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  • 1
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A design equation is presented for packed-bed reactors containing immobilized enzymes in spherical porous particles with internal diffusion effects and obeying reversible one-intermediate Michaelis-Menten kinetics. The equation is also able to explain irreversible and competitive product inhibition kinetics. It allows the axial substrate profiles to be calculated and the dependence of the effectiveness factor along the reactor length to be continuously evaluated. The design equation was applied to explain the behavior of naringinase immobilized in Glycophase-coated porous glass operating in a packed-bed reactor and hydrolyzing both p-nitrophenyl-α-L-rhamnoside and naringin. The theoretically predicted results were found to fit well with experimentally measured values.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heteroaromatische nucleophile Substitutionsreaktionen durch Phasen-Transfer-Katalyse- Synthese von neuen Alkoxypyridazin-3(2H)-onenDie Synthese von einigen 4- und 5-alkoxysubstituierten Pyridazin-3(2H)-onen mit hypotensiver und β-blockierender Wirkung durch Phasen-Transfer-Katalyse aus Halogenpyridazin-3(2H)-onen wird beschrieben. Der nucleophile Austausch verläuft recht glatt in der 5-Stellung aber viel langsamer in der 4-Stellung. Im Falle von 4,5-Dihalogenpyridazin-3(2H)-onen ergibt die Phasen-Transfer-Katalyse eine hohe Regioselektivität für die Substitution in 5-Stellung.
    Notes: The synthesis of several 4- and 5-alkoxy-substituted pyridazin-3(2H)-ones with hypotensive and β-blocking activities by phase-transfer catalysis (PTC) starting from halopyridazin-3(2H)-ones is described. The nucleophilic displacement reaction proceeds easily at the 5-position and remarkably slower at the 4-position. In the case of 4,5-dihalopyridazin-3(2H)-ones the PTC methods provide a high regioselectivity towards substitution in 5-position.
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 7 (1993), S. 427-438 
    ISSN: 0886-9383
    Keywords: Quality control ; Kerosene ; Variable reduction ; Cross-validation ; Variable selection ; Procrustes rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper deals with a typical question encountered in all industrial analytical laboratories: are all the tests performed in the laboratory to characterize the final product really necessary? In this work the cross-validation technique, Procrustes rotation techniques and statistical variable selection have been used to reduce the 26 initial British Petroleum and ASTM kerosene specification test to ten ‘essential’ ones. Statistical as well as chemical considerations were used to select the optimum subset of original variables to be retained from all the possible ones.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2469-2477 
    ISSN: 0887-624X
    Keywords: acyclic dience metathesis ; ADMET ; depolymerization ; aqueous ring-opening metathesis polymerization ; ROMP ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acyclic dience metathesis (ADMET) depolymerization of functionalized furan-based polymers prepared via aqueous ring-opening polymerization of 7-oxanobornenes has been investigated. Results indicate that while very high molecular weight poly [exo-N-methyl-7-oxabicyclo [2.2.1] hept-2,5-diene-2,3-dicarboximide] can be depolymerized to oligomers with ease, poly [2,3-dicarbomethoxy-7-oxabicyclo [2.2.1] hept-2,5-diene] is more resistant to depolymerization under similar conditions. This difference may be due to differential interaction of the carbonyls in the side chains with the metal atom of the catalyst in the proposed metallacyclobutane intermediate. ADMET depolymerization of poly [2,3-bis (trifluoromethyl)-7-oxabicyclo [2.2.1] hept-2,5-diene] was feasible, however, the extent of depolymerization was decreased due to the use of a coordinating solvent (THF) used during the depolymerization process. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 5
    ISSN: 0899-0042
    Keywords: arylpropionic acid ; ketoprofen ; enantiomer ; stereoselectivity ; Coenzyme A thioester ; hybrid triacylglycerols ; inversion ; adipose tissue ; hepatocytes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomeric bioinversion of ketoprofen (KP) enantiomers and their incorporation into triacylglycerols were investigated in the rat (1) in vitro, using liver homogenates, subcellular fractions, and hepatocytes, and (2) in vivo, in different tissue samples after oral administration of the radiolabelled compounds. In liver homogenates or subcellular fractions, the enantiomer (S)-ketoprofen (S-KP) was recovered unchanged, whereas (R)-ketoprofen (R-KP) was partially converted into its Coenzyme A (CoA) thioester and inverted to S-KP. Both processes occurred mainly in the mitochondrial fraction. This supports the mechanism of inversion via stereoselective formation of CoA thioesters of R-KP, already described for other non-steroidal anti-inflammatory drugs. Incorporation into triacylglycerols was detected after incubation with intact hepatocytes in the presence of added glycerol. The process was stereoselective for R-KP vs. S-KP (covalently bound radioactivity 26,742 ± 4,665 dpm/106 cells vs. 6,644 ± 3,179 dpm/106 cells, respectively). However, no incorporation was found in liver samples after oral administration of either R-KP or S-KP. On the contrary, in adipose tissue samples a significant and stereoselective formation of hybrid triacylglycerols was observed: 11,076 ± 2,790 dpm.g-1 for R-KP vs. 660 ± 268 dpm.g-1 for S-KP. The incorporated R/S ratio, higher in adipose tissue (R/S = 17) than in hepatocytes (R/S = 4), indicates that fat may be the main tissue store for the xenobiotic R-KP in rats. © 1996 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 5 (1988), S. 77-84 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper is based on the development of the Moza-Austin technique for characterizing thousands of coal particles by approximate analysis of the major inorganic constituents Ca, Al, Si, K, Na, Fe and S in each particle. The technique has sufficient sensitivity to work on small volumes, is fast enough to handle large number of particles within a reasonable period of time, and consists of scanning electron microscopy combined with energy dispersive x-ray spectrometry (SEM-EDS). A computerized SEM-EDS system that allows the automated analysis of hundreds of particles per hour is described. The analysis is based on the location and tracing of exposed areas of particles embedded in a polished specimen, the selection of sampling points on the traced sections, the collection of an x-ray spectrum from each sampled point for a defined period of time, and the processing of the x-ray intensity to calculate point composition using ZAF corrections. Procedures for correcting for dead time, spectrum background, x-ray detector efficiency and spectrum overlap are described. Problems and future work are discussed.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 20-21 
    ISSN: 0935-6304
    Keywords: Capillary GC ; GC-MS ; Gorse pyrolytic oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermochemical conversion of biomass produces solid charcoal, gaseous fuels, and condensable oils. Because these oils vary widely in composition depending on the cellulosic feedstock and the operating conditions used, analysis of the oils is necessary in order to determine the best ways of utilizing or disposing of them. The major components of the organic oil from pyrolysis of gorse have been characterized by capillary gas chromatography - mass spectrometry. A qualitative study of the aqueous oil from the same source has also been attempted.
    Additional Material: 2 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 36 (1995), S. 345-351 
    ISSN: 0959-8103
    Keywords: viscometry ; densimetry ; unperturbed dimensions ; preferential interactions ; poly(N-vinyl-2-pyrrolidone) ; CdCl2 ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The poly(N-vinyl-2-pyrrolidone)(PVP)(2)/water(1)/CdCl2(3) ternary system has been studied by viscometry, densimetry and atomic absorption spectrophotometry. In this system a preferential adsorption of Cd2+ at all solvent compositions studied and a conformational transition at 4mM of salt, the concentration at which a preferential adsorption minimum of Cd2+ in exhibited, are observed. The PVP/Cd2+ bound molar ratio is 0·23. CdCl2 behaves as a salting-in agent for the macromolecule. The binary solvent mixture is thermodynamically more favourable at salt concentrations greater than 10 mM of CdCl2.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 61-76 
    ISSN: 1057-9257
    Keywords: magnetic molecular materials ; conducting molecular materials ; polyoxometalates ; TTF ; ET ; conducting polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The different approaches used by the authors for the synthesis of new molecular materials exhibiting simultaneously magnetic and conducting properties are presented here. The aim is to prepare materials where a magnetic and a conducting sublattice coexist and/or interact in order to obtain either coexistence of properties or coupling between them. The strategy described is a hybrid one that combines various types of inorganic metal complexes with planar organic π-electron donors of the TTF family or with organic matrices made of conducting polymers. There are four main combinations: (i) magnetic polyoxometalates with organic donors - this strategy has already produced more than 10 radical salts where a magnetic character coexists with a conducting or semiconducting one; (ii) small magnetic anions with organic donors - in this case one of the most promising results has been the synthesis of one of the very few known examples of magnetic molecular metals; (iii) ferro- and ferrimagnetic oxalate-bridged bimetallic layers with organic donors; (iv) magnetic polyoxometalates incorporated into electrodeposited films of conducting polymers. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 18 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 1685-1698 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The nucleophilic substitution reactin of poly(vinyl chloride) (PVC) with sodium benzenethiolate (NaBT) has been studied in the melt with the aim of determining whether a conformational mechanism is applicable under conditions that would apply in the polymer processing. The evolution of unreacted syndio, hetero, and isotactic triads content, and of the apparent molecular weight has been followed by 13C-NMR and GPC, respectively. The kinetic behavior was defined by choosing appropriate mixing conditions of temperature, shear stress, load, and amount of plasticizer. In all cases the kinetic curves attain a plateau after a rather fast reaction period has elapsed. The conversion at the plateau, that is, the reaction efficiency, proved to depend linearly on the amount of nucleophile and is hardly influenced by the mixing conditions for a given stoichiometric composition. The mixing conditions have been found to affect markedly the kinetics but to be quite inoperative on the evolution of both the content of unreacted tactic triads and the apparent molecular weight with degree of conversion. The results are discussed by taking into consideration those previously obtained in solution.
    Additional Material: 11 Ill.
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