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

The study explore machine learning (ML) techniques to predict temperature-dependent photoluminescence (PL) spectra in colloidal CdSe nanoplatelets (NPLs), leveraging polynomial regression models trained on experimental data from 85 to 270 K spanning temperatures to forecast PL spectra backward to 0 K and forward to 300 K. 6th-degree polynomial models with Tweedie regression were optimal for band energy ([Formula: see text]) predictions up to 300 K, while 9th-degree models with LassoLars and Linear Regression regressors were suitable for backward predictions to 0 K. For exciton energy ([Formula: see text]), the Lasso model of degree 5 and the Ridge model of degree 4 performed well up to 300 K, while the Tweedie model of degree 2 and Theil-Sen model of degree 2 showed promise for predictions to 0 K.

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Unlabelled: The development of new drugs in nuclear medicine for diagnosis or treatment (chemotherapy) of brain tumors, in particular gliomas, is inextricably linked with the use of tumor models in animals (usually rats).

Objective: To compare the widely used glioma cell model C6 and the new experimental tissue model of glioblastoma 101.8.

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In pursuit of identifying less toxic hybrid compounds suitable for optoelectronic applications, we synthesized a novel homopiperazinium bromoantimonate(III), (CHN){SbBr}. It readily crystallized from an aqueous hydrobromic acid solution and was found to be stable both in air and upon heating up to 175 °C. The crystal structure of the new bromoantimonate(III) consisted of {SbBr} zigzag chains, which were composed of strongly trigonally distorted SbBr octahedral anions and CHN dications.

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Direct numerical simulation of three-dimensional acoustic turbulence has been performed for both weak and strong regimes. Within the weak turbulence, we demonstrate the existence of the Zakharov-Sagdeev spectrum ∝k^{-3/2} not only for weak dispersion but in the nondispersion (ND) case as well. Such spectra in the k space are accompanied by jets in the form of narrow cones.

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We analyzed spin polarization dynamics in a two-dimensional system of spin 1/2 charged particles with spin-orbit interaction in perpendicular magnetic field in the presence of external noise. It was shown that spin polarization reveals quantum oscillations, collapses, and revivals. The hierarchy of time scales corresponding to quantum oscillations, collapses, and revivals was identified and analyzed.

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Article Synopsis
  • δ-BiO-based materials are studied for their potential use in solid oxide fuel cells due to their high electrical conductivity and thermal stability.
  • Extensive research on BiWO compounds explored their thermal stability, polymorphism, and conduction properties, revealing that these materials are dense and thermally stable up to 900 °C.
  • The study combined theoretical and experimental approaches to analyze electrical transport mechanisms, confirming that the predominant conduction type in BiWO is anionic, achieving significant conductivity values at high temperatures.
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LiNbO crystal with a lithium composition gradient of Li/Nb = 0.8 wt%/cm (LiNbO) were obtained. A monotonic change in the edge of the UV absorption edge is observed when scanning the surface of the gradient crystal along the growth direction.

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The coherent spin dynamics of electrons and holes in CsPbI perovskite nanocrystals in a glass matrix are studied by the time-resolved Faraday ellipticity technique in magnetic fields up to 430 mT across a temperature range from 6 K to 120 K. The Landé -factors and spin dephasing times are evaluated from the observed Larmor precession of electron and hole spins. The nanocrystal size in the three studied samples varies from about 8 to 16 nm, resulting in exciton transition varying from 1.

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  • This study aimed to determine the relative biological effectiveness (RBE) of carbon ion beams in particle radiotherapy, focusing on different regions of the Bragg curve while comparing it to X-ray radiation.
  • SHK mice were irradiated at varying doses (0-1.5 Gy for cytogenetic damage and 6.5 Gy for survival) to assess the effects of carbon ions in the Bragg peak using different widths of the spread-out Bragg peak (SOBP).
  • Results indicated that RBE values were lower before and after the Bragg peak (0.8-0.9), but increased significantly in the low-dose region (1.1-1.7 for 10-mm SOBP), suggesting
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This study addresses the challenge of modeling temperature-dependent photoluminescence (PL) in CdS colloidal quantum dots (QD), where PL properties fluctuate with temperature, complicating traditional modeling approaches. The objective is to develop a predictive model capable of accurately capturing these variations using Long Short-Term Memory (LSTM) networks, which are well suited for managing temporal dependencies in time-series data. The methodology involved training the LSTM model on experimental time-series data of PL intensity and temperature.

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Polycystic ovary syndrome (PCOS) is a complex disorder that impacts both the endocrine and metabolic systems, often resulting in infertility, obesity, insulin resistance, and cardiovascular complications. The aim of this study is to investigate the role of intestinal flora and its metabolites, particularly short-chain fatty acids (SCFAs), in the development of PCOS, and to assess the effects of metformin therapy on these components. SCFA levels in fecal and blood samples from women with PCOS (n=69) and healthy controls (n=18) were analyzed using Gas Chromatography-Mass Spectrometry (GC/MS) for precise measurement.

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Article Synopsis
  • * Raman spectroscopy is highlighted as an effective method for monitoring changes in the structure of these glycol solutions over time, especially how water content decreases on substrates.
  • * The study also reveals that the water content reduction affects the presence of certain molecular conformations in the glycols and demonstrates that a specific laser wavelength (1064 nm) is effective for analyzing antifreeze products containing dyes.
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Dinuclear complexes bearing Ru(II) photoactive centers are of interest for the development of efficient dual catalysts for many photocatalyzed reactions. Ditopic polypyridine ligands, bis(pyridin-2-yl)amino-1,10-phenanthrolines, containing an additional coordination site (bis(pyridin-2-yl)amine, dpa) at positions 3, 4 or 5 of the 1,10-phenanthroline core (Phen-3NPy2, Phen-4NPy2 and Phen-5NPy2) were synthesized. They were used as bridging ligands to obtain dinuclear complexes [(bpy)Ru(Phen-NPy2)PdCl](PF) (Ru(Phen-NPy2)Pd) in good yields stepwise complexation.

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The development of assisted reproductive technologies increases the likelihood of nanoparticles' (NPs) direct contact with gametes and embryos in in vitro conditions. Analyzing the influence of nanomaterials on the early mammalian embryo becomes increasingly relevant. This work is devoted to the effect of graphene oxide (GO) NPs on the in vitro development of mammalian embryos.

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In this paper, a network of interacting neurons based on a two-component system of reaction-superdiffusion equations with fractional Laplace operator responsible for the coupling configuration and nonlinear functions of the Hindmarsh-Rose model is considered. The process of synchronization transition in the space of the fractional Laplace operator exponents is studied. This parametric space contains information about both the local interaction strength and the asymptotics of the long-range couplings for both components of the system under consideration.

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Ultrafast laser radiation or beams of fast charged particles primarily excite the electronic system of a solid driving the target transiently out of thermal equilibrium. Apart from the nonequilibrium between the electrons and atoms, each subsystem may be far from equilibrium. From first principles, we derive the definition of various atomic temperatures applicable to electronically excited ensembles.

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Emerging fields of quantum technologies and biomedical applications demand pure nanodiamonds (NDs) with well-defined surface chemistry. Therefore, an inexpensive, scalable and eco-friendly ND surface purification technology is required. In this study, we report our method, salt-coated air oxidation (SCAO) thermal annealing, to achieve uniform purification of a ND surface without the loss of diamond material.

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We prepared an organically templated magnet, (H)VPOOH (H = diprotonated ethylenediamine), hydrothermally and characterized its crystal structure by powder X-ray diffraction and Fourier-transform infrared spectroscopy, and its physical properties by magnetization, specific heat and nuclear magnetic resonance measurements and density functional theory calculations. (H)VPOOH consists of uniform chains of V (d, = 1) ions and exhibits Haldane magnetism with spin gap = 59.3 K from the magnetic susceptibility () at = 0.

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Conventional X-ray therapy (XRT) is commonly applied to suppress cancerous tumors; however, it often inflicts collateral damage to nearby healthy tissue. In order to provide a better conformity of the dose distribution in the irradiated tumor, proton therapy (PT) is increasingly being used to treat solid tumors. Furthermore, radiosensitization with gold nanoparticles (GNPs) has been extensively studied to increase the therapeutic ratio.

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This paper presents the results of research, development, and testing of magnetically insulated air diodes with replaceable graphite and stainless-steel tubular and coaxial cathodes of various configurations capable of generating directed bunches of runaway electrons. At the anode, the bunches have cross sections shaped as circles or rings with an outer diameter of 1-2 cm. The durations of the bunches, which carry currents of a few to tens of amperes, range from tens of picoseconds to 100 ps, and their charges range from tenths of a nanocoulomb to a few nanocoulombs.

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Hafnium nitride nanoparticles (HfN NPs) can offer appealing plasmonic properties at the nanoscale, but the fabrication of stable water-dispersible solutions of non-toxic HfN NPs exhibiting plasmonic features in the window of relative biological transparency presents a great challenge. Here, we demonstrate a solution to this problem by employing ultrashort (femtosecond) laser ablation from a HfN target in organic solutions, followed by a coating of the formed NPs with polyethylene glycol (PEG) and subsequent dispersion in water. We show that the fabricated NPs exhibit plasmonic absorption bands with maxima around 590 nm, 620 nm, and 650 nm, depending on the synthesis environment (ethanol, acetone, and acetonitrile, respectively), which are largely red-shifted compared to what is expected from pure HfN NPs.

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Recently, progress has been made in fabricating diamond-based scintillators with integrated rare-earth luminescent particles. These luminescent particles are integrated into the bulk of diamond during their synthesis by chemical vapor deposition (CVD). However, the growth conditions include a chemically aggressive plasma environment and elevated temperatures, which results in the partial degradation of particles and a decrease in the intensity of their luminescence.

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Boron-enhanced proton therapy has recently appeared as a promising approach to increase the efficiency of proton therapy on tumor cells, and this modality can further be improved by the use of boron nanoparticles (B NPs) as local sensitizers to achieve enhanced and targeted therapeutic outcomes. However, the mechanisms of tumor cell elimination under boron-enhanced proton therapy still require clarification. Here, we explore possible molecular mechanisms responsible for the enhancement of therapeutic outcomes under boron NP-enhanced proton therapy.

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The impact of substituents at the 4- and 7-positions of 1,10-phenanthroline-2,9-dicarboxamides on the photophysical properties of the ligands and their coordination compounds with the lanthanide triad-europium, gadolinium, and terbium-was analyzed. This study demonstrates how modification of the electronic nature of ligands through the incorporation of diverse functional groups affects the luminescence properties of their complexes. The introduction of various substituents leads to the appearance of intra-ligand or ligand-to-ligand charge transfer (CT) states.

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Here, the optical properties of the Nafion polymer membrane containing colloidal CdSe/CdS/ZnS nanocrystals embedded by diffusion have been studied. The CdSe/CdS/ZnS nanocrystals have a core/shell/shell appearance. All experiments were carried out at room temperature (22 ± 2) °C.

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