Specular reflection intensity modulated by grazing-incidence diffraction in a wide angular range

Grazing-incidence X-ray diffraction (GID) is a well known technique for the characterization of crystal surfaces. A theoretical study has been performed of the sensitivity of GID to the structure of a crystal surface and distorted nanometre-thin surface layers. To simulate GID from crystals that have a complex subsurface structure, a matrix formalism of the dynamical diffraction theory has been applied. It has been found that the azimuthal rocking curves of a crystal that has a distorted subsurface, measured over a wide angular range, show asymmetric thickness oscillations with two distinguishable sets of frequencies: one corresponding to the diffraction in the single-crystal subsurface layer and the second corresponding to the diffraction in the single-crystal substrate. Therefore, azimuthal rocking curves allow characterization of the subsurface structure of a single crystal. Furthermore, thickness oscillations induced by evanescent diffraction modulate the specular reflection intensity, showing high-intensity modulations. This will potentially allow implementation of subsurface crystal characterization using, for instance, a laboratory-scale X-ray diffractometer.</p

Постановка задачи управления автономным надводным судном для внутренних водных путей

Development of autonomous (uncrewed) surface vessels for commercial, industrial, and auxiliary fleet is currently one of the most rapidly advancing transport technologies. The key issue of its implementation is creation of an integrated control system (ICS) of safe navigation of uncrewed surface vehicles (USV) in automatic mode along the route. Then, it is necessary to keep in mind the features of maritime navigation and inland navigation.A performed analytical review of basic heading and speed control algorithms allowed revealing the main problems referring to development of an integrated control system for an USV. The statement of the control problem is followed by enlisting directions for further research.Одной из наиболее бурно развивающихся транспортных технологий в настоящее время является создание автономных (безэкипажных) надводных судов для коммерческого, технического и вспомогательного флота. Ключевым вопросом её внедрения является создание комплексной системы управления (КСУ) безопасным движением БЭС в автоматическом режиме по маршруту. При этом нужно иметь в виду специфику морской навигации и плавания по внутренним водным путям.Проведён аналитический обзор базовых алгоритмов управления по курсу и скорости. Сформулированы основные проблемы создания комплексной системы управления безэкипажным судном. Приведена постановка задачи управления и определены направления дальнейших исследований

Study of ultrathin Pt/Co/Pt trilayers modified by nanosecond XUV pulses from laser-driven plasma source

We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt1-xCox alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar ∼1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt1-xCox alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration

Роль микроРНК в развитии радиорезистентности клеток рака предстательной железы (экспериментальное исследование)

Background. Radiation therapy is one of the leading treatments for early and late stage prostate cancer. Radiation therapy is one of the leading treatments for early and late stage prostate cancer. The significant frequency of prostate cancer progression after radiation therapy makes it relevant to study the molecular mechanisms of the development of radioresistance, to identify prognostic markers of its development.Objective: identification and analysis of the mechanism of action of microRNAs regulating radioresistance of prostate cancer cells on the model of the androgen-independent DU145 cell line.Materials and methods. We used human prostate adenocarcinoma cell lines: DU145-hormone-independent prostate cancer cell line and DU145-RR - its radioresistant variant. Differential microRNA expression was measured in cultured DU145 and DU145-RR cells 1, 8 days after a single gamma irradiation at a dose of 4 Gy. To analyze the differential expression of microRNAs in the initial and radioresistant variants of DU145 cells, the HiSeq 2000 platform (Illumina Inc., USA) was used. The miRBase v.21 database was used to identify microRNAs. The miRTarbase 7.0 and KEGG PATHWAY databases were used for bioinformatic analysisResults. The results of the study showed that the aberrant expression of miR-101-3p, -148a-3p, -21-3p, -532-5p, -92a-3p in DU145-RR cells upregulated compared to that in DU145 cells, and miR-125b-5p, -23a-3p, -424-3p - downregulated. It has been shown that the role of these microRNAs is associated with the provision of functional interaction between DNA methyltransferases, the transcriptional regulator of the proto-oncogenic protein Myc, and PTEN phosphatase in the regulation of the activity of MAPK and PI3K protein kinase signaling cascades. Constitutive activation of these cascades leads to an increase in cell survival, migration, proliferation, and growth.Conclusion. A wide range of target genes and a significant change in the expression profiles of microRNAs in various conditions, including the transition of malignant cells to a radioresistant status, makes microRNAs promising prognostic markers of radioresistance in prostate cancer.Введение. Лучевая терапия - один из ведущих методов лечения рака предстательной железы на ранней и поздней стадиях развития. Значительная частота прогрессирования рака предстательной железы после лучевой терапии делает актуальными изучение молекулярных механизмов развития радиорезистентности и выявление прогностических маркеров ее развития.Цель исследования - идентификация и анализ механизма действия микроРНК, регулирующих радиорезистентность клеток рака предстательной железы на модели андрогеннезависимой клеточной линии DU145.Материалы и методы. В работе использовали клеточные линии аденокарциномы предстательной железы человека: DU145 - гормононезависимую клеточную линию рака предстательной железы и DU145-RR - ее радиорезистент-ный вариант. Дифференциальную экспрессию микроРНК измеряли в культивируемых клетках DU145 и DU145-RR через 1 и 8 сут после однократного Y-облучения в дозе 4 Гр. Для анализа дифференциальной экспрессии микроРНК в исходном и радиорезистентном вариантах клеток DU145 использовали платформу HiSeq 2000 (Illumina Inc., США). Для идентификации микроРНК применяли базу данных miRBase v.21. Для биоинформатического анализа - базы данных miRTarbase 7.0 и KEGG PATHWAY.Результаты. Результаты исследования показали, что аберрантная экспрессия miR-101-3p, -148a-3p, -21-3p, -532-5p, -92a-3p в клетках DU145-RR повышается по сравнению с таковой в клетках DU145, а miR-125b-5p, -23a-3p, -424-3p -снижается. Показано, что роль этих микроРНК связана с обеспечением функционального взаимодействия между ДНК-метилтрансферазами, транскрипционным регулятором протоонкогенного белка Myc, а также фосфатазой PTEN в регуляции активности протеинкиназных сигнальных каскадов MAPK и PI3K. Конститутивная активация данных каскадов приводит к повышению выживаемости, миграции, пролиферации и росту клеток.Заключение. Широкий спектр генов-мишеней и существенное изменение профилей экспрессии микроРНК при различных состояниях, включая переход злокачественных клеток в радиорезистентный статус, делают микроРНК перспективными прогностическими маркерами радиорезистентности при раке предстательной железы

Refined extreme ultraviolet mask stack model

A refined model of an extreme ultraviolet (EUV) mask stack consisting of the Mo/Si multilayer coated by a Ru protective layer and a TaBN/TaBO absorber layer was developed to facilitate accurate simulations of EUV mask performance for high-NA EUV photo-lithography (EUVL) imaging. The model is derived by combined analysis of the measured EUV and x ray reflectivity of an industry-representative mask blank. These two sets of measurements were analyzed using a combined free-form analysis procedure that delivers high-resolution x ray and EUV optical constant depth profiles based on self-adapted sets of sublayers as thin as 0.25 nm providing a more accurate description of the reflectivity than obtained from only EUV reflectivity. “Free-form analysis” means that the shape of the layer interfaces in the model is determined experimentally and is not given a priori by the structure model. To reduce the numerical effort for EUV imaging simulations, a low-resolution model of the multilayer and absorber stack with sublayer thicknesses larger than 2 nm, that fits to only the EUV reflectance, was derived from the high-resolution model. Rigorous high-NA EUVL simulations were done to compare the performance of the new model to our previous work

Wavelength selection for multilayer coatings for lithography generation beyond extreme ultraviolet

The spectral properties of LaN/B and LaN∕B4C multilayer mirrors have been investigated in the 6.5 to 6.9 nm wavelength range, based on measured B and B4C optical constants. We show that the wavelength of optimal reflectance for boron-based optics is between 6.63 and 6.65 nm, depending on the boron chemical state. The wavelength of the maximum reflectance of the LaN∕B4C multilayer system is confirmed experimentally. Calculations of the wavelength-integrated reflectance for perfect ten-multilayer-mirror stacks show that a B-based optical column can be optimized for a wavelength larger than 6.65 nm.</p

Si transfer and self-limiting chemisorption on Ru thin film surface in hydrogen radicals environment

Surface contamination and its level control play a crucial role in modern technologies and industries. One of the contamination mechanisms in industries which use hydrogen plasma is so-called hydrogen induced outgassing (HIO) when hydrogen species interact with surface contaminants forming volatile hydrides. Thus, these volatile hydrides may be adsorbed on chemically active surfaces spreading contamination. Our goal is to understand the HIO process and develop a dedicated surface cleanliness metrology. One of the approaches is to find a material that acts as getter for HIO species, such that the presence of HIO species on large surface area components can be detected by post-mortem analysis of the getter sample after simultaneous hydrogen radicals exposure of the component of interest and the getter sample. We have started to test this approach with Si as HIO material and a Ru thin film as the getter material. The interaction of hydrogen radicals with the Si surface leads to the formation of volatile silane which subsequently adsorbs on the getter material. In equilibrium conditions, when the silicon ‘source’ and Ru getter are placed next to each other and exposed to the same hydrogen radical flux, one monolayer of chemisorbed Si is observed. We propose that silane adsorption in hydrogen radicals environment is a self-limiting process, where the reaction terminates once all the reactive Ru sites on the surface are occupied by chemisorbed Si