28 research outputs found

    The use of small angle neutron scattering with contrast matching and variable adsorbate partial pressures in the study of porosity in activated carbons

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    The porosity of a typical activated carbon is investigated with small angle neutron scattering (SANS), using the contrast matching technique, by changing the hydrogen/deuterium content of the absorbed liquid (toluene) to extract the carbon density at different scattering vector (Q) values and by measuring the p/p0 dependence of the SANS, using fully deuterated toluene. The contrast matching data shows that the apparent density is Q-dependent, either because of pores opening near the carbon surface during the activation processor or changes in D-toluene density in nanoscale pores. For each p/p0 value, evaluation of the Porod Invariant yields the fraction of empty pores. Hence, comparison with the adsorption isotherm shows that the fully dry powder undergoes densification when liquid is added. An algebraic function is developed to fit the SANS signal at each p/p0 value hence yielding the effective Kelvin radii of the liquid surfaces as a function of p/p0. These values, when compared with the Kelvin Equation, show that the resultant surface tension value is accurate for the larger pores but tends to increase for small (nanoscale) pores. The resultant pore size distribution is less model-dependent than for the traditional methods of analyzing the adsorption isotherms

    Measurement of event-shape observables in Z→ℓ+ℓ− events in pp collisions at √ s=7 TeV with the ATLAS detector at the LHC

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    Event-shape observables measured using charged particles in inclusive ZZ-boson events are presented, using the electron and muon decay modes of the ZZ bosons. The measurements are based on an integrated luminosity of 1.1fb11.1 {\rm fb}^{-1} of proton--proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy s=7\sqrt{s}=7 TeV. Charged-particle distributions, excluding the lepton--antilepton pair from the ZZ-boson decay, are measured in different ranges of transverse momentum of the ZZ boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and F\mathcal{F}-parameter, which are in particular sensitive to properties of the underlying event at small values of the ZZ-boson transverse momentum. The Sherpa event generator shows larger deviations from the measured observables than Pythia8 and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high ZZ-boson transverse momenta than at low ZZ-boson transverse momenta and for the observables that are less sensitive to the number of charged particles in the event.Comment: 36 pages plus author list + cover page (54 pages total), 14 figures, 4 tables, submitted to EPJC, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-0

    Hipervitaminose D em animais

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    Carla Task Force on Sarcopenia: Propositions for clinical trials

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    In the presence of an aging population, public health priorities need to evolve. As the populations gets older, the already existing pathologies have become commonplace with specific geriatric clinical syndromes like frailty, mobility disability, or cognitive impairment, among others. Sarcopenia is a good example for which geriatricians, neurologists, physiologists, nutritionists and epidemiologists need to find a consensual definition and diagnostic tool as well as guidelines for the management of clinical trials and possible treatments. The Carla Sarcopenia Task Force, which met in the south of France (Toulouse) for an expert consensus meeting called “Les Entretiens du Carla“, have addressed a series of existing issues to place Sarcopenia into a nosological context: a definition which should be a composite of a change in muscle mass and a change in strength/function depending on either a progressive and chronic wasting process or an acute onset of loss of muscle mass; a recommendation for DXA and the Short Physical Performance Battery as a clinical pragmatic approach of Sarcopenia; a differentiated approach for clinical studies according to prevention or treatment objectives and depending on the sub-groups and target populations; and finally, a summary of therapeutic strategies currently recommended. The aim of “Les Entretiens du Carla”, based on an expert meeting panel, was to address a series of unsolved issues in the field of Sarcopenia by combining the expert opinion with a revision of the existing literature on the topic. Through this report, the reader will appreciate the determination to find conclusions on the various issues and further studies to be developed to determine the best multidisciplinary approach needed

    New insights on low vitamin D plasma concentration as a potential cardiovascular risk factor

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    The role of Vitamin D hormone in human health and disease is still debated. Recently, growing attention has been paid to its putative role in cardiovascular system homeostasis with several studies that suggested a correlation between low vitamin D levels and increased cardiovascular risk. Several mechanisms are involved in the development of cardiovascular diseases: systemic inflammation, endothelial dysfunction, arterial hypertension and insulin resistance. In the present paper, we have revised the current literature supporting a role for vitamin D in the development of these pathogenetic processes. Finally, we have evaluated the current evidence linking vitamin D to atherosclerosis and its natural consequence, cardiovascular diseases
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