Showing papers on "Sodium dichromate published in 1980"

Effect of human gastric juice on the mutagenicity of chemicals

Abstract: 10 mutagens were assayed in the Salmonella test after a pre-incubation step with human gastric juice. Such treatment affected the activity of 4 compounds, with different mechanisms, either in the sense of deactivation (sodium azide and sodium dichromate), of stabilization (captan), or even of potentiation (ICR-170). Conversely, the mutagenicity of other compounds (folpet, sodium nitrite, ICR-191, nitrofurantoin and a related drug) was unchanged. The stability of 2 carcinogens requiring metabolic activation, namely benzo[a]pyrene and aflatoxin B1, provided evidence that pre-incubation of compounds with gastric juice is compatible with the subsequent addition of liver post-mitochondrial preparations, thus reproducing in vitro 2 consecutive metabolic steps occurring in the organism. These findings lead us to report an improved correlation between assays in vivo and in vitro, in particular by explaining the lack of carcinogenicity of some mutagens introduced orally or by gastric intubation. Therefore, the Salmonella/gastric juice test is proposed as an additional assay for predicting the potential health hazards of chemicals.

Effects of drilling fluids on soils and plants: II. Complete drilling fluid mixtures

Abstract: Six typical drilling fluids (muds) and a drilling fluid base were mixed with six soils at ratios of 1:1 and 1:4 volumes of liquid mud/soil; these mixtures were tested for their effects on plant growth. Green beans (Phaseolus vulgaris) and sweet corn (Zea mays var. succharata (Sturtev.) Bailey) in pots in the greenhouse grew normally in a few mixtures, but in most instances plants had reduced growth when compared to those growing in soil alone (controls). It was concluded that high levels of soluble salts or the high exchangeable sodium percentages were the primary causes of reduced plant growth. The high salt content in some fluids was mostly from added potassium chloride, sodium hydroxide, and sodium dichromate. Dispersion of mud-treated soils caused by high exchangeable sodium percentages occurred in these samples because of the sodium hydroxide and sodium dichromate added to typical muds.

Method of surface-treating semiconductor substrate

Abstract: A surface or surfaces of a semiconductor substrate are roughened by etching the substrate with an etchant containing (i) hydrofluoric acid, ammonium fluoride and/or acid ammonium fluoride, (ii) at least one manganese- or chromium-containing oxidizing agent, such as potassium permanganate, potassium manganate, chromium trioxide, potassium or sodium chromate and potassium or sodium dichromate, and (iii) an alkali. If a rougher surface or surfaces are desired, the substrate is pre-etched with an etchant containing (i) the fluorine-containing compound and (ii) the manganese-containing oxidizing agent, and then, etched with the above-mentioned etchant.

Clastogenic Activity Of Hexavalent and Trivalent Chromium in Cultured Human Lymphocytes

Abstract: SUMMARYHuman peripheral lymphocytes cultured in vitro for 72 h have been used to compare the cytotoxic and clastogenic activity of water soluble compounds containing hexavalent chromium (as sodium dichromate, Na2Cr2O7) or trivalent chromium (as chromium chloride, CrC13).In the cultures treated for the last 24 h with different concentrations of Na2Cr2O7 (from 0.1 up to 50 × 10−6M), a decrease of the mitotic index and an increase of the percentage of cells with chromosome aberrations are noticed, which are linearly correlated with the logarithm of increasing Cr (VI) concentrations. Chromatid type aberrations are always prevalent and their frequency increases with a strongly inclined regression slope, whereas chromosomal type aberrations increase more slowly with the increasing Cr (VI) concentrations.In the cultures treated for the last 24 h with different CrCl3 concentrations (from 10 up to 7500×l0−6M), no significant increase of chromosome aberrations is noticed, not even when the cells are exposed to subt...

Method for the manufacture of capacitive electronic discs

Abstract: A method for passivating the surface of a recorded metal substrate in which the substrate is immersed for 5-30 minutes in a 35° C.-85° C. aqueous bath containing from about 5 to 30 g/l of an alkaline cleaner and from about 2.5 to 20 g/l of sodium dichromate, potassium dichromate, sodium permanganate, potassium permanganate, or mixtures thereof.

Process for the production of chromium trioxide

Abstract: Chromium trioxide contaminated with sulphate is purified by washing with an aqueous purifying wash liquor, generally water or aqueous chromic acid, while at a temperature above 50° C. and centrifuging the washed product. Washing is generally conducted on the centrifuge. The chromium trioxide is preferably made by reacting sodium dichromate with from 2.4 to 2.8 mols sulphuric acid. The process can be operated to produce a novel product consisting of crystalline, non-fused, chromium trioxide that is substantially pure. The novel product can be in the form of pellets.

Manufacture of chromium trioxide

Abstract: Chromium trioxide contaminated with sulphate is purified by washing with an aqueous purifying wash liquor, generally water or aqueous chromic acid, while at a temperature above 50 DEG C. and centrifuging the washed product. Washing is generally conducted on the centrifuge. The chromium trioxide is preferably made by reacting sodium dichromate with from 2.4 to 2.8 mols sulphuric acid. The process can be operated to produce a novel product consisting of crystalline, non-fused, chromium trioxide that is substantially pure. The novel product can be in the form of pellets.

Treating method for aged mixed solution of chromic acid and sulfuric acid

Abstract: PURPOSE:To recover chromium as chromium oxide from an aged mixed soln. of chromic acid and sulfuric acid by adding sodium chromate or sodium dichromate to the soln. followed by neutralization, thermal decomposition and dissolution separation of a water sol. component. CONSTITUTION:Sodium chromate or sodium dichromate is added to an aged mixed soln. of chromic acid and sulfuric acid to prepare a soln. based on chromic acid and sodium sulfate, and this soln. is neutralized to pH 6-7 with ammonia. After removing precipitates as required, the soln. is evaporated to dryness by heating, and the dry solid is decomposed by heating. A water sol. component is then dissolution- separated to obtain chromium oxide. When an aged soln. discharging place and a treating site are distant from each other, by adding sodium chromate or sodium dichromate to the aged soln. prior to transportation the corrosive action of the soln. is weakened remarkably, and the soln. can be stored for a time and transported in a polyethylene container.