358 research outputs found

    Controlling Boron Diffusion during Rapid Thermal Annealing with CoImplantation by Amphoteric Impurity Atoms

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    A model for simulating the rapid thermal annealing of silicon structures implanted with boron and carbon is developed. The model provides a fair approximation of the process of boron diffusion in silicon, allowing for such effects as the electric field, the impact of the implanted carbon, and the clustering of boron. The migration process of interstitials is described according to their drift in the field of internal elastic stress

    Модель формирования остаточных напряжений при газотермическом осаждении покрытий

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    The paper shows that gas-thermal coatings on the product surface may be considered on a first approximation as bimetallic material. Such approach permits to make calculations and determine residual stresses on the basis of multi-layer plate theory, mechanics of continuous medium and thermoelasticity.Показано, что газотермические покрытия на поверхности изделия можно рассматривать в первом приближении как биметаллический материал, что позволяет проводить расчеты и определять остаточные напряжения, основываясь на теории многослойных пластин, механики сплошных сред и термоупругости

    Combined Transfer of Human VEGF165 and HGF Genes Renders Potent Angiogenic Effect in Ischemic Skeletal Muscle

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    Increased interest in development of combined gene therapy emerges from results of recent clinical trials that indicate good safety yet unexpected low efficacy of “single-gene” administration. Multiple studies showed that vascular endothelial growth factor 165 aminoacid form (VEGF165) and hepatocyte growth factor (HGF) can be used for induction of angiogenesis in ischemic myocardium and skeletal muscle. Gene transfer system composed of a novel cytomegalovirus-based (CMV) plasmid vector and codon-optimized human VEGF165 and HGF genes combined with intramuscular low-voltage electroporation was developed and tested in vitro and in vivo. Studies in HEK293T cell culture, murine skeletal muscle explants and ELISA of tissue homogenates showed efficacy of constructed plasmids. Functional activity of angiogenic proteins secreted by HEK293T after transfection by induction of tube formation in human umbilical vein endothelial cell (HUVEC) culture. HUVEC cells were used for in vitro experiments to assay the putative signaling pathways to be responsible for combined administration effect one of which could be the ERK1/2 pathway. In vivo tests of VEGF165 and HGF genes co-transfer were conceived in mouse model of hind limb ischemia. Intramuscular administration of plasmid encoding either VEGF165 or HGF gene resulted in increased perfusion compared to empty vector administration. Mice injected with a mixture of two plasmids (VEGF165+HGF) showed significant increase in perfusion compared to single plasmid injection. These findings were supported by increased CD31+ capillary and SMA+ vessel density in animals that received combined VEGF165 and HGF gene therapy compared to single gene therapy. Results of the study suggest that co-transfer of VEGF and HGF genes renders a robust angiogenic effect in ischemic skeletal muscle and may present interest as a potential therapeutic combination for treatment of ischemic disorders

    МОДЕЛИРОВАНИЕ ПРОЦЕССОВ ИОННОЙ ИМПЛАНТАЦИИ И БЫСТРЫХ ТЕРМООБРАБОТОК ПРИ ФОРМИРОВАНИИ АКТИВНЫХ ОБЛАСТЕЙ СУБМИКРОННЫХ И НАНОМЕТРОВЫХ ИНТЕГРАЛЬНЫХ СХЕМ НА КРЕМНИИ

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    The physical models and numerical algorithms allowing one to accurately simulate advanced technological processes, such as low−energy ion implantation and rapid thermal processing (RTA) are presented. A software system on the basis of these models has been designed and integrated into the microelectronics device and process modeling system Silvaco ATHENA. It enables the use of models and calculationmethods alternative to those implemented in the well−known software products, mainly for solving the problems with shallow depths of doped regionsРассмотрены физико−математические модели и численные алгоритмы, позволяющие достаточно точно моделировать современные технологические процессы, такие как низкоэнергетическая ионная имплантация и быстрая термообработка. Разработанный на основе этих моделей программный комплекс, интегрированный в систему сквозного моделирования процессов и приборов интегральной электроники Silvaco ATHENA, дает возможность использовать модели и методы расчета, альтернативные реализованным в известных программных продуктах, главным образом в решении задач с малой глубиной формируемых легированных областей

    Parental Genome Dosage Imbalance Deregulates Imprinting in Arabidopsis

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    In mammals and in plants, parental genome dosage imbalance deregulates embryo growth and might be involved in reproductive isolation between emerging new species. Increased dosage of maternal genomes represses growth while an increased dosage of paternal genomes has the opposite effect. These observations led to the discovery of imprinted genes, which are expressed by a single parental allele. It was further proposed in the frame of the parental conflict theory that parental genome imbalances are directly mirrored by antagonistic regulations of imprinted genes encoding maternal growth inhibitors and paternal growth enhancers. However these hypotheses were never tested directly. Here, we investigated the effect of parental genome imbalance on the expression of Arabidopsis imprinted genes FERTILIZATION INDEPENDENT SEED2 (FIS2) and FLOWERING WAGENINGEN (FWA) controlled by DNA methylation, and MEDEA (MEA) and PHERES1 (PHE1) controlled by histone methylation. Genome dosage imbalance deregulated the expression of FIS2 and PHE1 in an antagonistic manner. In addition increased dosage of inactive alleles caused a loss of imprinting of FIS2 and MEA. Although FIS2 controls histone methylation, which represses MEA and PHE1 expression, the changes of PHE1 and MEA expression could not be fully accounted for by the corresponding fluctuations of FIS2 expression. Our results show that parental genome dosage imbalance deregulates imprinting using mechanisms, which are independent from known regulators of imprinting. The complexity of the network of regulations between expressed and silenced alleles of imprinted genes activated in response to parental dosage imbalance does not support simple models derived from the parental conflict hypothesis

    The who, where, what, how and when of market entry

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    This introductory, along with the eight articles contained within this Special Issue, highlights and brings greater clarity to entrant-incumbent interactions and to firm movement - when entrants traverse market territories for the creation and/or delivery of offerings, where 'markets' include service or product categories, technology or resource spaces, industries, sectors and/or geographies. Collectively, this Special Issues explains that firm movement across market boundaries is highly consequential, influencing resource-capability mixes inside firms, interfirm relations, market logic and industry value chains, and of course, people, communities and even nations. Specifically, we develop a field-wide perspective of market entry by expanding on the framework of market entry that Zachary and his colleagues developed (Zachary et al., 2015) - i.e., the who (players such as incumbents, entrants, suppliers, etc.), when (the timing and sequence of entry), how (the strategy, resources, capabilities, etc.), where (the space of entry) and what (product, service, business model, etc.) - to include two additional categories: complements (networks, platforms, ecosystems) and non-market elements (government, political, social and cultural arrangements). We also summarize the eight highly diverse and insightful articles that make this Special Issue, and conclude with a discussion to highlight foundational questions that point to new directions in future research in this field. In sum, we hope to inspire scholars to go beyond counting outcomes (e.g., entry/exit rates, or profiling successful versus unsuccessful entrants), to consider contexts, processes and contingencies (e.g., cost, time, collaboration, competition, interfirm relations, etc.) and to discover boundary conditions that inform a theory of market entry

    H3K27me3 Profiling of the Endosperm Implies Exclusion of Polycomb Group Protein Targeting by DNA Methylation

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    Polycomb group (PcG) proteins act as evolutionary conserved epigenetic mediators of cell identity because they repress transcriptional programs that are not required at particular developmental stages. Each tissue is likely to have a specific epigenetic profile, which acts as a blueprint for its developmental fate. A hallmark for Polycomb Repressive Complex 2 (PRC2) activity is trimethylated lysine 27 on histone H3 (H3K27me3). In plants, there are distinct PRC2 complexes for vegetative and reproductive development, and it was unknown so far whether these complexes have target gene specificity. The FERTILIZATION INDEPENDENT SEED (FIS) PRC2 complex is specifically expressed in the endosperm and is required for its development; loss of FIS function causes endosperm hyperproliferation and seed abortion. The endosperm nourishes the embryo, similar to the physiological function of the placenta in mammals. We established the endosperm H3K27me3 profile and identified specific target genes of the FIS complex with functional roles in endosperm cellularization and chromatin architecture, implicating that distinct PRC2 complexes have a subset of specific target genes. Importantly, our study revealed that selected transposable elements and protein coding genes are specifically targeted by the FIS PcG complex in the endosperm, whereas these elements and genes are densely marked by DNA methylation in vegetative tissues, suggesting that DNA methylation prevents targeting by PcG proteins in vegetative tissues
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