The boundary value problem of determining hydrogen concentration and the stress state in a titanium shell

Decreasing physical and mechanical properties of materials in contact with an aggressive environment is one of the factors determining the strength and service life of various structures. In this paper, the effect of a hydrogen-containing medium on the mechanical properties and stress state of a titanium alloy shell is shown. For this purpose, the diffusion boundary-value problem is solved and the distribution of hydrogen concentration over the shell wall thickness is determined. Then the boundary-value problem of statics is solved, and the stress state of the shell structure is determined before and after hydrogenation. The object of study is presented in the form of a shell of revolution loaded with internal pressure and working in a hydrogen-containing medium. © 2019 Author(s)

Surface-enhanced optical third-harmonic generation in Ag island films

Surface-enhanced optical third-harmonic generation (THG) is observed in silver island films. The THG intensity from Ag nanoparticles is enhanced by more than two orders of magnitude with respect to the THG intensity from a smooth and homogeneous silver surface. This enhancement is attributed to local plasmon excitation and resonance of the local field at the third-harmonic wavelength. The diffuse and depolarized component of the enhanced THG is associated with the third-order hyper-Rayleigh scattering in a 2-D random array of silver nanoparticles.Comment: 4 pages, 2 figure

The stressed state of a titanile shell operating in a medium with hydrogen

Improving reliability in the operation of equipment operating in a water-containing environment is associated with solving the problem of hydrogen embrittlement of metals. In the absence of a rigorous physical theory, it becomes necessary to predict the carrying capacity of various structures based on the available experimental data showing a decrease in the mechanical properties of materials in contact with hydrogen. In this paper, a solution is given to a physically nonlinear problem of determining stresses in a titanium shell. When integrating resolving equations, the method of SK Godunov's discrete orthogonalization is applied. Due to the fact that hydrogen most noticeably reduces the plastic properties of metals, the construction has revealed a dangerous point with a maximum intensity value of tangential stresses. The regularities of changes in the intensity of shear deformations at the dangerous point of the shell during an emergency pressure increase in the apparatus have been found. It is shown that an emergency pressure increase in the shell may lead to the appearance of plastic deformation zones, and the effect of hydrogen is manifested in the reduction of the breaking load. © Published under licence by IOP Publishing Ltd

THE CONDITION OF BRAIN HEMO DYNAMICS AT PATIENTS WITH OBLITERATING ATHEROSCLEROSIS OF ARTERIES OF THE BOTTOM EXTREMITIES

Purpose: Examine the state of cerebral hemodynamics in patients with obliterative atherosclerosis of the lower extremities.Materials and methods: Patients were divided into 3 groups depending on the degree of chronic limb ischemia. In one group (67 people) included patients with B II degree of ischemia. The 2nd group (36 patients) included patients with grade III ischemia. In the 3rd group entered 21 patients with a decompensation of collateral blood circulation into the extremities, being accompanied the expressed pain syndrome (the IV degree of ischemia). State of the blood flow was assessed by Doppler ultrasound data on the levels of the extracranial and intracranial arteries brachycephalic departments.Results: In patients with decompensation of collateral circulation of the lower limbs (group 3), a significant decrease in the rate of blood flow in the internal carotid arteries in comparison with the indicators of all other groups .Summary: Severe chronic ischemia of the lower limbs should be seen not only as a negative factor for the lower extremities, but also as a factor in reducing the risk of cerebral perfusion and significant deterioration of autoregulatory reserve of cerebral hemodynamics

Nontrivial dependence of dielectric stiffness and SHG on dc bias in relaxors and dipole glasses

Dielectric permittivity and Second Harmonic Generation (SHG) studies in the field-cooled mode show a linear dependence of dielectric stiffness (inverse dielectric permittivity) on dc bias in PMN-PT crystals and SHG intensity in KTaO$_{3}$:Li at small Li concentrations. We explain this unusual result in the framework of a theory of transverse, hydrodynamic-type, instability of local polarization.Comment: 5 figure

Photon Filamentation in Resonant Media with High Fresnel Numbers

The phenomenon of turbulent photon filamentation occurs in lasers and other active optical media at high Fresnel numbers. A description of this phenomenon is suggested. The solutions to evolution equations are presented in the form of a bunch of filaments chaotically distributed in space and having different radii. The probability distribution of patterns is defined characterizing the probabilistic weight of different filaments. The most probable filament radius and filament number are found, being in good agreement with experiment.Comment: Revtex file, 5 pages. Reference to the English edition of the journal is give

COMPARATIVE RESEARCH OF ENALAPRIL AND ATENOLOL ANTIHYPERTENSIVE EFFICACY IN HIGH RISK PATIENTS

Aim. To evaluate the effecacy of enalapril (Enam, Dr.Reddy’s, India) and atenolol (Tenormin, AstraZeneca, UK) and their influence on processes of cardiovascular system remodeling in comparative research in patients with arterial hypertension. Material and methods. 38 patients with arterial hypertension stage II were examined. 21 patients were treated with enalapril (10-40 mg\d) and 17 – with atenolol (50-100 mg\d). Duration of therapy was 24 weeks.  A daily monitoring of blood pressure and echocardiography were made before and after the treatment. Spontaneous erythrocyte aggregation and deformability, spontaneous platelet aggregation and adhesive property of neutrophils were also estimated. A number of leucocytes carrying activation markers and expressing adhesive molecules was calculated. The plasma concentration of adhesive molecules (ICAM-1) and von Willebrand protein as well as serum concentration of N-terminal peptide of procollagen type III was also estimated. Results. Enalapril versus atenolol improved blood rheology, reduced functional leucocytes activity, plasma concentration of von Willebrand protein and intercellular adhesive molecules. The reduction in collagen III synthesis activity in enalapril therapy was proved. A significant regress of left ventricle hypertrophy due to enalapril treatment was related with favorable non-hemodynamic effects. Conclusion. The research revealed that the blockage of tissue rennin-angiotensin system is very important in prevention of cardiovascular complications especially in high risk patients

Revisiting the 'LSND anomaly' II: critique of the data analysis

This paper, together with a preceding paper, questions the so-called 'LSND anomaly': a 3.8 sigma excess of antielectronneutrino interactions over standard backgrounds, observed by the LSND Collaboration in a beam dump experiment with 800 MeV protons. That excess has been interpreted as evidence for the antimuonneutrino to antielectronneutrino oscillation in the \Deltam2 range from 0.2 eV2 to 2 eV2. Such a \Deltam2 range is incompatible with the widely accepted model of oscillations between three light neutrino species and would require the existence of at least one light 'sterile' neutrino. In a preceding paper, it was concluded that the estimates of standard backgrounds must be significantly increased. In this paper, the LSND Collaboration's estimate of the number of antielectronneutrino interactions followed by neutron capture, and of its error, is questioned. The overall conclusion is that the significance of the 'LSND anomaly' is not larger than 2.3 sigma.Comment: 30 pages, 16 figures, 6 table

Reply to 'Corrections to the HARP-CDP Analysis of the LSND Neutrino Oscillation Backgrounds'

The alleged mistakes in recent papers that reanalyze the backgrounds to the 'LSND anomaly' do not exist. We maintain our conclusion that the significance of the 'LSND anomaly' is not 3.8 sigma but not larger than 2.3 sigma.Comment: 3 page

Cross-sections of large-angle hadron production in proton- and pion-nucleus interactions VII: tin nuclei and beam momenta from \pm3 GeV/c to \pm15 GeV/c

We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% nuclear interaction length thick stationary tin target, of proton and pion beams with momentum from \pm3 GeV/c to \pm15 GeV/c. Results are given for secondary particles with production angles between 20 and 125 degrees. Cross-sections on tin nuclei are compared with cross-sections on beryllium, carbon, copper, tantalum and lead nuclei.Comment: 68 pages, 13 figure