Vaccination against COVID-19 is the most effective method of controlling the spread of SARS-CoV-2 and reducing mortality from this disease. The development of vaccines with high protective activity ...against a wide range of SARS-CoV-2 antigenic variants remains relevant. In this regard, evaluation of the effectiveness of physical methods of virus inactivation, such as ultraviolet irradiation (UV) of the virus stock, remains relevant. This study demonstrates that the UV treatment of SARS-CoV-2 completely inactivates its infectivity while preserving its morphology, antigenic properties, and ability to induce the production of virus-neutralizing antibodies in mice through immunization. Thus, the UV inactivation of SARS-CoV-2 makes it possible to obtain viral material similar in its antigenic and immunogenic properties to the native antigen, which can be used both for the development of diagnostic test systems and for the development of an inactivated vaccine against COVID-19.
COMET Phase-I technical design report Abramishvili, R; Adamov, G; Allin, A ...
Progress of theoretical and experimental physics,
03/2020, Letnik:
2020, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Abstract
The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into ...electrons in the field of an aluminum nucleus ($\mu$–$e$ conversion, $\mu^{-}N \rightarrow e^{-}N$); a lepton flavor-violating process. The experimental sensitivity goal for this process in the Phase-I experiment is $3.1\times10^{-15}$, or 90% upper limit of a branching ratio of $7\times 10^{-15}$, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the $\mu$–$e$ conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.
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A modified method for culturing, concentrating, and purifying phage ϕ24B preparations was developed. In particular, a new lysogenic phage-producing strain lacking flagella was used, induction ...conditions were optimized, and purification in a sucrose gradient followed by concentration by deposition on a Freon 113 cushion were used. Using this method, a preparation of the Stx-converting bacteriophage ϕ24B was obtained, suitable for CryoEM direct analysis. Based on CryoEM data for this phage, the first primary three-dimensional reconstruction of its virions was performed. The structure of the phage ϕ24B tail is described. It was shown that the adsorption apparatus of this virus is represented by six thin lateral fibrils, and an axial fibril located at the end of the tail. This arrangement of the tail structure is consistent with the previously proposed hypothesis based on analysis of the receptor binding proteins (RBPs) of this bacteriophage.
Removal of 1,2-DCB from water emulsion using adsorbent catalysts was studied.Purification cycle comprises adsorption and regeneration by hydrodechlorination.The adsorption involves condensation and ...coalescence of 1,2-DCB drops on carbon.1,2-DCB adsorption was found to proceed by mechanism of volume filling of pores.Regeneration rate was shown to correlate with particle size of the active component.
Purification of emulsions of 1,2-dichlorobenzene (1,2-DCB) by carbon-based adsorbent catalysts has been studied. The cycle of purification includes: (1) adsorption of 1,2-DCB from the aqueous phase and (II) reductive regeneration by hydrodechlorination of the adsorbed 1,2-DCB by molecular hydrogen in the liquid phase. 1,2-DCB adsorption from aqueous solutions has been found to proceed by the mechanism of volume filling of pores. The rate of hydrodechlorination was shown to correlate with the particle size of the active component: the finer the particles, the higher the activity of the adsorbent catalyst. Pd/FAS with an average Pd particle size of 2.8nm was found to be the most efficient catalyst.
The paper reports an example of a successful upgrade of the JEOL JEM-2100 analytical transmission electron microscope to a low-resolution cryo-electron microscope, which can be used to optimize ...sample preparation and to assess preparation quality. As a result of the instrument upgrade, it is possible to obtain subnanometer resolution of protein molecule reconstructions (within 8 Å). The role of graphene and amorphous carbon substrates in preventing the effect of preferential orientation of protein particles in a frozen sample is discussed.
Cryo-electron microscopy (cryo-EM) is indispensable for the structural studies of enveloped viruses: dangerous pathogens of humans and animals. Yet, it requires highly specialized equipment as well ...as careful sample preparation. In this work, the capabilities of a JEOL JEM-2100 transmission electron microscope equipped with a cryo-transfer holder are used, and preliminary cryo-EM data for influenza A and B virus strains and SARS-CoV-2 inactivated with beta-propiolactone are presented. Image analysis allows us to (1) distinguish “empty” viral particles from “full” ones (containing nucleocapsid); (2) visualize the lipid bilayer of the viral envelope; (3) identify influenza virus surface antigens and the M1 protein layer combined with the inner lipid monolayer; and (4) distinguish different morphology of S-spikes on the surface of inactivated SARS-CoV-2 virions. The developed approach provides good image quality for both fundamental and applied research.
Prions form an infectious version of amyloid; they are involved in the pathogenesis of some human neurodegenerative diseases, including Alzheimer’s and Parkinson’s diseases. Yeast prions, in ...particular, the Sup35 protein, serve an effective model for studying the basic properties of amyloids. Strain versions of the prion form of Sup35 lie in the basis of the conformational diversity of the amyloid structures formed by it, which exhibit different biological properties. The spatial organization of the Sup35 prion has not yet been established. The structure of the strain version W of Sup35 prion protein, isolated ex vivo from yeast
Saccharomyces cerevisiae
, was studied by transmission electron microscopy (TEM). The parameters of the fibril were estimated, and its structure was reconstructed with a low resolution.
Construction on vacuum-compatible straw tracker for COMET Phase-I Nishiguchi, H.; Evtoukhovitch, P.; Fujii, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
Journal Article
Recenzirano
The COMET experiment at J-PARC aims to search for a lepton-flavour violating process of muon to electron conversion in a muonic atom, μ-e conversion, with a branching-ratio sensitivity of better than ...10−16, 4 orders of magnitude better than the present limit, in order to explore the parameter region predicted by most of well-motivated theoretical models beyond the Standard Model. The need for such an excellent sensitivity places several stringent requirements on the detector; (i) good momentum resolution, <2%, for 100 MeV/c electron, which is primarily limited by multiple scattering effect for this momentum region, and (ii) high rate capability, up to 5×109μ−/s muon beam by J-PARC. In order fulfil such requirements, we decided to develop the straw-base planar tracker which is operational in vacuum and made of an extremely light material. The COMET straw tracker consists of 10 mm diameter straw tube, longer than 1 m length, with 20μm-thick Mylar foil and 70 nm-thick aluminium cathode.
Recently, two big milestones, detector-performance verification by the full-scale prototype with 100 MeV/c electron beam, and start the assembly of final straw tracker for COMET Phase-I, were achieved. In this article, details of these two big milestones are provided. In addition, some prospects on the straw tracker development towards the COMET Phase-II are also given.
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