Browsing by Issue Date, starting with "2019-12-17"

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Bamboo-like nanostructures prepared using template-based wetting methods: Molecular arrangements of polyimide and carbon tubes in cylindrical nanopores
(2019-12-17)
Tu, Yi-Hsuan
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Liu, Chih-Ting
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Chu, Chien-Wei
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He, Hung-Chieh
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Chang, Chun-Wei
With excellent mechanical and physical properties, polyimides (PIs) possess diverse applications in different fields. PI-based materials can also be converted to carbon materials by high temperature carbonization processes. The fabrication and properties of PI-based nanomaterials and corresponding carbon nanomaterials, however, have been less investigated, especially the packing behaviors of the polymer chains. In this work, we study the fabrication and characterization of PI nanostructures using the solution wetting (SW) method and the solvent-annealing-induced nanowetting in templates (SAINT) method. Poly(amic acid) (PAA) tubes are first prepared using anodic aluminum oxide (AAO) membranes. After thermal imidization and carbonization processes, PI and carbon tubes can be obtained, respectively. Bamboo-like structures are also observed in the tubes, which can be attributed to the Marangoni effect induced by the gradient of the surface tensions during the solvent evaporation process. Moreover, the laser Raman micro-spectroscopy results show that the packing behaviors of the polymer chains in the nanostructures prepared by the SAINT method are better than those prepared by the SW method, indicating that the solvent annealing process can improve the chain packing while assisting the infiltration of polymer chains in the nanopores.
ZIF-8-Based Quasi-Solid-State Electrolyte for Lithium Batteries
(2019-12-18)
Sun, Cui
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Zhang, Jin-hua
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Yuan, Xiang-fei
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Duan, Jia-ning
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Deng, Sheng-wen
The quasi-solid-state electrolytes (QSSEs) with an inorganic skeleton, a solid-liquid composite material combining their respective merits, exhibit high ionic conductivity and mechanical strength. However, most quasi-solid electrolytes prepared by immobilizing ionic liquid (IL) or organic liquid electrolyte in inorganic scaffold generally have poor interface compatibility and low lithium ion migration number, which limits its application. Herein, we design and prepare a ZIF-8-based QSSE (ZIF-8 QSSE) in which the ZIF-8 has a special cage structure and interaction with the guest electrolyte to form a composite electrolyte with good ionic conductivity about 1.05 x 10(-4) S cm(-1) and a higher lithium-ion transference number of about 0.52. With the ZIF-8 QSSE, a protype lithium battery coupled with LiCoO2 cathode shows good electrochemical performances with an initial discharge capacity of 135 mAh g(-1) at 50 mA g(-1) and a remaining capacity of 119 mAh g(-1) after 100 cycles, only 0.119% capacity degradation per cycle. It is worth noting that the ZIF-8-based QSSEs have good thermal stability up to 350 degrees C that does not show thermal runaway, which is significantly higher than that of a conventional organic liquid battery system.
Oxygen-Sensitive Layered MoTe2 Channels for Environmental Detection
(2019-12-18)
Yang, Shih-Hsien
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Lin, Che-Yi
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Chang, Yuan-Ming
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Li, Mengjiao
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Lee, Ko-Chun
The oxygen (O-2)-dependent resistance change of multilayered molybdenum ditelluride (MoTe2) channels was characterized. A variation of the channel resistance could reproducibly determine relative O-2 content (denoted as the O-2 index). We found that Joule heating in a layered MoTe2 field-effect transistor caused the O-2 index to decrease drastically from 100 to 12.1% in back gate modulation. Furthermore, Joule heating caused effective O-2 desorption from the MoTe2 surface and repeatable O-2 detection by multilayered MoTe2 channels was realized. This work not only explored the influence of O-2 on the electrical properties of multilayered MoTe2 channels but also revealed that MoTe2 channels are promising for sensing O-2 in an environmental condition.
Tautomer Structures in Ketose-Aldose Transformation of 1,3-Dihydroxyacetone Studied by Infrared Electroabsorption Spectroscopy
(2019-12-19)
Chen, Szu-Hua
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Hiramatsu, Hirotsugu
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交大名義發表
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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 acyclic form of monosaccharides exists in a structural equilibrium, with aldose having the aldehyde group and ketose the ketone group (ketose-aldose equilibrium). A basic catalyst facilitates their transformation, which affects the chemical properties of the monosaccharide. In this study, we investigated the ketose-aldose transformation of 1,3-dihydroxyacetone (1,3-DHA), one of the simplest systems of the ketose-aldose equilibrium. We examined the effects of piperidine as the basic catalyst and used IR electroabsorption spectroscopy to study the responses to an external electric field. We analyzed the changes in IR absorption by considering the changes in the molecular orientation and number of molecules in response to the external electric field. The results of the analysis revealed the permanent dipole moment mu(P), an angle eta between mu(P) and mu(T) (the transition moment of the molecular vibration), and the equilibrium constants. The ketose-aldose transformation of 1,3-DHA can be explained in terms of the equilibrium of three states. In the presence of piperidine, a five-state equilibrium was concluded. On the basis of the experimental data, we propose plausible models of dihydroxyacetone, E-enediols, Z-enediol, or glyceraldehyde for each state. The results of our structural analysis of these tautomers provide a detailed understanding of the ketose-aldose transformation of acyclic saccharides and the effects of the basic catalyst.
Influences of Contact Metals on the Performances of MoS2 Devices under Strains
(2019-12-19)
Tseng, Sian-Hong
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Chen, Hung-Yi
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Hsu, Wei-Ting
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Wang, Hsiang-Chen
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Li, Yuan-Yao
The growth of large-area MoS2 films was achieved through atmospheric pressure chemical vapor deposition via vapor management in this study. The thickness of the MoS2 film changed upon varying the amount of vapor deposited on the substrate. Gratifyingly, large-area monolayer MoS2 was obtained under controlled conditions. Studies using transmission electron microscopy and second harmonic generation confirmed that the MoS2 films were composed of grains having sizes ranging from 40 to 70 mu m. Flexible MoS2 device arrays were fabricated on a polyimide substrate; the device arrays displayed high spatial uniformity in their carrier transport properties. The contact metals affected the electrical characteristics of the MoS2 devices under strain; the sensitivity of devices featuring Schottky contacts was higher than that of those with ohmic contacts. Importantly, the device arrays exhibit sensitive and endurance performances under strain cycles of up to 10(5) times. These results suggest a means for the feasible growth of large-area single-layer MoS2 films, as well as the exploitation of flexible MoS2 device arrays in strain and human motion sensor applications.
Evaluating failure mechanisms of dip slope using a multiscale investigation and discrete element modelling
(2019-12-20)
Weng, Meng-Chia
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Lin, Ming-Lang
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Lo, Chia-Ming
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Lin, Hsi-Hung
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Lin, Cheng-Han
This study proposed an in-depth multiscale analysis procedure to identify the dip slope area and assess dip slope stability and influencing area. The proposed analysis procedure comprised five stages: (1) identifying the potential area of a dip slope, (2) analyzing the possible failure types of the dip slope, (3) evaluating slope activity, (4) analyzing dip slope stability under the influence of possible triggering factors, and (5) assessment of the deformation and deposition area. To validate the proposed procedure, the Chaochouhu region of Taiwan was analyzed as a dip slope case. In stages (1) to (3), the scale of the utilized map and the precision of associated data were evaluated to identify the potential area of a dip slope, the possible failure types, and the activity of each slope unit. In stages (4) and (5), the processes of deformation and sliding in a high-activity slope unit were simulated using the discrete element method. The numerical model was first verified using in-situ monitoring data obtained from inclinometers. Subsequently, the model was used to predict the slope behavior under conditions of wetting deterioration of geomaterial. The multiscale analysis revealed comprehensive information regarding the dip slope. The application of the proposed approach would be useful to civil engineers for evaluating dip slope stability as well as to relevant authorities for planning hazard mitigation strategies.
Data-driven hybrid multiple attribute decision-making model for green supplier evaluation and performance improvement
(2019-12-20)
Liou, James J. H.
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Chuang, Yen-Ching
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Zavadskas, Edmundas Kazimieras
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Tzeng, Gwo-Hshiung
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科技管理研究所
Multi-attribute decision-making (MADM) is the most commonly used methodology for green supplier evaluation and performance improvement. Previous MADM models have mainly relied upon the knowledge and opinions of domain-experts as the starting point for making decisions. However, the results are affected by the subjectivity of these judgments and knowledge limitations. This study develops a data-driven MADM model that utilizes potential rules/patterns derived from a large amount of historical data to help decision-makers objectively select suitable green suppliers and provide systemic improvement strategies to help reach the aspiration level. First, the random forest (RF) algorithm is applied to explore the pairwise influential strength relations among attributes derived from real audit data. The influence matrix derived using the RF algorithm is used as input for decision-making trial and evaluation laboratory (DEMATEL)-based analytical network process analysis which is carried out to obtain the influential strength weights of the attributes. Then, multi-objective optimization on the basis of ratio analysis to the aspiration level (MOORA-AS) is utilized to evaluate the gap between the current and aspiration levels for each green supplier. The developed critical influence strength route (CISR) can help managers derive various strategies for improving green supplier performance. The functioning of the proposed model is illustrated using data obtained from the green supplier management department of a Taiwanese electronics company. The results reveal that the proposed model can effectively help decision-makers to solve the problem of green supplier selection and devise strategies for improvement. (C) 2019 Elsevier Ltd. All rights reserved.
Hydrogen-atom tunneling reactions with methyl formate in solid para-hydrogen: Infrared spectra of the methoxy carbonyl [center dot C(O)OCH3] and formyloxy methyl [HC(O)OCH2 center dot] radicals
(2019-12-21)
Haupa, Karolina A.
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Strom, Aaron I.
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Anderson, David T.
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Lee, Yuan-Pern
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交大名義發表
We investigated the reaction of methyl formate, HC(O)OCH3, with hydrogen atoms in solid para-hydrogen (p-H-2) at 1.74 and 3.3 K with infrared absorption spectroscopy. Hydrogen atoms were produced either upon direct photolysis of HC(O)OCH3 at 193 nm or upon irradiation of Cl-2, codeposited with HC(O)OCH3 in p-H-2, with light at 365 nm to produce Cl atoms that react with the p-H-2 host via the reaction Cl + H-2 (v = 1) -> HCl + H induced by subsequent IR irradiation of the p-H-2 matrix. We assigned lines at 1785.2, 1170.6, 1104.6, and 879.4/880.5 cm -1 and five additional weak lines to the methoxy carbonyl radical, center dot C(O)OCH3, and three weak lines at 1751.3, 1152.9, and 994.4/996.8 cm(-1) to the formyloxy methyl radical, HC(O)OCH2 center dot, according to the consideration of possible reactions, correlated variations in intensities after each experimental step, and comparison of observed vibrational wavenumbers and IR intensities with values predicted with the B3LYP/aug-cc-pVTZ method. Unlike most reported H-atom diffusion tunneling reactions, the reaction H + HC(O)OCH3, in solid p-H-2 at 3.3 K was found to diminish rapidly after IR irradiation, but, similar to reactions of H + N2O and H + HC(O)OH, this reaction was reinitiated when the matrix temperature was decreased from 4.0 K to 1.5 K. We confirmed that the method used to generate the mobile H atoms does not affect the subsequent chemistry. A possible reaction mechanism and the role of this reaction in dark interstellar clouds are discussed. Published under license by AIP Publishing.
Electronic and vibrational structure in the S-0 and S-1 states of corannulene
(2019-12-21)
Kanaoka, Ayumi
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Tohyama, Hiromi
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Kunishige, Sachi
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Katori, Toshiharu
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Nishiyama, Akiko
Corannulene is a nonplanar aromatic hydrocarbon also known as a buckybowl. Its electronic and vibrational structure has been investigated by analyzing its fluorescence excitation spectrum and dispersed fluorescence spectrum in a supersonic jet. Its spectral features are in keeping with the expectation, confirmed by some previous results, that it has fivefold or C-5 nu, symmetry. The observed prominent vibronic bands in the S-1 <- S-0 transition have been assigned to e(1) and e(2) bands on the basis of theoretical calculations so that the S-1 state was assigned to E-1(2). The symmetry adapted cluster configuration interaction calculation supports this assignment of the S, electronic state, although the time-dependent density functional theory calculation suggests that the S-1 state is (1)A(2). It has also been shown that the normal coordinates for strong vibronic bands mainly include out-of-plane vibrational motion. The rotational envelopes are well explained by taking account of the Coriolis interaction between the degenerate vibrational and rotational levels. The mechanism of bowl-to-bowl inversion is also discussed with the results of theoretical calculations regarding the barrier to inversion and metastable conformation. Published under license by AIP Publishing.
台灣同志家庭想好孕？一窺《人工生殖法》的困境
(2019-12-22)
蕭蕙崎
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Department of Communication and Technology
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傳播與科技學系
【同婚過後好孕到？台灣同志家庭的生育困境】專題

同婚過後為什麼同志伴侶們還是需要耗費許多金錢與心力到國外，進行人工生殖手術呢？送子鳥要何時才能順利將孩子送到同志的家庭呢？透過圖表讓你了解在台灣同志家庭生育的現況與困境。
總編輯的話
(2019-12-22)
李芝謙
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Department of Communication and Technology
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傳播與科技學系
本期為喀報329期，共計六篇文章，包含四篇文化現象，一篇社會議題，一篇人物特寫。本期頭題為石恩亞的〈藝術是一種自由－塗鴉師吳衞仁〉，一位投身公益以及藝術的熱血少年的故事。此外，還有許多時下社會的焦點議題討論，以及傳統文化現象探討。以兼具社會關懷及客觀的角度，報導多元且貼近生活的題材。
藝術是一種自由－塗鴉師吳衞仁
(2019-12-22)
石恩亞
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Department of Communication and Technology
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傳播與科技學系
藝術是什麼？對吳衞仁來說，藝術沒有答案，更不該有框架。
全台玩透透體驗經濟哪裡有？
(2019-12-22)
王會瑄
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Department of Communication and Technology
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傳播與科技學系
【滑世代的體驗經濟】專題

身為「滑世代」的一員，你是否厭倦了日復一日活在電子虛擬世界的生活？本篇指南將帶著你跨出家門，一探全台有哪些有趣的體驗活動。
21世紀的新型鴉片　你知多少？
(2019-12-22)
李金福
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Department of Communication and Technology
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傳播與科技學系
「電子鴉片抬頭不見低頭見」專題

你知道全世界，人們每日平均吸食電子鴉片是多長時間嗎？你知道多數人吸的電子鴉片是什麼類別嗎？本篇將用數據帶你一窺電子鴉片身後不為人知的秘密！
一起逛市場！　東門市場的重生
(2019-12-22)
黃心姵
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Department of Communication and Technology
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傳播與科技學系
【傳統市場的重生　一起逛市場！】專題

幾年前的東門市場因為沒落，環境陰暗，連當地人也不太願意進入。近幾年，在新竹市政府與國立清華大學合力推動「東門青年基地」下，年輕人與創新的元素進入東門市場，為市場帶來活化的可能。
保育動物與我何干？不是只有愛動物那麼簡單！
(2019-12-22)
李旻珊
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Department of Communication and Technology
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傳播與科技學系
【不是只有愛動物那麼簡單！保育知識面面觀】專題

每次人為開發下的犧牲，其實都深深影響著大自然的平衡與脈動，也是野生動物需要保育的實際理由。野生動物路死觀察與傷病救援，更是值得關注與學習的課題。
Path-based MAXBAND with green-split variables and traffic dispersion
(2019-12-23)
Cho, H-J
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Huang, T-J
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Huang, C-C L.
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
In this paper, we propose two path-based MAXBAND models for solving signal synchronization problems for coordinated traffic signalization systems. In the first proposed model (RM1), we relax the assumptions that the lengths of the common cycle, as well as the green splits, are fixed in the base path-based MAXBAND model. These two factors are considered as decision variables in RM1, which leads us to a generalized offset optimization problem. In the second model (RM2), we further relax the free-flow speed assumption used for estimating the link travel times in the coordinated system. Since the free-flow speed can only be reached in rare occasions, we, instead, adopt the Robertson's dispersion module for this purpose. Proposed methodologies are applied to solving a real-world application in that a pure-traffic arterial system in Chubei city, Taiwan, is analyzed for performance evaluations. Numerical results suggest significant improvements from the proposed models, compared to plans suggested by the governmental authority and the literature. From path-wise perspective, model RM1 and RM2 are nip-and-tuck alternatives. From an aggregate perspective, model RM2 has the best performance among all alternatives, with overall improvements around .
SnCl4-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives
(2019-12-23)
Asressu, Kesatebrhan Haile
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Wang, Cheng-Chung
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應用化學系
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Department of Applied Chemistry
Sialic acid-containing glycans are found in different sialic acid forms and a variety of glycosidic linkages in biologically active glycoconjugates. Hence, the preparation of suitably protected sialyl building blocks requires high attention in order to access glycans in a pure form. In line with this, various C-5-substituted 2,7-anhydrosialic acid derivatives bearing both electron-donating and -withdrawing protecting groups were synthesized and subjected to different Lewis acid-catalyzed solvent-free ring-opening reactions at room temperature in the presence of acetic anhydride. Among the various Lewis acids tested, the desired acetolysis products were obtained in moderate yields under tin(IV) chloride catalysis. Our methodology could be extended to regioselective protecting group installations and manipulations towards a number of thiosialoside and halide donors.
Thermal Management of GaN-on-Si High Electron Mobility Transistor by Copper Filled Micro-Trench Structure
(2019-12-23)
Mohanty, Srikant Kumar
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Chen, Yu-Yan
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Yeh, Ping-Hung
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Horng, Ray-Hua
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交大名義發表
Self-heating effect is a major limitation in achieving the full performance potential of high power GaN power devices. In this work, we reported a micro-trench structure fabricated on the silicon substrate of an AlGaN/GaN high electron mobility transistor (HEMT) via deep reactive ion etching, which was subsequently filled with high thermal conductive material, copper using the electroplating process. From the current-voltage characteristics, the saturation drain current was improved by approximately 17% with the copper filled micro-trench structure due to efficient heat dissipation. The I-DS difference between the pulse and DC bias measurement was about 21% at high bias V-DS due to the self-heating effect. In contrast, the difference was reduced to approximately 8% for the devices with the implementation of the proposed structure. Using Micro-Raman thermometry, we showed that temperature near the drain edge of the channel can be lowered by approximately similar to 22 degrees C in a HEMT operating at similar to 10.6 Wmm(-1) after the implementation of the trench structure. An effective method for the improvement of thermal management to enhance the performance of GaN-on-Silicon HEMTs was demonstrated.
From symmetry to entropy: Crystal entropy difference strongly affects early stage phase transformation
(2019-12-23)
Hu, C. H.
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Chen, Y. C.
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Yu, P. J.
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Fung, K. Y.
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Hsueh, Y. C.
Although the connection between symmetry and entropy is not clear, researchers calculate configurational entropy with an ideal gas mixing model all along regardless of which structure they are considering. However, it is obvious that crystalline structures have symmetry, while an ideal gas does not. Therefore, the same ideal gas mixing value should not be assigned to other structures, such as face-centered-cubic (fcc) and hexagonal-close-packed (hcp) structures. Here, we offer a precise definition for determining the configurational entropy of crystals. We calculate the difference in configurational entropy between fcc and hcp structures based on Burnside's lemma in combinatorial mathematics and crystallographic rotation-point groups.