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

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Infrared absorption of t-HOCO+, H+(CO2)(2), and HCO2- produced in electron bombardment of CO2 in solid para-H-2
(2016-07-07)
Das, Prasanta
;
Tsuge, Masashi
;
Lee, Yuan-Pern
;
應用化學系
;
應用化學系分子科學碩博班
We have employed electron bombardment during matrix deposition of CO2 (or (CO2)-C-13, (CO2)-O-18) and para-hydrogen (p-H-2) at 3.2 K and recorded infrared (IR) spectra of t-HOCO+, H+(CO2)(2) , HCO2-, CO2-, t-HOCO, and other species isolated in solid p-H-2. After the matrix was maintained in darkness for 13 h, intensities of absorption features of t-HOCO+ at 2403.5 (v(1)), 2369.9 (v(2)), 1018.1 (v(4)), and 606.5 (v(6)) cm(-1) and those of H+(CO2)(2) at 1341.1, 883.6, and 591.5 cm(-1) decreased. Corresponding lines of isotopologues were observed when (CO2)-C-13 or (CO2)-O-18 replaced CO2. In contrast, lines of HCO2- at 2522.4 (v(1)), 1616.1 (v(5)), 1327.9 (v(2)), and 745.6 (v(3)) cm(-1) increased in intensity; corresponding lines of (HCO2-)-C-13 or (HCO2-)-O-18 were also observed. Lines of t-DOCO+ and DCO2- were observed in an electron bombarded CO2/normal-deuterium (n-D-2) matrix. Data of v(6) of t-HOCO+ and all observed modes of (HOCO+)-O-18-O-18 and (HCO2-)-O-18 are new. The assignments were made according to expected chemical behavior, observed isotopic shifts, and comparisons with vibrational wavenumbers and relative intensities of previous reports and calculations with the B3PW91/aug-cc-pVQZ method. The v(1) line of t-HOCO+ in solid p-H-2 (2403.5 cm(-1)), similar to the line at 2673 cm(-1) of t-HOCO+ tagged with an Ar atom, is significantly red-shifted from that reported for gaseous t-HOCO+ (3375.37 cm(-1)) due to partial proton sharing between CO2 and H-2 or Ar. The v(1) line of HCO2- in solid p-H-2 (2522.4 cm(-1)) is blue shifted from that reported for HCO2- in solid Ne (2455.7 cm(-1)) and that of HCO2- tagged with Ar (2449 cm(-1)); this can be explained by the varied solvation effects by Ne, Ar, or H-2 on the mixing of H+ + CO2 and H+ CO2- surfaces. Possible formation mechanisms of t-HOCO+, H+(CO2)(2), HCO2-, CO2-, t-HOCO, H2O, and t-HCOOH are discussed. Published by AIP Publishing.
Ultrafast dynamics of uracil and thymine studied using a sub-10 fs deep ultraviolet laser
(2016-07-07)
Xue, Bing
;
Yabushita, Atsushi
;
Kobayashi, Takayoshi
;
電子物理學系
;
Department of Electrophysics
Single 9.6 fs deep ultraviolet pulses with a spectral range of 255-290 nm are generated by a chirpedpulse four-wave mixing technique for use as pump and probe pulses. The electronic excited state and vibrational dynamics are simultaneously observed for an aqueous solution of uracil and thymine over the full spectral range using a 128-channel lock-in amplifier detector. Two probe photon energy-dependent lifetimes gradually increasing with the probe photon energy are obtained from the decay dynamics data. Ultrafast decay dynamics through the conical intersection is assigned from the first excited pi pi* to the final ground state involving the n pi* states. Vibrational modes of the electronic ground state and excited states can be observed, which are strongly coupled to the decay dynamics of the electronic excited state.
Simultaneous Observation of an Intraband Transition and Distinct Transient Species in the Infrared Region for Perovskite Solar Cells
(2016-07-07)
Narra, Sudhakar
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Chung, Chih-Chun
;
Diau, Eric Wei-Guang
;
Shigeto, Shinsuke
;
應用化學系
Solar cells based on organometal-halide perovskites such as CH3NH3PbI3 have emerged as a promising next generation photovoltaic system, but the underlying photo physics and photochemistry remain to be established because of the limited availability of methods to implement the simultaneous and direct measurement of various charge carriers and ions that play a crucial role in the operating device. We used nanosecond time-resolved infrared (IR) spectroscopy to investigate, with high molecular specificity, distinct transient species that are formed in perovskite solar cells after photoexcitation. In CH3NH3PbI3 planar-heterojuction solar cells, we simultaneously observed infrared spectral signatures that are associated with an intraband transition of conduction-band electrons, Fano resonance, and the spiro-OMeTAD cation having an exceptionally short lifetime of 1.0 mu s (at similar to 4485 cm(-1)). The present results show that the time resolved IR method offers a unique capability to elucidate these important transients in perovskite solar cells and their dynamic interplay in a comprehensive manner.
iPARTS2: an improved tool for pairwise alignment of RNA tertiary structures, version 2
(2016-07-08)
Yang, Chung-Han
;
Shih, Cheng-Ting
;
Chen, Kun-Tze
;
Lee, Po-Han
;
Tsai, Ping-Han
Since its first release in 2010, iPARTS has become a valuable tool for globally or locally aligning two RNA 3D structures. It was implemented by a structural alphabet (SA)-based approach, which uses an SA of 23 letters to reduce RNA 3D structures into 1D sequences of SA letters and applies traditional sequence alignment to these SA-encoded sequences for determining their global or local similarity. In this version, we have re-implemented iPARTS into a new web server iPARTS2 by constructing a totally new SA, which consists of 92 elements with each carrying both information of base and backbone geometry for a representative nucleotide. This SA is significantly different from the one used in iPARTS, because the latter consists of only 23 elements with each carrying only the backbone geometry information of a representative nucleotide. Our experimental results have shown that iPARTS2 outperforms its previous version iPARTS and also achieves better accuracy than other popular tools, such as SARA, SETTER and RASS, in RNA alignment quality and function prediction. iPARTS2 takes as input two RNA 3D structures in the PDB format and outputs their global or local alignments with graphical display. iPARTS2 is now available online at http://genome.cs.nthu.edu.tw/iPARTS2/.
Successful continuous-flow left ventricular assist device implantation with adjuvant tricuspid valve repair for advanced heart failure
(2016-07-08)
Lee, Chih-Hsien
;
Wei, Jeng
;
生物科技學系
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Department of Biological Science and Technology
The prevalence of end-stage heart failure (HF) is on the increase, however, the availability of donor hearts remains limited. Left ventricular assist devices (LVADs) are increasingly being used for treating patients with end-stage HF. LVADs are not only used as a bridge to transplantation but also as a destination therapy. HeartMate II, a new-generation, continuous-flow LVAD (cf-LVAD), is currently an established treatment option for patients with HF. Technological progress and increasing implantation of cf-LVADs have significantly improved survival in patients with end-stage HF. Here we report a case of a patient with end-stage HF who was successfully supported using cf-LVAD implantation with adjuvant tricuspid valve repair in a general district hospital.
Ultrafast dynamics of ligand and substrate interaction in endothelial nitric oxide synthase under Soret excitation
(2016-07-08)
Hung, Chih-Chang
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Yabushita, Atsushi
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Kobayashi, Takayoshi
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Chen, Pei-Feng
;
Liang, Keng S.
Ultrafast transient absorption spectroscopy of endothelial NOS oxygenase domain (eNOS-oxy) was performed to study dynamics of ligand or substrate interaction under Soret band excitation. Photo-excitation dissociates imidazole ligand in <300 fs, then followed by vibrational cooling and recombination within 2 ps. Such impulsive bond breaking and late rebinding generate proteinquakes, which relaxes in several tens of picoseconds. The photo excited dynamics of eNOS-oxy with L-arginine substrate mainly occurs at the local site of heme, including ultrafast internal conversion within 400 fs, vibrational cooling, charge transfer, and complete ground-state recovery within 1.4 ps. The eNOS-oxy without additive is partially bound with water molecule, thus its photoexcited dynamics also shows ligand dissociation in <800 fs. Then it followed by vibrational cooling coupled with charge transfer in 4.8 ps, and recombination of ligand to distal side of heme in 12 ps. (C) 2016 Elsevier B.V. All rights reserved.
EFFECT OF SIZE AND STRETCH OF A MOVING FERROFLUID DROP ON INDUCED ELECTROMOTIVE FORCE
(2016-07-09)
Chen, Ching-Yao
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Wang, Sheng-Yan
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Wen, Chih-Yung
;
Jan, Cheng-Shiung
;
機械工程學系
Application for obtaining useful global features, e.g. the size and stretch of a moving ferrofluid drop by analyzing the characteristics of the induced electromotive force signal is demonstrated. These features are highly relevant to two maximum magnitudes in the electromotive force signal, e.g., the positive (V-1) and the negative (V-2) peak respectively induced when the drop enters and leaves the region covered by the induction coil. Favorable induction conditions of these two maximum magnitudes are opposite. In general, V-1 increases with the size of the ferrofluid drop because of stronger magnetization. On the contrary, V-2 is more prominent for a smaller drop, whose stretch is less significant. As a result, the ratio of vertical bar V-1/V-2 vertical bar monotonically increases with the, size of the ferrofluid drop. This finding suggests that the induced EMF signal can be used as a useful tool for quantifying the flow conditions, such as the size and stretch of moving ferrofluids.
Imagining Garage Start-Ups: Interactive Effects of Imaginative Capacities on Entrepreneurial Intention
(2016-07-09)
Chang, Chi-Cheng
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Yao, Shu-Nung
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Chen, Shi-An
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King, Jung-Tai
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Liang, Chaoyun
This article describes a structural examination of the interaction among different imaginative capacities and the entrepreneurial intention of electrical and computer engineering students. Two studies were combined to confirm the factor structure of survey items and test the hypothesised interaction model. The results indicated that imaginative capacity has 3 dimensions: conceiving, initiating, and transforming, whereas entrepreneurial intention comprises 2 factors: conviction and preparation. In addition, the results indicated that initiating imagination strongly affected entrepreneurial conviction and preparation; conceiving imagination positively predicted entrepreneurial conviction, whereas transforming imagination negatively predicted entrepreneurial preparation. The results also indicated that students possessing high, as well as those possessing low, conceiving and transforming imaginations demonstrated a high level of entrepreneurial preparation. In addition, an increase in transforming imagination increases the preparation of students possessing low initiating imagination and reduces the preparation of students possessing high initiating imagination. For developing a novel approach to conduct research on entrepreneurial intention and for discussing the practical implications of the findings, this study explicates alternative methods of cultivating students, promoting their interests, and enabling entrepreneurial behaviour in them by stimulating their imaginative capacities.
Stability of Einstein static state universe in the spatially flat branemodels
(2016-07-10)
Zhang, Kaituo
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Wu, Puxun
;
Yu, Hongwei
;
Luo, Ling-Wei
;
物理研究所
With the assumption that a perfect fluid with a constant equation of state is the only energy component on the brane, we study the stability of Einstein static state solution under homogeneous and inhomogeneous scalar perturbations in both spatially flat Randall-Sundrum (RS) and Shtanov-Sahni (SS) braneworlds. We find that if the perfect fluid has a phantom-like property and the "Weyl fluid" originating from the projection of the bulk Weyl tensor onto the brane behaves like a radiation with positive energy density, the Einstein static state solution is stable in the SS braneworld, but unstable in the RS one. Furthermore, we demonstrate that the static state solution is also stable in the bulk with a timelike extra dimension. Thus, in the model where the extra dimension is timelike, our universe can stay at the Einstein static state past-eternally, which means that the big bang singularity might be resolved successfully by an emergent scenario. (C) 2016 The Authors. Published by Elsevier B.V.
THE INFRARED SPECTRUM OF PROTONATED OVALENE IN SOLID PARA-HYDROGEN AND ITS POSSIBLE CONTRIBUTION TO INTERSTELLAR UNIDENTIFIED INFRARED EMISSION
(2016-07-10)
Tsuge, Masashi
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Bahou, Mohammed
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Wu, Yu-Jong
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Allamandola, Louis
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Lee, Yuan-Pern
The mid-infrared emission from galactic objects, including reflection nebulae, planetary nebulae, proto-planetary nebulae, molecular clouds, etc, as well as external galaxies, is dominated by the unidentified infrared (UIR) emission bands. Large protonated polycyclic aromatic hydrocarbons (H(+)PAHs) were proposed as possible carriers, but no spectrum of an H(+)PAH has been shown to exactly match the UIR bands. Here, we report the IR spectrum of protonated ovalene (7-C32H15+) measured in a para-hydrogen (p-H-2) matrix at 3.2 K, generated by bombarding a mixture of ovalene and p-H-2 with electrons during matrix deposition. Spectral assignments were made based on the expected chemistry and on the spectra simulated with the wavenumbers and infrared intensities predicted with the B3PW91/6-311++G(2d, 2p) method. The close resemblance of the observed spectral pattern to that of the UIR bands suggests that protonated ovalene may contribute to the UIR emission, particularly from objects that emit Class A spectra, such as the IRIS reflection nebula, NGC 7023.
A penetrating atherosclerotic ulcer rupture in the ascending aorta with hemopericardium: a case report
(2016-07-11)
Liu, Yuan-Hao
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Ke, Hung-Yen
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Lin, Yi-Chang
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Tsai, Chien-Sung
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生物科技學系
Background: Acute aortic syndrome, including classic aortic dissection, intramural aortic hematoma, and penetrating atherosclerotic ulcer (PAU), is a term used to describe a group of conditions with similar clinical symptoms, but with different pathophysiological mechanisms. PAU is a lesion that penetrates the internal elastic lamina through the media. It is usually located in the descending aorta and rarely observed in the ascending aorta. Case presentation: A 76-year-old man with a history of essential hypertension was brought to the emergency department (ED) because of a sudden-onset chest pain at rest. He had not been taking his medication as ordered. His vital signs in the ED were a blood pressure of 82/60 mmHg, heart rate of 158 beats per min, respiratory rate of 22 breaths per min, and a body temperature of 37.2 degrees C. An electrocardiogram did not show an ST segment elevation, and cardiac enzymes were within normal limits. No widening mediastinum was found on chest radiography, but a large pericardial effusion with an impending cardiac tamponade was revealed on echocardiography. The diagnosis of PAU rupture in the ascending aorta with hemopericardium was made with chest computed tomography. An emergent sternotomy and ascending aorta reconstruction were performed. A ruptured ulcerative plaque through the intima to the adventitia without flap dissection in the ascending aorta was confirmed. The patient was discharged 18 days after the operation. Conclusions: Although PAU in the ascending aorta is uncommon, it is commonly lethal when it ruptures. With the current advances in endovascular techniques and devices, endovascular repair of PAU in the ascending aorta is currently recommended only for high-risk patients unsuitable for open repair. However, we anticipate that endovascular repair may become feasible in patients with PAU in the ascending aorta in the future.
Superconductivity in the two-dimensional electron gas induced by high-energy optical phonon mode and large polarization of the SrTiO3 substrate
(2016-07-11)
Rosenstein, Baruch
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Shapiro, B. Ya.
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Shapiro, I.
;
Li, Dingping
;
電子物理學系
Pairing in one-atomic-layer-thick two-dimensional electron gas (2DEG) by a single flat band of high-energy longitudinal optical phonons is considered. The polar dielectric SrTiO3 (STO) exhibits such an energetic phonon mode and the 2DEG is created both when one unit cell FeSe layer is grown on its (100) surface and on the interface with another dielectric like LaAlO3 (LAO). We obtain a quantitative description of both systems solving the gap equation for T-c for arbitrary Fermi energy is an element of(F), electron-phonon coupling lambda, and the phonon frequency Omega, and direct (random-phase approximation) electron-electron repulsion strength alpha. The focus is on the intermediate region between the adiabatic, is an element of(F) >> Omega, and the nonadiabatic, is an element of(F) << Omega, regimes. The high-temperature superconductivity in single-unit-cell FeSe/STO is possible due to a combination of three factors: high-longitudinal-optical phonon frequency, large electron-phonon coupling lambda similar to 0.5, and huge dielectric constant of the substrate suppression the Coulomb repulsion. It is shown that very low density electron gas in the interfaces is still capable of generating superconductivity of the order of 0.1 K in LAO/STO.
A Quantitative Method to Data Reuse Patterns of SIMT Applications
(2016-07-12)
Lai, Bo-Cheng Charles
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Platero, Luis Garrido
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Kuo, Hsien-Kai
;
電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Understanding data reuse patterns of a computing system is crucial to effective design optimization. The emerging Single Instruction Multiple Threads (SIMT) processor adopts a programming model that is fundamentally disparate from conventional scalar processors. There is a lack of analytical approaches to quantify the data reuse of SIMT applications. This paper presents a quantitative method to study the data reuse inherent to SIMT applications. A metric, Data Reuse Degree, is defined to measure the amount of reused data between memory references, and associate each data reuse degree to a temporal distance representing the virtual time of the execution process. The experiments are performed on an abstracted SIMT processor that considers the programming model and runtime specifics. The experiments illustrate diverse data reuse patterns of SIMT applications and explore the impacts of architectural limitations.
Optical Properties of Plasmonic Mirror-Image Nanoepsilon
(2016-07-12)
Lin, Jia-Yu
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Tsai, Chia-Yang
;
Lin, Pin-Tso
;
Hsu, Tse-En
;
Hsiao, Chi-Fan
We propose a novel mirror-image nanoepsilon (MINE) structure to achieve highly localized and enhanced near field at its gap and systematically investigate its plasmonic behaviors. The MINE can be regarded as a combination of two fundamental plasmonic nanostructures: a nanorod dimer and nanoring. By adapting a nanoring surrounding a nanorod dimer structure, the nanorod is regarded as a bridge pulling the charges from the nanoring to the nanorod, which induces stronger plasmon coupling in the gap to boost local near-field enhancement. Two resonance peaks are identified as the symmetric and anti-symmetric modes according to the symmetries of the charge distributions on the ring and rod dimer in the MINE. The symmetric mode in the MINE structure is preferred because its charge distribution leads to stronger near-field enhancement with a concentrated distribution around the gap. In addition, we investigate the influence of geometry on the optical properties of MINE structures by performing experiments and simulations. These results indicate that the MINE possesses highly tunable optical properties and that significant near-field enhancement at the gap region and rod tips can be realized by the gap and lightning-rod effects. The results improve understanding of such complex systems, and it is expected to guide and facilitate the design of optimum MINE structures for various plasmonic applications.
Tunable complex magnetic states of epitaxial core-shell metal oxide nanocrystals fabricated by the phase decomposition method
(2016-07-13)
Chang, S. J.
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Lam, T. N.
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Yang, C. Y.
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Chen, Y. L.
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Chu, Y. H.
We report on the successful fabrication of epitaxial-discrete CoxFe3-xO4/CoO magnetic nanostructures on a SrTiO3 substrate as well as the results of a thorough investigation of the magnetic cross-reactions of the two phases in the vicinity of the epitaxial junction. These nanostructures were originally prepared as Fe3O4-CoO core-shell structures through the phase decomposition of bismuth perovskite precursors by pulsed-laser deposition. An antiphase boundary emerged during the structural/electronic transition from the CoO core to the Co1-xFe2+XO4 shell; this then developed into a ferrimagnetic/antiferromagnetic interface. Uncompensated spins (UCS) arose from the CoxFe3-xO4/CoO interface as a result of strong ferrimagnetic-antiferromagnetic interactions. A notable exchange bias as well as a significant exchange enhancement was observed owing to the UCS, which had a locking effect because of the decoupling of the Co1-xFe2+XO4/CoO reversal from the antiphase boundary. Control of the precursor ratio allowed for the fine-tuning of the Co1-xFe2+XO4 phase and the associated locking behaviors. This, in turn, allowed the anisotropy and coercivity of the nanostructures to be manipulated. Thus, we were able to create and thoroughly understand a complex epitaxial configuration with tunable structural and magnetic properties. This study should open new opportunities with regard to current magnetic oxide technology, which requires novel methods for pursuing extremity of controllable properties over an atomic landscape.
Manifestations of Torsion-CH Stretch Coupling in the Infrared Spectrum of CH3OO
(2016-07-14)
Hsu, Kuo-Hsiang
;
Huang, Yu-Hsuan
;
Lee, Yuan-Pern
;
Huang, Meng
;
Miller, Terry A.
With a step-scan Fourier-transform spectrometer we recorded temporally resolved infrared absorption spectra of CH3OO radicals that were produced upon irradiation of CH3COCH3 and O-2 at 193 nm in a flowing mixture. At a resolution of 0.15 cm(-1), the rotational structure of the nu(2) band of CH3OO near 2954.4 cm(-1) is partially resolved and shows an unexpectedly broadened, and somewhat distorted, Q-branch. A 4D model Hamiltonian, consisting of three CH stretches and the methyl torsion, was developed to explore the origins of this broadening. The vibrational progressions predicted by the model Hamiltonian and the rotational contours of the nu(2) band, based on experimental ground-state rotational parameters and their values scaled by their calculated ratios for the upper state, produced simulations in satisfactory agreement with the observed spectrum. These results provide new inSight into the vibrational couplings in CH3OO.
Analysis of local bond-orientational order for liquid gallium at ambient pressure: Two types of cluster structures
(2016-07-14)
Chen, Lin-Yuan
;
Tang, Ping-Han
;
Wu, Ten-Ming
;
物理研究所
;
Institute of Physics
In terms of the local bond-orientational order ( LBOO) parameters, a cluster approach to analyze local structures of simple liquids was developed. In this approach, a cluster is defined as a combination of neighboring seeds having at least n(b) local-orientational bonds and their nearest neighbors, and a cluster ensemble is a collection of clusters with a specified n(b) and number of seeds n(s). This cluster analysis was applied to investigate the microscopic structures of liquid Ga at ambient pressure ( AP). The liquid structures studied were generated through ab initio molecular dynamics simulations. By scrutinizing the static structure factors ( SSFs) of cluster ensembles with different combinations of n(b) and n(s), we found that liquid Ga at AP contained two types of cluster structures, one characterized by sixfold orientational symmetry and the other showing fourfold orientational symmetry. The SSFs of cluster structures with sixfold orientational symmetry were akin to the SSF of a hard-sphere fluid. On the contrary, the SSFs of cluster structures showing fourfold orientational symmetry behaved similarly as the anomalous SSF of liquid Ga at AP, which is well known for exhibiting a high-q shoulder. The local structures of a highly LBOO cluster whose SSF displayed a high-q shoulder were found to be more similar to the structure of beta-Ga than those of other solid phases of Ga. More generally, the cluster structures showing fourfold orientational symmetry have an inclination to resemble more to beta-Ga. Published by AIP Publishing.
Vesicle electrohydrodynamic simulations by coupling immersed boundary and immersed interface method
(2016-07-15)
Hu, Wei-Fan
;
Lai, Ming-Chih
;
Seol, Yunchang
;
Young, Yuan-Nan
;
應用數學系
In this paper, we develop a coupled immersed boundary (IB) and immersed interface method (IIM) to simulate the electrodeformation and electrohydrodynamics of a vesicle in Navier-Stokes leaky dielectric fluids under a DC electric field. The vesicle membrane is modeled as an inextensible elastic interface with an electric capacitance and an electric conductance. Within the leaky dielectric framework and the piecewise constant electric properties in each fluid, the electric stress can be treated as an interfacial force so that both the membrane electric and mechanical forces can be formulated in a unified immersed boundary method. The electric potential and transmembrane potential are solved simultaneously via an efficient immersed interface method. The fluid variables in Navier-Stokes equations are solved using a projection method on a staggered MAC grid while the electric potential is solved at the cell center. A series of numerical tests have been carefully conducted to illustrate the accuracy and applicability of the present method to simulate vesicle electrohydrodynamics. In particular, we investigate the prolateoblate-prolate (POP) transition and the effect of electric field and shear flow on vesicle electrohydrodynamics. Our numerical results are in good agreement with those obtained in previous work using different numerical algorithms. (C) 2016 Elsevier Inc. All rights reserved.
學術界揭竿而起—楊芬瑩
(國立交通大學丘成桐中心, 2016-07-15)
楊芬瑩
推倒貪婪期刊付費高牆！
數理簡訊 PK 大戰與對局論
(國立交通大學丘成桐中心, 2016-07-15)
編輯室
零和賽局混合策略的精彩實例