Mineral utilization

Table 2.7 Some characteristics of minerals utilized in separation processes.

Other components which may affect mineral utilization are noted. 

In several studies (e.g., 30-36, Table I), the effects of including "processed" fiber sources (fiber isolated from natural sources) have been investigated. Results have been contradictory for example, lOgm/day cellulose decreased zinc balances in one study (3.0) but 30 to 40g/day did not affect zinc absorption in another study (36). Processed fiber may have effects which are not indicative of the effect of a similar level of endogenous fiber from foods. In summary, daily intake levels of fiber equivalent to 20 to 30g NDF/day from food sources would not be expected to have long-term deleterious effects on mineral utilization. 

However, even with a molar phytic acid to zinc ratio of 22.3, average balances were positive (Table II). In contrast, at a much lower level of phytic acid intake, Cossack and Prasad (41) observed negative zinc balances with a soy protein diet. In the latter study, the soy products were "washed" with EDTA the possibility exists that some residual EDTA remained which could have affected mineral utilization. 

As noted above, disagreement has often been observed among different studies on the effects of fiber, phytic acid and protein source on mineral utilization. Some possible reasons include (a) estimates of absorption from single meals (with or without previous consumption of the same foods used in the test meal which may also affect results) may not always be equivalent to results from multi-day balance studies, (b) in balance studies, the failure to allow sufficient time (e.g., 1-2 weeks or more) for adaptation may alter the findings, (c) variations in the compositions of meals or diets, including mineral levels, between studies may influence the results obtained, and (d) the persons used as subjects vary and this may have an affect. In addition, in the fiber studies, the levels, types, and particle size of fiber fed have varied widely and levels of other possibly confounding components (e.g., caffeine, tanins, oxalates) may have differed. 

The large isotopic fractionations observed between oxidized and reduced forms of sulfur compounds and aqueous complexes require accurate appraisal of the effective cogeneticity of sulfur minerals utilized as geothermometric couples, and of their equilibrium condition, to avoid erroneous deductions. In fact, besides temperature, the isotopic composition of sulfur minerals is also affected by the bulk isotopic composition of the sulfur in the system (which is controlled... 

HV142 Kanauchi O., Y. Araki, A. Andoh, et al. Effect of germinated barley foodstuff administration on mineral utilization in rodents. J Gastroenterol 2000 35(3) 188-194. 

One of the most active areas of research on foods in the last few years has been the investigation of factors that effect human and animal mineral utilization from plant foods. 

Recent review articles (, 104-109) have described general factors that affect mineral utilization from foods. General factors such as the digestibility of the food that supplies the mineral, chemical form of the element, dietary levels of other nutrients, presence of mineral chelators, particle size of the food or supplemented minerals and food processing conditions all play a role in the ultimate mineral bioavailability (104). Many unit food processing operations can be shown to directly or indirectly alter the level or chemical form of minerals or the association of minerals with other food components. 

The pattern of excess " °Ar trapped in minerals can be used to estimate the bulk diffusivity through the rock. In theory, the concentration of " °Ar in a mineral above its closure temperature should be close to zero. However, if the Ar is produced in the rock faster than it can diffuse out, then the mineral is likely to retain some excess " °Ar. The build-up of " °Ar in a mineral above its closure temperature is a function of the relative rates of Ar production and diffusion out of the rock, not the mineral. Utilizing outcrop-scale gradients in " °Ar concentrations in an amphibolite from the Simplon pass Switzerland, Baxter et al. (2001) calculate a bulk Ar diffusivity of the order 10 cm s at a temperature of 500°C (the conditions of their study). These results probably define the upper limit on the bulk Ar diffusivity in the upper crust (at least, for the immediate lithology of amphibolite) as diffusion rates are likely to decrease at lower temperatures. Studies by Poland (1979) and Scailliet (1996) also correlate excess " °Ar buildup with limited bulk diffusivity. 

Considerable investigation has been reported on the effects of increasing dietary fiber on utilization of various minerals. Fiber supplementation may dilute the concentration of minerals by increasing fecal bulk, may lessen the absorption by decreasing fecal transit time, may encourage absorption of minerals upon fiber residues or trap minerals within residues, and/or may complex with phytate and other Inhibitors of mineral utilization. However, results of studies investigating utilization of different minerals under conditions of additions of different levels and sources of fiber have in no way been conclusive (26-29). 

The first commercial application of bioleaching in Europe is the Talvivaara Sotkamo Mine in Finland. The ore contains low grade sulphide minerals. Utilization of the deposit has been extensively studied for over 20 years. Bioheapleaching technology was chosen for the extraction of nickel from the ore based on its favorable capital, operational costs and good performance data obtained in a large on-site pilot trial. 

One of the most crucial aspects of green technology is the sustainable utilization of minerals. In a sense, the concept of sustainable mineral utilization is an oxymoron because minerals removed from the geosphere are not replaced. However, the idea of sustainability can greatly extend supplies of minerals. This section addresses the approach to sustainability in obtaining minerals. The broader questions of green utilization of materials, substitution of materials, and recycling are discussed in more detail in Chapters 14 and 16. 

By using enriched stable isotopes, the absorption of zinc, copper, and iron in normal, healthy adults was studied. Stable isotopes of zinc, copper, and iron were incorporated into diets. Complete fecal samples were collected and the unabsorbed isotopes remaining in the samples were measured by TIMS. Stable isotopes were also infused in five young men to evaluate mineral utilization and kinetics with stable isotopes. Isotopic enrichments can be measured in urine and blood, so kinetic studies of essential minerals utilization are now feasible with enriched stable isotopes. 

In the photocatalytic reduction of nitrobenzenes, positive holes in the valence band were effectively removed by formic acid and oxalic acid. These hole scavengers are greener sacrificial reagents because they are easily oxidized into CO2, and thus formed CO2 molecules are removed from the liquid phase in the presence of organic acids. The photocatalytic reduction of nitrobenzenes would be more attractive if positive holes are utilized for synthesis of valuable compounds, not for fruitless degradation or mineralization. Utilization of positive holes enables simultaneous production of two valuable reduced and oxidized compounds. In the case of reduction of nitrobenzene using oxalic acid (Eq. 9.15), atom efficiency (AE) [64], which is defined in Eq. 9.16, is calculated to be 23.7 % ... 

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