Fabrication of TiO2 Nanotanks Embedded in a Nanoporous Alumina Template

The feasibility of surface nanopatterning with TiO2 nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO) template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2 gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM). The TiO2 nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM) with selected area electron diffraction (SAED) were used to investigate the TiO2 structure. The optical properties were studied using UV-Vis spectroscopy

Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers

Abstract In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700˚C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO2. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample; this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characte-* Corresponding author. M. Siampiringue et al. 143 rized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO 2 nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere

Enhancement of Photoprotection and Mechanical Properties of Polymers by Deposition of Thin Coatings

Enhancement of Photoprotection and Mechanical Properties of Polymers by Deposition of Thin Coating

Enhancement of Photoprotection and Mechanical Properties of Polymers by Deposition of Thin Coatings

Enhancement of Photoprotection and Mechanical Properties of Polymers by Deposition of Thin Coating

Premier isolement de Stephanoascus ciferrii dans des infections vaginales a la clinique biasa a Lome (Togo) First isolation of Stephanoascus ciferrii in vaginal infections in clinique biasa (Lomé, Togo).

Introduction : Les infections fongiques connaissent une croissance extraordinaire avec les progrès thérapeutiques et l’apparition de maladies immunodéprimantes telles que le VIH. Chaque année de nouvelles espèces pathogènes sont identifiées. Les candidoses vaginales font partie de la vie de la femme en activité génitale et Candida albicans est l’espèce la plus fréquemment isolée. La survenue d’infections dues à des souches de Candida non albicans résistantes aux antifongiques courants augmente la fréquence des candidoses vaginales récidivantes. Nous rapportons ici deux cas d’infections vaginales dans lesquelles ont été isolées Stephanoascus ciferrii à la Clinique Biasa à Lomé (Togo).Matériels et méthodes : Les exsudats vaginaux ont été mis en culture sur géloseSabouraud – Chloramphénicol. L’identification et la susceptibilité aux antifongiques ont été réalisées sur « VITEK® 2 Systems » (bioMérieux®, France) avec les cartes YST® et AST-YS01®. La susceptibilité à quatre antifongiques (amphotéricine B, fluconazole, flucytosine et voriconazole) a été testée à quatre concentrations différentes.Résultats : Sur la gélose Sabouraud – Chloramphénicol a été obtenu des colonies crémeuses. Dans les deux cas, une souche de Stephanoascus ciferrii a été identifiée. L’antifongigramme a révélé une sensibilité aux quatre antifongiques avec des concentrations minimales inhibitrices précises.Conclusion : L’utilisation d’un système automatisé et standardisé tel que le Vitek® 2 a été déterminante pour l’isolement de Stephanoascus ciferrii. Il faut garder à l’esprit que des pathogènes inhabituels peuvent causer ces infections vaginales.Mots clés : Stephanoascus ciferrii, Vitek 2, candidose vaginale.ABSTRACTIntroduction: Fungal infections know an extraordinary expansion with therapeutic progress and apparition of immunodepressive diseases such as HIV. Every year, new pathogenic species are identified. Vaginal candidiasis is a part of genital activity woman's life and Candida albicans is the most frequently isolated species. The intervening of infections due to strains of “non albicans Candida” resistant to current antifungal drugs increases the frequency of the relapsing vaginal candidiasis. We report here two cases of vaginal infections due to Stephanoascus ciferrii in Clinique Biasa in Lomé (Togo).Materials and methods: Vaginal secretions were cultured on Sabouraud – Chloramphénicol agar. Identification and antifungal susceptibility have been achieved on “VITEK® 2 Systems” (bioMérieux®, France) using YST® and AST-YS01® cards. The susceptibility to four antifungal drugs (amphotéricine B, fluconazole, flucytosine and voriconazole) has been tested at four different concentrations.Results: On Sabouraud - Chloramphenicol agar has been gotten creamy colonies. In the two cases Stephanoascus ciferrii is identified. The antifungal susceptibility test revealed sensitivity to the four antifungal drugs tested with a precise determination of minimal inhibitory concentrations (MIC).Conclusion: The use of an automated and standardized system as the Vitek® 2 was decisive for isolation of Stephanoascus ciferrii. It is necessary to keep in mind that, unusual germs can cause vaginal infections.Keywords: Stephanoascus ciferrii, Vitek 2, vaginal candidiasis

Enhancement of Photoprotection and Mechanical Properties of Polymers by Deposition of Thin Coatings\u94

Exposing polymers to environmental atmosphere changes their external appearance and their properties and modifies their surface. Protection from photoaging of polymers with aromatic structures such as bisphenol-A polycarbonate (PC), poly(ethylene tereph- thalate) (PET), or poly(ethylene naphthalate) (PEN) is a difficult challenge as their monomer units strongly absorb UV light. UV radiations induce chemical reactions such as the rupture of covalent bonds initiating photolytic (without intervention of oxygen) and photooxidation (fixation of oxygen) reactions. This causes, in turn, breakdown of the materials, with yellowing and embrittlement as major consequences. To prevent these damages, a very effective method to protect the polymer is the dep- osition of ceramic coatings that are transparent in the visible light range. A ceramic coat- ing physically screens the incident radiation, which reduces the undesirable effects of photochemical processes. In addition, the photooxidation rate decreases because the coat- ing acts as an oxygen barrier. Low temperature crystalline deposition is of particular interest for polymers that cannot tolerate high temperatures

Photoelectrochemical advanced oxidation processes on nanostructured TiO2 catalysts: Decolorization of a textile azo-dye

This work describes a novel approach for water treatment by photoelectrocatalysis, based on nanostructured TiO₂. The decolorization of aqueous solutions containing the azo-dye RR243 is carried out in a tubular photocatalytic reactor working in semi-batch mode under electrical polarization of the catalyst. Two different nanostructured catalysts were tested: nanotubular TiO₂ obtained by conventional anodization (CA), and a novel photoactive nanoporous TiO₂, obtained by plasma electrolytic oxidation (PEO). Neither UV irradiation of the TiO₂ catalysts nor the electrical bias individually considered lead to a significant reduction of the dye concentration. By irradiating the catalysts with UVC light while applying an electrical bias to the same, the concentration of the dye decreased from 25 L to 2,5 mg/L using the nanotubular CA TiO₂ catalyst, and to less than 1,8 mg/L using the novel nanoporous PEO TiO₂ in 50 min. The main advantages of this method over current approaches for the degradation of pollutants are both the considerable processing time reduction and a suitable and easy-to-scale-up reactor design. A further advantage is the relatively easyness in the production of the TiO₂ catalysts by PEO

TiO 2 thin films prepared via adsorptive self-assembly for self-cleaning applications

10.1021/am201721eACS Applied Materials and Interfaces421093-110