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  • Chemistry  (88)
  • Atomic, Molecular and Optical Physics  (12)
  • Glucose
  • Magnetism
  • 1980-1984  (57)
  • 1975-1979  (46)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 131 (1982), S. 174-175 
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Methanol ; Glucose ; Methanol dissimilating enzymes ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study was made of the regulation of the synthesis of methanol dissimilating enzymes inkloeckera sp. 2201 andHansenula polymorpha using chemostat and batch growth conditions and methanol or glucose as carbon sources. During growth in methanol-limited chemostat cultures similar enzyme patterns for alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two yeasts were found. When growing in batch culture with glucoseH. polymorpha, but notKloeckera sp. 2201, was found to produce ethanol which might affect the synthesis of these enzymes.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 651-671 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations, using both minimal (STO-3G) and extended (Roos-Siegbahn) basis sets are reported for the systems methanethiol-imidazole, methanethiol-imidazole-formaldehyde, and methanethiol-imidazole-formamide, which, together with a point-change representation of a long α-helix, form models for the active site of papain. It is shown that the large electric field exerted by the helix in the active-site region is responsible for the presence of the essential residues Cys 25 and His 159 in the form of an ion pair RS- ··· ImH+, which is crucial for a recently proposed mechanism for the catalytic action of the enzyme. Also, an explanation is given for the anomalies in measured pK values for these residues. Detailed studies on the (sub)systems show that minimal basis sets lack the flexibility necessary for describing the type of proton transfer involved. We conclude that α-helices are essential parts of enzymes and that they play a significant role in the catalytic process.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Chemostat ; Mixed substrates ; Glucose ; Methanol ; Growth yields ; Enzyme regulation ; Dissimilatory enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the composition of methanol/glucose-mixtures as only sources of carbon and energy on growth and regulation of the synthesis of enzymes involved in methanol-dissimilation was studied under chemostat conditions at a fixed dilution rate with the methylotrophic yeasts Hansenula polymorpha and Kloeckera sp. 2201. Both carbon sources were found to be utilized completely independently of the composition of the C1/C6 mixture. Using mixtures of 14C-labelled methanol and glucose the growth yield for glucose was found to be constant for all C1/C6-mixtures tested and both yeasts. The growth yield for methanol, however, was reduced by up to 25% when the proportion of methanol in the inflowing medium was lower than 20% (w/w with respect to glucose) for H. polymorpha and 50% (w/w with respect to glucose) for Kloeckera sp. 2201 respectively. During growth with C1/C6-mixtures containing higher C1-proportions of methanol regular growth yields for methanol were recorded which corresponded to the growth yields found with methanol as the only carbon source. The regulation of the synthesis of the enzymes of the dissimilatory pathway for methanol was found to be under multiple control. Although glucose was present in the medium methanol had a positive effect on the synthesis of these enzymes. Thus, in addition to derepression induction by methanol was also observed. This inductive effect was found to increase with increasing proportions of methanol in the mixture. Depending on the enzyme, 10–40% methanol in the mixture resulted in a maximal induction with enzyme specific activities equal to those found in cells grown with methanol as the only carbon source. No further enhancements in enzyme specific activities were observed during growth on mixtures containing more than 40% methanol.
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  • 4
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Mixed substrate utilisation ; Chemostat ; Induction ; Repression ; Methanol ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Hansenula polymorpha and Kloeckera sp. 2201 with a mixture of glucose and methanol (38.8%/61.2%, w/w) and the regulation of the methanol dissimilating enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase were studied in chemostat culture, as a function of the dilution rate. Both organisms utilized and assimilated glucose and methanol simultaneously up to dilution rates of 0.30 h-1 (H. polymorpha) and 0.26h-1, respectively (Kloeckera sp. 2201) which significantly exceeded μmax found for the two yeasts with methanol as the only source of carbon. At higher dilution rates methanol utilisation ceased and only glucose was assimilated. Over the whole range of mixed-substrate growth both carbon sources were assimilated with the same efficiency as during growth with glucose or methanol alone. In cultures of H. polymorpha, however, the growth yield for glucose was lowered by the unmetabolized methanol at high dilution rates. During growth on both carbon sources the repression of the synthesis of all catabolic methanol enzymes which is normally caused by glucose was overcome by the inductive effect of the simultaneously fed methanol. In both organisms the synthesis of alcohol oxidase was found to be regulated differently as compared to catalase, formaldehyde and formate dehydrogenase. Whereas increasing repression of the synthesis of alcohol oxidase was found with increasing dilution rates as indicated by gradually decreasing specific activities of this enzyme in cell-free extracts, the specific activities of this enzyme in cell-free extracts, the specific activities of catalase and the dehydrogenases increased with increasing growth rates until repression started. The results indicate similar patterns of the regulation of the synthesis of methanol dissimilating enzymes in different methylotrophic yeasts.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 298-298 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Closing technique for static coating ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 11 (1980), S. 209-212 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: X-Ray Stress Measurement on Austenitic Steels - A Possibility of Predicting Fatigue DamageBased on the results found for fatigue tests on a ferritic steel combined with x-ray stress analysis similar investigations were carried out for an austenitic stainless steel. For that reason the Wöhler tests were interrupted after defined load cycle numbers and the residual stress and the half value breadth of the x-ray peaks were determined in the groove of the samples. The investigation has shown correlations between residual stress, load amplitudes and load cycle numbers. These relations in connection with a dependence of the breadth of the x-ray peaks from the load cycle number have been used for a non-destructive testing model of predicting the life of samples under alternating load.
    Notes: Aufbauend auf Untersuchungen an einem ferritischen Stahl wurden an Proben aus einem austenitischen Stahl Ermüdungsversuche kombiniert mit Eigenspannungsmessungen durchgeführt. Dazu wurden die Wöhlerversuche definiert nach vorgegebenen Lastwechselzahlen unterbrochen und röntgenografisch die Eigenspannungen und Interferenzbreiten im Kerb der Proben bestimmt. Es zeigten sich Abhängigkeiten der Oberflächeneigenspannungen von Lastamplituden und Lastwechselzahlen, die unter Zuhilfenahme der ebenfalls gefundenen Zusammenhänge zwischen Halbwertbreiten und Lastwechselzahlen dazu herangezogen werden, um auf zerstörungsfreiem Wege auf die Lebensdauer wechselbeanspruchter Proben zu schließen.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 9 (1978), S. 406-413 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Form and Mechanisms of Cracks and Fractures Caused by Simultaneous Corrosive and Dynamic Stress under Various FrequenciesDistinction of crack nucleation and crack propagation under variable frequencies and electrolytic corrosion. Relationship between crack nucleation and frequency due to differing sliding mechanisms. Crack propagation under decreasing frequencies causes transition from corrosion fatigue to cyclic stress corrosion cracking and finally stress corrosion cracking can be observed. Coordination of that transition with the increasing influence of the KISCC-value as determinant of the crack propagation.The influence of frequency on high temperature materals in hot gas atmosphere is mainly determined by creep mechanisms during top-load phase and the gas-metal-reactions. Accordingly the life time increases with growing load frequency.
    Notes: Anrißphase und Phase des Rißfortschritts bei der Betrachtung der Frequenzabhängigkeit unter elektrolytischer Korrosion. Abhängigkeit der Anrißphase von der Frequenz infolge unterschiedlicher Gleitmechanismen. Beim Rißfortschritt erfolgt mit sinkender Frequenz Übergang von Schwingungsrißkorrosion zu zyklischer Spannungsrißkorrosion und schließlich zu Spannungsrißkorrosion. Zuordnung dieses Übergangs zum zunehmenden Einfluß des KISCC-Wertes als Bestimmungsgröße für den Bruchvorgang.Frequenzabhängigkeit bei Hochtemperaturwerkstoffen in Heißgasatmosphäre im wesentlichen bestimmt durch Kriechvorgänge bei Einwirkung der Oberlast und zeitabhängige Gas-Metall-Reaktionen. Entsprechend verlängern sich die Standzeiten mit zunehmender Belastungsfrequenz.
    Additional Material: 16 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 299-308 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The Effect of Moisture on the Mechanical Properties of Phenolic Moulded MaterialsIn order to use thermosetting moulding material it is necessary to know how the mechanical properties are changed by absorption of water. Therefore, multiphase systems based on phenolic resin, with varying quantities of wood flour and/or powdered minerals as fillers, were examined. The relationship between moisture absorption and the change in Young's modulus, flexural strength and the strain of the outer fibre at fracture was determined. It could be shown that the increase in flexural strength as water absorption began is a result only of the swelling stress.
    Notes: Voraussetzung für den Einsatz duroplastischer Formstoffe in erhöhter Umgebungsfeuchte ist die Kenntnis der durch die Feuchteaufnahme bewirkten Änderung der mechanischen Werkstoffeigenschaften. Ausgehend von in ihrer Zusammensetzung variierten Mehrstoffsystemen auf der Basis Phenolharz/Holzmehl/Gesteinsmehl wird die formstoff- und feuchtespezifische Wechselwirkung zwischen Feuchteaufnahme, Biege-E-Modul, Biegefestigkeit und Randfaserdehnung beim Bruch aufgezeigt, und nachgewiesen, daß der zu Lagerungsbeginn zu beobachtende Anstieg der Biegefestigkeit ausschließlich auf durch Sorption hervorgerufene Druck-Eigenspannungen zurückzuführen ist.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 349-359 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The Swelling Behaviour of Thermosetting MaterialsThe moisture absorption of moulded materials can endanger a construction because of the change in volume of various parts. Therefore it is necessary to know the maximum possible swelling of the moulded materials employed at different relative humidities. The swelling of modified phenolic resin systems are described. Wood flour (which absorbs moisture) and powdered minerals (which in this case can be considered as inert) were used as fillers.Different methods have been developed to calculate the maximum possible swelling after a relatively short testing time (ca. 1000 h).
    Notes: Die Feuchteaufnahme eines Formstoffes kann durch die damit verbundene Volumenänderung des Formteils die Funktion einer Baugruppe gefährden. Daher muß die maximal mögliche formstoff- und umgebungsfeuchtespezifische Quelldehnung der eingesetzten Formstoffe bekannt sein. Am Beispiel von Ein-, Zwei- und Dreistoffsystemen mit Phenolharz als Matrixwekstoff wird der Einfluß der Harzträger Holzmehl (im Hinblick auf die Feuchteaufnahme „aktiv“) und Gesteinsmehl („inaktiv“) auf die Quellung untersucht. In diesem Zusammenhang werden Methoden aufgezeigt, die eine Abschätzung der maximal möglichen Quelldehnung nach relativ kurzer Versuchsdauer (etwa 1000 h) ermöglichen.
    Additional Material: 6 Ill.
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  • 10
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Separation of polychloro biphenyls ; Separation of organochlorine pesticides ; Splitless automated injection ; Residue level ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complicated PCB mixtures can be separated in individual compounds using glass capillary gas chromatography, (GC)2. Depending on extraction and clean-up procedure it is also possible to separate and determine organochlorine pesticides at the same time.This (GC)2 technique can be used to determine the contents of individual chlorinated biphenyls in milk products and animal feedstuffs and in the analysis of complicated extracts of soil and vegetable material.Practical aspects concerning connection of the capillary, automatic splitless injection, repeatability of the retention time, quality of the column with respect to separation and adsorption and degradation of DDT are discussed.The detection of individual chlorinated biphenyls is possible at the ppb level in fats and vegetable materials, using an extraction and clean-up procedure, based on saponification of the sample.Preliminary results for milk, obtained from several areas, are shown.
    Additional Material: 6 Ill.
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