Magnesium and/or calcium

Although FE of sodium is most commonly used to assess tubular function, FE of magnesium has been shown to be the most sensitive index in detecting low-level tubular injury in humans (Futrakul et al. 1999 Kang et al. 2000 Oladipo et al. 2003). Increases in FE of magnesium and/or calcium have also been shown to serve as sensitive indices of effects on renal function unrelated to overt renal injury (Lam and Adelstein 1986 Barton et al. 1987 Tuso and Nortman 1992 Eliott et al. 2000). 

Analysis of lunar rocks returned by Apollo astronauts reveals the presence of three major minerals, which occur in concentrations of more than 10 percent in some rocks an equal number of minor minerals, which occur in concentrations of 1 and 10 percent and a somewhat larger number of minerals that occur in only very small quantities, always less than 1 percent. The chart on pages 223-224 lists these minerals. Many of these minerals occur in more than one form. For example, the various forms of pyroxene differ in what cation is present (iron, magnesium, and/or calcium). Enstatite, one form of pyroxene, has the formula MgSiOs wollastonite is CaSi03 and hedenbergite is CaFeSi206. 

In an effort to increase the reactivity of Fe° towards chromium removal, acid washed zero-valent iron [AW-Fe(O)] was evaluated under groundwater geochemistry conditions. It was found that AW-Fe(O) could remove Cr(VI) from synthetic ground-water in the absence of bicarbonate, magnesium, and/or calcium ions. The presence of bicarbonate alone had the mildest impact on adsorption while co-presence with calcium had a pronounced negative impact. In comparison with unwashed Fe(0), the AW-Fe(O) displayed a poorer Cr(VI) removal capability [ 57% to 77% drop in capacity (53)]. 

Method 2. Transfer the dark-coloured reaction product to a separatory funnel and shake successively with water, with sufficient 5-10 per cent, sodium hydroxide solution to ensure that the washings are alkaline to litmus, and finally with water. Dry with anhydrous magnesium sulphate or calcium chloride. Filter through a fluted filter paper into a small distilling flask and distil slowly. Collect the crude bromobenzene at 150-170° pour the residue whilst still hot into a small porcelain basin. Redistil the hquid of b.p. 150-170° (3) and collect the bromobenzene at 154-157° the yield is about 60 g. 

Method 2. Ethyl p-nitrobenzoate. Place 21 g. of p-nitrobenzoic acid (Section IV,154), 11-5 g. of absolute ethyl alcohol, 3 8 g. of concentrated sulphuric acid, and 30 ml. of sodium-dried A.R. benzene in a 250 ml. round-bottomed flask, fit a reflux condenser, and heat the mixture under reflux for 16 hours. Add 50 ml. of ether to the cold reaction mixture, wash the extract successively with sodium bicarbonate soiution and water, dry with anhydrous magnesium sulphate or calcium chloride, and distil off the solvent on a water bath. Remove the last traces of benzene either by heating in an open evaporating dish on a water bath or in a bath at 100-110°. The residual ethyl p-nitrobenzoate (21 g.) solidifies completely on cooling and melts at 56°. 

Obtaining maximum performance from a seawater distillation unit requires minimising the detrimental effects of scale formation. The term scale describes deposits of calcium carbonate, magnesium hydroxide, or calcium sulfate that can form ia the brine heater and the heat-recovery condensers. The carbonates and the hydroxide are conventionally called alkaline scales, and the sulfate, nonalkaline scale. The presence of bicarbonate, carbonate, and hydroxide ions, the total concentration of which is referred to as the alkalinity of the seawater, leads to the alkaline scale formation. In seawater, the bicarbonate ions decompose to carbonate and hydroxide ions, giving most of the alkalinity. 

Seawater Distillation. The principal thermal processes used to recover drinking water from seawater include multistage flash distillation, multi-effect distillation, and vapor compression distillation. In these processes, seawater is heated, and the relatively pure distillate is collected. Scale deposits, usually calcium carbonate, magnesium hydroxide, or calcium sulfate, lessen efficiency of these units. Dispersants such as poly(maleic acid) (39,40) inhibit scale formation, or at least modify it to form an easily removed powder, thus maintaining cleaner, more efficient heat-transfer surfaces. 

Calcium, Magnesium and/or Sodium-Cation Exchanger (Insoluble) + Sulfuric Acid (Soluble) = Hydrogen Cation Exchanger (Insoluble) + Calcium, Magnesium and/or Sodium Sulfates (Soluble). 

The significance of conventional combinations arises largely in two classes of supply (ff) those in which the method indicates sodium bicarbonate to be present and ib) those similarly found to contain magnesium chloride or calcium chloride. 

Single or combination nonprescription antacid products, especially those containing magnesium hydroxide, aluminum hydroxide, and/or calcium carbonate, may provide sufficient relief from simple nausea or vomiting, primarily through gastric acid neutralization. 

The evolution of a lake or pond into dry land depends on the presence of nutrients in the water. The term nutrients refers to elements and compounds that are necessary for the growth of plants. Nutrients are commonly divided into two categories major nutrients and minor nutrients, also known as micronutrients. Despite some differences in the way that various elements and compounds are classified, carbon, nitrogen, and phosphorus are always regarded as major nutrients. Some authorities also list potassium, sulfur, calcium, magnesium, and/or iron as major nutrients. Micronutrients include aluminum, boron, chlorine, copper, manganese, molybdenum, silicon, and zinc. 

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