Browsing by Issue Date, starting with "2020-03-16"

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Photonic Crystal Circular Nanobeam Cavity Laser with Type-II GaSb/GaAs Quantum Rings as Gain Material
(2020-03-16)
Lin, Hsiang-Ting
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Hsu, Kung-Shu
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Chang, Chih-Chi
;
Lin, Wei-Hsun
;
Lin, Shih-Yen
The optical emission from type-II semiconductor nanostructures is influenced by the long carrier lifetime and can exhibit remarkable thermal stability. In this study, utilizing a high quality photonic crystal circular nanobeam cavity with a high quality factor and a sub-micrometer mode volume, we demonstrated an ultra-compact semiconductor laser with type-II gallium antimonide/gallium arsenide quantum rings (GaSb/GaAs QRs) as the gain medium. The lasing mode localized around the defect region of the nanobeam had a small modal volume and significant coupling with the photons emitted by QRs. It leads the remarkable shortening of carrier lifetime observed from the time-resolved photoluminescence (TRPL) and a high Purcell factor. Furthermore, a high characteristic temperature of 114K was observed from the device. The lasing performances indicated the type-II QRs laser is suitable for applications of photonic integrated circuit and bio-detection applications.
Phase modulators with tunability in wavefronts and optical axes originating from anisotropic molecular tilts under symmetric electric field II: experiments
(2020-03-16)
Wang, Yu-Jen
;
Lin, Yi-Hsin
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Cakmakci, Ozan
;
Reshetnyak, Victor
;
光電工程學系
We demonstrate, for the first time, an electrically-tunable and physically-planar freeform optical element made up of nematic liquid crystals (LCs). Continued on numerical study in previous paper (Part I), experimental results here show that it is possible to break the rotational symmetry of the wavefront through the use of uneven tilt angles of the LC molecules even though the electric potential is rotationally symmetric. Our optical element offers the ability to electrically tune the direction of the optical axis, the wavefront deviation, as well as the Zernike polynomials for general descriptions of wavefronts. Corresponding Zernike coefficients of a Zernike polynomial that are related to defocus and spherical aberration, which can be adjusted individually or together. The minimum wavefront deviation is >lambda/16. The Zernike coefficients related to coma aberration or the tilt of the optical axis are also electrically tunable. By incorporating our LC phase modulator with tunability of freeform wavefronts into a simple reflective optical system, we demonstrate convincing image performance for off-axis image aberration correction. This approach will inspire further development and design of LC optical elements for applications, such as hyperspectral imagers in aerospace optics, augmented reality, virtual reality, quantum information systems, innovative miniaturized reflective telescopic systems for astrophysics, planetary science, and earth science. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Merging anomalous data usage in wireless mobile telecommunications: Business analytics with a strategy-focused data-driven approach for sustainability
(2020-03-16)
Chen, Yi-Ting
;
Sun, Edward W.
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Lin, Yi-Bing
;
資訊工程學系
;
Department of Computer Science
Mobile internet usage has exploded with the mass popularity of smartphones that offer more convenient and efficient ways of doing anything from watching movies, playing games, and streaming music. Understanding the patterns of data usage is thus essential for strategy-focused data-driven business analytics. However, data usage has several unique stylized facts (such as high dimensionality, heteroscedasticity, and sparsity) due to a great variety of user behaviour. To manage these facts, we propose a novel density-based subspace clustering approach (i.e., a three-stage iterative optimization procedure) for intelligent segmentation of consumer data usage/demand. We discuss the characteristics of the proposed method and illustrate its performance in both simulation with synthetic data and business analytics with real data. In a field experiment of wireless mobile telecommunications for data-driven strategic design and managerial implementation, we show that our method is adequate for business analytics and plausible for sustainability in search of business value. (C) 2019 Published by Elsevier B.V.
A Displacement Frequency Response Function-Based Approach for Locating Damage to Building Structures
(2020-03-17)
Kao, Ching-Yun
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Chen, Xuan-Zhi
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Hung, Shih-Lin
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土木工程學系
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Department of Civil Engineering
Frequency response function (FRF) data can provide considerably more information on damage in the desired frequency range as compared to modal data extracted from a very limited range around resonances. Among structural health monitoring techniques, FRF-based methods have the potential to locate structural damage. Conventional structural damage detection technology collects structural response data using contact systems, such as displacement or acceleration transducers. However, installing these contact systems can be costly in terms of labor, cost, and time. Several noncontact measurement technologies, such as optical, laser, radar, and GPS, have been developed to overcome these obstacles. Given the rapid advances in optical imaging hardware technology, the use of digital photography in structural monitoring systems has attracted considerable attention. This study develops a displacement FRF-based approach to locate damage to building structures. The proposed damage location index, CurveFRFDI, improves the sensitivity of SubFRFDI, which is a substructure FRF-based damage location index proposed by Lin et al. (2012). Moreover, the feasibility of applying the proposed approach to locate damage to building structures using displacement measured by a digital camera combined with digital image correlation techniques is also investigated in this study. A numerical example and an experimental example are presented to demonstrate the feasibility of using the proposed approach to locate damage to building structures for single and multiple nonadjacent damage locations.
Killer cell immunoglobulin-like receptors (KIR) and human leukocyte antigen-C (HLA-C) allorecognition patterns in women with endometriosis
(2020-03-17)
Chou, Ya-Ching
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Chen, Chi-Huang
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Chen, Ming-Jer
;
Chang, Ching-Wen
;
Chen, Pi-Hua
Endometriosis shares similarities with several autoimmune diseases. The human leukocyte antigen (HLA)-C genotype is associated with several human autoimmune diseases. HLA-C is a ligand of killer cell immunoglobulin receptors (KIRs) and is an essential regulator of natural killer cell activity, which is associated with endometriosis progression. Polymorphisms in HLA-C and KIR affect the activity of NK cells and susceptibility to several diseases. Therefore, we attempted to investigate an association between HLA-C genotype and KIR polymorphism and the occurrence of endometriosis. We tested the association of certain KIR and HLA-C combinations and the development of endometriosis by characterizing both KIR and HLA-C genes in 147 women with endometriosis and 117 controls. The HLA-C genotypes and KIR polymorphisms were analyzed via DNA-based method for higher-resolution genotyping. We found that the occurrence of HLA-C*03:03*01 was increased in endometriosis than in control groups. Analysis of various KIR haplotypes revealed differences between the endometriosis and control cohorts. The number of KIR centromeric A/A haplotypes was increased in the endometriosis group than controls. Moreover, the endometriosis cohort was characterized by reduced number of KIR2DS2-positive individuals in the Han Chinese population. Our current findings suggest that the KIR and HLA-C genotypes are associated with the pathogenesis of endometriosis.
Titanium dioxide-mediated resistive nanobiosensor for E. coli O157:H7
(2020-03-17)
Nadzirah, Sh.
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Hashim, U.
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Gopinath, Subash C. B.
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Parmin, N. A.
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Hamzah, Azrul Azlan
A titanium dioxide nanoparticle (TiO2 NP)-mediated resistive biosensor is described for the determination of DNA fragments of Escherichia coli O157:H7 (E. coli O157:H7). The sol-gel method was used to synthesize the TiO2 NP, and microlithography was applied to fabricate the interdigitated sensor electrodes. Conventional E. coli DNA detections are facing difficulties in long-preparation-and-detection-time (more than 3 days). Hence, electronic biosensor was introduced by measuring the current-voltage (I-V) DNA probe without amplification of DNA fragments. The detection scheme is based on the interaction between the electron flow on the sensor and the introduction of negative charges from DNA probe and target DNA. The biosensor has a sensitivity of 1.67 x 10(13) omega/M and a wide analytical range. The limit detection is down to 1 x 10(-11) M of DNA. The sensor possesses outstanding repeatability and reproducibility and is cabable to detect DNA within 15 min in a minute-volume sample (1 mu L).
Label-Free Optical Microscope Based on a Phase-Modulated Femtosecond Pump-Probe Approach with Subdiffraction Resolution
(2020-03-18)
Fathi, Amir
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Chung, Chao-Yu
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Lee, Yuan-Pern
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Diau, Eric Wei-Guang
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交大名義發表
A far-field optical microscope (OM) is a powerful noninvasive, nondestructive tool to study sub-micrometer structures and organisms, which has been used for decades to study the interactions between light and matter in the spatial domain. We report here a sophisticated label-free OM method with superspatial resolution to visualize ZnO nanoparticles. Of three femtosecond pulses, two served as pumps at 1000 nm and the other one served as a probe at 774 nm. The two pumps (one of Gaussian shape and the other of toroidal shape) were generated with a phase difference of 180 degrees. When the conventional pump-probe approach was used in the absence of a second toroidal pump, a ZnO nanoparticle was observed to show a particle size of 445 nm because of the limit of diffraction. In contrast, when the second toroidal pump was applied out of phase, the obtained OM image showed a ZnO nanoparticle down to 96 nm. We demonstrated for the first time that the reported phase-modulated pump-probe approach has an ability for spatial resolution beyond its optical diffraction limit and a potential for label-free imaging applications in nanomaterials and life sciences.
Infrared Spectra of Isomers of Protonated Aniline in Solid para-Hydrogen
(2020-03-19)
Tsuge, Masashi
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Chen, Yu-Hsuan
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Lee, Yuan-Pern
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交大名義發表
;
應用化學系
The protonation sites of aniline molecule play important roles in its chemical reactions, but the preferred protonation site of gaseous aniline has yet to be determined. In this work, we recorded infrared (IR) absorption spectra of three isomers of protonated aniline, H+C6H5NH2, produced on electron bombardment during matrix deposition at 3.2 K of a mixture of aniline and para-H-2. The intensities of IR lines of H+C6H5NH2 decreased during maintenance of the electron-bombarded matrix in darkness because of neutralization with electrons that were slowly released from their trapping sites. The observed lines were classified into three groups according to their behavior upon secondary photolysis with light at 375 and 254 nm and assigned to para-, amino-, and ortho-H+C6H5NH2, the three most stable isomers of protonated aniline, according to comparison of experimental spectra with quantum-chemically predicted spectra of five possible isomers of H+C6H5NH2. The spectra of para- and ortho-H+C6H5NH2 are newly distinguished. The approximate relative abundance of these isomers in solid p-H-2 was para:amino:ortho similar to (1.0 +/- 0.1):(1.0 +/- 0.6):(0.6 +/- 0.1). The possible mechanisms of formation are discussed.
Pd(II)-Catalyzed Direct Dehydrogenative Mono- and Diolefination of Selenophenes
(2020-03-20)
Chen, Shi-Yen
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Sahoo, Santosh K.
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Huang, Ching-Li
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Chan, Tung-Hsien
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Cheng, Yen-Ju
Pd(II)-catalyzed dehydrogenative Heck olefination of selenophenes with a broad olefinic substrate scope and high functional group tolerance is demonstrated. Carbonyl-substituted and phenyl-substituted olefins with electron-donating (D) and electron-accepting (A) groups can be regioselectively installed at C2 of the selenophene. The 2-olefinated selenophenes can subsequently undergo a second oxidative olefination to rapidly produce a new class of symmetrical D-pi-D or unsymmetrical D-pi-A 2,5-diolefinated selenophene materials.
Hydrogen abstraction in astrochemistry: formation of & x2d9;CH2CONH2 in the reaction of H atom with acetamide (CH3CONH2) and photolysis of & x2d9;CH2CONH2 to form ketene (CH2CO) in solid para-hydrogen
(2020-03-21)
Haupa, Karolina Anna
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Ong, Wei-Siong
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Lee, Yuan-Pern
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交大名義發表
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應用化學系
Acetamide (CH3CONH2) is the largest molecule containing an amide bond that has been detected in an interstellar medium; it is considered to be a precursor for complex organic molecules (COM). We utilized the advantages of a para-hydrogen (p-H-2) quantum-solid matrix host to perform efficient reactions of hydrogen atoms with CH3CONH2. The H-abstraction reaction from the methyl group of CH3CONH2 to produce the 2-amino-2-oxoethyl radical, & x2d9;CH2CONH2, was observed as the sole reaction channel in solid p-H-2 at 3.3 K, consistent with theoretical predictions that this reaction has the smallest barrier among all possible channels. Our results show that the amide bond of acetamide is unaffected by hydrogen exposure, but the hydrogen abstraction activates this molecule to react with other species on its methyl site to extend its size or to include other functional groups as a first step to form COM under prebiotic or abiotic conditions. This previously neglected path should be considered in the astrochemical modeling. The photolysis of & x2d9;CH2CONH2 at wavelengths 380-450 nm produces ketene; this step might provide a plausible mechanism to explain the anti-correlated abundance of ketene and acetamide in some astronomical observations.
Unidirectional Charge Transport via Ripplonic Polarons in a Three-Terminal Microchannel Device
(2020-03-23)
Badrutdinov, A. O.
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Rees, D. G.
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Lin, J. Y.
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Smorodin, A., V
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Konstantinov, D.
We study the transport of surface electrons on superfluid helium through a microchannel structure in which the charge flow splits into two branches, one flowing straight and one turned at 90 degrees. According to Ohm's law, an equal number of charges should flow into each branch. However, when the electrons are dressed by surface excitations (ripplons) to form polaronlike particles with sufficiently large effective mass, all the charge follows the straight path due to momentum conservation. This surface-wave induced transport is analogous to the motion of electrons coupled to surface acoustic waves in semiconductor 2DEGs.
Facile and One-Step in Situ Synthesis of Pure Phase Mesoporous Li2MnSiO4/CNTs Nanocomposite for Hybrid Supercapacitors
(2020-03-23)
Kumar, Nagesh
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Singh, Meetesh
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Kumar, Amit
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Tseng, Tseung-Yuen
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Sharma, Yogesh
In material sciences, synergistic effect and nanostructuring are the two factors which enable researchers to look beyond the conventionally defined categories of the materials. Here, we report the synthesis mechanism of pure phase mesoporous Li2MnSiO4 (LMS) with a high specific surface area by varying the concentration of metal precursors and solvents in one-step hydrothermal technique. Furthermore, the effect of MWCNTs addition on the electrochemical performance of LMS is studied. The quantitative contribution of current generating from EDLC and/or the surface pseudocapacitance reactions, and the current caused by diffusion-controlled redox reactions in the total current is also evaluated. The pure phase LMS/CNTs nanocomposite with 2% MWCNTs (abbreviated as LMS2C) is found to be the best supercapacitor material among studied nanocomposites as it exhibits specific capacitance of similar to 290 F g(-1) @ 1 A g(-1), good rate capability, small relaxation time constant (tau = 87 ms), and higher diffusion coefficient of electrolytic cations (D-k(+) = 9.4 x 10(-9) cm(2) s(-1)) in 2 M KOH aqueous electrolyte. A hybrid supercapacitor cell (HSC) designed using LMS2C as positive and activated carbon as negative electrodes shows the maximum energy density of 31 W h kg(-1), which is much higher than several recently reported hybrid supercapacitor systems. Two series connected HSCs can power a drone motor and light up 8 red LEDs for more than 3 min, indicating practical applicability of our designed hybrid supercapacitor system.
An In-situ and Direct Confirmation of Super-Planckian Thermal Radiation Emitted From a Metallic Photonic-Crystal at Optical Wavelengths
(2020-03-23)
Lin, Shawn-Yu
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Hsieh, Mei-Li
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John, Sajeev
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Frey, B.
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Bur, James A.
Planck's law predicts the distribution of radiation energy, color and intensity, emitted from a hot object at thermal equilibrium. The Law also sets the upper limit of radiation intensity, the blackbody limit. Recent experiments reveal that micro-structured tungsten can exhibit significant deviation from the blackbody spectrum. However, whether thermal radiation with weak non-equilibrium pumping can exceed the blackbody limit in the far field remains un-answered experimentally. Here, we compare thermal radiation from a micro-cavity/tungsten photonic crystal (W-PC) and a blackbody, which are both measured from the same sample and also in-situ. We show that thermal radiation can exceed the blackbody limit by >8 times at lambda = 1.7 mu m resonant wavelength in the far-field. Our observation is consistent with a recent calculation by Wang and John performed for a 2D W-PC filament. This finding is attributed to non-equilibrium excitation of localized surface plasmon resonances coupled to nonlinear oscillators and the propagation of the electromagnetic waves through non-linear Bloch waves of the W-PC structure. This discovery could help create super-intense narrow band thermal light sources and even an infrared emitter with a laser-like input-output characteristic.
Heat Transfer of Semicrystalline Nylon Nanofibers
(2020-03-24)
Chien, Hsin-Che
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Peng, Wei-Tsu
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Chiu, Te-Hsuan
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Wu, Pei-Hsiu
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Liu, Yueh-Ju
Polymers are generally regarded as thermal insulators. The efficient heat transfer observed in the low-dimensional polymers in the literature mainly result from the larger crystallinity or improved polymer chain orientation in the low-dimensional polymers. However, the role of the amorphous domain on heat transfer in polymers remains unexplored. In this work, we report that the semicrystalline nylon polymer nanofibers can exhibit a very large thermal conductivity of 59.1 +/- 3.1 W m(-1) K-1 and the heat transfer in the semicrystalline polymer nanofibers was time-dependent. The thermal conductivity of the nanofibers could be modulated to span 3 orders of magnitude from being nearly insulated (similar to 0.27 +/- 0.02 W m(-1) K-1) to being highly thermal conductive after annealing (similar to 59.1 +/- 3.1 W m(-1) K-1). The time-dependent thermal conductivity was observed at a temperature lower than the gamma transition temperature of the polymer and was a result of the physical aging of the semicrystalline polymer. A phenomenological model was adopted to explain the time-dependent heat transfer of the semicrystalline nanofibers. The physical aging reduced the configuration disorder in the polymer and caused the heat transfer of the semicrystalline polymer to increase during the annealing process.
Exploring career commitment and turnover intention of high-tech personnel: a socio-cognitive perspective
(2020-03-25)
Lin, Chieh-Peng
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經營管理研究所
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Institute of Business and Management
Drawing upon social cognitive theory, this study presents psychosocial functioning in which personal factors and social influences jointly influence career commitment as a mediator and then turnover intention as an outcome among high-tech personnel. Based on a two-wave survey of working professionals in high-tech industry, this study's empirical results find that passion, social support, and perceived self-centered leadership indirectly relate to turnover intention through the full mediation of career commitment. At the same time, the effects of job self-efficacy and social support on career commitment are moderated respectively by passion. Finally, managerial implications and research limitations are discussed.
Combinational Approach To Realize Highly Efficient Light-Emitting Electrochemical Cells
(2020-03-25)
Yi, Rong-Huei
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Lo, Chieh-Liang
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Luo, Dian
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Lin, Chien-Hsiang
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Weng, Shu-Wen
Light-emitting electrochemical cells (LECs) show high technical potential for display and lighting utilizations owing to the superior properties of solution processability, low operation voltage, and employing inert cathodes. For maximizing the device efficiency, three approaches including development of efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction have been reported. However, most reported works focused on only one of the three optimization approaches. In this work, a combinational approach is demonstrated to optimize the device efficiency of LECs. A sophisticatedly designed yellow complex exhibiting a superior steric hindrance and a good carrier balance is proposed as the emissive material of light-emitting electrochemical cells and thus the external quantum efficiency (EQE) is up to 13.6%. With an improved carrier balance and reduced self-quenching by employing the host-guest strategy, the device EQE can be enhanced to 16.9%. Finally, a diffusive layer embedded between the glass substrate and the indium-tin-oxide layer is utilized to scatter the light trapped in the layered device structure, and consequently, a high EQE of 23.7% can be obtained. Such an EQE is impressive and consequently proves that the proposed combinational approach including adopting efficient emissive materials, optimizing the carrier balance, and maximizing the light extraction is effective in realizing highly efficient LECs.
Lattice distortion effect on elastic anisotropy of high entropy alloys
(2020-03-25)
Yen, Chao-Chun
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Huang, Guan-Rong
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Tan, Yun-Cheng
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Yeh, Han-Wen
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Luo, Da-Ji
The superior mechanical properties of high-entropy alloys (HEAs) have made an outstanding success in materials science and engineering. Studies to date have been devoted to what the severe lattice distortion induces. However, most researchers focus on its stimulation to plastic deformation instead of scrutinizing the variations on elasticity. Compared with conventional alloys, HEAs may perform disproportionate elasticity with uneven local lattice strain resulting from the severe lattice distortion. Therefore, it is necessary to survey its influence on the mechanical properties of HEAs systematically. In this study, the Lennard-Jones (LJ) potential, the embedded atom method (EAM) potential, and the modified embedded atom method (MEAM), are respectively conducted to investigate the lattice distortion effect on Young's modulus E (hkl) and Poisson's ratio nu (hkl, theta) along [100], [110], and [111] loading directions for several fcc metals composed of 1 similar to 5 atomic types, including Ni, Ni98W2, Ni96W4, FeCrNi, and CoNiCrFeMn HEAs. Also, a method is used to analyze the performance of the individual element on the elastic properties in the HEA environment. As a result, it can be unveiled that the effect of electron density inconsistency is more dominant than the effect of lattice distortion associated with the atomic size difference. The electronic configuration in the HEA environment plays a major role in elastic anisotropy while the difference of the atomic radii does the minor one. The anisotropy of CoNiCrFeMn HEA analyzed by this work is also consistent with in-situ neutron diffraction measurements. (C) 2019 Elsevier B.V. All rights reserved.
Evolving Crystal Morphology of Potassium Chloride Controlled by Optical Trapping
(2020-03-26)
Cheng, An-Chieh
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Masuhara, Hiroshi
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Sugiyama, Teruki
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交大名義發表
;
應用化學系
Dynamic morphology evolution of potassium chloride (KCl) crystals was demonstrated by surface optical trapping with a focused continuous-wave near-infrared laser. Optical trapping at an air/solution interface triggered the crystallization, and then, the dynamic change in crystal morphology was observed in real time. We observed three different crystal morphologies of needle, rectangle, and cubic at the early stage of crystallization. As the laser power increases, the probability of generation of a cubic crystal increases, especially upon the irradiation with linear polarization. We also found laser polarization-dependent morphology evolution by the continuous irradiation to the generated crystals. Upon linearly polarized laser irradiation, the stepwise morphology evolves from needle to rectangle, and eventually to cubic, which is an equilibrium shape of KCl crystals. Meanwhile, circularly polarized laser irradiation only induced morphology evolution from needle to rectangle, without morphology change into cubic, because the rectangle crystal was dissolved while the crystal was rotating. It was made possible to observe such a unique morphological evolution due to the spatiotemporal controllability of our crystallization method. The dynamics and mechanism of these intriguing phenomena are discussed from the perspective of a dense cluster domain formed by optical trapping before nucleation.
【同名計畫～陽明山會師大縱走】
(國立陽明大學, 2020-03-27)
陽明電子報編輯小組
「榮陽交防疫聯盟」全力協助國內藥廠量產抗病毒藥物
(國立陽明大學, 2020-03-27)
陽明電子報編輯小組
陽明與交通大學、臺北榮民總醫院因應新型冠狀病毒疫情組成的防疫聯盟，考量目前疫情發展急需抗病毒藥物，已與心悅生醫、台耀化學...