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排序方式: 共有690条查询结果,搜索用时 15 毫秒
61.
We report a mechanistic study of how flow and recirculation in a microreactor can be used to optimize the capture and release of stimuli-responsive polymer-protein reagents on stimuli-responsive polymer-grafted channel surfaces. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted to polydimethylsiloxane (PDMS) channel walls, creating switchable surfaces where PNIPAAm-protein conjugates would adhere at temperatures above the lower critical solution temperature (LCST) and released below the LCST. A PNIPAAm-streptavidin conjugate that can capture biotinylated antibody-antigen targets was first characterized. The conjugate's immobilization and release were limited by mass transport to and from the functionalized PNIPAAm surface. Transport and adsorption efficiencies were dependent on the aggregate size of the PNIPAAm-streptavidin conjugate above the LCST and also were dependent on whether the conjugates were heated in the presence of the stimuli-responsive surface or pre-aggregated and then flowed across the surface. As conjugate size increased, through the addition of non-conjugated PNIPAAm, recirculation and mixing were shown to markedly improve conjugate immobilization compared to diffusion alone. Under optimized conditions of flow and reagent concentrations, approximately 60% of the streptavidin conjugate bolus could be captured at the surface and subsequently successfully released. The kinetic release profile sharpness was also strongly improved with recirculation and helical mixing. Finally, the concentration of protein-polymer conjugates could be achieved by continuous conjugate flow into the heated recirculator, allowing nearly linear enrichment of the conjugate reagent from larger volumes. This capability was shown with anti-p24 HIV monoclonal antibody reagents that were enriched over 5-fold using this protocol. These studies provide insight into the mechanism of smart polymer-protein conjugate capture and release in grafted channels and show the potential of this purification and enrichment module for processing diagnostic samples. 相似文献
62.
M. Ali HaiderAaron J. Capizzi Mitsuhiro MurayamaSteven McIntosh 《Solid State Ionics》2011,196(1):65-72
La0.6Sr0.4CoxFe1−xO3−δ (LSCF), La0.6Sr0.4Cu0.2Fe0.8O3−δ, Ba0.5Sr0.4Co0.8Fe0.2O3−δ and LaFeO3−δ nanoparticles were synthesized by a reverse micelle procedure. Controlling the size of the micelles through the water:oil phase ratio enabled synthesis of phase pure perovskite particles with average sizes from 14 nm to 50 nm. Small amounts of an impurity phase, likely cobalt oxide, were detected in the XRD spectrum of high cobalt content samples of LSCF (x = 0.8). La0.6Sr0.4Co0.2Fe0.8O3−δ nanoparticles were utilized to coat the surface of a dense thin-film La0.6Sr0.4Co0.2Fe0.8O3−δ solid oxide fuel cell cathode. The polarization resistance of the nanoparticle coated electrode, measured at open circuit in air at 973 K, was 20% lower than an equivalent un-coated electrode. 相似文献
63.
Akira Zenidaka Toshiyuki Honda Mitsuhiro Terakawa 《Applied Physics A: Materials Science & Processing》2011,105(2):393-398
We describe the physics of the SERS based on the optical near-field intensity enhancement on the metallic (plasmonic) and
the nonmetallic (Mie scattering) nanostructured substrates with two-dimensional (2D) periodic nanohole arrays. The calculation
by the Finite-Difference Time-Domain (FDTD) method revealed that the optical intensity enhancement increases with the increase
of the thickness of a gold film coating on the nonmetallic (dielectric) nanostructured Si, GaAs, and SiC substrates. The resonance
spectrum shifts with the changes in the geometrical structure of the void diameter and inter-void distance. It was clarified
that the optical intensity enhancement obtained with the gold-coated substrate is equivalent to that with a gold substrate
at 70-nm thick gold coating on the dielectric substrates in this structure. The resonance spectral bandwidth for Mie scattering
and plasmonic near-fields is different. Therefore, if the Stokes line of the Raman scattering is located within the resonance
bandwidth, the SERS signal is enhanced proportionally to the fourth power of the electric near-field. However, if the Stokes
shift is located out of the resonance bandwidth, the SERS signal enhancement is only proportional to the square of the scattered
near-field. 相似文献
64.
Amal Kaddoumi Mitsuhiro Wada Kenichiro Nakashima 《Biomedical chromatography : BMC》2011,25(5):579-587
N‐Nitrosofenfluramine (N‐Fen), a synthetic adulterant in Chinese herbal diet products, is believed to cause hepatotoxicity in people who use these products. N‐Fen is a relatively new compound, and thus pharmacological and toxicological studies are insufficient. The aim of this work was to (1) define N‐Fen's plasma pharmacokinetics and tissue distribution after single intraperitoneal (i.p.) administration of 25 mg/kg to rats; (2) define its bioavailability; and (3) identify fenfluramine (Fen) and norfenfluramine (Norf) as N‐Fen metabolites. N‐Fen rapidly appeared in the circulation and was distributed to all tissues. Norf was found to be the primary metabolite and not Fen. Plasma and tissue levels of N‐Fen and Norf were low with bioavailability of N‐Fen after i.p. administration was <3%. The AUC0−t of N‐Fen in the liver and kidney were 6.6 and 12.1 times, respectively, greater than the brain, and 17.8 and 32.6 times, respectively, greater than the plasma. In conclusion, N‐Fen did not show local accumulation in the liver, the site of toxicity, with concentrations represented as percentage of the total dose ranginng from 0.008 to 0.122%; hence the cause of hepatotoxicity could be related to the mechanisms other than toxicity consequences accumulation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
65.
66.
67.
Mitsuhiro Hirata Yutaka Abe Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2010,48(20):4385-4392
Various star‐shaped poly(phenoxy propylene sulfide)s (PPSs) bearing curable end groups were synthesized by the functionalization of the propagating ends of star‐shaped poly(PPS) with various electrophilies. The functionalization with chloromethyl styrene proceeded quantitatively, and afforded polymers with Mn almost agreed with theoretical value and narrow Mw/Mn. The photocuring conditions were optimized, and the addition of 10 wt % of poly(ethylene glycol) diacrylate was effective to attain sufficient crosslinking. The photocuring reaction of the end‐functionalized poly(PPS) films cast on silicon wafers was conducted by UV irradiation. The cured poly (PPS)s became insoluble in THF, supporting the sufficient crosslinking. Developing of a cured polymer yielded a negative photoresist pattern. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
68.
69.
Speckle Velocimetry or high-image density PIV gives a velocity vector map of a twodimensional flow field by point-by-point spatial frequency analysis of local pattern at an interrogation spot in a double- or a multiple-exposed image of laser speckle or pseudo-speckle pattern generated by pulsed laser-light-sheet illuminations of a plane in the flow densely seeded with fine particles. The whole field spatial frequency analysis of the double- or multiple-exposed PIV image gives more useful information of the flow field. Optical Fourier transform is a conventional technique not only for the local spatial frequency analysis but for the whole field analysis. Filtering of spatial frequency is one of the typical techniques for the latter which can reconstruct a velocity contour or a component velocity contour map of the flow. Fundamentally this technique is a simple and efficient analogue method to get more information in the velocity field analysis of the flow than a digital image processing, but in practical applications the measurement is restricted to simple flows because of optical noise and low spatial resolution. In order to improve the technique, the fundamental characteristics of the filtering and the noise yielded in the filtering process must be investigated. Meanwhile, wavelet analysis can also be applied to the whole field spatial frequency analysis of PIV image. In this paper the filtering technique is examined by numerical convolution integral, and the results obtained are compared with ones obtained by the wavelet analysis. 相似文献
70.
Mitsuhiro T. Nakao Yoshitaka Watanabe 《Journal of Computational and Applied Mathematics》1994,50(1-3):401-410
This paper is an extension of the preceding study (Nakao, this journal, 1991) in which we described a numerical verification method of the solution for one-space dimensional parabolic problems, to the several-space dimensional case. Here, numerical verification means the automatic proof of the existence of solutions to the problems by some numerical techniques on a computer. We reformulate the verification condition for nonlinear parabolic initial boundary value problems using the fixed-point problem of a compact operator on certain function spaces. As in the preceding study based upon a simple C0 finite-element approximation and its constructive a priori error estimates, a numerical verification procedure is presented with some numerical examples. 相似文献