chromate conversion coating is applied on aluminum 6061. the optimum conditions for chromate bath composition and immersion time are also obtained for standard requirements provision such as corrosion resistance in salt spray test, electrical resistance and coating quality. the applied coatings are electrochemically tested in sea and distilled water. according to tafel and cyclic polarization c...

The chromate reductase purified from Pseudomonas ambigua was found to be homologous with several nitroreductases. Escherichia coli DH5alpha and Vibrio harveyi KCTC 2720 nitroreductases were chosen for the present study, and their chromate-reducing activities were determined. A fusion between glutathione S-transferase (GST) and E. coli DH5alpha NfsA (GST-EcNfsA), a fusion between GST and E. coli...

Chromate is a widespread pollutant as a waste of human activities. However, the mechanisms underlying its high toxicity are not clearly understood. In this work, we used the yeast Saccharomyces cerevisiae to analyse the physiological effects of chromate exposure in a eukaryote cell model. We show that chromate causes a strong decrease of sulfate assimilation and sulfur metabolite pools suggesti...

In order to attenuate or to prevent chromate-induced human erythrocytes injury, the influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide on chromate-induced human erythrocytes haemoglobin oxidation and peroxidation were investigated. It was observed that pretreatment of human erythrocytes with vitamin E (20 microM), vitamin C (1 mM), salicylate (3 mM), and deferoxam...

In an attempt to develop biomarkers of chromate and nickel exposure, we have used a rapid, simple and sensitive 125I-postlabelling assay to detect the formation of DNA-protein crosslinks (DPCs) in different tissues from male Sprague-Dawley rats exposed i.p. to potassium chromate (K2CrO4) and nickel chloride (NiCl2). The results demonstrated that 20 h after rats were injected i.p. with these age...

Reactivities of chromium compounds with DNA were investigated by the DNA sequencing technique using 32P 5'-end-labeled DNA fragments, and the reaction mechanism was investigated by ESR spectroscopy. Incubation of double-stranded DNA with sodium chromate(VI) plus hydrogen peroxide or potassium tetraperoxochromate(V) led to the cleavage at the position of every base, particularly of guanine. Even...

Large-scale industrial use of chromium(VI) has resulted in widespread contamination with carcinogenic chromium(VI). The abilities of microorganisms to survive in these environments and to detoxify chromate require the presence of specific resistance systems. Here we report identification of the transposon-located (TnOtChr) chromate resistance genes from the highly tolerant strain Ochrobactrum t...

In this work, chitosan bead materials were modified by cross-linking with epichlorohydrin (EP) and glutaraldehyde (GA) for the removal of heavy metals in wastewater. Using these cross-linked chitosan materials, the dependence of adsorption of chromate anions on pH was investigated experimentally and theoretically. The experimental results show that the adsorption process of the chromate (Cr) io...

The Escherichia coli ChrR enzyme is an obligatory two-electron quinone reductase that has many applications, such as in chromate bioremediation. Its crystal structure, solved at 2.2 Å resolution, shows that it belongs to the flavodoxin superfamily in which flavin mononucleotide (FMN) is firmly anchored to the protein. ChrR crystallized as a tetramer, and size exclusion chromatography showed tha...

Lung cancer mortality among 1152 men working at three English chromate pigment factories was studied from the 1930s or 1940s until 1981. Workers at factory C were exposed only to lead chromate and experienced normal mortality (Obs/Exp deaths 7/6.45). Workers at factories A and B were exposed to both lead and zinc chromate; mortality was normal among those who had only low exposure (O/E 7/6.95)....