1,163 research outputs found

    INFLUENCE OF HYDROCORTISONE AND BETA-ADRENERGIC RECEPTOR BLOCKADE IN EFFECTOR PHASE OF THE IMMUNE RESPONSE ON PHAGOCYTIC ACTIVITY OF REGIONAL LYMPH NODE CELLS, BLOOD MONOCYTES AND PERITONEAL MACROPHAGES

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    It was established that hydrocortisone reduces the phagocytic activity of regional lymph node cells and peritoneal mononuclear phagocytes, but does not affect the relative parameters of the phagocytic activity of peripheral blood monocytes in the effector phase of immune response in rats. Effects of hydrocortisone were significantly modified by the administration of beta-adrenoceptor antagonist propranolol hydrochloride

    Ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies

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    We develop a model for ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies. This model applies to (i) magnetic materials with both uniaxial and cubic anisotropies, and (ii) magnetic nanoparticles with effective core and surface anisotropies; We numerically compute the resonance frequency as a function of the field and the resonance field as a function of the direction of the applied field for an arbitrary ratio of cubic-to-uniaxial anisotropy. We also provide some approximate analytical expressions in the case of weak cubic anisotropy. We propose a method that uses these expressions for estimating the uniaxial and cubic anisotropy constants, and for determining the relative orientation of the cubic anisotropy axes with respect to the crystal principle axes. This method is applicable to the analysis of experimental data of resonance type measurements for which we give a worked example of an iron thin film with mixed anisotropy.Comment: 7 pages, 3 figure

    The role of alkane coordination in Cā€“H bond cleavage at a Pt(II) center

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    The rates of CFormula H bond activation for various alkanes by [(Nā€“N)Pt(Me)(TFEd3)]+ (N Formula N = ArFormula NFormula C(Me)Formula C(Me)Formula NFormula Ar; Ar = 3,5-di-tert-butylphenyl; TFE-d3 = CF3CD2OD) were studied. Both linear and cyclic alkanes give the corresponding alkene-hydride cation [(Nā€“N)Pt(H)(alkene)]+ via (i) rate determining alkane coordination to form a CFormula H {sigma} complex, (ii) oxidative cleavage of the coordinated CFormula H bond to give a platinum(IV) alkyl-methyl-hydride intermediate, (iii) reductive coupling to generate a methane {sigma} complex, (iv) dissociation of methane, and (v) beta-H elimination to form the observed product. Second-order rate constants for cycloalkane activation (CnH2n), are proportional to the size of the ring (k ~ n). For cyclohexane, the deuterium kinetic isotope effect (kH/kD) of 1.28 (5) is consistent with the proposed rate determining alkane coordination to form a CFormula H {sigma} complex. Statistical scrambling of the five hydrogens of the Pt-methyl and the coordinated methylene unit, via rapid, reversible steps ii and iii, and interchange of geminal CFormula H bonds of the methane and cyclohexane CFormula H {sigma} adducts, is observed before loss of methane

    Temperature dependence of self-trapped exciton luminescence in nanostructured hafnia powder

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    The intrinsic optical properties and peculiarities of the energy structure of hafnium dioxide largely determine the prospects for applying the latter in new generation devices of optoelectronics and nanoelectronics. In this work, we have studied the diffuse reflectance spectra at room temperature for a nominally pure nanostructured HfO2HfO_2 powder with a monoclinic crystal structure and, as well its photoluminescence in the temperature range of 40 - 300 K. We have also estimated the bandgap EgE_g under the assumption made for indirect (5.31 eV) and direct (5.61 eV) allowed transitions. We have detected emission with a 4.2 eV maximum at T < 200 K and conducted an analysis of the experimental dependencies to evaluate the activation energies of thermal quenching (140 meV) and enhancement (3 meV) processes. Accounting for both the temperature behavior of the spectral characteristics and the estimation of the Huang-Rhys factor S >> 1 has shown that radiative decay of self-trapped excitons forms the mechanism of the indicated emission. In this case, the localization is mainly due to the interaction of holes with active vibrational modes of oxygen atoms in non-equivalent (O3fO_{3f} and O4fO_{4f}) crystal positions. Thorough study of the discussed excitonic effects can advance development of hafnia-based structures with a controlled optical response.Comment: 21 pages, 7 figures, 2 tables, 56 references. Keywords: hafnium dioxide, self-trapped exciton, F-center, thermal quenching of luminescence, luminescence enhacement, Huang-Rhys factor, effective phonon energy, bandgap widt

    Soft normed rings

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    Nitric Oxide Has a Concentration-Dependent Effect on the Cell Cycle Acting via EIN2 in Arabidopsis thaliana Cultured Cells

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    Ethylene is known to influence the cell cycle (CC) via poorly characterized roles whilst nitric oxide (NO) has well-established roles in the animal CC but analogous role(s) have not been reported for plants. As NO and ethylene signaling events often interact we examined their role in CC in cultured cells derived from Arabidopsis thaliana wild-type (Col-0) plants and from ethylene-insensitive mutant ein2-1 plants. Both NO and ethylene were produced mainly during the first 5 days of the sub-cultivation period corresponding to the period of active cell division. However, in ein2-1 cells, ethylene generation was significantly reduced while NO levels were increased. With application of a range of concentrations of the NO donor, sodium nitroprusside (SNP) (between 20 and 500 Ī¼M) ethylene production was significantly diminished in Col-0 but unchanged in ein2-1 cells. Flow cytometry assays showed that in Col-0 cells treatments with 5 and 10 Ī¼M SNP concentrations led to an increase in S-phase cell number indicating the stimulation of G1/S transition. However, at ā‰„20 Ī¼M SNP CC progression was restrained at G1/S transition. In the mutant ein2-1 strain, the index of S-phase cells was not altered at 5ā€“10 Ī¼M SNP but decreased dramatically at higher SNP concentrations. Concomitantly, 5 Ī¼M SNP induced transcription of genes encoding CDKA;1 and CYCD3;1 in Col-0 cells whereas transcription of CDKs and CYCs were not significantly altered in ein2-1 cells at any SNP concentrations examined. Hence, it is appears that EIN2 is required for full responses at each SNP concentration. In ein2-1 cells, greater amounts of NO, reactive oxygen species, and the tyrosine-nitrating peroxynitrite radical were detected, possibly indicating NO-dependent post-translational protein modifications which could stop CC. Thus, we suggest that in Arabidopsis cultured cells NO affects CC progression as a concentration-dependent modulator with a dependency on EIN2 for both ethylene production and a NO/ethylene regulatory function

    Increasing the efficiency of investments on survey of abundant land for their return to agricultural us

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    The "ā€œState program for the effective involvement of abundant agricultural land in the use and the development of the reclamation complex of the Russian Federationā€ for 2021ā€“2030" assumes the return of 12 million hectares out of 44 million hectares of all abandoned agricultural land (AAL) in the Russian Federation. The costs of 12 million hectares survey can be considered productive, while the costs of surveying the remaining 32 million hectares should be considered unproductive. The application of the new geoinformation database of ā€œSoils of agricultural lands of the Russian Federationā€ (DB SALRU) developed by the Federal Research Centre ā€œV.VĀ Dokuchaev Soil Sience Instituteā€ allows reduction of unproductive costs. By the example of the Vladimir region, a typical Russian region with AAL, the option of ranking AAL by their quality was demonstrated to determine the order of their return to agricultural use. The soil quality criteria are the bonitet and the normative yield of grain crops, which are part of the DB SALRU. It is proposed to consider the expenditures on the survey of AAL for the soils, which are first to be returned to agricultural use, as productive costs. These soils occupy 25% of the AAL of the region. The best quality soils are characterized by more than 40 points of bonitet and the standard yield of grain crops of more than 20 centners/ha. The cost of surveying the lands of the first order of returning to agricultural use is 10 million 80 thousand rubles. Survey of AAL soils of IIā€“IV orders of involvement in agricultural use, with relatively poor quality compared to the soils of the first order, is proposed to be conducted in the case of expansion of the State program in the future. This would save the unproductive expenses for the survey of AAL for the Vladimir region by 30 million 165.5 thousand rubles. The application of the proposed GIS-approach makes it possible to reduce unproductive expenses for the survey of AAL in the Russian Federation nearly by 5.600 million rubles
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