Solvolysis of allylic prostaglandin mesylates: moderate 1,3-<Emphasis Type="Italic">syn</Emphasis>-stereoselectivity

The stereochemistry of S _N2 and S _N2 substitutions of the allylic mesyloxy group in mesylates of prostaglandin allylic epimeric 13- and 15-alcohols under the action of various nucleophiles (H₂O, MeOH, AcOH, LiBr) was studied. The substitution accompanied by rearrangement occurs with moderate (1.4–1.6 : 1) syn-stereoselectivity with respect to the configuration of the mesyloxy group, which increases with decreasing temperature and depends only slightly on the nature of the nucleophile.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2510–2518, November, 2004.     

Far-infrared radiation effect on the structure and properties of proteins

This paper describes the effect of far-infrared radiation on the activity and secondary structure of albumin, alcohol dehydrogenase, peroxidase and trypsin. For the first time the data obtained allowed a conclusion that enzymatic activity changes under the influence of radiation having the wavelength of 90 m. No disruptures of polypeptide chains or oligomerization of proteins were obtained. It has been shown that albumin secondary structure calculated from circular dichroism spectra changes lineary according to dose of laser emission.Abbreviations FIR far-infarred radiation - CD circular dichroism - ADG alcohol dehydrohenase - PXD peroxidase - ANS 1-anilinenaphalene-8-sulfonic acid     

Metallic beta-phase silicon nanowires: Structure and electronic properties

Electronic band structure and energetic stability of two types of 〈110〉 and 〈001〉 oriented silicon nanowires in β-Sn phase with the surface terminated by hydrogen atoms were studied using density functional theory. It was found that β-Sn nanowires are metastable with zero band gap against to nanowires in diamond phase. The relative energy of the studied wires tends to the energy of the bulk silicon crystal in β-Sn phase.     

Modification of chemically and physically obtained Fe3O4 magnetic nanoparticles with l-Lys for cell labeling

Russian Chemical Bulletin - Peculiar features of the modification of Fe3O4 magnetic nanoparticles (MNPs) obtained by co-precipitation from solutions of FeII and FeIII salts (10-nm MNPs) and by the...     

Transport Properties of Magnetic Nanogranular Composites with Dispersed Ions in an Insulating Matrix

Journal of Experimental and Theoretical Physics - This review is devoted to an analysis of the electrical resistance, the magnetoresistance, and the anomalous Hall effect in magnetic...     

Facial Synthesis and Bioevaluation of Well-Defined OEGylated Betulinic Acid-Cyclodextrin Conjugates for Inhibition of Influenza Infection

Betulinic acid (BA) and its derivatives exhibit a variety of biological activities, especially their anti-HIV-1 activity, but generally have only modest inhibitory potency against influenza virus. The entry of influenza virus into host cells can be competitively inhibited by multivalent derivatives targeting hemagglutinin. In this study, a series of hexa-, hepta- and octavalent BA derivatives based on α-, β- and γ-cyclodextrin scaffolds, respectively, with varying lengths of flexible oligo(ethylene glycol) linkers was designed and synthesized using a microwave-assisted copper-catalyzed 1,3-dipolar cycloaddition reaction. The generated BA-cyclodextrin conjugates were tested for their in vitro activity against influenza A/WSN/33 (H1N1) virus and cytotoxicity. Among the tested compounds, 58, 80 and 82 showed slight cytotoxicity to Madin-Darby canine kidney cells with viabilities ranging from 64 to 68% at a high concentration of 100 μM. Four conjugates 51 and 69–71 showed significant inhibitory effects on influenza infection with half maximal inhibitory concentration values of 5.20, 9.82, 7.48 and 7.59 μM, respectively. The structure-activity relationships of multivalent BA-cyclodextrin conjugates were discussed, highlighting that multivalent BA derivatives may be potential antiviral agents against influenza infection.     

Microfocus X-Ray Tubes with a Silicon Autoemission Nanocathode as an X-Ray Source

To develop nanostructures with extremely low spatial resolution (to 10 nm and below), a new concept of the use of arrays of microfocus X-ray tubes based on field emission silicon nanocathodes is proposed. A new λ-tunable microfocus source of X-ray radiation, based on a thinfilm transmission target with field emission nanocathode with tunable wavelength, is proposed. The possibility of decreasing the exposed area size to 20 nm and smaller by varying the tube blocking voltage is shown. The use of these X-ray sources opens a new way of developing maskless X-ray lithography.     

Wave-Packet Dynamics Study of the Transport Characteristics of Perforated Bilayer Graphene Nanoribbons

JETP Letters - The electrical conduction characteristics of perforated bilayer graphene nanoribbons are studied by the wave-packet dynamics method. The transport characteristics for typical...     

Influence of acceptor doping on ionic conductivity in alkali earth titanate perovskites

The electrical conductivity of the SrTi_1−xFe_xO_3−δ, BaTi_1−xFe_xO_3−δ and SrTi_1−xMn_xO_3−δ systems has been studied in a range of oxygen partial pressures between 10⁻¹⁶ and 0.21 atm at 900 and 1000 °C. The materials exhibit predominantly ionic conductivity in a wide range of intermediate oxygen partial pressures. It has been found that in Fe doped strontium and barium titanates, the dependencies of the ionic conductivity on the acceptor concentration show a local maximum near x=0.2. Taking into account that in the CaTi_1−xFe_xO_3−δ system (x=0−0.5), the concentration dependence of the ionic conductivity also has a maximum near x=0.2, it can be concluded that this is a common phenomenon for Fe doped alkali earth titanates. An assumption has been made that a scheme of defect formation devised earlier for Fe doped calcium titanate is applicable for other alkali earth titanates.     

一类只有两个不同非零交换理想的无限维李代数

构造了一类无限维李代数,它是无中心的Virasoro李代数的推广,且只有两个不同的非零交换的理想.还研究了这类李代数的理想、中心和子代数.