Implications of Exceptional Material Kinetics on Thermochemical Fuel Production Rates

Production of chemical fuels by solar-driven thermochemical cycling has recently generated significant interest for its potential as a highly efficient method of storing solar energy. Of particular interest is the thermochemical process using non-stoichiometric oxides, such as ceria. In this process a reactive oxide is cyclically exposed to an inert gas, typically at 1500 °C to induce the partial reduction of the oxide, and then exposed to an oxidizing gas of either H_2O or CO_2 at a temperature between 800–1500 °C to oxidize the oxide and release H_2 or CO. Conventional wisdom has held that material kinetics limit the fuel production rates. Herein we demonstrate that, instead, at 1500 °C the rates of both reduction and oxidation of ceria, and hence also the global fuel production rate, are limited only by thermodynamic considerations for any reasonable set of operating conditions. Thus, in terms of materials design, significant room exists for sacrificing material kinetics in favor of thermodynamic characteristics

Measurement of the B0s→μ+μ− Branching Fraction and Effective Lifetime and Search for B0→μ+μ− Decays

See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-001.html - Submitted to Phys. Rev. Lett.International audienceA search for the rare decays B0s→μ+μ− and B0→μ+μ− is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb−1. An excess of B0s→μ+μ− decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B0s→μ+μ−)=(3.0±0.6+0.3−0.2)×10−9, where the first uncertainty is statistical and the second systematic. The first measurement of the B0s→μ+μ− effective lifetime, τ(B0s→μ+μ−)=2.04±0.44±0.05 ps, is reported. No significant excess of B0→μ+μ− decays is found and a 95 % confidence level upper limit, B(B0→μ+μ−)<3.4×10−10, is determined. All results are in agreement with the Standard Model expectations

The yeast gene YJR025c encodes a 3-hydroxyanthranilic acid dioxygenase and is involved in nicotinic acid biosynthesis

AbstractWe have deleted the yeast gene YJR025c and shown that this leads to an auxotrophy for nicotinic acid. The deduced protein sequence of the gene product is homologous to the human 3-hydroxyanthranilic acid dioxygenase (EC 1.13.11.6) which is part of the kynurenine pathway for the degradation of tryptophan and the biosynthesis of nicotinic acid. In cell-free extracts the 3-hydroxyanthranilic acid dioxygenase activity is proportional to the copy number of the YJR025c gene. As YJR025c encodes the yeast 3-hydroxyanthranilic acid dioxygenase, we have named this gene BNA1 for biosynthesis of nicotinic acid

Maximizing fuel production rates in isothermal solar thermochemical fuel production

Production of chemical fuels by isothermal pressure-swing cycles has recently generated significant interest. In this process a reactive oxide is cyclically exposed to an inert gas, which induces partial reduction of the oxide, and to an oxidizing gas of either H_2O or CO_2, which reoxidizes the oxide, releasing H_2 or CO. At sufficiently high temperatures and sufficiently low gas flow rates, both the reduction and oxidation steps become limited only by the flow of gas across the material and not by material kinetic factors. In this contribution, we develop a numerical model describing fuel production rates in this gas-phase limited regime. The implications of this behavior are explored under all possible isothermal pressure-swing cycling conditions, and the outcome is optimized in terms of fuel production rate as well as fuel conversion and utilization of input gas of all types. Fuel production rate is maximized at infinitesimally small cycle times and attains a value that is independent of material thermodynamics. Gas utilization is maximized at infinitesimally small gas inputs, but the values can be made independent of cycle time, depending on manipulation of flow conditions. Gas-phase conditions (temperature, oxidant and reductant gas partial pressures, and CO_2 vs H_2O as oxidant) have a strong impact on fuel production metrics. Under realistic, finite cycle times, material thermodynamics play a measurable role in establishing fuel production rates

Subunit organization and Rab interactions of Vps-C protein complexes that control endolysosomal membrane traffic

The Vps-C complexes, CORVET and HOPS, are key regulators of membrane traffic through late endosomes and lysosomes. In this study Vps-C intersubunit contacts, domain architecture, and interactions with Rab G proteins are systematically dissected using genetic and biochemical approaches

White matter involvement in sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease is considered primarily a disease of grey matter, although the extent of white matter involvement has not been well described. We used diffusion tensor imaging to study the white matter in sporadic Creutzfeldt-Jakob disease compared to healthy control subjects and to correlated magnetic resonance imaging findings with histopathology. Twenty-six patients with sporadic Creutzfeldt-Jakob disease and nine age- and gender-matched healthy control subjects underwent volumetric T(1)-weighted and diffusion tensor imaging. Six patients had post-mortem brain analysis available for assessment of neuropathological findings associated with prion disease. Parcellation of the subcortical white matter was performed on 3D T(1)-weighted volumes using Freesurfer. Diffusion tensor imaging maps were calculated and transformed to the 3D-T(1) space; the average value for each diffusion metric was calculated in the total white matter and in regional volumes of interest. Tract-based spatial statistics analysis was also performed to investigate the deeper white matter tracts. There was a significant reduction of mean (P = 0.002), axial (P = 0.0003) and radial (P = 0.0134) diffusivities in the total white matter in sporadic Creutzfeldt-Jakob disease. Mean diffusivity was significantly lower in most white matter volumes of interest (P < 0.05, corrected for multiple comparisons), with a generally symmetric pattern of involvement in sporadic Creutzfeldt-Jakob disease. Mean diffusivity reduction reflected concomitant decrease of both axial and radial diffusivity, without appreciable changes in white matter anisotropy. Tract-based spatial statistics analysis showed significant reductions of mean diffusivity within the white matter of patients with sporadic Creutzfeldt-Jakob disease, mainly in the left hemisphere, with a strong trend (P = 0.06) towards reduced mean diffusivity in most of the white matter bilaterally. In contrast, by visual assessment there was no white matter abnormality either on T(2)-weighted or diffusion-weighted images. Widespread reduction in white matter mean diffusivity, however, was apparent visibly on the quantitative attenuation coefficient maps compared to healthy control subjects. Neuropathological analysis showed diffuse astrocytic gliosis and activated microglia in the white matter, rare prion deposition and subtle subcortical microvacuolization, and patchy foci of demyelination with no evident white matter axonal degeneration. Decreased mean diffusivity on attenuation coefficient maps might be associated with astrocytic gliosis. We show for the first time significant global reduced mean diffusivity within the white matter in sporadic Creutzfeldt-Jakob disease, suggesting possible primary involvement of the white matter, rather than changes secondary to neuronal degeneration/loss