Search

Uranium–cerium oxide solid solutions, U1−xCexO2+δ·nH2O, were prepared through hydrothermal conversion of mixed U(IV)–Ce(III) oxalate precursors, cerium being used as a surrogate for plutonium. Whatever the starting pH, the fluorite-type structure of AnO2 was obtained after heating at 250 °C for 24 h. The initial pH of the reaction media appeared to affect significantly the oxide morphology: for pH ≤ 2, the powder was found to be composed of microspheres, whereas for more alkaline pH values, agglomerates of nanocrystallites were found. Furthermore, a study of the hydrothermal treatment duration (T = 250 °C, pH = 8, t = 1–48 h) showed that fluorite-type mixed dioxides started to form after only 1 h, and then became single phase after 3 h. SEM and TEM/EDS analyses revealed that the cationic distribution narrowed with time to finally form highly homogeneous mixed oxides. Such a preparation route was then applied to various cerium incorporation rates and it was found that the formation of U1−xCexO2+δ·nH2O mixed oxides was possible for 0.1 ≤ x ≤ 0.75. In all the systems investigated, the speciation of uranium and cerium was questioned in both the solid and liquid phases. Thermodynamic calculations and evaluation of the O/M ratio in the final oxides led us to understand the complex redox behaviour of uranium and cerium in solution during hydrothermal processes and to propose a conversion mechanism. [ABSTRACT FROM AUTHOR]

Background:The von Hippel-Lindau (VHL) gene encodes two mRNA variants. Variant 1 encodes two protein isoforms, pVHL213 and pVHL160, that have been extensively documented in the literature. Variant 2 is produced by alternative splicing of exon 2 and encodes a pVHL isoform of 172 amino acids with a theoretical molecular weight of 19 kDa (pVHL172), the expression of which has never been demonstrated so far due to the absence of suitable antibodies.Methods:We have generated an anti-pVHL monoclonal antibody (JD-1956) using pVHL172 recombinant protein. We tested the antibody against exogenous or endogenous expressed proteins in different cell lines. We identified the pVHL172 using a silencing RNA strategy. The epitope of the antibody was mapped using a peptide array.Results:We efficiently detected the three different isoforms of pVHL in cell lines and tumorigenic tissues by western blotting and immunohistochemistry and confirmed for the first time the endogenous expression of pVHL172.Conclusions:The endogenous expression of the three isoforms and particularly the pVHL172 has never been shown before due to a lack of a highly specific antibody since none of the available commercial antibodies distinguish the three isoforms of pVHL in cells or in both normal and cancerous human tissues. Evidence of pVHL172 expression emphasises the need to further study its implication in renal tumorigenesis and VHL disease. [ABSTRACT FROM AUTHOR]

A simple method to synthesize tetragonal zirconia stabilized at ambient temperature is developed and allows the monitoring of the tetragonal-monoclinic transition via a colloidal sol-gel process. By increasing the pH of an aqueous solution consisted of a zirconium precursor and a complexing agent (acetylacetone), a colloidal sol and then a gel can be formed under slightly acidic condition. After a drying step, tetragonal zirconia is easily obtained with an adequate thermal treatment at low temperature. The tetragonal-monoclinic transition occurs when the calcination temperature is increased. The relationship between the crystallite size, the crystallographic structure and the thermal treatment has been investigated by X-Ray Diffraction and the behaviour of the system from the gel state to the final powder has been studied by using Small Angle X-Ray Scattering and thermal analysis techniques. We demonstrate that compared to a chemical precipitation route, this colloidal sol-gel process allows the nanostructure of the material to be controlled due to the formation of primary nanoparticles. The presence of these nanoparticles makes possible the specific determination of the zirconia crystallographic phase through an accurate control of the nanostructure during the thermal treatment. [ABSTRACT FROM AUTHOR]