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101.
102.
C. dos Santos E. da Hora 《The European Physical Journal C - Particles and Fields》2010,70(4):1145-1151
In this paper we study the structure of one dimensional topological solitons in a generalized Abelian-Higgs Chern–Simons model
where the kinetic term is non-canonical. We present an example of an analytical self-dual electrically charged soliton solution
which has a finite momentum per unit length along its direction. We compared the physical properties of our soliton with those
for wall of Jackiw–Lee–Weinberg wall presented in Jackiw et al. (Phys. Rev. D 42:3488, 1990) to conclude that the non-canonical kinetic term can make the wall “thicker” redistributing uniformly the momentum flow along
it. 相似文献
103.
Kelly L. dos Santos CastroPaulo G. de Lima Leandro S.M. e MirandaRodrigo O.M.A. de Souza 《Tetrahedron letters》2011,52(32):4168-4171
A solvent mixture containing the ionic liquid derived from 4-picoline (C4MPyBF4) and water was tested for the Suzuki-Miyaura reaction under microwave irradiation. This solvent system led to very high conversions and clean reactions. When compared with the other more common ionic liquid, such as C4MImBF4, C4MPyBF4 proved to be superior. 相似文献
104.
K. L. G. V. Ara��jo P. S. Epaminondas M. C. D. Silva A. E. A. de Lima R. Rosenhaim A. S. Maia L. E. B. Soledade A. L. Souza I. M. G. Santos A. G. Souza N. Queiroz 《Journal of Thermal Analysis and Calorimetry》2011,106(2):557-561
Physicochemical and thermal analyses were undertaken to evaluate the influence of the temperature on the oxidation of sea fish oil once its polyunsaturated fatty acids deteriorate rapidly. Fish oil displayed four decomposition steps in synthetic air atmosphere and only one step in nitrogen atmosphere. The first step started at 189 and 222 °C for oxidizing and inert atmospheres, respectively. An OIT value of 53 min was measured at 100 °C. After the degradation process the peroxide index and the iodine index reduced from 35.38 to 9.85 meq × 1000 g?1 and from 139.79 to 120.19 gI2 × 100 g?1, respectively. An increase of the free fatty acids amount from 0.07 to 0.17% was observed while viscosity increased from 57.2 to 58.0 cP. Absorption at 272 nm also increased. The thermogravimetric and spectroscopic techniques are reproducible and versatile being an option for characterization of edible oil oxidation. 相似文献
105.
D. Melo R. M. M. Marinho F. T. G. Vieira S. J. G. Lima E. Longo A. G. Souza A. S. Maia I. M. G. Santos 《Journal of Thermal Analysis and Calorimetry》2011,106(2):513-517
Perovskite type oxides have been intensively studied due to their interesting optical, electrical, and catalytic properties.
Among perovskites the alkaline earth stannates stand out, being strontium stannates (SrSnO3) the most important material in ceramic technology among them due to their wide application as dielectric component. SrSnO3 has also been applied as stable capacitor and humidity sensor. In the present work, SrSnO3:Cu was synthesized by polymeric precursor method and heat treated at 700, 800, and 900 °C for 4 h. After that, the material
was characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, and UV–vis spectroscopy. Results
indicated three thermal decomposition steps and confirmed the presence of strontium carbonate and Cu2+ reduction to Cu+ at higher dopant amounts. XRD patterns indicated that the perovskite crystallization started at 700 °C with strontiatite
(SrCO3) and cassiterite (SnO2) as intermediate phases, disappearing at higher temperatures. The amount of secondary phase was reduced with the increase
in the Cu concentration. 相似文献
106.
E. F. S. M. Ramalho A. R. Albuquerque A. L. Souza A. K. Barro A. S. Maia I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,106(3):787-791
The poultry fat methylic (BMF) and ethylic (BEF) biodiesels were synthesized through transesterification by homogeneous basic
catalysis. The chromatographic analyses showed the palmitic, stearic, oleic, and linoleic esters as majority components. Owing
to its considerable amount of polyunsaturated fat acids, poultry fat usually leads to a biodiesel with low oxidative stability.
In this study, the oxidation of their ethylic and methylic biodiesels was evaluated by Rancimat, PDSC, and PetroOxy. The OSI
(Rancimat) was of 0.47 and 0.40 h for the ethylic and methylic biodiesel, respectively. In PDSC, both fuels presented an OT
of about 120–123 °C. PetroOxy analysis indicated an OxyStab of 11 min for BEF and higher than 11 min for BMF. There was no
correspondence among the oxidative stabilities of the employed techniques [OT(BEF) ≈ OT(BMF), OSI(BEF) > OSI(BMF), and OxyStab(BEF) < OxyStab(BMF)].
The discussion of these results was based on the indicator measured by each technique: enthalpic events are observed by PDSC;
conductivity of volatile secondary oxidation products is measured by Rancimat; reduction of the oxygen pressure is determined
by PetroOxy. This discussion showed that these different indicators do not reflect the same stage of the oxidative process
as energy is release at the beginning of the propagation step, oxygen pressure decreases during the propagation step, and
oxidation products are formed during the termination step. 相似文献
107.
Paulina V. F. Santos Ilanna C. Lopes Victor C. Diculescu Mário César U. de Araújo Ana Maria Oliveira‐Brett 《Electroanalysis》2011,23(10):2310-2319
The electrochemical behaviour of Nodularin (NOD), a hepatotoxic cyclic pentapeptide, was studied at a glassy carbon electrode. NOD electrochemical oxidation is an irreversible, pH‐independent process, involving the transfer of one electron. Upon incubation in different pH electrolytes, chemical degradation of NOD was electrochemically detected by the appearance of a new oxidation peak. The chemically degraded NOD (cdNOD), undergoes an irreversible, pH‐dependent oxidation, and its redox products are reversibly oxidised. The charge transfer properties of cdNOD as well as of its redox metabolites were investigated. Mechanisms for NOD oxidation, NOD chemical degradation and oxidation of cdNOD and its metabolites were proposed. 相似文献
108.
Dinorah Gambino Mariana FernándezDiego Santos Gustavo A. EtcheverríaOscar E. Piro Fernando R. PavanClarice Q.F. Leite Isabel TomazFernanda Marques 《Polyhedron》2011,30(7):1360-1366
In the search for gallium bioactive compounds five Ga(III) complexes, [GaIII(L-H)2](NO3), with tridentate salicylaldehyde semicarbazone derivatives as ligands (L) have been synthesized and characterized in the solid state and in solution by different techniques. The crystal structure of [GaIII(L4-H)2](NO3)·2H2O, where L4 is 3-ethoxysalicylaldehyde semicarbazone, was solved by X-ray diffraction methods. The gallium(III) ion is in a distorted octahedral environment, coordinated to two nearly planar and mutually perpendicular 3-ethoxysalicylaldehyde semicarbazonato anions acting as tridentate ligands through their phenol and carbonyl oxygen atoms and their azomethine nitrogen atom. Their biological potential has been explored by evaluating their activity on Mycobacterium tuberculosis, causative agent of tuberculosis, and their cytotoxicity on tumor cell lines. Three different human tumor cell lines were selected that show different degrees of resistance to metallodrugs: ovarian A2780 (low resistance), breast MCF7 (medium resistance) and prostate PC3 (high resistance) cells. Although the complexes have not shown activity on M. tuberculosis, complexation with gallium has led to the enhancement of the cytotoxic potencies of the organic compounds. Those complexes that contain a bromide substituent at the phenolate ring have shown the highest cytotoxicities. In particular, [GaIII(L2-H)2](NO3), where L2 is 5-bromosalicylaldehyde semicarbazone,·has shown a remarkable cytotoxicity on A2780 tumor cell line with an IC50 value of the same order than cisplatin (IC50 Ga-L2 = 2.4 ± 0.3 μM; IC50 cisplatin = 2.0 ± 0.1 μM, 72 h incubation at 37 °C). Interestingly, this complex has also shown moderate cytotoxicity against MCF7 and PC3 cells (IC50 MCF7 = 30 ± 6; IC50 PC3 = 18 ± 3 μM). Therefore, this gallium compound could be considered a promising wide spectrum potential anti-tumor agent. 相似文献
109.
Environmental concerns and oil price rises and dependency promoted strong research in alternative fuel sources and vectors.
Fischer-Tropsch products are considered a valid alternative to oil derivatives having the advantage of being able to share
current infrastructures. As a renewable source of energy, synthesis gas obtained from biomass gasification presents itself
as a sustainable alternative. However, prior to hydrocarbon conversion, the bio-syngas must be conditioned, which includes
the removal of carbon dioxide for subsequent sequestration and capture. A pressure swing adsorption cycle was developed for
the removal and concentration of CO2 from the bio-syngas stream. Activated carbon was chosen as adsorbent. The simulation results showed that it was possible
to produce a (H2 + CO) product with a H2/CO stoichiometric ratio of 2.14 (suitable as feed stream for the Fischer-Tropsch reactor) and a CO2 product with a purity of 95.18%. A CO2 recovery of 90.3% was obtained. A power consumption of 3.36 MW was achieved, which represents a reduction of about 28% when
compared to a Rectisol process with the same recovery. 相似文献
110.
Ancély F. dos Santos Daria Raquel Q. de Almeida Letícia F. Terra Rosangela A.M. Wailemann Vinícius M. Gomes Gabriel S. Arini Felipe G. Ravagnani Maurício S. Baptista Leticia Labriola 《Photochemistry and photobiology》2020,96(3):658-667
Photodynamic therapy (PDT) appears as a promising alternative in the treatment of breast cancer since it can be highly effective in curing cancer while preserving normal tissue. However, predicting outcomes in PDT still constitutes a great challenge. One of the parameters that are usually empirically determined is the rate of photon flux delivered to the tissue (light fluence rate). In the present study, we intended to understand why monolayers of human cells derived from mammary adenocarcinomas (MDA-MB-231 and MCF-7) respond quite differently to fluence rates (cells were irradiated either for 6 or for 16 min) at a fixed light dose (4.5 J cm−2) delivered with an array of LEDs in a typical methylene blue PDT protocol. While death rates of MDA-MB-231 cells were insensitive to the fluence rate, MCF-7 cells showed a quite impressive (three times) decrease in cell death levels in the shorter irradiation protocol. Independent on cell type cell death was invariably correlated with the depletion of reduced glutathione intracellular levels and consequently with widespread redox misbalance. Our data show the potential to optimize fluence rates to provide exhaustion of the cell antioxidant responses in order to circumvent therapy resistance of breast tumors. 相似文献