Showing papers on "Sodium dichromate published in 1998"

DNA fragmentation, DNA-protein crosslinks, 32P postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine

Abstract: An in vivo study was carried out with the objectives of evaluating ( a ) the localization of DNA lesions resulting from exposure to chromium(VI) by the respiratory route, ( b ) the molecular nature of DNA alterations, and ( c ) modulation of DNA damage by a known chemopreventive agent. To this purpose, Sprague-Dawley rats received intratracheal instillations of sodium dichromate (0.25 mg/kg body weight) for three consecutive days, and the day after the last treatment lung and liver were removed for DNA purification. The results showed a selective localization of DNA lesions in the lung but not in the liver, which can be ascribed to toxicokinetics and metabolic characteristics of chromium(VI). DNA alterations included DNA-protein crosslinks, DNA fragmentation, nucleotidic modifications, and 8-hydroxy-2′-deoxyguanosine. The last two endpoints were evaluated, for the first time in chromium toxicology, by means of 32 P postlabeling procedures. This methodology was adapted to the detection of the DNA damage produced by those reactive oxygen species which result from the intracellular reduction of chromium(VI). The oral administration of the thiol N -acetylcysteine completely prevented any induction of DNA lesions in lung cells.

Electrochemical reduction of nitrates and nitrites in alkaline media in the presence of hexavalent chromium

Abstract: Electrochemical reduction of nitrates and nitrites in alkaline media at constant current is rendered inoperable in the presence of hexavalent chromate. Even at chromate concentrations as low as 9mgdm−3, the chromium hydroxide film, formed by the reduction of chromate, interferes with the reduction of nitrate and nitrite. We show that reversing the polarity of the electrodes at constant time intervals minimizes the adverse effects of the chromium hydroxide film, enabling the electrochemical reduction of nitrates and nitrites to proceed efficiently. The optimum current and reversal time are coupled through an optimum charge density of 625Ccm−2 per cycle. We also demonstrate through long-term studies that the reversal technique can be operated on a continuous basis.

Bunker coal combustion adjuvant suitable for many kinds of coal

Abstract: The present invention discloses a combustion adjuvant for coal. Said combustion adjuvant is composed of boracic mud, carbide slag, limestone, iron ore dressing tailings, manganese dioxide, offscum resulted from production of potassium dichromate, offscum produced in the course of production of sodium dichromate, bauxite, sodium hydroxide, sodium carbonate, sodium nitrate, sodium chloride and canebreak according to a certain mixing proportion. Said combustion adjuvant is applicable to several varieties of coal, including bituminous coal and anthracite coal etc., and can be added in clinker-sintering coal, and used for sintering clinker by substituing anthracite for high-quality bituminous coal.

Manufacturing method of high anticorrosion permanent magnet

Abstract: PROBLEM TO BE SOLVED: To provide the simpler manufacturing method of an anticorrosion permanent magnet wherein deterioration of magnetic characteristics with time is small. SOLUTION: An R-Fe-B based permanent magnet (R is at least one kind of rare earth elements containing Y) is dipped in alkaline chromic acide treatment liquid composed of at least one kind of chromic acid, sodium dichromate, and potassium dichromate which are adjusted at pH7-11 and at a temperature 60-100 deg.C and alkaline carbonate. Thereby, the surface of the magnet is covered with an anticorrosion protective film.

Production of 2-methyl-1,4-naphthoquinone

Abstract: PROBLEM TO BE SOLVED: To obtain the subject compound in high yield with suppressed formation of by-products in no need of complicated purification procedures after the reaction by oxidizing methylnaphthalene only with dichromic acid with no use of sulfuric acid at all. SOLUTION: 2-Methylnaphthalene, preferably an aqueous dispersion containing 30-60wt.% of the naphthalene is oxidized by adding an aqueous dichromic acid solution of, preferably 30-60wt.% concentration calculating as anhydrous chromic acid to produce the objective compound. The reaction time is usually 2-5 hours and the produced objective compound is separated by filtration and purified in a usual manner as washing with water. The aqueous solution of dichromic acid is prepared by dissolving chromic acid anhydride (CrO3 ) in water, but further by adding an inorganic acid to the aqueous solution of a dichromate salt as sodium dichromate to liberate dichromic acid and the resultant aqueous dichromic acid solution can be also utilized. In another case anhydrous chromic acid is recovered after being used in oxidation reaction, and the dichromic acid aqueous solution may be prepared by using the recovered chromic acid anhydride.

Glycated plasma proteins in experimentally induced acute toxic renal failure by dichromate injection: evidence for loss with urine and decreased plasma levels.

Abstract: In the rat, a single subcutaneous injection of sodium dichromate (20 mg/kg) causes acute renal injury and significant polyuria, proteinuria, and glycosuria (peaking 2-3 days after treatment, and returning to normal by day 5) without any changes in the plasma levels of protein, glucose, and glycated haemoglobin. Surprisingly, the percentage levels of glycated plasma total proteins and albumin (assayed by boronate affinity chromatography) transiently and significantly decrease during recovery from proteinuria (days 4 and 10 after treatment) and were found in the normal range of values by day 18. These changes are concomitant with a significant increase in the percentage level of glycated albumin in urine. Constancy of total plasma protein and the temporal pattern of levels of glycation suggest that changes in the percentage values of glycated proteins are secondary to a transient selective loss of glycated plasma proteins in urine.