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171.
Heather J. Avens Erin L. Chang Allison M. May Brad J. Berron Gregory J. Seedorf Vivek Balasubramaniam Christopher N. Bowman 《Journal of nanoparticle research》2011,13(1):331-346
Incorporation of nanoparticles (NPs) into polymer films represents a valuable strategy for achieving a variety of desirable
physical, optical, mechanical, and electrical attributes. Here, we describe and characterize the creation of highly fluorescent
polymer films by entrapment of fluorescent NPs into polymer matrices through surface-mediated eosin photoinitiation reactions.
Performing surface-mediated polymerizations with NPs combines the benefits of a covalently anchored film with the unique material
properties afforded by NPs. The effects of monomer type, crosslinker content, NP size, and NP surface chemistry were investigated
to determine their impact on the relative amount of NPs entrapped in the surface-bound films. The density of entrapped NPs
was increased up to 6-fold by decreasing the NP diameter. Increasing the crosslinking agent concentration enabled a greater
than 2-fold increase in the amount of NPs entrapped. Additionally, the monomer chemistry played a significant role as poly(ethylene
glycol) diacrylate (PEGDA)-based monomer formulations entrapped a 10-fold higher density of carboxy-functionalized NPs than
did acrylamide/bisacrylamide formulations, though the latter formulations ultimately immobilized more fluorophores by generating
thicker films. In the context of a polymerization-based microarray biodetection platform, these findings enabled tailoring
of the monomer and NP selection to yield a 200-fold improvement in sensitivity from 31 (±1) to 0.16 (±0.01) biotinylated target
molecules per square micron. Similarly, in polymerization-based cell staining applications, appropriate monomer and NP selection
enabled facile visualization of microscale, sub-cellular features. Careful consideration of monomer and NP selection is critical
to achieve the desired properties in applications that employ surface-mediated polymerization to entrap NPs. 相似文献
172.
This paper deals with the synchronization control problem for the uncertain chaotic neural networks with randomly occurring uncertainties and randomly occurring control gain fluctuations. By introducing an improved Lyapunov–Krasovskii functional and employing reciprocally convex approach, a delay-dependent non-fragile output feedback controller is designed to achieve synchronization with the help of a drive–response system and the linear matrix inequality approach. Finally, numerical results and its simulations are given to show the effectiveness of the derived results. 相似文献
173.
The design and development of novel squaraine dyes as sensitisers for photodynamic therapy (PDT) applications has grown tremendously in the last decade from the time when a squaraine dye was proposed to be a potential candidate, to-date when the use of such dyes have been demonstrated in animal models for skin cancer. This perspective article highlights the basic design, tuning of absorption, triplet excited state and two-photon absorption properties and recent developments of the squaraines as PDT sensitisers. 相似文献
174.
Proper alignment of air-coupled ultrasonic transducers for generation and reception of Lamb waves is vital in order to acquire a high amplitude wave group. Any misalignment with either the transmitter or the receiver or both adversely influences the amplitude of a Lamb mode. This paper reports a systematic attempt to quantify the reduction in the amplitude of the fundamental anti-symmetric Lamb mode (Ao) in a metal plate caused by misalignments in air-coupled probes. Three different types of misalignments – linear, orientation and synchronised orientation were deliberately introduced in the transducers, and experiments were performed on a 6 mm thick aluminium plate. Amplitudes of Ao mode measured at various configurations were normalised with that of Ao mode, captured in a reference configuration. Suitable curves fitted over the experimental data points revealed that Gaussian curves represent appropriately the variations in normalised amplitudes of Ao mode. Moreover, analytical expressions were derived to predict the difference in arrival times of Lamb mode(s) due to orientation and synchronised orientation misalignments. 相似文献
175.
M. Syed Ali P. Balasubramaniam 《Communications in Nonlinear Science & Numerical Simulation》2009,14(6):2776-2783
In this paper, the global stability problem of uncertain Takagi–Sugeno (T–S) fuzzy Hopfield neural networks with time delays (TSFHNNs) is considered. A novel LMI-based stability criterion is obtained by using Lyapunov functional theory to guarantee the asymptotic stability of TSFHNNs. Here, we choose a generalized Lyapunov functional and introduce a parameterized model transformation with free weighting matrices to it, in order to obtain generalized stability region. In fact, these techniques lead to generalized and less conservative stability condition that guarantee the wide stability region. The proposed stability conditions are demonstrated with four numerical examples. Comparison with other stability conditions in the literature shows our conditions are the more powerful ones to guarantee the widest stability region. 相似文献
176.
Jayaram K. Sankaran 《Mathematical Programming》1993,61(1-3):171-195
This paper addresses the problem of minimizing the number of columns with superdiagonal nonzeroes (viz., spiked columns) in a square, nonsingular linear system of equations which is to be solved by Gaussian elimination. The exact focus is on a class of min-spike heuristics in which the rows and columns of the coefficient matrix are first permuted to block lower-triangular form. Subsequently, the number of spiked columns in each irreducible block and their heights above the diagonal are minimized heuristically.We show that ifevery column in an irreducible block has exactly two nonzeroes, i.e., is a doubleton, then there is exactly one spiked column. Further, if there is at least one non-doubleton column, there isalways an optimal permutation of rows and columns under whichnone of the doubleton columns are spiked.An analysis of a few benchmark linear programs suggests that singleton and doubleton columns can abound in practice. Hence, it appears that the results of this paper can be practically useful. In the rest of the paper, we develop a polynomial-time min-spike heuristic based on the above results and on a graph-theoretic interpretation of doubleton columns. 相似文献
177.
C. Jayaram 《Czechoslovak Mathematical Journal》2002,52(3):585-593
In this paper we study primary elements in Prüfer lattices and characterize -lattices in terms of Prüfer lattices. Next we study weak ZPI-lattices and characterize almost principal element lattices and principal element lattices in terms of ZPI-lattices. 相似文献
178.
Rajesh B Thampi KR Bonard JM Mathieu HJ Xanthopoulos N Viswanathan B 《Chemical communications (Cambridge, England)》2003,(16):2022-2023
Pt nanoparticle-supported conducting nanotubules of polypyrrole prepared by a template method exhibited excellent catalytic activity and stability for the electrooxidation of methanol in comparison to Pt supported on conventionally synthesised conducting polypyrrole. 相似文献
179.
180.
K. G. Prasad R. P. Sharma B. Jayaram S. K. Agarwal A. Gupta A. V. Narlikar R. Srinivasan 《Hyperfine Interactions》1989,50(1-4):543-553
Mössbauer spectra of YBa2?x Sn x Cu3O7?δ compounds withx=0.2 and 0.3 have revealed two components, both with isomer shifts corresponding to 4+ valency for Sn. The temperature dependence of the area of only one component shows an anomaly near the superconducting temperature for both samples, thus suggesting anisotropic behaviour for the lattice rigidity. In the case ofx=0.2 sample X-ray diffraction studies further indicate similar anomaly in the orthorhombic strain. It is concluded that such anomalies are precursors for the superconductivity to occur in these compounds. 相似文献