Display omitted
•5–500kW AC plasma torches for plasma chemical technologies are developed.•Air plasma gasification of coal, wood and RDF gives 43–55% of H2+CO in product gas.•Steam in the mix with ...other gases is using as plasma forming media in plasma torch.•Conversion is ∼99%, selectivity is ∼98%, during steam-CO2 plasma reforming of CH4.
The usage of plasma as a gasifying agent is efficient in waste to energy (WTE) gasification technologies. Over 20years the IEE RAS conducted researches in the field of Electrophysics, studied the properties of electrical discharges in gases and liquids in a wide range of pressures. AC plasma torches with long life time (thousands of hours) working on air, mixtures of steam, air, CO2 and CH4 have been developed. The power of these devices varies widely from 5 to 500kW and the thermal efficiency is 90–95%. Experimental results of wood, coal and refuse derived fuel (RDF) air plasma gasification are presented. The content of H2+CO is 43–55%vol., lower heating value (LHV) of product gas up to 6.61MJ/m3 when the specific energy consumption is 1.4–2.5MJ/kg of raw material. Methane reforming with usage of multi-gas plasma torch allows production of synthesis gas with H2 and CO selectivity up to 98%, methane conversion ∼99% and yield of soot is no more than 125mg/Nm3.
An original technique for describing excited states of electrons in crystal structure has been considered by an example of lithium. It is shown that the electron spectrum in lithium changes only ...slightly at large values of lattice parameter (up to 8.77 Bohr radii). The lifetimes of excited electrons of external
s
and
p
states differ significantly at lattice parameters
d
< 8.77 Bohr radii. A metastable crystalline state of bcc lithium is found, which barely depends on the excitation power at a lattice constant equal to 6.55 Bohr radii, corresponding to the bcc lattice constant of lithium in the ground state.
Ulcerative colitis (UC) is an inflammatory disease that affects the colon and rectum. Recently, evidence has emerged about the influence of microbiota on the development of this disease. However, ...studies on the role of intestinal microbiota in the pathogenesis of UC have been incomplete. In addition, there are no comprehensive studies of the causes of ulcerative colitis and data on the microbiological composition of the intestines of patients with ulcerative colitis in Russia. We carried out a study of the microbiological composition of the intestines of patients with ulcerative colitis and healthy individuals. We found significant changes in the bacteria genera and species in patients with UC compared with the control group using sequencing on the IonTorrent PGM system and subsequent data analysis. In our study we observed a significant increase of the genus Haemophilus, Olsenella, Prevotella, Cedecea, Peptostreptococcus, Faecalibacterium, Lachnospira, Negativibacillus, Butyrivibrio, and the species Bacteroides coprocola, Phascolarctobacterium succinatutens, Dialister succinatiphilus, Sutterella wadsworthensis, Faecalibacterium prausnitzii in patients with ulcerative colitis. In addition, in patients with ulcerative colitis there was a significant decrease in the genus Fusicatenibacter, Butyricimonas, Lactococcus, Eisenbergiella, Coprobacter, Cutibacterium, Falsochrobactrum, Brevundimonas, Yersinia, Leuconostoc and in the species Fusicatenibacter saccharivorans. We found confirmation of our data with literary sources and studies of UC. In addition, we discovered a few taxa such as Negativibacillus spp. and Falsochrobactrum spp. that have not been previously found in human stool samples. Our data confirm that more research is needed to understand the role of microbiome changes in the development of UC in different people populations.
Intestinal microbiota, ulcerative colitis, inflammatory bowel disease, sequencing, Russian population.
In slow collisions of two bare nuclei with the total charge number larger than the critical value, Zcr ≈ 173, the initially neutral vacuum can spontaneously decay into the charged vacuum and two ...positrons. Detection of the spontaneous emission of positrons would be the direct evidence of this fundamental phenomenon. However, the spontaneous emission is generally masked by the dynamical positron emission, which is induced by a strong time-dependent electric field created by the colliding nuclei. In our recent paper I. A. Maltsev et al., Phys. Rev. Lett. 123, 113401 (2019) it has been shown that the spontaneous pair production can be observed via measurements of the pair-production probabilities for a given set of nuclear trajectories. In the present paper, we have significantly advanced this study by exploring additional aspects of the process we are interested in. We calculate the positron energy spectra and find that these spectra can give a clear signature of the transition from the subcritical to the supercritical regime. It is found that focusing on a part of the positron spectrum, which accounts for the energy region where the spontaneously created positrons can contribute, allows us to get a much stronger evidence of the transition to the supercritical mode, making it very well pronounced in collisions, for example, of two uranium nuclei. The possibility of extending this study to collisions of bare nuclei with neutral atoms is also considered. The probability of a vacancy in the lowest-energy state of a quasimolecule which is formed in collisions of a bare U nucleus with neutral U and Cm atoms has been calculated. The relatively large values of this probability make such collisions suitable for observing the vacuum decay.
Abstract
Scintillation of pulsar radio signals caused by the interstellar medium can in principle be used for interstellar interferometry. Changes in the dynamic spectra as a function of pulsar ...longitude were in the past interpreted as having spatially resolved the pulsar magnetosphere. Guided by this prospect we used very long baseline interferometry observations of PSR B1237+25 with the Arecibo and Green Bank radio telescopes at 324 MHz and analyzed such scintillation at separate longitudes of the pulse profile. We found that the fringe phase characteristics of the visibility function changed quasi-sinusoidally as a function of longitude. Also, the dynamic spectra from each of the telescopes shifted in frequency as a function of longitude. Similar effects were found for PSR B1133+16. However, we show that these effects are not signatures of having resolved the pulsar magnetosphere. Instead, the changes can be related to the effect of low-level digitizing of the pulsar signal. After correcting for these effects the frequency shifts largely disappeared. Residual effects may be partly due to feed polarization impurities. Upper limits for the pulse emission altitudes of PSR B1237+25 would likely be well below the pulsar light cylinder radius. In view of our analysis, we think that observations with the intent of spatially resolving the pulsar magnetosphere need to be critically evaluated in terms of these constraints on interstellar interferometry.
The formation of lithium clusters in a helium flow is considered within the method considering the widths of energy levels. It is shown that lithium atoms in a plasma flow of inert helium form a ...cluster consisting of lithium only. In addition to lithium clusters with interatomic distances corresponding to interatomic distances of the equilibrium state, long-lived excitations of clusters with interatomic distances of 13 Bohr radii are observed. However, if excitations are removed, such systems transfer into the ground state or decay. In addition, it is observed that Li–He systems are long-lived under conditions of external excitations but quickly lose helium when these excitations are removed.
The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at ...different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.
In this paper, we discuss the concept of an analytic prolongation of a local Riemannian metric. We propose a generalization of the notion of completeness realized as an analytic prolongation of an ...arbitrary Riemannian metric. Various Riemannian metrics are studied, primarily those related to the structure of the Lie algebra 𝔤 of all Killing vector fields for a local metric. We introduce the notion of a quasi-complete manifold, which possesses the property of prolongability of all local isometries to isometries of the whole manifold. A classification of pseudo-complete manifolds of small dimensions is obtained. We present conditions for the Lie algebra of all Killing vector fields 𝔤 and its stationary subalgebra 𝔥 of a locally homogeneous pseudo-Riemannian manifold under which a locally homogeneous manifold can be analytically prolonged to a homogeneous manifold.
We study the analytic extension of a locally given Riemannian analytic metric to a metric of a nonextendable manifold. Various classes of locally isometric Riemannian analytic manifolds are studied. ...In each of these classes, the notion of the so-called pseudocomplete manifold is defined, which generalizes the notion of completeness of a manifold. A Riemannian analytic simply connected oriented manifold
is said to be pseudocomplete if it is nonextendable and there exists no locally isometric orientation-preserving covering mapping with a simply connected Riemannian manifold. Among the pseudocomplete manifolds, we single out the “most symmetric” regular pseudocomplete manifolds.
PDF
