Hybrid materials based on polymethylsilsesquioxanes containing Fe,Pt, and Fe–Pt metallic nanoparticles

New hybrid materials based on Pt, Fe, and Pt–Fe nanoparticles stabilized in a matrix of polymethylsilsesquioxane nanogel and ultrahigh molecular weight polyethylene (UHMWPE) were prepared. Metal vapor synthesis was used to produce mono- and bimetallic nanoparticles. It was shown that organosilicon nanogel effectively stabilizes Pt nanoparticles with an average size of 0.9 nm. Using the nanogel results in the formation of superparamagnetic Fe particles 3–5 nm in size that consist of ferromagnetic Fe⁰ core and antiferromagnetic shells of Fe oxides. It is established that using an organosilicon matrix in the formation of Pt-Fe/UHMWPE systems helps reduce the average particle size of Fe in the material from 6.5 to 4.5 nm and narrow their particle size distribution. The composition, magnetic and electronic characteristics of the nanocomposites are studied via transmission electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, XANES, and EXAFS.     

Anisotropy of the spatial distribution of CO molecules desorbing from tungsten

The desorption of CO from an anisotropic surface of polycrystalline tungsten after different periods of annealing has been studied. Anisotropy in the spatial distribution of CO molecules in the desorbing flux was detected at early stages of annealing. Smoothing out of the surface texture during annealing recorded by means of STM resulted in the disappearance of the spatial distribution anisotropy. The results are quantitatively explained by the model of a rough surface.⁷ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 999–1002, June, 1994.The authors express their profound gratitude to Prof. V. I. Panov and his collaborators for making it possible to carry out measurements with a tunneling microscope and for their help.     

Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Synthesis and photochromism of functionalized benzothiophene-based fulgides and fulgimides

Earlier unknown fulgides and the corresponding functionalized fulgimides containing a primary amino group were obtained. Their photochromism was examined using spectroscopic methods.     

Solution Behavior of Hyperbranched Polymethylsilsesquioxane with Intramolecular Cycles

Samples of hyperbranched polymethylsilsesquioxanes were synthesized at various polycondensation times and intramolecular cycle amounts. The samples were studied in solutions in toluene and hexane. It is shown that increasing the polycondensation duration results in the growth of number of cycles and intramolecular density that correlates with changes of molecular, hydrodynamic, and optic properties.     

Approximation of Bouguer's law for describing the transmission of laser radiation by a medium with an irregular structure of the absorption spectrum in laser-probing problems

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 4, pp. 604–609, April, 1989.     

Synthesis and characterization of nonsymmetric cyclopentene-based dithienylethenes

Nonsymmetric cyclopentene-based dithienylethenes, containing both thienyl and benzothienyl units, have been synthesized for the first time, employing intramolecular McMurry reaction as a key transformation to target compounds 10 and 16. Photochromic properties of these compounds were examined in toluene and acetonitrile solutions, PMMA layers, solid films, and crystal phase. To explain an unprecedented single-crystalline photochromism phenomena of 10, X-ray crystallographic analysis was performed, revealing a significant influence of strong S···S interatomic interactions on the intramolecular distance between two photochemical reaction centers in the molecule. Compound 16 could be further synthetically modified in a step-by-step manner, thus serving as potential key intermediate to various complex bifunctional photochromic molecules.