Browsing by Issue Date, starting with "2017-08-17"

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Real-time observation of interfragment vibration and charge transfer within the TCNQF(4) dimer
(2017-08-17)
Hashimoto, Sena
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Yabushita, Atsushi
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Iwakura, Izumi
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電子物理學系
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Department of Electrophysics
The organic electron acceptors, 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF(4)); are widely used to synthesize multivalent charge-transfer complexes. Their corresponding radical anion complexes have specific electronic, optical, and magnetic characters that have attracted attention in the field of materials development. In the present work,, we have performed time-resolved absorption spectroscopy of the (Na+)(2)(TCNQE(4)(center dot-))(2) radical anion complex to elucidate the reaction dynamics ([TCNQF(4)(center dot-)](2) -> TCNQF(4) + TCNQF(4)(2-)). A visible sub-10 fs laser pulse was used to observe the ultrafast dynamics of the charge transfer and real-time change of the molecular structure during the reaction. Unlike our previous work on the (Na+)(2)(TCNQ(.-))(2) radical anion complex, the interfragment vibrational mode was clearly observed for (Na+)(2)(TCNQP(4)(center dot-))(2). The difference in the intermolecular interaction is considered to reflect the difference in the pi-pi interaction and/or the difference in the flexibility of the molecular plane predicted by theoretical calculations. (C) 2017 Elsevier B.V. All rights reserved.
Andreev reflection in two-dimensional relativistic materials with realistic tunneling transparency in normal-metal/superconductor junctions
(2017-08-17)
Chang, Yung-Yeh
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Mou, Chung-Yu
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Chung, Chung-Hou
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電子物理學系
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Department of Electrophysics
The Andreev conductance across realistic two-dimensional (2D) normal-metal (N)/superconductor (SC) junctions with a relativistic Dirac spectrum is theoretically investigated within the Blonder-Tinkham-Klapwijk formalism with tunable tunneling transparency. It is known that due to the effect of Klein tunneling, impurity potentials at the interface of 2D relativistic materials will enhance (not suppress) the tunneling and therefore are not suitable to model a realistic tunnel junction of these materials. Here, we propose a way to construct a more realistic tunnel junction by adding a narrow, homogeneous local strain, which effectively generates a delta-gauge potential and variations of electron hopping at the interface, to adjust the transparency of the N/SC junction. Remarkable suppression of the Andreev conductance is indeed observed in the graphene N/SC junction as the strength of the local strain increases. We also explore the Andreev conductance in a topological N/SC junction at the two inequivalent Dirac points and predict the distinctive behaviors for the conductance across the chiral-to-helical topological phase transition. The relevance of our results for the adatom-doped graphene is discussed.
Musashi-1 Enhances Glioblastoma Cell Migration and Cytoskeletal Dynamics through Translational Inhibition of Tensin3
(2017-08-18)
Chen, Hsiao-Yun
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Lin, Liang-Ting
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Wang, Mong-Lien
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Laurent, Benoit
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Hsu, Chih-Hung
The RNA-binding protein Musashi-1 (MSI1) exerts essential roles in multiple cellular functions, such as maintenance of self-renewal and pluripotency of stem cells. MSI1 overexpression has been observed in several tumor tissues, including glioblastoma (GBM), and is considered as a well-established marker for tumor metastasis and recurrence. However, the molecular mechanisms by which MSI1 regulates cell migration are still undetermined. Here we reported that MSI1 alters cell morphology, promotes cell migration, and increases viscoelasticity of GBM cells. We also found that MSI1 directly binds to the 3'UTR of Tensin 3 (TNS3) mRNA, a negative regulator of cell migration, to inhibit its translation. Additionally, we identified that RhoA-GTP could be a potential regulator in MSI1/TNS3-mediated cell migration and morphological changes. In a xenograft animal model, high expression ratio of MSI1 to TNS3 enhanced GBM tumor migration. We also confirmed that MSI1 and TNS3 expressions are mutually exclusive in migratory tumor lesions, and GBM patients with MSI1(high)/TNS3(low) pattern tend to have poor clinical outcome. Taken together, our findings suggested a critical role of MSI1-TNS3 axis in regulating GBM migration and highlighted that the ratio of MSI1/TNS3 could predict metastatic and survival outcome of GBM patients.
Reactivity of carbonaceous nanocomposites for water purification and recovery applications
(2017-08-20)
Doong, Ruey-An
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環境工程研究所
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Institute of Environmental Engineering
Synthesis of biscalix[4]arene derivatives and their applications in molecular sensing and organogel materials
(2017-08-20)
Chung, Wen-Sheng
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交大名義發表
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National Chiao Tung University
Preparation and application of biochar for the removal of H2O2 from semiconductor wastewater
(2017-08-20)
Cheng, Hsiao-Fen
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Huang, Chihpin
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Guo, Cuixiang
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Huang, Chin-Pao
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環境工程研究所
Influences of polymorphism and low-angle grain boundary on OFET performances
(2017-08-20)
Wang, Chien-Lung
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Wu, Kuan-Yi
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Hsieh, Chou-Ting
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應用化學系
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Department of Applied Chemistry
Reduction of hydrogen peroxide over biochar surface in acidic solution
(2017-08-20)
Guo, Cuixiang
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Fan, Rui Mei
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Cheng, Hsiao-Fen
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Tzeng, Jing Hua
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Huang, Chihpin
Production and infrared spectra of hydrogenated free radicals and protonated species important in interstellar media
(2017-08-20)
Lee, Yuan-Pern
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Tsuge, Masashi
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Haupa, Karolina
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應用化學系
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Department of Applied Chemistry
Influences of out-of-plane lattice alignment on the OFET performance of TIPS-PEN crystal arrays
(2017-08-20)
Wu, Kuan-Yi
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Wang, Chien-Lung
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應用化學系
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Department of Applied Chemistry
Insights into linear supramolecular polymer formation via TPE and BODIPY containing host-guest interaction
(2017-08-20)
Gouda, Chinmayananda
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材料科學與工程學系
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Department of Materials Science and Engineering
交大e-News第238期-為世大運游泳選手張芳語同學加油
(2017-08-21)
國立交通大學秘書室
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Secretariat
Infrared spectra and anharmonic coupling of proton-bound nitrogen dimers N-2-H+-N-2, N-2-D+-N-2, and N-15(2)-H+-N-15(2) in solid para-hydrogen
(2017-08-21)
Liao, Hsin-Yi
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Tsuge, Masashi
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Tan, Jake A.
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Kuo, Jer-Lai
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Lee, Yuan-Pern
The proton-bound nitrogen dimer, N-2-H+-N-2, and its isotopologues were investigated by means of vibrational spectroscopy. These species were produced upon electron bombardment of mixtures of N-2 (or N-15(2)) and para-hydrogen (p-H-2) or normal-D-2 (n-D-2) during deposition at 3.2 K. Reduced-dimension anharmonic vibrational Schrodinger equations were constructed to account for the strong anharmonic effects in these protonated species. The fundamental lines of proton motions in N-2-H+-N-2 were observed at 715.0 (NH+N antisymmetric stretch, nu(4)), 1129.6 (NH+N bend, nu(6)), and 2352.7 (antisymmetric NN/NN stretch, nu(3)) cm(-1), in agreement with values of 763, 1144, and 2423 cm(-1) predicted with anharmonic calculations using the discrete-variable representation (DVR) method at the CCSD/aug-cc-pVDZ level. The lines at 1030.2 and 1395.5 cm(-1) were assigned to combination bands involving n nu(2) + n4 (n = 1 and 2) according to theoretical calculations; nu(2) is the N-2 ... N-2 stretching mode. For N-15(2)-H+-N-15(2) in solid p-H-2, the corresponding major lines were observed at 710.0 (nu(4)), 1016.7 (nu(2) + nu(4)), 1124.3 (nu(6)), 1384.8 (2 nu(2) + nu(4)), and 2274.9 (nu(3)) cm(-1). For N-2-D+-N-2 in solid n-D-2, the corresponding major lines were observed at 494.0 (nu(4)), 840.7 (nu(2) + nu(4)), 825.5 (nu(6)), and 2356.2 (nu(3)) cm(-1). In addition, two lines at 762.0 (weak) and 808.3 cm(-1) were tentatively assigned to be some modes of N-2-H+-N-2 perturbed or activated by a third N-2 near the proton.
A TDDFT study on the excited-state double proton transfer reaction of 8-hydroxyquinoline along a hydrogen-bonded bridge
(2017-08-21)
Liu, Yu-Hui
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Wang, Shi-Ming
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Zhu, Chaoyuan
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Lin, Sheng Hsien
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應用化學系
The mechanism of the excited-state double proton transfer (ESDPT) reactions of 8-hydroxyquinoline (8HQ) along three types of hydrogen-bonded bridges-ammonia (NH3), water (H2O) and acetic acid (AcOH) has been investigated by using time-dependent density functional theory. Based on the analysis of hydrogen bond strengths and the excited-state potential energy surfaces (PES) along the proton transfer coordinates, it is concluded that the hydrogen bonds play the key role in the excited-state multiple proton transfer reaction. Moreover, three different concerted mechanisms have been found in 8HQ center dot NH3, 8HQ center dot H2O and 8HQ center dot AcOH complexes. Upon photoexcitation, the deprotonation of a hydroxyl group in 8HQ would occur first in 8HQ center dot NH3 due to the stronger hydrogen bond -OH center dot center dot center dot NH3. On the contrary, the hydrogen bond -OH center dot center dot center dot O-C-OH is much weaker in the 8HQ center dot AcOH complex, and this leads to a fast protonation of -N- in the 8HQ moiety. For the 8HQ center dot H2O complex, the hydrogen bond strengths are almost the same, so that both protons would transfer simultaneously in a symmetrical and concerted fashion.
Origins of Kerr phase and orientational phase in polymer-dispersed liquid crystals
(2017-08-21)
Chang, Chia-Ming
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Lin, Yi-Hsin
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Reshetnyak, Victor
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Park, Chui Ho
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Manda, Ramesh
Polymer-dispersed liquid crystals (PDLCs) modulate the amplitude and optical phase of light. The optical phase modulation of PDLC can be dissected into two parts: Kerr phase and orientational phase according to the electro-optical (EO) response. We investigated the origins of the Kerr and orientational phases in PDLCs and their connection with the two-step EO response. The Kerr phase is attributed to LC orientation in the center of LC droplets. The orientational phase results from orientation of LC molecules near LC-polymer interfaces. Both phases can be adjusted by varying the droplet size. The two-step EO response in small droplets (<333 nm) is related to the Kerr and orientational phases, and possibly to rotation of point defects. A modified PDLC model considering the Kerr and orientational phases is proposed. Our findings suggest the possibility of versatile photonic devices using pure optical phase modulation. (C) 2017 Optical Society of America
Optimization of nano-honeycomb structures for flexible w-LEDs
(2017-08-21)
Lin, Huang-Yu
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Pai, Yung-Min
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Shi, Jing-xing
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Chen, Xin-Yin
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Lin, Chung-Hsiang
This study presents the low cost fabrication of flexible white-light-emitting diodes (w-LEDs) with nano-honeycomb-structured phosphor films. Extending the dimensions of the nano-honeycomb structures improved the color uniformity of the flexible samples, and the 950-nm pattern sample demonstrated optimal color uniformity because this nano-pattern exhibited an excellent diffusion ability owing to its pitch size. In addition to color uniformity, the use of this nano-pattern improved the luminous efficiency. The 750-nm pattern exhibited the highest luminous efficiency (235.8 lm/W), which was approximately 7% higher than that exhibited by a non-patterned phosphor film sample. Thus, flexible w-LEDs with nano-honeycomb structure optimization have great potential to be used as next-generation lighting sources. (C) 2017 Optical Society of America
Femtosecond-Laser-Enhanced Amyloid Fibril Formation of Insulin
(2017-08-22)
Liu, Tsung-Han
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Yuyama, Ken-ichi
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Hiramatsu, Takato
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Yamamoto, Naoki
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Chatani, Eri
Femtosecond (fs)-laser-induced crystallization as a novel crystallization technique was proposed for the first time by our group, where the crystallization time can be significantly shortened under fs laser irradiation. Similarly, we have further extended our investigation to amyloid fibril formation, also known as a nucleation-dependence process. Here we demonstrate that the necessary time for amyloid fibril formation can be signifiCantly shortened by fs laser irradiation, leading to favorable enhancement. The enhancement was confirmed by both spectral measurements and direct observations of amyloid fibrils. The thioflavin T fluorescence intensity of laser-irradiated solution increased earlier than that of the control solution, and such a difference was simultaneously revealed by ellipticity changes. At the same time before intensity Saturation in fluorescence, the number of amykid fibrils obtained under laser irradiation was generally mote than that in the control. Solution. Besides, such an enhancement is correlated to the laser power threshold of cavitation bubbling. Possible mechanisms are proposed by referring to fs-laser-induced crystallization and ultrasonication-induced amyloid fibril formation.
Electrically sign-reversible transverse g-factors of holes in droplet epitaxial GaAs/AlGaAs quantum dots under uniaxial stress
(2017-08-23)
Wu, Yu-Nien
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Wu, Ming-Fan
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Ou, Ya-Wen
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Chou, Ying-Lin
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Cheng, Shun-Jen
We present a theoretical investigation of anisotropic g-factor tensors of single holes confined in droplet epitaxial GaAs/AlGaAs quantum dots under electrical and mechanical controls using the gauge-invariant discretization method within the framework of four-band Luttinger-Kohn (k) over right arrow.(p) over right arrow theory. We reveal an intrinsic obstacle to realize the electrical sign reversal of the hole g-factors, being a key condition required for a full spin control in the scheme of g-tensor modulation, for the quantum dots solely with electrical bias control. Constructively, our studies show that, besides electrical gating, slightly stressing an inherently unstrained droplet epitaxial GaAs/AlGaAs quantum dot can offset the transverse hole g-factor to be nearly zero and make the electrical sign reversal of the hole g-factors feasible.
METHOD FOR PARAMETER EXTRACTION OF A SEMICONDUCTOR DEVICE
(2017-08-24)
Jyh-Chyurn GUO
;
Yen-Ying LIN
A method is provided for parameter extraction of a semiconductor device with a multi-finger gate. The method includes measuring gate-to-source and gate-to-drain capacitances and performing 3D simulation to compute fringing capacitances, thereby computing an overlap capacitance between the gate and a source/drain extension region, and computing a length of the source/drain extension region according to the overlap capacitance.
Sulfur-Doped Graphene Oxide Quantum Dots as Photocatalysts for Hydrogen Generation in the Aqueous Phase
(2017-08-24)
Gliniak, Jacek
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Lin, Jia-Hoa
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Chen, Yi-Ting
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Li, Chuen-Ru
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Jokar, Efat
Sulfur-doped graphene oxide quantum dots (S-GOQDs) were synthesized and investigated for efficient photocatalytic hydrogen generation application. The UV/Vis, FTIR, and photoluminescence spectra of the synthesized S-GOQDs exhibit three absorption bands at 333, 395, and 524 nm, characteristic of C=S and C=S stretching vibration signals at 1075 and 690 cm(-1), and two excitation-wavelength-independent emission signals with maxima at 451 and 520 nm, respectively, confirming the successful doping of S atom into the GOQDs. Electronic structural analysis suggested that the S-GOQDs exhibit conduction band minimum (CBM) and valence band maximum (VBM) levels suitable for water splitting. Under direct sunlight irradiation, an initial rate of 18166 mu molh(-1) g(-1) in pure water and 30519 mu molh(-1) g(-1) in 80% ethanol aqueous solution were obtained. Therefore, metal-free and inexpensive S-GOQDs hold great potential in the development of sustainable and environmentally friendly photocatalysts for efficient hydrogen generation from water splitting.