Pressure-induced structural transitions in MgH2{_2}

The stability of MgH$_2$ has been studied up to 20~GPa using density-functional total-energy calculations. At ambient pressure $\alpha$-MgH${_2}$ takes a TiO$_2$-rutile-type structure. $\alpha$-MgH$_2$ is predicted to transform into $\gamma$-MgH${_2}$ at 0.39~GPa. The calculated structural data for $\alpha$- and $\gamma$-MgH${_2}$ are in very good agreement with experimental values. At equilibrium the energy difference between these modifications is very small, and as a result both phases coexist in a certain volume and pressure field. Above 3.84~GPa $\gamma$-MgH${_2}$ transforms into $\beta$-MgH${_2}$; consistent with experimental findings. Two further transformations have been identified at still higher pressure: i) $\beta$- to $\delta$-MgH${_2}$ at 6.73 GPa and (ii) $\delta$- to $\epsilon$-MgH${_2}$ at 10.26~GPa.Comment: 4 pages, 4 figure

Interzone short wave radiative couplings through windows and large openings : proposal of a simplified model

International audienceA simplified model of indoor short wave radiation couplings adapted to multi-zone simulations is proposed, thanks to a simplifying hypothesis and to the introduction of an indoor short wave exchange matrix. The specific properties of this matrix appear useful to quantify the thermal radiation exchanges between the zones separated by windows or large openings. Integrated in CODYRUN software, this module is detailed and compared to experimental measurements carried out on a real scale tropical buildin

Structure and Thermodynamics of the Mixed Alkali Alanates

The thermodynamics and structural properties of the hexahydride alanates (M2M'AlH6) with the elpasolite structure have been investigated. A series of mixed alkali alanates (Na2LiAlH6, K2LiAlH6 and K2NaAlH6) were synthesized and found to reversibly absorb and desorb hydrogen without the need for a catalyst. Pressure-composition isotherms were measured to investigate the thermodynamics of the absorption and desorption reactions with hydrogen. Isotherms for catalyzed (4 mol% TiCl3) and uncatalyzed Na2LiAlH6 exhibited an increase in kinetics, but no change in the bulk thermodynamics with the addition of a dopant. A structural analysis using synchrotron x-ray diffraction showed that these compounds favor the Fm-3m space group with the smaller ion (M') occupying an octahedral site. These results demonstrate that appropriate cation substitutions can be used to stabilize or destabilize the material and may provide an avenue to improving the unfavorable thermodynamics of a number of materials with promising gravimetric hydrogen densities.Comment: 6 pages, 7 figures,3 tables, submitted to PR

Perception of Nuclear Energy and Coal in France and the Netherlands

This study focuses on the perception of large scale application of nuclear energy and coal in the Netherlands and France. The application of these energy-sources and the risks and benefits are judged differently by various group in society. In Europe, France has the highest density of nuclear power plants and the Netherlands has one of the lowest. In both countries scientists and social scientists completed a questionnaire assessing the perception of the large scale application of both energy sources. Furthermore, a number of variables relating to the socio cultural and political circumstances were measured. The results indicate that the French had a higher risk perception and a more negative attitude toward nuclear power than the Dutch. But they also assess the benefits of the use of nuclear power to be higher. Explanations for these differences are discussed

Alberta Infant Motor Scale:Cross-cultural analysis of gross motor development in Dutch and Canadian infants and introduction of Dutch norms

Background: The Alberta Infant Motor Scale (AIMS) has been developed in Canada in the 90ies. The AIMS and its Canadian norms are frequently used across the world to monitor infants' gross motor development. Currently, it is disputed whether the Canadian norms are valid for non-Canadian infants. Aims: To compare scores on the AIMS of Dutch infants with that of the Canadian norms, to compare the sequence of motor milestones in Dutch and Canadian infants, and to establish Dutch AIMS norms. Study design: Cross-sectional study. Subjects: 1697 infants, aged 2-18 months, representative of the Dutch population (gestational age 39.7 weeks (27-42)). Outcome measure. AIMS assessments, based on standardized video. Perinatal and social information was obtained by questionnaire and medical records. To create Dutch reference values quantile regression with polynomial splines was used. Results: 1236 Dutch infants (73%) scored below the 50th (P50) percentile of the Canadian norms, 653 (38%) below the P10 and 469 (28%) below the P5. In infants aged 6 to 12 months these values were: 567 infants (81%) <P50, 288 infants (41%) <P10, 201 infants (29%) <P5. The sequence of achievement of motor milestones of Dutch and Canadian infants was similar. Dutch norm-reference values of the AIMS were calculated. Conclusions and implications: Gross motor development of Dutch infants is considerably slower than that of the Canadian AIMS norms sample. To prevent overdiagnosis of developmental delay and overreferral to paediatric physiotherapy Dutch AIMS norms are required. The paper introduces these norms, including percentile ranks