254 research outputs found

    Sulfate corrosion of concrete caused by thionic bacteria

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    The article deals with conditions for the occurrence of sulfate corrosion of concrete. It is noted that thionic bacteria, changing pH of the medium at the expense of formed sulfuric acid, are active corrosion agents. The activity of thionic bacteria leads to concrete corrosion of the second and the third type. It is shown that the intensity of biocorrosion destruction is determined by the rate of chemical reactions and microorganisms and internal diffusion of metabolic products in the concrete structure is determined by the rate of chemical reactions and internal diffusion microorganisms and products of their metabolism in the concrete structure. The article presents modern methods of protection from sulfate corrosion

    Sulfate corrosion of concrete caused by thionic bacteria

    Get PDF
    The article deals with conditions for the occurrence of sulfate corrosion of concrete. It is noted that thionic bacteria, changing pH of the medium at the expense of formed sulfuric acid, are active corrosion agents. The activity of thionic bacteria leads to concrete corrosion of the second and the third type. It is shown that the intensity of biocorrosion destruction is determined by the rate of chemical reactions and microorganisms and internal diffusion of metabolic products in the concrete structure is determined by the rate of chemical reactions and internal diffusion microorganisms and products of their metabolism in the concrete structure. The article presents modern methods of protection from sulfate corrosion

    The observation of long-range three-body Coloumb effects in the decay of 16Ne

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    The interaction of an E/AE/A=57.6-MeV 17^{17}Ne beam with a Be target was used to populate levels in 16^{16}Ne following neutron knockout reactions. The decay of 16^{16}Ne states into the three-body 14^{14}O+pp+pp continuum was observed in the High Resolution Array (HiRA). For the first time for a 2p emitter, correlations between the momenta of the three decay products were measured with sufficient resolution and statistics to allow for an unambiguous demonstration of their dependence on the long-range nature of the Coulomb interaction. Contrary to previous experiments, the intrinsic decay width of the 16^{16}Ne ground state was found to be narrow (Γ<60\Gamma<60~keV), consistent with theoretical estimates.Comment: 6 pages, 5 figure

    Climate-Induced Boreal Forest Change: Predictions versus Current Observations

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    For about three decades, there have been many predictions of the potential ecological response in boreal regions to the currently warmer conditions. In essence, a widespread, naturally occurring experiment has been conducted over time. In this paper, we describe previously modeled predictions of ecological change in boreal Alaska, Canada and Russia, and then we investigate potential evidence of current climate-induced change. For instance, ecological models have suggested that warming will induce the northern and upslope migration of the treeline and an alteration in the current mosaic structure of boreal forests. We present evidence of the migration of keystone ecosystems in the upland and lowland treeline of mountainous regions across southern Siberia. Ecological models have also predicted a moisture-stress-related dieback in white spruce trees in Alaska, and current investigations show that as temperatures increase, white spruce tree growth is declining. Additionally, it was suggested that increases in infestation and wildfire disturbance would be catalysts that precipitate the alteration of the current mosaic forest composition. In Siberia, five of the last seven years have resulted in extreme fire seasons, and extreme fire years have also been more frequent in both Alaska and Canada. In addition, Alaska has experienced extreme and geographically expansive multi-year outbreaks of the spruce beetle, which had been previously limited by the cold, moist environment. We suggest that there is substantial evidence throughout the circumboreal region to conclude that the biosphere within the boreal terrestrial environment has already responded to the transient effects of climate change. Additionally, temperature increases and warming-induced change are progressing faster than had been predicted in some regions, suggesting a potential non-linear rapid response to changes in climate, as opposed to the predicted slow linear response to climate change

    Core excitation in Coulomb breakup reactions

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    Within the pure Coulomb breakup mechanism, we investigate the one-neutron removal reaction of the type A(a,bγ\gamma)X with 11^{11}Be and 19^{19}C projectiles on a heavy target nucleus 208^{208}Pb at the beam energy of 60 MeV/nucleon. Our intention is to examine the prospective of using these reactions to study the structure of neutron rich nuclei. Integrated partial cross sections and momentum distributions for the ground as well as excited bound states of core nuclei are calculated within the finite range distorted wave Born approximation as well as within the adiabatic model of the Coulomb breakup. Our results are compared with those obtained in the studies of the reactions on a light target where the breakup proceeds via the pure nuclear mechanism. We find that the transitions to excited states of the core are quite weak in the Coulomb dominated process as compared to the pure nuclear breakup.Comment: Revtex format, five postscript figures included, to appear in Phys. Rev.

    Status of the ACCULINNA-2 project at FLNR

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    The project of a new and more powerful in-flight fragment separator ACCULINNA-2 at U-400M cyclotron in FLNR, JINR planned to build in addition to the existing separator ACCULINNA is presented. The new separator will provide high intensity RIBs in the lowest energy range (5÷50 MeV/nucleon) which is attainable for in-flight separators. The possibilities for the astrophysics studies at the proposed device are presented. ACCULINNA-2 separator is planned to be constructed in the years 2010-2015. The current status of the project is reported

    "Tomography" of the cluster structure of light nuclei via relativistic dissociation

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    These lecture notes present the capabilities of relativistic nuclear physics for the development of the physics of nuclear clusters. Nuclear track emulsion continues to be an effective technique for pilot studies that allows one, in particular, to study the cluster dissociation of a wide variety of light relativistic nuclei within a common approach. Despite the fact that the capabilities of the relativistic fragmentation for the study of nuclear clustering were recognized quite a long time ago, electronic experiments have not been able to come closer to an integrated analysis of ensembles of relativistic fragments. The continued pause in the investigation of the "fine" structure of relativistic fragmentation has led to resumption of regular exposures of nuclear emulsions in beams of light nuclei produced for the first time at the Nuclotron of the Joint Institute for Nuclear Research (JINR, Dubna). To date, an analysis of the peripheral interactions of relativistic isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones, with nuclei of the emulsion composition, has been performed, which allows the clustering pattern to be presented for a whole family of light nuclei.Comment: ISBN 978-3-319-01076-2. 55 pages, 28 figure

    Positive biodiversity-productivity relationship predominant in global forests

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    The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone - US$166 billion to 490 billion per year according to our estimation - is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities.Peer Reviewe

    Coulomb breakup of 17 Ne from the view point of nuclear astrophysics

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    6 pags., 5 figs. -- XII International Symposium on Nuclei in the Cosmos, August 5-12, 2012, Cairns, AustraliaBy the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p, γ) 17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section σCoul has been determined, which then will be converted into a photo-absorption cross section σphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress.This project was supported by the German Federal Ministry for Education and Research (BMBF), EU(EURONS), EMMI-GSI, and HIC for FAI

    Coulomb breakup of 17Ne from the viewpoint of nuclear astrophysics

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    By the Coulomb breakup of 17Ne, the time-reversed reaction 15O(2p,γ)17Ne has been studied. This reaction might play an important role in the rp process, as a break-out reaction of the hot CNO cycle. The secondary 17Ne ion beam with an energy of 500 MeV/nucleon has been dissociated in a Pb target. The reaction products have been detected with the LAND-R3B experimental setup at GSI. The preliminary differential and integral Coulomb dissociation cross section sCoul has been determined, which then will be converted into a photo-absorption cross section sphoto, and a two-proton radiative capture cross section σcap. Additionally, information about the structure of the 17Ne, a potential two-proton halo nucleus, will be received. The analysis is in progress. \ua9 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence
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