906 research outputs found

    Deviation pattern approach for optimizing perturbative terms of QCD renormalization group invariant observables

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    We first consider the idea of renormalization group-induced estimates, in the context of optimization procedures, for the Brodsky-Lepage-Mackenzie approach to generate higher-order contributions to QCD perturbative series. Secondly, we develop the deviation pattern approach (DPA) in which through a series of comparisons between lower-order RG-induced estimates and the corresponding analytical calculations, one could modify higher-order RG-induced estimates. Finally, using the normal estimation procedure and DPA, we get estimates of αs4\alpha_s^4 corrections for the Bjorken sum rule of polarized deep-inelastic scattering and for the non-singlet contribution to the Adler function.Comment: 5 pages, proceedings for the XXIII International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics

    Low Q2Q^2 proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

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    The idea of the meson cloud approach in the chiral quark model has been extended to include gluon cloud in order to achieve the parton densities in the nucleon, based on the constitute quark framework. The splitting function of the quark to the quark-meson and quark-gluon at low Q2Q^2 value are used to obtain parton densities in the constituent quark. The phenomenological constituent model is employed to extract the parton distributions in the proton at low Q2Q^2 value. Since we have access to the parton densities at low Q2Q^2, we are able to obtain F2(x,Q2)F_{2}(x,Q^2) structure function at low Q2Q^2 value. The result is in good agreement with available experimental data and some theoretical models. To confirm the validity of our calculations, the fraction of total momentum of proton which is carried by gluon at high Q2Q^2 and also the Gottfried sum rule are computed. The results are in good agreement with what are expected.Comment: 13 pages, 3 figure

    Hadronization properties in e+e- annihilation at S=0 60GeV centre of mass energy

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    The hadronic events from the experimental data , as well as the PYTHIA Monte-carlo data at the 60 GeV centre of mass energies are studied.We present the general properties of multihadron final states produced by e+e- .Globalshape, inclusive charged-particle, and particle-flow distributions are presented. Our measurements are comparedwith QCD + fragmentation models that use either leading-logarithmic parton-shower evolution or QCD matrixelements at the parton level, and either string or cluster fragmentation for hadronization. Possible explanations forourcompariaon are presented in this paper

    Extracting the QCD Cutoff Parameter Using the Bernstein Polynomials and the Truncated Moments

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    Since there are not experimental data over the whole range of x-Bjorken variable, that is, 0<x<1, we are inevitable in practice to do the integration for Mellin moments over the available range of experimental data. Among the methods of analysing DIS data, there are the methods based on application of Mellin moments. We use the truncated Mellin moments rather than the usual moments to analyse the EMC collaboration data for muon-nucleon and WA25 data for neutrino-deuterium DIS scattering. How to connect the truncated Mellin moments to usual ones is discussed. Following that we combine the truncated Mellin moments with the Bernstein polynomials. As a result, Bernstein averages which are related to different orders of the truncated Mellin moment are obtained. These averaged quantities can be considered as the constructed experimental data. By accessing the sufficient experimental data we can do the fitting more precisely. We do the fitting at leading order and next-to-leading order approximations to extract the QCD cutoff parameter. The results are in good agreement with what is being expected

    Electrocatalytic Behavior of Levodopa at MultiWall Carbon Nanotubes and 4-((E)-(2-Methyl-4-Nitrophenylimino) Methyl) Benzene-1,2-Diol Modified Glassy Carbon Electrode

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    This work describes a glassy carbon electrode (GCE) modified by 4-((E)-(2-methyl-4-nitrophenylimino) methyl) benzene-1,2-diol (abbreviated as MBD) and multiwall carbon nanotubes (MWNT) as an electrochemical sensor for monitoring of levodopa (LD) concentration. Different electrochemical parameters of MBD were obtained at MWCNT-GCE by cyclic voltammetry. Also the electrocatalytic behavior of LD was investigated at the MBD-MWNT-GCE by cyclic voltammetry, chronoamperometry and differential pulse voltammetry. Using the electrocatalysis of LD V in phosphate buffer solution pH 7.0 on this modified electrode it is possible to obtain a linear calibration curve from 5.0 10 – 7 to 9.0 10 – 4 M and a detection limit of 0.37 μM for LD by differential pulse voltammetry. The electrode was successfully applied for determination of LD in real sample. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3493

    Triterpenic and phenolic acids production changed in Salvia officinalis via in vitro and in vivo polyploidization: A consequence of altered genes expression

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    The induction of polyploidy is an efficient technique for creating a diversity of genetic, phenotypic, and phytochemical novelties in plant taxa. Sage (Salvia officinalis L.) is a well-known medicinal plant rich of valuable bioactive molecules such as triterpenic and phenolic acids. In the present study, the effect of in vitro and in vivo polyploidization on morphological characteristics, anatomical structures, phytochemical traits, and expression level of the genes involved in the biosynthesis of major triterpenic acids (ursolic, betulinic, and oleanolic acids) of the plant was studied. The sterile seeds treated with different concentrations (0, 0.05, 0.1, and 0.2%) of colchicine for 24 and 48 h were considered for polyploidy induction. Flow cytometry and chromosome counting were used to confirm the ploidy level of diploid (2n = 2x = 14, 2C DNA = 1.10 pg) and tetraploid (2n = 4x = 28, 2C DNA = 2.12 pg) plants after seven months. The highest polyploidy induction was obtained by applying 0.1% (w/v) colchicine for 48 h with an efficiency of 19.05% in vitro tetraploidy. Polyploids showed differences in leaf shape and color, leaf and stem thickness, trichrome density, root length, plant height, and number of leaves compared to diploid plants. There was also a significant decrease in rosmarinic acid content in polyploid (plants) as compared to diploid plants. Although a significant decrease in ursolic acid content was observed in polyploids, betulinic acid content associated with the expression levels of genes encoding enzymes being active in triterpene biosynthesis such as squalene epoxidase (SQE) and lupeol synthase (LUS). The expression of SQE and LUS was significantly increased in in vitro tertaploids (2.9-fold) and in vivo mixoploids (2.4-fold). The results confirm the idea that induced polyploidy can randomly alter breeding traits of plants as well as the content of bioactive compounds

    Induced polyploidy and broad variation in phytochemical traits and altered gene expression in Salvia multicaulis

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    Induced polyploidy is nowadays an important strategy in plant breeding and for the development of new crops. Salvia multicaulis Vahl is a valuable medicinal plant that produce precious bioactive metabolites including triterpenic acids (TAs) and phenolic compounds. Hence, at first, for selecting elite lines, both HPLC and GC-MC analyses were performed on fourteen S. multicaulis lines. Then, seeds of selected lines of S. multicaulis were exposed to different concentrations (0.00, 0.05, 0.1, and 0.2 %) of colchicine for 24 or 48 h. The flow cytometric analysis and chromosome counting were used to confirm ploidy level of tetraploid control (2n = 4x = 28, 2C DNA = 1.36 pg) and hexaploid (2n = 6x = 42, 2C DNA = 1.97 pg) plants after seven-month. For the first time, the effects of in vitro polyploidization on morphological characteristics, TAs and phenolic acid contents as well as on the expression of six TAs biosynthesis related genes were investigated. The highest efficiency of hexaploidy (12.76 %) was achieved 48 h after exposure to 0.1 % colchicine concentration. The hexaploid plants showed different growth traits compared with those of tetraploid control plant; indeed, hexaploid plants had leaves with a darker green color, a lower trichome density, and lower plant height and root length. Moreover, there was a significant increase in rosmarinic acid and caffeic acid content in hexaploid plants compared with tetraploid control plants. Also, the increase of oleanolic acid (1.33 fold) content in hexaploids was associated with a significant increased expression of squalene synthase (SQS) and β-amyrin synthase (BAS) genes in hexaploid plants. Nevertheless, a significant decreased expression of squalene epoxidase (SQE), mixed-function amyrin synthase (MFAS), and lupeol synthase (LUS) was observed in hexaploid plants, that led to a reduced content of ursolic acid and betulinic acid compared with tetraploid control plants. These results confirmed that polyploidization is a breeding method with stochastic results in secondary metabolites production and gene expression related to biosynthetic pathways

    Phenolics diversity among wild populations of Salvia multicaulis: as a precious source for antimicrobial and antioxidant applications

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    The genus Salvia L. belongs to the Lamiaceae family including several known species rich in natural compounds that are extensively used in pharmaceutical, food, and cosmetic industries. Salvia multicaulis populations contain a broad diversity of flavonoids and phenolic acids. The present study aimed to explore biological and pharmacological effects including antimicrobial and antioxidant activities of nineteen S. multicaulis populations (SMPs) grown in Iran for the first time. High content of rosmarinic acid (RA) in SMP12 (Gazan) (5.65 ± 0.33 mg/g DW) caused high antimicrobial activity against two bacteria (Staphylococcus aureus, Escherichia coli) and the fungus Candida albicans, while methanolic extract of SMP1 (Taleghan) showed high antioxidant activity due to high content of salvianolic acid A (SAA) and quercetin (0.53 ± 0.04 and 0.49 ± 0.12 mg/g DW, respectively). Altogether these results can be considered for further commercial exploitations to meet the demands of the food and pharmaceutical industries
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