Destruction is considered as a discrete thermomechanical process, in which the deformation of a solid body is achieved by changing the boundary stresses acting on the part of the volume being ...destroyed with the external load unchanged. On the basis of the proposed concept, a model for adhesive stratification of a composite material is constructed. When adhesive stratification is used, the stress state of one or two boundaries of the adhesive layer changes to zero if the bonds with the joined body are broken. As a result of the stratification, the interaction between the part of the composite, which may include an adhesive layer and the rest of the body stops. When solving the elastoplastic problem of cohesive stratification, the region in which the destruction criterion is achieved is identified. With the help of a repeated solution of the problem of subcritical deformation with the known law of motion of the boundary of the region, the distribution of the load (nodal forces) acting from the region to the body is located. The next step considers the change in the stress-strain state of the body in the process of destruction of the selected area. The elastoplastic problem is solved with a simple unloading of the formed surface of the body and preservation of the external load corresponding to the beginning of the process of destruction.
First beams at neutrons for science Ledoux, X.; Foy, J. C.; Ducret, J. E. ...
The European physical journal. A, Hadrons and nuclei,
08/2021, Letnik:
57, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The neutrons for science facility (NFS), the first operational experimental area of the new GANIL/SPIRAL-2 facility, received its first beams in December 2019. Proton-induced reaction cross-sections ...as well as neutron beam characteristics were measured during the first commissioning phases. The first results, showing the features of the facility, are presented here and compared with previously published data. The physics cases and the first accepted experiments are presented as well.
Upland forest ecosystems are recognized as net sinks for atmospheric methane (CH4), one of the most impactful greenhouse gases. Biological methane uptake in these ecosystems occurs due to the ...activity of aerobic methanotrophic bacteria. Russia hosts one-fifth of the global forest area, with the most extensive forest landscapes located in West Siberia. Here, we report seasonal CH4 flux measurements conducted in 2018 in three types of stands in West Siberian middle taiga–Siberian pine, Aspen, and mixed forests. High rates of methane uptake of up to −0.184 mg CH4 m−2 h−1 were measured by a static chamber method, with an estimated total growing season consumption of 4.5 ± 0.5 kg CH4 ha−1. Forest type had little to no effect on methane fluxes within each season. Soil methane oxidation rate ranged from 0 to 8.1 ng CH4 gDW−1 h−1 and was negatively related to water-filled pore space. The microbial soil communities were dominated by the Alpha- and Gammaproteobacteria, Acidobacteriota and Actinobacteriota. The major group of 16S rRNA gene reads from methanotrophs belonged to uncultivated Beijerinckiaceae bacteria. Molecular identification of methanotrophs based on retrieval of the pmoA gene confirmed that Upland Soil Cluster Alpha was the major bacterial group responsible for CH4 oxidation.
The Asymptotic Normalization Coefficient (ANC) method, has proven to be useful in retrieving the direct part of the radiative capture cross section for a number of reactions of astrophysical ...interest. In this work, some of the latest results obtained by the AsFin2 group of the LSN-INFN (Catania) and the OJR of the NPI (Řež) will be briefly discussed.
A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux ...from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies.
The paper dwells on a web-based information system "Test Solver" development for a programming contest. The results of analogs analysis are commented: closed or limited access to these systems; ...outdated interface and framework; complicated or unfriendly user interface; a system which is impossible or not easy to install on one's own server. The means used to establish the system are concerned. Web programming tools HTML5, PHP 7.2, MySQL 5.7, JQuery, AJAX and the Materialize framework were used for the development of that software. The modules are outlined; the algorithms of the system are set out, such as adding problems and arranging the contest. The stability research was carried out during the programming contest in Sholom-Aleichem Priamursky State University. 11 students took part in it and 15 problems for the contest were made up. The system "Test Solver" has proved to be a stable foundation for preparing competitions of similar types. The system "Test Solver" might be added with more flexible settings, the multi-stage leagues, implementation of system of points taking, including bonus ones. Also at the moment the software has tools for testing in programming languages C/C++, C#, Pascal. In the future it is planned to add Python, Java.
The review on the book of a former Emergency Ministry official and a philosophy professor Nikolai Mikhailovich Tverdynin published in 2020 in ANO Dialog Kul’tur publishing house analyses views on ...technology and technics that are manifested by acknowledged people across the globe. Two major beliefs are as follows: technophobic and technocratic. Dr. Tverdynin provides an unbiased description of their application to practice, as it becomes clear that technological threat awareness is a key feature of both attitudes. The book suggests that modern technical boom and its increasing involvement in education and personal development shall remain a vital, but not central method of acquiring new skills, as direct experience teaches not only to operate, but also to be a qualified worker and an individual even in sciences. Despite this and other opinion messages (remember the author’s past service), the book is not a journalist, but a scientific work, as it is void of ideology that accompanies technology. Overall, the book serves as an example of a rare accurate review of such an urgent issue and on such a thorough source collection.
The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive ...signature of a monoenergetic electron of energy slightly below the muon rest mass (104.967 MeV). The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. Any observation of a CLFV signal will be a clear indication of new physics. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter, and an external veto for cosmic rays surrounding the solenoid. The calorimeter plays an important role in providing particle identification capabilities, a fast online trigger filter, a seed for track reconstruction while working in vacuum, in the presence of 1-T axial magnetic field and in a harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach at these energies: 1) a time resolution better than 0.5 ns; 2) an energy resolution <10%; and 3) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674-undoped cesium iodine crystals read by two large area arrays of UV-extended silicon photomultipliers (SiPMs). We report here the construction and the test of the Module-0 prototype. The Module-0 has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati. Preliminary results of timing and energy resolution at normal incidence are shown. A discussion of the technical aspects of the calorimeter engineering is also reported in this paper.
Abstract
Methanogens and homoacetogens compete for available H2 in anoxic environments. The competitiveness of these microorganisms was studied by measuring H2 consumption kinetics (Vmax, Km, ...threshold) in different psychroactive strains as function of temperature. Methanogenic strains MSB and MSP and homoacetogenic Acetobacterium bakii, A. paludosum, A. fimetarium, A. tundrae, which were isolated from different low-temperature environments, were all able to grow and consume H2 in a temperature range of 4–30°C. The H2 thresholds steadily decreased with decreasing temperature in cultures of A. bakii, A. tundrae and strain MSB. In A. paludosum, A. fimetarium and especially in strain MSP, however, H2 thresholds again increased below 10–15°C. With exception of strain MSP at ≤10°C, H2 thresholds were generally lower in the methanogens (<2 Pa H2) than homoacetogens (<200 Pa H2). The measured thresholds decreased in parallel to those predicted from thermodynamic theory, and thus allowed the calculation of a critical Gibbs’ free energy required for H2 consumption, i.e. approximately −5 to −8 kJ mol−1, being similar for methanogens and homoacetogens. Vmax increased with temperature. The increase was more pronounced in the methanogenic strains than in A. bakii, but the values of the latter were generally higher. Km also increased with temperature and was higher in A. bakii (about 190–520 Pa H2) than in the methanogens (about 50–190 Pa H2). The values of H2 threshold, Vmax and Km, were used to compare the relative competitiveness of the different microorganisms over the entire temperature range using a kinetic model. A. bakii revealed a generally strong competitiveness for H2 at high H2 concentrations because of higher Vmax. It also outcompeted the methanogenic strain MSP at low H2 and low temperature. However, the capacity of the methanogens to compete with A. bakii for H2 increased with decreasing H2 concentration because of more favorable Km and threshold. In the methanogenic strain MSB, the H2 thresholds were generally lower than those of the homoacetogens irrespective of the temperature, and thus it outcompeted A. bakii. Methanogenic strain MSP, on the other hand, was outcompeted by A. bakii at low temperature because of insufficient psychrotolerance.
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