Phase‐Change Materials: Vibrational Softening upon Crystallization and Its Impact on Thermal Properties

Crystallization of an amorphous solid is usually accompanied by a significant change of transport properties, such as an increase in thermal and electrical conductivity. This fact underlines the importance of crystalline order for the transport of charge and heat. Phase‐change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. The small change in this conductivity upon crystallization points to unique lattice properties. The present investigation reveals that the thermal properties of the amorphous and crystalline state of phase‐change materials show remarkable differences such as higher thermal displacements and a more pronounced anharmonic behavior in the crystalline phase. These findings are related to the change of bonding upon crystallization, which leads to an increase of the sound velocity and a softening of the optical phonon modes at the same time.     

Long-term ventilation at home in adults with neurological diseases

Protein kinase C (PKC) is now known to play an important physiological role in essentially all cell types. This review will focus on what is known about the kinase in contractile differentiated smooth muscle. Current knowledge on the molecular structure of PKC isoforms will be discussed as they relate to mechanisms of translocation and targeting of the kinase within smooth muscle cells. Studies performed on PKC-dependent signalling pathways in differentiated smooth muscle cells will be discussed with emphasis on studies form our laboratory, especially discussing thin filament linked pathways. Thick filament linked PKC-dependent pathways will be described in more detail elsewhere in this monograph.     

Contre-validation de l'organisation hiérarchique de la Mesure de l'Actualisation du Potentiel (MAP).

This study presents a cross-validation of the latent structure of the Measure of Self-actualization of Potential developed recently by G. Leclerc et al (1998) with Canadian people. The sample consisted of 643 French subjects (aged 18-85 yrs). The confirmatory factor analyses supported the hierarchical structure proposed by Leclerc et al. However some modifications were needed to reach an adequate model fit. The sense of these modifications is discussed. Moreover, this scale demonstrated a good internal consistency, and an excellent test-retest reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of capping thioalkyl acid on the growth and photoluminescence efficiency of CdTe and CdSe quantum dots

The influence of thioalkyl acid ligand was evaluated during aqueous synthesis at 100?°C and under hydrothermal conditions (150?°C) of CdTe and CdSe quantum dots (QDs). Experiments performed with 3-mercaptopropionic acid (MPA), 6-mercaptohexanoic acid (MHA) and 11-mercaptoundecanoic acid (MUA) demonstrated that the use of MHA and MUA allowed for the preparation of very small nanoparticles (0.6-2.5?nm) in carrying out the reaction under atmospheric pressure or in an autoclave and that the photophysical properties of QDs were dependent on the ligand and on the synthesis conditions. The influence of various experimental conditions, including the Te-to-Cd ratio, temperature, and precursor concentration, on the growth rate of CdTe or CdSe QDs has been systematically investigated. The fluorescence intensities of CdTe QDs capped with MPA, MHA, or MUA versus pH were also found to be related to the surface coverage of the nanoparticles.     

Physico-chemical and NMR relaxometric characterization of gadolinium hydroxide and dysprosium oxide nanoparticles

Gadolinium hydroxide and dysprosium oxide nanoparticles, which constitute a new interesting class of magnetic nanoparticles, are characterized by different methods, using x-ray diffraction, magnetometry and NMR relaxometry at multiple fields. The rod-like particles are first shown to have a simple paramagnetic behavior, like the bulk compound, without any influence of the nanometric size of the particles. Because of their paramagnetic moment, these particles considerably shorten water relaxation times, especially the transverse relaxation time at high fields. The relaxation induced by gadolinium hydroxide particles is due to a proton exchange between the particle surface and bulk water, while the transverse relaxation caused by dysprosium oxide particles is governed by the diffusion of water protons around the magnetized particles. 1/T(2) increases linearly with the magnetic field for gadolinium hydroxide particles while a quadratic increase is observed for dysprosium oxide nanoparticles. The relaxation results are compared with those from previous studies and interpreted using different theories for the relaxation induced by magnetic particles.     

DNA damage in Gammarus fossarum sperm as a biomarker of genotoxic pressure: intrinsic variability and reference level

In the perspective of a biomonitoring application for assessing genotoxicity of freshwater ecosystems, the Comet assay has recently been developed on spermatozoa in the amphipod Gammarus fossarum, in order to propose a sensitive and reliable genotoxicity biomarker in an ecologically relevant freshwater species. The appropriate use of a genotoxicity biomarker requires good knowledge of its basal level and its natural variability related to intrinsic biotic and environmental abiotic factors. We propose a procedure for which the lowest biomarker variability related to methodological and intrinsic biotic factors is obtained and a reference value of biomarker basal response taking into account its spatio-temporal changes has been defined. A strong impact of spermatogenesis status and exposure time on the response to genotoxicant pressure was observed. These reports led us to select a standard organism, i.e., the mature male gammarid in precopula. No effect of temperature and conductivity on baseline DNA damage was observed in the laboratory for the tested range (6-24 °C and 300/600 μS cm⁻¹). Similarly, no spatio-temporal change relative to season or the physico-chemical characteristics of the water was recorded during the field survey. On the basis of these results, a reference level with maximal threshold values has been proposed for the standard gammarid.     

Opportunities for predicting and manipulating beef quality

Meat quality is a complex concept and can be defined as the characteristics of meat which satisfy consumers and citizens. The quality concept can be divided into intrinsic quality traits (which are the characteristics of the product itself) and extrinsic quality traits (which are more or less associated to the product for instance the price, a major determinant of purchase, or any brand or quality label). Quality can also be generic for the mass market or specific for niche markets. The relative importance of the different quality traits varies with human culture and time with a general trend of an increasing contribution of healthiness, safety and extrinsic quality traits. This review underlines the need for the development of methods to interpret and aggregate measures under specific rules to be defined in order to produce an overall assessment of beef quality. Such methods can be inferred for example from genomic results or data related to muscle biochemistry to better predict tenderness or flavor. A more global assurance quality scheme (the Meat Standards Australia System) based on the aggregation of sensory quality traits has been developed in Australia to ensure palatability to consumers. We speculated that the combination of indices related to sensory and nutritional quality, social and environmental considerations (carbon footprint, animal welfare, biodiversity of pasture, rural development, etc.) and economic efficiency (incomes of farmers and of others players along the supply chain, etc.) will provide objective assessment of the overall quality of beef (i.e. incorporating an all encompassing approach) not only for the mass market but also to support official quality labels of niche markets which are so far mainly associated with the geographical origins of the products.