In variable concentration

Ca, Co, Ni, Pb, and Bi in single or combined application, with or without small amounts of mercury. The probably most important patents are cited in Ref. [211. Finally, the research and development activities led to a zinc quality, which is specified as "no mercury added" (nobody dares to claim "zero mercury"). Commercial zinc powders frequently contain a combination of indium, lead, and bismuth in variable concentrations up to 500 ppm each [25]. 

Oxidation-reduction electrodes. An inert metal (usually Pt, Au, or Hg) is immersed in a solution of two soluble oxidation forms of a substance. Equilibrium is established through electrons, whose concentration in solution is only hypothetical and whose electrochemical potential in solution is expressed in terms of the appropriate combination of the electrochemical potentials of the reduced and oxidized forms, which then correspond to a given energy level of the electrons in solution (cf. page 151). This type of electrode differs from electrodes of the first kind only in that both oxidation states can be present in variable concentrations, while, in electrodes of the first kind, one of the oxidation states is the electrode material (cf. Eqs 3.1.19 and 3.1.21). 

Herbal, natural, and food-supplement products are often used to promote weight loss (Table 59-3). The FDA does not strictly regulate these products, so the ingredients may be inactive and present in variable concentrations. After more than 800 reports of serious adverse events (e.g., seizures, stroke, and death) were attributed to ephedrine alkaloids, the FDA decided to exclude them from dietary supplements. 

The reaction of the same substrate with thiourea in variable-concentration conditions was also followed conductometrically with good results [16]. The reaction was carried out in a thermostatted reaction vessel. An autoburette was used to add a concentrated solution of thiourea. The conductance was read by means of a conductometric cell and acquired by a computer. 

Equilibrium constants for reaction (36) have been estimated from spectrophotometry. In some studies, visible spectra of solutions containing [VO(acac)2] at constant concentration and base in variable concentration show an isosbestic point, which suggests but does not prove that... 

Electrodes of the first kind differ distinctly from the redox electrodes in that in the latter case, both oxidation states can be present in variable concentrations, while in electrodes of the first kind, one of the oxidation states is the electrode material. 

Manganese is found in a limited range of mineral deposits, and in variable concentrations in soils, waters and living organisms. The composition of some common manganese minerals is given in Table 5.1. The major deposits... 

The choice of one or another of these molecules depends on the condition of the patient s skin. Tretinoin is not used if the patient has many telangiectasias AHAs are avoided if the skin is very thin. Conversely, the two products can be mixed in the same prescription, in variable concentrations, depending on the skin type and the desired effect. The concentration of tretinoin would be increased to stimulate reepithelialization the concentration of glycolic acid would be increased to improve and even out transcorneal penetration. 

Figure 9. Oxidation in variable concentration slurries. Measured [S4 ] (26) O, 20 , 30 and A, 50 g/L. Model solid lines for each slurry density shown. ki.s = 0.35 L A mol 1 pHt, 4.5 and 40°C.

Pb in variable concentration. This would then be an additional, hardly quantifiable source of 210Pb in the sediments, which results in a systematic uncertainty in the 210Pb ages. It should be noted, however, that age discrepancies between the two clocks never exceed five years. We thus conclude that the 137Cs time markers should be more reliable, but that the derived Pb/ Ra chronology can be useful for coarse age estimations below 54 cm. 

In nature, manganese can exist as common minerals, snch as carbonates, oxides, hydroxides, silicates, and to a limited extent as snlfides (Table 10.1). Next to iron, manganese is the most abundant element in the earth s crnst and is fonnd in variable concentrations in living organisms, water. 

The first choice to be made is the nature of the substances that will make the emulsion, will be the oil and aqueous pha.ses, as well as the emulsitier. In most cases, none of them will be a pure substance but rather a mixture, sometimes a very complex one. Fm instance, the aqueous phase generally contains different kinds of electroylytes in variable concentration. 

The analyst who desires a method for the determination of the protein content of plant or animal material is confronted with a voluminous and confusing literature. No better indication could be found of the unsatisfactory state of analytical development in this field. The reasons are apparent. Proteins form a very diverse group of similar compounds of extraordinary complexity, with widely different compositions and properties, yet difficult to separate completely, to purify and to dry. Their amphoteric nature, high adsorptive capacity, hydration properties and sensitivity to electrolytes cause them to vary widely in behavior depending on the composition, pH and temperature of the solvent medium (1). Moreover, they usually occur in mixture with each other in variable concentration ratios and in various solid and dissolved states. The analyst may be concerned with the content of a particular protein in such a mixture, or commonly, he wishes to know the total pro in content when that content is itself made up of a mixture of variable and uncertain composition. 

Uranium occurs naturally in variable concentrations in all soils, minerals, rocks and waters. It can also be derived from several anthropogenic sources. Uranium is weakly radioactive and human exposure to the element has long been considered to pose a radiological as well as toxic hazard (WHO, 2004 2008 Smedley et al., 2006). This dissolved toxic radioactive metal may poison drinking water sources and the food chain via contaminated surfaces and groundwater. In recent years, there has been increasing concern that the chemical effects of uranium may also pose a potential hazard to exposed populations. However, there are few if any epidemiological studies that have been able to demonstrate any resultant harm, even in occupational contexts (The Royal Society, 2001). 

The maximum velocity Vj ax and Michaelis constant were determined by measuring the catalytic effect of enz3mie in variable concentrations of sodium pyruvate as a substrate in the presence of a fixed concentration of inhibitors. 

We develop, by the sol-gel route, high-pass filters which suppress ultraviolet rays. These deposits on transparent substrate have cut-off wave lengths adjustable by judicious mixing of different doped oxides of the type Ti02, Fe203, VO3, etc., in variable concentrations [SCH 69]. 

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