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排序方式: 共有634条查询结果,搜索用时 15 毫秒
31.
Jignasu P. Mehta Prashant N. Bhatt Sudhindra N. Misra 《中国稀土学报(英文版)》2006,24(6):648-652
Pr( Ⅲ ) and Nd( Ⅲ ) can be utilized as absorption spectroscopic probes to investigate the interaction of biomolecules like Lysozyme (HEW) with Ca( Ⅱ ) in-vitro ; the most abundant metal ion in the human body system. The spectroscopic techniques involving comparative absorption, absorption difference, and quantitative intensity analysis using 4f-4f transitions are utilized for changes in the inner sphere coordination pattern of Pr( Ⅲ ) and Nd(Ⅲ ) in solution as well as in solid state. The present study deals with an important biomolecule in human metabolism, that is, Lysozyme (HEW). The absorption er-Condon the probab spectral parameters such as the oscillator strength (P), the Judd-Ofelt (Tλ) intensity parameters, and the Slatinter electronic parameters are calculated using chi square methods. The obtained results are used to determine le geometry of the complex in the solution, the nature of the bond between Pr(Ⅲ)/Nd(Ⅲ) with lysozyme, and the inner sphere coordination environment of f-f transitions. The results obtained from various experimental conditions are utilized to investigate the coordination changes in the Pr(Ⅲ)/Nd(Ⅲ) complexes caused by different coordinating sites of lysozyme, normalized bite, denticity, the solvent nature, the coordination number, the nature of bond and other parameters to mimic the interaction of the Ca( Ⅱ ) ion with such biomolecule. 相似文献
32.
Various aspects of the mechanical behavior of kaolin clay are discussed in light of experimental observations from a series of strain controlled true triaxial undrained tests performed on cubical kaolin clay specimens with flocculated and dispersed microfabric, using a fully automated flexible boundary experimental setup with real-time feedback control system. The laboratory procedures used to prepare flocculated and dispersed microfabric specimens are presented. Mercury intrusion porosimetry is used to evaluate the pore structure of these specimens. The influence of microfabric on the consolidation behavior of kaolin clay is evaluated based on the data obtained from K0 consolidation during constant rate of strain tests and the isotropic consolidation during true triaxial tests. Undrained tests on kaolin clay show that the following vary with microfabric of specimen: The shear stiffness, excess pore pressure generated during shear, and strength and strain to failure. For both microfabrics, the observed strength behavior using cubical triaxial testing shows a similar pattern of variation with applied stress anisotropy; hence, only a marginal influence of fabric-induced anisotropy. 相似文献
33.
Sohee Kim Prashant Tathireddy Richard A Normann Florian Solzbacher 《IEEE transactions on neural systems and rehabilitation engineering》2007,15(4):493-501
A chronically implantable, wireless neural interface device will require integrating electronic circuitry with the interfacing microelectrodes in order to eliminate wired connections. Since the integrated circuit (IC) dissipates a certain amount of power, it will raise the temperature in surrounding tissues where it is implanted. In this paper, the thermal influence of the integrated 3-D Utah electrode array (UEA) device implanted in the brain was investigated by numerical simulation using finite element analysis (FEA) and by experimental measurement in vitro as well as in vivo. The numerically calculated and experimentally measured temperature increases due to the UEA implantation were in good agreement. The experimentally validated numerical model predicted that the temperature increases linearly with power dissipation through the UEA, with a slope of 0.029 degree C/mW over the power dissipation levels expected to be used. The influences of blood perfusion, brain metabolism, and UEA geometry on tissue heating were also investigated using the numerical model. 相似文献
34.
Approximate dynamic programming (ADP) commonly employs value function approximation to numerically solve complex dynamic programming problems. A statistical perspective of value function approximation employs a design and analysis of computer experiments (DACE) approach, where the “computer experiment” yields points on the value function curve. The DACE approach has been used to numerically solve high-dimensional, continuous-state stochastic dynamic programming, and performs two tasks primarily: (1) design of experiments and (2) statistical modeling. The use of design of experiments enables more efficient discretization. However, identifying the appropriate sample size is not straightforward. Furthermore, identifying the appropriate model structure is a well-known problem in the field of statistics. In this paper, we present a sequential method that can adaptively determine both sample size and model structure. Number-theoretic methods (NTM) are used to sequentially grow the experimental design because of their ability to fill the design space. Feed-forward neural networks (NNs) are used for statistical modeling because of their adjustability in structure-complexity . This adaptive value function approximation (AVFA) method must be automated to enable efficient implementation within ADP. An AVFA algorithm is introduced, that increments the size of the state space training data in each sequential step, and for each sample size a successive model search process is performed to find an optimal NN model. The new algorithm is tested on a nine-dimensional inventory forecasting problem. 相似文献
35.
36.
Healing substrates with mobile, particle-filled microcapsules: designing a 'repair and go' system. 下载免费PDF全文
Rolf Verberg Alex T Dale Prashant Kumar Alexander Alexeev Anna C Balazs 《Journal of the Royal Society Interface》2007,4(13):349-557
We model the rolling motion of a fluid-driven, particle-filled microcapsule along a heterogeneous, adhesive substrate to determine how the release of the encapsulated nanoparticles can be harnessed to repair damage on the underlying surface. We integrate the lattice Boltzmann model for hydrodynamics and the lattice spring model for the micromechanics of elastic solids to capture the interactions between the elastic shell of the microcapsule and the surrounding fluids. A Brownian dynamics model is used to simulate the release of nanoparticles from the capsule and their diffusion into the surrounding solution. We focus on a substrate that contains a damaged region (e.g. a crack or eroded surface coating), which prevents the otherwise mobile capsule from rolling along the surface. We isolate conditions where nanoparticles released from the arrested capsule can repair the damage and thereby enable the capsules to again move along the substrate. Through these studies, we establish guidelines for designing particle-filled microcapsules that perform a 'repair and go' function and thus, can be utilized to repair damage in microchannels and microfluidic devices. 相似文献
37.
Novel 1‐methoxycarbonylethylmethylphenylsulfonium salts with nonnucleophilic anions, namely, hexafluorophosphate, hexafluoroantimonate, and tetrafluoroborate, were synthesized by the reaction of 1‐methoxycarbonylethylphenylsulfide and dimethyl sulfate followed by anion exchange with potassium hexafluorophosphate, sodium hexafluoroantimonate, and sodium tetrafluoroborate, respectively. The cationic polymerization (photopolymerization and thermal polymerization) of epoxy and vinyl ether monomers was carried out to demonstrate the applicability of the newly synthesized sulfonium salts. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3157–3163, 2007 相似文献
38.
39.
Nanomechanical properties of indium nanowires like structures fabricated on quartz substrate by trench template technique,
measured using nanoindentation. The hardness and elastic modulus of wires were measured and compared with the values of indium
thin film. Displacement burst observed while indenting the nanowire. ‘Wire-only hardness’ obtained using Korsunsky model from
composite hardness. Nanowires have exhibited almost same modulus as indium thin film but considerable changes were observed
in hardness value. 相似文献
40.
Additively manufactured polymeric products for automotive, aerospace, and biomedical applications are usually intended for service in an outdoor environment with high mechanical loading conditions. The strength and sustainability of the products can be significantly degraded due to the outdoor environmental conditions such as UV light, moisture, heat, and so forth. In this research work, a novel weather-resistant polymer (WRP) material, that is, acrylonitrile styrene acrylate (ASA), has been studied. Furthermore, this work aims to study the effect of process parameters and enhance the strength of WRP (ASA) specimens using the FFF process. The optimized process parameters, that is, build orientation (BO), extrusion temperature (ET), layer thickness (LT), and printing speed (PS), were identified based on the tensile and flexural strength using the Taguchi technique and statistical analysis. The best tensile and flexural strengths for the specimen were achieved at both orientations (XYZ and ZXY) TS: 255°C ET, 0.14 mm LT, 50 mm/s PS; and FS: 245°C ET, 0.28 mm LT, 50 mm/s PS, respectively. Regression model was developed to investigate the correlation between the process parameters with tensile and flexural strength. A validation test confirmed the findings, and the error between the actual and predicted values is less than ±10%. 相似文献