First beams at neutrons for science Ledoux, X.; Foy, J. C.; Ducret, J. E. ...
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.
This study combines a literature survey and field observation data in an ad initio attempt to construct a process-based model of methane sink in upland soils including both the biological and ...physical aspects of the process. Comparison is drawn between the predicted sink rates and chamber measurements in several forest and grassland sites in the southern part of West Siberia. CH4 flux, total respiration, air and soil temperature, soil moisture, pH, organic content, bulk density and solid phase density were measured during a field campaign in summer 2014. Two datasets from literature were also used for model validation. The modeled sink rates were found to be in relatively good correspondence with the values obtained in the field. Introduction of the rhizospheric methanotrophy significantly improves the match between the model and the observations. The Q10 values of methane sink observed in the field were 1.2-1.4, which is in good agreement with the experimental results from the other studies. Based on modeling results, we also conclude that soil oxygen concentration is not a limiting factor for methane sink in upland forest and grassland ecosystems.
—
The stress-strain state of a thin adhesion layer in a layered composite is investigated under shear loading taking into account its possible elastoplastic deformation. The layer thickness is ...treated as a linear parameter. Analyzed is the analytical solution obtained on the basis of a simplified formulation of the problem in differential form. For small layer thicknesses, a generalized criterion for the transition to the state of plasticity associated with a linear parameter is proposed.
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.
A comprehensive study of the net annual balance of biogenic carbon-containing greenhouse gases has been performed for Lgov administrative district (Kursk oblast) in the chernozem zone of the European ...part of Russia. The data sources include field estimates of carbon dioxide and methane exchange between soil and atmosphere, above- and below-ground phytomass stocks, models parameterized on these data, official statistical and meteorological information, and published scientific sources. Sugar industry wastewater treatment infiltration fields are responsible for 26% of CH
4
emissions from the territory of the district, although they occupy only 0.04% of its area. The maximum of CO
2
emission from soils is observed at the soil water content of 30 vol %; above this value, methane emission begins to rise linearly reaching its maximum in waterlogged habitats, including those of infiltration fields. Another significant local source of methane is compost storages (22%). However, water reservoirs, oxbow lakes and ponds are the largest local source of CH
4
(43%). Among the main net sources of CO
2
emission, the combustion of fossil fuels by transport and agricultural machinery predominates (22.3%). In contrast to methane, whose emission is mainly determined by powerful point sources, the input of net fluxes of CO
2
positively correlates with their area. Currently observed relatively small net CO
2
flux in the district area (–6.4 g C m
–2
per year) is decisively overlapped by local methane sources (+95 g C–CO
2
equiv m
–2
per year). The influence of the land use and methods of calculation on the C balance of the territory under study and a way of its transformation into a carbon-neutral state are discussed.
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.
PDF
