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131.
P. K. Venkatesh 《Journal of Optimization Theory and Applications》2001,109(3):675-689
We present a method, based on approximation theory, for the solution of optimum control problems of differential-algebraic systems of any index. Its essence is the rendering of any optimum control formulation of systems of differential-algebraic equations into one of a pure optimum control formulation of the Bolza type by means of characteristic functions approximated by damped pseudo-spectral expansions. 相似文献
132.
We examine using Monte Carlo simulations, photon transport in optically ‘thin’ slabs whose thickness L is only a few times the transport mean free path l*, with particles of different scattering anisotropies. The confined geometry causes an auto-selection of only photons with
looping paths to remain within the slab. The results of the Monte Carlo simulations are borne out by our analytical treatment
that incorporates directional persistence by the use of the Ornstein-Uhlenbeck process, which interpolates between the short
time ballistic and long time diffusive regimes. 相似文献
133.
Gantait Arunava Sahu Amita Venkatesh Pichairajan Dutta Pradeep K. Mukherjee Pulok K. 《平面色谱法杂志一现代薄层色谱法》2010,23(5):323-325
JPC – Journal of Planar Chromatography – Modern TLC - Coccinia grandis (L). Voigt (family: Cucurbitaceae) is widely used in the Indian system of medicine for various skin diseases,... 相似文献
134.
Rubel Chakravarty Rakesh Shukla Ramu Ram Avesh Kumar Tyagi Ashutosh Dash Meera Venkatesh 《Chromatographia》2010,72(9-10):875-884
The feasibility of using tetragonal nano-zirconia (t-ZrO2) as an effective sorbent for developing a 99Mo/99mTc chromatographic generator was demonstrated. The structural characteristics of the sorbent matrix were investigated by different analytical techniques such as XRD, BET surface area analysis, FT-IR, TEM etc. The material synthesized was nanocrystalline, in tetragonal phase with an average particle size of ~7 nm and a large surface area of 340 m2 g?1. The equilibrium sorption capacity of t-ZrO2 is >250 mg Mo g?1. The present study indicates that 99Mo is both strongly and selectively retained by t-ZrO2 at acidic pH and 99mTc could be readily eluted from it, using 0.9% NaCl solution. A 9.25 GBq (250 mCi) t-ZrO2 based chromatographic 99Mo/99mTc generator was developed and its performance was repeatedly evaluated for 10 days. 99mTc could be eluted with >85% yield having acceptable radionuclidic, radiochemical and chemical purity for clinical applications. The compatibility of the product in the preparation of 99mTc labeled formulations such as 99mTc-EC and 99mTc-DMSA was evaluated and found to be satisfactory. 相似文献
135.
The impact of basis set superposition error (BSSE) upon molecular properties determined using the density functionals B3LYP, B3PW91, B3P86, BLYP, BPW91, and BP86 in combination with the correlation consistent basis sets [cc-pVnZ, where n = D(2), T(3), Q(4), and 5] for a set of first-row closed-shell molecules has been examined. Correcting for BSSE enables the irregular convergence behavior in molecular properties such as dissociation energies with respect to increasing basis set size, noted in earlier studies, to be improved. However, for some molecules and functional combinations, BSSE correction alone does not improve the irregular convergence behavior. 相似文献
136.
Ch. Venkatesh V. Srinivas Maheswar Panda V.V. Rao 《Solid State Communications》2010,150(17-18):893-896
The dielectric behavior of polyvinylidene fluoride/nanoquasicrystalline Al–Cu–Fe composites has been investigated over a broad frequency range. High effective dielectric constant (3800) at 100 Hz is observed near the percolation threshold. The dielectric behavior has been explained on the basis of boundary layer capacitor effect, Maxwell Wagner Sillars interfacial polarization and percolation theory while the dielectric anomalies are attributed to process of fabrication leading to thick insulating layer between the filler particles forming a gap in effective tunneling range of two filler particles, inhibiting the probability of higher order tunneling. The mechanical/electronic properties of these composites will make them suitable for multifunctional applications. 相似文献
137.
Jayabharathi J Thanikachalam V Perumal MV Srinivasan N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,83(1):200-206
Azo linked dye derivatives were synthesized and characterized by NMR, mass and elemental analysis. An excited state intramolecular proton transfer (ESIPT) in hydroxy Schiff base has been analyzed, and found that two distinct ground state isomers of I and II are responsible for the observed dual emission. DFT calculation on energy, dipole moment, charge distribution of the rotamers in the ground and excited states support the ESIPT process. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than the ground state. By varying the addition of base concentration to hydroxy Schiff base, two isobestic points were found which confirm the equilibrium among the trans enol form, anion and the cis enol form. Fluorescence quenching with metal ions reveal that hydroxy Schiff base can be used as a new fluorescence sensor to detect the Cu(2+) ion. 相似文献
138.
Successful statistical copolymerization of an alpha-olefin (1-octene) with an acrylate (butyl acrylate, BA) and with a methacrylate (methyl methacrylate, MMA), employing reversible addition-fragmentation chain transfer (RAFT) mediated polymerization has been accomplished 相似文献
139.
Recent advances in sample preparation techniques for effective bioanalytical methods 总被引:1,自引:0,他引:1
This paper reviews the recent developments in bioanalysis sample preparation techniques and gives an update on basic principles, theory, applications and possibilities for automation, and a comparative discussion on the advantages and limitation of each technique. Conventional liquid-liquid extraction (LLE), protein precipitation (PP) and solid-phase extraction (SPE) techniques are now been considered as methods of the past. The last decade has witnessed a rapid development of novel sample preparation techniques in bioanalysis. Developments in SPE techniques such as selective sorbents and in the overall approach to SPE, such as hybrid SPE and molecularly imprinted polymer SPE, have been addressed. Considerable literature has been published in the area of solid-phase micro-extraction and its different versions, e.g. stir bar sorptive extraction, and their application in the development of selective and sensitive bioanalytical methods. Techniques such as dispersive solid-phase extraction, disposable pipette extraction and micro-extraction by packed sorbent offer a variety of extraction phases and provide unique advantages to bioanalytical methods. On-line SPE utilizing column-switching techniques is rapidly gaining acceptance in bioanalytical applications. PP sample preparation techniques such as PP filter plates/tubes offer many advantages like removal of phospholipids and proteins in plasma/serum. Newer approaches to conventional LLE techniques (salting-out LLE) are also covered in this review article. 相似文献
140.
Duke and Kowalski in [A problem of Linnik for elliptic curves and mean-value estimates for automorphic representations, Invent. Math. 139(1) (2000) 1–39 (with an appendix by Dinakar Ramakrishnan)] derive a large sieve inequality for automorphic forms on GL(n) via the Rankin–Selberg method. We give here a partial complement to this result: using some explicit geometry of fundamental regions, we prove a large sieve inequality yielding sharp results in a region distinct to that in [Duke and Kowalski, A problem of Linnik for elliptic curves and mean-value estimates for automorphic representations, Invent. Math. 139(1) (2000) 1–39 (with an appendix by Dinakar Ramakrishnan)]. As an application, we give a generalization to GL(n) of Duke's multiplicity theorem from [Duke, The dimension of the space of cusp forms of weight one, Internat. Math. Res. Notices (2) (1995) 99–109 (electronic)]; we also establish basic estimates on Fourier coefficients of GL(n) forms by computing the ramified factors for GL(n)×GL(n) Rankin–Selberg integrals. 相似文献