281 research outputs found

    Tracking the prelude of the electroreduction of carbon monoxide via its interaction with Cu(100): Studies by operando scanning tunneling microscopy and infrared spectroscopy

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    The first isolable intermediate in the electrochemical reduction of carbon dioxide is carbon monoxide. This species, or its hydrated form, formic acid, is also the primary end product from all but a handful of metallic electrodes; with the latter, hydrogen gas is generated, but it emanates from the reduction of water and not from CO₂. Only one electrode material, zerovalent copper, can spawn, in greater-than-trace quantities, a variety of species that are more highly reduced than CO. Hence, if the aim is to pursue a reaction trail of the reduction of CO₂ to products other than CO, it would be both logical and expedient to track the electrocatalytic reaction of CO itself. Heterogeneous electrocatalysis is a surface phenomenon; it transpires only when the reactant, CO in this case, chemisorbs on, or chemically interacts with, the Cu electrode surface. There is no electrocatalytic reaction if there is no CO adsorption. In ultrahigh vacuum, no CO resides on the Cu(100) surface at temperatures higher than 200 K. However, under electrochemical conditions, CO is chemisorbed on Cu at ambient temperatures at a given potential. We thus paired, in seriatim fashion, scanning tunneling microscopy (STM) and polarization-modulation IR reflection-absorption spectroscopy (PMIRS) to document the influence of applied potential on the coverage, the molecular orientation, and the adlattice structure of CO adsorbed on Cu(100) in alkaline solutions; the results are described in this paper

    Mechanisms of attenuation of pulmonary V'O_{2} slow component in humans after prolonged endurance training

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    In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V'O2 ) kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean\ub1SD: age 22.33\ub11.44 years, V'O2peak 3198\ub1458 mL \ub7 min-1 ) performed an endurance training composed mainly of moderate-intensity cycling, lasting 20 weeks. Training resulted in a decrease (by 3c5%, P = 0.027) in V'O2 during prior low-intensity exercise (20 W) and in shortening of \u3c4 p of the V'O2 on-kinetics (30.1\ub15.9 s vs. 25.4\ub11.5 s, P = 0.007) during subsequent heavy-intensity cycling. This was accompanied by a decrease of the slow component of V'O2 on-kinetics by 49% (P = 0.001) and a decrease in the end-exercise V'O2 by 3c5% (P = 0.005). An increase (P = 0.02) in the vascular endothelial growth factor receptor 2 mRNA level and a tendency (P = 0.06) to higher capillary-to-fiber ratio in the vastus lateralis muscle were found after training (n = 11). No significant effect of training on the V'O2peak was found (P = 0.12). However, the power output reached at the lactate threshold increased by 19% (P = 0.01). The power output obtained at the V'O2peak increased by 14% (P = 0.003) and the time of 1,500-m performance decreased by 5% (P = 0.001). Computer modeling of the skeletal muscle bioenergetic system suggests that the training-induced decrease in the slow component of V'O2 on-kinetics found in the present study is mainly caused by two factors: an intensification of the each-step activation (ESA) of oxidative phosphorylation (OXPHOS) complexes after training and decrease in the "additional" ATP usage rising gradually during heavy-intensity exercise

    Assessment of diving risks — based on selected haemostatic parameters

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    Безопасность ныряльщиков оценивали на основании проведения: - субъективного и объективного обследования; - оценки избранных гемостатических параметров фибринолиза; - радиологического обследования. При кратковременных погружения и погружениях в среде насыщении, а также при выполнении подводных работ, наблюдали изменения гемостатических показателей, что свидетельствует об образовании пузырьков газа в крови. Критерием оценки индивидуального риска развития декомпрессионной болезни может быть изменения гемостаза и фибринолиза кровяных пластинок, уменьшение количества тромбоцитов, увеличение процентного содержания микропластинок и экспрессии на частицах молекул ОЭ 62Р и ОЭ 61. Проведена оценка эффективности разработанных декомпрессионных режимов после моделированного погружения в насыщенной среде с использованием нитрокса, гелия и тройной смеси

    Assessment of diving risks — based on selected haemostatic parameters

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    Безопасность ныряльщиков оценивали на основании проведения: - субъективного и объективного обследования; - оценки избранных гемостатических параметров фибринолиза; - радиологического обследования. При кратковременных погружения и погружениях в среде насыщении, а также при выполнении подводных работ, наблюдали изменения гемостатических показателей, что свидетельствует об образовании пузырьков газа в крови. Критерием оценки индивидуального риска развития декомпрессионной болезни может быть изменения гемостаза и фибринолиза кровяных пластинок, уменьшение количества тромбоцитов, увеличение процентного содержания микропластинок и экспрессии на частицах молекул ОЭ 62Р и ОЭ 61. Проведена оценка эффективности разработанных декомпрессионных режимов после моделированного погружения в насыщенной среде с использованием нитрокса, гелия и тройной смеси

    Acute Modulation of Toll-Like Receptors by Insulin

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    OBJECTIVE—Low-dose insulin infusion has been shown to exert a prompt and powerful anti-inflammatory effect. Toll-like receptors (TLRs) are major determinants of the inflammatory response to viral and bacterial pathogens. We have now hypothesized that low-dose insulin infusion in obese type 2 diabetic patients suppresses TLR expression

    Prediction of Muscle Energy States at Low Metabolic Rates Requires Feedback Control of Mitochondrial Respiratory Chain Activity by Inorganic Phosphate

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    The regulation of the 100-fold dynamic range of mitochondrial ATP synthesis flux in skeletal muscle was investigated. Hypotheses of key control mechanisms were included in a biophysical model of oxidative phosphorylation and tested against metabolite dynamics recorded by 31P nuclear magnetic resonance spectroscopy (31P MRS). Simulations of the initial model featuring only ADP and Pi feedback control of flux failed in reproducing the experimentally sampled relation between myoplasmic free energy of ATP hydrolysis (ΔGp = ΔGpo′+RT ln ([ADP][Pi]/[ATP]) and the rate of mitochondrial ATP synthesis at low fluxes (<0.2 mM/s). Model analyses including Monte Carlo simulation approaches and metabolic control analysis (MCA) showed that this problem could not be amended by model re-parameterization, but instead required reformulation of ADP and Pi feedback control or introduction of additional control mechanisms (feed forward activation), specifically at respiratory Complex III. Both hypotheses were implemented and tested against time course data of phosphocreatine (PCr), Pi and ATP dynamics during post-exercise recovery and validation data obtained by 31P MRS of sedentary subjects and track athletes. The results rejected the hypothesis of regulation by feed forward activation. Instead, it was concluded that feedback control of respiratory chain complexes by inorganic phosphate is essential to explain the regulation of mitochondrial ATP synthesis flux in skeletal muscle throughout its full dynamic range

    Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

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    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

    Effect of heavy-intensity 'priming' exercise on oxygen uptake and muscle deoxygenation kinetics during moderate-intensity step-transitions initiated from an elevated work rate

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    We examined the effect of heavy-intensity ‘priming’ exercise on the rate of adjustment of pulmonary O2 uptake (τ 2p) initiated from elevated intensities. Fourteen men (separated into two groups: τ 2p≤25s [Fast] or τ 2p>25s [Slow]) completed step-transitions from 20W-to- 45%lactate threshold (LT; lower-step, LS) and 45%-to-90%LT (upper-step, US) performed (i) without; and (ii) with US preceded by heavy-intensity exercise (HUS). Breath-by-breath 2p and near-infrared spectroscopy-derived muscle deoxygenation ([HHb+Mb]) were measured. Compared to LS, τ 2p was greater (p0.05) from LS or Fast group US. In Slow, τ[HHb+Mb] increased (p<0.05) in US relative to HUS; this finding coupled with a reduced τ 2p indicates a priming-induced improvement in matching of muscle O2 delivery-to-O2 utilization during transitions from elevated intensities in those with Slow but not Fast 2p kinetics
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