Browsing by Issue Date, starting with "2019-05-02"

Now showing 1 - 20 of 7657

A Hollow Microtubular Triazine- and Benzobisoxazole-Based Covalent Organic Framework Presenting Sponge-Like Shells That Functions as a High-Performance Supercapacitor
(2019-05-02)
El-Mahdy, Ahmed F. M.
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Hung, Ying-Hui
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Mansoure, Tharwat Hassan
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Yu, Hsiao-Hua
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Chen, Tao
In this paper we report the construction of a hollow microtubular triazine- and benzobisoxazole-based covalent organic framework (COF) presenting a sponge-like shell through a template-free [3+2] condensation of the planar molecules 2,4,6-tris(4-formylphenyl)triazine (TPT-3CHO) and 2,5-diaminohydroquinone dihydrochloride (DAHQ-2HCl). The synthesized COF exhibited extremely high crystallinity, a high surface area (ca. 1855m(2)g(-1)), and ultrahigh thermal stability. Interestingly, a time-dependent study of the formation of the hollow microtubular COF having a sponge-like shell revealed a transformation from initial ribbon-like crystallites into a hollow tubular structure, and confirmed that the hollow nature of the synthesized COF was controlled by inside-out Ostwald ripening, while the non-interaction of the crystallites on the outer surface was responsible for the sponge-like surface of the tubules. This COF exhibited significant supercapacitor performance: a high specific capacitance of 256Fg(-1) at a current density of 0.5Ag(-1), excellent cycling stability (98.8% capacitance retention over 1850cycles), and a high energy density of 43Whkg(-1). Such hollow structural COFs with sponge-like shells appear to have great potential for use as high-performance supercapacitors in energy storage applications.
Probing Defect States in Organic Polymers and Bulk Heterojunctions Using Surface Photovoltage Spectroscopy
(2019-05-02)
Murthy, Lakshmi N. S.
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Barrera, Diego
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Xu, Liang
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Gadh, Aakash
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Cao, Fong-Yi
We performed frequency-modulated (AC) and steady-state (DC) surface photovoltage spectroscopy (SPS) measurements on a bilayer structure consisting of an organic semiconductor (P3HT, P3HT:PC61BM, or PFBT2Se2Th:PC71BM) on top of a ZnO electron-transport layer. The AC spectra overlap with the absorption spectra of the organic layer, providing evidence that AC SPS corresponds to band-to-band transitions. The DC spectra are generally broader than the AC spectra, with responses extended below the absorption edge. Thus, DC SPS also probes transitions between band states and trap states within the band gap in addition to band-to-band transitions. When a hole-transport layer (HTL) is deposited on top of the organic layer, the DC spectra of P3HT and P3HT:PC61BM are narrower than those without the HTL, suggesting that the sub-band gap states exist at the surface of these organic semiconductors. In contrast, PFBT2Se2Th:PC71BM does not show signature of surface states or optically active trap states in the band gap. External quantum efficiency and capacitance measurements are employed to explain the nature of sub-band gap states that contribute to surface photovoltage signals and the differences between the two bulk heterojunction systems.
Tunable disorder and localization in the rare-earth nickelates
(2019-05-02)
Wang, Changan
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Chang, Ching-Hao
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Huang, Angus
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Wang, Pei-Chun
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Wu, Ping-Chun
We demonstrate that transport in metallic rare-earth nickelates can be engineered by directly tuning the electronic mean free path. Using irradiation as a tool to induce disorder, we drive this system from a metallic phase into an Anderson insulator. This proceeds via an intermediate regime which shows a thermal crossover from insulating to metallic behavior. We argue that this phase falls within the paradigm of weak localization in three dimensions. We develop a theoretical model for the temperature dependence of resistivity which shows good agreement with our data. The three-dimensional weak localization picture is supported by magnetoconductivity, which scales as similar to B-2 up to several tesla. Interestingly, our data indicate that this phase lies in the Mott-Ioffe-Regel regime with the mean free path approaching the lattice constant. Upon further increasing disorder, the charge carriers are localized, leading to insulating behavior at all temperatures. Our results show that irradiation provides a "clean" tuning knob for the mean free path, without altering other system parameters. This suggests promising directions for studies of Anderson localization.
Dynamics of the Vortex-Particle Complexes Bound to the Free Surface of Superfluid Helium
(2019-05-03)
Moroshkin, P.
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Leiderer, P.
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Kono, K.
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Inui, S.
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Tsubota, M.
We present an experimental and theoretical study of the 2D dynamics of electrically charged nanoparticles trapped under a free surface of superfluid helium in a static vertical electric field. We focus on the dynamics of particles driven by the interaction with quantized vortices terminating at the free surface. We identify two types of particle trajectories and the associated vortex structures: vertical linear vortices pinned at the bottom of the container and half-ring vortices traveling along the free surface of the liquid.
Metal-Guided Selective Growth of 2D Materials: Demonstration of a Bottom-Up CMOS Inverter
(2019-05-03)
Chiu, Ming-Hui
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Tang, Hao-Ling
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Tseng, Chien-Chih
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Han, Yimo
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Aljarb, Areej
2D transition metal dichalcogenide (TMD) layered materials are promising for future electronic and optoelectronic applications. The realization of large-area electronics and circuits strongly relies on wafer-scale, selective growth of quality 2D TMDs. Here, a scalable method, namely, metal-guided selective growth (MGSG), is reported. The success of control over the transition-metal-precursor vapor pressure, the first concurrent growth of two dissimilar monolayer TMDs, is demonstrated in conjunction with lateral or vertical TMD heterojunctions at precisely desired locations over the entire wafer in a single chemical vapor deposition (VCD) process. Owing to the location selectivity, MGSG allows the growth of p- and n-type TMDs with spatial homogeneity and uniform electrical performance for circuit applications. As a demonstration, the first bottom-up complementary metaloxide-semiconductor inverter based on p-type WSe2 and n-type MoSe2 is achieved, which exhibits a high and reproducible voltage gain of 23 with little dependence on position.
Unique amorphization-mediated growth to form heterostructured silicide nanowires by solid-state reactions
(2019-05-05)
Lin, Wan-Jhen
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Lin, Ting-Yi
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Huang, Chun-Wei
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Ting, Yi-Hsin
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Tsai, Tsung-Chun
Transition metal silicide nanowires exhibit low resistivity, great thermal stability and excellent mechanical strength, contributing to their applications as interconnection and contact materials for future integrated circuits devices. In this work, we successfully fabricated two kinds of chromium silicide/silicon heterostructure nanowires through solid state reactions - bare Si/Cr3Si nanowires and Si/Cr5Si3-Al2O3 core-shell nanowires. The growth behaviors and diffusion mechanisms of the two silicide heterostructure nanowires were investigated with in-situ TEM at 700 degrees C. During the growth of chromium silicide nanowires, unique amorphous Si phase would form first in front of silicide nanowires. Also, we found that oxide-shell could control the diffusion process in silicon nanowires. With oxide-shell, compression stress would restrain the growth of chromium silicide in the radial direction but accelerate its growth rate in the axial direction. Additionally, Al2O3 shell reduced the radial expansion of chromium silicide nanowires and hindered Cr-rich phases with Cr5Si3 appearing as the first phase. The crystal structures of the nanowires have been identified to be single-crystalline A15 and D8m type structure of the intrinsic Cr3Si nanowires and Cr5Si3 nanowires, respectively. In addition to fundamental science, the significant study is beneficial for future processing techniques in nanotechnology and related applications. (C) 2019 Elsevier Ltd.
那些年偶像劇的主演們去哪了？
(2019-05-05)
陳盈璇
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Department of Communication and Technology
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傳播與科技學系
【演員的挑戰】專題

那些年很紅的偶像劇主演們現在怎麼樣了呢？隨著時間的推移、時代的轉變，他們的演員生涯、演技風格是否有所改變呢？
媒體診療室：猝不及防的媒體病
(2019-05-05)
呂奕廷
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彭姿敏
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林函諭
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蔡佳妤
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Department of Communication and Technology
近期爆發許多關於新聞媒體的議題，像是：
✤台灣大學與政治大學聯合抵制學生餐廳播放中天新聞
✤還有好多假新聞、網友酸民議題天天都在發生......
✤公投引起的網路世代「同溫層」議題
因此，讓更多⼈意識到媒體素質與閱聽⼈素養的重要性，就在今日資訊真假難辨的社會中顯得非常重要。
《青春有你》　有版權卻不火
(2019-05-05)
黃齡萱
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Department of Communication and Technology
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傳播與科技學系
【陸綜火什麼？綜藝熱潮與現象大解析】專題

2018年大陸移植韓國《Produce101》，以仿冒形式推出《偶像練習生》，即使有版權爭議，卻紅透半邊天。2019年推出第二季，以有版權名義強勢回歸，觀眾卻不像之前一樣買單，是什麼原因呢？
衣櫃永遠少一件？認識快時尚
(2019-05-05)
林芷懷
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Department of Communication and Technology
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傳播與科技學系
【極簡生活修練題】專題

老是覺得衣櫃少了一件衣服嗎？滿坑滿谷的上衣、褲子、外套，卻還是不知道要穿什麼，似乎是不少現代人的困擾。本文將以圖解的方式，談談你或許不太了解、卻已經深陷其中的「快時尚」現象。
「發現」茶的不一樣
(2019-05-05)
許家芸
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Department of Communication and Technology
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傳播與科技學系
【大家一起來找茶！】專題

發現茶團隊他們挑戰的不是茶葉技術的開發，而是下一代人喝茶的價值觀。
享受單身　探索單身女性商機
(2019-05-05)
王允姸
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Department of Communication and Technology
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傳播與科技學系
【單身化社會：單身女性何去何從】專題

隨著單身潮襲來、單身女性增多，本篇探討單身女性帶來多面向的單身商機！
電燈泡的陰謀　計畫性汰舊背後
(2019-05-05)
梁書瑜
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Department of Communication and Technology
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傳播與科技學系
【垃圾消失了？循環經濟大解密】專題

你是否有過身邊的東西用沒兩三年就故障的經驗呢？當維修人員告訴你維修費是新品價格的一半，這時你會怎麼做？堅持送修還是乾脆買一個新的呢？
Linear elliptic equations in composite media with anisotropic fibres
(2019-05-05)
Yeh, Li-Ming
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應用數學系
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Department of Applied Mathematics
Linear elliptic equations in composite media with anisotropic fibres are concerned. The media consist of a periodic set of anisotropic fibres with low conductivity, included in a connected matrix with high conductivity. Inside the anisotropic fibres, the conductivity in the longitudinal direction is relatively high compared with that in the transverse directions. The coefficients of the elliptic equations depend on the conductivity. This work is to derive the Holder and the gradient L-P estimates (uniformly in the period size of the set of anisotropic fibres as well as in the conductivity ratio of the fibres in the transverse directions to the connected matrix) for the solutions of the elliptic equations. Furthermore, it is shown that, inside the fibres, the solutions have higher regularity along the fibres than in the transverse directions. (C) 2019 Elsevier Inc. All rights reserved.
老屋概論
(2019-05-05)
吳佳璘
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Department of Communication and Technology
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傳播與科技學系
台灣的老房子多，連帶地產生不少潛在的隱憂、市容的景觀的不美觀為什麼不能大刀闊斧的完成都市更新呢？
關於同溫層　我們都是始作俑者
(2019-05-05)
蔡佳妤
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彭姿敏
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Department of Communication and Technology
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傳播與科技學系
2018年公投後「同溫層」成為熱搜話題，同溫層的形成與演算法之間的關聯是眾所皆知的，不過，除了社群媒體的演算法，閱聽人的認知形式也是造成同溫層的一大因素。本篇圖表將帶大家從「社群軟體」與「閱聽人」兩個不同的面向剖析同溫層的發生。
負評刷起來！網友跟風跟誰瘋
(2019-05-05)
呂奕廷
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林函諭
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Department of Communication and Technology
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傳播與科技學系
【媒體診療室：猝不及防的媒體病】專題

在網路開始盛行之後，各種因其而衍生出的事件如雨後春筍般冒出，跟風事件便是其中之一。然而跟風所引起的負面新聞不在少數，究竟跟風的背後，有什麼東西值得我們去探索的呢？
一個假新聞　大學生各自表述
(2019-05-05)
林函諭
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呂奕廷
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蔡佳妤
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彭姿敏
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Department of Communication and Technology
【媒體診療室：猝不及防的媒體病】專題

近年來假新聞在網路上漸漸猖獗，閱聽人在面對這些假新聞也較為麻木，甚至不去查證，而是一味地接受。最近學生發起抵制中天新聞在餐廳播放的連署事件，也讓學生們開始意識到選擇新聞台的權力，以及求證新聞內容的重要性。
總編輯的話
(2019-05-05)
蘇嘉薇
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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313期，稿件共計12篇。本期專題為「媒體診療室：猝不及防的媒體病」，透過多媒材的運用與多面向的討論，帶領讀者更加認識這世代媒體亂象。
無人機小教室　帶你認識小知識
(2019-05-05)
程安瑜
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Department of Communication and Technology
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傳播與科技學系
【俯瞰新視界：無人飛行機】專題

現在人人都有可能擁有自己的空拍機，但你知道空拍機其實只是無人機的其中一種嗎？讓無人機小教室帶你認識更多有關無人機的小知識！