Caractérisation par microsonde électronique de couches minces de Cd 1-xZnxS pour cellules solaires

Des couches de Cd1-xZnxS, obtenues par une méthode d'évaporation classique à partir d'une solution solide de quelques micromètres d'épaisseur, ont été analysées grâce à une microsonde électronique de Castaing. Dans l'épaisseur des couches correspondant à x = 0,09 et 0,10, un gradient important de l'élément Zn a pu être mis en évidence et caractérisé quantitativement parallèlement aux éléments Cd et S. Les mesures effectuées sur la tranche à partir des profils d'émission X et sur la surface pour différentes énergies du faisceau incident ont été comparées et ont permis en particulier de mettre en évidence la variation des gradients lors d'un recuit thermique

Caractérisation par microsonde électronique de couches minces de Cd 1-xZnxS pour cellules solaires

Cd1-xZnxS layers obtained by an evaporation of solid solution powders, a few microns thick have been analyzed by a Castaing microprobe. The particularity of these layers ( x = 0.09 and 0.10) which corresponds to an important Zn gradient in thickness has been characterized by X-Ray profiles. Quantitative measurements on profiles and on layers surface using different excitation energies permit to have a good idea of the concentration gradient and its variation as a function of thermal treatments.Des couches de Cd1-xZnxS, obtenues par une méthode d'évaporation classique à partir d'une solution solide de quelques micromètres d'épaisseur, ont été analysées grâce à une microsonde électronique de Castaing. Dans l'épaisseur des couches correspondant à x = 0,09 et 0,10, un gradient important de l'élément Zn a pu être mis en évidence et caractérisé quantitativement parallèlement aux éléments Cd et S. Les mesures effectuées sur la tranche à partir des profils d'émission X et sur la surface pour différentes énergies du faisceau incident ont été comparées et ont permis en particulier de mettre en évidence la variation des gradients lors d'un recuit thermique

Risques encourus par les insectes coprophages et la mesofaune edaphique apres certains traitements chimiques du betail

Available at INIST (FR), Document Supply Service, under shelf-number : RP 185 (2783) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Genetic engineering of the multicellular green alga Volvox: a modified and multiplied bacterial antibiotic resistance gene as a dominant selectable marker

Hallmann A, Rappel A. Genetic engineering of the multicellular green alga Volvox: a modified and multiplied bacterial antibiotic resistance gene as a dominant selectable marker. Plant J. 1999;17(1):99-109.The green alga Volvox represents the simplest multicellular organism: Volvox is composed of only two cell types, somatic and reproductive. Volvox, therefore, is an attractive model system for studying various aspects of multicellularity. With the biolistic nuclear transformation of Volvox carteri, the powerful molecular genetic manipulation of this organism has been established, but applications have been restricted to an auxotrophic mutant serving as the DNA recipient. Therefore, a dominant selectable marker working in all strains and mutants of this organism is required. Among several gene constructs tested, the most advantageous results were obtained with a chimeric gene composed of the coding sequence of the bacterial ble gene, conferring resistance to the antibiotic zeocin, modified with insertions of two endogenous introns from the Volvox arylsulfatase gene and fused to 5' and 3' untranslated regions from the Volvox beta 2-tubulin gene. In the most suitable plasmid used, the gene dosage was increased 16-fold by a technique that allows exponential multiplication of a DNA fragment. Co-transformation of this plasmid and a non-selectable plasmid allowed the identification of zeocin resistant transformants with nuclear integration of both selectable and non-selectable plasmids. Stable expression of the ble gene and of genes from several non-selectable plasmids is demonstrated. The modified ble gene provides the first dominant marker for transformation of both wild-type and mutant strains of Volvox

Impact of COVID-19 on Cardiovascular Testing in the United States Versus the Rest of the World

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-U.S. institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection