Temperature Dependence of the Cu(2) NQR Line Width in YBa2_2Cu3_3O7−y_{7-y}

Systematic measurements of the $^{63}$Cu(2) NQR line width were performed in underdoped YBa$_2$Cu$_3$O$_{7-y}$ samples over the temperature range 4.2 K $<T<300$ K. It was shown that the copper NQR line width monotonically increases upon lowering temperature in the below-critical region, resembling temperature behavior of the superconducting gap. The observed dependence is explained by the fact that the energy of a condensate of sliding charge-current states of the charge-density-wave type depends on the phase of order parameter. Calculations show that this dependence appears only at $T<T_c$. Quantitative estimates of the line broadening at $T<T_c$ agree with the measurement results.Comment: 4 pages, 2 figure

Application of the LASSO algorithm for fitting the multiexponential data of the NMR relaxometry

© 2018 Institute of Physics Publishing. All rights reserved. The problem of time series fitting by the sum of several exponentials with different decay parameters often arises analyzing the data of a physical experiment. In particular, such a problem arises determining the nuclear transverse relaxation times from the spin-echo decay NMR data. Mathematically, the problem can be formulated as a solution of the Fredholm integral equation of the first kind with an exponential kernel, or an equivalent system of linear equations. To solve this equation, various regularization methods are used, based on the L2-norm in most cases. We report the application of the L1-regularization for the problem, using the LASSO algorithm. A comparison was made between the results of L1- and L2-regularization on model time series, which were the sum of several exponential decays with noise. Also the L1- and L2-regularization were applied to analyze the 1H NMR experimental data of the spin-echo decays of n-hexane adsorbed in the porous volume of aluminium poor MFI-type zeolites known as ZSM-5. It was found out that the L1-regularization is effective method for determination of the transverse relaxation times from NMR data

Magnetic properties of powders LiTbF<inf>4</inf> and TbF<inf>3</inf>

© Kazan Federal University (KFU).Samples LiTbF4and TbF3were synthesized by modified methods of colloidal chemistry. The magnetization of these samples was measured in the external magnetic field at 100 Oe and 1T and in temperature range 2-300 K. Temperatures of phase transition to the magnetic ordering dipolar ferromagnet state were determined for synthesized samples

Low temperature x-ray diffraction study on phase transitions

By using the low temperature x-ray diffraction (LTXD) we investigated several phase transitions which accompany with the crystal distortion. In our present report we will mainly discuss the integrated intensity (I.I.) of the x-ray spectrum. The temperature dependence of I.I can be expressed by the Debye-Waller factor. As a precursor effect of the crystal phase transition, the softening of the lattice occurs. Due to the softening of the lattice, the I.I drastically decreases down to the crystal phase transition temperature. We observed this effect in many materials. Here we will show some of them, iron pnictide superconductor SmFe0.925Co0.075AsO, and magnetic ordering compounds PrCu4Ag and Nd2Ti2O 7. © Published under licence by IOP Publishing Ltd

ЗНАЧЕНИЕ ГЕРПЕСВИРУСОВ В ЭТИОЛОГИИ РЯДА ИНФЕКЦИОННЫХ И СОМАТИЧЕСКИХ ЗАБОЛЕВАНИЙ ДЕТЕЙ

The article is devoted to study the etiological role of herpes viruses in infectious and somatic pathology of children (n = 770) using the complex of methods of laboratory diagnostics. Determined the leading etiological role of HSV in children with neuroinfections (12,7%) during primary infection and in children with intrauterine infection (29,0%) during its reactivation. It is shown that in 50,9% of cases, the diagnosis of «infectious mononucleosis» confirmed by the detection of markers of acute EBV-infection, and 20,0%, it was replaced by mononucleotides syndrome was discovered markers of acute CMV-infection, and 18,1% — markers of acute HHV-6-infection. The role of HHV-6 as the primary etiologic agent of the disease is established at 36,3% of children admitted with convulsive syndrome on the background of febrile, at 29,1% — a sudden exanthema and 25,5% — with fever of unknown origin.  Статья посвящена изучению этиологической роли герпесвирусов в инфекционной и соматической патологии детей (n = 770) с использованием комплекса методов лабораторной диагностики. Определена ведущая этиологическая роль ВПГ у детей с ней-роинфекциями (12,7%) при первичном инфицировании и у детей с внутриутробной инфекцией (29,0%) при ее реактивации. Показано, что в 50,9% случаев диагноз «инфекционный мононуклеоз» подтвержден обнаружением маркеров острой ВЭБИ, а 20,0% он был заменен на мононуклеозоподобный синдром, так были обнаружены маркеры острой ЦМВИ и в 18,1% — маркеры острой ВГЧИ-6. Роль ВГЧ-6 как основного этиологического агента заболевания установлена у 36,3% детей, поступивших с судорожным синдромом на фоне фебрилитета, у 29,1% — с внезапной экзантемой и у 25,5% — с лихорадкой неясного генеза. 

Optimization of two-stage cooling conditions for wire rod diameter 5.5–6.5 mm of low-carbon steel grades in order to ensure the required degree of descaling mechanically before its subsequent processing

With the aim of obtaining scale with a high degree possibility of mechanical removal under the conditions of the section rolling shop No. 1, at the mill «150» JSC «Belarusian Metallurgical Works – Management Company of Holding «BMC» developed technological modes of production of wire rods made of low-carbon steel grades.The peculiarities of scale formation were studied, namely, the factors influencing the removability, obtaining the optimal thickness and its phase components on the wire rod diameter 5.5–6.5 mm in the cooling process immediately after rolling, intended for wire production.To obtain the necessary ratio of the phase constituents of the scales on the surface of the wire rod, the following factors was taken into account: the temperature of the layout of the turns on the roller table in the air cooling line; (uniformity along the length of the turn), the cooling conditions of the helix of the turns (prevention of the 4FeO = Fe3O4-Fe decay), where the condition of cooling the wire rod from 600 to 250 °С, not exceeding 100 s, must be observed.The results of metallographic studies of scale on the wire surface are presented. The introduced technological regimes provided the optimal thickness and the FeO / Fe3O4 ratio after the experimental rolling of the metal. Exhausted cooling regimes allowed to reduce the consumption of fiber for all types of wire

Application of the LASSO algorithm for fitting the multiexponential data of the NMR relaxometry

© 2018 Institute of Physics Publishing. All rights reserved. The problem of time series fitting by the sum of several exponentials with different decay parameters often arises analyzing the data of a physical experiment. In particular, such a problem arises determining the nuclear transverse relaxation times from the spin-echo decay NMR data. Mathematically, the problem can be formulated as a solution of the Fredholm integral equation of the first kind with an exponential kernel, or an equivalent system of linear equations. To solve this equation, various regularization methods are used, based on the L2-norm in most cases. We report the application of the L1-regularization for the problem, using the LASSO algorithm. A comparison was made between the results of L1- and L2-regularization on model time series, which were the sum of several exponential decays with noise. Also the L1- and L2-regularization were applied to analyze the 1H NMR experimental data of the spin-echo decays of n-hexane adsorbed in the porous volume of aluminium poor MFI-type zeolites known as ZSM-5. It was found out that the L1-regularization is effective method for determination of the transverse relaxation times from NMR data

ASSIMILATION OF PRODUCTION OF THERMO-MECHANICALLY HARDENED REINFORCING BAR WITH EFFECTIVE AND ECONOMICAL CUT, EQUIVALENT DIAMETER 5,5—8,0 mm and 500 H/mm2

The carried out team-work of NIIZHB and RUP “BMZ” enabled to receive new technological decisions at production of bale reinforcing bar, realization of which will increase reliability of reinforced-concrete constructions of buildings and installations