Defects in SiO2 as the possible origin of near interface traps in the SiC∕SiO2 system: A systematic theoretical study

A systematic study of the level positions of intrinsic and carbon defects in SiO2 is presented, based on density functional calculations with a hybrid functional in an alpha-quartz supercell. The results are analyzed from the point of view of the near interface traps (NIT), observed in both SiC/SiO2 and Si/SiO2 systems, and assumed to have their origins in the oxide. It is shown that the vacancies and the oxygen interstitial can be excluded as the origin of such NIT, while the silicon interstitial and carbon dimers give rise to gap levels in the energy range inferred from experiments. The properties of these defects are discussed in light of the knowledge about the SiC/SiO2 interface

Identification of intrinsic electron trapping sites in bulk amorphous silica from ab initio calculations

Using ab initio calculations we demonstrate that extra electrons in pure amorphous SiO2 can be trapped in deep band gap states. Classical potentials were used to generate amorphous silica models and density functional theory to characterise the geometrical and electronic structures of trapped electrons. Extra electrons can trap spontaneously on pre-existing structural precursors in amorphous SiO2 and produce ≈≈3.2 eV deep states in the band gap. These precursors comprise wide (⩾⩾130°°) O–Si–O angles and elongated Si–O bonds at the tails of corresponding distributions. The electron trapping in amorphous silica structure results in an opening of the O–Si–O angle (up to almost 180°°). We estimate the concentration of these electron trapping sites to be View the MathML source≈5×1019cm-3

Hydrogen-induced rupture of strained Si─O bonds in amorphous silicon dioxide

Using ab initio modeling we demonstrate that H atoms can break strained Si─O bonds in continuous amorphous silicon dioxide (a−SiO2) networks, resulting in a new defect consisting of a threefold-coordinated Si atom with an unpaired electron facing a hydroxyl group, adding to the density of dangling bond defects, such as E′ centers. The energy barriers to form this defect from interstitial H atoms range between 0.5 and 1.3 eV. This discovery of unexpected reactivity of atomic hydrogen may have significant implications for our understanding of processes in silica glass and nanoscaled silica, e.g., in porous low-permittivity insulators, and strained variants of a−SiO2

Spectrum of Light in a Quantum Fluctuating Periodic Structure

We address the general problem of the excitation spectrum for light coupled to scatterers having quantum fluctuating positions around the sites of a periodic lattice. In addition to providing an imaginary part to the spectrum, we show that these quantum fluctuations affect the real part of the spectrum, in a way that we determine analytically. Our predictions may be observed with ultracold atoms in an optical lattice, on a J=0->J'=1 narrow atomic transition. As a side result, we resolve a controversy for the occurrence of a spectral gap in a fcc lattice.Comment: 4 pages, 1 figure; introduction, conclusion and title change

Modulational instability of bright solitary waves in incoherently coupled nonlinear Schr\"odinger equations

We present a detailed analysis of the modulational instability (MI) of ground-state bright solitary solutions of two incoherently coupled nonlinear Schr\"odinger equations. Varying the relative strength of cross-phase and self-phase effects we show existence and origin of four branches of MI of the two-wave solitary solutions. We give a physical interpretation of our results in terms of the group velocity dispersion (GVD) induced polarization dynamics of spatial solitary waves. In particular, we show that in media with normal GVD spatial symmetry breaking changes to polarization symmetry breaking when the relative strength of the cross-phase modulation exceeds a certain threshold value. The analytical and numerical stability analyses are fully supported by an extensive series of numerical simulations of the full model.Comment: Physical Review E, July, 199

Analysis of Epidemiological Situation on Leptospiroses in the Amur-River Region. Operational Experience in the Flood Area in 2013, and Forecasting for 2014

For the first time ever mobile SAET units have performed complex investigation of epidemiological situation on leptospiroses in order to provide sanitary-epidemiological welfare of the population in the Amur-River region devastated by high water in 2013. Analyzed have been contemporary published and archival data on morbidity rate and epizootic activity of the natural leptospirosis foci in the Amur-River territory up to 2013. Summarized is the information concerning monitoring over natural focal infections (in particular leptospiroses) in the flooding area, obtained by specialized antiepidemic teams from Irkutsk Research Anti-Plague Institute of Siberia and Far East deployed in Belogorsk town of the Amur Region and Khabarovsk city in 2013. Epizootiological situation during the high water period in the Jewish Autonomous Region has been defined as an extremely adverse, unlike the Khabarovsk Territory and the Amur Region where epizootic process is less expressed. Therewith aggravation of epidemiological situation on leptospiroses in the Amur-River Region in 2014 is not ruled out

Analysis and Reuse of Plots Using Similarity and Analogy

Abstract: A plot is a partially ordered set of events. Plot analysis is a relevant source of knowledge about the agents behavior when accessing data stored in the database. It relies on logical logs which register the actions of individual agents. This paper proposes techniques to analyze and reuse plots based on the concepts of similarity and analogy, borrowed from cognitive science and linguistics. The concept of similarity is applied to organize plots as a library, and to explore the reuse of plots in the same domain. By contrast, the concept of analogy helps reuse plots across different domains. The techniques proposed in this paper find applications in areas such as computer games and emergency response information systems, as well as some traditional business applications

The First Case of <I>Yersinia Pestis</I> Subsp. <I>Pestis</I> Isolation in the Territory of Altai Mountain Natural Plague Focus. Communication 1. Microbiological Characteristics, Molecular-Genetic and Mass-Spectrometric Identification of the Isolate

Performed is a complex microbiological, molecular-genetic and mass-spectrometric identification of Yersinia pestis main ssp. strain, which was isolated for the first time in the history of surveillance over the Altai mountain natural plague focus in June, 2012. Determined is its high universal virulence. Plasmid screening, multi-locus VNTR- and mass-spectrometric analyses have revealed the strain to be more closely related to the plague agent variant, circulating in the territory of the natural focus Khuukh-Serkh-Munkh-Khairkhan, Bayan-Ul’giisk aimak, Mongolia

О разработке новых криминалистических средств выявления следов кожного покрова человека

The article reviews the main physical and physicochemical factors influencing the three-component system “fingerprint powder – prints bearing surface – sweat and grease print substance”. The authors propose new model compositions of fingerprint powders considering the reviewed common patterns: non-magnetic and luminescent magnetic. The features of prints bearing surfaces and developed fingerprint powders have been evaluated by applying electronic microscopy methods (scanning and probe microscopy). The authors have proven that the use of nano- and ultra disperse materials in the developed compositions (carbon nanotubes and shungite) enables to vary the sorption and adhesive capacity of fingerprint powders, which allows detecting fingerprints on varying surfaces with high selectivity toward the sweat and grease print substance and contrasting effect.Несмотря на широкий спектр технико-криминалистических средств выявления и фиксации следов кожного покрова человека, проблема разработки дактилоскопических порошков, обладающих одновременно универсальностью по отношению к различным поверхностям и специфичностью при взаимодействии с потожировым веществом, остается актуальной. В статье рассмотрены основные физические и физико-химические факторы, оказывающие влияние на трехкомпонентную систему «дактилоскопический порошок – следонесущая поверхность – потожировое вещество следа». Разработаны новые модельные составы дактилоскопических порошков: немагнитного и люминесцентного магнитного с учетом рассмотренных закономерностей. Характеристики полученных порошков, а также следонесущие поверхности оценивали методами электронной микроскопии (растровой и зондовой). Показано, что применение нано- и ультрадисперсных материалов (углеродных нанотрубок и шунгита) в разработанных составах позволяет варьировать сорбционную и адгезионную способность порошков. Это делает возможным выявление следов рук на различных по контрастности и свойствам поверхностях с высокой селективностью по отношению к потожировому веществу следа.