Antartica

Kanerva et al. have also reported DKR of cyanohydrins [47]. In particular, they obtained very good results with C. antartica lipase A (CAL-A) as the catalyst for the KR of a variety of substrates for which other enzymes such as CALB or PS-C do not give good results (Figure 4.22) [47a[. 

Deep water also forms along the margins of Antartica and feeds the Circumpolar Current. The Weddell Sea, because of its very low temperature, is the main source of Antarctic Bottom Water (AABW) which flows northward at the very bottom into the South Atlantic, and then through the Verna Channel in the Rio Grande Rise into the North Atlantic. It ultimately returns southward as part of the NADW. 

Chemo-enzymatic epoxidation of unsaturated fatty acids with aqueous H2O2 has been conducted with considerable success and here we have a remarkable situation that undesirable ring opening of the epoxide does not occur. Excellent activity and stability has been realized with Novozym 435, a Candida antartica lipase B immobilized on polyacryl. This enzyme is readily separable, can be used several times without loss of activity, and has a turnover of more than 2,00,000 moles of products per mole of catalyst (Bierman et al., 2000). 

Reagan MK, Volpe AM, Cashman KV (1992) and Th-series chronology of phonolite fractionation at Mount Erebus, Antartica. Geochim Cosmochim Acta 56 1401-1407 Reagan MK, Morris JD, Herrstrom EA, Murrell MT. (1994) Uranium series and beryllium isotope evidence for an extended history of subduction modification of the mantle below Nicaragua. Geochim Cosmochim Acta 58 4199-4212... 

However, groupings of soils can be and are made for all soils on this planet, and all soil types can be found on all continents except Antartica. Ultisols, Mollisols, Alfisols, and Spodosols, and other soil types occur in North and South America, Asia, Europe, and Africa, Australia, and New Zealand. Thus, researchers and analysts all over the world need to know about soils, soil types, and their nomenclature. 

El adelgazamiento de la capa de ozono sobre la Antartica se conoce como el agujero de ozono. 

Photograph Kindly provided by Dr. Mike Stroud, University of Southampton. It is Dr. Stroud who is surrounded by the Emperor Penguins in Antartica. 

Uchida, T. Hondoh, T. Mae, S. Lipenkov, V.Y. Duval, P. (1994). Air-hydrate crystals in deep ice-core samples from Vostok Station Antartica. J. Glaciology, 40 (134), 79-88. 

Webby, R. and Markham, K.R., Isoswertiajaponin 2"-0- 3-arabinopyranoside and other flavone-C-glycosides from the Antartic grass Deschampsia antartica, Phytochemistry, 36, 1323, 1994. 

Figure 14.13 shows C02 concentrations measured in ice cores at the Byrd Station in Antartica from 5000 years before the present (bp) to 40,000 years bp (Anklin et al., 1997). The use of ice core data for elucidating atmospheric composition is discussed by Delmas (1992) and in more detail in Section E.l. As seen in Fig. 14.13, atmospheric C02 concentrations about 5000 years ago were only 280 ppm. (Note that interpretation of such ice core data must be carried out with care since there is evidence that in some cases, C02 can be produced in the ice from decomposition of carbonate e.g., see Smith et al., 1997.)... 

De Diego, T., Lozano, R, Gmouh, S., Vaultier, M., Iborra, J.L., Understanding structure-stability relationships of Candida antartica lipase B in ionic liquids, Biomacromol., 6,1457-1464, 2005. 

CA, Candida antartica CR, Candida rugosa DKR, dynamic kinetic resolution DOIS, 2-deoxy-cyllo-inosose synthase LDH, lactate dehydrogenase THF, tetrahydrofuran. 

The DKR hydrolysis of thioesters described previously has also been extended to transesterifications in toluene, using triethylamine and Candida antartica lipase.28 This general approach can therefore be applied to the resolution of a wide range of both water-soluble and water-insoluble thioesters by selecting an appropriate solvent, base, and enzyme system. 

To achieve better results a series of lipases was screened using the Chirazyme screening kit and analysis by gas chromatography with a chiral stationary phase. Candida antartica Lipase B, available as Novozyme 435, was chosen for further development with the acyl transfer agent vinyl propionate. 

MFI ZSM-5 Mutinaite Na3Ca4Si85AliiOi92. 6OH2O Mount Adamson Antartica... 

NES NU-87 Gottardiite Na3Mg3Ca5Sij 17AI19O272 93H20 Moimt Adamson Antartica... 

Candida antartica lipase B Na2C03 (1 mmol) AcOCMe=CH2 (1.5 mmol) toluene, 25 °C... 

Zipfel J. and Worner G. (1992) Thermobarometry on four- and five-phase periodotites from a continental rift system evidence for upper mantle uphft and coohng at the Ross Sea margin (Antartica). Contrib. Mineral. Petrol. Ill, 24-36. 

Lyons W. B., Welch K. A., and Sharma P. (1998) Chlorine-36 in the waters of McMurdo Dry valley lakes, southern Victoria land Antartica revisited. Geochim. Cosmochim. Acta 62, 185-192. 

Recent studies have attempted to improve the efficiency of epoxidation under milder conditions that minimize the formation of byproducts. Chemo-enzymatic epoxidation uses the immobilized lipase from Candida antartica (Novozym 435) (56) to catalyze conversion of fatty acids to peracids with 60% hydrogen peroxide. The fatty acid is then self-epoxidized in an intermolecular reaction. The lipase is remarkably stable under the reaction conditions and can be recovered and reused 15 times without loss of activity. Competitive lipolysis of triacylglycerols is inhibited by small amounts of fatty acid, allowing the reaction to be carried out on intact oils (57). Rapeseed oil with 5% of rapeseed fatty acids was converted to epoxidized rapeseed oil in 91% yield with no hydroxy byproducts. Linseed oil was epoxidized in 80% yield. Methyl esters are also epoxidized without hydrolysis under these conditions. 

Regioselective acylations of polyhydroxylated compounds such as carbohydrates, glycerols, steroids, or alkaloids have been carried out with lipases, esterases, and proteases [13, 20]. One example is the Candida antartica lipase (immobilized on acrylic resin) catalyzed monoacylation of the signalling steroid ectysone (1) giving selectively the 2-C)-acetate 2 (eq. (1)). Using vinyl acetate for this transesterification the reaction was irreversibly pushed to the product side, since the liberated enol instantaneously isomerizes to acetaldehyde [21]. The sometimes unfavorable aldehyde is avoided when 1-ethoxyvinyl acetates [22], trichloro- or -fluoroethyl esters [23 a, b], oxime esters [23 c] or thioesters [23 d] are employed for the quasi-irreversible reaction courses. 

R. Giordano, G. Lombardi, L. Ciaralli, E. Beccaloni, A. Sepe, M. Ciprotti, S. Costantini, Major and trace elements in sediments from Terra Nova Bay - Antartica, Sci. Total Environ., 227 (1999), 29 0. 

L. Campanella, T. Ferri, B. M. Petronio, A. Pupella, M. Soldani, B. Cosma, Organic matter and metals in lake sediments at Terra Nova Bay (Antartica), Ann. Chim. (Rome), 81 (1991), 417-437. 

G. Piccardi, F. Casella, R. Udisti, Non-sea-salt contribution of some chemical species to the snow composition at Terra Nova Bay (Antartica), Int. J. Environ. Anal. Chem., 63 (1996), 207-223. 

F. Casella, R. Udisti, G. Piccardi, The Oceanic Source Contribution to the Snow Composition, as Function of Elevation, at Two Coastal Stations in the Terra Nova Bay Area (Antarctica). Terra Antartica Reports, 1 (1997), 77-80. 

L. Ventajas, Determinacion de residuos de petroleo en aguas antarticas, Instituto Antartico Argentino, Report No. 315 (1985), pp. 12. 

M. Scagliola, A. Poblet, C. Vodopivez, A. Curtosi, J. Marcovecchio, Distribucion de metales pesados en sedimentos marinos superficiales de la Caleta Potter, Isla 25 de Mayo (Shetland del Sur), Antartida, Terceras Jornadas de Comunicaciones sobre Investigaciones Antarticas. Instituto Antartico Argentino (1994), Buenos Aires, 401-408. 

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