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Medium Design for Cell Culture Processing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
It should be noted that CO2 is also an essential nutrient for cell growth. It is a substrate in many biochemical carboxylation reactions. Normally, the demand for CO2 is met by its production in cell metabolism. If cells are cultured in a bicarbonate-free medium and the ambient air is aerated vigorously through the medium to strip off the CO2 produced by the metabolism, one may see cell growth inhibition until the aeration is stopped, thus allowing the CO2 produced in the metabolism to accumulate. When a sodium bicarbonate-free medium is used to grow cells, it is common practice to maintain the CO2 in the gas phase at 0.2–0.5%. Many media have low concentrations of sodium bicarbonate and HEPES to provide a neutral pH at the beginning of a cell culture process. The low level of bicarbonate provides the CO2 required for cell growth.
Hazardous Organic Waste Amenable to Biological Treatment
Published in Daphne L. Stoner, Biotechnology for the Treatment of Hazardous Waste, 2017
Of interest is the anaerobic oxidation of aromatic compounds by an iron-reducing bacterium.40,41 The bacterium, designated GS-15, was able to utilize toluene, phenol, or p-cresol as the sole carbon source with Fe(III) as the terminal electron acceptor. Because of the transient accumulation of p-hydroxybenzoate during growth on phenol or p-cresol, the initial step in the metabolism of phenol was suggested to be a carboxylation step. A carboxylation step was also postulated for the anaerobic degradation of phenol by denitrifying pseudomonads.46 The metabolism of p-hydroxybenzylalcohol and p-hydroxybenzaldehyde by GS-15 suggests that these compounds are intermediates in the metabolism of p-cresol.
Vitamins and Nutrition
Published in Richard J. Sundberg, The Chemical Century, 2017
Biotin, sometimes called vitamin B7 or H, is present in most foods, but in very small amounts. The richest natural sources are “royal jelly,” which is produced by honeybees and induces the reproductive ability of queen bees, and brewer’s yeast. Milk, liver, and egg yolks are the most important sources in the human diet. Another likely source is absorption in the gut of biotin produced by microorganisms. Biotin is strongly bound by avidin, a protein found in egg white, and biotin deficiency can be produced by use of avidin to remove biotin. Biotin is sensitive to oxidation and its level is reduced by many types of food processing. Biotin is a coenzyme for a family of enzymes that catalyze carboxylation, decarboxylation, and transcarboxylation. One of these enzymes, pyruvate carboxylase, is critical in carbohydrate biosynthesis.
Different scenarios of glycerin conversion to combustible products and their effects on compression ignition engine as fuel additive: a review
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Farid Haghighat Shoar, Bahman Najafi, Shahab S. Band, Kwok-Wing Chau, Amir Mosavi
Different studies on the carboxylation reaction for glycerol carbonate were performed (Alvarez et al., 2012; Alvarez et al., 2012; Das & Mohanty, 2019; dos Santos et al., 2019; Elhaj et al., 2019; Gao et al., 2015; Goncalves et al., 2015; Gonzalez-Arellano et al., 2015; Lertlukkanasuk et al., 2013; Li & Wang, 2011; Sangkhum et al., 2019; Wang et al., 2017; Zhang et al., 2010; Zheng et al., 2015) (Table 7). The carboxylation reaction results in the production of glycerol carbonate, which is used as a solvent for plastics and resins, for example, cellulose acetate, nitro-cellulose, and poly-acrylonitrile. Besides, this compound has the adhering property to metal surfaces and resistant to oxidation, hydrolysis, and pressure, and has a lubricating effect. According to the results of the above table, various studies have been carried out to produce glycerol carbonate. Among them, Wang et al. (2017) reported the highest amount of glycerol carbonate production. The Na2SiO3 solid base catalyst at 200°C was a noteworthy example for industrial applications in GC synthesis that illustrated glycerol conversion of 97.7%. This comparison is expressed based on the highest amount of glycerol carbonate production efficiency.
Emulsifier-free emulsion polymerization of acrylonitrile-butadiene-carboxylic acid monomers: a kinetic study based on polymerization pressure profile
Published in Journal of Dispersion Science and Technology, 2020
Ali Safinejad, Saeed Pourmahdian, Behzad Shirkavand Hadavand
The monomers used in conventional emulsion polymerization systems (e.g., styrene and butadiene) are usually water-insoluble or have low solubility in water. In these systems, the primary reaction locus is inside the particles and the polymerization in the aqueous phase is ignorable. However, many industrial processes usually use one or more functional monomers with significant water solubilities such as acrylic acid and methacrylic acid.[1,2] These products are called carboxylated latexes, in which carboxylic groups are distributed between aqueous phase, buried inside the polymer particles, or located on the surface of the particles.[3] The most industrially-important rubber latexes of this type are the carboxylated styrene-butadiene rubber latexes. Also of considerable interest are carboxylated acrylonitrile-butadiene rubber latexes and carboxylated polychloroprene rubber latexes. The advantages of carboxylation which accrue to the polymer present in the latex include susceptibility to reaction with additional reagents, improved adhesion to polar substrates (such as textile fibers, paper fibers, and metals), enhanced polymer tensile strength, and to a lesser extent, improved resistance to swelling in hydrocarbon oils.[4] Adsorbed groups on the surface of the particles enhance the stability of the particles by steric and electrostatic mechanisms.[5] The kinetics of these systems does not follow the conventional ones. The presence of carboxylic monomers has a profound effect on the polymerization kinetics because they are present to a significant extent in the aqueous phase and strongly modify key aspects such as the rates of radical entry and exit and particle nucleation.[6]
Carbon capture and utilization technologies: a literature review and recent advances
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Francisco M. Baena-Moreno, Mónica Rodríguez-Galán, Fernando Vega, Bernabé Alonso-Fariñas, Luis F. Vilches Arenas, Benito Navarrete
It is concluded that the use of CO2 in carboxylation processes is interesting to meet the economic and environmental requirements, and provides an alternative to traditional CO2 coupling reactions that require organometallic reagents, with a great future of electrocarboxylation, and especially, that is free of sacrificial anodes (Luo and Larrosa 2017; Senboku and Katayama 2017).