Browsing by Author "Lin, Tzu-Wei"

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Atomic layer oxidation on graphene sheets for tuning their oxidation levels, electrical conductivities, and band gaps
(2018-09-07)
Gu, Siyong
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Hsieh, Chien-Te
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Lin, Tzu-Wei
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Yuan, Chun-Yao
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Gandomi, Yasser Ashraf
Graphene sheets that can exhibit electrical conducting and semiconducting properties are highly desirable and have potential applications in fiber communications, photodetectors, solar cells, semiconductors, and broadband modulators. However, there is currently no efficient method that is able to tune the band gap of graphene sheets. This work adopts an efficient atomic layer oxidation (ALO) technique to cyclically increase the oxidation level of graphene sheets, thus, tuning their electrical conductance, band-gap structure, and photoluminescence (PL) response. The O/C atomic ratio as an increasing function of the ALO cycle number reflects two linear regions: 0.23% per cm(2) per cycle (0-15 cycles) and 0.054% per cm(2) per cycle (15-100 cycles). The excellent correlation coefficients reveal that the ALO process follows a self-limiting route to step-by-step oxidize graphene layers. The interlayer distance of ALO-graphene sheets shows an obvious increase after the ALO treatment, proved by X-ray diffraction. As analyzed by X-ray photon spectroscopy, the hydroxyl or epoxy group acts as a major contributor to the interlayer spacing distance and oxidation extent in the initial ALO stage, as compared to carbonyl and carboxyl groups. The ALO mechanism, based on Langmuir-Hinshelwood and Eley-Rideal models, is proposed to clarify the formation of oxygen functionalities and structural transformation from pristine graphene sheets to oxidized ones during the ALO cycle. With a tunable oxidation level, the electrical resistivity, semiconductor character, and PL response of ALO-graphene samples can be systematically controlled for desired applications. The ALO approach is capable of offering a straightforward route to tune the oxidation level of graphene sheets or other carbons.
Glutamate Stimulation Dysregulates AMPA Receptors-Induced Signal Transduction Pathway in Leber's Inherited Optic Neuropathy Patient-Specific hiPSC-Derived Retinal Ganglion Cells
(2019-06-01)
Yang, Yi-Ping
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Phan Nguyen Nhi Nguyen
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Lin, Tai-Chi
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Yarmishyn, Aliaksandr A.
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Chen, Wun-Syuan
The mitochondrial genetic disorder, Leber's hereditary optic neuropathy (LHON), is caused by a mutation in MT-ND4 gene, encoding NADH dehydrogenase subunit 4. It leads to the progressive death of retinal ganglion cells (RGCs) and causes visual impairment or even blindness. However, the precise mechanisms of LHON disease penetrance and progression are not completely elucidated. Human-induced pluripotent stem cells (hiPSCs) offer unique opportunities to investigate disease-relevant phenotypes and regulatory mechanisms underlying LHON pathogenesis at the cellular level. In this study, we successfully generated RGCs by differentiation of LHON patient-specific hiPSCs. We modified the protocol of differentiation to obtain a more enriched population of single-cell RGCs for LHON study. Based on assessing morphology, expression of specific markers and electrophysiological activity, we found that LHON-specific hiPSC-derived were more defective in comparison with normal wild-type RGCs. Based on our previous study, whereby by using microarray analysis we identified that the components of glutamatergic synapse signaling pathway were significantly downregulated in LHON-specific RGCs, we focused our study on glutamate-associated alpha -amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors. We found that the protein expression levels of the subunits of the AMPA receptor, GluR1 and GluR2, and their associated scaffold proteins were decreased in LHON-RGCs. By performing the co-immunoprecipitation assay, we found several differences in the efficiencies of interaction between AMPA subunits and scaffold proteins between normal and LHON-specific RGCs.
On-chip bus encoding for power minimization under delay constraint
(2007)
Lin, Tzu-Wei
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Tu, Shang-Wei
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Jou, Jing-Yang
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
As technology advances, the global interconnect delay and the power consumption of long wires become crucial issues in nanometer technologies. In particular, both inductive and capacitive coupling effects between wires result in serious problems such as crosstalk delay, coupling noise, and power consumption. In this paper, we propose a new bus encoding scheme for global bus design in nanometer technologies. With the user-given bus parameters, the working frequency, and the delay constraint, the scheme can minimize the bus power consumption subject to the delay constraint by effectively reducing the LC coupling effects.