Browsing by Issue Date, starting with "2017-03-30"

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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
;
Cheng, Hui-Yu
;
Chen, Wei-Liang
;
Huang, Yi-Hsin
;
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
;
Zhang, Zhiyue
;
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
;
Kuan, Yen-Cheng
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Li, Yilei
;
Hu, Boyu
;
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
;
Fang, Chiu-Ping
;
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).
Eager Synching: A Selective Logging Strategy for Fast fsync() on Flash-Based Android Devices
(2017-04-01)
Chang, Li-Pin
;
Sung, Po-Han
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Chen, Po-Tsang
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Chen, Po-Hung
;
資訊工程學系
Flash storage has been a standard component in Android devices. Recent research has reported that application data management in Android involves frequent fsync() operations. The current fsync() implementations, including those of ext4 and F2FS, have several common drawbacks. Specifically, ext4 commits a transaction every time to sync a file, whereas F2FS commits a checkpoint to sync a directory. Committing a transaction or checkpoint flushes all dirty data from the page cache to the flash storage via many small, random block write requests. The resultant high I/O frequency and excessive write traffic cause a high fsync() latency. This study presents an efficient fsync() method, called eager synching, which is based on a simple idea: write less, and write sequentially. To sync a file, eager synching writes only a subset of all dirty data in the page cache to a sequential log space using a few sequential block write requests. It does not involve transaction or checkpoint committing. We successfully implemented eager synching in ext4 and F2FS, and our experimental results show that, compared with the original fsync() methods of ext4 and F2FS, eager synching reduced the average and maximum fsync() latencies by up to 72% and 91%, respectively, block-level write traffic by up to 35%, and I/O frequency by up to 66%. Through enhanced crash recovery procedures, eager synching can successfully recover all previously synched files while still guaranteeing the file system integrity. We also conducted live application replays using the proposed eager synching approach and observed that this approach significantly improved the application frame updating rate and application execution time.
Conductive nanogel-interfaced neural microelectrode arrays with electrically controlled in-situ delivery of manganese ions enabling high-resolution MEMRI for synchronous neural tracing with deep brain stimulation
(2017-04)
Huang, Wei-Chen
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Lo, Yu-Chih
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Chu, Chao-Yi
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Lai, Hsin-Yi
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Chen, You-Yin
Chronic brain stimulation has become a promising physical therapy with increased efficacy and efficiency in the treatment of neurodegenerative diseases. The application of deep brain electrical stimulation (DBS) combined with manganese-enhanced magnetic resonance imaging (MEMRI) provides an unbiased representation of the functional anatomy, which shows the communication between areas of the brain responding to the therapy. However, it is challenging for the current system to provide a real-time high-resolution image because the incorporated MnCl2 solution through microinjection usually results in image blurring or toxicity due to the uncontrollable diffusion of Mn2+. In this study, we developed a new type of conductive nanogel-based neural interface composed of amphiphilic chitosan-modified poly(3,4 -ethylenedioxythiophene) (PMSDT) that can exhibit biomimic structural/mechanical properties and ionic/electrical conductivity comparable to that of Au. More importantly, the PMSDT enables metal-ligand bonding with Mn2+ ions, so that the system can release Mn2+ ions rather than MnCl2 solution directly and precisely controlled by electrical stimulation (ES) to achieve real-time high resolution MEMRI. With the integration of PMSDT nanogel-based coating in polyimide-based micro electrode arrays, the post-implantation DBS enables frequency-dependent MR imaging in vivo, as well as small focal imaging in response to channel site-specific stimulation on the implant. The MR imaging of the implanted brain treated with 5-min electrical stimulation showed a thalamocortical neuronal pathway after 36 h, confirming the effective activation of a downstream neuronal circuit following DBS. By eliminating the susceptibility to artifact and toxicity, this system, in combination with a MR-compatible implant and a bio-compliant neural interface, provides a harmless and synchronic functional anatomy for DBS. The study demonstrates a model of MEMRI-functionalized DBS based on functional neural interface engineering and controllable delivery technology, which can be utilized in more detailed exploration of the functional anatomy in the treatment of neurodegenerative diseases. (C) 2017 Elsevier Ltd. All rights reserved.
SOLVING ROUTING AND WAVELENGTH ASSIGNMENT PROBLEM WITH MAXIMUM EDGE-DISJOINT PATHS
(2017-04-01)
Hsu, Chia-Chun
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Cho, Hsun-Jung
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Fang, Shu-Cherng
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
The routing and wavelength assignment (RWA) problem in wavelength-division multiplexing optical networks is critically important for increasing the efficiency of wavelength-routed all-optical networks. Given the physical network structure and a set of connection requests, the problem aims to establishing routes for the requests and assigning a wavelength to each of them, subject to the wavelength continuous and wavelength clash constraints. The objective is to minimize he number of required wavelengths to satisfy all requests. The RWA problem was proven to be NP-hard and has been investigated for decades. In this paper, an algorithm based on the maximum edge-disjoint paths is proposed to tackle the RWA problem. Its performance is verified by experiments on some realistic network topologies. Compared with the state-of-the-art bin-packing based methods and the particle swarm optimization al- gorithm, the proposed method can find the best solution among all testing instances in reasonable computing time.
Local co-administration of gene-silencing RNA and drugs in cancer therapy: State-of-the art and therapeutic potential
(2017-04-01)
Larsson, Mikael
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Huang, Wei-Ting
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Liu, Dean-Mo
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Losic, Dusan
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材料科學與工程學系
Gene-silencing miRNA and siRNA are emerging as attractive therapeutics with potential to suppress any genes, which could be especially useful in combination cancer therapy to overcome multidrug resistant (MDR) cancer. Nanomedicine aims to advance cancer treatment through functional nanocarriers that delivers one or more therapeutics to cancer tissue and cells with minimal off-target effects and suitable release kinetics and dosages. Although much effort has gone into developing circulating nanocarriers with targeting functionality for systemic administration, another alternative and straightforward approach is to utilize formulations to be administered directly to the site of action, such as pulmonary and intratumoral delivery. The combination of gene-silencing RNA with drugs in nanocarriers for localized delivery is emerging with promising results. In this review, the current progress and strategies for local co-administration of RNA and drug for synergistic effects and future potential in cancer treatment are presented and discussed. Key advances in RNA-drug anticancer synergy and localized delivery systems were combined with a review of the available literature on local co-administration of RNA and drug for cancer treatment. It is concluded that advanced delivery systems for local administration of gene-silencing RNA and drug hold potential in treatment of cancer, depending on indication. In particular, there are promising developments using pulmonary delivery and intratumoral delivery in murine models, but further research should be conducted on other local administration strategies, designs that achieve effective intracellular delivery and maximize synergy and feasibility for clinical use. (C) 2017 Elsevier Ltd. All rights reserved.
Alain Brossat與陳光興對話：關於「亞洲作為方法」及其他－編案
(深河出版有限公司, 2017-04-01)
人間思想編輯部
A comprehensive study on the oxidation of 4H-SiC in diluted N2O ambient
(2017-04-01)
Tseng, Yuan-Hung
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Wu, Tsung-Han
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Tsui, Bing-Yue
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Yen, Cheng-Tyng
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Hung, Chien-Chung
The oxidation mechanism of 4H-SiC in diluted N2O ambient was studied at various temperatures, N2O flow rates, and N-2/N2O flow ratios. The collision partner, N-2 in this study, plays crucial roles in determining the oxidation rate and N-incorporation. According to the proposed oxidation mechanism, lowering the interface state density at lower oxidation temperatures is possible with a high-efficiency collision partner. (C) 2017 The Japan Society of Applied Physics
Imbalanced Plasma ACE and ACE2 ratio in the Uremic Patients with Cardiovascular Diseases and Its Change during a Single Hemodialysis Session
(2017-04-01)
Cho, Ching-Chang
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Lu, Li-Che
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Chang, Chia-Chu
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Lin, Chung-I
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Wang, Guan-Hua
Characteristics of Cu2ZnSn(SXSe1-x)(4) thin-film solar cells prepared by sputtering deposition using single quaternary Cu2ZnSnS4 target followed by selenization/sulfurization treatment
(2017-04)
Lin, Yu-Pin
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Hsieh, Tsung-Eong
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Chen, Yen-Chih
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Huang, Kun-Ping
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材料科學與工程學系
This work demonstrates the preparation of Cu2ZnSn(SxSe1-x)(4)(CZTSSe) thin films by sputtering deposition using single-phase Cu2ZnSnS4 (CZTS) target followed by selenization/sulfurization treatment at 570 degrees C for 1 h. Afterward, the CZTSSe thin-film solar cell samples with the Mo/CZTSSe/CdS/i-ZnO/IZO/Al structure were prepared and their performances were evaluated. By varying the ratio of Se and S powders of heat treatment, the Cu-poor/Zn-rich CZTSSe layers with S/(S+Se) ratio in the range of 0.21-1 were achieved and the CZTSSe layers were the mixture of kesterite CZTS and CZTSe phases as revealed by the x-ray diffraction and the Raman spectroscopy analyses. UV-NIR spectroscopy indicated the bandgaps of CZTSSe samples are in the range of 1.06-1.45 eV when the S/(S+Se) ratio varies from 0.21 to 1. Hall measurement observed the best transport property with p-type carrier concentration of 2.17x10(15) cm(-3) and mobility of 8.9 cm(2) V-1 sec(-1) in CZTSSe layer with S/(S+Se) ratio of 0.46. Under the AM1.5 illumination condition, the CZTSSe thin-film solar cell sample with S/(S+Se) ratio of 0.46 exhibited the best performance with open-circuit voltage of 0.506 V, short-circuit current density of 27.41 mA/cm(2), fill factor of 50% and conversion efficiency of 6.9%.
Chiral Optical Tamm States: Temporal Coupled-Mode Theory
(2017-04-01)
Timofeev, Ivan V.
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Pankin, Pavel S.
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Vetrov, Stepan Ya.
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Arkhipkin, Vasily G.
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Lee, Wei
The chiral optical Tamm state (COTS) is a special localized state at the interface of a handedness-preserving mirror and a structurally chiral medium such as a cholesteric liquid crystal or a chiral sculptured thin film. The spectral behavior of COTS, observed as reflection resonances, is described by the temporal coupled-mode theory. Mode coupling is different for two circular light polarizations because COTS has a helical structure replicating that of the cholesteric. The mode coupling for co-handed circularly polarized light exponentially attenuates with the cholesteric layer thickness since the COTS frequency falls into the stop band. Cross-handed circularly polarized light freely goes through the cholesteric layer and can excite COTS when reflected from the handedness-preserving mirror. The coupling in this case is proportional to anisotropy of the cholesteric and theoretically only anisotropy in magnetic permittivity can ultimately cancel this coupling. These two couplings being equal result in a polarization crossover (the Kopp-Genack effect) for which a linear polarization is optimal to excite COTS. The corresponding cholesteric thickness and scattering matrix for COTS are generally described by simple expressions.
Suppression of Current Collapse in Enhancement Mode GaN-Based HEMTs Using an AIGaN/GaN/AIGaN Double Heterostructure
(2017-04-01)
Ho, Shin-Yi
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Lee, Chun-Hsun
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Tzou, An-Jye
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Kuo, Hao-Chung
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Wu, Yuh-Renn
Current collapse is a phenomenon that increases the channel resistance during the switching process when the high gate and drain voltages are applied. The effect can be found from GaN-based high electron mobility transistors (HEMTs) and is an obstacle for their applications to power electronics. There have been numerous reports on suppressing current collapse using semiconductor process technologies. In this paper, an enhancement mode (E-mode) AIGaN/GaN/AIGaN double heterostructure was proposed. The current collapse phenomena were studied on devices of E-mode MIS and Schottky gate HEMTs. The results indicate the suppression of current collapse for devices with double heterostructure.
Temperature- and doping-concentration-dependent characteristics of junctionless gate-all-around polycrystalline-silicon thin-film transistors
(2017-04-01)
Tso, Chia-Tsung
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Liu, Tung-Yu
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Pan, Fu-Ming
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Sheu, Jeng-Tzong
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材料科學與工程學系
The temperature effects of both gate-all-around polycrystalline silicon nanowire (GAA poly-Si NW) junctionless (JL) and inversion mode (IM) transistor devices at various temperatures (77-410 K) were investigated. The electrical characteristics of these devices, such as subthreshold swing (SS), threshold voltage (Vth), and drain-induced barrier lowering (DIBL), were also characterized and compared in this study. Moreover, JL devices with different doping concentrations at various temperatures were also discussed. Both Vth and I-on showed significant doping concentration dependences for JL devices with doping concentrations of 1 x 10(19) and 5 x 10(19) cm(-3). However, the electrical characteristics of JL devices showed less thermal sensitivity when the doping concentration reached 10(20) cm(-3) . (C) 2017 The Japan Society of Applied Physics
Speckle noise reduction in the laser mini-projector by vibrating diffuser
(2017-04-01)
Pan, Jui-Wen
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Shih, Chi-Hao
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光電系統研究所
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影像與生醫光電研究所
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Institute of Photonic System
We proposed a design for a laser mini-projector with a low speckle contrast value and high contrast ratio that maintains system efficiency. The key design is that two diffusers are located in the two sides of the light tunnel. By vibrating the 30 x 30 diffuser under 100 Hz, the speckle contrast value can be decreased to 2.32% which is invisible to the human eye. Considering the trade-off issue of optical efficiency and speckle noise, the most suitable arrangement with circular diffusers is '30 x 30H, 5 x 5. The vibration direction is at the long side of the light tunnel.