Effects Of Chromium Compounds Research Articles

Effect of chromium compounds on synthesis of alkali metal ferrates (VI)

The process features of producing alkali metal ferrates (VI) in the presence of chromium and its compounds, which are contained in the feedstock were investigated. It was found that during the ferrate synthesis, chromium impurities move from iron components to the alkaline solution and crystalline ferrates as oxoanion CrO 4 2 . It is shown that at long-term storage of crystalline ferrates and their solutions in the presence of chromates, their decomposition degree increases. The influence of chromium impurities on the synthesis effectiveness of ferrate solutions by various methods was determined. It was revealed that during transpassive electrochemical dissolution with increasing chromium content in the anode material > 0.8%, a decrease in the target product yield is observed. Technological solutions to minimize the accumulation of Cr (VI) compounds in the target product, which lie in a rational feedstock selection, as well as the obligatory inclusion of several crystallization and extraction stages in inorganic (KOH solutions) and organic (methanol) solvents to the production cycle were proposed.

Teaching the properties of chromium's oxidation states with a case study method

The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013–2014. The students were taught using a case study about chromium's properties, the qualitative and quantitative analysis methods used with chromium compounds, the effects of chromium compounds on human health, and the chemical techniques that can be used to remove hexavalent chromium from wastewater. Open-ended questions were applied to determine the students' pre- and post-knowledge before and after instruction. An open-ended questionnaire and semi-structured interviews showed that the case study had a positive effect on all participants in terms of increasing their awareness of the hazardous effects of hexavalent chromium. Pair sample and independent samplet-test results revealed that the presenting and the audience groups significantly increased their content knowledge after instruction. On the other hand, while there was no statistically significant difference between the groups on verbal questions, there was a difference between the presenting and the audience groups on calculative questions. This finding shows that the mixed-method case instruction might not have affected all subjects in the same way.

Effect of chromium compounds on the properties of ion-exchange membranes

The transport properties of ion-exchange membranes MK-40 and MF-4SK, MA-40, and MA-41 in solutions of sodium chloride, chromium(III) chloride, and chromium(VI) oxide have been studied. It has been found that the MA-40 and MA-41 membranes retain their transport properties in chromium chloride(III) solutions, whereas the anion-exchange membranes in chromium(VI) oxide solutions undergo partial or complete degradation. The oxidative impact of chromate ions on both the hydrocarbon matrix of the MK-40 membranes and the chemically resistant perfluorocarbon matrix of the MF-4SK membrane has been revealed.

Effect of Chromium Compounds on Sporulation of Eimeria piriformis Oocysts

Freshly defecated unsporulated oocysts of Eimeria piriformis from rabbit were treated with various concentrations (1%, 2.5%, 5%, and 10%) of chromium compounds, potassium dichromate, potassium chromate, chromium oxide and chromium nitrate, to examine their effect on sporulation. The sporulation time of oocysts treated with 1 to 10% K(2)Cr(2)O(7) was 28 h. However, much longer sporulation times of about 60 h were required for oocysts treated with 2.5% CrO(3) and Cr(NO(3))(3). Moreover, for oocysts treated with distilled water, 1% K(2)CrO(4) and 10% K(2)CrO(4), the sporulation times required were 216, 156 and 96 h, respectively. Thus, potassium dichromate was found to have higher catalytic activity for the sporulation of E. piriformis oocysts than other chromium compounds.

Effect of Chromium Compounds on Thermochemical Transformations of Graft Copolymers of Polycaproamide and Poly(Dimethylaminoethyl Methacrylate)

IR spectroscopy and differential thermal and thermogravimetric analysis showed that impregnation of PCA fibre modified by grafting poly(dimethylaminoethyl methacrylate) (PDMAEMA) and chromium-containing compounds causes loss of thermoplasticity, accumulation of double bonds, a decrease in the maximum rate of decomposition, and an increase in coke residue. It was found that the yield of the final product increases in fabrication of carbon fibre from graft PCA—PDMAEMA copolymers in the presence of Cr(NO3)3 + (NH4)2HPO4. The carbon fibre containing chromium salts has a more developed pore structure than the initial fibre, as the almost ten-fold increase in the value of sorption of I2 indicates.

Effect of Chromium Compounds on Incidence of Social Aggression and Fertility in Prepubertal Male Mice

Effect of Chromium Compounds on Incidence of Social Aggression and Fertility in Prepubertal Male Mice

98/04022 The effects of chromium compounds on PVA-coated AN and GAP binder pyrolysis, and PVA-coated AN/GAP propellant combustion

98/04022 The effects of chromium compounds on PVA-coated AN and GAP binder pyrolysis, and PVA-coated AN/GAP propellant combustion

The effects of chromium compounds on PVA-coated AN and GAP binder pyrolysis, and PVA-coated AN/GAP propellant combustion

Pyrolysis characteristics of a mixture consisting of PVA-coated AN and chromium compounds as burning modifiers have been investigated in detail at pressures ranging from 0.1 to 5 MPa by means of DTA, DSC and TG. It has been found that the encapsulation of AN by PVA hardly affects pyrolysis characteristics of AN alone and AN with chromium compounds as burning accelerator. Chromium compounds enhance the pyrolysis reaction of AN by the following order; (NH 4) 2Cr 2O 7≥(NH 4) 2CrO 4>Cr 2O 3, but they do not affect the pyrolysis of GAP fuel-binder. The effects of chromium compounds on the burning rate of PVA-coated AN/GAP propellant have been examined. They enhance the burning rate of the propellant at pressure up to 7 MPa. Chromium oxide and ammonium dichromate would have a significant effect on the gas phase reaction and on both condensed-phase and gas phase reaction, respectively. GAP is also considered to promote the condensed-phase reaction during combustion.

Insulin-like action of chromate on glucose transport in isolated rat adipocytes.

The effects of chromium compounds on 3-O-methylglucose (3-O-MG) transport were studied in isolated rat adipocytes. Sodium chromate significantly stimulated 3-O-MG uptake into adipocytes in a dose-dependent manner without altering the equilibrium space of 3-O-MG in adipocytes. The stimulatory effect reached the maximum at 300 microM, and the effect was 60-70% of the maximal insulin effect that was obtained with 20 nM insulin. The chromate concentration achieving a half-maximal effect was estimated at 50 microM. The effect of the combination of 1 mM chromate and 20 nM insulin was equipotent to that of 20 nM insulin alone, which showed that these two effects were not additive. The stimulatory effects of 1 mM chromate and 20 nM insulin were entirely abolished in adipocytes deprived of ATP, which indicated that these effects were completely ATP-dependent. Judging from experiments using various chromium compounds, CrO4(2-) was responsible for the insulinomimetic action. These results indicate that the action of CrO4(2-) is exerted through a mechanism analogous to that of insulin action, and that CrO4(2-) is a novel and useful tool for studying issues involved in insulin actions.

Effects of chromium compounds on the respiratory system. 5. Long term inhalation of chromic acid mist in electroplating by C57BL female mice and recapitulation of our experimental studies

Long term inhalation of CrO3 mist by C57BL mice The effects of the chromic acid mist used in electroplating on the respiratory system of C57BL mice (female; n = 43) were examined histopathologically after exposure for 12 months to the mist (1.81 mgCr/m3-120 min, twice a week). Among the 23 mice sacrificed at 12 months after the first exposure, three cases of perforation in the nasal septs, a case of proliferative change of the tracheal epithelium, nine cases of emphysema and four of adenomatous metaplasia of the lungs were observed on antopsy. Among the 20 mice which were sacrificed six months after the last exposure, the same changes as the 12-month exposure group were also observed in the nasal septum, trachea and lungs, but papillomas observed in the nasal epithelia of six mice and adenoma in the lung of a mouse were new findings not seen in the 12-month exposure group. These results suggest that, in view of the low incidence of spontaneous lung tumor in C57BL mice, inhalation of chromic acid mist in electroplating might be a risk factor of lung cancer. Additionally, the occurrence of papillomas in the nasal epithelium demonstrates the need of directing attention to the possible development of cancer of the upper respiratory tract in chromium electroplating workers. Recapitulation on our experimental studies Upon completion of our five reports on the effects of chromium compounds on the respiratory system, a recapitulation of our experimental studies was made and compared with the findings of a number of reports on chromium. It was experimentally and epidemiologically confirmed that hexavalent chromium compounds act as carcinogens and cause specific biological effects on the respiratory system. These characteristics of hexavalent compounds might be attributable to the strong oxidizing potency and/or high permeability through the cell membrane. Furthermore, hexavalent compounds might be entirely different in biological action from trivalent compounds which are chemically most stable.

Nephrotoxic and hepatotoxic effects of chromium compounds in rats.

The nephrotoxic, hepatotoxic and cardiotoxic actions of hexavalent chromium compounds, as well as their effects on lung, blood and circulation may contribute to the fatal outcome of chromium intoxication. Although trivalent chromium have been regarded as relatively biologically inert, there are a few salts of chromium III that have been found to be carcinogenic when inhaled, ingested or brought in contact with the tissues. Sensitive persons and industry workers have been subjects of dermatitis, respiratory tract injuries and digestive ulcers due to chromium compounds. In this work, the authors have studied the effect of trivalent and hexavalent chromium compounds on rats measuring the transaminases (GOT and GPT), urea and creatinine levels in serum of chromium poisoned animals at different times.

Effects of chromium compounds on the respiratory system (Part 3). Inhalation of chromic oxide (Cr2O3) dust by F344 rats

Effects of chromium compounds on the respiratory system (Part 3). Inhalation of chromic oxide (Cr2O3) dust by F344 rats

Effects of chromium compounds on plasma membrane Mg 2+-ATPase activity of BHK cells

An ATPase activity stimulated by divalent ions (Mg 2+, Ca 2+, Mn 2+, Zn 2+) has been observed in intact hamster fibroblasts cultured in vitro (BHK line). Such activity has been determined by the incubation (30 min at 37°C) of washed cell suspensions (about 1 mg of proteins) in a medium containing 100 mM NaCl, 20 mM KCl, 15 mM Tris—HCl (pH 7.4), 10 mM NaHCO 3, 5 mM glucose and equimolar concentrations of ATP and divalent cation. Mg 2+-ATPase activity is insensitive to ouabain and lacks specificity towards nucleoside triphosphate substrates. AMP and ADP are not hydrolyzed under these conditions. Apparent K m of 0.76 mM and V max of 1.46 μmol Pi · mg proteins −1 · h −1 have been calculated for Mg-ATP complex. This ATPase is an ectoenzyme, therefore its activity could be used as a suitable index of the action of chemicals like chromium compounds known for their cytotoxic effects on membrane functions. Salts of trivalent (CrCl 3) and hexavalent (K 2Cr 2O 7) chromium at concentrations ranging from 1 mM to 5 mM inhibit Mg 2+-ATPase. The inhibition by K 2Cr 2O 7 is observed after pretreatment of the cells with this compound followed by its absence from the assay medium “per se” for Mg 2+-ATPase, and it is referred to the alterations of membrane bound enzyme structures by the oxidizing hexavalent chromium. The inhibition by CrCl 3 is mainly evident when this compound is present in the incubation medium, and is referred to the interaction of trivalent chromium with Mg 2+-ATP as it is partially reversed by increasing Mg 2+-ATP concentration.

Effects of hexavalent and trivalent chromium compounds on the skin.

This report is a continuation of previous investigations dealing with the effects of chromium compounds on the skin.1-3The purpose of the present study is to report the effects of hexavalent and trivalent chromium compounds in clinical and laboratory studies of the role of chromium compounds in shoe leather dermatitis, of absorption of hexavalent and trivalent chromium compounds in the skin of guinea pigs, and of conjugation between chromium salts with various proteins and the inactivation of chromium reactions. I. Chromium Compounds in the Causation of Shoe Leather Dermatitis In the most recent study,4we demonstrated the capacity of human sweat to extract chromium from chrome-tanned leathers. The findings support the observations reported by leather chemists. The chromium compounds extracted were both hexavalent and trivalent, as shown by polarographic studies. The nature of the chromium extracted was determined by spectrophotometric analyses; the trivalent chromium is in the form

The Dyeing of Wool with Chrome Dyes

The Dyeing of Wool with Chrome Dyes