453 research outputs found
Structure, stability, and mobility of small Pd clusters on the stoichiometric and defective TiO (110) surfaces
We report on the structure and adsorption properties of Pd ()
clusters supported on the rutile TiO (110) surfaces with the possible
presence of a surface oxygen vacancy or a subsurface Ti-interstitial atom. As
predicted by the density functional theory, small Pd clusters prefer to bind to
the stoichiometric titania surface or at sites near subsurface Ti-interstitial
atoms. The adsorption of Pd clusters changes the electronic structure of the
underlying surface. For the surface with an oxygen vacancy, the charge
localization and ferromagnetic spin states are found to be largely attenuated
owing to the adsorption of Pd clusters. The potential energy surfaces of the Pd
monomer on different types of surfaces are also reported. The process of
sintering is then simulated via the Metropolis Monte Carlo method. The presence
of oxygen vacancy likely leads to the dissociation of Pd clusters. On the
stoichiometric surface or surface with Ti-interstitial atom, the Pd monomers
tend to sinter into larger clusters, whereas the Pd dimer, trimer and tetramer
appear to be relatively stable below 600 K. This result agrees with the
standard sintering model of transition metal clusters and experimental
observations.Comment: 27 pages, 11 figure
Examination of evidence for collinear cluster tri-partition
In a series of the experiments at different time-of-flight spectrometers of
heavy ions we have observed manifestations of a new at least ternary decay
channel of low excited heavy nuclei. Due to specific features of the effect, it
was called collinear cluster tri-partition (CCT). The experimental results
obtained initiated a number of theoretical articles dedicated to different
aspects of the CCT. We compare theoretical predictions with our experimental
data, only partially published so far. The model of one of the most populated
CCT modes that gives rise to the so called "Ni-bump" is discussed. Detection of
the 68-72Ni fission fragments with a kinetic energy E<25 MeV at the
mass-separator Lohengrin is proposed for an independent experimental
verification of the CCT.Comment: 16 pages, 14 figure
Aromaticity in a Surface Deposited Cluster: Pd on TiO (110)
We report the presence of \sigma-aromaticity in a surface deposited cluster,
Pd on TiO (110). In the gas phase, Pd adopts a tetrahedral
structure. However, surface binding promotes a flat, \sigma-aromatic cluster.
This is the first time aromaticity is found in surface deposited clusters.
Systems of this type emerge as a promising class of catalyst, and so
realization of aromaticity in them may help to rationalize their reactivity and
catalytic properties, as a function of cluster size and composition.Comment: 4 pages, 3 figure
SETTING UP A DIGITAL LEARNING ENVIRONMENT IN A PEDAGOGICAL UNIVERSITY
This article is aimed at discovering the development particularities of the digital Russian university management system in Russia in the context of universal digitalisation, and identifying the opportunities for the development of university digital learning environment elements. The leading research method of the issue is a comparative analysis of the level of digital competences of students of professional education in Russia and the European Union member states. The authors of the article discovered the particularities of modern education transformational processes, revealed the main role of the development of information and communication technologies, determined the place of Russia in the world learning space and analysed the dynamics of the position of Russian higher educational institutions in the world university rating.Este artículo tiene como objetivo descubrir las particularidades de desarrollo del sistema digital de gestión de la universidad rusa en Rusia en el contexto de la digitalización universal, e identificar las oportunidades para el desarrollo de elementos del entorno de aprendizaje digital universitario. El principal método de investigación del tema es un análisis comparativo del nivel de competencias digitales de los estudiantes de educación profesional en Rusia y los estados miembros de la Unión Europea. Los autores del artículo descubrieron las particularidades de los procesos de transformación de la educación moderna, revelaron el papel principal del desarrollo de las tecnologías de información y comunicación, determinaron el lugar de Rusia en el espacio de aprendizaje mundial y analizaron la dinámica de la posición de las instituciones de educación superior rusas en La calificación de la universidad mundial.Este artigo tem como objetivo descobrir as particularidades de desenvolvimento do sistema de gerenciamento de universidades digitais da Rússia na Rússia no contexto da digitalização universal e identificar as oportunidades para o desenvolvimento de elementos do ambiente de aprendizado digital das universidades. O principal método de pesquisa da questão é uma análise comparativa do nível de competências digitais de estudantes de educação profissional na Rússia e nos estados membros da União Europeia. Os autores do artigo descobriram as particularidades dos processos transformacionais da educação moderna, revelaram o papel principal do desenvolvimento das tecnologias da informação e da comunicação, determinaram o lugar da Rússia no espaço de aprendizado mundial e analisaram a dinâmica da posição das instituições de ensino superior russas no país. a classificação mundial da universidade
Resolvent estimates for normally hyperbolic trapped sets
We give pole free strips and estimates for resolvents of semiclassical
operators which, on the level of the classical flow, have normally hyperbolic
smooth trapped sets of codimension two in phase space. Such trapped sets are
structurally stable and our motivation comes partly from considering the wave
equation for Kerr black holes and their perturbations, whose trapped sets have
precisely this structure. We give applications including local smoothing
effects with epsilon derivative loss for the Schr\"odinger propagator as well
as local energy decay results for the wave equation.Comment: Further changes to erratum correcting small problems with Section 3.5
and Lemma 4.1; this now also corrects hypotheses, explicitly requiring
trapped set to be symplectic. Erratum follows references in this versio
Two cases of hydrophobia in the Republic of Tatarstan: In vivo and postmortem laboratory diagnosis
The results of rabies in vivo and postmortem laboratory detection in two cases registered in the Republic of Tatarstan are reported: a victim bitten by a wolf in 2002 and another one bitten by a stray dog on Goa Island, India, in 2013. In the patient bitten by a wolf cornea imprints studies using the method of fluorescent antibodies (MFA) showed rabies-positive result 6 days before the patient's death. The results were confirmed by postmortem examination of different parts of the brain and salivary glands using the MFA, enzyme-linked immunosorbent assay (ELISA), optical microscopy, and bioassay methods. In the patient bitten by a stray dog the rabies virus specific antigen was detected by eye cornea studies using the MFA method and saliva studies using the ELISA. The rabies virus genome was also isolated from saliva and tear fluid using nested reverse-transcription polymerase chain reaction (RT-PCR) 9 days before the patient's death. The in vivo studies results were consistent with the postmortem study of different parts of the brain using the MFA, enzyme-linked immunosorbent assay (ELISA), optical microscopy, and bioassay methods. All the infection-positive results of both in vivo and postmortem studies were consistent with the clinical studies, i.e. rabies diagnosis was confirmed. The analysis of the rabies virus gene G fragment nucleotide sequence of 238 nd length showed a slight difference between the studied isolates (2 rabies) and the RABV AY956319 (1.68%), difference by 10.5% from the Vnukovo-32 vaccine strains and by 10.9 % from the SAD B19 rabies strain, respectively (rabies viruses of 1st genotype). It was also significantly different from the lissaviruses of 2,4,5, and 6 genotypes (21.0-32.7%). The obtained results indicate phylogenetic closeness of the studied isolates (2 rabies) with the RABV AY956319 rabies virus strain belonging to the 1st genotype
Prognostic value of left ventricular global longitudinal strain and mechanical dispersion by speckle tracking echocardiography in patients with ischemic and nonischemic cardiomyopathy: a systematic review and meta-analysis
Aim. To conduct a systematic review and meta-analysis in order to evaluate the prognostic value of left ventricular global longitudinal strain (LV GLS) and LV mechanical dispersion (LVMD) in ischemic and nonischemic cardiomyopathy.Material and methods. We searched PubMed, Google Scholar and Embase for studies on the prognostic value of LV GLS and LVMD in ischemic and nonischemic cardiomyopathy. Hazard ratios (HR) from included studies were pooled for metaanalysis.Results. Twelve studies were selected from 314 publications for this systematic review and meta-analysis. In total, 2624 patients (mean age, 57,3 years; mean follow-up, 40,8 months) were included in the analysis. Meta-analysis showed that decreased LV GLS was associated with an increased risk of ventricular arrhythmias (VAs) (adjusted HR: 1,10 per 1% of GLS; 95% CI: 1,01-1,19; p=0,03) and major adverse cardiovascular events (MACE): adjusted HR: 1,22 per 1% of GLS; 95% CI: 1,11-1,33; p<0,0001). Patients with VAs had greater LVMD than those without it (weighted mean difference, 33,69 ms; 95% CI: -41,32 to -26,05; p<0,0001). Each 10 ms increment of LVMD was significantly and independently associated with VA episodes (adjusted HR: 1,18; 95% CI: 1,08-1,29; p=0,0002).Conclusions. LV GLS and LVMD assessed using speckle tracking provides important predictive value and can be used as an effective tool for stratifying risk in patients with ischemic and nonischemic cardiomyopathy
Coupled phase transformations and plastic flows under torsion at high pressure in rotational diamond anvil cell: Effect of contact sliding
A three-dimensional large-sliding contact model coupled with strain-induced phase transformations (PTs) and plastic flow in a disk-like sample under torsion at high pressure in rotational diamond anvil cell (RDAC) is formulated and studied. Coulomb and plastic friction are combined and take into account variable parameters due to PT. Results are obtained for weaker, equal-strength, and stronger high pressure phases, and for three values of the kinetic coefficient in a strain-controlled kinetic equation and friction coefficient. All drawbacks typical of problem with cohesion are overcome, including eliminating mesh-dependent shear band and artificial plastic zones. Contact sliding intensifies radial plastic flow, which leads to larger reduction in sample thickness. Larger plastic strain and increased pressure in the central region lead to intensification of PT. However, the effect of the reduction in the friction coefficient on PT kinetics is nonmonotonous. Sliding increases away from the center and with growing rotation and is weakly dependent on the kinetic coefficient. Also, cyclic back and forth torsion is studied and compared to unidirectional torsion. Multiple experimental phenomena, e.g., pressure self-multiplication effect, steps (plateaus) at pressure distribution, flow to the center of a sample, and oscillatory pressure distribution for weaker high-pressure phase, are reproduced and interpreted. Reverse PT in high pressure phase that flowed to the low pressure region is revealed. Possible misinterpretation of experimental PT pressure is found. Obtained results represent essential progress toward understanding of strain-induced PTs under compression and shear in RDAC and may be used for designing experiments for synthesis of new high pressure phases and reduction in PT pressure for known phases, as well as for determination of PT kinetics from experiments
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