Alkalinity biological production

Cai, M., Liu, J., and Wei, Y. 2004. Enhanced biological production from sewage sludge with alkaline pretreatment. Environ. Sci. Technol.,38,3195-3202. 

The dynamic model presented herein builds on that reported previously (I) by incorporating the interactions between volatile acids, pH, alkalinity, gas production rate, and gas composition. The model is developed from material balances on the biological, liquid, and gas phases of a continuous-flow, complete mixing reactor. Appropriate relationships such as yield constants, an inhibition function, Henry s law, charge balances, and ionization equilibria are used to express the interactions between variables. The inputs and outputs for the reactor and the reactions considered are illustrated in Figure 2. 

Chitosan is a second abundant heteropolysaccharide composed of /3-[l-4]-2-deoxy-2-amino and -2-acetamino D-glucopyranose units [31]. Chitosan is the partial deacetylated (involving alkaline hydrolysis] product of chitin. Chltln is the main component of outer skeleton of small insects, cuticles, and the shells of shrimp, crab, lobster, etc. Chitosan has been expansively investigated in the pharmaceutical industries for the development of various sustained and controlled release drug delivery systems due to its versatile biological activity [as food and non-food items] and excellent biocompatibility. Hirano [22] conducted an experiment with both healthy and infected skin and found the LD50 in case of orally administered mouse to be [>16 g/kg]. Wu et al. [76] worked on... 

Lactulose (P-Gal/>-(l—>4)-Fru is a semi-synthetic disaccharide composed of fructose and galactose resulting from the alkaline isomerization of lactose. This disaccharide is present in significant concentrations in some food products since the isomerization can occur naturally, as for example, during heat treatment of milk (Barreteau et al., 2006). However, the isomerization reaction has several drawbacks, and the steps required for the separation and purification of these products presents high costs and results in low yields of lactulose. Several studies have investigated viability of biological production of lactulose by enzymes (Kimetal., 2005). 

Carboxyhc acid ester, carbamate, organophosphate, and urea hydrolysis are important acid/base-catalyzed reactions. Typically, pesticides that are susceptible to chemical hydrolysis are also susceptible to biological hydrolysis the products of chemical vs biological hydrolysis are generally identical (see eqs. 8, 11, 13, and 14). Consequentiy, the two types of reactions can only be distinguished based on sterile controls or kinetic studies. As a general rule, carboxyhc acid esters, carbamates, and organophosphates are more susceptible to alkaline hydrolysis (24), whereas sulfonylureas are more susceptible to acid hydrolysis (25). 

With the development of HPLC, a new dimension was added to the tools available for the study of natural products. HPLC is ideally suited to the analysis of non-volatile, sensitive compounds frequently found in biological systems. Unlike other available separation techniques such as TLC and electrophoresis, HPLC methods provide both qualitative and quantitative data and can be easily automated. The basis for the HPLC method for the PSP toxins was established in the late 1970 s when Buckley et al. (2) reported the post-column derivatization of the PSP toxins based on an alkaline oxidation reaction described by Bates and Rapoport (3). Based on this foundation, a series of investigations were conducted to develop a rapid, efficient HPLC method to detect the multiple toxins involved in PSP. Originally, a variety of silica-based, bonded stationary phases were utilized with a low-pressure post-column reaction system (PCRS) (4,5), Later, with improvements in toxin separation mechanisms and the utilization of a high efficiency PCRS, a... 

Isolation of the feeding factor for M. sexta was a far more difficult task. Whereas 2-tridecanone is a simple, stable molecule soluble in organic solvents, the feeding factor is water soluble, occurs at trace levels in plant tissue, and is easily hydrolyzed under mild alkaline or acidic conditions with subsequent loss of biological activity. The isolation of such a compound was a formidable obstacle requiring a departure from the more classical approach of hydrolysis or chemical derivatization followed by isolation of the lipophilic product. The necessity that pure substance be isolated with retention of biological activity required some basic research in modem separation techniques to develop a suitably mild isolation strategy. 

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