997 resultados para PG-M


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We present a quantitative low energy electron diffraction (LEED) surface-crystallograpic study of the complete adsorption geometry of glycine adsorbed on Cu{110} in the ordered p(3×2) phase. The glycine molecules form bonds to the surface through the N atoms of the amino group and the two O atoms of the de-protonated carboxylate group, each with separate Cu atoms such that every Cu atom in the first layer is involved in a bond. Laterally, N atoms are nearest to the atop site (displacement 0.41 Å). The O atoms are asymmetrically displaced from the atop site by 0.54 Å and 1.18 Å with two very different O-Cu bond lengths of 1.93 Å and 2.18 Å. The atom positions of the upper-most Cu layers show small relaxations within 0.07 Å of the bulk-truncated surface geometry. The unit cell of the adsorbate layer consists of two glycine molecules, which are related by a glide-line symmetry operation. This study clearly shows that a significant coverage of adsorbate structures without this glide-line symmetry must be rejected, both on the grounds of the energy dependence of the spot intensities (LEED-IV curves) and of systematic absences in the LEED pattern.

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

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The crystal structure of shikimate kinase from Mycobacterium tuberculosis (MtSK) complexed with MgADP and shikimic acid (shikimate) has been determined at 2.3 Angstrom resolution, clearly revealing the amino acid residues involved in shikimate binding. In MtSK, the Glu61 strictly conserved in SK forms a hydrogen bond and salt-bridge with Arg58 and assists in positioning the guanidinium group of Arg58 for shikimate binding. The carboxyl group of shikimate interacts with Arg58, Gly81, and Arg136, and hydroxyl groups with Asp34 and Gly80. The crystal structure of MtSK-MgADP-shikimate will provide crucial information for elucidation of the mechanism of SK-catalyzed reaction and for the development of a new generation of drugs against tuberculosis. (C) 2004 Elsevier B.V. All rights reserved.

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This study aims to test a new conceptual model based on the relationship between quality management (QM), environmental management maturity (EMM), adoption of external practices of green supply chain management (GSCM) (green purchasing and collaboration with customers) and green performance (GP) with data from 95 Brazilian firms with ISO 14001. To our knowledge, such links and relationships are not simultaneously identified and tested in the literature. The results indicate the validation of all of the research hypotheses. This paper highlights that an improvement in green performance will require attention to quality management, environmental management maturity, and green supply chain.

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We report the complete genome sequence of bovine pestivirus strain PG-2. The sequence data from this virus showed that PG-2 is closely related to the giraffe pestivirus strain H138. PG-2 and H138 belong to one pestivirus species that should be considered an approved member of the genus Pestivirus.