Problems of and perspectives to electronic B2B trade on the basis of Bulgaria

Development of information and communication technologies led to coming of the virtual market, which creates the foundations of expanding the opportunities for profit and growth and outlines new business horizons, gradually deleting geographical boundaries. The report analyses incoming qualitative changes in the field of marketing and electronic B2B trade, caused by the wide entering of modern information and communication technologies in economy, and presents the problems of and perspectives to electronic B2B trade in Bulgaria

ZINC CONTENT IN THE SERUM AND CARBONIC ANHYDRASE INHIBITION

No abstract

Thermal Breakage and Self-Healing of a Polymer Chain under Tensile Stress

We consider the thermal breakage of a tethered polymer chain of discrete segments coupled by Morse potentials under constant tensile stress. The chain dynamics at the onset of fracture is studied analytically by Kramers-Langer multidimensional theory and by extensive Molecular Dynamics simulations in 1D- and 3D-space. Comparison with simulation data in one- and three dimensions demonstrates that the Kramers-Langer theory provides good qualitative description of the process of bond-scission as caused by a {\em collective} unstable mode. We derive distributions of the probability for scission over the successive bonds along the chain which reveal the influence of chain ends on rupture in good agreement with theory. The breakage time distribution of an individual bond is found to follow an exponential law as predicted by theory. Special attention is focused on the recombination (self-healing) of broken bonds. Theoretically derived expressions for the recombination time and distance distributions comply with MD observations and indicate that the energy barrier position crossing is not a good criterion for true rupture. It is shown that the fraction of self-healing bonds increases with rising temperature and friction.Comment: 25 pages, 13 picture

Unusual persistence of superconductivity against high magnetic fields in the strongly-correlated iron-chalcogenide film FeTe:Ox_{x}

We report an unusual persistence of superconductivity against high magnetic fields in the iron chalcogenide film FeTe:O$_{x}$ below ~ 2.5 K. Instead of saturating like a mean-field behavior with a single order parameter, the measured low-temperature upper critical field increases progressively, suggesting a large supply of superconducting states accessible via magnetic field or low-energy thermal fluctuations. We demonstrate that superconducting states of finite momenta can be realized within the conventional theory, despite its questionable applicability. Our findings reveal a fundamental characteristic of superconductivity and electronic structure in the strongly-correlated iron-based superconductors.Comment: 10 pages, 3 figure

Recent trends in state of landscapes and shoreline dynamics in the Bulgarian sector of the Black Sea

The article analyzes the contemporary processes of natural and human-induced shore- line dynamics between cape Kaliakra and cape Emine, Bulgarian Black Sea coastal zone. Main accent is put on the anthropogenic impact on beach morphodynamics, coastal erosion, sediment transport and accretion influenced by land use changes and technogenic load. The stages of recent landscape transformations since the beginning of the XX century are discussed chronologically. Assumptions are made with reference to existing relationships among coastal geomorphic processes, land use dynamics, levels of anthropogenization and coastal landscape change at the investigated area.Проанализировано современные процессы естественной и подверженной антропогенному влиянию динамики береговой линии между мысом Калиакра и мысом Емине на болгарском побережье Черного моря. Основное внимание уделено воздействию антропогенных факторов на береговую морфодинамику, прибрежную эрозию, транспортировку и аккумуляцию осадков под влиянием изменений в использовании земель и техногенной нагрузки. Стадии недавних преобразований ландшафта с начала XX столетия рассмотрены хронологически. Сделаны выводы о взаимоотношениях прибрежных процессов, геоморфологии, динамики использования земли, уровня антропогенизации и изменения прибрежного ландшафта на исследованной территории.Проаналізовано сучасні процеси природної і зазнавшої антропогенного впливу динаміки берегової лінії між мисом Каліакра і мисом Еміне на болгарському узбережжі Чорного моря. Основну увагу приділено впливу антропогенних чинників на берегову морфодинаміку, прибережну ерозію, транспортування й акумуляцію осадів під впливом змін у використанні земель і техногенного навантаження. Стадії недавніх перетворень ландшафту з початку XX сторіччя розглянуто хронологічно. Зроблено висновки про взаємовідношення прибережних процесів, геоморфології, динаміки використання землі, рівня антропогенізації та зміни прибережного ландшафту на дослідженій території

Forced Imbibition - a Tool for Determining Laplace Pressure, Drag Force and Slip Length in Capillary Filling Experiments

When a very thin capillary is inserted into a liquid, the liquid is sucked into it: this imbibition process is controlled by a balance of capillary and drag forces, which are hard to quantify experimentally, in particularly considering flow on the nanoscale. By computer experiments using a generic coarse-grained model, it is shown that an analysis of imbibition forced by a controllable external pressure quantifies relevant physical parameter such as the Laplace pressure, Darcy's permeability, effective pore radius, effective viscosity, dynamic contact angle and slip length of the fluid flowing into the pore. In determining all these parameters independently, the consistency of our analysis of such forced imbibition processes is demonstrated.Comment: 4 pages, 5 figure