290 research outputs found
Michael L. Budde, Robert W. Brimlow (éd.), The Church as Counterculture, New York, State University of New York Press, 2000
No full textGrellier Isabelle. Michael L. Budde, Robert W. Brimlow (éd.), The Church as Counterculture, New York, State University of New York Press, 2000. In: Revue d'histoire et de philosophie religieuses, 82e année n°1, Janvier-Mars 2002. pp. 107-108
Neutrons in chemistry : contributions of single crystal neutron diffraction to coordination chemistry
No full text1. Introduction
Single crystal neutron diffraction is the technique of choice for unambiguously and accurately locating hydrogen atoms even in the presence of nearby “heavy atoms”. Recent advances in instrumentation and neutron sources are opening up new possibilities: in particular the use of fairly small crystals and short data collection times.
2. Results and Discussion
We will report three examples to illustrate the power of this technique in inorganic chemistry:
1) the first unambiguous structural evidence for non-conventional hydrogen bonding between a water molecule and a metal center in trans-[PtCl2(NH3)(N-glycine)]∙H2O.[1]
2) The coordination geometries of the binary platinum hydrides [Pt2(P-P)2(H)3]+ (P-P = dppb: 1,4–Bis(diphenylphosphino)butane and dpe: 1,2–Bis(diphenylphosphino)ethane).
3) The unambiguous location of deuterium atoms in the deuterated form of RuH2(η2-H2)2(PCyp3)2 (Cyp = cyclopentyl) complex as a proof of the metal-mediated C-H activation.[2]
3. References
[1] Silvia Rizzato, Jacqueline Bergès, Sax A. Mason, Alberto Albinati and Jiří Kozelka, Angew. Chem. Int. Ed., in press.
[2] M. Grellier, L. Vendier, B. Chaudret, A. Albinati, S. Rizzato, S. A. Mason and S. Sabo-Etienne J. Am. Chem. Soc., 2005,127 (50), 17593
A rational approach to the management of hepatitis C infection
No full textSummary pointsThe natural course of chronic hepatitis C is not fully defined. A range of disease exists—from mild asymptomatic infection with few consequences to serious disease with dire sequelae. Pretreatment assessments of viral load and genotype or serotype may help in predicting response. It is difficult to indicate the prognosis for younger patients with mild disease; they may need to be considered for treatment, so that the opportunity to avoid later disease is not forfeited.It is not yet clear whether patients who are more responsive to interferon have a better prognosis<br/
Synthesis, Neutron Structure, and Reactivity of the Bis(dihydrogen) Complex RuH2(η2-H2)2(PCyp3)2 Stabilized by Two Tricyclopentylphosphines
No full textTreatment of Ru(η4-C8H12)(h6-C8H10) with 3 bar H2 in the presence of 2 equiv of tricyclopentylphosphine (PCyp3) in pentane gave the new bis(dihydrogen) complex RuH2(η2-H2)2(PCyp3)2 (2), characterized by NMR and single-crystal x-ray and neutron diffraction. The single-crystal neutron diffraction study is the first carried out for a bis(dihydrogen) complex. The coordination geometry around the metal center is a distorted octahedron defined by the two phosphines in a trans configuration (making an angle of 168.9(1)°), two cis dihydrogen ligands, and two hydrides trans to them, defining the equatorial plane. The H-H bond distances (0.825(8) and 0.835(8) .ANG.) are characteristic of two unstretched dihydrogen ligands. H/D exchange between the Ru-H and the C-D bonds of deuterated benzene is obsd. within 1 h, giving various isotopomers RuHxD6-x(PCyp3)2 (with x = 0-6). 2 Is a catalyst precursor for ethylene coupling (20 bar, 293 K) to a functionalized arene (Murai reaction). The authors found a 90% conversion of acetophenone to 2-ethylacetophenone within 35 min, whereas 10 h was needed in the same conditions using the analogous tricyclohexylphosphine complex, RuH2(η2-H2)2(PCy3)2, the best catalyst precursor, at room temp., prior to this work
RGD-grafted pectin microspheres for human mesenchymal stem cell delivery and in situ bone regeneration
No full textOn nonlinear distortions of highly dispersive optical coherent systems
No full textWe investigate via experiments and simulations the statistical properties and the accumulation of nonlinear transmission impairments in coherent systems without optical dispersion compensation. We experimentally show that signal distortion due to Kerr nonlinearity can be modeled as additive Gaussian noise, and we demonstrate that its variance has a supra-linear dependence on propagation distance for 100 Gb/s transmissions over both low dispersion and standard single mode fiber. We propose a simple empirical model to account for linear and nonlinear noise accumulation, and to predict system performance for a wide range of distances, signal powers and optical noise levels
Halogen chemistry in volcanic plumes: a 1D framework based on MOCAGE 1D (version R1.18.1) preparing 3D global chemistry modelling
No full textHBr emissions from volcanoes lead rapidly to the formation of BrO within volcanic plumes and have an impact on tropospheric chemistry, at least at the local and regional scales. The motivation of this paper is to prepare a framework for further 3D modelling of volcanic halogen emissions in order to determine their fate within the volcanic plume and then in the atmosphere at the regional and global scales. The main aim is to evaluate the ability of the model to produce a realistic partitioning of bromine species within a grid box size typical of MOCAGE (Model Of atmospheric Chemistry At larGE scale) 3D (0.5×0.5). This work is based on a 1D single-column configuration of the global chemistry-transport model MOCAGE that has low enough computational cost to allow us to perform a large set of sensitivity simulations. This paper uses the emissions from the Mount Etna eruption on 10 May 2008. Several reactions are added to MOCAGE to represent the volcanic plume halogen chemistry. A simple plume parameterisation is also implemented and tested. The use of this parameterisation tends to only slightly limit the efficiency of BrO net production. Both simulations with and without the parameterisation give results for the partitioning of the bromine species, of ozone depletion and of the BrO/SO2 ratio that are consistent with previous studies. A series of test experiments were performed to evaluate the sensitivity of the results to the composition of the emissions (primary sulfate aerosols, Br radical and NO) and to the effective radius assumed for the volcanic sulfate aerosols. Simulations show that the plume chemistry is sensitive to all these parameters. We also find that the maximum altitude of the eruption changes the BrO production, which is linked to the vertical variability of the concentrations of oxidants in the background air. These sensitivity tests display changes in the bromine chemistry cycles that are generally at least as important as the plume parameterisation. Overall, the version of the MOCAGE chemistry developed for this study is suitable to produce the expected halogen chemistry in volcanic plumes during daytime and night-time
Eglises et conjugalité
No full textIsabelle Grellier, Alain Roy et Anne-Laure Zwilling (dir.), Les Églises face aux évolutions contemporaines de la conjugalité, Association des Publications de la Faculté de théologie protestante (Travaux de la Faculté de théologie protestante de Strasbourg 18), 2018
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