A new simple device to estimate thermophysical properties of insulating materials

International audienceThe method described here is to measure thermal conductivity of super insulating materials. The principle is based on a simple transient experiment and a single temperature measurement, The main idea is to control the heat flux diffusion in the sample by the adjunction of a semi infinite highly conductive medium

Short-term relationships between winter temperatures and cardiac disease mortality in Cape Town

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Niosomes and polymeric chitosan based vesicles bearing transferrin and glucose ligands for drug targeting

PURPOSE: To prepare polymeric vesicles and niosomes bearing glucose or transferrin ligands for drug targeting. METHODS: A glucose-palmitoyl glycol chitosan (PGC) conjugate was synthesised and glucose-PGC polymeric vesicles prepared by sonication of glucose-PGC/cholesterol. N-palmitoylglucosamine (NPG) was synthesised and NPG niosomes also prepared by sonication of NPG/ sorbitan monostearate/ cholesterol/ cholesteryl poly-24-oxyethylene ether. These 2 glucose vesicles were incubated with colloidal concanavalin A gold (Con-A gold), washed and visualised by transmission electron microscopy (TEM). Transferrin was also conjugated to the surface of PGC vesicles and the uptake of these vesicles investigated in the A431 cell line (over expressing the transferrin receptor) by fluorescent activated cell sorter analysis. RESULTS: TEM imaging confirmed the presence of glucose units on the surface of PGC polymeric vesicles and NPG niosomes. Transferrin was coupled to PGC vesicles at a level of 0.60+/-0.18 g of transferrin per g polymer. The proportion of FITC-dextran positive A431 cells was 42% (FITC-dextran solution), 74% (plain vesicles) and 90% (transferrin vesicles). CONCLUSIONS: Glucose and transferrin bearing chitosan based vesicles and glucose niosomes have been prepared. Glucose bearing vesicles bind Con-A to their surface. Chitosan based vesicles are taken up by A431 cells and transferrin enhances this uptake

Extension of the hot wire method to the characterization of stratified soils with multiple temperature analysis

International audienceThe aim of this article is to develop a practical device able to estimate a thermal conductivity profile in stratified media such as burned soils in Chile. The classical hot wire method consists of measuring the temperature response of a heat step imposed on a thin cylindrical probe by Joule effect. The main characteristic of the extension of the method consists of analyzing the two-dimensional temperature response of multiple thermo-couples equally spaced along the heating cylinder. A semianalytical method (quadrupole method) is then implemented in order to obtain a transfer matrix between the heat flux excitation and the temperature response vectors. Such method is suitable to obtain asymptotic expansions in order to investigate the sensitivity analysis and the estimation strategy. A complete two-dimensional model is used in order to define a time window in which the one-dimensional radial heat transfer assumption is valid. Some experiments and estimation results are presented in a case where the characteristic diffusion times in the radial direction are small compared to the inter-layers diffusion time

Possible explanation of the discrepancy of the light-cone QCD sum rule calculation of g(D*Dpi) coupling with experiment

The introduction of an explicit negative radial excitation contribution in the hadronic side of the light cone QCD sum rule (LCSR) of Belyaev, Braun, Khodjamirian and Ruckl, can explain the large experimental value of g(D*Dpi), recently measured by CLEO. At the same time, it considerably improves the stability of the sum rule when varying the Borel parameter.Comment: 9 pages, 1 PostScript figure

Magmatic evolution of the Nevado del Ruiz volcano, Central Cordillera, Colombia : mineral chemistry and geochemistry

A partir de nouvelles données pétrographiques, minéralogiques et géochimiques, les auteurs réalisent une caractérisation géochimique des laves du Nevado del Ruiz (éruptions quaternaires, historiques et récentes) et des formations volcaniques du Pliocène des pentes de la Cordillère central

Structure, nonlinear properties, and photosensitivity of (GeSe2)​100-​x(Sb2Se3)​x glasses

International audienceChalcogenide glasses from (GeSe2)​100-​x(Sb2Se3)​x system were synthesized, with x varying from 5 to 70, in order to evaluate the influence of antimony selenide addn. on nonlinear optical properties and photosensitivity. Nonlinear refractive index and two photon absorption coeffs. were measured both at 1064 nm in picosecond regime using the Z-​scan technique and at 1.55 μm in femtosecond regime using an original method based on direct anal. of beam profile change while propagating in the chalcogenide glasses. The study of their photosensitivity at 1.55 μm revealed highly glass compn. dependent behavior and quasi-​photostable compns. have been identified in femtosecond regime. To better understand these characteristics, the evolution of the glass transition temp., d. and structure with the chem. compn. were detd

Computational Design of Thermally Activated Delayed Fluorescence Materials: The Challenge Ahead

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N-doped Cycloparaphenylenes: Tuning Electronic Properties for Applications in Thermally Activated Delayed Fluorescence

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