Publications by authors named "Volchkov V"

Cold atom traps are at the heart of many quantum applications in science and technology. The preparation and control of atomic clouds involves complex optimization processes, that could be supported and accelerated by machine learning. In this work, we introduce reinforcement learning to cold atom experiments and demonstrate a flexible and adaptive approach to control a magneto-optical trap.

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Acoustic holograms are able to control pressure fields with high spatial resolution, enabling complex fields to be projected with minimal hardware. This capability has made holograms attractive tools for applications, including manipulation, fabrication, cellular assembly, and ultrasound therapy. However, the performance benefits of acoustic holograms have traditionally come at the cost of temporal control.

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The protein C is a small viral protein encoded in an overlapping frame of the P gene in the subfamily Orthoparamyxovirinae. This protein, expressed by alternative translation initiation, is a virulence factor that regulates viral transcription, replication, and production of defective interfering RNA, interferes with the host-cell innate immunity systems and supports the assembly of viral particles and budding. We expressed and purified full-length and an N-terminally truncated C protein from Tupaia paramyxovirus (TupV) C protein (genus Narmovirus).

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Abstract: The ability to load ultracold atoms at a well-defined energy in a disordered potential is a crucial tool to study quantum transport, and in particular Anderson localization. In this paper, we present a new method for achieving that goal by rf transfer of atoms in an atomic Bose-Einstein condensate from a disorder-insensitive state to a disorder-sensitive state. It is based on a bichromatic laser speckle pattern, produced by two lasers whose frequencies are chosen so that their light-shifts cancel each other in the first state and add up in the second state.

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To understand the dynamic interactions between the phosphoprotein (P) and the nucleoprotein (N) within the transcription/replication complex of the Paramyxoviridae and to decipher their roles in regulating viral multiplication, we characterized the structural properties of the C-terminal X domain (P) of Nipah (NiV) and Hendra virus (HeV) P protein. In crystals, isolated NiV P adopted a two-helix dimeric conformation, which was incompetent for binding its partners, but in complex with the C-terminal intrinsically disordered tail of the N protein (N), it folded into a canonical 3H bundle conformation. In solution, SEC-MALLS, SAXS and NMR spectroscopy experiments indicated that both NiV and HeV P were larger in size than expected for compact proteins of the same molecular mass and were in conformational exchange between a compact three-helix (3H) bundle and partially unfolded conformations, where helix α is detached from the other two.

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A series of pyridyl (pyridinium) substituted benzoxazoles were studied by steady state absorption, fluorescence spectroscopy, time-resolved fluorescence spectroscopy, fs pulse absorption and polarization spectroscopy, and quantum-chemical calculations. The spectral and kinetic parameters of the fluorophores in MeCN and EtOAc were obtained experimentally and were calculated by means of DFT and TDDFT methods. A scheme including four transient excited states was proposed for the interpretation of differential absorption kinetics of the charged fluorophores.

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The Crimean-Congo hemorrhagic fever virus (CCHFV) is the etiological agent of a severe hemorrhagic fever affecting Africa, Asia and southern Europe. Climate changes of recent decades have recently led to a rise in the distribution of this virus. Still few scientific data are available on the biology of its vector, the tick, or its own biology, but the proven presence of human infections observed in Spain and animals with positive serology in Corsica should focus our attention on this pathogen.

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The paper presents the results of a standard and complex treatment method using the peptide drug thymus thymalin in patients with COVID-19. One of the mechanisms of the immunomodulatory effect of thymalin is considered to be the ability of this peptide drug to influence the differentiation of human hematopoietic stem cells (HSCs). It was found that, as a result of standard treatment, patients in the control group showed a decrease in the concentration of the pro-inflammatory cytokine IL-6, C-reactive protein, D-dimer.

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The intricate lattice of Gn and Gc glycoprotein spike complexes on the hantavirus envelope facilitates host-cell entry and is the primary target of the neutralizing antibody-mediated immune response. Through study of a neutralizing monoclonal antibody termed mAb P-4G2, which neutralizes the zoonotic pathogen Puumala virus (PUUV), we provide a molecular-level basis for antibody-mediated targeting of the hantaviral glycoprotein lattice. Crystallographic analysis demonstrates that P-4G2 binds to a multi-domain site on PUUV Gc and may preclude fusogenic rearrangements of the glycoprotein that are required for host-cell entry.

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In the recent years, Ebola virus has been responsible for several major epidemics. Research efforts have allowed the development and evaluation in the field of several vaccine candidates. At present, two of them are already approved and used in the fight against the virus in the Democratic Republic of Congo.

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The femtosecond dynamics of photoinduced electron transfers in supramolecular donor-acceptor complexes between (E)-bis(18-crown-6)stilbene (D) and tetraperchlorates of 2,7-di(2-ammonioethyl)(2,7-diazapyrenium) (A1), 3,3'-(E)-ethene-1,2-diylbis[1-(3-ammoniopropyl)pyridinium] (A2) and 4,4'-ethane-1,2-diylbis[1-(3-ammoniopropyl)pyridinium] (A3) was studied. The acceptors A2 and A3 are weak electron acceptors whose first reduction potentials are equal to -1.0 and -1.

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Article Synopsis
  • The study investigates the complex structural features of Nipah virus phosphoprotein, which contains both ordered and intrinsically disordered regions, highlighting its role in the virus's ability to counteract host immune responses.
  • Using a combination of x-ray crystallography, NMR spectroscopy, and small angle x-ray scattering, the researchers achieved a detailed atomistic representation of the protein's structure, revealing that it forms tetramers.
  • The research also identifies specific regions in the phosphoprotein that interact with cellular components, providing insights into the protein’s functions and its coordination with other viral proteins, enhancing understanding of NiV's pathogenic mechanisms.*
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Acute coronary syndrome (ACS) in elderly and senile patients has a number of features and requires special attention to providing medical care. These patients is associated with significant comorbidity and atypical symptoms in the course of the disease. Diabetes mellitus is a common background disease in patients with ACS.

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We conducted an in-depth characterization of the Nipah virus (NiV) isolate previously obtained from a Pteropus lylei bat in Cambodia in 2003 (CSUR381). We performed full-genome sequencing and phylogenetic analyses and confirmed CSUR381 is part of the NiV-Malaysia genotype. In vitro studies revealed similar cell permissiveness and replication of CSUR381 (compared with 2 other NiV isolates) in both bat and human cell lines.

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Article Synopsis
  • An extensive study of elastic scattering time τ_{s} of matter waves in optical disordered potentials was conducted, utilizing experimental measurements and numerical simulations.
  • The research examines τ_{s} across a wide range of scattering regimes and highlights the significant impact of disorder statistics, particularly regarding the Ioffe-Regel-like criterion kl_{s}∼1.
  • The findings provide important insights that link experimental studies of complex transport phenomena, like Anderson localization, to underlying microscopic theories.
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Since the largest 2014⁻2016 Ebola virus disease outbreak in West Africa, understanding of Ebola virus infection has improved, notably the involvement of innate immune mediators. Amongst them, collectins are important players in the antiviral innate immune defense. A screening of Ebola glycoprotein (GP)-collectins interactions revealed the specific interaction of human surfactant protein D (hSP-D), a lectin expressed in lung and liver, two compartments where Ebola was found in vivo.

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Article Synopsis
  • The study explores the formation and properties of a supramolecular complex made from bis(18-crown-6)stilbene and 4,4'-bipyridine with specific ammoniopropyl N-substituents.
  • The research employs various spectroscopic techniques to demonstrate the binding of metal cations to the complex in acetonitrile, highlighting changes in absorption and fluorescence characteristics.
  • Results indicate rapid electron transfer processes and significant fluorescence quenching upon complexation, with quantum-chemistry calculations helping to clarify the relaxation mechanisms involved.
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The West African outbreak of Ebola virus (EBOV) infection during 2013-2016 highlighted the need for development of field-applicable therapeutic drugs for this infection. Here we report that mannoside glycolipid conjugates (MGCs) consisting of a trimannose head and a lipophilic chain assembled by a linker inhibit EBOV infection not only of human monocyte-derived dendritic cells and macrophages, but also of a number of susceptible cells. Analysis of the mode of action leads us to conclude that MGCs act directly on cells, notably by preventing virus endocytosis.

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Antibodies are promising post-exposure therapies against emerging viruses, but which antibody features and in vitro assays best forecast protection are unclear. Our international consortium systematically evaluated antibodies against Ebola virus (EBOV) using multidisciplinary assays. For each antibody, we evaluated epitopes recognized on the viral surface glycoprotein (GP) and secreted glycoprotein (sGP), readouts of multiple neutralization assays, fraction of virions left un-neutralized, glycan structures, phagocytic and natural killer cell functions elicited, and in vivo protection in a mouse challenge model.

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In 2018, the order Mononegavirales was expanded by inclusion of 1 new genus and 12 novel species. This article presents the updated taxonomy of the order Mononegavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.

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We report on the measurement of the spectral functions of noninteracting ultracold atoms in a three-dimensional disordered potential resulting from an optical speckle field. Varying the disorder strength by 2 orders of magnitude, we observe the crossover from the "quantum" perturbative regime of low disorder to the "classical" regime at higher disorder strength, and find an excellent agreement with numerical simulations. The method relies on the use of state-dependent disorder and the controlled transfer of atoms to create well-defined energy states.

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There are no approved medications for the treatment of Marburg or Ebola virus infection. In two previous articles (Martin et al., 2016, Martin et al.

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The dynamics of the excited states of a supramolecular complex with a charge transfer between (E)-bis(18-crown-6)stilbene and 4,4'-(E)-ethene-1,2-diylbis[1-(2-ammonioethyl)pyridinium]tetraperchlorate was studied by means of femtosecond transient spectroscopy. It is found that the characteristic time of the conversion of the locally excited (LE) state into the charge transfer (CT) state is equal to 300 fs, whereas the characteristic time of the conversion of the CT state into the ground state is equal to 400 fs. Due to host-guest interaction involving hydrogen bonds, the complex possesses high thermodynamic stability.

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IFITMs are broad antiviral factors that block incoming virions in endosomal vesicles, protecting target cells from infection. In the case of HIV-1, we and others reported the existence of an additional antiviral mechanism through which IFITMs lead to the production of virions of reduced infectivity. However, whether this second mechanism of inhibition is unique to HIV or extends to other viruses is currently unknown.

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The mononegaviral family has eight members assigned to three genera and seven species. Until now, genus and species demarcation were based on arbitrarily chosen filovirus genome sequence divergence values (≈50% for genera, ≈30% for species) and arbitrarily chosen phenotypic virus or virion characteristics. Here we report filovirus genome sequence-based taxon demarcation criteria using the publicly accessible PAirwise Sequencing Comparison (PASC) tool of the US National Center for Biotechnology Information (Bethesda, MD, USA).

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