Jean-François Gaillard

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The extensive use of nano-TiO2 in industry has led to growing concerns about its potential environmental impacts. However, negligible toxicity is commonly reported under insufficient illumination and artificial solution conditions in the literature, which rarely includes discussion of the regulating role of environmental factors. Herein, we report the(More)
The coordination environment and the redox speciation of arsenic in a newly discovered arsenic hyper-accumulating fern (Pteris vittata L) were investigated by X-ray absorption spectroscopy. This method allowed us to probe arsenic directly, i.e., with minimal sample preparation. The results indicate that arsenic is predominantly accumulated as As(III) in the(More)
Metal speciation in aquatic sediments is often characterized using wet chemical sequential extraction techniques. However, these methods are operationally defined and subject to artifacts, particularly when dealing with anoxic sediments, in which metal sulfide precipitates are likely to occur. Using X-ray absorption spectroscopy (XAS) and acid-volatile(More)
Nanostructured titania (nano-TiO2) is an engineered nanomaterial that can be cytotoxic primarily as a result of its ability to generate reactive oxygen species when illuminated. Production of nano-TiO2 has increased rapidly over the last decade, leading to concerns about its release into aquatic environments. To address the possible ecological impacts of(More)
The corundum-type In(2-2x)Zn(x)Sn(x)O(3) solid solution (cor-ZITO, x ≤ 0.7) was synthesized at 1000 °C under a high pressure of 70 kbar. cor-ZITO is a high-pressure polymorph of the transparent conducting oxide bixbyite-In(2-2x)Zn(x)Sn(x)O(3) (x ≤ 0.4). Analysis of the extended X-ray absorption fine structure suggests that significant face-sharing of Zn and(More)
A large number of microorganisms are responsible for the oxidation of Mn(2+)((aq)) to insoluble Mn(3+/4+) oxides (MnO(x)()) in natural aquatic systems. This paper reports the structure of the biogenic MnO(x)(), including a quantitative analysis of cation vacancies, formed by the freshwater bacterium Leptothrix discophora SP6 (SP6-MnO(x)()). The structure(More)
We describe the characterization of an unknown and difficult to identify but geochemically and environmentally significant MnOx structure produced by a freshwater bacterium, Leptothrix discophora SP-6, using combined transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS), and UV Raman spectroscopy. The large(More)
Nanostructured titania (nano-TiO2) is produced in diverse shapes, but it remains largely unknown how tuning the morphology of nano-TiO2 may alter its toxicity. Herein, we show that material morphology plays a critical role in regulating the phototoxicity of nano-TiO2 to bacteria. Low-dimensional nano-TiO2, including nanotubes, nanorods, and nanosheets, were(More)
The use of diverse engineered nanomaterials (ENMs) potentially leads to the release of multiple ENMs into the environment. However, previous efforts to understand the behavior and the risks associated with ENMs have focused on only one material at a time. In this study, the chemical interactions between two of the most highly used ENMs, nano-TiO2, and(More)