5,509 research outputs found

    Stable carbon and radiocarbon isotope compositions of particle size fractions to determine origins of sedimentary organic matter in an estuary

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    Stable and radioactive carbon isotopic compositions of particle size fractions of a surface sediment from the Ems-Dollard estuary vary considerably with particle size. The organic material in the fine fractions (<20 µm) has considerably higher 14C values (14a~80%) than that in the coarse fractions (52%) and has higher δ13C values (average of -23‰ and -25.6‰, respectively). This shows that OM in the fine and the coarse fractions has different sources. The organic carbon in the fractions with particle sizes <20 µm is mainly imported from the North Sea. The contribution of material from the Ems river appears negligible. The carbon isotopic composition of the coarse fractions points to a terrestrial contribution. Discrete organic fragments are found of both terrestrial and marine/estuarine origin.

    European air quality maps 2005 including uncertainty analysis

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    The objective of this report is (a) the updating and refinement of European air quality maps based on annual statistics of the 2005 observational data reported by EEA Member countries in 2006, and (b) the further improvement of the interpolation methodologies. The paper presents the results achieved and an uncertainty analysis of the interpolated maps and builds upon earlier reports from Horalék et al. (2005; 2007)

    Diffusion in sparse networks: linear to semi-linear crossover

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    We consider random networks whose dynamics is described by a rate equation, with transition rates wnmw_{nm} that form a symmetric matrix. The long time evolution of the system is characterized by a diffusion coefficient DD. In one dimension it is well known that DD can display an abrupt percolation-like transition from diffusion (D>0D>0) to sub-diffusion (D=0). A question arises whether such a transition happens in higher dimensions. Numerically DD can be evaluated using a resistor network calculation, or optionally it can be deduced from the spectral properties of the system. Contrary to a recent expectation that is based on a renormalization-group analysis, we deduce that DD is finite; suggest an "effective-range-hopping" procedure to evaluate it; and contrast the results with the linear estimate. The same approach is useful for the analysis of networks that are described by quasi-one-dimensional sparse banded matrices.Comment: 13 pages, 4 figures, proofed as publishe

    Novel sol–gel preparation of (PO)–(CaO)–(NaO)–(TiO) bioresorbable glasses (X = 0.05, 0.1, and 0.15)

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    Quaternary phosphate-based glasses in the PO–CaO–NaO–TiO system with a fixed PO and CaO content of 40 and 25 mol% respectively have been successfully synthesised via sol–gel method and bulk, transparent samples were obtained. The structure, elemental proportion, and thermal properties of stabilised sol–gel glasses have been characterised using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), P nuclear magnetic resonance (P NMR), titanium K-edge X-ray absorption near-edge structure (XANES), fourier transform infrared (FTIR) spectroscopy, and differential thermal analysis (DTA). The XRD results confirmed the amorphous nature for all stabilized sol–gel derived glasses. The EDX result shows the relatively low loss of phosphorus during the sol–gel process and Ti K-edge XANES confirmed titanium in the glass structure is in mainly six-fold coordination environment. The P NMR and FTIR results revealed that the glass structure consist of mainly Q and Q phosphate units and the Ti cation was acting as a cross-linking between phosphate units. In addition DTA results confirmed a decrease in the glass transition and crystallisation temperature with increasing NaO content. Ion release studies also demonstrated a decrease in degradation rates with increasing TiO content therefore supporting the use of these glasses for biomedical applications that require a degree of control over glass degradation. These sol–gel glasses also offer the potential to incorporate proactive molecules for drug delivery application due to the low synthesis temperature employed

    Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

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    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 10(17) m(-2). We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching. (C) 2015 Author(s).Dutch Polymer Institute (DPI), BISTABLE [704]; Fundacao para Ciencia e Tecnologia (FCT) through the research Instituto de Telecommunicacoes (IT-Lx); project Memristor based Adaptive Neuronal Networks (MemBrAiNN) [PTDC/CTM-NAN/122868/2010]; European Community Seventh Framework Programme FP7', ONE-P [212311]; Dutch Ministry of Education, Culture and Science (Gravity Program) [024.001.035]info:eu-repo/semantics/publishedVersio

    Effect of Megasphaera elsdenii NCIMB 41125 drenching on health and performance of steers fed high and low roughage diets in the feedlot

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    Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when high concentrate diets are fed to feedlot cattle. Ruminal lactate acidosis can lead to lower animal performance and morbidity. Preliminary studies suggested that the strain, Megasphaera elsdenii (M.e.) NCIMB 41125, is a particularly potent LUB. The potential of M.e.NCIMB 41125 to improve the health and performance of feedlot cattle was investigated. Four hundred and forty eight Bonsmara steers (ca. 240 kg) were used in a 100-day feeding trial. Half the steers received at processing 200 mL M.e.NCIMB 41125 per os (LY) and the other half no LUB (LN). The diets in each of these treatments were divided into a low roughage (2%) (RL) and high roughage (8%) (RH) diet. The effects of LY vs. LN, RL vs. RH as main effects and their respective interactions (LYRL, LYRH, LNRL & LNRH) were compared in terms of morbidity, feedlot performance and carcass characteristics. The steers were weighed at two week intervals, feed was offered daily and the orts were removed weekly from each pen. The faecal consistency score and incidence of morbidity were recorded. At slaughter, carcass data were collected and the health status of the liver and rumen epithelium was assessed. Steers dosed with M.e.NCIMB 41125 had a 5.6% better average daily gain (ADG) during weeks 3 - 5 (2.09 kg/day vs. 1.98 kg/day for LY and LN, respectively). Feed conversion ratio (FCR, Weeks 1 - 13) was better for the steers fed the RL than the RH treatment (4.72 kg/kg vs. 4.99 kg/kg for RL and RH, respectively). Steers on the LNRH treatment during weeks 3 - 5 used more feed per kg gain than steers on the other treatments (5.39 kg/kg for LNRH vs. 4.74 kg/kg and 4.72 kg/kg for LYRL and LNRL, respectively). More steers (21) on the LNRL treatment were treated for morbidity than on the other treatments (8, 7 and 5 for LYRL, LYRH and LNRH, respectively). In general, animal performance was not improved by dosing with M.e.NCIMB 41125, but since ADG was improved in the immediate postadaptation phase (weeks 3 - 5) and morbidity levels were lower on the low roughage diet, dosing of steers on low roughage, lactate acidosis-prone, diets with M.e.NCIMB 41125 should prove useful.Keywords: Beef cattle, lactic acid utilising bacteria, acidosis, morbidit

    HID-1 controls formation of large dense core vesicles by influencing cargo sorting and trans-Golgi network acidification

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    Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN), where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and we show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties, due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN.</jats:p

    Advances in Sustainable Catalysis: A Computational Perspective

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    The enormous challenge of moving our societies to a more sustainable future offers several exciting opportunities for computational chemists. The first principles approach to “catalysis by design” will enable new and much greener chemical routes to produce vital fuels and fine chemicals. This prospective outlines a wide variety of case studies to underscore how the use of theoretical techniques, from QM/MM to unrestricted DFT and periodic boundary conditions, can be applied to biocatalysis and to both homogeneous and heterogenous catalysts of all sizes and morphologies to provide invaluable insights into the reaction mechanisms they catalyze

    The Bethe Ansatz for AdS5 x S5 Bound States

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    We reformulate the nested coordinate Bethe ansatz in terms of coproducts of Yangian symmetry generators. This allows us to derive the nested Bethe equations for the bound state string S-matrices. We find that they coincide with the Bethe equations obtained from a fusion procedure. The bound state number dependence in the Bethe equations appears through the parameters x^{\pm} and the dressing phase only.Comment: typos correcte
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