Optical Properties of Porous Glass Modified with Vanadium(V) Oxide

Porous glasses modified with vanadium(V) oxide were obtained by impregnation with aqueous NH₄VO₃ solutions and by subsequent thermal decomposition of the salt. Changes in the charge-transfer spectra, resulting from an increase in the content of the deposited oxide and from water sorption, and also the possibility of using vanadium-containing glass for visual monitoring of air humidity were considered.     

Isolation and Identification of Peptides from Soy 11S-Globulin with Hypocholesterolemic Activity

A peptide with hypocholesterolemic activity was isolated by HPLC from the pepsin hydrolysate of 11S-globulin. Its molecular weight (755.2 Da) and amino-acid sequence (Ile-Ala-Val-Pro-Gly-Glu-Val-Ala) were established. The hypocholesterolemic effect was determined by analysis of bile-acid binding and the percent inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase in vitro. The lowering of the cholesterol content is explained by bile acids bound to hydrolysate peptides shielding them from reabsorption and stimulating the transformation of cholesterol in blood plasma. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 585–588, November–December, 2005.     

Photodielectric Processes in ZnS : Cu Polycrystalline Layers

The frequency dependences of dielectric parameters of zinc sulfide electroluminescent polycrystalline structures doped with copper are studied in the dark and under light excitation in the visible wavelength range. A positive photodielectric effect most pronounced in the low-frequency range was revealed. The experimental results are explained within framework of formation of a space charge in the bulk of a semiconductor. The analysis of data indicates they can be correlated with luminance characteristics of an electroluminescent layer.     

Special features of the state of copper(II) oxide and its electric conductivity in porous glass

Controllable accumulation of copper(II) oxide in porous glass was carried out by repeated impregnation of the carrier by Cu(NO₃)₂ aqueous solutions with subsequent thermal decomposition of the salt. The results of measuring electric conductivity of a series of modified plates in combination with the data on the optical and X-ray electron spectroscopy make it possible to characterize two trends in the oxide distribution on a silica surface. In the case of its cyclic accumulation by small portions, a two-dimensional structure of monolayer filling the surface is presumably formed in a narrow range of CuO concentration, whereas the increase in the ??step?? of the accumulation gives rise to the formation and growth of island oxide particles.     

Fatigue testing of condoms

Tests currently used for condoms are surrogates for the challenges they face in use. The tests involve looking for holes and slow stretching to break. This article describes a test that adds cyclic strain to a level well below breakage, and examines the differences among brands and types of condom. It is shown that there are very significant differences in resistance to cyclic straining. Such a test could be developed into a standard test for condom acceptability.     

Hole Localization in Thallium Nitrate (I)

Russian Physics Journal - Using the EPR method, an identification of paramagnetic centers formed in TlNO3 under γ-irradiation at 77 and 300 K is performed. Their spectral characteristics,...     

Synthesis of 2-Methylthio-4H-4-chromenones via Ketene Dithioacetal in the One-Pot Reaction

2-Methylthio-4H-4-chromenone which is key intermediate for the synthesis of 2-methylsulfonyl-4H-4-chromenone, equivalent to 2-halo-4H-4-chromenone, was very easily and efficiently synthesized from 2'-hydroxyacetophenone analogues via ketene dithioacetal in the one-pot reaction.     

The Webster scalar curvature flow on CR sphere. Part I

This is the first of two papers, in which we prove some properties of the Webster scalar curvature flow. More precisely, we establish the long-time existence, L^p$L^p$ convergence and the blow-up analysis for the solution of the flow. As a by-product, we prove the convergence of the CR Yamabe flow on the CR sphere. The results in this paper will be used to prove a result of prescribing Webster scalar curvature on the CR sphere, which is the main result of the second paper.     

Tiling simply connected regions with rectangles

In 1995, Beauquier, Nivat, Rémila, and Robson showed that tiling of general regions with two bars is NP-complete, except for a few trivial special cases. In a different direction, in 2005, Rémila showed that for simply connected regions by two rectangles, the tileability can be solved in quadratic time (in the area). We prove that there is a finite set of at most 10⁶ rectangles for which the tileability problem of simply connected regions is NP-complete, closing the gap between positive and negative results in the field. We also prove that counting such rectangular tilings is #P-complete, a first result of this kind.