Showing papers on "Sodium dichromate published in 2005"

Interindividual Variability in Response to Sodium Dichromate–Induced Oxidative DNA Damage: Role of the Ser326Cys Polymorphism in the DNA-Repair Protein of 8-Oxo-7,8-Dihydro-2′-Deoxyguanosine DNA Glycosylase 1

Abstract: Although the genotoxic mechanism(s) of hexavalent chromium (CrVI) carcinogenicity remain to be fully elucidated, intracellular reduction of CrVI and concomitant generation of reactive intermediates including reactive oxygen species and subsequent oxidative damage to DNA is believed to contribute to the process of carcinogenesis. In the current study, substantial interindividual variation (7.19-25.84% and 8.79-34.72% tail DNA as assessed by conventional and FPG-modified comet assay, respectively) in levels of DNA strand breaks after in vitro treatment of WBC with sodium dichromate (100 μmol/L, 1 hour) was shown within a group of healthy adult volunteers ( n = 72) as assessed by both comet and formamidopyrimidine glycosylase–modified comet assays. No statistically significant correlation between glutathione S -transferases M1 or T1, NADPH quinone oxidoreductase 1 (codon 187) and X-ray repair cross complementation factor 1 (codon 194) genotypes and individual levels of DNA damage were observed. However, individuals homozygous for the Cys326 8-oxo 7,8-dihydro-2′-deoxyguanosine glycosylase 1 (OGG1) polymorphism had a statistically significant elevation of formamidopyrimidine glycosylase–dependent oxidative DNA damage after treatment with sodium dichromate when compared with either Ser326/Ser326 or Ser326/Cys326 individuals ( P = 0.008 and P = 0.003, respectively). In contrast, no effect of OGG1 genotype on background levels of oxidative DNA damage was observed. When individuals were divided on the basis of OGG1 genotype, Cys326/Cys326 individuals had a statistically significant ( P < 0.05, one-way ANOVA followed by Tukey test) higher ratio of oxidative DNA damage to plasma antioxidant capacity than either Ser326/Ser326 or Ser326/Cys326 individuals. The results of this study suggest that the Cys326/Cys326 OGG1 genotype may represent a phenotype that is deficient in the repair of 8-oxo-7,8-dihydro-2′-deoxyguanosine, but only under conditions of cellular oxidative stress. We hypothesize that this may be due to oxidation of the Cys326 residue. In conclusion, the homozygous Cys326 genotype may represent a biomarker of individual susceptibility of lung cancer risk in individuals that are occupationally exposed to CrVI.

Magnesium and magnesium alloy chemical oxidation process

Abstract: The chemical magnesium and magnesium alloy oxidizing process includes the technological steps of dehydrogenation, chemically deoiling, washing with hot water, washing with cold water, polishing, washing with cold water and chemical oxidization. The chemical oxidizing solution consists of methyl tetrahydroxyl phthalic anhydride, potassium sulfate or aluminum acetate, boric acid, potassium dichromate or sodium dichromate or sodium tripolyhosphate or sodium sulfite, ammonium molybdate or diammonium biphophate, ammonium nickel sulfate, deionized water and optional dithio dipropyl sulfonate in certain proportion. The present invention can obtain chemical oxide film with corrosion rate not more than 3.739 mm/a. In different chemical oxidizing conditions, oxide films of different colors may be prepared. The present invention may be applied in aeronautics, astronautics, electronics, communication, building, automobile and other industry.

Oxidative Chemical Polymerization of P-Sulphanilamide and Characterization of the Polymer Obtained

Abstract: The oxidative chemical polymerization of p-sulphanilamide was studied in hydrochloric acid solution using sodium dichromate as oxidant at 5°C under nitrogen atmosphere. The effect of hydrochloric acid, sodium dichromate, and monomer concentration on the polymerization reaction was investigated. The orders of the polymerization reactions with respect to hydrochloric acid, sodium dichromate, and monomer concentrations are found to be 0.73, 0.971, and 0.966, respectively. Also, the effect of temperature on the polymerization rate was studied and the apparent activation energy was calculated and its value was found to be 24.291 × 104 J/mol. The characterization of the obtained polymer sample at the optimum conditions was carried out by IR, UV-visible, 1H-NMR, 13C-NMR, X-ray diffraction, electron microscopic, and thermogravimetric analysis. The dielectric and a.c. conductivity were investigated as a function of temperature.

Novel process for manufacturing soda ash and sulfuric acid from sodium sulfate

Abstract: China has the richest resource of sodium sulfate in the world, mostly located in its undeveloped western area.Sodium sulfate is also a byproduct of many industrial processes,mostly containing pollutants.The market capacity of sodium sulfate is limited and its economics is poor. Therefore, it is important to develop a new process to utilize sodium sulfate economically.A novel process for manufacturing soda ash and sulfuric acid from sodium sulfate is presented in this paper. It uses calcium oxide and aqueous sodium dichromate solution as a working medium and consists of the following reactions.Reaction of sodium sulfate and calcium oxide in aqueous sodium dichromate solution to get calcium sulfate precipitate and aqueous sodium chromate solution; reduction and decomposition of calcium sulfate to regenerate calcium oxide and get sulfur dioxide; transformation of sulfur dioxide to produce sulfuric acid; carbonation of aqueous sodium chromate solution to regenerate sodium dichromate and get sodium bicarbonate precipitate; removal of chromate from sodium bicarbonate and production of sodium carbonate. The process has the features of low cost, little corrosion and pollution. Hopefully it would become a new way to utilize sodium sulfate.