We demonstrate the resonance wavelength and quality factor dependence of 50nm defect-hole placement within photonic crystal L3 microcavities. Proper placement of defect-holes leads to a 12% increase in photonic crysta...
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It is well known that variations in the microstructure of lead free solders greatly affect their thermomechanical properties. Sn grain size, orientation and number, as well as secondary Ag 3 Sn and Cu 6 Sn 5 precipit...
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It is well known that variations in the microstructure of lead free solders greatly affect their thermomechanical properties. Sn grain size, orientation and number, as well as secondary Ag 3 Sn and Cu 6 Sn 5 precipitate sizes and numbers, are all seen to influence the mechanical response of solder joints during isothermal and thermal cycling. The solidification temperature of a SnAgCu solder joint dramatically affects its microstructure. Generally, smaller solder balls (e.g. CSP) undercool more, and thus their microstructure and properties are very different than larger solder balls (e.g. BGA). We report results of a study of the effects of solder joint volume, and pad sizes, on the microstructure and thermomechanical properties of solder joints. Solder joint shapes and dimensions spanned the ranges typical of BGA and CSP assemblies. Temperatures of solidification during cool-down were quantified by differential scanning calorimetry. Sn grain structures were characterized by crossed polarizer microscopy and scanning electron microscopy with electron backscattered diffraction. Precipitate sizes and distributions were measured using backscattered scanning electron microscopy. Corresponding properties, including hardness, strength and fatigue resistance were measured before and after aging for various lengths of times at temperatures up to 125°C. Smaller solder joints on smaller pads were shown to be harder and stronger than larger ones, but to age faster and eventually end up softer and weaker.
Using chemical vapor deposition technique, a novel 3D carbon nano-architecture called a pillared graphene nanostructure (PGN) is in situ synthesized. The fabricated novel carbon nanostructure consists of CNT pillars o...
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Using chemical vapor deposition technique, a novel 3D carbon nano-architecture called a pillared graphene nanostructure (PGN) is in situ synthesized. The fabricated novel carbon nanostructure consists of CNT pillars of variable length grown vertically from large-area graphene planes. The formation of CNTs and graphene occurs simultaneously in one CVD growth treatment. The detailed characterization of synthesized pillared graphene shows the cohesive structure and seamless contact between graphene and CNTs in the hybrid structure. The synthesized graphene-CNT hybrid has a tunable architecture and attractive material properties, as it is solely built from sp2 hybridized carbon atoms in form of graphene and CNT. Our methodology provides a pathway for fabricating novel 3D nanostructures which are envisioned for applications in hydrogen storage, nanoelectronics, and supercapacitors.
We report on multilayered optical storage in Sm(DBM)2Phen-doped and un-doped polymethylmethacrylate read out by fluorescence and reflection modes. The detection of fluorescence signal enables retrieval of the stored b...
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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 re...
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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 HA. 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.
Deoxyribonucleic acids provide exciting opportunities as templates in self assembled architectures and functionality in terms of optical and electronic properties. In this study, we investigate the effects of metalize...
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Deoxyribonucleic acids provide exciting opportunities as templates in self assembled architectures and functionality in terms of optical and electronic properties. In this study, we investigate the effects of metalized DNA sequences in organic bulk-heterojunction solar cells. These effects are characterized via optical, quantum efficiency and current-voltage measurements. We demonstrated that by arranging the band energy structure of the devices via placing metalized deoxyribonucleic acid sequences on the hole collection side of the active layer lead to a 20% increase in the power conversion efficiency.
We have developed novel opto-thermo-mechanical actuators by effectively distributing a significant amount of single-wall carbon nanotube (SWCNT, up to 0.7%w/w) into liquid crystal elastomer (LCE) matrices. These SWCNT...
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We have developed novel opto-thermo-mechanical actuators by effectively distributing a significant amount of single-wall carbon nanotube (SWCNT, up to 0.7%w/w) into liquid crystal elastomer (LCE) matrices. These SWCNT/LCE actuators exhibit a great potential to be utilized in MEMS applications, as they respond to a wide spectrum of visible/near-infrared light, and possess a large reversible compressive strain (up to 35%) when stimulated. Autonomous and passive light tracking is demonstrated here as one of the applications. With a simple design, the actuators are able to adaptively tilt a solar cell towards the light source by a degree of ~15° (with an incident light intensity of 1.6 kW/m 2 ). As a result, the photocurrent output of the solar cell is significantly enhanced (up to 247.10%) without any other control system or external energy source.
We have developed a microfluidic reactor array enabling systematic assessment of bacterial cells in a batch culture condition. This system enables creating a series of different growth conditions by preserving differe...
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ISBN:
(纸本)9781618395955
We have developed a microfluidic reactor array enabling systematic assessment of bacterial cells in a batch culture condition. This system enables creating a series of different growth conditions by preserving different growth factors inside nanoliter reactors and cultivating bacterial cells inside the reactors. From a single on-chip experiment, we determined the effects of carbon sources on bacterial phenotypes, i.e. the pattern of growth curves with Escherichia coli K-12. We demonstrated the systematic assessment of inhibition effect of antibiotics on the growth of Pseudomonas aeruginosa. The present system could be used for systematic phenotypic study of different types of bacterial cells.
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