Browsing by Issue Date, starting with "2019-06-15"

Now showing 1 - 20 of 7360

Exploring the formation of thermally detuned transverse patterns in a broad-area square VCSEL
(2019-06-15)
Tuan, P. H.
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Yu, Y. T.
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Huang, K. F.
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Chen, Y. F.
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電子物理學系
The formation of thermally detuned transverse patterns of a broad-area square-aperture vertical-cavity surface-emitting laser (VCSEL) via cryogenic cooling is explored. It is found that the transverse wave vector gradually rotates from the horizontal or vertical direction to the diagonal direction of the square boundary as the transverse mode order increases. A model based on the quantum billiards with a finite potential well is developed to emulate the transition behavior of lasing modes. Combining the effective modal gain analysis with the response wave function of driven finite potential billiards, all experimental lasing patterns under different operation temperatures are well recon- structed. (C) 2019 Optical Society of America
Analytical Modelling of Software and Hardware Switches with Internal Buffer in Software-Defined Networks
(2019-06-15)
Singh, Deepak
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Ng, Bryan
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Lai, Yuan-Cheng
;
Lin, Ying-Dar
;
Seah, Winston K. G.
Open Flow supports internal buffering of data packets in Software-Defined Networking (SDN) switch whereby a fraction of data packet header is sent to the controller instead of an entire data packet. This internal buffering increases the robustness and the utilization of the link between SDN switches and the controller by absorbing temporary burst of packets which may overwhelm the controller. Existing queuing models for an SDN have focused on the switches that immediately sends packets to the controller for decisioning, with no existing models investigating the impact of the internal buffer in SDN software and hardware switches. In this paper, we propose a unified queueing model to characterise the performance of SDN software and hardware switches with the internal buffer. This unified queueing model is an analytical tool for network engineers to predict a delay and loss during SDN deployments in delay and loss sensitive environments. Our results show that a hardware switch achieves up to 80% lower average packet transfer delay and 99% lower packet loss rate at the cost of requiring up to 50% more queue capacity than a software switch. The proposed models are validated with a discrete event simulation, where the error between 0.6% and 2.8% was observed for both average packet transfer delay and average packet loss rate. Moreover, a hardware switch outperforms a software switch with increasing number of hosts per switch suggesting that a hardware switch has better scalability. We use the insights from the model to develop guidelines that help network engineers decide between a software and hardware switch in their SDN deployments.
Insights into the rapid elimination of antibiotics from aqueous media by tunable C3N4 photocatalysts: Effects of dopant amount, co-existing ions and reactive oxygen species
(2019-06-15)
de Luna, Mark Daniel G.
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Paragas, Larah Kriselle B.
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Doong, Ruey-An
;
環境工程研究所
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Institute of Environmental Engineering
Conventional photocatalytic nanomaterials are not environmentally sustainable since these are usually produced from scarce mineral and metal precursors. Moreover, high pollutant removal efficiencies by conventional photocatalysts are only attained after several hours of reaction with light. In this study, novel visible light-active photocatalysts were synthesized from environment-friendly carbon precursors and applied for the rapid degradation of sulfamethoxazole (SMX) in aqueous solutions. The photocatalysts were prepared via the co-pyrolysis of urea with varying doping temperature and dopant amount. These variations played a vital role in improving the performance of the photocatalysts and resulted in up to >99% SMX removal within 45 min of visible light irradiation. Characterization of the photocatalysts showed that potassium and iodine dopants were responsible in the red shift and broadening of the light absorption spectrum to the visible region. In addition, the band gap energy narrowed by 0.23 eV resulting in faster charge transfer but slower recombination of the photo-generated electron and hole pairs. Effects of varying concentrations of inorganic salts (NO3-, SO42-, Cl-, PO43-) on SMX removal were also examined. Lastly, the mechanism of SMX photodegradation was elucidated. (C) 2019 Elsevier B.V. All rights reserved.
On identification of agonistic interaction: Hepatitis B and C interaction on hepatocellular carcinoma
(2019-06-15)
Lin, Sheng-Hsuan
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Huang, Yen-Tsung
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Yang, Hwai-I
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統計學研究所
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Institute of Statistics
Agonistic interaction is one of the most important types of mechanistic interaction, which is difficult to be distinguished from synergistic interaction by empirical data. In this study, we propose four approaches that suffice to identify and estimate the agonistic interaction: (1) to make a strong assumption that synergism does not exist; (2) to exploit information from a third factor by assuming that this factor is a necessary component for the background condition of synergistic interaction but is not involved in other mechanisms; (3) to consider a third factor necessary for the background condition of agonistic interaction but not involved in other mechanisms; and (4) similar to (3) but to allow flexibility that the third factor may have a main effect on the outcome and/or a synergistic effect with the two risk factors of interest. We applied the proposed methods to quantify the agonism of Hepatitis B and C viruses (HBV and HCV) infections on liver cancer using a Taiwanese cohort study (n = 23 820; HBV carrier n = 4149 (17.44%), HCV carrier n = 1313 (5.52%)). The result demonstrated that agonistic interaction is more dominant compared with synergistic interaction, which explains the findings that the dual infected patients do not have a significantly higher risk of liver cancer than those with single infection. By exploiting an additional risk factor that satisfies certain assumptions, these approaches potentially fill the gap between mechanistic and causal interactions, contributing the comprehensive understanding of causal mechanisms.
Pure rotational spectrum of cis-OSOO
(2019-06-16)
Nakajima, Masakazu
;
Endo, Yasuki
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應用化學系
;
Department of Applied Chemistry
Pure rotational transitions of cis-OSOO are identified in a discharge plasma of a SO2 and O-2 gaseous mixture by Fourier-transform microwave (FTMW) and FTMW-MW double-resonance spectroscopy. Both a- and b-type transitions are observed for this molecule, and the rotational and centrifugal distortion constants are precisely determined from the observed line positions. The inertial defect calculated from the determined rotational constants indicates that the cis-OSOO molecule has a planar equilibrium geometry in the ground vibronic state.
Catalyst-Controlled Chemodivergent Annulation to Indolo/Pyrrolo-Fused Diazepine and Quinoxaline
(2019-06-18)
Dhole, Sandip
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Chiu, Wei-Jung
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Sun, Chung-Ming
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應用化學系
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Department of Applied Chemistry
Catalyst-controlled chemodivergent annulation between o-indolo anilines and diazo compounds has explored for the synthesis of indolo-fused diazepine and quinoxaline Under the Rh(III) catalyst, reaction proceeded through the free amine assisted C2-H activation followed by amidation leading to the diazepino [1,7-alpha]indole in a highly selective manner. While with Ru(II) catalyst, reaction involves formation Ru-carbene complex followed by -NH2 group insertion and cascade cyclization via metallo-ene type reaction, beta-hydride elimination to furnish the indolo[1,2-alpha]quinoxaline as the predominating product. This strategy directs modular approach towards the construction of unique indolo-fused diazepine/quinoxaline as well as pyrrolo-fused diazepine/quinoxaline scaffolds in excellent yields.
Influences of Structural Modification of S,N-Hexacenes on the Morphology and OFET Characteristics
(2019-06-19)
Huang, Yi-Fan
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Wang, Chun-Kai
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Lai, Bo-Han
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Chung, Chin-Lung
;
Chen, Chin-Yi
Although chemical modifications on conjugated molecules are widely applied for the purpose of improving processability and device performances, the effect of the modification was far less investigated. Here, five S,N-hexacenes are studied to reveal the influences of (1) the lateral alkyl chain, (2) the terminal group (thiophene vs benzene), and (3) the end capping phenyl group of the hexacenes on the morphology and organic field-effect transistor (OFET) performances. Crystal arrays of the hexacenes were prepared via polydimethylsiloxane (PDMS)-assisted crystallization (PAC) prior to morphological and OFET characterizations. The lattice structures and crystal quality of the hexacenes were evaluated by microscopy and diffraction techniques including single-crystal diffractometer, electron diffraction, and grazing incidence wide-angle X-ray scattering. The systematic analyses led to the following conclusions: (1) the bulkier alkyl side chain assists to form more densely packed crystals with less structural defects; (2) the terminal thiophene rings bring about higher-lying E-HOMO, more ordered phase, and crystal orientation, whereas the terminal benzene rings deteriorate the structural order of the active layer and result in the liquid crystal phase; and (3) the phenyl end caps ameliorate the morphological order, intermolecular overlapping, thermal stability and elevate E-HOMO. Thus, EH-DTPTt-Ph delivers the highest mu(h), contributing to high-lying E-HOMO, well-oriented crystal array with a longer correlation length, and suitable lattice orientation. This systematic research provides the aspects about the effects of the functionalized S,N-hexacenes on the morphology and OFET characteristics, which is anticipated to be useful for the molecular design of heteroacenes.
Polymorphism Control of Layered MoTe2 through Two-Dimensional Solid-Phase Crystallization
(2019-06-19)
Huang, Jyun-Hong
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Hsu, Hao-Hua
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Wang, Ding
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Lin, Wei-Ting
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Cheng, Chun-Cheng
Two-dimensional (2D) molybdenum ditelluride (MoTe2) exhibits an intriguing polymorphic nature, showing stable semiconducting 2H and metallic 1T' phases at room temperature. Polymorphism in MoTe2 presents new opportunities in developing phase-change memory, high- performance transistors, and spintronic devices. However, it also poses challenges in synthesizing homogeneous MoTe2 with a precisely controlled phase. Recently, a new yet simple method using sputtering and 2D solid-phase crystallization (SPC) is proposed for synthesizing high-quality and large-area MoTe2. This study investigates the polymorphism control of MoTe2 synthesis using 2D SPC. The Te/Mo ratio and oxygen content in the as-sputtered films correlate strongly with the final phase and electrical properties of SPC MoTe2. Furthermore, the SPC thermal budget may be exploited for stabilizing a deterministic phase. The comprehensive experiments presented in this work demonstrate the versatile and precise controllability on the MoTe2 phase by using the simple 2D SPC technique.
Origin of Extended UV Stability of 2D Atomic Layer Titania-Based Perovskite Solar Cells Unveiled by Ultrafast Spectroscopy
(2019-06-19)
Thilakan, Anusha Puliparambil
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Li, Jia-Xing
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Chen, Tzu-Pei
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Li, Shao-Sian
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Chen, Chun-Wei
The inherent instability of UV-induced degradation in TiO2-based perovskite solar cells was largely improved by replacing the anatase-phase compact TiO2 layer with an atomic sheet transport layer (ASTL) of two-dimensional (2D) Ti1-delta O2. The vital role of microscopic carrier dynamics that govern the UV stability of perovskite solar cells was comprehensively examined in this work by performing time-resolved pump-probe spectroscopy. In conventional perovskite solar cells, the presence of a UV-active oxygen vacancy in compact TiO2 prohibits current generation by heavily trapping electrons after UV degradation. Conversely, the dominant vacancy type in the 2D Ti1-delta O2 ASTL is a titanium vacancy, which is a shallow acceptor and is not UV-sensitive. Therefore, it significantly suppresses carrier recombination and extends UV stability in perovskite solar cells with a 2D Ti1-delta O2 ASTL. Other carrier dynamics, such as electron diffusion, electron injection, and hot hole transfer processes, were found to be less affected by UV irradiation. Quantitative pump-probe data clearly show a correlation between the carrier dynamics and UV aging of perovskite solar cells, thus providing a profound insight into the factors driving UV-induced degradation in perovskite solar cells and the origin of its performance.
Correcting long-range electrostatics in DFTB
(2019-06-21)
Podeszwa, Rafal
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Jankiewicz, Wojciech
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Krzus, Magdalena
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Witek, Henryk A.
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交大名義發表
We demonstrate that the atom-based charge model implemented in the current versions of the density functional tight binding (DFTB) method fails to reproduce the correct charge distribution of a range of systems, including homonuclear molecules, graphene, and nanotubes, resulting in serious distortions in the electrostatic interactions for such systems caused by the missing quadrupole moments. In particular, this failure seriously impacts the long- and medium-range interaction energies of the DFTB plus dispersion (DFTB-D) model, leading to incorrect predictions of translational or rotational barriers in such systems. We show explicitly on examples of H-2 and N-2 that correct quadrupole momentsand consequently correct electrostatic interactionscan be restored in such systems by adding additional bond (ghost) sites to the homonuclear molecules. Attempts to determine the point charges associated with the additional sites using the usual Mulliken population analysis lead to unphysical results. Instead, these charges can be determined using the actual DFTB densities used in the parameterization process. For homonuclear molecules, we propose an extension to the DFTB-D model by adding charges that reproduce the physically correct quadrupolar charge distribution. The resulting DFTB-D-Q model greatly improves the rotational barriers for interactions of molecular hydrogen and nitrogen with benzene.
A functionalized membrane for lithium-oxygen batteries to suppress the shuttle effect of redox mediators
(2019-06-21)
Chen, Zi-Fang
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Lin, Xiaodong
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Xia, Hui
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Hong, Yuhao
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Liu, Xiaoyu
Redox mediators (RMs) are widely applied in lithium-oxygen (Li-O-2) batteries since they offer an alternative way to avoid the direct electrochemical oxidization of Li2O2 during charging, and thus greatly reduce the charge overpotential. Unfortunately, the defenseless Li-metal anode is severely corroded by the oxidized RMs shuttled from the cathode side, resulting in the low utilization of RMs and poor cycling stability. Herein, a functionalized double-guaranteed NPG membrane with electrostatic repulsion and steric hindrance characteristics is proposed to suppress the shuttle effect of LiI RM. Benefiting from the interaction between the O atoms in PEO and the sulfonic acid groups in Nafion and the two-dimensional skeleton structure of graphene, Nafion, PEO and graphene can couple with each other, forming a large network barrier with multi-functional properties. As expected, the LiI-based Li-O-2 batteries with the NPG membrane exhibited a smooth, iodine-free Li anode surface after many cycles and delivered an ultrahigh discharge capacity of similar to 26 917 mA h g(-1) at a current density of 200 mA g(-1) and ultralong cycle life (472 cycles) at 500 mA g(-1) with a cutoff capacity of 500 mA h g(-1), which are far better than that of the bare batteries.
Direct generation of red and orange optical vortex beams from an off-axis diode-pumped Pr3+:YLF laser
(2019-06-24)
Ma, Yuanyuan
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Valles, Adam
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Tung, Jung-Chen
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Chen, Yung-Fu
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Miyamoto, Katsuhiko
We demonstrate the direct generation of visible vortex beams at 640 nm and 607 nm by employing an off-axis pumping scheme in a diode end-pumped Pr3+:YLF laser. A detailed numerical analysis, based on the coherent superposition of Hermite-Gaussian modes with different amplitudes and phases, is perfectly consistent with the experimentally observed lasing modes. The maximum vortex output powers have been measured to be 808 mW and 211 mW at a pump power of 3.16 W, for the wavelengths of 640 nm and 607 nm, respectively. We also demonstrate the handedness control of the generated vortex beam. Such a visible vortex laser can potentially be applied in super-resolution fluorescent microscopes and micro-fabrication research. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Electrochemical Properties of CNT/MnO2 Hybrid Nanostructure with Low-Temperature Hydrothermal Synthesis as High-Performance Supercapacitor
(2019-06-25)
Li, Wei-Shuo
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Chang, Man-Lin
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Chuang, Kai-Chi
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Li, Yi-Shao
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Luo, Jun-Dao
Multi-walled carbon nanotubes (CNTs)/manganese dioxide (MnO2) nanocomposites were fabricated using the low-temperature hydrothermal method with no oxidant addition as hybrid supercapacitors. The electrochemical behaviors of CNTs-MnO2 were systematically investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The specific capacitance was promoted from 30.3 F g(-1) to 405.15 F g(-1) with a hydrothermal reaction time of 5 min. Compared to pristine CNTs, the improvement ratio of the specific capacitance of a hydrothermal reaction time of 5 min was 13.4 times under the condition of a 1 M Na2SO4 electrolyte at a scan rate of 100 mVs(-1). The CNTs-MnO2 electrode also demonstrated better cycling stability after 1000 cycles. Moreover, this study demonstrates that CNTs-MnO2 electrodes have a low-temperature facile synthesis, high specific capacitance, and good cycle stability. Thus, these good supercapacitors electrodes are promising for the development in energy-storage devices in the future. (c) 2019 The Electrochemical Society.
SeQuery: an interactive graph database for visualizing the GPCR superfamily
(2019-06-25)
Hu, Geng-Ming
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Secario, M. K.
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Chen, Chi-Ming
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應用化學系
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Department of Applied Chemistry
The rate at which new protein and gene sequences are being discovered has grown explosively in the omics era, which has increasingly complicated the efficient characterization and analysis of their biological properties. In this study, we propose a web-based graphical database tool, SeQuery, for intuitively visualizing proteome/genome networks by integrating the sequential, structural and functional information of sequences. As a demonstration of our tool's effectiveness, we constructed a graph database of G protein-coupled receptor (GPCR) sequences by integrating data from the UniProt, GPCRdb and RCSB PDB databases. Our tool attempts to achieve two goals: (i) given the sequence of a query protein, correctly and efficiently identify whether the protein is a GPCR, and, if so, define its sequential and functional roles in the GPCR superfamily; and (ii) present a panoramic view of the GPCR superfamily and its network centralities that allows users to explore the superfamily at various resolutions. Such a bottom-up-to-top-down view can provide the users with a comprehensive understanding of the GPCR superfamily through interactive navigation of the graph database. A test of SeQuery with the GPCR2841 dataset shows that it correctly identifies 99 out of 100 queried protein sequences. The developed tool is readily applicable to other biological networks, and we aim to expand SeQuery by including additional biological databases in the near future.
A Novel AURKA Mutant-Induced Early-Onset Severe Hepatocarcinogenesis Greater than Wild-Type via Activating Different Pathways in Zebrafish
(2019-06-26)
Su, Zhong-Liang
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Su, Chien-Wei
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Huang, Yi-Luen
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Yang, Wan-Yu
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Sampurna, Bonifasius Putera
Aurora A kinase (AURKA) is an important regulator in mitotic progression and is overexpressed frequently in human cancers, including hepatocellular carcinoma (HCC). Many AURKA mutations were identified in cancer patients. Overexpressing wild-type Aurka developed a low incidence of hepatic tumors after long latency in mice. However, none of the AURKA mutant animal models have ever been described. The mechanism of mutant AURKA-mediated hepatocarcinogenesis is still unclear. A novel AURKA mutation with a.a.352 Valine to Isoleucine (V352I) was identified from clinical specimens. By using liver-specific transgenic fish overexpressing both the mutant and wild-type AURKA, the AURKA(V352I)-induced hepatocarcinogenesis was earlier and much more severe than wild-type AURKA. Although an increase of the expression of lipogenic enzyme and lipogenic factor was observed in both AURKA(V352I) and AURKA(WT) transgenic fish, AURKA(V352I) has a greater probability to promote fibrosis at 3 months compared to AURKA(WT). Furthermore, the expression levels of cell cycle/proliferation markers were higher in the AURKA(V352I) mutant than AURKA(WT) in transgenic fish, implying that the AURKA(V352I) mutant may accelerate HCC progression. Moreover, we found that the AURKA(V352I) mutant activates AKT signaling and increases nuclear beta-catenin, but AURKA(WT) only activates membrane form beta-catenin, which may account for the differences. In this study, we provide a new insight, that the AURKA(V352I) mutation contributes to early onset hepatocarcinogenesis, possibly through activation of different pathways than AURKA(WT). This transgenic fish may serve as a drug-screening platform for potential precision medicine therapeutics.
Fluorescent B-10 embedded nanodiamonds as B-10 delivery agent for boron neutron capture therapy
(2019-06-26)
Lin, Bo-Rong
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Kunuku, Srinivasu
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Chen, Tzung-Yuang
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Chang, Yu-Jen
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Liao, Li-Chuan
Boron neutron capture therapy is a potentially powerful anti-cancer treatment, the success of which depends heavily on the boron delivery agent. Enabling the real-time tracing of delivery agents as they move through the body is crucial to the further development of boron neutron capture therapy. In this study, we fabricate fluorescent B-10 embedded nanodiamonds using physical ion implantation in conjunction with a two-step annealing process. Fluorescent B-10 embedded nanodiamonds perform well in cell viability test. The red fluorescence of the B-10 embedded nanodiamonds allows their use in fluorescence microscopy and in vivo imaging systems, thereby making it possible to conduct tracking in real time. The proposed fluorescent B-10 embedded nanodiamonds, combining optical visibility and B-10 transport capability, might be a promising boron delivery agent suitable for a wide range of biomedical applications.
Performance Enhancement for Tungsten-Doped Indium Oxide Thin Film Transistor by Hydrogen Peroxide as Cosolvent in Room-Temperature Supercritical Fluid Systems
(2019-06-26)
Ruan, Dun-Bao
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Liu, Po-Tsun
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Yu, Min-Chin
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Chien, Ta-Chun
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Chiu, Yu-Chuan
In this study, hydrogen peroxide (H2O2) cosolvent, which was dissolved into supercritical-phase carbon dioxide fluid (SCCO2), is employed to passivate excessive oxygen vacancies of the high-mobility tungsten-doped indium oxide without any essential thermal process. With the detailed material analysis, the internal physical mechanism of the cosolvent effect or the interaction between the cosolvent solution and supercritical-phase fluid is well discussed. In addition, the optimized result has been applied for the thin film transistor device fabrication. As a result, the device with SCCO2 + H2O2 treatment exhibits the lowest subthreshold swing of 82 mV/dec, the lowest interface trap density of 8.76 x 10(11) eV(-1) cm(-2), the lowest hysteresis of 47 mV, and an excellent reliability and uniformity characteristic compared with any other control groups. Besides, an extremely high field-effect mobility of 98.91 cm(2)/V s can also be observed, while there is even a desirable positive shift for the threshold voltage. Notably, compared with the untreated sample, the highest on/off current ratio of 5.11 x 10(7) can be achieved with at least four orders of magnitude enhancement by this unique treatment.
Electrical, Optical, and Thermal Transport Properties of Oxygen-Deficient Amorphous WOx (2.5 < x < 3) Films
(2019-06-27)
Kim, Gowoon
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Cho, Hai Jun
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Sheu, Yu-Miin
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Ohta, Hiromichi
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交大名義發表
Oxygen-deficient tungsten oxide (WOx) is known as an active material for various future applications such as smart displays, photocatalysts, Li-ion battery, and so on. WOx exhibits versatile properties depending on the valence state of W, which can vary from +6 to +4. Therefore, clarifying the relationship between x, the valence state of W ion, and the material properties of WOx is crucial for discovering more unique device applications. In case of crystalline WOx, since WOx has many different phases, the valence state of W cannot be modulated continuously from +6 to +4. On the other hand, there is no phase boundary in amorphous (a-) WOx, the valence state of W ion can be continuously modulated against x, and the effect of valence state of W on the material properties of WOx can be thoroughly examined. Here, we report the electrical, optical, and thermal properties of a-WOx films with several valence states of +6 (d(0)), +5 (d(1)), and +4 (d(2)) for x ranging from 2.511 to 2.982. Although the +6 dominant films were electrical insulators with optical transparency in the visible region, we found that both optical transmissivity and electrical resistivity decreased drastically with increase in the +5 concentrations, which also enhances the thermal conductivity because heat can be carried by additional conduction electrons. As the +4 state became dominant in the film, the resistivity slightly increased, whereas the low visible transmission was maintained. These results suggest that the redox of tungsten between +6 and +5 is attributed to all versatile properties of a-WOx, which would be of great use for developing unique devices in the future.
Contrapuntal Composition and Autonomous Style Development of Organum Motets by using AntsOMG
(2019-06-28)
Chang, Chun-yien
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Chen, Ying-ping
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資訊工程學系
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Department of Computer Science
球隊年度盛事——歡樂校友盃
(國立陽明大學, 2019-06-28)
陽明電子報編輯小組
本校各球隊每年最盛大的一場活動──校友盃球賽，即是邀請歷屆球隊的校友，撥冗回母校，與在校生攜手進行球賽交流！學長姐豐富的經驗與表現，都是學弟妹成長學習的典範，每年此時，在各球場揮汗打球與歡笑聲中，總能更拉近彼此間緊密的情誼！學弟妹們也非常感謝學長姐們一直以來的支持，以下就是今年各球隊所分享之108年排球 /男籃 /桌球 /女籃 /足球校友盃球賽精采回顧！他們也期盼明年，再次與學長姐切磋討教！