Browsing by Issue Date, starting with "2019-11-20"

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Engineering radiative coupling of excitons in 2D semiconductors
(2019-11-20)
Horng, Jason
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Chou, Yu-Hsun
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Chang, Tsu-Chi
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Hsu, Chu-Yuan
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Lu, Tien-Chang
The resonance energy and the transition rate of atoms, molecules, and solids were understood as their intrinsic properties in classical electromagnetism. It was later realized that these quantities are linked to the radiative coupling between the transition dipole and photon modes. Such effects can be greatly amplified in macroscopic many-body systems from virtual photon exchange between dipoles, but are often masked by inhomogeneity and pure dephasing, especially in solids. Here, we observe in both absorption and emission spectroscopy the renormalization of the exciton resonance and the radiative decay rate in transition metal dichalcogenides monolayers due to their radiative interactions. Tuning the photon mode density near the monolayer, we demonstrate control of cooperative Lamb shift, radiative decay, and valley polarization of the excitons as well as control of the charged exciton emission. Our work establishes a technologically accessible and robust experimental system for engineering cooperative matter-light interactions. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Structural and Electronic Optimization of MoS2 Edges for Hydrogen Evolution
(2019-11-20)
Wang, Hao
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Xiao, Xu
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Liu, Shuyuan
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Chiang, Chao-Lung
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Kuai, Xiaoxiao
The activity and accessibility of MoS2 edge sites are critical to deliver high hydrogen evolution reaction (HER) efficiency. Here, a porous carbon network confining ultrasmall N-doped MoS2 nanocrystals (N-MoS2/CN) is fabricated by a self-templating strategy, which realizes synergistically structural and electronic modulations of MoS2 edges. Experiments and density functional theory calculations demonstrate that the N dopants could activate MoS2 edges for HER, while the porous carbon network could deliver high accessibility of the active sites from N-MoS2 nanocrystals. Consequently, N-MoS2/CN possesses superior HER activity with an overpotential of 114 mV at 10 mA cm(-2) and excellent stability over 10 h, delivering one of best MoS2-based HER electrocatalysts. Moreover, this study opens a new venue for optimizing materials with enhanced accessible catalytic sites for energy-related applications.
Enhancing Condensation Heat Transfer on Three-Dimensional Hybrid Surfaces
(2019-11-20)
Lo, Ching-Wen
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Chu, Yu-Cheng
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Yen, Ming-Han
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Lu, Ming-Chang
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機械工程學系
In recent years, micro/nanostructured surfaces have been applied to enhance condensation heat transfer. However, condensation heat transfer is greatly deteriorated by the flooding phenomenon that occurs at high subcooling temperatures. Here, we propose a three-dimensional (3D) hybrid surface to enhance the condensation at high subcooling temperatures. The 3D hybrid surface consisted of superhydrophobic (SHB) Si nanowire (SiNW) arrays and hydrophilic microchannels. The microchannels could confine the liquid-film thickness, and the liquid bridges formed on the 3D hybrid surfaces could be self-removed. Both of these characteristics prevent the surfaces from flooding. In addition, liquid droplets formed in the SiNW regions were dragged into the microchannels, which also improved the heat transfer. The heat transfer coefficient on the 3D hybrid surface could be enhanced over a large subcooling range. More remarkably, a record high heat flux of 655 +/- 10 kW.m(-2) was obtained on the 3D hybrid surface.
Review-Opportunities for Rapid, Sensitive Detection of Troponin and Cerebral Spinal Fluid Using Semiconductor Sensors
(2019-11-20)
Carey, Patrick H.
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Lobo, Brian C.
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Gebhard, Michael P.
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Leon, Marino E.
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Flax, Sherri D.
There are opportunities for development of modularized, inexpensive protein biomarker sensors in clinical applications. In this review we focus on two of these, namely early diagnosis of acute myocardial infarction (AMI) and detection of cerebral spinal fluid (CSF). Evaluation of patients with acute chest pain is challenging due to the heterogeneity of the underlying conditions, leading to patients with AMI being mistakenly sent home from emergency rooms or those at low risk for an adverse cardiac event being unnecessarily admitted without precise cardiac biomarker testing. Cardiac troponin I (cTnI) in cardiac muscle tissue is a standard clinical biomarker for AMI, as its concentration rises quickly in the blood during release from myocardial cells following cell death. The time-dependence of the cTnI concentration is the basis of antigen-antibody methodologies such as radioimmunoassay and enzyme-linked immunosorbent assay (ELISA). These methods are time consuming, leading to delays in diagnosis and higher costs. The challenge is to develop a real-time, accurate, low-cost point-of-care heart attack sensor. The coefficient of variation must be precise, within the parameters established by the American College of Cardiology. Similarly, leakage of cerebrospinal fluid (CSF) is a critical condition with a high risk of meningitis and potential mortality. The primary methods of detection for the biomarker beta 2-Transfferin (B2T) are immunofixation electrophoresis (IFE) and ELISA. Consistent IFE results down to 2 mu g/mL can be obtained in patient samples, but requires a minimum 2.5-hour testing period, which is not expedient for real time feedback during surgery in or around the central nervous system. Additionally, to achieve good sensitivity and handle the inherently low concentration of B2T in CSF, lab procedures require samples to be concentrated or run in duplicate to ensure accurate detection. Real time turnaround is on the order of days. To alleviate the slow turn-around times, there is strong interest in electronic detection methods for proteins using biologically functionalized transistors, which provide an electronic readout and are readily integrated with wireless data transmission. (C) The Author(s) 2019. Published by ECS.
Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states
(2019-11-20)
Banuls, Mari Carmen
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Cichy, Krzysztof
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Kao, Ying-Jer
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Lin, C. -J. David
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Lin, Yu-Ping
Employing matrix product states as an ansatz, we study the nonthermal phase structure of the (1 + 1)-dimensional massive Thirring model in the sector of a vanishing total fermion number with staggered regularization. In this paper, details of the implementation for this project are described. To depict the phase diagram of the model, we examine the entanglement entropy, the fermion bilinear condensate, and two types of correlation functions. Our investigation shows the existence of two phases, with one of them being critical and the other gapped. An interesting feature of the phase structure is that the theory with the nonzero fermion mass can be conformal. We also find clear numerical evidence that these phases are separated by a transition of the Berezinskii-Kosterlitz-Thouless type. Results presented in this paper establish the possibility of using the matrix product states for probing this type of phase transition in quantum field theories. They can provide information for further exploration of scaling behavior, and they serve as an important ingredient for controlling the continuum extrapolation of the model.
An efficient and stable photoelectrochemical system with 9% solar-to-hydrogen conversion efficiency via InGaP/GaAs double junction
(2019-11-21)
Varadhan, Purushothaman
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Fu, Hui-Chun
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Kao, Yu-Cheng
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Horng, Ray-Hua
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He, Jr-Hau
Despite III-V semiconductors demonstrating extraordinary solar-to-hydrogen (STH) conversion efficiencies, high cost and poor stability greatly impede their practical implementation in photoelectrochemical (PEC) water splitting applications. Here, we present a simple and efficient strategy for III-V-based photoelectrodes that functionally and spatially decouples the light harvesting component of the device from the electrolysis part that eliminates parasitic light absorption, reduces the cost, and enhances the stability without any compromise in efficiency. The monolithically integrated PEC cell was fabricated by an epitaxial lift-off and transfer of inversely grown InGaP/GaAs to a robust Ni-substrate and the resultant photoanode exhibits an STH efficiency of similar to 9% with stability similar to 150 h. Moreover, with the ability to access both sides of the device, we constructed a fully-integrated, unassisted-wireless "artificial leaf" system with an STH efficiency of similar to 6%. The excellent efficiency and stability achieved herein are attributed to the light harvesting/catalysis decoupling scheme, which concurrently improves the optical, electrical, and electrocatalytic characteristics.
砸千萬拯救浪貓——音樂家林心儀
(2019-11-24)
陳姝芸
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Department of Communication and Technology
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傳播與科技學系
她，放棄身為音樂家優渥的生活，散盡千萬積蓄甚至負債，三十餘年來無怨無悔，拯救數百隻流浪毛孩。
教育現場──特殊選才到底在特殊什麼？
(2019-11-24)
石恩亞
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Department of Communication and Technology
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傳播與科技學系
考試不再是唯一的方式！「特殊選才」於107學年度起納入正式入學管道，目的是招收具有特殊才能或不同教育資歷學生，隨著試辦順利，各大學也爭相釋出名額。特殊選才對於招生方式和入學後安排，都由各大學自行籌劃，再經教育部審核即可，因此各校的特色皆不同，同時也會遇到不少困難。
一篇沒有營養卻有智慧的專訪
(2019-11-24)
林怡恩
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Department of Communication and Technology
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傳播與科技學系
「一本正經地講幹話」是沒有營養的生活智慧王的特色，他近期在臉書爆紅，教導觀眾如何在日常生活中發揮智慧。
總編輯的話
(2019-11-24)
施詞萱
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Department of Communication and Technology
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傳播與科技學系
本期別為喀報325期，共計10篇文章，包含四篇社會議題、五篇人物特寫、一篇文化現象。本篇頭題為黃心姵的〈性別友善住宿　你願意入住嗎？〉，文章以性別友善宿舍為題，分析並探討台灣的性別平等教育現象。
淺談「成功」與「失敗」這枚硬幣
(2019-11-24)
李金福
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Department of Communication and Technology
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傳播與科技學系
越來越多的人隨著創業的潮流，認可創業的精神，並且往往會把成功創業的人士，當做人生「勝利組」，也經常把「失敗」設在「成功」的對立面，人生難道就只能在兩個坑裡來回選擇嗎？
性別友善住宿　你願意入住嗎？
(2019-11-24)
黃心姵
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Department of Communication and Technology
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傳播與科技學系
台灣國立師範大學設立全台第一間「男女性同層、不同房」的性別友善宿舍。設立目的是為了讓學生在「性平教育」方面有更多的學習，然而宿舍的設立卻引起安全議題與性平教育的兩難。
「青銀共居」大齡與青年共處的新世代
(2019-11-24)
李旻珊
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Department of Communication and Technology
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傳播與科技學系
孤獨老人有陪伴需求、年輕人有住房需求，社會上急需解決的兩個問題，就這樣一手給「青銀共居」包辦了。
外送進校園　方便還是隨便？
(2019-11-24)
沈品妤
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Department of Communication and Technology
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傳播與科技學系
吃膩營養午餐或學餐了嗎？中式西式外送任你點！許多新聞平台紛紛針對位於雙北市的高中在用餐時間時，外送員雲集的景象做出報導；清華大學校方更祭出限制外送時段的做法，但遭到師生反對。究竟外送平台進入校園是帶給學生更多選擇？還是衍生出更多問題？本篇將針對此議題深入探討。
自由潛水如何自由？
(2019-11-24)
曾冠霖
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Department of Communication and Technology
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傳播與科技學系
【屏息之間的自由】專題

抽離繁忙的日常，在蔚藍之中，找尋生命起源的自由奔放。
用3000幅畫說我愛你　太太先生—馬修
(2019-11-24)
馬鈺絜
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Department of Communication and Technology
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傳播與科技學系
馬修用實際行動來證明對太太的愛，不管再忙碌、再疲勞，每天都抽空畫下與妻子的生活點滴。以貼近日常生活的情節、詼諧的插畫風格博得大眾喜愛，這段刻骨銘心的感情讓他堅決地說：「我會畫到不能再畫為止。」
連上班也在創作？TP田珮的多重生活
(2019-11-24)
曾弘碩
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Department of Communication and Technology
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傳播與科技學系
有一種頭銜叫做斜槓青年，普遍出現在現今社會當中。TP田珮除了上班之外，她的多重身分為生活增添不少樂趣。
Seeing pressure in color based on integration o highly sensitive pressure sensor and emission tunable light emitting diode
(2019-11-25)
Shen, Tien-Lin
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Chen, Chien-Tung
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Liao, Yu-Kuang
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Su, Teng-Yu
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Liu, Che-Yu
We demonstrate a highly sensitive, low-cost, environmental-friendly pressure sensor derived from a wool-based pressure sensor with wide pressure sensing range using wool bricks embedded with a Ag nano-wires. The easy fabrication and light weight allow portable and wearable device applications. Wth the integration of a light-emitting diode possessing multi-wavelength emission, we illustrate a hybrid multi-functional LED-integrated pressure sensor that is able to convert different applied pressures to light emission with different wavelengths. Due to the high sensitivity of the pressure sensor, the demonstration of acoustic signal detection has also been presented using sound of a metronome and a speaker playing a song. This multi-functional pressure sensor can be implemented to technologies such as smart lighting, health care, visible light communication (VLC), and other internet of things (IoT) applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Optical servo with high design freedom using spherical-wave Bragg degeneracy in a volume holographic optical element
(2019-11-25)
Yu, Yeh-Wei
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Shu, Chung-Mou
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Sun, Ching-Cherng
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Hsieh, Po-Kai
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Yang, Tsung-Hsun
A novel optical sensor is proposed and demonstrated with the use of spherical-wave Bragg degeneracy of a volume holographic optical element. Bragg degeneracy can be performed perfectly for a volume hologram written by two plane waves or spherical waves. But only spherical reference light is useful to perform severe shifting selectivity in one direction and Bragg degeneracy in another direction. The experiment corresponding to theoretical simulation was demonstrated in a volume holographic optical element, which was an optical servo for a collinear volume holographic disc. Through clever design, the displacement response of the tracking beam was observed for a magnification magnitude of 980% to the displacement of the probe beam so that the resolution requirement of the photosensor can be reduced. Besides, a high linearity of the displacement response was observed. To discover the design freedom, a theoretical study of the displacement response was done for the servo by two spherical waves. The linearity, the magnification magnitude, and the diffraction efficiency were examined and the property of the Bragg degeneracy was figured out. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Comparison of Properties of Thin Film AlGaInP LEDs with Composite Metal and Si Substrates
(2019-11-25)
Sinha, ShreeKant
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Feng, Hsiang-An
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Chung, Cheng-Yu
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Tu, Chia-Wei
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Horng, Ray-Hua
N-side up thin-AlGaInP epilayers based on vertical light-emitting diodes (VLEDs) (light emitting area: 44 mil x 44 mil) with Si and composite metal (copper/Invar/copper; CIC) substrates were obtained by wafer bonding and epilayer transferring technologies. The coefficients of thermal expansion of the Si and CIC substrates were about 2.6 x 10(-6) /K and 6.1 x 10(-6) /K respectively. The coefficient of thermal expansion of CIC was matched to the GaAs substrate and AlGaInP epilayer. After the epilayer transferred to the CIC substrate, a small amount of bending occurred. The performance of the packaged LEDs/CIC was almost the same with that of LEDs/Si. The redshift phenomenon was from 623 to 643 nm for the CIC/LEDs while that of the LEDs/Si chip was from 625 to 643 nm with an injected current from 100 mA to 1 A and high output power (251 mW at 1 A) as compared to packaged LEDs/Si (299.5 mW at 1 A). The variation in light-emitting wavelengths of the LEDs/CIC was the same with that of the LEDs/Si. The distribution of the temperature of the LEDs on the CIC substrate was less than the LEDs on Si throughout the surface. The obtained data suggested that CIC could be extended instead of a Si substrate for high-power thin film LEDs applications. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.