Low-temperature conductivity of a two-dimensional disordered semiconductor under power localization conditions

An estimate is given of the temperature dependence of the conductivity under conditions when the Fermi level is in the power localization domain.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 24–26, November, 1982.One of us (V. L. Bonch-Bruevich) is grateful to Dr. M. Pepper for sending a preprint.     

The adsorption properties of titanium dioxide

The adsorption properties of titanium dioxide were studied by gas chromatography. We used organic compounds from different classes, namely, n-alkanes, n-alkenes (C₆-C₈), and polar compounds (electron donors and acceptors) as test adsorbates. The differential heats of adsorption and the contributions of dispersion and specific intermolecular interaction energies were determined for the systems from the experimental retention data. The electron-donor and electron-acceptor characteristics of the ultimately hydroxylated surface of TiO₂ were evaluated.     

On continuous dependence of solutions of linear differential equations on a parameter in a Banach space

We prove the reduction theorem for linear differential equations in a Banach space in the case where the convergence is strong. This result is used to obtain the necessary and sufficient conditions for continuous dependence of solutions on a parameter. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 51, No. 2, pp. 275–280, February, 1999.     

Kinetics of catalytic hydrogenation of 4-nitroaniline in aqueous solutions of propan-2-ol with acid or base additives

The effect of addition of acetic acid and sodium hydroxide to an aqueous azeotropic solution of propan-2-ol on the rate of 4-nitroaniline hydrogenation is studied. The base additive accelerates the apparent rate of nitro group reduction, while the presence of acetic acid slows the reaction rate. It is experimentally established that the rate of nitro group conversion calculated from the amount of reacted 4-nitroaniline exceeds the rate of hydrogen uptake from the gas phase in all of the studied solvents. Hydrogen bound by active sites of the catalyst surface is found to participate notably in the reactions. It is proved both experimentally and theoretically that strongly bound atomic forms of adsorbed hydrogen are most active in the reduction of the nitro group.     

Multiresidue determination of pesticides in fruit and vegetables by gas chromatography/tandem mass spectrometry

Pesticide residues in fruit and vegetables were determined by gas chromatography/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and chemical ionization (CI)/MS/MS were developed for 80 compounds, including organochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichloromethane-petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS. Initial steps involving cleanup and concentration of extracts were eliminated. The excellent selectivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been used for routine analysis of many vegetables.     

Dynamics of the accumulation of the flavan compounds ofHibiscus cannabinus

The amounts and compositions of the flavan compounds in various organs of kenaf according to the vegetation periods have been studied. It has been established that the maximum amounts of flavan substances are formed in the phloem and roots in the vegetation period.Deceased.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 558–560, September–October, 1981.     

Solution of a nonlinear resonance boundary problem

An iterational method is given for solving a nonlinear resonance boundary problem.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 5, pp. 663–674, May, 1991.     

Activation of metal-acyl oxygen atoms by triflic anhydride: a simple synthetic route to reactive cationic vinylidene complexes

(η⁵-Cyclopentadienyl) (acyl) (carbonyl) (tertiary phosphine) iron complexes react rapidly with trifluoromethanesulfonic acid anhydride to afford cationic vinylidene complexes, via the intermediacy of cationic carbene complexes. Spectroscopic and chemical characterizations of these vinylidene complexes are reported.