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Abstract: GaSb/GaAlAsSb uncooled photodiodes for the 1.1-1.85 μm spectral range are fabricated and studied. A unique method for the growth of GaSb from lead solution-melts makes it possible to obtain a low carrier concentration in the active region: n = 2 × 1015 cm-3. The capacitance of the photodiodes is 70-110 pF for a sensitive -area diameter of 300 μm and 150-250 pF for a diameter of 500 μm. The photodiodes are characterized by a high (for GaSb devices) spectral sensitivity Sλ = 0.95 A/W at the maximum, a relatively low reverse dark current density j = (4-9) × 10-3 A/cm2 at Urev = 1.0-2.0 V, and high-speed performance (response time 5-10 ns). [ABSTRACT FROM AUTHOR]

Two problems are considered that describe the processes of impregnation and extraction in a semi-infinite porous solid in the case where a diffusion coefficient linearly depends on concentration. Using these problems as an example, it is shown that the method of fractional differentiation makes it possible to establish the structure of an exact solution for a diffusion flux on the domain boundary without predetermining a concentration field. Information obtained in this case is more detailed than that in the use of the dimensional theory. [ABSTRACT FROM AUTHOR]

A mathematical model for extraction from a semi-infinite porous body with pores of n kinds branched in a scale-similar manner, including the case in which n → ∞, is considered. The method of fractional differentiation is used to find the formulas describing the variation of target-component extraction yield with time that can be applied in practical calculations with t → 0 and t → ∞. The agreement between the theoretical results and experimental data is discussed. [ABSTRACT FROM AUTHOR]

The adsorption of unsaturated C18: n fatty acids on magnetite and volume effects of their dissolution in n-hexane and carbon tetrachloride are studied. It is established that an increase in the values of limiting adsorption of a series of oleic, linolic, and linolenic acids corresponds to positive volume effects of their dissolution in CCl4. Opposite picture of the adsorption behavior of studied acids in n-hexane corresponds to negative volume effects of the dissolution of the acids in this solvent. [ABSTRACT FROM AUTHOR]

The solubility of Kr in H2O-CD3OH-CO(NH2)2 and D2O-CH3OD-CO(ND2)2 mixtures in the entire range of compositions of the mixed aqueous-methanol solvent at a urea content of up to 1.5 solvomolality units (mole fraction 0.0263) was measured at 101 325 Pa and 278.15–318.15 K (at 10 K step). The standard Sechenov parameters K of the solubility of Kr and the thermodynamic parameters of krypton-urea pair interactions were determined. A differentiating effect of the H/D isotope substitution on K was revealed: Upon deuteration of groups participating in strong hydrogen bonding, the Sechenov solubility parameter increases, and upon replacement of CH3 by CD3, decreases in the absolute value. [ABSTRACT FROM AUTHOR]

The H/D isotope effects in the thermodynamic functions of solvation of N2 and O2 were calculated from the experimental data on the solubility of these nonpolar gases in H2O and D2O at ∼0.1 MPa and 278–318 K. The sharp increase in the solubility in going from N2 to O2 is caused both by a decrease in the contribution of the hydrophobic hydration and by the possibility of formation of H-type bonds by oxygen molecules with the aqueous environment. [ABSTRACT FROM AUTHOR]

The solubility of krypton in the liquid system H2O-CH3OH-CO(NH2)2 was measured at 101 325 Pa and 278.15–318.15 K (10 K step) in the whole range of compositions of the mixed aqueous-methanol solvent at the urea content of up to 1.5 solvomolality units (mole fraction 0.0263). The temperature dependence of the Sechenov parameter of the solubility of the noble gas exhibits an inversion in the region of equimolar composition of the water-methanol mixture. A considerable decrease in the salting-out of the gas with urea in this concentration region is due to loosening of the solvation shell of urea. [ABSTRACT FROM AUTHOR]

Within the concepts of structurally-thermodynamic characteristics of solvation and pseudo-chemical potential, the sample collection of the most authentic experimental data on solubility of gaseous He, Ne, Ar, Kr, Xe, and Rn in H2O and D2O is analysed at ≈0.1 MPa and T = 278–318 K. The conclusion is drawn that at deuteration of water molecules and also with increasing molar mass of noble gas, the relative contribution of effect of its hydrophobic hydration decreases. However in case of pass from lightweight noble gases (He, Ne, Ar) to heavy ones (Kr, Xe, Rn), structural transformations in their aqueous solutions become more expressed as a whole due to strengthening interaction between dissolved substance and solvent. [ABSTRACT FROM AUTHOR]

Based on experimental data about the density of very dilute solutions of H2O and D2O in 1,4-dioxane, hexamethylphosphotriamide, and acetonitrile at 278.15 K-318.15 K we determined the limiting partial molar volume (error ±0.03 cm3·mol−1) and dilatability of the water component. A correlation equation has been derived which relates the isotope effect (IE) in the limiting excess partial molar dilatability of water to the energy of the H2O-solvent hydrogen bond. The stated IE may be used as a “structural indicator” for evaluating the ability of an aprotic dipolar solvent to undergo specific interactions through hydrogen bonding. [ABSTRACT FROM AUTHOR]

Using the data of precision densimetry measurements for diluted solutions of H2O and D2O in 1,4-dioxane (1,4-DX) at 288.15 K-318.15 K we calculated the limiting partial molar volumes of the H/D isotopomers of water in dioxane and the excess molar volumes of the stated systems. The water molecules dispersed in 1,4-DX form complexes H-bonded into associates whose packing coefficient slightly exceeds that of the structural aggregates in liquid H2O and D2O. It is concluded that the structure of 1,4-DX is loosened and concomitantly undergoes volume expansion caused by the water microimpurities. The differentiating temperature effect on the volume solvation effects of H2O and D2O in 1,4-DX has been found. [ABSTRACT FROM AUTHOR]

The solubility of krypton in mixtures of H/D isotopomers of water (H2O, D2O) and methanol (CH3OH, CD3OH, CH3OD) was studied at 101325 Pa and 278.15-318.15 K with a 10 K step. The thermodynamic characteristics of Kr solvation were calculated. The densities of mixtures of water and methanol isotopomers at the examined temperatures were calculated with an error of no more than 1 × 10-5 g cm-3 in the entire composition range. Both in water and aqueous methanol, krypton behaves as a structure-making component, but the alcohol solvation surrounding of the Kr atoms is more labile and more susceptible to the breaking effect of temperature. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the influence of alkanol isomerization on the solvation of tetramethyl-bis-urea. The values of ΔsolHn∞ were measured on an ampule isoperibol calorimeter with approximately 60 milliliter reaction vessel. The results indicated that the successive increase in the number of carbon atoms in the normal alkanol molecule will produce a nonlinear change in ΔsolHn∞.

Diffusion in a flat capillary restricted by the arcs of concentric circles is studied. A flow of a substance in a curvilinear capillary turns out to be larger than in a rectilinear channel of the same length. However, for pore structures met in practice, this difference is negligible. [ABSTRACT FROM AUTHOR]