Browsing by Author "Chen, Yu-Liang"

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(110)-Exposed Gold Nanocoral Electrode as Low Onset Potential Selective Glucose Sensor
(2010-10-01)
Cheng, Ta-Ming
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Huang, Ting-Kai
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Lin, Huang-Kai
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Tung, Sze-Ping
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Chen, Yu-Liang
A straightforward electrochemical deposition process was developed to grow gold nanostructures, including nanocoral, nanothorn, branched belt, and nanoparticle, on carbon electrodes by reducing HAuCl(4) under constant potentials in mixtures containing CTAC and/or NaNO(3). Among the nanostructures, the quasi-one-dimensional nanocoral electrode showed the highest surface area. Because of this, it provided excellent electrochemical performances in cyclic voltammetric (CV) studies for kinetic-controlled enzyme-free glucose oxidation reactions. In amperometric studies carried out at 0.200 V in PBS (pH 7.40, 0.100 M), the nanocoral electrode showed the highest anodic current response. It also offered the greatest sensitivity, 22.6 mu AmM(-1)cm(-2), an extended linear range, 5.00 x 10(-2) mM to 3.00 x 10(1) mM, and a low detection limit, 1.00 x 10(1) mu m among the electrodes investigated in this study. In addition, the glucose oxidation by the nanocoral electrode started at -0.280 V. more negative than the one of using a commercial Au electrode as the working electrode. This is attributed to the presence of exposed Au (110) surfaces on the electrode. The feature was applied to oxidize glucose selectively in the presence of ascorbic acid (AA) and uric acid (UA), common interferences found in physiological analytes. With an applied voltage at -0.100 V. the AA oxidation (started at -0.080 V) can be avoided while the glucose oxidation still provides a significant response.
(110)-Exposed Gold Nanocoral Electrode as Low Onset Potential Selective Glucose Sensor
(2010-10-01)
Cheng, Ta-Ming
;
Huang, Ting-Kai
;
Lin, Huang-Kai
;
Tung, Sze-Ping
;
Chen, Yu-Liang
A straightforward electrochemical deposition process was developed to grow gold nanostructures, including nanocoral, nanothorn, branched belt, and nanoparticle, on carbon electrodes by reducing HAuCl(4) under constant potentials in mixtures containing CTAC and/or NaNO(3). Among the nanostructures, the quasi-one-dimensional nanocoral electrode showed the highest surface area. Because of this, it provided excellent electrochemical performances in cyclic voltammetric (CV) studies for kinetic-controlled enzyme-free glucose oxidation reactions. In amperometric studies carried out at 0.200 V in PBS (pH 7.40, 0.100 M), the nanocoral electrode showed the highest anodic current response. It also offered the greatest sensitivity, 22.6 mu AmM(-1)cm(-2), an extended linear range, 5.00 x 10(-2) mM to 3.00 x 10(1) mM, and a low detection limit, 1.00 x 10(1) mu m among the electrodes investigated in this study. In addition, the glucose oxidation by the nanocoral electrode started at -0.280 V. more negative than the one of using a commercial Au electrode as the working electrode. This is attributed to the presence of exposed Au (110) surfaces on the electrode. The feature was applied to oxidize glucose selectively in the presence of ascorbic acid (AA) and uric acid (UA), common interferences found in physiological analytes. With an applied voltage at -0.100 V. the AA oxidation (started at -0.080 V) can be avoided while the glucose oxidation still provides a significant response.
A low-cost, high-availability P2P storage scheme with regenerating code that combines caching methods
(2012)
Chen, Yu-Liang
;
Yuan, Shyan-Ming
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資訊工程學系
;
Department of Computer Science
Peer-to-peer (P2P) storage systems are expected to be fast, fault-tolerant, scalable, and reliable. Thus, high data availability is an essential feature of P2P storage systems. In this article, we present a scheme that utilizes a regenerating code (RC) with caching to improve the performance of content services provided by P2P storage systems. Erasure coding is commonly employed to support high availability, but this technique requires the original file to produce redundant data. In contrast, RC solves the problem by collecting the encoded information. However, RC requires more peers to decode the blocks, which is difficult in a P2P environment because more peers must simultaneously remain active to hold the file blocks. Based on the RC, we store the information for a peer that has recently accessed blocks and utilized the data in the peer's LRU cache to increase the access performance and reduce the encoding cost. We carried out a series of experiments with different cache sizes under various levels of P2P availability. The results show that our scheme can outperform the traditional RC system in terms of access performance, allowing access at least 83% of the time, while also achieving a lower cost.
A P2P Auto-Recover Method for the Factory Data of Cable Modem over the HFC Network
(2012)
Chen, Yu-Liang
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Luo, Guo-Heng
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Chang, Yi-Ming
;
Yuan, Shyan-Ming
;
資訊工程學系
With the popularization of the Data-OverCable Service Interface Specifications (DOCSIS) product, many devices have been installed in client sides. The issue of how to maintain the quality while providing quick repair becomes more and more important. In some practical circumstances, the cable modem may lose the factory data which include the calibration table and the digital certificates. These data are unique and vital for the regular operations of cable modem. The traditional way of handling the malfunction product is to ship back the product to the maintenance branch and replaces a working device for the customer. In this paper we will present a solution which is based on network coding over peer to peer (P2P) network to fix the problem automatically online, named Cable modem Auto-Recovery (CAROL).
Ballistic Impact Performance of SiC Ceramic-Dyneema Fiber Composite Materials
(2020-01-22)
Wu, Kai-Kuang
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Chen, Yu-Liang
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Yeh, Jau-Nan
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Chen, Wei-Lun
;
Lin, Chia-Shih
This study investigated the ballistic resistance of a composite target plate fabricated by combining SiC ceramic with the Dyneema fiber. To achieve a light-weight target plate that conforms to the US National Institute of Justice level four (NIJ IV) standards, minimal areal density analysis was conducted to obtain the optimal SiC ceramic-Dyneema fiber thickness combination. This study used energy absorption to analyze the ballistic resistance of the target plates. To drastically reduce experimental costs, most of this work employed ANSYS/LS-DYNA software to conduct finite element numerical simulations. First, ballistic experiments that conformed to NIJ IV standards were conducted to verify the simulation parameter configurations. Subsequently, the correlation function of the relationship between the combined thickness of the composite material and its ballistic resistance was determined through the experimental design, which effectively reduced the simulation analysis time. According to simulation experiments and regression analysis, the equation for the relationship between the combined thickness of the composite material and its ballistic resistance was EA though there were limitations to its application. From the numerical analysis results, 8.1940 mm SiC ceramic and 6.9637 mm Dyneema fiber were determined to constitute the optimal thickness combination for a composite that features a minimal areal density and which conforms to NIJ IV standards. The combination was verified to be consistent with the numerical simulation analysis results.
Conversion oil Potassium Titanate Nanowires into Titanium Oxynitride Nanotubes
(2011-10-01)
Wei, Yen-Ju
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Peng, Chih-Wei
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Cheng, Ta-Ming
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Lin, Huang-Kai
;
Chen, Yu-Liang
Tunnel-structured potassium titanate with a K(3)Ti(8)O(17) phase was synthesized by direct oxidation of titanium powder mixed with KF(aq) in water vapor at 923 K. The reaction conditions were adjusted so that uniform single crystalline potassium titanate nanowires with [010] growth direction (length: 5-30 mu m, diameter: 80-100 nm) were obtained. Nitridation of the nanowires by NH(3)(g) at 973-1073 K converted the titartate nanowires into rock-salt structured cubic phase single crystalline titanium oxynitride TiN(x)O(y) nanotubes (x = 0.88, y = 0.12, length = 1-10 mu m, diameter = 150-250 nm, wall thickness = 30 - 50 nm) and nanorods (x = 0.5, y = 0.5, length 1-5 mu m, diameter = 100-200 nm) with rough surfaces and [200] growth direction. The overall conversion of the titanate nanowires into the nanotubes and the nanorods can be rationalized by Ostwald ripening mechanism. We fabricated an electrode by adhering TiN(x)O(y) nanotubes (0.2 mg) on a screen-printed carbon electrode (geometric area: 0.2 cm(2)). Electrochemical impedance spectroscopy demonstrated its charge transfer resistance to be 20 Omega. The electrochemical surface area of the nanotubes on the electrode was characterized by cyclic voltammetry to be 0.32 cm(2). This property suggests that the TiN(x)O(y) nanostructures can be employed as potential electrode materials for electrochemical applications.
Electrochemical Growth of Gold Nanostructures for Surface-Enhanced Raman Scattering
(2011-02-10)
Yang, Yu-Cheng
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Huang, Ting-Kai
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Chen, Yu-Liang
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Mevellec, Jean-Yves
;
Lefrant, Serge
We demonstrate a facile fabrication of gold nanostructures including Au nanoplates (NPs), Au nanothorns (NTs), and Au nanowires (NWs) on indium tin oxide substrates via electrochemical growth. A simple two-electrode electrochemical deposition system was applied for the fabrication process. Dense Au nanostructures were grown directly on an Au seeding layer on the substrate. After 48 h, the Au NPs were 2-5 mu m in width and 150-200 nm in thickness. The Au NTs were 1-3 mu m in height, 300-500 nm in bottom side width, and 20 nm at the apex. The Au NWs were 30-80 nm in diameter and about 20 mu m in length. The entire process was template-free and economical. We investigated the correlation between surface plasmon resonance (SPR) and surface enhanced scattering (SERS) effects of the Au nanostructures with different excitation wavelengths. By using the SPR absorption maxima of the nanostructures as the excitation wavelengths for SERS, the highest SERS enhancements were achieved. SERS effects of the Au NWs were investigated further. We discovered that the length and the density of the Au NWs affected the SERS performance significantly. The result is rationalized by the amount of "hot spot" generated at the crossing of the Au NWs. With the Au NWs, Rhodamine 6G can be detected at a concentration as low as 10(-9) M.
Fabrication of gold/polypyrrole core/shell nanowires on a flexible substrate for molecular imprinted electrochemical sensors
(2014-01-01)
Huang, Wei-Ren
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Chen, Yu-Liang
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Lee, Chi-Young
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Chiu, Hsin-Tien
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應用化學系
In this work, we fabricated gold-nanowires (Au NWs) on flexible substrates by direct current electrochemical deposition. Then, we electropolymerized a polypyrrole layer onto the Au NWs via cyclic voltammetry (CV) as the molecular imprinted polymer biosensor to detect dopamine (DA). The influence of the scan rate of CV for the sensor preparation was optimized. CV and differential pulse voltammetry (DPV) were used to measure different DA concentrations. The Au/polypyrrole core/shell nanowires sensor showed good DPV signal intensity at 805 mu A mM(-1) and the determined linear range for DA was 4 x 10(-7) to 1 x 10(-5) M (N = 3).
Game-Based Remedial Instruction in Mastery Learning for Upper-Primary School Students
(2013-04-01)
Lin, Chun-Hung
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Liu, Eric Zhi-Feng
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Chen, Yu-Liang
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Liou, Pey-Yan
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Chang, Maiga
The study examines the effectiveness of using computer games for after-school remedial mastery learning. We incorporated instructional materials related to "area of a circle" into the popular Monopoly game to enhance the performance of sixth-grade students learning mathematics. The program requires that students enter the answers to avoid the shortcomings of multiple-choice questions. Throughout the game, whenever students are unable to answer questions correctly they receive immediate remedial instruction specifically for that question. This study sought to compare the effectiveness of game-based and video-based remedial instruction incorporated with elements of mastery learning. The results demonstrate that (a) both instructional videos and the proposed Monopoly game enhance the learning of mathematical concepts; and (b) the Monopoly game is more effective than instructional videos at leveraging the benefits of mastery learning. The goal of the research was to integrate games and mastery learning into after-school remedial instruction and design a game to practice the steps of mastery learning.
Gold Nanostructures on Flexible Substrates as Electrochemical Dopamine Sensors
(2012-10-01)
Hsu, Ming-Sheng
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Chen, Yu-Liang
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Lee, Chi-Young
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Chiu, Hsin-Tien
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應用化學系
In this study, we fabricated Au nanowires (NWs), nanoslices (NSs), and nanocorals (NCs) on flexible polyethylene terephthalate (PET) substrates via direct current electrochemical depositions. Without any surface modification, the Au nanostructures were used as the electrodes for dopamine (DA) sensing. Among them, the Au NW electrode performed exceptionally well. The determined linear range for DA detection was 0.2- 600 mu M (N = 3) and the sensitivity was 178 nA/mu M cm(2), while the detection limit was 26 nM (S/N = 3). After 10 repeated measurements, 95% of the original anodic current values were maintained for the nanostructured electrodes. Sequential additions of citric acid (CA, 1 mM), uric acid (UA, saturated), and ascorbic acid (AA, 1 mu M) did not interfere the amperometric response from the addition of DA (0.1 mu M).
Growth of Carbon Nanocoils from K and Ag Cooperative Bicatalyst Assisted Thermal Decomposition of Acetylene
(2010-07-01)
Liu, Wen-Chih
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Lin, Huang-Kai
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Chen, Yu-Liang
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Lee, Chi-Young
;
Chiu, Hsin-Tien
Growth of amorphous carbon nanocoil (CNC) from acetylene on Si substrates was achieved by using nanosized Ag and K as the catalysts. The deposition of CNC was carried out inside a hot-wall reactor at 723 K using H(2) as the carrier gas. Based on the observed results, we propose a cooperative bimetal catalyst enhanced vapor-liquid-solid (VLS) growth mechanism to rationalize the CNC growth. In the reaction, the liquid phase metallic K dehydrogenated acetylene into the solid-state carbon, while the Ag nanoparticle assisted the extension of carbon one-dimensionally (1-D) via a tip-growth mechanism. Due to the adhesive force between the K liquid and the carbon, the 1-D solid curled along the C K interface into the nanocoil shape. Some CNC samples were further heat-treated at 1423 K and showed very good field emission properties. They emitted electrons (10 mu A/cm(2)) at a turn-on field E(10) of 2.51 V/mu m, while J(max) reached 17.71 mA/cm(2) at 5.64 V/mu m. The field enhancement factor beta was calculated to be 2124, comparable to other carbon nanotube (CNT) and CNC based emitters. The CNC was also characterized by using the electrochemical behavior of K(3)[Fe(CN)(6)] via cyclic voltammetry (CV). The electrochemical surface area of a CNC electrode (geometric surface area 0.078 cm(2)) was calculated to be 0.143 cm(2). These properties suggest that the CNC electrodes may have potential applications in field emission and electrochemical devices.
Growth of gold nanowires on flexible substrate for highly sensitive biosensing: detection of thrombin as an example
(2013)
Chen, Yu-Liang
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Lee, Chi-Young
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Chiu, Hsin-Tien
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應用化學系
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Department of Applied Chemistry
We demonstrated a facile fabrication of high density Au nanostructures including nanothorns (NTs), nanocorals (NCs), nanoslices (NSs), and nanowires (NWs) which were electrochemically grown on flexible plastic substrates of polyethylene terephthalate (PET). A thrombin-binding aptamer was immobilized on the surfaces of the Au nanostructures to form highly sensitive electrochemical impedance spectroscopic (EIS) biosensors for thrombin recognition. The binding of thrombin to the aptamer sequence was monitored by EIS in the presence of [Fe(CN)(6)]((aq))(3-/4-). The protein (1-50 pM) was detected linearly by the Au nanostructures. Among them, the Au NWs exhibited excellent thrombin detection performances. The biosensor provided high sensitivity, selectivity, and stability due to its high surface area.
Nanosized MnO2 spines on Au stems for high-performance flexible supercapacitor electrodes
(2013)
Chen, Yu-Liang
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Chen, Po-Chin
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Chen, Tze-Lung
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Lee, Chi-Young
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Chiu, Hsin-Tien
Electrodes composed of ultrathin MnO2 (thickness 5-80 nm) spines on Au nanowire (NW) stems (length 10-20 mu m, diameter 20-100 nm) were electrochemically grown on flexible polyethylene terephthalate (PET) substrates. The electrodes demonstrated high specific capacitance, high specific energy value, high specific power value, and long-term stability. In Na2SO4(aq.) (1 M), the maximum specific capacitance was determined to be 1130 F g(-1) by cyclic voltammetry (CV, scan rate 2 mV s(-1)) using a three-electrode system. From a galvanostatic (GV) charge/discharge test using a two-electrode system, a maximum capacitance of 225 F g(-1) (current density 1 A g(-1)) was measured. Even at a high charge/discharge rate of 50 A g(-1), the specific capacitance remained at an extremely high value of 165 F g(-1). The flexible electrodes also exhibited a maximum specific energy of 15 W h kg(-1) and a specific power of 20 kW kg(-1) at 50 A g(-1). After five thousand cycles at 10 A g(-1), 90% of the original capacitance was retained. A highly flexible solid-state device was also fabricated to reveal its supercapacitance performance.
New Group Shuffled BP Decoding Algorithms for LDPC Codes
(2009)
Chang, Chi-Yuan
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Chen, Yu-Liang
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Lee, Chang-Ming
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Su, Yu T.
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電信工程研究所
Implementing a belief propagation (BP) based LDPC decoder requires high degrees of parallelism using many component soft-in soft-output (SISO) decoding units to perform message passing from variable nodes to check nodes or vice versa. An obvious complexity-reduction solution is to serialize the decoding process, i.e., dividing a decoding iteration into several serial sub-iterations in which a sub-iteration performs only part of the complete parallel message-passing operation. The group horizontal shuffled BP (GHSBP) and vertical shuffled BP (GVSBP) algorithms respectively partition the check and variable nodes of the code graph into groups to perform group-by-group message-passing decoding. This paper proposes new techniques to improve three key elements of a GHSBP decoding algorithm, namely, the grouping method, the decoding schedule and the log-likelihood updating formulae. The (check nodes) grouping method and decoding schedule optimize certain design criterion. The new normalized min-sum updating formula with a self-adjustable correction (scaling) factor offers better nonlinear approximation. Numerical performance of new GHSBP algorithms that include part or all three new techniques indicate that the combination of the proposed grouping and decoding schedule yields a faster convergence rate and our modified min-sum algorithm gives performance superior to that of the conventional min-sum and normalized min-sum algorithm and is very close to that of the sum-product algorithm.
Regenerating Code Based P2P Storage Scheme with Caching
(2009)
Chen, Yu-Liang
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Li, Guang-Ming
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Tsai, Ching-Tsorng
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Yuan, Shyan-Ming
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Chiao, Hsin-Ta
High data availability is an important feature of P2P storage system. Erasure coding is a common method employed to support the property. But the technique requires an original file to produce redundant data. On the contrary Regenerating Code, without maintaining the original file, solves the problem through collecting encoded information in a distributed way. However, there is a drawback in this method; that is, encoding needs more peers to get involved in order to obtain good information, which is a harsh condition in a P2P environment due to the requirement of keeping more peers alive simultaneously to hold the file blocks. On the condition that the system did not need to store a replica, we recorded the information of peers which have accessed files recently and utilized the data which have been accessed last in the LRU cache of the peer to improve the access performance and reduce the encoding cost. Through simulation, we experimented with different cache sizes under various peer availability. The results showed that our scheme can successfully improve at least 83 percent of the access performance and lower the cost of Regenerating Code when a file is divided into 7 blocks and the cache size is 64 file blocks.
Surface-Enhanced Raman Scattering Imaging of a Single Molecule on Urchin-like Silver Nanowires
(2011-09-01)
Hsiao, Wei-Han
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Chen, Hsin-Yu
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Yang, Yu-Cheng
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Chen, Yu-Liang
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Lee, Chi-Young
Urchin-like silver nanowires are prepared by reacting AgNO(3)(aq) with copper metal in the presence of cetyltrimethylammonium chloride and HNO(3)(aq) on a screen-printed carbon electrode at room temperature. The diameters of the nanowires are about 100 nm, and their lengths are up to 10 mu m. Using Raman spectroscopy, the detection limit of Rhodamine 6G (R6G) on the urchin-like silver nanowire substrate can be as low as 10(-16) M, while the analytical enhancement factor is about 10(13). Raman mapping images confirm that a single R6G molecule on the substrate can be detected.
The "cascade effect" of nano/micro hierarchical structure: A new concept for designing the high photoactivity materials - An example for TiO2
(2013-10-01)
Chen, Po-Chin
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Tsai, Min-Chiao
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Yang, Min-Han
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Chen, Ting-Ting
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Chen, Huang-Chin
The chrysanthemum-like TiO2 (CT800) was synthesized. It exhibited excellent photoactivity, which greatly exceeded that of conventional P25. To discover the key factors that governed the photocatalytic properties, the specific reduction of Ag+ ions was carried out and EPR spectra of CT800 were obtained. Both an HADDF image and EDX mapping indicated that the Ag+ ions tended to be reduced close to the center of the micro matrix of CT800. Moreover, the EPR spectra strongly suggest that the excited electrons tended to migrate toward the center of the micro matrix, resulting from a multiple junction, cascade effect, which efficiently reduces the recombination of excited electrons and holes and greatly increases the photoactivity. Additionally, the special morphology of CT800 was responsible for the hot spots at the surface of nano sheets and then contributing to its outstanding photocatalytic activity. Furthermore, the unidirectional electron transfer, because of the cascade effect, by materials of different sizes provides a new avenue for the design of electronic and photoelectrochemical devices. (c) 2013 Elsevier B.V. All rights reserved.
Urchin-like Ag Nanowires as Non-enzymatic Hydrogen Peroxide Sensor
(2012-04-01)
Hsiao, Wei-Han
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Chen, Hsin-Yu
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Cheng, Ta-Ming
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Huang, Ting-Kai
;
Chen, Yu-Liang
Urchin-like Ag nanowires were prepared by reacting AgNO3(aq) with Cu metal in the presence of cetyltrimethylammonium chloride and HNO3(aq) on a screen printed carbon electrode at room temperature. The diameters of the nanowires were about 100 nm, while the lengths were up to 10 mu m. Cyclic voltammetric experiments using the Ag nanowires as the working electrode showed electrocatalytic H2O2 reduction. The electrode exhibited a high sensitivity of 4705 mu A mM(-3) me cm(-2) from 50 mu M to 10.35 rnM and a measurable detection limit of 10 mu M in amperometric detection. This is the first report on Ag NWs for non-enzymatic H2O2 sensing.