КОЛЛИНЕАРНОЕ АКУСТООПТИЧЕСКОЕ ВЗАИМОДЕЙСТВИЕ БЕССЕЛЕВЫХ СВЕТОВЫХ ПУЧКОВ В ДВУОСНЫХ КРИСТАЛЛАХ

The collinear acousto-optic transformation of Bessel light beams into two ring beams of internal conical refraction has been considered. Using the Fourier transformation method, the expressions for power flows of ring diffracted beams of internal conical refraction are found in closed form. For a potassium biftalate crystal, the dependence of the diffraction efficiency on the ultrasound intensity and interaction durability is calculated. Based on this interaction, the creation of collinear convertible AO filters with a narrow width of a transmission band of about 0.1 is proposed. Рассмотрено коллинеарное акустооптическое преобразование бесселевых световых пучков в два кольцевых пучка внутренней конической рефракции. С использованием метода преобразования Фурье найдены выражения для потоков мощности дифрагированных кольцевых пучков внутренней конической рефракции в замкнутой форме. Для кристалла бифталата калия произведен расчет зависимости эффективности дифракции от интенсивности ультразвука и длины взаимодействия. На основе данного взаимодействия предложено создание коллинеарных перестраиваемых АО фильтров с узкой шириной полосы пропускания, достигающей 0,1 Å.

Статистическая модель гомодинного акустооптического спектроанализатора

Introduction. Acousto-optic spectrum analyzers interferometric schemes have been developed to increase dynamic range. It was assumed that dynamic range, expressed in dB, would double. An expected increase was not achieved yet.Aim. To analyze the homodyne acousto-optic spectrum analyzer noise characteristics, to estimate the signal-tonoise ratio and the dynamic range.Materials and methods. A mathematical model was compiled which took into account the need to form quadrature components to obtain an amplitude spectrum of an input signal, shot noise and readout noise.Results. An interferometric scheme did not allow to achieve dynamic range doubling compared to an acoustooptical power spectrum analyzer. The dynamic range increase was less than 1.35 dB. Constant illumination led to a significant increase of the spectrum analyzer self-noise due to shot noise, compared to which thermal noise and readout noise became insignificant. The spurious-free dynamic range estimation expression was obtained. It was prior determined by acousto-optic interaction nonlinearity. With typical analyzer blocks parameters the spurious-free dynamic range covered a single-signal dynamic range. Signal-to-noise ratio estimation expression was presented.Conclusion. The homodyne acousto-optic spectrum analyzer single-signal dynamic range is determined primarily by the photosensor saturation charge. One needs to optimize their relation by taking into account light source power, acousto-optical modulator diffraction efficiency and photosensor saturation charge. Presented noise model gives more accurate estimation of the dynamic range with an error of 1 dB.Введение. Интерференционные схемы акустооптических спектроанализаторов были разработаны для увеличения динамического диапазона за счет формирования амплитудного спектра исследуемого сигнала вместо спектра мощности. Предполагалось, что это позволит удвоить динамический диапазон, выраженный в децибелах. В настоящей статье показано, что это теоретически невозможно и ожидания, связанные с переходом к интерференционным схемам, завышены.Цель работы. Анализ шумовых характеристик гомодинного акустооптического спектроанализатора (ГАОСА), оценка отношения сигнал/шум и динамического диапазона на выходе устройства.Материалы и методы. Представлена математическая модель описания работы ГАОСА с учетом формирования квадратурных компонентов для получения амплитудного спектра входного сигнала. Модель учитывает дробовые шумы и шумы, возникающие при считывании заряда.Результаты. Показано, что использование интерферометрической схемы не позволяет достичь двукратного выигрыша (при измерении в децибелах) в динамическом диапазоне по сравнению с простой схемой акустооптического спектроанализатора с пространственным интегрированием. Коэффициент увеличения динамического диапазона составляет не более 1.35 дБ. С учетом специфики работы акустооптических устройств получено выражение для оценки динамического диапазона спектроанализатора по интермодуляционным искажениям третьего порядка. Определяющим фактором при этом является нелинейность акустооптического взаимодействия. Показано, что при типовых параметрах узлов устройства динамический диапазон по интермодуляционным искажениям включает в себя односигнальный динамический диапазон. Представлено выражение для оценки отношения сигнал/шум.Заключение. Односигнальный динамический диапазон ГАОСА определяется в первую очередь уровнем заряда насыщения фотоприемника. При макетировании необходимо решать вопрос оптимального соотношения обоих параметров с учетом мощности источника излучения, эффективности дифракции в акустооптическом модуляторе и заряда насыщения фотоприемника. Представленная статистическая модель ГАОСА с фотоприемником с накоплением дает более точную оценку динамического диапазона с ошибкой в 1 дБ

Получение износостойких материалов методом СВС-литья с применением центробежных сил

The paper is devoted to the problem of producing hard, wear-resistant materials by SHS-casting using centrifugal forces. We have developed a device for centrifugal SHS casting and initial compositions of the reactive iron-base charge. A technology for producing coatings, materials and final products with a non-uniform distribution of strengthening particles over the specimen volume has been developed and tested in industrial conditions. The microstructure and phase composition of the synthesized material with a non-uniform distribution of reinforcing particles is studied. The synthesized material implements the Charpy principle: dispersed hard carbide particles are distributed in a relatively soft matrix, which ensures high wear resistance. By means of SHS casting, billets were obtained for producing a measurement instrument, namely a plug-type gauge, which successfully passed industrial tests at OJSC “VIZAS”. The tests shown that the hardness of all synthesized samples was in the range from 63 to 68 HRC and the number of measurements per 1 micron of wear on a diameter of15 mm was 2500 to 2700. Hence, the developed method made it possible to significantly increase the service life of the measuring tool: by a factor of 1.5 to 2.Работа посвящена проблеме получения твердых износостойких материалов методом СВС-литья с применением центробежных сил. Разработано устройство для центробежного СВС-литья и составы исходной реакционной шихты на основе железа. Создана и реализована на практике технология получения покрытий, материалов и конечных изделий с неоднородным распределением упрочняющих частиц по объему образца. Исследована микроструктура и фазовый состав синтезированного материала с неоднородным распределением упрочняющих частиц. В синтезированном материале реализован принцип Шарпи: в относительно мягкой основе распределены твердые дисперсные частицы карбидов, что обеспечивает высокую износостойкость. Методом СВС-литья были изготовлены заготовки для измерительных калибров типа «пробка», которые успешно прошли производственные испытания на ОАО «ВИЗАС». Испытания показали, что твердость всех синтезированных образцов находится в интервале 63–68 HRC; количество измерений на 1 мкм износа на диаметре 15 мм составляет 2500–2700. Таким образом, использование разработанного метода позволило существенно (в 1,5–2 раза) повысить срок службы измерительного инструмента

ПРЕОБРАЗОВАНИЕ ДВУМЕРНЫХ КВАЗИБЕЗДИФРАКЦИОННЫХ СВЕТОВЫХ ПУЧКОВ ПРИ АКУСТООПТИЧЕСКОМ ВЗАИМОДЕЙСТВИИ В ОДНООСНЫХ КРИСТАЛЛАХ

Participants of shape transformation of two-dimensional nearly absent-diffracted (cosine-supergaussian) light beams under Braggs diffraction by ultrasonic waves in iniaxial gyrotropic crystals are investigated. It is shown that at diffraction of such light beams travelling in the vicinity of the crystal optical axis on a slow shear ultrasonic wave under the conditions of a strong acoustooptical interaction, light beams experience a significant deformation of the intensity distribution in the beam cross section. At large widths of a supergaussian component of an incident beam, the shape of a diffracted beam remains underchanged. It is stated that the diffraction efficiency weakly depends on the width of the supergaussian component of the cosine-supergaussian beam.Исследованы особенности преобразований формы двумерных квазибездифракционных (косинус-супергауссовых) световых пучков при брэгговской дифракции на ультразвуковых волнах в одноосных гиротропных кристаллах. Показано, что при дифракции таких световых пучков, распространяющихся вблизи оптической оси кристалла на медленной сдвиговой УЗ-волне в условиях сильного акустооптического взаимодействия, дифрагированные световые пучки испытывают существенную деформацию распределения интенсивности в поперечном сечении пучка. При больших ширинах супергауссовой составляющей падающего пучка форма дифрагированного пучка остается неизменной. Установлено, что эффективность дифракции слабо зависит от ширины супергауссовой составляющей косинус-супергауссового пучка

Кинетика формирования наночастиц серебра в среде полиэтиленгликоля 400

Kinetics of silver nanoparticle formation in the reaction between silver nitrate and (poly)ethylene glycol 400 produced by Aldrich, BASF, BioChemica and Fluka has been studied. It has been found that different polyethylene glycol samples show significant variations of behavior in this process. The initial rate of (poly)ethylene glycol reaction with silver ions has been found to vary broadly when (poly)ethylene glycol samples of different manufacturers are used. It has been shown that kinetic curves of the (poly)ethylene glycols produced by Aldrich, BASF and Fluka can be fitted by Boltzmann sigma function while the kinetic curve of (poly)ethylene glycol produced by BioChemica can be fitted by reversed exponential growth equation.Проведено исследование кинетических особенностей образования наночастиц серебра при взаимодействии нитрата серебра с полиэтиленгликолем 400 различных производителей (Aldrich, BASF, BioChemica и Fluka), поведение образцов которого существенно различается в данном процессе. Выявлены отличия в начальной скорости процесса взаимодействия полиэтиленгликолей различных производителей с ионами серебра. Установлено, что для аппроксимации кинетических кривых для полиэтиленгликолей производства Aldrich, BASF и Fluka наилучшие результаты достигаются при использовании сигмоидальной функции Больцмана, а для полиэтиленгликоля производства BioChemica - уравнения обратного экспоненциального роста

Reduction in Phencyclidine Induced Sensorimotor Gating Deficits in the Rat Following Increased System Xc − Activity in the Medial Prefrontal Cortex

Rationale: Aspects of schizophrenia, including deficits in sensorimotor gating, have been linked to glutamate dysfunction and/or oxidative stress in the prefrontal cortex. System xc −, a cystine–glutamate antiporter, is a poorly understood mechanism that contributes to both cellular antioxidant capacity and glutamate homeostasis. Objectives: Our goal was to determine whether increased system xc − activity within the prefrontal cortex would normalize a rodent measure of sensorimotor gating. Methods: In situ hybridization was used to map messenger RNA (mRNA) expression of xCT, the active subunit of system xc −, in the prefrontal cortex. Prepulse inhibition was used to measure sensorimotor gating; deficits in prepulse inhibition were produced using phencyclidine (0.3–3 mg/kg, sc). N-Acetylcysteine (10–100 μM) and the system xc − inhibitor (S)-4-carboxyphenylglycine (CPG, 0.5 μM) were used to increase and decrease system xc − activity, respectively. The uptake of 14C-cystine into tissue punches obtained from the prefrontal cortex was used to assay system xc − activity. Results: The expression of xCT mRNA in the prefrontal cortex was most prominent in a lateral band spanning primarily the prelimbic cortex. Although phencyclidine did not alter the uptake of 14C-cystine in prefrontal cortical tissue punches, intraprefrontal cortical infusion of N-acetylcysteine (10–100 μM) significantly reduced phencyclidine- (1.5 mg/kg, sc) induced deficits in prepulse inhibition. N-Acetylcysteine was without effect when coinfused with CPG (0.5 μM), indicating an involvement of system xc −. Conclusions: These results indicate that phencyclidine disrupts sensorimotor gating through system xc − independent mechanisms, but that increasing cystine–glutamate exchange in the prefrontal cortex is sufficient to reduce behavioral deficits produced by phencyclidine

Gas-Cooled Fast Reactor (GFR) FY05 Annual Report

The gas-cooled fast reactor (GFR) was chosen as one of the Generation IV nuclear reactor systems to be developed based on its excellent potential for sustainability through reduction of the volume and radio toxicity of both its own fuel and other spent nuclear fuel, and for extending/utilizing uranium resources orders of magnitude beyond what the current open fuel cycle can realize. In addition, energy conversion at high thermal efficiency is possible with the current designs being considered, thus increasing the economic benefit of the GFR. However, research and development challenges include the ability to use passive decay heat removal systems during accident conditions, survivability of fuels and in-core materials under extreme temperatures and radiation, and economical and efficient fuel cycle processes. Nevertheless, the GFR was chosen as one of only six Generation IV systems to be pursued based on its ability to meet the Generation IV goals in sustainability, economics, safety and reliability, proliferation resistance and physical protection. Current research and development on the Gas-Cooled Fast Reactor (GFR) has focused on the design of safety systems that will remove the decay heat during accident conditions, ion irradiations of candidate ceramic materials, joining studies of oxide dispersion strengthened alloys; and within the Advanced Fuel Cycle Initiative (AFCI) the fabrication of carbide fuels and ceramic fuel matrix materials, development of non-halide precursor low density and high density ceramic coatings, and neutron irradiation of candidate ceramic fuel matrix and metallic materials. The vast majority of this work has focused on the reference design for the GFR: a helium-cooled, direct power conversion system that will operate with on outlet temperature of 850 C at 7 MPa. In addition to the work being performed in the United States, seven international partners under the Generation IV International Forum (GIF) have identified their interest in participating in research related to the development of the GFR. These are Euratom (European Commission), France, Japan, South Africa, South Korea, Switzerland, and the United Kingdom. Of these, Euratom (including the United Kingdom and Switzerland), France, and Japan have active research activities with respect to the GFR. The research includes GFR design and safety, and fuels/in-core materials/fuel cycle projects. This report outlines the current design status of the GFR, and includes work done in the areas mentioned above for this fiscal year. In addition, this report fulfills the Level 2 milestones, ''Complete annual status report on GFR reactor design'', and ''Complete annual status report on pre-conceptual GFR reactor designs'' in work package GI0401K01. GFR funding for FY05 included FY04 carryover funds, and was comprised of multiple tasks. These tasks involved a consortium of national laboratories and universities, including the Idaho National Laboratory (INL), Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), Oak Ridge National Laboratory (ORNL), Auburn University (AU), Idaho State University (ISU), and the University of Wisconsin-Madison (UW-M). The total funding for FY05 was $1000K, with FY04 carryover of$174K. The cost breakdown can be seen in Table 1

Update of EULAR recommendations for the treatment of systemic sclerosis

The aim was to update the 2009 European League against Rheumatism (EULAR) recommendations for the treatment of systemic sclerosis (SSc), with attention to new therapeutic questions. Update of the previous treatment recommendations was performed according to EULAR standard operating procedures. The task force consisted of 32 SSc clinical experts from Europe and the USA, 2 patients nominated by the pan-European patient association for SSc (Federation of European Scleroderma Associations (FESCA)), a clinical epidemiologist and 2 research fellows. All centres from the EULAR Scleroderma Trials and Research group were invited to submit and select clinical questions concerning SSc treatment using a Delphi approach. Accordingly, 46 clinical questions addressing 26 different interventions were selected for systematic literature review. The new recommendations were based on the available evidence and developed in a consensus meeting with clinical experts and patients. The procedure resulted in 16 recommendations being developed (instead of 14 in 2009) that address treatment of several SSc-related organ complications: Raynaud's phenomenon (RP), digital ulcers (DUs), pulmonary arterial hypertension (PAH), skin and lung disease, scleroderma renal crisis and gastrointestinal involvement. Compared with the 2009 recommendations, the 2016 recommendations include phosphodiesterase type 5 (PDE-5) inhibitors for the treatment of SSc-related RP and DUs, riociguat, new aspects for endothelin receptor antagonists, prostacyclin analogues and PDE-5 inhibitors for SSc-related PAH. New recommendations regarding the use of fluoxetine for SSc-related RP and haematopoietic stem cell transplantation for selected patients with rapidly progressive SSc were also added. In addition, several comments regarding other treatments addressed in clinical questions and suggestions for the SSc research agenda were formulated. These updated data-derived and consensus-derived recommendations will help rheumatologists to manage patients with SSc in an evidence-based way. These recommendations also give directions for future clinical research in SSc

The potential contribution of disruptive low-carbon innovations to 1.5 °C climate mitigation

This paper investigates the potential for consumer-facing innovations to contribute emission reductions for limiting warming to 1.5 °C. First, we show that global integrated assessment models which characterise transformation pathways consistent with 1.5 °C mitigation are limited in their ability to analyse the emergence of novelty in energy end-use. Second, we introduce concepts of disruptive innovation which can be usefully applied to the challenge of 1.5 °C mitigation. Disruptive low-carbon innovations offer novel value propositions to consumers and can transform markets for energy-related goods and services while reducing emissions. Third, we identify 99 potentially disruptive low-carbon innovations relating to mobility, food, buildings and cities, and energy supply and distribution. Examples at the fringes of current markets include car clubs, mobility-as-a-service, prefabricated high-efficiency retrofits, internet of things, and urban farming. Each of these offers an alternative to mainstream consumer practices. Fourth, we assess the potential emission reductions from subsets of these disruptive low-carbon innovations using two methods: a survey eliciting experts’ perceptions and a quantitative scaling-up of evidence from early-adopting niches to matched segments of the UK population. We conclude that disruptive low-carbon innovations which appeal to consumers can help efforts to limit warming to 1.5 °C