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91.
Manuel Alberto Flores‐Hidalgo Daniel Glossman‐Mitnik D. H. Galvan Diana Barraza‐Jimenez 《中国化学会会志》2013,60(8):1082-1091
Density Functional Theory employing hybrid and M06 functionals in combination with three different basis sets is used to calculate the ground state of a cage like (ZnO)12 nanocluster which has been consistently reported as the more stable cluster for its particular size. B3LYP and B3PW91 hybrid functionals combined with 6‐31+G*, Lanl2dz and SDD basis sets are employed to treat the ZnO molecular system. Alternatively, three M06 functionals in combination with three basis sets are employed in the nanostructure calculations. Results obtained by treating ZnO sodalite cage nanocluster with M06 functionals demonstrated comparable quality to results obtained with hybrid functionals. Within this study, efficient theoretical DFT methods with the widely known hybrid and the recently created M06 meta‐hybrid functionals are employed to study nanostructured ZnO. Our resulting parameters provide a fresh approach performance wise on the different theoretical methods to treat transition metal nanostructures, particularly, ZnO nanoclusters geometry and electronic structure. 相似文献
92.
Claudio L. Donnici Elaine Henriques Teixeira Pereira Júlio C. Dias Lopes Liliana Marzorati Blanka Wladislaw 《合成通讯》2013,43(3):342-350
The study on reactivity of several α-substituted α-sulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the α-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity of α-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2? and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any α-substituted α-sulfonyl malonate. 相似文献
93.
Ricardo A. W. Neves Filho Diana C. B. da Silva-Alves Janaína V. dos Anjos 《合成通讯》2013,43(19):2596-2602
A simple and straightforward synthesis of 3-aryl-5-hydroxyalkyl-1,2,4-oxadiazoles is described. The reaction among arylamidoximes, ethyl glycolate or ethyl lactate, and potassium carbonate in refluxing toluene afforded the desired 1,2,4-oxadiazoles in moderate to good yields. The synthesis has been accomplished in a single step, avoiding protection–deprotection protocols. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
94.
M. H. Godinho C. Cruz P. I. C. Teixeira A. J. Ferreira C. Costa P. S. Kulkarni 《Liquid crystals》2013,40(2):103-107
The phase behaviour of a number of N‐alkylimidazolium salts was studied using polarizing optical microscopy, differential scanning calorimetry and X‐ray diffraction. Two of these compounds exhibit lamellar mesophases at temperatures above 50°C. In these systems, the liquid crystalline behaviour may be induced at room temperature by shear. Sheared films of these materials, observed between crossed polarisers, have a morphology that is typical of (wet) liquid foams: they partition into dark domains separated by brighter (birefringent) walls, which are approximately arcs of circle and meet at “Plateau borders” with three or more sides. Where walls meet three at a time, they do so at approximately 120° angles. These patterns coarsen with time and both T1 and T2 processes have been observed, as in foams. The time evolution of domains is also consistent with von Neumann's law. We conjecture that the bright walls are regions of high concentration of defects produced by shear, and that the system is dominated by the interfacial tension between these walls and the uniform domains. The control of self‐organised monodomains, as observed in these systems, is expected to play an important role in potential applications. 相似文献
95.
Theolyta S. Araújo Claudener S. Teixeira Maria A. P. Falcão Vanir R. Pinto Junior Mayara Quiroz Santiago Raquel G. Benevides Plínio Delatorre Jorge L. Martins Magna S. Alexandre-Moreira Benildo S. Cavada Eliane A. Campesatto Bruno A. M. Rocha 《Applied biochemistry and biotechnology》2013,171(8):1944-1955
Lectins are a structurally heterogeneous group of proteins or glycoproteins with at least one noncatalytic domain binding reversibly to a specific mono- or oligosaccharide. Monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins. In this study, we evaluated anti-inflammatory and antinociceptive effects of monocot lectin from the Canna limbata seeds (CLL). To accomplish this, CLL was purified and subjected to pharmacological assays: abdominal writhing induced by acetic acid, formalin, hot plate and Zymosan A-induced peritonitis tests. The CLL was purified by chromatographic chitin column, and the relative mass of 21 kDa observed in electrophoresis was confirmed by electrospray mass spectrometry, which also revealed that purified CLL consists of a dimer having a weight of 49,676 Da. The CLL showed nociceptive activity in the acetic acid test as well as peripheral antinociceptive response. The CLL also showed anti-inflammatory effect with the reduction of inflammation in the formalin test and neutrophil migration into the peritoneal cavity. This is the first report of anti-inflammatory activity for a monocot lectin, and it suggests a new pharmacological tool to understand inflammatory and antinociceptive processes mediated through lectins. 相似文献
96.
Carlos Victor Montefusco-Pereira Maria José de Carvalho Ana Paula de Araújo Boleti Lorisa Simas Teixeira Humberto Reis Matos Emerson Silva Lima 《Applied biochemistry and biotechnology》2013,170(6):1367-1378
Diabetes mellitus is a metabolic disease characterized by abnormally high plasma glucose levels, leading to major complications, such as insulin resistance, obesity, hyperlipidemia, and hypertension, also with alterations in the immune and neuronal systems. Brazilian plants have been studied as important sources for new molecules with medicinal properties. The genus Passiflora known as “Maracujá” has been used as a traditional folk medicine for a long time, so an investigation was performed regarding an endemic kind of passion fruit (Passiflora nitida Kunth) from Amazonas, Brazil. Here, we aimed to determine its potential biological activity against metabolic syndrome, oxidative stress, pain, and inflammation. The hydroethanol leaf extract revealed an in vitro α-glucosidase inhibitory activity of 50 % inhibitory concentration (IC50)?=?6.78?±?0.31 μg/mL and an α-amylase inhibition of IC50?=?93.36?±?4.37. In vivo, experiments of different saccharide tolerance resulted in significant glycemia control and, with alloxan-diabetic mice, resulted in a decrease of total cholesterol, a hypoglycemic effect, and an antioxidant activity by thiobarbituric acid-reactive substances measurement. Also, it decreased the carrageenan-induced edema volume and the rate of writhing as a nociceptive response. These results indicate positive effects of P. nitida extract and its potential to inhibit metabolic syndrome. 相似文献
97.
Effect of viscosity of a liquid membrane containing oleyl alcohol on the pertraction of butyric acid
Marek Blahušiak Ján Marták Fernando Miranda Štefan Schlosser José A. Teixeira 《Chemical Papers》2013,67(12):1560-1568
Solvent formulation is important in the optimization of the mass-transfer through supported liquid membranes (SLM) in pertraction and membrane extraction. Oleyl alcohol (OA) is frequently used as the solvent or diluent in the extraction of carboxylic acids. A disadvantage of OA is its relatively high viscosity of 28.32 mPa s at 25°C. This can be decreased by the application of a less viscous OA diluent, e.g. dodecane. The relationship between the ratio of the distribution coefficient of butyric acid (BA), D F, and the viscosity of OA-dodecane solvents, µ, as extraction and transport characteristics, and the overall mass-transfer coefficient, K p, through SLMs was analyzed. Dependence of the D F/µ ratio on the OA concentration showed a maximum at the OA concentration of 15 mass % to 30 mass %. The OA concentration dependence of K p for SLMs exhibited also a maximum at about 30 mass % and 20 mass % of OA at the BA concentration driving force of 0.12 kmol m?3 and 0.3 kmol m?3, respectively. Shifting of the maximum in K p dependences towards lower OA concentrations by increasing the BA concentration driving force is in agreement with the D F/µ ratio dependence. Using pure OA as the solvent or diluent is not preferable and a mixture of a low viscosity diluent with the OA concentration below 40 mass % should be used. The presented results show the potential of the D F/µ ratio in the screening and formulation of solvents in extraction and SLM optimization. 相似文献
98.
99.
Poul Erik Hansen Fadhil S. Kamounah Diana Zhiryakova Yana Manolova Liudmil Antonov 《Tetrahedron letters》2014
It has recently been suggested that 1,1′,1′′-(2,4,6-trihydroxybenzene-1,3,5-triyl)triethanone may be tautomeric. Using 13C NMR chemical shifts and deuterium isotope effects on 13C chemical shifts, it is demonstrated that this is not the case. This compound occurs as a strongly hydrogen bonded benzene structure with hydrogen bonds between OH groups and the acetyl groups in both non-polar and hydrogen donating solvents. Quantum-chemical calculations using MP2 and M06-2X methods show substantial preference for the phenol structure in both the gas phase, and in cyclohexane and methanol. In addition, conventional UV–vis spectroscopy data suggest not tautomeric, but aggregation behaviour of the molecule in methanol and acetonitrile. 相似文献
100.
The ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was successfully used as alternative solvent for native chemical ligation of peptide fragments to produce model peptide LYRAXCRANK (X = G, A, L, N, Q, K, and F). The commonly used buffer system including thiol additives such as thiophenol and benzyl mercaptan can be replaced by the nontoxic ionic liquid [C2mim][OAc]. In addition to improving the solubility of the peptides in [C2mim][OAc], yields and rates of the ligation reactions were found to be efficiently enhanced. 相似文献