Characterization and Growth Mechanism of Nickel Nanowires Resulting from Reduction of Nickel Formate in Polyol Medium

Nickel linear nanostructures were synthesized by reduction of nickel formate with hydrazine hydrate in ethylene glycol medium in the absence of any surfactants or capping agents for direction of the particles growth. The effect of the synthesis conditions such as temperature, reduction time, type of polyol, and nickel formate concentration on the reduction products was studied. The size and morphology of the nickel nanowires were characterized by X-ray diffraction, scanning, and transmission electron microscopy. It was shown that the nickel nanocrystallites were wire-shaped with a face-center-cubic phase. Ethylene glycol was found to play a crucial role in the formation of the nickel nanowires. The possible growth processes of the wire-shaped particles taking place at 110 and 130°C are discussed. It was shown that, under certain synthesis conditions, nickel nanowires grow on the surface of the crystals of the solid intermediate of nickel with hydrazine hydrate

Conductive inks for inkjet printing based on composition of nanoparticles and organic silver salt

In this article, conductive inks for inkjet printing with high content of silver nanoparticles with the addition of organic silver salt and polymer additives are developed and investigated. Silver nanoparticles are shown to be stably dispersed in a solvent and the presence of a silver salt and a polymeric surfactant ensures the viscosity necessary for printing. A print of test images is performed using a laboratory inkjet printer equipped with an industrial small-droplet printhead followed by annealing of printed patterns at 150–250°C, and their structural and electrical properties are investigated. Simultaneous presence of polymer additives and silver salt is found to influence the structure of the forming conductive layer and the conducting properties

Spin relaxation of localized electrons in n-type semiconductors

The mechanisms that determine spin relaxation times of localized electrons in impurity bands of n-type semiconductors are considered theoretically and compared with available experimental data. The relaxation time of the non-equilibrium angular momentum is shown to be limited either by hyperfine interaction, or by spin-orbit interaction in course of exchange-induced spin diffusion. The energy relaxation time in the spin system is governed by phonon-assisted hops within pairs of donors with an optimal distance of about 4 Bohr radii. The spin correlation time of the donor-bound electron is determined either by exchange interaction with other localized electrons, or by spin-flip scattering of free conduction-band electrons. A possibility of optical cooling of the spin system of localized electrons is discussed.Comment: Submitted to the special issue "Optical Orientation", Semiconductor Science and Technolog

Spin relaxation in low-dimensional systems

We review some of the newest findings on the spin dynamics of carriers and excitons in GaAs/GaAlAs quantum wells. In intrinsic wells, where the optical properties are dominated by excitonic effects, we show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped wells, the two spin components of an optically created two-dimensional electron gas are well described by Fermi-Dirac distributions with a common temperature but different chemical potentials. The rate of the spin depolarization of the electron gas is found to be independent of the mean electron kinetic energy but accelerated by thermal spreading of the carriers.Comment: 1 PDF file, 13 eps figures, Proceedings of the 1998 International Workshop on Nanophysics and Electronics (NPE-98)- Lecce (Italy

Current Problems of Environmental Safety in the Republic of Tatarstan

Важным направлением в развивающемся мире является сохранение окружающей среды. Существует множество способом контроля и мониторинга состояния природы. В данной статье мы рассмотрим основные проблемы и методы обеспечения экологической безопасности в Республике Татарстан на примере таких городов как Набережные Челны, Альметьевск и Нижнекамск.An important direction in the developing world is the preservation of the environment. There are many ways to control and monitor the state of nature. In this article we will consider the main problems and methods of ensuring environmental safety in the Republic of Tatarstan on the example of cities such as Naberezhnye Chelny, Almetyevsk and Nizhnekamsk

МОНИТОРИНГ ИЗМЕНЕНИЙ НАПРЯЖЕННО-ДЕФОРМИРОВАННОГО СОСТОЯНИЯ ГЕОСРЕДЫ В РАЙОНЕ ПЕТРОПАВЛОВСКОГО ГЕОДИНАМИЧЕСКОГО ПОЛИГОНА ПО ДАННЫМ КОМПЛЕКСНЫХ СКВАЖИННЫХ И GPS-ИЗМЕРЕНИЙ НА АКТИВНОЙ ФАЗЕ ПОДГОТОВКИ ЖУПАНОВСКОГО ЗЕМЛЕТРЯСЕНИЯ (30.01.2016; Mw=7.2)

The paper presents the results of comparative analysis of the data regarding the multi-instrumental borehole monitoring data of changes in the geoenvironment stress-strain state and GPS data obtained in the time vicinity of the close strong Zhupanovsky earthquake. The purpose this study was to assess the feasibility of using GPS measurements on routine basis for effective monitoring of strong Kamchatka earthquakes in the area of Petropavlovsk-Kamchatsky. The Zhupanovsky earthquake active phase was chosen as a "test" time interval for comparing GPS and borehole monitoring data. This earthquake has been the strongest seismic event since 2000 in terms of the ratio of the earthquake focus length to the hypocentral distance. The time series borehole electromagnetic and geoacoustic data were compared with the dilatation series reflecting the relative changes in the area of a triangle composed of Kamchatka GPS observation network located in the Petropavlovsk geodynamic testing site. The analysis indicates a high degree of consistency in these time series. GPS data obtained during the active phase of the earthquake preparation is agree with the results of mathematical modeling expected values of volumetric strain on the daylight surface on the eve of the earthquake. A joint analysis of borehole and GPS data made it possible to specify the time limits for the stages of change in the stress-strain state of geoenvironment and to resolve ambiguity of interpretation of the electromagnetic and geoacoustic borehole measurement results at the final stage of preparing the Zhupanovsky earthquake.Приводятся результаты сравнительного анализа данных комплексного скважинного мониторинга изменений напряженно-деформированного состояния геосреды и данных GPS-измерений, полученных во временной окрестности сильного близкого Жупановского землетрясения. Целью исследований являлась оценка целесообразности привлечения на постоянной основе данных GPS-измерений для повышения эффективности системы мониторинга процессов подготовки сильных камчатских землетрясений, функционирующей в районе г. Петропавловска-Камчатского. В качестве «тестового» временного интервала для сравнения данных GPS-измерений с результатами комплексного скважинного мониторинга был выбран интервал активной фазы подготовки Жупановского землетрясения – самого сильного с 2000 г. сейсмического события по величине отношения длины очага землетрясения к гипоцентральному расстоянию. В ходе анализа временные ряды данных скважинных электромагнитных и геоакустических измерений в районе Петропавловского геодинамического полигона сравнивались с рядом дилатации, данные которого отражают относительные изменения площади треугольника, составленного из пунктов Камчатской сети GPS-измерений, расположенных в том же районе. Результаты анализа свидетельствуют о высокой степени согласованности указанных временных рядов. Значимость исходных данных GPS-измерений, полученных на интервале активной фазы подготовки землетрясения, подтверждается их совпадением с оценками ожидаемых величин объемных деформаций на дневной поверхности накануне момента землетрясения, полученными по результатам математического моделирования. Совместный анализ данных скважинных и GPS-измерений позволил уточнить временные границы стадий изменений напряженно-деформированного состояния геосреды, а также устранить неоднозначность в интерпретации результатов электромагнитных и геоакустических скважинных измерений на заключительных стадиях подготовки Жупановского землетрясения

PECULIAR FEATURES OF PTCA IN CORONARY PATIENTS WITH BIFURCATION LESIONS

The aim of the study was to analyse the clinical and angiographic results of bifurcational coronary balloon angioplasty and/or stenting depending on procedural variables and treatment method. The study included 56 patients with stable angina presenting bifurcational coronary lesions. The stent was implanted in main vessel in 32 patients. 24 patients were treated without stenting. Side branch angioplasty was performed in 16 stented and in 12 nonstented segments. All stenting procedures were performed using three ways: 1) so called «standard» manner without side branch protection during stenting, 2) elsewhere well described «jailed guidewire» technique and 3) hand9mounted two9balloons system proposed by K. Aroney. In 28 cases of successful bifurcational angioplasty an immediate clinical benefit was achieved. Among patients in whom side branch dilatation attempts have failed, 4 were finally free of symptoms, 6 have still demonstrated objective ischemic signs despite of considerable improvement in terms of angina functional class and 3 patients showed no clinical benefit. Conclusion: intact side branch ostium arising from main branch stenosis becomes compromised in large number of cases. 30% of side branch angioplasty attempts fail, of which the majority fall on stented main branch cases. Among types of bifurcation treatment, Aroney’s method showed the least effectiveness. Incomplete bifurcation reconstruction substantially decrease the clinical benefit in these patients. Key words: bifurcation lesion, coronary angioplasty, coronary stenting