Scattering of high-frequency waves by surfaces in continuous media with allowance for rereflections

This study is devoted to the development of the ray theory of diffraction in application to arbitrary (nonconvex) smooth obstacles in the scalar case. A three-dimensional problem is considered. An asymptotic method of estimating the diffraction integrals is described. The method is based on the multidimensional stationary phase approach. The diffraction integrals are obtained on the basis of the generalization of the Kirchhoff physical theory of diffraction. Explicit expressions are derived for the pressure in the reflected wave in the cases of its single and double reflections.     

Annihilation of positrons in hydrogen-saturated titanium

The effect of atomic hydrogen on the electronic structure of α-titanium samples is studied using the electron-positron annihilation methods. It is shown that different states of hydrogen atoms are manifested in different ways in the positron lifetime distribution spectrum. The results of theoretical calculations of the first component of the positron lifetime are in accord with the obtained experimental data.     

Positron states in KCL crystals before and after radiation exposure

The features of positron annihilation in KCl crystals before and after radiation exposure is investigated. A significant increase in the efficiency of the ortho-vapor process of positronium state conversion is detected. A model is proposed for taking part in the ortho-vapor conversion of conduction electrons drawn into the conduction band by a positron field that affords a qualitative interpretation of the results obtained and permits values of the electron concentration in a spur to be obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 98–102, July, 1988.     

Cyclic deformation of aluminium and its alloys

The formation of slip bands is the main mechanism of cyclic deformation in pure Al. Their density, orientation and heights in polycrystalline Al were investigated during cycling. Types, sizes and densities of precipitates are responsible for the mode of cyclic deformation in AlCu4 pure alloy. In technical Al alloys intermetallic phases have detrimental effects on deformation homogeneity and largely govern the fatigue mechanism of the material and especially microcrack initiation.     

含氧光敏引发体系的研究——Ⅵ.二苯酮/三乙胺体系引发光聚合过程中的再次引发效应

过去,作者曾发表了多种光敏引发体系引发烯类单体光聚合的工作,在研究2,2-二甲氧基苯乙酮在氧存在下引发甲基丙烯酸甲酯光聚合时,结合在聚合物链端的引发剂碎片具有光化学活性,在光聚合反应中产生高分子自由基,发生再次聚合,出现高分子量     

Flexible ureasil hybrids with tailored optical properties through doping with metal nanoparticles

Hybrid organic-inorganic nanocomposites containing uniform distributions of metal nanoparticles have been prepared by mixing a preformed nanoparticle colloid with the precursors of a ureasil, prior to the sol-gel transition. These nanocomposites possess not only high optical quality and optical features dictated by the size and shape of the nanoparticle dopants but also a high degree of flexibility, which can largely enhance the range of applications in practical devices. The deposition of a uniform silica shell on the nanoparticle surface prior to the sol-gel transition was found to be required to maintain the colloidal stability during the process and, thus, to retain the optical properties in the final nanocomposite material. This method can be readily extended to other materials, such as semiconductor and magnetic nanoparticles.     

Reaction of acetylferrocene with dimethylformamide dimethyl acetal and some transformations of the reaction product

1-Dimethylamino-3-ferrocenyl-3-oxoprop-1-ene was synthesized by the reaction of acetylferrocene with dimethylformamide dimethyl acetal. Its reactivity in the reactions with mononucleophilic (sodium salts of phenol, thiophenol, benzenesulfinate, diethylphosphorous acid) and binucleophilic reagents (hydrazine hydrate, hydroxylamine, amidines, 1,2-diaminobenzene, 2-aminophenol, 2-aminothiophenol) and methyl iodide was studied. As a result, we obtained new ferrocene-containing α-keto-unsaturated compounds and heterocycles of pyrazole, isoxazole, pyrimidine, and benzazepine series. In the reaction with CH₃I formed ferrocenoylacetylene which in the presence of dicarbonyl-bis(triphenylphosphine)nickel catalyst easily trimerized to give a mixture of 1,2,4- and 1,3,5-triferrocenoylbenzene.     

Synthesis of N-arylmethyl-3-azabicyclo[3.3.1]nonan-9-ones

Russian Journal of Organic Chemistry -     

Reaction of 2- and 4-(Acetoxymercuriomethyl)-1-phenylquinolinium Perchlorates with Sodium Ethoxide

Russian Journal of Organic Chemistry -