Calcium affecting

These analyses are mainly performed on natural raw materials, notably on clay. The user of this clay is always interested in the mass percentage Fe, Ca and humus and in the mass percentage loam, fine sand and coarse sand. The contents of iron and calcium affect the baking colour and other contents are of influence on the properties of the mass as far as moulding and drying and firing behaviours are concerned. Furthermore we have learnt from the chapter on clay that this material may contain many more components which sometimes also need to be determined, for instance for environmental reasons. 

Bouwstra, J.A., et al. 1999. Cholesterol sulfate and calcium affect stratum corneum lipid organization over a wide temperature range. J Lipid Res 40 2303. 

One-dimensional transport through soils of calcium affected by equilibrium-controlled self-exchange is described by ... 

The viscosity of mucus is affected by binding between calcium and the mucus, which probably arises from an ionic interaction with the sialic acid in the mucin. These variations are indicated by a change in the pH, viscoelastic properties, water, and protein content of cervical mucus. Calcium is needed to establish an intercellular contact and the assembly of tight junction in the cervical epithelium. Changes in extracellular calcium affect the permeability of tight junctions and play a role in regulating the production of cervical mucus.Prostaglandin concentrations... 

Wedekind KJ, Titgemeyer EC, Twardock AR, et al. 1991. Phosphorus, but not calcium, affects manganese absorption and turnover in chicks. J Nutr 121 1776-1786. 

The commercial use of calcium ion in cucumber pickle products has stimulated efforts to better understand the mechanisms by which calcium affects cucumber texture. Recent results suggest that a high level of pectin methylation has little effect upon the ability of calcium to maintain the firmness of acidified cucumber tissue, while in fermented cucumbers maintenance of a minimum degree of methylation may be important to firmness retention. Efforts are being made to measure calcium binding characteristics in cucumber tissue and to obtain estimates of the effectiveness of calcium ion in inhibiting tissue degradation by pectolytic enzymes. 

Metallic sodium. This metal is employed for the drying of ethers and of saturated and aromatic hydrocarbons. The bulk of the water should first be removed from the liquid or solution by a preliminary drying with anhydrous calcium chloride or magnesium sulphate. Sodium is most effective in the form of fine wire, which is forced directly into the liquid by means of a sodium press (see under Ether, Section II,47,i) a large surface is thus presented to the liquid. It cannot be used for any compound with which it reacts or which is affected by alkalis or is easily subject to reduction (due to the hydrogen evolved during the dehydration), viz., alcohols, acids, esters, organic halides, ketones, aldehydes, and some amines. 

Minerals. Supplementation of macrominerals to mminants is sometimes necessary. Calcium and phosphoms are the minerals most often supplemented in mminant diets. One or both may be deficient, and the level of one affects the utilization of the other. Limestone, 36% calcium, is commonly used as a source of supplemental calcium. Dolomite, 22% calcium oyster sheUs, 35% calcium and gypsum, 29% calcium, are sources of calcium. Bone meal, 29% calcium, 14% phosphoms dicalcium phosphate, 25—28% calcium, 18—21% phosphoms and defluorinated rock phosphate, 32% calcium, 18% phosphoms, are sources of both calcium and phosphoms. Diammonium phosphate, 25% phosphoms phosphoric acid, 32% phosphoms sodium phosphate, 22% phosphoms and sodium tripolyphosphate, 31% phosphoms, are additional sources of phosphoms (5). 

Normally, a slight excess of sulfuric acid is used to bring the reaction to completion. There are, of course, many side reactions involving siHca and other impurity minerals in the rock. Fluorine—silica reactions are especially important as these affect the nature of the calcium sulfate by-product and of fluorine recovery methods. Thermodynamic and kinetic details of the chemistry have been described (34). 

Precautions in Handling. Ammonium bifluoride, like all soluble fluorides, is toxic if taken internally. Hydrofluoric acid bums may occur if the material comes in contact with moist skin. Ammonium bifluoride solutions should be thoroughly washed from the skin with mildly alkaline soap as soon as possible however, if contact has been prolonged, the affected areas should be soaked with 0.13% solution of Zephiran chloride, or 0.2% Hyamine 1622 (Lonza, Inc.) or calcium gluconate, the treatment recommended for hydrofluoric acid bums. If any of these solutions come in contact with the eyes, they should be washed with water for at least 10 min and a physician should be consulted. 

Calcium C rbon te. Calcium carbonate, like R2O2, affects sulfuric and oleum consumption in the HF process. Sulfuric acid loss is approximately 0.98% H2SO4 for each percentage of CaCO. The carbon dioxide evolved by the reaction increases the noncondensable gas flow, and because it carries HF, contributes to yield losses in the vent stream. 

Propionates. Propionic acid [79-09-4], C2H 02, and its calcium and sodium salts ate effective mold inhibitors. They ate particularly useful in yeast-leavened baked products because they do not affect the activity of yeast. In addition to being widely used in baked goods, they ate used as mold inhibitors in cheese foods and spreads (77). 

Because of this soHd solution, natural magnesite contains varying amounts of iron which can affect the ultimate use of the material. Small amounts of calcium and manganese may also be present. 

Magnesium. In the adult human, 50—70% of the magnesium is in the bones associated with calcium and phosphoms. The rest is widely distributed in the soft tissues and body duids. Most of the nonbone Mg ", like K", is located in the intracellular duid where it is the most abundant divalent cation. Magnesium ion is efftcientiy retained by the kidney when the plasma concentration of Mg fads in this respect it resembles Na". The functions of Na", K", Mg ", and Ca " are interrelated so that a deficiencv of Mg " affects the metaboHsm of the other three ions (26). Foods rich in magnesium are listed in Table 9. 

Dihydroxyvitamin (283) is the endogenous ligand for the vitamin receptor (VDR). It modulates genomic function in a tissue and developmentaHy specific manner and affects ceU proliferation, differentiation, and mineral homeostasis (74). Vitamin mobilizes calcium from the bone to maintain plasma Ca " levels. Vitamin and VDR are present in the CNS where they may play a role in regulating Ca " homeostasis. Vitamin D has potent immunomodulatory activity in vivo. 

Plants can also be pests that need to be controlled, particulady noxious weeds infesting food crops. Prior to 1900, inorganic compounds such as sulfuric acid, copper nitrate, sodium nitrate, ammonium sulfate, and potassium salts were used to selectively control mustards and other broadleaved weeds in cereal grains. By the early 1900s, Kainite and calcium cyanamid were also used in monocotyledenous crops, as well as iron sulfate, copper sulfate, and sodium arsenate. Prom 1915 to 1925, acid arsenical sprays, carbon bisulfate, sodium chlorate, and others were introduced for weed control use. Total or nonselective herbicides kill all vegetation, whereas selective compounds control weeds without adversely affecting the growth of the crop (see Herbicides). 

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