1,342 research outputs found

    Effect of charged line defects on conductivity in graphene: Numerical Kubo and analytical Boltzmann approaches

    Get PDF
    Charge carrier transport in single-layer graphene with one-dimensional charged defects is studied theoretically. Extended charged defects, considered an important factor for mobility degradation in chemically-vapor-deposited graphene, are described by a self-consistent Thomas-Fermi potential. A numerical study of electronic transport is performed by means of a time-dependent real-space Kubo approach in honeycomb lattices containing millions of carbon atoms, capturing the linear response of realistic size systems in the highly disordered regime. Our numerical calculations are complemented with a kinetic transport theory describing charge transport in the weak scattering limit. The semiclassical transport lifetimes are obtained by computing scattered amplitudes within the second Born approximation. The transport electron-hole asymmetry found in the semiclassical approach is consistent with the Kubo calculations. In the strong scattering regime, the conductivity is found to be a sublinear function of electronic density and weakly dependent on the Thomas-Fermi screening wavelength. We attribute this atypical behavior to the extended nature of one-dimensional charged defects. Our results are consistent with recent experimental reports.Comment: 15 pages, 9 figure

    Extrapolation of Multiplicity distribution in p+p(\bar(p)) collisions to LHC energies

    Full text link
    The multiplicity (N_ch) and pseudorapidity distribution (dN_ch/d\eta) of primary charged particles in p+p collisions at Large Hadron Collider (LHC) energies of \sqrt(s) = 10 and 14 TeV are obtained from extrapolation of existing measurements at lower \sqrt(s). These distributions are then compared to calculations from PYTHIA and PHOJET models. The existing \sqrt(s) measurements are unable to distinguish between a logarithmic and power law dependence of the average charged particle multiplicity () on \sqrt(s), and their extrapolation to energies accessible at LHC give very different values. Assuming a reasonably good description of inclusive charged particle multiplicity distributions by Negative Binomial Distributions (NBD) at lower \sqrt(s) to hold for LHC energies, we observe that the logarithmic \sqrt(s) dependence of are favored by the models at midrapidity. The dN_ch/d\eta versus \eta for the existing measurements are found to be reasonably well described by a function with three parameters which accounts for the basic features of the distribution, height at midrapidity, central rapidity plateau and the higher rapidity fall-off. Extrapolation of these parameters as a function of \sqrt(s) is used to predict the pseudorapidity distributions of charged particles at LHC energies. dN_ch/d\eta calculations from PYTHIA and PHOJET models are found to be lower compared to those obtained from the extrapolated dN_ch/d\eta versus \eta distributions for a broad \eta range.Comment: 11 pages and 13 figures. Substantially revised and accepted for publication in Journal of Physics

    Charged-Particle Multiplicity in Proton-Proton Collisions

    Full text link
    This article summarizes and critically reviews measurements of charged-particle multiplicity distributions and pseudorapidity densities in p+p(pbar) collisions between sqrt(s) = 23.6 GeV and sqrt(s) = 1.8 TeV. Related theoretical concepts are briefly introduced. Moments of multiplicity distributions are presented as a function of sqrt(s). Feynman scaling, KNO scaling, as well as the description of multiplicity distributions with a single negative binomial distribution and with combinations of two or more negative binomial distributions are discussed. Moreover, similarities between the energy dependence of charged-particle multiplicities in p+p(pbar) and e+e- collisions are studied. Finally, various predictions for pseudorapidity densities, average multiplicities in full phase space, and multiplicity distributions of charged particles in p+p(pbar) collisions at the LHC energies of sqrt(s) = 7 TeV, 10 TeV, and 14 TeV are summarized and compared.Comment: Invited review for Journal of Physics G -- version 2: version after referee's comment

    Retrospective analysis and current state of the improving qualification of pharmacists on quality questions of medicines in Shupyk NMAPE

    Get PDF
    To date, one of the advanced educational and research centers of Kiev and Ukraine, which is the improving qualification of pharmacists on quality questions of medicines, is the Department of Quality Control and Standardization of Medicines of Shupyk National Medical Academy of Post-Graduate Education (NMAPE). The aim of the work is to analyze the historical stages of formation and development of the Department of Quality Control and Standardization of Medicines of Shupyk NMAPE. The materials of the research are: archival and current documentation of the department, scientific publications, encyclopedic reference materials. Studies were conducted using methods: content analysis, historical documentary, generalization and systematization of historical data. In this work a retrospective analysis was performed and current state of activity of the Department of Quality Control and Standardization of Medicines of Shupyk NMAPE was considered. The basic stages of formation and historical development of the department during 1938 to 2018 are determined. The contribution to the development of pharmaceutical education and science of professors (prof. Ya.A. Fialkov, N.P. Maksyutina, O.M Gritsenko, N.O. Vetiutneva, etc.) was noted. The educational cycles, taught at the department, are shown, namely: specialization cycles, internships, pre-certification training in the specialties «Analytical Control Pharmacy», «General Pharmacy»; thematic improvement cycles on topical issues of pharmacy, quality assurance and prevention of falsification of medicines, functioning of quality systems of pharmacies (for pharmacists); cycles of improvement of assistant pharmacists; thematic improvement cycles on the scientific basis of phytotherapy and the use of modern medicines based on active ingredients of natural origin (for physicians). The basis of educational-methodical and scientific production of the department is described. The main areas of the scientific activity of the department are described, covering the following areas: development of methods for the investigation of complex synthetic compounds, methods for express analysis of extemporal multicomponent medicines, methods for quality control the of phytotherapeutic and homeopathic medicines; study of the composition and intermolecular interaction of biologically active compounds in plants and phytopreparations; synthesis and creation of new medicines and dietary supplements; study of the properties of crown compounds; study of the interaction of auxiliary substances with active ingredients; research on increasing the solubility of difficult soluble substances; substantiation of methodological and organizational-methodical principles of quality assurance of medicines at stages of wholesale, retail sale and medical use, etc. Analysis of the activities of the Department of Quality Control and Standardization of Medicines of Shupyk NMAPE during 1938 to 2018 testifies to its significant contribution and great potential for the development of pharmaceutical science and practice, in particular in the direction of the creation, standardization, assurance and control of quality of medicines and dietary supplements

    Comparative molecular biological analysis of membrane transport genes in organisms

    Get PDF
    Comparative analyses of membrane transport genes revealed many differences in the features of transport homeostasis in eight diverse organisms, ranging from bacteria to animals and plants. In bacteria, membrane-transport systems depend mainly on single genes encoding proteins involved in an ATP-dependent pump and secondary transport proteins that use H+ as a co-transport molecule. Animals are especially divergent in their channel genes, and plants have larger numbers of P-type ATPase and secondary active transporters than do other organisms. The secondary transporter genes have diverged evolutionarily in both animals and plants for different co-transporter molecules. Animals use Na+ ions for the formation of concentration gradients across plasma membranes, dependent on secondary active transporters and on membrane voltages that in turn are dependent on ion transport regulation systems. Plants use H+ ions pooled in vacuoles and the apoplast to transport various substances; these proton gradients are also dependent on secondary active transporters. We also compared the numbers of membrane transporter genes in Arabidopsis and rice. Although many transporter genes are similar in these plants, Arabidopsis has a more diverse array of genes for multi-efflux transport and for response to stress signals, and rice has more secondary transporter genes for carbohydrate and nutrient transport

    Increasing the Operation Efficiency of Air Conditioning System for Integrated Power Plant on the Base of Its Monitoring

    Get PDF
    Increasing the Operation Efficiency of Air Conditioning System for Integrated Power Plant on the Base of Its Monitoring / E. Trushliakov, A. Radchenko, S. Forduy, A. Zubarev, A. Hrych // Advances in intelligent systems and computing. – 2020. – Т. 1113 AISC . – P. 351–360Abstract. The efficiency of reciprocating gas engines of integrated energy systems (IES) for combined electricity, heat and refrigeration generation is strictly influenced by their cyclic air temperatures. To evaluate the effect of gas engine cyclic air deep cooling, compared with conventional its cooling, the data on dependence of fuel consumption and power output of gas engine JMS 420 GS-N.L on its inlet air temperature at varying ambient air temperatures at the entrance of the radiator for scavenge air cooling were received. The results of treatment of gas engine efficiency monitoring proved non-effective operation of conventional chilling all the ambient air, coming into the engine room, because of increased air temperature at the inlet of turbocharger (TC), caused by heat influx from surroundings in the engine room. A new method of gas engine inlet air two-stage cooling at increased ambient air temperatures and advanced cyclic air cooling system with absorption lithium-bromide chiller and refrigerant ejector chiller was proposed. With this chilled water from absorption lithiumbromide chiller is used as a coolant in the first high-temperature stage of engine inlet air cooler and boiling refrigerant of ejector chiller in the second lowtemperature stage

    National records of 3000 European bee and hoverfly species: A contribution to pollinator conservation

    Get PDF
    Pollinators play a crucial role in ecosystems globally, ensuring the seed production of most flowering plants. They are threatened by global changes and knowledge of their distribution at the national and continental levels is needed to implement efficient conservation actions, but this knowledge is still fragmented and/or difficult to access. As a step forward, we provide an updated list of around 3000 European bee and hoverfly species, reflecting their current distributional status at the national level (in the form of present, absent, regionally extinct, possibly extinct or non-native). This work was attainable by incorporating both published and unpublished data, as well as knowledge from a large set of taxonomists and ecologists in both groups. After providing the first National species lists for bees and hoverflies for many countries, we examine the current distributional patterns of these species and designate the countries with highest levels of species richness. We also show that many species are recorded in a single European country, highlighting the importance of articulating European and national conservation strategies. Finally, we discuss how the data provided here can be combined with future trait and Red List data to implement research that will further advance pollinator conservation
    corecore