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  • 1
    Electronic Resource
    Electronic Resource
    Characteristics of tyrosinase in AOT-isooctane reverse micelles (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 304-308 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isooctane-AOT-H2O is a suitable system for studying enzyme behavior in organic solvents. Tyrosinase was able to catalyze a well-known reaction in aqueous medium: oxidation of 4-methylcatechol to yield 4-methyl-o-benzoquinone. This reaction was studied using the preceding ternary system with adequate amounts of each component to make up reverse micelles. 4-Methyl-o-benzoquinone stability was demonstrated in isooctane even at alkaline pH values. Apparent Km and Vmax were similar to those in water, but substrate inhibition was more evident. The pH and temperature appear to be shifted toward high and low values, respectively. Characteristic parameters of reverse micelles, ω0 (= H2O/AOT) and percentage of H2O (v/v), were investigated. The results obtained showed that the steady-state rate varies either with ω0 or with percentage of H2O. The variation observed with ω0 showed an optimal value while an increase in percentage of H2O can lead to decreased or increased activity depending on substrate concentration.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340305
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  • 2
    Electronic Resource
    Electronic Resource
    An improved algorithm for the generalized rank annihilation method (1989)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 493-498 
    Details
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Generalized rank annihilation method ; Generalized eigenproblem ; Calibration ; Spectral interferents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved algorithm for the generalized rank annihilation method (GRAM) is presented. GRAM is a method for multicomponent calibration using two-dimensional instruments, such as GC-MS. In this paper an orthonormal base is first computed and used to project the calibration and unknown sample response matrices into a lower-dimensional subspace. The resulting generalized eigenproblem is then solved using the QZ algorithm. The result of these improvements is that GRAM is computationally more stable, particularly in the case where the calibration sample contains chemical constituents not present in the unknown sample and the unknown contains constituents not present in the calibration (the most general case).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180030306
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  • 3
    Electronic Resource
    Electronic Resource
    Water absorption characteristics of vinyl alcohol/vinyl propionate copolymers with different microstructure (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 181-194 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Vinylakohol/Vinylpropionat (VAL/VP)-Copolymere mit unterschiedlicher Mikrostruktur wurden durch zwei verschiedene Methoden, nämlich partielle alkalische Hydrolyse von Polyvinylpropionat und partielle Veresterung von Polyvinylalkohol, hergestellt. 13C-NMR Messungen zeigen, daß die Vinylpropionateinheiten in durch Veresterung hergestellten VAL/VP-Copolymeren eine alternierende Tendenz aufweisen, während solche in durch Hydrolyse hergestellten Copolymeren eine Blockverteilung besitzen. Die Wasserabsorptions-Charakteristik der VAL/VP-Copolymeren wurde ebenfalls untersucht. VAL/VP-Copolymere mit Blocksequenz-Verteilung zeigen eine größere Fähigkeit, Wasser zu absorbieren, als VAL/VP-Copolymeren mit einer statistischen Verteilung und gleicher chemischer Zusammensetzung. Die Bildung von intramolekularen Wasserstoffbrückenbindungen oder Effekte sterischer Hinderung können für dieses Verhalten verantwortlich sein. Versuche mit Natriumsalicylat zeigen, daß die Freisetzung von Salicylat aus durch Hydrolyse hergestellten VAL/VP-Copolymeren aufgrund ihrer höheren Quellfähigkeit in Wasser schneller erfolgt.
    Notes: Vinyl alcohol/vinyl propionate (VAL/VP) copolymers with different microstructure were prepared by two different methods, i.e. partial alkaline hydrolysis of poly(vinyl propionate) and by partial esterification of poly(vinyl alcohol). 13C-NMR results show that vinyl propionate units have an alternating tendency in VAL/VP copolymers prepared by esterification and a block distribution in VAL/VP copolymers when they are prepared by hydrolysis. The water absorption characteristics of VAP/VP copolymers have been studied. VAL/VP copolymers with a block sequence distribution exhibit a higher water absorption ability as compared with VAP/VP copolymers with a random sequence distribution and similar chemical composition. These results can be interpreted considering the formation of intramolecular hydrogen bondings as well as due also to steric hindrances effects. Sodium salicylate release studies from VAL/VP copolymers show that release is faster in VAL/VP copolymers prepared by hydrolysis according to its higher swelling ability in water.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051680115
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  • 4
    Electronic Resource
    Electronic Resource
    Electroanalytical study of indomethacin (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 279-282 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Polarographic behavior of indomethacin has been studied with the aim of developing a procedure for its determination in pharmaceutical tablets. In the study of the electrode process, linear-sweep voltammetry and controlled potential coulometry were also considered. The electrode reactions are shown to be strongly affected by variations in pH. Adsorption phenomena appear at certain pH values. Detection limits and sensitivity in the determination of indomethacin were obtained by using tast polarography (TP), differential pulse polarography (DPP), and pseudoderivative pulse polarography (NPP).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010314
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  • 5
    Electronic Resource
    Electronic Resource
    Surface states in deformed and perturbed diatomic crystals (1989)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 36 (1989), S. 553-561 
    Details
    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: The electronic properties of a one-dimensional diatomic crystal have been analyzed by using the MO-LCAO method in the tight binding approximation, with mathematical techniques involved in setting up and solving difference equations. The approach gives the exact sets of analytic solutions for both localized and nonlocalized states. The theory of surface states is developed as a characteristic value problem. To illustrate the method the surface states for a semiinfinite crystal which contains a local imperfection at the surface were examined. It appears that this method has advantages over previous methods developed to solve surface problems in crystalline lattices.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560360503
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  • 6
    Electronic Resource
    Electronic Resource
    Potential H1-Antihistaminic Drugs: Synthesis of 4-[(2,3-Dihydro-2-oxo-1H-benzimidazol-1-yl)alkoxycarbonyl]-1-(diphenylmethyl)piperazines by Selective Monoalkoxycarbonylation of α,ω-Dichloroalkanes by Phase-Transfer Catalysis (1989)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 539-544 
    Details
    ISSN: 0170-2041
    Keywords: H1-Antihistaminic ; Piperazines ; Phase-transfer catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Potentielle H1-Antihistaminica: Synthese von 4-[(2,3-Dihydro-2-oxo-1H-benzimidazol-1-yl)alkoxycarbonyl]-1-(diphenylmethyl)piperazinen durch selektive Phasen-Transfer-katalysierte Monoalkoxycarbonylierung von α,ω-DichloralkanenDie Synthese einer Reihe von neuen 4-[(2,3-Dihydro-2-oxo-1H-benzimidazol-1-yl)alkoxycarbonyl]-1-(diphenylmethyl)piperazinen 2 durch Phasen-Transfer-katalysierte Monoalkoxycarbonylierung von α,ω-Dichloralkanen wird beschrieben. Die Piperazine 2 ähneln Oxatomid1) (1) und sind potentielle H1-Antihistaminica. Ferner wurde eine Untersuchung zur regioselektiven Synthese von substituierten 1,3-Dihydro-1-isopropenyl-2H-benzimidazol-2-onen (5) durchgeführt.
    Notes: The synthesis of a series of new 4-[(2,3-Dihydro-2-oxo-1H-benzimidazol-1-yl)alkoxycarbonyl]-1-(diphenylmethyl)piperazines 2 by phase-transfer catalysed monoalkoxycarbonylation of α,ω-dichloroalkanes is described. Compounds 2 are related to oxatomide1) (1) and are potential histamine-H1 antagonists. A study on the regioselective preparation of substituted 1,3-dihydro-1-isopropenyl-2H-benzimidazol-2-ones (5) was also carried out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198919890195
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  • 7
    Electronic Resource
    Electronic Resource
    The tautomerism of 1,2,3-triazole, 3(5)-methylpyrazole and their cations (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 426-433 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The annular tautomerism of 1,2,3-triazole and 3(5)-methylpyrazole is discussed by means of a combination of theoretical calculations and experimental (ICR) gas-phase basicities and acidities. In the gas phase 1,2,3-triazole exists as the 2H-tautomer, whereas both tautomers of 3(5)-methylpyrazole are of similar energy. The solvent effects on these prototropic equilibria are discussed taking into account solvent properties as polarity/polarizability, acidity, and basicity. In nonhydrogen bonding solvents, the difference in dipole moments between both tautomers plays a role that has usually been underestimated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100318
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  • 8
    Electronic Resource
    Electronic Resource
    Controlled release behaviour of 2-acetoxybenzoic acid-dextran conjugates (1989)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 10 (1989), S. 431-433 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1989.030100809
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  • 9
    Electronic Resource
    Electronic Resource
    Glycolysis and glutaminolysis in perifused ehrlich ascites tumour cells (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 7 (1989), S. 7-10 
    Details
    ISSN: 0263-6484
    Keywords: Glycolysis ; glutaminolysis ; tumour ; perifused cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A perifusion system was designed in order to study glucose and glutamine metabolism by freshly harvested Ehrlich ascites tumour cells in steady state conditions. Cells were perifused in the presence of 5 mM glucose, 0·5 mM glutamine or 5mM glucose and 0·5 mM glutamine. The results in steady state reveal that both substrates glucose and glutamine are continuously wasted by tumour cells, excreting two moles of lactate per mol of glucose and one mol of glutamate and ammonia per mol of glutamine consumed into the medium. Glutamine consumption in the presence of glucose was higher than with glutamine alone.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cbf.290070103
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of 2-acetoxybenzoic acid-dextran ester conjugates (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 2391-2396 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work deals with the modification reaction of dextran with 2-acetoxybenzoyl chloride (acetylsalicyloyl chloride) using tertiary amines as catalyst/acceptor systems and the DMF/LiCl system as solvent. The structure of the resulting polymers was determined by means of IR, 1H and 13C NMR spectroscopy. Transesterification reactions were observed when 4-dimethylaminopyridine or pyridine were used as catalysts, with the formation of acetoxy, 2-hydroxybenzoyloxy (salicyloyloxy) and 2-acetoxybenzoyloxy (acetylsalicyloxy) groups. When triethylamine was used as catalyst, only acetylsalicyloyloxy groups were found to be grafted onto the polymer chain. A linear dependence of the reaction rate on the concentrations of polymer, acetylsalicyloyl chloride and triethylamine was found. The activation energy was found to be 13,8 kJ/mol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021901005
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