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991.
Roddy E. Ramos-Gonzáles Enver Fernandez-Chillcce Luiz C. Barbosa Hugo E. Hernández-Figueroa 《Fiber and Integrated Optics》2013,32(3):186-195
Abstract An efficient technique to control the zero-dispersion wavelength of a microstructured optical fiber is proposed and numerically demonstrated in this article. This technique is based on the variation of the linear refractive index and the thickness of a thin film covering the microstructured optical fiber holes' inner surfaces. A powerful and accurate code based on a full-vector finite-element method formulation in conjunction with perfectly matched layers was used. A maximum of 570-nm zero-dispersion wavelength displacement is demonstrated. This thin film can be included after the microstructured optical fiber has been fabricated, as that means the zero dispersion of such fiber can be tailored as needed. 相似文献
992.
993.
Lenilson C. Rocha Isac G. Rosset Rodrigo F. Luiz Cristiano Raminelli André L.M. Porto 《Tetrahedron: Asymmetry》2010,21(8):926-929
The kinetic resolution of (±)-iodophenylethanols was carried out using lipase from Candida antarctica and in some cases the enantiomeric excesses were high (up to >98%). Enantiomerically enriched (S)-iodophenylethanols produced by the enzymatic resolution process were used in the synthesis of chiral biphenyl compounds by the Suzuki reaction with good yields (63–65%). 相似文献
994.
995.
Rogério A. GarianiFernando A.G. Luengo Luiz A.S. ValeReinaldo C. Bazito João V. Comasseto 《Tetrahedron letters》2011,52(26):3336-3338
1-(Phenylthio)-, 1-(phenylseleno)- and 1-(phenyltelluro)-propan-2-ol were efficiently resolved by CAL-B in sc-CO2. 相似文献
996.
Influence of lead dioxide electrodes morphology on kinetics and current efficiency of oxygen-ozone evolution reactions 总被引:1,自引:0,他引:1
Élen C. G. Rufino Mario H. P. Santana Luiz A. De Faria Leonardo M. Da Silva 《Chemical Papers》2010,64(6):749-757
Influence of electrode morphology on electrochemical properties of lead dioxide electrodes (β-PbO2) for oxygen-ozone evolution reactions in acid medium was investigated using scanning electronic microscopy (SEM), cyclic
voltammetry (CV), polarization curves (PC), and determination of the current efficiency (Φ). Experimental findings revealed that application of high electrodeposition current densities furnishes more rough β-PbO2 films. Surface characteristics were verified by SEM images and the analysis of interfacial pseudo-capacitances and morphology
factor (φ). Kinetic study of the overall electrode process (O2 + O3) based on the analysis of the Tafel slope revealed that the electrode morphology and electrolyte composition considerably
affect the electrode kinetics. In most cases, the existence of two Tafel slopes distributed in the low and high overpotential
domains was observed. Abnormal Tafel slopes (b ≠ 120 mV) obtained for the primary water discharge step during water electrolysis were interpreted considering the apparent
charge transfer coefficient (α
apa). Optimum conditions for the ozone production were obtained for the less rough β-PbO2 electrode immersed in a sulfuric acid solution (1.0 mol dm−3) containing KPF6 (30 × 10−3 mol dm−3), where the current efficiency of 15 mass % for the ozone production was obtained. 相似文献
997.
Sergio Antonio Fernandes Luiz Fernando Cabeça Anita Jocelyne Marsaioli Eneida de Paula 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):395-401
Cyclodextrins (CD) and calixarenes are complexing agents that have been successfully used as pharmaceutical drug carriers,
to improve the bioavailability of medicines. The aim of this work was to investigate the complexation of the local anesthetic
tetracaine 1 with β-cyclodextrin 2, as well as with p-sulphonic acid calix[6]arene 3. 1H NMR experiments were carried out in D2O, i.e., with the charged tetracaine species 1. HR-DOSY 1H NMR allowed determination of the fraction of complexed population (%p
bound = 55% and 70%) and the apparent association constants (K
a = 1358 and 3889 M−1), respectively, for 1/2 and 1/3. These results confirm that a strong association takes place between 1 and 2, while the 1/3 complex is even more stable, due to the negatively charged sulphonic groups of 3. Studies conducted at pH 10 revealed that the association of the uncharged form of 1 with 3 is considerably weaker, while that with 2 increased significantly (K
a
= 6597 M−1), protecting the anesthetic against alkaline hydrolysis. 1H-ROESY 1D NMR experiments allowed determination of the host-guest relative positions, revealing that the proposed topologies
for the 1/2 and 1/3 complexes were quite different. The complexation of 1 with either 2 or 3 is being investigated in view of its potential use in new therapeutic formulations, designed to increase the bioavailability
and/or to decrease the systemic toxicity of tetracaine, in anesthesia procedures. 相似文献
998.
Juliano R. de Menezes Vicenti Robert A. Burrow 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(3):m88-m90
In the title chain compound, [Ag(NO3)(C3H7NO)(C26H24P2)]n, the bis(diphenylphosphino)ethane (dppe) components lie across centres of inversion. The dppe units link the Ag+ ions into chains along [100]. A nitrate anion is coordinated to the Ag atom, together with one molecule of N,N‐dimethylformamide (DMF) solvent. At room temperature, the coordinated DMF shows a long Ag—O distance [2.620 (3) Å] and relatively large thermal motion, while at 100 K the Ag—O distance is shorter [2.5588 (19) Å] and the thermal motion is similar to that of the rest of the complex. The behaviour of the DMF molecule is related to the size of the solvent pocket, viz. 146 Å3 at 293 K and 131 Å3 at 100 K. 相似文献
999.
Maria Isaura P. Oliveira Nilton D. Piovesan Ines C. José Everaldo G. Barros Maurilio A. Moreira Luiz O. Oliveira 《Chromatographia》2007,66(7-8):521-527
Two traditional soybean cultivars, CAC-1 and Garimpo, two backcrossed-derived isolines lacking lipoxygenase (LOX?KTI+), and two backcrossed-derived isolines lacking lipoxygenase and Kunitz trypsin inhibitor (LOX?KTI?) in the seeds were grown in São Gotardo and Paracatu, Brazil, and their protein, oil, and isoflavone contents were assessed. The loss of LOX or the combined loss of LOX and KTI brought about no significant changes in seed oil content. Significant decreases in seed protein content were observed in isolines of the CAC-1 genetic background, but not in isolines of the Garimpo background. Total isoflavone contents in LOX?KTI+ and LOX?KTI? isolines were higher than those in the normal parental cultivars. Genetic eliminations also changed isoflavone composition. These results suggest that the genetic removal LOX and KTI may be an efficient approach to improve nutritional and nutraceutical values of soybean seeds, however, performances of null lines should be evaluated for undesirable modifications in seed composition. 相似文献
1000.
The dispersion of pollutants in the environment is an issue of great interest as it directly affects air quality, mainly in large cities. Experimental and numerical tools have been used to predict the behavior of pollutant species dispersion in the atmosphere. A software has been developed based on the control‐volume based on the finite element method in order to obtain two‐dimensional simulations of Navier–Stokes equations and heat or mass transportation in regions with obstacles, varying position of the pollutant source. Numeric results of some applications were obtained and, whenever possible, compared with literature results showing satisfactory accordance. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献