Préparation du chlorure mercureux et mesure de sa pression de vapeur
Canadian Journal of Chemistry, 1999
Mercurous chloride (Hg2Cl2), or calomel, was prepared by direct synthesis from commercial mercury... more Mercurous chloride (Hg2Cl2), or calomel, was prepared by direct synthesis from commercial mercury and mercuric chloride. The mercuric chloride mass fraction in the synthesized material is particularly small. The mercurous chloride vapor pressure was measured between 353 and 453 K by the Knudsen cell method. In order to obtain the mercurous chloride vapor pressure, we took into account the dissociation in the vapor phase into mercury and mercuric chloride. Our results are compared with those in the literature.Key words: mercurous chloride, calomel, vapor pressure, mass spectrometry, Knudsen cell.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
RÉSUMÉ. Des nanotubes de dioxyde de titane (TiO 2) ont été fabriqués par anodisation d’une feuill... more RÉSUMÉ. Des nanotubes de dioxyde de titane (TiO 2) ont été fabriqués par anodisation d’une feuille de titane dans une solution d’acide f luorhydrique et ensuite recuits à différentes températures entre 300°C et 600°C. Nous avons cherché dans ce travail la corrélation entre la structure cristalline des nano tubes de TiO2 et leur capacité à photodégrader une solution d’acide orange 7. La couche d e nanotubes a été caractérisée par microscopie électronique à balayage et par la diffr action des RX. Après le recuit à 500°C, les fractions massiques de l’anatase et du r utile sont respectivement de l’ordre de 55% et 45%. La couche recuite à 500°C montre une meilleure activité photocatalytique.
In the present work, we report on the behavior of synthesized gold nanoparticles suspension, inco... more In the present work, we report on the behavior of synthesized gold nanoparticles suspension, incorporated in titanium dioxide nanotube layers (TiO 2-NT) and fabricated by electrochemical anodization in 0.4 wt% hydrofluoric acid solution and we study its photocatalytic response. Gold nanoparticles were characterized using Transmission electron microscopy and X-ray diffraction. Scanning electron microscopy was used to study the morphology of TiO 2 nanotube layers doped by gold nanoparticles. Boosted photocatalytic performances on the degradation of an azo dye were obtained by using TiO 2 nanotube layers doped by gold nanoparticles (Au/TiO 2-NT), compared to undoped TiO 2 nanotube layer (TiO 2-NT) catalysts. Under UV irradiation, this new nanomaterial, with noble metal-semi conductor heterojunction (Au/ TiO 2-NT) exhibits a synergetic effect in accelerating the electron transfert, resulting in an enhanced photoactivity recorded in the kinetics of degradation of Acid Orange 7 (AO7). Chronoamperometry was used to highlight higher photocurrent produced by gold-titania interface submited to UV irradiation.
Journal of Biomaterials and Nanobiotechnology, 2016
Bacterial infections on the surface of medical devices are a significant problem in therapeutic a... more Bacterial infections on the surface of medical devices are a significant problem in therapeutic approach, especially when implants are used in the living. In cardiology, pacemaker generator pocket surfaces, made in titanium alloy can be colonized by pathogen microorganism. This contamination represents a major risk of sepsis, endocarditis and localized infections for patients. A way to limit this bacterial contamination is to modify the surface topography using nano-structuration process of the titanium alloy surface of the implanted devices. The aim of this study is to evaluate the influence of TiO2 nanotube layers on bacterial infection in the living, considering the feasibility of an animal model of chronic foreign body infection. TiO2 nanotube layers prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution were implanted subcutaneously in Wistar rats. Three weeks after implantation, TiO2 implants were contaminated by a Staphylococcus epidermilis strain using two different concentrations at 10 6 and 10 8 colony forming unit (CFU) in order to induce a sufficient infection level and to avoid unwanted over infection consequences on rats health during the experiments. After 28 days in the living, 75% of nanotube layers initially submitted to the 10 8 CFU inoculum were contaminated while only 25% nanotube layers initially submitted to the 10 6 CFU inoculum remained infected. This significant result underlines the influence of TiO2 nanotube layers in decreasing the infection level. Our in vitro experiments showed that the synthesized TiO2 nanotubes indeed decreased the Staphylcoccus epidermis adhesion compared to unanodized Ti foil. C. Vorilhon et al.
Journal of Biomaterials and Nanobiotechnology, 2015
The aim of this work was to evaluate the photokilling efficiency of synthesized titanium dioxide ... more The aim of this work was to evaluate the photokilling efficiency of synthesized titanium dioxide nanoparticles in suspension. Two strains of Escherichia coli, Lactobacillus casei rhamnosus and Staphylococcus aureus were used as probes to test the photokilling activities of the nanoparticles. The toxicity effects of TiO 2 nanoparticles on the environment were determined by a standard test using gram-negative bioluminescent bacteria Vibrio fischeri. The antimicrobial activity of these nanoparticles (NPs) was then investigated versus NPs concentration, UV irradiation time and microorganism strains. We evaluated the LC50 values of the nanoparticles suspension by counting the Colony-Forming Units. Results highlighted the differences in bacteria sensitivity facing photokilling treatment induced by the irradiation of anatase TiO 2 nanoparticles suspension. At the concentration of 1 g•L −1 TiO 2 , tested bacteria were killed after 30 minutes of photo-treatment. Using different TiO 2 concentrations, the Staphylococcus aureus gram-positive/catalase-positive bacteria were more resistant than gram-negative/catalase-positive ones or gram-positive/catalase-negative bacteria. An effect of UV irradiation was evaluated by the quantification of hydrogen peroxide generated by the photolysis of water molecules in presence of the nanoparticles with or without the most resistant bacterium (S. aureus). After 30 minutes with UV irradiation in these two conditions, the concentration of hydrogen peroxide was 35 µM in presence of 1.2 g•L −1 TiO 2 suspension. This result suggested that the resistance mechanism of S. aureus was not due to an extracelullar H 2 O 2 enzymatic degradation.
External fixation is a method of osteosynthesis currently used in traumatology and orthopedic sur... more External fixation is a method of osteosynthesis currently used in traumatology and orthopedic surgery. Pin tract infection is a common problem in clinical practice. Infection occurs after bacterial colonization of the pin due to its contact with skin and the local environment. One way to prevent such local contamination is to create a specific coating that could be applied in the medical field. In this work, we developed a surface coating for external fixator pins based on the photocatalytic properties of titanium dioxide, producing a bactericidal effect with sufficient mechanical strength to be compatible with surgical use. The morphology and structure of the sol-gel coating layers were characterized using, respectively, scanning electron microscopy and X-ray diffraction. The resistance properties of the coating were investigated by mechanical testing. Photodegradation of acid orange 7 in aqueous solution was used as a probe to assess the photocatalytic activity of the titanium dioxide layers under ultraviolet irradiation. The bactericidal effect induced by the process was evaluated against two strains, ie, Staphylococcus aureus and multiresistant Staphylococcus epidermidis. The coated pins showed good mechanical strength and an efficient antibacterial effect after 1 hour of ultraviolet irradiation.
Journal of Biomaterials and Nanobiotechnology, 2013
In this work, the photokilling of Escherichia coli using a "one-pot" synthesized suspension of an... more In this work, the photokilling of Escherichia coli using a "one-pot" synthesized suspension of anatase crystallized nanoparticles is evaluated. Preliminary to the biological tests concerning the antibacterial efficiency, the fabricated suspension, using a derived sol-gel process in soft chemistry condition, is characterized. Structural properties of the nanoparticles are investigated using Electronic Transmission Microscopy (TEM) equipped with Selected Area Electron Diffraction (SAED) probe and X-ray diffraction. The inorganic solid content was evaluated by Thermogravimetric Analysis (TGA). Photodegradation of Acid Orange 7 in aqueous solution was used as a probe to assess the photocatalytic activity of the elaborated suspension under UV irradiation. The photokilling of Escherichia coli in presence of hybrid TiO 2 nanoparticles suspended in aqueous liquid under UV irradiation is evaluated. Such TiO 2 nanoparticles suspension shows a strong bactericidal activity with the total destruction of bacteria after only one hour.
In this work we have developed an analytical method to measure potential titanium debris released... more In this work we have developed an analytical method to measure potential titanium debris released from TiO2 nanotube layers devices immersed in biological fluids. This quantitative study is highly required to ensure both the security and non toxicity of the nanostructured surfaces used as future implantable medical devices in the living. A one-pot synthesis process is developed to produce high quality standard solutions of titanium dioxide nanoparticles in aqueous medium. The elaborated dispersion is then used to fabricate standard solutions in both aqueous and human blood plasma media. The synthesized nanoparticles dispersion was characterized by granulometry. The nanoparticles structure and morphology were then observed using Transmission Electron Microscopy (TEM). Thermogravimetric Analysis (TGA) was used to evaluate the concentration of TiO2 in the suspension. A quantitative routine by the use of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) is developed. The...
Journal of Biomaterials and Nanobiotechnology, 2016
In this work, we study the influence of the annealing treatment on the behaviour of titanium diox... more 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. 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.
Surface nano-patterning with Ni nanodot arrays was investigated for adhesion and friction reducti... more Surface nano-patterning with Ni nanodot arrays was investigated for adhesion and friction reduction of contacting interfaces. Self-assembled anodized aluminum oxide (AAO) templates in conjunction with thermal evaporation was used to fabricate nanopatterned surfaces with ordered Ni nanodot arrays on Si substrates. Surface morphology of the Ni nanodot-patterned surfaces (NDPSs) was characterized by scanning electron microscopy (SEM). Adhesion and friction studies on a Ni NDPS and a baseline smooth Si(100) surface were conducted using a TriboIndenter employing a diamond tip with 100 lm nominal radius of curvature. The results show that the ordered Ni nanodot-patterning reduced the adhesion forces and coefficients of friction up to 92 and 83%, respectively, compared to those of the smooth silicon surface. Surprisingly, the nanoscale multi-asperity contact between the diamond tip and inhomogeneous Ni NDPSs under low loads follows a continuum contact mechanics model.
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