Resolving the controversy on the glass transition temperature of water?

We consider experimental data on the dynamics of water (1) in glass-forming aqueous mixtures with glass transition temperature Tg approaching the putative Tg=136 K of water from above and below, (2) in confined spaces of nanometer in size and (3) in the bulk at temperatures above the homogeneous nucleation temperature. Altogether, the considered relaxation times from the data range nearly over 15 decades from 10-12 to 103 s. Assisted by the various features in the isothermal spectra and theoretical interpretation, these considerations enable us to conclude that relaxation of un-crystallized water is highly non-cooperative. The exponent Beta_K of its Kohlrausch stretched exponential correlation function is not far from having the value of one, and hence the deviation from exponential time decay is slight. Albeit the temperature dependence of its alpha-relaxation time being non-Arrhenius, the corresponding Tg-scaled temperature dependence has small steepness index m, likely less than 44 at Tg, and hence water is not 'fragile' as a glassformer. The separation in time scale of the alpha- and the beta-relaxations is small at Tg, becomes smaller at higher temperatures, and they merge together shortly above Tg. From all these properties and by inference, water is highly non-cooperative as a glass-former, it has short cooperative length-scale, and possibly minimal configurational entropy and small change of heat capacity at Tg compared with other organic glass-formers. This conclusion is perhaps unsurprising because water is the smallest molecule. Our deductions from the data rule out that the Tg of water is higher than 160 K, and suggest that it is close to the traditional value of 136 K.Comment: 22 pages, 7 figure

Charge transfer and weak bonding between molecular oxygen and graphene zigzag edges at low temperatures

Electron paramagnetic resonance (EPR) study of air-physisorbed defective carbon nano-onions evidences in favor of microwave assisted formation of weakly-bound paramagnetic complexes comprising negatively-charged O2- ions and edge carbon atoms carrying pi-electronic spins. These complexes being located on the graphene edges are stable at low temperatures but irreversibly dissociate at temperatures above 50-60 K. These EPR findings are justified by density functional theory (DFT) calculations demonstrating transfer of an electron from the zigzag edge of graphene-like material to oxygen molecule physisorbed on the graphene sheet edge. This charge transfer causes changing the spin state of the adsorbed oxygen molecule from S = 1 to S = 1/2 one. DFT calculations show significant changes of adsorption energy of oxygen molecule and robustness of the charge transfer to variations of the graphene-like substrate morphology (flat and corrugated mono- and bi-layered graphene) as well as edges passivation. The presence of H- and COOH- terminated edge carbon sites with such corrugated substrate morphology allows formation of ZE-O2- paramagnetic complexes characterized by small (<50 meV) binding energies and also explains their irreversible dissociation as revealed by EPR.Comment: 28 pages, 8 figures, 2 tables, accepted in Carbon journa

Dirac fermions on a disclinated flexible surface

A self-consisting gauge-theory approach to describe Dirac fermions on flexible surfaces with a disclination is formulated. The elastic surfaces are considered as embeddings into R^3 and a disclination is incorporated through a topologically nontrivial gauge field of the local SO(3) group which generates the metric with conical singularity. A smoothing of the conical singularity on flexible surfaces is naturally accounted for by regarding the upper half of two-sheet hyperboloid as an elasticity-induced embedding. The availability of the zero-mode solution to the Dirac equation is analyzed.Comment: 6 page

Interactive web system for a educational process management

В работе рассмотрены существующие в настоящее время web-системы дистанционного обучения, указаны их недостатки и достоинства. Рассмотрены web-сервисы Рунета для реализации некоторых видов образовательных технологий. Указаны общие принципы построения современной интерактивной web-системы для реализации и управления образовательным процессом. Рассмотрены основные модули разрабатываемой в настоящее время в ПГУТИ образовательной web-системы i-LMS, реализующей указанные принципы построения образовательного процесса и являющейся ядром системы дистанционного обучения.The paper discusses the currently existing web systems for a distance education, given their advantages and disadvantages. The Runet web-services for a different educational technologies are considered. The general principles of modern interactive web-system for the educational process implementation and management are indicated. The basic modules are currently being developed in PSUTI educational web-system (i-LMS) are considered. The i-LMS is the core of distance learning system

Modification of the experimental setup of the FTIR spectrometer and thirty-meter optical cell for measurements of weak selective and nonselective absorptions

The improvement of the experimental setup based on a Fourier spectrometer Bruker IFS-125 and a 30-meter multipass optical cell is described. The improvement includes the cell equipment with a system of automated adjustment of the number of beam passes without cell depressurization and ensures the cell work at high temperatures

Measurement of tensor analyzing powers in deuteron photodisintegration

New accurate measurement of tensor analyzing powers T20, T21 and T22 in deuteron photodisintegration has been performed. Wide-aperture non-magnetic detectors allowed to cover broad kinematic ranges in a single setup: photon energy = 25 to 600 MeV, proton emission angle in CM = 24 to 48 deg. and 70 to 102 deg. New data provide a significant improvement of a few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Improving the efficiency of sport and health-improving activity of the Siberian Federal University

Decrease in level of physical health of students is a serious problem of modern society. According to experts it occurs because of a lack of physical activity and low motivation of young people to regular exercises and sports. At the Siberian federal university this problem solve by carrying out the annual competition "Healthy lifestyle"Снижение уровня физического здоровья студентов является серьезной проблемой современного общества. По мнению специалистов это происходит из-за недостатка двигательной активности и низкой мотивации молодых людей к регулярным занятиям физкультурой и спортом. В Сибирском федеральном университете данную проблему решают путем проведения ежегодного конкурса «Здоровый образ жизни