Investigation of the structural features of insoluble complex-forming sorbents with the aid of solid-state high-resolution13C NMR spectroscopy

The special features of the chemical structure of polymeric complex-forming sorbents obtained on the basis of various polymeric matrices with a macroporous structure and pyrazole derivatives have been investigated with the aid of solid-state high-resolution¹³C NMR spectroscopy (MAS/CP/DD). The signals of the atoms in individual structural fragments of the polymeric matrices and the complex-forming groups have been identified, and the form of the complex-forming groups in the sorbent and the form in which they appear in the polymeric matrix have been established.V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 72–78, March–April, 1991.     

On the behaviour of Eu oxo-species in molten NaBr–NaI (0.77:0.23) mixture at 973 K

The interaction of Eu₂O₃ with molten NaBr–NaI (0.77:0.23) mixture at 973 K was studied by sequential addition method with the use of YSZ membrane oxygen electrode for controlling of course of the process. The Red-Ox process is accompanied with formation of EuO in the melt. The total solubility of EuO (sum of concentration of Eu²⁺, O^2–, non-dissociated EuO) in the molten NaBr–NaI at 973 K (mole fraction 2.7 × 10^–4) is considerably lower than in pure NaI melt (4.2 × 10^–4), which can be explained using the ‘hole’ model by reduction of a number of holes of comparable with EuO particle size because of addition of smaller bromide ion to the iodide melt.

The solubility of EuO is appreciably affected by its dispersity and the value of surface energy causing these solubility changes is estimated as 37 J m^–2.     

Precision magnetic quadrupole lens for a nuclear scanning microprobe based on an ÉGP-10 electrostatic tandem accelerator

Basic ideas underlying the design of a precision magnetic quadrupole lens for a nuclear scanning microprobe with a maximal accelerating voltage of 14 MV are set forth. Four magnetic quadrupoles are combined into doublets. The doublets are placed on adjusting gears, which bring the local coordinate system of each lens into coincidence with the laboratory system related to the axis of the beam. Each lens provides a maximal gradient of the field of 0.68 T/cm, which makes it possible to perform stigmatic focusing of the beam with a working distance of 22 cm. All lenses are nonseparable and made of one piece of high-quality electrical steel. A special lens-feeding unit is designed that provides manual and remote control of pole tip excitation.     

Structure of a supersonic jet of an argon-helium mixture in a vacuum

Results of an experimental investigation of barodiffusion processes in supersonic jets of argon and helium mixtures by using an electron beam are presented.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 158–163, September–October, 1970.     

Direct Statistical Simulation of a Supersonic Flow of a Binary Mixture of Rarefied Gases around a Transversely Positioned Cylinder

A supersonic flow of a binary mixture of gases in a wide range of rarefaction (from a flow with a Knudsen number K _n = 0.1 to a free-molecular flow) around a cylinder is studied by means of direct statistical Monte Carlo simulations (DSMC method). The influence of a small fraction of heavy particles in a light gas flow on the region of significant nonequilibrium near the cylinder and on the heat flux is considered.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 53–59, September–October, 2005.     

Low-Energy Collisions of Protonated Enantiopure Amino Acids with Chiral Target Gases

Here we report on the gas-phase interactions between protonated enantiopure amino acids (l- and d-enantiomers of Met, Phe, and Trp) and chiral target gases [(R)- and (S)-2-butanol, and (S)-1-phenylethanol] in 0.1–10.0 eV low-energy collisions. Two major processes are seen to occur over this collision energy regime, collision-induced dissociation and ion-molecule complex formation. Both processes were found to be independent of the stereo-chemical composition of the interacting ions and targets. These data shed light on the currently debated mechanisms of gas-phase chiral selectivity by demonstrating the inapplicability of the three-point model to these interactions, at least under single collision conditions.

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