357 research outputs found
Structure and dynamics of Oxide Melts and Glasses : a view from multinuclear and high temperature NMR
Solid State Nuclear Magnetic Resonance (NMR) experiments allow characterizing
the local structure and dynamics of oxide glasses and melts. Thanks to the
development of new experiments, it now becomes possible to evidence not only
the details of the coordination state of the network formers of glasses but
also to characterize the nature of polyatomic molecular motifs extending over
several chemical bonds. We present results involving 31P homonuclear
experiments that allow description of groups of up to three phosphate units and
27Al/17O heteronuclear that allows evidencing μ3 oxygen bridges in
aluminate glasses and rediscussion of the structure of high temperature melts.Comment: Journal of Non-Crystalline Solids (2007) in press; Also available
online at: http://crmht.cnrs-orleans.fr/Intranet/Publications/?id=207
Laser-initiated primary and secondary nuclear reactions in Boron-Nitride
International audienceNuclear reactions initiated by laser-accelerated particle beams are a promising new approach to many applications, from medical radioisotopes to aneutronic energy production. We present results demonstrating the occurrence of secondary nuclear reactions, initiated by the primary nuclear reaction products, using multicomponent targets composed of either natural boron (B) or natural boron nitride (BN). The primary proton-boron reaction (pâ+â11B â 3 αâ+â8.7âMeV), is one of the most attractive aneutronic fusion reaction. We report radioactive decay signatures in targets irradiated at the Elfie laser facility by laser-accelerated particle beams which we interpret as due to secondary reactions induced by alpha (α) particles produced in the primary reactions. Use of a second nanosecond laser beam, adequately synchronized with the short laser pulse to produce a plasma target, further enhanced the reaction rates. High rates and chains of reactions are essential for most applications
Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy
Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient's survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using 1H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermore, a metabolic signature specific of serous (N-acetyl-aspartate) and mucinous (N-acetyl-lysine) carcinomas was found. The statistical models generated in this study are able to predict borderline tumors characterized by an intermediate metabolic pattern similar to the normal ovarian tissue. Finally and importantly, the statistical model of serous carcinomas provided good predictions of both patient's survival rates and the patient's response to chemotherapy. Conclusions. Despite the small number of samples used in this study, the results indicate that metabolomic analysis of intact tissues by HRMAS-NMR is a promising technique which might be applicable to the therapeutic management of patients
State of play and future steps for the EU Biodiversity Strategy (EU BDS) dashboard
â The EU BDS dashboard is publicly accessible through the website of the European Commissionâs Knowledge Centre for Biodiversity (KCBD) under âToolsâ.
â Following the publication of six new indicators, the EU BDS dashboard currently contains 16 indicators to monitor progress on 8 out of the 16 EU BDS targets.
â The EU BDS dashboard has also undergone technical updates to make it easier to navigate and maintain.
â The two indicators selected following the last meeting of the EU Biodiversity Platformâs Monitoring and Assessment subgroup (EUBP-MA) are planned to be published by the end of 2024, as well as the two pesticide indicators previously proposed.
â Two new indicators are proposed to be added in the EU BDS dashboard: EUBP-MA is invited to give its feedback on these proposed indicators.
â The indicator developed to track progress on the EU BDS commitment to unlock at least ⏠20 billion/year for biodiversity is also presented and open to EUBP-MA feedback
Tailoring microstructure and phase segregation for low friction carbon-based nanocomposite coatings
Friction has a direct relation with the energy efficiency and environmental cleanliness in all moving mechanical systems. To develop low friction coatings is extremely beneficial for preserving not only our limited energy resources but also the earthâs environment. This study proposes a new design for low friction carbon-based nanocomposite coatings by tailoring the microstructure and phase segregation,and thereby it contributes to better controlling the mechanical and tribological properties. Experimental findings and theoretical calculations reveal that high-hardness (18.2 GPa), high-adhesion strength (28 N) as well as low-internal stress (-0.8 GPa) can be achieved by a nanocrystallite/amorphous microstructure architecture for the nc-WC/a-C(Al) carbon-based nanocomposite coating;in particular low friction (~0.05) can be acquired by creating a strong thermodynamic driving force to promote phase segregation of graphitic carbon from the a-C structure so as to form a low shear strength graphitic tribo-layer on the friction contact surfaces. This design concept is general and has been successfully employed to fabricate a wide class of low friction carbon-based nanocomposite coating
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