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71.
Ren Y Acuña UM Jiménez F García R Mejía M Chai H Gallucci JC Farnsworth NR Soejarto DD Carcache de Blanco EJ Kinghorn AD 《Tetrahedron》2012,68(12):2671-2678
Six new (1-6) and eight known germacranolide-type sesquiterpene lactones, along with several known phenylpropanol coumarates and methylated flavonoids, were isolated from the leaves of Piptocoma rufescens, collected in the Dominican Republic. The new compounds were identified by analysis of their spectroscopic data, with the molecular structure of 3 being established by single-crystal X-ray diffraction. The absolute configurations of the sesquiterpene lactones isolated were determined from their CD and NOESY NMR spectra, together with the analysis of Mosher ester reactions. Bioassay screening results showed the majority of the sesquiterpene lactones isolated (1-13) to be highly cytotoxic toward the HT-29 human colon cancer cell line, with the most potent compound being 15-deoxygoyazensolide (10, IC(50), 0.26 μM). In addition, several of the sesquiterpene lactones exhibited NF-κB (p65) inhibitory activity. 相似文献
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73.
One of the most common environmental impacts of road transportation is the traffic noise. Linked to this, Start/Stop is a technology which has demonstrated to save fuel by powering off the engine when the vehicle is stopped, such as in front of a traffic light, and restarting the engine instantly when the driver pushes back the pedal brake to proceed. The technology helps also to reduce the CO2 emission, playing a key role in a way to accomplish stringent emission norms for vehicle manufacturer. However, we are not sure whether it reduces the noise emission and how much? Thus, the main aim of this work is to assess the engine noise emissions of a vehicle incorporating a Start/Stop system in urban traffic, and compare it with those radiated by the mean traffic stream. Experimental results demonstrate that there are no contributions of the Start/Stop system to reduce meaningfully the engine noise in urban traffic. 相似文献
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75.
Heloisa Beraldo Ricardo F. F. da Costa Rejane Lima Geraldo M. de Lima Ivana S. Lula Bernard Mahieu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2455-2463
The reaction of tin(IV) tetrachloride with 3-formylpyridine semicarbazone and different 3-formylpyridine thiosemicarbazones produces [Sn(HL)CL 3 ][SnCl 5 ] where HL stands for the neutral ligand. The tin(IV) complexes were characterized using a variety of spectroscopic techniques. Coordination through the pyridine nitrogen occurs in all cases. Solvation studies in DMSO indicated that dissociation of the ligands and their complete replacement by solvent molecules occurs. 相似文献
76.
Ray L. Frost Yunfei Xi Ricardo Scholz Andrés López Fernanda M. Belotti Mário L. S. C. Chaves 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):1526-1534
Abstract The metal lithium is very important in industry, including lithium batteries. An important source of lithium besides continental brines is granitic pegmatites as in Australia. Lithiophilite is a lithium and manganese phosphate with chemical formula LiMnPO4 and forms a solid solution with triphylite, its Fe analog, and belongs to the triphylite group that includes karenwebberite, natrophilite, and sicklerite. The mineral lithiophilite was characterized by chemical analysis and spectroscopic techniques. The chemical is: Li1.01(Mn0.60, Fe0.41, Mg0.01, Ca0.01)(PO4)0.99 and corresponds to an intermediate member of the triphylite-lithiophilite series, with predominance of the lithiophilite member. The mineral lithiophilite is readily characterized by Raman and infrared spectroscopy. 相似文献
77.
Luis Alvarez‐Thon Carlos Bustos Katherina Espinoza‐Santibaez Maria Teresa Garland Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1200-1204
The title compound, C17H11F5N4O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N—H...O hydrogen bonds and π–π interactions into dimeric entities, presenting a noticeable noncrystallographic C2 symmetry. These dimers are in turn linked by a medium‐strength type‐I C—F...F—C interaction into elongated tetramers. Much weaker C—H...F contacts link the tetramers into broad two‐dimensional substructures parallel to (101). 相似文献
78.
The self-assembly and bioactivity of the peptide–polymer conjugate DGRFFF–PEG3000 containing the RGD cell adhesion motif has been examined, in aqueous solution. The conjugate is designed to be amphiphilic by incorporation of three hydrophobic phenylalanine residues as well as the RGD unit and a short poly(ethylene glycol) (PEG) chain of molar mass 3000 kg mol−1. Above a critical aggregation concentration, determined by fluorescence measurements, signals of β-sheet structure are revealed by spectroscopic measurements, as well as X-ray diffraction. At high concentration, a self-assembled fibril nanostructure is revealed by electron microscopy. The fibrils are observed despite PEG crystallization which occurs on drying. This suggests that DGRFFF has an aggregation tendency that is sufficiently strong not to be prevented by PEG crystallization. The adhesion, viability and proliferation of human corneal fibroblasts was examined for films of the conjugate on tissue culture plates (TCPs) as well as low attachment plates. On TCP, DGRFFF–PEG3000 films prepared at sufficiently low concentration are viable, and cell proliferation is observed. However, on low attachment surfaces, neither cell adhesion nor proliferation was observed, indicating that the RGD motif was not available to enhance cell adhesion. This was ascribed to the core–shell architecture of the self-assembled fibrils with a peptide core surrounded by a PEG shell which hinders access to the RGD unit. 相似文献
79.
Anderson Hollerbach Klier Ricardo José Alvea Maria Auxiliadora Fontes Prado José Dias de Bouza Filho Norma Beatriz D'accorso 《合成通讯》2013,43(23):4361-4374
The synthesis of 5-[6′-deoxy-(1′,2′:3′,4′-di-O-isopropylidene-α-D-galactopyranos-6′-yl)]tetrazole and its reaction with acetic anhydride and 1,2:3,4-di-O-isopropylidene-6-O-(4-toluenesulfonyl)-α-D-galactopyranose are described. 相似文献
80.
Alessandra S. Kiametis João B. L. Martins Luiz A. S. Romeiro Ricardo Gargano 《International journal of quantum chemistry》2013,113(10):1461-1466
Alzheimer's disease is the leading cause of dementia for elderly people. The main active therapeutic is supported on the increased levels of acetylcholine in the synaptic cleft, based on reversible inhibition of the acetylcholinesterase (AChE) enzyme. This article aims to propose possible inhibitor candidates for AChE, designed from nonisoprenoid lipids of cashew (Anacardium occidentale), and based on several electronic properties. These electronic properties were obtained through B3LYP/6‐311+G(2d,p) calculation level. Principal component analysis reveals that from the set of studied molecular structures a small group is correlated with donepezil, a drug with known biological activity. © 2012 Wiley Periodicals, Inc. 相似文献