Adsorption and diffusion of selenite on Boda Claystone Formation

This study provides adsorption and diffusion data of selenite on Boda Claystone Formation (BCF) which is a potential host rock of a deep geological disposal of high-level radioactive waste. The experiments were performed on two diverse core samples: one albitic claystone sample characteristic for the entire BCF and one pyrite containing sample sparsely occurring in BCF. The experiments were carried out under atmospheric conditions. Batch experiments were carried out to study the kinetics of adsorption at a high initial concentration (1.2 × 10−3 M), the adsorption isotherms and reversibility were investigated in the 10−10–10−3 M concentration range. Adsorption onto petrographic thin sections was done to study the elemental distribution on the microscale and the oxidation state of selenium. The maximum of the distribution coefficient was found as Kd ≈ 200 L/kg and a decrease was experienced around 10−6–10−7 M equilibrium concentration, which showed similarities to other argillaceous rocks. Isotopic exchange experiments revealed reversibility of selenite adsorption. Diffusion was studied with through-diffusion and in-diffusion experiments. Using X-ray fluorescence, despite a low initial concentration of 2.3 × 10−5 M in the in-diffusion experiment, a meaningful diffusion profile of selenium could be obtained, from which the selenite apparent diffusion coefficient Dappselenite = (1.5–4.3) × 10−14 m2/s and the selenite rock capacity factor αselenite = 1.4–2.2 were determined. As selenium species are redox sensitive the oxidation state of adsorbed species was studied with X-ray absorption near edge structure spectroscopy on Se–K edge. Adsorbed selenium remained in +IV oxidation state, however reduction was experienced on the pyritic sample

Effect of sitagliptin on cardiovascular outcomes in type 2 diabetes

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P = 0.98). There were no significant between-group differences in rates of acute pancreatitis (P = 0.07) or pancreatic cancer (P = 0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events

Ni-ZSM-5 and Cu-ZSM-5 Synthesized Directly from Aqueous Fluoride Gels.

Ni-ZSM-5 and Cu-ZSM-5 have been synthesized in a slightly acidic fluoride medium. A low water H-ZSM-5 formula was used to synthesize the metal-substituted systems using bis(tetraethylammonium) tetrachloronickelate(II) [N(CH2CH3)4]2[NiCl4] and bis(tetraethylammonium) tetrachlorocuprate(II) [N(CH2CH3)4]2[CuCl4] as the tetrahedrally coordinated metal species. X-ray diffraction analysis established the presence of highly crystalline and thermally stable material. Unit cell dimensions increased with increasing levels of metal substitution. X-ray fluorescence (XRF) bulk analysis showed increasing levels of metals in the material and corresponding decreases in the moles of silica. The maximum levels of substitution achieved were Ni 3.93 and Cu 4.38 (in wt %). Analysis by scanning electron microscopy (SEM) showed a crystal morphology similar to that of H-ZSM-5 but with smaller crystals having an increasing aspect ratio in the substituted materials. There was evidence of twinned crystals and the appearance of raised faces in all substituted samples. Thermogravimetric and derivative thermogravimetric analysis showed anomalous losses, which could be explained by Jahn-Teller distortions. Fourier transform infrared analysis of the materials showed an increasing level of distortion in significant regions of the spectra. Analysis of the filtrate, from EDTA-exchanged material, by atomic absorbance spectroscopy (AAS) showed that there were tetrahedrally coordinated M2+ species in the material and relatively small amounts were removed by ion exchange