109 research outputs found
The nexus of soil radon and hydrogen dynamics and seismicity of the northern flank of the Kuril-Kamchatka subduction zone
The comparison of kinematics and dynamic parameters of radon and molecular hydrogen concentration in subsoil
air on the stations network at the Petropavlovsk-Kamchatsky geodynamic proving ground with seismicity
of the northern flank of the Kuril-Kamchatka subduction zone was fulfilled in the period from July till August
2004. On the basis of correlation analysis of the regional seismicity and variations of radon flux density calculated
using the data of gas-discharge counters of STS-6 type and SSNTDs it was shown that the radon mass
transfer abnormal variations are conditioned by both regional seismicity in total and the subduction zone of proving
ground. The azimuths of «geodeformation waves» coming to the registration points are calculated during
clearly expressed anomaly beginnings, which coincide with directions to earthquake epicenters taking place at
the same time. The geochemical anomalies recorded are presumptively deformative by nature and can be conditioned
by processes of «quasi-viscous» flow of the lithosphere during rearrangement of tectonic stress fields of
the subduction zone. The short-term (predicted time Τ <14 days) precursor of the earthquakes swarm was revealed
in hydrogen dynamics on August, 4-5 (four earthquakes had M≥5.3 and epicentral distance about 130 km
from the Paratunka base station)
Spectroscopic investigations of dispersion-shifted fiber with thin active Bi-doped ring and high nonlinear refractive index
A germanium-doped silica-core fiber with an active region in the form of a thin ring of silica doped with bismuth ions was fabricated. Bismuth doping in the ring surrounding the core allows to stabilize bismuth in silica glass, and it does not impose any restrictions on the composition of the core. The bismuth concentration in the ring is less than 0.2 wt.%. The GeO2 concentration in the core is more than 15 mol.%. A high germanium concentration in the core allows to shift the zero dispersion wavelength to 1860 nm and to obtain a high nonlinear refractive index (n2 more than 3,2*10-20 m2/W). Spectroscopic investigations were carried out in the visible and near infrared (800-1700 nm) spectral range. Despite the small concentration of bismuth, we observed the absorption and luminescence characteristic bands, confirming the presence of bismuth active centers in silica glass. Upon pumping at 1350 nm the on/off gain spectrum was measured on a 20-m fiber. The gain was observed throughout investigated range of 1430-1530 nm. The maximal gain of ~9.5 dB was obtained near 1430 nm. The results of the spectroscopic investigations of the fiber with a thin active Bi-doped ring showed prospects of the creation and application of such fiber type for laser and nonlinear optics
Microstructure formation in cast TiZrHfCoNiCu and CoNiCuAlGaIn high entropy shape memory alloys: A comparison
The present study is dedicated to the microstructure characterization of the as-cast high entropy intermetallics that undergo a martensitic transformation, which is associated with the shape memory effect. It is shown that the TiZrHfCoNiCu system exhibits strong dendritic liquation, which leads to the formation of martensite crystals inside the dendrites. In contrast, in the CoNiCuAlGaIn system the dendritic liquation allows the martensite crystals to form only in interdendritic regions. This phenomenon together with the peculiarities of chemical inhomogeneities formed upon crystallization of this novel multicomponent shape memory alloys systems will be analyzed and discussed
Non-Equilibrium Evolution Thermodynamics Theory
Alternative approach for description of the non-equilibrium phenomena arising
in solids at a severe external loading is analyzed. The approach is based on
the new form of kinetic equations in terms of the internal and modified free
energy. It is illustrated by a model example of a solid with vacancies, for
which there is a complete statistical ground. The approach is applied to the
description of important practical problem - the formation of fine-grained
structure of metals during their treatment by methods of severe plastic
deformation. In the framework of two-level two-mode effective internal energy
potential model the strengthening curves unified for the whole of deformation
range and containing the Hall-Petch and linear strengthening sections are
calculated.Comment: 7 pages, 1 figur
IR Bismuth active centers in optical fibers: Combined excitation-emission spectroscopy
3D excitation-emission luminescence spectra of Bi-doped optical fibers of
various compositions were measured in a wide wavelength range 450-1700 nm. Such
luminescence spectra were obtained for Bi-doped pure silica and germania
fibers, and for Bi-doped Al- or P-codoped silica fibers (at room and liquid
nitrogen temperatures). The energy level schemes of IR bismuth active centers
in pure silica and germania core fibers were derived from spectra obtained. The
energy level schemes similarity of bismuth active centers in these two types of
fibers was revealed.Comment: 12pages, 7 figures, 5 table
Sarilumab in patients admitted to hospital with severe or critical COVID-19: a randomised, double-blind, placebo-controlled, phase 3 trial
Background: Elevated proinflammatory cytokines are associated with greater COVID-19 severity. We aimed to assess safety and efficacy of sarilumab, an interleukin-6 receptor inhibitor, in patients with severe (requiring supplemental oxygen by nasal cannula or face mask) or critical (requiring greater supplemental oxygen, mechanical ventilation, or extracorporeal support) COVID-19. Methods: We did a 60-day, randomised, double-blind, placebo-controlled, multinational phase 3 trial at 45 hospitals in Argentina, Brazil, Canada, Chile, France, Germany, Israel, Italy, Japan, Russia, and Spain. We included adults (≥18 years) admitted to hospital with laboratory-confirmed SARS-CoV-2 infection and pneumonia, who required oxygen supplementation or intensive care. Patients were randomly assigned (2:2:1 with permuted blocks of five) to receive intravenous sarilumab 400 mg, sarilumab 200 mg, or placebo. Patients, care providers, outcome assessors, and investigators remained masked to assigned intervention throughout the course of the study. The primary endpoint was time to clinical improvement of two or more points (seven point scale ranging from 1 [death] to 7 [discharged from hospital]) in the modified intention-to-treat population. The key secondary endpoint was proportion of patients alive at day 29. Safety outcomes included adverse events and laboratory assessments. This study is registered with ClinicalTrials.gov, NCT04327388; EudraCT, 2020-001162-12; and WHO, U1111-1249-6021. Findings: Between March 28 and July 3, 2020, of 431 patients who were screened, 420 patients were randomly assigned and 416 received placebo (n=84 [20%]), sarilumab 200 mg (n=159 [38%]), or sarilumab 400 mg (n=173 [42%]). At day 29, no significant differences were seen in median time to an improvement of two or more points between placebo (12·0 days [95% CI 9·0 to 15·0]) and sarilumab 200 mg (10·0 days [9·0 to 12·0]; hazard ratio [HR] 1·03 [95% CI 0·75 to 1·40]; log-rank p=0·96) or sarilumab 400 mg (10·0 days [9·0 to 13·0]; HR 1·14 [95% CI 0·84 to 1·54]; log-rank p=0·34), or in proportions of patients alive (77 [92%] of 84 patients in the placebo group; 143 [90%] of 159 patients in the sarilumab 200 mg group; difference −1·7 [−9·3 to 5·8]; p=0·63 vs placebo; and 159 [92%] of 173 patients in the sarilumab 400 mg group; difference 0·2 [−6·9 to 7·4]; p=0·85 vs placebo). At day 29, there were numerical, non-significant survival differences between sarilumab 400 mg (88%) and placebo (79%; difference +8·9% [95% CI −7·7 to 25·5]; p=0·25) for patients who had critical disease. No unexpected safety signals were seen. The rates of treatment-emergent adverse events were 65% (55 of 84) in the placebo group, 65% (103 of 159) in the sarilumab 200 mg group, and 70% (121 of 173) in the sarilumab 400 mg group, and of those leading to death 11% (nine of 84) were in the placebo group, 11% (17 of 159) were in the sarilumab 200 mg group, and 10% (18 of 173) were in the sarilumab 400 mg group. Interpretation: This trial did not show efficacy of sarilumab in patients admitted to hospital with COVID-19 and receiving supplemental oxygen. Adequately powered trials of targeted immunomodulatory therapies assessing survival as a primary endpoint are suggested in patients with critical COVID-19. Funding: Sanofi and Regeneron Pharmaceuticals
Magnetic and Electrical Effects of the Explosive Stage of the Stromboli Volcanic Eruption (July 3, 2019, Italy)
Modeling of the ductile-brittle transition in porous metallic materials under conditions of crack resistance tests
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