Extractive spectrophotometric determination of trace amounts of cadmium(II) in medicinal leaves and environmental samples using benzildithiosemicarbazone (BDTSC)

A new thiosemicarbazone, benzildithiosemicarbazone (BDTSC), is proposed as a sensitive and selective analytical reagent for extractive spectrophotometric determination of Cd(II). BDTSC reacts with cadmium(II) to give a yellow-colored complex in ammonium chloride-ammonium hydroxide buffer of pH 10.5, which is easily extracted into isoamylalcohol with 1:1 composition having a maximum absorbance at wavelength 360 nm. The molar absorptivity and Sandell's sensitivity are found to be 0.196 x 10(4)dm3 mol(-1)cm(-1) and 0.008 microg cm(-2) of Cd(II), respectively. The instability constant of the method has been calculated by Asmus' method as 5.05 x 10(-5) (which is in close agreement with the value obtained by Edmonds and Birnbaum's method) at room temperature. The interfering effect of various cations and anions has also been studied. The method has been successfully applied for the determination of Cd(II) in several standard reference materials as well as environmental samples, medicinal leaves and leafy vegetables.     

Fabrication of bimetallic PtPd alloy nanospheres supported on rGO sheets for superior methanol electro-oxidation

Bimetallic PtPd nanospheres strongly fabricated on reduced graphene oxide (rGO) sheets (rGO-PtPd) by simple one pot wet reflux method for superior methanol electro-oxidation. There is no any other polymer or seed involved for preparation of nanocomposite. The as-synthesized materials structure and morphology was calibrated by Powdered X-ray diffraction (P-XRD), Raman, X-ray photo electron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The PtPd nanoparticles supported rGO sheets displays superior electro-catalytic activity and stability towards methanol electro-oxidation (MOR) because of their large electrochemical surface area (ECSA, which is 1.68 times greater than that of commercial Pt/C black) and synergistic effect of the bimetallic alloy. The rGO-PtPd showed enhanced electro-catalytic performances towards MOR in acidic media due to particle size and uniform distribution of particles, which rGO-Pt1Pd1 (Pt/Pd molar ratio 1/1) showed the more specific activity, mass activity and stability for MOR. Thus, as-synthesized rGO-PtPd catalyst could apply potential applications in direct methanol fuel cells (DMFCs) to lower their cost and advance their cycle ability, which make it promising for practical catalysis in energy conversion and storage.     

Amylase production in solid state fermentation by the thermophilic fungus Thermomyces lanuginosus

The production of extracellular amylase by the thermophilic fungus Thermomyces lanuginosus was studied in solid state fermentation (SSF). Solid substrates such as wheat bran, molasses bran, rice bran, maize meal, millet cereal, wheat flakes, barley bran, crushed maize, corncobs and crushed wheat were studied for enzyme production. Growth on wheat bran gave the highest amylase activity. The maximum enzyme activity obtained was 534 U/g of wheat bran under optimum conditions of an incubation period of 120 h, an incubation temperature of 50 degrees C, an initial moisture content of 90%, a pH of 6.0, an inoculum level of 10% (v/w), a salt solution concentration of 1.5:10 (v/w) and a ratio of substrate weight to flask volume of 1:100 with soluble starch (1% w/w) and peptone (1% w/w) as supplements.     

Novel aerobic perchloroethylene degradation by the white-rot fungus Trametes versicolor

Perchloroethylene (PCE) is one of the most important groundwater pollutants around the world. It is a suspected carcinogen and is believed to be recalcitrant to microbial degradation. We report here, for the first time, aerobic degradation of PCE by the white rot fungus, Trametes versicolor, to less hazardous products. Aerobic degradation rate of PCE was 0.20 and 0.28 nmol h(-1) mg(-1) dry weight of fungal biomass. Trichloroacetic acid (TCA) was identified as the main intermediate using [2-13C]-PCE as the substrate. Chloride released and TCA produced were stoichiometric with PCE degradation. Our studies using 1 -aminobenzotriazole (ABT), an inhibitor of cytochrome P-450, suggested that a cytochrome P-450 system may be involved in PCE degradation by T. versicolor. These results are of particular interest because TCA production from PCE has not been reported to date in bacteria or fungi.