1,150 results match your criteria: "Lebedev Physical Institute[Affiliation]"

Polysaccharide from Helianthus tuberosus L. as a potential radioprotector.

Biochem Biophys Res Commun

November 2024

Department of Cellular Mechanisms of Neuropathology, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, Russian Federation. Electronic address:

Introduction: Radioprotectors help to protect the body or at least minimize the negative consequences of radiation exposure. The present study aimed to assess the radioprotective potential of Helianthus tuberosus L. polysaccharide (HTLP) in vitality and micronuclei tests.

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Radiosensitivity to low and medium doses of X-ray radiation and the ability to induce a radiation adaptive response (RAR) of lymphocytes during in vitro irradiation of peripheral blood of patients with cancer were studied. The criterion for cytogenetic damage was the frequency of micronuclei (MN) in cytochalasin-blocked binucleate lymphocytes in culture. It was found that the spontaneous level of cytogenetic damage in the lymphocytes of patients was 2.

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Shock-ignition effect in indirect-drive inertial confinement fusion approach.

Phys Rev E

June 2024

Lebedev Physical Institute, Russian Academy of Sciences. Leninskii Prospect 53, Moscow 11991, Russia.

Shock-ignition effect in indirect-drive thermonuclear target is demonstrated on the base of numerical simulations. Thermonuclear gain (in relation to laser pulse energy) of a shock-ignited indirect-drive thermonuclear capsule is obtained, which is 22.5 times higher than that at a traditional spark ignition of the capsule with the same DT-fuel mass, wherein the shock-ignition laser pulse energy is 1.

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Isoprene affects new particle formation rates in environments and experiments also containing monoterpenes. For the most part, isoprene reduces particle formation rates, but the reason is debated. It is proposed that due to its fast reaction with OH, isoprene may compete with larger monoterpenes for oxidants.

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Raman microspectroscopy has become an effective method for analyzing the molecular appearance of biomarkers in skin tissue. For the first time, we acquired in vitro Raman spectra of healthy and malignant skin tissues, including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), at 532 and 785 nm laser excitation wavelengths in the wavenumber ranges of 900-1800 cm and 2800-3100 cm and analyzed them to find spectral features for differentiation between the three classes of the samples. The intensity ratios of the bands at 1268, 1336, and 1445 cm appeared to be the most reliable criteria for the three-class differentiation at 532 nm excitation, whereas the bands from the higher wavenumber region (2850, 2880, and 2930 cm) were a robust measure of the increased protein/lipid ratio in the tumors at both excitation wavelengths.

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It is known that various polysulfide species determine the color of sodalite-group minerals (haüyne, lazurite, and slyudyankaite), and that heating induces their transformations and color change, but the mechanisms of the transitions are unknown. A prominent example is the decay of cyclic S molecule. Using density-functional simulations, we explore its main decay pathways into the most probable final reaction products (the pairs of radical anions S⋅+S⋅ and S⋅+S⋅).

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Article Synopsis
  • - Direct laser acceleration (DLA) of electrons in near-critical density (NCD) plasmas is showing promise for high-energy laser applications, particularly in Inertial Confinement Fusion research.
  • - Experiments at the PHELIX sub-PW laser revealed efficient and highly directed betatron radiation from DLA electrons, producing around (3.4 ± 0.4)·10 photons per keV per sr at 10 keV photon energy.
  • - The results align well with particle-in-cell simulations, indicating that using low-density pre-ionized foams could lead to innovative advancements in high energy density research.
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We derive the probability representation of even and odd cat states of two and three qubits. These states are even and odd superpositions of spin-1/2 eigenstates corresponding to two opposite directions along the axis. The probability representation of even and odd cat states of an oscillating spin-1/2 particle is also discussed.

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In the study we thoroughly analyze diffraction effects accompanying the laser beam transmission through inhomogeneous plasma microstructures and simulate their diffraction patterns at the object output and in the near field. For this we solve the scalar Helmholtz wave equation in the first Rytov approximation and compute the diffraction spreading of the transmitted beam in free space. Diffraction effects are found to arise within the beam passage through inhomogeneous plasma microstructures even in the simplest approximations of the laser beam interaction with plasma.

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Molecular specificity in fluorescence imaging of cells and tissues can be increased by measuring parameters other than intensity. For instance, fluorescence lifetime imaging became a widespread modality for biomedical optics. Previously, we suggested using the fluorescence saturation effect at pulsed laser excitation to map the absorption cross-section as an additional molecular contrast in two-photon microscopy [Opt.

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Quinoxaline-based azamacrocycles: synthesis, AIE behavior and acidochromism.

Org Biomol Chem

June 2024

Université de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, École Normale Supérieure de Lyon, 46 allée d'Italie, 69342 Lyon, France.

The development of luminescent molecular materials has advanced rapidly in recent decades, primarily driven by the synthesis of novel emissive compounds and a deeper understanding of excited-state mechanisms. Herein, we report a streamlined synthetic approach to light-emitting diazapolyoxa- and polyazamacrocycles NCOQ and NCQ ( = 3-10; = 2, 3; = 2-5), incorporating a 2,3-diphenylquinoxaline residue (DPQ). This synthetic strategy based on macrocyclization through Pd-catalyzed amination reaction yields the target macrocycles in good or high yields (46-92%), enabling precise control over their structural parameters.

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Free crystal space in more than 600 chalcogenide structures taken out from the ICSD has been theoretically analyzed. As a result, wide voids and channels accessible for Na-ion migration were found in 236 structures. Among them, 165 compounds have not been described in the literature as Na-conducting materials.

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Proton therapy can treat tumors located in radiation-sensitive tissues. This article demonstrates the possibility of enhancing the proton therapy with targeted gold nanoparticles that selectively recognize tumor cells. Au-PEG nanoparticles at concentrations above 25 mg/L and 4 Gy proton dose caused complete death of EMT6/P cells in vitro.

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Studies of Fractal Microstructure in Nanocarbon Polymer Composites.

Polymers (Basel)

May 2024

Laboratory of Acoustic Microscopy, Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russia.

The in situ study of fractal microstructure in nanocarbon polymers is an actual task for their application and for the improvement in their functional properties. This article presents a visualization of the bulk structural features of the composites using pulsed acoustic microscopy and synchrotron X-ray microtomography. This article presents details of fractal structure formation using carbon particles of different sizes and shapes-exfoliated graphite, carbon platelets and nanotubes.

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Temperature, humidity, and ionisation effect of iodine oxoacid nucleation.

Environ Sci Atmos

May 2024

Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki Helsinki Finland

Article Synopsis
  • * The study found that particle formation rates due to ion-induced processes are stable across temperature changes, while neutral particle formation rates increase significantly when temperatures drop from +10 °C to -10 °C.
  • * Despite higher ionization rates, the formation of charged clusters is unlikely to be enhanced in upper tropospheric conditions; instead, neutral nucleation is expected to dominate, with humidity having little effect unless extremely low.
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The deceleration of a low-density beam of ions in plasma with developed ion-acoustic turbulence arising in strong electric field is described. The time and length of beam deceleration along and across the anisotropy axis of the wave number distribution of ion-acoustic waves are found. It is shown to what extent an increase in the strength of the electric field that generates turbulence is accompanied by a decrease in the time and length of braking.

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Nafion, a versatile polymer used in electrochemistry and membrane technologies, exhibits complex behaviors in saline environments. This study explores Nafion membrane's IR spectra during soaking and subsequent drying processes in salt solutions at various concentrations. Utilizing the principles of Fick's second law, diffusion coefficients for these processes are derived via exponential approximation.

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Article Synopsis
  • The study explored the effectiveness of combining local proton irradiation with intra-tumoral injections of two types of bismuth nanoparticles (one coated with Pluronic-F127 and the other with Silane-PEG).
  • Both types of nanoparticles significantly enhanced the antitumor effects of proton therapy when injected directly into the tumor, with greater effects observed at higher doses of nanoparticles and radiation.
  • These findings suggest a potential new approach for improving treatments for malignant tumors by using nanoparticles to increase the efficacy of radiation therapy.
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Excited States in Single-Stranded and i-Motif DNA with Silver Ions.

J Phys Chem B

May 2024

Department of Molecular Biophysics and Polymer Physics, Saint-Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia.

We have studied the excited states and structural properties for the complexes of cytosine (dC) chains with silver ions (Ag) in a wide range of the Ag to DNA ratio () and pH conditions using circular dichroism, steady-state absorption, and fluorescence spectroscopy along with the ultrafast fluorescence upconversion technique. We also calculated vertical electronic transition energies and determined the nature of the corresponding excited states in some models of the cytosine-Ag complexes. We show that (dC) chains in the presence of silver ions form a duplex stabilized by C-Ag-C bonds.

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Isocyanates play an essential role in modern manufacturing processes, especially in polyurethane production. There are numerous synthesis strategies for isocyanates both under industrial and laboratory conditions, which do not prevent searching for alternative highly efficient synthetic protocols. Here, we report a detailed theoretical investigation of the mechanism of sulfur dioxide-catalyzed rearrangement of phenylnitrile oxide into phenyl isocyanate, which was first reported in 1977.

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An X-pinch load driven by an intense current pulse (>100 kA in ∼100 ns) can result in the formation of a small radius, runaway compressional micro-pinch. A micro-pinch is characterized by a hot (>1 keV), current-driven (>100 kA), high-density plasma column (near solid density) with a small neck diameter (1-10 µm), a short axial extent (<1 mm), and a short duration (≲1 ns). With material pressures often well into the multi-Mbar regime, a micro-pinch plasma often radiates an intense, sub-ns burst of sub-keV to multi-keV x rays.

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Based on long-term monitoring data of the blazar, a new model for determining the parameters of this close binary supermassive black hole (SMBH) is proposed. The model uses the laws of celestial mechanics and results of harmonic analysis of observational data obtained mainly in the radio and optical wavelength ranges. Within the framework of the proposed model, the masses of SMBH companions, the values of their orbital elements, the parameters of the accretion disk, and its dimensions and thickness were determined.

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This paper delves into the significance of the tomographic probability density function (pdf) representation of quantum states, shedding light on the special classes of pdfs that can be tomograms. Instead of using wave functions or density operators on Hilbert spaces, tomograms, which are the true pdfs, are used to completely describe the states of quantum systems. Unlike quasi-pdfs, like the Wigner function, tomograms can be analysed using all the tools of classical probability theory for pdf estimation, which can allow a better quality of state reconstruction.

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Characterization of the fiber-like cortical cells in moss gametophytes.

Planta

March 2024

The Laboratory of Plant Cell Growth Mechanisms, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia.

Fiber-like cells with thickened cell walls of specific structure and polymer composition that includes (1 → 4)-β-galactans develop in the outer stem cortex of several moss species gametophytes. The early land plants evolved several specialized cell types and tissues that did not exist in their aquatic ancestors. Of these, water-conducting elements and reproductive organs have received most of the research attention.

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High X-ray absorption combined with photothermal properties make bismuth nanoparticles (Bi NP) a promising agent for multimodal cancer theranostics. However, the synthesis of Bi NP by the "classical" chemical methods has numerous limitations, including potential toxicity of the produced nanomaterials. Here we studied in vitro toxicity of laser-synthesized Bi NP coated with Pluronic F-127 on mouse fibroblast cell line L929.

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