Calculation of nonstationary drainage in the case of a finite number of closed horizontal drains

In the hydrodynamic formulation, a study is made of nonstationary drainage in a water-bearing stratum in the presence of a finite number of closed drains and variable infiltration. The drains are simulated by linear sinks with known time-dependent flow rates per unit length of the drains. The dependences found in the paper enable one to predict, and if necessary also regulate the dynamics of the level of ground water in a drained region, which is of practical interest in the study of salinization and swamping of land.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 165–170, July–August, 1979.     

Application of IR spectroscopy in the analysis of the woody-fibrous mass in the process of hydrolysis

The possibility has been shown of using IR spectroscopy in the investigation of the changes in the polysaccharide component of wood in the process of acid hydrolysis. The method of determining the relative optical density (ROD) was used for the quantitative evaluation of the changes in the functional groups of the lignocellulose.     

Tautomeric and conformational properties of malonamic acid methyl ester, NH2C(O)-CH2-C(O)OCH3: electron diffraction and quantum chemical study

The tautomeric and conformational properties of malonamic acid methyl ester, NH2C(O)-CH2-C(O)OCH3, have been investigated by means of gas-phase electron diffraction (GED) and quantum chemical calculations (HF, B3LYP, and MP2 approximations with different basis sets up to 6-311++G(3df,pd)). Both quantum chemistry and GED at 360(8) K result in the existence of a single diketo conformer in the gas phase. According to GED refinement, this conformer possesses an (ac, sc) conformation with dihedral angles C-C-C(NH2)=O of 140.3(3.0) degrees and C-C-C(OCH3)=O of 31.1(7.2) degrees. The experimental geometric parameters are reproduced very closely by MP2 and B3LYP methods with large basis sets.     

Optical field at the center of a sphere

The paper gives an exact formula for determining the intensity of an optical field at the center of a spherical particle of arbitrary radius obtained by evaluating an indeterminate form of the 0/0 type of Mie theory for the electricfield components at the center of the sphere. This formula is valid for arbitrary values of the complex refractive index of the particle material and arbitrary wavelengths of the incident radiation. An approximation for large particles and two approximations for particle sizes less than 10^–4 cm are obtained. The solution obtained for the opticalfield intensity at the center of small particles coincides with the classical Lorentz formula for local fields.     

Analysis of the demixing of yttria-stabilized zirconia in an electric field for different diffusion mechanisms

Steady-state demixing of the cations in yttria-stabilized zirconia in an electric field is analyzed for diffusion via independent vacancies, by vacancy pairs and by vacancy triplets. We analyze two conditions, one (open system) where the vacancies are everywhere close to an internal surface, which allows the Schottky defect reaction to permit the equilibration of the concentration of the vacancies, the other (closed system) where such equilibration is only possible at the external surface. For diffusion via independent vacancies and vacancy pairs, critical values of the ratio of the yttrium to zirconium vacancy exchange frequencies causing yttrium enrichment at the cathode are determined. It is also shown that diffusion via the vacancy-triplet mechanism always leads to yttrium enrichment at the anode end. Using Monte Carlo simulation, we also verify the analysis of the situation where demixing occurs by independent cation vacancies in a closed system.     

Diffusion kinetics of isolated and paired species: a Monte Carlo study

In this paper, we address a four-frequency diffusion model that allows diffusion of paired and unpaired atoms (or small molecular species) in an otherwise empty lattice. The model is useful for describing tracer and collective diffusion of interstitials in dilute interstitial solid solutions and of adsorbed species on surfaces. Diffusion kinetics of this model have been treated analytically by McKee, Le Claire and Okamura and Allnatt. We use Monte Carlo computer simulation to calculate, for the first time, the correlation factors and the linear solute diffusion enhancement factor. Absolute values of the tracer correlation factors and the linear enhancement factors are in excellent agreement with the results of the theory of Okamura and Allnatt, but only in semi-quantitative agreement with results of the other theory. A general argument is also presented to show that the chemical diffusion coefficient does not exhibit correlation effects. This is verified by computer simulation.