123 resultados para Photolabile protecting groups


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We studied the occurrence of O-type P elements in at least one species of each subgroup of the saltans group, in order to better understand the phylogenetic relationships among the elements within the saltans group and with those of species belonging to the willistoni group. We found that the O-type subfamily has a patchy distribution within the saltans group (it does not occur in D. neocordata and D. emarginata), low sequence divergence among species of the saltans group as well as in relation to species of the willistoni group, a lower rate of synonymous substitution for coding sequences compared to Adh, and phylogenetic incongruities. These findings suggest that the evolutionary history of the O-type subfamily within the saltans and willistoni groups follows the same model proposed for the canonical subfamily of P elements, i.e., events of horizontal transfer between species of the saltans and willistoni groups.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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We discuss a system formed by two pairs of brane-anti-brane that form an arbitrary angle in a plane. We identify the gauge groups from this system which presumably could be used to construct gauge theories.

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In this work we make some contributions to the theory of actions of abelian p-groups on the n-Torus T-n. Set congruent to Z(pk1)(h1) x Z(pk2)(h2) x...x Z(pkr)(hr), r >= 1, k(1) >= k(2) >=...>= k(r) >= 1, p prime. Suppose that the group H acts freely on T-n and the induced representation on pi(1)(T-n) congruent to Z(n) is faithful and has first Betti number b. We show that the numbers n, p, b, k(i) and h(i) (i = 1,..,r) satisfy some relation. In particular, when H congruent to Z(p)(h), the minimum value of n is phi(p) + b when b >= 1. Also when H congruent to Z(pk1) x Z(p) the minimum value of n is phi(p(k1)) + p - 1 + b for b >= 1. Here phi denotes the Euler function.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The Brazilian species of Paspalum L. (Poaceae) groups Virgata and Quadrifaria are revised based on herbarium material and live specimens of recent collections. The Virgata taxa are P. wettsteinii, P. rufum, P. regnellii, P. conspersum, P. virgatum and P. commune, while Quadrifaria encompasses P. intermedium, P. densum, P. millegrana, P. durifolium, P. brunneum, P. usteri, P. plenum, P. quadrifarium, P. coryphaeum, P. exaltatum and P. haummmanii. Both groups are commonly found throughout the country, but rare in the wet areas of the Amazonian forest, and better characterized as megatherm plants.

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Objectives: the purpose of this study was to evaluate the correlation between central incisor form and face form in 4 racial groups and to investigate if there was agreement among experts in categorizing the central incisor forms. Method and Materials: A total of 160 subjects (40 whites, 40 mulattos, 40 blacks, and 40 Asians) ranging from 18 to 33 years of age were selected. Digital photographic records were made, 1 full-face and 1 intraoral view of the maxillary right central incisor. The outline tracings of the tooth and face images were obtained using Adobe Photoshop 5.0 software. The outline tracings were printed in distinct transparencies, and 3 prosthodontists determined if there was correspondence between the tooth and the face forms by superimposition of the transparencies. If there was disagreement among the prosthodontists' evaluations, the prevalent decision was considered. The experts also classified the central incisor forms into square, ovoid, tapering, or combination at 2 different sessions. At the first session, no instructions were given. At the second session, the prosthodontists were instructed to follow Williams' method of classification. Results: A correspondence between tooth and face forms was found in 23.75% of all cases. Agreement on the tooth form classifications among the prosthodontists occurred in 30.62% of all cases at the first session and 24.37% at the second session. Conclusion: There is not a highly defined correlation between central incisor form and face form in any racial group studied. In addition, the experts were not in fair agreement in categorizing tooth forms.

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In this study, the influence of the addition of antioxidants in vivo on the fatty acid composition of the flesh of a freshwater fish known as pacu (Piaractus mesopotamicus) is verified. Four groups (one being the control group) of juvenile pacu were cultured on isocaloric and isoproteic diets. The lipid source was soybean oil and diets were added with either 100 ppm of alpha-tocopheryl acetate, or 100 ppm of BHT or 1.4 g of rosemary extract (Herbalox(R))/kg diet. The fatty acid composition of the lipids of the different groups was determined before and after irradiation at 2 and 3 kGy, respectively, for the evaluation of the protective effects of the different antioxidants. Similarly, thiobarbituric acid reactive substances (TBARS) were determined from irradiated and nonirradiated samples. The results showed that the use of antioxidants altered the fatty acid composition of the fillets. TEARS and irradiation confirmed their important role in protecting against lipid oxidation. Among all the antioxidants used, tocopherol was the most efficient, as shown by the highest percentage of polyunsaturated fatty acids (PUFA), by the lowest values of TEARS and by the analyses of the individual fatty acid levels at different irradiation doses. Significant statistical differences were observed only in 17% of the fatty acids in the fillets of the groups. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

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The aim of this paper is to present a procedure that utilizes C-13 NMR for identification of substituent groups which are bonded to carbon skeletons of natural products. For so much was developed a new version of the program (MACRONO), that presents a database with 161 substituent types found in the most varied terpenoids. This new version was widely tested in the identification of the substituents of 60 compounds that, after removal of the signals that did not belong to the carbon skeleton, served to test the prediction of skeletons by using other programs of the expert system (SISTEMAT). (C) 2002 Elsevier B.V. Ltd. All rights reserved.