The Advanced Laser Interferometer Gravitational-Wave Observatory and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst ...that followed the merger of this binary was also recorded by Fermi gamma-ray burst monitor and International Gamma-Ray Astrophysics Laboratory, indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the energy range of 1 TeV–100 PeV using the Baikal Gigaton Volume Detector. No neutrinos directionally coincident with the source were detected within ±500 s around the merger time, as well as during a 14-day period after the gravitational wave detection. We derived 90% C.L. upper limits on the neutrino fluence from GW170817 during a ±500 s window centered on the gravitational wave trigger time, and a 14-day window following the gravitational wave signal under the assumption of an
E
−2
neutrino energy spectrum.
Abstract
In recent years, the export volumes of Russian coal to the Asia-Pacific countries have been continuously growing. Coal dust is among of the strongest air pollutants. The article describes ...the study of airborne particulate matter in large transport hubs of the Primorsky Krai (Russian Far East): Nakhodka city and Posyet urban-type settlement using the method of measuring the mass and quantitative concentrations of particulate matter. It is shown that the air of these areas is polluted with particulate matter with diameter below 10 microns (PM10). The absolute dominance of 0.3 μm and 0.5 μm particles was revealed in the air of both areas. According to the Russian hygienic standard, the maximum permissible concentrations of PM were exceeded only at several sampling points. However, when compared to some international standards, the content of PM exceeded maximum permissible values at 42% of sampling points in Nakhodka city and at 43% of sampling points in Posyet settlement. It is advisable to install systems for continuous environmental monitoring of air pollution with coal dust particles near coal terminals.
The 1-cubic km deep Baikal-GVD underwater Cherenkov detector, a new-generation neutrino telescope, is now being deployed in Lake Baikal. The telescope’s status is described and the first physical ...results from its operation are presented.
The Baikal Gigaton Volume Detector (Baikal-GVD) is a km
3
-scale neutrino detector currently under construction in Lake Baikal, Russia. The detector consists of several thousand optical sensors ...arranged on vertical strings, with 36 sensors per string. The strings are grouped into clusters of 8 strings each. Each cluster can operate as a stand-alone neutrino detector. The detector layout is optimized for the measurement of astrophysical neutrinos with energies of
∼
100 TeV and above. Events resulting from charged current interactions of muon (anti-)neutrinos will have a track-like topology in Baikal-GVD. A fast
χ
2
-based reconstruction algorithm has been developed to reconstruct such track-like events. The algorithm has been applied to data collected in 2019 from the first five operational clusters of Baikal-GVD, resulting in observations of both downgoing atmospheric muons and upgoing atmospheric neutrinos. This serves as an important milestone towards experimental validation of the Baikal-GVD design. The analysis is limited to single-cluster data, favoring nearly-vertical tracks.
ABSTRACT
The existence of high-energy astrophysical neutrinos has been unambiguously demonstrated, but their sources remain elusive. IceCube reported an association of a 290-TeV neutrino with a ...gamma-ray flare of TXS 0506 + 056, an active galactic nucleus with a compact radio jet pointing to us. Later, radio-bright blazars were shown to be associated with IceCube neutrino events with high statistical significance. These associations remained unconfirmed with the data of independent experiments. Here, we report on the detection of a rare neutrino event with the estimated energy of 224 ± 75 TeV from the direction of TXS 0506 + 056 by the new Baikal Gigaton Volume Detector (Baikal-GVD) in April 2021. This event is the highest energy cascade detected so far by the Baikal-GVD neutrino telescope from a direction below horizon. The result supports previous suggestions that radio blazars in general, and TXS 0506 + 056 in particular, are the sources of high-energy neutrinos, and opens up the cascade channel for the neutrino astronomy.
The results of a study on the condition of the soil and vegetative cover of the fallow lands in steppe ecosystems of the Barguzin Hollow (Republic of Buryatia) are presented. We studied the soil ...encrustation process on fallow lands during moss–lichen cover formation on their surface, which resulted in the slowing of regenerative processes in plant communities. The main factors of the transformation of regeneration in the Barguzin Hollow were revealed. They differ from the classical scheme of restoration of plant communities that had been earlier identified for the fallow lands of the steppe zone of Kazakhstan, Southern Siberia, and Mongolia.
Oriented attachment of synthetic semiconductor nanocrystals is emerging as a route for obtaining new semiconductors that can have Dirac-type electronic bands such as graphene, but also strong ...spin-orbit coupling. The two-dimensional (2D) assembly geometry will require both atomic coherence and long-range periodicity of the superlattices. We show how the interfacial self-assembly and oriented attachment of nanocrystals results in 2D metal chalcogenide semiconductors with a honeycomb superlattice. We present an extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods. The honeycomb superlattices are atomically coherent and have an octahedral symmetry that is buckled; the nanocrystals occupy two parallel planes. Considerable necking and large-scale atomic motion occurred during the attachment process.
Oriented attachment of PbSe nanocubes can result in the formation of two-dimensional (2D) superstructures with long-range nanoscale and atomic order. This questions the applicability of classic ...models in which the superlattice grows by first forming a nucleus, followed by sequential irreversible attachment of nanocrystals, as one misaligned attachment would disrupt the 2D order beyond repair. Here, we demonstrate the formation mechanism of 2D PbSe superstructures with square geometry by using in situ grazing-incidence X-ray scattering (small angle and wide angle), ex situ electron microscopy, and Monte Carlo simulations. We observed nanocrystal adsorption at the liquid/gas interface, followed by the formation of a hexagonal nanocrystal monolayer. The hexagonal geometry transforms gradually through a pseudo-hexagonal phase into a phase with square order, driven by attractive interactions between the {100} planes perpendicular to the liquid substrate, which maximize facet-to-facet overlap. The nanocrystals then attach atomically via a necking process, resulting in 2D square superlattices.
We report on the specific properties of O- and OH-terminated Ti3C2Tx nanosheets contributing the permeance of MXene membranes with sorption type selectivity. Thin MXene selective layers on porous ...support demonstrated separation factor for NH3/H2 pair over 50 with ammonia permeance up to 5.0 m3(STP)∙m−2∙bar−1∙h−1 facilitated for humid medium and separation factor for H2O/N2 over 1000 with water permeance over 30 m3(STP)∙m−2∙bar−1∙h−1 close to P0(H2O). According to QCM and GIWAXS studies, high permeance and selectivity of membranes towards ammonia and water vapors are attributed both to ultimate sorption capacity for “basic” vapors and condensation-induced expansion of the interlayer space. Sorption capacity of MXene over 0.045 g∙g(MXene)−1 at 0.3P0 for both NH3 and H2O, significantly exceeds the sorption capacity for permanent gases. Calculations of the diffusion coefficient suggest labyrinthine transport of vapors. For permanent gases no variation of diffusion coefficients was observed with feed pressure, indicating Knudsen diffusion mechanism. Diffusion coefficient of strongly absorbed gases significantly increases with pressure. According to GIWAXS the effect was attributed to the increase of the interlayer distance with saturation of membrane with vapors and reduction of activation barriers for hopping diffusion. Demonstrated characteristics of Ti3C2Tx nanosheets makes it a promising candidate for developing of ammonia selective membranes for Haber-Bosch process membrane extractors.
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•Acidic properties of OH groups on MXene surface determine affinity to “basic” gases.•NH3 sorption coefficient attains 52 mmol/(m3·Pa), drastically exceed sorption for other gases.•Membranes with Ti3C2Tx selective layer were obtained by spin-coating technique.•Selectivity for a NH3/H2 exceeds 50 with ammonia permeance up to 3.91 m3 m−2 bar−1∙h−1.•The increase of interlayer distance with MXene saturation with vapors was founded.
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