150 research outputs found

    Establishing The Equipment-methodical Support For Determining The Properties Of Extracts Of Grape Pomace Extracts Produced In The Subcreative Water Environment

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    Research objective: development of a high-pressure reactor for researching the process of extraction of grape pomace by the subcritical water and determining the parameters, providing the maximum yield of various target products – biologically active substances; formation of methodological support for raw material preparation, qualitative and quantitative analysis of extracts, produced by the subcritical extraction. As a result of simulation in the ANSYS system of the stress-strain state of the walls of the reactor chamber and a set of calculation operations, a high-pressure reactor was created that meets the requirements. The formed methodical complex for determining the physicochemical properties of extracts and the content of various biologically active substances included methods for preparing samples and determining the yield of dry extractive substances, evaluation of extraction of polyphenols (tannic-catechol complex), evaluation of extraction of reducing substances, identification furfural and gallic acids, estimation of free organic acids in terms of tartaric acid, evaluation of antioxidant activity of extracts). This methodological complex allows us to estimate the physico-chemical properties of the extracted biologically active substances

    Four-dimensional integration by parts with differential renormalization as a method of evaluation of Feynman diagrams

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    It is shown how strictly four-dimensional integration by parts combined with differential renormalization and its infrared analogue can be applied for calculation of Feynman diagrams.Comment: 6 pages, late

    Exponential Renormalization II: Bogoliubov's R-operation and momentum subtraction schemes

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    This article aims at advancing the recently introduced exponential method for renormalisation in perturbative quantum field theory. It is shown that this new procedure provides a meaningful recursive scheme in the context of the algebraic and group theoretical approach to renormalisation. In particular, we describe in detail a Hopf algebraic formulation of Bogoliubov's classical R-operation and counterterm recursion in the context of momentum subtraction schemes. This approach allows us to propose an algebraic classification of different subtraction schemes. Our results shed light on the peculiar algebraic role played by the degrees of Taylor jet expansions, especially the notion of minimal subtraction and oversubtractions.Comment: revised versio

    Zero-mode contribution to the light-front Hamiltonian of Yukawa type models

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    Light-front Hamiltonian for Yukawa type models is determined without the framework of canonical light-front formalism. Special attention is given to the contribution of zero modes.Comment: 14 pages, Latex, revised version with minor changes, Submitted to J.Phys.

    OPE coefficient functions in terms of composite operators only. Singlet case

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    A method for calculating coefficient functions of the operator product expansion, which was previously derived for the non-singlet case, is generalized for the singlet coefficient functions. The resulting formula defines coefficient functions entirely in terms of corresponding singlet composite operators without applying to elementary (quark and gluon) fields. Both "diagonal" and "non-diagonal" gluon coefficient functions in the product expansion of two electromagnetic currents are calculated in QCD. Their renormalization properties are studied.Comment: 33 pages, 15 figures, minor corrections are mad

    Operator product expansion coefficient functions in terms of composite operators only. Nonsinglet case

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    A new method for calculating the coefficient functions of the operator product expansion is proposed which does not depend explicitly on elementary fields. Coefficient functions are defined entirely in terms of composite operators. The method is illustrated in the case of QCD nonsinglet operators.Comment: Derivation of the main formula is improved. References are added. To appear in Physical Review

    Adhesive organelles of Gram-negative pathogens assembled with the classical chaperone/usher machinery: structure and function from a clinical standpoint

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    This review summarizes current knowledge on the structure, function, assembly and biomedical applications of the superfamily of adhesive fimbrial organelles exposed on the surface of Gram-negative pathogens with the classical chaperone/usher machinery. High-resolution three-dimensional (3D) structure studies of the minifibers assembling with the FGL (having a long F1-G1 loop) and FGS (having a short F1-G1 loop) chaperones show that they exploit the same principle of donor-strand complementation for polymerization of subunits. The 3D structure of adhesive subunits bound to host-cell receptors and the final architecture of adhesive fimbrial organelles reveal two functional families of the organelles, respectively, possessing polyadhesive and monoadhesive binding. The FGL and FGS chaperone-assembled polyadhesins are encoded exclusively by the gene clusters of the gamma 3- and kappa-monophyletic groups, respectively, while gene clusters belonging to the gamma 1-, gamma 2-, gamma 4-, and pi-fimbrial clades exclusively encode FGS chaperone-assembled monoadhesins. Novel approaches are suggested for a rational design of antimicrobials inhibiting the organelle assembly or inhibiting their binding to host-cell receptors. Vaccines are currently under development based on the recombinant subunits of adhesins

    Non-Linear Algebra and Bogolubov's Recursion

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    Numerous examples are given of application of Bogolubov's forest formula to iterative solutions of various non-linear equations: one and the same formula describes everything, from ordinary quadratic equation to renormalization in quantum field theory.Comment: LaTex, 21 page

    Generalized Quark Transversity Distribution of the Pion in Chiral Quark Models

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    The transversity generalized parton distributions (tGPDs) of the the pion, involving matrix elements of the tensor bilocal quark current, are analyzed in chiral quark models. We apply the nonlocal chiral models involving a momentum-dependent quark mass, as well as the local Nambu--Jona-Lasinio with the Pauli-Villars regularization to calculate the pion tGPDs, as well as related quantities following from restrained kinematics, evaluation of moments, or taking the Fourier-Bessel transforms to the impact-parameter space. The obtained distributions satisfy the formal requirements, such as proper support and polynomiality, following from Lorentz covariance. We carry out the leading-order QCD evolution from the low quark-model scale to higher lattice scales, applying the method of Kivel and Mankiewicz. We evaluate several lowest-order generalized transversity form factors, accessible from the recent lattice QCD calculations. These form factors, after evolution, agree properly with the lattice data, in support of the fact that the spontaneously broken chiral symmetry is the key element also in the evaluation of the transversity observables.Comment: 17 pages, 17 figures, regular pape

    Structural Insight into Archaic and Alternative Chaperone-Usher Pathways Reveals a Novel Mechanism of Pilus Biogenesis

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    AVZ is supported by the Finnish Academy (grants 140959 and 273075; http://sciencenordic.com/partner/academy-finland) and Sigrid Juselius Foundation (grant 2014; www.sigridjuselius.fi/foundation). SMis supported by the Wellcome Trust (Senior Investigator Award 100280, Programme grant 079819; http://www.wellcome.ac.uk) The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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