Calcium reservoir

In addition to the endoplasmic reticulum, the mitochondria also function as an intracellular calcium reservoir. The mitochondria also play an important role in programmed cell death —apoptosis (see p. 396). 

Menon, G.K., Grayson, S., and Elias, P.M., Ionic calcium reservoirs in mammalian epidermis ultrastructural localization by ion-capture cytochemistry, J. Invest. Dermatol. 84, 508-512,1985. 

Ronov (1976) estimated the average CaO content in sedimentary layer of 15.91 %, and in granite layer, of 2.71 %. Accordingly, the calcium reservoir in sedimentary shell is 272.8 X 10 - tons, and in the granite pool is 222.8 x lO tons. The weathering and metamorphosis of deep-layer silicates is accompanied by the formation of clay minerals with release of calcium available for plant and microbial uptake. 

Bone is the body s calcium reservoir. PTH stimulates bone resorption leading to the dissolution of hydroxyapatite and release of calcium and phosphate into the blood. This action of PTH appears to be the major mechanism for the rapid elevation of blood calcium levels. PTH also maintains blood calcium levels by promoting calcium reabsorption from the renal tubules. 

One example of a liquid-based ion-selective electrode is that for Ca +, which uses a porous plastic membrane saturated with di-(n-decyl) phosphate (Figure 11.13). As shown in Figure 11.14, the membrane is placed at the end of a nonconducting cylindrical tube and is in contact with two reservoirs. The outer reservoir contains di-(n-decyl) phosphate in di- -octylphenylphosphonate, which soaks into the porous membrane. The inner reservoir contains a standard aqueous solution of Ca + and a Ag/AgCl reference electrode. Calcium ion-selective electrodes are also available in which the di-(n-decyl) phosphate is immobilized in a polyvinyl chloride... 

Chlorine. Nearly all chlorine compounds are readily soluble in water. As a result, the major reservoir for this element in Figure 1 is the ocean (5). Chloride, as noted earHer, is naturally present at low levels in rain and snow, especially over and near the oceans. Widespread increases in chloride concentration in mnoff in much of the United States can be attributed to the extensive use of sodium chloride and calcium chloride for deicing of streets and highways. Ref. 19 points out the importance of the increased use of deicing salt as a cause of increased chloride concentrations in streams of the northeastern United States and the role of this factor in the chloride trends in Lake Ontario. Increases in chloride concentration also can occur as a result of disposal of sewage, oil field brines, and various kinds of industrial waste. Thus, chloride concentration trends also can be considered as an index of the alternation of streamwater chemistry by human development in the industrialized sections of the world. Although chlorine is an essential element for animal nutrition, it is of less importance for other life forms. 

Historically, bleaching powder and tropical bleach were significant sources of available chlorine but very Httle are used today. This is because of the greater availabiUty of sodium hypochlorite solutions and the development of calcium hypochlorite. They are stiU used to sanitize fields, drainage ditches, and reservoirs where its insoluble portion is not important. And, they are important sources of available chlorine within some less developed tropical countries. 

Wettability measurements show that most soil constituents are water wettable or hydrophilic,28 although calcium carbonates [calcite, CaC03, and dolomite, CaMg(C03)2] are slightly hydrophobic for example, the contact angle of water and heptane is 100 to 105°. Therefore, carbonaceous reservoirs are usually oil-wet. 

Adhesive force, non-Brownian particles, 549 Admicelle formation, 277 Adsorption flow rate, 514 mechanism, 646-647 on reservoir rocks, 224 patterns, on kaolinite, 231 process, kinetics, 487 reactions, nonporous surfaces, 646 surface area of sand, 251 surfactant on porous media, 510 Adsorption-desorption equilibria, dynamic, 279-239 Adsorption plateau, calcium concentration, 229... 

Bio-nanocomposites based on calcium phosphates can perform other innovative fundions such as acting as a reservoir for the controlled release of bioadive compounds once the material is implanted in the bone defect. For instance, the incorporation of a morphogenetic protein that promotes bone regeneration in an HAP-alginate-collagen system [110] or a vitamin in a Ca-deficient HAP-chitosan nanocomposite [111] are recent examples of this kind of application. 

Chapter 8 describes a similar one-dimensional chain of identical reservoirs, but one that contains several interacting species. The example illustrated here is the composition of the pore waters in carbonate sediments in which dissolution is occurring as a result of the oxidation of organic matter. I calculate the concentrations of total dissolved carbon and calcium ions and the isotope ratio as functions of depth in the sediments. I present... 

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