1,785 research outputs found

    Magnetic degeneracy and hidden metallicity of the spin density wave state in ferropnictides

    Get PDF
    We analyze spin density wave (SDW) order in iron-based superconductors and electronic structure in the SDW phase. We consider an itinerant model for Fe-pnictides with two hole bands centered at (0,0)(0,0) and two electron bands centered at (0,π)(0,\pi) and (π,0)(\pi,0) in the unfolded BZ. A SDW order in such a model is generally a combination of two components with momenta (0,π)(0,\pi) and (π,0)(\pi,0), both yield (π,π)(\pi,\pi) order in the folded zone. Neutron experiments, however, indicate that only one component is present. We show that (0,π)(0,\pi) or (π,0)(\pi,0) order is selected if we assume that only one hole band is involved in the SDW mixing with electron bands. A SDW order in such 3-band model is highly degenerate for a perfect nesting and hole-electron interaction only, but we show that ellipticity of electron pockets and interactions between electron bands break the degeneracy and favor the desired (0,π)(0,\pi) or (π,0)(\pi,0) order. We further show that stripe-ordered system remains a metal for arbitrary coupling. We analyze electronic structure for parameters relevant to the pnictides and argue that the resulting electronic structure is in good agreement with ARPES experiments. We discuss the differences between our model and J1J2J_1-J_2 model of localized spins.Comment: reference list updated, typos are correcte

    Search for the gamma-ray fluxes with energies above 10915) eV from various objects

    Get PDF
    Considerable interest has developed in the search for local sources of superhigh-energy gamma-rays. The experimental data obtained with the extensive air showers (EAS) array of the Moscow State University are analyzed with a view to searching for the superhigh-energy gamma-rays from various objects and regions of the Galaxy

    ENDOVENOUS LASER ABLATION OF MAIN SUPERFICIAL VEINS: FIRST APPLICATION IN EAST SIBERIA

    Get PDF
    The aim of the work was to evaluate the effectiveness of endovenous laser ablation of great and small saphenous veins by a series of clinical cases of patients with varicose veins. Endovenous laser ablation of great (18) and small saphenous veins (8) were performed in 24 patients. This surgery was combined with phlebectomy varicose veins in 16 and foam form sclerotherapy in 10 cases. All patients werefollowed up for 2 and 6 months. Full ablation of main saphenous vein achieved in all patients in the early period of observation. Endovenous laser ablation of main saphenous veins is a good alternative to standard flebectomy it has the same with the surgery percentage of recurrence in early period of observation but faster rehabilitation after interference. Further control clinical study is needed for assessment effect of this treatment in the course of year and more

    Development and validation of methods of quantitative determination of the new antidiabetic drug in the blood plasma of rats by high performance liquid chromatography with mass spectrometric detection

    Get PDF
    We developed a method of quantification of the new antidiabetic drug 3-(1h-benzimidazole-2-yl)-1,2,2-trimethyl-cyclopentane-carbonic acid (c7070) in the blood plasma of rats by high-performance liquid chromatography with mass-spectrometric detectio

    Pharmacokinetic studies of new antiparkinsonian drug Rapitalam

    Get PDF
    The aim of this study was to investigate the pharmacokinetic parameters of the mGluR4 receptor blocker Rapitalam on rabbits. There was developed the method of the quantitative determination of Rapitalam in the blood plasma of rabbits using high performance liquid chromatography with tandem mass spectrometric detection. The study was performed on 12 rabbits (males, weighing between 3,300 to 3,500 g). In intragastric dosing of the substance was administered using a gastric tube in the form of suspension in water 0.9 mg/ml, 9 mg/ml, and 90 mg/ml at a dose of 0.3 mg/kg, 3 mg/kg and 30 mg/kg. The main pharmacokinetic parameters of the substance was established on rabbits that allow you to optimize the future use of it's as a potential drug for the treatment of Parkinson's diseas

    Escape of the martian protoatmosphere and initial water inventory

    Get PDF
    Latest research in planet formation indicate that Mars formed within a few million years (Myr) and remained a planetary embryo that never grew to a more massive planet. It can also be expected from dynamical models, that most of Mars' building blocks consisted of material that formed in orbital locations just beyond the ice line which could have contained ~0.1-0.2 wt. % of H2O. By using these constraints, we estimate the nebula-captured and catastrophically outgassed volatile contents during the solidification of Mars' magma ocean and apply a hydrodynamic upper atmosphere model for the study of the soft X-ray and extreme ultraviolet (XUV) driven thermal escape of the martian protoatmosphere during the early active epoch of the young Sun. The amount of gas that has been captured from the protoplanetary disk into the planetary atmosphere is calculated by solving the hydrostatic structure equations in the protoplanetary nebula. Depending on nebular properties such as the dust grain depletion factor, planetesimal accretion rates and luminosities, hydrogen envelopes with masses >=3x10^{19} g to <=6.5x10^{22} g could have been captured from the nebula around early Mars. Depending of the before mentioned parameters, due to the planets low gravity and a solar XUV flux that was ~100 times stronger compared to the present value, our results indicate that early Mars would have lost its nebular captured hydrogen envelope after the nebula gas evaporated, during a fast period of ~0.1-7.5 Myr. After the solidification of early Mars' magma ocean, catastrophically outgassed volatiles with the amount of ~50-250 bar H2O and ~10-55 bar CO2 could have been lost during ~0.4-12 Myr, if the impact related energy flux of large planetesimals and small embryos to the planet's surface lasted long enough, that the steam atmosphere could have been prevented from condensing. If this was not the case... (continued)Comment: 47 pages, 10 figures, 3 tables, submitted to PS

    Pharmacokinetic studies derived indole SS-68 with antiarrhythmic and antianginal properties

    Get PDF
    A method of quantitative determination of SS-68 derivative of indole in rabbit blood plasma by high performance liquid chromatography with tandem mass spectrometric detector (HPLCMS/ MS). Conducted pharmacokinetic studies SS-68 in the body of rabbits. Set the main pharmacokinetic parameters of the substance that allow you to optimize the future use of it’s as a potential drug in cardiology practic

    Anticholinergic activity and pharmacokinetic parameters of agent SS-68 with properties of class III antiarrhythmic drugs

    Get PDF
    It was shown that the indole derivate SS-68 (50 and 250 μg/kg intravenous) in acute experiments on cats with neurogenic atrial fibrillation (AF) has a dose-dependent antiarrhythmic action which is associated with the neurotropic influence of this substance, since the suppression of the AF coincides with its anticholinergic effect observed for more than 2 hours, but cardiotropic action at this time was not observed. High antiarrhythmic activity of SS-68 to neurogenic AF may be due to the IKAch inhibition and blockade of M2-cholinergic receptor
    corecore