Synthesis, crystal structure and spectroscopic characterization of a new organic bismuthate (III) [C9H28N4][Bi2Cl10].H2O

The chemical preparation, crystal structure and spectroscopic characterization of [C9H28N4][Bi2Cl10].H2O have been reported. This compound crystallizes in the monoclinic system in space group P21/c and cell parameters a = 12.2385 (6), b = 17.3062 (7), c = 13.0772 (6) Å, β = 104.475 (5)°, Z = 4 and V = 2681.9 (2) Å3. Its crystal structure has been determined and refined to R = 0.049, using 5848 independent reflections. The atomic arrangement can be described by an alternation of organic and inorganic layers. The inorganic layer built up of [Bi2Cl10]4– bioctahedra arranged in sandwich between the organic layer. The organic groups are interconnected by the water molecules through N-H…O(W) hydrogen bonds to form infinite zig-zag chains spreading along the b-axis. These Chains are themselves interconnected by means of the N–H…Cl hydrogen bonds originating from [Bi2Cl10]4– anions, to form a three-dimensional network. Intermolecular Cl…Cl interactions between adjacent dimeric [Bi2Cl10]4– anions have been observed. The compound was also characterized by FT-IR and Raman spectrscopies

Revue des principales méthodes d’identification des sources de pollutions fécales des eaux et coquillages

Les contaminations fécales des eaux et des coquillages induisent des risques pour la santé humaine et des pertes économiques liées, entre autres, aux interdictions de baignade et à la fermeture des zones de conchyliculture. La réduction des apports à l’origine de cette contamination est facilitée par une identification précise des sources (humaines ou animales) qui peut aussi servir à hié rarchiser les mesures à adopter en cas de besoin. De nombreux marqueurs ont été proposés à ce titre durant les deux dernières décennies. Ils correspondent :-à des micro-organismes (bactéries, virus ou bactériophages) mis en évidence par des approaches culturales, biochimiques ou moléculaires; -à des molécules chimiques présentes naturellement dans les fèces ou associées à l’une des sources de pollution; -et à la mise en évidence de cellules spécifiques de l’hôte dissimulées dans les matières fécales. Cet article présente ces différentes methods d’identification des sources de contaminations fécales en décrivant leur utilisation et la nature des résultats qu’elles permettent d’obtenir. Le principal corollaire de cette revue bibliographique est qu’il semble nécessaire de coupler différents marqueurs pour pouvoir identifier les sources

Performances of Anode-resistive Micromegas for HL-LHC

Micromegas technology is a promising candidate to replace Atlas forward muon chambers -tracking and trigger- for future HL-LHC upgrade of the experiment. The increase on background and pile-up event probability requires detector performances which are currently under studies in intensive RD activities. We studied performances of four different resistive Micromegas detectors with different read-out strip pitches. These chambers were tested using \sim120 GeV momentum pions, at H6 CERN-SPS beam line in autumn 2010. For a strip pitch 500 micrometers we measure a resolution of \sim90 micrometers and a efficiency of ~98%. The track angle effect on the efficiency was also studied. Our results show that resistive techniques induce no degradation on the efficiency or resolution, with respect to the standard Micromegas. In some configuration the resistive coating is able to reduce the discharge currents at least by a factor of 100.Micromegas technology is a promising candidate to replace Atlas forward muon chambers -tracking and trigger- for future HL-LHC upgrade of the experiment. The increase on background and pile-up event probability requires detector performances which are currently under studies in intensive RD activities. We studied performances of four different resistive Micromegas detectors with different read-out strip pitches. These chambers were tested using \sim120 GeV momentum pions, at H6 CERN-SPS beam line in autumn 2010. For a strip pitch 500 micrometers we measure a resolution of \sim90 micrometers and a efficiency of \sim98%. The track angle effect on the efficiency was also studied. Our results show that resistive techniques induce no degradation on the efficiency or resolution, with respect to the standard Micromegas. In some configuration the resistive coating is able to reduce the discharge currents at least by a factor of 100.Comment: "Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 3 pages, 6 figures.

Effects of elevated root zone CO2 and air temperature on photosynthetic gas exchange, nitrate uptake, and total reduced nitrogen content in aeroponically grown lettuce plants

Effects of elevated root zone (RZ) CO2 and air temperature on photosynthesis, productivity, nitrate (NO3–), and total reduced nitrogen (N) content in aeroponically grown lettuce plants were studied. Three weeks after transplanting, four different RZ [CO2] concentrations [ambient (360 ppm) and elevated concentrations of 2000, 10 000, and 50 000 ppm] were imposed on plants grown at two air temperature regimes of 28 °C/22 °C (day/night) and 36 °C/30 °C. Photosynthetic CO2 assimilation (A) and stomatal conductance (gs) increased with increasing photosynthetically active radiation (PAR). When grown at 28 °C/22 °C, all plants accumulated more biomass than at 36 °C/30 °C. When measured under a PAR ≥600 μmol m−2 s−1, elevated RZ [CO2] resulted in significantly higher A, lower gs, and higher midday leaf relative water content in all plants. Under elevated RZ [CO2], the increase of biomass was greater in roots than in shoots, causing a lower shoot/root ratio. The percentage increase in growth under elevated RZ [CO2] was greater at 36 °C/30 °C although the total biomass was higher at 28 °C/22 °C. NO3– and total reduced N concentrations of shoot and root were significantly higher in all plants under elevated RZ [CO2] than under ambient RZ [CO2] of 360 ppm at both temperature regimes. At each RZ [CO2], NO3– and total reduced N concentration of shoots were greater at 28 °C/22 °C than at 36 °C/30 °C. At all RZ [CO2], roots of plants at 36 °C/30 °C had significantly higher NO3– and total reduced N concentrations than at 28 °C/22 °C. Since increased RZ [CO2] caused partial stomatal closure, maximal A and maximal gs were negatively correlated, with a unique relationship for each air temperature. However, across all RZ [CO2] and temperature treatments, there was a close correlation between maximal A and total shoot reduced N concentration of plants under different RZ [CO2], indicating that increased A under elevated RZ [CO2] could partially be due to the higher shoot total reduced N

Développement d'outils microbiologiques et chimiques permettant d'identifier l'origine des pollutions fécales dans les eaux de baignades

La pollution organique issue des effluents d'élevage et des stations d'épuration urbaines conduit à un problème essentiel de santé publique lié à la contamination des eaux de surface où s'exercent des activités sensibles telles que la baignade. S'il est possible de déterminer les pollutions localisées liées à un dysfonctionnement des systèmes de traitement, il est beaucoup plus difficile d'identifier les pollutions organiques diffuses qui participent pourtant majoritairement à la dégradation de la qualité des eaux de surface. La problématique des pollutions diffuses est d'autant plus importante que la nouvelle réglementation européenne concernant les eaux de baignade (Directive 2006/7/CE) demande de constituer des profils de baignade qui nécessitent une identification et une hiérarchisation des sources de pollutions fécales. Le dénombrement de Escherichia coli et des entérocoques intestinaux stipulé par les textes réglementaires européens, représente actuellement le seul outil analytique permettant la mise en évidence d'une contamination fécale du milieu aquatique, sans toutefois différencier l'origine humaine ou animale de cette contamination. Il est donc nécessaire de développer de nouvelles méthodes de détection de la pollution fécale qui puissent non seulement mettre en évidence une contamination mais aussi en indiquer l'origine. C'est d'ailleurs dans cet objectif que s'est développé depuis quelques années, le concept de "Microbial Source Tracking" ("Traceurs de Sources Microbiennes") qui consiste à identifier à l'aide de marqueurs microbiologiques ou chimiques les sources de pollutions fécales. Dans ce contexte, six laboratoires de recherche se sont associés pour développer des techniques de traçage des contaminations fécales afin de proposer un outil opérationnel utilisable pour différencier les sources de pollution, de leur point d'émission jusqu'au milieu récepteur final que constituent les eaux de surface. Les marqueurs qui ont fait l'objet de cette étude sont des molécules chimiques naturelles (stéroïdes, caféine), des molécules de synthèse retrouvées dans les effluents de stations d'épuration ou des rapports de fluorescence de la matière organique ainsi que des micro-organismes (bactériophages, bactéries). A la suite des développements méthodologiques, plusieurs marqueurs ont été sélectionnés : - bactéries appartenant aux groupes bactériens dominants du tractus intestinal humain (Bifidobacterium adolescentis) et porcin (Lactobacillus amylovorus) ; - Bacteroidales spécifiques des humains, porcins et bovins (HF183, Pig-2-Bac, Rum-2-Bac); - génogroupes humains des bactériophages F ARN spécifiques; - rapports de stéroïdes : coprostanol/(24ethylcoprostanol+coprostanol) (R1) et sitostanol/coprostanol (R2); - caféine, benzophénone et tri(2-chloroethyl)phosphate (TCEP)

Neutron imaging with a Micromegas detector

The micropattern gaseous detector Micromegas has been developed for several years in Saclay and presents good performance for neutron detection. A prototype for neutron imaging has been designed and new results obtained in thermal neutron beams are presented. Based on previous results demonstrating a good 1D spatial resolution, a tomographic image of a multiwire cable has been performed using a 1D Micromegas prototype. The number of pillars supporting the micromesh is too large and leads to local losses of efficiency that distort the tomographic reconstruction. Nevertheless, this first tomographic image achieved with this kind of detector is very encouraging. The next worthwhile development for neutron imaging is to achieve a bi-dimensional detector, which is presented in the second part of this study. The purpose of measurements was to investigate various operational parameters to optimize the spatial resolution. Through these measurements the optimum spatial resolution has been found to be around 160 microns (standard deviation) using Micromegas operating in double amplification mode. Several 2D imaging tests have been carried out. Some of these results have revealed fabrication defects that occurred during the manufacture of Micromegas and that are limiting the full potential of the present neutron imaging system.Comment: 6 pages, 10 figures, presented at IEEE 2004 conference in Roma, Ital

Sources of pro-cyclicality in east Asian financial systems

Procyclicality is a normal feature of economic systems, but financial sector weaknesses can exacerbate it sufficiently to pose a threat to macroeconomic and financial stability. These include shortcomings in bank risk management and governance, in supervision and in terms of dependence on volatile sources of funds. The paper tests econometrically for the importance of such features leading to pro-cyclicality in the financial systems of 11 East Asian countries. This analysis makes it possible to identify specific policy measures for East Asian countries that could limit the extent to which financial systems exacerbate pro-cyclicality

The silicon micro-strip detector plane for the LOFT/Wide Field Monitor

The main objective of the Wide Field Monitor (WFM) on the LOFT mission is to provide unambiguous detection of the high-energy sources in a large field of view, in order to support science operations of the LOFT primary instrument, the LAD. The monitor will also provide by itself a large number of results on the timing and spectral behaviour of hundreds of galactic compact objects, Active Galactic Nuclei and Gamma-Ray Bursts. The WFM is based on the coded aperture concept where a position sensitive detector records the shadow of a mask projected by the celestial sources. The proposed WFM detector plane, based on Double Sided micro-Strip Silicon Detectors (DSSD), will allow proper 2-dimensional recording of the projected shadows. Indeed the positioning of the photon interaction in the detector with equivalent fine resolution in both directions insures the best imaging capability compatible with the allocated budgets for this telescope on LOFT. We will describe here the overall configuration of this 2D-WFM and the design and characteristics of the DSSD detector plane including its imaging and spectral performances. We will also present a number of simulated results discussing the advantages that this configuration offers to LOFT. A DSSD-based WFM will in particular reduce significantly the source confusion experienced by the WFM in crowded regions of the sky like the Galactic Center and will in general increase the observatory science capability of the mission.Comment: Proceedings of SPIE, Vol. 8443, Paper No. 8443-89, 201

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13