2- Carbon fragment identity

The position of the double bond in the 2-hydroxyglycals has been verified in two instances by isolation of the five-carbon fragment resulting on oxidation with potassium permanganate in the presence of potassium carbonate. From 2,3,4,6-tetra-0-acetyl-(2-hydroxy-D-glucal) there was recovered potassium tri-O-acetyl-D-arabonate in 87.8% yield. Its identity was confirmed by conversion to the phenylhydrazide after deacetylation.1 Similarly, 2,3,4,6-tetra-0-acetyl-(2-hydroxy-D-galactal) was converted to potassium D-lyxonate, the identity of which was confirmed by conversion to the lactone.9... 

The pyrolytic gasification of biomass has been interpreted to involve the decomposition of carbohydrates by depolymerization and dehydration followed by steam-carbon and steam-carbon fragment reactions. So the chemistries of coal and biomass gasification are quite similar in terms of the steam-carbon chemistry and are essentially identical after a certain point is reached in the gasification process. Note, however, that biomass is much more reactive than most coals. Biomass contains more volatile matter than coal, and the pyrolytic chars from biomass are more reactive than pyrolytic coal chars. 

D, 2 or the two one-carbon fragments in type D,3, are identical .in these eases there are thus only two, not three, reagents. Actually all known syntheses pertaining to group D satisfy this condition. This requirement also explains why no example for a fourth imaginable51 type D,4, for the two imaginable four-component syntheses E,1 and... 

Reactions of transketolase (TK) and phosphoketolase (PK). The first half of the reactions of TK and PK are identical. TK catalyses the transfer of the 2-carbon fragment to an acceptor, whereas PK catalyses dehydration and subsequent nucleophilic attack of phosphate to produce acetyl phosphate. For the first reaction of TK in the pentose pathway, where donor, acceptor, products 1 and 2 are xylulose 5-phosphate, ribose 5-phosphate, glyceraldehyde 3-phosphate and sedoheptulose 7-phosphate, Ri = R2 = -CH0H-CH2-0P03. Pyr and PP represent 2,5-dimethyl-4-amino-pyrimidine and the ethyl diphosphate tail, respectively. 

DL-Norvaline-3-C on administration to rats or on incubation with rat liver homogenates yielded radioactive a-ketovaleric acid, butyric acid, acetic acid, acetoacetate, and 3-hydroxybutyric acid HI). These compounds were isolated by column cluomatography and their identity established. Degradation of the butyric acid demonstrated that only C-2 was significantly labeled. This established that the butyrate was formed by a direct pathway from norvaline and not by the subsequent condoisation of two-carbon fragments. 

The formation of acetoacetate in washed liver homogenates is consistent with the view that from 40% to 50% of the terminal 2 carbons of a fatty acid becomes identical in reactivity with the 2-carbon fragments derived from the rest of the molecule. Table VI gives the theoretical and observed values for R and Rt for 40% and 50% conversion of (CH3CO—)... 

The possibility that, in animal tissues, butyrate, or the terminal 4 carbons of a fatty acid of the even series, forms acetoacetate (1) by random condensation of identical 2-carbon fragments as well as (2) by a partial direct conversion to acetoacetate is no longer tenable if one accepts the findings with butyrate-l-C and butyrate-3-C (Table IV). If these were the only processes for the formation of acetoacetate, the C 0 C 00H ratios for these labeled butyrates should be exact reciprocals of one another. This, however, is not borne out by the data. In the opinion of the authors, however, a small conversion of the terminal 4 carbons (or butyrate) to acetoacetate directly cannot be ruled out even if we assume... 

It has been noted in a round robin test of microcomposites that there arc large variations in test results for an apparently identical fiber and matrix system between 13 different laboratories and testing methods (Pitkethly et al., 1993). Table 3.1 and Fig 3.15 summarize the IFSS values of Courtaulds XA (untreated and standard surface treated) carbon fibers embedded in an MY 750 epoxy resin. It is noted that the difference in the average ISS values between testing methods, inclusive of the fiber fragmentation test, fiber pull-out test, microdebond test and microindentation test, are as high as a factor of 2.7. The most significant variation in ISS is obtained in the fiber pull-out /microdebond tests for the fibers with prior surface treatments, and the microindentation test shows the least variation. 

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