Electrochemical oxidation of hexaalkyldisilanes

Electrochemical oxidation of hexaalkyldisilanes in acetonitrile follows the activation mechanism with cleavage of the Si-Si bond in the overall two-electron process. Oxidation of hexamethyldisilane occurs at a potential 1 V more positive than the standard potential of the process. The standard potential of the leaving group Me3Si+/Me3Si is negative and large in value, which determines the activation character of the whole process. © 1999 MAHK "Hayka/Interperiodica"

Electrooxidation of amino-substituted aryl chalcogenides

Electrochemical oxidation of amino- and dimethylamino-substituted aryl methyl chacogenides and diaryl dichalcogenides involves reversible electron transfer to form an unstable radical cation whose reduction current was registered by switching voltammetry. The unshared electron pair of nitrogen contributes much more into the highest occupied molecular orbital compared with those of sulfur and selenium, thus changing the nature of reaction centers participating in the electron transfer and subsequent reaction of the radical cations so that amino-substituted aryl chalcogenides no longer fit linear free-enegry relationships for aryl chalcogenide reaction series. © 1999 MAHK "Hayka/Interperiodica"

Stepwise and dissociative mechanisms of the electron transfer in electrochemical reactions involving organosilicon compounds: Molecular-thermodynamic approach

Electrochemical reduction of organochlorosilanes and oxidation of hexaorganodisilanes may occur via dissociative and stepwise mechanisms, the choice between which is determined by the balance between fundamental structural parameters of elementoorganic molecules. The formation of radical anions of silyl-substituted chloromethane in the conditions of an electrochemical experiment is shown. The formation is due to α-silicon stabilization of the intermediate during the electron transfer. The role of conjugation and hyperconjugation in the organosilicon compounds' reactivity is analyzed

Electrochemical oxidation of aryldisilanes

Oxidation of disilanes containing at least one aromatic substituent at the silicon atom involves reversible electron transfer with formation of radical cations of different stabilities. The subsequent transformations of the radical cations are governed by the possibility of charge delocalization over the developed HOMO and the presence of a good leaving group. Two nitroaryl fragments in the disilane molecule destabilize this orbital, so that for bis(p-nitrophenyl)tetramethyldisilane the dissociative electron transfer becomes energetically preferable over the step process, and the reaction involves no radical-cation intermediate

Electrochemical Oxidation of Benzylsilanes

Electrochemical oxidation of substituted trialkylbenzylsilanes follows the ECE scheme including reversible electron transfer and formation of a short-lived radical cation, which can be detected for methoxybenzylsilanes at high sweep rates. In terms of the three-parameter model of the electrochemical reactivity of benzylsilanes, the inductive effect of alkyl substituents at the silicon on the rate of fragmentation of the radical cation is stronger than on the energy of the highest occupied molecular orbital, which results in the inversed influence on the effective oxidation potential

Reduction of Nitrogen Oxides Emissions from a Coal-Fired Boiler Unit

During combustion of fossil fuels a large amount of harmful substances are discharged into the atmospheres of cities by industrial heating boiler houses. The most harmful substances among them are nitrogen oxides. The paper presents one of the most effective technological solutions for suppressing nitrogen oxides; it is arrangement of circulation process with additional mounting of the nozzle directed into the bottom of the ash hopper. When brown high-moisture coals are burnt in the medium power boilers, generally fuel nitrogen oxides are produced. It is possible to reduce their production by two ways: lowering the temperature in the core of the torch or decreasing the excess-air factor in the boiler furnace. Proposed solution includes the arrangement of burning process with additional nozzle installed in the lower part of the ash hopper. Air supply from these nozzles creates vortex involving large unburned fuel particles in multiple circulations. Thereby time of their staying in the combustion zone is prolonging. The findings describe the results of the proposed solution; and recommendations for the use of this technological method are given for other boilers

Electrosynthesis of tetraethylsilane from elemental silicon

Electrolysis of alkylation reagents at silicon-containing electrodes results in alkylsilanes in both cathodic and anodic processes. A mechanism for the reaction is proposed. © 1995, Plenum Publishing Corporation. All rights reserved

ИСПОЛЬЗОВАНИЕ ИНФОРМАТИВНЫХ ГРУПП АКУСТИЧЕСКИХ СИГНАЛОВ ДЛЯ ДИАГНОСТИКИ ЭЛЕКТРОТЕХНИЧЕСКОГО ОБОРУДОВАНИЯ

The algorithm for separation the informative groups from acoustic signal is presented. Separation acts by means the periodic component and the amplitude. There are following informative groups: 1) silence; 2) noise; 3) tones; 4) pulse signals. The algorithm used segment, i.e. interval, and stream, i.e. point processing of sampled acoustic signals using the adaptation of algorithm to the signals. Application of the algorithm to a normalized to "1" signal with stationary intervals of 30 ms and fundamental harmonics at frequencies of 50 - 2000 Hz demonstrated the quantity of correct signal separation better than 91%. This quantity is retained for a wide range of signals.Предложен алгоритм распределения акустических сигналов на информативные группы по наличию периодической составляющей и величине амплитуды. Выделяются следующие информативные группы: 1)тишина; 2) шумовые; 3) тональные; 4) импульсные сигналы. В алгоритме использована сегментная, т.е. интервальная, и потоковая, т.е. поотсчетная обработка дискретизированного акустического сигнала, с использованием адаптации алгоритма к обрабатываемому сигналу. Применение алгоритма к нормированному на «1» сигналу с интервалом стационарности 30 мс и основными гармониками с частотами 50-2000 Гц продемонстрировало больше 91% правильно классифицированных фрагментов сигнала. Количество правильно классифицированных фрагментов сохраняется для широкого круга сигналов.Запропонований алгоритм розподілу акустичних сигналів на інформативні групи по наявності періодичної складової і величині амплітуди. Виділяються наступні інформативні групи: 1)тишина; 2) шумові; 3) тональні; 4) імпульсні сигнали. У алгоритмі використана сегментна, тобто інтервальна, і потокова, тобто поотсчетная обробка акустичного сигналу, що дискретизує, з використанням адаптації алгоритму до оброблюваного сигналу.Застосування алгоритму до нормованого на «1» сигналу з інтервалом стаціонарності 30 мс і основними гармоніками з частотами 50.2000 Гц продемонструвало більше 91% правильно класифікованих фрагментів сигналу. Кількість правильно класифікованих фрагментів зберігається для широкого круга сигналів

Assessment of Central Siberia Forest Ecosystems Sustainability to Forest Fires: Academic Research Outcomes

AbstractThe majority of negative consequences caused by extreme and natural hazards are qualified as weather and climate-related emergency situations. Programs and measures developed to reduce climate risks for economics should be based on scientific background, R&D projects and ongoing monitoring. Fire has always been remained as the main natural factor devastating forest ecosystems and outlining the status and resource potential of boreal forests. Extremely drought – afflicted hot summer and dry cold winter trigger the risks and consequences of forest fires thus affecting wildlife biodiversity and forest ecosystems performance in terms of СО2 accumulation from the atmosphere. Multifunctional and sustainable forest management in extreme natural conditions should be initiated on reliable (scientifically-proven) evaluation of ecological and resource potential of the forests with economically-effective approach developed to enhance sustainability of ecosystems to fires and insect invasion

Estimation of operating modes of the self-excited current inverter with use SFI-wavelet transformation

Abstract: Application of the SFI-wavelet transformation for fault isolation in self-excited current inverter consider in this paper. Definition of the fault type based on the analysis of current and voltage spectrum constructed with the use of SFI-wavelet transformation