Browsing by Issue Date, starting with "2017-03-20"

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Cyclooxygenase-2 facilitates dengue virus replication and serves as a potential target for developing antiviral agents
(2017-03-20)
Lin, Chun-Kuang
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Tseng, Chin-Kai
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Wu, Yu-Hsuan
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Liaw, Chih-Chuang
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Lin, Chun-Yu
Cyclooxygenase-2 (COX-2) is one of the important mediators of inflammation in response to viral infection, and it contributes to viral replication, for example, cytomegalovirus or hepatitis C virus replication. The role of COX-2 in dengue virus (DENV) replication remains unclear. In the present study, we observed an increased level of COX-2 in patients with dengue fever compared with healthy donors. Consistent with the clinical data, an elevated level of COX-2 expression was also observed in DENV-infected ICR suckling mice. Using cell-based experiments, we revealed that DENV-2 infection significantly induced COX-2 expression and prostaglandin E-2 (PGE(2)) production in human hepatoma Huh-7 cells. The exogenous expression of COX-2 or PGE2 treatment dose-dependently enhanced DENV-2 replication. In contrast, COX-2 gene silencing and catalytic inhibition sufficiently suppressed DENV-2 replication. In an ICR suckling mouse model, we identified that the COX-2 inhibitor NS398 protected mice from succumbing to life-threatening DENV-2 infection. By using COX-2 promoter-based analysis and specific inhibitors against signaling molecules, we identified that NF-kappa B and MAPK/JNK are critical factors for DENV-2-induced COX-2 expression and viral replication. Altogether, our results reveal that COX-2 is an important factor for DENV replication and can serve as a potential target for developing therapeutic agents against DENV infection.
Optical filter requirements in an EML-based single-sideband PAM4 intensity-modulation and direct-detection transmission system
(2017-03-20)
Chen, Hsing-Yu
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Kaneda, Noriaki
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Lee, Jeffrey
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Chen, Jyehong
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Chen, Young-Kai
The feasibility of a single sideband (SSB) PAM4 intensity-modulation and directdetection (IM/DD) transmission based on a CMOS ADC and DAC is experimentally demonstrated in this work. To cost effectively build a >50 Gb/s system as well as to extend the transmission distance, a low cost EML and a passive optical filter are utilized to generate the SSB signal. However, the EML-induced chirp and dispersion-induced power fading limit the requirements of the SSB filter. To separate the effect of signal-signal beating interference, filters with different roll-off factors are employed to demonstrate the performance tolerance at different transmission distance. Moreover, a high resolution spectrum analysis is proposed to depict the system limitation. Experimental results show that a minimum roll-off factor of 7 dB/10GHz is required to achieve a 51.84Gb/s 40-km transmission with only linear feedforward equalization. (C) 2017 Optical Society of America
交大e-News第228期-校長講座：李遠哲院士談全球氣候變遷
(2017-03-20)
國立交通大學秘書室
;
Secretariat
Near-field spectral properties of coupled plasmonic nanoparticle arrays
(2017-03-20)
Yu, Han
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Sun, Quan
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Yang, Jinghuan
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Ueno, Kosei
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Oshikiri, Tomoya
We investigated the grating effect in complex gold dolmen structures, in which multiple plasmon modes are present due to plasmon hybridization, experimentally from both the far field and the near field. In particular, the near-field properties were investigated using photoemission electron microscopy, and it was demonstrated that two hybridized plasmon modes on the dolmen structures could be influenced by the grating effect. For comparison, we also investigated the grating effect in arrays of simple nanoblocks and heptamer structures, which were supposed to support a strong bright plasmon mode and a strong dark plasmon mode, respectively, in the near field. We found that the spectral responses of the two hybridized modes on the dolmen structures as the pitch size changed evolved in a manner similar to that of the bright dipole mode on the nanoblocks, whereas the dark mode on the heptamer structures is less sensitive to the pitch size. (C) 2017 Optical Society of America
A Comprehensive Study of One-Step Selenization Process for Cu(In1-xGax) Se-2 Thin Film Solar Cells
(2017-03-21)
Chen, Shih-Chen
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Wang, Sheng-Wen
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Kuo, Shou-Yi
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Juang, Jenh-Yih
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Lee, Po-Tsung
In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn1-xGaxSe2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H2Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra. The surface morphologies examined by scanning electron microscope (SEM) further suggested that voids and binary phase commonly existing in CIGS films could be successfully eliminated by the present one-step selenization process. The agglomeration phenomenon attributable to the formation of MoSe2 layer was also observed. Due to the significant microstructural improvement, the current-voltage (J-V) characteristics and external quantum efficiency (EQE) of the devices made of the present CIGS films have exhibited the remarkable carrier transportation characteristics and photon utilization at the optimal location, resulting in a high conversion efficiency of 11.28%. Correlations between the defect states and device performance of the one-step selenized CIGS thin film were convincingly delineated by femtosecond pump-probe spectroscopy.
Effect of the type-I to type-II Weyl semimetal topological transition on superconductivity
(2017-03-21)
Li, Dingping
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Rosenstein, Baruch
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Shapiro, B. Ya.
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Shapiro, I.
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電子物理學系
The influence of recently discovered topological transition between type-I and type-II Weyl semimetals on superconductivity is considered. A set of Gorkov equations for weak superconductivity inWeyl semimetal under topological phase transition is derived and solved. The critical temperature and superconducting gap both have spikes in the transition point as functions of the tilt parameter of the Dirac cone determined, in turn, by the material parameters like pressure. The spectrum of superconducting excitations is different in two phases: The sharp cone pinnacle is characteristic for type I, while two parallel almost flat bands, are formed in type II. Spectral density is calculated on both sides of transition to demonstrate the different weights of the bands. The superconductivity thus can be used as a clear indicator for the topological transformation. Results are discussed in the light of recent experiments.
High-Throughput Screening of Sulfated Proteins by Using a Genome-Wide Proteome Microarray and Protein Tyrosine Sulfation System
(2017-03-21)
Huang, Bo-Yu
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Chen, Po-Chung
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Chen, Bo-Han
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Wang, Chen-Chu
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Liu, Hsuan-Fu
Protein tyrosine sulfation (PTS) is a widespread posttranslational modification that induces intercellular and extracellular responses by regulating protein protein interactions and enzymatic activity. Although PTS affects numerous physiological and pathological processes, only a small fraction of the total predicted sulfated proteins has been identified to date. Here, we localized the potential sulfation sites of Escherichia coli proteins on a proteome microarray by using a 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthase-coupled tyrosylprotein sulfotransferase (TPST) catalysis system that involves in situ PAPS generation and TPST catalysis. Among the 4256 E. coil K12 proteins, 875 sulfated proteins were identified using antisulfotyrosine primary and Cy3-labeled antimouse secondary antibodies. Our findings add considerably to the list of potential proteins subjected to tyrosine sulfation. Similar procedures can be applied to identify sulfated proteins in yeast and human proteome microarrays, and we expect such approaches to contribute substantially to the understanding of important human diseases.
Voltage-induced Interface Reconstruction and Electrical Instability of the Ferromagnet-Semiconductor Device
(2017-03-23)
Chang, Shu-Jui
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Chang, Po-Chun
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Lin, Wen-Chin
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Lo, Shao-Hua
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Chang, Liang-Chun
Using x-ray magnetic spectroscopy with in-situ electrical characterizations, we investigated the effects of external voltage on the spin-electronic and transport properties at the interface of a Fe/ZnO device. Layer-, element-, and spin-resolved information of the device was obtained by cross-tuning of the x-ray mode and photon energy, when voltage was applied. At the early stage of the operation, the device exhibited a low-resistance state featuring robust Fe-O bonds. However, the Fe-O bonds were broken with increasing voltage. Breaking of the Fe-O bonds caused the formation of oxygen vacancies and resulted in a high-resistance state. Such interface reconstruction was coupled to a charge-transfer effect via Fe-O hybridization, which suppressed/enhanced the magnetization/coercivity of Fe electronically. Nevertheless, the interface became stabilized with the metallic phase if the device was continuously polarized. During this stage, the spin-polarization of Fe was enhanced whereas the coercivity was lowered by voltage, but changes of both characteristics were reversible. This stage is desirable for spintronic device applications, owing to a different voltage-induced electronic transition compared to the first stage. The study enabled a straightforward detection of the spin-electronic state at the ferromagnet-semiconductor interface in relation to the transport and reversal properties during operation process of the device.
Combination of Electroencephalography and Near-Infrared Spectroscopy in Evaluation of Mental Concentration during the Mental Focus Task for Wisconsin Card Sorting Test
(2017-03-23)
Chen, Che-Wei
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Sun, Chia-Wei
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光電工程學系
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Department of Photonics
Near-infrared spectroscopy (NIRS) is a noninvasive neuroimaging tool for measuring evoked functional changes in brain oxygenation. Electroencephalography (EEG) can be used to evaluate the functionality of cortical connections and obtain information on regional cortical activity. Coregistration of EEG-NIRS is a recent technique that has been applied for measuring changes in electrical and hemodynamic activity in the human brain. EEG-NIRS coregistration facilitates the avoidance of misleading interpretations of NIRS, particularly in the diagnosis of neurological disorders. In this study, we investigated an approach for enhancing accuracy of NIRS by using EEG to monitor physiological activity during a mental focus task. Using the Wisconsin Card Sorting Test for the subjects mental focus task, we identified two trend types in the EEG and NIRS signals of normal subjects. These data can assist in understanding brain activation statuses and enable determining subjects' degree of mental concentration. If the data can be standardized for the diagnosis of neurological disorders, they can provide a new index to improve traditional methods (e.g., questionnaires) to assist clinical doctors in diagnosing cognitive disorders.
AUTOMATIC PROBE CONSTRUCTION SYSTEM AND METHOD THEREOF
(2017-03-23)
Shiuhpyng Shieh
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Chi-Wei Wang
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Chia-Wei Wang
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Chia-Wei Hsu
An automatic probe construction system and the method thereof are provided. The automatic probe construction system includes a data dereference analysis module, a probe selection module, and a probe verification module. The data dereference analysis module dereferences a plurality of target data of an electronic apparatus according to a plurality of pointers, and constructs a plurality of candidate probes. The probe selection module constructs a control flow graph according to the candidate probes and an instruction code of an executable image file, to select via the control flow graph from the candidate probes at least one dedicated probe. The probe verification module searches the executable image file for an instruction code corresponding to the dedicated probe, to verify the dedicated probe. Therefore, the dedicated probe can be constructed automatically, and the number of the dedicated probes is thus limited.
Photoexfoliation of two-dimensional materials through continuous UV irradiation
(2017-03-24)
Lin, Wai-Chen
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Chuang, Ming-Kai
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Keshtov, Muchamed L.
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Sharma, Ganesh D.
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Chen, Fang-Chung
This paper describes the preparation of fluorinated graphene nanosheets (FGNs) through photoexfoliation of fluorinated graphite (FG) in the liquid phase. We discovered that UV irradiation of FG dispersions in N-methyl-2-pyrolidone facilitated exfoliation to give FGNs. Transmission electron microscopy and atomic force microscopy revealed that the average thickness of the FGNs was approximately 3 nm; they were considerably thinner than the nanosheets prepared using a conventional sonication approach. Furthermore, when the FGNs were deposited uniformly onto substrates (through spin coating), they formed effective cathode interlayers for polymer solar cells (PSCs), the efficiency of which was 60% greater than that of PSCs containing FGNs prepared through ultrasonication.
Augmented reality with image registration, vision correction and sunlight readability via liquid crystal devices
(2017-03-27)
Wang, Yu-Jen
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Chen, Po-Ju
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Liang, Xiao
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Lin, Yi-Hsin
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光電工程學系
Augmented reality (AR), which use computer-aided projected information to augment our sense, has important impact on human life, especially for the elder people. However, there are three major challenges regarding the optical system in the AR system, which are registration, vision correction, and readability under strong ambient light. Here, we solve three challenges simultaneously for the first time using two liquid crystal (LC) lenses and polarizer-free attenuator integrated in optical-see-through AR system. One of the LC lens is used to electrically adjust the position of the projected virtual image which is so-called registration. The other LC lens with larger aperture and polarization independent characteristic is in charge of vision correction, such as myopia and presbyopia. The linearity of lens powers of two LC lenses is also discussed. The readability of virtual images under strong ambient light is solved by electrically switchable transmittance of the LC attenuator originating from light scattering and light absorption. The concept demonstrated in this paper could be further extended to other electro-optical devices as long as the devices exhibit the capability of phase modulations and amplitude modulations.
Three dimensional characterization of GaN-based light emitting diode grown on patterned sapphire substrate by confocal Raman and photoluminescence spectromicroscopy
(2017-03-30)
Li, Heng
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Cheng, Hui-Yu
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Chen, Wei-Liang
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Huang, Yi-Hsin
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Li, Chi-Kang
We performed depth-resolved PL and Raman spectral mappings of a GaN-based LED structure grown on a patterned sapphire substrate (PSS). Our results showed that the Raman mapping in the PSS-GaN heterointerface and the PL mapping in the InxGa1-xN/GaN MQWs active layer are spatially correlated. Based on the 3D construction of E2(high) Raman peak intensity and frequency shift, V-shaped pits in the MQWs can be traced down to the dislocations originated in the cone tip area of PSS. Detail analysis of the PL peak distribution further revealed that the indium composition in the MQWs is related to the residual strain propagating from the PSS-GaN heterointerface toward the LED surface. Numerical simulation based on the indium composition distribution also led to a radiative recombination rate distribution that shows agreement with the experimental PL intensity distribution in the InxGa1-xN/GaN MQWs active layer.
Photodynamic dye adsorption and release performance of natural zeolite
(2017-03-31)
Hovhannisyan, Vladimir
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Dong, Chen-Yuan
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Chen, Shean-Jen
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光電學院
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College of Photonics
Clinoptilolite type of zeolite (CZ) is a promising material for biomedicine and pharmaceutics due to its non-toxicity, thermal stability, expanded surface area, and exceptional ability to adsorb various atoms and organic molecules into micropores. Using multiphoton microscopy, we demonstrated that individual CZ particles produce two-photon excited luminescence and second harmonic generation signal at femtosecond laser excitation, and adsorb photo-dynamically active dyes such as hypericin and methylene blue. Furthermore, the release of hypericin from CZ pores in the presence of biomolecules is shown, and CZ can be considered as an effective material for drug delivery and controlled release in biological systems. The results may open new perspectives in application of CZ in biomedical imaging, and introducing of the optical approaches into the clinical environment.
New Conservative Finite Volume Element Schemes for the Modified Regularized Long Wave Equation
(2017-04)
Yan, Jinliang
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Lai, Ming-Chih
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Li, Zhilin
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Zhang, Zhiyue
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應用數學系
In this paper, we propose a new energy-preserving scheme and a new momentum-preserving scheme for the modified regularized long wave equation. The proposed schemes are designed by using the discrete variational derivative method and the finite volume element method. For comparison, we also propose a finite volume element scheme. The conservation properties of the proposed schemes are analyzed and we find that the energy-preserving scheme can precisely conserve the discrete total mass and total energy, the momentum-preserving scheme can precisely conserve the discrete total mass and total momentum, while the finite volume element scheme merely conserve the discrete total mass. We also analyze their linear stability property using the Von Neumann theory and find that the proposed schemes are unconditionally linear stable. Finally, we present some numerical examples to illustrate the effectiveness of the proposed schemes.
反杜邦卅年：轉身面對
(深河出版有限公司, 2017-04-01)
鍾喬
DPLL for Phase Noise Cancellation in Ring Oscillator-Based Quadrature Receivers
(2017-04-01)
Chen, Zuow-Zun
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Kuan, Yen-Cheng
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Li, Yilei
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Hu, Boyu
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Wong, Chien-Heng
In this paper, a low overhead phase noise cancellation technique for ring oscillator (RO)-based quadrature receivers is presented. The proposed technique operates in background and extracts RO phase noise as well as supply-induced phase noise from the digital phase-locked loop. The obtained phase noise information is then used to restore the randomly rotated baseband signal in digital domain. A receiver prototype is fabricated in standard 65-nm CMOS technology. It demonstrates a phase noise reduction from -88 to -109 dBc/Hz at 1-MHz offset and an integrated phase noise reduction from -16.8 to -34.6 dBc when operating at 2.4 GHz.
Probabilistic Medium Access Control for Full-Duplex Networks With Half-Duplex Clients
(2017-04-01)
Chen, Shih-Ying
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Huang, Ting-Feng
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Lin, Kate Ching-Ju
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Hong, Y. -W. Peter
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Sabharwal, Ashutosh
The feasibility of practical in-band full-duplex radios has recently been demonstrated experimentally. One way to leverage full-duplex in a network setting is to enable three-node full-duplex, where a full-duplex access point (AP) transmits data to one node yet simultaneously receives data from another node. Such three-node full-duplex communication, however, introduces inter-client interference, directly impacting the full-duplex gain. It hence may not always be beneficial to enable three-node full-duplex transmissions. In this paper, we present a distributed full-duplex medium access control (MAC) protocol that allows an AP to adaptively switch between full-duplex and half-duplex modes. We formulate a model that determines the probabilities of full-duplex and half-duplex access so as to maximize the expected network throughput. A MAC protocol is further proposed to enable the AP and clients to contend for either full-duplex or half-duplex transmissions based on their assigned probabilities in a distributed way. Our evaluation shows that, by combining the advantages of centralized probabilistic scheduling and distributed random access, our design improves the overall throughput by 1.53 times, on average, as compared with the greedy downlink-uplink client pairing.
A Palladium/Light System Combined with Hanztsch Ester: Radical Vinylation of Alkyl Iodides with Vinyl Bromides
(2017-04-01)
Sumino, Shuhei
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Ryu, Ilhyong
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應用化學系
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Department of Applied Chemistry
Radical vinylation of alkyl iodides with vinyl bromides proceeds smoothly with a combined Pd/light/Hanztschester system. In this reaction system, the Hanztsch ester acts as an effective reducing reagent of Pd-II to Pd-0 that generates key alkyl radicals via single electron transfer (SET) with alkyl iodides upon photo-excitation.
Diversity-Oriented Synthesis of Coumarin-Linked Benzimidazoles via a One-Pot, Three-Step, Intramolecular Knoevenagel Cyclization
(2017-04-01)
Yao, Po-Hsin Eric
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Kumar, Sunil
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Liu, Yu-Li
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Fang, Chiu-Ping
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Liu, Chia-Chen
Diversity-oriented synthesis of coumarin-linked benzimidazoles from N-(2-aminophenyl)-2-cyanoacetamide was achieved via a one-pot, three-step sequential reaction in excellent. yields. In situ intramolecular cyclization of the cyanoacetamide afforded benzimidazoles which subsequently underwent a Knoevenagel condensation of the 2-cyanome-thylbenzimidazoles with salicylaldehydes promoted by triethylamine to reach the target compounds. An important intermediate, 2-(2-imino-2H-chromen-3-yl)-1H-benzimidazole was characterized by X-ray analysis and further hydrolyzed to 2-(coumarin-3-yl)benzimidazole in acidic condition. Among the synthesized compounds, some were found to be promising inhibitors of porcine kidney D-amino acid oxidase (pkDAO).