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91.
Caetano W Haddad PS Itri R Severino D Vieira VC Baptista MS Schröder AP Marques CM 《Langmuir : the ACS journal of surfaces and colloids》2007,23(3):1307-1314
We study the photodecomposition of phospholipid bilayers in aqueous solutions of methylene blue. Observation of giant unilamellar vesicles under an optical microscope reveals a consistent pattern of membrane disruption as a function of methylene blue concentration and photon density for different substrates supporting the vesicles. 相似文献
92.
Liara Aparecida dos Santos Leal Dalcidio Moraes Claudio Laira Vieira Toscani 《PAMM》2004,4(1):590-591
In the present work we are interested in to provide a universal language for supporting formalisms to specify the approximation hierarchy system for an abstract NP‐hard optimization problem. This work grew from the idea of providing a categorical view of structural complexity to optimization problems. The direction is aimed towards actually exploring the connections among the structural complexity aspects and categorical concepts, which may be viewed in a high‐level, in a structuralistic sense. After introducing the optimization problems categories OPTS and OPT, as well as related questions, a formal system modelling the approximation hierarchy of a given optimization problem is provided, based on categorical shape theory. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
93.
Schistosomiasis is one of the major public health problems worldwide. Even though this is a common illness among preschool children in poor countries, treatment is carried out mainly through the administration of praziquantel tablets, which has some disadvantages, such as the strong bitter taste. As an alternative to overcome this problem, the development of new encapsulated praziquantel formulations is demanded. For this reason, suspension polymerizations are carried out for the in situ encapsulation of praziquantel into polymer microparticles, using methyl methacrylate (MMA) and cationic compounds (diethylaminoethyl methacrylate, DEAEMA, and dimethylaminoethyl methacrylate, DMAEMA) as comonomers. This technique allows for the preparation of polymer microparticles with high encapsulation efficiencies (>90%) with characteristic sizes ranging from 0.5 to 1500 µm. Drug release profiles show that praziquantel is released from poly(methyl methacrylate) microparticles slowly due to the existence of strong diffusional resistance. On the other hand, the addition of cationic comonomers renders polymer particles sensitive to pH variations, allowing for faster release of praziquantel in acidic environments, as found in the stomach. 相似文献
94.
Thermography was used to study the propagation of fatigue cracks during cyclic loading of pre-cracked SAE keyhole polycarbonate specimens. A micro-bolometer infrared camera (FLIR A655sc) and a commercially available software program (DeltaTherm2) were employed. The stress intensity factors were determined using a hybrid thermoelastic stress analysis (TSA) technique. The crack growth rate was determined via thermography using two different approaches. The first approach used the output of the crack-tip position from the developed TSA algorithm and the number of cycles between data sets. The second approach used temperature measurement as a new way to determine da/dN (crack growth rate) directly. As a result, da/dN vs ΔK (stress intensity factor range) graphs were plotted and fitted using Paris’ law. A comparison between the resultant da/dN vs ΔK curves and results found in the literature, as well as curves from the finite element method (FEM) simulations showed good agreement. The conclusion was that thermography is a very powerful tool that can detect, measure and monitor fatigue cracks in polycarbonate. 相似文献
95.
S. Faria P. A. Vieira M. M. Resende F. P. França V. L. Cardoso 《Applied biochemistry and biotechnology》2009,156(1-3):45-58
Xanthan gum production was studied using sugarcane broth as the raw material and batch fermentation by Xanthomonas campestris pv. campestris NRRL B-1459. The purpose of this study was to optimize the variables of sucrose, yeast extract, and ammonium nitrate concentrations and to determine the kinetic parameters of this bioreaction under optimized conditions. The effects of yeast extract and ammonium nitrate concentrations for a given sucrose concentration (12.1–37.8 g L?1) were evaluated by central composite design to maximize the conversion efficiency. In a bioreactor, the maximum conversion efficiency was achieved using 27.0 g L?1 sucrose, 2.7 g L?1 yeast extract, and 0.9 g L?1 NH4NO3. This point was assayed in a shaker and in a bioreactor to compare bioreaction parameters. These parameters were estimated by the unstructured kinetic model of Weiss and Ollis (Biotechnol Bioeng 22:859–873, 1980) to determinate the yields (Y P/S), the maximum growth specific rate (μ max), and the saturation cellular concentration (X*). The parameters of the model (μ max, X*, m, λ, α, and β) were obtained by nonlinear regression. For production of xanthan gum in a shaker, the values of μ max and Y P/S obtained were 0.119 h?1 and 0.34 g g?1, respectively, while in a bioreactor, they were 0.411 h?1 and 0.63 g g?1, respectively. 相似文献
96.
Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and an environmental
estrogen. The aim of this work was to verify the degradation the alachlor by gamma radiation. Gamma radiation from 60Co was used to degrade the alachlor herbicide in water and methanol solution. The alachlor in water and alcohol solution in
the concentration of 100 mgL−1 was irradiated with doses of 0.25–50 kGy, at dose rate 5–6 and 2.7 kGyh−1. High performance liquid chromatography was used as an analytical technique to determine the degradation rate of herbicide
studied. 相似文献
97.
Vanessa Gisele Pasqualotto Severino Cristiane de Melo CazalMoacir Rossi Forim Maria Fátima das Graças Fernandes da SilvaEdson Rodrigues-Filho João Batista FernandesPaulo Cezar Vieira 《Journal of chromatography. A》2009,1216(19):4275-4281
High-speed counter-current chromatography (HSCCC) with a two-phase solvent system (hexane–ethanol–acetonitrile–water 10:8:1:1, v/v) was applied to examine the leaves of Hortia oreadica, which afforded the known limonoid guyanin (1), the alkaloids rutaecarpin (2) and dictamnine (6), the dihydrocinnamic acid derivatives methyl 5,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoate (3), 5,8-dimethoxy-2,2-dimethyl-2H-1-benzopyran-6-propanoic acid (4), together with the new E-3,4-dimethoxy-α(3-hydroxy-4-carbomethoxyphenyl)cinnamic acid (5). The recovery of compounds 1–6 was determined by comparison with LC-atmospheric pressure chemical ionization MS/MS data: 66.2%, 93.1%, 102.5%, 101.2%, 99.0% and 84.9%, respectively. Compound 3 showed IC50 of 23.6 μM against Plasmodium falciparum and 15.6 μM against Trypanosoma brucei rhodesienses and was not toxic to KB cells (IC50 > 100 μM). 相似文献
98.
A. L. M. de Oliveira J. M. Ferreira Márcia R. S. Silva Soraia C. de Souza F. T. G. Vieira E. Longo A. G. Souza Iêda M. G. Santos 《Journal of Thermal Analysis and Calorimetry》2009,97(1):167-172
NiWO4 and ZnWO4 were synthesized by the polymeric precursor method at low temperatures with zinc or nickel carbonate as secondary phase.
The materials were characterized by thermal analysis (TG/DTA), infrared spectroscopy, UV–Vis spectroscopy and X-ray diffraction.
NiWO4 was crystalline after calcination at 350 °C/12 h while ZnWO4 only crystallized after calcination at 400 °C for 2 h. Thermal decomposition of the powder precursor of NiWO4 heat treated for 12 h had one exothermic transition, while the precursor heat treated for 24 h had one more step between
600 and 800 °C with a small mass gain. Powder precursor of ZnWO4 presented three exothermic transitions, with peak temperatures and mass losses higher than NiWO4 has indicating that nickel made carbon elimination easier. 相似文献
99.
Sylvio Barbon Jr. Rodrigo Capobianco Guido Lucimar Sasso Vieira Everthon Silva Fonseca Fabrício Lopes Sanchez Paulo Rogério Scalassara Carlos Dias Maciel José Carlos Pereira Shi-Huang Chen 《Journal of Computational and Applied Mathematics》2009
Dynamic Time Warping (DTW), a pattern matching technique traditionally used for restricted vocabulary speech recognition, is based on a temporal alignment of the input signal with the template models. The principal drawback of DTW is its high computational cost as the lengths of the signals increase. This paper shows extended results over our previously published conference paper, which introduces an optimized version of the DTW that is based on the Discrete Wavelet Transform (DWT). 相似文献
100.
Vieira HS Takahashi JA Gunatilaka AA Boaventura MA 《Magnetic resonance in chemistry : MRC》2006,44(2):146-150
A highly rearranged novel dilactone was the single product isolated from Baeyer-Villiger oxidation of a norketone prepared from grandiflorenic acid, a natural kaurane diterpene. The complete 1H and 13C NMR assignment is presented for this novel compound that showed discrete in vitro antibacterial activity. 相似文献