Browsing by Issue Date, starting with "2020-07-29"

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Correlation among photoluminescence and the electronic and atomic structures of Sr2SiO4:xEu(3+) phosphors: X-ray absorption and emission studies
(2020-07-29)
Zheng, Shi-Yan
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Chiou, Jau-Wern
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Li, Yueh-Han
;
Yang, Cheng-Fu
;
Ray, Sekhar Chandra
A series of Eu3+-activated strontium silicate phosphors, Sr2SiO4:xEu(3+) (SSO:xEu(3+), x=1.0, 2.0 and 5.0%), were synthesized by a sol-gel method, and their crystalline structures, photoluminescence (PL) behaviors, electronic/atomic structures and bandgap properties were studied. The correlation among these characteristics was further established. X-ray powder diffraction analysis revealed the formation of mixed orthorhombic alpha'-SSO and monoclinic beta-SSO phases of the SSO:xEu(3+) phosphors. When SSO:xEu(3+) phosphors are excited under ultraviolet (UV) light (lambda=250 nm,similar to 4.96 eV), they emit yellow (similar to 590 nm), orange (similar to 613 nm) and red (similar to 652 and 703 nm) PL bands. These PL emissions typically correspond to 4f-4f electronic transitions that involve the multiple excited D-5(0)-> F-7(J) levels (J=1, 2, 3 and 4) of Eu3+ activators in the host matrix. This mechanism of PL in the SSO:xEu(3+) phosphors is strongly related to the local electronic/atomic structures of the Eu3+-O2- associations and the bandgap of the host lattice, as verified by Sr K-edge and Eu L-3-edge X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure, O K-edge XANES and K-alpha X-ray emission spectroscopy. In the synthesis of SSO:xEu(3+) phosphors, interstitial Eu2O3-like structures are observed in the host matrix that act as donors, providing electrons that are nonradiatively transferred from the Eu 5d and/or O 2p-Eu 4f/5d states (mostly the O 2p-Eu 5d states) to the D-5(0) levels, facilitating the recombination of electrons that have transitioned from the D-5(0) level to the F-7(J) level in the bandgap. This mechanism is primarily responsible for the enhancement of PL emissions in the SSO:xEu(3+) phosphors. This PL-related behavior indicates that SSO:xEu(3+) phosphors are good light-conversion phosphor candidates for use in near-UV chips and can be very effective in UV-based light-emitting diodes.
科技部大專生研究獎，陽明獲獎人數創新高
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
科技部公布「108年度大專學生研究計畫研究創作獎」得獎名單，陽明今年獲獎人數創新高，共有五位同學獲獎，包括醫學系「醫師科學家.
學餐暑假大翻修，九月全新亮相
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
今年暑假期間，校內有多項工程進行，其中比較大的一項，就是學餐大翻修，包括外牆、內部設施、軟硬體全部進行翻新，預計九月中開...
陽明「偏鄉醫學體驗營」，培養小小部落之星
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
7月13日這天，陽明迎來一批特別的小小嘉賓。他們是遠從宜蘭山地部落而來，18位南澳國小四、五年級的小朋友。這是他們第一次來到台
醫工學院「創新創業課程」，培育生醫跨領域人才
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
生物醫學暨工程學院過去六年辦理創新創業人才培育計畫，歷年得獎成果豐碩，共獲18大獎，很榮幸今年續辦教育部「生醫產業與新農業.
2020 亞洲生技大展，陽明產學研醫、研學能量再突破
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
今年台灣生技年度盛事「2020 亞洲生技大會（BIO Asia-Taiwan）」在疫情中堅定向前，以全新「實體在線」（Online + Live）模式盛大...
美食記憶三疊
(國立陽明大學, 2020-07-30)
張麗君
;
陽明電子報編輯小組
【109年動物中心使用說明會】
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
講述有關動物中心各區使用方式、動物訂購、代養、轉移和移房等.
【109年職員教育訓練課程2】困境與突破～從貝多芬《命運》聽起
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
日期：8月4日（二）時間：9:40-12:10 地點：圖資402教.
「愛呀，你好！」社募書活動～用閱讀為孩童築夢
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
「愛呀，你好！」社成立至今，已邁入第六年。一直以來，本社的宗旨就是藉由陪伴與服務，為榮總兒童癌症病房的病童營造一個有活力的環境，讓他們在醫院的生活不是只有化療，還多了一些與外界接觸的機會，增添生活中特別的經驗。而本社的服務，這六年來也在榮總兒童癌症病房得到很多熱烈的迴響。今年（2020年）二月初，由於武漢肺炎疫情迅速蔓延，在諮詢過醫師後，確定這學期（108學年度下學期）我們無法再進入病房陪伴兒童。這個消息讓我們感到非常的遺憾，因為突如其來的疫情，讓我們失去了進行服務最重要的管道。考量到上述問題，我們決定與「書寶二手書店」合作。
Detection of a Criegee Intermediate with an Unsaturated Hydrocarbon Substituent: Fourier-Transform Microwave Spectroscopy of Methyl Vinyl Ketone Oxide
(2020-07-30)
Endo, Yasuki
;
Witek, Henryk A.
;
Chung, Chen-An
;
Lee, Yuan-Pern
;
交大名義發表
Pure rotational transitions of methyl vinyl ketone oxide, or the so called methyl-vinyl Criegee intermediate, were observed by Fourier-transform microwave spectroscopy. Among the four possible conformers of this species, predicted by theory within an energy window of 3 kcal/mol, only the lowest-energy conformer, the syn-trans form, was detected in a discharged jet of a 1,3-diiode-but-2-ene (either in Z- or E-conformation) and O-2 mixture diluted in Ar. Thirty pure rotational transitions with internal rotation splitting of the methyl top were observed. The observed frequencies were analyzed by the XIAM program, yielding an internal rotation barrier of 702.8(28) cm(-1), which reasonably agrees with a theoretical value of 680 cm(-1) determined with CCSD(T)/cc-pVTZ.
Dynamic Coupling of Optically Evolved Assembling and Swarming of Gold Nanoparticles with Photothermal Local Phase Separation of Polymer Solution
(2020-07-30)
Aibara, Issei
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Huang, Chih-Hao
;
Kudo, Tetsuhiro
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Bresoli-Obach, Roger
;
Hofkens, Johan
Optical trapping of gold nanoparticles (Au NPs) at a glass/solution interface initially generates a periodically aligned structure of a few NPs along the direction perpendicular to a linearly polarized laser. When the number of NPs was increased, this alignment was expanded to the outside of the irradiated focus, forming a single large assembly where the Au NPs dynamically fluctuated like a swarming of bees. The morphology was dumbbell-shape, consisting of two swarms at both sides of the focus, and its size reached about 10 mu m. This optically evolved assembling and swarming was studied in poly(N-isopropylacrylamide) (PNIPAM) solution, where liquid-liquid phase separation (LLPS) was induced by photothermal heating of the trapped Au NPs forming a microdroplet of highly concentrated PNIPAM. Dynamic coupling of the NPs assembling and swarming with the droplet formation of PNIPAM leads to cooperative optical evolution, through which the assembly was embedded in the single microdroplet.
【陽明合唱團2020年度公演】
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
日期：8月23日（日）時間：8:30-17:20 地點：陽明大學...
Highly improved convergence approach incorporating edge conditions for scattering analysis of graphene gratings
(2020-07-30)
Hwang, Ruey-Bing
;
交大名義發表
;
National Chiao Tung University
This research developed an effective and efficient approach for improving the slow convergence in the scattering analysis of a one-dimensional graphene grating, made of a periodic array of parallel graphene strips, illuminated by a TM-polarized plane wave. Specifically, the electric fields over the graphene strips and slit regions in a unit cell are individually expressed as an expansion of local basis functions inherently satisfying edge conditions. Interestingly, convergence rate is highly improved compared to the customary and modified Fourier modal method. Additionally, with the aid of local basis functions, the Gibbs phenomenon occurring at both edges of graphene strip can be removed.
【109年職員教育訓練課程3】提升心的生產力
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
日期：8月18日（二）時間：9:40-12:10 地點：圖資402教..
【109學年度學生體檢】
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
日期：9月8日（二）、9日（三）時間：8:30-16:00 地點
【生醫領航方舟】企業講座外一章～腦與禪：從腦科學看禪定
(國立陽明大學, 2020-07-30)
陽明電子報編輯小組
因疫情而延後舉辦的【生醫領航方舟～企業講座外一章】，由謝仁俊教授主講的「腦與禪：從腦科學看禪定」，重新隆重登場囉！ ..
Ruthenium substituted pyrochlore metal oxide catalysts Y2Ce2-xRuxO7-delta (x=0-0.4) for oxidative steam reforming of ethanol
(2020-07-31)
Hsieh, Ho-Chen
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Chen, Yun-Sheng
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Weng, Sheng-Feng
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Hsieh, Yu-Ping
;
Lee, Chi-Shen
Metal oxides Y2Ce2-xRuxO7-delta (x = 0-0.4) with partial substitution of Run+ cations in the host structure were synthesized to study their catalytic activity on oxidative steam reforming of ethanol (OSRE). The samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). The performances investigated by varied temperatures, Ru ion content, carbon-to-oxygen ratios and long-term stability. The lowest activation temperature on OSRE is 300 degrees C, which is significantly lower than that of La2Ce2-xRuxO7-delta (400 degrees C). The cell dimension of Y2Ce2-xRuxO7-delta was reduced compare to La2Ce2-xRuxO7-delta for the replacement of the Y3+ ion with La3+ ion. The reduced unit cell in the host structure not only increase the surface composition of the Ce4+ ions, but also induce the synergetic effect of Run+/Ru4+ (n > 4) and Ce4+/Ce3+, which lead to the enhanced OSRE activity. The optimized catalyst Y2Ce1.6Ru0.4O7-delta showed selectivity of hydrogen S-H2 = 84(4)% (Y-H2 = 2.5(1) mol/mol EtOH) and carbon monoxide S-CO = 48(1)% for long-term stability test at T = 300 degrees C, C/O = 0.5, and O-2/C2H5OH = 1.5. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Substrate-induced strain in 2D layered GaSe materials grown by molecular beam epitaxy
(2020-07-31)
Liu, Cheng-Wei
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Dai, Jin-Ji
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Wu, Ssu-Kuan
;
Nhu-Quynh Diep
;
Sa-Hoang Huynh
Two-dimensional (2D) layered GaSe films were grown on GaAs (001), GaN/Sapphire, and Mica substrates by molecular beam epitaxy (MBE). The in situ reflective high-energy electron diffraction monitoring reveals randomly in-plane orientations of nucleated GaSe layers grown on hexagonal GaN/Sapphire and Mica substrates, whereas single-orientation GaSe domain is predominant in the GaSe/GaAs (001) sample. Strong red-shifts in the frequency of in-plane E2g2 vibration modes and bound exciton emissions observed from Raman scattering and photoluminescence spectra in all samples are attributed to the unintentionally biaxial in-plane tensile strains, induced by the dissimilarity of symmetrical surface structure between the 2D-GaSe layers and the substrates during the epitaxial growth. The results in this study provide an important understanding of the MBE-growth process of 2D-GaSe on 2D/3D hybrid-heterostructures and pave the way in strain engineering and optical manipulation of 2D layered GaSe materials for novel optoelectronic integrated technologies.
Ultrafast laser ablation of copper by GHz bursts
(2020-07-31)
Cheng, Chung-Wei
;
Chen, Jinn-Kuen
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機械工程學系
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Department of Mechanical Engineering
The ablation of copper, using a 10 GHz burst ultrafast laser with a wavelength of 1030 nm, a pulse duration of 1 ps, a variable total laser fluence, and a number of sub-pulses per burst, is investigated theoretically. A two-temperature model with an extended Lorentz-Drude model for dynamic optical properties is used to simulate the melting and ablation process. Due to the heat accumulation from the preceding pulses, multipulse laser ablation could be advantageous over a single pulse. Moreover, the ablation performance can be maximized by properly selecting the pulse number, separation time, and energy in a laser burst. The numerical result shows that the present prediction is in fairly agreement with existing experimental result. Under the same total laser fluence of 32 J/cm(2), a 10 GHz burst laser with an optimized 128 sub-pulse can significantly enhance the ablation depth, 4.2 times that a single pulse does. It is found that the optimized ablation depth is a linear function of the total fluence of ultrafast laser bursts.