987 resultados para NATURAL C-13 ABUNDANCE


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Mononuclear manganese(II) [Mn(kappa O-HL)(2)(CH3OH)(4)] (4), nickel(II) [Ni(kappa O-2, kappa N-L)(H2O)(3)] (5), cadmium(II) [Cd(kappa O-2-HL)(2)(CH3OH)(3)] (7), tetranuclear zinc(II) [Zn-4(mu-OH)(2)(1 kappa O:2 kappa O-HL)(4)(kappa O-HL)(2)(H2O)(4)] (6) and polynuclear aqua sodium(I) [Na(H2O)(2)(mu-H2O)(2)](n)(HL)(n) (2) and magnesium(II) [Mg(OH)(H2O)(mu-H2O)(2)](n)(-HL)(n) (3) complexes were synthesized using 3-(2-carboxyphenyl-hydrazone)pentane-2,4-dione (H2L, 1) as a ligand precursor. The complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR, H-1 and C-13 NMR (for 2, 3, 6 and 7) spectroscopies. Mono- or dianionic deprotonated derivatives of H2L display different coordination modes and lead to topologies and nuclearities of the complexes depending on metal ions and conditions used for the syntheses. Extensive intermolecular H-bonds form supramolecular arrangements in 1D chains (4 and 6), 1D chains of the organic anion and 2D networks of the metal-aqua aggregates (2 and 3), 2D networks (7) or even 3D frameworks (5). Electrochemical studies, by cyclic voltammetry and controlled potential electrolysis, show ligand centred redox processes as corroborated by theoretical DFT calculations in terms of LUMO and HOMO compositions. (C) 2012 Elsevier Ltd. All rights reserved.

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The compounds [mPTA][CoCl4] (1, mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation), [CoCl(H2O)(DION)(2)][BF4] (2, DION = 1,10-phenanthroline-5,6-dione), [Zn(DION)(2)]Cl-2 (3) and [ZnCl(O-PTA=O)(DION)][BF4] (4) were synthesized by reaction of CoCl2 with [mPTA]I or DION and ZnCl2 with DION or 1,3,5-triaza-7-phosphaadamantane-7-oxide (PTA=O) and DION, respectively. All complexes are water soluble and have been characterized by IR, far-IR, H-1, C-13 and P-31{H-1} NMR spectroscopy, ESI-MS, elemental analyses and single-crystal X-ray diffraction structural analysis (for 1). They were screened against the human tumour cell lines HCT116, HepG2 and MCF7. Complexes 2 and 3 exhibit the highest in vitro cytotoxicity and show lower cytotoxic activities in normal human fibroblast cell line than in HCT116 tumour cell line, which demonstrates their slight specificity for this type of tumour cell.

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The ruthenium(II)-cymene complexes [Ru(eta(6)-cymene)(bha)Cl] with substituted halogenobenzohydroxamato (bha) ligands (substituents = 4-F, 4-Cl, 4-Br, 2,4-F-2, 3,4-F-2, 2,5-F-2, 2,6-F-2) have been synthesized and characterized by elemental analysis, IR, H-1 NMR, C-13 NMR, cyclic voltammetry and controlled-potential electrolysis, and density functional theory (DFT) studies. The compositions of their frontier molecular orbitals (MOs) were established by DFT calculations, and the oxidation and reduction potentials are shown to follow the orders of the estimated vertical ionization potential and electron affinity, respectively. The electrochemical E-L Lever parameter is estimated for the first time for the various bha ligands, which can thus be ordered according to their electron-donor character. All complexes exhibit very strong protein tyrosine kinase (PTK) inhibitory activity, even much higher than that of genistein, the clinically used PTK inhibitory drug. The complex containing the 2,4-difluorobenzohydroxamato ligand is the most active one, and the dependences of the PTK activity of the complexes and of their redox potentials on the ring substituents are discussed. (C) 2012 Elsevier B.V. All rights reserved.

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[RuCl(arene)(-Cl)](2) dimers were treated in a 1:2 molar ratio with sodium or thallium salts of bis- and tris(pyrazolyl)borate ligands [Na(BpBr3)], [Tl(TpBr3)], and [Tl(Tp(iPr,4Br))]. Mononuclear neutral complexes [RuCl(arene)((2)-BpBr3)] (1: arene=p-cymene (cym); 2: arene=hexamethylbenzene (hmb); 3: arene=benzene (bz)), [RuCl(arene)((2)-TpBr3)] (4: arene=cym; 6: arene=bz), and [RuCl(arene)((2)-Tp(iPr,4Br))] (7: arene=cym, 8: arene=hmb, 9: arene=bz) have been always obtained with the exception of the ionic [Ru-2(hmb)(2)(-Cl)(3)][TpBr3] (5), which formed independently of the ratio of reactants and reaction conditions employed. The ionic [Ru(CH3OH)(cym)((2)-BpBr3)][X] (10: X=PF6, 12: X=O3SCF3) and the neutral [Ru(O2CCF3)(cym)((2)-BpBr3)] (11) have been obtained by a metathesis reaction with corresponding silver salts. All complexes 1-12 have been characterized by analytical and spectroscopic data (IR, ESI-MS, H-1 and (CNMR)-C-13 spectroscopy). The structures of the thallium and calcium derivatives of ligand TpBr3, [Tl(TpBr3)] and [Ca(dmso)(6)][TpBr3](2)2DMSO, of the complexes 1, 4, 5, 6, 11, and of the decomposition product [RuCl(cym)(Hpz(iPr,4Br))(2)][Cl] (7) have been confirmed by using single-crystal X-ray diffraction. Electrochemical studies showed that 1-9 and 11 undergo a single-electron (RuRuIII)-Ru-II oxidation at a potential, measured by cyclic voltammetry, which allows comparison of the electron-donor characters of the bis- and tris(pyrazol-1-yl)borate and arene ligands, and to estimate, for the first time, the values of the Lever E-L ligand parameter for BpBr3, TpBr3, and Tp(iPr,4Br). Theoretical calculations at the DFT level indicated that both oxidation and reduction of the Ru complexes under study are mostly metal-centered with some involvement of the chloride ligand in the former case, and also demonstrated that the experimental isolation of the (3)-binuclear complex 5 (instead of the mononuclear 5) is accounted for by the low thermodynamic stability of the latter species due to steric reasons.

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The Ni-II and Zn-II complexes [MCl(Tpms(Ph))] (Tpms(Ph) = SO3C(pz(Ph))(3), pz = pyrazolyl; M = Ni 2 or Zn 3) and the Cu-II complex [CuCl(Tpms(Ph))(H2O)] (4) have been prepared by treatment of the lithium salt of the sterically demanding and coordination flexible tris(3-phenyl-1-pyrazolyl)methanesulfonate (Tpms(Ph))(-) (1) with the respective metal chlorides. The (Tpms(Ph))(-) ligand shows the N-3 or N2O coordination modes in 2 and 3 or in 4, respectively. Upon reaction of 2 and 3 with Ag(CF3SO3) in acetonitrile the complexes [M(Tpms(Ph))-(MeCN)](CF3SO3) (M = Ni 5 or Zn 6, respectively) were formed. The compounds were obtained in good yields and characterized by analytic and spectral (IR, H-1 and C-13{H-1} NMR, ESI-MS) data, density functional theory (DFT) methods and {for 4 and [(Bu4N)-Bu-n](Tpms(Ph)) (7), the tatter obtained upon Li+ replacement by [(Bu4N)-Bu-n](+) in Li(Tpms(Ph))} by single crystal X-ray diffraction analysis. The Zn-II and Cu-II complexes (3 and 4, respectively) act as efficient catalyst precursors for the diastereoselective nitroaldol reaction of benzaldehydes and nitroethane to the corresponding beta-nitroalkanols (up to 99% yield, at room temperature) with diastereoselectivity towards the formation of the anti isomer, whereas the Ni-II complex 2 only shows a modest catalytic activity.

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Tri-and hexa-cyanoethyl functionalized 17-(L-1) and 42-membered (L-2) macrocyclic compounds were obtained by [1 + 1] (for L-1) or [2 + 2] (for L-2) cyclocondensation of the corresponding dialdehyde and diethylenetriamine, followed by hydrogenation by KBH4 and subsequent cyano-functionalization with acrylonitrile. They react with silver nitrate, leading to the formation of [AgL1](NO3) (1) and of the metalorganic coordination polymers [Ag-2(NO3)(2)L-1](n) (2) and {[Ag2L2](NO3)(2)}(n) (3). The complexes were characterized by elemental analysis, H-1 NMR, C-13 NMR, IR spectroscopies, and ESI-MS; moreover, L-2, 1, 2 and 3 were also characterized by single crystal X-ray diffraction. The metal cation in 1 is pentacoordinated with a N3O2 coordination environment; in 2, the metal cations display N4O2 octahedral and N2O3 square-pyramid coordination and in 3 they are in square-planar N-4 sites. In 1, the ligand acts as a pentadentate chelator, and in the other two cases, the ligands behave as octadentate chelators in a 1 kappa N-3:kappa O-2,2 kappa N,3 kappa N,4 kappa N (in 2) or 1 kappa N-3,2 kappa N-3,3 kappa N,4 kappa N fashion (in 3). The cyanoethyl strands of the ligands are directly involved in the formation of the 2D frameworks of 2 and 3, which in the former polymer can be viewed as a net composed of hexametallic 36-membered macrocyclic rings and in the latter generates extra hexametallic 58-membered cyclic sets that form zig-zag layers. The thermal analytical and electrochemical properties of these silver complexes were also studied.

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We study the peculiar dynamical features of a fractional derivative of complex-order network. The network is composed of two unidirectional rings of cells, coupled through a "buffer" cell. The network has a Z3 × Z5 cyclic symmetry group. The complex derivative Dα±jβ, with α, β ∈ R+ is a generalization of the concept of integer order derivative, where α = 1, β = 0. Each cell is modeled by the Chen oscillator. Numerical simulations of the coupled cell system associated with the network expose patterns such as equilibria, periodic orbits, relaxation oscillations, quasiperiodic motion, and chaos, in one or in two rings of cells. In addition, fixing β = 0.8, we perceive differences in the qualitative behavior of the system, as the parameter c ∈ [13, 24] of the Chen oscillator and/or the real part of the fractional derivative, α ∈ {0.5, 0.6, 0.7, 0.8, 0.9, 1.0}, are varied. Some patterns produced by the coupled system are constrained by the network architecture, but other features are only understood in the light of the internal dynamics of each cell, in this case, the Chen oscillator. What is more important, architecture and/or internal dynamics?

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Essa pesquisa foi conduzida no laboratório de Entomologia Florestal da Universidade Federai de Viçosa à 25 ± 2" C, 60 ± 10% UR e fotoperiodo de 12L:12E. O objetivo foi estudar a biologia de Nystalea nyseus(Cramer, 1775) (Lepidoptera: Notodontidae) em folhas de Eucalyptus urophylla. Ν. nyseusapresentou cinco estádios, com duração, média, de 3,99 ± 0,11; 3,80 ±0,10; 4,95 ± 0,30; 5,96 ±0,21 e 6,85 ±0,14 dias, respectivamente. A duração total da fase larval foi de 25,5 dias. A fase de pré-pupa teve duração de 3,05 ± 0,05; 3,08 ± 0,06 dias e a de pupa 14,75 ± 0,45 c 13,82 ± 0,29 dias para machos e fêmeas, respectivamente. A viabilidade, dos ovos, foi de 74,72% e o período embrionário de 3,40 ± 0,16 dias. A longevidade de adultos, acasalados, foi de 6,71 ± 0,74 dias para machos e 9,14 ± 0,96 dias para fêmeas e razão sexual de 0,55, ou seja uma fêmea para 0,81 macho.

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OBJETIVO: Avaliar a eficácia de programas de conscientização (PC) sobre o controle de fatores de risco (FR) para doença cardiovascular (DCV). MÉTODOS: Pacientes hipercolesterolêmicos de alto risco para DCV foram divididos em 2 grupos durante 16 semanas. O grupo A (n=417, 54,3±10,0 anos, 55% homens) recebeu orientação verbal e escrita sobre controle de FR, e o grupo B (n=180, 54,4±10,9 anos, 45% homens) apenas orientação verbal. Todos os participantes receberam 10mg/dia de pravastatina por 12 semanas. Avaliaram-se o peso, pressão arterial, o colesterol total (CT) e frações, triglicérides, índices I e II de Castelli (CT/HDL-C e LDL-C/HDL-C) e escores de Framingham. RESULTADOS: No basal, A diferiu de B no HDL-C (40,0±11,0 vs 43,0±11,0mg/dl, p=0,013) e no índice I (8,2±3,0 vs 7,6±2,3, p=0,008). Após 16 semanas as variações % foram maiores em A do que B no CT (-28,0 vs -25,0, p<0,05), LDL-C (-29,0 vs -27,6, p<0,05), HDL-C (+13,7 vs. + 10,8, p<0,05) e índice I (-39,0 vs -33,0; p<0,05). A pravastatina potencializou os efeitos da dieta sobre os lípides. CONCLUSÃO: O PC parece ser mais eficaz a curto prazo, em reduzir os FR para DCV do que a orientação apenas verbal.

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I. This paper deals with an experiment carried out to evaluate the effect of the sugar cane upper end on the composition of the sugar cane harvest as a raw material for the sugar industry. The variety studied was Co 421. The authors intend to study other varieties in the future. The data were collected from plant cane, at intervals of two weeks, always from the same field, from a small central area of 3.000 square meters approximately. Sixty (60) stalks were cut in each occasion, randomly chosen from the whole area. They were afterwards separated into three groups of 20 stalks, one for each of the treatments, namely: a) Complete stalks, with no leaves or sheaths. b) Stalks harvested by the technique of REYNOSO, that is, as usually done in practice. c) Stalks with the tops completely cut out, that is, cut by technique of REYNOSO and then with 3 other top internodes eliminated. The treatments caused significant differences on the following technological characteristics: a) Weight b) Cane pol c) Available sucrose (pol) per cent cane d) Cane juice pol e) Saline coefficient of juice. II. Except for weight, all changes were favorable to treatment c, even if with differences relatively slight, in percentage. IIII. Treatment differences for cane fiber, brix, reducing sugars, juice ashes, coefficient of purity and glucose coefficient were not significant. IV. Time of harvest was an important factor affecting the composition of the cane and of the juice. V. On the average the available sucrose of cane for treatments, with an standard error of 0.13%, was: Treatment c 13.05% Treatment b 12.65% Treatment a 12.53% This shows that there is no sound basis for the heavy fines applied by some sugar mills to planters who do not cut low enough the tops of the cane stalks.

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O presente trabalho versa sobre um estudo de variação de Colletotrichum lindemuthianum (Sacc. et Magn.) Scrib., 1888, agente de antracnose do feijoeiro, uma das mais sérias doenças que ocorrem no Brasil. O autor isolou 19 culturas, de C. lindemuthianum de diferentes regiões do Estado de São Paulo e testou-as sôbre as variedades diferenciais Michelite, Dark Red Kidney e Perry Marrow, provenientes de Cornell e Beltsville, e sôbre variedades locais. A variedade Dark Red Kidney proveniente de Cornell se comportou diferentemente da de Beltsville quando inoculada com as culturas C-12, C-13, C-18. Em vista disso, não se pode afirmar se essas culturas pertencem à raça delta ou a uma raça nova ainda não constatada em nenhum lugar do mundo. Para as culturas C-3 e C-15 a variedade Dark Red Kidney se comportou uniformemente, independente da origem. Em vista disso pode-se afirmar que essas culturas pertencem realmente à raça alfa. Para outras culturas não se pôde fazer comparações, com raças que ocorrem em outras partes do mundo. Variedades locais foram em grande número suscetíveis a maioria dos isolamentos testados. Algumas variaram na reação às raças do grupo alfa. A variedade 54 foi resistente a 18 isolamentos testados e a variedade 131 a 5 isolamentos testados num dos ensaios.

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Projecte de recerca elaborat a partir d’una estada a la Stanford University entre abril i juliol del 2007. L’anàlisi de les dinàmiques socials i culturals establertes en els espais de poder de les comunitats locals sicilianes, les acròpolis, és el marc de treball que en l’actualitat s’està desenvolupant per a una futura tesi doctoral. Un estudi que intenta ometre les tradicionals lectures colonials i la perspectiva de l’hel•lenització que habitualment envolten els estudis centrats en les poblacions locals que entren en contacte amb les colònies gregues. En aquest cas, partint de la materialització del discurs de l’elit es vol analitzar com les comunitats sicilianes actuen en una complexa situació d’encontre cultural que caracteritzarà Sicília al llarg de quasi tot el Ir. M. a.C.

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Petrographic, mineralogical, and stable isotopes (delta C-13, delta O-18 values) compositions were used to characterise marbles and sedimentary carbonate rocks from central Morocco, which are considered to be a likely source of ornamental and building material from Roman time to the present day. This new data set was used in the frame of an archaeometric provenance study on Roman artefacts from the town of Thamusida (Kenitra, north Morocco), to assess the potential employment of these rocks for the manufacture of the archaeological materials. A representative set of samples from marbles and other carbonate rocks (limestone, dolostone) were collected in several quarries and outcrops in the Moroccan Meseta, in a region extending from the Meknes-Khenifra alignment to the Atlantic Ocean. All the samples were studied using a petrographic, mineralogical and geochemical methods. The petrographic and minerological investigations (optical microscopy, electron microscopy, X-ray diffraction) allowed to group the carbonate rocks in limestones, foliated limestone, diagenetic breccias and dolostone. The limestones could be further grouped as mudstones, wackestones-packstones, crinoid grainstones, oolitic grainstone and floatstones. Textural differences allowed to define marbles varieties. The stable carbon and oxygen isotope composition proved to be quite useful in the discrimination of marble sources, with apparently less discriminatory potential for carbonate rocks.

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The Mississippi Valley-type zinc and lead deposits at Topla (250,150 metric tons (t) of ore grading 1.0 wt % Zn and 3.3 wt % Pb) and Mezica (19 million metric tons (Mt) of ore grading 5.3 wt % Pb and 2.7 wt % Zn) occur within the Middle to Upper Triassic platform carbonate rocks of the northern Karavanke/Drau Range geotectonic units of the Eastern Alps, Slovenia. The ore and host rocks of these deposits have been investigated by a combination of inorganic and organic geochemical methods to determine major, trace, and rare earth element (REE) concentrations, hydrocarbon distribution, and stable isotope ratios of carbonates, kerogen, extractable organic matter, and individual hydrocarbons. These data combined with sedimentological evidence provide insight into the paleoenvironmental conditions at the site of ore formation. The carbonate isotope composition, the REE patterns, and the distribution of hydrocarbon biomarkers (normal alkanes and steranes) suggest a marine depositional environment. At Topla, a relatively high concentration of redox sensitive trace elements (V, Mo, U) in the host dolostones and REE patterns parallel to that of the North American shale composite suggest that sediments were deposited in a reducing environment. Anoxic conditions enhanced the preservation of organic matter and resulted in relatively higher total organic carbon contents (up to 0.4 wt %). The isotopic composition of the kerogen (delta C-13(kerogon) = -29.4 to -25.0 parts per thousand, delta N-15(kerogen) = -.13.6 to 6.8 parts per thousand) suggests that marine algae and/or bacteria were the main source of organic carbon with a very minor contribution from detrital continental plants and a varying degree of alteration. Extractable organic matter from Topla ore is generally depleted in C-13 compared to the associated kerogen, which is consistent with an indigenous source of the bitumens. The mineralization correlates with delta N-15(kerogen) values around 0 per mil, C-13 depleted kerogen, C-13 enriched n-heptadecane, and relatively high concentrations of bacteria] hydrocarbon biomarkers, indicating a high cyanobacterial biomass at the site of ore formation. Abundant dissimilatory sulfate-reducing bacteria, feeding on the cyanobacterial remains, led to accumulation of biogenic H2S in the pore water of the sediments. This biogenic H2S was mainly incorporated into sedimentary organic matter and diagenetic pyrite. Higher bacterial activity at the ore site also is indicated by specific concentration ratios of hydrocarbons, which are roughly correlated with total Pb plus Zn contents. This correlation is consistent with mixing of hydrothermal metal-rich, fluids and local bacteriogenic sulfide sulfur. The new geochemical data provide supporting evidence that Topla is a low-temperature Mississippi Valley-type deposit formed in an anoxic supratidal saline to hypersaline environment. A laminated cyanobacterial mat, with abundant sulfate-reducing bacteria was the main site of sulfate reduction.