolded configuration, was able to pass through the pores. The loss of carbonic anhydrase through the membrane was controlled by the dialysis conditions. Dialysis against 0.05 M Tris-HCl for 30 min reduced the denaturant around the protein to a concentration that allowed the return of secondary structure, increasing the hydrodynamic radius, thus preventing protein transmission. Under these conditions a maximum of 42% of carbonic anhydrase was recovered (from a starting concentration of 5 mg/mL) with 94% activity. This is an improvement over refolding carbonic anhydrase by simple batch dilution, which gave a maximum reactivation of 85% with 35% soluble protein yield. The batch refolding of carbonic anhydrase is very sensitive to temperature; however, during HF refolding between 0 and 25°C the temperature sensitivity was considerably reduced. In order to reduce the convection forces that give rise to aggregation and promote refolding the dialyzate was slowly heated from 4 to 25°C. This slow, temperature-controlled refolding gave an improved soluble protein recovery of 55% with a reactivation yield of 90%. The effect of a number of additives on the refolding system performance were tested: the presence of PEG improved both the protein recovery and the recovered activity from the membrane, while the detergents Tween 20 and IGEPAL CA-630 increased only the refolding yield. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 590-599, 1998.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 119-120 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 658-662 
    ISSN: 0006-3592
    Keywords: T4 lysozyme ; silica nanoparticles ; synthetic enzyme variants ; surface-induced conformational change ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Maintaining a specific molecular conformation is essential for the proper functioning of an enzyme. A substantial loss of catalytic activity can occur from the displacement caused by even a single amino acid substitution. Activity may also be lost as an enzyme undergoes a conformational change during adsorption. In this study, we investigated the effect of thermostability on the activities of three T4 lysozyme variants after adsorption to 9 nm colloidal silica particles. Less-stable T4 lysozyme variants lost more activity after adsorption than did more stable variants, apparently because they experienced more extensive structural alteration. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58: 658-662, 1998.
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    Biotechnology and Bioengineering 58 (1998), S. 139-148 
    ISSN: 0006-3592
    Keywords: metabolic engineering ; pathway analysis ; metabolic and energetic model ; physiological state ; Saccharomyces cerevisiae ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work, an integrated modeling approach based on a metabolic signal flow diagram and cellular energetics was used to model the metabolic pathway analysis for the cultivation of yeast on glucose. This approach enables us to make a clear analysis of the flow direction of the carbon fluxes in the metabolic pathways as well as of the degree of activation of a particular pathway for the synthesis of biomaterials for cell growth. The analyses demonstrate that the main metabolic pathways of Saccharomyces cerevisiae change significantly during batch culture. Carbon flow direction is toward glycolysis to satisfy the increase of requirement for precursors and energy. The enzymatic activation of TCA cycle seems to always be at normal level, which may result in the overflow of ethanol due to its limited capacity. The advantage of this approach is that it adopts both virtues of the metabolic signal flow diagram and the simple network analysis method, focusing on the investigation of the flow directions of carbon fluxes and the degree of activation of a particular pathway or reaction loop. All of the variables used in the model equations were determined on-line; the information obtained from the calculated metabolic coefficients may result in a better understanding of cell physiology and help to evaluate the state of the cell culture process. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:139-148, 1998.
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  • 21
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    Biotechnology and Bioengineering 58 (1998), S. 149-153 
    ISSN: 0006-3592
    Keywords: Metabolic Control Analysis ; flux control coefficients ; top down MCA ; metabolic engineering ; Corynebacterium glutamicum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Grouping of reactions around key metabolite branch points can facilitate the study of metabolic control of complex metabolic networks. This top-down Metabolic Control Analysis is exemplified through the introduction of group (flux, as well as concentration) control coefficients whose magnitudes provide a measure of the relative impact of each reaction group on the overall network flux, as well as on the overall network stability, following enzymatic amplification. In this article, we demonstrate the application of previously developed theory to the determination of group flux control coefficients. Experimental data for the changes in metabolic fluxes obtained in response to the introduction of six different environmental perturbations are used to determine the group flux control coefficients for three reaction groups formed around the phosphoenolpyruvate/pyruvate branch point. The consistency of the obtained group flux control coefficient estimates is systematically analyzed to ensure that all necessary conditions are satisfied. The magnitudes of the determined control coefficients suggest that the control of lysine production flux in Corynebacterium glutamicum cells at a growth base state resides within the lysine biosynthetic pathway that begins with the PEP/PYR carboxylation anaplorotic pathway. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:149-153, 1998.
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  • 22
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    Biotechnology and Bioengineering 58 (1998), S. 154-161 
    ISSN: 0006-3592
    Keywords: central carbon pathways ; metabolic optimization ; ethanol production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many attempts to engineer cellular metabolism have failed due to the complexity of cellular functions. Mathematical and computational methods are needed that can organize the available experimental information, and provide insight and guidance for successful metabolic engineering. Two such methods are reviewed here. Both methods employ a (log)linear kinetic model of metabolism that is constructed based on enzyme kinetics characteristics. The first method allows the description of the dynamic responses of metabolic systems subject to spatiotemporal variations in their parameters. The second method considers the product-oriented, constrained optimization of metabolic reaction networks using mixed-integer linear programming methods. The optimization framework is used in order to identify the combinations of the metabolic characteristics of the glycolytic enzymes from yeast and bacteria that will maximize ethanol production. The methods are also applied to the design of microbial ethanol production metabolism. The results of the calculations are in qualitative agreement with experimental data presented here. Experiments and calculations suggest that, in resting Escherichia coli cells, ethanol production and glucose uptake rates can be increased by 30% and 20%, respectively, by overexpression of a deregulated pyruvate kinase, while increase in phosphofructokinase expression levels has no effect on ethanol production and glucose uptake rates. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:154-161, 1998.
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    Biotechnology and Bioengineering 58 (1998), S. 170-174 
    ISSN: 0006-3592
    Keywords: catabolite repression ; phosphotransferase system ; inducer exclusion ; inducer expulsion ; protein kinase ; transcriptional regulation ; transport regulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Catabolite repression is a universal phenomenon, found in virtually all living organisms. These organisms range from the simplest bacteria to higher fungi, plants, and animals. A mechanism involving cyclic AMP and its receptor protein (CRP) in Escherichia coli was established years ago, and this mechanism has been assumed by many to serve as the prototype for catabolite repression in all organisms. However, recent studies have shown that this mechanism is restricted to enteric bacteria and their close relatives. Cyclic AMP-independent mechanisms of catabolite repression occur in other bacteria, yeast, plants, and even E. coli. In fact, single-celled organisms such as E. coli, Bacillus subtilis, and Saccharomyces cerevisiae exhibit multiple mechanisms of catabolite repression, and most of these are cyclic AMP-independent. The mechanistic features of the best of such characterized processes are briefly reviewed, and references are provided that will allow the reader to delve more deeply into these subjects. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:170-174, 1998.
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    Biotechnology and Bioengineering 58 (1998), S. 162-169 
    ISSN: 0006-3592
    Keywords: bioinformatics ; metabolic engineering ; genetic engineering ; mathematical analysis ; stoichiometry ; enzyme kinetics ; modal analysis ; genetic circuits ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ten microbial genomes have been fully sequenced to date, and the sequencing of many more genomes is expected to be completed before the end of the century. The assignment of function to open reading frames (ORFs) is progressing, and for some genomes over 70% of functional assignments have been made. The majority of the assigned ORFs relate to metabolic functions. Thus, the complete genetic and biochemical functions of a number of microbial cells may be soon available. From a metabolic engineering standpoint, these developments open a new realm of possibilities. Metabolic analysis and engineering strategies can now be built on a sound genomic basis. An important question that now arises; how should these tasks be approached? Flux-balance analysis (FBA) has the potential to play an important role. It is based on the fundamental principle of mass conservation. It requires only the stoichiometric matrix, the metabolic demands, and some strain specific parameters. Importantly, no enzymatic kinetic data is required. In this article, we show how the genomically defined microbial metabolic genotypes can be analyzed by FBA. Fundamental concepts of metabolic genotype, metabolic phenotype, metabolic redundancy and robustness are defined and examples of their use given. We discuss the advantage of this approach, and how FBA is expected to find uses in the near future. FBA is likely to become an important analysis tool for genomically based approaches to metabolic engineering, strain design, and development. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:162-169, 1998.
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    Biotechnology and Bioengineering 58 (1998), S. 191-195 
    ISSN: 0006-3592
    Keywords: control analysis ; Lactococcus lactis ; gene expression ; flux ; oligonucleotide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this article, we review some of the expression systems that are available for Metabolic Control Analysis and Metabolic Engineering, and examine their advantages and disadvantages in different contexts. In a recent approach, artificial promoters for modulating gene expression in micro-organisms were constructed using synthetic degenerated oligonucleotides. From this work, a promoter library was obtained for Lactococcus lactis, containing numerous individual promoters and covering a wide range of promoter activities. Importantly, the range of promoter activities was covered in small steps of activity change. Promoter libraries generated by this approach allow for optimization of gene expression and for experimental control analysis in a wide range of biological systems by choosing from the promoter library promoters giving, e.g., 25%, 50%, 200%, and 400% of the normal expression level of the gene in question. If the relevant variable (e.g., the flux or yield) is then measured with each of these constructs, then one can calculate the control coefficient and determine the optimal expression level. One advantage of the method is that the construct which is found to have the optimal expression level is then, in principle, ready for use in the industrial fermentation process; another advantage is that the system can be used to optimize the expression of different enzymes within the same cell. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:191-195, 1998.
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    Biotechnology and Bioengineering 58 (1998), S. 175-190 
    ISSN: 0006-3592
    Keywords: protein-based polymers ; inverse temperature transitions ; hydrophobic-induced pKa shifts ; waters of hydrophobic hydration ; five axioms for protein engineering; microwave dielectric relaxation ; a universal mechanism for biological energy conversion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Metabolism is the conversion of available energy sources to those energy forms required for sustaining and propagating living organisms; this is simply biological energy conversion. Proteins are the machines of metabolism; they are the engines of motility and the other machines that interconvert energy forms not involving motion. Accordingly, metabolic engineering becomes the use of natural protein-based machines for the good of society. In addition, metabolic engineering can utilize the principles, whereby proteins function, to design new protein-based machines to fulfill roles for society that proteins have never been called upon throughout evolution to fulfill.This article presents arguments for a universal mechanism whereby proteins perform their diverse energy conversions; it begins with background information, and then asserts a set of five axioms for protein folding, assembly, and function and for protein engineering. The key process is the hydrophobic folding and assembly transition exhibited by properly balanced amphiphilic protein sequences. The fundamental molecular process is the competition for hydration between hydrophobic and polar, e.g., charged, residues. This competition determines Tt, the onset temperature for the hydrophobic folding and assembly transition, Nhh, the numbers of waters of hydrophobic hydration, and the pKa of ionizable functions.Reported acid-base titrations and pH dependence of microwave dielectric relaxation data simultaneously demonstrate the interdependence of Tt, Nhh and the pKa using a series of microbially prepared protein-based poly(30mers) with one glutamic acid residue per 30mer and with an increasing number of more hydrophobic phenylalanine residues replacing valine residues. Also, reduction of nicotinamides and flavins is shown to lower Tt, i.e., to increase hydrophobicity.Furthermore, the argument is presented, and related to an extended Henderson-Hasselbalch equation, wherein reduction of nicotinamides represents an increase in hydrophobicity and resulting hydrophobic-induced pKa shifts become the basis for understanding a primary energy conversion (proton transport) process of mitochondria. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:175-190, 1998.
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  • 27
    ISSN: 0006-3592
    Keywords: Escherichia coli ; Chloramphenicol Acetyltransferase (CAT) ; Culture Redox Potential (CRP) ; Dithiothreitol (DTT) ; reducing agents ; molecular chaperones ; proteases ; heat shock ; stress response ; protein folding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The independent control of culture redox potential (CRP) by the regulated addition of a reducing agent, dithiothreitol (DTT) was demonstrated in aerated recombinant Escherichia coli fermentations. Moderate levels of DTT addition resulted in minimal changes to specific oxygen uptake, growth rate, and dissolved oxygen. Excessive levels of DTT addition were toxic to the cells resulting in cessation of growth. Chloramphenicol acetyltransferase (CAT) activity (nmoles/μg total protein min.) decreased in batch fermentation experiments with respect to increasing levels of DTT addition. To further investigate the mechanisms affecting CAT activity, experiments were performed to assay heat shock protein expression and specific CAT activity (nmoles/μg CAT min.). Expression of such molecular chaperones as GroEL and DnaK were found to increase after addition of DTT. Additionally, sigma factor 32 (σ32) and several proteases were seen to increase dramatically during addition of DTT. Specific CAT activity (nmoles/μg CAT min.) varied greatly as DTT was added, however, a minimum in activity was found at the highest level of DTT addition in E. coli strains RR1 [pBR329] and JM105 [pROEX-CAT]. In conjunction, cellular stress was found to reach a maximum at the same levels of DTT. Although DTT addition has the potential for directly affecting intracellular protein folding, the effects felt from the increased stress within the cell are likely the dominant effector. That the effects of DTT were measured within the cytoplasm of the cell suggests that the periplasmic redox potential was also altered. The changes in specific CAT activity, molecular chaperones, and other heat shock proteins, in the presence of minimal growth rate and oxygen uptake alterations, suggest that the ex vivo control of redox potential provides a new process for affecting the yield and conformation of heterologous proteins in aerated E. coli fermentations. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 248-259, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 261-272 
    ISSN: 0006-3592
    Keywords: effective diffusive permeability ; diffusion coefficient ; biofilm ; cell density ; review ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental measurements of effective diffusive permeabilities and effective diffusion coefficients in biofilms are reviewed. Effective diffusive permeabilities, the parameter appropriate to the analysis of reaction-diffusion interactions, depend on solute type and biofilm density. Three categories of solute physical chemistry with distinct diffusive properties were distinguished by the present analysis. In order of descending mean relative effective diffusive permeability (De/Daq) these were inorganic anions or cations (0.56), nonpolar solutes with molecular weights of 44 or less (0.43), and organic solutes of molecular weight greater than 44 (0.29). Effective diffusive permeabilities decrease sharply with increasing biomass volume fraction suggesting a serial resistance model of diffusion in biofilms as proposed by Hinson and Kocher (1996). A conceptual model of biofilm structure is proposed in which each cell is surrounded by a restricted permeability envelope. Effective diffusion coefficients, which are appropriate to the analysis of transient penetration of nonreactive solutes, are generally similar to effective diffusive permeabilities in biofilms of similar composition. In three studies that examine diffusion of very large molecular weight solutes ( 〉 5000) in biofilms, the average ratio of the relative effective diffusion coefficient of the large solute to the relative effective diffusion coefficient of either sucrose or fluorescein was 0.64, 0.61, and 0.36. It is proposed that large solutes are effectively excluded from microbial cells, that small solutes partition into and diffuse within cells, and that ionic solutes are excluded from cells but exhibit increased diffusive permeability (but decreased effective diffusion coefficients) due to sorption to the biofilm matrix. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:261-272, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 281-285 
    ISSN: 0006-3592
    Keywords: protein aggregation ; RNase A ; protein formulation ; protein additives ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the previous study (part I), heat-denatured RNase A aggregation was shown to depend on the solution pH. Interestingly, at pH 3.0, the protein did not aggregate even when exposed to 75°C for 24 h. In this study, electrostatic repulsion was shown to be responsible for the absence of aggregates at that pH. While RNase A aggregation was prevented at the extremely acidic pH, this is not an environment conducive to maintaining protein function in general. Therefore, attempts were made to confer electrostatic repulsion near neutral pH. In this study, heat-denatured RNase A was mixed with charged polymers at pH 7.8 in an attempt to provide the protein with excess surface cations or anions. At 75°C, SDS and dextran sulfate were successful in preventing RNase A aggregation, whereas their cationic, nonionic, and zwitterionic analogs did not do so. We believe that the SO3- groups present in both additives transformed the protein into polyanionic species, and this may have provided a sufficient level of electrostatic repulsion at pH 7.8 and 75°C to prevent aggregation from proceeding. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:281-285, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 328-343 
    ISSN: 0006-3592
    Keywords: biotrickling filters ; biotrickling filter modeling ; mono-chlorobenzene ; biodegradation kinetics of mono-chlorobenzene ; chlorinated VOC emissions ; biofiltration ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of mono-chlorobenzene (m-CB) vapor from airstreams was studied in a biotrickling filter (BTF) operating under counter-current flow of the air and liquid streams. Experiments were performed under various values of inlet m-CB concentration, air and/or liquid volumetric flow rates, and pH of the recirculating liquid. Conversion of m-CB was never below 70% and at low concentrations exceeded 90%. A maximum removal rate of about 60 gm-3-reactor h-1 was observed. Conversion of m-CB was found to increase as the values of liquid and air flow rate increase and decrease, respectively. The effects of pH and frequency of medium replenishment on BTF performance were also investigated. The process was successfully described with a detailed mathematical model, which accounts for mass transfer and kinetic effects based on m-CB and oxygen availability. Solution of the model equations yielded m-CB and oxygen concentration profiles in all three phases (airstream, liquid, biofilm). It is predicted that oxygen has a controling effect on the process at high inlet m-CB concentrations. From independent, suspended culture, experiments it was found that m-CB biodegradation follows Andrews inhibitory kinetics. The kinetic constants were found to remain practically unchanged after the culture was used in BTF experiments for 8 months. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:328-343, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 344-350 
    ISSN: 0006-3592
    Keywords: electrodialysis ; citric acid ; pH ; temperature ; Faraday efficiency ; solute recovery efficiency ; specific energy consumption ; solute flux ; water flux ; feed solute concentration ; electric current density ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of pH and temperature (θ) on the overall performance indicators (i.e., solute recovery, ρ, and Faraday, η, efficiencies; specific energy consumption, ε, solute, JS, and water, JW, fluxes) of batch electrodialytic recovery of citric acid from model solutions was assessed at different values of feed solute concentration (cSf) and electric current density (j). Regardless of the initial feed concentration used, ρ and JS were found to be independent of θ; η and JW exhibited a positive trend with respect to θ, while ε a negative one. At the maximum temperature tested (33°C), as the pH of the feed solution was varied from 3 to 7, ρ increased from 0.90 ± 0.08 to 0.97 ± 0.02, η grew from 0.09 ± 0.02 to 0.50 ± 0.01, JS practically doubled, ε reduced about 8 times, but JW increased from 3 to 4 times. So, the optimal conditions for this technique are to be determined by balancing the savings in the investment and maintenance costs against the energy costs. © John Wiley & Sons, Inc. Biotechnol Bioeng 59:344-350, 1998.
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    ISSN: 0006-3592
    Keywords: chymotrypsin ; enzyme stability ; reversed micelles ; interface ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The stability of α-chymotrypsin and δ-chymotrypsin was studied in reversed micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in isooctane. α-Chymotrypsin is inactivated at the interface and at the water pool, while δ-chymotrypsin is inactivated only at the water pool. The mechanism of inactivation at the interface is related to the interaction of N-terminal group alanine 149 (absent in δ-chymotrypsin) with the negative interface. The dependence of enzyme activity on water content of these two enzymes in reversed micelles of AOT is also related with the interface interaction, since δ-chymotrypsin does not have a bell-shaped curve as observed for α-chymotrypsin. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:360-363, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 351-359 
    ISSN: 0006-3592
    Keywords: bioreactor ; high density ; insect cells ; perfusion ; Sf9 ; ultrasonic filter ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The baculovirus/insect cell expression system has provided a vital tool to produce a high level of active proteins for many applications. We have developed a very high-density insect cell perfusion process with an ultrasonic filter as a cell retention device. The separation efficiency of the filter was studied under various operating conditions. A cell density of over 30 million cells/mL was achieved in a controlled perfusion bioreactor and cell viability remained greater than 90%. Sf9 cells from a high-density culture and a spinner culture were infected with two recombinant baculoviruses expressing genes for the production of human chitinase and monocyte-colony inhibition factor. The protein yield on a cell basis from infecting high-density Sf9 cells was the same as or higher than that from the spinner Sf9 culture. Virus production from the high-density culture was similar to that from the spinner culture. The results show that the ultrasonic filter did not affect insect cells' ability to support protein expression and virus production following infection with baculovirus. The potential applications of the high-density perfusion culture for large-scale protein expression from Sf9 cells are also highlighted. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:351-359, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 374-378 
    ISSN: 0006-3592
    Keywords: conductive paint electrode ; prevention of marine biofouling ; fishing net ; alternating potential ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Conductive paint electrode was used for marine biofouling on fishing nets by electrochemical disinfection. When a potential of 1.2 V vs. a saturated calomel electrode (SCE) was applied to the conductive paint electrode, Vibrio alginolyticus cells attached on the electrode were completely killed. By applying a negative potential, the attached cells were removed from the surface of the electrode. Changes in pH and chlorine concentration were not observed at potentials in the range -0.6 ∼1.2 V vs. SCE. In a field experiment, accumulation of the bacterial cells and formation of biofilms on the electrode were prevented by application of an alternating potential, and 94% of attachment of the biofouling organisms was inhibited electrically on yarn used for fishing net coated with conductive paint. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:374-378, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 364-373 
    ISSN: 0006-3592
    Keywords: porous supports ; internal and external diffusion ; active site accessibility ; enzyme loading ; kinetically controlled dipeptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer limitations were studied in enzyme preparations of α-chymotrypsin made by deposition on different porous support materials such as controlled pore glasses, Celite, and polyamides of different particle sizes. It is the onset of mass transfer limitations that determines the position of the activity optimum with respect to enzyme loading on each support. The evidence of various experiments indicates that internal diffusional limitations are the important mechanism for the observed mass transfer limitations. External diffusion was not found to play an important role under the conditions used, and it was also found that when immobilizing multilayers of enzyme the buried enzyme molecules are active to a large extent. An extreme situation is observed on Celite at very high loadings. Under these conditions, this support is expected to have its pores completely filled with packed enzyme molecules, and then it is the diffusion within the enzyme layer that determines the observed rate. As the enzyme loading increases, the area of contact between the deposited enzyme layers and the liquid solution inside the pores diminishes, causing a decrease on the observed rate of an intrinsically fast reaction which apparently is incongruous with the presence of more enzyme in the system. This work shows that mass transfer limitations can be an important factor when working with immobilized enzymes in organic media, and its study should be carried out in order to avoid undesired reduced enzyme activities and specificities. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:364-373, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 438-444 
    ISSN: 0006-3592
    Keywords: bioremediation ; plasma discharge ; dichlorophenol degradation ; perchloroethylene degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pulsed electric discharge (PED) and bioremediation were combined to create a novel two-stage system which dechlorinates the halogenated pollutants, 2,4-dichlorophenol and perchloroethylene, with repetitive (0.1-1 kHz), short pulse (∼100 ns), low voltage (40-80 kV) discharges and then mineralizes the less chlorinated products with aerobic bacteria. A 6.1 mM aqueous dichlorophenol sample was cycled through the PED reactor (60 kV of applied pulsed voltage and 300 Hz) 6 times, resulting in the release of 55% of the initial dichlorophenol chloride ions (1 mM Cl- removed each cycle). The respective average specific efficiency is 0.4-0.6 keV/(Cl- molecule). Pseudomonas mendocina KR1, which grows in minimal medium supplemented with phenol but not with dichlorophenol, increased in cell density in all cultures supplemented with the PED-treated DCP samples and yielded a maximum of two-fold additional Cl- released compared to the PED-related alone. The number of PED-treatment cycles, voltage, and frequency were also varied, showing that both cell densities and overall dichlorophenol dechlorination were highly dependent upon the number of PED-treatment cycles, rather than the tested voltages and frequencies. Using this two-stage treatment system, PED released 31% of the initial chloride ions from dichlorophenol (after three cycles at 40-45 kV and 1.2 kHz) while P. mendocina KR1 in the second stage increased dechlorination to 90%. These results were corroborated by the 35% additional chloride release found with activated sludge cultures. Perchloroethylene (0.6 mM) was similarly treated in a first-stage PED reactor (80% chloride removal after four cycles) followed by biodegradation of the dechlorinated products with a recombinant toluene o-monooxygenase-expressing Pseudomonas fluorescens strain. Gas chromatographic analysis showed that the PED reactor created less-chlorinated byproducts (i.e., trichloroethylene) that were removed (74%) upon exposure to the recombinant bacterium. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:438-444, 1998.
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    Biotechnology and Bioengineering 59 (1998), S. 445-450 
    ISSN: 0006-3592
    Keywords: CHO cells ; glycosylation engineering ; antisense ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Novel glycoproteins, inaccessible by other techniques, can be obtained by metabolic engineering of the oligosaccharide biosynthesis pathway. Furthermore, alteration of cell-surface oligosaccharides can change the properties of receptors involved in cell-cell adhesion. Sialyl Lewis X (sLex) is a cell-surface oligosaccharide determinant which is specifically expressed on granulocytes and monocytes and which interacts with selectins to influence leukocyte trafficking, thrombosis, inflammation, and cancer. Antisense technology targeting fucosyltransferase VI (Fuc-TVI), an enzyme necessary for the synthesis of the sLex in engineered Chinese hamster ovary (CHO) cells, has reduced Fuc-TVI activity, sLex synthesis, and adhesion to endothelial cells. Antisense methodology to reduce targeted activity in oligosaccharide biosynthesis or other pathways is an important addition to CHO cell metabolic engineering capabilities. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:445-450, 1998.
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  • 38
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    Biotechnology and Bioengineering 59 (1998), S. 451-460 
    ISSN: 0006-3592
    Keywords: protein fouling ; membrane transport ; ultrafiltration ; adsorption ; filtration ; composite membrane ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein fouling can significantly alter both the flux and retention characteristics of ultrafiltration membranes. There has, however, been considerable controversy over the nature of this fouling layer. In this study, hydraulic permeability and dextran sieving data were obtained both before and after albumin adsorption and/or filtration using polyethersulfone ultrafiltration membranes. The dextran molecular weight distributions were analyzed by gel permeation chromatography to evaluate the sieving characteristics over a broad range of solute size. Protein fouling caused a significant reduction in the dextran sieving coefficients, with very different effects seen for the diffusive and convective contributions to dextran transport. The changes in dextran sieving coefficients and diffusive permeabilities were analyzed using a two-layer membrane model in which a distinct protein layer is assumed to form on the upstream surface of the membrane. The data suggest that the protein layer formed during filtration was more tightly packed than that formed by simple static adsorption. Hydrodynamic calculations indicated that the pore size of the protein layer remained relatively constant throughout the adsorption or filtration, but the thickness of this layer increased with increasing exposure time. These results provide important insights into the nature of protein fouling during ultrafiltration and its effects on membrane transport. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:451-460, 1998.
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  • 39
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    Biotechnology and Bioengineering 59 (1998), S. 461-470 
    ISSN: 0006-3592
    Keywords: aqueous two-phase separation ; protein partitioning ; T4 lysozyme ; electrochemical partitioning ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein partitioning in aqueous two-phase systems based on phase-forming polymers is strongly affected by the net charge of the protein, but a thermodynamic description of the charge effects has been hindered by conflicting results. Many of the difficulties could be because of problems in isolating electrochemical effects from other interactions of phase components.We explored charge effects on protein partitioning in poly(ethylene glycol)-dextran two-phase systems by using two series of genetically engineered charge modifications of bacteriophage T4 lysozyme produced in Escherichia coli. The two series, one in the form of charged-fusion tails and the other in the form of charge-change point mutations, provided matching net charges but very different polarity. Partition coefficients of both series were obtained and interfacial potential differences of the phase systems were measured. Multi-angle laser light scattering measurements were also performed to determine second virial coefficients. A semi-empirical model accounting for the roles of both charge and non-charge effects on protein partitioning behavior is proposed, and the results predicted from the model are compared to the results from the experiments. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:461-470, 1998.
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  • 40
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    Biotechnology and Bioengineering 48 (1995), S. 631-638 
    ISSN: 0006-3592
    Keywords: Saccharomyces cerevisiae ; fermentation ; on-line simulation ; state estimation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to study and control fermentation processes, indirect on-tine measurements and mathematical models can be used. In this article we present a mathematical on-line model for fermentation processes. The model is based on atom and partial mass balances as well as on equations describing the acid-base system. The model is brought into an adaptive form by including transport equations for mass transfer and unstructured expressions for the fermentation kinetics. The state of the process, i.e., the concentrations of biomass, substrate, and products, can be estimated on-line using the balance part of the model completed with measurement equations for the input and output flows of the process. Adaptivity is realized by means of on-line estimation of parameters in the transport and kinetic expressions using recursive regression analysis. These expressions can thus be used in the model as valid equations enabling prediction of the process. This makes model-based automation of the process and testing of the validity of the measurement variables possible. The model and the on-line principles are applied to a 3.5-L laboratory tormentor in which Saccharomyces cerevisiae is cultivated. The experimental results show that the model-based estimation of the state and the predictions of the process correlate closely with high-performance liquid chromatography (HPLC) analyses. © 1995 John Wiley & Sons, Inc.
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  • 41
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    Biotechnology and Bioengineering 48 (1995), S. 659-666 
    ISSN: 0006-3592
    Keywords: methanogenic activity ; ethylene ; dechlorination ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetics were determined for methanogenic activity and chlorinated ethylene dehalogenation by a methanol-enriched, anaerobic sediment consortium. The culture reductively dechlorinated perchloroethylene (PCE) to trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), vinylchloride (VC), and ethylene and ethane. The absence : of methanol or the addition of 2-bromoethanesulfonic. acid in the presence of methanol suppressed both methanogenic activity and dechlorination. In contrast, acetate production continued in the presence of 2-bromoethanesulfonic acid. These results suggest that dechlorination was strongly linked to methane formation and not to acetate production. A kinetic model, developed to describe both methanogenesis and dechlorination, successfully predicted experimentally measured concentrations of biomass, methane, substrate, and chlorinated ethylenes. The average maximum specific dehalogenation rates for PCE, TCE, 1,1-DCE, and VC were 0.9 ± 0.6, 0.4 ± 0.1, 12 ± 0.1, and 2.5 ± 1.7 μmol contaminant/ g. DW/day, respectively. This pattern for dechlorination rates is distinctly different than that reported for transition metal cofactors, where rates drop by approximately one order of magnitude as each successive chlorine is removed. The experimental results and kinetic analysis suggest that it will be impractical to targeting methanol consuming methanogenic organisms for in situ ground-water restoration. © 1995 John Wiley & Sons, Inc.
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  • 42
    ISSN: 0006-3592
    Keywords: bovine serum albumin ; growth factor ; hollow-fiber culture ; perfusion culture ; antibody production rate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of the high-molecular-weight growth factors, transferrin and bovine serum albumin (BSA), on antibody production were analyzed quantitatively in continuous hollow-fiber cultivation over a period of 60 days. Transferrin enhanced cell growth but had no significant effect on the specific antibody production rate, whereas BSA significantly enhanced antibody production. The antibody production rate was increased 4- and 14-fold respectively by feeding BSA at 2 and 5 g L-1 into the EC side of the system (the side connected to the cell-containing outer part of the hollow-fiber unit) compared with the production achieved without BSA. Addition of 5 g L1 BSA into the IC side of the system (the side connected to the inner part of the hollow-fiber unit) resulted in a 2.5-fold increase in the antibody production rate. The effect of BSA was also analyzed using the perfusion culture system with a separation unit. When fresh medium containing either 2 or 5 g L-1 BSA was fed into the reactor, both the specific growth rate and specific death rate increased, while the specific antibody production rate was increased 2- and 25-fold, respectively, by feeding BSA at these two concentrations compared with no addition. Comparing the two systems, the increase in the antibody production rate achieved with the hollow-fiber system was threefold greater than that in the perfusion culture system with the same concentration of BSA feeding. © 1995 John Wiley & Sons, Inc.
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  • 43
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    Biotechnology and Bioengineering 55 (1997), S. 252-260 
    ISSN: 0006-3592
    Keywords: lipase ; chemical modification ; stability ; esterification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Semipurified lipase of Candida rugosa (CRSL) was subjected to chemical modification, and the activities of the modified lipase, in hydrolysis and esterification reactions, were examined. The esterification reactions were carried out in the absence and presence of isooctane. When the enzyme was modified with polyethylene glycol (PEG), two methodologies were studied. The activation of PEG with p-NO2-phenylchloroformate gives better biocatalysts than those obtained with cyanuric chloride-PEG. The chemical modification with PEG increases the stability of pure lipases in isooctane at 50°C (extreme conditions). The chemically modified enzymes are useful for biotransformations in organic solvents. In addition the nitration of tyrosines with tetranitromethane was also studied. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 252-260, 1997.
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  • 44
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    Biotechnology and Bioengineering 49 (1996), S. 204-216 
    ISSN: 0006-3592
    Keywords: expanded bed adsorption ; bakers' yeast ; G6PDH ; STREAMLINE ion exchange adsorbents ; Chemistry ; Biochemistry and Biotechnology
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    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of expanded beds of STREAMLINE ion exchange adsorbents for the direct extraction of an intracellular enzyme glucose-6-phosphate dehydrogenase (G6PDH) from unclarified yeast cell homogenates has been investigated. It has been demonstrated that such crude feedstocks can be applied to the bed without prior clarification steps. The purification of G6PDH from an unclarified yeast homogenate was chosen as a model system containing the typical features of a direct extraction technique. Optimal conditions for the purification were determined in small scale, packed bed experiments conducted with clarified homogenates. Results from these experiments were used to develop a preparative scale separation of G6PDH in a STREAMLINE 50 EBA apparatus. The use of an on-line rotameter for measuring and controlling the height of the expanded bed when operated in highly turbid feedstocks was demonstrated. STREAMLINE DEAE has been shown to be successful in achieving isolation of G6PDH from an unclarified homogenate with a purification factor of 12 and yield of 98% in a single step process. This ion exchange adsorbent is readily cleaned using simple cleaning-in-place procedures without affecting either adsorption or the bed expansion properties of the adsorbent after many cycles of operation. The ability of combining clarification, capture, and purification in a single step will greatly simplify downstream processing flowsheets and reduce the costs of protein purification. © 1996 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 49 (1996), S. 259-265 
    ISSN: 0006-3592
    Keywords: hepatocytes ; lactose-derivatized polystyrene ; polystyrene ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hepatocytes isolated from male Fisher 344VF rats were cultured on two substrates, collagen I and a lactose-derivatized polystyrene (PS-lactose), to compare morphological and functional differences. Hepatocyte morphology changed dramatically depending upon the substrate, shown through actin cytoskeletal staining and scanning electron microscopy. Functional assays performed included albumin secretion, reduced glutathione content, UDP-glucuronosyl transferase, and cytochrome P4501A1 activity. The presence of dexamethasone and dimethylsulfoxide (DMSO) in the media was required for the maintenance of several differentiated functions for cells cultured on collagen. In general, cells cultured on the PS-lactose substrate showed a much slower loss of function over the same period of time. The maintenance of differentiated function of cells on PS-lactose was enhanced with the addition of dexamethasone and DMSO. This is the first report of a culture system in which hepatocytes, cultured on a polymer substrate without additional protein coatings or media additives, have been able to maintain differentiated functions for up to 1 week. © 1996 John Wiley & Sons, Inc.
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  • 46
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    Biotechnology and Bioengineering 49 (1996), S. 290-299 
    ISSN: 0006-3592
    Keywords: proteins, modified ; partitioning in aqueous system ; thaumatin ; β-lactoglobulin ; BSA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Relatively conservative modifications of three proteins were carried out to alter their surface properties. The protein properties modified were hydrophobicity and charge. This was done by acylation of amino groups with anhydrides. For the hydrophobic modification experiments, two proteins (β-lactoglobulin and bovine serum albumin [BSA]) and four anhydrides (hexanoic, butyric, succinic, acetic) were used. For the modification of surface charge the protein thaumatin was selected and various proportions of the free amino groups were blocked with acetic anhydride to give a series of proteins with differing isoelectric points. Detailed characterization and purification of selected modified proteins was carried out including molecular weight measurements and conformational analysis. The criteria used for selecting the modified proteins for subsequent investigation of their partitioning in aqueous two-phase systems (ATPS) is described. With a judicious choice of starting material it was found that limited chemical modifications to proteins could effectively alter surface hydrophobicity or charge almost independently, with little effect on other molecular properties. It appears, however, that the method for chemical modification and the reaction conditions must also be carefully controlled. © 1996 John Wiley & Sons, Inc.
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  • 47
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    Biotechnology and Bioengineering 49 (1996), S. 309-315 
    ISSN: 0006-3592
    Keywords: surface charge ; proteins, modified ; partitioning in aqueous system ; thaumatin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A series of charge-modified thaumatins with different values of surface charge were partitioned in aqueous two-phase systems (ATPS) to study the effect of surface charge as a single property on partitioning. Electrophoretic mobility of the proteins in titration curves was used as a measure of surface charge. Four modified proteins derived from thaumatin with the following values of isoelectric point: 8.70, 8.15, 5.60, and 4.50 were used for partitioning. The resolution of the systems in terms of protein surface charge was calculated. Partitioning of modified thaumatins in PEG 4000/dextran systems with phosphate buffer, Tris buffer, NaCl, KCl, and sulfate salts was carried out. Among the sulfate salts tested, the addition of 50 mM Li2SO4 to the system buffered with phosphate gave the highest value of resolution for differences in surface protein charge (RSPC). It shows a decrease in the value of K (partition coefficient) with an increase in the protein's charge. The addition of 100 mM KCl to the system promoted the opposite effect on the RSPC value. Charge-modified proteins were partitioned in PEG/salt systems to investigate the ability of these systems for resolving differences in surface charge. The PEG/citrate system seemed to have almost no ability for resolving proteins on the basis of surface charge differences; PEG/phosphate systems had some capability for resolving differently charged proteins. The more negative proteins tended to have higher values of K than the more positively charged fractions. The use of charge-modified proteins allowed the investigation of the effect of protein surface charge on partitioning in aqueous two-phase systems independently from other protein parameters as they were prepared from a common parent protein thaumatin. This technique provides an interesting novel tool to investigate the effect of protein surface charge on partitioning in ATPS taking protein charge as an independent parameter. © 1996 John Wiley & Sons, Inc.
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  • 48
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    Biotechnology and Bioengineering 49 (1996), S. 348-354 
    ISSN: 0006-3592
    Keywords: oxygenator ; NMR spectroscopy ; organ perfusion ; mammalian cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A compact, reusable membrane oxygenator has been constructed for the perfusion of cultured cells and isolated organs. While the oxygenator was designed to be compatible with nuclear magnetic resonance (NMR) spectroscopy studies, it can also be used for any experiment which requires warming and oxygenation of perfusates. For the NMR studies, the oxygenator can be positioned at the opening of the magnet bore which allows oxygenation and warming of the perfusate immediately prior to delivery to the tissue, therefore eliminating problems with heat or oxygen loss which may occur with the long perfusion lines. © 1996 John Wiley & Sons, Inc.
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  • 49
    ISSN: 0006-3592
    Keywords: c-fos protein ; endothelium ; hemodynamics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The c-fos protein belongs to a family of transcriptional cofactors that can complex with proteins of the Jun family and activate mRNA transcription from gene promoters containing an activator protein 1 (AP-1) binding element. The shear stress inducibility of the c-fos protein was studied in human and animal cell lines of vastly different origins. Primary human umbilical vein endothelial cells (HUVEC), bovine aortic endothelial cells (BAEC, passage 2-14), HeLa cells, and Chinese hamster ovary (CHO) cells were subjected to steady laminar shear stress using a parallel plate flow apparatus. After 1 h of flow exposure at 25 dyn/cm2, the c-fos levels in nuclei of shear stress HUVEC, BAEC, HeLa, and CHO were 5.4 ± 2.0 (n = 3), 2.25 ± 1.38 (n = 6), 2.14 ± 0.07 (n = 8), 1.92 ± 0.58 (n = 2) times higher, respectively, than in matched stationary controls. Flow exposure at 4 dyn/cm2 caused no enhancement of c-fos levels in any of the cell lines tested, but caused significant reduction in c-fos expression in the HeLa cells. The c-fos induction by shear stress could be blocked by pharmacological agents. For example, the flow induction of the c-fos protein levels was blocked by 50% with the preincubation of HUVEC with a protein kinase C inhibitor, H7 (10 μM) and blocked completely in HeLa cells preincubated with the phospholipase C inhibitor, neomycin (5 mM). The minimum time of shear stress exposure required to induce the c-fos protein expression in HeLa cells was found to be as low as 1 min. By Northern analysis, the c-fos mRNA levels were found to be elevated in BAEC, CHO, and HeLa cells exposed to 25 dyn/cm2 for 30 min. These studies indicate that c-fos induction is a consistent genetic response in a variety of mammalian cells that may alter cellular phenotype in mechanical environments. © 1996 John Wiley & Sons, Inc.
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  • 50
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    Biotechnology and Bioengineering 49 (1996), S. 412-420 
    ISSN: 0006-3592
    Keywords: Amycolatopsis orientalis ; vancomycin production ; chemostat culture ; phosphate inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Production of the glycopeptide antibiotic vancomycin by two Amycolatopsis orientalis strains was examined in batch shake flask culture in a semidefined medium with peptone as the nitrogen source. Different growth and production profiles were observed with the two strains; specific production (Yp/x) was threefold higher with strain ATCC 19795 than with strain NCIMB 12945. A defined medium with amino acids as the nitrogen source was developed by use of the Plackett-Burman statistical screening method. This technique identified certain amino acids (glycine, phenylalanine, tyrosine, and arginine) that gave significant increased specific production, whereas phosphate was identified as inhibitory for high specific vancomycin production. Experiments made with the improved medium and strain ATCC 19795 showed that vancomycin production kinetics were either growth dissociated or growth associated, depending on the amino acid concentration. In chemostat culture at a constant dilution rate (0.087 h-1), specific vancomycin production rate (qvancomycin) decreased linearly as the medium phosphate concentration was increased from 2 to 8 mM. In both phosphate and glucose limited chemostats, qvancomycin was a function of specific growth rate; the maximum value was observed at D = 0.087 h-1 (52% of the maximum specific growth rate). Under phosphate limited growth conditions, qvancomycin was threefold higher (0.37 mg/g dry weight/h) than under glucose limitation (0.12 mg/g dry weight/h). © 1996 John Wiley & Sons, Inc.
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  • 51
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    Biotechnology and Bioengineering 50 (1996), S. 36-48 
    ISSN: 0006-3592
    Keywords: insect cell culture ; Sf-9 cells ; respiration ; bioreactor ; on-line monitoring ; baculovirus expression vector system ; recombinant proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Respiration rates in Spodoptera frugiperda (Sf-9) cell bioreactor cultures were successfully measured on-line using two methods: The O2 uptake rate (OUR) was determined using gas phase pO2 values imposed by a dissolved oxygen controller and the CO2 evolution rate (CER) was measured using an infrared detector. The measurement methods were accurate, reliable, and relatively inexpensive. The CER was routinely determined in bioreactor cultures used for the production of several recombinant proteins. Simple linear relationships between viable cell densities and both OUR and CER in exponentially growing cultures were used to predict viable cell density. Respiration measurements were also used to follow the progress of baculoviral infections in Sf-9 cultures. Infection led to increases in volumetric and per-cell respiration rates. The relationships between respiration and several other culture parameters, including viable cell density, cell protein, cell volume, glucose consumption, lactate production, viral titer, and recombinant β-galactosidase accumulation, were examined. The extent of the increase in CER following infection and the time postinfection at which maximum CER was attained were negatively correlated with the multiplicity of infection (MOI) at multiplicities below the level required to infect all the cells in a culture. Delays in the respiration peak related to the MOI employed were correlated with delays in the peak in recombinant protein accumulation. DO levels in the range 5-100% did not exert any major effects on viable cell densities, CER, or product titer in cultures infected with a baculovirus expressing recombinant β-galactosidase. © 1996 John Wiley & Sons, Inc.
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  • 52
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    Biotechnology and Bioengineering 50 (1996) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 53
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    Biotechnology and Bioengineering 50 (1996), S. 169-183 
    ISSN: 0006-3592
    Keywords: liposomes ; biotin ; aggregation kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The aggregation of biotinylated phospholipid vesicles (liposomes) cross-linked by antibiotin IgG was studied experimentally and theoretically. The liposomes were either low density liposomes that contained 0.4 mol% biotinylated phospholipid (≈100 exposed biotin molecules per liposome), or high density liposomes that contained 2.7 mol% biotinylated phospholipid (≈1000 exposed biotin molecules per liposome). The solution turbidity and mean particle size measured by quasi-elastic light scattering (QLS) were monitored throughout the aggregation. Three different lots of antibiotin antibodies, each with different association constants and binding heterogeneities, were used. The antibody binding characteristics affected the aggregation rates. The aggregation kinetics were analyzed using a model based on the Smoluchowski theory of aggregation, fractal concepts of aggregate microstructure, and Rayleigh and Mie light scattering theory. The experimental conditions of liposome concentration, protein concentration, and ligand density under which aggregation occurred correlated well with calculated sticking probabilities based on isotherms describing the adsorption of antibiotin antibody to the liposomes. These results are compared with prior observations made when avidin was used as the cross-linking protein. © 1996 John Wiley & Sons, Inc.
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  • 54
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    Biotechnology and Bioengineering 50 (1996) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
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  • 55
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    Biotechnology and Bioengineering 50 (1996), S. 211-216 
    ISSN: 0006-3592
    Keywords: microgravity ; bioprocessing ; sedimentation ; turbulence ; collagenase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of a quiescent microgravity fluid environment on the activity of collagenase directed at demineralized bone fragments was investigated over a period of 10 days. Enzyme treatment resulted in greater mass loss in microgravity, with nearly three times the loss of mass during Space Shuttle mission STS-62 compared to the stationary ground control. Clinorotation enhanced the loss of mass relative to a stationary control, but this increase was still significantly less than the increase with exposure to microgravity. This suggests the detrimental influence of turbulence on the enzyme function and the benefit of using microgravity to provide both low turbulence and uniformity of unequally dense materials within the reaction chamber. The results are considered for their general applicability to a variety of bioprocessing applications that may be enhanced in microgravity. © 1996 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 50 (1996), S. 430-437 
    ISSN: 0006-3592
    Keywords: cartilage ; tissue regeneration ; chondrocytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the last 5 to 10 years, tissue engineering has revolutionized the way in which medical researchers and clinicians are thinking of and, in some cases, actually treating diseases involving tissue damage and destruction. One such disease, osteoarthritis, results from progressive degeneration of articular cartilage, which has a limited ability to repair itself. With tissue engineering, scientists are now able to regenerate cartilage in vitro from isolated mature chondrocytes. While the regeneration process is still not fully understood, enough has been learned that physicians are already implanting cultured chondrocytes into humans and other animals in the hopes of effecting joint repair. One aspect which has not been fully explored is the effect of mechanical stress on developing and implanted cartilage, especially over the long term. This article will review in brief what is now known about the mechanical factors affecting cartilage regeneration in vitro and what still remains to be determined for optimum tissue engineering of cartilage constructs. © 1996 John Wiley & Sons, Inc.
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    Biotechnology and Bioengineering 50 (1996), S. 443-451 
    ISSN: 0006-3592
    Keywords: osteoblast ; migration ; poly(αhydroxy esters) ; poly(DL-lactic-co-glycolic acid) ; PLGA ; biodegradable polymers ; tissue engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We investigated the migration of rat calvaria osteoblast populations on poly(α-hydroxy ester) films for up to 14 days to determine effects of substrate composition and culture conditions on the migratory characteristics of osteoblasts. Initial osteoblast culture conditions included cell colonies formed by seeding a high (84,000 cells/cm2) or low (42,000 cells/cm2) density of isolated osteoblasts on the polymer films, and bone tissue cultures formed by plating bone chips directly on the substrates. High density osteoblast colonies cultured and allowed to migrate and proliferate radially on 85:15 poly(DL-lactic-co-glycolic acid) (PLGA) films, 75:25 PLGA films, and tissue culture polystyrene controls demonstrated that the copolymer ratio in the polymer films did not affect the rate of increase in substrate surface area (or culture area) covered by the growing cell colony. However, the rate of increase in culture area was dependent on the initial osteoblast seeding density. Initial cell colonies formed with a lower osteoblast seeding density on 75:25 PLGA resulted in a lower rate of increase in culture area, specifically 4.9 ± 0.3 mm2/day, versus 14.1 ± 0.7 mm2/day for colonies seeded with a higher density of cells on the same polymer films. The proliferation rate for osteoblasts in the high and low density seeded osteoblast colonies did not differ, whereas the proliferation rate for the osteoblasts arising from the bone chips was lower than either of these isolated cell colonies. Confocal and light microscopy revealed that the osteoblast migration occurred as a monolayer of individual osteoblasts and not a calcified tissue front. These results demonstrated that cell seeding conditions strongly affect the rates of osteoblast migration and proliferation on biodegradable poly(α-hydroxy esters). © 1996 John Wiley & Sons, Inc.
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  • 58
    ISSN: 0006-3592
    Keywords: bone marrow ; hematopoiesis ; perfusion ; culture optimization ; stroma ; stem cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hematopoiesis, the formation of mature blood cells from stem (LTC-IC) and progenitor (CFU-GM) cells in the bone marrow, is a complex tissue-forming process that leads to many important physiological functionalities. Consequently, a functioning ex vivo hematopoietic system has a variety of basic scientific and clinical uses. The design and operation of such a system presents the tissue engineer with challenges and choices. In this study, three culture variables were used to control ex vivo human hematopoiesis. Systematic variation of inoculum density (ID), medium exchange interval (MEI), and the use of preformed stroma (PFS) showed that (1) all three variables significantly influenced culture performance, (2) the three variables interacted strongly, and (3) the variables could be manipulated to achieve the optimization of different performance criteria. Donor-to-donor variability in culture performance was great at low ID but was minimized at higher ID. PFS had a large positive effect on cell and CFU-GM output at low ID, but had minimal effect at higher ID. In fact, PFS caused a decrease in LTC-IC output at high ID. The effects of PFS indicated that stromal cell elements became more limiting than proliferative cell elements as ID was reduced.In cultures without PFS, maximum cell output was obtained with high ID using a short MEI, whereas the greatest cell expansion ratio was obtained at low ID with an intermediate MEI. Maximum CFU-GM output was obtained from cultures with high ID using a short to intermediate MEI, whereas the greatest CFU-GM expansion ratio was obtained at intermediate ID with an intermediate MEI. The addition of PFS altered the locations of these maxima. In general, PFS moved the maxima to lower ID, and culture output became more sensitive to MEI. Therefore, the optimization of one performance criterion always resulted in a decline of the others. This study demonstrates that ex vivo tissue function is sensitive to many culture variables in an interactive fashion and that systematic multivariable studies are required to characterize tissue function. Once the effects of individual variables and their interactions are known, this knowledge can be used to optimize tissue performance with respect to desired criteria. © 1996 John Wiley & Sons, Inc.
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  • 59
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    Biotechnology and Bioengineering 50 (1996) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 60
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    Biotechnology and Bioengineering 55 (1997), S. 565-570 
    ISSN: 0006-3592
    Keywords: hybridoma ; hypoosmotic stress ; specific antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To investigate the response of hybridoma cells to hypoosmotic stress, S3H5/γ2bA2 and DB9G8 hybridomas were cultivated in the hypoosmolar medium [Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% serum] resulting from sodium chloride subtraction. Both hybridomas showed similar responses to hypoosmotic stress in regard to cell growth and antibody production. The cell growth and antibody production at 276 mOsm/kg were comparable to those at 329 mOsm/kg (standard DMEM). Both cells grew well at 219 mOsm/kg, though their growth and antibody production were slightly decreased. When the osmolality was further decreased to 168 mOsm/kg, the cell growth did not occur. When subjected to hyperosmotic stress, both cells displayed significantly enhanced specific antibody productivity (qAb). However, the cells subjected to hypoosmotic stress did not display enhanced qAb. Taken together, both hyperosmotic and hypoosmotic stresses depressed the growth of S3H5/γ2bA2 and DB9G8 hybridomas. However, their response to hypoosmotic stress in regard to qAb was different from that to hyperosmotic stress. © 1997 John Wiley & Sons, Inc. Biotechnol Biong 55: 565-570, 1997.
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  • 61
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    Biotechnology and Bioengineering 55 (1997), S. 547-555 
    ISSN: 0006-3592
    Keywords: ethanol ; cellulose ; hemicellulose ; endoglucanase ; cellulase ; lignocellulose ; biomass ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study demonstrates a new approach to reduce the amount of fungal cellulase required for the conversion of cellulose into ethanol. Escherichia coli KO11, a biocatalyst developed for the fermentation of hemicellulose syrups, was used to produce recombinant endoglucanase as a co-product with ethanol. Seven different bacterial genes were expressed from plasmids in KO11. All produced cell-associated endoglucanase activity. KO11(pLOI1620) containing Erwinia chrysanthemi celZ (EGZ) produced the highest activity, 3,200 IU endoglucanase/L fermentation broth (assayed at pH 5.2 and 35°C). Recombinant EGZ was solubilized from harvested cells by treatment with dilute sodium dodecyl sulfate (12.5 mg/ml, 10 min, 50°C) and tested in fermentation experiments with commercial fungal cellulase (5 filter paper units/g cellulose) and purified cellulose (100 g/L). Using Klebsiella oxytoca P2 as the biocatalyst, fermentations supplemented with EGZ as a detergent-lysate of KO11(pLOI1620) produced 14%-24% more ethanol than control fermentations supplemented with a detergent-lysate of KO11(pUC18). These results demonstrate that recombinant bacterial endoglucanase can function with fungal cellulase to increase ethanol yield during the simultaneous saccharification and fermentation of cellulose. © 1997 Wiley & Sons, Inc. Biotechnol Bioeng 55: 547-555, 1997.
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  • 62
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    Biotechnology and Bioengineering 55 (1997), S. 577-580 
    ISSN: 0006-3592
    Keywords: mRNA stability ; hairpins ; gene expression control ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An expression system has been developed for the introduction of DNA cassettes into the region between the transcription and translation start sites of a gene of interest. This cassette system was used to engineer mRNA stability through the introduction of hairpins at the 5′ end. A synthetic DNA cassette was designed so that the resulting mRNA hairpin would be positioned one nucleotide from the 5′ mRNA end. The hairpin-containing mRNA exhibited a half-life 3 times that of the mRNA with no hairpin, resulting in increases in both mRNA and protein levels. These results indicate that it is possible to engineer mRNA stability as an additional means of controlling gene expression. © 1997 John Wiley & Sons Inc. Biotechnol Bioeng 55: 557-580, 1997
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  • 63
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    Biotechnology and Bioengineering 55 (1997), S. 581-591 
    ISSN: 0006-3592
    Keywords: adsorptive membranes ; oscillatory flow ; integrated processes ; in situ product recovery ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Preferential transport in adsorptive membranes can be used to selectively remove biochemicals directly from fermentation broths. During preferential transport, an adsorbing solute is selectively transported across the membrane while nonadsorbing solutes and cells are retained by the membrane. This technique was used to separate lysozyme directly from a feed containing lysozyme, myoglobin, and yeast cells. We found that because the oscillatory flows used in preferential transport involve strokes that are close to symmetric, they are very efficient in alleviating cake formation due to cell deposition on the membrane surface. Theoretical results suggest that, by optimizing process variables, preferential transport can lead to a continuous concentrated stream of the adsorbing protein. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 581-591, 1997.
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  • 64
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    Biotechnology and Bioengineering 55 (1997), S. 592-608 
    ISSN: 0006-3592
    Keywords: Saccharomyces cerevisiae ; metabolic modeling ; sensitivity analysis ; glycolysis ; compartmentation ; transient response ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model of glycolysis in Saccharomyces cerevisiae is presented. The model is based on rate equations for the individual reactions and aims to predict changes in the levels of intra- and extracellular metabolites after a glucose pulse, as described in part I of this study. Kinetic analysis focuses on a time scale of seconds, thereby neglecting biosynthesis of new enzymes. The model structure and experimental observations are related to the aerobic growth of the yeast. The model is based on material balance equations of the key metabolites in the extracellular environment, the cytoplasm and the mitochondria, and includes mechanistically based, experimentally matched rate equations for the individual enzymes. The model includes removal of metabolites from glycolysis and TCC for biosynthesis, and also compartmentation and translocation of adenine nucleotides. The model was verified by in vivo diagnosis of intracellular enzymes, which includes the decomposition of the network of reactions to reduce the number of parameters to be estimated simultaneously. Additionally, sensitivity analysis guarantees that only those parameters are estimated that contribute to systems trajectory with reasonable sensitivity. The model predictions and experimental observations agree reasonably well for most of the metabolites, except for pyruvate and adenine nucleotides. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 592-608, 1997.
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  • 65
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    Biotechnology and Bioengineering 55 (1997), S. 609-615 
    ISSN: 0006-3592
    Keywords: interacting populations ; membrane reactor ; induced metabolic changes ; elicitation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design of a reactor in which two interacting cell populations (microorganisms and plants) could grow under controlled conditions was considered. In this reactor, the cell populations are separated by a membrane which permits semi-in vivo study of induced interaction-specific changes in metabolism. In this paper, the interaction of suspension culture of Nicotiana tabacum (tobacco) and the Oomycete, Phytophthora nicotiana was simulated. The results of the computer simulation show the induced metabolic changes as a consequence of the biological interaction. The paper introduces a novel approach in the strategy for the study of interacting population in suspension cultures. This type of system has potential applications in studies of the regulation of secondary metabolism and for the production of high values pharmaceuticals. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 609-615, 1997.
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  • 66
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    Biotechnology and Bioengineering 55 (1997), S. 616-629 
    ISSN: 0006-3592
    Keywords: cell adhesion ; radial-flow chamber ; hydrodynamic shear ; detachment kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The strength of adhesion and dynamics of detachment of murine 3T3 fibroblasts from self-assembled monolayers were measured in a radial-flow chamber (RFC) by applying models for fluid mechanics, adhesion strength probability distributions, and detachment kinetics. Four models for predicting fluid mechanics in a RFC were compared to evaluate the accuracy of each model and the significance of inlet effects. Analysis of these models indicated an outer region at large radial positions consistent with creeping flow, an intermediate region influenced by inertial dampening, and an inner region dominated by entrance effects from the axially-oriented inlet. In accompanying experiments patterns of the fraction of cells resisting detachment were constructed for individual surfaces as a function of the applied shear stress and evaluated by comparison with integrals of both a normal and a log-normal distribution function. The two functions were equally appropriate, yielding similar estimates of the mean strength of adhesion. Further, varying the Reynolds number in the inlet, Red, between 630 and 1480 (corresponding to volumetric flow rates between 0.9 and 2.1 mL/s) did not affect the mean strength of adhesion. For these same experiments, analysis of the dynamics of detachment revealed three temporal phases: 1) rapid detachment of cells at the onset of flow, consistent with a first-order homogeneous kinetic model; 2) time-dependent rate of detachment during the first 30 sec. of exposure to hydrodynamic shear, consistent with the first-order heterogeneous kinetic model proposed by Dickinson and Cooper (1995); and 3) negligible detachment, indicative of pseudo-steady state after 60 sec. of flow. Our results provide rigorous guidelines for the measurement of adhesive interactions between mammalian cells and prospective biomaterial surfaces using a RFC. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 616-629, 1997.
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  • 67
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    Biotechnology and Bioengineering 55 (1997), S. 693-700 
    ISSN: 0006-3592
    Keywords: glucose ; lactate ; real-time determination ; hematopoietic cell culture ; colony-forming cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucose and lactate metabolic rates were evaluated for cultures of cord blood (CB) mononuclear cell (MNC), peripheral blood (PB) MNC, and PB CD34+ cell cultures carried out in spinner flasks and in T-flasks in both serum-containing and serum-free media. Specific glucose uptake rates (qgluc, in micromoles per cell per hour) and lactate generation rates (qlac) correlated with the percentage of colony-forming cells (CFC) present in the culture for a broad range of culture conditions. Specifically, the time of maximum CFC percentage in each culture coincided with the time of maximum qgluc and qlac in cultures with different seeding densities and cytokine combinations. A two-population model (Qlac = α[CFC] + β([TC] - [CFC]), where [TC] is total cell concentration; Qlac is volumetric lactate production rate in micromoles per milliliter per hour; α is qlac for an average CFC; and β is qlac for an average non-CFC) was developed to describe lactate production. The model described lactate production well for cultures carried out in both T-flasks and spinner flasks and inoculated with either PB or CB MNC or PB CD34+ cells. The values for α and β that were derived from the model varied with both the inoculum density and the cytokine combination. However, preliminary results indicate that cultures carried out under the same conditions from different samples with similar initial CD34+ cell content have similar values for β and β. These findings suggest that it should be possible to use lactate production data to predict the harvest time that corresponds to the maximum number of CFC in culture. The ability to harvest ex vivo hematopoietic cultures for transplantation when CFC are at a maximum has the potential to speed the rate at which immunocompromised patients recover. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 693-700, 1997.
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  • 68
    ISSN: 0006-3592
    Keywords: tubular photobioreactors ; light distribution ; average solar irradiance ; light attenuation ; microalgae mass culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model to estimate the solar irradiance profile and average light intensity inside a tubular photobioreactor under outdoor conditions is proposed, requiring only geographic, geometric, and solar position parameters. First, the length of the path into the culture traveled by any direct or disperse ray of light was calculated as the function of three variables: day of year, solar hour, and geographic latitude. Then, the phenomenon of light attenuation by biomass was studied considering Lambert-Beer's law (only considering absorption) and the monodimensional model of Cornet et al. (1900) (considering absorption and scattering phenomena). Due to the existence of differential wavelength absorption, none of the literature models are useful for explaining light attenuation by the biomass. Therefore, an empirical hyperbolic expression is proposed. The equations to calculate light path length were substituted in the proposed hyperbolic expression, reproducing light intensity data obtained in the center of the loop tubes. The proposed model was also likely to estimate the irradiance accurately at any point inside the culture. Calculation of the local intensity was thus extended to the full culture volume in order to obtain the average irradiance, showing how the higher biomass productivities in a Phaeodactylum tricornutum UTEX 640 outdoor chemostat culture could be maintained by delaying light limitation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 701-714, 1997.
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  • 69
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    Biotechnology and Bioengineering 55 (1997), S. 715-726 
    ISSN: 0006-3592
    Keywords: fungal morphology ; pellets ; hyphae ; hair of pellets ; agitation intensity ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both parallel fermentations with Aspergillus awamori (CBS 115.52) and a literature study on several fungi have been carried out to determine a relation between fungal morphology and agitation intensity. The studied parameters include hyphal length, pellet size, surface structure or so-called hairy length of pellets, and dry mass per-wet-pellet volume at different specific energy dissipation rates. The literature data from different strains, different fermenters, and different cultivation conditions can be summarized to say that the main mean hyphal length is proportional to the specific energy dissipation rate according to a power function with an exponent of -0.25 ± 0.08. Fermentations with identical inocula showed that pellet size was also a function of the specific energy dissipation rate and proportional to the specific energy dissipation rate to an exponent of -0.16 ± 0.03. Based on the experimental observations, we propose the following mechanism of pellet damage during submerged cultivation in stirred fermenters. Interaction between mechanical forces and pellets results in the hyphal chip-off from the pellet outer zone instead of the breakup of pellets. By this mechanism, the extension of the hyphae or hair from pellets is restricted so that the size of pellets is related to the specific energy dissipation rate. Hyphae chipped off from pellets contribute free filamentous mycelia and reseed their growth. So the fraction of filamentous mycelial mass in the total biomass is related to the specific energy dissipation rate as well.To describe the surface morphology of pellets, the hyphal length in the outer zone of pellets or the so-called hairy length was measured in this study. A theoretical relation of the hairy length with the specific energy dissipation rate was derived. This relation matched the measured data well. It was found that the porosity of pellets showed an inverse relationship with the specific energy dissipation rate and that the dry biomass per-wet-pellet volume increased with the specific energy dissipation rates. This means that the tensile strength of pellets increased with the increase of specific energy dissipation rate. The assumption of a constant tensile strength, which is often used in literature, is then not valid for the derivation of the relation between pellet size and specific energy dissipation rate. The fraction of free filamentous mycelia in the total biomass appeared to be a function of the specific energy dissipation in stirred bioreactors. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 715-726, 1997.
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  • 70
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    Biotechnology and Bioengineering 57 (1998), S. 518-528 
    ISSN: 0006-3592
    Keywords: ammonium ; UDP-GlcNAc ; N -glycosylation ; BHK-21 cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of different ammonium concentrations and glucosamine on baby hamster kidney (BHK)-21 cell cultures grown in continuously perfused double membrane bioreactors was investigated with respect to the final carbohydrate structures of a secretory recombinant glycoprotein. The human interleukin-2 (IL-2) mutant glycoprotein variant IL-Mu6, which bears a novel N-glycosylation site (created by a single amino acid exchange of Gln100 to Asn), was produced under different defined protein-free culture conditions in the presence or absence of either glutamine, NH4Cl, or glucosamine. Recombinant glycoprotein products were purified and characterized by amino acid sequencing and carbohydrate structural analysis using matrix-assisted laser desorption ionization time of flight mass spectrometry, high-pH anion-exchange chromatography with pulsed amperometric detection, and methylation analysis. In the absence of glutamine, cells secreted glycoprotein forms with preponderantly biantennary, proximal fucosylated carbohydrate chains (85%) with a higher NeuAc content (58%). Under standard conditions in the presence of 7.5 mM glutamine, complex-type N-glycans were found to be mainly biantennary (68%) and triantennary structures (33%) with about 50% containing proximal α1-6-linked fucose; 37% of the antenna were found to be substituted with terminal α2-3-linked N-acetylneuraminic acid. In the presence of 15 mM exogenously added NH4Cl, a significant and reproducible increase in tri- and tetraantennary oligosaccharides (45% of total) was detected in the secretion product. In glutamin-free cultures supplemented with glucosamine, an intermediate amount of high antennary glycans was detected. The increase in complexity of N-linked oligosaccharides is considered to be brought about by the increased levels of intracellular uridine diphosphate-GlcNAc/GalNAc. These nucleotide sugar pools were found to be significantly elevated in the presence of high NH3/NH4+ and glucosamine concentrations. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 518-528, 1998.
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  • 71
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    Biotechnology and Bioengineering 57 (1998), S. 557-570 
    ISSN: 0006-3592
    Keywords: Alcaligenes eutrophus ; polyhydroxyalkanoates ; metabolic engineering ; mathematical modeling ; enzyme kinetics ; regulation of metabolism ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model describing intracellular polyhydroxybutyrate (PHB) synthesis in Alcaligenes eutrophus has been constructed. The model allows investigation of issues such as the existence of rate-limiting enzymatic steps, possible regulatory mechanisms in PHB synthesis, and the effects different types of rate expressions have on model behavior. Simulations with the model indicate that activities of all PHB pathway enzymes influence overall PHB flux and that no single enzymatic step can easily be identified as rate limiting. Simulations also support regulatory roles for both thiolase and reductase, mediated through AcCoA/CoASH and NADPH/NADP+ ratios, respectively. To make the model more realistic, complex rate expressions for enzyme-catalyzed reactions were used which reflect both the reversibility of the reactions and the reaction mechanisms. Use of the complex kinetic expressions dramatically changed the behavior of the system compared to a simple model containing only Michaelis-Menten kinetic expressions; the more complicated model displayed different responses to changes in enzyme activities as well as inhibition of flux by the reaction products CoASH and NADP+. These effects can be attributed to reversible rate expressions, which allow prediction of reaction rates under conditions both near and far from equilibrium. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 557-570, 1998.
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  • 72
    ISSN: 0006-3592
    Keywords: rhG-CSF ; fusion protein ; secretion efficiency ; glycosylation ; multimer ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The synthesis and secretion of recombinant human granulocyte colony-stimulating factor (rhG-CSF) are investigated in fed-batch cultures at high cell concentration of recombinant Saccharomyces cerevisiae, and some important characteristics of the secreted rhG-CSF are demonstrated. Transcription of the recombinant gene is regulated by a GAL1-10 upstream activating sequence (UASG), and the rhG-CSF is expressed in a hybrid fusion protein consisting of signal sequence of Kluyveromyces lactis killer toxin and N-terminal 24 amino acids of human interleukin 1β. The intracellular KEX2 cleavage leads to excretion of mature rhG-CSF into extracellular culture broth, and the cleavage process seems to be highly efficient. In spite of relatively low copy number the plasmid propagation is stably maintained even at nonselective culture conditions. The rhG-CSF synthesis does not depend on galactose level, whereas the production of extracellular rhG-CSF was significantly enhanced by increasing the inducer concentration above a certain level and also by supplementing the nonionic surfactant to the culture medium, which is notably due to the enhanced secretion efficiency. Various immunoblotting analyses demonstrate that none of the rhG-CSF is accumulated in the cell wall fraction and that a significant amount of intracellular rhG-CSF antibody-specific immunoreactive proteins is located in the ER. A core N-glycosylation at fused IL-1β fragment is likely to play a critical role in directing the high-level secretion of rhG-CSF, and the O-glycosylation of secreted rhG-CSF seems nearly negligible. Also the extracellular rhG-CSF is observed to exist as various multimers, and the nature of molecular interaction is evidently not the covalent disulfide bridges. The CD spectra of purified rhG-CSF and Escherichia coli-derived standard show that the conformations of both are similar and are almost identical to that reported for natural hG-CSF. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 600-609, 1998.
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    Biotechnology and Bioengineering 57 (1998), S. 620-623 
    ISSN: 0006-3592
    Keywords: protein refolding ; reversed micelles ; solid-liquid extraction ; RNase A ; DNA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article reports that a reversed micellar solution is useful for refolding proteins directly from a solid source. The solubilization of denatured RNase A, which had been prepared by reprecipitation from the denaturant protein solution, into reversed micelles formulated with sodium di-2-ethylhexyl sulfosuccinate (AOT) has been investigated by a solid-liquid extraction system. This method is an alternative to the ordinary protein extraction in reversed micelles based on the liquid-liquid extraction. The solid-liquid extraction method was found to facilitate the solubilization of denatured proteins more efficiently in the reversed micellar media than the ordinary phase transfer method of liquid extraction. The refolding of denatured RNase A entrapped in reversed micelles was attained by adding a redox reagent (reduced and oxidized glutathion). Enzymatic activity of RNase A was gradually recovered with time in the reversed micelles. The denatured RNase A was completely refolded within 30 h. In addition, the efficiency of protein refolding was enhanced when reversed micelles were applied to denatured RNase A containing a higher protein concentration that, in the case of aqueous media, would lead to protein aggregation. The solid-liquid extraction technique using reversed micelles affords better scale-up advantages in the direct refolding process of insoluble protein aggregates. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 620-623, 1998.
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    Biotechnology and Bioengineering 57 (1998), S. 610-619 
    ISSN: 0006-3592
    Keywords: dynamic model ; Saccharomyces cerevisiae ; oxidative capacity ; feedback control ; calorimetry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of this study was to characterize the dynamic adaptation of the oxidative capacity of Saccharomyces cerevisiae to an increase in the glucose supply rate and its implications for the control of a continuous culture designed to produce biomass without allowing glucose to be diverted into the reductive metabolism. Continuous cultures subjected to a sudden shift-up in the dilution rate showed that the glucose uptake rate increased immediately to the new feeding rate but that the oxygen consumption could not follow fast enough to ensure a completely oxidative metabolism. Thus, part of the glucose assimilated was degraded by the reductive metabolism, resulting in a temporary decrease of biomass concentration, even if the final dilution rate was below Dcrit. The dynamic increase of the specific oxygen consumption rate, qO2, was characterized by an initial immediate jump followed by a first-order increase to the maximum value. It could be modeled using three parameters denoted qjumpO2, qmaxO2, and a time constant τ. The values for the first two of the parameters varied considerably from one shift to another, even when they were performed under identical conditions. On the basis of this model, a time-dependent feed flow rate function was derived that should permit an increase in the dilution rate from one value to another without provoking the appearance of reductive metabolism. The idea was to increase the glucose supply in parallel with the dynamic increase of the oxidative capacity of the culture, so that all of the assimilated glucose could always be oxidized. Nevertheless, corresponding feed-profile experiments showed that deviations in the reductive metabolism could not be completely suppressed due to variability in the model parameters. Therefore, a proportional feedback controller using heat evolution rate measurements was implemented. Calorimetry provides an excellent and rapid estimate of the metabolic activity. Satisfactory control was achieved and led to constant biomass yields. Ethanol accumulated only up to 0.49 g L-1 as compared to an accumulation of 1.82 g L-1 without on-line control in the shift-up experiment to the same final dilution rate. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 610-619, 1998.
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  • 75
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    Biotechnology and Bioengineering 51 (1996), S. 410-421 
    ISSN: 0006-3592
    Keywords: lysozyme ; thermal stability ; 1H NMR ; conformational flexibility ; melting temperature ; PEG ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reversible folding destabilization of hen lysozyme has been confirmed by a melting temperature (Tm) decrease in aqueous poly(ethylene glycol) (PEG). The percent denatured, extracted from the histidine 15 C2H (H15 C2H) native and denatured peak areas from 500-MHz one-dimensional proton nuclear magnetic resonance (1D 1H NMR) spectra in D2O, was analyzed through denaturation temperatures at 0% and 20% (w/w) PEG 1000. The lysozyme (3.5 mM) Tm decreased by 4.2°C and 7.1°C in 20% (w/w) PEG 1000 at pH 3.8 and 3.0, respectively. The Tm decreased with increasing lysozyme concentration. Additionally, the temperature-induced resonance migrations of 17 protons from 8 residues indicate that the native lysozyme structure undergoes temperature-induced conformational changes. The changes were essentially identical in both 0% and 20% (w/w) PEG 1000 at both pH 3.0 and 3.8. This small, local restructuring of the hydrophobic box region may be a manifestation of temperature-dependent solution hydrophobicity, whereas active-site cleft fluctuations may be due to the inherent active-site flexibility. The lysozyme structure in PEG at 35°C was determined to be essentially native from the 1H nuclear Overhauser effect spectroscopy (NOESY) fingerprint regions. Additionally, lysozyme chemical shifts, from 1D spectra, in PEG 200, 300, and 1000 at 35°C and various concentrations were essentially identical, further confirming that the conformation remains native in various PEG solutions. © 1996 John Wiley & Sons, Inc.
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  • 76
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    Biotechnology and Bioengineering 51 (1996), S. 375-383 
    ISSN: 0006-3592
    Keywords: cellulase ; enzyme recycling ; enzyme adsorption ; lignocellulosic hydrolysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Past technoeconomic modeling work has identified the relatively large contribution that enzymatic hydrolysis adds to the total cost of producing ethanol from lignocellulosic substrates. This cost was primarily due to the high concentration of enzyme and long incubation time that was required to obtain complete hydrolysis. Although enzyme and substrate concentration and end-product inhibition influenced the rate of hydrolysis, the effect was less pronounced during the initial stages of hydrolysis. During this time most of the cellulases were adsorbed onto the unhydrolyzed residue. By recycling the cellulases adsorbed to the residual substrate remaining after an initial 24 h, a high rate of hydrolysis, with low overall residence time and minimal cellulase input, could be achieved for several rounds of enzyme recycle. A comparison of the front end (pretreatment, fractionation, and hydrolysis) of a softwood/hardwood to ethanol process indicated that the lignin associated with the softwood-derived cellulose stream limited the number of times the cellulose containing residue could be recycled. © 1996 John Wiley & Sons, Inc.
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  • 77
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    Biotechnology and Bioengineering 51 (1996), S. 399-409 
    ISSN: 0006-3592
    Keywords: cell damage ; cell culture ; bubble aeration ; agitation ; bubble coalescence and breakup ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been established that the forces resulting from bubbles rupturing at the free air (gas)/liquid surface injure animal cells in agitated and/or sparged bioreactors. Although it has been suggested that bubble coalescence and breakup within agitated and sparged bioreactors (i.e., away from the free liquid surface) can be a source of cell injury as well, the evidence has been indirect. We have carried out experiments to examine this issue. The free air/liquid surface in a sparged and agitated bioractor was eliminated by completely filling the 2-L reactor and allowing sparged bubbles to escape through an outlet tube. Two identical bioreactors were run in parallel to make comparisons between cultures that were oxygenated via direct air sparging and the control culture in which silicone tubing was used for bubble-free oxygenation. Thus, cell damage from cell-to-bubble interactions due to processes (bubble coalescence and breakup) occurring in the bulk liquid could be isolated by eliminating damage due to bubbles rupturing at the free air/liquid surface of the bioreactor. We found that Chinese hamster ovary (CHO) cells grown in medium that does not contain shear-protecting additives can be agitated at rates up to 600 rpm without being damaged extensively by cell-to bubble interactions in the bulk of the bioreactor. We verified this using both batch and high-density perfusion cultures. We tested two impeller designs (pitched blade and Rushton) and found them not to affect cell damage under similar operational conditions. Sparger location (above vs. below the impeller) had no effect on cell damage at higher agitation rates but may affect the injury process at lower agitation intensities (here, below 250 rpm). In the absence of a headspace, we found less cell damage at higher agitation intensities (400 and 600 rpm), and we suggest that this nonintuitive finding derives from the important effect of bubble size and foam stability on the cell damage process. © 1996 John Wiley & Sons, Inc.
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  • 78
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    Biotechnology and Bioengineering 51 (1996), S. 434-438 
    ISSN: 0006-3592
    Keywords: polyphosphate ; Escherichia coli ; phosphate starvation ; gene expression ; heterologous ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of intracellular polyphosphate on the phosphate-starvation response in Escherichia coli was studied by genetically manipulating the intracellular polyphosphate levels and by performing phosphate shifts on the genetically engineered strains. Strains that produced large quantities of polyphosphate and were able to degrade it induced the phosphate-starvation response to a lesser extent than wild-type strains, whereas strains that were unable to degrade a large intracellular polyphosphate pool induced the phosphate-starvation response to a greater extent than wild-type strains. These results have important implications for expression of heterologous genes under control of the phoA promoter. © 1996 John Wiley & Sons, Inc.
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  • 79
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    Biotechnology and Bioengineering 51 (1996), S. 458-465 
    ISSN: 0006-3592
    Keywords: concentric-cylinder shear device ; rotor/stator homogenization ; shear ; shear rate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Shear is present in almost all bioprocesses and high shear is associated with processes involving agitation and emulsification. The purpose of this study is to investigate the effect of high shear and high shear rate on proteins. Two concentric cylinder-based shear systems were used. One was a closed concentric-cylinder shear device (CCSD) and the other was a homogenizer with a rotor/stator assembly. Mathematical modeling of these systems allowed calculation of the shear rate and shear. The CCSD generated low shear rates (a few hundred s-1), whereas the homogenizer could generate very high shear rates (〉 105 s-1). High shear could be achieved in both systems by increasing the processing time. Recombinant human growth hormone (rhGH) and recombinant human deoxyribonuclease (rhDNase) were used as the model proteins in this study. It was found that neither high shear nor high shear rate had a significant effect on protein aggregation. However, a lower melting temperature and enthalpy were detected for highly sheared rhGH by using scanning microcalorimetry, presumably due to some changes in protein's conformation. Also, SDS-PAGE indicated the presence of low molecular-weight fragments, suggesting that peptide bond breakage occurred due to high shear. rhDNase was relatively more stable than rhGH under high shear. No conformational changes and protein fragments were observed. © 1996 John Wiley & Sons, Inc.
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  • 80
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    Biotechnology and Bioengineering 51 (1996), S. 494-499 
    ISSN: 0006-3592
    Keywords: cell metabolism ; baculovirus ; insect cells ; recombinant protein OSF-2 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The properties of Sf9 and Tn5 insect cells were analyzed comparatively under serum-free culture conditions. Sf9 cells in SF900II medium apparently utilized sucrose as a primary nutrient both before and after virus infection, yielding small amounts of lactate and ammonia. Tn5 cells in Excell 401 medium consumed all the nutrients examined, including sucrose. The productivity of a recombinant glycoprotein, OSF-2, by Tn5 cells, was moderate in both monolayer and spinner cultures, but the ability to secrete it was compromised in the former case. Relative to the Tn5 cultures, Sf9 produced 30-fold more OSF-2 in either culture mode. © 1996 John Wiley & Sons, Inc.
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  • 81
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    Biotechnology and Bioengineering 51 (1996), S. 538-543 
    ISSN: 0006-3592
    Keywords: NMR imaging ; biosorption ; alginate ; shrinking core model ; Laminaria ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this contribution, an NMR imaging study of heavy metal absorption in alginate, immobilized-cell biosorbents, and kombu (Laminaria japonica) algal biomass is presented. This method provides the good possibility of directly monitoring the time evolution of the spatial distribution of the ions in the materials. From these results, we demonstrate that rare earth ions are absorbed with a steep reaction front that can be described very well with a modified shrinking core model, while copper ions are absorbed with a more diffuse front.
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  • 82
    ISSN: 0006-3592
    Keywords: oxidoreductase ; chiral alcohol ; racemic resolution ; membrane reactor ; continuous extraction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxidations of alcohols by alcohol dehydrogenases often suffer from low conversions and slow reaction rates due to severe product inhibition. This can be overcome by continuous product extraction, because only the concentrations, but not the kinetic parameters, can be changed. As a consequence, it is favorable to apply a differential circulation reactor with continuous product extraction, where only a small amount of product is formed per cycle. The product is then directly extracted using a microporous hydrophobic hollow fiber membrane. This results in an increase of the relative activity of the dehydrogenase at a given conversion. The reaction investigated is the kinetic resolution of racemic 1-phenyl-1,2-ethanediol by glycerol dehydrogenase (GDH). The resulting oxidation product, 2-hydroxyacetophenone, causes a strong product inhibition. Additionally, it reacts in a chemical reaction with the cofactor lowering its active concentration. Because the GDH needs β-nicotinamide adenine dinucleotide (NAD+) as a cofactor, lactate dehydrogenase is used to regenerate NAD+ from NADH by reducing pyruvate to (L)-lactate. A conversion of 50% with respect to the racemate and an enantiomeric excess 〉99% of the (S)-enantiomer was reached.
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  • 83
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    Biotechnology and Bioengineering 51 (1996), S. 581-590 
    ISSN: 0006-3592
    Keywords: microfiber ; graft polymerization ; DNA immobilization ; immunoadsorbent ; DNA ; anti-DNA antibody ; systemic lupus erythematosus ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilization of DNA to the surface of poly(ethylene terephthalate) (PET) microfibers with a high specific surface area of 0.83 m2/g was carried out to give the fiber surface an affinity for anti-DNA antibody. Following ozone oxidation, the microfibers were subjected to graft polymerization of monomers including acrylic acid, methacryloyloxyethyl phosphate, N,N-dimethylaminoethyl methacrylate, N-vinylformamide, and glycidyl methacrylate. Calf thymus DNA was immobilized to the grafted fiber surface through either covalent binding or polyion complexation with the grafted polymer chains. The highest surface density of DNA immobilized (0.6 μg/cm2) was obtained when DNA was immobilized through formation of phosphodiester linkage between the hydroxyl group of DNA and the phosphate group in grafted poly(methacryloyloxyethyl phosphate) using 1,1-carbonyldiimidazole, or through polyion complexation between the anionic DNA and the cationic grafted poly(N,N-dimethylaminoethyl methacrylate) chains. Batch adsorption of anti-DNA antibody to the grafted PET fibers with and without DNA immobilized on their surface was conducted with serum obtained from systemic lupus erythematosus model mice. The DNA-immobilized PET fibers exhibited a higher adsorption capacity and specificity than the others. In addition, the DNA-immobilized fibers effectively adsorbed human anti-DNA antibody.
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  • 84
    ISSN: 0006-3592
    Keywords: c-jun ; cell cycle ; apoptosis ; antisense ; growth deprivation ; F-MEL ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: F-MEL cells were transfected with the c-jun antisense gene located downstream of a glucocorticoid-inducible MMTV promoter, and the obtained cells were named c-jun AS cells. When the c-jun AS cells were treated with dexamethasone (DEX) in DMEM supplemented with 10% serum, the growth of the cells was completely suppressed for a duration of 16 days with a high cell viability exceeding 86%. The c-jun expression in the c-jun AS cells was suppressed moderately in the absence of DEX and strongly in the presence of DEX. The c-jun AS cells grew well and reached a density of 106 cells/mL without supplementation of any serum components. Viability was greater than 80% after the cells had been cultured for 8 days in the absence of DEX. The c-jun AS cells stayed at a constant cell density and high viability above 80% for 8 days when they were cultured in the presence of DEX under serum deprivation. In contrast, the wild type F-MEL cells were unable to grow and died by apoptosis in 3 days under serum deprivation. Internucleosomal cleavage of DNA, a landmark of apoptosis, was clearly detectable. Thus the c-jun AS cell line that is resistant to apoptosis induced by serum deprivation and can reversibly and viably be growth-arrested was established. A dual-signal model was proposed to explain the experimental result, the interlinked regulation of apoptosis, and growth by c-jun.© 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:65-72, 1998.
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  • 85
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    Biotechnology and Bioengineering 55 (1997), S. 921-926 
    ISSN: 0006-3592
    Keywords: green fluorescent protein ; sensor ; on-line monitoring ; quantitation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present an intensity based sensor designed for on-line monitoring of green fluorescent protein, a revolutionary marker of protein expression. The device consisted of a blue light emitting diode as the excitation source. A band pass excitation filter cut off light longer than 490 nm. The light was directed into a bifurcated optical fiber bundle with the common end inserted into a stainless steel housing equipped with a quartz window. The fiber bundle and stainless steel housing are steam sterilizable. The emission radiation was collected through a long wave pass filter to reject the excitation light shorter than 505 nm and was detected by a photomultiplier tube. The signal was amplified and sent to a computer for recording time course data. The sensor was tested in an Escherichia coli fermentation of JM105 transformed with pBAD-GFP. The on-line signal was compared to off-line fluorescence spectrophotometer measurements. The on-line profile closely followed the off-line. Western blot data showed that with a time shift, the sensor was able to both continuously and quantitatively monitor expression of green fluorescent protein on-line in real time. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55:921-926, 1997.
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  • 86
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    Biotechnology and Bioengineering 55 (1997), S. 909-920 
    ISSN: 0006-3592
    Keywords: baculovirus ; insect cells ; metabolism ; Sf-9; high five™ ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nutrient utilization and byproduct accumulation were monitored in Spodoptera frugiperda Sf-9 and Trichoplusia ni BTI-Tn-5B1-4 (High Five™) cell lines during growth and following viral infection in suspension cultures in order to develop a better understanding of cell metabolism and to acquire information relevant to large scale fed-batch bioreactors. The utilization of glucose, dissolved oxygen, and amino acids were monitored in Sf-9 cell cultures grown in Sf-900 II serum-free medium (SFM) and in High Five™ cell cultures grown in both Sf-900 II and Express Five SFM. Using the optimal medium for each cell line, i.e., Sf-900 II SFM for Sf-9 cells and Express Five SFM for High Five™ cells, the cell growth rate, maximum cell density, specific glucose and glutamine utilization rates, and specific alanine production rate were comparable during cell growth. In addition, the expression level of recombinant human tissue plasminogen activator was comparable in the two cell lines on a per cell basis. It was found, however, that lactate and ammonia accumulated in High Five™ cell cultures, but not in Sf-9 cell cultures. In addition, High Five™ cells utilized asparagine more rapidly than glutamine, whereas Sf-9 cells consumed only minimal asparagine, and the oxygen utilization rate was significantly higher in High Five™ cell cultures. It was also found that the medium had a significant effect on High Five™ cell metabolism, e.g., the specific glucose utilization rate and the specific lactate and alanine production rates were significantly higher in Sf-900 II SFM than in Express Five SFM. In addition, the maximum cell density and specific asparagine utilization rate were significantly higher in Express Five SFM. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55:909-920, 1997.
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  • 87
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    Biotechnology and Bioengineering 55 (1997), S. 940-940 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
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  • 88
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    Biotechnology and Bioengineering 58 (1998), S. 380-386 
    ISSN: 0006-3592
    Keywords: reverse micelles ; cutinase ; deactivation ; conformational changes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Deactivation data and fluorescence intensity changes were used to probe functional and structural stability of cutinase in reverse micelles. A fast deactivation of cutinase in anionic (AOT) reverse micelles occurs due to a reversible denaturation process. The deactivation and denaturation of cutinase is slower in small cationic (CTAB/1-hexanol) reverse micelles and does not occur when the size of the cationic reverse micellar water-pool is larger than cutinase. In both systems, activity loss and denaturation are coupled processes showing the same trend with time. Denaturation is probably caused by the interaction between the enzyme and the surfactant interface of the reversed micelle. When the size of the empty reversed micelle water-pool is smaller than cutinase (at W0 5, with W0 being the water:surfactant concentration ratio) a three-state model describes denaturation and deactivation with an intermediate conformational state existing on the path from native to denaturated cutinase. This intermediate was clearly detected by an increase in activity and shows only minor conformational changes relative to the native state. At W0 20, the size of the empty water-pool was larger than cutinase and the data was well described by a two-state model for both anionic and cationic reverse micelles. For AOT reverse micelles at W0 20, the intermediate state became a transient state and the deactivation and denaturation were described by a two-state model in which only native and denaturated cutinase were present. For CTAB/1-hexanol reverse micelles at W0 20, the native cutinase was in equilibrium with an intermediate state, which did not suffer denaturation. 1-Hexanol showed a stabilizing effect on cutinase in reverse micelles, contributing to the higher stabilities observed in the cationic CTAB/1-hexanol reverse micelles. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:380-386, 1998.
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  • 89
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    Biotechnology and Bioengineering 56 (1997), S. 1-8 
    ISSN: 0006-3592
    Keywords: transesterification ; hydrolysis ; water activity ; cutinase ; gas ; bioreactor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fusarium solani cutinase supported onto Chromosorb P was used to catalyze transesterification (alcoholysis) and hydrolysis on short volatile alcohols and esters in a continuous gas/solid bioreactor. In this system, a solid phase composed of a packed enzymatic preparation was continuously percolated with carrier gas which fed substrates and removed reaction products simultaneously. A kinetic study was performed under differential operating conditions in order to get initial reaction rates. The effect of the hydration state of the biocatalyst on the kinetics was studied for 3 conditions of hydration (aw = 0.2, aw = 0.4 and aw = 0.6), the alcoholysis of propionic acid methyl ester with n-propanol, and for 5 hydration levels (from aw = 0.2 to aw = 0.6) for the hydrolysis of propionic acid methyl, ethyl or propyl esters. F. solani cutinase was found to have an unusual kinetic behavior. A sigmoid relationship between the rate of transesterification and the activity of methyl propionate was observed, suggesting some form of cooperative activation of the enzyme by one of its substrate. For the hydrolysis of short volatile propionic acid alkyl esters, threshold effects on the reaction rate, highly depending on the water activity and the substrate polarity, are reported. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 1-8, 1997.
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  • 90
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    Biotechnology and Bioengineering 56 (1997), S. 9-22 
    ISSN: 0006-3592
    Keywords: condensation reactions ; disaccharides ; equilibria ; glucoamylase ; kinetics ; monosaccharides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Arabinose, fructose, galactose, myo-inositol, lyxose, mannose, ribose, and xylose were incubated individually and with glucose in the presence of Aspergillus niger glucoamylase at pH 4.5 and 45°C. Glucoamylase condenses galactose, glucose, and mannose individually into disaccharides. It also produces mixed disaccharides when each of the eight carbohydrates is incubated with glucose. Many products were identified by gas chromatography of the derivatized reaction mixtures followed by mass spectroscopy of the individual chromatographic peaks. Galacto-, gluco-, or mannopyranosyl rings appear to be present at the nonreducing ends of all the disaccharides produced. Molecules linked through primary hydroxyl groups have the highest equilibrium constants of all products formed, since these bonds are thermodynamically favored. However, glucoamylase is capable of forming bonds with many available hydroxyl groups, as previously demonstrated when it was incubated with glucose alone. Formation rates of different bonds linking different residues vary widely. These results demonstrate that glucoamylase has a wide selectivity toward residues it will condense into disaccharides and toward bonds it will form between them. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 9-22, 1997.
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  • 91
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    Biotechnology and Bioengineering 45 (1995), S. 107-115 
    ISSN: 0006-3592
    Keywords: biofilm ; waste gas treatment ; hydrophobic microporous membrane ; mass transfer ; propene ; Xanthobacter ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel type of bioreactor for waste gas treatment has been designed. The reactor contains a microporous hydrophobic membrane to create a large interface between the waste gas and the aqueous phase. To test the new reactor, propene was chosen because of its high air/water partition coefficient, which causes a low water concentration and hampers its removal from air. Propene transfer from air to a suspension of propene-utilizing Xanthobacter Py2 cells in the membrane bioreactor proved to be controlled by mass transfer in the liquid phase. The resistance of the membrane was negligible. Simulated propene transfer rates agreed well with the experimental data. A stable biofilm of Xanthobacter Py2 developed on the membrane during prolonged operation. The propene flux into the biofilm was 1 × 10-6 mol m-2 s-1 at a propene concentration of 9.3 × 10-2 mol m-3 in the gas phase. © 1995 John Wiley & Sons, Inc.
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  • 92
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    Biotechnology and Bioengineering 45 (1995), S. 97-106 
    ISSN: 0006-3592
    Keywords: antibody integrity ; human monoclonal antibodies ; insect cells ; mammalian cell culture ; proteolytic activity ; protein microheterogeneity ; serum-free media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To investigate the effects of factors secreted by different cell lines on human monoclonal antibody (MAb) integrity, 600 mg of a human MAb, which specifically binds to human erythrocytes, were produced in a perfusion process. After purification by protein A affinity chromatography, the MAb was used for integrity testing in supernatants of several cell lines to investigate their potential to degrade the antibody in the extracellular environment. One insect cell line (IPLB-SF-21 AE) and four mammalian cell lines [CHO K1, BHK-21 (C13), C1271, P3-X63-Ag8.653], all of them commonly used for the production of recombinant proteins, and the human-human-mouse heterohybridoma cell line itself (H-CB-hahE), were adapted to serum-free culture media. For integrity testing all cell lines were cultivated in spinner flasks using serum-free media supplemented with 30 μg mL-1 of purified MAb. MAb integrity was assayed by SDS polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing, both followed by Western blotting, and an antigen binding assay. None of the mammalian cells showed any detectable effects on antibody stability and integrity during exponential growth, whereas isoelectric focusing of monoclonal antibody taken from IPLB-SF-21 AE culture supernatants revealed a new band indicating a partial modification of the MAb by secreted factors of these cells. This observation did not correlate with the total proteolytic activity, which was measured in all supernatants and found to be lowest in the insest cell cultures. For mammalian cell cultures, it could be concluded from these findings that shifts of the antibody microheterogeneity pattern, which can be found normally as a result of variations in different production parameters, are not caused by extracellular factors once the product has been secreted into the supernatant. In addition to their well-known advantages in posttranslational modifications (e.g., formation of complex type N-glycans), mammalian cells appear to be more suitable as expression systems for human monoclonal antibodies to be used in vivo when compared with baculovirus-infected insect cells. © 1995 John Wiley & Sons, Inc.
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  • 93
    ISSN: 0006-3592
    Keywords: buffer exchange ; chromatography ; flow filtration ; dialysis, counter current ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: There are three major methods for buffer exchange of proteins at industrial scale: size exclusion chromatography (SEC), tangential flow filtration (TFF), and countercurrent dialysis (CCD). In order to determine the optimal technology for a given process, a study was done to compare these technologies on a technological and economic basis. This comparison required that new mathematical models be developed which enable the common features of each unit operation to be directly compared. The new concept of a diavolume equivalent for SEC, defined as the inverse of the fractional loading, was also introduced to aid in this comparison. Variables that were examined for each unit operation included range of buffer exchange, dilution of protein solution, yield, buffer requirements, total operating time, throughput, plant space, capital, raw materials, and labor costs. It was found that TFF and CCD have a greater range of buffer exchange than SEC. TFF also provides the advantage that concentration of the protein can readily be accomplished in the same step. For processes of equal batch size and yield, TFF and CCD also provide a two- to five- fold improvement in each of the remaining variables. The major economic advantage in using TFF and CCD over SEC is the decreased plant size required for manufacturing and thus the longer term use of existing facilities. Situations where SEC (or CCD) would be favored over TFF are when protein denaturation occurs in TFF but does not occur in SEC. © 1995 John Wiley & Sons, Inc.
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  • 94
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    Biotechnology and Bioengineering 47 (1995), S. 174-180 
    ISSN: 0006-3592
    Keywords: ultrafiltration membranes ; protein fouling ; BET measurements ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Membrane morphology is compared to protein depostion under passive adsorption and ultrafiltration conditions. Solute resistance of protein deposits for membranes of varying roughness, structure, and permeability can vary dramatically with operating conditions. Using Brunauer-Emmett-Teller adsorption isotherm (BET), study of the internal area and accessibility of several uttrafiltration membranes to protein deposition allows better understanding of the fouling mechanisms and interpretation of adsorbed protein quantities. © 1995 John Wiley & Sons, Inc.
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  • 95
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    Biotechnology and Bioengineering 47 (1995), S. 215-226 
    ISSN: 0006-3592
    Keywords: adsorption ; penicillin ; tetracycline ; cephalosporin ; polymeric sorbents ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of this work was to study the equilibria for adsorption of three antibiotics (penicillin V, tetracycline, and cephalosporin C) from water onto commercially available neutral polymeric sorbents. The pH was observed to be an important factor in adsorption as our results suggest that the neutral forms of penicillin V and cephalosporin C are preferentially adsorbed onto the neutral sorbents. Also, sorbent surface chemistry was observed to be important for adsorption, as the antibiotics adsorbed more favorably (both in terms of affinities and enthalpies) onto the aromatic sorbent as compared to the aliphatic ester sorbent. In addition to these thermodynamic measurements, molecular modeling studies and Monte Carlo simulations suggest that adsorption onto aromatic sorbents may involve specific interactions between the planar regions of the antibiotic molecules and the phenyl rings of the aromatic sorbent. The interaction energies predicted from Monte Carlo simulations were observed to provide qualitative agreement with experimentally determined adsorption affinities. © 1995 John Wiley & Sons, Inc.
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  • 96
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    Biotechnology and Bioengineering 47 (1995), S. 252-260 
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; polyethylene glycol-dextran systems ; electrostatic potential ; hydrophobicity ; surface tension ; polyelectrolytes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In aqueous polyethylene glycol/dextran two-phase systems, the hydrophobicity, free volume, surface tension, and interfacial tension of the phases in equilibrium were measured as a function of pH and ionic strength. These parameters were found to change with pH, but the pattern and magnitude cannot explain the unusual partition of charged macromolecules, observed previously. The electrostatic potential difference was determined by a new experimental approach based on the measurement of the pH difference between the phases at equilibrium. In polyethylene glycol/dextran systems containing sodium chloride as ionized species, the electrostatic potential is not constant in the pH range 2 to 11. The partition behavior of charged macromolecules and its dependence on pH can be explained by the combined action of charge and phase potential. This conclusion was tested with poly-L-glutamate, which partitioned as predicted and in a pattern opposite to positively charged macro- molecules. © 1995 John Wiley & Sons, Inc.
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  • 97
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    Biotechnology and Bioengineering 47 (1995), S. 261-269 
    ISSN: 0006-3592
    Keywords: photosynthesis ; global warming ; CO2 fixation ; photobioreactor ; Spirulina platensis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The photosynthetic performance of a helical tubular photobioreactor (“Biocoil”), incorporating the filamentous cyanobacterium Spirulina platensis, was investigated. The photobioreactor was constructed in a cylindrical shape (0.9 m high) with a 0.25-m2basal area and a photostage comprising 60 m of transparent PVC tubing of 1.6-cm inner diameter (volume = 12.1 L). The inner surface of the cylinder (area = 1.32 m2) was illuminated with cool white fluorescent lamps; the energy input of photosynthetically active radiation(PAR, 400 to 700 nm) into the photobioreactor was 2920 kJ per day. An air-lift system ncorporating 4%CO2 was used to circulate the growth medium in the tubing. The maximum productivity achieved in batch culture was 7.18 g dry biomass per day [0.51 g · d biomass/L · day, or 5.44 g · d biomass/m2(inner surface of cylindrical shape)/day] which corresponded to a photosynthetic (PAR) efficiency of 5.45%. The CO2 was efficiently removed from the gaseous stream; monitoring the CO2 the outlet and inlet gas streams showed a 70% removal of CO2 from the inlet gas over an 8-h period with almost maximum growth rate. © 1995 John Wiley & Sons, Inc.
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  • 98
    ISSN: 0006-3592
    Keywords: anaerobic biodegradation ; polychlorinated aliphatics ; acclimation ; enrichment ; polyurethaneactivated carbon carrier ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The simultaneous biodegradation of toxic compounds in mixtures is a major current concern. To bioremediate a toxic mixture, we designed a strategy combining an ad-sorbent carrier with an ecological and nutritional system which allowed work close to heavily polluted conditions in nature. Starting from a methanogenic community, we developed a microbial consortium acclimated to a mixture of about 30 chlorinated aliphatics in a fixed-film stationary-bed bioreactor. Prior to the establishment of a durable period of dechlorination, an interval of progressive dechlorination of the toxic mixture was observed during which the excess of the toxic compounds was stored on the carrier. The latter, consisting of activated carbon in a polyurethane foam, allowed us to work at concentrations far above the solubility of the toxic compounds (apparent concentrations of about 10 g/L). The complete disappearance of hexachloroethane as well as its lower homologues, penta-, tetra-, and trichloroethane, present in the toxic mixture, was observed. Additionally, octachlorocyclopentene, carbon tetrachloride, trichloro-ethylene, tetrachloroethylene, and hexachloro-1,3-butadiene also completely disappeared. For the four latter compounds, from mass balances in the bioreactor, degradation rates around 10 μmol/L per day were determined with total dechlorination. The enrichment culture thus developed exhibited high degradation performances similar to those reported in the literature for pure or enriched anaerobic microbial cultures in contact with a single toxic compound. The results demonstrate the possibility of concurrent high-rate degradation of several highly chlorinated toxic compounds, under conditions approximating field situations.© 1995 John Wiley & Sons, Inc
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  • 99
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    Biotechnology and Bioengineering 47 (1995), S. 277-287 
    ISSN: 0006-3592
    Keywords: phosphorus removal ; biological ; kinetics ; metabolic model ; polyphosphate ; PHB ; glycogen ; batch reactor, sequenced ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process. In this approach all relevant metabolic reactions underlying the metabolism, considering also components like adenosine triphosphate (ATP) and nic-otinamide-adenine dinucleotide (NADH2) are describedbased on biochemical pathways. As a consequence of the relations between the stoichiometry of the metabolic reactions and the reaction rates of components, the required number of kinetic relations to describe the process is reduced. The model describes the dynamics of the storage compounds which are considered separately from the active biomass. The model was validated in experiments at a constant sludge retention time of 8 days, over the anaerobic and aerobic phases in which the external oncentrations as well as the internal fractions of the relevant components involved in the P-removal process were monitored. These measurements include dissolved acetate, phosphate, and ammonium; oxygen consumption; poly-β-hydroxybutyrate (PHB); glycogen; and active biomass. The model satisfactorily describes the dynamic behavior of all components during the anaerobicand aerobic phases.© 1995 John Wiley & Sons, Inc
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  • 100
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    Biotechnology and Bioengineering 47 (1995), S. 334-346 
    ISSN: 0006-3592
    Keywords: mammalian cells ; glycolysis ; glutarninolysis ; regulation ; kinetic model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of factors have been shown to affect the metabolism of glucose and glutamine in mammalian cells and their mechanisms have been partially elucidated. Despite these efforts, a quantitative knowledge of the significance of these factors, the regulation of glucose and glutamine utilization, and particularly the interactions of these two nutrients is still lacking. Controversies exist in the literature. To clarify some of these controversies, mathematical models are proposed in this work which enable to separate and identify the effects of individual factors. Experimental data from five cell lines obtained in batch, fed-batch, and continuous cultures, both under steady-state and transient conditions, were used to verify the model formulations. The resulting kinetic models successfully describe all these cultures. According to the models, the specific consumption rate of glucose (QGlc) of continuous animal cells under normal culture conditions can be expressed as a sum of three parts: a part owing to cell growth; a part owing to glucose excess; and a part owing to glutamine regulation. The specific consumption rate of glutamine (qGlc7) can be expressed as a sum of only two parts: a part owing to cell growth; and a part owing to glutamine excess. Using the kinetic models the interaction and regulation of glucose and glutamine utilizations are quantitatively analyzed. The results indicate that, whereas qGlc is affected by glutamine, qGln appears to be not or less significantly affected by glucose. It is also shown that the relative utilizations of glucose and glutamine by anabolism and catabolism are mainly affected by the residual concentrations of the respective compounds and are less sensitive to growth rate and the nature of growth limitation.© 1995 John Wiley & Sons, Inc
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