975 resultados para 1,3-BIS(4-PYRIDYL)PROPANE


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C28H20N4Pd2S2, monoclinic, P121/c1 (No. 14), a = 11.325(1) Å, b = 13.530(1) Å, c = 17.925(1) Å, β = 106.23(1)°, V = 2637.1 Å 3, Z = 4, Rgt(F) = 0.052, wRref(F2) = 0.129, T = 293 K. © by Oldenbourg Wissenschaftsverlag.

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C4H7BF3KS2, monoclinic, P121/c1 (no. 14), a = 14.7374(3) Å, b = 9.0612(1) Å, c = 13.5805(2) Å, β = 98.964(4)°, V = 1791.4 Å3, Z = 8, Rgt(F) = 0.029, wRref(F2) = 0.010, T = 296 K. © by Oldenbourg Wissenschaftsverlag.

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A series of segmented poly(urethane-urea)s containing 1,3,5 triazine in the hard block and hexamethylene spacers in the soft block was prepared. The hard to soft segment ratio was varied systematically, to afford a series of polymers in which the chromophore concentration varied from 4.2% to 18.1%. Although triazine emission is located in the UV region, the films with higher content of the chromophore emitted a visible blue light (425 nm) when excited at the very red-edge of the absorption band. The photophysical properties of the materials were strongly dependent on the relative amount of triazine moieties along the main chain. Isolated moieties emit in copolymers with small amount of triazine groups, indicating that even though in solid state, these moieties tend to be apart. Two photophysical consequences were observed when the amount of triazine increases: there is some energy transfer process involving isolated moieties with consequent decrease of the lifetime and an additional red-edge emission attributed to aggregated lumophores. The mono-exponential decay observed for the isolated form is substituted by a bi-exponential decay of the aggregated species. The materials were not strong emitters, but since the N-containing triazine moieties are good electron transport groups, the polymers have potential application as electron transport enhancers in various applications. © 2006 Elsevier B.V. All rights reserved.

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Botryosphaeria rhodina MAMB-05 produced β-1,3-glucanases and botryosphaeran when grown on glucose, while Trichoderma harzianum Rifai only produced the enzyme. A comparison of long-term cultivation (300h) by B. rhodina demonstrated a correlation between the formation of botryosphaeran (48h) and its consumption (after 108h), and de-repression of β-1,3-glucanase synthesis when glucose was depleted from the nutrient medium, whereas for T. harzianum enzyme production commenced during exponential growth. Growth profiles and levels of β-1,3-glucanases produced by both fungi on botryosphaeran also differed, as well as the production of β-1,3-glucanases and β-1,6-glucanases on glucose, lactose, laminarin, botryosphaeran, lasiodiplodan, curdlan, Brewer's yeast powder and lyophilized fungal mycelium, which were dependent upon the carbon source used. A statistical mixture-design used to optimize β-1,3-glucanase production by both fungi evaluated botryosphaeran, glucose and lactose concentrations as variables. For B. rhodina, glucose and lactose promoted enzyme production at the same levels (2.30UmL -1), whereas botryosphaeran added to these substrates exerted a synergic effect favorable for β-glucanase production by T. harzianum (4.25UmL -1). © 2010 Elsevier B.V.

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The synthesis and characterization of ruthenium compounds of the type [RuCl2(P)2(N-N)] [(P)2 = (PPh3) 2, dppb = 1,4-bis(diphenylphosphino)butano; dppp = 1,3-bis(diphenylphosphino)propane; N-N = 5,5′-dimethyl-2,2′dipyridyl (5,5′-mebipy) or 4,4′-dimethyl-2,2′dipyridyl (4,4′-mebipy)] are described. The complexes were characterized using elemental analysis, UV-Vis and infrared spectroscopies, cyclic voltammetry, and X-ray crystallography. In vitro evaluation of the complexes, using the MTT methodology, revealed their cytotoxic activities in a range of 5.4-15.7 μM against the MDA-MB-231 breast tumor cells and showed that, in this case, they are more active than the reference metallodrug cisplatin. The in vitro antimycobacterial activities of the complexes had their Minimum Inhibitory Concentration (MIC) for MTB cell growth measured, by the REMA method. The MICs for these complexes were found to be between 12.5 and 25.0 μg/mL. The results are comparable with the second line drug cycloserine (MIC = 12.5-50.0 μg/mL), commonly used in the treatment of TB. © 2013 Elsevier Ltd. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Odontologia - FOA

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Oxidation state and coordination of transition metal cations seems to be hard to assess when considering multiple cations, each one with different possible oxidation states. In fact, this is the case of the spineltype double oxides family. High resolution K beta X-ray fluorescence spectra were measured in Mn(2-x)V(1+4)O4 (x=0 and 1/3) spinels-type double oxides in order to determine the oxidation state and coordination of V and Mn cations. The relative intensity of radiative Auger effect KM2,3M4,5 to the total intensity and the integral absolute difference value were used as reference parameters for the characterization of Mn oxidation states. The coordination of Mn ions was inferred by the intensity of the K beta(5) line. In the case of V compounds, it was used as the intensity of the line K beta' relative to the total area of K beta region. The obtained results were further compared with X-ray absorption spectra analysis, showing good agreements regarding the oxidation state characterization. However, there were found some discrepancies in coordination, due to customary oversimplifications in the K beta(5) line origin. The obtained results might represent valuable and useful data for chemical scopes of characterizing spineltype oxides family. (C) 2013 Elsevier Ltd. All rights reserved.

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β-(1→3)-Glucanases were produced by Trichoderma harzianum Rifai PAMB-86 cultivated on botryosphaeran in a bench-fermenter and optimised by the response surface method. Maximal enzyme titres occurred at 5 days, initial pH 5.5 and aeration of 1.5vvm. β-(1→3)-The β-glucanolytic enzyme complex produced by T. harzianum Rifai PAMB- 86 was fractionated by gel filtration into 2 fractions (F-I, F-II), and employed to produce gluco-oligosaccharides from algal paramylon ((1→3)-β-D-glucan) and lichen pustulan ((1→6)-β-D-glucan). Both enzymes attacked paramylon to the extent of ~15-20% in 30 min releasing glucose and laminaribiose as major end-products, and laminarioligosaccharides of degree of polymerization (DP) ≥3. Only F-I degraded pustulan resulting in ~2% degradation at 30 min, with glucose, gentiobiose and gentio-oligosaccharides of DP ≥4 as major products. The difference in the nature of the hydrolysis products can be explained by the substrate specificities of each enzyme fraction, and the structural differences of the β-D-glucans attacked.

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The organometallic compound [Pd(C-bzan)(SCN)(dppp)] {bzan = N-benzylideneaniline, dppp = 1,3-bis(diphenylphosphino)propane} was synthesized and characterized by elemental analyses, infrared and H-1 and P-31(H-1) NMR spectroscopies. The crystal and molecular structures of the title complex were determined by single-crystal X-ray diffraction techniques. In vitro antimycobacterial evaluation demonstrated that the compound [Pd(C-bzan)(SCN)(dppp)] displayed a MIC of 5.15 mu M, which is superior than those values found for some commonly used anti-TB drugs and other Pd(II) complexes. (C) 2012 Elsevier B.V. All rights reserved.

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Nicotinic acetylcholine receptors (nAChRs) have been studied in detail with regard to their interaction with therapeutic and drug addiction-related compounds. Using a structureactivity approach, we have examined the relationship among the molecular features of a set of eight para-R-substituted N,N-[(dimethylamino)ethyl] benzoate hydrochlorides, structurally related to procaine and their affinity for the a3 beta 4 nAChR heterologously expressed in KXa3 beta 4R2 cells. Affinity values (log[1/IC50]) of these compounds for the a3 beta 4 nAChR were determined by their competition with [3H]TCP binding. Log(1/IC50) values were analyzed considering different hydrophobic and electronic parameters and those related to molar refractivity. These have been experimentally determined or were taken from published literature. In accordance with literature observations, the generated cross-validated quantitative structureactivity relationship (QSAR) equations indicated a significant contribution of hydrophobic term to binding affinity of procaine analogs to the receptor and predicted affinity values for several local anesthetics (LAs) sets taken from the literature. The predicted values by using the QSAR model correlated well with the published values both for neuronal and for electroplaque nAChRs. Our work also reveals the general structure features of LAs that are important for interaction with nAChRs as well as the structural modifications that could be made to enhance binding affinity. (c) 2012 Wiley Periodicals, Inc.

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Glasses in the system [Na2S](2/3)[(B2S3)(x)(P2S5)(1-x)](1/3) (0.0 <= x <= 1.0) were prepared by the melt quenching technique, and their properties were characterized by thermal analysis and impedance spectroscopy. Their atomic-level structures were comprehensively characterized by Raman spectroscopy and B-11, P-31, and Na-23 high resolution solid state magic-angle spinning (MAS) NMR techniques. P-31 MAS NMR peak assignments were made by the presence or absence of homonuclear indirect P-31-P-31 spin-spin interactions as detected using homonuclear J-resolved and refocused INADEQUATE techniques. The extent of B-S-P connectivity in the glassy network was quantified by P-31{B-11} and B-11{P-31} rotational echo double resonance spectroscopy. The results clearly illustrate that the network modifier alkali sulfide, Na2S, is not proportionally shared between the two network former components, B and P. Rather, the thiophosphate (P) component tends to attract a larger concentration of network modifier species than predicted by the bulk composition, and this results in the conversion of P2S74-, pyrothiophosphate, Na/P = 2:1, units into PS43-, orthothiophosphate, Na/P = 3:1, groups. Charge balance is maintained by increasing the net degree of polymerization of the thioborate (B) units through the formation of covalent bridging sulfur (BS) units, B S B. Detailed inspection of the B-11 MAS NMR spectra reveals that multiple thioborate units are formed, ranging from neutral BS3/2 groups all the way to the fully depolymerized orthothioborate (BS33-) species. On the basis of these results, a comprehensive and quantitative structural model is developed for these glasses, on the basis of which the compositional trends in the glass transition temperatures (T-g) and ionic conductivities can be rationalized. Up to x = 0.4, the dominant process can be described in a simplified way by the net reaction equation P-1 + B-1 reversible arrow P-0 + B-4, where the superscripts denote the number of BS atoms for the respective network former species. Above x = 0.4, all of the thiophosphate units are of the P-0 type and both pyro-(B-1) and orthothioborate (B-0) species make increasing contributions to the network structure with increasing x. In sharp contrast to the situation in sodium borophosphate glasses, four-coordinated thioborate species are generally less abundant and heteroatomic B-S-P linkages appear to not exist. On the basis of this structural information, compositional trends in the ionic conductivities are discussed in relation to the nature of the charge-compensating anionic species and the spatial distribution of the charge carriers.

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Background: This study evaluated a wide range of viral load (VL) thresholds to identify a cut-point that best predicts new clinical events in children on stable highly active antiretroviral therapy (HAART). Methods: Cox proportional hazards modeling was used to assess the adjusted risk for World Health Organization stage 3 or 4 clinical events (WHO events) as a function of time-varying CD4, VL, and hemoglobin values in a cohort study of Latin American children on HAART >= 6 months. Models were fit using different VL cut-points between 400 and 50,000 copies per milliliter, with model fit evaluated on the basis of the minimum Akaike information criterion value, a standard model fit statistic. Results: Models were based on 67 subjects with WHO events out of 550 subjects on study. The VL cut-points of >2600 and >32,000 copies per milliliter corresponded to the lowest Akaike information criterion values and were associated with the highest hazard ratios (2.0, P = 0.015; and 2.1, P = 0.0058, respectively) for WHO events. Conclusions: In HIV-infected Latin American children on stable HAART, 2 distinct VL thresholds (>2600 and >32,000 copies/mL) were identified for predicting children at significantly increased risk for HIV-related clinical illness, after accounting for CD4 level, hemoglobin level, and other significant factors.