Modeling of phase volume diffractive gratings, part 1: transmitting sinusoidal uniform gratings

A detailed model of the diffraction of plane and Gaussian beams on plane uniform phase Bragg gratings based on Kogelnik\u27s theory of coupled waves is presented. The model describes transmitting gratings with arbitrary orientation in a plane-parallel plate taking into account spectral width and angular divergence of laser beams along with material dispersion of a photosensitive medium. The model results are compared with experimental data for high- efficiency Bragg gratings in a photothermorefractive (PTR) glass

Heteronuclear Palladium and Tin Complexes

Equilibrium states in solutions containing palladium(II) and tin(II) chlorides widely used as catalytic systems are studied. The intricate and labile character of heteronuclear palladium and tin complexes formed in these solutions is noted. In these complexes, palladium and tin are involved in direct or indirect metal-metal bonds, and they can be in different oxidation states. The nature of the metal-metal bond and the metal oxidation state significantly influence the redox properties and catalytic activity of these complexes

Prooxidant-Antioxidant State of the Organism during Oxidative Stress and Correction of the L-Arginine-NO System

lipid peroxidation; antioxidant system; lipopolysaccharide; nitric oxideThe prooxidant-antioxidant balance in rats with oxidative stress was studied during correction of the L-arginine-NO system. Oxidative stress was induced by intravenous injection of E. coli lipopolysaccharide. Under conditions of oxidative stress the prooxi-dant-antioxidant imbalance was least pronounced during selective correction of the L-arginine-NO system. L-Arginine and nonselective NO synthase inhibitor had little protective effect

Multinuclear, heteronuclear, and heterovalent complexes in solutions

The results of investigations on the multinuclear 3d-metal compounds in solutions are generalized. The conditions for their formation, the stability, properties, composition, and interaction of the unpaired electrons of the metal centers are discussed. Interrelation between the magnetic properties, composition, and structure of the multinuclear complexes of paramagnetic ions is analyzed. © 1998 MAEe cyrillic signK Hayκa/Interperiodica Publishing

ТЕХНОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ОСВОЕНИЯ МЕСТОРОЖДЕНИЙ ТВЕРДЫХ ПОЛЕЗНЫХ ИСКОПАЕМЫХ С ИСПОЛЬЗОВАНИЕМ ШАРНИРНО-СОЧЛЕНЕННЫХ САМОСВАЛОВ

The paper provides an analysis for production of four-wheel drive dump trucks with an articulated frame and it also describes a practical experience pertaining to operation of dump trucks as mining automotive transport. Technical characteristics for some models of articulated dump trucks manufactured in Russia and Belarus are presented in the paper. The paper gives examples for transportation of run-of-mine ore at enterprises of Russia and abroad. The attention has been focused on specific features concerning organizational, technological and design decision making while introducing and promoting articulated dump trucks. It has been established that articulated dump trucks make it possible to improve an efficiency of mine development during construction period and when ore mining and processing enterprises are put into operation especially in geographically remote and inaccessible areas. The paper proposes technological solutions allowing to expand the scope of articulated dump truck application at mining enterprises while using them for quarry development excavating deep deposits of solid minerals. It has been revealed that reduction in overburden volume can be achieved by transition from a certain depth to lower capacity dump trucks or special dump trucks operating on elevated slopes of roads. The paper shows that one of perspective directions for development of mining technology on kimberlite deposits is an opening of lower quarry horizons by peripheral road tunnels of spiral shape while using articulated dump trucks. The presented technological solutions require further research and design consideration and study and they will allow to ensure resource efficiency and safety of surface mining while extracting minerals at previously uneconomic ore deposits. In order to realize an import substitution program for four-wheel drive dump trucks with an articulated frame it is necessary to carry out marketing research on potential market for machines of this class required for open-pit mining in order to justify prospects for provision of the Russian production market.Проведен анализ производства полноприводных самосвалов с шарнирно-сочлененной рамой и практического опыта эксплуатации их в качестве карьерного автотранспорта. Представлены технические характеристики некоторых моделей шарнирно-сочлененных самосвалов российского и белорусского производства. Приведены примеры транспортирования горной массы на предприятиях России и за рубежом. Акцентировано внимание на особенностях принятия организационно-технологических и проектных решений при внедрении шарнирно-сочлененных самосвалов. Установлено, что шарнирно-сочлененные самосвалы позволяют повысить эффективность отработки месторождения на стадии строительства и ввода в эксплуатацию горно-обогатительных комбинатов, особенно в территориально удаленных и труднодоступных районах. Предложены технологические решения, позволяющие расширить сферу применения шарнирно-сочлененных самосвалов на горнодобывающих предприятиях путем использования их при доработке карьеров, разрабатывающих глубокозалегающие месторождения твердых полезных ископаемых. Выявлено, что сокращение объемов вскрыши можно обеспечить путем перехода с определенной глубины на автосамосвалы меньшей грузоподъемности или на специализированные автосамосвалы, работающие на повышенных уклонах автодорог. Показано, что одним из перспективных направлений развития технологии отработки кимберлитовых месторождений с использованием шарнирно-сочлененных самосвалов является вскрытие нижних горизонтов карьера законтурными автомобильными тоннелями спиральной формы. Представленные технологические решения требуют дальнейшей научно-проектной проработки и позволят обеспечить ресурсосбережение и безопасность открытых горных работ при извлечении руд ранее нерентабельных месторождений. Для реализации программы импортозамещения полноприводных самосвалов с шарнирно-сочлененной рамой необходимы маркетинговые исследования по изучению возможного рынка потребления машин данного класса на открытых горных работах с целью обоснования перспективы обеспечения российского рынка производства

Coupled-wave analysis of apodized volume gratings

This work presents the use of longitudinal refractive index modulation (apodization) in photosensitive glass for improved sidelobe suppression in volume holographic optical elements. We develop a numerical model for both uniform and apodized volume holograms based on rigorous coupled-wave analysis. We validate the model by comparison with a transmissive 1.55-mum uniform volume grating in photothermorefractive glass. We then apply our numerical model to calculate the spectral response of apodized gratings. The numerical results demonstrate that apodization of the refractive index modulation envelope improves spectral selectivity and reduces first and second-order side-lobe peaks by up to 33 and 65 dB, respectively. We suggest a method for creating apodization in volume holograms with approximately Gaussian spatial refractive index profile