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  • Chemistry  (104)
  • 2000-2004
  • 1970-1974  (50)
  • 1960-1964  (46)
  • 1945-1949  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Electron-impact fragmentation of the bicyclo[4.1.0]heptane-2-one system: Correlations with photochemistry (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 1-11 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The low resolution and complete high resolution mass spectra of a series of methyl and deuterium substituted bicyclo[4.1.0]heptane-2-one derivatives have been measured. An attempt has been made to test the operation of a fragmentation process analogous to the known photochemical rearrangement, and to determine if the substitution effects critical to the photorearrangement also influence the electron-impact process. The fragmentation pattern of these conjugated cyclopropyl ketones is detailed and the influence of the cyclopropyl ring is discussed. It is suggested that electron-impact-induced rearrangements which are analogous to photochemical transformations will be relatively low energy processes and will remain prominent at low ionizing voltages.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210030102
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and properties of fluorescent components associated with calcified tissue collagen (1971)
    Springer
    Calcified tissue international 8 (1971), S. 197-210 
    Details
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010138
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  • 3
    Electronic Resource
    Electronic Resource
    The dynamics of the helix-coil transition in poly-α, L-glutamic acidAn account of this work formed part of a paper delivered at the Fifth International Congress of Biochemistry, Moscow, 1961. (1964)
    New York : Wiley-Blackwell
    Biopolymers 2 (1964), S. 489-500 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Temperature jump measurements employing optical rotation to follow transients show an upper limit of 10μsec. on the half time of the helix-random coil relaxation in poly-α, L-glutamic acid. No relaxations are observed under conditions where the polymer exists in completely helical or completely random coil form. Assuming that the helix-coil transition can be described kinetically as a pure growth process, expressions for the relaxation time are derived for three special cases. A comparison is made between the rate of the helix-coil transition and the rate of imide proton exchange.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1964.360020507
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  • 4
    Electronic Resource
    Electronic Resource
    Die Krystallstruktur der kubischen Modifikation von organischen Verbindungen mit kugelförmigen Molekeln (1947)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 30 (1947), S. 1782-1783 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19470300646
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  • 5
    Electronic Resource
    Electronic Resource
    Maintaining perpetual synchrony in HeLa S3 culture (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 16 (1974), S. 149-156 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: HeLa S3 cells in suspension culture are resynchronized in each successive generation by exposure to 0.25mM thymidine. The resynchronization approach appears to be superior to single- and double-block techniques because the period of effective inhibition of DNA synthesis is significantly shortened. Gram quantities of highly synchronous viable cells have been produced on a daily basis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260160111
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  • 6
    Electronic Resource
    Electronic Resource
    Microbial production of amino acids. I. The synthesis of lysine and threonine by ustilago species (1962)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 23-36 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of a number of Ustilago species, especially Ustilago maydis (DC.) Cda., to produce lysine and threonine was investigated. The organisms were grown in shake flasks or in 10-l. fermentors. Lysine and threonine were found to be excreted into the medium both in the free and bound form. The bound amino acids could be released by acid hydrolysis or by enzymes from autolyzed cells. The optimal conditions for the release by autolysis were, in the case of Ustilago maydis (DC.) Cda., pH 4.3 and 45°C. An enzyme that could liberate lysine from the bound form(s) occurring in the broth was extracted from cells of Ustilago maydis (DC.) Cda. It exhibited an apparent pH optimum near 4.0. The effect of pH and temperature during the growth phase on the yield of lysine and threonine was studied in 10-l. fermentations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260040105
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  • 7
    Electronic Resource
    Electronic Resource
    Microbial production of amino acids. II. The influence of carbon and nitrogen sources and metal ions on growth of Ustilago maydis (DC.) Cda. and on lysine and threonine production (1962)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 4 (1962), S. 37-52 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of Ustilago maydis (DC.) Cda. to grow and to produce lysine and threonine was investigated in shake flask cultures. Growth and production of lysine and threonine increased markedly when aeration was increased. The optimal ratio of glucose to diammonium phosphate in the medium seemed to be approximately 10:1. Ammonium phosphate, ammonium sulfate, ammonium chloride, ammonium nitrate, sodium nitrate, urea, aspartic acid, glutamic acid, and glycine were readily used as nitrogen sources. Growth and amino acid production was poor on ammonium carbonate, ammonium acetate, ammonium citrate, trimethylamine, and betaine.U. maydis (DC.) Cda. was found to grow on a number of different carbohydrates. Besides D-glucose the organism could utilize D-mannose, D-galactose, D-fructose, L-arabinose, D-xylose, D-ribose, sucrose, maltose, and the polyalcoholes D-sorbitol, D-mannitol, and i-inositol. Pectin, dextrin, and corn starch treated with α-amylase could also be used but not untreated corn starch or lactose, cellobiose, D-sedoheptulose, glycerol, or D-glucosamine. The formation of lysine and threonine was better with disaccharides and hexoses than with pentoses.No specific effects on the formation of lysine and threonine could be observed from changes in the concentration of calcium, sodium, potassium, magnesium, zinc, iron, copper, manganese, cobalt, or molybdenum. The requirement of metal ions for growth is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260040106
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  • 8
    Electronic Resource
    Electronic Resource
    Kontrollmessungen an kathodisch geschützten RohrleitungenNach einem Vortrag erstattet auf dem 3. Kongreß der Europäischen Föderation Korrosion, Brüssel, Juni 1963. (1964)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 15 (1964), S. 201-212 
    Details
    ISSN: 0947-5117
    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: Control measurements on cathodically protected pipelinesThe most important control measurement for the cathodic protection of buried pipelines is the measurement of the pipel soil potential. On the strength of experimental and theoretical investigations, it is possible to indicate safe protection potentials at which the corrosion rate becomes practically insignificant. In applying the scientific results of electro-chemistry to cathodic protection in practice, problems may be encountered if phenomena are over-simplified or if local conditions are not sufficiently taken into account.Such practical problems are not so much concerned with measuring instruments and reference electrodes; they are more associated with the measuring methods subsequently described and with the fact that influence factors difficult to ascertain must be taken into account.The cathodic polarisation at the metal surface to be protected is composed of overtensions of a penetration and a diffusion type. In addition, there occurs a resistance polarisation which may be governed, on the one hand, by the ohmic voltage drop between pipe surface and reference electrode and, on the other hand, by poorly conducting coating or insulating layers. The latter usually cause, at the same time, a change in the diffusion type overtension. Since the resistance polarisation does not partake in the reaction kinetics, this influence must be eliminated in measuring the protection potential. Since the different types of polarisation have different type curves, it is possible to ascertain the separate partial reactions in accordance with the normal methods of electro-chemistry. By means of oscillographic recordings of potential/time curves, through calculation or with the aid of suitable measuring bridges, it is possible to eliminate the resistance polarisation or to determine the ohmic voltage drop in the electrolyte.
    Notes: Die wichtigste Kontrollmessung für den kathodischen Schutz erdverlegter Rohrleitungen ist die Messung des Rohr/Boden-Potentials. An Hand experimenteller und theoretischer Untersuchungen ist es möglich, sichere Schutzpotentiale anzugeben, bei denen die Korrosionsgeschwindigkeit praktisch bedeutungslos wird. Bei der Anwendung wissenschaftlicher Ergebnisse der Elektrochemie auf den kathodischen Schutz in der Praxis können Probleme auftreten, wenn Vorgänge zu stark vereinfacht und örtliche Gegebenheiten nicht genügend berücksichtigt werden.Solche praktischen Probleme liegen weniger bei Meßgeräten und Bezugselektroden, als bei den anschließend beschriebenen Meßverfahren und der Berücksichtigung schwer erfaßbarer Einflußgrößen. Die kathodische Polarisation an der Zu schützenden Metalloberfläche Setzt sich aus einer Durchtritts- und einer Diffusionsüberspannung zusammen. Ferner tritt eine Widerstandspolarisation auf, die einerseits durch den Ohmschen Spannungsabfall zwischen Rohroberfläche und Bezugselektrode, andererseits durch schlecht leitende Deck- oder Isolierschichten gegeben sein kann. Letztere verursachen meist gleichzeitig eine Änderung der Diffusionsüberspannung. Da die Widerstandspolarisation keinen Anteil an der Reaktionskinetik besitzt, muß ihr Einfluß bei der Schutzpotentialmessung eliminiert werden. Auf Grund eines zeitlich unterschiedlichen Verhaltens der Polarisationsarten gelingt die Aufspaltung der einzelnen Teilreaktionen nach den in der Elektrochemie üblichen Verfahren. Durch oszillographische Aufnahme won Potential-Zeitkurven, durch Rechnung oder mit geeigneten Meßbrücken kann die Widerstandspolarisation ausgeschaltet bzw. der Ohmsche Spannungsabfall im Elektrolyten ermittelt werden.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19640150302
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  • 9
    Electronic Resource
    Electronic Resource
    Liquid-side mass transfer coefficients in packed towers (1960)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 6 (1960), S. 174-175 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690060137
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  • 10
    Electronic Resource
    Electronic Resource
    Performance of packed columns: IX. Simulation of a packed column (1971)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 631-640 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model is described which may be used to simulate a packed column for countercurrent gas-phase controlled absorption with liquid-phase reaction. The model consists of a number of continuous stirred-tank reactors in parallel with equal volumes and mass transfer areas. A distribution is presented which uses one parameter to determine the fraction of total liquid throughput going to each reactor. The model successfully predicts all responses, including those of Kga versus time for no reaction, Kga versus inlet acid normality, and Kga versus inlet gas concentration for liquid-phase reaction for the systems ammonia-water and ammonia-sulfuric acid. It also explains the increase in mass transfer obtained by pulsing and controlled cycling.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690170328
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