a simple, rapid and sensitive spectrophotometric method has been proposed for the determinationof vanadium (iv). the method is based on the catalytic effect of v (iv) on the oxidation of alkali blue bypotassium bromate at ph 4. the rate of decrease in the absorbance of alkali blue (at 572 nm) wasproportional to the concentration of v (iv) in the range of 100-6000 ng ml-1. the detection limit wa...

Alkaline anion–exchange membranes (AAEM) for alkaline polymer electrolyte fuel cells (APEFC) were successfully prepared using electron beam irradiated poly(ethylene–co– tetrafluoroethylene) precursor films grafted with vinylbenzyl chloride (VBC) monomer. The resulting chloromethyl groups were subsequently reacted with trimethylamine to form quaternary ammonium anion–exchange functional head–gro...

Positron annihilation spectra reveal isolated zinc vacancy (V(Zn)) creation in single-crystal ZnO exposed to 193-nm radiation at 100 mJ/cm(2) fluence. The appearance of a photoluminescence excitation peak at 3.18 eV in irradiated ZnO is attributed to an electronic transition from the V(Zn) acceptor level at ~100 meV to the conduction band. The observed V(Zn) density profile and hyperthermal Zn(...

Semi-preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of oridonin from Isodon rubescens by using a two-phase-solvent system composed of n-hexane-ethyl acetate-methanol-water (2.8:5:2.8:5, v/v/v/v). The targeted compound isolated, collected and purified by HSCCC was analyzed by high performance liquid chromatography (HPLC). A tota...

three marine bacteria, pseudomonas putida ptcc 1664, bacillus cereus  pttc 1665 and pseudomonas pseudoalkaligenes ptcc 1666 isolated from the east anzali wetland sediments of the caspian sea, were resistant to heavy metals of cadmium (cd), nickel (ni) and vanadium (v). pseudomonas pseudoalkaligenes ptcc 1666 was found to be resistant to all 3 metals ni, cd, v. heavy metal uptake was determined ...