Momentum Dependence of Resonant Inelastic X-Ray Scattering Spectrum in Insulating Cuprates

The resonant inelastic x-ray scattering spectrum in insulating cuprates is examined by using the exact diagonalization technique on small clusters in the two-dimensional Hubbard model with second and third neighbor hopping terms. When the incident photon energy is tuned near the Cu K absorption edges, we find that the features of the unoccupied upper Hubbard band can be extracted from the spectrum through an anisotropic momentum dependence. They provide an opportunity for the understanding of the different behavior of hole- and electron-doped superconductors.Comment: 4 pages with 4 figures, to be published in PR

Electronic structure of Co_xTiSe_2 and Cr_xTiSe_2

The results of investigations of intercalated compounds Cr_xTiSe_2 and Co_xTiSe_2 by X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES) are presented. The data obtained are compared with theoretical results of spin-polarized band structure calculations. A good agreement between theoretical and experimental data for the electronic structure of the investigated materials has been observed. The interplay between the M3d--Ti3d hybridization (M=Cr, Co) and the magnetic moment at the M site is discussed. A 0.9 eV large splitting of the core Cr2p{3/2} level was observed, which reveals a strong exchange magnetic interaction of 3d-2p electrons of Cr. In the case of a strong localization of the Cr3d electrons (for x<0.25), the broadening of the CrL spectra into the region of the states above the nominal Fermi level was observed and attributed to X-ray re-emission. The measured kinetic properties are in good accordance with spectral investigations and band calculation results.Comment: 14 pages, 11 figures, submitted to Phys.Rev.

Resonant soft X-ray Raman scattering of NiO

Resonant soft X-ray Raman scattering measurements on NiO have been made at photon energies across the Ni 2p absorption edges. The details of the spectral features are identified as Raman scattering due to d-d and charge-transfer excitations. The spectra are interpreted within the single impurity Anderson model, including multiplets, crystal-field and charge-transfer effects. At threshold excitation, the spectral features consists of triplet-triplet and triplet-singlet transitions of the 3d8 configuration. For excitation energies corresponding to the charge-transfer region in the Ni 2p X-ray absorption spectrum of NiO, the emission spectra are instead dominated by charge-transfer transitions to the 3d9L-1 final state. Comparisons of the final states with other spectroscopical techniques are also made.Comment: 9 pages, 2 figures, 2 tables, http://iopscience.iop.org/0953-8984/14/13/32

Electronic structure investigation of CeB6 by means of soft X-ray scattering

The electronic structure of the heavy fermion compound CeB6 is probed by resonant inelastic soft X-ray scattering using photon energies across the Ce 3d and 4d absorption edges. The hybridization between the localized 4f orbitals and the delocalized valence-band states is studied by identifying the different spectral contributions from inelastic Raman scattering and normal fluorescence. Pronounced energy-loss structures are observed below the elastic peak at both the 3d and 4d thresholds. The origin and character of the inelastic scattering structures are discussed in terms of charge-transfer excitations in connection to the dipole allowed transitions with 4f character. Calculations within the single impurity Anderson model with full multiplet effects are found to yield consistent spectral functions to the experimental data.Comment: 9 pages, 4 figures, 1 table, http://link.aps.org/doi/10.1103/PhysRevB.63.07510

Tuning catalytic activity of Ni–Co nanoparticles synthesized by gamma-radiolytic reduction of acetate aqueous solutions

Transition metal-based catalysts show great potential to replace Pt-based material in energy conversion devices thanks to their low cost, reasonable intrinsic activity, thermodynamic stability, and corrosion resistance. The electrochemical performance of such catalysts is sensitive to their composition and structure. Here, it is demonstrated that homogeneous alloy nanoparticles with varying Ni-to-Co ratio and controlled structure can be synthesized from aqueous Ni(Co) acetate solutions using a facile γ-radiolytic reduction method. The obtained samples are found to possess defects that are ordered to form polytypes structures. The concentration of these defects depends on the Ni-to-Co ratio, as supported by the results of ab initio calculations. It is found that structural defects may influence the activity of catalysts toward the oxygen evolution reaction, while this effect is less pronounced with respect to the oxygen reduction reaction. At the same time, the activity of Ni–Co catalysts in the hydrogen evolution reaction is affected by formation of NiOH bonds on the surface rather than by the presence of structural defects. This study demonstrates that the composition of NiCo nanoparticles is an essential factor affecting their structure, and both composition and structure can be tuned to optimize electrochemical performance with respect to various catalytic reactions

Management approach to patients with premalignant lesions of the stomach

The aim of review. To analyze modern aspects of management of patients with premalignant changes in the stomach.Key points. According to requirements of system OLGA or OLGIM application of modern endoscopic methods and morphological investigation is necessary for expert diagnostics of atrophy, metaplasia and dysplasia in the stomach. Detection of Helicobacter pylori infection and its eradication are important principles of management of patients with stomach premalignant lesions.Conclusion. Monitoring methods of patients with stomach mucosa dysplasia are specified. Modes of H. pylori eradication are presented

Insight into the structure-property relationship of UO2_{2} nanoparticles

Highly crystalline UO$_{2}$ nanoparticles (NPs) with sizes of 2–3 nm were produced by fast chemical deposition of uranium(IV) under reducing conditions at pH 8–11. The particles were then characterized by microscopy and spectroscopy techniques including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy at the U M$_{4}$ edge and extended X-ray absorption fine structure (EXAFS) spectroscopy at the U L$_{3}$ edge. The results of this investigation show that despite U(IV) being the dominant oxidation state of the freshly prepared UO$_{2}$ NPs, they oxidize to U$_{4}$O$_{9}$ with time and under the X-ray beam, indicating the high reactivity of U(IV) under these conditions. Moreover, it was found that the oxidation process of NPs is accompanied by their growth in size to 6 nm. We highlight here the major differences and similarities of the UO$_{2}$ NP properties to PuO$_{2}$, ThO$_{2}$ and CeO$_{2}$ NPs

Bioactive Pyrrolo[2,1-f][1,2,4]triazines: Synthesis, Molecular Docking, In Vitro Cytotoxicity Assay and Antiviral Studies

A series of 2,4-disubstituted pyrrolo[2,1-f][1,2,4]triazines containing both aryl and thienyl substituents were synthesized by exploiting the 1,3-cycloaddition reaction of N(1)-ethyl-1,2,4-triazinium tetrafluoroborates with dimethyl acetylenedicarboxylate. The antiviral activity of the synthesized compounds against influenza virus strain A/Puerto Rico/8/34 (H1N1) was studied in experiments on Madin-Darby canine kidney (MDCK) cell culture. Among the pyrrolo[2,1-f][1,2,4]triazine derivatives, compounds with low toxicity and high antiviral activity were identified. Dimethyl 4-(4-methoxyphenyl)-7-methyl-2-p-tolylpyrrolo[2,1-f][1,2,4]triazine-5,6-dicarboxylate was found to demonstrate the best antiviral activity (IC50 4 µg/mL and selectivity index 188). Based on the results of in vitro tests and molecular docking studies performed, a plausible mechanism of action for these compounds was suggested to involve inhibition of neuraminidase. © 2023 by the authors.Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2020-777This research was supported by the Ministry of Science and Higher Education of the Russian Federation: Agreement on granting grants from the federal budget in the form of subsidies in accordance with paragraph 4 of Article 78.1 of the Budget Code of the Russian Federation (Moscow, October 1, 2020, No. 075-15-2020-777)

Роль апоптоза в дисрегуляции локального и системного иммунитета при Helicobacter pilory-инфекции

The level of intracellular apoptosis regulators (cell death antagonists (Bcl-2) and agonists (CPP-32)), proliferation antigen Ki67 in lymphocytes of biopsy materials of the mucous coat of stomach at Helicobacter pylori-associated gastric ulcer and chronic gastritis in Khakassian aboriginal population and newcomers have been studied. The lymphocyte apoptosis in peripheral blood in aboriginal population was assessed. Changes in immunological indices were revealed in patients infected with Helicobacter pylori compared to healthy donors and newcomers. These changes were characterized by the more intense apoptotic lymphocyte death compared to the number of such cells in patients with chronic gastritis and in the control group. The role of apoptosis disfunctions in the regulation of local and system immunity at Helicobacter pylori infection is discussed.Исследован уровень внутриклеточных регуляторов апоптоза — антагонистов (Bcl-2) и агонистов (CPP-32) клеточной гибели, антиген пролиферации Ki-67 в лимфоцитах биоптатов слизистой оболочки желудка при Helicobacter pyloriассоциированных язвенной болезни и хроническом гастрите у коренных и пришлых жителей Хакасии. Оценивался апоптоз лимфоцитов периферической крови у коренных жителей. Установлены изменения иммунологических показателей у больных, инфицированных Helicobacter pylori, по сравнению с таковыми у здоровых доноров и представителей пришлого населения. Изменения, выявленные в крови у больных язвенной болезнью, характеризовались усилением апоптотической гибели лимфоцитов по сравнению с количеством таких клеток у больных хроническим гастритом и в контроле. Обсуждается роль нарушений апоптоза в регуляции локального и системного иммунитета при Helicobacter pylori-инфицировании

Indolyl-Derived 4H-Imidazoles: PASE Synthesis, Molecular Docking and In Vitro Cytotoxicity Assay

The strategy of the nucleophilic substitution of hydrogen (SNH) was first applied for the metal-free C-H/C-H coupling reactions of 4H-imidazole 3-oxides with indoles. As a result, a series of novel bifunctional azaheterocyclic derivatives were obtained in yields up to 95%. In silico experiments on the molecular docking were performed to evaluate the binding possibility of the synthesized small azaheterocyclic molecules to the selected biotargets (BACE1, BChE, CK1δ, AChE) associated with the pathogenesis of neurodegenerative diseases. To assess the cytotoxicity for the synthesized compounds, a series of in vitro experiments were also carried out on healthy human embryo kidney cells (HEK-293). The leading compound bearing both 5-phenyl-4H-imidazole and 1-methyl-1H-indole moieties was defined as the prospective molecule possessing the lowest cytotoxicity (IC50 &gt; 300 µM on HEK-293) and the highest binding energy in the protein–ligand complex (AChE, −13.57 kcal/mol). The developed compounds could be of particular interest in medicinal chemistry, particularly in the targeted design of small-molecule candidates for the treatment of neurodegenerative disorders. © 2023 by the authors.Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2022-1118, W03.31.0034; Russian Science Foundation, RSF: 20-73-10077The chemical design, synthesis and characterization of indolyl-derived 4H -imidazoles and in vitro studies were supported by the Russian Science Foundation (Project # 20-73-10077). The in silico studies were supported by the Ministry of Science and Higher Education of the Russian Federation (Ref. # 075-15-2022-1118, dated 29 June 2022). The synthesis of starting 4H -imidazole N -oxide substrates was supported by the Ministry of Science and Higher Education of the Russian Federation (Project # 14.W03.31.0034)