A precision measurement of the ratio RK of the rates of kaon leptonic decays K±→e±ν and K±→μ±ν with the full data sample collected by the NA62 experiment at CERN in 2007–2008 is reported. The result, ...obtained by analysing ∼150000 reconstructed K±→e±ν candidates with 11% background contamination, is RK=(2.488±0.010)×10−5, in agreement with the Standard Model expectation.
The propagation of whistler waves in a magnetized plasma containing multiple small‐scale (100 m to 1 km) field‐aligned irregularities of enhanced electron density is considered analytically and by ...means of numerical simulations. Such systems of irregularities can develop in the upper ionosphere during the generation of density ducts by high‐frequency heating facilities and other types of active experiments. The simulation parameters are close to those of an active experiment where a whistler wave of 18 kHz emitted by a ground‐based very low frequency (VLF) transmitter was received onboard the DEMETER satellite at 700 km above the SURA heater. The study reveals a number of remarkable properties of the VLF waves' propagation, including the existence of specific waveguide modes of the small‐scale density structures and of a characteristic transverse size d0 of the irregularities. Irregularities with small density enhancements around 10–20% and transverse sizes larger than d0∼1 km can serve as separate waveguides for VLF waves. In their turn, single irregularities narrower than d0 cannot be considered as individual ducting structures. Numerical simulations show that, for the analysis of the electromagnetic whistlers' propagation, a system of closely spaced irregularities with scales narrower than d0 can be modeled by an equivalent ducting structure with a smoothed density profile. Such equivalent structure has the same ducting properties for whistlers and can be produced by averaging with a sliding window of a scale about d0 the original density distribution.
Key Points
Small‐scale field‐aligned ionospheric irregularities can serve as specific ducting structures for VLF whistlers
The ducting properties of systems from multiple small‐scale irregularities are studied both numerically and analytically
The cross‐field irregularity size exists, below which the system of irregularities can be replaced by “equivalent” smoothed density profile
Riboflavin (vitamin B2) is one of the most important water-soluble vitamins and a coenzyme involved in many biochemical processes. It has previously been shown that adjuvant therapy with flavin ...mononucleotide (a water-soluble form of riboflavin) correlates with normalization of clinically relevant immune markers in patients with COVID-19, but the mechanism of this effect remains unclear. Here, the antiviral and anti-inflammatory effects of riboflavin were investigated to elucidate the molecular mechanisms underlying the riboflavin-induced effects.
Riboflavin was evaluated for recombinant SARS-CoV-2 PLpro inhibition in an enzyme kinetic assay and for direct inhibition of SARS-CoV-2 replication in Vero E6 cells, as well as for anti-inflammatory activity in polysaccharide-induced inflammation models, including endothelial cells in vitro and acute lung inflammation in vivo.
For the first time, the ability of riboflavin at high concentrations (above 50 μM) to inhibit SARS-CoV-2 PLpro protease in vitro was demonstrated; however, no inhibition of viral replication in Vero E6 cells in vitro was found. At the same time, riboflavin exerted a pronounced anti-inflammatory effect in the polysaccharide-induced inflammation model, both in vitro, preventing polysaccharide-induced cell death, and in vivo, reducing inflammatory markers (IL-1β, IL-6, and TNF-α) and normalizing lung histology.
It is concluded that riboflavin reveals anti-inflammatory rather than antiviral activity for SARS-CoV-2 infection.
Riboflavin could be suggested as a promising compound for the therapy of inflammatory diseases of broad origin.
•Riboflavin inhibits the SARS-CoV-2 PLpro protease at concentrations above 50 μM.•Riboflavin prevents LPS-induced death of mouse SVEC-4-10 endothelial cells.•Riboflavin decreases inflammatory markers IL-1β, IL-6, and TNF-α levels in vivo.
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•The high efficiency of the new DMDCS catalyst for benzene alkylation with ethylene at moderate conditions in liquid phase is shown.•The equation of kinetics of ethylbenzene formation ...for controlling the new technological process is created.•The possibility of DMDCS catalyst application in industry is reported.
The kinetics of the alkylation of benzene with ethylene in the presence of dimethyldichlorosilane (DMDCS) are studied and a kinetic equation for this homogeneous irreversible reaction of the second order is created. The circulation of the DMDCS catalyst does not reduce its initial activity in relation to the formation of ethylbenzene and diethylbenzenes. The presence of moisture in the initial C6H6+C2H4+DMDCS mixture reduces the catalyst activity. The dehydration of the starting mixture by removal of moisture from benzene was carried out using an azeotropic distillation. A reaction mechanism for the benzene alkylation with ethylene in the presence of DMDCS is formulated based on the generalized quantum-chemical principle and the theory of groups. The participation of DMDCS in the process of hydrocarbon conversion is confirmed experimentally and theoretically for the first time.
Electromagnetic signals generated by a wide-aperture electron beam in the laboratory plasma under conditions limitedly modeling the interaction between waves and particles in the near-Earth plasma ...have been studied at the large-scale Krot device. The spectrum of electromagnetic radiation includes whistler noise, which is presumably due to the current instability, and discrete (narrowband) signals near harmonics of the electron cyclotron and plasma frequencies. It has been shown that narrowband signals with a positive frequency drift that are observed at the injection of the electron beam are caused by nonstationary variations of the plasma density due to an additional ionization of a neutral gas by accelerated electrons. These effects should be taken into account to interpret nonconventional forms of the dynamic spectrum in various laboratory experiments simulating processes in the Earth’s ionosphere and magnetosphere.
Single-domain antibodies (sdAbs, VHHs, or nanobodies) are a promising tool for the treatment of both infectious and somatic diseases. Their small size greatly simplifies any genetic engineering ...manipulations. Such antibodies have the ability to bind hard-to-reach antigenic epitopes through long parts of the variable chains, the third complementarity-determining regions (CDR3s). VHH fusion with the canonical immunoglobulin Fc fragment allows the Fc-fusion single-domain antibodies (VHH-Fc) to significantly increase their neutralizing activity and serum half-life. Previously we have developed and characterized VHH-Fc specific to botulinum neurotoxin A (BoNT/A), that showed a 1000-fold higher protective activity than monomeric form when challenged with five times the lethal dose (5 LD
) of BoNT/A. During the COVID-19 pandemic, mRNA vaccines based on lipid nanoparticles (LNP) as a delivery system have become an important translational technology that has significantly accelerated the clinical introduction of mRNA platforms. We have developed an mRNA platform that provides long-term expression after both intramuscular and intravenous application. The platform has been extensively characterized using firefly luciferase (Fluc) as a reporter. An intramuscular administration of LNP-mRNA encoding VHH-Fc antibody made it possible to achieve its rapid expression in mice and resulted in 100% protection when challenged with up to 100 LD
of BoNT/A. The presented approach for the delivery of sdAbs using mRNA technology greatly simplifies drug development for antibody therapy and can be used for emergency prophylaxis.
SARS-CoV-2 variants have evolved over time in recent years, demonstrating immune evasion of vaccine-induced neutralizing antibodies directed against the original S protein. Updated S-targeted ...vaccines provide a high level of protection against circulating variants of SARS-CoV-2, but this protection declines over time due to ongoing virus evolution. To achieve a broader protection, novel vaccine candidates involving additional antigens with low mutation rates are currently needed. Based on our recently studied mRNA lipid nanoparticle (mRNA-LNP) platform, we have generated mRNA-LNP encoding SARS-CoV-2 structural proteins M, N, S from different virus variants and studied their immunogenicity separately or in combination in vivo. As a result, all mRNA-LNP vaccine compositions encoding the S and N proteins induced excellent titers of RBD- and N-specific binding antibodies. The T cell responses were mainly specific CD4
T cell lymphocytes producing IL-2 and TNF-alpha. mRNA-LNP encoding the M protein did not show a high immunogenicity. High neutralizing activity was detected in the sera of mice vaccinated with mRNA-LNP encoding S protein (alone or in combinations) against closely related strains, but was undetectable or significantly lower against an evolutionarily distant variant. Our data showed that the addition of mRNAs encoding S and M antigens to mRNA-N in the vaccine composition enhanced the immunogenicity of mRNA-N and induced a more robust immune response to the N protein. Based on our results, we suggested that the S protein plays a key role in enhancing the immune response to the N protein when they are both encoded in the mRNA-LNP vaccine.
The low accessibility of natural gas fields and transporting pipelines requires portable online analyzers of the composition of natural gas, ensuring nearly chromatographic precision and capable of ...in situ analysis of a wide range of gases, including infrared-inactive ones (hydrogen, oxygen, nitrogen, chlorine). We have developed an express method of gas analysis meeting all the requirements for analysis of natural gas and its derivative mixtures using a portable 532 nm Raman spectrometer rigidly connected to a hollow-core crystal photonic fiber.
Improving the gas-dynamic and thermal modes of external heating of a sintering charge layer, including preheating the layer, igniting the charge, and subsequent heat treatment of the layer, is ...important for increasing the productivity of sintering machines, improving the sinter quality, and saving fuel. AF‑5 design solutions can fully achieve all these operations. When setting up the operation of the sintering machines, layer preheating is eliminated and the ignition hearth is moved onto the vacuum chamber no. 1. The hot air supply to the hearth, which prevents thermal shock when the layer emerges from under the hearth, is also eliminated.
In this study, because of charge heating with lime, deep throttling of the first vacuum chambers of the sintering machine, and the operation of the sintering machines at a charge layer height of 560 mm, the layer shrinkage was minimal. This finding confirmed the efficiency of the decision to eliminate charge layer preheating. The influence of the charge layer height on the operating mode of the ignition hearth is discussed. The ineffectiveness of sintering machine equipment used worldwide with two parallel prefabricated collectors, instead of one, and a sectional design is experimentally established. Technical solutions to eliminate the negative consequences of dismantling the waste gas recirculation system are clarified. Moreover, recommendations for modernizing prefabricated collectors for stage 1 gas purification from dust are detailed. The advantages of using exhaust guide vanes instead of throttling vacuum chambers after the ignition hearth have been experimentally demonstrated. The features of the operation of sintering machine exhausts in a single scheme with a desulfurization unit are considered.
Aims.
EXor-type objects are protostars that display powerful UV-optical outbursts caused by intermittent and powerful events of magnetospheric accretion. These objects are not yet well investigated ...and are quite difficult to characterize. Several parameters, such as plasma stream velocities, characteristic densities, and temperatures, can be retrieved from present observations. As of yet, however, there is no information about the magnetic field values and the exact underlying accretion scenario is also under discussion.
Methods.
We use laboratory plasmas, created by a high power laser impacting a solid target or by a plasma gun injector, and make these plasmas propagate perpendicularly to a strong external magnetic field. The propagating plasmas are found to be well scaled to the presently inferred parameters of EXor-type accretion event, thus allowing us to study the behaviour of such episodic accretion processes in scaled conditions.
Results.
We propose a scenario of additional matter accretion in the equatorial plane, which claims to explain the increased accretion rates of the EXor objects, supported by the experimental demonstration of effective plasma propagation across the magnetic field. In particular, our laboratory investigation allows us to determine that the field strength in the accretion stream of EXor objects, in a position intermediate between the truncation radius and the stellar surface, should be of the order of 100 G. This, in turn, suggests a field strength of a few kilogausses on the stellar surface, which is similar to values inferred from observations of classical T Tauri stars.
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