Inhibition by 5-(tetradecyloxy)-2-furoic acid of fatty acid and cholesterol synthesis in isolated rat hepatocytes

Fatty acid and cholesterol synthesis in isolated rat hepatocytes were strongly inhibited by 5-(tetradecyloxy)-2-furoic acid. With either³H₂O or [2-¹⁴C]acetate as the labeled precursor, the concentrations of inhibitor causing 50% decrease in fatty acid and cholesterol synthesis were, respectively, <0.005 mM and 0.020 mM. At 0.1 mM inhibitor, citrate concentration in cells from fed rats was increased by 75%; lactate and pyruvate concentrations were decreased by 30%; ethanol oxidation was decreased by 20%; with cells from starved rats, the mitochondrial [NAD⁺]/[NADH] was decreased. Other parameters were unaffected. Both its potency and its specificity indicate that 5-(tetradecyloxy)-2-furoic acid will be useful in studies on the regulation of lipid biosynthesis.     

Dynamic Model Adaptation for Multiscale Simulation of Hyperbolic Systems with Relaxation

In numerous industrial CFD applications, it is usual to use two (or more) different codes to solve a physical phenomenon: where the flow is a priori assumed to have a simple behavior, a code based on a coarse model is applied, while a code based on a fine model is used elsewhere. This leads to a complex coupling problem with fixed interfaces. The aim of the present work is to provide a numerical indicator to optimize to position of these coupling interfaces. In other words, thanks to this numerical indicator, one could verify if the use of the coarser model and of the resulting coupling does not introduce spurious effects. In order to validate this indicator, we use it in a dynamical multiscale method with moving coupling interfaces. The principle of this method is to use as much as possible a coarse model instead of the fine model in the computational domain, in order to obtain an accuracy which is comparable with the one provided by the fine model. We focus here on general hyperbolic systems with stiff relaxation source terms together with the corresponding hyperbolic equilibrium systems. Using a numerical Chapman–Enskog expansion and the distance to the equilibrium manifold, we construct the numerical indicator. Based on several works on the coupling of different hyperbolic models, an original numerical method of dynamic model adaptation is proposed. We prove that this multiscale method preserves invariant domains and that the entropy of the numerical solution decreases with respect to time. The reliability of the adaptation procedure is assessed on various 1D and 2D test cases coming from two-phase flow modeling.     

SplitLab: A shear-wave splitting environment in Matlab

We present a graphical user interface to facilitate the processing of teleseismic shear-wave splitting observations. In contrast to a fully automated technique, we present a manual, per-event approach that maintains user control during the sequence of processing. The SplitLab environment is intended to undertake the repetitive processing steps while enabling the user to focus on quality control and eventually the interpretation of the results. Pre-processing modules of SplitLab create a database of events and link the corresponding seismogram files. The seismogram viewer tool uses this database to perform the measurement interactively. Post-processing of the combined results of such a project includes a viewer and export option. Our emphasis lies in the application to teleseismic shear-wave splitting analysis, but our code can be extended easily for other purposes. SplitLab can be downloaded at http://www.gm.univ-montp2.fr/splitting/.     

A non-premixed combustion model based on flame structure analysis at supercritical pressures

This work presents a study of non-premixed flames at supercritical-pressure conditions. Emphasis is placed on flame stability in liquid rocket engines fueled with liquid oxygen and gaseous hydrogen. The flame structure sensitivity to strain, pressure, temperature and real-fluid effects was investigated in detailed opposed-jet flames calculations. It is shown that the flame is very robust to strain, that the flamelet assumption is valid for the conditions of interest, and that real-fluid phenomena can have a significant impact on flame topology. At high-pressure supercritical conditions, small pressure or temperature variations can induce strong changes of thermodynamic properties across the flame. A substantial finding was also that the presence of water from combustion significantly increases the critical pressure of the mixture, but this does not lead to a saturated state where two-phase flow may be observed. The present study then shows that a single-phase real-fluid approach is relevant for supercritical hydrogen–oxygen combustion. Resultant observations are used to develop a flamelet model framework that combines detailed real-fluid thermodynamics with a tabulated chemistry approach. The governing equation for energy contains a compressible source term that models the flame. Through this approach, the solver is capable of capturing compressibility and strain-rate effects. Good agreements have been obtained with respect to detailed computations. Heat release sensitivity to strain and pressure variations is also recovered. Consequently, this approach can be used to study combustion stability in actual burners. The approach preserves the density gradient in the high-shear region between the liquid-oxygen jet and product rich flame region. The latter is a key requirement to properly simulate dense-fluid jet destabilization and mixing in practical devices.     

Competition,virulence, host body mass and the diversification of macro-parasites

Adaptive speciation has been much debated in recent years, with a strong emphasis on how competition can lead to the diversification of ecological and sexual traits. Surprisingly, little attention has been paid to this evolutionary process to explain intrahost diversification of parasites. We expanded the theory of competitive speciation to look at the effect of key features of the parasite lifestyle, namely fragmentation, aggregation and virulence, on the conditions and rate of sympatric speciation under the standard ‘pleiotropic scenario’. The conditions for competitive speciation were found similar to those for non-parasite species, but not the rate of diversification. Adaptive evolution proceeds faster in highly fragmented parasite populations and for weakly aggregated and virulent parasites. Combining these theoretical results with standard empirical allometric relationships, we showed that parasite diversification can be faster in host species of intermediate body mass. The increase in parasite load with body mass, indeed, fuels evolution by increasing mutants production, but because of the deleterious effect of virulence, it simultaneously weakens selection for resource specialization. Those two antagonistic effects lead to optimal parasite burden and host body mass for diversification. Data on the diversity of fishes'' gills parasites were found consistent with the existence of such optimum.     

Sintering and conductivity of BaCe0.9Y0.1O2.95 synthesized by the sol-gel method

Ceramic powders of BaCe_0.9Y_0.1O_2.95 (BCY10) have been prepared by the sol-gel method. Barium and yttrium acetate and cerium nitrate were used as ceramic precursors in a water solution. The reaction process studied by DTA-TG and XRD showed that calcination of the precursor powder at T ≥ 1000 °C produces a single perovskite phase. The densification behaviour of green compacts studied by constant heating rate dilatometry revealed that the shrinkage rate was maximal at 1430 °C. Sintered densities higher than 95% of the theoretical one were thus obtained below 1500 °C. The bulk and additional blocking effects were characterized by impedance spectroscopy in wet atmosphere between 150 and 600 °C. A proton conduction behaviour was clearly identified. The blocking effect can be related to a space-charge depletion layer of protons in the vicinity of grain boundaries.     

Nanostructural Evolution of Titania-Based Materials Using Modified Titanium Precursors

Titanium ethoxide [Ti(OEt)₄] was modified with aminobenzoic acid (AB) or aminosalicylic acid (AS) in order to control the hydrolysis and condensation rates, and to allow the preparation of organic–inorganic hybrid materials. A suite of complementary techniques, including Fourier transform infrared spectroscopy, NMR, SEM, thermogravimetric analysis, and X-ray diffraction, were used to elucidate the effects of incorporating an organic functional group into the precursor chemistry and its subsequent affect on the structure and morphology of the resultant hybrid material. The annealing behavior of the resulting hybrid titanium base materials was also investigated. Our studies show that both amino acid organic ligands, AB and AS, chemically bounded to the titanium complex, effect the precursor reactivity, specifically the hydrolysis and polycondensation reactions, which control the evolution and formation of the nanohybrid-based titania material. Following sol–gel processing, the nanohybrid materials are amorphous, due to the incorporation of the organic component. The phase transition (amorphous–anatase–rutile) observed during annealing from 25° to 800°C show subtle differences in the crystallization behavior, which are associated with the nature of the organic ligand.     

Grafting Single Molecule Magnets on Gold Nanoparticles

The chemical synthesis and characterization of the first hybrid material composed by gold nanoparticles and single molecule magnets (SMMs) are described. Gold nanoparticles are functionalized via ligand exchange using a tetrairon(III) SMM containing two 1,2‐dithiolane end groups. The grafting is evidenced by the shift of the plasmon resonance peak recorded with a UV–vis spectrometer, by the suppression of nuclear magnetic resonance signals, by X‐ray photoemission spectroscopy peaks, and by transmission electron microscopy images. The latter evidence the formation of aggregates of nanoparticles as a consequence of the cross‐linking ability of Fe₄ through the two 1,2‐dithiolane rings located on opposite sides of the metal core. The presence of intact Fe₄ molecules is directly proven by synchrotron‐based X‐ray absorption spectroscopy and X‐ray magnetic circular dichroism spectroscopy, while a detailed magnetic characterization, obtained using electron paramagnetic resonance and alternating‐current susceptibility, confirms the persistence of SMM behavior in this new hybrid nanostructure.     

GdBaCo2O5+x layered perovskite as an intermediate temperature solid oxide fuel cell cathode

GdBaCo₂O_5+x (GBCO) was evaluated as a cathode for intermediate-temperature solid oxide fuel cells. A porous layer of GBCO was deposited on an anode-supported fuel cell consisting of a 15 μm thick electrolyte of yttria-stabilized zirconia (YSZ) prepared by dense screen-printing and a Ni–YSZ cermet as an anode (Ni–YSZ/YSZ/GBCO). Values of power density of 150 mW cm⁻² at 700 °C and ca. 250 mW cm⁻² at 800 °C are reported for this standard configuration using 5% of H₂ in nitrogen as fuel. An intermediate porous layer of YSZ was introduced between the electrolyte and the cathode improving the performance of the cell. Values for power density of 300 mW cm⁻² at 700 °C and ca. 500 mW cm⁻² at 800 °C in this configuration were achieved.