Molybdenum absorption rate

The apparent absorption rate of the macro elements in humans with a mixed diet varied between 98% for sodium, 83% for potassium, 61% for phosphorus, 35% for magnesium, and 13% for calcium. Ovolacto-vegetarians have a significantly decreased apparent absorption rate for magnesium and calcium, and apparent absorption rates for trace elements varied between 81% for iodine, 62% for selenium, 42% for nickel, 37% for molybdenum, 2.5% for zinc, and 2.0% for manganese. 

Tab. 18.6 Molybdenum intake, excretion, apparent absorption rate and balance of peoples with mixed and ovo-lacto-vegetarian diets...

Edwards e/a/. carried out controlled potential, slow strain-rate tests on Zimaloy (a cobalt-chromium-molybdenum implant alloy) in Ringer s solution at 37°C and showed that hydrogen absorption may degrade the mechanical properties of the alloy. Potentials were controlled so that the tensile sample was either cathodic or anodic with respect to the metal s free corrosion potential. Hydrogen was generated on the sample surface when the specimen was cathodic, and dissolution of the sample was encouraged when the sample was anodic. The results of these controlled potential tests showed no susceptibility of this alloy to SCC at anodic potentials. 

Problems in the direct determination of cadmium in soil extracts by graphite furnace atomic absorption spectrometry are overcome by the use of a low atomisation temperature of 1200 °C (mini-furnace or high heating rate of > 2000 °C/s), the addition of molybdenum, hydrogen peroxide and nitric acid as a matrix modifier, and accurate optimisation of the instrumental parameters. 

Giussani, A., Arogunjo, A., Claire Cantone, M., Tavola, F., and Veronese, 1. (2006) Rates of intestinal absorption of molybdenum in humans. Appl. Radiat. Isot., 64, 639-644. 

Silicate, arsenate, and germanate also form heteropoly acids, which on reduction yield molybdenum blue species with similar absorption maxima [97]. This positive interference in the determination of phosphate is particularly pronounced for silicate because of its relatively high concentration in many waters. However, the formation of silicomolyb-date may be suppressed by the addition of tartaric or oxalic acid to the molybdate reagent [98]. If, however, the organic acid is added after the formation of the heteropoly acid, the phosphomolybdate is destroyed, and this is used as the basis for determination of silicate in the presence of phosphate. Kinetic discrimination between phosphate and silicate, arsenate and germanate is also possible because of the faster rate of formation of phosphomolybdate. Thus, the widely adopted Murphy and Riley method employs a reagent mixture of acidic molybdate and antimonyl tartrate [83] at concentrations which are known to enhance the kinetics of phosphomolybdate and suppress the formation of silicomolybdate. 

The rate at which uranyl(V) concentration changed was estimated from the absorption spectra. The absorption at 780 nm was chosen because uranyl(VI) and molybdenum(III) ions do not absorb there and the results showing the effect of temperature, initial uranium concentration and cationic melt composition on the reaction rate are presented in Figures 6.13.8-6.13.10. Increasing the temperature or the initial uranyl(VI) concentration... 

Iron and molybdenum were determined by standard atomic absorption methods. Pore volume, densities and hardness values were determined by the usual methods used in catalysts characterizatiom Activities and selectivities of the catalysts in the conversion of methanol to formaldehyde were determined in a continuous flow pilot plant described by Karim and Hununadi [8]. Test conditions were reactor temperature 200 to 350°C (473-623 K) pressure, 10 atm (1013 kPa) flow rate, 15.858 cm /s methanol, 5.5% by volume in oxygen. 

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