Chromium, potentiation

McLeod MN, Gaynes BN, Golden RN. Chromium potentiation of antidepressant pharmacotherapy for dysthymic disorder in 5 patients. J Clin Psychiatry 1999 60(4) 237 0. 

Because chromium potentiates the action of glucose, a poor chromium status might lead to impaired glucose tolerance and Type II diabetes (Anderson 1998). The prevalence of impaired glucose tolerance was 15.8% in adults aged 40-74 years in the Third National Health and Nutrition Examination Survey in the U.S. (Harris etal. 

Chromium. Chromium offers a number of potential advantages for high temperature appHcations, including oxidation resistance, low density, and a melting point over 400°C higher than that of nickel. Nevertheless, all efforts to use chromium have been hindered by its extreme brittieness (58). 

Metabolic Functions. Chromium (ITT) potentiates the action of insulin and may be considered a cofactor for insulin (137,138). In in vitro tests of epididymal fat tissue of chromium-deficient rats, Cr(III) increases the uptake of glucose only in the presence of insulin (137). The interaction of Cr(III) and insulin also is demonstrated by experimental results indicating an effect of Cr(III) in translocation of sugars into ceUs at the first step of sugar metaboHsm. Chromium is thought to form a complex with insulin and insulin receptors (136). 

Duplex stainless steels (ca 4% nickel, 23% chrome) have been identified as having potential appHcation to nitric acid service (75). Because they have a lower nickel and higher chromium content than typical austenitic steels, they provide the ductabdity of austenitic SS and the stress—corrosion cracking resistance of ferritic SS. The higher strength and corrosion resistance of duplex steel offer potential cost advantages as a material of constmction for absorption columns (see CORROSION AND CORROSION CONTROL). 

Solvent for Electrolytic Reactions. Dimethyl sulfoxide has been widely used as a solvent for polarographic studies and a more negative cathode potential can be used in it than in water. In DMSO, cations can be successfully reduced to metals that react with water. Thus, the following metals have been electrodeposited from their salts in DMSO cerium, actinides, iron, nickel, cobalt, and manganese as amorphous deposits zinc, cadmium, tin, and bismuth as crystalline deposits and chromium, silver, lead, copper, and titanium (96—103). Generally, no metal less noble than zinc can be deposited from DMSO. 

Preparation and chemistry of chromium compounds can be found ia several standard reference books and advanced texts (7,11,12,14). Standard reduction potentials for select chromium species are given ia Table 2 whereas Table 3 is a summary of hydrolysis, complex formation, or other equilibrium constants for oxidation states II, III, and VI. 

Table 2. Standard Reduction Potentials for Chromium Species ...

Eor shifting coal-derived gas, conventional iron—chromium catalysts can be used. Because coal gas has a significantly higher concentration of carbon monoxide than is found in gas streams in conventional refineries, the catalyst must be able to withstand high thermal loads. However, potential catalyst poisons such as phenol and other hydrocarbons are not a concern in entrained-bed gasifiers. 

The only components in a coating powder which might cause the waste to be classified as hazardous are certain heavy-metal pigments sometimes used as colorants. Lead- (qv) and cadmium-based pigments (qv) are seldom used, however, and other potentially hazardous elements such as barium, nickel, and chromium are usually in the form of highly insoluble materials that seldom cause of the spent powder to be characterized as a hazardous waste (86). 

The property most frequently cited in connection with the use of Ti dental or medical appHances is titanium s unique biocompatibiHty. This helps practitioners avoid occasional allergic reactions that occur with nickel or chromium alloys, and removes concerns about the toxic or carcinogenic potential of appHances that contain nickel, chromium, or beryUium. Wrought alloys of titanium are used for orthodontic wires because of their unique elastic... 

Two classes of metals have been examined for potential use as catalytic materials for automobile exhaust control. These consist of some of the transitional base metal series, for instance, cobalt, copper, chromium, nickel, manganese, and vanadium and the precious metal series consisting of platinum [7440-06-4], Pt palladium [7440-05-3], Pd rhodium [7440-16-6], Rh iridium, [7439-88-5], Ir and mthenium [7440-18-8], Ru. Specific catalyst activities are shown in Table 3. 

This method is used for the determination of total chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), manganese (Mn), beiylhum (Be), copper (Cu), zinc (Zn), lead (Pb), selenium (Se), phosphorus (P), thalhum (Tl), silver (Ag), antimony (Sb), barium (Ba), and mer-cuiy (Hg) stack emissions from stationaiy sources. This method may also be used for the determination of particulate emissions fohowing the procedures and precautions described. However, modifications to the sample recoveiy and analysis procedures described in the method for the purpose of determining particulate emissions may potentially impacl the front-half mercury determination. 

The unsaturated substituent in the carbene complex 1 often is aromatic or heteroaromatic, but can also be olefinic. The reaction conditions of the Dotz procedure are mild various functional groups are tolerated. Yields are often high. The use of chromium hexacarbonyl is disadvantageous, since this compound is considered to be carcinogenic however to date it cannot be replaced by a less toxic compound. Of particular interest is the benzo-anellation procedure for the synthesis of anthra-cyclinones, which are potentially cytostatic agents. ... 

In the case of chromium in 1 N H2SO4 transpassivity occurs at about 1 1 V (below the potential for oxygen evolution, since the equilibrium potential in acid solutions at pH 0 is 1 23 V and oxygen evolution requires an appreciable overpotential) and is associated with oxidation of chromium to dichromate anions ... 

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