| | 6 | Author
| M. Rauh, H.-U Finzel, P. Wißmann | Requires cookie* | | | Title
| The Oxidation Kinetics of Thin Copper Films Studied by Resistivity Measurements  | | | | Abstract
| Resistivity measurements on thin metal films allow to study the kinetics of oxidation. The method is applied to 50 -60 nm thick copper films deposited on glass substrates under UHV conditions. After annealing at 150 °C, the films are exposed to pure oxygen at various temperatures in the range 85 -135 °C, and the electrical resistivity is recorded in situ. At these temperatures, the oxygen begins to penetrate into the interior of the films, which results in a relatively steep increase in the film resistivity. A linear time law is valid to good approximation, which can be attributed to the influence of the dissociation of an adsorbed molecular species of oxygen on the reaction velocity. A potential diffusion of oxygen in the grain boundaries is also discussed. | | | |
Reference
| Z. Naturforsch. 54a, 117—123 (1999); received July 29 1998 | | | |
Published
| 1999 | | | |
Keywords
| Oxidation, Kinetics, Resistivity, Thin Metal Films | | | |
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| default:Reihe_A/54/ZNA-1999-54a-0117.pdf | | | | Identifier
| ZNA-1999-54a-0117 | | | | Volume
| 54 | |
| 8 | Author
| S. | Requires cookie* | | | Title
| Kinetics and Possible Mechanisms o f the Ce(IY) Oxidation of EDTA, CDTA, DTPA and NTA in Perchloric Acid Media | | | | Abstract
| a m ir B. H a n n a , W i l l i a m R . C a r r o l l , S a l e m A. A t t i g a , a n d W i l l i a m H . W e b b The rates of oxidation of four chelating agents with Ce(IV) in HC104 solutions, have been studied by the stopped-flow technique. The rates first increase with increasing acidity, reach maxima which are characteristic of the chelating agent and the medium, then progressively decrease with further increasing acid concentration. A t their maximum reactivities, the tendencies for oxidation decrease in the following order: 2rans-l,2-dia-minocyclohexane tetraacetic acid (CDTA) > ethylenedinitrilotetraacetic acid (EDTA) > diethylenetriaminepentaacetic acid (DTPA) > nitrilotriacetic acid (NTA). A mech anism for the oxidation of EDTA, involving Ce4+ and Ce(OH)3+ and both unprotonated and monoprotonated chelating agent, is proposed. | | | |
Reference
| (Z. Naturforsch. 30b, 409—415 [1975]; received December 27 1974) | | | |
Published
| 1975 | | | |
Keywords
| Oxidation, Amino Acids, Kinetics, Mechanisms, Cerium(IY) | | | |
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| | | | | TEI-XML for
| default:Reihe_B/30/ZNB-1975-30b-0409.pdf | | | | Identifier
| ZNB-1975-30b-0409 | | | | Volume
| 30 | |
| 10 | Author
| CrI. Simionescu, S. Dumitriu, V. I. Popa | Requires cookie* | | | Title
| im kalten Plasma The Mechanism and Kinetics of Methane-Water Mixture Decomposition in Cold Plasma | | | | Abstract
| In the present paper the mechanism and kinetics of methane-water mixtures decompo-sition in cold plasma are discussed. It was found that nature and composition of the products depend on reaction time, ratio of the two components, and how long the products are in contact after the decomposition was performed. Reactions in the decomposition system generally follow two mechanisms: corresponding to the discharge phase and to postreaction one. The highest yield of formaldehyde was obtained for the ratio methane water of 0.6-1 and two minutes of discharge. Die Bildung von Formaldehyd aus den hypothe-tischen Bestandteilen der Uratmosphäre wurde von LÖB 1 noch im Jahre 1906 in den dmch elektrische Entladungen in einer Mischung von Kohlendioxyd und Wasser entstandenen Produkten nachgewiesen. Später erwähnt derselbe Verfasser die Erzeugung von Glycin über Formaldehyd in einem aus Kohlen-mon-oder -dioxyd, Ammoniak und Wasser beste-henden System. Die Verwendung anderer Systeme (CO + H2; | | | |
Reference
| (Z. Naturforsch. 31b, 466—471 [1976]; eingegangen am 5. November 1975) | | | |
Published
| 1976 | | | |
Keywords
| Methane-Water, Decomposition, Formaldehyde, Mechanism, Kinetics | | | |
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| default:Reihe_B/31/ZNB-1976-31b-0466.pdf | | | | Identifier
| ZNB-1976-31b-0466 | | | | Volume
| 31 | |
| 11 | Author
| Milan Strašák | Requires cookie* | | | Title
| Substituent Effects in the Oxythallation of Alkenes | | | | Abstract
| The rate constants for oxythallation of alkenes have been correlated with their experi-mental and calculated ionization potentials respectively. A good correlation between the rate constants and the ionization potentials of alkenes was found. It was found that inductive effects were the most important in the oxythallation of RCH —CH2 and RiR2C = CH2 alkenes. From earlier studies [1, 2] it is obvious that the rate determining step of the oxidation of alkenes by thallic salts is the formation of the intermediate oxythallation adduct according to Eq (1): R2C=CR2 + T13+ + H20 -> [CR2(0H)CR2T1]2+ + H+ (1) | | | |
Reference
| Z. Naturforsch. 33b, 224—227 (1978); received October 20 1977 | | | |
Published
| 1978 | | | |
Keywords
| Alkenes, Oxythallation, Kinetics, Inductive Effect, Ionization Potentials | | | |
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| default:Reihe_B/33/ZNB-1978-33b-0224.pdf | | | | Identifier
| ZNB-1978-33b-0224 | | | | Volume
| 33 | |
| 13 | Author
| I. Basic, KineticsHartmut Schmidt, Peter Rosenkranz | Requires cookie* | | | Title
| On the Mechanism of the Acridine Orange Sensitized Photodynamic Inactivation of Lysozyme | | | | Abstract
| The kinetics of the photodynamic desactivation of lysozyme in presence of acridine orange as the sensitizer have been investigated in detail varying oxygen, protein, dye concentration, ionic strength and pH value. The kinetics can be approximately described as an over all pseudo-first-order rate process. Changing the solvent from water to D20 or by quenching experiments in pres ence of azide ions it could be shown that the desactivation of lysozyme is caused exclusively by singlet oxygen. The excited oxygen occurs via the triplet state of the dye with a rate constant considerably lower than that to be expected for a diffusionally controlled reaction. Singlet oxygen reacts chemically (desactivation, k —2.9 x 107 M -1 sec-1) and physically (quenching process, k = 4.1 x 108 m — 1 sec-J) with the enzyme. The kinetical analysis shows that additional chemical reac tions between singlet oxygen and lysozyme would have only little influence on the kinetics of the desactivation as long as their products would be enzymatically active and their kinetical constants would be less than about 1 x 1 0 8 m -1 sec-1. | | | |
Reference
| (Z. Naturforsch. 31c, 29 [1976]; received July 7/September 19 1975) | | | |
Published
| 1976 | | | |
Keywords
| Photodynamic Effect, Singlet Oxygen, Lysozyme, Acridine Orange, Kinetics | | | |
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| default:Reihe_C/31/ZNC-1976-31c-0029.pdf | | | | Identifier
| ZNC-1976-31c-0029 | | | | Volume
| 31 | |
| 14 | Author
| HansW. Erner Müller, Udo Schwuléra, Manfred Salzer, Klaus Dose | Requires cookie* | | | Title
| Purification, Subunit Structure, and Kinetics of the Chloroform-Released FjATPase Complex from Rhodospirillum rubrum and Its Comparison with FjATPase Forms Isolated by Other Methods | | | | Abstract
| A stable and homogeneous adenosine-5'-triphosphatase (ATPase, EC 3.6.1.3) has been solubilized from R hodospirillum rubrum (R . rubrum) chromatophores by chloroform extraction. Purification of the Ca2+-dependent ATPase activity was 200-fold. Ca2+ can be replaced by M g2+, Cd2+, and M n2+ .The K m for Ca-ATP (0.17 m M) is increased about 5-fold during solubilization of the enzyme, whereas the K m values for Mg-ATP (0.029 m M) and Cd-ATP (0.014 m M) are not affected. The chloroform-released A TPase has a molecular weight of 400,000 + 30,000 and consists of the following subunits (m olecular weights in parenthesis): a (58,000), ß (53,500), y (39,000), 6(18,500), and £(14,000). The amino acid composition and the fluorescence spectra are presented. Besides the chloroform-released A TPase complex three other Ca2+-dependent A T Pase forms have been isolated from R. rubrum chromatophores by other methods for comparison. Ultrasonica-tion of the m em branes leads to the release of an ATPase complex which is m ainly composed of a, ß , and 7 -subunits. From an acetone powder extract an A TPase complex could be purified by affinity chromatography which is composed of four kinds of subunits (a, ß , y, 6). The same acetone powder yields an A TPase consisting of only three different types of subunits (a, ß, y) if the final purification step is preparative disc electrophoresis on 6% polyacrylam ide gels instead of affinity chromatography. | | | |
Reference
| Z. Naturforsch. 34c, 38 (1979); received November 10 1978 | | | |
Published
| 1979 | | | |
Keywords
| Rhodospirillum rubrum, F xA TPase Complexes, Subunit Structure, Kinetics | | | |
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| default:Reihe_C/34/ZNC-1979-34c-0038.pdf | | | | Identifier
| ZNC-1979-34c-0038 | | | | Volume
| 34 | |
| 16 | Author
| Hans Liidi, Bernhard Rauch, Wilhelm Hasselbach | Requires cookie* | | | Title
| The Influence of Detergents on the Ca2+-and Mg2+-Dependent Adenosine Triphosphatase of the Sarcoplasmic Reticulum | | | | Abstract
| During the stepwise solubilization of sarcoplasmic reticulum vesicles with detergents, the following changes in the structural and enzymatic properties of the preparation are observed: 1. The viscosity of the vesicular suspension initially rises. This change is accompanied by the formation of elongated tubules. Subsequently the membranes are completely desintegrated, resulting in a considerable reduction of the viscosity. 2. A decrease in the activity of the Ca2+-dependent ATPase, which is restored after complete solubilization. 3. A decrease in the change of intrinsic tryptophan-fluorescence on removal of calcium ions, which is also restored after complete solubilization. 4. A decrease of the calcium affinity of the ATPase. 5. A decrease in the amount of phosphorylated protein formed by the incorporation of inorganic phosphate. On the other hand, the amount of phosphoprotein formed from ATP is not affected during solubilization. 6. The dependence of the initial rates of phosphoprotein formation from inorganic phosphate on either magnesium or inorganic phosphate at low concentrations of the respective ligand changes from an S-shape profile to a normal hyperbolic profile after solubilization. | | | |
Reference
| Z. Naturforsch. 37c, 299—307 (1982); received January 1982 | | | |
Published
| 1982 | | | |
Keywords
| Sarcoplasmic Reticulum, ATPase, Detergent, Protein-Phosphorylation, Kinetics | | | |
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| default:Reihe_C/37/ZNC-1982-37c-0299.pdf | | | | Identifier
| ZNC-1982-37c-0299 | | | | Volume
| 37 | |
| 17 | Author
| Ingrid Gilles, Hans-Gerd Löffler, Friedhelm Schneider | Requires cookie* | | | Title
| Ein neues Isolierungsverfahren für Schweinenierenacylase. Kinetik des Co2+, M n2+, N i2+ und Cd2+-enzyms A New Isolation Procedure for Acylamino Acid Amidohydrolase. Kinetics of the Co2+, M n2+, N i2+ and C d2+ Enzyme | | | | Abstract
| A new procedure for the isolation o f highly purified acylamino acid amidohydrolase from hog kidney is d e scribed which allows the preparation o f the enzym e with a recovery o f about 45%, a 200 fold purification and a spec.activity o f 3 5 0 -5 0 0 U. The essential Zn2+ o f the enzyme was exchanged for Co2+, N i2+, M n2+ and C d2+, and the kinetic parameters K M, kCdl and kCät/ K M o f the different enzyme species for a series o f acetyl-L-amino acids were determined. | | | |
Reference
| Z. Naturforsch. 39c, 1017 (1984); received June 18/July 13 1984 | | | |
Published
| 1984 | | | |
Keywords
| Acylamino Acid Amidohydrolase, Isolation, Metall Ion Exchange, Kinetics | | | |
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| default:Reihe_C/39/ZNC-1984-39c-1017_n.pdf | | | | Identifier
| ZNC-1984-39c-1017_n | | | | Volume
| 39 | |
| 18 | Author
| AniruddhaP. Sane, VidhuA. Sane | Requires cookie* | | | Title
| Isolation and Kinetic Analyses of the Soluble ¥i ATPases from Mitochondria of Wheat and Pearlmillet | | | | Abstract
| The mitochondrial F j ATPases from two cereal crops, wheat and pearlmillet, were purified and studied. The wheat F, ATPase could be purified to homogeneity and is apparently com posed of six subunits with apparent molecular weights of 55 kDa (a and ß), 35 kDa (y), 26 kDa (8 ') and 22 kDa (8). The e subunit was barely detectable. Both enzymes reveal typical non-linear kinetics but show variability in their response to bicarbonate and chloride. While the wheat F, ATPase is stimulated by bicarbonate and chloride, the pearlmillet F j ATPase is inhibited by both anions. The two enzymes are Mg2+ dependent ATPases and are competi tively inhibited by Ca2+, unlike maize, pea and turnip ATPases. Both the enzymes also pos sess a GTPase activity which is two fold higher than the ATPase, unlike rice, sorghum and oat root Fj ATPases. | | | |
Reference
| Z. Naturforsch. 53c, 341 (1998); received December 12 1997/January 22 1998 | | | |
Published
| 1998 | | | |
Keywords
| F] ATPase, Purification, Kinetics, Wheat, Pearlmillet | | | |
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| default:Reihe_C/53/ZNC-1998-53c-0341.pdf | | | | Identifier
| ZNC-1998-53c-0341 | | | | Volume
| 53 | |
| 19 | Author
| FayezY. Khalil, M. T. Hanna | Requires cookie* | | | Title
| Kinetic Study of the Acid Hydrolysis of Ethyl Hydrogen Succinate in Binary Solvent Mixtures | | | | Abstract
| The specific rate constants for the acid-catalysed hydrolysis of ethyl hydrogen succinate in water and in a series of acetone-water and dioxane-water mixtures were determined at 30-45 °C. The solvent composition covered the range 0-90% by weight of the organic solvent. The rate was found to decrease to a minimum at about 80% of the organic solvent then to increase again with successive addition of the latter. In dioxane-water medium a slight initial increase in rate on the first addition of dioxane to water was observed and attributed to an increase in the number of "free" water molecules. The activation energy showed only slight dependence on solvent composition. The radius of the activated complex was calculated in the two media. The thermodynamic parameters were evaluated and discussed in terms of solvent composition. The reaction proved to be essentially an ion-dipole rather than an ion-ion interaction. A comparative discussion of the specific solvent effects of the two solvent systems under consideration is presented, based on the respective bond energies as given by the heats of mixing of the solvent components. | | | |
Reference
| Z. Naturforsch. 33b, 1479—1483 (1978); received April 25 1978 | | | |
Published
| 1978 | | | |
Keywords
| Ethyl Hydrogen Succinate, Acid Hydrolysis, Kinetics, Solvent Effects, Thermodynamic Parameters | | | |
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| default:Reihe_B/33/ZNB-1978-33b-1479.pdf | | | | Identifier
| ZNB-1978-33b-1479 | | | | Volume
| 33 | |
| 20 | Author
| Volker Böhmer, Klaus Wörsdörfer | Requires cookie* | | | Title
| Nachbargruppeneffekte bei der Aminolyse von Estern, III Der verlangsamende Einfluß von Triethylamin bei der Aminolyse von 2 -( 2 -Hydroxy benzyl )pheny lacetaten Neighboring Group Effects in the Amino lysis of Esters, III The Rate Diminishing Influence of Triethylamine in the Aminolysis of 2-(2-Hydroxybenzyl)phenylacetates | | | | Abstract
| The rate of the aminolysis of 2-(2-hydroxybenzyl)phenylacetates with n-butylamine in dioxane is diminished by the addition of triethylamine. This can be quantitatively described by the competitive formation of complexes between monoacetate and n-butyl-amine or triethylamine, if the assumption is made, that the complex with triethylamine is aminolysed slowly or not at all. The neighboring group effect in aminolysis cannot be explained therefore by a base catalysed decomposition of the tetrahedral intermediate. | | | |
Reference
| Z. Naturforsch. 34b, 720—727 (1979); eingegangen am 6. April/23. November 1978/17. Januar 1979 | | | |
Published
| 1979 | | | |
Keywords
| Kinetics, Aminolysis, Neighboring Group Effects, 2-(2-Hydroxybenzyl)phenylacetates, Triethylamine | | | |
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| default:Reihe_B/34/ZNB-1979-34b-0720.pdf | | | | Identifier
| ZNB-1979-34b-0720 | | | | Volume
| 34 | |
|
