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991.
Hyung Giun Kim Taeg Woo Lee Seung Zeon Han Kwangjun Euh Won-Yong Kim Sung Hwan Lim 《Metals and Materials International》2012,18(2):335-339
The effects of C-alloying on the microstructure and secondary phase particles of Cu-2.5Fe-0.1P cast alloy were investigated
by transmission electron microscopy (TEM), high-resolution electron microscopy (HREM), and image simulation. The mechanical
and electrical properties were slightly improved, and grain refinement and fine γ-Fe particles were evident. Additionally,
the Fe3P particles were characterized, and abnormally grown Fe3P particles were observed at the grain boundary in the non C-alloyed and C-alloyed specimens. 相似文献
992.
Ambient ionization imaging mass spectrometry is uniquely suited for detailed spatially resolved chemical characterization of biological samples in their native environment. However, the spatial resolution attainable using existing approaches is limited by the ion transfer efficiency from the ionization region into the mass spectrometer. Here, we present a first study of ambient imaging of biological samples using nanospray desorption ionization (nano-DESI). Nano-DESI is a new ambient pressure ionization technique that uses minute amounts of solvent confined between two capillaries comprising the nano-DESI probe and the solid analyte for controlled desorption of molecules present on the substrate followed by ionization through self-aspirating nanospray. We demonstrate highly sensitive spatially resolved analysis of tissue samples without sample preparation. Our first proof-of-principle experiments indicate the potential of nano-DESI for ambient imaging with a spatial resolution of better than 12 μm. The significant improvement of the spatial resolution offered by nano-DESI imaging combined with high detection efficiency will enable new imaging mass spectrometry applications in clinical diagnostics, drug discovery, molecular biology, and biochemistry. 相似文献
993.
We demonstrate a measurement apparatus to inspect spatial uniformity of quantum efficiency of solar cells using a beam projector. Deviation of irradiance from the used beam projector over the area of 1.5×0.8 m on the cell plane was flattened within ±2.6% through gray scale adjustment, which was originally about 200%. Scanning a small square image with an area of 3×3 mm over a square-shaped photovoltaic cell with an area of 15.6×15.6 cm, we could identify the locations according to efficiency level and showed that the cell had quantum efficiency deviation of more than 10%. Utilizing the advantageous feature of a projection display, we also demonstrated that this apparatus can inspect the spatial uniformity of solar modules and panels consisting of multiple solar cells. 相似文献
994.
Inverse extraction of cohesive zone laws by field projection method using numerical auxiliary fields
Hyun‐Gyu Kim Huck Beng Chew Kyung‐Suk Kim 《International journal for numerical methods in engineering》2012,91(5):516-530
The cohesive zone law relates the cohesive tractions with the cohesive separations within the fracture process zone of a material and is used to quantify the strength and toughness of the material. Determining the material's cohesive zone law, however, is a nontrivial inverse problem of finding unknown tractions and separations from measurement data. Previously, a field projection method was established to extract the cohesive zone laws from far‐field data using interaction J‐integrals between the physical field of interest and auxiliary analytical probing fields. Here, we extend the universality of the field projection method and its ease of numerical implementation by using numerical auxiliary fields. These numerical fields are generated by systematically imposing uniform surface tractions element‐by‐element along the crack faces in finite element models. Then, interaction J‐ and M‐integrals between these auxiliary probing fields and the measurement field are used to reconstruct the traction and separation relationship along the crack faces. The effectiveness of this method in extracting the cohesive zone law from measured displacements in the far‐field region is demonstrated through numerical experiments. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
Jaehyun Moon Joohyun Hwang Jin Woo Huh Jin-Wook Shin Doo-Hee Cho Seung Koo Park Jun-Han Han Chul Woong Joo Jeong-Ik Lee Hye Yong Chu 《Materials Research Bulletin》2012,47(10):2788-2791
A linear stability model was formulated to analyze the perturbation of solid polymer surfaces. Surface energy and thermal stress were considered as the main variables. The surface tends to more unstable as the temperature increase. This is interpreted as the dominancy of the lattice vacancy diffusion over surface mass diffusion and the increase in thermal stress. 相似文献
996.
997.
Yoon KJ Lee MH Kim GH Song SJ Seok JY Han S Yoon JH Kim KM Hwang CS 《Nanotechnology》2012,23(18):185202
A tri-stable memristive switching was demonstrated on a Pt/TiO?/Pt device and its underlying mechanism was suggested through a series of electrical measurements. Tri-stable switching could be initiated from a device in unipolar reset status. The unipolar reset status was obtained by performing an electroforming step on a pristine cell which was then followed by unipolar reset switching. It was postulated that tri-stable switching occurred at the location where the conductive filament (initially formed by the electroforming step) was ruptured by a subsequent unipolar reset process. The mechanism of the tri-stable memristive switching presented in this article was attributed to the migration of oxygen ions through the ruptured filament region and the resulting modulation of the Schottky-like interfaces. The assertion was further supported by a comparison study performed on a Pt/TiO?/TiO(2-x)/Pt cell. 相似文献
998.
999.
Yong Il Park Hyung Min Kim Jeong Hyun Kim Kyung Chul Moon Byeongjun Yoo Kang Taek Lee Nohyun Lee Yoonseok Choi Wooram Park Daishun Ling Kun Na Woo Kyung Moon Seung Hong Choi Hong Seok Park Soo‐Young Yoon Yung Doug Suh Sung Ho Lee Taeghwan Hyeon 《Advanced materials (Deerfield Beach, Fla.)》2012,24(42):5755-5761
1000.
Herman I Yeo J Hong S Lee D Nam KH Choi JH Hong WH Lee D Grigoropoulos CP Ko SH 《Nanotechnology》2012,23(19):194005
In this paper we have demonstrated the simple, low cost, low temperature, hydrothermal growth of weeping willow ZnO nano-trees with very long branches to realize high efficiency dye-sensitized solar cells (DSSCs). We also discuss the effects of branching on solar cell efficiency. By introducing branched growth on the backbone ZnO nanowires (NWs), the short circuit current density and the overall light conversion efficiency of the branched ZnO NW DSSCs increased to almost four times that for vertically grown ZnO NWs. The efficiency increase is attributed to the increase in surface area for higher dye loading and light harvesting and also to reduced charge recombination through direct conduction along the crystalline ZnO branches. As the length of the branches increased, the branches became flaccid and the increase in solar cell efficiency slowed down because the effective surface area increase was hindered by branch bundling during the drying process and subsequent decrease in the dye loading. 相似文献