Tungstate

Synthesis of a-Ag 2 WO 4 a-Ag 2 WO 4 microcrystals were prepared at 358 K for 30 min by a simple precipitation method without the use of any surfactant. The typical synthesis procedure of a-Ag 2 WO 4 crystals is described as follows: 1 Â 10 À3 mol of tungstate sodium dihydrate (Na 2 WO 4 Á2H 2 O; 99.5% purity, Sigma-Aldrich) was dissolved in 5 mL of deionized water and 2 Â 10 À3 mol of silver nitrate (AgNO 3 ; 99.8% purity, Sigma-Aldrich) was dissolved in 95 mL of deionized water at 358 K. The tungstate solution was added to the silver solution with stirring. The resulting suspensions were washed with deionized water and acetone several times to remove remaining ions and dried at 60 1C for 12 h. The a-Ag 2 WO 4 crystals were structurally characterized by X-ray diffraction (XRD) patterns using a diffractometer model LabX XRD-6000 (Shimadzu s , Japan) with Cu-Ka radiation (l = 1.5406 Å) in the 2y range from 101 to 701 with a scanning velocity of 11 per min. The shapes, sizes, visualization of Ag filaments and element distribution of the a-Ag 2 WO 4 microcrystals were observed using a FEG-SEM model Supra 35-VP, Carl Zeiss, Germany operated at 5, 10, 15 and 20 kV, and a TEM operating at 200 KV and an EDS, model Tecnai G2TF20, FEI.

Cortisol, cortisone, corticosterone, 11-dehydrocorticosterone, G6P, NADP, vanadate, tungstate, alamethicin, and metyrapone were purchased from Sigma Chemical Co. [U-14 C]G6P (100 μCi/mmol) was purchased from American Radiolabeled Chemicals, Inc. (St. Louis, MO). All other reagents were of analytical grade.