ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Polymer and Materials Science  (112,478)
  • Inorganic Chemistry  (83,671)
  • Landwirtschaft
Collection
Keywords
Language
Years
  • 1
    facet.materialart.
    Unknown
    transcript Verlag | transcript Verlag
    Publication Date: 2024-03-28
    Description: Land Grabbing, die Industrialisierung der Landwirtschaft und damit einhergehende Konflikte um Land nehmen seit Mitte der 2000er Jahre stetig zu. Landarbeiter*innen sind zentrale Akteure in diesem Kontext, finden in der wissenschaftlichen und entwicklungspolitischen Debatte jedoch kaum Beachtung. Jan Brunner nimmt sich dieser Leerstelle an und erforscht in seiner Studie des Zuckerrohrsektors die Auswirkungen agrarindustrieller Transformationen auf Landarbeiter*innen im Bundesstaat São Paulo (Brasilien). Aus arbeitssoziologischer und klassentheoretischer Perspektive analysiert er, wie sich Arbeitsverhältnisse sowie Arbeitskämpfe verändern und welche Herausforderungen, aber auch Chancen sich dadurch für die Organisierung und Kämpfe von Landarbeiter*innen ergeben.
    Keywords: Arbeit ; Arbeitskampf ; Klassenkampf ; Land Grabbing ; Transformation ; Konflikt ; Landwirtschaft ; Agrarindustrie ; Brasilien ; Gewerkschaft ; Landarbeit ; Zuckerrohr ; Wirtschaft ; Globalisierung ; Konfliktforschung ; Arbeits- und Industriesoziologie ; Arbeitsökonomie ; Lateinamerika ; Politikwissenschaft ; Work ; Labour Struggle ; Class War ; Conflict ; Agriculture ; Agricultural Industry ; Brazil ; Labour Union ; Land Work ; Sugar Cane ; Economy ; Globalization ; Conflict Studies ; Sociology of Work and Industry ; Labour Economics ; Latin America ; Political Science ; thema EDItEUR::G Reference, Information and Interdisciplinary subjects::GT Interdisciplinary studies::GTU Peace studies and conflict resolution ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology::JHBL Sociology: work and labour ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCF Labour / income economics
    Language: German
    Format: image/jpeg
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    Frontiers Media SA
    Publication Date: 2024-04-04
    Description: The Frontiers in Chemistry Editorial Office team are delighted to present the inaugural “Frontiers in Chemistry: Rising Stars” article collection, showcasing the high-quality work of internationally recognized researchers in the early stages of their independent careers. All Rising Star researchers featured within this collection were individually nominated by the Journal’s Chief Editors in recognition of their potential to influence the future directions in their respective fields. The work presented here highlights the diversity of research performed across the entire breadth of the chemical sciences, and presents advances in theory, experiment and methodology with applications to compelling problems. This Editorial features the corresponding author(s) of each paper published within this important collection, ordered by section alphabetically, highlighting them as the great researchers of the future. The Frontiers in Chemistry Editorial Office team would like to thank each researcher who contributed their work to this collection. We would also like to personally thank our Chief Editors for their exemplary leadership of this article collection; their strong support and passion for this important, community-driven collection has ensured its success and global impact.
    Keywords: Green and Sustainable Chemistry ; Analytical Chemistry ; Theoretical and Computational Chemistry ; Polymer Chemistry ; Medicinal and Pharmaceutical Chemistry ; Organic Chemistry ; Nanoscience ; Catalysis and Photocatalysis ; Supramolecular Chemistry ; Electrochemistry ; Inorganic Chemistry ; Chemical Biology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues
    Language: English
    Format: image/jpeg
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    Böhlau
    Publication Date: 2024-04-09
    Description: Taking the province of Niederdonau as an example, this pioneer study highlights everyday fields-of-force between National Socialism and agrarian society in which rural actors competed for resources among themselves and with official functionaries. The megaproject of ‘volkish productivism’ – the creation of an efficient peasantry in ‘racial’ and economic terms – got stuck with regard to technical development. However, with regard to institutional development, there emerged a pathway towards an alternative modernity beyond Liberalism and Communism.
    Description: Diese Pionierstudie beleuchtet am Beispiel des Reichsgaues Niederdonau alltägliche Kräftefelder zwischen Nationalsozialismus und Agrargesellschaft, in denen ländliche Akteure untereinander und mit Funktionsträgern um Ressourcen rangen. Das Entwicklungsprojekt des ‚völkischen Produktivismus‘ – die Erzeugung eines „rassisch“ und wirtschaftlich leistungsfähigen „Bauerntums“ – blieb zwar in technischer Hinsicht stecken. Jedoch stellte es in institutioneller Hinsicht die Weichen der Agrarentwicklung in Richtung einer alternativen Moderne jenseits von Liberalismus und Kommunismus.
    Keywords: agrarian society ; agriculture ; everyday life ; productivism ; National Socialism ; Second World War ; Austria ; Agrargesellschaft ; Landwirtschaft ; Alltagsleben ; Produktivismus ; Nationalsozialismus ; Zweiter Weltkrieg ; Österreich ; Hektar ; Reichsmark ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning
    Language: German
    Format: image/jpeg
    Format: image/jpeg
    Format: image/jpeg
    Format: image/jpeg
    Format: image/jpeg
    Format: image/jpeg
    Format: image/jpeg
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2021-03-29
    Description: Die entwässerungsbasierte Nutzung von Moorstandorten führt einerseits zu einer erheblichen Emission von Treibhausgasen und andererseits zum Verlust der Ökosystemdienstleistungen und Lebensraumfunktionen eines naturnahen Moores. Zur Wiederherstellung von landwirtschaftlich vorgenutzten Hochmoorbiotopen fehlen bisher strukturierte, wissenschaftliche Erkenntnisse. Anders als ehemalige Torfabbau- oder Ödlandflächen waren intensiv genutzte landwirtschaftliche Flächen bisher nicht Ziel von großflächigen und wissenschaftlich begleiteten Wiederherrichtungsmaßnahmen. Vorrangiges Ziel des Projekts „OptiMoor – Erprobung und Entwicklung der Sanierung von landwirtschaftlich vorgenutzten Hochmooren zur Erhöhung der Biodiversität und Kohlenstoffspeicherung“ ist die Entwicklung eines Leitfadens für die Wiederherstellung von Hochmoorbiotopen nach intensiver landwirtschaftlicher Nutzung. Darin werden Maßnahmen beschrieben, die sich als erfolgsversprechend für die Umwandlung von Hochmoorgrünland zurück in ein naturnahes Hochmoorökosystem erwiesen haben. Das Projekt wird gefördert im Rahmen eines „Erprobungs- und Entwicklungsvorhabens“ des Bundesamts für Naturschutz sowie im durch das EFRE Förderprogramms „Klimaschutz durch Moorentwicklung“ des Landes Niedersachsens.
    Description: DFG, SUB Göttingen, DGMT
    Description: conference
    Keywords: 553.21 ; conference report ; Tagungsbericht ; Landwirtschaft ; land-use ; Moor ; Torf ; peat ; peatland ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2021-03-29
    Description: Apart from the traditional contribution of geographers to the study of population, this particular thesis attempts to divert the emphasis of geographical enquiry towards the examination of how particular innovations affect the population distribution and the organization of human society. It deals specifically with questions concerning the demographic, social and economic impact of population mobility on both sending in receiving areas. It attempts to shed light on the different variables that work to produce a selective type of population mobility within a particular socio—economic set-up. Although various aspects of population mobility have been studied in some detail during the present decade, no attempt has been made, however, towards a concrete presentation of its multiple causes and its socio-economic impact on the areas and people that are left behind. Far from assuming complete coverage of all interrelated fields of study we attempt here to draw attention t0 the expected socio-economic repercussions of population mobility as induced by a particular factor, namely agricultural mechanization. Certain limitations‚ however, have made it difficult to deal with every aspect of population mobility in the Sudan.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 910 ; Wanderungen {Entwicklungsländerforschung} ; Wirtschaft {Entwicklungsländerforschung} ; Sudan {Geographie} ; Mechanisierung ; Landwirtschaft ; Mobilität ; Landwirtschaft ; Mechanisierung ; Mobilität ; FID-GEO-DE-7
    Language: English
    Type: monograph_digi
    Format: V, 287 Seiten, 2 Karten
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Reimer Verlag Berlin
    In:  Herausgeberexemplar | QA = 4 Z GEOGR 107:51
    Publication Date: 2021-03-29
    Description: Die vorliegende Arbeit stellt ein Konzept zur Bestimmung der Tragfähigkeit in nomadisch genutzten Weidegebieten vor, das es erlaubt, Weide-Öko-Nutzungs-Systeme zu beschreiben, zu evaluieren und ihre Leistungsfähigkeit weitgehend zu quantifizieren. Am Fallbeispiel einer Untersuchungsregion in Zentralsomalia werden die Charakteristika und Potentiale des Natur- sowie des Wirtschaftsraumes analysiert und in einen synthetischen Zusammenhang gestellt. Die Erfassung des Naturraumes beinhaltet neben der quantitativen Bemessung der Weideressourcen auch die qualitative Bewertung des Weidezustandes. Daneben sind die vielschichtigen ökonomischen und ökologischen Implikationen, die das tatsächliche Weidenutzungspotential bestimmen, aufgezeigt. Lösungsansätze zur Erhaltung der bestehenden Weideressourcen werden angeboten, die auf der Basis der nomadischen Perzeption der Umweltproblematik erarbeitet wurden. Das vorgeschlagene Konzept zeichnet sich dadurch aus, dass die Erhebungen mit relativ geringem Aufwand bewerkstelligt werden können und dennoch eine sehr detaillierte Datenbasis erzielen.
    Description: thesis
    Description: DFG, SUB Göttingen
    Keywords: 910 ; Somalia {Geographie} ; Nomadismus ; Weidewirtschaft ; Landwirtschaft ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 344
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2021-03-29
    Description: Summary: Most of the Emsland moorlands finally vanished with the „Emsland plan“. The foundation of settlements in the 17th and 18th century which stagnated in poor development, picked up again under the aegis of the Prussian government. Wasteland cultivation, internal colonisation and economic exploitation of peat became guiding principles in the „conquest“ of the moors, not only of the Emsland district or northwest Germany. This development was interrupted by the Second World War. Acting as a consequence of the necessity to create living space for refugees in the post-war period, the moor cultivation grew into a space reform of an unimaginable degree, especially in the districts of the Emsland and Grafschaft Bentheim. The present essay investigates the different stages of this development and shows the research desiderata according to the latest state of research.
    Description: Zusammenfassung: Mit dem Emslandplan verschwand der größte Teil der emsländischen Moore als Naturraum endgültig. Was mit Siedlungsgründungen im 17. und 18. Jahrhundert begann und lange Jahre in ärmlicher Entwicklung stagnierte, nahm unter der Ägide der preußischen Regierung Fahrt auf. Ödlandkultivierung, Binnenkolonisation und wirtschaftliche Nut zung der Torfe wurden zu Leitmotiven der „Eroberung“ der Moore, nicht nur des Emslandes oder Nordwestdeutschlands. Diese Entwicklung wurde durch den Zweiten Welt krieg unterbrochen. In der Nachkriegszeit, aus der Not heraus forciert Lebensraum für Flüchtlinge zu schaffen, erwuchs die Moorkultivierung in der Zeit des Wirtschaftswunders vor allem in den Landkreisen Emsland und Grafschaft Bentheim zu einer Raumneuordnung unvorstellbaren Ausmaßes. Der vorliegende Aufsatz folgt diesen Entwicklungsschritten und zeigt anhand des aktuellen Forschungsstandes die Forschungsdeside rata auf.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; Torf ; Torfabbau ; Landwirtschaft ; land-use ; Emsland ; peatland ; peat ; peatmining ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2021-03-29
    Description: Abstract: The effects of different grassland management on vegetation pattern and yield potential were investigated in a long-term study on a low peat site typical for the county of Mecklenburg (Northeast-Germany). For this purpose we varied nutrient supply and the utilisation regime (cutting and grazing). Recordings of weathering data and soil water table were additional used to explain water-supply effects on grassland yields. Utilisation and K-supply were identified as the strongest predictors of vegetation patterns, whereas above ground biomass depends mainly from water supply during mid and late summer despite of significant management effects. We concluded that distinguishing between combined effects of vegetation utilisation and site condition water supply had necessarily to taken into account to got reliable information about grassland yield on drained low peat soils.
    Description: Zusammenfassung: In einer langjährigen Studie auf einem für Mecklenburg typischen Niedermoorstandort sind die Auswirkungen verschiedener Bewirtschaftungen auf den Pflanzenbestand und dessen Ertragsfähigkeit untersucht worden. Variiert wurden die Nährstoffversorgung und die Nutzung. Die Aufzeichnung von Witterung und Grundwasserflurabständen dienten der Abschätzung der Einflüsse des Wasserdargebotes auf den Ertrag. Der markanteste Einfluss auf die botanische Zusammensetzung des Grünlandes ging von der Nutzungsart und der Kalium-Düngung aus. Der Ertrag (bei Schnitt ohne Düngung 69 dt TM ha-1, mit NPK-Düngung 100 dt TM ha-1 und bei Weide ohne Düngung 59 dt TM ha-1, mit NPK-Düngung 74 dt TM ha-1) wurde hingegen ungeachtet signifikanter Bewirtschaftungseffekte am stärksten vom Wasserdargebot während der Sommermonate beeinflusst. Es wird gefolgert, dass für die Beurteilung der Ertragsfähigkeit von dränierten Niedermoorstandorten sowohl Nutzung als auch Witterung zu berücksichtigen sind, um zu realitätsnahen Richtwerten zu gelangen.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; Niedermoor ; land-use ; vegetation ; Landwirtschaft ; fen ; peatland ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2021-03-29
    Description: Summary: In some fen areas in Brandenburg, the landscape element is marked by narrow grassland areas which are separated from each other at regular intervals by ditches accompanied by trees and bushes. These structures, which characterise the landscape, are often the Rimpau bog sand-cover cultivation structured in the eighties of the 19th century. Rimpau bog sand-cover cultivation is an amelioration of fens for agriculture. Due to the high returns bog sand-cover cultivation spread very quickly in Germany at the time. Through subsequent ameliorative measures, most of the former 10,000 ha of bog sand-cover cultivation were modified or disappeared. Today there are only a few examples of this cultivation in its original condition. They are worth to be preserved as monuments of rural engineering and species-rich biotopes.
    Description: Zusammenfassung: In einigen Niedermoorgebieten Brandenburgs ist das Landschaftsbild von schmalen Grünlandflächen gekennzeichnet, die durch gehölzbestandene Gräben in regelmäßigem Abstand voneinander getrennt sind. Diese landschaftsprägenden Strukturen sind meist die in den 80er Jahren des 19. Jahrhunderts angelegten Rimpau’schen Moordammkulturen. Die Rimpau’sche Moordammkultur ist ein kulturtechnisches Verfahren, mit dem durch Besandung Niedermoorstandorte für eine ackerbauliche Nutzung erschlossen wurden. Wegen der damit erzielten höheren Erträge, verbreitete sich die Moordammkultur damals sehr schnell in Deutschland. Durch spätere Meliorationen sind von den ehemals etwa 10.000 ha Moordammkulturen die meisten verändert worden bzw. verschwunden. Heute gibt es nur noch wenige Beispiele dieser Kulturen im Originalzustand. Sie sind als Denkmale der Kulturtechnik und artenreiche Biotope als „Kulturhistorische Landschaftselemente“ erhaltenswert.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Brandenburg ; land-use ; Landwirtschaft ; Moor ; peatland ; Geschichte ; history ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    Unknown
    Centre for Development Studies (ZELF), Institute of Geographical Sciences, Freie Universität Berlin
    Publication Date: 2021-03-29
    Description: The mechanism of granting Economic Land Concessions (ELCs) to (inter-)national investors for agro-industrial exploitation was the starting point of a wave of large-scale land acquisitions in Cambodia since the Royal Government of Cambodia (RGC) issued a respective directive in 2005. While ELCs are supposed to combine overall economic benefits on the one hand with poverty reduction and the compliance with environmental standards on the other hand, it turned out that there is a wide gap between the legal framework, which is supposed to govern the granting of ELCs, and its actual implementation on the ground. Eventually, the granting of ELCs led to severe human rights violations and several land conflicts, involving the local population, investor companies, political and economic elites as well as authorities. This situation is especially difficult for the Indigenous Peoples of Cambodia, who not just struggle to claim rights to their lands, but for whom land is also an essential component of livelihood. Drawing on a literature review and the results of a two-month field study, this thesis aims at shedding light at the relationship between different actors of society and land as a resource in the context of asymmetrical power constellations within the land conflict of Samot Leu Village in Seda Commune, Lumphat District, Ratanakiri Province.
    Description: Stiftung der Deutschen Wirtschaft (sdw)
    Description: research
    Keywords: 910 ; Kambodscha ; Landwirtschaft ; FID-GEO-DE-7
    Language: English
    Type: monograph , publishedVersion
    Format: 60
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    facet.materialart.
    Unknown
    Selbstverlag des 2. Geographischen Instituts der Freien Universität Berlin
    In:  Herausgeberexemplar (FU Berlin) | ZB 20559:11
    Publication Date: 2021-03-29
    Description: research
    Description: DFG, SUB Göttingen, FU Berlin
    Keywords: 554 ; 910 ; 910.02 ; Frankreich ; Agrargeografie ; Landwirtschaft ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 102
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Publication Date: 2021-03-29
    Description: Abstract: The RIMPAU bog sand-cover cultivation was created in 1862 in the usually very shallow fens of the Drömling area. The objective had been to use these areas for agriculture. The shallowness of the fen made it possible to take the cover sand from the underground spreading it then on the dikes. For deep fen areas it became necessary to modify the process bringing in the sand from the mineral rim. However, difficulties arose from subsidence due to drainage and the sand load, the characteristics of the bog substrate and the grain size composition of the cover sand. Economic reasons, however, the agriculture bog sand-cover cultivation area was transformed into grassland. Today there are only a few examples of cultivated areas of this type left in their original shape. The bog sand-cover cultivations of SCHREYER in Wendemark may be considered an exception. The moderately deep to deep, highly degraded and nutrient-rich bog had been the deciding factor for creating the bog sand-cover cultivation. In the wake of collectivization of agriculture the bog sand-cover cultivations were filled in and large harvesting units were created. The location remained in fields und a transformation into grass land is not yet planned.
    Description: Zusammenfassung: Die RIMPAU‘sche Moordammkultur wurde im Jahre 1862 im überwiegend sehr flachgründigen Niedermoor des Drömling entwickelt. Ziel war es, hier Ackerbau betreiben zu können. Die Flachgründigkeit des Moores gestattete es, den Decksand aus dem Untergrund zu entnehmen und auf den Moordämmen zu verkarren. Für die tiefgründigen Moorstandorte war es erforderlich, das Verfahren dahingehend zu modifizieren, dass der Decksand aus dem Mineralrand herangeholt wurde. Probleme bereiteten hier bald die Moorsackung durch Entwässerung und Sandauflast, die Beschaffenheit der Moorsubstrate und die Korngrößenzusammensetzung des Decksandes. Ökonomische Gründe bewirkten jedoch, dass die Acker-Moordammkulturen in Grünland umgewandelt wurden. Es gibt heute nur noch wenige Beispiele, wo ein Originalzustand dieser Kulturen vorhanden ist. Eine Ausnahme sind die Moordammkulturen SCHREYER‘s in Wendemark. Das mitteltiefgründige, hochzersetzte und nährstoffreiche Moor war entscheidend für die Anlage der Acker-Moordammkulturen. Nach der Kollektivierung der Landwirtschaft wurden die Moordammgräben verfüllt und große Schlageinheiten eingerichtet. Die Standorte verblieben weiterhin in Ackernutzung und eine Umwandlung in Grünland war nicht vorgesehen.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: 553.21 ; Moor ; peatland ; history ; Geschichte ; land-use ; Landwirtschaft ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    facet.materialart.
    Unknown
    Selbstverlag des 2. Geographischen Instituts der Freien Universität Berlin
    In:  SUB Göttingen, Überlassung des Instituts für Geographische Wissenschatfen der Freien Universität Berlin
    Publication Date: 2021-03-29
    Description: Das Ziel der vorliegenden Arbeit war, das jahreszeitlich wechselnde Bild ausgewählter britischer Agrarlandschaften an Hand von sieben Repräsentativbetrieben zu untersuchen. Unter Berücksichtigung der statischen Komponenten wurde die jahreszeitliche Rhythmik der Agrarlandschaft durch ihre dynamische Komponente, die Arbeit in der Landwirtschaft, erfaßt. Die Untersuchung erfolgte mit Hilfe der Arbeitsmethode von G. JENSCH (1957) bei einer Weiterentwicklung derselben; die von Jensch benutzten „Arbeitsdiagramme“ wurden in der Weise differenziert, daß sowohl Arbeitsart wie Arbeit an bestimmten Feldfrüchten und Tieren auf ihnen abzulesen ist. Danach wurde versucht, den räumlichen Bezug von diesen Arbeitsdiagrammen zur Agrarlandschaft zu finden. Zu diesem Zweck wurden Flurkarten der einzelnen Betriebe entworfen, die in 15 Darstellungen für jedes Feld das jeweilige Erscheinungsbild im Verlaufe eines Jahres darstellen. Ein Vergleich der beiden Darstellungen zeigt für jedes Flurstück durch die Art der Arbeit und die damit verbundene, für jede Frucht typische Veränderung des Feldes das Ausmaß und «den Zeitpunkt der Veränderung der Flur an. Damit konnte eine direkte Aussage über den Zustand und die Zustandsänderung der gesamten Flur, die mit Hilfe der Diagramme allein nur indirekt möglich war, gemacht werden. Für jeden der sieben Betriebe, die etwa auf einer SE-NW-Achse von Kent bis Sutherland zu suchen sind, wurde sein Arbeitsrhythmus mit Hilfe des für ihn entworfenen Arbeitsdiagrammes erklärt, danach die hierdurch hervorgerufene Veränderung in der Flur erläutert und ein regionaler Vergleich der einzelnen Arbeitsarten, ihrer Einsatztermine und Arbeitsandauer gegeben. Nach einer vergleichenden Beschreibung des Arbeitsaufwandes und Arbeitsrhythmus im Verlaufe des Jahres wurde schließlich im Vergleich aller sieben Repräsentativbetriebe versucht, unter Zuhilfenahme der Ergebnisse aus Arbeitsdiagrammen und Flurkarten die für jeden Betrieb geltende Rhythmik seines Landschaftsbildes darzustellen und mit denen der anderen Betriebe zu vergleichen. Hierdurch wurde erstmalig auf dem durch G. JENSCH angeregten Wege die mit Hilfe der Arbeit in der Landwirtschaft exakt meßbare jahresrhythmische Zustandsänderung der Flur für einige Agrarlandschaften einzeln und vergleichend dargestellt.
    Description: research
    Description: DFG, SUB Göttingen, FU Berlin
    Keywords: 554 ; 910.02 ; Agrarlandschaft ; Landwirtschaft ; Britannien ; FID-GEO-DE-7
    Language: German
    Type: monograph_digi
    Format: 62
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Publication Date: 2021-03-29
    Description: Die meisten Moore in Nordwestdeutschland werden seit mehreren Jahrhunderten landwirtschaftlich genutzt. Die Kultivierungsverfahren der Moore entscheiden, welche Nutzungen möglich sind. Tiefumbruchböden lassen sich vielfältig, überwiegend als Acker nutzen. Auf den Schwarzkulturen dominiert heute die standortgerechte Grünlandnutzung, wobei die nicht standortgerechte, ackerbauliche Nutzung in jüngster Zeit zugenommen hat. Mit zunehmender Intensität der Flächenbewirtschaftung verschlechtern sich die Torfeigenschaften und durch Mineralisierung der Torfe treten Höhenverluste auf. Die Grenzen der Befahrbarkeit bzw. Trittfestigkeit werden häufig erreicht. In der Nährstoffdynamik unterscheiden sich Hoch- und Niedermoore. Bei der extensiven Grünlandnutzung, verbunden mit reduzierter Entwässerungsintensität, bereiten häufig Flatterbinse (Juncus effusus) und Rasenschmiele (Deschampsia caespitosa) Probleme. Neue Nutzungsverfahren der Paludikultur befinden sich noch in der Entwicklung und Erprobung. Eine dauerhafte Sicherung der Produktionsstandorte für landwirtschaftliche Nutzungen ist auf Tiefumbruchböden möglich.
    Description: report
    Keywords: 553.21 ; Moor ; land-use ; Landwirtschaft ; peatland ; FID-GEO-DE-7
    Language: German
    Type: article , publishedVersion
    Format: 19
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    facet.materialart.
    Unknown
    Institut für Geographie und Geologie der Universität Greifswald
    Publication Date: 2022-01-11
    Description: Trotz relativ guter physiogeographischer Rahmenbedingungen fällt die Landwirtschaft Mecklenburg-Vorpommerns nach Wertschöpfung, Flächenproduktivität, Subventionseffektivität weit hinter die der westlichen Bundesländer zurück. Ursachen sind unter anderem die Inflexibilität und Unproduktivität übergroßer Unternehmen, die Dominanz billiger Massenproduktion und der Verzicht der Großbetriebe auf die Bedienung nachfragestarker Marktsegmente im ökologischen und hochqualitativen Bereich. Die Subventionierung und Privilegierung der großbetrieblich strukturierten Agrarindustrie muss abgebaut, die Förderung innovativer kleiner und mittlerer bäuerlicher Betriebe intensiviert werden. Die Infrastruktur in Ländlichen Räumen muss wachstumsorientiert für Landwirtschaft, Tourismus, hochwertiges Wohnen und seniorenbezogene Dienstleistungen ausgebaut werden.
    Description: In spite of relatively good general conditions and good soils, agriculture in Mecklenburg-Vorpom-mern is the only economic sector in the state whose gross value added has not seen a positive development in the last 20 years. Mecklenburg-Vorpommern’s agricultural sector stagnates at a low level and with a productivity of only 613 euros per hectare at 31.7 per cent below the German average. One of the most significant causes for this are the large farming businesses which are specialised in cheap mass production. Low area productivity is a result of inadequate flexibility of the large farming companies when it comes to reacting to market signals. Whilst smaller farms, which dominate agriculture in West Germany, can adjust their productive alignment relatively quickly or diversify to mix their income, large farming businesses try to avoid changes or put them off for as long as possible. The form of production, which is dominated by industrial farming, and the marginalisation of small and medium-sized farms as a result of land speculation and price dumping, cause the federal state of Mecklenburg-Vorpommern regional economic damages of at least € 250 million annually. The subsidisation and privileged treatment of industrial farming has to be cut down on as quickly as possible. We propose a new model of cooperation in rural areas called “Garden of metropolises”. It combines small and medium sized farms, preferably family farms, with tourism, leisure, high quality service, medium and high standard of living.
    Description: Fraktion Bündnis 90/Die Grünen im Landtag von Mecklenburg-Vorpommern
    Description: Unternehmerverband MiLaN, Wietzow
    Description: research
    Description: research
    Keywords: 910 ; QGB 570 ; QER 250 ; Mecklenburg-Vorpommern {Geographie} ; Agrar- und Forstgeographie {Wirtschaftsgeographie} ; Landwirtschaft ; Ländliche Räume ; Mecklenburg-Vorpommern
    Language: German
    Type: map , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-02-10
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Polynitrogens have the potential for ultrahigh-performing explosives or propellants because singly or doubly bonded polynitrogens can decompose to triply bonded dinitrogen (N2) with an extraordinarily large energy release. The large energy content and relatively low activation energy toward decomposition makes the synthesis of a stable polynitrogen allotrope an extraordinary challenge. Many elements exist in different forms (allotropes)—for example, carbon can exist as graphite, diamond, buckyballs, or graphene. However, no stable neutral allotropes are known for nitrogen, and only two stable homonuclear polynitrogen ions had been isolated until now—namely, the N3− anion (1) and the N5+ cation (2). On page 374 of this issue, Zhang et al. (3) report the synthesis and characterization of the first stable salt of the cyclo-N5− anion, only the third stable homonuclear polynitrogen ion ever isolated. Author: Karl O. Christe
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Publication Date: 2024-02-28
    Description: Abstract: In Germany, more than 70% of peat soils are used for agriculture. Due to drainage and utilization, these peat soils have considerable environmental impact. Drainage-based use also leads to continuous peat mineralization and subsidence and over time to a loss of productive land. In an expert meeting (16 - 18 June 2016), organized by the MoorDialog project (Greifswald Mire Centre) and the DGMT, representatives from agriculture, water management, research, and nature conservation discussed the ‘good professional practice’ of agricultural use of peat soils in Germany. The overarching goal should be to secure the availability of productive land. As the management of peat soils also affects the provision of other ecosystem services such as climate and water protection, a good professional practice must consider and balance all these benefits. The expert meeting explored criteria for water management and land management to define good professional practice in societal consensus. Finally, the necessary changes of legal and economic frameworks were discussed. This paper can be the basis for a broad discussion in the political arena.
    Description: Zusammenfassung: In Deutschland werden mehr als 70% der Moorböden landwirtschaftlich genutzt. Von der mit der Bewirtschaftung verbundenen Entwässerung gehen meist erhebliche Umweltbelastungen aus, die im Widerspruch zu internationalen Vorgaben und nationalen Vorschriften stehen. Die entwässerungsbasierte Nutzung von Moorböden führt zur kontinuierlichen Abnahme des Höhenniveaus und damit über die Zeit zu einem Verlust an Kulturland. Auf einem vom Projekt MoorDialog (Greifswald Moor Centrum) und der DGMT organisierten Fachgespräch vom 16. bis 18. Juni 2016 haben Vertreter aus Land- und Wasserwirtschaft, Wissenschaft sowie Natur- und Umweltschutz diskutiert, was eine gute fachliche Praxis der Nutzung von landwirtschaftlich genutzten Moorböden in Deutschland beinhalten sollte. Als übergeordnetes Ziel wurde definiert, heutiges Kulturland dauerhaft als nutzbares Land zu erhalten. Die Bewirtschaftung von Moorstandorten beeinflusst neben der Produktionsfunktion die Bereitstellung von anderen gesellschaftsrelevanten Ökosystemleistungen wie den Klima- und Gewässerschutz und die Lebensraumfunktion für einheimische Organismen. Im Rahmen einer guten fachlichen Praxis sollten diese Leistungen berücksichtigt und integral abgewogen werden. Als Ergebnis des Fachgesprächs wurden Kriterien für die Steuerung des Wasserhaushalts und das Flächenmanagement sondiert, anhand derer eine gute fachliche Praxis definiert und im gesellschaftlichen Konsens vereinbart werden kann. Abschließend werden die dafür notwendigen Änderungen der rechtlichen und ökonomischen Rahmenbedingungen diskutiert. Der vorliegende Entwurf soll als Grundlage für eine breite Diskussion im politischen Raum dienen.
    Description: DFG, SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; ddc:630.914 ; Moor ; peatland ; land-use ; Landwirtschaft ; peat ; Torf ; soil ; Boden
    Language: German
    Type: doc-type:article , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-09-09
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-11-11
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    facet.materialart.
    Unknown
    Geozon Science Media
    Publication Date: 2021-03-29
    Description: Es ist das Bemühen des Naturparks, seiner Mitarbeiter und des Fördervereins, das ihnen anvertraute Gebiet und sein Umfeld in seiner Entstehungsgeschichte darzustellen. Durch Tun und Lassen wandelte sich die einst waldreiche Naturlandschaft schrittweise zu einer immer stärker vom Menschen geprägten Kulturlandschaft (Ellenberg 1990). Anfangs waren es die Steinzeit-, Bronze- und Eisenzeitmenschen und dann die Slawen, die ihre heute noch erkennbaren Spuren in unserem Raum hinterließen, z.B. Grabanlagen, alte Burgwälle, Dorfnamen. Mit der Besiedlung des Slawenlandes durch deutsche Bauern ab dem 13. Jh. kam es zur Gründung neuer Dörfer unterschiedlichen Typs, wodurch auch die Naturlandschaft stark verändert wurde. Die sich ständig zahlreicher, umfangreicher und vielfältiger gestaltenden menschlichen Ansiedlungen wurden immer mehr zu einem wesentlichen Bestandteil unseres Gebietes.
    Description: research
    Keywords: 910 ; QGB 570 ; Kulturgeographie {Norddeutschland} ; Siedlungsgeografie ; Kulturgeschichte ; Ländlicher Raum ; Landwirtschaft ; Landesgeschichte ; Naturpark Nossentiner/Schwinzer Heide ; Mecklenburg-Vorpommern
    Language: German
    Type: anthology , publishedVersion
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Publication Date: 2012
    Description: Analysen zum Auftreten des Kohlschotenrüßlers in Raps der Vergangenheit und Abschätzungen zum Befall in der Zukunft mit Ensembleläufen verschiedener Klimamodelle KATASTER-BESCHREIBUNG: Beschreibung der Biologie (Überwinterungsdauer, Erstauftreten und Aktivität) der Kohlschotenrüßlers (Ceutorhynchus pallidactylus (Mrsh.)) in Raps in Luxemburg, Auswertung historischer Daten für 1961-90 und Vergleich mit Szenarienzeiträumen (2021-50 bzw. 2069-2098), Bandbreite der Simulationen aus 5 Globalen Klimamodellen (GCM) mit A1B und weiter regionalisiert (25x25km) mit 6 regionalen Klimamodellen KATASTER-DETAIL: Für die Zeit 2090-2099 im Vergleich zu 1980-1999 prognostizieren die GCM bei dem Szenario A1B eine Temperaturzunahme um 2.8 °C (Bandbreite 1.7 bis 4.4 °C) Delta T, dann Auftreten des Kohlschotenrüsslers um 3.3 Tage pro Dekade eher
    Keywords: Großherzogtum Luxemburg ; 1961-90 ; Szenarien ; Klima ; Landwirtschaft ; Pflanzenschädling ; Raps
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    facet.materialart.
    Unknown
    In:  Münster: proPlant GmbH. http://www.proplant.de/data/2010/ 2010_12_Volk-Richthofen-Johnen_Abschlussbericht- Klimawandel-und-Pflanzenschutz_proPlant.pdf
    Publication Date: 2010
    Description: Infektionsrisiko für pilzliche, bakterielle und tierische Schädlinge bei Weizen, Winterraps, Kartoffeln, Zuckerrüben und Mais werden für das Szenario A1B abgeschätzt KATASTER-BESCHREIBUNG: Schwerpunkt auf den 8 bedeutensten Krankheiten bei Weizen, Halmbruch, Mehltau, Septoria-Blattdürre, Gelbrost, Braunrost, DTR-Blattdürre, Septoria nodorum und Fusarium, Simulationen mit proPlant.expert und Einteilung in Trendklassen (1-5) von linearer Trend ansteigend (=1) bis abnehmend (=5) KATASTER-DETAIL: Tmit+ (Wettreg 2006, A1B), dann ansteigendes Risiko für Septoria tritici, Braunrost, Mehltau, Fusarium, für Halmbruch und DTR kein ansteigendes Risiko ermittelt Detaillierte Trendübersicht und Beurteilung für einzelne Kulturen und Regionen in NRW siehe Dokument, Anhang
    Keywords: Nordrhein-Westfalen ; 2001-2050 ; Insekten ; Zuckerrüben ; Kartoffeln ; Infektionskrankheiten ; Landwirtschaft ; Mais ; Niederschlag ; Pflanzenkrankheit ; Pflanzenschädling ; Temperatur ; Weizen ; Raps ; Modell
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    facet.materialart.
    Unknown
    In:  Global Change Biology (2007) 13, 1550–1564, doi: 10.1111/j.1365-2486.2007.01394.x
    Publication Date: 2007
    Description: Biologie zum Auftreten und der Ausbreitung verschiedener Läusearten (Blatt, Baumlaus etc) durch Auswertung europaweiter Fallen, Ableitungen eines statistischen Ansatzes durch Verschneiden geografischer, klimatischer und Landnutzngsindikatoren mit dem Auftreten bestimmter Aphis-Aten, Hochrechnungen für die Zukunft KATASTER-BESCHREIBUNG: Zusammenhang zwischen den Läuseflug und der Umwelt wurde anhand von Fallenfunden über die am EXAMINE-Projekt beteiligten Länder, bzw. Partner geschätzt, Verschneiden geografischer, klimatischer und Landnutzngsindikatoren mit dem Flugverhalten, Herleiten eines stat. Models KATASTER-DETAIL: Delta T+, dann erwarteter Läuseflug in den nächsten 50 Jahren etwa 8 Tage eher Regressionsmodel: Julian Day=137.976+0.000023574*ARABLE + 0.0000390578xGRASS + 0.0000287559xSEA + 0.000102947xWATER -3.36069xC30DAY - 6.44658xC30P60DAY +0.0524365xDECPRN +0.108988xFEBRN + 0.0590551xNOVPRN ARABLE=Arable land (area in ha in a circle of R575 km), GRASS=Grassland (area in ha in a circle of R575 km), SEA=Sea (area in ha in a circle of R575 km), WATER=Inland waters (area in ha in a circle of R575 km), C30DAY=Mean temperature of the mean coldest 30 days, P60DAY=Mean temperature of the 60 days immediately after the mean coldest 30, DECPRN=Mean rainfall during the previous December, FEBRN=Mean rainfall during February, NOVPRN=Mean rainfall during the previous November
    Keywords: Europa ; 1970-2006, Szenarien ; Insekten ; Landwirtschaft ; Parasit ; Modell
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    facet.materialart.
    Unknown
    In:  2 -NAP 02-231 Bericht IV Interreg IIIA Literaturstudie alpine Kulturpflanzen Vs. 3.0 070425.
    Publication Date: 2007
    Description: Sammlung historischer Informationen und Dokumentation des bäuerlichen Erfahrungswissens Kulturpflanzen von der Prähistorie - 20. Jahrhundert KATASTER-BESCHREIBUNG: KATASTER-DETAIL:
    Keywords: Südtirol, Nordtirol und GraubündenSüdtirol, Nordtirol und Graubünden ; Kartoffeln ; Anbautermine ; Boden ; Ertrag ; Getreide ; Hafer ; Klima ; Landwirtschaft ; Mais ; Niederschlag ; Pflanzenkrankheit ; Pflanzenschädling ; Roggen ; Temperatur ; Trockenheit ; Vegetationsperiode ; Weizen ; Wetterbeobachtung ; Witterung ; Düngung ; Hackfrüchte
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    facet.materialart.
    Unknown
    In:  Diss., Sozialwissenschaftliche Schriften zur Landnutzung und ländlichen Entwicklung, no. 62. Margraf Verlag. , Kapitel 4
    Publication Date: 2005
    Description: Beschreibung der Entstehung des landwirtschaftlichen Wissens und der Entwicklung der Wissensvermittlung KATASTER-BESCHREIBUNG: - KATASTER-DETAIL: -
    Keywords: Baden-Württemberg ; 800 v. Chr. bis 1945 ; Ertrag ; Getreide ; Landwirtschaft
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 0006-3525
    Keywords: folding type-specific secondary structure propensities ; amino acids ; α-helical proteins ; β sheet proteins ; α/β proteins ; α+β proteins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Folding type-specific secondary structure propensities of 20 naturally occurring amino acids have been derived from α-helical, β-sheet, α/β, and α+β proteins of known structures. These data show that each residue type of amino acids has intrinsic propensities in different regions of secondary structures for different folding types of proteins. Each of the folding types shows markedly different rank ordering, indicating folding type-specific effects on the secondary structure propensities of amino acids. Rigorous statistical tests have been made to validate the folding type-specific effects. It should be noted that α and β proteins have relatively small α-helices and β-strands forming propensities respectively compared with those of α+β and α/β proteins. This may suggest that, with more complex architectures than α and β proteins, α+β and α/β proteins require larger propensities to distinguish from interacting α-helices and β-strands. Our finding of folding type-specific secondary structure propensities suggests that sequence space accessible to each folding type may have differing features. Differing sequence space features might be constrained by topological requirement for each of the folding types. Almost all strong β-sheet forming residues are hydrophobic in character regardless of folding types, thus suggesting the hydrophobicities of side chains as a key determinant of β-sheet structures. In contrast, conformational entropy of side chains is a major determinant of the helical propensities of amino acids, although other interactions such as hydrophobicities and charged interactions cannot be neglected. These results will be helpful to protein design, class-based secondary structure prediction, and protein folding. © 1998 John Wiley & Sons, Inc. Biopoly 45: 35-49, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 69-83 
    ISSN: 0006-3525
    Keywords: DNA branched junctions ; branch migration ; superhelical torque ; control of DNA structure ; endonuclease VII ; nanomechanical device ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: DNA branched junctions are analogues of Holliday junction recombination intermediates. Partially mobile junctions contain a limited amount of homology flanking the branch point. A partially mobile DNA branched junction has been incorporated into a synthetic double-stranded circular DNA molecule. The junction is flanked by four homologous nucleotide pairs, so that there are five possible locations for the branch point. Two opposite arms of the branched junction are joined to form the circular molecule, which contains 262 nucleotides to the base of the junction. This molecule represents a system whereby torque applied to the circular molecule can have an impact on the junction, by relocating its branch point. Ligation of the molecule produces two topoisomers; about 87% of the product is a relaxed molecule, and the rest is a molecule with one positive supercoil. The position of the branch point is assayed by cleaving the molecule with endonuclease VII. We find that the major site of the branch point in the relaxed topoisomer is at the maximally extruded position in the relaxed molecule. Upon the addition of ethidium, the major site of the branch point migrates to the minimally extruded position. © 1998 John Wiley & Sons, Inc. Biopoly 45: 69-83, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    ISSN: 0006-3525
    Keywords: conformation ; aggregation ; κ-carrageenan ; flow field-flow fractionation ; multiangle light scattering ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relatively novel combination of flow field-flow fractionation (FFF) and multiangle light scattering (MALS) was employed to study a nondegraded κ-carrageenan in different 0.1M salt solutions. The applicability of the technique was tested, and the effects of salt type and salt composition on the molar mass and radius of gyration were studied. A conformational ordering was induced at room temperature by switching the solvent from 0.1M NaCl (coil form) to 0.1M NaI (helix form). An approximate doubling of the average molar mass and an increase in radius of gyration was then observed, in agreement with results obtained previously using size exclusion chromatography-MALS. This increase in size was attributed to conformational ordering and to the formation of double helices. Severe aggregation was observed above 40% CsI in the 0.1M mixed salt solution of CsI and NaI. This was ascribed to the association of helices into large aggregates. For these large associates, having molar masses of several millions, a reversal of the elution order in flow FFF was detected. © 1998 John Wiley & Sons, Inc. Biopoly 45: 85-96 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 119-133 
    ISSN: 0006-3525
    Keywords: conformations of D-alanyl-D-alanine ; β-lactam ; structural overlay ; AMBER force field ; AM1 ; ab initio ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article a conformational analysis of the D-alanyl-D-alanine dipeptide, both charged and neutral, has been carried out. The preferred conformations were determined by means of ab initio and semiempirical quantum, together with empirical force field calculations. The AMBER* force field and the 6-31 + G** and 6-31G** ab initio levels give rise to a coincident minimum energy structure, which, on the other hand, differs from that determined by AM1, 3-21 + G, and 3-21G. The solvent effect on the different charged and neutral conformations have been considered through the AMSOL semiempirical method. A quantification regarding the structural similarities between the different dipeptide conformations and the ampicillin has been performed. The results show that the best overlay is attained by the minimum structure energy obtained by using the 6-31 + G** methodology, which presents a planar amidic nitrogen. © 1998 John Wiley & Sons, Inc. Biopoly 45: 119-133, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 0006-3525
    Keywords: chemical oxidation ; cellulose ; conformational transition ; capillary viscosity ; microcalorimetry ; calcium ions ; gels ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behavior of different molecular weight fractions of a synthetic C6-oxidized derivative of cellulose were investigated by means of capillary viscometry, CD, and microcalorimetric measurements. Experiments were carried out in the presence of either monovalent or divalent counterions.The experimental data indicated that C6-oxidized cellulose can assume an ordered extended conformation at low ionic strength, induced by the intrachain repulsions of negative charges. This conformation was suggested to be very similar to the fully extended structure of cellulose. In addition to this, upon increasing the ionic strength, a conformational transition of the order-to-disorder type occurred. In fact, the screening of the electrostatic repulsions introduced a number of conformational kinks into the cellulosic backbone, which enabled the polymer to assume a more coiled conformation hence producing less viscous aqueous solutions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 157-163, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 0006-3525
    Keywords: conformational stability ; biological polyelectrolytes ; enthalpy ; entropy ; conformational transitions ; carrageenan ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method is proposed for the determination of the enthalpy and entropy changes of nonionic origin upon conformational transition of linear biopolyelectrolytes in solution. For all transition midpoints, defined by given temperature and ionic strength, the total free energy change of the system is zero, which means that the nonionic contribution to the free energy change is equal in value and opposite in sign to the polyelectrolytic one. The counterion condensation theory of linear polyelectrolytes provides for the appropriate analytical expression to be used in such calculations. Linear plots of the proper functions of the calculated free energy changes vs the proper functions of temperature allows for the determination of the enthalpic and entropic terms of the nonionic free energy change of transition.The method has been applied to the extensive available data of the ion-induced conformational change of κ-carrageenan, a linear sulfated galactan extracted from seaweeds. The method has proved very successful, with the results showing a remarkable convergency of the enthalpy values for different monovalent counterions. On the other hand, the above approach has made it possible to explain the known effect of counterion specificity on the transition by a small difference in the nonionic entropic contributions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 203-216, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 0006-3525
    Keywords: uv resonance Raman spectroscopy ; Raman cross section ; hypochromism ; DNA ; deoxynucleoside ; protein ; aromatic amino acid ; virus assembly ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ultraviolet resonance Raman (UVRR) spectra of H2O and D2O solutions of the nucleoside (dA, dG, dC, dT) and aromatic amino acid (Phe, Trp, Tyr) constituents of DNA viruses have been obtained with laser excitation wavelengths of 257, 244, 238, and 229 nm. Using the 981 cm-1 marker of Na2SO4 as an internal standard, Raman frequencies and scattering cross sections were evaluated for all prominent UVRR bands at each excitation wavelength. The results show that UVRR cross sections of both the nucleosides and amino acids are strongly dependent on excitation wavelength and constitute sensitive and selective probes of the residues. The results provide a library of UVRR marker bands for structural analysis of DNA viruses and other nucleoprotein assemblies. © 1998 John Wiley & Sons, Inc. Biopoly 45: 247-256, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 0006-3525
    Keywords: hemoglobin ; hexagonal bilayer ; Lumbricus ; electron microscopy ; three-dimensional reconstruction ; small-angle x-ray scattering ; three-dimensional models ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quaternary structure of Lumbricus terrestris hemoglobin was investigated by small-angle x-ray scattering (SAXS). Based on the SAXS data from several independent experiments, a three-dimensional (3D) consensus model was established to simulate the solution structure of this complex protein at low resolution (about 3 nm) and to yield the particle dimensions. The model is built up from a large number of small spheres of different weights, a result of the two-step procedure used to calculate the SAXS model. It accounts for the arrangement of 12 subunits in a hexagonal bilayer structure and for an additional central unit of cylinder-like shape. This model provides an excellent fit of the experimental scattering curve of the protein up to h = 1 nm-1 and a nearly perfect fit of the experimental distance distribution function p(r) in the whole range. Scattering curves and p(r) functions were also calculated for low-resolution models based on 3D reconstructions obtained by cryoelectron microscopy (EM). The calculated functions of these models also provide a very good fit of the experimental scattering curve (even at h 〉 1 nm-1) and p(r) function, if hydration is taken into account and the original model coordinates are slightly rescaled. The comparison of models reveals that both the SAXS-based and the EM-based model lead to a similar simulation of the protein structure and to similar particle dimensions. The essential differences between the models concern the hexagonal bilayer arrangement (eclipsed in the SAXS model, one layer slightly rotated in the EM model), and the mass distribution, mainly on the surface and in the central part of the protein complex. © John Wiley & Sons, Inc. Biopoly 45: 289-298, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 0006-3525
    Keywords: conformational changes ; vicinal glycosylation ; branched α-l-Rhap(1-2)[β-d-Galp(1-3)]-β-d-Glc1-OMe trisaccharide ; parent disaccharides ; hydrogen bond ; isotope effect ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformations of the α-l-Rhap(1-2)-β-d-Glc1-OMe and β-d-Galp(1-3)-β-d-Glc1-OMe disaccharides and the branched title trisaccharide were examined in DMSO-d6 solution by 1H-nmr. The distance mapping procedure was based on rotating frame nuclear Overhauser effect (NOE) constraints involving C- and O-linked protons, and hydrogen-bond constraints manifested by the splitting of the OH nmr signals for partially deuteriated samples. An “isotopomer-selected NOE” method for the unequivocal identification of mutually hydrogen-bonded hydroxyl groups was suggested. The length of hydrogen bonds thus detected is considered the only one motionally nonaveraged nmr-derived constraint. Molecular mechanics and molecular dynamics methods were used to model the conformational properties of the studied oligosaccharides. Complex conformational search, relying on a regular Φ,Ψ-grid based scanning of the conformational space of the selected glycosidic linkage, combined with simultaneous modeling of different allowed orientations of the pendant groups and the third, neighboring sugar residue, has been carried out. Energy minimizations were performed for each member of the Φ,Ψ grid generated set of conformations. Conformational clustering has been done to group the minimized conformations into families with similar values of glycosidic torsion angles. Several stable syn and anti conformations were found for the 1→2 and 1→3 bonds in the studied disaccharides. Vicinal glycosylation affected strongly the occupancy of conformational states in both branches of the title trisaccharide. The preferred conformational family of the trisaccharide (with average Φ,Ψ values of 38°, 17° for the 1→2 and 48°, 1° for the 1→3 bond, respectively) was shown by nmr to be stabilized by intramolecular hydrogen bonding between the nonbonded Rha and Gal residues. © 1998 John Wiley & Sons, Inc. Biopoly 46: 417-432, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 489-492 
    ISSN: 0006-3525
    Keywords: refractive index increment ; proteins ; solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The refractive index increment of a protein solution is a property not only of the protein, but also of the solvent. This is demonstrated theoretically and confirmed experimentally using analytical interferometry. © 1998 John Wiley & Sons, Inc. Biopoly 46: 489-492, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 1-1 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 0006-3525
    Keywords: hepatitis A ; synthetic peptides ; CD ; liposomes ; computational study ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present study was undertaken to examine the structural features that may be important to explain the immunogenicity of the (110-121) peptide sequence (FWRGDLVFDFQV) of VP3 capsid protein of hepatitis A virus. A conformational analysis of the preferred conformations by CD and molecular mechanics was carried out. Present results suggest that the interaction with liposomes as biomembrane model induces and stabilizes the amphipathic β-structure of the peptide.To study the contribution of amino acid replacements at the RGD tripeptide as well as the influence of the peptide chain length on peptide conformation, solid-phase peptide synthesis of several peptide analogs was carried out and the peptide conformation was studied using CD spectroscopy. The results show that the RGD sequence is necessary to induce the β-structure in the presence of liposomes. © 1998 John Wiley & Sons, Inc. Biopoly 45: 479-492, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 31-37 
    ISSN: 0006-3525
    Keywords: DNA liquid crystals ; DNA fragments ; screened Coulomb interactions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric-isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye-Hückel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan-Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm. © 1998 John Wiley & Sons, Inc. Biopoly 46: 31-37, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 245-252 
    ISSN: 0006-3525
    Keywords: gelatin ; gelation ; atomic force microscopy ; interfacial rheology ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gelation of gelatin under various conditions has been followed by atomic force microscopy (AFM) with the objective of understanding more fully the structure formed during the gelation process. AFM images were obtained of the structures formed from both the bulk sol and in surface films during the onset of gelation. While gelation occurred in the bulk sol, the extent of helix formation was monitored by measurements of optical rotation, and the molecular aggregation was imaged by AFM. Interfacial gelatin films formed at the air-water interface were also studied. Measurements of surface tension and surface rheology were made periodically and Langmuir-Blodgett films were drawn from the interface to allow AFM imaging of the structure of the interfacial layer as a function of time. Structural studies reveal that at low levels of helical content the gelatin molecules assemble into aggregates containing short segments of dimensions comparable to those expected for gelatin triple helices. With time larger fibrous structures appear whose dimensions suggest that they are bundles of triple helices. As gelation proceeds, the number density of fibers increases at the expense of the smaller aggregates, eventually assembling into a fibrous network. The gel structure appears to be sensitive to the thermal history, and this is particularly important in determining the structure and properties of the interfacial films. © 1998 John Wiley & Sons, Inc. Biopoly 46: 245-252, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 65-81 
    ISSN: 0006-3525
    Keywords: nucleotide analogue interference mapping ; phosphorothioate ; group I intron ; interference suppression ; RNA ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review I will outline several chemogenetic approaches used to determine the chemical basis of large ribozyme function and structure. The term chemogenetics was first used to describe site-specific functional group modification experiments in the analysis of DNA-protein interactions. Within the past few years equivalent experiments have been performed on large catalytic RNAs using both single-site substitution and interference mapping techniques with nucleotide analogues. While functional group mutagenesis is an important aspect of a chemogenetic approach, chemical correlates to genetic revertants and suppressors must also be realized for the genetic analogy to be intellectually valid and experimentally useful. Several examples of functional group revertants and suppressors have now been obtained within the Tetrahymena group I ribozyme. These experiments define an ensemble of tertiary hydrogen bonds that have made it possible to construct a detailed model of the ribozyme catalytic core. The model includes a functionally important monovalent metal ion binding site, a wobble-wobble receptor motif for helix-helix packing interactions, and a minor groove triple helix. © 1998 John Wiley & Sons, Inc. Biopoly 48: 65-81, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 83-96 
    ISSN: 0006-3525
    Keywords: nucleic acid ; disulfide cross-link ; structure ; dynamics ; stability ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review I discuss straightforward and general methods to modify nucleic acid structure with disulfide cross-links. A motivating factor in developing this chemistry was the notion that disulfide bonds would be excellent tools to probe the structure, dynamics, thermodynamics, folding, and function of DNA and RNA, much in the way that cystine cross-links have been used to study proteins. The chemistry described has been used to synthesize disulfide cross-linked hairpins and duplexes, higher order structures like triplexes, nonground-state conformations, and tRNAs. Since the cross-links form quantitatively by mild air oxidation and do not perturb either secondary or tertiary structure, this modification should prove quite useful for the study of nucleic acids. © 1998 John Wiley & Sons, Inc. Biopoly 48: 83-96, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 113-135 
    ISSN: 0006-3525
    Keywords: divalent cations ; magnesium ; RNA ; ion binding ; RNA folding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Divalent cations, like magnesium, are crucial for the structural integrity and biological activity of RNA. In this article, we present a picture of how magnesium stabilizes a particular folded form of RNA. The overall stabilization of RNA by Mg2+ is given by the free energy of transferring RNA from a reference univalent salt solution to a mixed salt solution. This term has favorable energetic contributions from two distinct modes of binding: diffuse binding and site binding. In diffuse binding, fully hydrated Mg ions interact with the RNA via nonspecific long-range electrostatic interactions. In site binding, dehydrated Mg2+ interacts with anionic ligands specifically arranged by the RNA fold to act as coordinating ligands for the metal ion. Each of these modes has a strong coulombic contribution to binding; however, site binding is also characterized by substantial changes in ion solvation and other nonelectrostatic contributions. We will show how these energetic differences can be exploited to experimentally distinguish between these two classes of ions using analyses of binding polynomials. We survey a number of specific systems in which Mg2+-RNA interactions have been studied. In well-characterized systems such as certain tRNAs and some rRNA fragments these studies show that site-bound ions can play an important role in RNA stability. However, the crucial role of diffusely bound ions is also evident. We emphasize that diffuse binding can only be described rigorously by a model that accounts for long-range electrostatic forces. To fully understand the role of magnesium ions in RNA stability, theoretical models describing electrostatic forces in systems with complicated structures must be developed. © 1999 John Wiley & Sons, Inc. Biopoly 48: 113-135, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 0006-3525
    Keywords: 1H-nmr ; molecular modeling ; peptaibol ; peptide-lipid interaction ; sodium dodecyl sulfate micelles ; trichorzianin TA VII ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trichorzianin TA VII, Ac0 U1 A2 A3 U4 J5 Q6 U7 U8 U9 S10 L11 U12 P13 V14 U15 I16 Q17 Q18 Fol19, is a nonadecapeptide member of the peptaibol antibiotics biosynthesized by Trichoderma soil fungi, which is characterized by a high proportion of the α,α-dialkylated amino acids, α-aminoisobutyric acid (Aib, U) and isovaline (Iva, J), an acetylated N-terminus and a C-terminal phenylalaninol (Pheol, Fol). The main interest in such peptides stems from their ability to interact with phospholipid bilayers and form voltage-dependent transmembrane channels in planar lipid bilayers. In order to provide insights into the lipid-peptide interaction promoting the voltage gating, the conformational study of TA VII in the presence of perdeuterated sodium dodecyl sulfate (SDS-d25) micelles has been carried out. 1H sequential assignments have been performed with the use of two-dimensional homo- and -heteronuclear nmr techniques including double quantum filtered correlated spectroscopy, homonuclear Hartmann-Hahn, nuclear Overhauser effect spectroscopy, 1H-13C heteronuclear single quantum correlation, and heteronuclear multiple bond correlation. Conformational parameters, such as 3JNHCαH coupling constants, temperature coefficients of amide protons (Δδ/ΔTNH) and quantitative nuclear Overhauser enhancement data, lead to detailed structural information. Ninety-eight three-dimensional structures consistent with the nmr data were generated from 231 interproton distances and six Φ dihedral angle restraints, using restrained molecular dynamics and energy minimization calculations. The average rms deviation between the 98 refined structures and the energy-minimized average structure is 0.59 Å for the backbone atoms. The structure of trichorzianin TA VII associated with SDS micelles, as determined by these methods, is characterized by two right-handed helical segments involving residues 1-8 and 11-19, linked by a β-turn that leads to an angle about 90°-100° between the two helix axes; residues 18 and 19 at the end of the C-terminal helix exhibit multiple conformations. © 1998 John Wiley & Sons, Inc. Biopoly 46: 75-88, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    ISSN: 0006-3525
    Keywords: 9-hydroxyellipticine ; DNA ; CD ; linear dichroism ; resonance light scattering ; intercalation ; drug-drug interactions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of 9-hydroxyellipticine to calf thymus DNA, poly[d(A-T)]2, and poly-[d(G-C)]2 has been studied in detail by means of CD, linear dichroism, resonance light scattering, and molecular dynamics. The transition moment polarizations of 9-hydroxyelliptiycine were determined in polyvinyl alcohol stretched film. Spectroscopic solution studies of the DNA/drug complex are combined with theoretical CD calculations using the final 50 ps of a series of molecular dynamics simulations as input. The spectroscopic data shows 9-hydroxyellipticine to adopt two main binding modes, one intercalative and the other a stacked binding mode involving the formation of drug oligomers in the DNA major groove. Analysis of the intercalated binding mode in poly[d(A-T)]2 suggests the 9-hydroxyellipticine hydroxyl group lies in the minor groove and hydrogen bonds to water with the pyridine ring protruding into the major groove. The stacked binding mode was examined using resonance light scattering and it was concluded that the drug was forming small oligomer stacks rather than extended aggregates. Reduced linear dichroism measurements suggested a binding geometry that precluded a minor groove binding mode where the plane of the drug makes a 45° angle with the plane of the bases. Thus it was concluded that the drug stacks in the major groove. No obvious differences in the mode of binding of 9-hydroxyellipticine were observed between different DNA sequences; however, the stacked binding mode appeared to be more favorable for calf thymus DNA and poly[d(G-C)]2 than for poly[d(A-T)]2, an observation that could be explained by the slightly greater steric hindrance of the poly[d(A-T)]2 major groove. A strong concentration dependence was observed for the two binding modes where intercalation is favored at very low drug load, with stacking interactions becoming more prominent as the drug concentration is increased. Even at DNA : drug mixing ratios of 70:1 the stacked binding mode was still important for GC-rich DNAs. © 1998 John Wiley & Sons, Inc. Biopoly 46: 127-143, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 169-179 
    ISSN: 0006-3525
    Keywords: macromolecular carriers ; drug targeting and delivery ; branched chain synthetic polypeptides ; membrane-synthetic polypeptide interaction ; lipid monolayers/bilayers ; polymer therapeutics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface properties at the air/water interface and the interaction of branched chain polymeric polypeptides with a general formula poly[Lys-(DL-Alam-X1)], where X = Π (AK), Ser (SAK), or Glu (EAK), with phospholipids were investigated. Polylysine derivatives with polycationic (SAK, AK) or amphoteric (EAK) were capable to spread and form stable monomolecular layers. The stability of monolayers at the air/water interface was dependent on the side-chain terminal amino acid residue of polymers and can be described by SAK 〈 AK 〈 EAK order. The area per amino acid residue values calculated from compression isotherms were in the same range as compared to those of linear poly-α-amino acids and proteins. Moreover, these polymers interact with phospholipid monomolecular layers composed of dipalmitoyl phosphatidyl choline (DPPC) or DPPC/PG (PG: phosphatidyl glycerol; 95/5, mol/mol). Data obtained from compression isotherms of phospholipids spread on aqueous polymer solutions at different initial surface pressure indicated that insertion into lipid monolayers for SAK or AK is more pronounced than for EAK. The interaction between branched polypeptides and phospholipid membranes was further investigated using lipid bilayers with DPPC/PG and fluorescent probes located either at the polar surface [1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) sodium anilino naphthalene sulfonate (ANS)] or within the hydrophobic core (DPH) of the liposome. Changes in fluorescence intensity and in polarization were observed when TMA-DPH or ANS, but not DPH were used. Comparative data also indicate that all three polymers interact only with the outer surface of the bilayer, but even the most marked penetration of polycationic polypeptide (SAK) did not result in alteration of the ordered state of the alkyl chains in the bilayer. Taken together, data obtained from mono- or bilayer experiments suggest that the interaction between branched polymers and phospholipids are highly dependent on the charge properties (Ser vs Glu) and on the identity (Ser vs Ala) of side-chain terminating amino acids. The binding of polymers to the model membranes could be mainly driven by electrostatic forces, but the significant role of hydrophilic properties in case of SAK cannot be excluded. © 1998 John Wiley & Sons, Inc. Biopoly 46: 169-179, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 0006-3525
    Keywords: Cα,α-dialkylated glycines ; molecular dynamics ; geometry and conformation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between the local backbone conformation and bond angles at Cα of symmetrically substituted Cα,α-dialkylated glycines (Cα,α-dimethylglycine or α-aminoisobutyric acid, Aib; Cα,α-diethylglycine, Deg; Cα,α-di-n-propylglycine, Dpg) has been investigated by molecular dynamics (MD) simulation adopting flat bottom harmonic potentials, instead of the usual harmonic restraints, for the Cα bond angles. The MD simulations show that the Cα bond angles are related to the local backbone conformation, irrespectively of the side-chain length of Aib, Deg, and Dpg residues. Moreover, the N-Cα-C′ (τ) angle is the most sensitive conformational parameter and, in the folded form, is always larger and more flexible than in the extended one. © 1998 John Wiley & Sons, Inc. Biopoly 46: 239-244, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 319-327 
    ISSN: 0006-3525
    Keywords: methionine ligation ; parathyroid hormones ; biomimetic ligation ; S-methylation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In biological systems, both proteolysis and aminolysis of amide bonds produce activated intermediates through acyl transfer reactions either inter- or intramolecularly. Protein splicing is an illustrative example that proceeds through a series of catalyzed acyl transfer reactions and culminates at an O- or S-acyl intermediate. This intermediate leads to an uncatalyzed acyl migration to form an amide bond in the spliced product. A ligation method mimicking the uncatalyzed final steps in protein splicing has been developed utilizing the acyl transfer amide-bond feature for the blockwise coupling of unprotected, free peptide segments at methionine (Met). The latent thiol moiety of Met can be exploited using homocysteine at the α-amino terminal position of a free peptide for transthioesterification with another free peptide containing an α-thioester to give an S-acyl intermediate. A subsequent, proximity-driven S- to N-acyl migration of this acyl intermediate spontaneously rearranges to form a homocysteinyl amide bond. S-methylation with excess p-nitrobenezensulfonate yields Met at the ligation site. The methionine ligation is selective and orthogonal, and is usually completed within 4 h when performed at slightly basic pH and under strongly reductive conditions. No side reactions due to acylation were observed with any other α-amines of both peptide segments as seen in the synthesis of parathyroid hormone peptides. Furthermore, cyclic peptide can also be obtained through the same strategy by placing both homocysteine at the amino terminus and the thioester at the carboxyl terminus in an unprotected peptide precursor. These biomimetic ligation strategies hold promise for engineering novel peptides and proteins. © 1998 John Wiley & Sons, Inc. Biopoly 46: 319-327, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 359-373 
    ISSN: 0006-3525
    Keywords: boundary element method ; DNA electrophoresis ; electrophoretic mobility of DNA ; free solution electrophoretic mobility of DNA ; ion relaxation, DNA electrophoresis ; modeling electrophoresis of polyions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boundary element methods are used to model the free solution electrophoretic mobility of short DNA fragments. The Stern surfaces of the DNA fragments are modeled as plated cylinders that reproduce translational and rotational diffusion constants. The solvent-accessible and ion-accessible surfaces are taken to be coincident with the Stern surface. The mobilities are computed by solving simultaneously the coupled Navier-Stokes, Poisson, and ion-transport equations. The equilibrium electrostatics are treated at the level of the full Poisson-Boltzmann equation and ion relaxation is included. For polyions as highly charged as short DNA fragments, ion relaxation is substantial. At .11 M KCl, the simulated mobilities of a 20 base pair DNA fragment are in excellent agreement with experiment. At .04 M Tris acetate, pH = 8.0, the simulated mobilities are about 10-15% higher than experimental values and this discrepancy is attributed to the relatively large size of the Tris counterion. The length dependence of the mobility at .11 M KCl is also investigated. Earlier mobility studies on lysozyme are reexamined in view of the present findings. In addition to electrophoretic mobilities, the effective polyion charge measured in steady state electrophoresis and its relationship to the preferential interaction parameter γgG is briefly considered. © 1998 John Wiley & Sons, Inc. Biopoly 46: 359-373, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 341-346 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    ISSN: 0006-3525
    Keywords: diffusional encounter ; Brownian dynamics ; average Boltzmann factor ; acetylcholinesterase ; Poisson-Boltzmann ; electrostatics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The utility of the average Boltzmann factor around the active site of an enzyme as the predictor of the electrostatic enhancement of the substrate binding rate is tested on a set of data on wild-type acetylcholinesterase and 18 charge mutants recently obtained by Brownian dynamics simulations. A good correlation between the average Boltzmann factors and the substrate binding rate constants is found. The effects of single charge mutations on both the Boltzmann factor and the substrate binding rate constant are modest, i.e., 〈5 fold increase or decrease. This is consistent with the experimental results of Shafferman et al. but does not support their suggestion that the overall rate of the catalytic reaction is not limited by the diffusional encounter of acetylcholinesterase and its substrate. © 1998 John Wiley & Sons, Inc. Biopoly 45: 355-360, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 469-478 
    ISSN: 0006-3525
    Keywords: molecular dynamics ; hydrated proteins ; crystal structures ; density distributions ; globular proteins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using molecular dynamics simulations of fully hydrated proteins and analysis of crystal structures contained in the Protein Data Bank, we develop a transferable set of perpendicular radial distribution functions for water molecules around globular proteins. These universal functions may be used to reconstruct the unique three-dimensional solvent density distribution around every individual protein with a modest error. We discuss potential applications of this solvent treatment in protein x-ray crystallographic refinements and in theoretical modeling. We also present a fast, grid-based algorithm for construction of the perpendicular solvent density distributions. © 1998 John Wiley & Sons, Inc. Biopoly 45: 469-478, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 23-29 
    ISSN: 0006-3525
    Keywords: independently folded polypeptide motifs ; miniproteins ; natural target domains ; BBA motif ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper we present a redesign strategy for the development of uniquely folded polypeptide motifs of less than 40 residues. These mini proteins are based on natural target domains, including the zinc finger domains (BBA motif) Nomenclature corresponds to the defined elements of secondary structure, beginning at the N-terminus of the peptide. Roman lettering refers to a specific motif while Greek characters correspond to the elements of secondary structure within that motif. and the disulfide-rich snake and scorpion toxins (BBB motif). These motifs are designed to act as the molecular framework for the construction of novel functional polypeptides. We will explore the structural determinants of the folded BBA motif, inspired by the zinc finger peptides, in relation to the redesign process. © 1998 John Wiley & Sons, Inc. Biopoly 47: 23-29, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 75-81 
    ISSN: 0006-3525
    Keywords: ion channel ; synthetic peptide ; de novo design ; template-assembled synthetic proteins ; supramolecular assembly ; membrane protein ; planer lipid bilayers ; amphiphilic peptide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To create ion channel function by synthetic peptides is a challenge in the de novo design of artificial membrane proteins. Amphiphilic α-helical motifs of ∼ 20 amino acid residues to span lipid bilayers are most often used for the creation of peptide ion channels. Template molecules to tether helical peptides have been employed to obtain more organized pore structures. Approaches to form molecular assembly of peptides in the membranes by hydrogen bonding have been also investigated. We have developed approaches to assemble helices with individual amino acid sequences to construct artificial helical proteins. Using one of these approaches, four helices corresponding to the voltage sensor segments (S4 in repeat I-IV) of the sodium channel were assembled on a peptide template to give a protein having ion channel activity with rectification. © 1998 John Wiley & Sons, Inc. Biopoly 47: 75-81, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 127-142 
    ISSN: 0006-3525
    Keywords: collagen mimetics ; triple helix ; peptoid ; template ; biophysics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collagen peptidomimetics have been synthesized as an alternative to natural collagen. The incorporation of unnatural residues such as peptoids in the collagen sequences can demonstrate potent and specific biological activity and enhance the biostability against enzymatic degradation. Furthermore, the use of achiral peptoids simplifies synthetic strategies by reducing racemization problems. The peptoid residue N-isobutylglycine (Nleu) has been successfully incorporated into a series of collagen mimetics composed of Gly-Pro-Nleu, Gly-Nleu-Pro, and Gly-Nleu-Nleu. The discovery of template-assembled collagen mimetics and metal binding ability has laid the foundation for new opportunities in the design of novel collagen mimetic complexes. This review summarizes the synthesis and integrated biophysical analyses of the structures of these collagen mimetics. Solid phase segment condensation techniques have been utilized for the synthesis of the single chain and template-assembled analogues. The characterization of the collagen-like structures has been established by temperature-dependent optical rotation measurements, CD, NMR spectroscopy, and molecular modelling simulations. © 1998 John Wiley & Sons, Inc. Biopoly 47: 127-142, 1998
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 0006-3525
    Keywords: non-natural amino acid ; peptide ; squarylium dye ; thin film ; poly(3-methylthiophene) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We designed a polypeptide that behaves as a photodevice by using a non-natural amino acid with replacement of an α-hydrogen by a squarylium dye and succeeded in syntheses of the non-natural amino acid derivative containing a squarylium and its peptide with trialanine Ala-Ala-Ala. Strong dye-dye interactions were confirmed by absorption and CD spectra for the peptide in 2,2,2-trifluoroethanol solution and in water suspension. The non-natural amino acid derivative could be deposited onto a PMeT/Au electrode by the micelle disruption method. © 1998 John Wiley & Sons, Inc. Biopoly 47: 179-183, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 263-263 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    ISSN: 0006-3525
    Keywords: electrostatically driven Monte Carlo method ; cluster analysis ; global energy minimum ; perturbed conformations ; conformational space ; lowest energy conformations ; polypeptide chain ; melittin, membrane-bound portion ; Empirical Conformational Energy Program for Peptides 3 ; annealing methods ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrostatically driven Monte Carlo (EDMC) method has been greatly improved by adding a series of new features, including a procedure for cluster analysis of the accepted conformations. This information is used to guide the search for the global energy minimum. Alternative procedures for generating perturbed conformations to sample the conformational space were also included. These procedures enhance the efficiency of the method by generating a larger number of low-energy conformations.The improved EDMC method has been used to explore the conformational space of a 20-residue polypeptide chain whose sequence corresponds to the membrane-bound portion of melittin. The ECEPP/3 (Empirical Conformational Energy Program for Peptides) algorithm was used to describe the conformational energy of the chain. After an exhaustive search involving 14 independent runs, the lowest energy conformation (LEC) (-91.0 kcal/mol) of the entire study was encountered in four of the runs, while conformations higher in energy by no more than 1.8 kcal/mol were found in the remaining runs with the exception of one of them (run 8). The LEC is identical to the conformation found recently by J. Lee, H.A. Scheraga, and S. Rackovsky [(1998) “Conformational Analysis of the 20-Residue Membrane-Bound Portion of Melittin by Conformational Space Annealing,” Biopolymers, Vol. 46, pp. 103-115] as the lowest energy conformation obtained in their study using the conformational space annealing method. These results suggest that this conformation corresponds to the global energy minimum of the ECEPP/3 potential function for this specific sequence; it also appears to be the conformation of lowest free energy. © 1998 John Wiley & Sons, Inc. Biopoly 46: 117-126, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 195-200 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 201-214 
    ISSN: 0006-3525
    Keywords: band broadening ; dispersion ; DNA ; gels ; electrophoresis ; fluorescence recovery ; photobleaching ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We determined quantitatively the band broadening effect during gel electrophoresis by measuring the longitudinal dispersion coefficient Dx, with a fluorescence recovery after photobleaching setup, coupled to an electrophoretic cell. We carried out measurements as a function of the electric field, the average pore size, and the molecular length of DNA fragments. Our results are in good agreement with the predictions of the biased reptation model with fluctuations described by T. A. Duke et al. [(1992) Physics Review Letters, vol. 69, pp. 3260-3263]. This agreement is observed on single-stranded DNA [persistence length ≅ 4 nm; B. Tinland et al. (1997) Macromolecules, vol. 30, pp. 5763-5765] in polyacrylamide gels and on double-stranded DNA (persistence length ≅ 50 nm) in agarose gels, two systems where the ratio between the average pore size and the Kuhn length is larger than 1. © 1998 John Wiley & Sons, Inc. Biopoly 46: 201-214, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 403-415 
    ISSN: 0006-3525
    Keywords: molecular dynamics ; DNA curvature ; DNA flexibility ; TATA box functionality ; TATA box binding protein (TBP) ; TBP recognition ; TBP binding ; TBP transcriptional activation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four 1.5 ns molecular dynamics (MD) simulations were performed on the d(GCTATAAAAGGG) · d(CCCTTTTATAGC) double helix dodecamer bearing the Adenovirus major late promoter TATA element and three iso-composition mutants for which physical and biochemical data are available from the same laboratory. Three of these DNA sequences experimentally induce tight binding with the TATA box binding protein (TBP) and induce high transcription rates; the other DNA sequence induces much lower TBP binding and transcription. The x-ray crystal structures have previously shown that the duplex DNA in DNA-TBP complexes are highly bent. We performed and analyzed MD simulations for these four DNAs, whose experimental structures are not available, in order to address the issue of whether inherent DNA structure and flexibility play a role in establishing these observed preferences. A comparison of the experimental and simulated results demonstrated that DNA duplex sequence-dependent curvature and flexibility play a significant role in TBP recognition, binding, and transcriptional activation. © 1998 John Wiley & Sons, Inc. Biopoly 46: 403-415, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 0006-3525
    Keywords: vibrational CD ; solution conformation ; alanine oligopeptides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution conformation of a number of small, linear alanine oligomers was investigated via ir (or vibrational) CD (VCD). We find that these oligopeptides assume distinct solution conformations that depend primarily on chain lengths, and to a lesser degree on temperature, ionic strength, and pH. As expected, the longer chain oligomers exhibit more distinct VCD features and, presumably, more stable solution structures. At the level of the hexamer, however, aggregation of the peptide occurs. The fast time scale of VCD allows solution structures to be detected that may not be observable using slower techniques such as various forms of nmr spectroscopy. The VCD results reported here confirm that it is generally possible to obtain conformational information for small, linear homo- and heterooligopeptides via VCD spectroscopy. In this respect, the sensitivity of VCD is similar to that of electronic CD. Furthermore, the temperature dependence of the VCD results indicate that at elevated temperatures, the increasing number of conformational states results in a loss of discernible conformers, and consequently, a broadening and weakening of the VCD features. © 1998 John Wiley & Sons, Inc. Biopoly 46: 455-463, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 5-22 
    ISSN: 0006-3525
    Keywords: hemoproteins ; model systems ; miniaturized proteins ; mimochromes ; helix structures ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present paper highlights and reviews current research in the field of hemoprotein models. Hemoproteins have been extensively studied in order to understand structure-function relationships, and to design new molecules with desired functions. A wide number of synthetic analogues have been developed, using quite different approaches. They differ in molecular structures, ranging from simple meso-substituted tetraaryl-metalloporphyrins and peptide-porphyrin conjugates.In this paper we summarize the state of the art on peptide based hemoprotein models. We also report here the approach used by us to develop a new class of molecules, named mimochromes. They can be regarded as miniaturized hemoproteins, because mimochromes are low molecular weight compounds with some structural and functional properties common to those of the parent high molecular weight protein. The basic structure of mimochromes is a deuteroporphyrin ring covalently linked to two helical peptide chains. Two molecules of this series have been fully characterized. All the information derived from their structural analysis has been applied to the design of new analogues with additional functions. © 1998 John Wiley & Sons, Inc. Biopoly 47: 5-22, 1998
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 503-516 
    ISSN: 0006-3525
    Keywords: discrete charge model of DNA ; dielectric cylinder in water ; effective dielectric constant ; salt effects ; Debye shielding factor ; potential variations in DNA surface ; Boltzmann averaged bending angles ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied electrostatic properties of DNA with a discrete charge model consisting of a cylindrical dielectric core with a radius of 8 Å and a dielectric constant Di = 4, surrounded by two helical strings of phosphate point charges at 10 Å from the axis, immersed in an aqueous medium with dielectric constant Dw = 78.54. Eliminating the dielectric core makes potentials in the phosphate surface less negative by about 0.5 kT/e. Salt effects are evaluated for the model without a dielectric core, using the shielded Coulomb potential. Smearing the phosphate charges increases their potential by about 2.5 kT/e, due mostly to the self-potential of the smeared charge. Potentials in the center of the minor and major grooves vary less than 0.02 kT/e along their helical path. The potential in the center of the minor groove is from 1.0 to 1.7 kT/e, more negative than in the center of the major groove, depending on dielectric core and salt concentration. So multivalent cations and also larger cationic ligands, such as some antibiotics, are likely to adsorb in the minor groove, in agreement with earlier computations by A. and B. Pullman. Dielectric effects on the surface potential and the local potential variations are found to be relatively small. Bending of DNA is studied by placing a multivalent cation, MZ+, in the center of the minor or major groove, curving DNA around it for a certain length, and calculating the free energy difference between the bent and the straight configuration. Boltzmann averaged bending angles, 〈β〉, are found to be maximal in 0.03M monovalent salt, for a length of about 50 or 25 Å of curved DNA when an MZ+ ion is adsorbed in the minor or the major groove, respectively. When the dielectric constant of water is used throughout the calculation, we find maximal bends of 〈β〉 = 11° for M2+ and 〈β〉 = 16° for M3+ in the minor groove, 〈β〉 = 13° for M3+ in the major groove. The absence of bends in DNA adsorbed to mica in the presence of Mg salts supports the role of Mg2+ in “ion bridging” between DNA and mica. The treatment of the effective dielectric constant between two points outside a dielectric cylinder in water is appended. © 1998 John Wiley & Sons, Inc. Biopoly 46: 503-516, 1998
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 63-73 
    ISSN: 0006-3525
    Keywords: protein de novo design ; novel macromolecules ; topological templates ; Template Assembled Synthetic Proteins (TASP) ; biosensors ; protein folding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ultimate goal in protein de novo design is the creation of novel macromolecules with tailor-made receptor, sensory, and catalytic functions. Despite considerable progress in understanding basic rules of secondary structure formation and protein stability, the well-known protein folding problem is still far from being solved and, in general, only a limited number of designed proteins are folded uniquely. In this article the state-of-the-art in protein design is demonstrated on some selected examples, indicating that the construction of protein-like macromolecules mimicking some essential features of natural proteins seems to be within reach. Thus, protein design and mimicry has become an interdisciplinary challenge with most intriguing perspectives. © 1998 John Wiley & Sons, Inc. Biopoly 47: 63-73, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 47 (1998), S. 451-463 
    ISSN: 0006-3525
    Keywords: bacteria ; antibiotics ; linear amphipathic α-helical antimicrobial peptides ; peptide-lipid interactions ; membrane permeation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The increasing resistance of bacteria to conventional antibiotics resulted in a strong effort to develop antimicrobial compounds with new mechanisms of action. Antimicrobial peptides seem to be a promising solution to this problem. Many studies aimed at understanding their mode of action were described in the past few years. The most studied group includes the linear, mostly α-helical peptides. Although the exact mechanism by which they kill bacteria is not clearly understood, it has been shown that peptide-lipid interactions leading to membrane permeation play a role in their activity. Membrane permeation by amphipathic α-helical peptides can proceed via either one of the two mechanisms: (a) transmembrane pore formation via a “barrel-stave” mechanism; and (b) membrane destruction/solubilization via a “carpet-like” mechanism. The purpose of this review is to summarize recent studies aimed at understanding the mode of action of linear α-helical antimicrobial peptides. This review, which is focused on magainins, cecropins, and dermaseptins as representatives of the amphipathic α-helical antimicrobial peptides, supports the carpet-like rather the barrel-stave mechanism. That these peptides vary with regard to their length, amino acid composition, and net positive charge, but act via a common mechanism, may imply that other linear antimicrobial peptides that share the same properties also share the same mechanism. © 1999 John Wiley & Sons, Inc. Biopoly 47: 451-463, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 39-55 
    ISSN: 0006-3525
    Keywords: modified nucleotides ; site-specific probes ; RNA structure ; RNA function ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modified nucleotides can be incorporated site specifically into RNA by the use of total chemical synthesis as well as by use of a variety of recombinant RNA techniques. The range of nucleotide analogues includes modifications to base, sugar, and phosphate for structure-function analysis and for cross-linking studies as well as to answer specific mechanistic questions in RNA catalysis. We describe how RNA containing site-specific modifications are prepared, concentrating in particular on routes involving chemically synthesized oligoribonucleotides, and give examples of their application in studies of the hammerhead and hairpin ribozymes. © 1998 John Wiley & Sons, Inc. Biopoly 48: 39-55, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 29-37 
    ISSN: 0006-3525
    Keywords: amide synthase ; catalytic antibodies ; Diels-Alderase ; ideal catalyst platform ; in vitro selection ; Lewis acid ; modified uridines ; modified RNA ; ribozymes ; SELEX ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this manuscript the catalytic ability of RNA is examined and compared to other biopolymers. Despite having considerably fewer catalytically enabling properties when compared to proteins, the power of in vitro selection has allowed for RNA and DNA catalysts to be isolated. RNA catalysis has been expanded by incorporating modified bases to enrich the structural and functional diversity of RNA. Successful examples of new RNA chemistry using base modifications include carbon-carbon bond forming reactions and creation of highly specific active sites that are capable of recognizing small organic molecules without the need for nucleic acid templating or intercalation. In fact, the scope of functional modifications available for use in the RNA platform may eventually surpass those that are found in proteins and there are already hints that well chosen modifications allow nucleic acid catalysts to take advantage of mechanisms not available to selected protein catalysts for similar reactions. The chemical versatility of RNA is just emerging and future research directions will likely entail more creative methods for functional modification that will lead to new catalysts. © 1998 John Wiley & Sons, Inc. Biopoly 48: 29-37, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 48 (1998), S. 137-153 
    ISSN: 0006-3525
    Keywords: RNA ; pseudoknot ; Turnip Yellow Mosaic Virus ; Mouse Mammary Tumor Virus ; Beet Western Yellows Virus ; Simian Retrovirus type-1 ; Hepatitis Delta Virus ; translational frameshifting ; ribozyme ; nmr ; x-ray diffraction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently, several high-resolution structures of RNA pseudoknots have become available. Here we review the progress in this area. The majority of the structures obtained belong to the classical or H-type pseudoknot family. The most complicated pseudoknot structure elucidated so far is the Hepatitis Delta Virus ribozyme, which forms a nested double pseudoknot. In particular, the structure-function relationships of the H-type pseudoknots involved in translational frameshifting have received much attention. All molecules considered show interesting new structural motifs. © 1999 John Wiley & Sons, Inc. Biopoly 48: 137-153, 1998
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 737-748 
    ISSN: 0887-624X
    Keywords: inverse microemulsion polymerization ; MADQUAT ; nucleation ; photopolymerization ; molecular weights ; flocculants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of inverse microemulsions of 2-methacryloyl oxyethyl trimethyl ammonium chloride stabilized by a blend of nonionic emulsifiers (a sorbitan sesquioleate and a sorbitan monooleate) and initiated by UV light in the presence of Azobis(isobutyronitrile) (AIBN) was investigated. The effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the polymerization rate (Rp), number of polymer particles (Np), and polymer molecular weight (Mw) was studied. The application of this process to tubular reactors is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 737-748, 1998
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1217-1226 
    ISSN: 0887-624X
    Keywords: polypropylene ; pyrene ; two-solute system ; pulse radiolysis ; solute ionic species ; solute excited states ; low-temperature radiolysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A pulse radiolysis study of isotactic polypropylene (PP) film has been carried out with the main aims of investigating charge trapping in an undoped system and solute radical ion generation in an pyrene (Py) doped matrix. In PP, pulse radiolysis gives electron-positive hole pairs. The electron can be stabilized in the undoped system as a trapped electron, et-. The transient absorption spectrum of et- in the near-IR (up to 1800 nm) was observed in the temperature range 30-100 K. This IR absorption was not detected in the case of oxidized PP. In such a matrix electrons can be scavenged by oxidation products generating respective radical-anions (absorption in the UV RANGE, λ 〈 350 nm). In a doped matrix transient absorption bands centered at 450 and 500 nm were observed which can be assigned to the Py radical cation and anion, respectively. The recombination of these ionic species leads to monomer excited-state formation observed during and after the 17 ns pulse. Contrary to the Py-doped polyethylene no excimer emission was detected at room temperature even if Py content in PP was close to 0.02 mol dm-3. The rate of Py radical-ion decay was found to be temperature dependent. Two linear parts of the Arrhenius plot were observed which intersected at ca. 240 K, the glass transition temperature, Tg, for PP. The activation energies calculated for two parts of Arrhenius plot were equal to 111 and ca. 0.78 kJ mol-1 for T 〉 Tg and T 〈 Tg, respectively. Some preliminary results concerning the ionic processes in PP containing two solutes (Py, 3,3′-dimethyldiphenyl) were presented. The mechanism of ionic recombination in PP will be proposed and discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1217-1226, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1345-1348 
    ISSN: 0887-624X
    Keywords: acid functional ; telechelic ; benzyl alcohol ; poly(ε-caprolactone) ; polymerization ; living ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 883-888 
    ISSN: 0887-624X
    Keywords: temperature sensitive ; particle ; emulsion polymerization ; morphology ; adsorption ; enzyme ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two kinds of temperature-sensitive composite polymer particles were prepared by seeded emulsion copolymerizations of (dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate with 0.14 μm-sized polystyrene and 0.26 μm-sized poly(methylmethacrylate) seed particles. To evaluate the usefulness as a carrier for biomolecules, the enzymatic activities of trypsin adsorbed on these two composite polymer particles were measured at temperatures above and below each lower critical solution temperature (LCST). In both cases, adsorbed trypsin retained its enzymatic activity during repeated adsorption/desorption measurements. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 883-888, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    ISSN: 0887-624X
    Keywords: (1→6)-2,5-anhydro-D-glucitol ; HPLC ; optical resolution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclopolymerization of 3,4-di-O-allyl-1,2 : 5,6-dianhydro-D-mannitol (1) was carried out using BF3·OEt2 and t-BuOK. The polymer obtained by the polymerization with BF3·OEt2 mainly consisted of (1→6)-bonded 3,4-di-O-allyl-2,5-anhydro-D-glucitol as the five-membered constitutional repeating unit, though it contained a small amount of other cyclic repeating units. On the other hand, during the polymerization using t-BuOK, the stereoregular polymer (1→6)-linked 3,4-di-O-allyl-2,5-anhydro-D-glucitol (2) was synthesized via a regio- and stereoselective mechanism. Cleavage of the allyl ether linkage in polymer 2 occurred to produce the polymer consisting of only 2,5-anhydro-D-glucitol units, i.e., (1→6)-2,5-anhydro-D-glucitol (3). Chromatographic enantioseparation of chloroquine and tröger base has been performed on (3,5-dimethylphenyl)carbamate and 4-methylbenzoate derivatives of 3 as a chiral stationary phase for high-performance liquid chromatography. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 901-909, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 939-947 
    ISSN: 0887-624X
    Keywords: fluorine ; perfluoropolyether ; polyester ; segmented ; thermoplastic ; interfacial synthesis ; thermal transitions ; dynamic-mechanical properties ; chemical resistance ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear segmented polyesters containing soft perfluoropolyether (PFPE) and hard aromatic segments are obtained by an interfacial polycondensation reaction of an acyl chloride-ended fluorinated prepolymer with various aromatic diphenols in the presence of phase transfer catalysts (PTC) as accelerators. Experimental conditions for reaching high molecular weights are discussed. The calorimetric analysis (DSC) of all the polyesters synthesized shows a typical biphasic morphology, where a very low Tg (〈 -110°C) corresponding to the segregated PFPE moiety, is always accompanied by another Tg or a higher melting temperature, depending on the nature of the hard phase. Dynamic-mechanical analysis (DMA) has been carried out confirming the DSC results and suggesting diversified mechanical behaviors at the various temperatures in line with the amorphous or semicrystalline nature of the polymer. Chemical resistance was finally tested by dipping in several solvents and chemicals. The new polyesters show high contact angles, a moderate swelling in many organic solvents and excellent stability in aggressive hydrolytic environments. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 939-947, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1919-1928 
    ISSN: 0887-624X
    Keywords: emulsion polymerization ; vinylidene chloride ; kinetics ; sodium lauryl sulfate ; potassium persulfate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Emulsion polymerization of vinylidene chloride was carried out at 50°C using sodium lauryl sulfate as emulsifier and potassium persulfate as initiator, respectively. Contrary to the results so far reported, the stirring rate did not affect the progress of the polymerization and such an abnormal kinetic behavior as the rate of polymerization suddenly drops in the course of polymerization was not observed. The number of polymer particles produced was proportional to the 0.7 power of the concentration of emulsifier forming micelles and to the 0.3 power of the initial initiator concentration, respectively, and was independent of the initial monomer concentration. The rate of polymerization was in proportion to the 0.3 power of the concentration of emulsifier forming micelles, to the 0.5 power of the initial initiator concentration, to the 0.2 power of the initial monomer concentration, and to the 0.45 power of the number of polymer particles, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1919-1928, 1998
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1961-1964 
    ISSN: 0887-624X
    Keywords: Poly(4,4′-phenylene-3,3′,4,4′-biphenyltetracarboxyimide) ; poly(4,4′-oxydiphenylenepyromellitimide) ; precursor solution ; aprotic polar solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1969-1972 
    ISSN: 0887-624X
    Keywords: hydrosilation ; polymer ; siloxane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1995-1999 
    ISSN: 0887-624X
    Keywords: poly-γ-D-glutamic acid ; biopolymer ; covalent modification ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods for the covalent modification in aqueous solution of poly-γ-D-glutamic acid from Bacillus licheniformis have been studied. Co-derivatization of a synthetic UV-absorbent amine and ethanolamine, using a water-soluble carbodi-imide coupling agent, yielded a water-soluble modified polymer. Derivatization of the polymer was accompanied by cleavage of the γ-linked polypeptide backbone, and a reduction in molecular mass from 170 to 10 kDa. A procedure was developed for the removal of noncovalently bound ligands by treatment with 5 M CaCl2. The polymer sidechains also reacted in aqueous solution with p-nitrophenyl acetate to form covalent linkages. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 1995-1999, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2037-2042 
    ISSN: 0887-624X
    Keywords: radical polymerization ; vinylcyclopropane ; vinylsilane ; desilylation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and radical polymerization of novel vinylcyclopropanes; 1-carboethoxy-2-trimethylsilyl-2-vinylcyclopropane (1a) and 1-carboethoxy-2-(1-trimethylsilyl)-vinylcyclopropane (1b), were examined. 1a and 1b were prepared by the coupling reaction of 2-trimethylsilylbutadiene with ethyl diazoacetate, which was prepared from glycine ethyl ester hydrochloride. The radical polymerization of 1a and 1b was carried out at 60°C in bulk for 40 h in the presence of 2,2′-azobis(isobutyronitrile) (5 mol % vs. monomer). Poly(1) consisted of a 1,5-ring-opened unit. Desilylation reaction of poly(1) proceeded quantitatively in aqueous hydrochloric acid. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2037-2042, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2021-2027 
    ISSN: 0887-624X
    Keywords: 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride ; aromatic polyimides ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new aromatic tetracarboxylic dianhydride having a crank and twisted noncoplannar structure, 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, was synthesized by the reaction of 4-nitrophthalonitrile with biphenyl-2,2′-diol, followed by hydrolysis and cyclodehydration. The biphenyl-2,2′-diyl-containing aromatic polyimides having inherent viscosities up to 0.66 dL/g were obtained by the conventional two-step procedure starting from the dianhydride monomer and various aromatic diamines. Most of the polyimides were readily soluble in amide-type solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The aromatic polyimides had glass transition temperatures in the range of 205-242°C, and began to lose weight around 415°C, with 10% weight loss being recorded at about 500°C in air. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2021-2027, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2069-2079 
    ISSN: 0887-624X
    Keywords: Candida antarctica lipase ; Novozym 435® ; polyester ; enzymatic polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary enzymatic polymerization studies in the simple stoichiometric adipic acid/butane-1,4-diol system using lipase B from Candida antarctica, immobilized as Novozym 435®, suggest that in solvent-free conditions a step-growth mechanism operates involving the sequential addition of an AB synthon by esterification mode only. Conversely, in toluene as solvent there is a change to the more facile transesterification mode in line with the conventional polyesterification procedure, pointing to a change in specificity of the lipase. Evidence is drawn from qualitative studies using a series of synthetic intermediates, enabling authentication of product mixtures together with an indication of the comparative reactivity of species along the proposed reaction pathway. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2069-2080, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2111-2117 
    ISSN: 0887-624X
    Keywords: dendritic polymer ; blends ; coatings ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonance (NMR) spectroscopy, and tensile property measurements. The data suggest a much higher degree of interaction between components of PVAc-containing blends compared to those containing PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2111-2117, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2135-2146 
    ISSN: 0887-624X
    Keywords: SCLC polyurethanes ; azobenzene mesogenic group ; alkyl spacer ; bilayer smectic phases ; hydrogen bonding ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of side chain liquid crystal polyurethanes (CnCNPs), in which the spacer length was varied from 2 to 12 methylene units, were synthesized by the addition polymerization of α-[bis(2-hydroxyethyl)amino]-ω-(4-cyanoazobenzene-4′-oxy)alkanes (CnCN-diols) with hexamethylene diisocyanate. The liquid crystalline properties of CnCNPs were characterized by means of differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. Polyurethanes with spacer length 4 or higher exhibited mesomophic properties. C4CNP and C5CNP exhibited an enantiotropic nematic mesophase, while C6-C12CNPs exhibited enantiotropic bilayer smectic mesophases. CnCNPs have a high tendency to crystallize; crystallization is kinetically controlled. Polyurethane's backbone crystallization is closely related to hydrogen bonding. To establish the role of hydrogen bonding in mesophase formation as well as crystallization, Fourier transform infrared spectroscopy studies of CnCNPs were carried out at different temperatures focusing on H-bonds between the N—H and C=O groups of the urethane backbone. With increasing temperature, C=O and N—H stretching bands were evenly shifted to higher wavenumbers, with two exceptions (C4CNP and C5CNP) discussed in detail in the text. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2135-2146, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2169-2176 
    ISSN: 0887-624X
    Keywords: free radical ; initiation ; styrene ; acrylonitrile ; copolymerization ; nitroxide trapping ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The competitive reactions of cyanoisopropyl radicals with the mixed monomers styrene and acrylonitrile have been investigated using the nitroxide radical trapping technique. When the trap concentration is kept low, second, third, and even fourth generation (in terms of successive monomer addition) carbon radicals have been observed as trapped products. The ratio of rate constants for the addition of styrene and acrylonitrile to cyanoisopropyl radicals is 2.7 at 75°C and 5.3 at 105°C. These values are compared with the ratios for reactions of these two monomers with a number of other radicals and discussed in terms of the polarities of the radicals and monomers. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2169-2176, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2193-2200 
    ISSN: 0887-624X
    Keywords: N-phenylated polyamides ; 4,4′-dianilinobiphenyl ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New N-phenylated aromatic-aliphatic and all aromatic polyamides were prepared by the high-temperature solution polycondensation of 4,4′-dianilinobiphenyl with both aliphatic (methylene chain lengths of 6-11) and aromatic dicarboxylic acid chlorides. All of the aromatic-aliphatic polyamides and the wholly aromatic polyamides exhibited an amorphous nature and good solubility in amide-type and chlorinated hydrocarbon solvents, except for those aromatic polyamides containing p-oriented phenylene or biphenylylene linkages in the backbone; the latter were crystalline and insoluble in organic solvents except m-cresol. The N-phenylated aromatic-aliphatic polyamides and aromatic polyamides had glass transition temperatures in the range of 79-116°C and 207-255°C, respectively, and all the polymers were thermally stable with decomposition temperatures above 400°C in air. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2193-2200, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2237-2245 
    ISSN: 0887-624X
    Keywords: NMR ; polysiloxane, polysiloxane-block-polyimide ; solution imidization ; kinetic analysis ; structure analysis ; spin-lattice relaxation time ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of polysiloxane-block-polyimides were synthesized by solution imidization of the polyamic acids derived from the combination of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and diamino(polysiloxane) (PSX (Mw = 750)) in N-methyl-2-pyrrolidone (NMP). Their structures were analyzed by 1H-, 13C-, and 29Si-NMR spectra as well as by IR spectroscopy. The solid-state NMR spectrum was also measured to determine the spin-lattice relaxation time of the copolyimides. The observed relaxation times of both aromatic and polysiloxane segments were similar in the copolyimides having 10-30 wt % of PSX, while those in the copolyimide with 50 wt % of PSX was significantly different. This may be attributed to the morphology change due to the increase in PSX composition in the polymer backbone. The reduced viscosity of the copolyimides could be controlled by changing the monomer ratio in the feed or by adding an end-capping reagent such as phthalic anhydride into the polymerization system. The kinetic study of the solution imidization revealed that the imidization reaction obeyed second-order kinetics. The activation energy calculated for this imidization was 99.2 kJ/mol, being similar to that for the imidization of the DSDA-based aromatic polyimides. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2237-2245, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2229-2235 
    ISSN: 0887-624X
    Keywords: polyarylates ; aromatic polyether ; 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New polyarylates having benzopinacolone units were synthesized from 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone and aromatic dicarboxylic acid chlorides. The polymers having an inherent viscosity of 0.71-0.94 dL/g were obtained by the two-phase method using toluene as an organic solvent. The polymers were easily soluble in various organic solvents and had high glass transition temperatures in the range of 200-240°C. An aromatic polyether having benzopinacolone unit was also prepared. However, its inherent viscosity was low because of the occurrence of a side reaction. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2229-2235, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 31-38 
    ISSN: 0887-624X
    Keywords: triblock copolymers ; polycondensations ; telechelic character ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Telechelic oligo(ether-ketone)s containing two trimethylsiloxy end groups and one methyl group per repeating unit were prepared by polycondensation of 4-fluoro-2′-methyl-4′-(trimethylsiloxy)benzophenone. The telechelic character was achieved by cocondensation of a small amount of silylated bisphenol-P. The end groups of the silylated oligo(ether-ketone)s were acetylated by means of acetyl chloride. On the basis of 1H-NMR end group analyses two samples of α,ω-bis(acetoxy) oligo(ether-ketone)s with DP = 14 and DP ∼ 28 were obtained. These oligo(ether-ketone)s and a 70 or 140 fold molar amount of silylated 3,5-bis(acetoxy)benzoic acid were polycondensed at 270°C in bulk. The resulting A-B-A triblock copolymers were fractionated by dissolution in tetrahydrofuran. In three out of four experiments a small fraction of precipitated material rich in oligo(ether-ketone) was isolated. The purified triblock copolymers were characterized by inherent viscosities and NMR spectra. For those samples containing the long oligo(ether-ketone) block a low degree of crystallinity was observed after annealing. Four additional polycondensations were conducted with an initial reaction temperature of 290°C. In this way a completely soluble and amorphous triblock copolymer was obtained. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 31-38, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    ISSN: 0887-624X
    Keywords: liquid crystalline polymers ; epoxy resins ; thermotropic ; polymer chain extension ; catalytic polyaddition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work is a continuation of the authors' earlier investigations of liquid crystalline epoxy resins prepared from diglycidyl ether of 4,4′-dihydroxybiphenyl (DGE-DHBP), which was used as a mesogenic agent, and aliphatic dicarboxylic compounds, which were used as flexible spacers. In this paper, the synthesis and characterization of liquid crystalline epoxy resins, prepared from DGE-DHBP and difunctional aromatic compounds are described. Three series of liquid crystalline epoxy resins were prepared by chain extension of DGE-DHBP with isomeric hydroxybenzoic and benzenedicarboxylic acids as well as diphenols. An isophthalic-terminated polyether was applied to decrease the temperature of phase transitions. The syntheses were carried out by catalytic polyaddition in the melt. Triphenylphosphine was applied as the catalyst. The resulting epoxy resins were investigated by DSC, polarizing microscope as well as by X-ray and IR spectroscopy. The phase transition temperatures and the type of mesophase of the resulting products depend on the character of the functional groups in the chain extender and on the position of the functional groups in the aromatic ring. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 21-29, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1987-1994 
    ISSN: 0887-624X
    Keywords: triphenylamine-based bis(o-aminophenol)s ; aromatic polybenzoxazoles ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new triphenylamine-based bis (o-aminophenol) monomers, 4,4′-diamino-3,3′-dihydroxytriphenylamines, were successfully synthesized by the cesium fluoride-mediated condensation of 2-(benzyloxy)-4-fluoronitrobenzene with aniline derivatives, followed by simultaneous deprotection and reduction. Aromatic polybenzoxazoles having inherent viscosities of 0.58-1.05 dL/g were obtained by the low-temperature solution polycondensation of the bis(aminophenol)s with various aromatic dicarboxylic acid chlorides and the subsequent thermal cyclodehydration of the resultant poly(hydroxyamide)s. All the polybenzoxazoles were amorphous, and most of them were soluble in organic solvents such as m-cresol and o-chlorophenol. Flexible and tough films of polybenzoxazoles could be cast from the DMAc solutions of some aromatic poly(hydroxyamide)s, followed by thermal cyclodehydration. The glass transition temperatures and 10% weight loss temperatures of the polybenzoxazoles under nitrogen were in the range of 262-327 and 610-640°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1987-1994, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2013-2019 
    ISSN: 0887-624X
    Keywords: asymmetric polymerization ; anionic polymerization ; (2-fluorophenyl)(4-fluorophenyl)(2-pyridyl) methyl methacrylate ; optically active polymer ; helix ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel racemic methacrylate, (2-fluorophenyl)(4-fluorophenyl)(2-pyridyl)-methyl methacrylate1 (2F4F2PyMA), was synthesized and polymerized with chiral complexes of N,N′-diphenylethylenediamine monolithium amide (DPEDA-Li) with (-)-sparteine (Sp), (2S, 3S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)butane (DDB), and (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine (PMP) in toluene at -78°C. The monomer showed higher resistance against methanolysis compared with triphenylmethyl methacrylate (TrMA) and several other analogues. In the asymmetric anionic polymerization of 2F4F2PyMA, PMP was found to be a more effective chiral ligand than DDB and Sp and gave quantitatively an optically active polymer with nearly perfect isotacticity. Enantiomer selection was observed in the polymerization of racemic 2F4F2PyMA with the chiral lithium complexes. Chiral recognition ability of the optically active poly(2F4F2PyMA) was examined by an enantioselective adsorption experiment. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2013-2019, 1998
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2521-2530 
    ISSN: 0887-624X
    Keywords: poly(methylphenylsiloxane) ; poly(methyl methacrylate) ; graft copolymer ; spin-spin relaxation ; degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(methylphenylsiloxane)-poly(methyl methacrylate) graft copolymers (PSXE-g-PMMA) were prepared by condensation reaction of poly(methylphenylsiloxane)-containing epoxy resin (PSXE) with carboxyl-terminated poly(methyl methacrylate) (PMMA), and they were characterized by gel permeation chromatography (GPC), infrared (IR), and 29Si and 13C nuclear magnetic resonance (NMR). The microstructure of the PSXE-g-PMMA graft copolymer was investigated by proton spin-spin relaxation T2 measurements. The thermal stability and apparent activation energy for thermal degradation of these copolymers were studied by thermogravimetry and compared with unmodified PMMA. The incorporation of poly(methylphenylsiloxane) segments in graft copolymers improved thermal stability of PMMA and enhanced the activation energy for thermal degradation of PMMA. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2521-2530, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2563-2570 
    ISSN: 0887-624X
    Keywords: thioxanthone derivatives ; water-compatible photoinitiator ; absorption spectrum ; fluorescence ; photopolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six amine-linked thioxanthones, i.e., 2-(2-hydroxy-3-[bis(2-hydroxyethyl)amino]propoxy)thioxanthone (HAPTX) and its 4-methyl, 1,3-dimethyl, 1,4-dimethyl, 3,4-dimethyl, and 1,3,4-trimethyl substituted derivatives, were synthesized as water-compatible photoinitiators and identified with FTIR, MS, NMR, and elementary analysis. The absorption and fluorescence properties were studied. Their photoinitiating polymerization efficiencies were tested with a recording dilatometer utilizing acrylamide as monomer in aqueous solution. The results show that the six amine-linked thioxanthones can independently initiate acrylamide polymerization efficiently without additional external amines as co-initiators. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2563-2570, 1998
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2593-2600 
    ISSN: 0887-624X
    Keywords: phenylenediamine ; oxidative polymerization ; enzyme ; horseradish peroxidase ; CD spectrum ; organic solvent ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ortho-, meta-, and para-phenylenediamines were polymerized using hydrogen peroxide as an oxidant and horseradish peroxidase as a catalyst in mixed solvents of 1,4-dioxane and water. The yield of the polymers was strongly dependent on solvent composition, and maximum yields were obtained at 15-30% 1,4-dioxane. The analysis of circular dichroic spectra of the enzyme suggested that enzyme structure was significantly modified at high 1,4-dioxane contents, which may be responsible for the decrease of catalytic activity of the enzyme. On the basis of IR and electronic spectra of the polymers, it was considered that o- and p-phenylenediamine polymers retain disubstituted benzene nuclei, which suggests that the polymerization proceeded mainly via N - N coupling. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2593-2600, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2667-2668 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2691-2698 
    ISSN: 0887-624X
    Keywords: N-substituted pyrrole ; liquid crystalline polymer ; polypyrrole ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three liquid crystalline N-substituted pyrroles were synthesized from 6-(1-pyrrolyl)hexanol with phenolic derivatives having a mesogenic core of cyclohexylbenzene or biphenyl by Mitsunobu reaction. These pyrroles had two anodic peaks at 1.4 and 1.8 V (vs. SCE). The former was due to an oxidation of the pyrrole moiety and the latter was due to an oxidation of the mesogenic moiety. These pyrrole monomers were polymerized by electrochemical and chemical methods. The potentiostatic method and the chemical method using FeCl3 gave a soluble and fusible polymer, respectively. A polymer having a mesogenic core of cyclohexyl benzene obtained by the chemical method and a polymer having a mesogenic core of biphenylketone obtained by the potentiostatic method had a liquid-crystalline phase. The phase was identified as smectic A by polarizing microscopy and XRD analysis. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2691-2698, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2715-2719 
    ISSN: 0887-624X
    Keywords: polymerization ; acrylamide ; peroxomonosulfate ; ultrasound ; mechanism ; rate parameters ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of acrylamide (M) in the presence of ultrasound and peroxomonosulfate (PMS) was carried out for the first time for various concentration ranges of monomer and initiator and various temperatures at a constant frequency of 1 Mhz. The rate of polymerization Rp was found to increase with increase in the concentration of monomer and initiator and found to depend on [M] and [PMS]1/2. The rate of disappearance of initiator (-d[PMS]/dt) was also followed simultaneously under the experimental conditions and found to increase linearly with increase in [PMS]. A probable reaction mechanism was proposed on the basis of the observed results, and the individual rate constant were evaluated. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2715-2719, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2741-2748 
    ISSN: 0887-624X
    Keywords: stereoregular polymers ; chiral polyamides ; ω-amino acids ; glycine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoregular, enantiomerically pure, chiral polyamides of the -AB- type, containing a natural (glycine) and a synthetic [(S)-5-amino-4-methoxypentanoic acid (AMP)] component have been prepared by the active ester polycondensation method. Thus, polyamide 7 was obtained by polycondensation of the conveniently activated H2NGly-AMPCO2R unit (6). In this reaction, 7 appeared accompanied by a considerable amount of cyclic (Gly-AMP)2 (8), which makes the isolation and purification of 7 difficult. The formation of cyclic byproducts could be avoided by preparing and polymerizing the oligoamide H2NGly-AMP-AMPCO2R (11), which has the terminal carboxyl group activated as the pentachlorophenyl ester. The resulting polyamide (12) was obtained in 85% yield and free of macrolactams, such as 8. The new polyamides 7 and 12 were characterized by elemental analysis and infrared and 1H- and 13C-nuclear magnetic resonance spectroscopies. Thermal studies revealed that 12 is crystalline and yields films with spherulitic texture by slow evaporation of formic acid solutions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2741-2748, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...