78 research outputs found

    Experimental studies of restoration of ball mill trunnion

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    The article deals with the analysis of experimental data on reconstruction of cement mill axles by the auxiliary machine at the place of operation. Based on the experimental research in repair the regression models of large-size equipment are developed, coefficients of equations of regression are defined. Importance of coefficients is estimated, and the adequacy of regression models is checke

    Magnetoelastic and thermal effects in the BiMn2O5 lattice: a high-resolution x-ray diffraction study

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    High-resolution synchrotron x-ray diffraction measurements were performed on single crystalline and powder samples of BiMn2O5. A linear temperature dependence of the unit cell volume was found between T_{N}=38Kand100K,suggestingthatalowenergylatticeexcitationmayberesponsibleforthelatticeexpansioninthistemperaturerange.BetweenT 65KandTN,alllatticeparametersshowedincipientmagnetoelasticeffects,duetoshortrangespincorrelations.AnanisotropicstrainalongtheadirectionwasalsoobservedbelowT.BelowTN,arelativelylargecontractionoftheaparameterfollowingthesquareoftheaveragesublatticemagnetizationofMnwasfound,indicatingthatasecondorderspinhamiltonianaccountsforthemagneticinteractionsalongthisdirection.Ontheotherhand,themorecomplexbehaviorsfoundfor K and 100 K, suggesting that a low-energy lattice excitation may be responsible for the lattice expansion in this temperature range. Between T* ~ 65 K and T_{N}, all lattice parameters showed incipient magnetoelastic effects, due to short-range spin correlations. An anisotropic strain along the a-direction was also observed below T*. Below T_{N}, a relatively large contraction of the a-parameter following the square of the average sublattice magnetization of Mn was found, indicating that a second-order spin hamiltonian accounts for the magnetic interactions along this direction. On the other hand, the more complex behaviors found for band and c$ suggest additional magnetic transitions below T_{N} and perhaps higher-order terms in the spin hamiltonian. Polycrystalline samples grown by distinct routes and with nearly homogeneous crystal structure above T_{N} presented structural phase coexistence below T_{N}, indicating a close competition amongst distinct magnetostructural states in this compound.Comment: 23 pages, 7 figure

    Quantum Entanglement in Nitrosyl Iron Complexes

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    Recent magnetic susceptibility measurements for polycrystalline samples of binuclear nitrosyl iron complexes [Fe_2(C_3H_3N_2S)_2(NO)_4] (I) and [Fe_2(SC_3H_5N_2)_2(NO)_4] (II), suggest that quantum-mechanical entanglement of the spin degrees of freedom exists in these compounds. Entanglement E exists below the temperature T_E that we have estimated for complexes I and II to be 80-90 and 110-120 K, respectively. Using an expression of entanglement in terms of magnetic susceptibility for a Heisenberg dimer, we find the temperature dependence of the entanglement for complex II. Having arisen at the temperature T_E, the entanglement increases monotonically with decreasing temperature and reaches 90-95% in this complex at T=25 K, when the subordinate effects are still small.Comment: 8 page

    Electromagnons in multiferroic RMn2O5 compounds and their microscopic origin

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    We summarize the existing experimental data on electromagnons in multiferroic RMn2O5 compounds, where R denotes a rare earth ion, Y or Bi, and discuss a realistic microscopic model of these materials based on assumption that the microscopic mechanism of magnetically-induced ferroelectricity and electromagnon absorption relies entirely on the isotropic Heisenberg exchange and magnetostrictive coupling of spins to a polar lattice mode and does not involve relativistic effects. This model explains many magnetic and optical properties of RMn2O5 manganites, such as the spin re-orientation transition, magnetically-induced polarisation, appearance of the electromagnon peak in the non-collinear spin state and the polarisation of light for which this peak is observed. We compare experimental and theoretical results on electromagnons in RMn2O5 and RMnO3 compounds.Comment: 20 pages, 9 figures, to be published in J. Phys.: Condens. Matter, special issue on multiferroic

    Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

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    M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe

    EVALUATING THE CLINICAL AND HEMODYNAMICAL ACTION OF NEBIVOLOL IN CHRONIC HEART FAILURE

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    A task of this research was to study the influence of nebivolol on hemodynamic parameters, clinical sympthoms and life quality in patients II-IV FK HD by NYHA. 24 patients of main group have taken nebivolol in daily dose of 2,5-5 mg per os. Patients were treated with the drug in a course of 3 months.A control group(15 people) was treated traditional therapy (by heart glicozides, metabolic preparations, diurethics, if necessary). We have found that new β-adrenoblocker with additional vasodilatatorial qualities- nebivolol (NEBILET) kindly influences main hemodinamic parameters in chronic coronary patients. During 3 months’ observation examined patients had KDR and KSR distinctly lowered, speed of shortening of miocardium fibrem and the function of throw and MV grew, tension in a pulmonary artery decreased. NEBILET’S prescription in dosage of 2,5-5 mg/ daily kindly influences the reduction of heart rythm’s disturbances, a distinct tendency to lowering of MMLV noted. NEBILET can be successfully used in a combinated therapy of CCD II-IV FK, its usage in cases of coronary deficiency and AG is mostly advisable
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