Direct observation of cesium at the interlayer region in phlogopite mica.

To investigate the sorption mechanism of cesium (Cs) into clay minerals, high-resolution (scanning) transmission electron microscopy (TEM/STEM) imaging of Cs in mica (phlogopite) has been conducted. Platy phlogopite powders were immersed in a cesium chloride (CsCl) solution to achieve Cs(+)-K(+) ion-exchange at the interlayer regions in phlogopite. To observe many phlogopite particles with the incident electron beam parallel to the mica layers, cross-sectional thin specimens were prepared from sedimented particles using a focused ion beam. High-angle annular dark-field imaging with STEM is superior to conventional high-resolution TEM (HRTEM) for visualizing Cs at interlayer sites even in thicker crystal regions and/or at lower magnification due to the intense Z-contrast of Cs. However, HRTEM is also practical for estimating the concentration of Cs at the interlayer site from the thickness dependence of the contrast at the interlayer region. Cs sorption of micas was previously thought to be localized mainly at the frayed-edge sites of mica crystals. However, the present observations indicate that Cs substitution of K occurs not around crystal edges but deep inside the crystals along specific interlayer regions.

Ezrin, a membrane cytoskeletal cross-linker, is essential for the regulation of phosphate and calcium homeostasis.

Ezrin cross-links plasma membrane proteins with the actin cytoskeleton. In the kidney, ezrin mainly localizes at the brush border membrane of proximal tubules with the scaffolding protein, Na(+)/H(+) exchanger regulatory factor (NHERF) 1. NHERF1 interacts with the sodium/phosphate cotransporter, Npt2a. Defects in NHERF1 or Npt2a in mice cause hypophosphatemia. Here we studied the physiological role of ezrin in renal phosphate reabsorption using ezrin knockdown mice (Vil2). These mice exhibit hypophosphatemia, hypocalcemia, and osteomalacia. The reduced plasma phosphate concentrations were ascribed to defects in urinary phosphate reabsorption. Immunofluorescence and immunoblotting indicated a marked reduction in renal Npt2a and NHERF1 expression at the apical membrane of proximal tubules in the knockdown mice. On the other hand, urinary loss of calcium was not found in Vil2 mice. Plasma concentrations of 1,25-dihydroxyvitamin D were elevated following reduced plasma phosphate levels, and mRNA of the vitamin D-dependent TRPV6 calcium channel were significantly increased in the duodenum of knockdown mice. Expression of TRPV6 at the apical membrane, however, was significantly decreased. Furthermore, tibial bone mineral density was significantly lower in both the adult and young Vil2 mice. These results suggest that ezrin is required for the regulation of systemic phosphate and calcium homeostasis in vivo.

Biological treatment of wastewater discharged from biodiesel fuel production plant with alkali-catalyzed transesterification.

The biological treatment of wastewater discharged from a biodiesel fuel (BDF) production plant conducting alkali catalysis transesterification was investigated. BDF wastewater has a high pH and high hexane-extracted oil and low nitrogen concentrations, and inhibits the growth of microorganisms. The biological treatment of BDF wastewater is difficult because the composition of such wastewater is not suitable for microbial growth. To apply the microbiological treatment of BDF wastewater using an oil degradable yeast, Rhodotorula mucilaginosa, the pH was adjusted to 6.8 and several nutrients such as a nitrogen source (ammonium sulfate, ammonium chloride or urea), yeast extract, KH2PO4 and MgSO4.7H2O were added to the wastewater. The optimal initial concentration of yeast extract was 1 g/l and the optimal C/N ratio was between 17 and 68 when using urea as a nitrogen source. A growth inhibitor was also present in the BDF wastewater, and this growth inhibitor could be detected by measuring the solid content in an aqueous phase after the hexane extraction of the wastewater. Microorganisms could not grow at solid contents higher than 2.14 g/l in the wastewater. To avoid the growth inhibition, the BDF wastewater was diluted with the same volume of water. Oil degradation in the diluted BDF wastewater was observed and the best result was obtained under the determined optimal conditions. This treatment system is simple because no controllers, except for a temperature, are necessary. These results suggest that the biological treatment system developed for BDF wastewater is useful for small-scale BDF production plants.