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51.
Kinetics of oxidation of pantothenic acid (PA) by sodium N‐chloro‐p‐toluenesulfonamide or chloramine‐T (CAT) in the presence of HClO4 and NaOH (catalyzed by OsO4) has been investigated at 313 K. The stoichiometry and oxidation products are same in both media; however, their kinetic patterns were found to be different. In acid medium, the rate shows first‐order dependence on [CAT]o, fractional‐order dependence on [PA]o, and inverse fractional‐order on [H+]. In alkaline medium, the rate shows first‐order dependence each on [CAT]o and [PA]o and fractional‐order dependence on each of [OH?] and [OsO4]. Effects of added p‐toluenesulfonamide and halide ions, varying ionic strength, and dielectric constant of medium as well as solvent isotope on the rate of reaction have been investigated. Activation parameters were evaluated, and the reaction constants involved in the mechanisms have been computed. The proposed mechanisms and the derived rate laws are consistent with the observed kinetics. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 201–210, 2005 相似文献
52.
Aerodynamic force measurement using 3-component accelerometer force balance system in a hypersonic shock tunnel 总被引:1,自引:0,他引:1
A new three-component accelerometer force balance has been designed, calibrated and tested in hypersonic shock tunnel (HST2)
of Indian Institute of Science. The newly designed balance is able to measure aerodynamic forces (within test time of one
millisecond) on test models at angles of attack from 0 to 12°. Two models, a blunt cone with after body and a blunt cone with
after body and frustum are used to establish the accuracy of the force balance. The tests were conducted for the above two
configurations with a constant Mach number of 8 and total enthalpy of 2.0 MJ/kg. The effectiveness of the balance is demonstrated
by comparing the forces and moments of measured data with AGARD models. The flow fields around the test model are simulated
using a 3D axisymmetric Navier–Stokes solver and the simulated results were compared with the measured values. Measured and
computed force data are matched within ±10% for two different models tested here. The accuracy of the force balance is also
estimated with the Newtonian theory and the values are approximately ±10% for the axial component and ±8% for the normal and
pitching moment components.
相似文献
53.
Band‐selective excited ultrahigh resolution PSYCHE‐TOCSY: fast screening of organic molecules and complex mixtures 下载免费PDF全文
Jagadeesh Bharatam 《Magnetic resonance in chemistry : MRC》2016,54(4):308-314
Precise assignments of 1H atomic sites and establishment of their through‐bond COSY or TOCSY connectivity are crucial for molecular structural characterization by using 1H NMR spectroscopy. However, this exercise is often hampered by signal overlap, primarily because of 1H–1H scalar coupling multiplets, even at typical high magnetic fields. The recent developments in homodecoupling strategies for effectively suppressing the coupling multiplets into nice singlets (pure‐shift), particularly, Morris's advanced broadband pure‐shift yielded by chirp excitation (PSYCHE) decoupling and ultrahigh resolution PSYCHE‐TOCSY schemes, have shown new possibilities for unambiguous structural elucidation of complex organic molecules. The superior broadband PSYCHE‐TOCSY exhibits enhanced performance over the earlier TOCSY methods, which however warrants prolonged experimental times due to the requirement of large number of dwell increments along the indirect dimension. Herein, we present fast and band‐selective analog of the broadband PSYCHE‐TOCSY, which is useful for analyzing complex organic molecules that exhibit characteristic yet crowded spectral regions. The simple pulse scheme relies on band‐selective excitation (BSE) followed by PSYCHE homodecoupling in the indirect dimension. The BSE‐PSYCHE‐TOCSY has been exemplified for Estradiol and a complex carbohydrate mixture comprised of six constituents of closely comparable molecular weights. The experimental times are greatly reduced viz., ~20 fold for Estradiol and ~10 fold for carbohydrate mixture, with respect to the broadband PSYCHE‐TOCSY. Furthermore, unlike the earlier homonuclear band‐selective decoupling, the BSE‐PSYCHE‐decoupling provides fully decoupled pure‐shift spectra for all the individual chemical sites within the excited band. The BSE‐PSYCHE‐TOCSY is expected to have significant potential for quick screening of complex organic molecules and mixtures at ultrahigh resolution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
54.
Frontispiece: Rhodium Enalcarbenoids: Direct Synthesis of Indoles by Rhodium(II)‐Catalyzed [4+2] Benzannulation of Pyrroles 下载免费PDF全文
55.
Lower bounds on the scalar dissipation rate in rectilinear flows are found for three sets of constraints. The bounding dissipation rates provide upper bound estimates of the scalar concentration variance. One of the lower bounds on the dissipation rate is close to the dissipation rate assessed from detailed numerical simulation. This proximity enables a simplified model of concentration variance. For a pulse input of solute, the predictions of concentration variance by the simplified model are in agreement with the results of detailed simulation. The large-time bimodality of the concentration variance and its rate of decay observed in the detailed numerical simulations is predicted by the simplified model. 相似文献
56.
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
57.
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
58.
Rajenahally V. Jagadeesh Y. Sree Sandhya P. Karthikeyan S. Sudhakar Reddy P. Pradeep Kumar Reddy M. Viniod Kumar 《合成通讯》2013,43(16):2343-2349
α-Chloroalkyl aryl ethers has been obtained in good yields from phenols and aryl α-chloroalkyl sulfides. 相似文献
59.
The ruthenium benzimidazolylidene‐based N‐heterocyclic carbene (NHC) complex 4 catalyzes the direct dehydrogenative condensation of primary alcohols into esters and primary alcohols in the presence of amines to the corresponding amides in high yields. This efficient new catalytic system shows a high selectivity towards the conversion of diols to polyesters and of a mixture of diols and diamines to polyamides. The only side product formed in this reaction is molecular hydrogen. Remarkable is the conversion of hydroxytelechelic polytetrahydrofuran ( = 1000 g mol−1)—a polydispers starting material—into a hydrolytically degradable polyether with ester linkages ( = 32 600 g mol−1) and, in the presence of aliphatic diamines, into a polyether with amide linkages in the back bone ( = 16 000 g mol−1).
60.
M. S. R. Murty Mohana Rao Katiki B. Ramalingeswara Rao Jagadeesh Babu Nanubolu Sudheer Kumar Buddana R. S. Prakasham 《合成通讯》2014,44(18):2724-2737
An efficient, green, and chemoselective S-alkylation of 5-aryl-1H-1,2,4-triazole-3-thiones with diethyl (3-bromopropyl)phosphonate in water, catalyzed by nano-Fe2O3 under ligand- and base-free conditions, is reported. Clean reaction, less expensive catalyst, excellent yields, and easy workup are the advantages of the present method. The catalyst can be easily collected by a magnet and recycled without significant loss in catalytic activity. The newly synthesized compounds were screened for their antioxidant property by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay. The majority of the compounds exhibited good antioxidant activity. 相似文献