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交大e-News第232期-校長講座─從醫轉商大立光林恩平執行長鼓勵學生跨域學習
(2017-05-22)
國立交通大學秘書室
;
Secretariat
Competitive Interactions of pi-pi Junctions and Their Role on Microphase Separation of Chiral Block Copolymers
(2017-05-23)
Wen, Tao
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Lee, Jing-Yu
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Li, Ming-Chia
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Tsai, Jing-Cherng
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Hoy, Rong-Ming
Herein, enantiomeric polylactide-containing chiral block copolymers (BCPs*) with aliphatic and aromatic junctions are designed and synthesized for investigating the impact of junction pi-pi interactions on the self-assembly of BCPs*. A profound effect on the microphase separation of the BCP* can be found by introducing the pi-pi interaction of junctions, resulting in reduced structural ordering due to the mixing of constituted blocks by the formation of junction pi-stacking. An ordered microphase-separated structure of the BCP* can be obtained by decreasing the number of aromatic rings of the junction or increasing the total molecular weight of the BCP*. Accordingly, competitive interactions of pi-pi junctions and microphase separation of the BCP* can be manifested by tuning the thermodynamic driving force for self-organization through molecular design. Most interestingly, the self-assembled morphology can be amended by self-assembling the BCP* from solution through the kinetic control of solvent evaporation. Fast solvent evaporation limits the formation of junction stacking while slow solvent evaporation enhances the stacking between junctions, and thus depresses the microphase separation of BCPs*. The self-assembled mechanisms are further evidenced by spectroscopic results and the corresponding induced circular dichroism (ICD) behaviors of the aromatic junctions. This work demonstrates a new approach to thermodynamically and kinetically regulate the self-assembled morphologies of BCP* by introducing the competitive interactions of pi-pi junctions on self-assembly.
Computational Chemical Kinetics for the Reaction of Criegee Intermediate CH2OO with HNO3 and Its Catalytic Conversion to OH and HCO
(2017-05-25)
Raghunath, P.
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Lee, Yuan-Pern
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Lin, M. C.
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應用化學系
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應用化學系分子科學碩博班
The kinetics and mechanisms for the reaction of the Criegee intermediate CH2OO with HNO3 and the unimolecular decomposition of its reaction product CH2(O)NO3 are important in atmospheric chemistry. The potential-energy profile of the reactions predicted with the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ method shows that the initial association yields a prereaction complex that isomerizes by H migration to yield excited intermediate nitrooxymethyl hydroperoxide NO3CH2OOH* with internal energy similar to 44 kcal mol(-1). A fragmentation of this excited intermediate produces CH2(O)NO3 + OH with its transition state located 5.0 kcal mor(-1) below that of the reactants. Further decomposition of CH2(O)NO3 produces HCO + HNO3, forming a catalytic cycle for destruction of CH2OO by HNO3. The rate coefficients and product-branching ratios were calculated in the temperature range 250-700 K at pressure 20-760 Torr (N-2) using the variational-transition-state and Rice-Ramsperger-Kassel-Marcus (RRKM) theories. The predicted total rate coefficient for reaction CH2OO + HNO3 at 295 K, 5.1 x 10(-10) cm(3) molecule(-1) s(-1), agrees satisfactorily with the experimental value, (5.4 +/- 1.0) X 10(-10) cm(3) molecule(-1) s(-1). The predicted branching ratios at 295 K are 0.21 for the formation of NO3CH2OOH and 0.79 for CH2(O)NO3 + OH at a pressure of 40 Torr (N-2), and 0.79 for the formation of NO3CH2OOH and 0.21 for CH2(O)NO3 + OH at 760 Torr (N-2). This new catalytic conversion of CH2OO to HCO + OH by HNO3 might have significant impact on atmospheric chemistry.
METHOD FOR ANALYZING AND SEARCHING 3D MODELS
(2017-05-25)
I-Chen LIN
;
Jun-Yang LIN
;
Mei-Fang SHE
;
Wen-Hsiang TSAI
A method for analyzing and searching 3D models includes steps of obtaining data global features and data local features of data images by globally analyzing and locally analyzing data images of 3D models respectively; obtaining searching global features and searching local features by globally analyzing and locally analyzing searching images respectively; obtaining corresponding data global features and corresponding data local features based on the search global features and the searching local feature; and obtaining corresponding data images based on the corresponding data global features and the corresponding data local features.
Nonvolatile reconfigurable sequential logic in a HfO2 resistive random access memory array
(2017-05-28)
Zhou, Ya-Xiong
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Li, Yi
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Su, Yu-Ting
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Wang, Zhuo-Rui
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Shih, Ling-Yi
Resistive random access memory (RRAM) based reconfigurable logic provides a temporal programmable dimension to realize Boolean logic functions and is regarded as a promising route to build non-von Neumann computing architecture. In this work, a reconfigurable operation method is proposed to perform nonvolatile sequential logic in a HfO2-based RRAM array. Eight kinds of Boolean logic functions can be implemented within the same hardware fabrics. During the logic computing processes, the RRAM devices in an array are flexibly configured in a bipolar or complementary structure. The validity was demonstrated by experimentally implemented NAND and XOR logic functions and a theoretically designed 1-bit full adder. With the trade-off between temporal and spatial computing complexity, our method makes better use of limited computing resources, thus provides an attractive scheme for the construction of logic-in-memory systems.
High performance solution-processable tetrathienoacene (TTAR) based small molecules for organic field effect transistors (OFETs)
(2017-05-28)
Vegiraju, Sureshraju
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Huang, Deng-Yi
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Priyanka, Pragya
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Li, Yo-Shan
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Luo, Xian-Lun
Three new organic semiconductors with alkyl chain-substituted tetrathienoacene (TTAR) as the central core and both ends capped with thiophene (DT-TTAR), thienothiophene (DTT-TTAR) and dithienothiophene (DDTT-TTAR) have been synthesized and characterized for organic field effect transistor (OFET) applications. A hole mobility of 0.81 cm(2) V-1 s(-1) was achieved for the DDTT-TTAR film, which represents the highest mobility yet found for a solution-processable p-type TTAR-based small molecular semiconductors.
Enhanced photocatalytic activity of Cu-deposited N-TiO2/titanate nanotubes under UV and visible light irradiations
(2017-05-31)
Doong, Ruey-an
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Liao, Chun-Yi
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環境工程研究所
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Institute of Environmental Engineering
A rapid and green synthesis of Cu-deposited N-doped TiO2/titanate nanotubes (TNTs) by the aid of microwave-assisted hydrothermal method was developed for the enhanced photocatalytic activity toward bisphenol A (BPA) degradation under UV and visible light irradiations. The TNTs are first synthesized at 150 degrees C for 3 h by microwave-assisted method followed by the calcination at 450 degrees C under NH3/N-2 atmosphere after the adsorption of 2-10 wt% Cu(II) ions to produce metallic Cu-deposited N-TiO2/TNTs nanocomposites. The microstructural analyses show that the Cu(II) ions are converted to Cu-0 in NH3/ N-2 with mean particle sizes of 39-42 nm and N atoms are incorporated into the lattices of TiO2/TNTs. The Cu-deposited N-TiO2/TNT nanocomposites show the superior photoactivity toward BPA degradation under both UV and visible light irradiations. The photodegradation efficiency and rate of BPA increases upon increasing Cu amount and the optimal mass loadings of 8-10 wt% are obtained. In addition, the pseudo-first-order rate constants for BPA degradation increase 5.3-6.8 and 2.1-3.0 times under UV and visible light irradiations, respectively, when compare with those of Degussa P25 TiO2. The Schottky barrier between Cu-0 and N-TiO2 promotes the electron transfer from N-doped TiO2 to metallic Cu nanoparticles under UV and visible light irradiations, resulting in the efficient generation of prolonged oxygen-containing radicals for enhanced photodegradation of BPA. Results obtained in this study clearly open a new pave for the green synthesis of 1-dimensional metal-metal oxide nanophotocatalysts which can be potentially used in the fields of purification, green chemistry and photocatalysis. (C) 2017 Elsevier B.V. All rights reserved.
Selective Detection of Shiga-like Toxin 1 from Complex Samples Using Pigeon Ovalbumin Functionalized Gold Nanoparticles as Affinity Probes
(2017-05-31)
Li, Chun-Hsien
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Bai, Yi-Ling
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Selvaprakash, Karuppuchamy
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Mong, Kwok-Kong Tony
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Chen, Yu-Chie
Escherichia coli 0151:H7 is a foodborne pathogen. This bacterial strain can generate Shiga-like toxins (SLTs), which can cause serious sickness and even death. Thus, it is important to develop effective and sensitive methods that can be used to rapidly identify the presence of SLTs from complex samples. Pigeon egg white (PEW) contains abundant glycoproteins, including pigeon ovalbumin (POA) (similar to 60%). POA possesses Gal-alpha(1 -> 4)-Gal-beta(1 -> 4)-GlcNAc termini,. which can recognize the B subunits in SLT type 1 (SLT-1B). Thus, POA is a suitable probe for trapping SLT-1B. In this work, we used PEW proteins as starting materials to react with aqueous tetrachloroauric acid for generation of PEW-protein-immobilized gold nanoparticles (AuNPs@PEW) via one-pot reactions. We demonstrated that the generated AuNPs@PEW were mainly dominated by POA-immobilized Au NPs. The as-prepared AuNPs@PEW were used as affinity probes to selectively probe SLT-1B from complex cell lysates derived from E. coli 0157:H7. The selective trapping step can be completed within similar to 90 s under microwave heating (power = 450 W) to enrich sufficient SLT-1B for Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis. Furthermore; this approach:can be used to detect SLT-1B at a concentration as low as similar to 40 pM. The feasibility of using the proposed method to selectively detect SLT-1B from ham contaminated by E. coli 0157:H7 was also demonstrated.
Site-controlled crystalline InN growth from the V-pits of a GaN substrate
(2017-05-31)
Kuo, Chien-Ting
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Hsu, Lung-Hsing
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Lai, Yung-Yu
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Cheng, Shan-Yun
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Kuo, Hao-Chung
A site-controlled crystalline InN growth from the V-pits of a GaN substrate was investigated. The V-pits were fabricated by epitaxial lateral growth of GaN over SiO2 disks patterned on a sapphire substrate. InN crystals were found to preferably grow on the inclined {10-11} crystal planes of the V-pits. A V-pit size of 1 mu m or less can provide precise site-controlled InN nucleation at the V-pit bottom, while no InN was grown on the rest of the exposed GaN surfaces. The site-controlled nucleation is attributed to the low surface energy point created by the converging six {10-11} crystal facets at the V-pit bottom. When In source supply is below a certain value, this V-pit bottom is the only location able to aggregate enough active sources to start nucleation, thereby providing site-controlled crystal growth. (C) 2017 Elsevier B.V.
Unveiling the influence of inner spacer length of the non-linear S-shaped chiral oligomers on liquid crystalline phase
(2017-06-01)
Yeap, Guan-Yeow
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Osman, Faridah
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Maeta, Nobuyuki
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Ito, Masato M.
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Lin, Chien-Min
A series of S-shaped liquid crystal oligomers consisting of biphenylene, catechol and cholesterol moieties have been synthesized and characterized. The members in this series differ by the length of inner spacers -(CH2)(n)-where n are varied from 4 to 9 whereas the outer spacer of undecanoate chain is remained intact. The texture and phase transition temperatures with associated enthalpy changes are recorded. Increase in the number of carbon atom at the inner spacer affects the stability of liquid crystalline phase. The homologues with shorter inner spacers n = 4 and 5 exhibit monotropic N* whilst the analogue with medium spacer n = 6 exhibits monotropic N* and SmC* phase. However, the oligomers with longer spacers n = 7, 8 and 9 exhibit enantiotropic N* and SmC* phase. The I -N* transition temperatures were found to depend on the parity of the inner spacers. An Xray diffraction study reveals that the S-shaped oligomers exist as a monolayer chiral smectic C phase. (C) 2017 Elsevier B.V. All rights reserved.
Photothermal imaging of skeletal muscle mitochondria
(2017-06-01)
Tomimatsu, Toru
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Miyazaki, Jun
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Kano, Yutaka
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Kobayashi, Takayoshi
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電子物理學系
The morphology and topology of mitochondria provide useful information about the physiological function of skeletal muscle. Previous studies of skeletal muscle mitochondria are based on observation with transmission, scanning electron microscopy or fluorescence microscopy. In contrast, photothermal (PT) microscopy has advantages over the above commonly used microscopic techniques because of no requirement for complex sample preparation by fixation or fluorescent-dye staining. Here, we employed the PT technique using a simple diode laser to visualize skeletal muscle mitochondria in unstained and stained tissues. The fine mitochondrial network structures in muscle fibers could be imaged with the PT imaging system, even in unstained tissues. PT imaging of tissues stained with toluidine blue revealed the structures of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria and the swelling behavior of mitochondria in damaged muscle fibers with sufficient image quality. PT image analyses based on fast Fourier transform (FFT) and Grey-level co-occurrence matrix (GLCM) were performed to derive the characteristic size of mitochondria and to discriminate the image patterns of normal and damaged fibers. (C) 2017 Optical Society of America
The study of wet etching on GaN surface by potassium hydroxide solution
(2017-06-01)
Lai, Yung-Yu
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Hsu, Shih-Chieh
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Chang, Hua-Sheng
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Wu, YewChung Sermon
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Chen, Ching-Hsiang
Potassium hydroxide solution was used to etch un-doped GaN grown on the sapphire substrate at 180 and 260 A degrees C. We illustrated the etching phenomenon in detail and probed its mechanism in the wet etching process. By multiplying the planar density and the number of dangling bonds on the N atom, we proposed the etching barrier index (EBI) to describe the difficulty degree of each lattice facet. The raking of EBI will be +c-plane > a-plane > m-plane > -c-plane > (10-1-1) plane > r-plane. Combining the EBI with SEM results, we thoroughly studied the whole etching process. We confirmed that in our research, KOH wet etching on GaN starts from the r-plane instead of the +c-plane or -c-plane, which differs from other studies. We also found that during the high-temperature etching process, there are two etching approaches. In one, the etching begins vertically from the top to the bottom, then horizontally, and finally reversely from the bottom to the top. In the other, etching pits will develop into a hexagonal hole of the sidewall of m-plane.
Randomized, Multicenter Trial of ARTSS-2 (Argatroban With Recombinant Tissue Plasminogen Activator for Acute Stroke)
(2017-06-01)
Barreto, Andrew D.
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Ford, Gary A.
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Shen, Loren
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Pedroza, Claudia
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Tyson, Jon
Background and Purpose-We conducted a randomized exploratory study to assess safety and the probability of a favorable outcome with adjunctive argatroban, a direct thrombin-inhibitor, administered to recombinant tissue-type plasminogen activator (r-tPA)-treated ischemic stroke patients. Methods-Patients treated with standard-dose r-tPA, not receiving endovascular therapy, were randomized to receive no argatroban or argatroban (100 mu g/kg bolus) followed by infusion of either 1 (low dose) or 3 mu g/kg per minute (high dose) for 48 hours. Safety was incidence of symptomatic intracerebral hemorrhage. Probability of clinical benefit (modified Rankin Scale score 0-1 at 90 days) was estimated using a conservative Bayesian Poisson model (neutral prior probability centered at relative risk, 1.0 and 95% prior intervals, 0.33-3.0). Results-Ninety patients were randomized: 29 to r-tPA alone, 30 to r-tPA+low-dose argatroban, and 31 to r-tPA+high-dose argatroban. Rates of symptomatic intracerebral hemorrhage were similar among control, low-dose, and high-dose arms: 3/29 (10%), 4/30 (13%), and 2/31 (7%), respectively. At 90 days, 6 (21%) r-tPA alone, 9 (30%) low-dose, and 10 (32%) high-dose patients were with modified Rankin Scale score 0 to 1. The relative risks (95% credible interval) for modified Rankin Scale score 0 to 1 with low, high, and either low or high dose argatroban were 1.17 (0.57-2.37), 1.27 (0.63-2.53), and 1.34 (0.68-2.76), respectively. The probability that adjunctive argatroban was superior to r-tPA alone was 67%, 74%, and 79% for low, high, and low or high dose, respectively. Conclusions-In patients treated with r-tPA, adjunctive argatroban was not associated with increased risk of symptomatic intracerebral hemorrhage and provides evidence that a definitive effectiveness trial is indicated.
Fabrication of hydrothermally reduced graphene oxide/chitosan composite membranes with a lamellar structure on methanol dehydration
(2017-06-01)
Hung, Wei-Song
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Chang, Sue-Mm
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Lecaros, Rumwald Leo G.
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Ji, Yan-Li
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An, Quan-Fu
Reduced graphene oxide (rGO) has been prepared through hydrothermal reduction, an environmentally safe reduction of graphene oxide (GO). rGO is used to fabricate a highly compatible and orderly stacked lamellar structure of composite membranes with chitosan (CS). This method also facilitates a continuous large-scale fabrication of membranes. Conventionally, GO and CS are the preferred compounds for this type of fabrication because of their hydrophilic nature. Nevertheless, when they are mixed together, the occurrence of ionic complexation (-COO-H3+N-R) between the negatively charged carboxylate ions of GO and the positively charged protonated amines of CS create extreme membrane aggregation. Hydrothermal reduction is useful for preventing undesired ionic complexation from mixing rGO and CS because it can remove most carboxylate ions from GO. Consequently, the hydrophilic CS molecular chain is inserted in between the rGO laminates, improving the dispersion and enabling the rGO/CS to stack-up and self-assemble into a lamellar structure. Furthermore, excellent methanol dehydration can be observed through pervaporation, which is attributed to the selective water channels formed in the rGO laminates. (C) 2017 Elsevier Ltd. All rights reserved.
Compact coupling scheme to achieve the synchronously dual self-mode-locked operation with a 35.2 THz optical beating
(2017-06-01)
Cheng, Hao Ping
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Huang, Tzu Lin
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Sung, Cheng Lin
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Cho, Chun Yu
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Liang, Hsing Chih
A synchronously dual self-mode-locked (SML) operation at 946 and 1064 nm is experimentally accomplished by using a compact coupling scheme to obtain the optical beating frequency up to 35.2 THz. The SML emissions at 946 and 1064 nm are established by a monolithic Nd:YAG cavity and a Nd: YVO4 crystal in a flat-flat cavity, respectively. Two gain media are butt adjoined to be longitudinally pumped by a single laser diode. The monolithic Nd: YAG crystal is used not only as the 946 nm laser cavity, but also as the output coupler of the Nd: YVO4 1064 nm laser. More importantly, the output surface of the monolithic Nd: YAG laser is coated to generate the optical feedback for the synchronization of the dual SML operation. At a pump power of 10.7 W, the output powers at 1064 and 946 nm can simultaneously reach 1.5 W by controlling the focal position of the pump waist. (C) 2017 Optical Society of America
NON-EQUIVALENCE OF SPECIFIC AND AD VALOREM TAXATION IN THE COMPETITIVE MARKET WITH TAX EVASION
(2017-06-01)
Huang, Che-Chiang
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Ueng, K. L. Glen
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Hu, Jin-Li
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經營管理研究所
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Institute of Business and Management
The well-known equivalence between specific and ad valorem taxation in competitive markets may not hold in the presence of tax evasion. Evading specific taxes has to take place via concealing quantities sold, whereas evading ad valorem taxes can take place via concealing selling prices as well as quantities sold. We show that in the competitive market (i) this difference could make the equivalence of these two taxes break down, and (ii) specific taxation may be superior to ad valorem taxation if it causes firms to channel fewer resources into tax evasion, given other things being equal.
Recovery of failed resistive switching random access memory devices by a low-temperature supercritical treatment
(2017-06-01)
Du, Xiaoqin
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Wu, Xiaojing
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Chang, Ting-Chang
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Chang, Kuan-Chang
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Pan, Chih-Hung
The successful recovery of resistive switching random access memory (RRAM) devices that have undergone switching failure is achieved by introducing a low-temperature supercritical-fluid process that passivates the switching layer. These failed RRAM devices, which are incapable of switching between high-and low-resistance states, were treated with supercritical carbon dioxide with pure water at 120 degrees C for 1 h. After the treatment, the devices became operational again and showed excellent current-voltage (I-V) characteristics and reliability as before. On the basis of the current conduction mechanism fitting results, we propose a model to explain the phenomenon. (C) 2017 The Japan Society of Applied Physics
Dimension dependent immunity of X-ray irradiation on low-temperature polycrystalline-silicon TFTs
(2017-06-01)
Wei, Yin-Chang
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Li, Yi-Chieh
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Lee, I-Che
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Cheng, Huang-Chung
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電子工程學系及電子研究所
Typically, each element in a large-area flat-panel X-ray image sensor consists of a photodetector and amorphous silicon (a-Si) thin-film transistor (TFT) switches. In order to reduce noise, increase sensor dynamic range, and increase carrying capacity, the low-temperature polycrystalline-silicon (LTPS) TFTs have been proposed as a candidate to replace the a-Si TFTs. However, there are concerns regarding the impact of X-ray radiation in LTPS-TFTs, and several studies have been conducted to inquire into the same. In this paper, we show that LTPS TFTs with small channel length (<2 mu m) are almost immune to X-ray radiation. (C) 2017 The Japan Society of Applied Physics
Characterization of LOCOS Field Oxide on 4H-SiC Formed by Ar Preamorphization Ion Implantation
(2017-06-01)
Tseng, Yuan-Hung
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Lin, Chung-Yu
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Tsui, Bing-Yue
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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
In this letter, the electrical properties of local oxidation of silicon (LOCOS) field oxide formed on 4H-SiC are reported. Moreover, unlike the conventional Si LOCOS process, a simpler method based on Ar preamorphization implantation is proposed. In addition to direct characterization of the field oxide, device properties achieved using LOCOS isolation are compared with those achieved using the conventional chemical vapor deposition oxide isolation to clarify the impact of isolation technology. The results of this letterwould be insightful for silicon-carbide-basedvery-large-scale integration technology.
Enhanced Light Extraction of High-Voltage Light Emitting Diodes Using a Sidewall Chamfer Structure
(2017-06-01)
Wu, Ping-Chen
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Ou, Sin-Liang
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Horng, Ray-Hua
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Wuu, Dong-Sing
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電子工程學系及電子研究所
High-voltage light-emitting diodes (HV-LEDs) were prepared with 4 x 2 microcells. A novel technique for enhancing the light extraction of HV-LEDs by using wet-etched chamfer structures in the sidewalls of each cell is proposed. The thicknesses of the u-GaN layers used were in the range of 3-7 mu m. Simulations revealed that the light extraction of the HV-LEDs with chamfer structures would be enhanced by increasing the u-GaN thickness. The output power (@ 80 mA) of the HV-LEDs without chamfer structures was 538.0-539.1 mW. However, the output powers (@ 80 mA) of the HV-LEDs with chamfer structures and u-GaN thicknesses of 3, 5, and 7 mu m were increased to 555.3, 573.1, and 561.6 mW, respectively. The 7 mu m thick u-GaN layer led to an extremely large thickness of the HV-LED epitaxial structure, which caused difficulties during the wet etching process. Because of the apparent decrease in the wet etching rate of GaN, the damages to the epitaxial structures of the HV-LED with the 7 mu m thick u-GaN was more obvious. Therefore, the device's light extraction was slightly reduced. The results confirm that chamfer structures are highly useful for improving the performance of HV-LEDs, especially for the u-GaN thickness of 5 mu m.