Carbon dioxide during conversion

Because not all amino acids are glucogenic, and because entry of carbon-skeleton metabolites into the Krebs cycle results in the release of carbon atoms as carbon dioxide during conversion to phosphoenolpyruvate, greater than 3 g of protein is required to make 1 g of glucose. 

The deprotection of carbobenzyloxy protected phenylalanine was carried out in a low-pressure test unit (V= 200 ml) equipped with a stirrer, hydrogen inlet and gas outlet. The gas outlet was attached to a Non Dispersive InfraRed (NDIR) detector to measure the carbon dioxide. During the reaction the temperature was kept at 25 °C at a constant agitation speed of 2000 rpm. In a typical reaction run, 10 mmol of Cbz protected phenylalanine and 200 mg of 5%Pd/C catalyst were stirred in a mixture of 70 ml ethanol/water (1 1). The Cbz protected phenylalanine is not water-soluble but is quite soluble in alcoholic solvents conversely, the water-soluble deprotected phenylalanine is not very soluble in alcoholic solvents. Thus, the two solvent mixture was used in order to keep the entire reaction in the solution phase. Twenty p.1 of the corresponding modifier was added to the reaction mixture, and hydrogen feed was started. The hydrogen flow into the reactor was kept constant at 500 ml/minute and the progress of the reaction was monitored by the infrared detection of C02 in the off-gas. 

Tyj"alo—lactic fermentation can be defined as the bacterial conversion of L-malic acid to L-lactic acid and carbon dioxide during storage of new wine. Malic acid is dicarboxylic, but lactic acid is monocarboxylic therefore, the net result of malo-lactic fermentation in wine, aside from the production of carbon dioxide, is a loss in total acidity. In commercial practice, this fermentation is not well understood, and better methods of controlling it are sought. 

In guinea pigs there is considerable conversion of ascorbic acid to respiratory carbon dioxide (3,37). Further, the entire carbon chain of ascorbic acid is subjected to extensive oxidation to carbon dioxide (3,21), Following injection of (1- C)ascorbic acid, 66% of the label was recovered as ( C)carbon dioxide during 10 d up to 30-40% of the dose was catabolized to carbon dioxide during the first 24 h (20). Our data indicate that in a time period of 216 h about 65% of the oral dose of (1- C)ascorbic acid is exhaled as labeled carbon dioxide (Table I). The maximum rate of excretion occurred at 0.5 h (Figure 6), and we derived from this radioactivity-time curve that within the first 12 h about 30% of the label was exhaled (36% after 24 h). 

Radioactive acetyl CoA can be generated by direct synthesis from C-acetate or from (3 oxidation of radioactive fatty acids, such as uniformly labeled palmitate. Examination of the reactions of the citric acid cycle reveals that neither of the two carbons that enter citrate horn acetate is removed as carbon dioxide during the first pass through the cycle. Labeled carbon from C-methyl-labeled acetate appears in C-2 and C-3 of oxaloacetate, because succinate is symmetrical, with either methylene carbon in that molecule labeling C-2 or C-3 of oxaloacetate. The conversion of oxaloacetate to phosphoenolpyruvate yields PEP labeled at C-2 or C-3 as well. Formation of glyceraldehyde 3-phosphate and its isomer dihydroxyacetone phosphate gives molecules, both labeled at carbons 2 and... 

Under UV light, all forms of titania oxidize propane to carbon dioxide. The conversion was followed by periodical illumination with dark periods of 5 min during which propane was found to be the only weakly adsorbed in the dark. Analysis of the carbon mass balance (Figure 4.2) obtained by online MS indicates the formation and accumulation of intermediate reaction products at the catalyst surface whose concentration increases with reaction time in the order anatase > rutile >= mixed anatase/rutile > P25. Taking into account the specific surface areas, the turn over number (TON) increases in the order anatase (9) rutile (15) P25 (112). The activity of titania P25 is higher by a factor of 10 compared to rutile, anatase, or their physical mixture. 

A Buffer Agent.—Cell membranes are more or less permeable to the Cl-ion, but relatively impermeable to the metallic ions that accompany it. Potassium is located chiefly in cells sodium is found chiefly in tissue fluids. The Cl-ion is able to migrate between cell and surrounding fluid in response to changes in K+ or Na+ concentration. This chloride shift occurs in blood when increase in carbonate concentration drives chlorine from plasma to red cell, or vice-versa. Conversely, removal of carbon dioxide during pulmonary aeration causes chlorine to pass from the red cells to the plasma. 

The rate of decomposition in unmanaged landfills, as measured by gas production, reaches a peak within the first 2 years and then slowly tapers off, continuing in many cases for periods up to 25 years or more. The total volume of the gases released during anaerobic decomposition can be estimated in a number of ways. If all the organic constituents in the wastes (with the exception of plastics, rubber, and leather) are represented with a generahzed formula of the form QH O N, the total volume of gas can be estimated by using Eq. (25-27) with the assumption of completed conversion to carbon dioxide and methane. 

The time necessary for completion of the reaction may vary from 0.5 to 4 hours, depending on the actual activity of the alumina. The progress of conversion should be monitored by infrared analysis of a concentrated sample of the solution. Stirring should be continued for 15 minutes after the nitroso band at 1540 cm. has disappeared. A strong diazo band at about 2100 cm. will then be present. The carbonyl band at 1750 cm. initially due to nitrosocarbamate, will usually not disappear completely during the reaction, because some diethyl carbonate is formed in addition to carbon dioxide and ethanol. Diethyl carbonate is removed during the work-up procedure. 

The process will adversely affect air quality by releasing nitrogen oxides, sulfur oxides, carbon monoxides and other particulates into the atmosphere. Better control of the conversion conditions and better control of emissions can make the process cleaner, yet technology cannot do anything to curb carbon emissions. Since much of the carbon in coal is converted to carbon dioxide in the synthesis process, and is not part of the synthetic fuel itself, the amount of carbon dioxide that will be released to the environment during combustion is 50 to 100 percent more than coal, and around three times more than natural gas. 

Mechanisms depending on carbanionic propagating centers for these polymerizations are indicated by various pieces of evidence (1) the nature of the catalysts which are effective, (2) the intense colors that often develop during polymerization, (3) the prompt cessation of sodium-catalyzed polymerization upon the introduction of carbon dioxide and the failure of -butylcatechol to cause inhibition, (4) the conversion of triphenylmethane to triphenylmethylsodium in the zone of polymerization of isoprene under the influence of metallic sodium, (5) the structures of the diene polymers obtained (see Chap. VI), which differ. both from the radical and the cationic polymers, and (6)... 

GP 2[ [R 3a[ Catalysts need to be initially activated on-stream with a mixture of 20% ethylene and 20% oxygen in methane as balance [44], The temperature was raised until first formation of carbon dioxide became notable. The initial selectivity is close to 70% and after time-in-stream for 1 day at 250 °C decreases to 62% at 1.3% conversion. This loss in selectivity at the expense of conversion is a general phenomenon during all investigations conducted in [44], Non-promo ted catalysts show a certain decrease in selectivity within a few days, particularly at high temperature and conversion. 

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