This paper presents the design and fabrication of a 3-dimensional (3-D), hemispherical lens based on reflecting superposition compound eye (RSCE) optics. The configuration of our hemispherical lens, similar to that of...
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Porous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1...
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Porous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1000 m/sec and impacted onto a translating substrate [1]. The impacting particles have sufficient energy to stick to the substrate, allowing patterned thick films to be directly written from the aerosol without a mask. Unlike other low temperature processing routes for achieving patterned films, no organics are added that can interfere with postdeposition processing. Typical films are 5- 100 μm thick, up to several centimeters long, and have an as-deposited relative densities as high as 70% of bulk Ag. Compression tests were carried out in steps at room temperature and at 150°C under constant displacement rates. Local strain and densification were measured by optical profilometry between each compression step. The results can be used as a starting point to better understand the mechanisms that govern plasticity, creep, and sintering in nanostructured, porous silver at low processing temperatures.
This paper focuses on validating a novel framework for estimating the functional strain from cine cardiac magnetic resonance imaging (CMRI). The framework consists of three processing steps. First, the left ventricle ...
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This paper focuses on validating a novel framework for estimating the functional strain from cine cardiac magnetic resonance imaging (CMRI). The framework consists of three processing steps. First, the left ventricle (LV) wall borders are segmented using a level-set based deformable model. Second, the points on the wall borders are tracked during the cardiac cycle based on solving the Laplace equation between the LV edges. Finally, the circumferential and radial strains are estimated at the inner, mid-wall, and outer borders of the LV wall. The proposed framework is validated using synthetic phantoms of the material strains that account for the physiological features and the LV response during the cardiac cycle. Experimental results on simulated phantom images confirm the accuracy and robustness of our method.
We propose a shape-based approach for the segmentation of the left ventricle (LV) wall on cardiac first-pass magnetic resonance imaging (FP-MRI) using level sets. To reduce the variabilities of the LV wall in FP-MRI, ...
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ISBN:
(纸本)9781467364560
We propose a shape-based approach for the segmentation of the left ventricle (LV) wall on cardiac first-pass magnetic resonance imaging (FP-MRI) using level sets. To reduce the variabilities of the LV wall in FP-MRI, it is first imperative to co-align the time series images to account for the global and local motions of the heart. Therefore, we developed a two-step registration methodology that includes an affine-based registration followed by a local B-splines based alignment to maximize a similarity function that accounts for the first- and second-order normalized mutual information (NMI). Additionally, myocardial signal intensity varies with the agent transit, which makes it difficult to control the level set evolution using image intensities alone. Thus, we constrained the level set evolution using three features: a weighted probabilistic shape prior, the first-order pixel-wise image intensities, and a second-order Markov-Gibbs random field (MGRF) spatial interaction model. We tested our approach on 24 data sets in 8 infarction patients using the Dice similarity coefficient (DSC), comparing our approach to other shape-based segmentation approaches. We also tested the performance of our segmentation approach using the receiver operating characteristics (ROC). Our approach achieved a mean DSC value of 0.910±0.037 compared to other shape-based methods that achieved 0.862±0.045 and 0.844±0.047. Finally, the ROC analysis for our segmentation method showed the best performance, with area under the ROC curve of 0.92, while that for intensity showed the worst performance, with area under the ROC curve of 0.69.
This paper presents the development of a Twin-T oscillator comprising polymer coated parallel plates as a sensor for ocean water salinity *** sensor employs a parallel plate capacitor design, with sea water serving as...
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This paper presents the development of a Twin-T oscillator comprising polymer coated parallel plates as a sensor for ocean water salinity *** sensor employs a parallel plate capacitor design, with sea water serving as the medium between plates. Novalac resin and a proprietary commercial polymer (AccufloTW) were investigated as corrosion protective coatings for the copper electrodes of the capacitor. Electrochemical Impedance Spectroscopy (EIS) was employed to evaluate corrosion inhibition of polymer coatingin sea water. A detection circuit was designed and simulated using P-spice and then implemented in Printed Circuit Board (PCB). EIS results indicate that Accuflo exhibits better corrosion inhibition in ocean water than Novolac. Further, the use of Twin-T oscillator based detection circuit resulted in enhanced sensitivity and better detection limit. Experiments performed using ocean water samples resulted in oscillator frequency shift of 410 Hertz/power supply unit (Hz/PSU). Oscillator frequency drift was reduced using frequency-to-voltage converters and sensitivity of 10 mV/PSU was achieved.
Reflection and refraction of electromagnetic waves by artificial periodic composites (metamaterials) can be accurately modeled by an effective medium theory only if the boundary of the medium is explicitly taken into ...
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Reflection and refraction of electromagnetic waves by artificial periodic composites (metamaterials) can be accurately modeled by an effective medium theory only if the boundary of the medium is explicitly taken into account and the two effective parameters of the medium (the index of refraction and the impedance) are correctly determined. Theories that consider infinite periodic composites do not satisfy the above condition. As a result, they can not model reflection and transmission by finite samples with the desired accuracy and are not useful for design of metamaterial-based devices. As an instructive case in point, we consider the “current-driven” homogenization theory, which has recently gained popularity. We apply this theory to the case of one-dimensional periodic medium wherein both exact and homogenization results can be obtained analytically in closed form. We show that, beyond the well-understood zero-cell limit, the current-driven homogenization result is inconsistent with the exact reflection and transmission characteristics of the slab.
Nematic and cholesteric liquid crystals are three-dimensional fluids that possess long-range orientational ordering and can support both topological defects and chiral superstructures. Implications of this ordering re...
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Nematic and cholesteric liquid crystals are three-dimensional fluids that possess long-range orientational ordering and can support both topological defects and chiral superstructures. Implications of this ordering remain unexplored even for simple dynamic processes such as the ones found in so-called “fall experiments,” or motion of a spherical inclusion under the effects of gravity. Here we show that elastic and surface anchoring interactions prompt periodic dynamics of colloidal microparticles in confined cholesterics when gravity acts along the helical axis. We explore elastic interactions between colloidal microparticles and confining surfaces as well as with an aligned ground-state helical structure of cholesterics for different sizes of spheres relative to the cholesteric pitch, demonstrating unexpected departures from Stokes-like behavior at very low Reynolds numbers. We characterize metastable localization of microspheres under the effects of elastic and surface anchoring periodic potential landscapes seen by moving spheres, demonstrating the important roles played by anchoring memory, confinement, and topological defect transformation. These experimental findings are consistent with the results of numerical modeling performed through minimizing the total free energy due to colloidal inclusions at different locations along the helical axis and with respect to the confining substrates. A potential application emerging from this work is colloidal sorting based on particle shapes and sizes.
We introduce a label-free method for detecting high-grade prostatic intraepithelial neoplasia (HGPIN) in unstained biopsies. We image this condition based on the identification of basal cells in biopsies that otherwis...
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Ochratoxin-A[7-(L-β-phenylalanylcarbonyl)-carboxyl-5-chloro-8-hydroxy-3,4-dihydro-3R-methyl-isocumarin, OTA] is a common food contaminant mycotoxin that enters the human body through the consumption of improperly sto...
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Ochratoxin-A[7-(L-β-phenylalanylcarbonyl)-carboxyl-5-chloro-8-hydroxy-3,4-dihydro-3R-methyl-isocumarin, OTA] is a common food contaminant mycotoxin that enters the human body through the consumption of improperly stored food products. Upon ingestion, it leads to immuno-suppression and immuno-toxicity. OTA has been known to produce nephrotoxic, teratogenic, and carcinogenic activity (via oxidative DNA damage) in several species. This review introduces potentials of electrochemical biosensor to provide breakthroughs in OTA detection through improved selectivity and sensitivity and also the current approaches for detecting OTA in food products.
Significant physical challenges remain for CMOS technology to decrease I off as transistor dimension and power supply voltages continue downscaling. However, a fundamental thermodynamic limit in the subthreshold slop...
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Significant physical challenges remain for CMOS technology to decrease I off as transistor dimension and power supply voltages continue downscaling. However, a fundamental thermodynamic limit in the subthreshold slope SS = |(∂V g )/(∂lnI d )| = ln10 · k B T/q at >60 mV/dec exists at room temperature. We have designed and demonstrated the first semiconductor nanowires (NWs) and nanoelectromechanical system (NEMS) field effect transistor structure (NW-NEMFET). We have previously demonstrated 0.5 ps intrinsic delay and near ballistic operation in quantum confined semiconductor heterostructure NWFETs with diameters less than 15 nm.[1] The current design uses high performance suspended semiconductor NWs as the conduction channel, while the electrostatic pull-in of the NW towards the gate stack enables abrupt switching to the off-state leading to high frequency, low power nanoelectronics. Simulation shows that compared to planar suspended-gate FET (SGFET) design [2], NW-NEMFET allows zero SS with 10 15 on-off ratio and near 1V pull-in voltage due to enhanced 3D capacitive coupling, as well as operation at very-high-frequency (VHF) and even ultra-high-frequency (UHF) due to the NW beams high aspect ratio and small dimensions.
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