Browsing by Issue Date, starting with "2019-01-17"

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UNMANNED AERIAL VEHICLE AND METHOD USING THE SAME
(2019-01-17)
Mau-Chung Frank CHANG
;
Chiun-Hsun CHEN
An unmanned aerial vehicle (UAV) includes a body, a plurality of rotated propulsion systems, and at least one air bag. The rotated propulsion systems are connected to the body and each includes a blade and an actuator configured to actuate the blade. The air bag is disposed on the body.
Exotic Mode Suppression in Plasmonic Heterotrimer System
(2019-01-17)
Song, Hanfa
;
Sun, Quan
;
Li, Jie
;
Yang, Fan
;
Yang, Jinghuan
We investigate the far- and near-field properties of plasmonic heterotrimers with small detuning of the eigenfrequency numerically, theoretically, and experimentally. In our simulations, we find that the dipolar mode of the middle nanorod in the trimer system is greatly suppressed in both far and near fields. This phenomenon is confirmed by our subsequent experiments. The far-field suppression can be interpreted by the destructive interference due to the antiphase dipolar response of the respective nanorod. To deeply understand the underlying physics, an analytical model considering both the near-field-mediated direct coupling and radiative-field-mediated indirect coupling is adopted. We determine that the radiative field coupling, which is stronger in the trimer system with a smaller detuning, plays an essential role in mode suppression in the near field. Our work will provide new thoughts on the fundamental mechanisms of plasmon coupling and plasmon-based applications.
Layer-Dependent Dielectric Function of Wafer-Scale 2D MoS2
(2019-01-18)
Song, Baokun
;
Gu, Honggang
;
Fang, Mingsheng
;
Chen, Xiuguo
;
Jiang, Hao
Wafer-scale, high-quality, and layer-controlled 2D MoS2 films on c-sapphire are synthesized by an innovative two-step method. The dielectric functions of MoS2 ranging from the monolayer to the bulk are investigated by spectroscopic ellipsometry over an ultra-broadband (0.73-6.42 eV). Up to five critical points (CPs) in the dielectric function spectra are precisely distinguished by CP analysis, and their physical origins are identified in the band structures with the help of first-principles calculations. Results demonstrate that the center energies of these CPs exhibit intriguing layer dependency, which are interpreted by the intrinsic layer-dependent transitions in MoS2. Specially, the change in the imaginary part of the dielectric functions versus the thickness exhibits a "W" like curve, and the two valley bottoms appear at about four-layer and 10-layer respectively. These complex fluctuations are attributed to the alternating domination of the decreasing excitonic effect, the increasing joint density of states, and the mass density increase in relative thick MoS2 samples.
Single-Step Per-O-Sulfonation of Sugar Oligomers with Concomitant 1,6-Anhydro Bridge Formation for Binding Fibroblast Growth Factors
(2019-01-18)
Yeh, Che-Jui
;
Ku, Chiao-Chu
;
Lin, Wei-Chen
;
Fan, Chiao-Yuan
;
Zulueta, Medel Manuel L.
Many circulating cancer-related proteins, such as fibroblast growth factors (FGFs), associate with glycosaminoglycans-particularly heparan sulfate-at the cell surface. Disaccharide analogues of heparan sulfate had previously been identified as the shortest components out of the sugars that bind to FGF-1 and FGF-2. Taking note of the typical pose of l-iduronic acid, we conceived of per-O-sulfonated analogues of such disaccharides, and devised a single-step procedure for per-O-sulfonation of unprotected sugars with concomitant 1,6-anhydro bridge formation to achieve such compounds through direct use of SO3Et3N as sulfonation reagent and dimethylformamide as solvent. The synthesized sugars based on the oligomaltose backbone bound FGF-1 and FGF-2 mostly at the sub-micromolar level, although the tetrasaccharide analogue achieved low-nanomolar binding with FGF-2.
Investigation of Cavity Enhanced XEOL of a Single ZnO Microrod by Using Multifunctional Hard X-ray Nanoprobe
(2019-01-18)
Lin, Bi-Hsuan
;
Li, Xiao-Yun
;
Lin, Dai-Jie
;
Jian, Bo-Lun
;
Hsu, Hsu-Cheng
The multifunctional hard X-ray nanoprobe at Taiwan Photon Source (TPS) exhibits the excellent ability to simultaneously characterize the X-ray absorption, X-ray excited optical luminescence (XEOL) as well as the dynamics of XEOL of materials. Combining the scanning electron microscope (SEM) into the TPS 23A end-station, we can easily and quickly measure the optical properties to map out the morphology of a ZnO microrod. A special phenomenon has been observed that the oscillations in the XEOL associated with the confinement of the optical photons in the single ZnO microrod shows dramatical increase while the X-ray excitation energy is set across the Zn K-edge. Besides having the nano-scale spatial resolution, the synchrotron source also gives a good temporal domain measurement to investigate the luminescence dynamic process. The decay lifetimes of different emission wavelengths and can be simultaneously obtained from the streak image. Besides, SEM can provide the cathodoluminescence (CL) to be a complementary method to analyze the emission properties of materials, we anticipate that the X-ray nanoprobe will open new avenues with great characterization ability for developing nano/microsized optoelectronic devices.
Diverse Synthesis of Natural Trehalosamines and Synthetic 1,1 '-Disaccharide Aminoglycosides
(2019-01-18)
Lu, Yen-Chu
;
Mondal, Soumik
;
Wang, Ching-Chi
;
Lin, Chun-Hung
;
Mong, Kwok-Kong Tony
A general strategy for the diverse synthesis of ten disaccharide aminoglycosides, including natural 2-trehalosamine (1), 3-trehalosamine (2), 4-trehalosamine (3), and neotrehalosyl 3,3 '-diamine (8) and synthetic aminoglycosides 4-7, 9, and 10, has been developed. The aminoglycoside compounds feature different anomeric configurations and numbers of amino groups. The key step for the synthesis was the glycosylation coupling of a stereodirecting donor with a configuration-stable TMS glycoside acceptor. Either the donor or acceptor could be substituted with an azido group. The aminoglycosides prepared in the present study were characterized by 1D and 2D NMR spectroscopy.
江山藝改所外在文青而內心狂放的藝術靈魂
(國立交通大學傳播與科技學系, 2019-01-19)
馮瑜庭
「江山藝改所」是一個複合式的獨立空間，結合咖啡廳、書店、唱片行、藝文展演空間和背包客棧。
Hybrid light field head-mounted display using time-multiplexed liquid crystal lens array for resolution enhancement
(2019-01-21)
Chou, Ping-Yen
;
Wu, Dui-Yi
;
Huang, Shang-Hao
;
Wang, Chun-Ping
;
Qin, Zong
In recent years, head-mounted display technologies have greatly advanced. In order to overcome the accommodation-convergence conflict, light field displays reconstruct three-dimensional (3D) images with a focusing cue but sacrifice resolution. In this paper, a hybrid head-mounted display system that is based on a liquid crystal microlens array is proposed. By using a time-multiplexed method, the display signals can be divided into light field and two-dimensional (2D) modes to show comfortable 3D images with high resolution compensated by the 2D image. According to the experimental results, the prototype supports a 12.28 ppd resolution in the diagonal direction, which reaches 82% of the traditional virtual reality (VR) head-mounted display (HMD). (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Charge transport mechanism of high-resistive state in RRAM based on SiOx
(2019-01-21)
Gismatulin, A. A.
;
Kruchinin, V. N.
;
Gritsenko, V. A.
;
Prosvirin, I. P.
;
Yen, T. -J.
Nonstoichiometric silicon oxide SiOx is a promising material for developing a new generation of high-speed, reliable flash memory based on the resistive effect. It is necessary to understand the electron transport mechanism of the high-resistive state in SiOx to develop a resistive memory element. At present, it is generally accepted that the charge transport of the high-resistive state in the Resistive Random Access Memory (RRAM) is described by the Frenkel effect. In our work, the charge transport of the high-resistive state in RRAM based on SiOx is analyzed with two contact-limited and five volume-limited charge transport models. It is established that the Schottky effect model, thermally assisted tunneling, the Frenkel model of Coulomb trap ionization, the Makram-Ebeid and Lannoo model of multiphonon isolated trap ionization, and the Nasyrov-Gritsenko model of phonon-assisted tunneling between traps, quantitatively, do not describe the charge transport of the high-resistive state in the RRAM based on SiOx. The Shklovskii-Efros percolation model gives a consistent explanation for the charge transport of the highresistive state in the RRAM based on SiOx at temperatures above room temperature. Published under license by AIP Publishing.
交大e-News第271期-本土人才國際化台灣首屆國際高教認證培訓落幕
(2019-01-21)
國立交通大學秘書室
;
Secretariat
Tunable topological semimetallic phases in Kondo lattice systems
(2019-01-22)
Lu, Yen-Wen
;
Chou, Po-Hao
;
Chung, Chung-Hou
;
Mou, Chung-Yu
;
電子物理學系
We exploit topological semimetallic phases resulting from the Kondo screening in Anderson lattice models. It is shown that by including spin-orbit interactions both in the bulk electrons and in the hybridization between the conduction electrons and electrons in the f orbit, all types of topological semimetallic phases can be realized in Anderson lattice models. Specifically, upon either broken time-reversal symmetry or broken inversion symmetry, we find that either the Weyl semimetallic phase, Dirac semimetallic phase, or nodal-ring semimetallic phases always emerge between insulating phases and can be accessed by tuning either temperature or spin-orbit interaction. For Anderson lattice models with general three-dimensional spin-orbit hybridization between the conduction electrons and electrons in the f orbit, we find that Weyl nodal-ring semimetallic phases emerge between strong and weak topological insulating phases. Furthermore, in the presence of an exchange field, Weyl semimetallic phases form after two Weyl points of charge +/- 1 split off from a Dirac point at time-reversal momenta. On the other hand, when the spin-orbit interaction is included in the conduction electron, we find that upon the rotation symmetry being broken with anisotropic hopping amplitudes, a Weyl semimetallic phase emerges with a double Weyl node with charges of +/- 2. Furthermore, the Weyl semimetallic phases with charges of +/- 2 can be tuned into Weyl semimetallic phases with charges of +/- 1 through the inclusion of the Rashba spin-orbit interaction. Our analyses indicate that Anderson lattices with appropriate spin-orbit interactions provide a platform for realizing all types of topological semimetallic phases.
TiO2 Nanowire-Supported Sulfide Hybrid Photocatalysts for Durable Solar Hydrogen Production
(2019-01-23)
Hsieh, Ping-Yen
;
Chiu, Yi-Hsuan
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Lai, Ting-Hsuan
;
Fang, Mei-Jing
;
Wang, Yu-Ting
As the feet of clay, photocorrosion induced by hole accumulation has placed serious limitations on the widespread deployment of sulfide nanostructures for photoelectrochemical (PEC) water splitting. Developing sufficiently stable electrodes to construct durable PEC systems is therefore the key to the realization of solar hydrogen production. Here, an innovative charge-transfer manipulation concept based on the aligned hole transport across the interface has been realized to enhance the photostability of In2S3 electrodes toward PEC solar hydrogen production. The concept was realized by conducting compact deposition of In2S3 nanocrystals on the TiO2 nanowire array. Under PEC operation, the supporting TiO2 nanowires functioned as an anisotropic charge-transfer backbone to arouse aligned charge transport across the TiO2-In2S3 interface. Because of the aligned hole transport, the TiO2 nanowire-supported In2S3 hybrid nanostructures (TiO2 In2S3) exhibited improved hole-transfer dynamics at the TiO2-In2S3 interface and enhanced hole injection kinetics at the electrode surface, substantially increasing the long-term photostability toward solar hydrogen production. The PEC durability tests showed that TiO2-In2S3 electrodes can achieve nearly 90.9% retention of initial photocurrent upon continuous irradiation for 6 h, whereas the pure In2S3 merely retained 20.8% of initial photocurrent. This double-gain charge-transfer manipulation concept is expected to convey a viable approach to the intelligent design of highly efficient and sufficiently stable sulfide photocatalysts for sustainable solar fuel generation.
Epitaxial Growth of Optically Thick, Single Crystalline Silver Films for Plasmonics
(2019-01-23)
Cheng, Fei
;
Lee, Chien-Ju
;
Choi, Junho
;
Wang, Chun-Yuan
;
Zhan, Qiang
Single crystalline Ag films on dielectric substrates have received tremendous attention recently due to their technological potentials as low loss plasmonic materials. Two different growth approaches have been used to produce single crystalline Ag films previously. One approach is based on repetitive cycles of a two-step process (low temperature deposition followed by RT annealing) using molecular beam epitaxy (MBE), which is extremely time-consuming due to the need for repeat growth cycles. Another approach is based on rapid e-beam deposition which is capable of growing thick single crystalline Ag films (>300 nm) but lacks the precision in thickness control of thin epitaxial films. Here, we report a universal approach to grow atomically smooth epitaxial Ag films by eliminating the repetitive cycles used in the previous two-step MBE method while maintaining the precise thickness control from a few monolayers to the optically thick regime, thus overcoming the limitations of the two aforementioned methods. In addition, we develop an in situ growth of aluminum oxide as the capping layer to protect the epitaxial Ag films. The quality of the epitaxial Ag films was evaluated using a variety of techniques, and the superior optical performance of the films is demonstrated by measuring the propagation length of surface plasmon polaritons (similar to 80 mu m at 632 nm) as well as their capability to support a plasmonic nanolaser in infrared incorporating an InGaAsP quantum well as the gain media.
Zr-MOF/Polyaniline Composite Films with Exceptional Seebeck Coefficient for Thermoelectric Material Applications
(2019-01-23)
Lin, Chih-Chien
;
Huang, Yi-Chia
;
Usman, Muhammad
;
Chao, Wen-Hsuan
;
Lin, Wei-Keng
Controlling the polymerization of aniline in the presence of zirconium-based metal-organic frameworks (Zr-MOFs) using polystyrene sulfonic acid as a dopant resulted in the formation of a new type of freestanding thermoelectric composite film. Polyaniline chains interpenetrate into the Zr-MOFs to enhance the crystallinity of polyaniline, resulting in an improved degree of electrical conductivity. In addition, the inherent porosity of the Zr-MOFs functions to suppress the increase in thermal conductivity, thus dramatically promoting a negative Seebeck coefficient. When 20 wt % Zr-MOF was used, a power factor of up to 664 mu W/(m K-2) was obtained, which was accompanied by a surprisingly large, negative Seebeck coefficient. The new class of MOF-based composites offers a new direction for developing new types of efficient thermoelectric materials.
Genome-wide transcriptome analysis to further understand neutrophil activation and lncRNA transcript profiles in Kawasaki disease
(2019-01-23)
Ko, Tai-Ming
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Chang, Jeng-Sheng
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Chen, Shih-Ping
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Liu, Yi-Min
;
Chang, Chia-Jung
Kawasaki disease (KD) is the most common cause of acquired cardiac disease in children in developed countries. However, little is known regarding the role of transcriptomic targets of KD in the disease progression and development of complications, especially coronary artery aneurysms (CAA). The aim of our study was to identify transcripts affected by KD and their potential role in the disease. We enrolled 37 KD patients and collected blood samples along a comprehensive time-course. mRNA profiling demonstrated an abundance of CD177 transcript in acute KD, and in the intravenous immunoglobulin (IVIG)-resistant group compared to in the IVIG-sensitive group. lncRNA profiling identified XLOC_006277 as the most highly expressed molecule. XLOC_006277 expression in patients at acute stage was 3.3-fold higher relative to patients with convalescent KD. Moreover, XLOC_006277 abundance increased significantly in patients with CAA. XLOC_006277 knockdown suppressed MMP-8 and MMP-9 expression, both associated with heart lesions. Our result suggested that the increase of CD177(pos) neutrophils was associated with KD. Moreover, this study provided global long non-coding RNA transcripts in the blood of patients with KD, IVIG-resistant KD, or CAA. Notably, XLOC_006277 abundance was associated with CAA, which might contribute to further understanding of CAA pathogenesis in KD.
Facet-Dependent Photocatalytic Behaviors of ZnS-Decorated Cu2O Polyhedra Arising from Tunable Interfacial Band Alignment
(2019-01-23)
Naresh, Gollapally
;
Hsieh, Pei-Lun
;
Meena, Vandana
;
Lee, Shih-Kuang
;
Chiu, Yi-Hsuan
ZnS particles were grown over Cu2O cubes, octahedra, and rhombic dodecahedra for examination of their facet-dependent photocatalytic behaviors. After ZnS growth, Cu2O cubes stay photocatalytically inactive. ZnS-decorated Cu2O octahedra show enhanced photocatalytic activity, resulting from better charge carrier separation upon photo excitation. Surprisingly, Cu2O rhombic dodecahedra give greatly suppressed photocatalytic activity after ZnS deposition. Electron paramagnetic resonance spectra agree with these experimental observations. Time-resolved photoluminescence profiles provide charge-transfer insights. The decrease in the photocatalytic activity is attributed to an unfavorable band alignment caused by significant band bending within the Cu2O(110)/ZnS(200) plane interface. A modified Cu2O-ZnS band diagram is presented. Density functional theory calculations generating plane -specific band energy diagrams of Cu2O and ZnS match well with the experimental results, showing that charge transfer across the Cu2O(110)/ZnS(200) plane interface would not happen. This example further illustrates that the actual photocatalysis outcome for semiconductor heterojunctions cannot be assumed because interfacial charge transfer is strongly facet-dependent.
Supercapacitive Properties of Micropore- and Mesopore-Rich Activated Carbon in Ionic-Liquid Electrolytes with Various Constituent Ions
(2019-01-24)
Quoc Dat Nguyen
;
Patra, Jagabandhu
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Hsieh, Chien-Te
;
Li, Jianlin
;
Dong, Quan-Feng
Ionic-liquid (IL) electrolytes, characterized by large potential windows, intrinsic ionic conductivity, low environmental hazard, and high safety, are used for micropore- and mesopore-rich activated-carbon (AC(micro) and AC(meso)) supercapacitors. IL electrolytes consisting of various cations [1-ethyl-3-methylimidazolium (EMI+), N-propyl-N-methylpyrrolidinium (PMP+), and N-butyl-N-methylpyrrolidinium (BMP+)] and various anions [bis(trifluoromethylsulfonyl)imide (TFSI-), BF4-, and bis(fluorosulfonyl)imide (FSI-)] are investigated. The electrolyte conductivity, viscosity, and ion transport properties at the AC(micro) and AC(meso) electrodes are studied. In addition, the capacitance, rate capability, and cycling stability of the two types of AC electrodes are systematically examined and post-mortem material analyses are conducted. The effects of IL composition on the charge-discharge capacitances of the AC(micro) electrodes are more pronounced than those for the AC(meso) electrodes. The FSI-based IL electrolytes, for which electrochemical properties are cation dependent, are found to be promising. Incorporating EMI+ with FSI- results in a low electrolyte viscosity and a fast ion transport, giving rise to optimized electrode capacitance and rate capability. Replacing EMI+ with PMP+ increases the cell voltage (to 3.5 V) and maximum energy density (to 42 Wh kg(-1)) of the AC(micro) cell at the cost of cycling stability.
Characteristics of flexible and transparent Eu2O3 resistive switching memory at high bending condition
(2019-01-25)
Aluguri, R.
;
Sailesh, R.
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Kumar, D.
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Tseng, Tseung-Yuen
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材料科學與工程學系
The characteristics of ITO/Eu2O3/ITO/PET transparent and flexible resistive switching memory are studied. The device exhibits superior characteristics such as device area-independent and forming-free resistive switching behavior with a resistance on/off ratio of 10(4), good retention of >10(4) s and high AC endurance of >10(7) cycles. The conduction mechanism of the high-resistance state is the Poole-Frenkel mechanism, while that of the low-resistance state is ohmic conduction. The electrical characteristics of the flexible device have shown excellent results up to 5 mm bending radius, at which a degradation in the on/off ratio of the memory window is observed, due to the change in the dielectric layer resistance. The resistive switching characteristics can be improved during bending up to the radius of 2 mm by the incorporation of an aluminum-doped zinc oxide layer in the device as the bottom electrode, proving its application in future flexible and transparent memory devices.
Palladium-catalyzed N1-selective allylation of indoles with allylic alcohols promoted by titanium tetraisopropoxide
(2019-01-25)
Chang, Chieh-Yu
;
Lin, Yu-Huan
;
Wu, Yen-Ku
;
應用化學系
;
Department of Applied Chemistry
The direct N1-selective allylation of indoles with allylic alcohols has been accomplished by synergistic functions of palladium catalysts and titanium tetraisopropoxide. The site selectivity is notably different from that observed in other related transition metal-catalyzed approaches. This chemistry provides a facile route to a variety of allylated indoles in synthetically useful yields. The utility of this simple allylation reaction was demonstrated with the first total synthesis of (+)-N-(4-hydroxyprenyl)-cyclo(alanyltryptophyl), which was completed in five steps, starting from l-tryptophan methyl ester hydrochloride.
Tumor targeting with DGEA peptide ligands: a new aromatic peptide amphiphile for imaging cancers
(2019-01-25)
Zhan, Fu-Kai
;
Liu, Jyun-Cheng
;
Cheng, Bill
;
Liu, Yen-Chu
;
Lai, Tsung-Sheng
We report a novel fluorescent bioprobe, tetraphenylethylene-Phe-Asp-Gly-Glu-Ala (TPE-FDGEA), and its self-assembly behavior, photophysical properties, and biocompatibility. The hydrogelator TPE-FDGEA exhibited aggregation-induced emission characteristics, which facilitated imaging of PC-3 human prostate cancer cells, thereby demonstrating the utility of such fluorescent probes for specific labeling of target cells in vitro.