333 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
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
Exclusive photoproduction of in proton-proton and proton-antiproton scattering
Protons and antiprotons at collider energies are a source of high energy
Weizs\"acker--Williams photons. This may open a possibility to study exclusive
photoproduction of heavy vector mesons at energies much larger than possible at
the HERA accelerator. Here we present a detailed investigation of the exclusive
photoproduction in proton-proton (RHIC, LHC) and proton-antiproton
(Tevatron) collisions. We calculate several differential distributions in , as well as transverse momentum distributions of 's. We
discuss correlations in the azimuthal angle between outgoing protons or proton
and antiproton as well as in the () space. Differently from
electroproduction experiments, here both colliding beam particles can be a
source of photons, and we find large interference terms in azimuthal angle
distributions in a broad range of rapidities of the produced meson. We also
include the spin--flip parts in the electromagnetic vertices. We discuss the
effect of absorptive corrections on various distributions. Interestingly,
absorption corrections induce a charge asymmetry in rapidity distributions, and
are larger for reactions than for the case. The reaction
considered here constitutes an important nonreduceable background in recently
proposed searches for odderon exchange.Comment: 22 pages, 20 figures; dedicated to Kolya Nikolaev on the occasion of
his 60th birthday; 4 figures and discussion adde
OBTAINING OF FERROSILICOCHROMIUM POWDER ALLOY BY SILICOTHERMIC REDUCTION AND STUDY OF THE MECHANISM OF THIS PROCESS
The process of obtaining a powder ferrosilicochromic alloy by the method of silicothermic reduction of local chromites and slags of copper smelters was investigated. The mechanism of this process has been studied. It is established that the best results are obtained in the case of slag / chromite ratio = 1: 1, when an alloy with microdispersed structure and high strength is obtained. The optimum composition of the resulting alloy is as follows: 35,1% Fe; 36,35% Si and 28,53% Cr, with a metal yield of 98,4%. The obtained alloy powder can be used as an acidified and alloying additive to chromium- and silicon-containing stainless composite materials. The aspects of the process for obtaining FeSiCr alloy have been developed. The maximum temperature (Tc) and the linear propagation velocity of the combustion wave (Uv) are determined graphically. The mechanism of the formation of FeSiCr in the SHS process is explained.The process of obtaining a powder ferrosilicochromic alloy by the method of silicothermic reduction of local chromites and slags of copper smelters was investigated. The mechanism of this process has been studied. It is established that the best results are obtained in the case of slag / chromite ratio = 1: 1, when an alloy with microdispersed structure and high strength is obtained. The optimum composition of the resulting alloy is as follows: 35,1% Fe; 36,35% Si and 28,53% Cr, with a metal yield of 98,4%. The obtained alloy powder can be used as an acidified and alloying additive to chromium- and silicon-containing stainless composite materials. The aspects of the process for obtaining FeSiCr alloy have been developed. The maximum temperature (Tc) and the linear propagation velocity of the combustion wave (Uv) are determined graphically. The mechanism of the formation of FeSiCr in the SHS process is explained
Dielectric model of point charge defects in insulating paraelectric perovskites
Some point defects (i.e., oxygen vacancies) create deep trapping levels in the bandgap of the paraelectric phase ferroelectric crystals. Under applied DC field the traps release electrons via the Poole-Frenkel mechanism and become charged. The electric field of a point charge polarizes the crystal locally reducing its permittivity. In this paper a simple theory is proposed for calculating the DC field dependent apparent (measureable) permittivity of a paraelectric crystal with point charge defects. It is shown that the apparent permittivity of a paraelectric crystal may be sufficiently lower as compared with the defectless crystal. This reduction is in addition to the possible reduction of the apparent permittivity associated with the interfacial "dead" layers and strain
INVESTIGATION ON STABILITY OF TEXTILE MATERIALS FOR OVERALLS PROCESSED BY NEW BIOCIDAL PREPARATIONS
This article is devoted to the research of new promising biocidal preparations, in particular ethyl, allyl and methyl, which promote the improvement of the consumer properties of textile materials and increase their durability. The problem of protecting textile materials and products from microbiological destruction is complex and multifaceted, and its successful solution requires coordinated and focused efforts of specialists of various profiles. Of particular relevance is the search for effective ways to protect against microbiological destruction of textile materials. And today one of such methods of protection is to provide textiles with biocidal properties, which not only prevents the growth of bacteria, but can also provide a high level of wear resistance of tissues. The aim of the work was to study the impact of new low-toxic biocidal drugs on the stability of coloring of textile materials to the effect of various physical and chemical factors. In the research, the method and technology of providing biocidal properties to textile materials for the production of overalls, in particular, impregnation of textile materials in alcoholic solution of biocidal preparations, was developed. As samples were selected fabrics of different chemical composition, which are intended for the manufacture of overalls. The best results were obtained with dry friction, and, treatment, does not significantly affect the stability of color, and in the case of cotton-polyester fabric, on the contrary, even increases it.
Low indicators of the stability of color to the action of wet friction is due to the low resistance of colors to water
STUDY OF THE EXISTING SYSTEM OF LOGISTICS SUPPORT IN CONSTRUCTION
The article deals with the concept of logistics, presents particular logistical support in a number of countries. The role and significance of the subsystem of logistics in the construction industry. The problems of logistics in the field of construction. The article suggests measures to improve the system of logistics domestic construction industry
STUDY OF THE EXISTING SYSTEM OF LOGISTICS SUPPORT IN CONSTRUCTION
The article deals with the concept of logistics, presents particular logistical support in a number of countries. The role and significance of the subsystem of logistics in the construction industry. The problems of logistics in the field of construction. The article suggests measures to improve the system of logistics domestic construction industry
Elastic pp Scattering at LHC Energies
We consider the first LHC data for elastic pp scattering in the framework of
Regge theory with multiple Pomeron exchanges. The simplest eikonal approach
allows one to describe differential elastic cross sections at LHC, as well as
pp and scattering at lower collider energies, on a reasonable level.Comment: 11 pages, 5 figures, and 1 tabl
Effects of α-amylase, endo-xylanase and exoprotease combination on dough properties and bread quality
Received: January 31st, 2021 ; Accepted: May 2nd, 2021 ; Published: May 6th, 2021 ; Correspondence: [email protected] enzymes composition is an actual alternative to chemicals to improve functional
properties of flours and to generate changes in the structure of the dough and bread quality. The
objective of this study was to analyze the individual and synergistic effects of enzymes
preparation (α-amylase, endo-xylanase and exoprotease), newly produced in Russia, on dough
properties and bread quality made from wheat flour with different amylolytic activity.
Reofermentometric results revealed decreases in gas-forming capacity of dough by 10.0–13.9%
when single α-amylase preparates were used. The α-amylase addition had significant effect on
gas retention coefficient in flour possessed low amylolytic activity. The effect of endo-xylanase
and exoprotease on hydration and amount of wheat gluten was established. The fractional
composition of gluten proteins in the dough made with combination of endo-xylanase and
exoprotease was established using Lowry method immediately after kneading and after
fermentation. It was found that mainly water-soluble, alcohol-soluble and alkaline-soluble
proteins were undergone by transformation. The bread with enzymes had a higher specific
volume, porosity and aldehyde content and lower shape stability indicator than the control bread
made without enzymes. Bread with enzymes was characterized by tenderer and not crumbly
crumb with developed thin-walled uniform porosity compared to the control. The crusts were
more brightly colored. The combined usage of α-amylase and endo-xylanase and exoprotease
retarded bread staling during 5-day storage period. New enzyme composition may be a potentially
strong candidate for future applications in the bread-making industry
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