排序方式: 共有21条查询结果,搜索用时 15 毫秒
11.
Eimutis Juzeliūnas Yu Pei Ma John P. Wikswo 《Journal of Solid State Electrochemistry》2006,10(9):700-707
SQUID (Superconducting QUantum Interference Device) magnetometer operating in liquid helium with a special resolution of ca. 1 mm was used to study the magnetic fields produced by corrosion reactions under electrolyte flow conditions. Macroscopic magnetic field images were obtained on AA 2024 samples corroding in naturally aerated and oxygen-saturated NaCl solutions and 0.1 M NaOH. The fields originated from the macroscopic surface currents (ionic and electronic), which appear due to corrosion potential differences that resulted from differences in electrolyte flow characteristics (velocity, direction, and turbulence). The measurements demonstrated SQUID capability of remote corrosion sensing across the integrated media consisting of gaseous and solid dielectrics, metal, and electrolyte. The results have shown the potential of magnetometry for practical corrosion detection in the restricted locations (“hidden” corrosion) where solution flow is applied. 相似文献
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The structural and electronic transport properties of La1−x
Ce
x
MnO3 (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with
Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration
up to 50% doping. The system La0.5Ce0.5MnO3 also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition. 相似文献
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Darby SG Moore MR Friedlander TA Schaffer DK Reiserer RS Wikswo JP Seale KT 《Lab on a chip》2010,10(23):3218-3226
We describe the design, fabrication, and testing of a microfabricated metering rotary nanopump for the purpose of driving fluid flow in microfluidic devices. The miniature peristaltic pump is composed of a set of microfluidic channels wrapped in a helix around a central camshaft in which a non-cylindrical cam rotates. The cam compresses the helical channels to induce peristaltic flow as it is rotated. The polydimethylsiloxane (PDMS) nanopump design is able to produce intermittent delivery or removal of several nanolitres of fluid per revolution as well as consistent continuous flow rates ranging from as low as 15 nL min(-1) to above 1.0 μL min(-1). At back pressures encountered in typical microfluidic devices, the pump acts as a high impedance flow source. The durability, biocompatibility, ease of integration with soft-lithographic fabrication, the use of a simple rotary motor instead of multiple synchronized pneumatic or mechanical actuators, and the absence of power consumption or fluidic conductance in the resting state all contribute to a compact pump with a low cost of fabrication and versatile implementation. This suggests that the pump design may be useful for a wide variety of biological experiments and point of care devices. 相似文献
15.
Jérôme JP. Leon 《Letters in Mathematical Physics》1981,5(1):75-80
We establish a transformation which connects the potentials of the one-dimensional Dirac and Klein-Gordon operators. This transformation links the solutions of the nonlinear evolution equations solvable by means of the two inverse spectral transforms which use the Dirac and Klein-Gordon direct and inverse spectral problems. 相似文献
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Effects of flow and diffusion on chemotaxis studies in a microfabricated gradient generator 总被引:2,自引:0,他引:2
An understanding of chemotaxis at the level of cell-molecule interactions is important because of its relevance in cancer, immunology, and microbiology, just to name a few. This study quantifies the effects of flow on cell migration during chemotaxis in a microfluidic device. The chemotaxis gradient within the device was modeled and compared to experimental results. Chemotaxis experiments were performed using the chemokine CXCL8 under different flow rates with human HL60 promyelocytic leukemia cells expressing a transfected CXCR2 chemokine receptor. Cell trajectories were separated into x and y axis components. When the microchannel flow rates were increased, cell trajectories along the x axis were found to be significantly affected (p < 0.05). Total migration distances were not affected. These results should be considered when using similar microfluidic devices for chemotaxis studies so that flow bias can be minimized. It may be possible to use this effect to estimate the total tractile force exerted by a cell during chemotaxis, which would be particularly valuable for cells whose tractile forces are below the level of detection with standard techniques of traction-force microscopy. 相似文献
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Werdich AA Lima EA Ivanov B Ges I Anderson ME Wikswo JP Baudenbacher FJ 《Lab on a chip》2004,4(4):357-362
A hybrid chip is described which combines a microfluidic network fabricated in a silicone elastomer (PDMS) with planar microelectrodes. It was used to measure extracellular potentials from single adult murine cardiac myocytes in a restricted extracellular space. The recorded variations in the extracellular potentials were caused by transmembrane currents associated with spontaneously initiated intracellular calcium waves. Single cells were trapped inside the 100 pl microchamber by pressure gradients and maintained for several hours by continuous perfusion. In addition, the localized delivery of drugs to a portion of the cell was demonstrated. The impedance of the electrodes was reduced by a factor of 10 to 20 after the electrodeposition of platinum black. Biopotentials recorded from single cells with platinum black electrodes showed a three-fold decrease in the noise, resulting in a maximum signal-to-noise ratio of 15:1. Characteristic variations in the frequency and shape of the extracellular potentials were observed among different cells which are most likely due to differences in the sarcoplasmic reticulum Ca(2+) load. Our device architecture permits the integration of electrochemical and optical sensors for multiparameter recordings. 相似文献
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Vortex filament-filament interactions are believed to underlie lethal arrhythmias in cardiac tissue but their dynamics remain poorly understood. We numerically replicate an experimentally postulated reentrant filament configuration as a pair of adjacent circular filaments (scroll rings) with common symmetry axes and varying initial radii and separation distances. The interaction properties are quantified in terms of the scroll-ring lifetime T(L) and direction of initial velocity V0. Two cases were examined, differing only in the direction of the wave around the filament, and observed drastic differences in T(L) between the cases as the separation distance between the rings was decreased. We conclude that ring interactions present unexpected behaviors associated with competing interaction and decay mechanisms. 相似文献