Browsing by Issue Date, starting with "2017-08-21"

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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
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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.
MANUFACTURING, UTILIZATION, AND ANTIFOULING COATING OF HYDROXYL-COVERED SILICON QUANTUM DOT NANOPARTICLE
(2017-08-24)
CHANG-CHING TU
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KUANG-PO CHEN
;
YAW-KUEN LI
A hydroxyl-covered silicon quantum dot nanoparticle having a silicon core, a plurality of silicon quantum dots, and a plurality of hydrocarbon chains is illustrated. A first portion of a surface associated with the silicon core is passivated by a plurality of silicon hydroxyl groups (Si—OH). The silicon quantum dots are attached to a second portion of the surface associated with the silicon core. The hydrocarbon chains are bonded to each of the silicon quantum dots through a plurality of silicon carbide bonds (Si—C), wherein each termination of the hydrocarbon chains has a carbon hydroxyl group (C—OH), such that the hydroxyl-covered silicon quantum dot nanoparticle is thoroughly covered by the carbon hydroxyl groups (C—OH) and the silicon hydroxyl groups (Si—OH).
Direct Reprogramming of Human Suspension Cells into Mesodermal Cell Lineages via Combined Magnetic Targeting and Photothermal Stimulation by Magnetic Graphene Oxide Complexes
(2017-08-25)
Chiang, Min-Yu
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Lin, Yi-Zhen
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Chang, Shwu-Jen
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Shyu, Woei-Cherng
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Lu, Huai-En
Suspension cells can provide a source of cells for cellular reprogramming, but they are difficult to transfect by nonviral vectors. An efficient and safe nonviral vector (GO-Fe3O4-PEI complexes) based on iron oxide nanoparticle (Fe3O4)-decorated graphene oxide (GO) complexed with polyethylenimine (PEI) for the first time is developed for delivering three individual episomal plasmids (pCXLE-hOCT3/4-shp53, pCXLE-hSK, and pCXLE-hUL) encoding pluripotent-related factors of Oct3/4, shRNA against p53, Sox2, Klf4, L-Myc, and Lin28 into human peripheral blood mononuclear cells (PBMCs) simultaneously. The combined treatment of magnetic stirring and near-infrared (NIR)-laser irradiation, which can promote contact between the complexes and floating cells and increase the cell membrane permeability, respectively, is used to conduct multiple physical stimulations for suspension PBMCs transfection. The PCR analysis shows that the combinatorial effect of magnetic targeting and photothermal stimulation obviously promoted the transfection efficiency of suspension cells. The transfected cells show positive expression of the pluripotency markers, including Nanog, Oct4, and Sox2, and have potential to differentiate into mesoderm and ectoderm cells. The results demonstrate that the GO-Fe3O4-PEI complex provides a safe, convenient, and efficient tool for reprogramming PBMCs into partially induced pluripotent stem cells, which are able to rapidly transdifferentiate into mesodermal lineages without full reprogramming.
Synthesis of multicomponent asymmetric star-branched polymers by iterative methodology with new diblock copolymer in-chain anions as building blocks
(2017-08-25)
Goseki, Raita
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Ito, Shotaro
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Hirao, Akira
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應用化學系
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Department of Applied Chemistry
New AB diblock copolymer in-chain anions having poly(2-vinylpyridine) (P2VP) and/or poly(methyl methacrylate) (PMMA) blocks, whose anion is located at the junction between the A and B blocks, have been prepared by the 1:1 addition reaction of the living polymer (A) with the omega- or alpha-terminal 1-phenyl1-( 2-pyridinyl) ethylene-functionalized polymer (B). The P2VP-block-PS, PS-block-P2VP, P2VP-blockpoly( 4-tert-butyldimethylsilyloxystyrene), PS-block-PMMA, and P2VP-block-PMMA in-chain anions could be practically prepared for the first time. Based on this preparation, a newly synthesized 1,4-bis(1-(2pyridinyl) ethenyl) benzene satisfactorily works as a key core agent, with which the polymers (A) can be connected to the polymer (B), and the in-chain anion can be generated between the A and B polymers. By developing the iterative methodology with such new block copolymer in-chain anions as the building blocks, the successive synthesis of the 3-arm ABC and 5-arm ABCDE mu-star polymers having PMMA and P2VP arms, which were synthetically difficult by the previous systems, have been successfully achieved. The success of the developed methodology demonstrates the further possibility to synthesize more component mu-star polymers. (C) 2017 Elsevier Ltd. All rights reserved.
DDX3 localizes to the centrosome and prevents multipolar mitosis by epigenetically and translationally modulating p53 expression
(2017-08-25)
Chen, Wei-Ju
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Wang, Wei-Ting
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Tsai, Tsung-Yuan
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Li, Hao-Kang
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Lee, Yan-Hwa Wu
The DEAD-box RNA helicase DDX3 plays divergent roles in tumorigenesis, however, its function in mitosis is unclear. Immunofluorescence indicated that DDX3 localized to centrosome throughout the cell cycle and colocalized with centrosome-associated p53 during mitosis in HCT116 and U2OS cells. DDX3 depletion promoted chromosome misalignment, segregation defects and multipolar mitosis, eventually leading to G2/M delay and cell death. DDX3 prevented multipolar mitosis by inactivation and coalescence of supernumerary centrosomes. DDX3 silencing suppressed Ser(15) phosphorylation of p53 which is required for p53 centrosomal localization. Additionally, knockout of p53 dramatically diminished the association of DDX3 with centrosome, which was rescued by overexpression of the centrosomal targeting-defective p53 S15A mutant, indicating that centrosomal localization of DDX3 is p53 dependent but not through centrosomal location of p53. Furthermore, DDX3 knockdown suppressed p53 transcription through activation of DNA methyltransferases (DNMTs) along with hypermethylation of p53 promoter and promoting the binding of repressive histone marks to p53 promoter. Moreover, DDX3 modulated p53 mRNA translation. Taken together, our study suggests that DDX3 regulates epigenetic transcriptional and translational activation of p53 and colocalizes with p53 at centrosome during mitosis to ensure proper mitotic progression and genome stability, which supports the tumor-suppressive role of DDX3.
Exciton-polariton Josephson junctions at finite temperatures
(2017-08-25)
Lebedev, M. E.
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Dolinina, D. A.
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Hong, Kuo-Bin
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Lu, Tien-Chang
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Kavokin, A. V.
We consider finite temperature effects in a non-standard Bose-Hubbard model for an exciton-polariton Josephson junction (JJ) that is characterised by complicated potential energy landscapes (PEL) consisting of sets of barriers and wells. We show that the transition between thermal activation (classical) and tunneling (quantum) regimes exhibits universal features of the first and second order phase transition (PT) depending on the PEL for two polariton condensates that might be described as transition from the thermal to the quantum annealing regime. In the presence of dissipation the relative phase of two condensates exhibits non-equilibrium PT from the quantum regime characterized by efficient tunneling of polaritons to the regime of permanent Josephson or Rabi oscillations, where the tunneling is suppressed, respectively. This analysis paves the way for the application of coupled polariton condensates for the realisation of a quantum annealing algorithm in presently experimentally accessible semiconductor microcavities possessing high (105 and more) Q-factors.
Controlled self-assemblies of polystyrene-block-polydimethylsiloxane micelles in cylindrical confinement through a micelle solution wetting method and Rayleigh-instability-driven transformation
(2017-08-28)
Ko, Hao-Wen
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Higuchi, Takeshi
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Chang, Chun-Wei
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Cheng, Ming-Hsiang
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Isono, Komei
Block copolymer micelles have been extensively discussed for many decades because of their applications, such as lithography and drug delivery. However, controlling the morphologies of nanostructure assembly using block copolymer micelles as building elements remains a great challenge. In this work, we developed a novel route to induce micelle assembly in confined geometries. Polystyrene-block-polydimethylsiloxane (PS-b-PDMS) micelle solutions were used to prepare micelle nanostructures, and the critical parameters affecting the morphologies were determined. Micelle nanorods, micelle nanospheres, and multi-component nanopeapods were prepared by wetting anodic aluminum oxide (AAO) templates with micelle solutions. Rayleigh-instability-driven transformation was discovered to play an important role in controlling the morphologies of the micelle nanostructures. This study not only proposes a versatile approach to preparing block copolymer micelle nanostructures, but it also provides deeper insight into the controlling factors of block copolymer micelle morphologies in cylindrical confinement.
Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement
(2017-08-28)
Li, Jung-Yu
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Chen, Shih-Pu
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Siao, Huei-Jhen
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Wu, Jin-Han
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Chen, Guan-Yu
In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m(2), which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity. Published by AIP Publishing.
AC stress and electronic effects on SET switching of HfO2 RRAM
(2017-08-28)
Liu, Jen-Chieh
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Magyari-Kope, Blanka
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Qin, Shengjun
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Zheng, Xin
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Wong, H. -S. Philip
An AC stress test was performed to investigate the accompanying electronic effects in a HfO2 resistive random access memory during the SET transition, which featured a sudden decrease in resistance. Comparing the DC and AC measurement results indicated the pronounced influence of interrupted stress on both the mean values and variations of time to SET. First-principles calculations suggested that the charge states (+2, +1, or neutral) of oxygen vacancies affect the migration barrier for forming oxygen vacancy clusters. Therefore, a charge-state-dependent SET model is proposed to include the additional electronic effects induced by the dynamics of electron trapping and detrapping in oxygen vacancies during AC stress. A trimodal Weibull fitting based on the proposed model reproduced the experimental time to SET distributions obtained in a wide range of AC stress conditions. Published by AIP Publishing.
Gate tunable spin-orbit coupling and weak antilocalization effect in an epitaxial La2/3Sr1/3MnO3 thin film
(2017-08-28)
Chiu, Shao-Pin
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Yamanouchi, Michihiko
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Oyamada, Tatsuro
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Ohta, Hiromichi
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Lin, Juhn-Jong
Epitaxial La2/3Sr1/3MnO3 (LSMO) films have been grown on SrTiO3 (001) substrates via pulsed laser deposition. In a 22-nm-thick LSMO film with a low residual resistivity of rho(0) approximate to 59 mu Omega cm, we found a zero-field dip in the magnetoresistance (MR) below 10 K, manifesting the weak antilocalization (WAL) effect due to strong spin-orbit coupling (SOC). We have analyzed the MR data by including the D'yakonov-Perel' spin-relaxation mechanism in the WAL theory. We explain that the delocalized spin-down electron sub-band states play a crucial role for facilitating marked SOC in clean LSMO. Moreover, we find that the SOC strength and gate voltage tunability are similar to those in a two-dimensional electron gas at the LaAlO3/SrTiO3 interface, indicating the presence of an internal electric field near the LSMO/SrTiO3 interface. In a control measurement on a 5-nm-thick high resistivity (rho(0) approximate to 280 mu Omega cm) LSMO film, we observe only a small zero-field peak in MR from weak localization effect, indicating negligible SOC.
Hyperscaling violating black hole solutions and magneto-thermoelectric DC conductivities in holography
(2017-08-28)
Ge, Xian-Hui
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Tian, Yu
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Wu, Shang-Yu
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Wu, Shao-Feng
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電子物理學系
We derive new black hole solutions in Einstein-Maxwell-axion-dilaton theory with a hyperscaling violation exponent. We then examine the corresponding anomalous transport exhibited by cuprate strange metals in the normal phase of high-temperature superconductors via gauge-gravity duality. Linear-temperature-dependence resistivity and quadratic-temperature-dependence inverse Hall angle can be achieved. In the high-temperature regime, the heat conductivity and Hall Lorenz ratio are proportional to the temperature. The Nernst signal first increases as temperature goes up, but it then decreases with increasing temperature in the high-temperature regime.
Co-delivery of paclitaxel and cetuximab by nanodiamond enhances mitotic catastrophe and tumor inhibition
(2017-08-29)
Lin, Yu-Wei
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Raj, Emmanuel Naveen
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Liao, Wei-Siang
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Lin, Johnson
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Liu, Kuang-Kai
The poor intracellular uptake and non-specific binding of anticancer drugs into cancer cells are the bottlenecks in cancer therapy. Nanocarrier platforms provide the opportunities to improve the drug efficacy. Here we show a carbon-based nanomaterial nanodiamond (ND) that carried paclitaxel (PTX), a microtubule inhibitor, and cetuximab (Cet), a specific monoclonal antibody against epidermal growth factor receptor (EGFR), inducing mitotic catastrophe and tumor inhibition in human colorectal cancer (CRC). ND-PTX blocked the mitotic progression, chromosomal separation, and induced apoptosis in the CRC cells; however, NDs did not induce these effects. Conjugation of ND-PTX with Cet (ND-PTX-Cet) was specifically binding to the EGFR-positive CRC cells and enhanced the mitotic catastrophe and apoptosis induction. Besides, ND-PTX-Cet markedly decreased tumor size in the xenograft EGFR-expressed human CRC tumors of nude mice. Moreover, ND-PTX-Cet induced the mitotic marker protein phospho-histone 3 (Ser10) and apoptotic protein active-caspase 3 for mitotic catastrophe and apoptosis. Taken together, this study demonstrated that the co-delivery of PTX and Cet by ND enhanced the effects of mitotic catastrophe and apoptosis in vitro and in vivo, which may be applied in the human CRC therapy.