Browsing by Issue Date, starting with "2019-02-20"

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Nine-sector three-stage Fresnel lens concentrator (vol 58, pg 122, 2019)
(2019-02-20)
Chen, Yong-Da
;
Tu, Sheng Han
;
Hong, Hwen-Fen
;
Chen, Chun-Yi
;
Pan, Jui-Wen
Review on Nanomaterial-Based Melamine Detection
(2019-02-20)
Shellaiah, Muthaiah
;
Sun, Kien Wen
;
應用化學系
;
電子工程學系及電子研究所
;
Department of Applied Chemistry
Illegal adulteration of milk products by melamine and its analogs has become a threat to the world. In 2008, the misuse of melamine with infant formula caused serious effects on babies of China. Thereafter, the government of China and the US Food and Drug Administration (FDA) limited the use of melamine of 1 mg/kg for infant formula and 2.5 mg/kg for other dairy products. Similarly, the World Health Organization (WHO) has also limited the daily intake of melamine of 0.2 mg/kg body weight per day. Many sensory schemes have been proposed by the scientists for carrying out screening on melamine poisoning. Among them, nanomaterial-based sensing techniques are very promising in terms of real-time applicability. These materials uncover and quantify the melamine by means of diverse mechanisms, such as fluorescence resonance energy transfer (FRET), aggregation, inner filter effect, surface-enhanced Raman scattering (SERS), and self-assembly, etc. Nanomaterials used for the melamine determination include carbon dots, quantum dots, nanocomposites, nanocrystals, nanoclusters, nanoparticles, nanorods, nanowires, and nanotubes. In this review, we summarize and comment on the melamine sensing abilities of these nanomaterials for their suitability and future research directions.
Efficient Tandem Organic Photovoltaics with Tunable Rear Sub-cells
(2019-02-20)
Cheng, Pei
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Liu, Yuqiang
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Chang, Sheng-Yung
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Li, Tengfei
;
Sun, Pengyu
A tandem structure was invented to enhance photon utilization efficiency and reduce thermal loss. Considering the unique advantages of non-fullerene acceptors (NFAs), the combination of NFAs and the tandem concept shows great potential for organic photovoltaics (OPVs). Herein, a simple strategy to balance the voltage-current trade-off in tandem OPVs by employing mixed NFAs in rear sub-cells is reported. The V-OC and J(SC) of rear sub-cells can be tuned by using the blend of donor/NFA/NFA. This strategy offers an easy approach to balance the V-OC and J(SC) in tandem OPVs toward higher power conversion efficiency (PCE) without rational and careful synthesis of new materials. Tandem OPVs based on mixed NFAs in rear sub-cells exhibited the best PCE of 13.3% in the lab. Importantly, the tandem devices were certified by the National Renewable Energy Laboratory (NREL) under asymptotic scans, and a PCE of 11.52% was achieved and recognized on the most recent NREL chart.
交大e-News第272期-交大台南分部：我國第一個大學研究校區
(2019-02-20)
國立交通大學秘書室
;
Secretariat
Carbon fiber ionization mass spectrometry coupled with solid phase microextraction for analysis of Benzo[a]pyrene
(2019-02-21)
Wu, Min-Li
;
Chen, Te-Yu
;
Chen, Wen-Jie
;
Baig, Mirza Muhammad Fahad
;
Wu, Yi-Cheng
Solid phase micro-extraction (SPME) is an effective technique that can be used to selectively enrich trace analytes of interest from complex samples. Owing to its high sensitivity and high selectivity, mass spectrometry (MS) has been widely used as the detection tool to confirm the analytes enriched on SPME fibers. Generally, thermal desorption or solvent desorption is used to desorb analytes from SPME fibers for MS analysis. A straightforward ionization method called carbon fiber ionization (CFI), which uses a single carbon fiber (diameter: similar to 10 mu m) as ionization emitter in MS, has been demonstrated lately. Analytes adsorbed on the carbon fiber, which is placed close (similar to 5 mm) to the inlet of a mass spectrometer, can be readily ionized through corona discharge and detected by the mass spectrometer. One unique feature regarding this approach over other existing ambient ionization methods is that no additional electric contact is applied directly on the carbon fiber. Nevertheless, on the basis of the electric field provided by the mass spectrometer, corona discharge can readily occur for ionizing analytes on the carbon fiber. Carbon fiber has high affinity toward polycyclic aromatic hydrocarbons due to its graphite-like surface structure. We herein explore a hyphenated-technique by combining carbon-fiber based SPME with CFI-MS for extraction of benzo[a]pyrene (BaP), a carcinogen, from aqueous samples. After BaP are adsorbed on a carbon fiber through SPME, the SPME carbon fiber can be readily placed in front of the mass spectrometer for MS analysis. The ions at m/z 252 derived from BaP adsorbed on the carbon fiber can be immediately acquired by the mass spectrometer without the requirement of applying heating or solvent. The limit of detection of BaP using the developed method was as low as similar to 60 pM. It is also feasible to detect BaP from complex serum sample. The feasibility of using the approach for quantitative analysis of BaP was also demonstrated. The linear dynamic range toward BaP was 0.2-5 nM. The extraction efficiency using this approach for aqueous samples was similar to 91%. (C) 2018 Elsevier B.V. All rights reserved.
RESONANT MAGNETIC COUPLING WIRELESS POWER TRANSFER SYSTEM WITH CALIBRATION CAPABILITIES OF ITS INDUCTOR-CAPACITOR RESONANT FREQUENCIES
(2019-02-21)
HAO-CHIAO HONG
A resonant magnetic coupling wireless power transfer system with calibration capabilities of the resonant frequencies of its power transmitter(s) and power receiver(s) is disclosed. The system detects the peak voltages of the coil inductors or the resonant capacitors and tunes the resonant capacitors until the detected peak voltages reach their maximal values given proper setup conditions, so as to calibrate the inductor-capacitor (LC) resonance frequencies of the power transmitter(s) and the power receiver(s) in the resonant magnetic coupling wireless power transfer system to achieve the highest power transferred to the load and a high PTE.
Enhancing photovoltaic performance by tuning the domain sizes of a small-molecule acceptor by side-chain-engineered polymer donors
(2019-02-21)
Lin, Yu-Che
;
Lu, Yi-Ju
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Tsao, Cheng-Si
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Saeki, Akinori
;
Li, Jia-Xing
This paper reports two new fluorine-substituted polymer donors (BO2FC8, BO2FEH), with different side-chain architectures, and a new chlorine-substituted small-molecule acceptor (m-ITIC-OR-4Cl) that are capable of simultaneous charge and energy transfer as the binary blend active layer for organic photovoltaics. We first resolved the single-crystal structure of m-ITIC-OR-4Cl and then used simultaneous grazing-incidence wide-and small-angle X-ray scattering to decipher the multi-length-scale structures-such as the shape and size of aggregated domains and molecular orientation-of the blends of BO2FEH and BO2FC8 with m-ITIC-OR-4Cl. The linear side chains of BO2FC8 facilitated its packing and, thus, induced m-ITIC-OR-4Cl to form smaller disc-shaped aggregated domains (thickness: 2.9 nm) than its aggregate domain (thickness: 5.4 nm) in the blend of the branched BO2FEH. That is, the binary blend system of linear-side-chain BO2FC8 with m-ITIC-OR-4Cl featured larger interfacial areas and more pathways for charge transfer and transport, as evidenced by their carrier mobilities. The highest power conversion efficiency (PCE) of 11.0% was that for the BO2FC8: m-ITIC-OR-4Cl device, being consistent with the predicted PCE of 11.2% using machine learning based on random forest algorism; in comparison, the PCE of the BO2FEH:m-ITIC-OR-4Cl device was 6.4%. This study has not only provided insight into the photovoltaic performances of new polymer donor/small-molecule acceptor blends but has also, for the first time, deciphered the hierarchical morphologies-from molecule orientation to nano-domain shape and size-of such blend systems, linking the morphologies to the photovoltaic performances. The use of side-chain architectures suggests an approach for tuning the morphology of the polymer/small-molecule binary blend active layer for use in organic photovoltaics.
Enhanced Photocarrier Generation with Selectable Wavelengths by M-Decorated-CuInS2 Nanocrystals (M = Au and Pt) Synthesized in a Single Surfactant Process on MoS2 Bilayers
(2019-02-22)
Tang, Shin-Yi
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Medina, Henry
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Yen, Yu-Ting
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Chen, Chia-Wei
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Yang, Tzu-Yi
A facile approach for the synthesis of Au- and Pt-decorated CuInS2 nanocrystals (CIS NCs) as sensitizer materials on the top of MoS2 bilayers is demonstrated. A single surfactant (oleylamine) is used to prepare such heterostructured noble metal decorated CIS NCs from the pristine CIS. Such a feasible way to synthesize heterostructured noble metal decorated CIS NCs from the single surfactant can stimulate the development of the functionalized heterostructured NCs in large scale for practical applications such as solar cells and photodetectors. Photodetectors based on MoS2 bilayers with the synthesized nanocrystals display enhanced photocurrent, almost 20-40 times higher responsivity and the On/Off ratio is enlarged one order of magnitude compared with the pristine MoS2 bilayers-based photodetectors. Remarkably, by using Pt- or Au-decorated CIS NCs, the photocurrent enhancement of MoS2 photodetectors can be tuned between blue (405 nm) to green (532 nm). The strategy described here acts as a perspective to significantly improve the performance of MoS2-based photodetectors with the controllable absorption wavelengths in the visible light range, showing the feasibility of the possible color detection.
《逐步東行》，說些關於家鄉的「東西」。
(國立交通大學傳播與科技學系, 2019-02-25)
Hsien Chuang
《逐步東行》--一本竹東的在地刊物中，編輯群是跌破眾人眼鏡、來自竹東國中美術班的幾位學生。從背著相機記錄竹東在地風景、採訪店家，到刊物中細緻的插畫和清新的文字，每期《逐東》都是學生們花了將近八個月的心血，從甄選、學習相關課程、到交稿、退稿、再改稿，才堆砌出這本在地刊物獨有的溫度。
Sunny-Side-Up Egg-Shaped Structures: Surface Modification To Form Anisotropic Polymer Particles Driven by the Plateau-Rayleigh Instability as Fluorescence Manipulation Platforms
(2019-02-26)
Chiu, Yu-Jing
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Liu, Chih-Ting
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Weng, Chang-Ching
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Chiu, Tang-Yao
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Li, Jia-Wei
The Plateau-Rayleigh instability is a phenomenon driven by the reduction of the surface energies, in which a liquid cylinder transforms to a series of droplets with distinct spacing. This instability phenomenon is also applied broadly for the transformation of cylindrical materials to spherical particles in homogeneous environments. The demonstration of the instability in heterogeneous environments, however, has been less studied. Here, we study the Plateau-Rayleigh instability of electrospun polystyrene (PS)/poly(methyl methacrylate) (PMMA) core-shell fibers annealed on n-octadecyl-trichlorosilane (ODTS)-modified glass substrates with toluene vapors. After the annealing procedures, the PS/PMMA core-shell fibers transform to anisotropic sunny-side-up egg-shaped polymer structures, driven by the reduction of the total surface and interfacial energies. Quantitative analyses are performed on the sizes of the structures. Fluorescent fibers are also prepared by electrospinning and annealed on the ODTS-modified substrates, demonstrating the potential application as fluorescence manipulation platforms.
Enhanced photoelectrochemical hydrogen generation in neutral electrolyte using non-vacuum processed CIGS photocathodes with an earth-abundant cobalt sulfide catalyst
(2019-02-28)
Wang, Mingqing
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Chang, Yung-Shan
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Tsao, Chun-Wen
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Fang, Mei-Jing
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Hsu, Yung-Jung
This work reports the novelty of using eco-friendly and cost-effective non-vacuum Electrostatic Spray-Assisted Vapour Deposited Cu(In, Ga) SSe (CIGS) thin films as photocathodes, combined with the earth abundant cobalt sulfide (Co-S) as a catalyst to accelerate the kinetics of photogenerated electron transfer and hydrogen generation for photoelectrochemical water splitting. CdS and ZnO layers were subsequently deposited on top of the selenised CIGS films to increase the charge separation and lower the charge recombination for the photocathodes. In order to improve the lifetime and scalability of the CIGS photocathode and the other cell components, a photoelectrochemical test was conducted in a neutral electrolyte of 0.5 M Na2SO4 under simulated sunlight (AM 1.5G). Both the photocurrent densities and the onset potentials of the photocathodes were significantly improved by the electro-deposition of the low cost and earth-abundant Co-S catalyst, with a photocurrent density as high as 19.1 mA cm(-2) at -0.34 V vs. reversible hydrogen electrode (RHE), comparable with and even higher than that of the control photocathode using rare and precious Pt as a catalyst.
RcsB regulation of the YfdX-mediated acid stress response in Klebsiella pneumoniae CG43S3
(2019-02-28)
Liu, Chia-Jui
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Lin, Ching-Ting
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Chiang, Jo-Di
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Lin, Chen-Yi
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Tay, Yen-Xi
In Klebsiella pneumoniae CG43S3, deletion of the response regulator gene rcsB reduced the capsular polysaccharide amount and survival on exposure to acid stress. A comparison of the pH 4.4-induced proteomes between CG43S3 and CG43S3.rcsB revealed numerous differentially expressed proteins and one of them, YfdX, which has recently been reported as a periplasmic protein, was absent in CG43S3.rcsB. Acid survival analysis was then conducted to determine its role in the acid stress response. Deletion of yfdX increased the sensitivity of K. pneumoniae CG43S3 to a pH of 2.5, and transforming the mutant with a plasmid carrying yfdX restored the acid resistance (AR) levels. In addition, the effect of yfdX deletion was cross-complemented by the expression of the periplasmic chaperone HdeA. Furthermore, the purified recombinant protein YfdX reduced the acid-induced protein aggregation, suggesting that YfdX as well as HdeA functions as a chaperone. The following promoter activity measurement revealed that rcsB deletion reduced the expression of yfdX after the bacteria were subjected to pH 4.4 adaptation. Western blot analysis also revealed that YfdX production was inhibited by rcsB deletion and only the plasmid expressing RcsB or the nonphosphorylated form of RcsB, RcsBD56A, could restore the YfdX production, and the RcsB-mediated complementation was no longer observed when the sensor kinase RcsD gene was deleted. In conclusion, this is the first study demonstrating that YfdX may be involved in the acid stress response as a periplasmic chaperone and that RcsB positively regulates the acid stress response partly through activation of yfdX expression. Moreover, the phosphorylation status of RcsB may affect the YfdX expression under acidic conditions.
A curvature-tunable random laser
(2019-02-28)
Lee, Ya-Ju
;
Yeh, Ting-Wei
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Yang, Zu-Po
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Yao, Yung-Chi
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Chang, Chen-Yu
The application of random lasers has been restricted due to the absence of a well-defined resonant cavity, as the lasing action mainly depends on multiple light scattering induced by intrinsic disorders of the laser medium to establish the required optical feedback that hence increases the difficulty in efficiently tuning and modulating random lasing emissions. This study investigated whether the transport mean free path of emitted photons within disordered scatterers composed of ZnO nanowires is tunable by a curvature bending applied to the flexible polyethylene terephthalate (PET) substrate underneath, thereby creating a unique light source that can be operated above and below the lasing threshold for desirable spectral emissions. For the first time, the developed curvature-tunable random laser is implemented for in vivo biological imaging with much lower speckle noise compared to the non-lasing situation through simple mechanical bending, which is of great potential for studying the fast-moving physiological phenomenon such as blood flow patterns in mouse ear skin. It is expected that the experimental demonstration of the curvature-tunable random laser can provide a new route to develop disorder-based optoelectronic devices.
Bromine-Radical-Mediated Site-Selective Allylation of C(sp(3))-H Bonds
(2019-03-01)
Ueda, Mitsuhiro
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Maeda, Ayami
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Hamaoka, Kanako
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Sasano, Mika
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Fukuyama, Takahide
The C(sp(3))-H allylation of alkanes is investigated by using allyl bromides under radical reaction conditions. In many cases, methine C-H allylation preceded methylene and methyl C-H allylation with complete or a high degree of site selectivity. The C-H allylation of allylic compounds, such as allylbenzene, gives 1,5-dienes with the S(H)2' reactions of the allyl radicals occurring at the less hindered carbon.
Hexanoyl chitosan/ENR25 blend polymer electrolyte system for electrical double layer capacitor
(2019-03-01)
Winie, Tan
;
Jamal, Asheila
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Saaid, Farish Irfal
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
Single salt polymer electrolytes based on hexanoyl chitosan-ENR25 were prepared by employing LiN (CF3SO2)(2) or LiCF3SO3 as the doping salt. Elastic property of hexanoyl chitosan was enhanced with the incorporation of ENR25. DSC studies revealed immiscibility of hexanoyl chitosan and ENR25, and dissolution of salt was favored in ENR25 phase. Conductivity enhancement was observed in the blends as compared with the neat hexanoyl chitosan. The maximum conductivities achieved for LiCF3SO3- and LiN (CF3SO2)(2)-comprising electrolyte systems were 1.6 x 10(-8) and 5.0 x 10(-7) S cm(-1), respectively. Deconvolution of spectra bands in the v(as) (SO2-) mode of LiN (CF3SO2)(2) and v(s) (SO3-) mode of LiCF3SO3 has been carried out to estimate the relative percentage of free ions and associated ions. The findings were in good agreement with conductivity results. Electrical double layer capacitor (EDLC) was fabricated with hexanoyl chitosan/ENR25 (90:10)-LiN (CF3SO2)(2)-EmImTFSI electrolyte and activated carbon-based electrodes. The conductivity and electrochemical stability window of hexanoyl chitosan/ENR25-LiN (CF3SO2)(2)-EmImTFSI were similar to 10(-6) S cm(-1) and 2.7 V, respectively. The performance of the EDLC was analyzed by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). From GCD, the specific capacitance of EDLC was 58.0 F g(-1) at 0.6 mA cm(-2). The specific capacitance was found to decrease with increasing current density.
A trading decision support model to maximize the sustainability of a self-financed guaranteed farmgate price program
(2019-03-01)
Chen, Wen-Chih
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Wu, Cheng-Hung
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工業工程與管理學系
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Department of Industrial Engineering and Management
We study a non-government organization (NGO) program that supports the household livelihood of small farmers by committing to purchase a fixed quantity at a guaranteed farmgate price of a storable agri-product under price fluctuation. Since the World Trade Organization (WTO) disciplines its members to limit and reduce domestic support for the agriculture, storing and trading (selling) the product on the spot market at a favorable price generates revenue to cover the cost of the program. The objective of this study is to develop a stochastic dynamic trading decision model that maximizes the sustainability of the NGO's supporting program, measured as the survival probability, i.e. the probability that the program can continue operating after a predetermined period of time. The results of a numerical study, based on the tilapia aquaculture in Taiwan, show that our model yields higher survival probability (after 4 years) than the profit-maximization policy by close to 10% in average. Moreover, the trading decision optimization is particularly suitable for market environments with high price fluctuation, i.e. the most challenging circumstances for small farmers.
Sheaf lines of Yang-Mills instanton sheaves
(2019-03-01)
Lai, Sheng-Hong
;
Lee, Jen-Chi
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Tsai, I-Hsun
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電子物理學系
;
Department of Electrophysics
We calculate a sheaf line in CP3 which is the real line supporting sheaf points on CP3 of SL(2, C) Yang-Mills (YM) instanton (or SU(2) complex YM instanton) sheaves for some given ADHM data we obtained previously. We found that this sheaf line is indeed a special jumping line over S-4 spacetime. In addition, we calculate the singularity structure of the connection A and the field strength F at the corresponding singular point on S-4 of this sheaf line. We found that the order of singularity at the singular point on S-4 associated with the sheaf line in CP3 is higher than those of other singular points associated with normal jumping lines. We conjecture that this is a general feature for sheaf lines among jumping lines.
Design Automation for Dilution of a Fluid Using Programmable Microfluidic Device-Based Biochips
(2019-03-01)
Gupta, Ankur
;
Huang, Juinn-Dar
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Yamashita, Shigeru
;
Roy, Sudip
;
電子工程學系及電子研究所
Microfluidic lab-on-a-chip has emerged as a new technology for implementing biochemical protocols on small-sized portable devices targeting low-cost medical diagnostics. Among various efforts of fabrication of such chips, a relatively new technology is a programmable microfluidic device (PMD) for implementation of flow-based lab-on-a-chip. A PMD chip is suitable for automation due to its symmetric nature. In order to implement a bioprotocol on such a reconfigurable device, it is crucial to automate a sample preparation on-chip as well. In this article, we propose a dilution PMD algorithm (namely DPMD) and its architectural mapping scheme (namely generalized architectural mapping algorithm (GAMA)) for addressing fluidic cells of such a device to perform dilution of a reagent fluid on-chip. We used an optimization function that first minimizes the number of mixing steps and then reduces the waste generation and further reagent requirement. Simulation results show that the proposed DPMD scheme is comparative to the existing state-of-the-art dilution algorithm. The proposed design automation using the architectural mapping scheme reduces the required chip area and, hence, minimizes the valve switching that, in turn, increases the life span of the PMD-chip.
【學術交流】華盛頓大學黃正能教授演講
(國立交通大學資訊學院, 2019-03)
黃粵丞/資科工博士生
黃正能教授，於1981 和1983 年在台灣大學取得電子工程學士與碩士學位，並於1988 年在University of Southern California 取得博士學位。在1989 年在華盛頓大學任職，研究的領域為多媒體訊號處理、多媒體網路、影像處理、電腦視覺及圖形識別，已在國際期刊、國際會議論文集、書籍和書籍章節發表超過300 篇研究論文。黃正能教授於10 月21 日應邀蒞臨資訊學院演講，講題為：Coordinated Visual 3D Physical World Exploration for Smart City，本次演講探討3D 視覺技術如何應用在未來的智慧城市發展，旁及一些有趣的研究方向，並討論相關的理論基礎及研究成果。
Control of plasmon dephasing time using stacked nanogap gold structures for strong near-field enhancement
(2019-03-01)
Ueno, Kosei
;
Yang, Jinghuan
;
Sun, Quan
;
Aoyo, Daisuke
;
Yu, Han
The construction of metallic nanostructures with strong near-field enhancement is becoming increasingly significant for the practical use of plasmonic devices, such as plasmonic sensors and light-energy conversion systems. Importantly, the near-field enhancement effect depends on the plasmon dephasing time. Here, we propose a method for controlling plasmon dephasing time by utilizing plasmonic coupling for stronger near-field enhancement. Ordered arrays of stacked nanogap gold (Au) structures composed of a metal/insulator/metal nanostructure were fabricated by electron beam lithography and dry etching processes on a niobium-doped titanium dioxide substrate. The dark plasmon mode was excited by the near-field coupling between the upper and lower Au nanostructures separated by an alumina layer with a thickness of 15 nm. A strong near-field enhancement effect was induced by the localization of the electromagnetic field between the upper and lower Au nanostructures and the longer plasmon dephasing time based on the excitation of the dark plasmon mode. It is noteworthy that the dephasing time of the dark plasmon mode measured by time-resolved photoemission electron microscopy was extended 3-fold compared with that of the plasmon mode of the Au nanoblock, which can be controlled by the structural design of the stacked nanogap Au structures. (C) 2018 Elsevier Ltd. All rights reserved.