Nutrients Oxidant

Cells. We finally come to what are the direct building blocks of biological materials cells. Cells are assemblies of molecules enclosed within a plasma membrane that carry out specific functions. The human body contains over 10 " cells, all of which take in nutrients, oxidize fuels, and excrete waste products. Despite their varied functions, all cells have a similar internal organization. We will concentrate on this internal organization for now and will leave the topics of cell reproduction, energy production, and related concepts to the molecular biologist. 

Melanson, E.L., Sharp, T.A., Seagle, H.M. et al.. Effect of exercise intensity on 24-h energy expenditure and nutrient oxidation, J Appl Physiol, 92, 1045, 2002. Lamont, L.S., McCullough, A.J., and Kalhan, S.C., Gender differences in the regulation of amino acid metabolism, J Appl Physiol, 95, 1259, 2003. 

Tauson, A.-H., R. Pink and A. Chwalibog, 1997. Can gas exchange measurements be used for calculation of nutrient oxidation in mink (Musteal vison) exposed to short-term changes in energy supply Z. Emahrungswiss 36,317-320. 

If the mean urine pH of cats fed ad libitum is not below 6.4, the risk of stmvite uroHthiasis iucreases as the magnesium content of the diet iucreases. Because of very poor bioavailabiUty, iron from carbonate or oxide sources that are added to the diet should not be considered as components ia meeting the minimum nutrient level ia cats. 

In kaolin (clay) processing, sulfur dioxide reduces colored impurities, eg, iron compounds. In the bromine industry, sulfur dioxide is used as an antioxidant in spent brine to be reinjected underground. In agriculture, especially in California, sulfur dioxide is used to increase water penetration and the avadabiHty of soil nutrients by virtue of its abiHty to acidulate saline—alkaH soils (327). It is also usefiil for cleaning ferric and manganese oxide deposits from tile drains (328). 

Nitrate and Nitrite. Nitrate is usually present in trace quantities in surface waters but occasionally occurs in high concentrations in some groundwaters. If present in excessive amounts, it can contribute to the illness infant methemoglobinemia. Nitrate is an essential nutrient for many photosynthetic autotrophs. Nitrite is an intermediate in the reduction of nitrate as well as in the oxidation of ammonia it is also used as a corrosion inhibitor in some industrial processes. 

Potassium peroxymonosulfate, introduced in the late 1980s, is finding increasing use as an auxiUary oxidant for shock treatment and oxidation of chloramines. Sodium peroxydisulfate is also being sold for shock treatment, however, it is less reactive than peroxymonosulfate. Mixtures of sodium peroxydisulfate and calcium hypochlorite can be used for shock treatment (28). Disadvantages of peroxymonosulfate and peroxydisulfate are they do not provide a disinfectant residual and peroxymonosulfate oxidizes urea and chloramines to nitrate ion, which is a nutrient for algae. 

Nutrition. Zinc is essential to the proper functioning of plants and animals and, as zinc sulfate and oxide, it is used as a feed supplement (49—51) (see Mineral nutrients Feedsand feed additives). Most crops use less than a kilogram of zinc per 1000 m per year, so that zinc salts added at 1.3—4.5 kg/ha gradually build up the zinc reserve (52). Animals, including humans, store relatively Htde available zinc and, thus, require a constant supply in the diet. For instance, beef cattle require 10—30 mg/kg dry feed, dairy cattle 40 mg/kg, and breeding hens 65 mg/kg. Zinc from plants is considered less available to monogastric aminals than zinc from animal protein. 

Approximately 5% of the U.S. consumption of is in agriculture. Boron is a necessary trace nutrient for plants and is added in small quantities to a number of fertilizers. Borates are also used in crop sprays for fast rehef of boron deficiency. Borates, when apphed at relatively high concentration, act as nonselective herbicides. Small quantities of borates are used in the manufacture of alloys and refractories (qv). Molten borates readily dissolve other metal oxides usage as a flux in metallurgy is an important apphcation. Other important small volume apphcations for borates are in fire retardants for both plastics and ceUulosic materials, in hydrocarbon fuels for fungus control, and in automotive antifreeze for corrosion control (see Corrosion and corrosion inhibitors). Borates are used as neutron absorbers in nuclear reactors. Several borates, which are registered with the Environmental Protection Agency (EPA) can be used for insecticidal purposes, eg, TIM-BOR. 

Other Acids. Ascorbic acid (3) is used primarily as an antioxidant and to a lesser extent as an added nutrient ia beverages. It oxidizes readily, preventing the oxidation of certain flavoting compounds. Tartaric (4) and adipic acids are used to a lesser extent ia grape flavored beverages. Malic acid can be used as an alternative to citric acid ia some fmit flavored beverages. 

Copper is one of the twenty-seven elements known to be essential to humans (69—72) (see Mineral nutrients). The daily recommended requirement for humans is 2.5—5.0 mg (73). Copper is probably second only to iron as an oxidation catalyst and oxygen carrier in humans (74). It is present in many proteins, such as hemocyanin [9013-32-3] galactose oxidase [9028-79-9] ceruloplasmin [9031 -37-2] dopamine -hydroxylase, monoamine oxidase [9001-66-5] superoxide dismutase [9054-89-17, and phenolase (75,76). Copper aids in photosynthesis and other oxidative processes in plants. 

The common indices of the physical environment are temperature, pressure, shaft power input, impeller speed, foam level, gas flow rate, liquid feed rates, broth viscosity, turbidity, pH, oxidation-reduction potential, dissolved oxygen, and exit gas concentrations. A wide variety of chemical assays can be performed product concentration, nutrient concentration, and product precursor concentration are important. Indices of respiration were mentioned with regard to oxygen transfer and are particularly useful in tracking fermentation behavior. Computer control schemes for fermentation can focus on high productiv-... 

Transpiration is the movement of water from the root system up to the leaves and its subsequent evaporation to the atmosphere. This process moves nutrients throughout the plant and cools the plant. Respiration is a heat-producing process resulting from the oxidation of carbohydrates by O2 to form CO2 and H2O, as shown in Eq. (8-2). 

The catabolism of amino acids provides pyruvate, acetyl-CoA, oxaloacetate, fumarate, a-ketoglutarate, and succinate, ail of which may be oxidized by the TCA cycle. In this way, proteins may serve as excellent sources of nutrient energy, as seen in Chapter 26. 

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