Carbon reserves

Figure 4-491. Nonideal buffer characteristics of a 0.10 M carbonate reserve pit fluid [228].

It was expected that an eggshell thickness of scale would form, but that it would be relatively soft and easily removed (despite normally containing some silicate and sulfate). However, a disadvantage of this method of internal control was that the carbonate degraded to form carbon dioxide, and at higher pressures the rate of breakdown was so great that the necessary carbonate reserve required to prevent sulfate scale often could not be maintained. (Never mind the danger to the steam and condensate lines from the production of carbon dioxide and ultimately carbonic acid.)... 

If undesirable sulfate scale is to be avoided, a relatively high concentration of carbonate must be maintained as a BW reserve. The quantity of BW carbonate reserve required depends on the level of sulfates present in the BW and the boiler gauge pressure, as indicated in Table 10.2. 

Table 10.2 Carbonate-Cycle Program. BW Carbonate Reserve Requirements by Pressure and Sulfate Concentration...

Poly(hydroxyalkanoates) (PHAs), of which poly(hydroxybutyrate) (PHB) is the most common, can be accumulated by a large number of bacteria as energy and carbon reserve. Due to their bio degradability and bio compatibility these optically active biopolyesters may find industrial applications. A general overview of the physical and material properties of PHAs, alongside with accomplished applications and new developments in this field is presented in this chapter. 

Fareleira P, LeGall I, Xavier AV, Santos H. 1997. Pathways for utilization of carbon reserves in Desulfovibrio gigas under fermentative and respiratory conditions. I Bacteriol 179 3972-80. 

Santos H, Fareleira P, Xavier AV, et al. 1993. Aerobic metabolism of carbon reserves by the obligate anaerobe Desulfovibrio gigas. Biochem Biophys Res Commun 195 551-7. 

A somewhat similar constraint applies to the early development of sclerophylly, a potential herbivore deterring feature. Oonstructlon of rigid cell walls and the production of lignin and other compounds would certainly slow the overall rate of leaf expansion and prolong the period during which the leaf Is a net importer of carbon reserves. 

Carbon reserve in plants 550-681) GtC photosynthesis 50 GtC/yr carbon sequestration... 

Carbon reserves in the World Ocean surface 100 m layer 45 GtC carbon of living biomass 2 GtC photosynthesis 50 GtC/yr... 

On the Earth, the total amount of carbon sequestered in offshore and onshore hydrate deposits is believed to be larger than all other carbon sources combined. Fig. 7 shows the relative sizes of organic carbon reserves. Of the estimated 18,777 gigatons of carbon, 10,000 giga-tons are believed to be in the hydrate form. ... 

Fig. 7 Relative sizes of organic carbon reserves. (From ReF f) (View this art in color at www.dekker.com.)...

The comparison between the two chain pairs is also consistent with the physical properties. Paramylon and amylose are known for their gel forming properties and their carbon reserve function in p1 ants.(13,69) Although (l- -3)-3-D-glucan also plays a structural rFTe when it occurs in the cell walls of yeast( ), it is probably more of a matrix substance than anything else. The ability to form multiple helices probably accounts for unusual solubility phenomena such as retrogradation( ) and irreversible gel formation on heating. (13)... 

Gan HH, Wu SH, Fan XD (2003) Soil organic carbon reserves and characteristic of spatial distribution in Guangdong Province. Chin J Appl Ecol 14(9) 1499-1502 (in Chinese with English abstract)... 

Stachyose is the principal transport carbohydrate in the phloem of some herbaceons and woody plants [19,20], Raffinose and stachyose are fonnd in leguminous seeds such as soybean (Glycine max) and lupine (Lupinus spp.) where they prevent desiccation of seeds after maturity [21] and serve as carbon reserves for use during germination [22],... 

MAJOR APPLICATIONS In bacteria, PHB is a carbon reserve. The purified product is used as biodegradable packaging (bottles, containers, sheets, films, laminates, fibers, and coatings), especially as a copolymer of /3-hydroxybutyrate and /3-hydroxyvalerate. In biomedical applications, it is an excipient, a prosthetic material, etc. In organic syntheses, it provides chiral synthons. 

Numerous microorganisms synthesize PHAs by the fermentation of a carbon source and then accumulate them as intracellular carbon reserve inclusion bodies. In order to accumulate PHAs, in most bacteria an excess supply of carbon and limitation of nitrogen, phosphorus, oxygen or magnesium is required. These unfavourable growth conditions result in a decrease in cell growth and division, and a... 

The seeds of many plants contain fat as the major carbon reserve in some, such as those of castor bean, this is stored in the endosperm tissue surrounding the embryo, while in those of cucurbits and other plants it is stored in the cotyledons. Electron micrographs of the storage tissue show that the cells are almost completely occupied by spherosomes (membrane-bound vesicles of fat) and by protein bodies (e.g.. Vigil, 1970). 

The term PHA (Figure 9.1) is applied to a family of polyesters accumulated by various bacteria, deposited in the cells in the form of highly refractive granules of carbon reserve, energy and reducing equivalents. " In general, PHA synthesis by bacteria in a nutrient medium occurs when there is an excess of carbon source and a lack of one necessary nutrient at least (N, P, Mg, Fe etc.) for cell multiplication. ... 

PHB is accumulated by a large number of bacteria as an energy and carbon reserve. PHB is a biodegradable and biocompostable highly crystalline thermoplastic with very low water vapor permeability, similar to that of LDPE [105]. PLA/PHB blends have been studied with the goal of producing PLA-based materials with different physical properties and improved processability [106]. 

Marine diatoms are major contributors to coastal and oceanic primary productivity. Assimilation of nitrate, the predominant limiting nutrient, is usually tightly coupled to photosynthetic carbon fixation however, during darkness or periods of rapid nitrate assimilation, stored carbon reserves are respired for the energetic requirements of the cell and for protein synthesis (Turpin and Weger 1990). 

Initially world came to know about PHB by discovery of Maurice Lemoigne of the Pasteur Institute, Paris in 1925 while xtAyingBacillus megaterium (Lemoigne, 1925). When PHB was extracted from the bacteria it crystallizes to form a polymer with similar properties to polypropylene as shown in Table 2 and is a biodegradable substitute for thermoplastics. The PHB is accirmirlated as a carbon reserve imder nutrient limitation. 

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