Showing papers on "Potassium dichromate published in 1998"
TL;DR: In this article, the structure, doping, conductivity and thermal stability of reduced polyaniline (PANI-R) were studied by elemental analysis, FT-i.r., solid-state 13C-NMR, XPS and TGA.
283 citations
TL;DR: In this paper, the influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, potassium dichromate, and 3,5-Dichlorophenol.
Abstract: The influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, 3,5-dichlorophenol, and potassium dichromate. Emphasis was put on the following four main factors: light, temperature, nitrogen source, and pH. The green alga Selenastrum capricornutum was grown in batch cultures, and the toxic response was measured as reduction in average growth rate, relative to controls. Multifactor experiments were carried out to investigate the effects of the above four factors as well as the interactions between them: light intensity (44 and 198 μE/m2/s), temperature (16 and 26°C), nitrogen source (NH and NO), and pH of the medium (7.5 and 8.6). Within the data set generated, the highest and lowest median effective concentration estimate differed by a factor of 3.8. The sensitivity of the test system to 3,4-dichloroaniline, potassium dichromate, and 3,5-dichlorophenol was less under light limitation than under light saturation. Conversely, with the photosynthetic inhibitor atrazine a reduced sensitivity was found at high light intensity, which, however, was high enough to cause slight photoinhibition. The inhibitory response to the weak organic acid 3,5-dichlorophenol was less at the high than at the low pH level, which stems from the fact that neutral species of ionizable compounds are usually more toxic than charged species. No effect of the nitrogen source on inhibitory responses could be ascertained, and temperature influenced the results only indirectly by interacting with light (the saturation intensity increases with temperature). It is concluded that the light intensity in standardized algal toxicity tests could preferably be increased to achieve light-saturated photosynthesis as this may potentially reduce test result variability.
71 citations
TL;DR: In this article, a new flow injection analysis (FIA) manifold for the rapid determination of chemical oxygen demand is presented and evaluated, which combines sample digestion by means of an oxidant solution (i.e., potassium dichromate and mercury sulfate) in a domestic microwave oven with the liquid-liquid extraction of Cr(VI) with tributyl phosphate (TBP).
46 citations
TL;DR: The use of different oxidants allows the obtention of polymers with different redox states which, in some cases, present semiconducting properties and are soluble in methanol and acetone as discussed by the authors.
31 citations
TL;DR: The data indicate that plasma reduction capacity is enhanced by a recent meal, but may be overwhelmed at Cr( VI) concentrations between 2000 and 10,000 micrograms/L, and that the rate of Cr(VI) uptake into RBCs may not exceed the rates of intracellular reduction at these concentrations.
30 citations
TL;DR: The prevalence of contact sensitization is generally comparable with the findings of the NACDG, with the exception of reactions to potassium dichromate.
27 citations
Journal Article•
TL;DR: In this study, the short-term toxicities of sodium lauryl sulphate (an anionic detergent) and potassium dichromate on instar are studied.
Abstract: In this study, the short-term toxicities of sodium lauryl sulphate (an anionic detergent) and potassium dichromate on instar
16 citations
TL;DR: The combined treatment of both carcinogens caused a slightly greater than additive decrease in the cloning ability of the cells when compared to cells treated with the individual carcinogens, regardless of the treatment protocol used in the experiment.
Abstract: The interaction of multiple carcinogens on human cells has not been extensively examined. This study reports the results of experiments in which normal human fibroblasts were exposed to both benzo[a]pyrene diolepoxide (BPDE) and potassium dichromate. The effect of four different treatment protocols on the cloning ability of the cells and the mutant frequency of the HPRT gene was determined. The combined treatment of both carcinogens caused a slightly greater than additive decrease in the cloning ability of the cells when compared to cells treated with the individual carcinogens. The result was the same regardless of the treatment protocol used in the experiment. The results of the mutant frequency experiments, however, varied dramatically with the protocol employed. The mutant frequency in cells which were simultaneously treated with both carcinogens was dramatically reduced from the mutant frequency found when cells were treated with BPDE alone. This antagonistic effect was not present when cells were either pretreated with potassium dichromate prior to BPDE or incubated with potassium dichromate following BPDE treatment. The observed antagonistic effect was the result of oxidative stress produced by chromium since it was completely or nearly completely reversed by the addition of either vitamin E or catalase to the cultures.
16 citations
TL;DR: The HT29 and HepG2 human cell lines have been shown to express stress proteins (heat shock proteins, HSP) when submitted to a variety of sublethal environmental aggressions, and the accumulation of the mRNA coding for the HSP72 stress proteins was found to be maximum within 3 h after the aggression.
Abstract: The HT29 and HepG2 human cell lines have been shown to express stress proteins (heat shock proteins, HSP) when submitted to a variety of sublethal environmental aggressions. In the present study, these cells were submitted to standardized mild aggression by heat, ethanol, or propan-1-ol in vitro. Subsequent formation of the hsp72 mRNA was measured by a very specific RNase protection method using a radiolabeled antisense RNA probe. The accumulation of the mRNA coding for the HSP72 stress proteins was found to be maximum within 3 h after the aggression. Results were obtained faster and were much more interpretable than those from the classical method involving the autoradiography of electrophoretically separated 35 S-labeled proteins, especially in the case of very weak, threshold-level, aggressions. When this model was used as a biological system for the detection of low concentrations of chromium(VI) (Cr2O7
2-), it was possible to detect concentrations as low as 0.5 µmol/L. This indicates that measuring indices of stress induction in human cultured cells can be several orders of magnitude more sensitive than the commercial Microtox assay used for detecting low levels of pollution.
16 citations
Journal Article•
TL;DR: Patch tests with serial dilutions of nickel sulphate, potassium dichromate and cobalt chloride in petrolatum were performed on 124 nickel-sensitive, 64 chromium- sensitive, and 72 cobalt-sensitive subjects and the lowest eliciting patch test concentrations were as follows.
Abstract: Patch tests with serial dilutions of nickel sulphate, potassium dichromate and cobalt chloride in petrolatum were performed on 124 nickel-sensitive, 64 chromium-sensitive, and 72 cobalt-sensitive subjects. The lowest eliciting patch test concentrations were as follows: nickel sulphate--0.005, potassium dichromate--0.0025, and cobalt chloride--0.005.
9 citations
TL;DR: The results suggest that not only the existence of collagen macromolecules with right-handed triple helix structure but also their long-range arrangement is essential for the spiral growth of K 2 Cr 2 O 7.
Abstract: We have studied the effect of salts, adenosine triphosphate (ATP) and glycoprotein on the growth of huge right-handed spiral crystals of potassium dichromate (K 2 Cr 2 O 7 ) in gelatin gel. These materials are known to induce, respectively, amorphous, short-range and long-range arrangements of collagen macromolecules that constitute the gelatin-gel network. It was revealed that both salts and ATP have a clear tendency to reduce the spiral growth of K 2 Cr 2 O 7 , while glycoprotein strongly enhances it. These results suggest that not only the existence of collagen macromolecules with right-handed triple helix structure but also their long-range arrangement is essential for the spiral growth of K 2 Cr 2 O 7 .
TL;DR: A 16-year-old boy in whom vomiting, diffuse abdominal pain, and acute renal and liver failure developed in January 1996, after he had ingested an unknown quantity of potassium dichromate in a suicide attempt is reported on.
Abstract: To the Editor: Chromium compounds are commonly used as oxidizing agents in industrial processes and in technical-research laboratories. Oral ingestion of potassium dichromate usually leads to rapid death, regardless of immediate treatment attempts.1 Acute mucosal damage, vomiting, and diarrhea are followed by renal and hepatic failure.2 The lowest reported lethal dose is 0.1 g.3,4 We report on a 16-year-old boy in whom vomiting, diffuse abdominal pain, and acute renal and liver failure developed in January 1996, after he had ingested an unknown quantity of potassium dichromate in a suicide attempt. He obtained the poison from the chemical laboratory at . . .
TL;DR: In this paper, the solubility data for potassium dichromate in dilute aqueous methanol and 2-propanol solutions and the densities of the saturated solutions at the equilibrium temperature were determined at five temperatures (283, 288, 293, 298, and 303) K.
Abstract: Solubility data for potassium dichromate in dilute aqueous methanol and 2-propanol solutions and the densities of the saturated solutions at the equilibrium temperature were determined at five temperatures (283, 288, 293, 298, and 303) K. The solubility data were correlated with the empirical equation ln x1= A + Bxi at temperatures (283, 288, 293, and 298) K and ln x1= A + Bxi + Cxi2 at 303 K, where x1 are the mole fraction of potassium dichromate and xi the mole fraction of methanol or 2-propanol in salt-saturated solutions and A, B, and C are fitted empirical constants depending on the temperature. The precision of the fitted correlations are less than ±0.7% for both methanol and 2-propanol aqueous systems.
Patent•
06 Mar 1998
TL;DR: In this article, an R-Fe-B based permanent magnet is dipped in alkaline chromic acide treatment liquid composed of at least one kind of chromic acid, sodium dichromate, and potassium dichromates which are adjusted at pH7-11 and at a temperature 60-100 deg.C and alkaline carbonate.
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.
Patent•
11 Sep 1998
TL;DR: In this article, the authors proposed a method to grow a high-quantity II-VI compd. thin film with suppressed defects at the growth interface by the chemical etching with a mixed liq. of potassium dichromate water soln. with sulfuric acid and the surface treatment utilizing the reduction of H gas.
Abstract: PROBLEM TO BE SOLVED: To grow a high-quantity II-VI compd. thin film with suppressed defects at the growth interface by the chemical etching with a mixed liq. of potassium dichromate water soln. of a specified range of concns. with sulfuric acid and the surface treatment utilizing the reduction of H gas. SOLUTION: The chemical etching with a mixed liq. of potassium dichromate water soln. of 3-12wt.% concn. with sulfuric acid is applied to a semiconductor surface 1 which is then activated with a flat VI element oxide 10 and surface- treated, utilizing the reduction of H gas. This oxide 10 has a higher vapor pressure than that of a II oxide and allows the treating temp. to be lowered to 220 deg.C by the plasma reduction of H gas and hence a pure surface suited to the epitaxial growth is obtd., without roughening the substrate surface due to desorption of Se, etc., thus reducing the defect concn. of a II-VI compd. semiconductor film.
TL;DR: In this paper, a chemical reaction method was employed to grow doped potassium perchlorate single crystals in silica gel and the dopants used were potassium permanganate and potassium dichromate.
Abstract: Chemical reaction method was employed to grow doped potassium perchlorate single crystals in silica gel. Dopants used were potassium permanganate and potassium dichromate and the dopant levels were 500 and 1000 ppm. FT-IR spectral analysis, etching study and microhardness measurements were carried out for these crystals.
TL;DR: In this article, a new and convenient procedure for the preparation of aldehydes and ketones by the oxidation of the corresponding primary and secondary alcohols with a neutral potassium dichromate-dimethylformamide system is described.
Abstract: A new and convenient procedure for the preparation of aldehydes and ketones by the oxidation of the corresponding primary and secondary alcohols with a neutral potassium dichromate-dimethylformamide system is described.