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Band-to-Band Tunneling Analytical Model and Implications in Compact Modeling of Ternary CMOS
No full textLabel-free phase microscopy for morphogenetic screening of zebrafish brain
No full textZebrafish are emerging specimens in morphogenesis studies, due to their genetic similarity to humans, fast development, embryonic transparency, and the availability of rapid phenotypic screening. Monitoring the phenotype in zebrafish conventionally involves a visual assessment and scoring of morphological features. As advanced microscopic imaging techniques are introduced for high resolution and volumetric anatomy, these techniques have been initially applied to neuroscience and developmental studies. However, existing methods are time-consuming and methodologically limited to provide fast and morphogenetic information of whole-mount zebrafish due to shallow imaging depth and the availability of transgenic reagents. In this study, we propose a novel label-free phase microscope for morphogenetic screening of the brain of zebrafish embryos in several development stages. Our system is based on quantitative phase imaging (QPI) which recovers phase delays after light passes through the specimen. Among the various QPI methods, we used four asymmetric NIR illumination patterns providing improved contrast and penetration depth. Using clear embryo samples within 1% agarose gel, prepared by 1-phenyl 2-thiourea (PTU) treatment, we acquired the dorsal and lateral views at 3, 4, and 5 days post fertilization (dpf). As a result, we confirmed that QPI had sufficient contrast and imaging depth to identify brain regions in dorsal and lateral QPIs than bright-field images. Lateral QPIs clearly showed detailed brain structures of normal zebrafish embryos, such as epiphysis, optic tectum, and cerebellum. To further evaluate our imaging system, we compared wile-type (WT) zebrafish embryos to the atad5a mutants at 3 and 5dpf. We segmented specific parts within the brain and found that there is significant differences in size and morphology between WT and mutant animals. The midbrain of atad5a mutants became smaller and flatter than WT controls from 3 dpf and the morphological appearance of the optic tectum showed visible alteration in the mutants at 5 dpf. In conclusion, we demonstrated that our phase microscope has sufficiently high contrast and depth penetration to visualize the developmental morphology of the zebrafish brain without any labeling or contrast agents. These results showed the possibility of applying our imaging system to the screening of brain morphological alterations by genetic modification or drug treatment. Finally, the imaging capability of our system can be enhanced when it is combined with the 360-degree rotation of the specimen, which provides a quantitative, volumetric, and comprehensive brain of zebrafish developmental studies
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No full textSmart fiber orientation monitoring system in a mold via electrical route modeling
Get PDFThe orientation of unidirectional carbon fibers (UDCFs) in a manufacturing process is critical to the mechanical properties of carbon fiber reinforced plastics (CFRPs). This study presents a method to monitor the orientation of UDCFs on a mold using electrical resistance during the CFRP manufacturing process. An equivalent electrical model for UDCFs was proposed to develop an in situ sensor in a mold. The orientation of UDCFs during the CFRP manufacturing process is investigated in terms of its orthotropic electrical properties. The proposed technique can have strong implications on in situ monitoring of composite molding process where the fiber orientation is unseen by monitoring electrical resistance with Cu tapes as electrodes
Advances in Nanomaterials-Based Color Conversion Layer
No full textColor conversion layer refers to a layer that converts the blue light emitted from the backlight into the red and green light. Heavy metal-free quantum dots and perovskite nanocrystals have attracted great attention as base materials for color conversion layers due to their outstanding optical characteristics. Here, we review recent advances in the development of color conversion layers based on quantum dots. First, we overview the representative optical characteristics of quantum dots and perovskite nanocrystals, and then introduce printing techniques for color converting layers including photolithography, inkjet printing, and nanoimprinting. Finally, we conclude this review with a brief perspective
Highly Densified Fracture-Free Silicon-based Electrode for High Energy Lithium-Ion Batteries
No full textThere has recently been an increasing volume of research in silicon-based anodes for high energy density lithium-ion batteries. Micron-sized composites with high tap density and a number of pores accommodating the massive volume expansion of silicon (Si) exhibit considerable electrochemical performance with high volumetric energy density. However, huge pressure on the particle during the calendering process brings about mechanical failure which causes the formation of additional by-products upon lithiation and electrical contact loss. Here, we discover specific particle size distribution based on the constructive simulation including calculation of the packing density depending on the different particle size distribution and stress evolution of each particle at high pressure. A silicon/graphite hybrid anode in which the silicon nanolayer (similar to 15 nm) is coated on the graphite is selected to validate the simulation. This anode sustains its morphological integrity and secures its void space without crack propagation of the silicon nanolayer in the densely packed electrode. As a result, it demonstrates high initial specific capacity (>500 mAh g(-1)), high initial Coulombic efficiency (95.2 %), low electrode swelling ratio (35 % at first cycle), and excellent capacity retention ratio (99.1 % during 50 cycles) for high energy density lithium-ion batteries
