98 research outputs found

    In situ SR-XPS observation of Ni-assisted low-temperature formation of epitaxial graphene on 3C-SiC/Si

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    Low-temperature (~1073 K) formation of graphene was performed on Si substrates by using an ultrathin (2 nm) N

    Prostaglandin H synthase kinetics in the two-phase aqueous-micellar system

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    AbstractReaction mixture for PGHS (prostaglandin-H-synthase) is a two-phase system including micellar hydrophobic phase and hydrophilic aqueous phase. Reagents added to the mixture are distributed between phases, thus concentrations of reagents dissolved in phases can differ significantly from their overall contents.Using dynamic light scattering we found that the hydrophobic phase produced by tween-20 consists of micelles, which radius (4–5nm) does not depend on either tween-20 overall content (0.1%–1% v/v) or arachidonic acid (AA) addition (10–1000μM) or PGHS addition (1μM).Tween-20 overall content changing from 0.1% to 2% v/v dramatically affected COX kinetic, but accounting AA distribution between phases allowed us to estimate “true” parameters, independent of the tween-20 overall content and the concentration of another substrate: KMOx equals 9.8μM O2 in the aqueous phase or 0.0074bar in the gaseous phase, KMAA equals 5400μM AA in the phase of tween-20 micelles and 5400/PμM AA in the aqueous phase (P is the distribution ratio for the AA between the aqueous phase and the hydrophobic phase (P≫1000)). This approach allowed to evaluate PS, the distribution ratio for the AA between the hydrophobic phase and the PGHS active center (PS ~310). This coefficient indicates the AA selectivity toward the cyclooxygenase active center

    Nonreciprocity of spin waves in metallized magnonic crystal

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    The nonreciprocal properties of spin waves in metallized one-dimensional bi-component magnonic crystal composed of two materials with different magnetizations are investigated numerically. Nonreciprocity leads to the appearance of indirect magnonic band gaps for magnonic crystals with both low and high magnetization contrast. Specific features of the nonreciprocity in low contrast magnonic crystals lead to the appearance of several magnonic band gaps located within the first Brillouin zone for waves propagating along the metallized surface. Analysis of the spatial distribution of dynamic magnetization amplitudes explains the mechanism of dispersion band formation and hybridization between magnonic bands in magnonic crystals with metallization

    Multiple Folding Pathways of the SH3 domain

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    Experimental observations suggest that proteins follow different pathways under different environmental conditions. We perform molecular dynamics simulations of a model of the SH3 domain over a broad range of temperatures, and identify distinct pathways in the folding transition. We determine the kinetic partition temperature --the temperature for which the SH3 domain undergoes a rapid folding transition with minimal kinetic barriers-- and observe that below this temperature the model protein may undergo a folding transition via multiple folding pathways. The folding kinetics is characterized by slow and fast pathways and the presence of only one or two intermediates. Our findings suggest the hypothesis that the SH3 domain, a protein for which only two-state folding kinetics was observed in previous experiments, may exhibit intermediates states under extreme experimental conditions, such as very low temperatures. A very recent report (Viguera et al., Proc. Natl. Acad. Sci. USA, 100:5730--5735, 2003) of an intermediate in the folding transition of the Bergerac mutant of the alpha-spectrin SH3 domain protein supports this hypothesis.Comment: 16 pages, 4 figures To be published in the "Journal of Molecular Biology

    Collaborative development of predictive toxicology applications

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    OpenTox provides an interoperable, standards-based Framework for the support of predictive toxicology data management, algorithms, modelling, validation and reporting. It is relevant to satisfying the chemical safety assessment requirements of the REACH legislation as it supports access to experimental data, (Quantitative) Structure-Activity Relationship models, and toxicological information through an integrating platform that adheres to regulatory requirements and OECD validation principles. Initial research defined the essential components of the Framework including the approach to data access, schema and management, use of controlled vocabularies and ontologies, architecture, web service and communications protocols, and selection and integration of algorithms for predictive modelling. OpenTox provides end-user oriented tools to non-computational specialists, risk assessors, and toxicological experts in addition to Application Programming Interfaces (APIs) for developers of new applications. OpenTox actively supports public standards for data representation, interfaces, vocabularies and ontologies, Open Source approaches to core platform components, and community-based collaboration approaches, so as to progress system interoperability goals

    In Situ SR-XPS Observation of Ni-Assisted Low-Temperature Formation of Epitaxial Graphene on 3C-SiC/Si

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    Low-temperature (~1073 K) formation of graphene was performed on Si substrates by using an ultrathin (2 nm) Ni layer deposited on a 3C-SiC thin film heteroepitaxially grown on a Si substrate. Angle-resolved, synchrotron-radiation X-ray photoemission spectroscopy (SR-XPS) results show that the stacking order is, from the surface to the bulk, Ni carbides(Ni(3)C/NiC(x))/graphene/Ni/Ni silicides (Ni(2)Si/NiSi)/3C-SiC/Si. In situ SR-XPS during the graphitization annealing clarified that graphene is formed during the cooling stage. We conclude that Ni silicide and Ni carbide formation play an essential role in the formation of graphene

    Overview and comparison of cloud solutions for application development

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    This bachelor thesis lets the reader understand the definition of cloud computing, learn some facts about history of occurrence of the term. Also this bachelor thesis presents basic information considering the key players in the cloud computing market and main advantages and disadvantages of choosing cloud computing. The practical part of this thesis describes some smaller but extremely interesting cloud platforms, which are not well-known and distributed as a freeware. The main goal of this thesis is to explore cloud platforms for development

    Start of Higher School in Crimea: Taurida University (1918–1920)

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    October 14, 2018 marked the 100th anniversary of the inauguration of the first university in Crimea, which initially, in 1918–1920, was called the Taurida University, and now is V.I. Vernadsky Crimean Federal University. In this regard, it is useful to recall the main stages of the history of the university. Of particular interest is the history of Taurida University in the years of the Civil War, when its teachers were the greatest scientists who fled from the Bolshevik terror from the university centers of the former Russian Empire to the “white” Crimea. But it was precisely this period that received the least coverage in the literature published in the twentieth century. The main reason for this is the lack of a sufficient source base. After all, the pre-war university archive was lost, and the main source for a long time remained only two volumes of the “News of the Tauride University” published in 1919 and 1920. The noted narrowness of the source base forced researchers to look for additional sources of information. Attention was drawn to the archives of institutions, organizations and individuals associated with the university in the initial period of its existence, as well as sources of personal origin (diaries of Academician V.I. Vernadsky, memories of his son, Professor G.V. Vernadsky, etc.).In the late 1990s, the author of the article was fortunate enough to reach the richest unique source that remained untapped by researchers on the history of the Crimean intelligentsia, science and culture in 1917–1920 – Crimean newspapers during the Civil War. On their pages, it was possible to find not only chronicle notes to recreate the missing pages of the history of Taurida University and existing scientific societies, not only information about the participation of university professors in the activities of numerous Crimean scientific organizations, but also publications of a number of leading scientists that remained unknown.The present article is based mainly on these newspapers, which have long become a bibliographic rarity

    Ab initio calculations of absolute surface energies of clean and hydrogen covered 3C-SiC(001), (110) and (111) surfaces

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    The absolute surface energies of three major low index surfaces of cubic silicon carbide (3C-SiC) are determined by first-principles density functional theory calculations. Calculations show that among clean 3C-SiC surfaces the Si-terminated 3C-SiC(001)-(3x2) surface has the lowest energy. The second and third lowest energy surfaces are the Si-terminated 3C-SiC(111)-(√3x√3) surface and the nonreconstructed 3C-SiC(110) surface. Hydrogen passivation greatly reduces both the absolute surface energies of the low index 3C-SiC surfaces and the surface energy anisotropy. In particular, the surface energies of fully passivated 3C-SiC(110) and (111) surfaces become indistinguishable at hydrogen-rich deposition conditions
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