We successfully engineered Si nano-columns with different cross-sectional geometries by e-beam evaporation with an angle between source and substrate. The Si nano-columns were grown as pillars with square, triangle an...
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We successfully engineered Si nano-columns with different cross-sectional geometries by e-beam evaporation with an angle between source and substrate. The Si nano-columns were grown as pillars with square, triangle and linear cross sections in in-plane. Mesenchymal stem cells (MSCs) isolated from the bone marrow stroma of young adult rats were cultured on these different Si nanosurfaces. We found that the behaviour of MSCs highly depended on the geometry of nano-topography so that mesenchymal stem cells were differentiated and induced CaP precipitation on square-cross-sectional Si nano-columns without growth factor in the culture medium.
In most of the ternary (and higher-order) ferromagnetic shape memory alloys (FSMAs) with compositions close to the A2BC stoichiometry, the austenite phase exhibits L21-type ordering. Recent investigations of the Co-Ni...
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In most of the ternary (and higher-order) ferromagnetic shape memory alloys (FSMAs) with compositions close to the A2BC stoichiometry, the austenite phase exhibits L21-type ordering. Recent investigations of the Co-Ni-Ga FSMA system, however, suggest that the austenite phase has B2-type ordering, although definite confirmation remains elusive. In this work, we present a theoretical investigation of the effect of configurational order on the magnetic properties of the ordered (L21) and disordered (B2) FSMA Co2NiGa. Through the use of calculations based on density functional theory, we predict the structural and magnetic properties (including magnetic exchange constants) of ordered and disordered Co2NiGa alloys. We validate our calculation of the magnetic exchange constants by extracting the Curie temperatures of the austenite and martensite structures and comparing them to experimental results. By constructing a q-state Potts magnetic Hamiltonian and through the use of lattice Monte Carlo simulation, we predict the finite-temperature behavior of the magnetization and magnetic susceptibility as well as the magnetic specific heat and entropy. The role of configurational order in the magnetic properties of the phases involved in the martensitic phase transformation is discussed, and predictions of the magnitude of the magnetic contributions to the transformation entropy are presented. The calculations are compared to experimental information available in the literature as well as experiments performed by the authors. It is concluded that in FSMAs magnetism plays a fundamental role in determining the relative stability of the austenite and martensite phases, which in turn determines the martensitic transformation temperature Ms, irrespective of whether magnetic fields are used to drive the transformation.
In this paper, we review various LTPS backplane technologies based on laser-crystallization and other related methods that have been applied to AMLCD and AMOLED displays. The TFT performances obtained by different mel...
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Step-graded InGaPySb1-y and InxGa 1-xAs metamorphic buffer layer (MBL) structures are grown on GaAs substrates by metal-organic chemical vapor deposition (MOCVD). AFM analysis indicates that graded group V InGaPySb1-y...
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We have investigated the shapes, thickness, density, composition, and quality of Ge/Si(001) islands grown by solid source molecular beam epitaxy in ultra high vacuum conditions. Nano crystals were formed by means of t...
We have investigated the shapes, thickness, density, composition, and quality of Ge/Si(001) islands grown by solid source molecular beam epitaxy in ultra high vacuum conditions. Nano crystals were formed by means of the Stranski-Krastanow “self assembly” growth mechanism. 5 nm of Ge were deposited on Si(001) substrates, at 500 °C, with deposition rate of 0.5 nm/min. Atomic force microscope measurements reveal islands of various sizes, ranging from 60 nm to 700 nm in diameter. Islands’ density found to be correlated with their sizes, with denser areas containing mostly islands of the smaller sizes. Micro Raman spectroscopy, with probing spot of about 0.7 µm diameter, has been used to study the composition, thickness and crystalline quality of the islands. Data were taken at various points on the sample distinguishing between various islands’ types. Combined analysis of Raman spectra and the micrographs reveal low amount of alloying (less than 30%) in all types of islands, with the larger islands showing the more amount of intermixing. High crystalline quality of the layers within the islands suggests negligible amount of dislocations.
Infrared photoluminescence (PL) and electroluminescence (EL) from erbium-doped porous silicon (PSi) structures are studied. The PL and EL from the Er-doped PSi structures and the absence of silicon band edge recombina...
Infrared photoluminescence (PL) and electroluminescence (EL) from erbium-doped porous silicon (PSi) structures are studied. The PL and EL from the Er-doped PSi structures and the absence of silicon band edge recombination, point defect, and dislocation luminescence bands suggest that the Er-complex centers are the most efficient recombination sites. PSi multilayers with very high reflectivity (R ≥ 90%) in the 1.5 gim range have been incorporated in the structures resulting in a PL enhancement of over 100%. Stable and intense EL is obtained from the Er-doped structures. The EL spectrum is similar to that of the PL, but shifted towards higher energy. The unexpected shift in emission opens up the possibility for erbium related luminescence to encompass a larger part of the optimal wavelength window for fiber optic communications.
The multi-luminophore lifetime determination (MLD) technique uses a simple window sum correction to calculate the true lifetime of two temporally-distinct luminophores using time-domain techniques. This method offers ...
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ISBN:
(纸本)9781424492909
The multi-luminophore lifetime determination (MLD) technique uses a simple window sum correction to calculate the true lifetime of two temporally-distinct luminophores using time-domain techniques. This method offers advantages over traditional fitting methods because it can quickly calculate lifetime for optimal use in applications which require the ability to monitor dynamic changes, such as multi-analyte sensing. Measurement error can be reduced if sampling parameters such as window width are chosen appropriately.
Organized nanostructures are formed after irradiation of layers of randomly aligned single-wall carbon nanotube (SWNT)-polymer composites by a Ti:Sapphire 775 nm laser with a 150 fs pulse at fluences near 0.1 J/cm2. A...
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Organized nanostructures are formed after irradiation of layers of randomly aligned single-wall carbon nanotube (SWNT)-polymer composites by a Ti:Sapphire 775 nm laser with a 150 fs pulse at fluences near 0.1 J/cm2. At varying peak fluences morphology is seen where the tubes are ejected from the substrate or formed into long, parallel structures of SWNT’s. These structures have been created on both glass substrates and carbon grids. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) investigation of the structures reveal that they are composed of bundled nanotubes typically 400 nm – 1 micron long. Large-area laser patterning of the film allows for structuring of the film without detrimental decreases in conductivity.
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