On the existence of AgM9(VO4)(6)I (M = Ba, Pb)

The syntheses of the reported compounds AgM9(VO4)6I (M ¼ Ba, Pb) were reinvestigated. Stoichiometric amounts of AgI with either M3(VO4)2 (M ¼ Ba, Pb) or PbO and V2O5 were reacted in the solid-state at elevated temperatures in air or in flame-sealed quartz vessels. The resulting products were characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, and thermal analyses. Results show that, for all reaction conditions, the target AgM9(VO4)6I (M ¼ Ba, Pb) phases could not be isolated. Instead, heterogeneous phase distributions of primarily M3(VO4)2 (M ¼ Ba, Pb) and AgI were obtained. These findings demonstrate that AgI incorporation into single phase, iodine-deficient apatite derivatives for the immobilization of iodine-129 are not feasible under such conditions. This conclusion is important for the conditioning of iodine-129 in advanced reprocessing flowsheets, where iodine is typically sequestered as AgI

Synthesis and characterization of iodovanadinite using PdI2, an iodine source for the immobilisation of radioiodine

The synthesis of a palladium-containing iodovanadinite derivative, hypothetically “PdPb9(VO4)6I2”, was attempted using PdI2 as a source of iodine in searching for a novel waste form for radioiodine. Stoichiometric amounts of Pb3(VO4)2 and PdI2 were batched and reacted at elevated temperatures in sealed vessels. Batched material was also subjected to high-energy ball-milling (HEBM) in order to reduce reaction time and the potential for iodine volatilization during subsequent reaction at 200–500 °C. The resulting products were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, IR spectroscopy, thermal analysis and Pd K XANES. Results showed that PdI2 can function as a sacrificial iodine source for the formation of iodovanadinite, prototypically Pb10(VO4)6I2, however, the incorporation of Pd into this phase was not definitively observed. The sacrificial reaction mechanism involved the decomposition of PdI2 to Pd metal and nascent I2, with the latter incorporated into the iodovanadinite Pb10(VO4)6I2 phase. In comparison to processing using standard solid state reaction techniques, the use of HEBM prior to high temperature reaction generates a more homogeneous end-product with better iodine retention for this system. Overall, the key novelty and importance of this work is in demonstrating a method for direct immobilisation of undissolved PdI2 from nuclear fuel reprocessing, in a composite wasteform in which I-129 is immobilised within a durable iodovandinite ceramic, encapsulating Pd metal

An investigation of iodovanadinite wasteforms for the immobilisation of radio-iodine and technetium

99Tc and 129I are two long-lived, highly soluble and mobile fission products that pose a long-term hazard. A proposed wasteform for the disposal of radio-iodine is iodovanadinite (Pb5(VO4)3I), an apatite-structured vanadate. In this investigation, a suite of potential iodovanadinite wasteforms designed for the co-disposal of Tc and I or the sole disposal of I were synthesised via hot isostatic pressing (with Mo as a surrogate for Tc). It was found that direct synthesis from oxide and iodide precursors was possible using hot isostatic pressing (HIPing). Increasing overpressure during HIPing was found to improve the density of the final product. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses indicated that the use of AgI as the source of iodine affected the formation of the target iodovanadinite phase and produced unfavourable phase assemblages. Here, we report the direct synthesis of Pb5(VO4)3I in a single step by hot isostatic pressing

Tag polymorphisms at the A20 (TNFAIP3) locus are associated with lower gene expression and increased risk of coronary artery disease in type 2 diabetes

A20 or tumor necrosis factor (TNF)-induced protein 3 (TNFAIP3) is a negative regulator of nuclear factor-kappa B (NF-kappa B). We have investigated whether polymorphisms in this gene are associated with increased atherosclerosis in diabetic patients. Five tag single nucleotide polymorphisms (SNPs) were typed in 479 type 2 diabetic patients from Boston, including 239 coronary artery disease (CAD)positive case subjects and 240 CAD-negative control subjects. Two tag SNPs (rs5029930 and rs610604) were independently associated with CAD; adjusted odds ratios (ORs) for minor allele carriers were 2.3 (95% CI 1.4-3.8, P = 0.001) and 2.0 (1.3-2.9, P = 0.0008), respectively. The association with rs610604 was dependent on glycemic control, with ORs of 3.9 among subjects with A1C 7.0% (P for interaction = 0.015). A similar interaction pattern was found among 231 CAD-positive and 332 CAD-negative type 2 diabetic patients from Italy (OR 2.2, P = 0.05 vs. OR 0.9, P = 0.63 in the low vs. high A1C strata, P for interaction = 0.05). Quantitative RT-PCR in blood mononuclear cells from 83 nondiabetic subjects showed that rs610604 and rs5029930 minor allele homozygotes have 30-45% lower levels of A20 mRNA than major allele homozygotes, and heterozygotes have intermediate levels (P = 0.04 and 0.028, respectively). These findings point to variability in the A20/TNFAIP3 gene as a modulator of CAD risk in type 2 diabetes. This effect is mediated by allelic differences in A20 expression

On the nature of heptavalent technetium in concentrated nitric and perchloric acid

The speciation of Tc(+7) was performed in HClO4 and HNO3 by 99-Tc NMR, UV-Vis and XAFS spectroscopy. The speciation of Tc(+7) depends on the concentration and strength of the acid. Pertechnetic acid, HTcO4, forms above 8 M HClO4 while in concentrated HNO3, [TcO4]− is still the predominant species. EXAFS spectroscopy shows that the structure of HTcO4 in HClO4 is similar to the one in H2SO4. The reactivity of Tc(+7) was analyzed in the frame of the partial charge model. The partial charge calculated on the Tc atoms (ΔTc) indicates that HTcO4 (ΔTc = +057) is more electrophilic than [TcO4]− (ΔTc = +0.52). The difference in the oxidizing properties between [TcO4]− and HTcO4 is given from the reaction of these species with 12 M HCl(aq). In 13 M sulfuric acid HTcO4 is reduced to Tc(+5) while [TcO4]− is not reduced in 6 M H2SO4

A Common Haplotype at the CD36 Locus Is Associated With High FFA Levels and Increased Cardiovascular Risk in Caucasians

CD36 is a class B scavenger receptor recognizing a variety of ligands including long-chain fatty acids and modified LDL. We investigated whether genetic variability at this locus is a determinant of free fatty acid (FFA) plasma levels and risk of coronary artery disease (CAD) in Caucasians. Typing of 21 polymorphic markers, evenly spanning the CD36 gene, revealed two linkage disequilibrium (LD) blocks that could be tagged by five polymorphisms (-33137A>G, -31118G>A, 25444G>A, 27645del>ins and 30294G>C). In 585 non-diabetic individuals of Caucasian origin, the 30294G>C polymorphism was significantly associated with FFA levels (P=0.02)-an effect that was especially visible among men (P=0.009). A similar association was observed in this gender at -33137 (P=0.008) and -31118 (P=0.028). When the five tag polymorphisms were considered together, men carrying the AGGIG haplotype had 31% higher FFA (P=0.0002) and 20% higher triglycerides (P=0.025) than non-carriers. The same haplotype was associated with increased risk of CAD in 197 type 2 diabetic individuals from the US (OR=2.3, 95% CI 1.2-4.2). A similar tendency was observed in a group of 321 type 2 diabetic individuals from Italy (OR=1.4, 0.9-2.3), resulting in an overall relative risk of 1.6 (1.1-2.3, P=0.015) in the two populations considered together. By targeted resequencing, we identified a common variant in the CD36 promoter that is in strong LD with the AGGIG haplotype and could be partly responsible for these findings. In conclusion, this comprehensive study of CD36 variability indicates that the common polymorphisms at this locus modulate lipid metabolism and cardiovascular risk in Caucasians