Browsing by Issue Date, starting with "2020-04-25"

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Enhanced photovoltaic performance of Y2O3:Ho3+/Yb3+ upconversion nanophosphor based DSSC and investigation of color tunability in Ho3+/Tm3+/Yb3+ tridoped Y2O3
(2020-04-25)
Tadge, Prachi
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Yadav, Ram Sagar
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Vishwakarma, Pradeep Kumar
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Rai, S. B.
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Chen, Teng-Ming
The present study reports the upconversion (UC) based color tuning in Y2O3:Ho3+/Yb3+, Y2O3:Tm3+/Yb3+ and Y2O3:Tm3+/Ho3+/Yb3+ phosphors synthesized through complex based precursor solution method. The Y2O3:Ho3+/Yb3+ phosphor emits intense green and weak red colors whereas the Y2O3:Tm3+/Yb3+ emits NIR and blue colors on excitation with 976 nm. The impact of the enhancement in the concentration of Yb3+ on the color point of codoped as well as tridoped phosphors has been studied in detail. When Y2O3:Tm3+/Ho3+/Yb3+ phosphor is excited by 976 nm laser, the phosphor emits dominant green color. This is due to energy transfer from Tm3+ to Ho3+ ions. The increase in the concentration of Yb3+ ion leads to a color tunability not only in the co-doped but also in the tridoped phosphors. Furthermore, we have incorporated Y2O3:Ho3+,Yb3+ UC phosphor into TiO2 electrode to form an UC based DSSC for converting near IR (NIR) light into visible where DSSCs typically have high sensitivity. The short-circuit current density (Jsc) as well as the open-circuit voltage (Voc) of the UC-TiO2 based cell was found to be 8.46% and 5.18% higher which in turn, resulted into a 10.33% enhancement in power conversion efficiency as compared to that of bare TiO2 based DSSC. Thus, the UC based Y2O3:Ho3+/Yb3+ may be useful in color tunability and DSSC applications. (C) 2019 Elsevier B.V. All rights reserved.
3C時代，你網路成癮了嗎？
(2020-04-26)
周容萱
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Department of Communication and Technology
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傳播與科技學系
人人都有網路成癮？自從智慧型手機的出現、科技發展的便利，我們的生活已經完全離不開手機和網路，一聲「叮咚」，就能獲取我們的注意力。
不「紙」是搶劫
(2020-04-26)
李詠濠
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Department of Communication and Technology
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傳播與科技學系
誰說搶劫一定是壞人？《紙房子》大大顛覆觀眾的刻板印象。
總編輯的話
(2020-04-26)
高儷玲
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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335期，總計10篇文章。其中有一半為人物特寫，3篇社會議題，以及2篇藝文評論。本期頭題為廖玥茹的《偷拍——躲藏在社群及法律邊緣》，點出容易被忽視卻是潛在的社會議題。另外，本期的人物特寫也十分精彩，呈現各式各樣的職業，望讀者能藉此認識更多在自己領域默默耕耘的小人物。
Alex人生日記　不只是時尚部落客
(2020-04-26)
邱欣誼
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Department of Communication and Technology
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傳播與科技學系
從時尚雜誌編輯、國際品牌行銷、電商到公關，對時尚產業如數家珍的Alex Shih（以下簡稱Alex），謙虛地表示自己還在學習的路上。除了朝九晚五的正職，Alex也是一名部落客和專欄作家。文章內容從時尚產業觀察日記，到影視節目的推薦賞析，再到人生際遇的分享，多篇文章同時被轉載於女人迷、關鍵評論等媒體。
熱愛網球的陽光青年　鄭國亨
(2020-04-26)
張筠婕
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Department of Communication and Technology
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傳播與科技學系
鄭國亨，從七歲開始接觸網球，如今已在網球路上走了十五年。曾在全中運、全大運拿下亮眼成績的他，是一名對網球充滿熱情的運動員。
你是我的眼　視障陪跑員陳梅菊
(2020-04-26)
黃博暄
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Department of Communication and Technology
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傳播與科技學系
沒有人敢在黑暗中奔跑，有了這群熱情的陪跑員，指引了視障朋友方向，開啟視障人士不同的路跑生涯。
警察出腳　踹出警界制度問題
(2020-04-26)
楊詠嵐
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Department of Communication and Technology
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傳播與科技學系
本月初發生的中和分局警察踹頭事件，激起了社會各界的討論。除了探討警察是否執法過當外，更重要的是找出警察工作的文化與制度有哪些問題，並朝正確的方向進行警政改革，讓警察有更好的勞動條件，才能避免更多誤判情勢的情形發生。
聲音，讓畫面不一樣　戴志光
(2020-04-26)
吳政陽
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Department of Communication and Technology
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傳播與科技學系
影像和聲音使我們的日常生活富有色彩，在影像產業越來越重要的時代下，配音和錄音師們的角色也日趨重要，合拍的音效讓影像更加生動，這就是錄音師的魔法。
邱福源　活在藝術裡的男人
(2020-04-26)
許峰睿
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Department of Communication and Technology
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傳播與科技學系
對邱福源來說，畫圖已經無法滿足自己創作藝術的慾望，因此開始從事木工。對於他而言，木工不只是製作家具、器具，而是把藝術融入生活中的一種方式。
偷拍——躲藏在社群及法律邊緣
(2020-04-26)
廖玥茹
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Department of Communication and Technology
;
傳播與科技學系
你有被偷拍過嗎？或是你有偷拍過別人嗎？未經許可的拍攝，照片只要不含隱私部位、不露臉，就不違法嗎？科技的便利不是要成為傷害別人的工具，當我們對他人有基本的尊重及性別教育觀念時，才能創造更好的社會。
移民者背後的辛酸　《虎尾》
(2020-04-26)
梁子敬
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Department of Communication and Technology
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傳播與科技學系
《虎尾》（Tigertail）於2020年4月10日於Netflix上映，由楊維榕編劇及導演。透過多個角度來描述移民者的故事以及家庭問題。電影促進東西方文化的交流，也讓西方世界的觀眾可以更了解移民者的心境。
A Strategy to Synthesize Ultrahigh-N-Doped Hierarchical Carbons via Induced beta-Sheet from Silk Fibroin by In Situ Electrogelation/Electropolymerization
(2020-04-27)
Liu, Ta-Chung
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Li, Tsung-Yu
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Hung, Pei-Sung
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Liang, Chun-Wei
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Wu, Szu-Chen
Silk fibroin (SF) is recognized for its rich nitrogen content and has been explored for its promising potential in energy storage because of its hexagonal pseudographitic structure from the direct transformation of the unique secondary protein beta-sheet peptides of carbonized SF. In this work, we proposed a novel strategy that combined with in situ electrophoresis and electrogelation of SF as well as the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) for producing high-level nitrogen-doped (N-doped) carbons. A high beta-sheet content of SF can be synthesized in a three-dimensional (3D) inverse opaline skeleton via double-network microstructure (physical beta-sheet cross-linking and chemical PEDOT cross-linking) induced by the hydrophobic EDOTs. This synergistic effect regulating SF distribution and balancing the intra/intermoleeular hydrogen bonding among SF results in boosting beta-sheet contents. Herein, this 3D SF/PEDOT composite inverse opal (SPIO) exhibits a much ultrahigh-coneentrated beta-sheets (46.4%) compared to pure electrogelated SFIO with 16.4% of beta-sheets. After subsequent pyrolysis, a high-level (14.7%) N-doped pseudographitic carbon inverse opal is realized. For evaluation as a pseudocapacitor, this high-level N-doped pseudographitic carbon inverse opal shows a capacitance of 342 F g(-1) at 0.5 A g(-1) and a commendable energy density of 31.7 Wh kg(-1) at an ultrahigh power density of 25009 W kg(-1) (at 50 A g(-1)). After galvanostatic charging/discharging at 15 A g(-1) for 10000 cycles, the sample maintains an impressive capacitance retention of 89.8%.
Annealed Polycrystalline TiO2 Interlayer of the n-Si/TiO2/Ni Photoanode for Efficient Photoelectrochemical Water Splitting
(2020-04-27)
Chuang, Chi-Huang
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Lai, Yung-Yu
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Hou, Cheng-Hung
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Cheng, Yuh-Jen
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材料科學與工程學系
High photovoltage generation from a photoelectrode is important for efficient solar-driven water splitting. Here, we report a thermal treatment process that greatly enhances photovoltage generation from an n-Si/TiO2/Ni photoanode. By selectively annealing the TiO2 interlayer, the photoanode generates a high photovoltage of 570 mV, which is very competitive as compared with photovoltages produced using other similar metal-insulator-semiconductor structures with earth-abundant metal catalysts. Different annealing conditions and junction layer thicknesses were systematically investigated. It is found that the optimal annealing temperature occurs between 500 and 600 degrees C. Within this temperature range, the deposited amorphous Ti is converted into polycrystalline anatase phase TiO2. The optimal annealing time scales linearly with TiO2 thickness and inversely with annealing temperature. The large photovoltage generation is attributed to the reduced defect states and improved junction barrier height by the annealed TiO2 interlayer. This study demonstrates that thermal annealing offers an attractive approach to modify the TiO2 interlayer material's properties for photovoltage optimization.
Flexible BSA MIM capacitor with negative voltage coefficient for RF applications
(2020-04-27)
Kumar, Parkarsh
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Guhathakurata, Shrabani
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Choudhury, A.
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Sharma, A.
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Tripathy, Anupam R.
In this report, Bovine Serum Albumin-based Metal-Insulator-Metal structures on Indium doped Tin Oxide coated flexible Polyethylene Terephthalate substrates with Aluminum (Al) as the top electrode have been fabricated and studied in detail. The thickness of the film was measured using a Field Emission Scanning Electron Microscope. The Fourier Transform Infrared Attenuated Total Reflectance spectrum confirms the presence of both amide-I and amide-II in the protein film. Ultraviolet-Visible Spectroscopy was performed for the absorption spectrum used to extract the optical bandgap. The surface roughness of the film was estimated by Atomic Force Microscopy. Electrical characterization of the devices gives a high capacitance density with a negative quadratic coefficient and a low dissipation factor, showing their potential for Radio Frequency/analog application. The number of dipoles (N-PD) is found to be 1.01x10(18)cm(-3) with a permanent dipole moment (mu (0)) of 2.92x10(-25) C m at an applied frequency of 1MHz. The devices show high reliability resistant to degradation, studied by Constant Voltage Stressing. We also examined the performance of these flexible devices by repeated bending with different bending radii.
Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions
(2020-04-27)
Bennett, Ed
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Hong, Deog Ki
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Lee, Jong-Wan
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Lin, C-J David
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Lucini, Biagio
We perform lattice studies of meson mass spectra and decay constants of the Sp(4) gauge theory in the quenched approximation. We consider two species of (Dirac) fermions as matter field content, transforming in the 2-index antisymmetric and the fundamental representation of the gauge group, respectively. All matter fields are formulated as Wilson fermions. We extrapolate to the continuum and massless limits and compare to each other the results obtained for the two species of mesons. In the case of two fundamental and three antisymmetric fermions, the long-distance dynamics is relevant for composite Higgs models. This is the first lattice study of this class of theories. The global SU(4) x SU(6) symmetry is broken to the Sp(4) x SO(6) subgroup, and the condensates align with the explicit mass terms present in the lattice formulation of the theory. The main results of our quenched calculations are that, with fermions in the 2-index antisymmetric representation of the group, the masses squared and decay constant squared of all the mesons we considered are larger than the corresponding quantities for the fundamental representation, by factors that vary between similar to 1.2 and similar to 2.7. We also present technical results that will be useful for future lattice investigations of dynamical simulations, of composite chimera baryons, and of the approach to large N in the Sp(2N) theories considered. We briefly discuss their high-temperature behavior, where symmetry restoration and enhancement are expected.
Spatiotemporal Dynamics of Aggregation-Induced Emission Enhancement Controlled by Optical Manipulation
(2020-04-27)
Wang Shun-Fa
;
Lin Jhao-Rong
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Ishiwari, Fumitaka
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Fukushima, Takanori
;
Masuhara, Hiroshi
We present spatiotemporal control of aggregation-induced emission enhancement (AIEE) of a protonated tetraphenylethene derivative by optical manipulation. A single submicrometer-sized aggregate is initially confined by laser irradiation when its fluorescence is hardly detectable. The continuous irradiation of the formed aggregate leads to sudden and rapid growth, resulting in bright yellow fluorescence emission. The fluorescence intensity at the peak wavelength of 540 nm is tremendously enhanced with growth, meaning that AIEE is activated by optical manipulation. Amazingly, the switching on/off of the activation of AIEE is arbitrarily controlled by alternating the laser power. This result means that optical manipulation increases the local concentration, which overcomes the electrostatic repulsion between the protonated molecules, namely, optical manipulation changes the aggregate structure. The dynamics and mechanism in AIEE controlled by optical manipulation will be discussed from the viewpoint of molecular conformation and association depending on the laser power.
Layer-Dependent and In-Plane Anisotropic Properties of Low-Temperature Synthesized Few-Layer PdSe2 Single Crystals
(2020-04-28)
Lu, Li-Syuan
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Chen, Guan-Hao
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Cheng, Hui-Yu
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Chuu, Chih-Piao
;
Lu, Kuan-Cheng
Palladium diselenide (PdSe2), a peculiar noble metal dichalcogenide, has emerged as a new two-dimensional material with high predicted carrier mobility and a widely tunable band gap for device applications. The inherent in-plane anisotropy endowed by the pentagonal structure further renders PdSe2 promising for novel electronic, photonic, and thermoelectric applications. However, the direct synthesis of few-layer PdSe2 is still challenging and rarely reported. Here, we demonstrate that few-layer, single-crystal PdSe2 flakes can be synthesized at a relatively low growth temperature (300 degrees C) on sapphire substrates using low-pressure chemical vapor deposition (CVD). The well-defined rectangular domain shape and precisely determined layer number of the CVD-grown PdSe2 enable us to investigate their layer-dependent and in-plane anisotropic properties. The experimentally determined layer-dependent band gap shrinkage combined with first-principle calculations suggest that the interlayer interaction is weaker in few-layer PdSe2 in comparison with that in bulk crystals. Field-effect transistors based on the CVD-grown PdSe2 also show performances comparable to those based on exfoliated samples. The low-temperature synthesis method reported here provides a feasible approach to fabricate high-quality few-layer PdSe2 for device applications.
Sub-stoichiometric reductive etherification of carbohydrate substrates and one-pot protecting group manipulation
(2020-04-28)
Chen, Chiao Wen
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Wang, Ching Chi
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Li, Xin Ru
;
Witek, Henryk
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Mong, Kwok-Kong Tony
In this study, we report a new reductive etherification procedure for protection of carbohydrate substrates and its application for one-pot preparation of glycosyl building blocks. The reported procedure features the use of polymethylhydrosiloxane (PMHS) as a sub-stoichiometric reducing agent, which prevents the transilylation side reaction and improves the efficiency of the reductive etherification method. Application of the PMHS reductive etherification procedure for one-pot protecting group manipulation are described.
Imaging and time-resolved study of laser-induced fluorescence of dysprosium atoms injected into superfluid helium
(2020-04-28)
Moroshkin, P.
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Kono, K.
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國際半導體學院
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International College of Semiconductor Technology
We study the time evolution of the cloud of Dy atoms dispersed in superfluid helium and investigate the possibility of using these atoms as tracers for the imaging of superfluid-helium flows. The atoms are produced by pulsed laser ablation and are visualized via their laser-induced fluorescence. It turns out that the observation time is limited by the optical pumping of the atomic population into a nonabsorbing metastable state which is also responsible for the saturation of the fluorescence yield observed earlier.