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Annual International Conference of the IEEE engineering in Medicine and Biology Society

作者： Ruiqi Long Mike McShane Department of Biomedical Engineering Texas A&M University College Station TX 77843 USA Department of Biomedical Engineering and Materials Science and Engineering Program Texas A&M University College Station TX 77843 USA.

ISBN: (纸本)9781424441198

Ratiometric luminescent microparticle sensors have been developed for sensing biochemical targets such as glucose in interstitial fluid, enabling use of dermal implants for on-demand monitoring. For these sensor systems to be deployed in vivo, a matched optoelectronic system for interrogation of dermally-implanted sensors was previously designed, constructed, and evaluated experimentally. During evaluation experiments, it revealed that the system efficiency was compromised by losses due to fiber connections of a commercial spectrometer. In this work, a high-throughput spectral system was presented to solve the photon loss problem. This system was designed, constructed, and tested. The throughput was around hundred time more than the previous system we used, and it was cost-effective, as well. It enables use of an integrated system for excitation, collection and measurement of luminescent emission, and will be used as a tool for in vivo studies with animal models or human subjects.

关键词： Ratiometric microparticle luminescent

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Optical generation of crystalline, quasicrystalline, and arbitrary arrays of torons in confined cholesteric liquid crystals for patterning of optical vortices in laser beams

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Physical Review E 2012年第2期86卷 021703-021703页

作者： Paul J. Ackerman Zhiyuan Qi Ivan I. Smalyukh Department of Physics University of Colorado Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering Liquid Crystal Materials Research Center and Materials Science and Engineering Program University of Colorado Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA

Condensed matter systems with topological defects in the ground states range from the Abrikosov phases in superconductors, to various blue phases and twist grain boundary phases in liquid crystals, and to phases of skyrmion lattices in chiral ferromagnets and Bose-Einstein condensates. In nematic and chiral nematic liquid crystals, which are true fluids with long-range orientational ordering of constituent molecules, point and line defects spontaneously occur as a result of symmetry-breaking phase transitions or due to flow, but they are unstable, hard to control, and typically annihilate with time. Here we describe the optical generation of two-dimensional crystalline, quasicrystalline, and arbitrary ensembles of particlelike structures manifesting both skyrmionlike and Hopf fibration features—dubbed “torons”—composed of looped double twist cylinders and point defects embedded in a uniform director field. In these two-dimensional lattices, we then introduce various dislocations, defects in positional ordering of the torons. We show that the periodic defect lattices with and without dislocation are light- and voltage-tunable reconfigurable two-dimensional diffraction gratings and can be used to generate various controlled phase singularities in the diffracted laser beams. The results of computer simulations of optical images, diffraction patterns, and phase distributions with optical vortices are in a good agreement with the corresponding experimental findings.

关键词： QUASICRYSTALS CONDENSED matter CRYSTAL grain boundaries PHASE transformations (Physics) LIQUID crystals CRYSTAL optics BROKEN symmetry (Physics) LASER beams SUPERCONDUCTORS

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Potential bone replacement materials prepared by two methods

Potential bone replacement materials prepared by two methods

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2011 MRS Fall Meeting

作者： Lee, Steve Porter, Michael Wasko, Scott Lau, Grace Chen, Po-Yu Novitskaya, Ekaterina E. Tomsia, Antoni P. Almutairi, Adah Meyers, Marc A. McKittrick, Joanna University of California San Diego Materials Science and Engineering Program 9500 Gilman Dr. San Diego CA 92093 United States University of California San Diego Skaggs School of Pharmacy 9500 Gilman Dr. San Diego CA 92093 United States Lawrence Berkeley National Laboratory 1 Cyclotron Rd. Berkeley CA 94720 United States National Tsing Hua University Department of Materials Science and Engineering Hsinchu 30013 Taiwan University of California San Diego Dept. of Mechanical and Aerospace Engineering 9500 Gilman Dr. San Diego CA 92093 United States

ISBN: (纸本)9781605113951

Natural and synthetic hydroxyapatite (HA) scaffolds for potential load-bearing bone implants were fabricated by two methods. The natural scaffolds were formed by heating bovine cancellous bone at 1325°C, which removed the organic and sintered the FIA. The synthetic scaffolds were prepared by freeze-casting HA powders, using different solid loadings (20-35 vol.%) and cooling rates (1-10°C/min). Both types of scaffolds were infiltrated with polymethylmethacrylate (PMMA). The porosity, pore size, and compressive mechanical properties of the natural and synthetic scaffolds were investigated and compared to that of natural cortical and cancellous bone. Prior to infiltration, the sintered cancellous scaffolds exhibited pore sizes of 100 - 300 μm, a strength of 0.4-9.7 MPa, and a Young's modulus of 0.1-1.2 GPa. The freeze-casted scaffolds had pore sizes of 10-50 μm, strengths of 0.7-95.1 MPa, and Young's moduli of 0.1-19.2 GPa. When infiltrated with PMMA, the cancellous bone-PMMA composite showed a strength of 55 MPa and a Young's modulus of 4.5 GPa. Preliminary data for the synthetic HA-PMMA composite showed a strength of 42 MPa and a modulus of 0.8 GPa. © 2012 materials Research Society.

关键词： Pore size

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Fabrication of Graphene By Electrochemical Exfoliation in Alkaline Electrolytes

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ECS Meeting Abstracts 2013年第41期MA2013-02卷

作者： Li-Chung Chang Yu-Chi Hsieh Yong-Min Chen Pu-Wei Wu Jyh-Fu Lee Graduate Program for Science and Technology of Accelerator Light Source National Chiao Tung University 1001 Ta Hsueh Road Hsinchu City Taiwan 300 Department of Materials Science and Engineering National Chiao Tung University 1001 Ta Hsueh Road Hsinchu City Taiwan 300 National Synchrotron Radiation Research Center 101 Hsin-Ann Road Hsinchu Science Park Hsin-Chu 30076 Taiwan ROC

Abstract not Available.

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Diabetes diagnosis by direct measurement from urine odor using electronic nose

Diabetes diagnosis by direct measurement from urine odor usi...

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Biomedical engineering International Conference (BMEiCON)

作者： Satetha Siyang Chatchawal Wongchoosuk Teerakiat Kerdcharoen Materials science and Engineering Program Faculty of Science Mahidol University Bangkok Thailand NANOTEC Center of Excellent National Nanotechnology Center Department of Physicsand Center of Nanoscience and Nanotechnology Faculty of Science Mahidol University Thailand Department of Physics Faculty of Science Kasetsart University Bangkok Thailand

ISBN: (纸本)9781467348904

Diabetes is one of the most common chronic diseases and can occur at any age. To avoid many side effects of diabetes on health, early detection of diabetes is very necessary. In this paper, we propose an alternative method to detect diabetes based on direct measurement of urine odor by using an electronic nose (E-nose). Artificial urines, used to simulated a situation of diabetes patient, were produced by adding glucose into the pure urine samples. Eight commercial chemical gas sensors were used as the sensing elements of our e-nose. Principal components analysis (PCA) and cluster analysis (CA) methods were employed for data analysis. The PCA and CA results show that the proposed technique was able to identify the glucose concentration in urine. In the future, e-nose can be a potential tool for diabetes diagnosis by healthcare personnel as well as home users.

关键词： Sugar Diabetes Principal component analysis Temperature measurement Electronic noses Strips Temperature sensors

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Characterization of 4H Silicon Carbide Films Grown by Solvent-Laser Heated Floating Zone

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MRS Online Proceedings Library 2012年第1期1433卷 113-118页

作者： Woodworth, Andrew A. Sayir, Ali Neudeck, Philip G. Raghothamachar, Balaji Dudley, Michael NASA Postdoctoral Program Fellow NASA Glenn Research Center Cleveland USA NASA Glenn Research Center Cleveland USA Department of Materials Science & Engineering Stony Brook University Stony Brook USA

Commercially available bulk silicon carbide (SiC) has a high number (>2000/cm2) of screw dislocations (SD) that have been linked to degradation of high-field power device electrical performance properties. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce significantly higher quality bulk SiC. In order for this bulk growth method to become reality, growth of long single crystal SiC fibers must first be achieved. Therefore, a new growth method, Solvent-Laser Heated Floating Zone (Solvent-LHFZ), has been implemented. While some of the initial Solvent-LHFZ results have recently been reported, this paper focuses on further characterization of grown crystals and their growth fronts. To this end, secondary ion mass spectroscopy (SIMS) depth profiles, cross section analysis by focused ion beam (FIB) milling and mechanical polishing, and orientation and structural characterization by X-ray transmission Laue diffraction patterns and X-ray topography were used. Results paint a picture of a chaotic growth front, with Fe incorporation dependant on C concentration.

关键词： crystal growth crystallographic structure secondary ion mass spectroscopy (SIMS)

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Surface-tension-induced flattening of a nearly plane elastic solid

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Physical Review E 2012年第5期85卷 051602-051602页

作者： Anand Jagota Dadhichi Paretkar Animangsu Ghatak INM-Leibniz Institute for New Materials and Saarland University Campus D 2 2 66123 Saarbruecken Germany Department of Chemical Engineering and Bioengineering Program Lehigh University Bethlehem Pennsylvania 18015 United States Department of Chemical Engineering and Department of Science and Technology Unit on Nanoscience Indian Institute of Technology Kanpur 208016 India

We report direct measurement of surface deformation in soft solids due to their surface tension. Gel replicas of poly(dimethysiloxane) masters with rippled surfaces are found to have amplitudes that decrease with decreasing gel modulus. Surface undulations of a thin elastomeric film are attenuated when it is oxidized by brief exposure to oxygen plasma. Surface deformation in both cases is modeled successfully as driven by surface tension and resisted by elasticity. Our results show that surface tension of soft solids drives significant deformation, and that the latter can be used to determine the former.

关键词： SURFACE tension ELASTIC solids DEFORMATIONS (Mechanics) SILICONES ELASTOMERS PLASMA (Ionized gases)

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Power-Law Creep from Discrete Dislocation Dynamics

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Physical Review Letters 2012年第26期109卷 265504-265504页

作者： Shyam M. Keralavarma T. Cagin A. Arsenlis A. Amine Benzerga Department of Aerospace Engineering Texas A&M University College Station Texas 77843 USA Materials Science and Engineering Program Texas A&M University College Station Texas 77843 USA Department of Chemical Engineering Texas A&M University College Station Texas 77843 USA Lawrence Livermore National Laboratory Livermore California 94551 USA

We report two-dimensional discrete dislocation dynamics simulations of combined dislocation glide and climb leading to “power-law” creep in a model aluminum crystal. The approach fully accounts for matter transport due to vacancy diffusion and its coupling with dislocation motion. The existence of quasiequilibrium or jammed states under the applied creep stresses enables observations of diffusion and climb over time scales relevant to power-law creep. The predictions for the creep rates and stress exponents fall within experimental ranges, indicating that the underlying physics is well captured.

关键词： POWER law (Mathematics) ALUMINUM crystals GLIDE (Crystallography) CREEP (materials) RESEARCH DISLOCATIONS in crystals DISCRETE systems

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Hierarchical Structure of Porosity in Cortical and Trabecular Bones

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MRS Online Proceedings Library (OPL) 2012年第1期1420卷 mrsf11-1420-oo10-09-mrsf11-1420-oo10-09页

作者： Ekaterina Novitskaya Elham Hamed Jun Li Zherrina Manilay Iwona Jasiuk Joanna McKittrick University of California San Diego Materials Science and Engineering Program 9500 Gilman Dr. La Jolla CA 92093 USA University of Illinois at Urbana-Champaign Department of Mechanical Science and Engineering 1206 West Green Street Urbana IL 61801 USA University of California San Diego Department of Mechanical and Aerospace Engineering 9500 Gilman Dr. La Jolla CA 92093 USA

In this paper the amount and morphology of cortical and trabecular bone porosities were estimated using optical microscopy and micro-computed tomography technique. The hierarchical structure of porosity at different structural scales spanning from a single lacuna (sub-microscale) to trabecular or cortical bone levels (mesoscale) was characterized and described. This study was conducted by using samples of untreated, deproteinized and demineralized bones, to obtain better insight into the bone structure and porosities. The motivation of this work is that the porosity in bone has a major effect on its mechanical response, yet it is often neglected in bone models. Investigations of the mechanical properties of bone and its main components (collagen and mineral phases), complemented by modeling, are of importance in orthopedics.

关键词： bone porosity microstructure

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Graphene fillers for ultra-efficient thermal interface materials

Graphene fillers for ultra-efficient thermal interface mater...

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IEEE Silicon Nanoelectronics Workshop (SNW)

作者： K. M. F. Shahil V. Goyal R. Gulotty A. A. Balandin Nano-Device Laboratory Department of Electrical Engineering and Materials Science and Engineering Program University of California Riverside CA USA Intel Corporation Hillsboro OR USA Texas Instruments Inc. Dallas TX USA

Summary form only given. Continuous scaling of Si CMOS devices and circuits, increased speed and integration densities resulted in problems with thermal management of nanoscale device and computer chips. Further progress in information, communication and energy storage technologies requires more efficient heat removal methods and stimulates the search for thermal interface material (TIMs) with enhanced thermal conductivity. The commonly used TIMs are filled with the particles such as silver or silica. The conventional TIMs require high volume fractions of the filler (~70%) to achieve thermal conductivity of ~1-5 W/mK. Recently, some of us discovered that graphene has extremely high intrinsic thermal conductivity, which exceeds that of carbon nanotubes. To use this property for thermal management of nanoscale electronic devices, we utilized the inexpensive liquid-phase exfoliated graphene and multi-layer graphene (MLG) as filler materials in TIMs. The thermal properties of the obtained graphene-epoxy composites were measured using the “laser flash” technique. It was found that the thermal conductivity enhancement factor exceeded a factor of 23 at 10% of the graphene volume loading fraction. This enhancement is larger than anything that has been achieved using other fillers. We have also tested graphene flakes in the electrically-conductive hybrid graphene-metal particle TIMs. The thermal conductivity of resulting composites was increased by a factor of ~5 in a temperature range from 300 K to 400 K at a small graphene loading fraction of 5-vol.-%. The unusually strong enhancement of thermal properties was attributed to the high thermal conductivity of graphene, strong graphene coupling to matrix materials and the large range of the length-scale - from nanometers to micrometers - of the graphene and silver particle fillers. Graphene-based TIMs have a number of other advantages related to their viscosity and adhesion, which meet the industry requirements. Our results su

关键词： Thermal conductivity materials Conductivity Thermal engineering Thermal loading Loading

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