摘要:

The self-diffusion of nickel has been studied in polycrystalline samples by a sectioning technique. There is evidence of grain boundary diffusion below temperatures of 1150 °C. The results obtained between 1150° and 1400 °C are representative of volume diffusion and are represented by the expressionA comparison is made with the results of other self-diffusion studies using Zener's hypothesis.

ISSN:0008-4042    

DOI:10.1139/v59-236

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The self-diffusion of nickel and the diffusion of Ni63into iron, cobalt, and two iron–nickel alloys was studied using the technique of decrease in surface activity, The nickel self-diffusion results are compared to previously reported values. Nickel is found to diffuse more slowly than iron in the iron-rich portion of the iron–nickel system. The rate of nickel diffusion increases with increasing nickel content. A comparison is made between the present results for diffusion of Ni63into iron, cobalt, and nickel with reported values for diffusion of Co60and Fe59in the same metals. In each solvent, the magnitudes of the activation energies,Q, are such thatQNi > QCo > QFe.

ISSN:0008-4042    

DOI:10.1139/v59-237

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Under the activating influence of short-wave ultraviolet light, diphenylamine and nitrate ions in solution or on filter paper react to yield a yellow-colored product. Between pH 4 and 10 this consists mainly of 2-nitrodiphenylamine and 4-nitrodiphenylamine. Over this range of pH, the absorption maxima at 405 mμ did not shift; however, the intensity of absorption appeared to reach a minimum at or near neutrality and then increase rapidly as the solution was made more alkaline. The reaction rate was not affected by lowering the concentration of diphenylamine from 0.38% to 0.038%. A similar change in nitrate concentration decreased the rate 5.4 times. No evidence of nitroso compounds was found. Possible mechanisms are suggested.

ISSN:0008-4042    

DOI:10.1139/v59-238

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Starting with formaldehyde-C14, 1,2-dibromocyclopentane-4-C14(XI) was synthesized in eight steps. Conversion of XI to cyclopentadiene was accomplished in three different ways, namely: the dehydrobromination of XI with quinoline at 195–198 °C, the preparation of 1,2-bis-(trimethylammonium)-cyclopentane-4-C14hydroxide from XI followed by thermal decomposition, and the conversion of XI to 3,5-dibromocyclopentene followed by reaction of the latter with magnesium in dry ether. Degradations of the samples of cyclopentadiene obtained by these three synthetic routes showed a completely randomized distribution of the C14activity, with 20% of the total activity on each of the five carbon positions. These results led to the conclusion that these preparations of cyclopentadiene very likely involved ionization to the cyclopentadienyl anion. The randomized distribution of C14in the resulting products thus furnishes a strong indication that all five carbon positions in the cyclopentadienyl anion are equivalent.

ISSN:0008-4042    

DOI:10.1139/v59-239

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The water vapor permeability of cellophane was measured over adsorption–desorption cycles and was found to parallel the sorption isotherm. When a constant vapor pressure was applied on the low pressure side of the membrane, the mass flow rate was independent of the vapor pressure used and showed hysteresis on desorption. The permeabilities of methanol, ethanol, and benzene were found to increase with increasing vapor pressure.

ISSN:0008-4042    

DOI:10.1139/v59-240

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The partial specific volumes of several macromolecules were determined from their sedimentation rates in aqueous and heavy water solutions with results comparable to those obtained by conventional methods. Corrections for the changes in weight due to isotopic exchange were obtained from measurements on small quantities of material with a quartz spiral balance. Measurements of the partial specific volumes of bovine plasma albumin, polyvinyl alcohol, glycine, and triglycylglycine in both aqueous and heavy water media, made with a magnetic float apparatus, indicate that isotopic exchange has no significant effect on the macromolecular volume. The sedimentation method is therefore a micro method that does not require a knowledge of the concentration of macromolecules and which is applicable to mixtures that are resolvable during sedimentation.

ISSN:0008-4042    

DOI:10.1139/v59-241

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The initial rates of product formation in the photooxidation of acetaldehyde at room temperature have been determined through the use of infrared spectrometry. The rates of formation of the products peroxyacetic acid, carbon monoxide, carbon dioxide, methanol, formic acid, and acetic acid were determined in experiments with various pressures of acetaldehyde, oxygen, and added gases. The amounts of methylhydroperoxide and acetylperoxide formed in all of the experiments were below the detection limit of the analytical methods. The results require that some modification and corrections be made to the mechanism suggested by McDowell and Sharples.

ISSN:0008-4042    

DOI:10.1139/v59-242

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Molecular oxygen was subjected to an electrodeless discharge in the pressure range 0.1–3 mm Hg. The oxygen atom concentration was measured as a function of time in a flow system by means of a movable atom detector which consisted of a platinum wire coated with a suitable catalyst for atom recombination. The atom concentration was calculated from the heat liberated when the detector was operated under isothermal conditions. The surface recombination was found to be first order in the atom concentration. A value of 7.7 × 10−5was obtained for the recombination coefficient (γ) on Pyrex. No temperature dependence for γ was observed. The gas phase recombination of oxygen atoms was found to be consistent with the mechanismThe rate constant for the third-order reaction was found to have a value of 1.0 × 1014 cc2mole−2sec−1, and a small negative temperature dependence.Evidence was also obtained for the presence of considerable amounts of excited molecular oxygen in electrically activated O2.

ISSN:0008-4042    

DOI:10.1139/v59-243

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

In the reaction between NO and O-atoms, the concentration of NO remains essentially unaltered. The reaction can therefore be considered as a NO-catalyzed recombination of O-atoms. Its rate can be conveniently studied by following the disappearance of O-atoms by an isothermal calorimetric technique. The reaction was found to be third order, first order in the concentrations of O, NO, and M, where M is some third body. The third-order rate constant was found to be 1.85 × 1016 cc2mole−2sec−1when M = O2, A, or He and 2.0 × 1016 cc2mole−2sec−1when M = CO2The rate constant was found to have a slight negative temperature coefficient which corresponded to a negative Arrhenius activation energy of about 0.2 kcal/mole. A detailed mechanism for the reaction has been proposed.

ISSN:0008-4042    

DOI:10.1139/v59-244

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The Hg3P1-photosensitized decomposition of benzaldehyde at low pressure and high radiation intensity forms predominantly a polymeric material. In the fraction of the reaction which forms the identifiable final products benzene and carbon monoxide, both a direct molecular rearrangement and a free radical split to phenyl and formyl radicals occur. The decomposition reactions of acrolein and crotonaldehyde involve the three primary processes:

ISSN:0008-4042    

DOI:10.1139/v59-245

出版商:NRC Research Press    

年代:1959

数据来源: NRC