Evaluation of the expanded measurement uncertainty in the determination of the net flux of nutrients and carbon atoms through the liver in ruminants

In in vivo metabolic studies, quantifying the flux of a nutrient and/or the carbon atoms through the liver implies the analytical determination of nutrient concentrations before and after crossing the liver and of blood or plasma flux. There is a measurement uncertainty (MU) associated with each input quantity, which may compromise accurate physiological interpretations of the results. The objective of this work was to calculate the expanded MU of net fluxes of nutrients and carbon atoms through the liver of ruminants and to identify the main components that affect MUs. To this end, all quantities (i.e., nutrient concentrations, para-aminohippuric acid concentrations, hematocrit, time of infusion, and others) that influenced the final results were identified and quantified. Their associated MUs were calculated with Type A or Type B approaches. An expanded MU model was developed by combining these two approaches. In general, the relative expanded MU of the net flux of nutrients calculated in plasma was lower than that in blood. For both plasma and blood fluxes, the main components that increased MUs were identified. The net hepatic flux of carbon atoms, for example, was estimated to be (63 ± 229) mmol min^?1. This high expanded MU was mainly a result of acetate concentration measurements in hepatic and portal veins. Priority strategies to reduce MUs, such as selecting an adequate matrix or using more accurate measurement methods, were identified.     

Determination of 3‐α‐hydroxytibolone in human plasma by LC‐MS/MS: application for a pharmacokinetic study after administration of a tibolone formulation

A new method was developed for the quantitation of 3‐α‐hydroxy tibolone, in human plasma, after oral administration of a tablet formulation containing tibolone (2.5 mg). 3‐α‐Hydroxy tibolone was extracted by a liquid–liquid procedure, using cyproterone acetate as internal standard and chlorobutane as extraction solvent. After extraction, samples were submitted to a derivatization step with p‐toluenesulfonyl isocyanate. A mobile phase consisting of acetonitrile and water (72:28 v/v) was used and chromatographic separation was achieved using Agilent XDB C₁₈ column (100 × 4.6 mm i.d.; 5 µm particle size), at 40°C. Mass spectrometric detection was performed using atmospheric pressure chemical ionization in negative mode for 3‐α‐hydroxy tibolone and in positive mode for cyproterone acetate. The fragmentation transitions were m/z 510.2 → m/z 170.1 and m/z 417.0 → m/z 357.1 for 3‐α‐hydroxy tibolone and cyproterone acetate, respectively. Calibration curves were constructed over the range 100–30,000 pg/mL and the method was shown to be specific, precise and accurate, with a mean recovery rate of 94.2% for 3‐α‐hydroxy tibolone. No matrix effect or carry‐over was detected in the samples. The validated method was applied in a pharmacokinetic study with a tibolone formulation in healthy female volunteers. Copyright © 2013 John Wiley & Sons, Ltd.     

A macrocyclic diurea derived from diphenylether

A new 16-membered cyclic diurea was synthesized and tested as potential receptor for fluoride. ¹H and ¹⁹F NMR spectroscopy revealed an unexpected deprotonation of both urea groups after initial 1:1 binding. A single crystal X-ray structure shows bifurcated hydrogen bonds to two DMSO molecules.     

Une caractérisation des familles exponentielles naturelles quadratiques simples par une propriété de martingale inverseA characterization of simple quadratic natural exponential families with a reverse martingale property

López-Blázquez and Salamanca-Miño [7] obtained a characterization of natural exponential families with quadratic variance functions via a reverse martingale property of certain orthogonal polynomials. We extend this result to the multidimensional case yielding a new characterization of natural exponential families with simple quadratic variance functions. To cite this article: D. Gutierrez-Rubio et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 405–409.     

Poly-5-aminoindole and graphene-like materials derived bifunctional Co–N-C electrocatalysts for oxygen reduction and hydrogen evolution

Journal of Solid State Electrochemistry - Pyrolyzed cobalt-nitrogen-carbon (Co–N-C) systems are considered as promising Pt-free electrocatalysts for oxygen reduction reaction (ORR) and...     

Visco-potential free-surface flows and long wave modelling

In a previous study [D. Dutykh, F. Dias, Viscous potential free-surface flows in a fluid layer of finite depth, C. R. Acad. Sci. Paris, Ser. I 345 (2007) 113–118] we presented a novel visco-potential free-surface flows formulation. The governing equations contain local and nonlocal dissipative terms. From physical point of view, local dissipation terms come from molecular viscosity but in practical computations, rather eddy viscosity should be used. On the other hand, nonlocal dissipative term represents a correction due to the presence of a bottom boundary layer. Using the standard procedure of Boussinesq equations derivation, we come to nonlocal long wave equations. In this article we analyze dispersion relation properties of proposed models. The effect of nonlocal term on solitary and linear progressive waves attenuation is investigated. Finally, we present some computations with viscous Boussinesq equations solved by a Fourier type spectral method.     

Nanostructures and Functionalities in Polymer Thin Films

Several examples of self-organization in thin polymer films are considered for the fabrication of nanopatterned surfaces and nanoscopic objects. Mixed polymer brushes of statistical distribution at the surface, composed of two immiscible polymers covalently bonded to the substrate phase, segregate in the sub-micrometer scale. Interplay between lateral and perpendicular (sandwich-like) segregation effects switching behavior of the thin films upon exposure to different environments. The switching between brush morphologies is used for the fabrication of adaptive/responsive surfaces. Fabrication of nano-domains based on microphase segregation in block-copolymer systems is used for structures with lateral dimensions as small as 5-50 nm. The ordered copolymer structures are applied as templates for the fabrication of membranes, nanofibers and nanoparticles.     

Manifold increase in high-rate properties of LiMn2O4 in a LiMn2O4-poly(pyrrole) composite and the depth of Li+ penetration into the material in fast pseudocapacitive processes

Journal of Solid State Electrochemistry - Lithium-ion batteries for automotive and military applications must tolerate high current loads, i.e., be able to be charged/discharged in less time....     

Triples of orthogonal Latin and Youden rectangles for small orders

We have performed a complete enumeration of nonisotopic triples of mutually orthogonal Latin rectangles for . Here we will present a census of such triples, classified by various properties, including the order of the autotopism group of the triple. As part of this, we have also achieved the first enumeration of pairwise orthogonal triples of Youden rectangles. We have also studied orthogonal triples of rectangles which are formed by extending mutually orthogonal triples with nontrivial autotopisms one row at a time, and requiring that the autotopism group is nontrivial in each step. This class includes a triple coming from the projective plane of order 8. Here we find a remarkably symmetrical pair of triples of rectangles, formed by juxtaposing two selected copies of complete sets of mutually orthogonal Latin squares of order 4.