Browsing by Issue Date, starting with "2015-06-23"

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Phosphorus-Doped p-n Homojunction ZnO Nanowires: Growth Kinetics in Liquid and Their Optoelectronic Properties
(2015-06-23)
Lee, Wei-Che
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Chen, Jul-Yuan
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Huang, Chun-Wei
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Chiu, Chung-Hua
;
Lin, Ting-Yi
For wide-ranging applications in nanoscale electronic devices, durable and reproducible p-type nanostructures are essential. In this work, simple ZnO nano-wire (NW) p-n homojunctions were grown using a two-step hydrothermal synthesis method. P2O5 served as a doping source to obtain p-type ZnO NW\'s. The morphology of the ZnO NW arrays was examined using field emission scanning electron microscopy. The high-resolution transmission electron microscopy (HRTEM) image indicated that the ZnO NW p-n homojunction is single-crystalline with a < 0001 > growth direction. The distribution of P element was analyzed using energy-dispersive spectroscopy. The dynamic growth observation was conducted using liquid in situ TEM to investigate the ZnO nucleation and growth mechanism. We divided the ZnO nanocrystal precipitation into three processes. Whether two adjacent particles grow stably or not was found to be related to the distance. Moreover, the temperature-dependent photoluminescence spectra revealed that two extra emission peaks located at 416 and 435 nm were emitted from the ZnO NW p-n homojunction, which resulted from donor-acceptor recombination. In addition, the electron transport properties confirmed the rectification behavior of the multi ZnO NW p-n homojunctions. The turn-on voltage and the current were approximately 2.8 V and 10(-4) to 10(-5) A, respectively, under forward bias. The results indicate the potential application of ZnO NW p-n homojunctions as nanoscale light-emitting diodes.
Tailoring low-dimensional structures of bismuth on monolayer epitaxial graphene
(2015-06-23)
Chen, H. -H.
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Su, S. H.
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Chang, S. -L.
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Cheng, B. -Y.
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Chen, S. W.
To improve graphene-based multifunctional devices at nanoscale, a stepwise and controllable fabrication procedure must be elucidated. Here, a series of structural transition of bismuth (Bi) adatoms, adsorbed on monolayer epitaxial graphene (MEG), is explored at room temperature. Bi adatoms undergo a structural transition from one-dimensional (1D) linear structures to two-dimensional (2D) triangular islands and such 2D growth mode is affected by the corrugated substrate. Upon Bi deposition, a little charge transfer occurs and a characteristic peak can be observed in the tunneling spectrum, reflecting the distinctive electronic structure of the Bi adatoms. When annealed to similar to 500 K, 2D triangular Bi islands aggregate into Bi nanoclusters (NCs) of uniform size. A well-controlled fabrication method is thus demonstrated. The approaches adopted herein provide perspectives for fabricating and characterizing periodic networks on MEG and related systems, which are useful in realizing graphene-based electronic, energy, sensor and spintronic devices.
Photon doughnut-shaped pair for easy production of entangled photon pairs
(2015-06-29)
Lo, Hsin-Pin
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Yabushita, Atsushi
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Kobayashi, Takayoshi
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電子物理學系
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Department of Electrophysics
Parametric down-conversion in a nonlinear crystal-generated photon pair in which photons have orthogonal polarization. The pair was emitted in a cone shape for each polarization and collimated by a lens to be doughnut shaped. The doughnutlike photon pair runs collinear to the pump laser. The group delay and walk-off between the orthogonal polarization photons in the pair were compensated passing through a half-wave plate and a nonlinear crystal. Then, the photon doughnut pair was coupled into a 1 x 2 fiber together with a pump laser, i.e., the intense pump laser was used as a guide for alignment. After the alignment was finished, a cut filter was inserted in the optical path to cut the pump laser transmitting the photon doughnut pair. The coincidence measurement of the output of the 1 x 2 fiber showed that the photon pairs are entangled in polarization.
Electrically tunable microlens arrays based on polarization-independent optical phase of nano liquid crystal droplets dispersed in polymer matrix
(2015-06-29)
Yu, Ji Hoon
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Chen, Hung-Shan
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Chen, Po-Ju
;
Song, Ki Hoon
;
Noh, Seong Cheol
Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast similar to 5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality. (C) 2015 Optical Society of America
On-line monitoring of Soxhlet extraction by chromatography and mass spectrometry to reveal temporal extract profiles
(2015-06-30)
Chen, Ssu-Ying
;
Urban, Pawel L.
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應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
Soxhlet extraction is a popular sample preparation technique used in chemical analysis. It enables liberation of molecules embedded in complex matrices (for example, plant tissues, foodstuffs). In most protocols, samples are analyzed after the extraction process is complete. However, in order to optimize extraction conditions and enable comparisons between different types of extraction, it would be desirable to monitor it in real time. The main development of this work is the design and construction of the interface between Soxhlet extractor and GC-MS as well as ESI-MS system. The temporal extract profiles, obtained in the course of real-time GC-MS monitoring, have been fitted with mathematical functions to analyze extraction kinetics of different analytes. For example, the mass transfer coefficients of pinene, limonene and terpinene in lemon sample, estimated using the first-order kinetic model, are 0.540 h(-1), 0.507 h(-1) and 0.722 h(-1), respectively. On the other hand, the Peleg model provides the following extraction rates of pinene, limonene and terpinene: 0.370 nM h(-1), 0.216 nM h(-1) and 0.596 nM h(-1), respectively. The results suggest that both first-order kinetic and Peleg equations can be used to describe the progress of Soxhlet extraction. On-line monitoring of Soxhlet extraction reveals extractability of various analytes present in natural samples (plant tissue), and can potentially facilitate optimization of the extraction process. (C) 2015 Elsevier B.V. All rights reserved.
Delirium, Subsyndromal Delirium, and Cognitive Changes in Individuals Undergoing Elective Coronary Artery Bypass Graft Surgery
(2015-07-01)
Li, Hsiu-Ching
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Chen, Yih-Sharng
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Chiu, Ming-Jang
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Fu, Mei-Chiung
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Huang, Guan-Hua
Background: The course of incident delirium and subsyndromal delirium (SSD) after cardiac surgery is not well studied. Objective: The aim of this study was to evaluate the course of incident delirium and SSD, their risk factors, and impact on patients\' cognitive function after elective coronary artery bypass graft (CABG) surgery. Methods: Consecutive patients scheduled for an isolated CABG at a tertiary medical center in Taiwan were enrolled if they had no preoperative delirium symptoms. Delirium was assessed daily for 1 week after surgery using the Confusion Assessment Method. Subsyndromal delirium was defined as presenting with any core symptom below the diagnostic threshold for delirium. Cognitive function was assessed by the Mini-mental State Examination. Results: Of 38 participants, 7 had incident (first-time) delirium (18.4% incidence) and 13 had incident SSD (34.2% incidence). Whereas SSD usually lasted 1 day, delirium changed gradually to SSD to recovery and its symptomatology lasted longer. We identified 6 delirium risk factors: older age, more comorbidities, cardiac pulmonary bypass, blood transfusion, larger transfusion volume, and longer duration of intraoperative blood pressure less than 60 mm Hg. The frequencies of these risk factors for SSD were often intermediate between those of risk factors in groups with and without delirium. By hospital discharge, participants with delirium had the longest hospital stays and lowest cognitive scores, those with SSD had intermediate stays and scores, and those without delirium had the lowest stays and scores. Conclusion: Delirium and SSD after CABG are common. Greater number and severity of risk factors for delirium may predict increasingly poor outcomes, with the dose-response relationship between risk factors and outcomes for SSD intermediate between that for no symptoms and full delirium. Intervention trials are indicated, particularly for patients with a greater number and severity of predisposing and precipitating risk factors.
Investigation of no analogue-equalization and blue filter for 185 Mbps phosphor-LED wireless communication
(2015-07-01)
Yeh, C. H.
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Chow, C. W.
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Liu, Y. L.
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Chen, H. Y.
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Liu, Y.
In this demonstration, we first propose an optimal analogue front end circuit without employing pre-equalization (series peaking) to increase the modulation bandwidth of phosphor-LED in visible light communication (VLC) transmission. And there is no blue filter and post-equalization in the client side. Here, only using optimal adjustment of resistance (R), inductance (L), and capacitance (C) in bias-tee to compensate the impedance matching of phosphor-LED, nearly 32 MHz modulation bandwidth can be accomplished. Therefore, utilizing orthogonal frequency division multiplexed modulation with bit-loading algorithm in VLC system, 185 Mbps data rate can be achieved under a transmission distance of 80 cm.
An investigation of unsteady flow reversal of natural convection in vertical parallel plates by the modified local one-dimensional inviscid relations method
(2015-07-01)
Fu, Wu-Shung
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Huang, Shang-Hao
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Li, Chung-Gang
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機械工程學系
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Department of Mechanical Engineering
An unsteady flow reversal of natural convection in vertical parallel plates with an asymmetrically heated wall is investigated numerically. For clarifying the occurrence of flow reversal, the width of the plates is regarded as a variable, and the non-reflecting boundary condition is adopted at apertures. The methods of the Roe scheme, preconditioning and dual time stepping matching LUSGS are siinultaneously used to solve governing equations which are available for a low speed compressible flow problem. The flow reversal is observed under broad width situations and absent under narrow width situations. Distributions of the pressure differences at the apertures are revealed to indicate the occurrence of flow reversal. The present Nusselt numbers, which mean time and area-averaged ones, display relatively good agreement with those of the existing works. (C) 2015 Elsevier Ltd. All rights reserved.
具容忍變異字元線驅動抑制機制之隨機存取記憶體
(2015-07-01)
莊景德
;
林宜緯
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陳家政
;
石維強
一種隨機存取記憶體，包含：複數個列，每一該列包含複數個記憶單元及一對應的字元線；各該記憶單元包含一個用於儲存資料的閂鎖器以及至少一閘通電晶體，耦接於該閂鎖器、該對應字元線與一對應位元線之間；複數個字元線驅動器，每一該字元線驅動器包含一電源端、一驅動端、一輸入端及一驅動電晶體；該電源端接收一工作電壓，該驅動端耦接該些列的該些字元線的其中之一，該輸入端接收一解碼訊號，該驅動電晶體包含一控制端與兩通道端，分別耦接該輸入端、該驅動端與該電源端；至少一第一追隨電晶體，各該第一追隨電晶體對應該些字元線驅動器的其中之一，包含兩通道端；其中一通道端耦接該對應字元線驅動器的該電源端及該驅動端的其中之一；該第一追隨電晶體的電子特性追隨該對應字元線驅動器中該驅動電晶體的電子特性；以及至少一第二追隨電晶體，包含一通道端，耦接該第一追隨電晶體的該兩通道端的其中之一；該第二追隨電晶體的電子特性追隨該些記憶單元中該些閘通電晶體的電子特性。
ACE2 associated with pulmonary inflammation and MMPs activities in acute lung injury by bleomycin treatment
(2015-07-01)
Hsieh, W. -Y.
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Chuang, W. -H.
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Liu, F. -C.
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Lin, C. -S.
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生物科技學系
Reconfigurable Custom Functional Unit Generation and Exploitation for Multiple-Issue Processors
(2015-07-01)
Wu, I-Wei
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Shann, Jean Jyh-Jiun
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Chung, Chung-Ping
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資訊工程學系
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Department of Computer Science
Next-generation digital entertainment and mobile communication devices are anticipated to require greater processor performance. To meet these demands, several researchers have attached a reconfigurable hardware accelerator to the base processor core. The reconfigurable hardware accelerator, termed a reconfigurable customized functional unit (RCFU), is usually realized by multiple processing elements (PE) organized in matrix form. The structure of the RCFU is generated from hot operation patterns of specific applications. Other than the RCFU, \'multiple-issue\' is another microarchitectural technique to increase the performance. However, the impact of combining both of these approaches in the same design is not yet well understood. This problem motivates us to design RCFU generation and exploitation algorithms for a multiple-issue processor. To allow more operations to execute on the RCFU simultaneously, the proposed generation algorithm merges several data-independent operation patterns to construct the RCFU architecture. To schedule operations on both the RCFU and functional units (FU) of the base processor core simultaneously, the proposed exploitation algorithm presents a model to represent all available computing resources from both the FUs of the base processor and the PEs in the RCFU. Using this model, the RCFU exploitation problem can be considered as an instruction-scheduling problem. Our experiment achieves an average improvement in execution performance of 50% compared with previous efforts [2, 5].
60-GHz Polarization-Adjustable Antenna Arrays
(2015-07-01)
Chi, Yu-Jen
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Chen, Fu-Chiarng
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電機工程學系
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Department of Electrical and Computer Engineering
This paper proposes 2 x 2 and 4 x 4 polarization-adjustable millimeter-wave antenna arrays. The antennas were designed to function at 60 GHz and are planar and vialess. The proposed antenna designs contain two input ports; if the input phases and magnitudes of the two input ports can be controlled, enabling the proposed antenna to generate six types of polarization: right-handed circular polarization, left-handed circular polarization, and linear polarization along the phi = 0 degrees, phi = 45 degrees, phi = 90 degrees, and phi = 135 degrees axes. The achieved antenna gain of the 2 x 2 polarization diversity array was approximately 12 dBi, whereas that of the 4 x 4 array was 16 dBi. Prototypes of both the 2 x 2 and 4 x 4 arrays were fabricated and tested. The operating mechanism and design steps are described in detail in this paper.
A Miniature Magnetic-Piezoelectric Thermal Energy Harvester
(2015-07-01)
Chen, Chin-Chung
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Chung, Tien-Kan
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Tseng, Chia-Yuan
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Hung, Chiao-Fang
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Yeh, Po-Chen
In this paper, we report a miniature thermal energy harvester with a novel magnetic-piezoelectric design. The harvester consists of a soft magnetic Gd cantilever beam, a piezoelectric lead zirconate titanate sheet, an NdFeB hard magnet, silicon clamps, and a silicon frame. In this design, the harvester is driven by a temperature difference between a cold side and room temperature ambient air, unlike other magnetic-piezoelectric thermal energy harvesters that are driven by a temperature difference between a cold side and a hot side or between two hot sides. Experimental results show that with a temperature difference of 20 degrees C (cold side: 6.7 degrees C, hot side: 26.7 degrees C), the harvester produces a maximum peak-to-peak voltage of 37 mV and a root mean square voltage of 1.98 mV. The estimated maximum instantaneous power density and average power density is 21.7 nW/cm(3) and 62.9 pW/cm(3), respectively. Moreover, the total volume of our harvester (length x width x height: 6 x 3.5 x 3 mm) is 217 times lower than that of previous experimental harvesters and 38 times smaller than that of previous theoretical-modeled harvesters. Therefore, our harvester is the smallest machined magnetic-piezoelectric thermal energy harvester designed to date. These features enable our harvester to be more easily implemented and integrated with micro wireless sensors and thereby increase more self-powered wireless-sensing applications.
Prioritized Optimal Channel Allocation Schemes for Multi-Channel Vehicular Networks
(2015-07-01)
Chu, Jui-Hung
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Feng, Kai-Ten
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Lin, Jia-Shi
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電機資訊學士班
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Undergraduate Honors Program of Electrical Engineering and Computer Science
The IEEE 1609.4 standard has been proposed to provide multi-channel operations in wireless access for vehicular environments (WAVE), where all channels are periodically synchronized into control and service intervals. Communication device in each vehicle will stay at the control channel for negotiation and contention during the control interval, and thereafter switch to one of the service channels for data transmission in the service interval. In this paper, based on the concept of cognitive radio (CR), the vehicles are categorized into primary providers (PPs) that intend to transmit safety-related messages and secondary providers (SPs) with non-safety information to be delivered. The prioritized optimal channel allocation (POCA) approaches are proposed to improve channel utilization of IEEE 1609.4 standard for multi-channel vehicular networks. Prioritized channel access is analyzed in the POCA schemes in order to increase the transmission opportunity of PPs. Moreover, depending on whether the CR network is distributed or centralized, the optimal channel-hopping sequence and optimal channel allocation is assigned for SPs based on dynamic programming and linear programming technique, respectively. These schemes are designed to consider optimal load balance between both channel availability and channel utilization within the throughput constraints of PPs. With the adoption of proposed POCA schemes, simulation results show that maximum throughput of SPs can be achieved with guaranteed quality-of-service requirement for PPs.
The impact of customer experience and perceived value on sustainable social relationship in blogs: An empirical study
(2015-07-01)
Chen, Shih-Chih
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Lin, Chieh-Peng
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經營管理研究所
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Institute of Business and Management
Blogs are currently powerful instrument and their proliferation has attracted substantial attention from marketing practitioners and academics. The aim of this study is to propose a model to understand and examine during the formation of sustainable social relationships and the continued usage of blogs in marketing contexts. Two exogenous constructs - customer experience and perceived value - have not only directly influenced satisfaction and intention to continue to use blogs, but also indirectly affected customers\'/citizens\' sustainable social relationship with blogs through the mediation of satisfaction and continuance intention. The analysis results herein demonstrate that sustainable social relationship is determined significantly by continuance intention and satisfaction toward blogs, while the influences of customer experience and perceived value on continuance intention are both respectively significant. However, the direct influence of customer experience on continuance intention is insignificant In addition, this study examined and empirically confirmed the mediating role of continuance intention and satisfaction on blogs between customer experience and perceived value. Finally, the findings of this research propose the detailed theoretical and managerial implications for academicians, blog operators and government agencies. (C) 2014 Elsevier Inc. All rights reserved.
Sparsity Enhanced Mismatch Model for Robust Intercell Interference Management in Heterogeneous Networks With Doubly-Selective Fading Channels
(2015-07-01)
Chang, Chieh-Yao
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Fung, Carrson C.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Transmission over doubly-selective fading (DSF) interference channel often relies on the use of robust precoder due to a lack of accurate channel state information, with performance often depending on the conservativeness of the mismatch model. Previously proposed mismatch models either have been deemed too conservative (deterministic models) or are prone to error due to inaccuracy in the probability density function (pdf) and corresponding parameters (stochastic models). A deterministic mismatch model called Sparsity Enhanced Mismatch Model-Reverse discrete prolate spheroidal sequence, or SEMMR, is proposed herein in an attempt to alleviate this problem. Different from all previously deterministic models, the proposed model exploits the inherent sparse characteristics of DSF interference channels which lead to a two-stage robust transceiver design that outperforms precoding only strategy incorporating conventional norm ball mismatch model (NBMM). The inherent sparsity in the channel is brought forth by modeling the channel using a basis expansion model (BEM) where discrete prolate spheroidal sequence (DPSS) is used as a basis. Analytical and simulation results are provided to validate the performance gains of the SEMMR transceiver over the NBMM precoder.
Innovative Fabrication of Wafer-Level InGaN-Based Thin-Film Flip-Chip Light-Emitting Diodes
(2015-07-01)
Chiang, Yen-Chih
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Lin, Bing-Cheng
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Chen, Kuo-Ju
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Lin, Chien-Chung
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Lee, Po-Tsung
In this letter, an innovative fabrication method for InGaN-based light-emitting diode (LED) was proposed, and the produced optical device was called the wafer-level InGaN-based thin-film flip-chip LEDs (wTFFC-LEDs). Packaging technologies, such as wafer-to-wafer bonding, laser lift-off, textured surface, and interconnection techniques, were applied to complete the device. Through this architecture, the absorption caused by electrodes in traditional vertical injection LEDs (V-LEDs) can be minimized, as well as the light extraction efficiency can be improved. Light-output power of wTFFC-LEDs (350 mA) was increased by 36.5% and 17.2% compared with the V-LEDs and flip-chip LEDs. Furthermore, the external quantum efficiency was also relatively enhanced by 36.3% and 15.5% higher than those of reference devices.
Angiotensin converting enzyme II deficiency accelerates the progression of COPD via irregular signaling STAT3 phosphorylation
(2015-07-01)
Hung, Y. -H.
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Hsieh, W. -Y.
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Hsieh, J. -S.
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Wu, C. -L.
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Lin, C. -S.
Sequence Conservation, Radial Distance and Packing Density in Spherical Viral Capsids
(2015-07-01)
Chang, Chih-Min
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Huang, Yu-Wen
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Lee, Chi-Wen
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Huang, Tsun-Tsao
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Shih, Chung-Shiuan
The conservation level of a residue is a useful measure about the importance of that residue in protein structure and function. Much information about sequence conservation comes from aligning homologous sequences. Profiles showing the variation of the conservation level along the sequence are usually interpreted in evolutionary terms and dictated by site similarities of a proper set of homologous sequences. Here, we report that, of the viral icosahedral capsids, the sequence conservation profile can be determined by variations in the distances between residues and the centroid of the capsid - with a direct inverse proportionality between the conservation level and the centroid distance - as well as by the spatial variations in local packing density. Examining both the centroid and the packing density models against a dataset of 51 crystal structures of nonhomologous icosahedral capsids, we found that many global patterns and minor features derived from the viral structures are consistent with those present in the sequence conservation profiles. The quantitative link between the level of conservation and structural features like centroid-distance or packing density allows us to look at residue conservation from a structural viewpoint as well as from an evolutionary viewpoint.
電性連接結構及其製備方法
(2015-07-01)
陳智
;
劉道奇
;
黃以撒
;
劉健民
一種用以電性連接一第一基板及一第二基板之電性連接結構之製備方法，包括下列步驟：(A)提供一第一基板及一第二基板，其中該第一基板上係設有一第一銅膜，該第二基板上係設有一第一金屬膜，該第一銅膜之一第一接合面係為一含(111)面之接合面，且該第一金屬膜具有一第二接合面；以及(B)將該第一銅膜及該第一金屬膜相互接合以形成一接點，其中該第一銅膜之該第一接合面係與該第一金屬膜之該第二接合面相互對應。