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  • 1985-1989  (224)
  • 1987  (224)
  • Life Sciences (general)  (133)
  • Physical Chemistry
  • 101
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 111-118 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The investigations demonstrate that in addition to Saccharomyces also strains Candida and Hansenula can be used for ethanol production. Their efficiences are at the standard level and the first phase of fermentation is considerably accelerated with results in suppression of bacterial contamination in cold mashing. In the future efficiency optimisations will be expected based on mixed strain populations as well as on technological improvement. Furthermore, genetic modifications present actually a real prospect to secure “made-to-measure” strains for special processes of corn mash fermentation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 126-126 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 103
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 135-145 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: To enhance the digestibility of wheat straw as an animal feedstock a partial delignification by action of 1percnt; aqueous alkali in combination with mechanical pre- and after-treatment steps is proposed. On the basis of in vitro digestibility by cellulase the influence of various process parameters on the effect obtained is summarized. Sheep feeding studies comparing original and chemomechanically pretreated straw confirm the suitability of the process-principle proposed for upgrading cereal straw. The practical feasibility of the process is considered with regard to animal nutrition and technology.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 104
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 156-156 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 105
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 106
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 529-534 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In the fodder yeast production from sulfite spent liquor (SSL) the content of yeast-poisons in the SSL is of particular importance. The negative influence of sulfur dioxide has been known for a long time.Furfural is also named as a pollutant. Our own works showed that there is only an influence on the RS-analysis and in this way a decrease of yield is simulated but not genuine.Practical results and theoretical calculations showed that 1.0 gram of furfural is equivalent to 1.88 g RS.This knowledge is of importance for carrying out the production process by simultaneous change of the furfural concentration. In this way the charge of the fermenter with carbohydrate can be too high or too low.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 107
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 547-553 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The article summarizes the work of this laboratory on the design of eleven types of amperometricpenzyme electrodes mainly based on the CLARK oxygen sensor in connection with cross-linked oxidases. Special attention is paid to the sensors coupled with plant tissue slice for determining L-ascorbic acid and phenols. A “second generation” bienzyme electrode is reported which enables tow analytes forming a metabolic couple to be determined simultaneously. A principle of the first useful model of conductimetric enzyme electrode for assaying urea and arginase is also presented.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 563-566 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Kluyveromyces bulgaricus cells were immobilized in matrices resisting to complexing anions. Yeast entrapped in alginate stabilized by polyethylenimine and glutaraldehyde were unable to hydrolyse whey owing to the inactivation of β-galactosidase by the stabilizing agents. Chitosan was resistant to whey medium but decreased the yeast hydrolyzing capacity by 15% with respect to alginate. The hydrolysis rate was found to be unchanged for 37 days at 21-25°C.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 109
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 568-569 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 110
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 571-571 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 111
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 226-226 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 112
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 237-245 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In commercial batch processes the productivity of product formation is low. But a significant increase of productivity can be achieved in continuous fermentations. By using high flow rate fermenter systems characterized by a relatively long retention time of biomass in comparison with the retention time of the liquid we can realize a high-performance fermentation. The problem of holding back the biomass within the reactor could be solved by means of membranes being impenetrable to the cells, but permeable to the hydraulic phase. Such a process technology was successfully tested for its applicability in alcoholic and lactic acid fermentations. The maximum productivities obtained on this way were ṗ = 120 g/l. · h for ethanol production and ṗ = 51 g/l. h for lactic acid fermentation, respectively.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 227-235 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The digestion of several proteins, casein, α-lactalbumin, human serum albumin and a mixture of whey proteins by immobilized pronase, thermitase and leucine aminopeptidase was studied on various conditions in five types of enzyme reactors. Reactors and operating conditions were designed to maximize the extent of hydrolysis and to minimize the adverse effects of the macromolecular nature of the substrates. A simple analytical method was developed to follow routinely the extent of hydrolysis. Substrate proteins were subjected to various pretreatments intended to disturb their native structure. The maximum feasible extent of hydrolysis in the reactor effluent, which is an average quantity, clustered around the magic figure of 33% in all systems studied. Protein digestion in bubbled column reactors charged with the polyaminomethylstyrene-fixed thermostable proteinase “thermitase” and operated at 50 to 60°C turned out to be the most efficient setup to produce continuously amino acid/peptide mixtures.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 114
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 279-283 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The investigation of unfitness of beet molasses for citric acid production shows the presence of hydroacarbons in a toxic fraction of lipid extracts derived from antifoaming agents used in the suger industry. The model experiments demonstrate that these compounds dispersed in water solutions of the medium create on the surface of growing spores a layer which isolates them from the surrounding and prevents their normal growth. The inhibition effect of hydrocarbons on Aspergillus niger increases with degree of their dispersion in the water phase and is promoted by surface active substances e.g. emulgators present in antifoaming additives.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 115
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 284-284 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987) 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 117
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 295-297 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 118
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 298-298 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 119
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 120
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 331-336 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Growing and resting cells of microorganisms are able to accumulate metal ions.These reactions are based on a storage within the cells as well as sorption at the cell wall.The intracellular storage takes place preferably by growing cells.The stored amounts of metals by resting cells depend on the concentration of metal ions in the aqueous phase, the pH-value, and, in some cases on the temperature.Maximum concentrations for some metals and strains of microorganisms are given.The representation of the uptake reaction as an adsorption process using a FREUNDLICH-Isotherm demonstrates straight lines with different clopes.The removal of the metals from the biomass by a desorption reaction is possible in some cases, other possibilities are a reducing process or the formation of an ash of the biomss containing compounds of metals.These reactions may be used simultaneously for detoxification and removal of metals from waste water.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 121
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 454-454 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 122
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 455-460 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: It was analysed the influence of different pretreatment methods of cellulosic materials to increase the productivity of the cellulase biosynthesis.The most effective pretreatment method for cotton cellulose is the thermomechanical destruction in a worm extruder (5-15 minutes) with hydrolysis catalysts.The enzymatic saccharification degree was increased about 4 fold. Utilizing a pretreated cellulose an increase of 70-120% in C1-activity was found besides their level was stabilized in higher values.It was demonstrated that enzymatic hydrolysis parameters would be applied as model for biochemical utilization of cellulosic materials in the biosynthesis of cellulases.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 123
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 124
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 484-484 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 125
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 487-497 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The applicability of biotechnological methods to metal recovery from non-sulfide industrial waste products (slag, galvanic sludge, filter-press residue, filter dust, and fly ash) was investigated. From some products, copper, chromium, zinc or vanadium were completely extracted by sulfuric acid produced by Thiobacillus thiooxidans. The efficiency of bacterial metal solubilization varied depending on the type of waste material and on the pulp density. Stepwise increase of pulp density promoted bacterial growth and activity, resulting in metal concentrations of 6.6 g Cu/l, 6.3 g V/l, 24.4 g Zn/l or 21 g Cr/l in the leaching medium. In some cases bacterial leaching was as effective as chemical leaching with sulfuric acid. The efficiency of both processes is considered. In principal, bacterial metal recovery from industrial waste products seems to be feasible and may contribute to an increase in future supplies of raw materials, as well as to detoxification of industrial waste products resulting in reduced environmental pollution problems.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 520-520 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 127
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The influence of different concentrations of magnesium, potassium, phosphorus and copper on the growth kinetics of the methanotrophic bacterium GB 25 was investigated. Diverse inhibition models were used for the mathematical description of the results. On the basis of these model equations the optimal concentrations of the investigated ions were derived. Copper causes the greatest inhibition, on the contrary, potassium practically does not inhibit the growth of bacterium GB 25.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 128
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 546-546 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 129
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 554-554 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 130
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
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  • 131
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 415-434 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The aqueous cleavage of methyl salicylate has been studied in the buffer solutions of various primary mono- and di-amines as well as secondary amines at 30°C. Both ionized (MS-) and nonionized (MSH) methyl salicylate are reactive toward primary mono- and di-amines. The second-order rate constants for the reactions of MS- with primary mono- and di-amines of pKa 〉 9.4 exhibit Bronsted plot of slope (βnuc) of 0.82. This high value of βnuc is attributed to an intramolecular proton transfer in a thermodynamically unfavorable direction in the rate-determining step in a stepwise process for the formation of monoanionic tetrahedral intermediate. However, a concerted process for the formation of a monoanionic tetrahedral intermediate in the reactions of MS- with amine nucleophiles wherein expulsion of leaving group is a rate-determining step is not completely ruled out. The α-effect nitrogen nucleophiles hydroxylamine and hydrazine reveal, respectively, ca. 104- and 103-fold higher reactivity compared to other amine nucleophiles of comparable basicity. The value of βnuc of 1.03 obtained for the reactions of primary monoamines with MSH is ascribed to the expulsion of leaving group as the rate-determining step. The significantly lower value of βnuc of 0.60 obtained in the reactions of MSH with both monoprotonated and unprotonated diamines is explained in terms of possible occurrence of intramolecular general acid-base catalysis. Intramolecular general base catalysis is responsible for the enhanced nucleophilic reactivity of primary amines toward MS-. Dimethylamine, piperidine, morpholine, and piperazine have no detectable nucleophilic reactivity toward MS-.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 132
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 133
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 1073-1082 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constants of the gas phase reaction of OH radicals with dimethyl sulfide (CH3SCH3) over the temperature range 260-393 K have been studied using the discharge flow-resonance fluorescence technique. The rate constants were fitted by the Arrhenius equation k = (11.8 ± 2.2) × 10-12 exp[-(236 ± 150)/T] cm3 molecule-1 s-1 with k = (5.5 ± 1.0) × 10-12 cm3 molecule-1 s-1 at 298 K. Our results are in good agreement with the lower range of values reported previously. The observation of a small positive activation energy agrees well with that reported by Hynes et al. The rate constant was not affected by the total pressure variation (0.8-3.0 torr) or by the addition of oxygen (up to 1 torr) in the flow tube.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 134
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 1107-1107 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Br atoms produced in a microwave discharge react abnormally rapidly with isobutane to produce HBr + t-Butyl. A VLPR study of the system at high Br atom concentration (Br ˜ 1013/cc) between 298 and 363 K permits one to separate the effects of excited atoms, Br* (2P1/2) from ground state atoms, Br (2P3/2). Rate constants for the latter agree well with bromination measurements and permit fixing ΔHƒ2980(tBu) at 9.5 ± 0.5kcal/mol in agreement with earlier work.
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  • 135
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 319-362 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Experimental data for the reaction of O atoms with NH3 have been reviewed with particular attention to the possible effects of secondary reactions on the deduced rate coefficient. A reaction mechanism was assembled and computer calculations carried out to simulate several sets of experiments. The sensitivity of the calculations to uncertainties in the various rate coefficients was assessed. Transition-state theory calculations were carried out on the rate coefficient k1 for the O + NH3 → OH + NH2 reaction. These studies suggest that the reaction stoichiometry is dependent on temperature, initial reagent ratios, and extent of reaction; that available data are not sufficient to determine whether the initial step is H-atom abstraction (producing OH and NH2 radicals) or O-atom addition (producing an NH3O* complex): and that the low temperature values of k1 (T ≤ 400 K) are not consistent with values deduced at higher temperatures if the reaction proceeds by H-atom abstraction. Taking all the evidence into account, it is recommended that the expression 1.1 × 103 T2.1 exp(-2620/T) L mol-1 s-1 be used for k1 until more definitive experimental measurements are made at low temperatures.
    Zusätzliches Material: 2 Ill.
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  • 136
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 137
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 391-400 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: By allowing the t-butoxy radical to decompose in the presence of nitric oxide, it has been possible to determine rate constants for decomposition by the measurements of the relative rates (2) and (3) Process (3) is clearly pressure dependent. The value of k3(∞) has been determined in the presence of several inert gases (CF4, SF6, N2, and Ar) and a value of k3 interpolated for atmospheric conditions. The results may be compared with those for other relevant alkoxy radicals at room temperature. Extrapolated values for k3 in the presence of CF4 lead to the result \documentclass{article}\pagestyle{empty}\begin{document}$$ k_3 (\infty)/s^{ - 1} = 10^{14.6 \pm 0.6} \exp (- 8052 \pm 604/T) $$\end{document}
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 138
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 401-413 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Disproportionation-combination rate constant ratios, kd/kc, have been determined for R + RCH2CHCl and for the auto disproportionation-combination of RCH2CHCl radicals, R = CF3, C2F5, and C3F7. The kd/kc for R = CF3 and to a lesser degree for R = C2F5 and C3F7 were very sensitive to the surface/volume ratio of the reaction vessel suggesting a heterogeneous component for disproportionation.
    Zusätzliches Material: 4 Ill.
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  • 139
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 373-389 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The average downward energy transfer (〈Δ Edown〉) is obtained for highly vibrationally excited acetyl chloride with Ne and C2H4 bath gases at ca. 870 K. Data are obtained by the technique of very low-pressure pyrolysis (VLPP). Fitting these data by solution of the appropriate reaction-diffusion integrodifferential master equation yields the gas/gas collisional energy transfer parameters: 〈Δ Edown〉 values are 220 ± 10 cm-1 (Ne bath gas) and 330 ± 20 cm-1 (C2H4).These energy transfer quantities are much less than those predicted by statistical theories, or those observed for similar sized molecules such as CH3CH2Cl. These results are explained by the qualitative predictions of the biased random walk model wherein the fundamental mechanism of energy transfer is the multiple interactions between the bath gas and the individual atoms of the reactant molecule, during the course of the collision event. The charge distribution of acetyl chloride decreases the number of such interactions, thereby reducing the amount of energy transferred per collision.
    Zusätzliches Material: 3 Ill.
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  • 140
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 487-487 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 141
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 142
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 489-501 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A steady-state system involving the photolysis of NO2 in an excess of I2 as a source of IO radicals has been used to study the reaction IO + DMS in 760 Torr N2 at 296 K. IO radicals were found to react rapidly with DMS, one molecule of DMSO being produced for each molecule of DMS consumed. Numerical analysis of the experimental results yielded a rate constant of (3.0 ± 1.5) × 10-11 cm3 s-1 for the reaction IO + DMS → DMSO + I.
    Zusätzliches Material: 3 Ill.
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  • 143
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 513-518 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rates of acidic hydrolysis of hexano-, octano-, and decanohydroxamic acids and of 4-bromophenylaceto- and phenylacetohydroxamic acids have been determined in aqueous perfluorooctanoic acid - a reactive counterion surfactant system. Typical micellar catalysis was observed for the hydrolyses of the n-alkyl hydroxamic acids but not for the arylacetohydroxamic acids. The Arrhenius activation energy for hydrolysis of octano-hydroxamic acid is smaller above the cmc of the surfactant than it is below the cmc.
    Zusätzliches Material: 3 Tab.
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  • 144
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 519-537 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the direct synthesis reaction (Si + 2CH3Cl → (CH3)2SiCl2) were measured on a Cu3Si alloy containing 1.2 atom % Zn. Reaction was carried out in a differential reactor (520-595 K, 1 atm) attached to an ultrahigh vacuum (UHV) system. Auger spectroscopy was used to characterize the surface before and after reaction. Zinc does not significantly change the overall rate of reaction, but it changes selectivity to dimethyldichlorosilane (the desired product), surface composition, activation energies, and induction times. The rate of silicon diffusion to the surface is not limiting in the presence of zinc. Zinc is found to be a promoter for improved selectivity only in low concentrations, and only a fraction of the surface appears to be active for reaction. The kinetics appear relatively insensitive to the surface composition or the form of surface carbon. A Cu3Si surface with Zn is shown to be a good model catalyst for the direct synthesis reaction.
    Zusätzliches Material: 7 Ill.
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  • 145
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 553-570 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We examine the kinetic model D. The differential equations describing this reaction scheme are cast in a nondimensional form and analyzed in four basic approximation regimes: a ‘pseudo-first order’ approximation valid for small values of the ratio of the initial concentrations of the reactants; an asymptotic solution valid for large values of k3; the standard steady state (Bodenstein) approximation; and an approximation to a second order system without intermediate. Interconnecting relationships between the various approximations derived are examined, and the approximations are compared to numerical solutions to the full equations. The results are assessed from the standpoint of the experimental kineticist, and it is suggested that the reaction studied, and consequently many other more complex reactions, may under certain circumstances be subject to non-unique interpretation.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 146
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 609-614 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rates of decay of ozone in a large excess of the cycloalkene have been re-measured by an improved experimental procedure, and the following second-order rate constants (cm3 molecule-1 s-1) have been determined in synthetic air at atmospheric pressure: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm O}_3 + {\rm cyclopentene} \longrightarrow {\rm products,}} & {k = (4.97 \pm 0.30) \times 10^{ - 16} {\rm at}} \\ \end{array}291.5{\rm K} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm O}_3 + {\rm cyclohexene} \longrightarrow {\rm products,}} & {k = (1.51 \pm 0.10) \times 10^{ - 16} {\rm at}} \\ \end{array}295{\rm K} $$\end{document} The results are discussed in relation to existing literature data on the kinetics of ozonecycloalkene reactions.
    Zusätzliches Material: 2 Ill.
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  • 147
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 539-551 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surface reaction of NO2 and H2O vapor to emit HONO into the gas phase was studied in the evacuable and bakeable photochemical chamber under the irradiation of UV-visible light (≳ 290 nm). Kinetic analysis of the NO, NO2, and HONO with the aid of computer modeling strongly suggested that the formation of HONO by the surface reaction is photoenhanced. When a linear regression was assumed, the photoenhancement factor defined by {(k′21/k21) - 1} was expressed as (6.8 ± 2.5)k1 under our experimental conditions, where k1 is the primary photolysis rate of NO2, and k21, k′21 are the second-order-equivalent rate constants of the HONO formation reaction in dark and under irradiation, respectively. The discussion was made that this photocatalitic enhancement of HONO formation would explain the nature of the extra OH radical flux in the smog chamber experiments, which has been discussed as “unknown radical source” and has still been unexplained by the surface dark reaction of NO2 and H2O to emit HONO.
    Zusätzliches Material: 3 Ill.
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  • 148
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 149
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The following gas-phase reactions: were studied by the competitive method with CF3I as the source of radicals. The kinetic parameters obtained in the temperature range 533-613 K and 503-613 K respectively for chlorine atom transfer reactions are given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_1 /k_c ^{1/2} ({\rm cm}^{\rm 3}\, {\rm mol}^{{\rm - 1/2}} s^{ - 1/2}) = (6.19 \pm 0.10) - (16900 \pm 100)/\theta $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_2 /k_c ^{1/2} ({\rm cm}^{\rm 3}\, {\rm mol}^{{\rm - 1/2}} s^{ - 1/2}) = (6.52 \pm 0.10) - (14890 \pm 100)/\theta $$\end{document} where θ = 2.303 RT (cal mol-1).The Arrhenius A values were calculated for seven chlorine atom transfer reactions (CF2Cl2, CFCl3, CCl4 with CF3 radicals; CF3Cl, CF2Cl2, CFCl3 and CCl4 with CH3 radicals) by using the thermochemical kinetic version of the Transition State Theory (TST).
    Zusätzliches Material: 2 Ill.
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  • 150
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 649-658 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Published data show that in its early stages (up to 3% decomposition), the pyrolysis of n-hexane in the ranges 723-823 K and 10-100 Torr is not inhibited by the olefin products, in contrast with neopentane pyrolysis which is very strongly inhibited in similar conditions. Detailed consideration of the chain mechanisms for the two pyrolyses shows that the reactivity of the chain terminating radical towards hydrogen abstraction from an allylic C—H bond in product olefin is the factor which determines whether or not observable self-inhibition occurs. Thus, n-hexane pyrolysis, whose chain decomposition is terminated by recombination and disproportionation of ethyl, is not significantly self-inhibited, whereas that of neopentane which is terminated by recombination of methyl is very strongly inhibited because methyl is 14× more reactive than ethyl. The implications for other alkanes are briefly discussed.
    Zusätzliches Material: 1 Ill.
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  • 151
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 683-690 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase elimination of 4-(methylthio)-1-butyl acetate and 1-chloro-4-(methylthio)-butane has been investigated in a seasoned, static reaction vessel over the temperature range of 310-410°C and the pressure range of 46-193 Torr. The presence of the inhibitors propene, cyclohexene, and/or toluene had no effect on the rates. The reactions are homogeneous, unimolecular, and obey a first-order rate law. The rate coefficients are given by the following Arrhenius equations: for 4-(methylthio)-1-butyl acetate, log k1(s-1) = (12.32 ± 0.29) - (192.1 ± 3.6) kJ/mol/2.303RT; for 1-chloro-4-(methylthio)-butane, log k1(s-1) = (12.23 ± 0.59) - (175.7 ± 6.8) kJ/mol/2.303RT. The CH3S substituent in 1-chloro-4-(methylthio)-butane has been found to participate in the elimination reaction, where tetrahydrothiophene and methyl chloride formation may result from an intimate ion-pair type of mechanism. The yield of a cyclic product in gas phase reactions provides additional evidence of an intimate ion pair mechanism through neighboring group participation in gas phase elimination of special types of organic halides.
    Zusätzliches Material: 5 Tab.
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  • 152
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 741-755 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the permanganate oxidation of formic acid in aqueous perchloric acid at 30°C were examined by the spectrophotometric method. The chemical reaction 2MnO4- + 3HCOOH + 2H+ → 2MnO2 + 3CO2 + 4H2O, appears to proceed via several parallel reactions. The overall rate equation has been obtained by using statistical multilinear regression analysis of the 660 cases studied, and the presence in the rate equation of two new terms in relation to previous studies shows that both permanganate autocatalytic effects and acid media inhibition must be taken into account when the reaction proceeds at constant ionic strength.
    Zusätzliches Material: 6 Ill.
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  • 153
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 777-780 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 799-828 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A previous technique for the calculation of rate constants for the gas-phase reactions of the OH radical with organic compounds has been updated and extended to include sulfur- and nitrogen-containing compounds. The overall OH radical reaction rate constants are separated into individual processes involving (a) H-atom abstraction from C—H and O—H bonds in saturated organics, (b) OH radical addition to 〉C=C〈 and —C≡C— unsaturated bonds, (c) OH radical addition to aromatic rings, and (d) OH radical interaction with —NH2, 〉NH, 〉N—, —SH, and —S— groups. During its development, this estimation technique has been tested against the available database, and only for 18 out of a total of ca. 300 organic compounds do the calculated and experimental room temperature rate constants disagree by more than a factor of 2. This suggests that this technique has utility in estimating OH radical reaction rate constants at room temperature and atmospheric pressure of air, and hence atmospheric lifetimes due to OH radical reaction, for organic compounds for which experimental data are not available. In addition, OH radical reaction rate constants can be estimated over the temperature range ca. 250-1000 K for those organic compounds which react via H-atom abstraction from C—H and O—H bonds, and over the temperature range ca. 250-500 K for compounds containing 〉C=C〈 bond systems.
    Zusätzliches Material: 6 Ill.
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  • 155
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 156
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 929-942 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constant of the primary decomposition step was determined for four symmetrical and four unsymmetrical azoalkanes. From the experimental activation energies and some literature enthalpy data, the following enthalpies of formation of radicals and group contributions were calculated: ΔHƒ (CH3N2) = 51.5 ± 1.8 kcal mol-1, ΔHƒ (C2H5N2) = 44.8 ± 2.5 kcal mol-1, ΔHƒ (2-C3H7N2) = 37.9 ± 2.2 kcal mol-1, [NA-(C)] = 27.6 ± 3.7 kcal mol-1, [NA-(ṄA) (C)] = 61.2 ± 3.1 kcal mol-1.
    Zusätzliches Material: 2 Ill.
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  • 157
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 158
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 963-973 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new determination of the disproportionation/combination ratio for C2F5 and C2H5 radicals gives a value of Δ(C2F5, C2H5) = 0.24 ± 0.02, independent of temperature. The cross-combination ratio for the two radicals was found to increase with temperature and the significance of this is discussed in evaluating Δ.
    Zusätzliches Material: 1 Ill.
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  • 159
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 1015-1023 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute rate constants were determined for the gas phase reactions of OH radicals with a series of aliphatic alcohols using the flash photolysis resonance fluorescence technique. Experiments were performed over the temperature range 240-440 K at total pressures (using Ar diluent gas) between 25-50 Torr. The kinetic data for methanol (k1), ethanol (k2), and 2-propanol (k3) were used to derive the Arrhenius expressions \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = (4.8 \pm 1.2) \times 10^{ - 12} \exp [- (480 \pm 70)/T]\,{\rm cm}^3\, {\rm molecule}^{ - 1} {\rm s}^{ - 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_2 = (7.4 \pm 3.2) \times 10^{ - 12} \exp [- (240 \pm 110)/T]{\rm cm}^3 {\rm molecule}^{ - 1} {\rm s}^{ - 1} $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ k_3 = (5.8 \pm 1.9) \times 10^{ - 12} \exp [- (30 \pm 90)/T]\,{\rm cm}^3\, {\rm molecule}^{ - 1} {\rm s}^{ - 1} $$\end{document} At 296 K, the measured rate constants (in units of 10-13 cm3 molecule-1 s-1) were: k1 = (8.61 ± 0.47), k2 = (33.3 ± 2.3), and k3 = (58.1 ± 3.4). Room temperature rate constants for the OH reactions with several other aliphatic alcohols were also measured. These were (in the above units): 1-propanol, (53.4 ± 2.9); 1-butanol, (83.1 ± 6.3) and 1-pentanol, (108 ± 11). The results are discussed in terms of the mechanisms for these reactions and are compared to previous literature data.
    Zusätzliches Material: 2 Ill.
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  • 160
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 1025-1047 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mechanism of ligand substitution in 17- and 19-electron organometallic radicals is discussed. These species substitute ligands by an associative process some 106 to 1010 faster than analogous 18-electron complexes. When 17-electron species can be generated by bond homolysis or electron transfer reactions of 18-electron complexes, they can act as intermediates in radical chain reactions of 18-electron complexes. A 17-19 electron rule is proposed to explain transformations of organometallic radicals just as the 16-18 electron rule finds use for closed shell organometallic complexes. The origin of this rule is the favorable two-center three-electron bond that can form when an odd electron in a sterically accessible metal d-orbital interacts with an electron pair on an entering nucleophile. Besides simple substitution, these radicals can disproportionate, dimerize, and undergo insertion or atom abstraction reactions.
    Zusätzliches Material: 6 Ill.
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  • 161
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 171-181 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A detailed statistical study is presented, based on simulated experimental data, on the estimation of activation parameters using the Arrhenius equation: k = A exp(B/T). The close correlation of the two parameters is shown, which requires the computation of the covariance matrix for the representation of uncertainties. This matrix facilitates the correct estimation of the confidence interval for interpolated (or extrapolated) values of rate coefficients. It is proposed that the full correlation matrix should be published in any article dealing with the determination of Arrhenius parameters.The importance of correct weighting is emphasized. Nonlinear fitting to the Arrhenius equation can be carried out without weighting only in case the (absolute) error of rate coefficient is independent of the temperature. Simulated experiments show that noncorrect weighting shifts the average values of fitted parameters and increases the variance of the parameters as well.With respect to the modified Arrhenius equation: k = A · Tn exp(B/T), statistical analysis shows that the physically meaningful estimation of all three parameters is impossible. Nonlinear fitting of three parameters is suggested for interpolation (and extrapolation) of rate coefficients, whereas in case of activation parameter estimation, the fixing of “n” on the basis of theoretical considerations is advised followed by the estimation of the remaining two parameters.
    Zusätzliches Material: 3 Ill.
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  • 162
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 183-189 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolysis of 4-chloro-1-butanol has been studied in a static system, seasoned with allyl bromide, and in the presence of the free radical suppressor toluene. The working temperature and pressure ranges were 400-450°C and 43-164 Torr, respectively. The reaction is homogeneous, unimolecular, and follows a first-order rate law. The temperature dependence of the rate coefficients is given by the following Arrhenius equation: log k1(s-1) = (13.34 ± 0.50) - (221.1 ± 6.7) kJ mol-1 (2.303RT)-1. The products tetrahydrofuran, formaldehyde, and propene, arise by the participation of the neighboring OH group in 4-chloro-1-butanol pyrolysis. The reaction is best explained in terms of an intimate ion pair type of mechanism.
    Zusätzliches Material: 2 Ill.
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  • 163
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 191-205 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase reaction of N2O5 with water vapor was investigated in a 17.3-m3 Teflon lined chamber. Temporal concentration profiles for ozone, total nitrogen oxides, and nitrogen dioxide were measured. Concentration profiles for N2O5 and HNO3 were calculated from a combination of measurements of nitrogenous species. A kinetic mechanism with an adjustable value for the rate constant of N2O5 + H2O was used to model the experiments. From this analysis an upper limit value of k ≤ 4 × 10-7 ppm-1 min-1 for the gas phase reaction N2O5 + H2O → 2HNO3 was derived.
    Zusätzliches Material: 3 Ill.
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  • 164
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 207-228 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions which proceed through energized adducts, including radical recombinations, insertions, and addition to unsaturates, frequently exhibit unusual kinetic behavior. The branching ratios among various product channels are often complex functions of both temperature and pressure. Four such reactions involving methyl radicals are analyzed by combining chemical activation distribution functions with QRRK methods to predict rate constants for each channel. These include three oxidation paths, CH3 + O, CH3 + O2, CH3 + OH, and the addition reaction CH3 + C2H2. These predictions are compared to experiments wherever possible; generally, the agreement is quite satisfactory. Analysis of the energetics of the various reaction channels, using parameters which are readily available, provides a convenient framework for prediction. Suggested rate constants for the various channels for the four reactions are given at three pressures, 20, 760, and 7600 Torr, for the temperature range 300-2500 K. The approach used here can easily be applied to other reactions.
    Zusätzliches Material: 10 Ill.
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  • 165
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 229-242 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The direct photolysis of bicyclo[4.2.0]octa-2,4-diene in the gas phase at 280-300 nm produces mainly 1,3,5-cyclooctatriene and benzene plus ethylene. The yield of the former product is enhanced by added gases, and it is proposed that it is formed in a vibrationally excited state which can revert to bicyclooctadiene unless the excess energy is removed in collisions. Computer modelling of the direct photolysis yielded quantitative agreement with the experimental results, but only when large, arbitrary adjustments were made to the calculated rate constants for the interconversion of cyclooctratriene and bicyclooctadiene. The Hg(63P1) sensitized reaction of bicyclooctadiene produces mainly benzene plus ethylene, a process which is also enhanced by added gases.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 166
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 251-259 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute rate coefficients for the reactions of the hydroxyl radical with dimethyl ether (k1) and diethyl ether (k2) were measured over the temperature range 295-442 K. The rate coefficient data, in the units cm3 molecule-1 s-1, were fitted to the Arrhenius equations k1 (T) = (1.04 ± 0.10) × 10-11 exp[-(739 ± 67 cal mol-1)/RT] and k2(T) = (9.13 ± 0.35) × 10-12 exp[+(228 ± 27 kcal mol-1)/RT], respectively, in which the stated error limits are 2σ values. Our results are compared with those of previous studies of hydrogen-atom abstraction from saturated hydrocarbons by OH. Correlations between measured reaction-rate coefficients and C—H bond-dissociation energies are discussed.
    Zusätzliches Material: 4 Ill.
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  • 167
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 261-268 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple collision theory model for reaction between two different radicals shows that the cross-reaction ratio, φ*, is 2 only if the masses and collision diameters of the radicals are identical; for all other combinations of mass and size, φ* is greater than 2. The value of φ* is shown to depend simply on the ratios of the masses and diameters of the two radicals: which of the two is the heavier or larger is unimportant.Calculated and experimental values of φ* are compared for several systems involving small alkyl and fluoroalkyl radicals, and the relationship between φ* and φ, the cross-combination ratio, is discussed.
    Zusätzliches Material: 2 Tab.
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  • 168
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 243-249 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas-phase reaction of the NO3 radical with NO2 was investigated, using a flash photolysis-visible absorption technique, over the total pressure range 25-400 Torr of nitrogen or oxygen diluent at 298 ± 2 K. The absolute rate constants determined (in units of 10-13 cm3 molecule-1 s-1) at 25, 100, and 400 Torr total pressure were, respectively, (4.0 ± 0.5), (7.0 ± 0.7), and (10 ± 2) for M = N2 and (4.5 ± 0.5), (8.0 ± 0.4), and (8.8 ± 2.0) for M = O2. These data show that the third-body efficiencies of N2 and O2 are identical, within the error limits, and that previous evaluations for M = N2 are applicable to the atmosphere. In addition, upper limits were determined for the rate constants of the reactions of the NO3 radical with methanol, ethanol, and propan-2-ol of ≤6 × 10-16, ≤9 × 10-16, and ≤2.3 × 10-15 cm3 molecule-1 s-1, respectively, at 298 ± 2 K.
    Zusätzliches Material: 2 Ill.
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  • 169
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 170
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 269-276 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Using a laser pyrolysis/laser fluorescence method, we have measured the rate constants for OH reacting with 1-butene, t-2-butene, isobutene, and 2,3-dimethyl-2-butene near 1200 K. The butene rate constants are large, ranging from 2.0-3.7 × 10-11 cm-3 s-1, and increase with the number of allylic hydrogens. Transition-state theory considerations indicate these allylic hydrogens are easily abstracted, in contrast to prior observations on propene.
    Zusätzliches Material: 2 Ill.
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  • 171
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 363-371 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the Diels-Alder additions of CH2 = CHCN, CH2 = C(CH3) CN, and cis- and trans-CH3CH = CHCN to cyclohexa-1, 3-diene have been studied in the gas phase. The stereochemistry of these reactions is discussed. In terms of a biradical mechanism, a minimum value of 4.1 ± 0.8 kcal mol-1 for the stabilizing effect of a CN group vis-à-vis a methyl group is shown to fit the experimental activation energies.
    Zusätzliches Material: 3 Ill.
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  • 172
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 435-455 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new approach is presented for analyzing kinetic models of relaxation-type oscillatory systems on the basis of numerical data. Feature sensitivities of the length of the two kinetic states of the Belousov-Zhabotinsky (BZ) reaction with respect to the rate constants of the model are explained by means of a logic-based inference system. The main kinetic roles of the individual reaction steps on the relaxing components are revealed, and a consistent interpretation of the kinetic states is given by this process. Both the high and the low set of rate constants were studied. According to our analysis, the bromous acid-hypobromous acid reaction is an important Br- producing step of the model, and in the case of the low set, the bromate-bromous acid reaction is not the rate-determining step of the bromous acid autocatalysis.
    Zusätzliches Material: 8 Ill.
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  • 173
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 583-608 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A general method has been developed for the determination of the differential energy distribution in nonthermally activated reacting systems. A series of known distributions and kinetic models has been used to test this method and to determine its efficacy. Application was then made to the kinetic data of energetic CH3CF2 18F formed by the substitution of F by 18F produced by nuclear recoil. The distribution obtained for this activated CH3CF2 18F is seen to be highly energetic with a median energy of 137.6 kcal mol-1 and with 33.1% of the molecules possessing energy in excess of 171 kcal mol-1. The shape of the calculated distribution suggests that there are two mechanisms for the formation of CH3CF2 18F from CH3CF3 and 18F, as well as that 62 kcal mol-1 is a lower limit to the kinetic energy needed by the 18F atom for this substitution to take place.
    Zusätzliches Material: 7 Ill.
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  • 174
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 175
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 691-708 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new, improved variant of the very low pressure reactor (VLPR) system with interchangeable discharge orifices was used for studying the compatibility of the chemical and physical processes occurring simultaneously. It is shown that the ratio of calculated and effective escape rate constants is a complex function of the reactor cell geometry for reactions of non-spherical symmetry.The test reaction of atomic chlorine with methane proved to be a pure chemical process free of side reactions and was used to calibrate the system. The measured rate constant is k1 = (0.993 ± 0.013) × 10-13 cm3/molec-s at 25°C. A new procedure is outlined for measuring the equilibrium constant by changing the concentrations of all three components resulting in a remarkable accuracy of K1 = 1.406 ± 0.034 for the test reaction at 25°C.
    Zusätzliches Material: 8 Ill.
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  • 176
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 725-739 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute rate constants for the gas phase reactions of OH radicals with ethane (k1), benzene (k2), fluorobenzene (k3), chlorobenzene (k4), bromobenzene (k5), iodobenzene (k6), and hexafluorobenzene (k7) have been measured over the temperature range 234-438 K using the flash photolysis resonance fluorescence technique. The rate constants measured at room temperature (296 K), at total pressures of argon diluent between 25 and 50 Torr, were (in units of 10-13 cm3 molecule-1 s-1): k1 = (2.30 ± 0.26), k2 = (12.9 ± 1.4), k3 = (6.31 ± 0.81), k4 = (7.41 ± 0.94), k5 = (9.15 ± 0.97), k6 = (13.2 ± 1.6), and k7 = (1.61 ± 0.24), respectively. The indicated errors are our estimate of 95% confidence limits and include two standard deviations from the least-squares analysis together with an allowance for any possible systematic errors in the measurements. At elevated temperatures and under pseudo-first-order reaction conditions, non-exponential hydroxyl radical decays were observed for benzene and the monosubstituted halo-aromatics. For ethane and hexafluorobenzene, exponential decays were observed over the complete temperature range and the data were fit by the Arrhenius expressions: k1 = (8.4 ± 3.1) × 10-12 exp[(-1050 ± 100)/T] and k7 = (1.3 ± 0.3) × 10-12 exp[(-610 ± 80)/T], respectively. The results are compared with previous literature data and the mechanistic implications are discussed.
    Zusätzliches Material: 9 Ill.
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  • 177
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 757-776 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The first-order rate constants, k1, obtained for methanolysis and ethanolysis of phenyl salicylate (PSH) in aqueous mixed solvents, fit to a relationship: k1 = A1 · [ROH]T/(1 + A2[ROH]T) where A1 and A2 are the unknown parameters and [ROH]T is the total concentration of alkanol. It is proposed that the alkanolysis of PSH involves the preequilibrium formation of monomeric ROH from polymeric (ROH)n, followed by an intramolecular general base-catalysed nucleophilic attack by monomeric ROH on the carbonyl carbon of the ester. In the mixed solvents containing alkanol and MeCN, the k1 - [ROH]T profiles obtained in the presence of K+ ions are different from those obtained in the presence of Na+ ions which could be attributed to the cation-induced changes in the alkanol structure. Negative KCl salt effect has been observed on methanolysis of PSH, while it is essentially unaffected by the presence of tetraalkylammonium iodide salts (R4NI). The rates of ethanolysis of PSH have been found to increase with increase in [R4NI] and this increase becomes more pronounced with increasing hydrophobic surface area of R4NI. The rate constants for methanolysis of PSH in aqueous mixed solvents containing 80% MeOH (v/v) are independent of [ŌH] within the [ŌH] range of 0.01 to 0.15 M. The rate of methanolysis could not be detected within ca. 47 h in mixed solvents containing 96% HeOH (3.8% MeCN and 0.2% H2O), 80% MeOH (19.8% MeCN and 0.2% H2O), and 0.022 M HCl. It is concluded that for efficient transesterification, PSH should exist in ionized form. The reaction of PSH with MeOH is ca. 400 times faster than that with t-BuOH which could be ascribed to the most likely steric effect. The values of ΔH* and ΔS* obtained for methanolysis and ethanolysis are essentially independent of [ROH] within the ROH content of 20% to 96% for MeOH and 50% to 96% for EtOH. The effect of organic co-solvent on rate of hydrolysis of PSH could be explained in terms of organic co-solvent-induced water polarization.
    Zusätzliches Material: 5 Ill.
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  • 178
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 789-797 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ethyl 4-chlorobutyrate, which is reexamined, pyrolyzes at 350-410°C to ethylene, butyrolactone, and HCl. Under the reaction conditions, the primary product 4-chlorobutyric acid is responsible for the formation of γ-butyrolactone and HCl. In seasoned vessels, and in the presence of a free-radical inhibitor, the ester elimination is homogeneous, unimolecular, and follows a first-order rate law. For initial pressures from 69-147 Torr, the rate is given by the following Arrhenius expression: log k1(s-1) = (12.21 ± 0.26) - (197.6 ± 3.3) kJ mol-1 (2.303RT)-1. The rates and product formation differ from the previous work on the chloroester pyrolysis.4-Chlorobutyric acid, an intermediate product of the above substrate, was also pyrolyzed at 279-330°C with initial pressure within the range of 78-187 Torr. This reaction, which yields γ-butyrolactone and HCl, is also homogeneous, unimolecular, and obeys a first-order rate law. The rate coefficient, is given by the following Arrhenius equation: log k1(s-1) = (12.28 ± 0.41) - (172.0 ± 4.6) kJ mol-1 (2.303RT)-1. The pyrolysis of ethyl chlorobutyrate proceeds by the normal mechanism of ester elimination. However, the intermediate 4-chlorobutyric acid was found to yield butyrolactone through anchimeric assistance of the COOH group and by an intimate ion pair-type of mechanism. Additional evidence of cyclic product and neighboring group participation is described and presented.
    Zusätzliches Material: 3 Ill.
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  • 179
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 869-879 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A one-parameter analytical potential energy function for β-bonds in free radicals is described, which accounts quantitatively for their observed stretching frequencies and the position and size of the activation barriers for their fission. It is shown that such a function can be used to characterize a priori the corresponding transition states by assuming that the structural and spectroscopic changes taking place along the minimum energy path track the development of pi bonding rather than following a simple exponential dependence on the reaction coordinate. This procedure, tested by comparing predicted A-factors and isotope effects with experimental data for alkyl radicals and ab-initio calculations on C2H5, fully encodes the basic features of radical decomposition reactions and provides a simple, realistic, and self-consistent technique for the estimation of their kinetic parameters.
    Zusätzliches Material: 2 Ill.
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  • 180
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 885-894 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal reactions of endo- and exo-5-cyanobicyclo-[2.2.2]oct-2-ene and their trans- and cis-6-methyl-substituted derivatives have been investigated in the gas phase between 518 and 630 K. Each product decomposes by two parallel first-order retro-Diels-Alder reactions, a main one with formation of cyclohexa-1,3-diene and a minor one with elimination of ethene. Slight isomerizations are also observed. The kinetic results can be explained in terms of a biradical mechanism. The rate-determining step is shown to depend on the amount of resonance energy in the biradical. Heats of formation and entropies of the bicyclo[2.2.2]oct-2-enes studied are estimated.
    Zusätzliches Material: 1 Ill.
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  • 181
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 923-927 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The standard deviations (σ) of the parameters of a single exponential function can vary strongly with the range of the data, the character of the underlying error structure and also with the inclusion or omission of the appropriate relative weights. These effects are studied quantitatively, for least squares analysis of uniformly spaced, ln-linearized simulated data. The parameters, k and A, extracted are less precise when weighting is omitted, increasingly so as the range of the data increases, particularly for the case of equal amplitude errors for each A exp(-kti) datum. The results, expressed as efficiencies (σ2[using weights]/σ2[omitting weights]), show 〈 1% efficiency in some cases. This is tantamount to ignoring 〉 99% of the data and treating the remainder with proper relative weighting.
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  • 182
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 943-957 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Benzylic H-atom abstraction rates by diphenylmethyl radicals from a series of donors were determined in nonpolar liquids at elevated temperatures. Relative rates were converted to absolute rates via available equilibrium constant data for the dimerization of diphenylmethyl radicals. Abstraction by diphenylmethyl from 1, 2, 3, 4-tetrahydronaphthalene (tetralin) was studied over the temperature range 489-573 K. Its Arrhenius expression is 109.9±0.3 exp{-(10183 ± 373)/T} M-1 s-1. Abstraction from other donors was studied at 548 K. Rate constant values ranged from a low of 3.6 M-1 s-1 for toluene to a high of 3000 M-1 s-1 for 9, 10-dihydroanthracene. Similar reactions with the fluorenyl radical were also studied. In this case, relative rates were converted to absolute rates with an equilibrium constant for fluorenyl dimerization determined from the observed homolysis rate of the dimer and an assumed recombination rate. In addition, forward and reverse rate measurements yielded the equilibrium constant for hydrogen transfer between fluorenyl and diphenylmethyl. At 548 K, fluorenyl is favored by a factor of 13 over diphenylmethyl.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
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  • 183
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 961-961 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 184
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 337-345 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The conversion of lactose  -  the main constituent of whey  -  to methane and carbon dioxide was studied using different defined constructed cultures, imploying strains of Methanosarcina barkeri, Methanobacterium bryantii, Escherichia coli, Acetobacterium woodii, Lactobacillus casei, and Lactobacillus plantarum. The following combinations of strains (food chains) were studied with respect to efficiency and yield of lactose conversion (methane yield in parentheses): E. coli and M. barkeri (4.5-7.6%), E. coli and M. bryantii (13.3%),E. coli, M. barkeri and M. bryantii (54%), L. casei, A. woodii and M. barkeri (93.3%). These conversions were carried out in pH controlled batch fermentations. A very efficient coculture was a combination of L. plantarum with A. woodii and M. barkeri: in chemostat cultures lactose was converted to methane and carbon dioxide with a yield of about 90%, at dilution rates of 0.27 d-1to 0.37 d-1.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 185
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 327-330 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Growth kinetics of Aspergillus niger strain A.n./61 on a solid medium containing beet pulp were examined.Solid state fermentation was carried out in laboratory microfermenter (aerated packed columns). During the experiments the CO2 evolution, protein biosynthesis, as well as cellulose and sucrose utilization were determined.It was found that CO2 evolution evidently increased in the logarithmic phase, together with the protein biosynthesis. Between 30-32 h of culture CO2 evolution and protein content in product were the greatest. Subsequently, CO2 evolution decreased.During 28 h of culture, cellulose was slightly utilized, the strain using mainly sucrose. Intense utilization of cellulose was paralleled by a drop in CO2 evolution.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 186
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 353-356 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A rhamnolipid released by Pseudomonas aeruginosa 196 Aa into the culture medium reduced the number of local lesions induced by tobacco mosaic virus on leaves of the hypersensitive host Nicotiana glutinosa L. by up to 90%. The content of potato virus X in the systemically infected host Nicotiana tabacum L. ‘Samsun’ is decreased in inoculated as well as in secondarily infected leaves by up to 50%. In a smaller degree red clover mottle virus is influenced in the systemic host Pisum sativumconvar.speciosum (Dierb.) Alef ‘Nadja’.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 187
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 377-385 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A specific enzyme electrode with L-Lysine decarboxylase (E.C. 4.1.1.18) from Klebsiella pneumoniae and a CO2-sensor are described. The electrode can be used for assay of L-Lysine in amino acid mixtures as protein hydrolysates or culture filtrates from fermentation processes. The accuracy and reproducibility are those of an amino acid analyzer. The electrode works well for several weeks.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 188
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 357-359 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The present investigation sought the use of Bovine Kidney Cells (BKC) which is a readily available substrate for the cultivation and isolation of measles virus. Results showed that measles virus grew well on BKC, showing identical cytopathologic effect (CPE) of syncytial and giant cell formation also noted for Vero cells. However, the growth on Vero cells was faster indicating a better sensitivity to the measles virus than BKC. The virus replicated and produced CPE in both confluent monolayer and trypsin dispersed cultures. The ability of the virus to form CPE was faster in trypsin-dispersed cells than confluent monolayers.The viral yield in Vero- and BK-cells were compared to assess any difference by analysis of variance. The F-value of 0.824 with degree of freedom 1.34 showed no significant difference at any reasonable confidence interval.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 189
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987) 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 190
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 48-48 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 191
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 416-416 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 192
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 61-69 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A continuous flow system with an enzyme electrode and with a new type of measuring instrument, the BIOXY-Meter, is described as an example for the determination of glucose. The BIOXY-Meter combined with various biosensors may be used in biotechnology and in other fields for the solution of a number of analytical problems. Measuring principle is the reduction of oxygen. The peak of first derivation of the current-time-curve is proportional to oxygen consumption and to decrease of substrate concentration. Enzyme fixation with common adhesive and a device for automated saturation of measuring samples with air in the sampler are also described. With the apparatus 60 samples per hour are analyzed for glucose. The linear measuring range is 0.1 mMol to 1.5 mMol with a coefficient of variation of Vk = 0.93 per cent. The described type of enzyme electrode is stable for 2 to 12 weeks or 1,000 to 5,000 measurements.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 193
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 499-505 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The authors studied the influence of the pancreatic desoxyribonucleasa enzyme preparation on the growth of microorganisms and the biosynthesis of some essential amino acids.Kinetic data of amino acid biosynthesis with stimulator and without it are presented. The splain-approximation method for the estimation of the principal physiological characteristics of the fermentation process is used.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 194
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 195
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 528-528 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 196
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The wild strain Aspergillus niger VKMF-2092 forms β-glucosidase on the basis of glucose as the sole carbon source. The formation of β-glucosidase is initiated after the glucose concentration in the medium has reached a low level since the formation is subjected to catabolite repression. The β-glucosidase is mainly cell-bound and only released after a longer period. Under non-repressed conditions the total formation of β-glucosidase is not associated with growth.By supplying glucose in a fed-batch-technique, maintaining a low actual glucose concentration in the medium, the formation of β-glucosidase is enhanced in comparison to simple batch fermentation. Using a fed-batch-technique with a frequently intermittent addition of glucose it is possible to increase the formation of β-glucosidase with regard to both productivity and the activity related to the mycelium and the fermentation broth as well. The increase of productivity is about two to four times greater than at constant feed rate of the same overall amount of glucose.The reason for this increase will be discussed below. A method is presented which permits to investigate the influence of the substrate concentration and other parameters on the enzyme formation in short periods of one and the same fermentation run.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 197
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 127-134 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: An attempt is made to give a thermodynamic interpretation of the complete temperature profile curve of ethanol formation. Taking into consideration an enhancing competition between thermal activation and thermal deactivation of ethanol formation at increasing temperatures and supposing that the ethanol production is affected by a reversible and an irreversible term of thermal deactivation of a modified ARRHENIUS equation being current for the total biokinetic sphere may be derived: \documentclass{article}\pagestyle{empty}\begin{document}$$\ln {\rm (}v_2 /v_1 ) = - \frac{1}{R}(\Delta H_{{\rm EtoH}}^A - \Delta H_T^{D_1 } - \Delta H_T^{D_2 } )\left( {\frac{1}{{T_2 }} - \frac{1}{{T_1 }}} \right) \cdot $$\end{document}.The quantities ΔHTD1 and ΔHD2T are identical with the temperature functions of the change of entropy caused by reversible and irreversible deactivation of ethanol formation, respectively. Accordingly for the yeast strain Saccharomyces cerevisiae Sc 5 the calculated entropy coefficients of reversible and irreversible thermal deactivation of ethanol formation amount to CSTD1 = (0.245± 0.013) kJ/mol · deg.2 and CSTD2 = (1.657 ± 0.046) kJ/mol · deg.2.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 198
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 147-155 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Employing anionic and non-ionic cellulose ethers, differing in type of substituent and degree of substitution, as substrates, the pH-profile of enzyme activity and the parameter Km and Vmax of the MICHAELIS-MENTEN kinetics have been determined with Penicillium citrioviride cellulase in an homogeneous system. Within rather wide limits, a linear correlation was found between the DS of the substrate and Km or Vmax, respectively. Also the pH-profile was found to depend on DS mainly, being bimodal at higher DS. On the other hand, no significant difference was observed between anionic and non-ionic cellulose ethers of about the same DS with regard to the parameters determined. It is assumed, that substrate-enzyme interaction is governed mainly by the length of non-derivatized chain sequences mainly and not by Coulomb interactions.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 199
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 146-146 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 200
    Digitale Medien
    Digitale Medien
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 7 (1987), S. 173-177 
    ISSN: 0138-4988
    Schlagwort(e): Life Sciences ; Life Sciences (general)
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A framework for modelling microbial growth is given in which the biological properties of the regulation of cell growth and proliferation are taken as a basis. Some stages on the way of formulating state-structure models are discussed. The resulting delay-differential equations are both comprehensible and suitable for a mathematical treatment.
    Materialart: Digitale Medien
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