Vanadium depletion

In adult humans (see Table 27.3), the vanadium content of the organs analyzed was unaffected by gender, and corresponded with that of the animal species investigated. However, from childhood up to an age of 80 + years, the vanadium content in kidneys, prostate gland and rib bone decreased significantly to only 5 - 30% of levels found in babies. Both sexes showed vanadium depletion by onset of puberty. Only in liver, the vanadium content was unaffected by age (from birth until age > 80 years) (Anke et al. 1998b, 2000). 

After intrauterine vanadium depletion, the post-natal development of both sexes was significantly reduced. Kids with a normal vanadium supply during intrauterine development grew normally (Illing-Giinther et al. 1995). 

The recovery of vanadium from these slags is of commercial interest because of the depletion of easily accessible ores and the comparatively low concentrations (ranging from less than 100 ppm to 500 ppm) of vanadium in natural deposits (147,148). In the LILCO appHcations the total ash contained up to 36% 20 (147). Vanadium is of value in the manufacture of high strength steels and specialized titanium alloys used in the aerospace industry (148,149). Magnesium vanadates allow the recovery of vanadium as a significant by-product of fuel use by electric utiUties (see Recycling, nonferrous LffiTALS). 

Analysis of the dynamics of SCR catalysts is also very important. It has been shown that surface heterogeneity must be considered to describe transient kinetics of NH3 adsorption-desorption and that the rate of NO conversion does not depend on the ammonia surface coverage above a critical value [79], There is probably a reservoir of adsorbed species which may migrate during the catalytic reaction to the active vanadium sites. It was also noted in these studies that ammonia desorption is a much slower process than ammonia adsorption, the rate of the latter being comparable to that of the surface reaction. In the S02 oxidation on the same catalysts, it was also noted in transient experiments [80] that the build up/depletion of sulphates at the catalyst surface is rate controlling in S02 oxidation. 

In the Pre-Carpathian biogeochemical province with prevalent Eutric Podsolu-visols, enriched in lead and barium and depleted in chromium and vanadium, the predominant diseases are mieloleukemia, chronic lymphatic leukemia, hemorrhagic vasculitis, hypoanemia with a relatively low number of sharp leukemia, lung and stomach cancer. 

Vanadium is recovered from several sources vanadium minerals, vanadium-bearing phosphates, boder residues, and spent vanadium catalysts. One major vanadium mineral is patronite, a greenish-black, amorphous sulfide ore used extensively for many years to produce vanadium. This mineral, found in Peru, has depleted gradually. The metal also is recovered commercially from carnotite and roscoelite. 

The concentrates obtained from ilmenite sand, being depleted in iron, are generally richer in TiOz than those from the massive deposits. Other elements in these concentrates include magnesium, manganese, and vanadium (present in the ilmenite) and aluminum, calcium, chromium, and silicon which originate from mineral intrusions. 

Treatment with either vanadium salts or organic complexes of vanadium have decreased plasma insulin levels and improved insulin sensitivity in animal models of both insulin resistance and type 2 diabetes. This work has recently been reviewed [13]. The Zucker Diabetic Fatty (ZDF) rat develops overt hyperglycemia in the presence of hyperinsulinemia followed by [3-cell depletion. This is a type 2 diabetic rat model developed from the Zucker Fatty (fa/fa) rat. In these animals, chronic treatment with vanadium reduced the elevated plasma glucose levels [152,153], The effect in the type 2 models of diabetes can take weeks to develop, whereas the effect in the type 1 models of diabetes are seen within 3 to 4 days. 

Itqiy is distinct from chondritic meteorites in bulk composition. Aluminum, FREE, europium, sodium, potassium, vanadium, chromium, and manganese are aU depleted. Itqiy has La/Yb of 0. lOxCI, and Eu/Sm of 0.16 X Cl. Refractory siderophile elements are enriched —2-3 X Cl, while moderately volatile siderophile elements are at roughly Cl abundances. The bulk rock Mg/Si and Fe/Si ratios are greater than those of EH or EL chondrites. 

Figure 7 shows the abundances of the four refractory lithophile elements—aluminum, calcium, scandium, and vanadium—in several groups of undilferentiated meteorites, the Earth s upper mantle and the Sun. The RLE abundances are divided by magnesium and this ratio is then normalized to the same ratio in Cl-chondrites. These (RLE/Mg)N ratios are plotted in Figure 7 (see also Figure 1). The level of refractory element abundances in bulk chondritic meteorites varies by less than a factor of 2. Carbonaceous chondrites have either Cl-chondritic or higher Al/Mg ratios (and other RLE/Mg ratios), while rumurutiites (highly oxidized chondritic meteorites), ordinary chondrites, acapulcoites, and enstatite chondrites are depleted in refractory elements. The (RLE/Mg)N ratio in the mantle of the Earth is within the range of carbonaceous chondrites.

Orthopyroxene partitions nickel, cobalt, and manganese less than olivine and there are no clear correlations amongst these elements. Although low in abundance, orthopyroxene can be a significant reservoir for the trivalent cations vanadium, scandium plus tetravalent titanium, due to its high modal abundance, especially in depleted xenoliths with little or... 

However, it is clear that magnesiowiistite is a significant host phase for manganese, chromium, and vanadium and may contribute to the depletions of these elements in the Earth s upper mantle, rather than metal/silicate equilibrium. 

A slightly different, but still a high pressure and temperature scenario, has been proposed recently by several groups, based on a subset of the above elements. With additional data for nickel and cobalt, Li and Agee (2001) proposed that the concentrations of these elements in Earth s upper mantle could be explained by metal-silicate equilibrium in the deep mantle (40-50 GPa and —3,000 °C). Studying nickel, cobalt, manganese, vanadium, and chromium in (Mg, Ee)0-metal systems, Gessmann and Rubie (2000) concluded that the depletions of these five elements could be... 

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