Direct removal

We consider first Cycles A of Table 8.1 A and the a.ssociated Figs. 8.6-8.8. These are cycles in which the major objective is to separate or sequestrate some or all of the carbon dioxide produced, and to store or dispose it. This can be achieved either by direct removal of the CO2 from the combustion ga.ses with little or no modification to the existing plant or by modest restructuring or alteration of the conventional power cycle so that the carbon dioxide can be removed more easily. 

Fig. 8.6. Cycle A1. Direct removal of CO2 from an existing plant (after Chiesa and Consonni 111).

In cycle D4 [15, since the fuel is burnt with pure oxygen, the exhaust gases contain CO2 and H2O almost exclusively (Fig. 8.21). Cooling the exhaust below the dew point enables the water to condense and the resulting CO2 stream is obtained without the need for chemical absorption. The exjjensive auxiliary plant involved in direct removal of the CO2 is not needed, but of course there is now the additional expense of an air separation plant to provide the pure oxygen for combustion. 

Bohlmann and Rahtz, in 1957, reported the preparation of 2,3,6-trisubstituted pyridines. Their method employed the Michael addition of acetylenic ketones 35 with enamines 36. The 5-aminoketones 37 are typically isolated and subsequently heated at temperatures greater than 120°C to facilitate the cyclodehydration to afford 38. Again one can see the parallels in this mechanism with that for the Hantzsch protocol. However, in this case the pyridine is formed directly removing the need for the oxidation step in the Hantzsch procedure. 

Similar to the active perimeter gas control system, an active interior gas collection/recovery system consists of gas extraction wells, gas collection headers, vacuum blowers or compressors, and a treatment system. However, it is used to directly remove the hazardous gases from the site (beneath a landfill), instead of off-site removal. Figure 16.9 shows a schematic view of such a system. 

Most methods depend upon the direct removal of water from oxalic acid crystals by the application of heat.2 The weakness of this lies chiefly in a lack of standardization. 

Birch has made good use of oxidative decarboxylation in hydrofuroic acids (Section VI,B,2) but otherwise the direct removal of hydrogen from a hydrofuran is usually regarded as impracticable, and while the dismutation catalyzed by palladium on alumina at 180 C is interesting, it depends too much upon the substitution pattern to be sufficiently general18 ... 

Carbamate substituents have also been found to permit the direct removal of allylic, propargylic and allenic protons by organolithium reagents [32, 33]. In the latter case, the resulting lithioallenes can be converted to the allenyltitanium reagents with ClTi(OiPr)3 (Eq. 9.28) [8]. As illustrated, subsequent addition to acetaldehyde proceeds with only modest diastereoselectivity. 

Antipyrine Uptake and Elimination by Mussels Directly Removed or Laboratory Cultured. 

Haraguchi, M., Yamashiro, S., Fumkawa, K., Takamiya, K., and Shiku, H., 1995, The effects of the site-directed removal of N-glycosylation sites from beta-1,4-N-acetylgalactosaminyltransferase on its function. Biochem J 312 273-280. 

A direct removal of image Fourier coefficients from a reconstructed electron exit wave seems a most suitable way for resolution verification. Here, Figure 2 shows for the first time the contribution of Si (444) image Fourier coefficients to the separation of the 0.78A dumbbell distance in Si [112] in the phase of an electron exit wave. The focal series was recorded at Lichte defocus with the 0AM and reconstructed in 2001. 

Kulprathipanja, S. and Spehlmann, B.C. (2001) Direct removal of trace ionic iodide from acetic add. Proceedings of the 13th International Zeolite Conference, Montpellier, France, 8-13 )uly. 

MBD2b a truncated version of MBD2a (translation stars at a second methionine codon in MBD2a) that lacks the (GR)n domain was reported to have demethylase activity with direct removal of the methyl group expressed in somatic tissues but not ES cells... 

Demet X procedure simply consists of an oxidation at elevated temperature, both the New Demet and the Demet III process has a sulfiding step which transforms the metal oxides to insoluble sulfides. In Demet III the sulfiding step is followed by a partial oxidation step. This oxidation is carefully controlled to produce metal sulfates and sulfides which can be directly removed by washing or be transferred into soluble compounds by the reductive and oxidative washes used in this procedure. In the New Demet process the sulfiding step is followed by chlorination which results in a transformation of the sulfides into washable chlorides. Since vanadium chlorides are volatile, most of the vanadium removal using this procedure occurs in the gas phase. In the Demet X procedure, the vanadium oxides formed are water soluble or can be transformed into water soluble forms by aqueous treatments. In contrast the nickel oxides are insoluble in water. 

Flow diagram for the extraction of an organic base. (1) Direct removal of neutral and acidic excipients. (2) Acidic excipients left behind in aqueous layer. (3) Neutral excipients left behind in organic layer. 

Reports in the literature that isolate any of these processes are rare and often require unusual conditions. For example, in addition to the oxazoI-5(4//)-one studies described above, Kemp and Rebek[27l were able to use kinetic isotope effects to distinguish the enolization mechanism from oxazol-5(4//)-one formation in a simple peptide coupling experiment. a-2H-Labeled Bz-L-Leu-OH and Z-Gly-Phe-OH were prepared and coupling reactions to H-Gly-OEt were carried out. In cases where oxazol-5(4//)-one formation is rate-determining, such as with Bz- L-Leu-OH, the isotope effect kHlkD is equal to 1 because the a-proton is not removed until after this rate-determining step. In contrast, enolization requires the direct removal of the a-proton, and the isotope effect measured for this mechanism was as high as 2.9 with Z-Gly-Phe-OH. Therefore, a measurement of the isotope... 

The plausible deoxygenation routes for production of diesel like hydrocarbons from fatty acids and their derivates are decarboxylation, decarbonylation, hydrogenation and decarbonylation/hydrogenation. The main focus in this study is put on liquid phase decarboxylation and decarbonylation reactions, as depicted in Figure 1. Decarboxylation is carried out via direct removal of the carboxyl group yielding carbon dioxide and a linear paraffinic hydrocarbon, while the decarbonylation reaction yields carbon monoxide, water and a linear olefinic hydrocarbon. 

In this formula, most herbs enter the Lung meridian, have descending properties and can directly remove phlegm-heat from the Lung. 

Ju Hong and Jie Gen can directly remove phlegm and stop cough. 

Product formation in both cases results from deprotonative transformation of the a complex [Eq. (10.10)]. At very high sulfuric acid concentrations (>95%) the product sulfonic acid may be formed by the direct removal of the aromatic ring proton93 [Eq. (10.11)] ... 

Differences between 5 - 3 and 3 - 5 exonucleases The 5 - 3 exonuclease activity of DNA polymerase I differs from the 3 - 5 exonuclease used by both DNA polymerase I and III in two important ways. First, 5 3 exonuclease can remove one nucleotide at a time from a region of DNA that is properly base-paired. The nucleotides it removes can be either ribonucleotides or deoxyribonucleotides. Second, 5 —>3 exonuclease can also remove groups of altered nucleotides in the 5 —>3 direction, removing from one to ten nucleotides at a time. This ability is important in the repair of some types of damaged DNA. 

---