Browsing by Issue Date, starting with "2020-01-08"

Now showing 1 - 20 of 5791

n-Type Thin-Film Transistors Based on Diketopyrrolopyrrole Derivatives: Role of Siloxane Side Chains and Electron-Withdrawing Substituents
(2020-01-08)
Prakoso, Suhendro Purbo
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Kumar, Sushil
;
Wu, San-Lien
;
Ciou, Guan-Ting
;
Ke, Yao-Jin
The physical properties, packing, morphology, and semiconducting performance of a planar pi-conjugated system can be effectively modified by introducing side chains and substituent groups, both of which can be complementary to the pi framework in changing the intermolecular association, frontier molecular orbital energy, optical band gap, and others. We herein show that installation of end-capped electron-withdrawing groups (EWGs), such as dicyanovinyl (-DCV), 3-ethylrhodanine (-RD), and 2-(3-oxo-indan-1-ylidene)-malononitrile (-INCN), together with siloxane side chains to the backbones of dithienyldiketopyrrolopyrrole (DPPT), such as DPPT-Si-DCV, DPPT-Si-RD, and DPPT-Si-INCN, can greatly improve its solubility, air stability, and film morphology to serve as an n-channel in thin-film transistor fabrication. The EWGs attached to the DPPT core narrowed the optical band gap (E-g(opt)) and changed the highest occupied molecular orbital and the lowest unoccupied molecular orbital energies (E-HOMO and E-LUMO), making them suitable for n-channel field-effect transistor (FET) applications. The benefits of introducing siloxane side chains to the DPPT core include enhanced solubility, low crystallization barrier, enantiotropic phase behavior, and much improved FET performance. The DPPT-Si-INCN film displayed low-lying HOMO (-5.82 eV) and LUMO (-4.60 eV) energy levels and an optical band gap as low as 1.22 eV, all of which suggest that this derivative can be quite resistant toward aerial oxidation. Thin films of these derivatives were prepared by the solution-shear method. A comparison of the solution-sheared films indicated that the molecular packing motif of DPPT-Si-INCN film was somehow different from that of DPPT-Si-DCV and DPPT-Si-RD, in which the pi-pi stacking tended to align orthogonally to the shearing direction. This specific pi-pi stacking alignment could have an impact on the electron mobility (mu(e)) values in transistors based on the solution-sheared films.
High Power Na3V2(PO4)(3)@C/AC Bi-material Cathodes for Hybrid Battery-Capacitor Energy Storage Devices
(2020-01-08)
Akhtar, Mainul
;
Chang, Jeng-Kuei
;
Majumder, S. B.
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We have reported the synthesis and electrochemical characteristics of carbon-coated sodium vanadium phosphate/activated carbon (NVP@C/AC) bi-material electrodes. We have reported that bi-material type NVP@C/AC cathodes offer superior rate performance as compared to either NVP@C or AC electrodes. Through a detailed impedance spectroscopy analyses, we demonstrated that the synergic effect observed in the bi-material electrodes correlates well with the lowering of their charge transfer resistances (R-CT) and the increase of Li(+)diffusion coefficient (DLi+) with the increase of activated carbon content from 0 to 0.60 weight fraction. Through a detailed cyclic voltammogram analyses we have delineated the faradaic and capacitive contribution towards the overall capacities of the bi-material electrodes at various rate conditions. For both these bi-materials, irrespective of the AC content and rate, capacitive contribution dominates the overall capacity. NVP@C/AC40 yields discharge capacities of 67 and 40 mAh g(-1)with capacity retention of more than 93% and 67% after 500 cycles measured at 50 and 1000 mA g(-1), respectively. These bi-materials are demonstrated to be excellent material candidates for high power density lithium titanium oxide (LTO)//NVP@C/AC hybrid battery-capacitor (bat-cap) energy storage devices.
miRTarBase 2020: updates to the experimentally validated microRNA-target interaction database
(2020-01-08)
Huang, Hsi-Yuan
;
Lin, Yang-Chi-Dung
;
Li, Jing
;
Huang, Kai-Yao
;
Shrestha, Sirjana
MicroRNAs (miRNAs) are small non-coding RNAs (typically consisting of 18-25 nucleotides) that negatively control expression of target genes at the post-transcriptional level. Owing to the biological significance of miRNAs, miRTarBase was developed to provide comprehensive information on experimentally validated miRNA-target interactions (MTIs). To date, the database has accumulated >13,404 validated MTIs from 11,021 articles from manual curations. In this update, a text-mining system was incorporated to enhance the recognition of MTI-related articles by adopting a scoring system. In addition, a variety of biological databases were integrated to provide information on the regulatory network of miRNAs and its expression in blood. Not only targets of miRNAs but also regulators of miRNAs are provided to users for investigating the up- and downstream regulations of miRNAs. Moreover, the number of MTIs with high-throughput experimental evidence increased remarkably (validated by CLIP-seq technology). In conclusion, these improvements promote the miRTarBase as one of the most comprehensively annotated and experimentally validated miRNA-target interaction databases.
Investigation of the forming process under UV illumination in HfO2-based resistance random access memory with a transparent electrode
(2020-01-09)
Huang, Wei-Chen
;
Huang, Shin-Ping
;
Chen, Po-Hsun
;
Chen, Min-Chen
;
Chang, Ting-Chang
Traditionally, metal is used for the top electrode (TE) in HfO2-based resistance random access memory. When transparent indium-tin-oxide (ITO) is used as the TE, different forming processes, including lower forming voltages and higher forming currents, are exhibited. This work investigates the forming process with such a transparent TE under UV illumination. In addition, different TE thicknesses and device cell sizes are also investigated to confirm the results. Finally, a possible conduction model is provided to explain the mechanisms under UV-light illumination for the transparent TE during the forming process.
Automatic cloud service testing and bottleneck detection system with scaling recommendation
(2020-01-10)
Liu, Xiaolong
;
Sheu, Ruey-Kai
;
Lo, Win-Tsung
;
Yuan, Shyan-Ming
;
資訊工程學系
Performance problems in a cloud service are difficult to diagnose because they may be caused by various system components. This study proposes an automatic cloud service testing and bottleneck detection system that is applicable to different types of services. With the proposed test module, the user can customize test scenarios to automatically test and collect the corresponding metrics of the target service. Afterward, the proposed bottleneck detection algorithm analyzes the collected metrics and determines whether a bottleneck is presented in the target system. The bottleneck detection module also provides a scaling recommendation for the service provider to facilitate the service system reconfiguration. The experimental results reveal that the proposed system could detect a potential bottleneck in a service system accurately. In accordance with the scaling recommendation, the performance of the target cloud service can be improved efficiently after reconfiguration. Therefore, usage of the proposed system can ensure a high quality of service, and the service level objective could be fulfilled.
Protein Crosslinking and Immobilization in 3D Microfluidics through Multiphoton Absorption
(2020-01-12)
Lin, Chen-Feng
;
Su, Che-Fu
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Lin, Kung-Hsuan
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Hsieh, Yu-Shen
;
Cheng, Yun-Chien
This study used laser multiphoton absorption (MPA) to crosslink and immobilize protein in 3D microfluidics. MPA can be used to crosslink proteins to form smaller crosslinked-protein structures than those formed through single-photon absorption. However, studies on MPA protein crosslinking in 3D microfluidics are lacking. In this study, the MPA was implemented using pulse laser to induce bovine serum albumin (BSA) crosslinking. We also applied (3-glycidyloxypropyl)trimethoxysilane to increase the adhesion of crosslinked BSA. Also, the width of crosslinked-BSA structure was measured, and then curve-fitting and optical equation were used to predict heights of the crosslinked-BSA structures formed under various laser powers. At last, BSA structures were effectively crosslinked in the three-layered glass or polydimethylsiloxane microchannels. In contrast to studies on single-photon absorption in 3D microfluidics or MPA protein crosslinking in 2D microfluidics, we obtained relatively small crosslinked-BSA structures through MPA and immobilize BSA in 3D microfluidics. In the future, this method can be applied in monolithic 3D microfluidics for protein crosslinking to avoid misalignment and leakage in layer-by-layer 3D microchannels and form more compact 3D microfluidics. These features are conducive to enhance the diversity and convenience of microfluidics in biomedical testing.
Rapid and Highly Sensitive Extended Gate FET-Based Sensors for Arsenite Detection Using a Handheld Device
(2020-01-12)
Tatavarthi, Sai Sudheer
;
Wang, Shin-Li
;
Wang, Yu-Lin
;
Chen, Jung-Chih
;
分子醫學與生物工程研究所
Heavy metals are very harmful to the environment and is toxic which affects the human health. Monitoring the heavy metal ion in food and water is necessary. In this research, we developed a FET based ion selective sensor for detecting Arsenite (As(III)) ions by a hand held device. The sensor characteristics are carried out and illustrated. This selective sensor shows higher sensitivity (35.19 mV/log [As3+]) than the ideal Nernstian slope. The dynamic range of the Arsenite based ion sensor is from 10(-10)M to 10(-4)M. The detection limit of this FET based ion selective sensor is below 10(-10)M and is comparable to ICP-MS. The sensor captures the particular target ion and is not affected by the interfering ions such as Cadmium and Lead. The sensitivity and selectivity characteristics are comparatively better than the traditional potentiometric Ion selective electrode (ISE). The sensor has shorter response time and is easy to operate. This sensor is affordable for everyone and convenient to use for monitoring the food and drinking water frequently.
Observation of hydroperoxyethyl formate from the reaction between the methyl Criegee intermediate and formic acid
(2020-01-14)
Cabezas, Carlos
;
Endo, Yasuki
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應用化學系
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Department of Applied Chemistry
Rapid reactions of carboxylic acids with Criegee intermediates provide efficient gas phase removal processes and are proposed to trigger the formation of new molecular compounds, which are implicated in the growth of atmospheric aerosols. The new adducts formed in these reactions are known as hydroperoxide esters and are predicted to be condensable, with lower vapor pressures than the reactants. We report here the direct detection of hydroperoxyethyl formate (HOOCH(CH3)OCHO) formed in the gas phase reaction between the methyl substituted Criegee intermediate, CH3CHOO, and formic acid. Two different isomers of this hydroperoxide ester have been observed using the combination of pulsed Fourier-transform microwave spectroscopy with isotopic substitution experiments and high-level quantum chemical calculations. The identification of hydroperoxyethyl formate as the main nascent product of the CH3CHOO and HCOOH reaction differs from previous results that reported the formation of vinyl hydroperoxide as the reaction product of this reaction.
Amino-functionalization on graphene oxide sheets using an atomic layer amidation technique
(2020-01-14)
Gu, Siyong
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Hsieh, Chien-Te
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Mallick, Bikash Chandra
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Gandomi, Yasser Ashraf
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Chang, Jeng-Kuei
Nitrogen functionalization on graphene sheets has solely been demonstrated with a stepwise amidation implementation within the literature. The present work proposes an atomic layer amidation (ALN) technique to linearly adjust the surface amidation level on the carbon nanostructures. The ALN cycling protocol proposed in this work consists of an ammonia pulse, nitrogen pulse, and pumping at 100 and 150 degrees C. Both surface amidation and oxidation levels were linearly controlled by the ALN cycle number. The ALN technique was demonstrated as a self-limiting process capable of step-by-step N-functionalizing graphene oxide (GO) sheets on the atomic scale. The amidation reaction rates were ca. 0.023 (100 degrees C) and 0.028 atomic percent (at%) cycle(-1) (150 degrees C), and the apparent activation energy was determined to be 14.3 kJ mol(-1) (= 0.148 eV atom(-1)) from the Arrhenius equation. The amidation mechanism for forming the "chemical N" and "lattice N" at an atomic level was also proposed. Linearly controlling the optical band-gap with the ALN cycle number was suggested as a robust method for tuning the oxidation as well as the amidation level on the GO sheets. In this sense, nitrogen functionalization can be utilized for engineering any desirable properties within the graphene sheets.
In situ TEM investigation of electron beam-induced ultrafast chemical lithiation for charging
(2020-01-14)
Huang, Guan-Min
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Huang, Chun-Wei
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Kumar, Nagesh
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Huang, Chih-Yang
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Tseng, Tseung-Yuen
The enhancement of operational life and charging speed have been considered to be two of the major factors that will influence the development of energy storage devices in the future. Here, we utilized an electron beam (e-beam) to retrieve Li metal from LiF, the degradation product of LiPF6, and trigger the further lithiation of NiFe2O4/carbon nanotubes (CNTs) to relieve the degradation of the electrolyte and achieve ultrafast lithiation. Accordingly, in situ transmission electron microscopy (in situ TEM) was used to investigate the comprehensive mechanism of the whole process. The e-beam acting on the degradation product, i.e., LiF clusters, led to the generation of Li flakes, which served as the source for the subsequent lithiation. Then, with these Li flakes, the chemical lithiation of the NiFe2O4/CNTs was triggered, resulting in phase transformation to Ni and Fe nanograins. Compared to "electrochemical" lithiation, ultrahigh reaction speed and the ability to charge without a directly applied potential in the "chemical" lithiation are expected to extend lithiation to more diverse applications. As a result of this investigation, we have provided a new strategy for designing novel energy storage devices for the energy-harvesting field.
金融科技與機器學習：財務文字資料分析
(國立交通大學丘成桐中心, 2020-01-15)
王釧茹
近年來，由於財務相關資料的大量累積，如何有效率地從中發現有用的訊息並用以進行更精準且有效的財務決策，遂成為一個重要的研究議題。這些訊息不僅可協助相關從業人員（如：會計師、分析師）掌握投資機會、最大程度地降低風險或控制成本，更可以運用至各種不同的金融場景。本文介紹文字分析（text mining）及自然語言處理（natural language processing）技術於非結構化財務文字資料上的相關技術及應用。
幾十年懸而未解計算機科學猜想的證明竟只需兩頁：再度窺見上帝的瑰寶
(國立交通大學丘成桐中心, 2020-01-15)
蔻拉萊克
;
林武雄
;
Erica Klarreich
一篇於今年七月線上 1 發表的論文解決一個懸宕將近 30 年有關電路基本組件結構的猜想。「靈敏度」（sensitivity）猜想多年來困惑了許多最傑出的資訊學家，然而新證明卻簡單到一個研究員用一條推文（tweet）就能總結。
中英名詞對照表
(國立交通大學丘成桐中心, 2020-01-15)
編輯室
中英名詞對照
數理簡訊
(國立交通大學丘成桐中心, 2020-01-15)
編輯室
當人工智慧遇見倫理
Anti-interference single-photon LiDAR using stochastic pulse position modulation
(2020-01-15)
Tsai, Chia-Ming
;
Liu, Yung-Chien
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This Letter introduces an anti-interference single-photon light detection and ranging (LiDAR) system with photon-driven stochastic pulse position modulation. A photon arrival sequence with a programmable minimum interval time and trigger rate was proposed to trigger laser pulses, thus providing true nature-based randomness in modulation which is beneficial for achieving bet ter anti-interference capability. In the proposed LiDAR system, two complementary metal-oxide-semiconductor single-photon avalanche diodes (SPADs) are used as an optical receiver and to generate a random trigger pattern of a pulsed laser. To prevent the range ambiguity problem, an interval-time filter capable of controlling the minimum interval time is integrated into the LiDAR system. A trigger rate controller capable of adaptively controlling the driving voltage of a light-emitting diode coupled with the SPAD responsible for the generation of the random trigger sequence is also integrated for achieving a precise control of trigger rate. Finally, a proof-ofconcept demonstration was provided through experiments, and the obtained results were consistent with theoretical predictions. At an effective trigger rate of 800 kHz,, an excellent suppression ratio of 56.2 dB has been achieved in the presence of a 1 MHz periodic interference. (C) 2020 Optical Society of America
數學家想要真正成功，必須被保護：2019 年阿貝爾獎得主烏蘭貝克訪談
(國立交通大學丘成桐中心, 2020-01-15)
烏蘭貝克
;
傑克森
;
翁秉仁
;
Karen Keskulla Uhlenbeck
;
Allyn Jackson
受訪者簡介烏蘭貝克 1942 年生，1966 年在布朗戴斯大學（Brandeis University）取得博士學位，指導教授是帕雷斯（Richard Palais）。先在麻省理工學院和加州大學柏克萊分校做博士後，再分別於伊利諾大學厄巴納 / 香檳分校（1971 ～1976）、伊利諾大學芝加哥分校（1976 ～ 1983）、芝加哥大學（1983 ～ 1988）擔任教職。1988 年起，她擔任德州大學奧斯丁分校的 Sid W. Richardson Foundation 講座教授。如今烏蘭貝克從德大退休，正在普林斯頓高等研究院訪問。過去半世紀，烏蘭貝克是分析學界的卓越領導人物之一，特別在幾何分析有深刻貢獻。令她最知名的可能是數學規範場論的研究，為 20 世紀數學最關鍵的進展之一奠定基礎。基於這項成就，於 2019 年她更獲頒數學界大獎阿貝爾獎。她還曾獲得麥克阿瑟獎（1983）等的多項榮譽與獎項。1990 年，她成為史上第二位在國際數學家大會（InternationalCongress of Mathematicians）做大會演講的女性，之前是 1932 年的諾特（Emmy Noether）。
電腦會有人文藝術的創作能力嗎？：人工智慧與人文藝術創作應用與研究
(國立交通大學丘成桐中心, 2020-01-15)
蘇豐文
人工智慧是一個探討如何利用機器來建構模擬人類智慧與能力的學問。所有人類的智慧行為都是人工智慧所探討的心理認知模型。過去人工智慧的研究從很多基礎的訣竅式搜索法、問題解法與規劃、自動邏輯推理模型、不確定模糊推理模型、知識表示法、情緒計算、常識推理、歸納學習演算法、最佳化演算法、類神經網路與深度學習等，有些甚至從生物與自然界的到靈感如：模擬退火演算法（simulate anneal arithmetic）、基因演算法（genetic algorithm）、群體智慧（swarm intelligence）等。歷史上很多的藝術天才（如莫札特音樂家、達文西美術家、蘇東坡文學家等）具有高人一等的天賦可以產生傳頌不朽的作品。這些能力人工智慧有一天可以達到嗎？
中國算學之過去與現在
(國立交通大學丘成桐中心, 2020-01-15)
陳省身
作者陳省身（Shiing Shen Chern，1911 年10 月28 日～ 2004 年12 月3 日），生於浙江嘉興秀水縣，美籍華裔數學大師，第一屆中央研究院院士，同時是法國科學院、義大利國家科學院、英國皇家學會和中國科學院的外籍院士。他是20 世紀最偉大的幾何學家之一，也是最有影響力的數學家之一。於1982 年在伯克萊大學退休後，建立了美國國家數學科學研究所（MSRI）。1984 年獲頒沃爾夫數學獎，是第一位得到沃爾夫獎的華裔科學獎。國際數學聯盟（IMU）為了紀念陳省身的卓越貢獻，在2014 年還特別設立了陳省身獎（Chern Medal）作為國際數學界最高級別的終身成就獎，這是第一個以華人為名的國際數學重要獎項。近十數年來中國算學的研究有了若干可喜的進步。為檢討過去，策勵將來起見，筆者願把中國算學家幾千年來所做的工作加以歷史的敘述，最後則略敘近年國人進行研究工作的大概情形，俾大家瞭然我們這個時代將在中國算學史上所佔的地位。
編輯曲線
(國立交通大學丘成桐中心, 2020-01-15)
編輯室
本期內容:電腦會有人文藝術的創作能力嗎？
中國的高等教育
(國立交通大學丘成桐中心, 2020-01-15)
丘成桐
作者丘成桐為哈佛大學數學與物理教授，費爾茲獎、克拉福得獎、沃爾夫獎、馬賽爾‧ 格羅斯曼獎得主，中央研究院院士。科普著作有《丘成桐談空間的內在形狀》，並為《數理人文》主編。本文為作者2019年6月11日於北京清華大學第八屆世界華人數學家大會（ICCM2019）公開演講稿。