393 research outputs found

    Production of Z^0 bosons with rapidity gaps: exclusive photoproduction in gamma p and p p collisions and inclusive double diffractive Z^0's

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    We extend the k_\perp-factorization formalism for exclusive photoproduction of vector mesons to the production of electroweak Z^0 bosons. Predictions for the gamma p \to Z^0 p and p p \to p p Z^0 reactions are given using an unintegrated gluon distribution tested against deep inelastic data. We present distributions in the Z^0 rapidity, transverse momentum of Z^0 as well as in relative azimuthal angle between outgoing protons. The contributions of different flavours are discussed. Absorption effects lower the cross section by a factor of 1.5-2, depending on the Z-boson rapidity. We also discuss the production of Z^0 bosons in central inclusive production. Here rapidity and (x_{\Pom,1}, x_{\Pom,2}) distributions of Z^0 are calculated. The corresponding cross section is about three orders of magnitude larger than that for the purely exclusive process.Comment: 19 pages, 14 figs, A. Cisek is married name of A. Rybarsk

    Reactive self-heating model of aluminum spherical nanoparticles

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    Aluminum-oxygen reaction is important in many highly energetic, high pressure generating systems. Recent experiments with nanostructured thermites suggest that oxidation of aluminum nanoparticles occurs in a few microseconds. Such rapid reaction cannot be explained by a conventional diffusion-based mechanism. We present a rapid oxidation model of a spherical aluminum nanoparticle, using Cabrera-Mott moving boundary mechanism, and taking self-heating into account. In our model, electric potential solves the nonlinear Poisson equation. In contrast with the Coulomb potential, a "double-layer" type solution for the potential and self-heating leads to enhanced oxidation rates. At maximal reaction temperature of 2000 C, our model predicts overall oxidation time scale in microseconds range, in agreement with experimental evidence.Comment: submitte

    Modeling and Simulation of Janus-like Nanoparticles Formation by Solid-Gas Exothermic Reactions

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    Theoretical model for the simulation of synthesis of Janus-like particles (JP) consisting two different phases using the Carbon Combustion Synthesis of Oxides (CCSO) is presented. The model includes the variation of sample initial porosity, carbon concentration and oxygen flow rate used to predict the formation of JP features. The two temperature (2T) combustion model of chemically active submicron-dispersed mixture of two phases including ferroelectric and ferromagnetic was implemented and assessed by using the experimentally estimated activation energy of 112±3.3 kJ/mol and combustion temperature. The experimental values allowed to account the thermal and concentration expansion effect along with the dispersion by the slip-jump simulation for high Knudsen numbers. The model predicted that the smaller initial porosity of the combustion media creates higher formation rate of Janus-like particles. The simulation of slippage and jumps of the gas temperature allowed the scale-bridging between macro- and micro- structures

    Gravity Effect on Electrical Field Generation and Charge Carriers Transfer During Combustion Synthesis of Sulfides

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    The effect of gravity on the electric potential generated by the combustion synthesis of zinc sulfide is analyzed using the numerical simulation. Recent experimental studies on generation of electric voltage during combustion synthesis of zinc sulfide (ZnS) have revealed high voltage signals (4 V) with duration about 1 s, which are much higher than those produced by the gas–solid and solid–solid combustion reactions studied previously. These data have raised the question about mechanism of such a phenomenon. In our previous work we developed a novel (distributed) model describing the electric potential generation during combustion synthesis of sulfides (CSS) that didn\u27t count the effect of gravity. In this paper the simulations of heat - mass transfer, charge carriers motion, and voltage profiles taking into account the Earth gravity effect. The simulations confirms that the gravitation force strongly affects the emission of negatively charged sulfur ions as well as electrons and has a significant impact on the amplitude and temporal evolution of the combustion induced voltage. The voltage reduction up to four times has been observed numerically in the case when gravity acts in the direction coincident to that of the propagating combustion wave. Vice versa, the significant acceleration of the combustion and the voltage amplification due to the advection is simulated when gravity acts in the direction opposite to that of the propagating combustion wave

    Slip-Jump Model for Carbon Combustion Synthesis of Complex Oxide Nanoparticles

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    Carbon Combustion Synthesis of Oxides (CCSO) is a promising method to produce submicron- and nano- sized complex oxides. The CCSO was successfully utilized for producing several complex oxides, a complete theoretical model including the sample porosity, fl ow parameters and reaction energetics is needed to predict the combustion parameters for CCSO. In this work, we studied the ignition temperature and combustion wave axial temperature distribution, activation energy, combustion heat and thermal losses for a typical CCSO synthesis for cylindrical samples of Ni-Zn ferrites with high (\u3e85%) porosity. We developed a two level combustion model of chemically active nano-dispersed mixture, using the experimentally measured ignition temperature and combustion parameter values utilizing the slipjump method for high Knudsen numbers. The theoretical predictions of highly porous samples when the flow resistivity is small and the gas can easily fl ow through the cylindrical sample are in good agreement with the experimental data. The calculation of combustion characteristics for the lower porosity values demonstrated that the surface combustion was dominated due to high gas flow resistivity of the sample. Finger combustion features were observed at this combustion mode

    A novel nano-energetic system based on bismuth hydroxide

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    We report the first study of gas generation and thermal wave behavior during the performance of a novel nano-energetic system based on aluminum and bismuth hydroxide Al–Bi(OH)3. Thermodynamic calculations demonstrate that this system is comparable to one of the most powerful known nanothermite systems, Al–Bi2O3, in terms of energy capacity per initial charge mass, and may generate more than twice the gaseous products: 0.0087 mol g1 . Differential scanning calorimetry analysis shows that homogenization of the as-received powder using mechanical activation is an essential step to reduce the decomposition energy of bismuth hydroxide by 30%. This results in nano-thermite with higher pressure discharge abilities. The mechanical activation with energy of 450–750 kJ g1 is enough to transform micro-meter sized particles to sub-micro and nano-sized particles. The resulting nanothermite generated a significant pressure discharge with a value of up to 5.6 kPa m3 g

    Thermal Dose Inactivation of Escherichia coli by Magnetic Induced Hyperthermia

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    Background: Apoptosis of mutated cells via magnetic hyperthermia has gained advocacy as technology capable of being used in lieu of chemotherapy for targeting cancer tumors. Progress of nanotechnology offers effective remote heating of magnetic fluid via hyperthermia. The heating and specific power absorption of these nanoparticles use in the magnetic fluid are dependent on particle properties and treatment locations. Methods: Nanoparticles were fabricated using microfluidic system by interaction of two solutions containing 2Fe(NO3)3+FeSO4 and NaOH+2%Dextran to create nanostructured media with a biocompatible dextran coating and a Fe3O4 core. The nanoparticles, of a concentration of 5mg/ml, were placed in a vile containing Luria-Bertani (LB) media with approximately 2.0x108 cells. The vile was inserted into a DM100 Series Magnetic Hyperthermia Device that provides an alternating magnetic field of 300 Gauss with a frequency of 604KHz. Results: Magnetite produced via the microfluidic systems at flow rate of 0.04mL/s showed uniform particle size distribution with average size 10nm and saturation magnetization up to 60emu/g as well as pure-phase of Fe3O4 with high crystallinity. Zero-Field-Cooled and Field-Cooled measurements indicated a superparamagnetic nature of as synthesized particles with a low blocking temperature that varies by the amount of dextran introduced in the mixture. Conclusions: The superparamagnetic nanoparticles were heated up to 60°C, inciting a heat shock effect that led to the destruction of the E.coli bacteria. The specific power absorption value obtained was 130 W/g, showing that magnetite–dextran nanostructured fluid appears to be a promising active media for the local magnetic hyperthermia for cancer therapy

    The main features of phraseological units in the Russian and Armenian languages and their translation

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    The study deals with the structure of phraseological units of the Russian and Armenian languages. The researchers analyze figurative meaning of phraseological units appearing on the base of primary, nominative meaning of the words in one or another free phras

    Transformation of Political Culture in Modern Russian Society

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    В данной статье автор проводит анализ трансформации политической культуры современного российского общества. Рассматриваются понятие политической культуры, его специфика, особенности, проводится краткий анализ типов политической культуры. Выделяется основной тип политической культуры России, анализ факторов, повлиявших на процесс трансформации политической культуры, определяются основные итоги этих преобразований.In this article, the author repeats the analysis of the transformation of the political culture of modern Russian society. In the article, adhere to the conservative political culture, its features, features, a brief analysis of the types of political culture. The main type of political culture in Russia is singled out, considering the influence of the analysis that influenced the process of transfor-mation of political culture, the fundamental overall result of the transformation of the political culture of the Russian Federation
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