1,576 research outputs found

    Pneumatic transportation of dispersed medium through a vertical tube immersed into a fluidized bed

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    We discuss the technical problem of how to transport granular material in a vertical direction from the underlying section of a multistage apparatus containing a fluidized bed to an upper section through tubes immersed into the fluidized bed without additional expenditures of energy. The intensity with which the dispersed medium (a mixture of gas and fuel particles) moves through the tube and the mass flowrate of particles are determined by the ratio between the hydraulic resistances of dispersed medium inside the tube and of the fluidized bed outside of it. In turn, this ratio depends on the fluidization number W (W = w s/w 0, where w s is the seepage velocity and w 0 is the fluidization commencement velocity) and on the tube immersing depth into the bed. © 2013 Pleiades Publishing, Inc

    Atomic, electronic and magnetic structure of graphene/iron and nickel interfaces: theory and experiment

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    First-principles calculations of the effect of carbon coverage on the atomic, electronic and magnetic structure of nickel and iron substrates demonstrate insignificant changes in the interatomic distances and magnetic moments on the atoms of the metallic substrates. The coverage of the iron surface by mono- and few-layer graphene induces significant changes in the orbital occupancies and exchange interactions between the layers in contrast to the case of a nickel substrate for which changes in the orbital ordering and exchange interactions are much smaller. Experimental measurements demonstrate the presence of ferromagnetic fcc-iron in Fe@C nanoparticles and the superparamagnetic behavior of Ni@C nanoparticles.Comment: 19 pages, 7 figures, accepted to RSC Advance

    Kostroma cattle breed in the new century: the state and the prospects (review)

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    The article reflects the current state and the prospects of the Kostroma cattle breed development. The creation and improvement of the breed anticipated the formation and further breed development in the domestic and world zoo technical science. In recent years, the number of Kostroma cattle breed has been unreasonably reducing despite its economic valuable traits. At the same time in the Kostroma region there are prospects for preserving the valuable gene pool of one of the best domestic dairy and meat cattle breeds. As a result of directed selection and breeding work with the use of Brown Swiss bulls, a stud milk breed "Karavaevsky KK-1" has been developed. At present cow-champions of the Kostroma breed give up to 12,000 kg of milk per lactation. The milk of the Kostroma breed cows has a high content of protein and fat. The animals of Kostroma breed have good meat qualities, high resistance to a number of diseases, strong ungulate horn, easy adaptability to intensive technologies, good fertility and high productive longevity. To save the Kostroma breed it is important to put on 8-10 bulls of 8 planned lines and related groups for the validation and accumulation of sperm every year. The restoration of previously created lines with high genetic potential should be foreseen. It is necessary to identify and actively use the stud bulls bred in their own breeding farms; to conduct a linear assessment of bulls and daughter heifers by body type for more competent selection. In addition to the generally accepted forms and methods of selection, it is necessary to continue immunogenetic control of the authenticity of the origin of breeding animals and introduce modern methods of DNA technology to assess the breeding and productive qualities of cattle, which will reveal valuable genetic complexes in the best breeding animals and thus 1.5-2 times accelerate the selection processes.Conflict of interest: the authors stated that there was no conflict of interest

    On the kinetic equation approach to pair production by time-dependent electric field

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    We investigate the quantum kinetic approach to pair production from vacuum by time-dependent electric field. Equivalence between this approach and the more familiar S-matrix approach is explicitly established for both scalar and fermion cases. For the particular case of a constant electric field exact solution for kinetic equations is provided and the accuracy of low-density approximation is estimated.Comment: 8 pages, 4 figure

    An improvement of the Berry--Esseen inequality with applications to Poisson and mixed Poisson random sums

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    By a modification of the method that was applied in (Korolev and Shevtsova, 2009), here the inequalities ρ(Fn,Φ)0.335789(β3+0.425)n\rho(F_n,\Phi)\le\frac{0.335789(\beta^3+0.425)}{\sqrt{n}} and ρ(Fn,Φ)0.3051(β3+1)n\rho(F_n,\Phi)\le \frac{0.3051(\beta^3+1)}{\sqrt{n}} are proved for the uniform distance ρ(Fn,Φ)\rho(F_n,\Phi) between the standard normal distribution function Φ\Phi and the distribution function FnF_n of the normalized sum of an arbitrary number n1n\ge1 of independent identically distributed random variables with zero mean, unit variance and finite third absolute moment β3\beta^3. The first of these inequalities sharpens the best known version of the classical Berry--Esseen inequality since 0.335789(β3+0.425)0.335789(1+0.425)β3<0.4785β30.335789(\beta^3+0.425)\le0.335789(1+0.425)\beta^3<0.4785\beta^3 by virtue of the condition β31\beta^3\ge1, and 0.4785 is the best known upper estimate of the absolute constant in the classical Berry--Esseen inequality. The second inequality is applied to lowering the upper estimate of the absolute constant in the analog of the Berry--Esseen inequality for Poisson random sums to 0.3051 which is strictly less than the least possible value of the absolute constant in the classical Berry--Esseen inequality. As a corollary, the estimates of the rate of convergence in limit theorems for compound mixed Poisson distributions are refined.Comment: 33 page

    Excitonic instability and electric-field-induced phase transition towards a two dimensional exciton condensate

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    We present an InAs-GaSb-based system in which the electric-field tunability of its 2D energy gap implies a transition towards a thermodynamically stable excitonic condensed phase. Detailed calculations show a 3 meV BCS-like gap appearing in a second-order phase transition with electric field. We find this transition to be very sharp, solely due to exchange interaction, and so, the exciton binding energy is greatly renormalized even at small condensate densities. This density gradually increases with external field, thus enabling the direct probe of the Bose-Einstein to BCS crossover.Comment: LaTex, 11 pages, 3 ps figures, To appear in PR

    Composition based on aluminum oxide and polydimethylsiloxane matrix for enhancing drug targeting

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    Methodological approaches developed at Research Institute of Clinical and Experimental Lymphology for a number of years allow formulating the importance of embedding active pharmaceutical ingredients (API) in the structure of porous carriers (sorbents). The composition of the carrier and API is an enteral system for prolonged dosing of pharmacological agents, which allows providing a specific pharmacological effect and safety of use. The pores of the media (sorbents) act as containers for API. This is especially important for rapidly absorbed drugs, which include, for example, lithium preparations that are used in narrow concentration limits due to their side effects. At the moment, an innovative technology for creating new medicines with an improved combination of efficiency and safety (pharmacological upgrade) has been developed and implemented. The essence of the technology is to create a composition of aluminum oxide and polydimethylsiloxane (matrix) and an active pharmacological ingredient (API). A study of two drugs based on matrix / lithium citrate and matrix / melatonin showed continued specific pharmacological activity of API, better pharmacokinetics, and better safety parameters. The matrix of aluminum oxide and polydimethylsiloxane provides an upgrade of the pharmacological properties of drugs for the dosed and safe delivery of API to the zone of their therapeutic effect
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