Activation and structural and adsorption features of activated carbons with highly developed micro-, meso- and macroporosity

Three sets of activated carbons (ACs) were prepared with the same precursor but activated differently (by CO₂ or water vapour) with various burn-off levels. The ACs demonstrate increased deviation of the pore shape from the slitshaped model with increasing burn-off and contributions of pores of different sizes depending on the activation type. Significant re-arrangement of adsorption complexes, especially of the Van der Waals type characteristic for nonpolar or weakly polar adsorbates (H₂, CH₄, CH₂Cl₂, CHCl₃), occurs in both micropores and mesopores of ACs with decreasing temperature. The behaviour of their mixtures with water and DMSO can strongly differ from that of individual adsorbates.     

The synthesis of Leishmania major phosphoglycan fragments

The triglycosyl monophosphate 1, heptaglycosyl triphosphates 2 and 3, and octaglycosyl triphosphate 4, which are fragments of the phosphoglycan part of Leishmania major lipo- and proteo-phosphoglycans have been prepared using di- and tri-saccharide H-phosphonates for construction of the phosphodiester bridges.     

Process for Preparation and Modification of Formulations for Medicine,Based on Blends of Ultra-High-Molecular-Weight Polyethylene and Polysiloxane

A process is proposed for preparing formulations based on ultra-high-molecular-weight polyethylene and polysiloxane, yielding materials with the required adhesion between the phases. Procedures are developed for physicochemical modification of the compositions with the aim to prepare items for medical purposes with various properties on working surfaces.     

On alkaline opening of columbite and tantalite

Sintering of columbite and tantalite with K₂CO₃·1.5H₂O with subsequent leaching of the sinters with water was studied. The possibility of selective extraction of Nb(V) and Ta(V) into liquid phase was demonstrated.     

EMC effect and breaking of additivity of nucleons in the high-energy hadron-nucleus interactions

The EMC effect implies a strong violation of additivity of nucleons in the absorption of virtual photons by atomic nuclei. In this paper we analyze the experimental data on the hadron-nuclei interaction cross sections in search for similar effects in the scattering of hadrons on nuclei. Specifically, we look for deviations from predictions of the multiple scattering theory. We formulate, and make extensive use of the Glauber-Bribov universality of the hadron-nucleus interaction cross sections, which makes it possible to check in a unique way a consistency of the experimental data on the total, inelastic and absorption cross sections for all the incident hadrons. We find evidence for the effective cross section of interaction with bound nucleons being 5–15% larger than with free nucleons. We comment on implications of this observation for models of the EMC effect.     

Methane Pyrolysis Stimulated by Admixture of Atomic Hydrogen: 2. Mechanism Analysis and Kinetics Calculation

The kinetics of methane pyrolysis stimulated by the introduction of atomic hydrogen into the reaction medium from an arcjet plasma source was analyzed. Numerical simulation of the reaction kinetics demonstrated that the thermal pyrolysis at lower temperatures (1800 K or lower) followed the radical chain mechanism with short chains (a chain length of 2 or 3), and the addition of atomic hydrogen considerably increased the rate of the process. An analysis of the kinetics of pyrolysis in a stirred reactor showed that acetylene was formed immediately after methane degradation without the buildup of by-products in the reaction medium.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 4, 2005, pp. 312–316.Original Russian Text Copyright © 2005 by Baranov, Demkin, Zhivotov, Nikolaev, Rusanov, Fedotov.     

Effect of residual gas on the ion charge distribution in vacuum arc discharge plasmas

A magnetic mass analyzer and time-of-flight mass spectrometer are used to study the effect of the pressure and type of residual gas on the ion charge distribution in the plasma of an arc discharge with a cathode spot. The possibility of ionizing a substantial fraction of the gas atoms in this type of discharge is pointed out. Zh. Tekh. Fiz. 68, 24–28 (September 1998)     

Mössbauer research of magnetic particles in medicinal ointments

Stability of the properties of magnetite particles in novel medicinal magnetic ointments of multipurpose application was studied using Mössbauer spectroscopy. Comparative analysis of the results obtained by model fitting of⁵⁷Fe nuclei spectra with those known for the system Fe₃O₄-γ-Fe₂O₃ allowed to identify the phase composition of the particles. This composition, as well as that of the initial pure component in the form of a highly dispersed fraction (～100 Å), differs noticeably from the stoichiometric one. Despite their small sizes, the particles exhibit no superparamagnetism (in the temperature range from 95 to 300 K). Radiative sterilization of the ointments has no effect on the magnetic component composition.