排序方式： 共有45条查询结果，搜索用时 0 毫秒
11.
Desireddy Krishna Swaroop;Nagiri Ravi Kumar;Narra Srikanth Reddy;Nagender Punna;Nanubolu Jagadeesh Babu;Banda Narsaiah; 《European journal of organic chemistry》2019,2019(22):3654-3657
An efficient method for the synthesis of α-fluoroamides having C–F quaternary stereogenic center was achieved by a one-pot four-component strategy under mild reaction conditions. A variety of α-fluoroamides was synthesized by using 1,3-dicarbonyl, isocyanide, acetylenedicarboxylate and N-fluorobenzenesulfonimide (NFSI) systems with good to excellent yields up to 93 %. The current protocol proceeds through the unstable 3-fluoro 4H-pyran intermediate, which is key for the reaction and further it can be hydrolyzed due to the high electronegativity of the fluorine atom to produce the desired α-fluoroamides. 相似文献
12.
Robson Tadeu Soares de Oliveira Giancarlo Richard Salazar‐Banda Sergio Antonio Spinola Machado Luis Alberto Avaca 《Electroanalysis》2008,20(4):396-401
The electrochemical methods cyclic and square‐wave voltammetry were applied to develop an electroanalytical procedure for the determination of N‐nitrosamines (N‐nitrosopyrrolidine, N‐nitrosopiperidine and N‐nitrosodiethylamine) in aqueous solutions. Cyclic voltammetry was used to evaluate the electrochemical behaviors of N‐nitrosamines on boron‐doped diamond electrodes. It was observed an irreversible electrooxidation peak located in approximately 1.8 V (vs. Ag/AgCl) for both N‐nitrosamines. The optimal electrochemical response was obtained using the following square‐wave voltammetry parameters: f=250 Hz, Esw=50 mV and Es=2 mV using a Britton–Robinson buffer solution as electrolyte (pH 2). The detection and quantification limits determined for total N‐nitrosamines were 6.0×10?8 and 2.0×10?7 mol L?1, respectively. 相似文献
13.
Singh Sahjendra N. Myatt James H. Addington Gregory A. Banda Siva S. Hall James K. 《Nonlinear dynamics》2002,28(1):71-81
This paper treats the question of feedback linearizing control oftwo-dimensional incompressible, unsteady wake flow. For definiteness,flow past a circular cylinder is considered, but the design approachpresented here is applicable to other flow control problems. Twofinite-dimensional lower-order models based on Proper OrthogonalDecomposition (POD) of dimension N with N actuators are considered.Models I and II are obtained using control function and penalty functionmethods, respectively. Control action can be achieved by a combinationof suction, injection, and synthetic jets. For the design ofcontrollers, it is assumed that the system matrices of the POD modelsare unknown. Nonlinear adaptive control systems for the two models arederived. For model I, nontrivial zero-error dynamics exists, which playa key role in the stability of the closed-loop system. But for model II,global adaptive trajectory control is achieved. In the closed-loopsystem, the mode amplitudes asymptotically follow the referencetrajectories. Simulation results for a 4-mode POD model obtained usingthe penalty function method are presented. These results show that inthe closed-loop system, unsteadiness in the mode amplitudes can besuppressed in spite of large uncertainties in the flow model. 相似文献
14.
Kim SH Kwon SW Chu SY Lee JH Narsaiah B Kim CH Kang SK Kang NS Rhee SD Bae MA Ahn SH Ha DC Kim KY Ahn JH 《Chemical & pharmaceutical bulletin》2011,59(1):46-52
In the continuation of our 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitor research, cyclic sulfonamide derivatives with an acetamide group at the 2-position were synthesized and evaluated for their abilities to inhibit 11β-HSD1. Among this series, Compound 34 showed good in vitro activity toward human 11β-HSD1, selectivity against 11β-HSD2, microsomal stability, good pharmacokinetic and safety profiles human ether-a-go-go related gene (hERG and cytochrome P450 (CYP)). Also, a docking study explained the activity difference between human and mouse 11β-HSD1. 相似文献
15.
The image reconstructed from a composite hologram is compared with that obtained by multiple-exposure of images independently reconstructed from a single element and also with that from a synthetic-aperture hologram. The experimental results show the difference in the principle of speckle noise reduction with these three methods and prove that the composite hologram arranged only in a row is sufficient for reducing the speckle noise. 相似文献
16.
Cheol Park John Wilkinson Sumanth Banda Zoubeida Ounaies Kristopher E. Wise Godfrey Sauti Peter T. Lillehei Joycelyn S. Harrison 《Journal of Polymer Science.Polymer Physics》2006,44(12):1751-1762
While high shear alignment has been shown to improve the mechanical properties of single‐wall carbon nanotube (SWNT)‐polymer composites, this method does not allow for control over the electrical and dielectric properties of the composite and often results in degradation of these properties. Here, we report a novel method to actively align SWNTs in a polymer matrix, which permits control over the degree of alignment of the SWNTs without the side effects of shear alignment. In this process, SWNTs were aligned via AC field‐induced dipolar interactions among the nanotubes in a liquid matrix followed by immobilization by photopolymerization under continued application of the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy, and the morphology of the aligned nanocomposites was investigated by high‐resolution scanning electron microscopy. The structure of the field induced aligned SWNTs was intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field parameters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1751–1762, 2006 相似文献
17.
Shinichi Sakurai Yoshihiro Okamoto Harunori Sakaue Takeshi Nakamura Lameck Banda Shunji Nomura 《Journal of Polymer Science.Polymer Physics》2000,38(13):1716-1728
We report the structure and properties of segmented poly(urethaneurea) (SPUU) with relatively short hard‐segment chains. The SPUU samples comprised poly(tetramethylene glycol) prepolymer as a soft segment and 4,4′‐diphenylmethane diisocyanate (MDI) units as a hard segment that were extended with ethylenediamine. To discuss quantitatively the conformation of the soft‐segment chain in the microphase‐separated domain space, we used SPUU samples for which the molecular weights of the hard‐ and soft‐segment chains are well characterized. The effects of the cohesive force in the hard‐segment chains on the structure and properties of SPUU were also studied with samples of different chain lengths of the hard segment, although the window of xH, the average number of MDI units in a hard‐segment chain, was narrow (2.38 ≤ xH ≤ 2.77). There were urethane groups in the soft segments and urea groups in the hard segments. Because of a strong cohesive force between the urea groups, we could control the overall cohesive force in the hard‐segment chains by controlling the chain lengths of the hard segment. First of all, microphase separation was found to be better developed in the samples with longer hard‐segment chains because of an increase of the cohesive force. It was also found that the interfacial thickness became thinner. The long spacing for the one‐dimensionally repeating hard‐ and soft‐segment domains could be well correlated with the molecular characteristics when the assumption of Gaussian conformation was employed for the soft‐segment chains. This is unusual for strongly segregated block copolymers and might be characteristic of multiblock copolymers containing rod–coil chains. The tensile moduli and thermal stability temperature, TH, increased with an increase of the cohesive force, whereas the glass‐transition temperature, the melting temperature, and the degree of crystallinity of the soft‐segment chains decreased. The increase in TH especially was appreciable, although the variation in the chain length of the hard segment was not profound. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1716–1728, 2000 相似文献
18.
19.
Mapundi Banda Mohammed Seaïd 《Numerical Methods for Partial Differential Equations》2007,23(5):1211-1234
We present a class of high‐order weighted essentially nonoscillatory (WENO) reconstructions based on relaxation approximation of hyperbolic systems of conservation laws. The main advantage of combining the WENO schemes with relaxation approximation is the fact that the presented schemes avoid solution of the Riemann problems due to the relaxation approach and high‐resolution is obtained by applying the WENO approach. The emphasis is on a fifth‐order scheme and its performance for solving a wide class of systems of conservation laws. To show the effectiveness of these methods, we present numerical results for different test problems on multidimensional hyperbolic systems of conservation laws. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
20.
In this talk some recent numerical results based on discrete-velocity relaxation systems will be presented. Discrete-velocity equations are derived from continuous Boltzmann-type equations with appropriate approximations suitable for incompressible flows. A relaxation system is derived by taking moments of the discrete-velocity equations. This approach is also extended to turbulence flows using Large-Eddy Simulation as well as thermal flows. The schemes are tested by solving a collection of examples. In particular the developed methods demonstrate potential as tools for Large-Eddy Simulation and flow with Radiative Heat transfer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献