28 research outputs found

    Counting and computing regions of DD-decomposition: algebro-geometric approach

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    New methods for DD-decomposition analysis are presented. They are based on topology of real algebraic varieties and computational real algebraic geometry. The estimate of number of root invariant regions for polynomial parametric families of polynomial and matrices is given. For the case of two parametric family more sharp estimate is proven. Theoretic results are supported by various numerical simulations that show higher precision of presented methods with respect to traditional ones. The presented methods are inherently global and could be applied for studying DD-decomposition for the space of parameters as a whole instead of some prescribed regions. For symbolic computations the Maple v.14 software and its package RegularChains are used.Comment: 16 pages, 8 figure

    From graphene oxide towards aminated graphene facile synthesis, its structure and electronic properties

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    In this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. The amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. The chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. Particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications

    Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation

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    The current status of electric dipole moments of diamagnetic atoms which involves the synergy between atomic experiments and three different theoretical areas -- particle, nuclear and atomic is reviewed. Various models of particle physics that predict CP violation, which is necessary for the existence of such electric dipole moments, are presented. These include the standard model of particle physics and various extensions of it. Effective hadron level combined charge conjugation (C) and parity (P) symmetry violating interactions are derived taking into consideration different ways in which a nucleon interacts with other nucleons as well as with electrons. Nuclear structure calculations of the CP-odd nuclear Schiff moment are discussed using the shell model and other theoretical approaches. Results of the calculations of atomic electric dipole moments due to the interaction of the nuclear Schiff moment with the electrons and the P and time-reversal (T) symmetry violating tensor-pseudotensor electron-nucleus are elucidated using different relativistic many-body theories. The principles of the measurement of the electric dipole moments of diamagnetic atoms are outlined. Upper limits for the nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained combining the results of atomic experiments and relativistic many-body theories. The coefficients for the different sources of CP violation have been estimated at the elementary particle level for all the diamagnetic atoms of current experimental interest and their implications for physics beyond the standard model is discussed. Possible improvements of the current results of the measurements as well as quantum chromodynamics, nuclear and atomic calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for EPJ

    First experimental results obtained using the highpower free electron laser at the siberian center for photochemical research

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    The first lasing near the wavelength of 140 µm was achieved in April 2003 using a high-power free electron laser (FEL) constructed at the Siberian Center for Photochemical Research. In this paper we briefly describe the design of the FEL driven by an accelerator–recuperator. Characteristics of the electron beam and terahertz laser radiation, obtained in the first experiments, are also presented in the paper.У Сибірському центрі фотохімічних досліджень навесні 2003 року отримана генерація випромінювання з довжиною хвилі 140 мкм на потужному лазері на вільних електронах (ЛВЕ). У роботі коротко описана конструкція ЛВЕ на базі прискорювача рекуператора і представлені результати вимірювання деяких параметрів електронного пучка і терагерцового випромінювання.В Сибирском центре фотохимических исследований весной 2003 года получена генерация излучения с длиной волны 140 мкм на мощном лазере на свободных электронах (ЛСЭ). В работе кратко описана конструкция ЛСЭ на базе ускорителя рекуператора и представлены результаты измерения некоторых параметров электронного пучка и терагерцового излучения

    Electrical response of lithium niobate and lithium tantalate thin films to modulated thermal radiation

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    In this work, we studied the pyroelectric activity of thin polycrystalline lithium niobate films fabricated by radio frequency magnetron sputtering and laser ablation, and thin polycrystalline lithium tantalate films fabricated by radio frequency magnetron sputtering. Using the dynamic method of studying the pyroelectric effect, it was found that all samples have self-polarization that occurs during the post-growth thermal annealing of the structure. An estimate of the pyroelectric coefficient showed that the values of the pyroelectric coefficient of lithium niobate and lithium tantalate thin films are several times lower than the values of the pyroelectric coefficient for bulk crystals of the corresponding materials. This may be due to the fact that the polarization vector of some grains lies in the film plane, as well as to the traps existing in the film volume and at the film/substrate interface, on which charge carriers recombine and do not participate in the generation of the pyroelectric current

    A Functional Line of Plasma Extractors

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    A competitive functional line of plasma extractors for blood service was developed using innovative technologies. The developed extractors can be used for preparation of blood components and blood-derived products. © 2021, Springer Science+Business Media, LLC, part of Springer Nature

    БИОАНТИОКСИДАНТЫ (ЧАСТЬ 2)

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    Based on the analysis of the latest scientific data, the paper suggests a synthetic classification of the known bioantioxidants, peculiarities of their structure and functioning. The second part of the review describes the sulfur-containing compounds, chelators of the metal ions of variable valency, compounds containing hydroxyl or amino group, and nanoparticles.На основе анализа последних научных данных представлена синтетическая классификация известных биоантиоксидантов, рассмотрены особенности их строения и функционирования. Во второй части описаны серосодержащие соединения, хелаторы ионов металлов переменной валентности, соединения, содержащие гидроксильную или аминогруппу, а также наночастицы
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