Browsing by Issue Date, starting with "2019-01-07"

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Exploring the ultrafast dynamics of a diarylethene derivative using sub-10 fs laser pulses
(2019-01-07)
Jarota, Arkadiusz
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Pastorczak, Ewa
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Tawfik, Walid
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Xue, Bing
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Kania, Rafal
A diarylethene derivative, 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene (DMP), is a photoswitch molecule utilizing a reversible aromatic ring-opening reaction. The quantum yield of the ring-opening reaction is however remarkably low. We investigate the origin of this behaviour by means of ultrafast transient absorption spectroscopy utilizing sub-10 fs pulses, which is an invaluable tool for simultaneously studying both the electronic and the vibrational molecular dynamics. Namely, a noncollinear optical parametric amplifier (NOPA) generating sub-10 fs pulses in the spectral range 605-750 nm is employed. The transient absorption signal is modulated by several vibrational modes, which are compared with experimental and computational Raman spectra and then assigned to the ground or excited electronic state. We observe that the most pronounced vibrational mode - the ethylenic stretching mode at a frequency of 1501 cm(-1) - exhibits instantaneous frequency and amplitude modulation. The observed modulations occur due to weak coupling with another 1431 cm(-1) stretching mode mediated by a vibrational mode of low frequency, i.e. around 60 cm(-1). Fast internal conversion S-1 S-0 originates in a relaxation through a conical intersection (found by density-functional theory computations), facilitated by the two aforementioned stretching modes.
Molecular design of near-infrared fluorescent Pdots for tumor targeting: aggregation-induced emission versus anti-aggregation-caused quenching
(2019-01-07)
Tsai, Wei-Kai
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Wang, Chun-I.
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Liao, Chia-Hsien
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Yao, Chun-Nien
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Kuo, Tsai-Jhen
Semiconducting polymer dots (Pdots) have recently emerged as a new type of ultrabright fluorescent probe that has been proved to be very useful for biomedical imaging. However, Pdots often suffer from serious fluorescence aggregation-caused quenching (ACQ) especially for near-infrared (NIR) fluorescent Pdots. This article compared two strategies to overcome the ACQ effect in near-infrared emissive Pdot systems: aggregation-induced emission (AIE) and anti-aggregation-caused quenching (anti-ACQ). The results show that the anti-ACQ platform outperforms the AIE system. The fluorescence quantum yield of anti-ACQ-based Pdots can be over 50% and the average per-particle brightness of the Pdots is about 5 times higher than that of the commercially available quantum dots. To help understand why the monomer conformations could greatly affect the optical properties of Pdots, molecular dynamics simulations were performed for the first time in such complicated Pdot systems. To demonstrate applications for in vivo fluorescence imaging, both microangiography imaging on living zebrafish embryos and specific tumor targeting on mice were performed. We anticipate that these studies will pave the way for the design of new highly fluorescent Pdot systems.
Stereoselective synthesis of a 9-O-sulfo Neu5Gc-capped O-linked oligosaccharide found on the sea urchin egg receptor
(2019-01-07)
Das, Anindya
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Li, Pei-Jhen
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Adak, Avijit K.
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Wu, Hsin-Ru
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Anwar, Mohammad Tarique
A straightforward synthesis of the (25)-linked 9-O-sulfated Neu5Gc-capped O-linked tetrasaccharide (1) identified in the egg cell surface glycoproteins of the sea urchin Strongylocentrotus purpuratus receptor for sperm is reported. The construction of the (25)Neu5Gc trimer by the formation of an amide linkage rather than a glycosidic bond avoids the requirement for -stereoselective glycosylation. To highlight this amide bond formation strategy as a relatively facile method for synthesizing oligo-Neu5Gc containing O-linked glycans, its versatility is demonstrated by application to the coupling of SO3H-9Neu5Gc(25)Neu5Gc glycolic acid and a sialyl-Tn-derived amine for achieving the target tetrasaccharide. This synthetic strategy may be implemented in the generation of other structurally similar O-sulfo Neu5Gc-capped 25-O-glycolyl-linked oligo-Neu5Gc chains, enabling additional biological and chemical investigations.
交大e-News第270期-國際無人駕駛船挑戰賽交通大學首度出賽獲佳績
(2019-01-07)
國立交通大學秘書室
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Secretariat
Liver X Receptor/Retinoid X Receptor Pathway Plays a Regulatory Role in Pacing-Induced Cardiomyopathy
(2019-01-08)
Lin, Yu-Sheng
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Chang, Tzu-Hao
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Shi, Chung-Sheng
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Wang, Yi-Zhen
;
Ho, Wan-Chun
Background-The molecular mechanisms through which high-demand pacing induce myocardial dysfunction remain unclear. Methods and Results-We created atrioventricular block in pigs using dependent right ventricular septal pacing for 6 months. Echocardiography was performed to evaluate dyssynchrony between pacing (n=6) and sham control (n=6) groups. Microarray and enrichment analyses were used to identify differentially expressed genes (DEGs) in the left ventricular (LV) myocardium between pacing and sham control groups. Histopathological and protein changes were also analyzed and an A cell pacing model was also performed. Pacing significantly increased mechanical dyssynchrony. Enrichment analysis using Ingenuity Pathway Analysis and the activation z-score analysis method demonstrated that there were 5 DEGs (ABCA1, APOD, CLU, LY96, and SERPINF1) in the LV septum (z-score=- 0.447) and 5 DEGs (APOD, CLU, LY96, MSR1, and SERPINF1) in the LV free wall (z-score=- 1.000) inhibited the liver X receptor/retinoid X receptor (LXR/RXR) pathway, and 4 DEGs (ACTA2, MYL1, PPP2R3A, and SNAI2) activated the integrin-linked kinase (ILK) pathway in the LV septum (z-score=1.000). The pacing group had a larger cell size, higher degree of myolysis and fibrosis, and increased expression of intracellular lipid, inflammatory cytokines, and apoptotic markers than the sham control group. The causal relationships between pacing and DEGs related to LXR/RXR and ILK pathways, apoptosis, fibrosis, and lipid expression after pacing were confirmed in the cell pacing model. Luciferase reporter assay in the cell pacing model also supported inhibition of the LXR pathway by pacing. Conclusions-Right ventricular septal-dependent pacing was associated with persistent LV dyssynchrony-induced cardiomyopathy through inhibition of the LXR/RXR pathway.
教育從小地方做起筆耕小書店
(國立交通大學傳播與科技學系, 2019-01-08)
蔡翔宇
筆耕小書店的成立與創辦人蔡文力現在的工作有關，他本身是友善書業合作社的成員，而筆耕小書店目前為友善書業合作社底下的獨立書店之一。筆耕小書店的二樓為筆耕寫作坊，主要提供給附近中小學生寫作課程，由蔡文力的太太擔任指導老師。
Energy Band Gap Modulation in Nd-Doped BiFeO3/SrRuO3 Heteroepitaxy for Visible Light Photoelectrochemical Activity
(2019-01-09)
Tan, Kok Hong
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Chen, Yun-Wen
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Chien Nguyen Van
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Wang, Hongliang
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Chen, Jhih-Wei
The ability of band offsets at multiferroic/metal and multiferroic/electrolyte interfaces in controlling charge transfer and thus altering the photoactivity performance has sparked significant attention in solar energy conversion applications. Here, we demonstrate that the band offsets of the two interfaces play the key role in determining charge transport direction in a downward self-polarized BFO film. Electrons tend to move to BFO/electrolyte interface for water reduction. Our experimental and first-principle calculations reveal that the presence of neodymium (Nd) dopants in BFO enhances the photoelectrochemical performance by reduction of the local electron hole pair recombination sites and modulation of the band gap to improve the visible light absorption. This opens a promising route to the heterostructure design by modulating the band gap to promote efficient charge transfer.
Porphyrin-Containing Polymer as a Superior Blue Light-Absorbing Additive To Afford High-J(sc) Ternary Solar Cells
(2019-01-09)
Li, Chia-Hua
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Chang, Chia-Chih
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Hsiao, Yu-Hsuan
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Peng, Shih-Hao
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Su, Yi-Jia
Integrating an additional component featuring complementary light absorption into binary polymer solar cells is a superior tactic to ameliorate solar cell efficiency and stability. An appropriate additive not only extends the absorption range but may also facilitate charge separation and transport processes. In this work, we elucidate the effects of incorporating a porphyrin-containing conjugated polymer (PPor-1), which displays absorption in 350-500 nm, into binary PTB7-Th:4TIC and PTB7-Th:ITIC blends, affording devices with an average power conversion efficiency approaching 9%. We successfully demonstrate that PPor-1 can be incorporated as an additive to impart improved J(sc) (up to 19.1 mA cm(-2)).
SDN-based dynamic multipath forwarding for inter-data center networking
(2019-01-10)
Wang, Yao-Chun
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Lin, Ying-Dar
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Chang, Guey-Yun
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資訊工程學系
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Department of Computer Science
Equal-cost multipath (ECMP)-based traffic engineering (TE) methods are commonly used in intra-data center (DC) networks to improve the transmission performance for east-west traffic (ie, traffic from server to server within a DC). However, applying ECMP on inter-DC wide area network (WAN) offers limited performance enhancement as a result of irregular network topology. Since TE can be intelligently and efficiently realized with software-defined networking (SDN), SDN-based multipath becomes a popular option. However, SDN suffers from scalability issue caused by limited ternary content-addressable memory (TCAM) size. In this paper, we propose an SDN-based TE method called dynamic flow-entry-saving multipath (DFSM) for inter-DC traffic forwarding. DFSM adopts source-destination-based multipath forwarding and latency-aware traffic splitting to reduce the consumption of flow entries and achieve load balancing. The evaluation results indicate that DFSM saves 15% to 30% of system flow entries in practical topologies and reduces the standard deviation of path latencies from 10% to 7% than do label-switched tunneling, and also reduces average latency by 10% to 48% by consuming 6% to 20% more flow entries than do ECMP in less-interconnected topologies. Note that the performance gain may not always be proportional to flow entry investment, with the interconnectivity between nodes being an important factor. The evaluation also indicates that per-flow provision consumes several times the flow entries consumed by DFSM but reduces latency by 10% at most. Besides, DFSM reduces the standard deviation of path latencies from 14% to 7% than do even traffic splitting.
A light-weight bit commitment protocol based on unpredictable channel noise
(2019-01-10)
Guan, Albert
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Tzeng, Wen-Guey
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資訊工程學系
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Department of Computer Science
Bit commitment is an important tool in the design of many secure cryptographic protocols, such as coin flipping, zero-knowledge proof, and secure computation. In this paper, we present a computationally light-weight bit commitment protocol over a noisy channel. For the security of the proposed protocol, we show that the receiver has almost no information about the committer's secret due to unpredictability of the noises in the communication channel. Hence, the security of our bit commitment protocol does not depend on hard problems; it is information-theoretically secure. Furthermore, the protocol needs only exclusive-or operations. Thus, it is computationally light-weight, and it can be used in the devices whose computing resources are limited. (C) 2018 Elsevier B.V. All rights reserved.
The evaluation of a better intubation strategy when only the epiglottis is visible: a randomized, cross-over mannequin study
(2019-01-10)
Hung, Tzu-Yao
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Lin, Li-Wei
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Yeh, Yu-Hang
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Su, Yung-Cheng
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Lin, Chieh-Hung
BackgroundThe Cormack-Lehane (C-L) grade III airway is considered to be a challenging airway to intubate and is associated with a poor intubation success rate. The purpose of this study was to investigate whether the holding position, shapes, bend angles of the endotracheal tube (ET) and the stylet-assisted lifting of the epiglottis could improve the success rate of intubation.MethodsThirty-two participants, 26 physicians, 2 residents, and 4 nurse practitioners, with 12.095.38years of work experience in the emergency department and more than 150 annual intubation events, were enrolled in this randomized, cross-over mannequin study. We investigated the effects of straight-to-cuff ET shapes with 35 degrees and 50 degrees bend angles, banana-shaped ET with longitudinal distances of 28cm and 26cm, two methods of holding the ET (either on the top or in the middle), and lifting or not the epiglottis, on the intubation duration, its success rate, and its subjective difficulty. The aim of the study is to provide optimized intubation strategies for difficult airway with C-L IIb or III grades, when the inlet of the trachea cannot be visualized.ResultsThe two groups that lifted the epiglottis using the stylets, in bend angles of 35 degrees and 50 degrees, had the shortest duration of intubation (23.7514.24s and 20.72 +/- 6.90s, hazard ratios 1.54 and 1.85 with 95% confidence intervals [95% CI] of 1.01-2.34 and 1.23-2.78, respectively) and a 100% success rate in intubations. In the survival analysis, lifting of the epiglottis was the only significant factor (p<0.0001, 95% CI 1.34-2.11) associated with the success rate of intubation.ConclusionsThe use of the epiglottic lift as an adjunctive technique can facilitate the intubation and improve its success rate without increasing procedure difficulty, in C-L III airway, when only the epiglottis is seen.Trial registration ClinicalTrials Registry (https://clincaltrials.gov, identifier NCT03366311).
Mimicking surface polaritons for unpolarized light with high-permittivity materials
(2019-01-10)
Papadakis, Georgia T.
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Davoyan, Artur
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Yeh, Pochi
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Atwater, Harry A.
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光電工程學系
Tailoring near-field optical phenomena often requires excitation of surface plasmon polaritons (SPPs) or surface phonon polaritons (SPhPs), surface waves at the interface between media with electric permittivities of opposite sign. Despite their unprecedented field confinement, surface polaritons are limited by polarization: only transverse magnetic fields enable their excitation, leaving transverse electric fields unexploited. By contrast, guided modes in positive permittivity materials occur for both linear polarizations, however, they typically cannot compete with SPPs and SPhPs in terms of confinement. Here we show that omnipolarization guided modes in materials with high-permittivity resonances can reach confinement factors similar to SPPs and SPhPs, while surpassing them in terms of propagation distance. We explore the cases of silicon carbide and transition-metal dichalcogenides near their permittivity resonances, and compare with SPhPs in silicon carbide and SPPs in silver, at infrared and visible frequencies, respectively.
Renal chymase-dependent pathway for angiotensin II formation mediated acute kidney injury in a mouse model of aristolochic acid I-induced acute nephropathy
(2019-01-11)
Hsieh, Wen-Yeh
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Chang, Teng-Hsiang
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Chang, Hui-Fang
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Chuang, Wan-Hsuan
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Lu, Li-Che
Angiotensin-converting enzyme (ACE) is the primary enzyme that converts angiotensin I (Ang I) to angiotensin II (Ang II) in the renin-angiotensin system (RAS). However, chymase hydrates Ang I to Ang II independently of ACE in some kidney diseases, and it may play an important role. The present study investigated whether chymase played a crucial role in aristolochic acid I (AAI)-induced nephropathy. C57BL/6 mice were treated with AAI via intraperitoneal injection for an accumulated AAI dosage of 45 mg/kg body weight (BW) (15 mg/kg BW per day for 3 days). The animals were sacrificed after acute kidney injury development, and blood, urine and kidneys were harvested for biochemical and molecular assays. Mice exhibited increased serum creatinine, BUN and urinary protein after the AAI challenge. Significant infiltrating inflammatory cells and tubular atrophy were observed in the kidneys, and high immunocytokine levels were detected. Renal RAS-related enzyme activities were measured, and a significantly increased chymase activity and slightly decreased ACE activity were observed in the AAI-treated mice. The renal Ang II level reflected the altered profile of RAS enzymes and was significantly increased in AAI-treated mice. Treatment of AAI-induced nephropathic mice with an ACE inhibitor (ACEI) or chymase inhibitor (CI; chymostatin) reduced renal Ang II levels. The combination of ACEI and CI (ACEI+CI) treatment significantly reversed the AAI-induced changes of Ang II levels and kidney inflammation and injuries. AAI treatment significantly increased renal p-MEK without increasing p-STAT3 and p-Smad3 levels, and p-MEK/p-ERK1/2 signalling pathway was significantly activated. CI and ACEI+CI treatments reduced this AAI-activated signaling pathway. AAI-induced nephropathy progression was significantly mitigated with CI and ACEI+CI treatment. This study elucidates the role of RAS in the pathogenesis of AAI-induced nephropathy.
Regio- and stereo-selective [4+4] photodimerization of angular-shaped dialkyltetracenedithiophene
(2019-01-11)
Hsu, Tze-Gang
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Chou, Hsiao-Chieh
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Liang, Ming-Ju
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Lai, Yu-Ying
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Cheng, Yen-Ju
Angular-shaped dialkyltetracenedithiophenes (aTDTs) undergo [4+4] photodimerization in solution to form a butterfly-shaped skeleton. This reaction proceeds in a regio- and stereo-selective manner, forming only a single planosymmetric syn-[2,2]-daTDT out of six possible products. The photocycloaddition of aTDTs can take place topochemically in the thin-film state while maintaining regio- and stereo-selectivity. Stronger aliphatic dispersion forces and - interactions play important roles in forming the eclipsed dimeric complex that leads to the syn-[2,2]-daTDT isomer.
A numerical study on reaction-induced radial fingering instability
(2019-01-11)
Sharma, Vandita
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Pramanik, Satyajit
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Chen, Ching-Yao
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Mishra, Manoranjan
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機械工程學系
The dynamics of A + B -> C fronts is analysed numerically in a radial geometry. We are interested to understand miscible fingering instabilities when the simple chemical reaction changes the viscosity of the fluid locally and a non-monotonic viscosity profile with a global maximum or minimum is formed. We consider viscosity-matched reactants A and B generating a product C having different viscosity than the reactants. Depending on the effect of C on the viscosity relative to the reactants, different viscous fingering (VF) patterns are captured which are in good qualitative agreement with the existing radial experiments. We have found that, for a given chemical reaction rate, an unfavourable viscosity contrast is not always sufficient to trigger the instability. For every fixed Peclet number (Pe), these effects of chemical reaction on VF are summarized in the Damkohler number (Da) - the log-mobility ratio (R-c) parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing Pe, we determine Da-dependent critical log-mobility ratios R-c(+) and R-c(-) such that no VF is observable whenever R-c(-) <= R-c <= R-c(+). The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.
Finite-size scaling for four-dimensional Higgs-Yukawa model near the Gaussian fixed point
(2019-01-14)
Chu, David Y. -J.
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Jansen, Karl
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Knippschild, Bastian
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Lin, C. -J. David
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電子物理學系
We analyse finite-size scaling behaviour of a four-dimensional Higgs-Yukawa model near the Gaussian infrared fixed point. Through improving the mean-field scaling laws by solving one-loop renormalisation group equations, the triviality property of this model can be manifested in the volume-dependence of moments of the scalar-field zero mode. The scaling formulae for the moments are derived in this work with the inclusion of the leading-logarithmic corrections. To test these formulae, we confront them with data from lattice simulations in a simpler model, namely the O(4) pure scalar theory, and find numerical evidence of good agreement. Our results of the finite-size scaling can in principle be employed to establish triviality of Higgs-Yukawa models, or to search for alternative scenarios in studying their fixed-point structure, if sufficiently large lattices can be reached.
最小曲面的黃金年代：柯丁/米尼庫齊理論
(國立交通大學丘成桐中心, 2019-01-15)
裴瑞茲
;
王夏聲
;
Joaquín Pérez
作者裴瑞茲是西班牙格蘭納達大學的數學與拓樸學教授與數學研究所（IEMath-GR）的主任。該研究所是屬於西班牙國家研究委員會所設的四個數學研究所其中之一。他也是西班牙皇家數學學會的國際關係委員會的一員。歷史上許多偉大的數學家都曾面對過最小曲面問題的挑戰，其中有一些數學家在相對確定的時期內獲得了驚人的進展，而促成了最小曲面的黃金年代。
大型線性方程組解法
(國立交通大學丘成桐中心, 2019-01-15)
許進超
．如何找線性代數方程組的解？這在數學與應用中是一個非常基本的問題，作者在本文討論求解的數值方法。．從最古老的高斯消去法到現代的多層網格法，作者在文中演示如何以數學技術研發大規模線性方程組的有效方法。．作者也有對於電腦硬體的開發與數學演算法的開發之間作出比較與探討。
解決物理難題的數學大師：我熟識的丘成桐先生
(國立交通大學丘成桐中心, 2019-01-15)
薛其坤
著者簡介:薛其坤是國際著名的實驗物理學家，現在是北京清華大學副校長，物理學教授，中國科學院院士。他的主要研究方向為量子物理。2013年他所帶領的團隊與合作者首次從實驗上發現量子反常霍爾效應，被2016年諾貝爾物理獎評獎委員會列入該領域過去三十年最重要的實驗發現。丘成桐先生是馳名中外的數學家，哈佛大學終身教授，國際數學最高獎「費爾茲獎」得主。我們都知道丘先生少年成名，標準的「學霸」一枚。22歲博士畢業，25 歲任副教授，27 歲攻克世界數學難題「卡拉比猜想」，34 歲獲得費爾茲獎。他幾乎拿遍了世界級的數學大獎，並已成為受人尊重的華人數學家領袖。
Growth of foreign-catalyst-free vertical InAs/InSb heterostructure nanowires on Si (111) substrate by MOCVD
(2019-01-15)
Anandan, Deepak
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Kakkerla, Ramesh Kumar
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Yu, Hung Wei
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Ko, Hua Lun
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Nagarajan, Venkatesan
In this study, growth of Au-free InAs/InSb vertical heterostructure (HS) nanowires (NWs) on highly lattice mismatched Si (1 1 1) substrate by metal organic chemical vapor deposition (MOCVD) is demonstrated. Careful selections of InSb growth parameters lead to In-rich growth regime such that direct impingement of growth precursors on top of grown InAs NW (self-assembled) stems result in axial InSb HSs nucleation on InAs stems. The observed indium (In) droplet on InSb HS NW tip shows that InSb HS growth followed a self-catalyzed growth mechanism. InSb HS axial growth rate and morphology are controlled by growth temperature and growth time. A small change in the growth parameters significantly affects In particle accumulation, particle size and its chemical composition, and thus affects the InSb nucleation on the stem. Especially, it is found that (i) growth time of less 10 min yields vertical InSb HS NW on the top of the InAs stem, (ii) as the growth time increases above 10 min, the growth turned to be InSb wrapped InAs/InSb core-shell HS due to coaxial lateral growth. High resolution transmission electron microscopy (HRTEM) study reveals that all the InSb HSs exhibit pure zinc-blende (ZB) crystal structure. The results presented here provide significant guidelines for external catalyst-free InAs/InSb HS NW growth using MOCVD on silicon (Si) substrate for various optoelectronics and electronics applications.