1+1 Dimensional Hydrodynamics for High-energy Heavy-ion Collisions

A 1+1 dimensional hydrodynamical model in the light-cone coordinates is used to describe central heavy-ion collisions at ultrarelativistic bombarding energies. Deviations from Bjorken's scaling are taken into account by choosing finite-size profiles for the initial energy density. The sensitivity of fluid dynamical evolution to the equation of state and the parameters of initial state is investigated. Experimental constraints on the total energy of produced particles are used to reduce the number of model parameters. Spectra of secondary particles are calculated assuming that the transition from the hydrodynamical stage to the collisionless expansion of matter occurs at a certain freeze-out temperature. An important role of resonances in the formation of observed hadronic spectra is demonstrated. The calculated rapidity distributions of pions, kaons and antiprotons in central Au+Au collisions at the c.m. energy 200 GeV per NN pair are compared with experimental data of the BRAHMS Collaboration. Parameters of the initial state are reconstructed for different choices of the equation of state. The best fit of these data is obtained for a soft equation of state and Gaussian-like initial profiles of the energy density, intermediate between the Landau and Bjorken limits.Comment: 43 pages, 27 figure

Bremsstrahlung of a Quark Propagating through a Nucleus

The density of gluons produced in the central rapidity region of a heavy ion collision is poorly known. We investigate the influence of the effects of quantum coherence on the transverse momentum distribution of photons and gluons radiated by a quark propagating through nuclear matter. We describe the case that the radiation time substantially exceeds the nuclear radius (the relevant case for RHIC and LHC energies), which is different from what is known as Landau-Pomeranchuk-Migdal effect corresponding to an infinite medium. We find suppression of the radiation spectrum at small transverse photon/gluon momentum k_T, but enhancement for k_T>1GeV. Any nuclear effects vanish for k_T > 10GeV. Our results allow also to calculate the k_T dependent nuclear effects in prompt photon, light and heavy (Drell-Yan) dilepton and hadron production.Comment: Appendix A is extended compared to the version to be published in Phys.Rev.

Metal hydride hydrogen storage and compression systems for energy storage technologies

Along with a brief overview of literature data on energy storage technologies utilising hydrogen and metal hydrides, this article presents results of the related R&D activities carried out by the authors. The focus is put on proper selection of metal hydride materials on the basis of AB5- and AB2-type intermetallic compounds for hydrogen storage and compression applications, based on the analysis of PCT properties of the materials in systems with H2 gas. The article also presents features of integrated energy storage systems utilising metal hydride hydrogen storage and compression, as well as their metal hydride based components developed at IPCP and HySA Systems

Synthesis of hydrides by interaction of intermetallic compounds with ammonia

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Synthesis of hydrides by interaction of intermetallic compounds with ammonia

Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A2B, AB, AB2, AB5 and A2B17 (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransitition elements, Al and B). In presence of NH4Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P-T conditions, at temperatures 100–200 ºC and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal-nitrogen-hydrogen compounds like magnesium amide Mg(NH2)2. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m2 /g

Late Saalian and Eemian palaeoenvironmental history of the Bol'shoy Lyakhovsky Island (Laptev Sea region, Arctic Siberia)

Paleoenvironmental records from permafrost sequences complemented by IRSL and 230Th/U dates from Bol'shoy Lyakhovsky Island (73?20?N, 141?30?E) document the environmental history in the Laptev Sea region for at least the past 200 ka. Pollen spectra and insect fauna indicate that relatively wet grass-sedge tundra habitats predominated during an interstadial c. 200-170 ka ago. Summers were rather warm and wet, while stable isotopes reflect severe winter conditions. The pollen spectra reflect sparser grass-sedge vegetation cover during a late Saalian stadial, c. 170-130 ka ago, with environmental conditions much more sever compared with the previous interstadials. Open Poaceae and Artemisia plant associations dominated vegetation at the beginning of the Eemian Interglacial, c. 130 ka ago. Some shrubs (Alnus fruticosa, Salix, Betula nana) grew in more protected and wetter places as well. The climate was relatively warm during this time, resulting in the melting of the Saalian ice wedges. Later, during the interglacial optimum shrub tundra with Alnus fruticosa and Betula nana s.l. dominated vegetation. Climate was relatively wet and warm. Quantitative pollen-based climate reconstruction suggests that mean July temperatures were 4-5?C higher than the present during the optimum of the Eemian Interglacial, while late Eemian records indicate significant climate deterioration

Study of hydrogen storage and electrochemical properties of AB2-typeTi0.15Zr0.85La0.03Ni1.2Mn0.7V0.12Fe0.12alloy

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Pollen records and age determinations from 2 profiles at Lake Nikolay, Lena Delta

Radiocarbon-dated pollen, rhizopod, chironomid and total organic carbon (TOC) records from Nikolay Lake (73°20'N, 124°12'E) and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the Holocene in the Lena Delta area. Shrubby Alnus fruticosa and Betula exilis tundra existed during 10,300-4800 cal. yr BP and gradually disappeared after that time. Climate reconstructions based on the pollen and chironomid records suggest that the climate during ca. 10,300-9200 cal. yr BP was up to 2-3 °C warmer than the present day. Pollen-based reconstructions show that the climate was relatively warm during 9200-6000 cal. yr BP and rather unstable between ca. 5800-3700 cal. yr BP. Both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modern-day conditions after ca. 3600 cal. yr BP. The chironomid-based temperature reconstruction suggests a relatively warm period between ca. 2300 and 1400 cal. yr BP, which corresponds to the slightly warmer climate conditions reconstructed from the pollen. Modern chironomid and rhizopod assemblages were established after ca. 1400 cal. yr BP

Holocene environmental history recorded in the Lake Lyadhej-To sediments, Polar Urals, Russia

An 1180-cm long core recovered in Lake Lyadhej-To (68°15'N, 65°45'E, 150 m a.s.l.) at the NW rim of the Polar Urals Mountains reflects the Holocene environmental history from c. 11,000 cal. yr BP. Pollen assemblages from the diamicton (c. 11,000-10,700 cal. yr BP) are dominated by Pre-Quaternary spores and redeposited Pinaceae pollen, pointing to a high terrestrial input. Turbid and nutrient-poor lake conditions existed in the lake c. 10,700-10,550 cal. yr BP. The chironomid-inferred reconstructions suggest that mean July temperature increased rapidly from 10.0 to 11.8°C during this period. Sparse, treeless vegetation dominated on the disturbed and denudated soils in the catchment area. The period c. 10,550-8800 cal. yr BP is noticeable for the lowest lake-ice coverage and the highest bioproductivity during the lake history. Birch forest with some shrub alder grew around the lake reflecting the warmest environmental conditions during the Holocene. Mean July temperature was likely 11-13°C and annual precipitation - 400-500 mm. The period c. 8800-5500 cal. yr BP is characterised by gradual deterioration of environmental conditions in the lake and lake vicinity. The pollen- and chironomid-inferred temperatures reflect a warm period (c. 6500-6000 cal. BP) with mean July temperature at least 1-2°C higher than today. Birch forests disappeared from the lake vicinity after 6000 cal. yr BP. The vegetation in the Lyadhej-To region became similar to the modern. Shrub (Betula nana, Salix) and herb tundra dominated around the lake since c. 5500 cal. yr BP. All proxies are pointing to rather harsh environmental conditions. Diatom assemblages reflect relatively short growing seasons and longer persistence of ice on the lake c. 5500-2500 cal. yr BP. Pollen-based reconstruction suggest significant cooling between c. 5500 and 3500 cal. yr BP with mean July temperature 7-10°C and annual precipitation - 100-300 mm. The bioproductivity in the lake remained low after 2500 cal. yr BP, but biogeochemical proxies reflect a higher terrestrial influx. Changes in diatom content may indicate warmer water temperatures and reduced ice cover on the lake; however, chironomid-based reconstructions reflect a period with minimal temperatures during the lake histor