Scattering Indicatrix of Aqueous Hemoglobin Solutions

Journal of Applied Spectroscopy - Aqueous solutions of human hemoglobin have been studied by the multi-angle static light scattering method. The tendency of sickle-shaped erythrocytes to aggregate...     

Point Mutations of Nicotinic Receptor α1 Subunit Reveal New Molecular Features of G153S Slow-Channel Myasthenia

Slow-channel congenital myasthenic syndromes (SCCMSs) are rare genetic diseases caused by mutations in muscle nicotinic acetylcholine receptor (nAChR) subunits. Most of the known SCCMS-associated mutations localize at the transmembrane region near the ion pore. Only two SCCMS point mutations are at the extracellular domains near the acetylcholine binding site, α1(G153S) being one of them. In this work, a combination of molecular dynamics, targeted mutagenesis, fluorescent Ca²⁺ imaging and patch-clamp electrophysiology has been applied to G153S mutant muscle nAChR to investigate the role of hydrogen bonds formed by Ser 153 with C-loop residues near the acetylcholine-binding site. Introduction of L199T mutation to the C-loop in the vicinity of Ser 153 changed hydrogen bonds distribution, decreased acetylcholine potency (EC₅₀ 2607 vs. 146 nM) of the double mutant and decay kinetics of acetylcholine-evoked cytoplasmic Ca²⁺ rise (τ 14.2 ± 0.3 vs. 34.0 ± 0.4 s). These results shed light on molecular mechanisms of nAChR activation-desensitization and on the involvement of such mechanisms in channelopathy genesis.     

Perpendicular magnetic anisotropy in single-crystal Co<Subscript>50</Subscript>Pt<Subscript>50</Subscript>/MgO(100) films

The crystal structure and hysteretic magnetic properties of equiatomic single-crystal CoPt films applied on MgO substrates by magnetron sputtering, as well as modification of these properties by thermal annealing, are studied. Heat-treated films of thickness in the range 2<d≤16 nm exhibit perpendicular magnetic anisotropy. A correlation between the crystalline anisotropy constant of the CoPt films and the order parameter of the LI₀ superstructure in these alloys is found. The effect of a single-crystalline MgO substrate on the structure and magnetic properties of equiatomic CoPt films is revealed.     

Nonstoichiometry and low-temperature magnetic properties of FeSi crystals

The results of experimental and theoretical studies of the low-temperature properties of FeSi crystals are presented. The specific features of the magnetic susceptibility are shown to be related to the superparamagnetic behavior of impurity clusters. The thermomagnetic hysteresis phenomena observed are explained using the model of exchange-coupled clusters.     

Cation distribution and interatomic interactions in oxides with heterovalent isomorphism: XI. (La1−xHox)2SrAl2O7 solid solutions

Interatomic distances and distributions of rare-earth and strontium cations over two sites in the structure of (La_1?x Ho_x)₂SrAl₂O₇ solid solutions were determined by means of full-profile X-ray structural analysis. Introduction of holmium cations into the La₂SrAl₂O₇ oxide results in ordered distribution of Ln³⁺ cations and stabilization of the perovskite-like structure.     

Synthesis of cyclic sulfites of stereoisomeric 3,4-caranediols

Conclusions The cyclic sulfites of the 3, 4- and 3,4-caranediols were synthesized as mixtures of two isomers that differ in the relative position of the S=O and 10-CH₃ groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1670–1671, July, 1976.     

Electrophilic addition of lead tetraacetate to 2-carene in an acidic medium

Oxidation of 2-carene by lead tetraacetate in acetic acid afforded p-menth-1(10),2-dien-7-ol, 2-acetyl-6,6-dimethylbicyclo[3.1.0]hexane, p-menth-2-ene-1,7-diol, p-menth-1-ene-3,7-diol, and 2-(m-tolyl)propanol-2.Deceased.A. M. Butlerov Scientific Research Chemical Institute, V. I. Ul'yanov-Lenin Kazan' State University, 420008 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 147–150, January, 1992.     

Metal complexes in the catalytic reactions of olefins. 1. Comparison of the catalytic properties of triphenylphosphine nickel complexes both individually and heterogenized on Al2O3 in the dimerization of ethylene

Conclusions By studying the liquid-phase dimerization of ethylene in the presence of Cat-Et₃Al₂-Cl₃ catalytic systems based on a nickel complex heterogenized on Al₂O₃ and a number of model nickel complexes, a similar activity and selectivity of the process has been established (Cat=NiPPh₃(CO)₂L, where L=PPh₃, CO, Al₂O₃; Ni(PPh₃)₂(CO)₂; Ni(PPh₃)₂(₂-C₂H₄); Ni[P(C₆H₁₁)₃]₂(H)Cl and Ni(PPh₃)(Et)Cl).The results of the investigation agree with the hypothesis that mono- and diolefinic nickel complexes are formed as the active intermediates in the reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2466–2469, November, 1988.