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排序方式: 共有236条查询结果,搜索用时 171 毫秒
231.
Billye Cheek Mieczyslaw Dabkowski Amr El Nagdi Louis R. Hunt T. P. LaFaveJr Ke Liu Duncan L. MacFarlane Viswanath Ramakrishna 《Acta Appl Math》2012,118(1):107-123
In this work, we consider design questions for an active optical lattice filter, which is being manufactured at the University
of Texas at Dallas, and which has proven to be useful in the signal processing task of RF channelization. The filter can be
described by a linear, discrete time state space model. The controlling agents, the gains, are embedded in the matrices intervening
in this state space model. Consequently, techniques from linear feedback control theory do not apply. We concentrate on the
question of finding real valued gains so that the A matrix of the state space model has a prescribed characteristic polynomial. We find that three of the coefficients can be
arbitrarily picked, but that the remaining are constrained by these and the other system parameters. Our techniques use methods
from constructive algebraic geometry. 相似文献
232.
The solvation dynamics of 4-aminophthalimide (4-AP) in two micellar systems (cetyltrimethylammonium bromide (M-CTAB) and Triton X-100 (M-TX-100)) has been studied. The results presented are in agreement with our earlier findings in sodium dodecyl sulfate (M-SDS) micelle (J. Phys. Chem. B 107 (2003) 13,986, J. Phys. Chem. B 109 (2005) 9422). They have confirmed that the main reason for the observed shape and position of the time changes in 4-AP time-resolved emission spectra (TRES) is the process of establishing a new equilibrium between two emissive species present in micellar systems, the excited 4-AP in the intramolecular charge transfer state (S(1)-ICT) and the exciplex formed between 4-AP in the S1-ICT state and water molecules dissolved inside micelles. In M-TX-100 and in M-CTAB this process has been found to be slower than in the earlier studied M-SDS. The presence of two emitting species has been concluded on the basis of observation of the isoemissive point in the time-resolved area-normalized emission spectra (TRANES) of 4-AP in micellar systems studied. It has been shown that the distance between the 4-AP molecule and the water molecules present inside the micelles can be one of the parameters responsible for the long-time duration of the exciplex formation and solvation process in the micelles. 相似文献
233.
This article reports for the first time the application of solid lead microelectrode for organic compound determination. The proposed sensor was used for anticancer drug Imatinib quantification by adsorptive stripping voltammetry. Procedure of Imatinib determination was developed utilizing advantages ensured by solid lead microelectrode: reusability and durability for a long period of time and its ecological character as compared to film electrodes. The detection limit of Imatinib determination was calculated to be 1.9 × 10−10 mol L−1. The analytical usability of the developed procedure was confirmed by acceptable recoveries of Imatinib determination in spiked urine samples. 相似文献
234.
Wincenty Turek Mieczyslaw Lapkowski Adam Pron Joanna Debiec Agnieszka Wolna Wojciech Domagala 《Macromolecular Symposia》2004,210(1):281-289
Polymer support such as polypyrrole was selected as a matrix for heteropolyacid H5PMo10V2O40 in an attempt to prepare heterogeneous catalysts containing two different active centers: protons and transition metal ions. Exchanging protons from heteropolyanions dispersed in polymer matrix into ferric or ferrous ions cause the modifications of their catalytic properties. It is manifested by decrease of activity of acid-base centers and increase of activity of oxidative-reductive centers. Oxidation state of iron in all samples before and after catalytic reaction is the same (Fe(III)), but their structure is not similar. For catalysts doped with ferric ions the structural order is much more pronounced than for these doped with ferrous ions. 相似文献
235.
236.
Ibrahim Barakat Philippe Dubois Robert Jr
me Philippe Teyssi Mieczyslaw Mazurek 《Macromolecular Symposia》1994,88(1):227-244
Block polymerization of glycolide (GA) and ϵ-caprolactone (ϵ-CL) has been initiated with aluminum alkoxides, such as Al(OiPr)3 and Et2AlOCH2X (where X = -CH2-Br and -CH2O-C(O)-C(Me)=CH2), in THF at 40°C. Structure and composition of block copolyesters have been characterized with respect to the molecular weight by NMR spectroscopy and thermal analysis. Copolymerization is typically living, so that block copolyesters have been synthesized with predictable molecular weight and composition. The inherent insolubility of polyglycolide block is responsible for the heterogeneity of the polymerization medium and formation of stable, non-aqueous colloidal dispersions. This effect is especially pronounced at high GA/ϵ-CL molar ratios. Colloidal dispersions have been analyzed by transmission electron microscopy (TEM) and photocorrelation spectroscopy (PCS). 相似文献