Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a f...
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Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.
作者：
Yoo, Jung-WooChen, Chia-YiJang, H. W.Bark, C. W.Prigodin, V. N.Eom, C. B.Epstein, A. J.Department of Physics
The Ohio State University Columbus Ohio 43210-1117 USAJung-Woo YooV. N. Prigodin &A. J. EpsteinDepartment of Chemistry The Ohio State University Columbus Ohio 43210-1173 USAJung-Woo Yoo &A. J. EpsteinChemical Physics Program The Ohio State University Columbus Ohio 43210-1106 USAChia-Yi ChenDepartment of Materials Science and Engineering University of Wisconsin–Madison Madison Wisconsin 53706-1595 USAH. W. JangC. W. Bark &C. B. Eom
An important component of spintronics devices is the magnetic electrode, which is usually made from an inorganic alloy. However, an organic-based spin polarizer is now demonstrated, opening new possibilities for devel...
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An important component of spintronics devices is the magnetic electrode, which is usually made from an inorganic alloy. However, an organic-based spin polarizer is now demonstrated, opening new possibilities for developing organic/inorganic hybrid spintronics devices.
In this paper, a novel microelectrical impedance spectroscopy (μEIS) with three-dimensional interdigitated electrodes (3D-IDE) is developed to differentiate normal and cancerous cells. The device utilizes a microflui...
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In this paper, a novel microelectrical impedance spectroscopy (μEIS) with three-dimensional interdigitated electrodes (3D-IDE) is developed to differentiate normal and cancerous cells. The device utilizes a microfluidic tunnel structure, which forces cells to be squeezed. Thus, the enlarged contact area between cells and electrodes allows the device to measure the intrinsic electrical signal of the cells with a higher sensitivity than a noncontact case. The cell squeezing is realized by fabricating smaller microfluidic channel than cell size. The electrical impedances are measured through 3D-IDE. The device well distinguishes normal human breast cell (MCF-10A) and early-stage human breast cancer cell (MCF-7) with a phase difference of 1.42° at 500 kHz. The proposed device also features a high repeatability because the phase change is as small as 0.27° (which is sufficiently smaller than the phase difference between normal and cancer cell) before and after the each cell assay.
Magnetotransport measurements and x-ray photoemission spectroscopy were used to investigate the surface conductivity of ZnO. Near-surface downward band bending, consistent with electron accumulation, was found on the ...
Magnetotransport measurements and x-ray photoemission spectroscopy were used to investigate the surface conductivity of ZnO. Near-surface downward band bending, consistent with electron accumulation, was found on the polar and nonpolar faces of bulk ZnO single crystals. A significant polarity effect was observed in that the downward band bending was consistently stronger on the Zn-polar face and weaker on the O-polar face. The surface electron accumulation layer was found to significantly influence the electrical properties of high resistivity, hydrothermally grown bulk ZnO crystals at temperatures below 200 K, and is largely responsible for the anomalously low electron mobility reported for this material.
The present study explains the morphogenesis of maze-like magnetic domains in amorphous Tb-Fe films. It is shown that the observed morphological complexity of the maze-like patterns (which arise due to out-of-plane an...
The present study explains the morphogenesis of maze-like magnetic domains in amorphous Tb-Fe films. It is shown that the observed morphological complexity of the maze-like patterns (which arise due to out-of-plane anisotropy) is superficial and can be explained by simple geometrical rules based on magnetostatic interactions between domains. Morphogenesis in applied field occurs in a fractal-like manner through growth of self-similar reversed domains of various shapes at progressively smaller length scales; the field-dependent fractal dimensions are quantified. The microscopic changes in domain morphology manifest as distinct kinks or “knees” in the macroscopic magnetization curves. Highly aligned synthetic patterns can be formed in microfabricated films, illustrating the potential for “domain engineering” for controlled magnetoelastic response.
We employ a parallel, three-dimensional level-set code to simulate the dynamics of isolated dislocation lines and loops in an obstacle-rich environment. This system serves as a convenient prototype of those in which e...
We employ a parallel, three-dimensional level-set code to simulate the dynamics of isolated dislocation lines and loops in an obstacle-rich environment. This system serves as a convenient prototype of those in which extended, one-dimensional objects interact with obstacles and the out-of-plane motion of these objects is key to understanding their pinning-depinning behavior. In contrast to earlier models of dislocation motion, we incorporate long-ranged interactions among dislocation segments and obstacles to study the effect of climb on dislocation dynamics in the presence of misfitting penetrable obstacles/solutes, as embodied in an effective climb mobility. Our main observations are as follows. First, increasing climb mobility leads to more effective pinning by the obstacles, implying increased strengthening. Second, decreasing the range of interactions significantly reduces the effect of climb. The dependence of the critical stress on obstacle concentration and misfit strength is also explored and compared with existing models. In particular, our results are shown to be in reasonable agreement with the Friedel-Suzuki theory. Finally, the limitations inherent in the simplified model employed here, including the neglect of some lattice effects and the use of a coarse-grained climb mobility, are discussed.
Heteroepitaxial growth of m -plane (10 1- 0) InN film on (100) -γ -LiAlO2 (LAO) substrate has been realized by plasma-assisted molecular-beam epitaxy. Surface treatment of LAO substrate plays an important role in con...
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In common with many other structured fluids, block copolymers can be effectively oriented by shear. This susceptibility to shear alignment has previously been shown to hold even in thin films, containing as few as two...
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In common with many other structured fluids, block copolymers can be effectively oriented by shear. This susceptibility to shear alignment has previously been shown to hold even in thin films, containing as few as two layers of spherical microdomains, or even a single layer of cylindrical microdomains. A phenomenological model has been proposed [M. W. Wu, R. A. Register, and P. M. Chaikin, Phys. Rev. E 74, 040801(R) (2006)] to describe the alignment of such block-copolymer films, yielding the microdomain lattice order parameter as a function of shearing temperature, stress, and time. Here we directly test the central idea of that model, that the grains which are most misaligned with the shear direction are selectively destroyed, to reform in a direction more closely aligned with the shear. Films are first shear aligned from a polygrain state into a monodomain orientation and are then subjected to a second shear, at a variable stress (σ) and misorientation angle (δθ) relative to the monodomain director, allowing the effects of σ and δθ to be independently and systematically probed. For both cylinder-forming and sphere-forming block copolymers, these experiments confirm the basic premise of the model, as the stress required for realignment increases monotonically as δθ becomes smaller. For a cylinder-forming block copolymer, we find that the characteristic stress σc required to realign cylinders from one monodomain orientation to another is indistinguishable from that required to generate a monodomain orientation from the polygrain state. By contrast, the hexagonal lattice of spheres requires a value of σc more than 3 times as high for reorientation than for generation of the initial monodomain orientation.
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