Caractérisation électrique de films amorphes de As50Te 50 irradiés par des ions lourds

Des films amorphes de composition As50Te50 sont irradiés avec des ions azote et néon d'énergie comprise entre 0,5 et 2 MeV. L'évolution de leur résistance électrique est suivie pendant et après l'irradiation. La diminution de résistivité est corrélée à l'état initial de la couche ; en particulier, le recuit initial-prérecuit module l'amplitude de cette décroissance. L'accroissement de conductivité est attribué à une augmentation du nombre des défauts structuraux, lesquels provoquent une modification de la densité des états localisés dans la bande interdite

ETUDE EXPERIMENTAL DE LA COMPACITE DU RESSAUT HYDRAULIQUE DANS UN CANAL TRAPEZOIDAL BRUSQUEMENT ELARGI

L'analyse bibliographique à montré que lorsque le ressaut hydraulique contrôlé est entièrement formé sur le radier du bassin amortisseur le déplacement du seuil vers l’aval ne modifie en rien la configuration du ressaut, ce qui revient à dire que la longueur  du ressaut est pratiquement assimilable à la position du seuil. Cependant, le déplacement du seuil vers l’amont  provoque la compacité du ressaut et conduit à plusieurs configurations de celui-ci, jusqu’à sa disparition complète. L’objectif principal de cette étude est de déterminer expérimentalement l’effet du seuil sur la configuration du ressaut hydraulique évoluant dans un canal trapézoïdal brusquement élargi; et de trouver des relations empiriques adimensionnelles exprimant l’effet de la compacité sur les différents paramètres du ressaut

Characterization of nanomedicines’ surface coverage using molecular probes and capillary electrophoresis

International audienceA faithful characterization of nanomedicine (NM) is needed for a better understanding of their in vivo outcomes. Size and surface charge are studied with well-established methods. However, other relevant parameters for the understanding of NM behavior in vivo remain largely inaccessible. For instance, the reactive surface of nanomedicines, which are often grafted with macromolecules to decrease their recognition by the immune system, is excluded from a systematic characterization. Yet, it is known that a subtle modification of NMs' surface characteristics (grafting density, molecular architecture and conformation of macromolecules) is at the root of major changes in the presence of biological components. In this work, a method that investigates the steric hindrance properties of the NMs’ surface coverage based on its capacity to exclude or allow adsorption of well-defined proteins was developed based on capillary electrophoresis. A series of proteins with different molecular weights (MW) were used as molecular probes to screen their adsorption behavior on nanoparticles bearing different molecular architectures at their surface. This novel strategy evaluating to some degree a functionality of NMs can bring additional information about their shell property and might allow for a better perception of their behavior in the presence of biological components. The developed method could discriminate nanoparticles with a high surface coverage excluding high MW proteins from nanoparticles with a low surface coverage that allowed high MW proteins to adsorb on their surface. The method has the potential for further standardization and automation for a routine use. It can be applied in quality control of NMs and to investigate interactions between proteins and NM in different situations

Role and Characterization of Surfaces in the Aluminium Industry

Aluminium is used extensively in the transportation, architecture, electronic and packaging industries. Aluminium presents particular characteristics such as low density, high ductility and a highly protective natural oxide film. However, formability, corrosion resistance, weldability, adhesion and surface aspect depend on the chemistry and microstructure of the metal surface. Properties of particular importance include the oxidation state, the degree of hydration and surface modifications induced by transformation and storage. For surface finishing processes it is necessary to determine the nature of chemical species created and their interactions with the substrate. Modern methods of surface characterization are extensively applied to solve these issues. Techniques such as X - ray photoelectron spectroscopy (XPS), Auger microscopy, secondary ion mass spectrometry (SIMS) and electron microscopy (TEM and SEM) are used routinely. In addition novel approaches are starting to be used systematically for industrial research (X - ray absorption spectroscopies, time of flight static SiMS and atomic force microscopy) after an initial phase of development in university laboratories. The use of these methods combined with studies of adsorption of model compounds leads to a better understanding of interfacial phenomena. For surface analysis to successfully contribute to R&D programmes, the representativity and data quantitation have to be assured. Use of several, complementary, methods enables interpretations to be confirmed. The principal applications of aluminium involving a high degree of surface technology are reviewed together with recent examples of the use of the aforementioned methods, in particular concerning the optimization of aluminium surfaces before subsequent surface finishing

Isolation and characterization of metal-resistant bacterial strain from wastewater and evaluation of its capacity in metal-ions removal using living and dry bacterial cells

International audienceA novel strain of the genus Micrococcus isolated from wastewater was studied for resistance to seven heavy metals and forty antibiotics. Its capacity to accumulate metal ions was also realized at different pH. The strain exhibited high minimal inhibitory concentration values for metal ions tested and resist to 15 antibiotics. The living cells of the bacterial strain show a largest uptake capacity at pH 6-8.5 for copper, nickel, and zinc with values ranging from 51.45 to 83.90 %, 52.59 to 78.81 %, and 59.55 to 78.90 %, respectively. It was also able to absorbed 59.81-80.08 % of chromium and 58.09-79.41 % of cobalt at pH 7.3-8.5. The maximum lead uptake was obtained at pH 5.5-8.5 with an amount of 55.28-91.06 %. The significant absorption of cadmium was shown at pH 6.5 with 38 %. In 25 A mu g mL-1 zinc, chromium, and nickel solutions, dead cells of the isolate were able to biosorbed 20.46, 22.5, and 23.98 A mu g mL(-1), respectively, after 30 min of contact. In other solutions with higher concentrations 50 and 100 A mu g mL(-1), the amount of each metal immobilized was, respectively, as follows: 38.02 and 90.21 A mu g mL(-1) for zinc, 39.78 and 89.23 A mu g mL(-1) for chromium, and 47.19 and 86.83 A mu g mL(-1) for nickel. Due to its high-metal accumulation capacity in aerobic conditions, these Gram-positive bacteria may be potentially applicable in situ bioremediation of heavy metals contaminating aqueous systems

Caractérisation électrique de films amorphes de As50Te 50 irradiés par des ions lourds

Amorphous As50Te50 films have been irradiated with Nitrogen and Neon ions in the energy range between 0.5 to 2 MeV. The electrical resistance has been monitored during the irradiation and was found to decrease. The magnitude of this decrease was depending on whether the films were preannealed or not. The conductivity enhancement is interpreted in terms of structural defects increases which give rise to density of localized states in the gap.Des films amorphes de composition As50Te50 sont irradiés avec des ions azote et néon d'énergie comprise entre 0,5 et 2 MeV. L'évolution de leur résistance électrique est suivie pendant et après l'irradiation. La diminution de résistivité est corrélée à l'état initial de la couche ; en particulier, le recuit initial-prérecuit module l'amplitude de cette décroissance. L'accroissement de conductivité est attribué à une augmentation du nombre des défauts structuraux, lesquels provoquent une modification de la densité des états localisés dans la bande interdite