Browsing by Issue Date, starting with "2016-04-07"

Now showing 1 - 20 of 17554

Photoisomerization mechanisms from trans, trans-1,4-diphenyl-1,3-butadiene: CASSCF on-the-fly trajectory surface hopping dynamic simulations
(2016-04-07)
Zheng, Xiaolei
;
Zhai, Gaohong
;
Gao, Wanqing
;
Lei, Yibo
;
Yu, Le
We have employed the SA2-CAS(4,4)/6-31G ab initio method together with an on-the-fly global-switching trajectory surface hopping algorithm to simulate photoisomerization reaction dynamics from reactant trans, trans-1,4-diphenyl-1,3-butadiene (DPB) to products cis,trans-DPB and cis,cis-DPB. This topic has been extensively studied experimentally and the present theoretical study is the first to simulate DPB photoisomerization reaction dynamics as far as we know. With total 600 sampling trajectories, 300 actively contribute to isomerization reaction via two conical intersections between the electronic ground and the first excited states. Simulated quantum yields of photoisomerization to cis, trans-DPB and cis, cis-DPB are 0.09 and 0.045, which are in good agreement with the experimental values of 0.07-0.25 and 0.02, respectively. The lifetime of the first excited state is estimated as 702 fs. The present simulation has shown two reactive photoisomerization mechanisms, namely one bond twist (OBT) and bicycle pedal (BP), and two non-reactive photoisomerization mechanisms, namely single bond torsion (SBT) and reverse torsion (RT) with respect to the central backbone CC bonds. We believe that the present theoretical work can benefit the experiments on photoisomerization of DPB derivates.
Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory
(2016-04-07)
Blyth, S. C.
;
Chan, Y. L.
;
Chen, X. C.
;
Chu, M. C.
;
Cui, K. X.
We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be I-mu = (5.7 +/- 0.6) x 10(-6) cm(-2) s(-1) sr(-1). The yield of muon-induced neutrons in the liquid scintillator was determined to be Y-n = (1.19 +/- 0.08(stat) +/- 0.21(syst)) x 10(-4) neutrons/(mu.g.cm(-2)). A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of < E-mu >(0.76 +/- 0.03) for liquid-scintillator targets.
Extremal RN/CFT in both hands revisited
(2016-04-10)
Kuo, En-Jui
;
Yang, Yi
;
電子物理學系
;
Department of Electrophysics
We study RN/CFT correspondence for four dimensional extremal Reissner-Nordstrom black hole. We uplift the 4d RN black hole to a 5d rotating black hole and make a geometric regularization of the 5d space-time. Both hands central charges are obtained correctly at the same time by Brown-Henneaux technique. (C) 2016 The Authors. Published by Elsevier B.V.
Restoring electronic coherence/decoherence for a trajectory-based nonadiabatic molecular dynamics
(2016-04-11)
Zhu, Chaoyuan
;
應用化學系分子科學碩博班
;
Institute of Molecular science
By utilizing the time-independent semiclassical phase integral, we obtained modified coupled time-dependent Schrodinger equations that restore coherences and induce decoherences within original simple trajectory-based nonadiabatic molecular dynamic algorithms. Nonadiabatic transition probabilities simulated from both Tully's fewest switches and semiclassical Ehrenfest algorithms follow exact quantum electronic oscillations and amplitudes for three out of the four well-known model systems. Within the present theory, nonadiabatic transitions estimated from statistical ensemble of trajectories accurately follow those of the modified electronic wave functions. The present theory can be immediately applied to the molecular dynamic simulations of photochemical and photophysical processes involving electronic excited states.
Helical Majorana fermions in d(x2-y2) + id(xy)-wave topological superconductivity of doped correlated quantum spin Hall insulators
(2016-04-11)
Sun, Shih-Jye
;
Chung, Chung-Hou
;
Chang, Yung-Yeh
;
Tsai, Wei-Feng
;
Zhang, Fu-Chun
There has been growing interest in searching for exotic self-conjugate, charge-neutral low-energy fermionic quasi-particles, known as Majorana fermions (MFs) in solid state systems. Their signatures have been proposed and potentially observed at edges of topological superconcuctors with non-trivial topological invariant in the bulk electronic band structure. Much effort have been focused on realizing MFs in odd-parity superconductors made of strong spin-orbit coupled materials in proximity to conventional superconductors. In this paper, we propose a novel mechanism for realizing MFs in 2D spin-singlet topological superconducting state induced by doping a correlated quantum spin Hall (Kane-Mele) insulator. Via a renormalized mean-field approach, the system is found to exhibits time-reversal symmetry (TRS) breaking d(x2-y2) + id(xy)-wave (chiral d-wave) superconductivity near half-filling in the limit of large on-site repulsion. Surprisingly, however, at large spin-orbit coupling, the system undergoes a topological phase transition and enter into a new topological phase protected by a pseudo-spin Chern number, which can be viewed as a persistent extension of the quantum spin Hall phase upon doping. From bulk-edge correspondence, this phase is featured by the presence of two pairs of counter-propagating helical Majorana modes per edge, instead of two chiral propagating edge modes in the d + id' superconductors.
A high performance transparent resistive switching memory made from ZrO2/AlON bilayer structure
(2016-04-11)
Tsai, Tsung-Ling
;
Chang, Hsiang-Yu
;
Lou, Jesse Jen-Chung
;
Tseng, Tseung-Yuen
;
電子工程學系及電子研究所
In this study, the switching properties of an indium tin oxide (ITO)/zirconium oxide (ZrO2)/ITO single layer device and those of a device with an aluminum oxynitride (AlON) layer were investigated. The devices with highly transparent characteristics were fabricated. Compared with the ITO/ZrO2/ITO single layer device, the ITO/ZrO2/AlON/ITO bilayer device exhibited a larger ON/OFF ratio, higher endurance performance, and superior retention properties by using a simple two-step forming process. These substantial improvements in the resistive switching properties were attributed to the minimized influence of oxygen migration through the ITO top electrode (TE), which can be realized by forming an asymmetrical conductive filament with the weakest part at the ZrO2/AlON interface. Therefore, in the ITO/ZrO2/AlON/ITO bilayer device, the regions where conductive filament formation and rupture occur can be effectively moved from the TE interface to the interior of the device. Published by AIP Publishing.
Organic Photovoltaics and Bioelectrodes Providing Electrical Stimulation for PC12 Cell Differentiation and Neurite Outgrowth
(2016-04-13)
Hsiao, Yu-Sheng
;
Liao, Yan-Hao
;
Chen, Huan-Lin
;
Chen, Peilin
;
Chen, Fang-Chung
Current bioelectronic medicines for neurological therapies generally involve treatment with a bioelectronic system comprising a power supply unit and a bioelectrode device. Further integration of wireless and self-powered units is of practical importance for implantable bioelectronics. In this study, we developed biocompatible organic photovoltaics (OPVs) for serving as wireless electrical power supply units that can be operated under illumination with near-infrared (NIR) light, and organic bioelectronic interface (OBEI) electrode devices as neural stimulation electrodes. The OPV/OBEI integrated system is capable to provide electrical stimulation (ES) as a means of enhancing neuron-like PC12 cell differentiation and neurite outgrowth. For the OPV design, we prepared devices incorporating two photoactive material systems-beta-carotene/N,N\'-dioctyl-3,4,9,10-perylenedicarboximide (beta-carotene/PTCDI-C8) and poly(3-hexylthiophene)/phenyl-C-61-butyric acid methyl ester (P3HT/PCBM)-that exhibited open circuit voltages of 0.11 and 0.49 V, respectively, under NIR light LED (NLED) illumination. Then, we connected OBEI devices with different electrode gaps, incorporating biocompatible poly(hydroxymethylated-3,4-ethyl-enedioxythiophene), to OPVs to precisely tailor the direct current electric field conditions during the culturing of PC12 cells. This NIR light-driven OPV/OBEI system could be engineered to provide tunable control over the electric field (from 220 to 980 mV mm(-1)) to promote 64% enhancement in the neurite length, direct the neurite orientation on chips, or both. The OPV/OBEI integrated systems under NIR illumination appear to function as effective power delivery platforms that should meet the requirements for wirelessly offering medical ES to a portion of the nervous system; they might also be a key technology for the development of next-generation implantable bioelectronics.
Synthesis and Luminescence Properties of Novel Ce3+- and Eu2+-Doped Lanthanum Bromothiosilicate La3Br(SiS4)(2) Phosphors for White LEDs
(2016-04-13)
Lee, Szu-Ping
;
Liu, Shuang-De
;
Chan, Ting-Shan
;
Chen, Teng-Ming
;
應用化學系
Novel Ce3+- and Eu2+-doped lanthanum bromothiosilicate La3Br(SiS4)(2):Ce3+ and La3Br(SiS4)(2):Eu2+ phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)(2):Ce3+ phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)(2):Eu2+ phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)(2):Ce3+ and La3Br(SiS4)(2):Eu2+ phosphors from 20 to 200 degrees C were investigated. The combination of a 450 nm blue InGaN-based LED chip with the red-emitting La3Br(SiS4)(2):Eu2+ phosphor, and green-emitting BOSE:Eu2+ commercial phosphor produced a warm-white light with the CRI value of similar to 95 and the CCT of 5,120 K. Overall, these results show that the prepared phosphors may have potential applications in pc-WLED.
清代數學家與經學家竟能鼎足而立
(國立交通大學丘成桐中心, 2016-04-15)
蘇俊鴻
從學術贊助看清代數學家專業與地位的提升
無窮小掀起大劇變
(國立交通大學丘成桐中心, 2016-04-15)
洪萬生
評論《無限小：一個危險的數學理論如何形塑現代世界》
LIGO 的重力波成就
(國立交通大學丘成桐中心, 2016-04-15)
郭兆林
基礎物理學除了探討物質與能量的本質之外，也非常關切空間與時間的問題。黑洞的視界（event horizon）可以說是空間的邊緣，而大霹靂則是時間的起點。由於不同的原因，重力波正好是研究這兩種現象的最佳利器，因此 CMB 的 B-模偏極、還有我上次在〈宇宙是怎麼來的？〉（《數理人文》第 4 期）介紹的 BICEP 實驗，常常和 LIGO 一起被提及。
STEM 時代中的數學觸角（下）
(國立交通大學丘成桐中心, 2016-04-15)
作者:美國工業與應用數學會（SIAM）
;
譯者:中華民國數學會與臺灣工業與應用數學會
從 18 項個案看數學在產業、科技、商業、醫學各方向的廣大應用
數學家如何提出可行的猜想
(國立交通大學丘成桐中心, 2016-04-15)
訪談者:梅哲（Barry Mazur）
;
譯者:趙學信
▲做數學要形成猜想，經常需要先採取可行性思考與啟發性方法釐清問題的樣貌，才能著手證明。 ▲可行性推論三種模式：從結果推理、從隨機性推理、從類比推理。 ▲作者以歐拉尚未證明的猜想與其他的例子，說明其中所牽涉到的可行性思考。
Generation of orthogonally polarized self-mode-locked Nd:YAG lasers with tunable beat frequencies from the thermally induced birefringence
(2016-04-15)
Sung, C. L.
;
Cheng, H. P.
;
Lee, C. Y.
;
Cho, C. Y.
;
Liang, H. C.
The simultaneous self-mode-locking of two orthogonally polarized states in a Nd:YAG laser is demonstrated by using a short linear cavity. A total output power of 3.8 W can be obtained at an incident pump power of 8.2 W. The beat frequency Delta f(c) between two orthogonally polarized mode-locked components is observed and measured precisely. It is found that the beat frequency increases linearly with an increase in the absorbed pump power. The origin of the beat frequency can be utterly manifested by considering the thermally induced birefringence in the Nd: YAG crystal. The present result offers a promising approach to generate orthogonally polarized mode-locked lasers with tunable beat frequency. (C) 2016 Optical Society of America
面對岔路，要毅然走進去
(國立交通大學丘成桐中心, 2016-04-15)
訪談者:勞森（Martin Raussen）．史考（Christian Skau）
;
譯者:周樹靜
2015 年阿貝爾獎得主尼倫伯格訪談
方程之術，即中等之法，何難之有？
(國立交通大學丘成桐中心, 2016-04-15)
洪萬生
;
英家銘
從朝鮮的中人技術官僚傳統看東亞算學的發展與交流
數理簡訊數學家族譜有什麼意思？用網絡科學一窺數學的歷史變遷
(國立交通大學丘成桐中心, 2016-04-15)
編輯室
上網搜尋過數學家資料的人想必都用過「數學系譜計畫」網站（Mathematics Genealogy Project，MGP）。網頁列出數學家國籍、博士學位年分、頒授學校、指導老師和學生，88%還有論文題目，43% 有 AMS 領域分類碼。目前 MGP 累積了將近 20 萬筆數學家資料，時間橫跨 14 世紀到現在。但是這個計畫堪稱極簡，除了告訴網友數學家最基本的資訊，偶爾帶來「X 原來是 Y 的學生！」的驚訝外，資訊似乎不多。
重力波終於現身！
(國立交通大學丘成桐中心, 2016-04-15)
作者:渥秋華（Natalie Wolchover）
;
譯者:戴守煌
愛因斯坦世紀前預測的時空漣漪，讓天文學進入嶄新的時代。
由考古發現看中國古代數學的演化（下）
(國立交通大學丘成桐中心, 2016-04-15)
作者:道本周（Joseph W. Dauben）
;
譯者:林倉億
從《數》、《筭數書》到《九章算術》
數理簡訊圍棋程式擊潰圍棋大師從AlphaGo 看類神經網路的浴火重生
(國立交通大學丘成桐中心, 2016-04-15)
編輯室
圍棋程式AlphaGo 這一天在分先（不讓子）的情況下，擊敗圍棋九段高手韓國李世乭，震憾了現場與網路直播的百萬觀眾，儼如大師的棋感更令人無法置信。沒想到之後 AlphaGo 再下兩城。以致於當李世乭在3 月13 日下贏第四盤、維護了人類尊嚴時，現場媒體竟然一片掌聲歡呼，激動莫名。戲劇化的情緒轉折，莫此為甚。