In-situ measurements of low energy D plasma-driven permeation through He pre-damaged W

Experiments concerning the effect of helium (He) plasma exposure on deuterium (D) plasma-driven permeation (PDP) through tungsten (W) foils in a linear plasma facility has been performed. 0.05 mm thick W foils were exposed to ~2×1020 m-2s-1 He plasma with various fluences at 883 K. After He irradiating, D permeation tests were performed for the samples and retention was also measured by high-resolution thermal desorption spectroscopy (TDS). It was observed that He pre-irradiation resulted in a significant reduction of D permeation and retention in W. Microstructure observation indicated that the surfaces of samples after He irradiation turned rough and He nanobubbles were formed near the surface. The defective structure including He nanobubbles very likely enhances D reemission and accordingly reduces the permeation and retention in He pre-irradiated W.

Reduction in DC-Drift in LiNbO3-Based Electro-Optical Modulator

This study involves the results of research on short-term and long-term DC-drifts in electro-optical modulators based on annealed proton exchange waveguides in LiNbO3 crystals after wafer pre-annealing. The relaxation time of the DC-drift of the operating point for a short-term drift is measured in minutes, and for a long-term drift it is measured in hours and days. DC-drift was measured by applying bias voltage and changing crystal temperature. The obtained results show significant impact on the stability of operating point in EO-modulators after treatment of defective structure of the near-surface layer of a LiNbO3 crystal. Treatment of the disturbed near-surface layer of a LiNbO3 crystal results in the simultaneous reduction in short-term DC-drift and increase in operation stability of electro-optical modulators during long-term measurement of temperature by activation energy calculation.

X-ray Photoelectron Spectroscopy of Surface Layers of Faceted Zinc Oxide Nanorods

The control of the nanomaterials surface’s hydrophilic properties is of interest for various applications, including optics, photocatalysis, and spintronics. In this work, techniques for designing the defective structure of the surface layers of faceted zinc oxide nanorods during sacrificial doping with iodine by hydrothermal synthesis were considered. The features of the chemical composition of the surface of the obtained layers were studied using X-ray photoelectron spectroscopy (XPS). It was found that peaks corresponding to the binding energy of iodine were not observed in the X-ray photoelectron spectra. An additional peak with a binding energy of 531.8 eV, corresponding to the oxygen of OH groups, was observed in the O 1s level spectrum for zinc oxide nanorods doped with iodine. During the heat treatment of the synthesized layers, iodine evaporates, which leads to a change in the surface composition and an increase in the oxygen content of the surface hydroxyl groups. A model has been proposed to explain the experimental results. It has been established that XPS techniques are effective for analyzing the defective surface structure of functional layers based on faceted zinc oxide nanorods.

Reduction of DC-drift in LiNbO3-based Electro-optical Modulator

This work involves results of research on short-term and long-term DC-drifts in electro-optical modulators based on annealed proton exchange waveguides in LiNbO3 crystals after wafer pre-annealing. The relaxation time of the DC-drift of the operating point for a short-term drift is minutes, and for a long-term drift, hours and days. DC-drift was measured by applying bias voltage and changing crystal temperature. Obtained results shows significant impact on stability of operating point in EO-modulators after treatment of defective structure of the near-surface layer of a LiNbO3 crystal. Treatment of the disturbed near-surface layer of a LiNbO3 crystal results in twice reduction of short-term DC-drift and increase of operation stability of electro-optical modulators during long-term measurement of temperature by activation energy calculation.

Diagnostic value of urine organic acids analysis among patients with primary mitochondrial disorders

Первичные митохондриальные заболевания (ПМЗ) - генетически и клинически гетерогенные заболевания, характеризующиеся нарушением структуры или функций системы окислительного фосфорилирования (OXPHOS), включая электрон-транспортную цепь. Несмотря на успешное применение методов секвенирования нового поколения в диагностике наследственных заболеваний в последнее десятилетие, существует ряд объективных трудностей в интерпретации результатов, особенно при обнаружении новых генов или новых вариантов нуклеотидной последовательности. Анализ биомаркеров, которые являются индикаторами нарушения функций митохондрий, является важным этапом в диагностике многих ПМЗ. Целью данной работы было проведение анализа спектра и концентраций 72 органических кислот в моче методом газовой хроматографии с масс-спектрометнией (ГХ-МС,7890А/5975С, Agilent Technologies, США) в выборке из 84 пациентов с подтвержденным молекулярно-генетическими методами диагнозом ПМЗ и оценка их диагностической значимости. Среди 84 пациентов с ПМЗ, отклонения в спектре органических кислот были выявлены в 78% (66/84) случаев. Уникальный спектр органических кислот наблюдался при митохондриальных гепатопатиях, связанных с мутациями в гене DGUOK: наравне с повышением уровня лактата, пирувата, 3-гидроксибутирата было выявлено повышение концентрации 4-гидроксифениллактата, 4-гидроксифенилпирувата. При анализе ROC-кривых было показано, что диагностическая значимость маркеров убывает в ряду: 3-гидроксибутират, лактат, пируват. При проведении оценки достоверности теста показано, что повышение концентраций пирувата и 4-гидроксифениллактата может быть принято во внимание при предположении ПМЗ у пациента. Introduction. Primary mitochondrial disorders (PMD) are a group of clinically and genetically heterogeneous group of diseases characterized by a defective structure and functions of the Oxidative Phosphorylation System (OXPHOS). Despite the advantages of the next generation sequencing, diagnosis of PMD is still challenging. There is no currently available biomarker with high specificity and sensitivity. But the level of metabolites reflecting the defective OXPHOS is needed for making of a diagnosis of PMD. Aim: to reveal the level and spectrum of urine organic acids among patients with confirmed diagnosis (by molecular-genetic analysis) of PMD and to estimate the diagnostic value of the test. Methods. We measured 72 different metabolites in 84 urine samples from patients with PMD by GC-MS (7890А/5975С, Agilent Technologies, USA). Results. In 66/84 cases among the patients, we detected the abnormal level of urine organic acids. We observed a unique spectrum of metabolites in the patients with DGUOK-associated hepatopathy (abnormal levels of lactate, pyruvate, 3-hydroxybutyrate, and at the same time 4-hydroxyphenyllactate and 4-hydroxyphenylpyruvate). Using ROC-analysis one of the most informative biomarkers was 3-hydroxybutyrate. But due to the lack of specificity, it could not be classified as a valuable biomarker for PMD. The high level of pyruvate and 4-hydroxyphenyllactate could be taken into account to make a diagnosis of PMD

Direct Reduction in Greenhouse Gases by Continuous Dry (CO2) Reforming of Methane over Ni-Containing SHS Catalysts

The world of energy is on the cusp of profound transformation. Hydrogen or hydrogen-containing fuel mixtures in the form of synthesis gas, as carriers of clean energy, will be in the short term among the most efficient solutions to pressing environmental problems, reducing the amount of greenhouse gases as well as pollution of cities and dependence on oil-based fuels. Carbon dioxide conversion of methane is the most promising method for the production of synthesis gas due to the simultaneous consumption of two greenhouse gases and, accordingly, a successful solution to environmental problems. Ni/Mn-based catalysts have been prepared by self-propagating high-temperature synthesis (SHS) for this process. The samples were characterized by X-ray diffraction, scanning electron microscopy, and nitrogen porosimetry. The effects of the catalysts’ composition on activity, selectivity, and product yield were investigated. The influence of the content of Ni, Mn on the behavior of catalysts has been established. Comparison of spinels with different component ratios showed that they have a defective structure. Non-stoichiometric spinels with highly defective catalyst structures were obtained due to very high heating and cooling rates during SHS. They work as active sites, which underlies the high activity of the catalysts.

Mechanisms of Solid-Solution Hardening of Single-Phase Cu-Al and Cu-Mn Alloys with a Mesh Dislocation Substructure

The dislocation structure and dislocation accumulation during deformation of polycrystalline FCC solid solutions of Cu-Al and Cu-Mn systems are studied by transmission diffraction electron microscopy. The Al content in Cu-Al alloys varies from 0.5 to 14 at.%. The Mn content in Cu-Mn alloys varies in the range of 0.4 ÷ 25 at.%. Alloys with a grain size in the range of 20 ÷ 240 µm are studied. The alloy samples are deformed by stretching at a rate of 2×10-2c-1 to failure at 293 K. The structure of samples deformed to various degrees of deformation is studied on foils using electron microscopes at an accelerating voltage of 125 kV. For each degree of deformation, the scalar dislocation density and its components are measured: statistically stored dislocations ρS and geometrically necessary dislocations ρG and some other parameters of the defective structure. The mechanisms and their contributions due to mesh and mesh-mesh dislocation substructures (DSS) are determined using the example of substructural and solid-solution hardening in polycrystalline Cu-Al and Cu-Mn alloys. The relative role of various mechanisms in the formation of the resistance to deformation of alloys at different grain sizes is determined. The role of the packaging defect energy on the value of solid-solution hardening for different grain sizes is revealed. The average scalar dislocation density is considered and determined along with its components: statistically stored dislocations ρS and geometrically necessary dislocations ρG. The dependences of the flow stress on the square root of the densities of geometrically necessary dislocations and the densities of statistically stored dislocations are found.

Formation of a stable defects structure in silicon noise diodes

vThe possibilities and methods of creating a stable defective structure, including dislocation structure near the zones of p–n-transitions of silicon diodes of noise generators on plates with crystallographic orientations (111) and (001) have been investigated. The effective distribution control of uncontrolled impurities in monocrystalline silicon is achieved by forming a stable dislocation structure in its volume. In order to obtain the reproducible characteristics of noise generator diodes, it is necessary that the dislocation density be homogeneous throughout the plate area. Since the density of dislocations is slightly lower at the edge of the dislocation trail than in the middle, this means that the dislocation traces formed by the adjacent melting zones with the help of a laser beam should overlap. On the basis of experimental studies, it has been established that the necessary degree of uniformity of the density of defects generated is achieved by compliance with the condition of a = (1.5–5.0)d, where a is a step, d is a width of the laser spot on the wafer. The melting process was carried out in a nitrogen environment using a laser hettering unit. The real width of the melting zone turns out to be slightly larger than the diameter of the laser spot due to the thermal conductivity of the silicon and is about 10 μm. Increased dislocation generation on the Si3N4 inclusions, as opposed to dislocations on the Si–SiO2 border, leads to an additional expansion of the dislocation track at the work surface of the plate of noise diodes. The presence of the stable dislocation structure, as well as the presence of impurities and secondary metal atoms in the noise diodes ND 103L structure are confirmed by the secondary ion mass spectroscopy (SIMS) method. The results of the study have been tested at Corporation “INTEGRAL” (Belarus) and can be used in the manufacture of silicon noise diodes.

Graphite Foil Waste to Graphene: New Carbon Precursors for Synthesis of Graphene and its Oxides

In this paper, graphene oxide (GO) was obtained by oxidation of powdered graphite foil wastes (pGFW) at 0 - 40°C. Oxidizing reagents can easily penetrate the layers of graphite foil and thus, the intercalation or functionalization-oxidation processes may occur resulting in graphite oxide formation. The methods of synthesis of GO and its separation from the reaction mixture were partially corrected. GO was reduced, also, to the reduced graphene oxide (rGO) by using hydroiodic acid, ascorbic acid, zinc powder, hydrazine, and Alnus extract. Thermal treatment of GO powders and GO films, obtained from pGFW was implemented at 20-300° C in air and at 20-1000° C under argon flow and in a vacuum. At high-temperature treatment (1000°C) of GO graphene was obtained with a defective structure.