Browsing by Issue Date, starting with "2007-01-10"

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InGaAs quantum-well saturable absorbers for a diode-pumped passively Q-switched Nd : YAG laser at 1123 nm
(2007-01-10)
Huang, J. Y.
;
Liang, H. C.
;
Su, K. W.
;
Lai, H. C.
;
Chen, Y. -F.
A low-loss semiconductor saturable absorber based on InGaAs quantum wells was developed for highly efficient Q switching of a diode-pumped Nd:YAG laser operating at 1123 nm. With an incident pump power of 16 W, an average output power of 3.1 W with a Q-switched pulse width of 77 ns at a pulse repetition rate of 100 kHz was obtained. (c) 2007 Optical Society of America.
Dispersion-convolution model for simulating peaks in a flow injection system
(2007-01-12)
Pai, Su-Cheng
;
Lai, Yee-Hwong
;
Chiao, Ling-Yun
;
Yu, Tiing
;
應用化學系
A dispersion-convolution model is proposed for simulating peak shapes in a single-line flow injection system. It is based on the assumption that an injected sample plug is expanded due to a "bulk" dispersion mechanism along the length coordinate, and that after traveling over a distance ora period of time. the sample zone will develop into a Gaussian-like distribution. This spatial pattern is further transformed to a temporal coordinate by a convolution process, and finally a temporal peak image is generated. The feasibility of the proposed model has been examined by experiments with various coil lengths, sample sizes and pumping rates. An empirical dispersion coefficient (D*) can be estimated by using the observed peak position. height and area (t(p)(*), h* and A(t)(*)) from a recorder. An empirical temporal shift ((Phi*) can be further approximated by (Phi* = D*/u(2), which becomes an important parameter in the restoration of experimental peaks. Also, the dispersion coefficient can be expressed as a second-order polynomial function of the pumping rate Q, for which D*(Q) =delta(0) + delta(1)Q+delta(2)Q(2). The optimal dispersion occurs at a pumping rate of Q(opt) = root delta(0)/delta(.)(2) This explains the interesting "Nike-swoosh" relationship between the peak height and pumping rate. The excellent coherence of theoretical and experimental peak shapes confirms that the temporal distortion effect is the dominating reason to explain the peak asymmetry in flow injection analysis. (c) 2006 Elsevier B.V. All rights reserved.
Multiplex method for the measurement of nonlinear susceptibility spectrum applied to third-harmonic generation in a polydiacetylene
(2007-01-12)
Kobayashi, Takayoshi
;
Mito, Akihiro
;
Kobayashi, Satoshi
;
Taneichi, Takashi
;
Furuta, Atsuhiro
Broadband near-infrared pulse generated from NOPA (non-collinear optical parametric amplifier) was used for measurement of the spectrum of susceptibility of the third harmonic generation (THG). Corrections for the effects of absorption and refractive index, contribution of non-degenerate third-order nonlinearity, and THG by air, were properly addressed. This multiplex method was applied to a polydiacetylene, poly[5,7-dodecadiyn-1,12-diol-bis(n-butoxylcarbonyl-methyl-urethane)] (4BCMU) in red phase resulting in a good agreement with theoretical prediction. (c) 2006 Elsevier B.V. All rights reserved.
Mesoporous silica reinforced by silica nanoparticles to enhance mechanical performance
(2007-01-15)
Luo, Jen-Tsung
;
Wen, Hua-Chiang
;
Chang, Yu-Ming
;
Wu, Wen-Fa
;
Chou, Chang-Pin
Silica nanoparticle/mesoporous silica composite films were prepared by direct mixing with mechanical stirring and thermal imidization. The structural morphology was elucidated by scanning electron microscopy and the surface of the film was imaged by atomic force microscopy. The functional groups and desorption process of the films were elucidated by Fourier transform infrared spectroscopy and thermal desorption spectroscopy. The mechanical properties were investigated using a nanoindenter system. The gel matrix and the filler are very compatible because they have similar molecular content. The composite films had a higher mechanical strength than pure porous silica film. Their strength is related to the silica nanoparticle content. The interfacial compatibility, dispersion effect, and interfacial strength also affect the mechanical strength of composite films. (c) 2006 Elsevier Inc. All rights reserved.
Comparison of amperometric biosensors fabricated by palladium sputtering, palladium electrodeposition and Nafion/carbon nanotube casting on screen-printed carbon electrodes
(2007-01-15)
Lee, Chung-Hun
;
Wang, Shih-Chang
;
Yuan, Chiun-Jye
;
Wen, Meng-Fang
;
Chang, Ku-Shang
Different strategies, including palladium electrodeposition (Pd-CV), I'd sputtering (Pd-S) and Nafion-solubilized carbon nanotube casting (Nafion/CNT), were used to modify screen-printed carbon electrodes (SPCEs) for the fabrication of amperometric enzyme biosensors. The electrochemical properties of the bare and modified SPCEs and the optimal conditions for surface modification were determined. The electrochemical response of the bare SPCE to H2O2 under the potential of 0.3 V could be improved about 100-fold by Pd modification by electrodeposition or sputtering. By contrast, the electrochemical response of the bare SPCE was enhanced by only about 11-fold by Nafion/CNT casting. Moreover, the Pd-CV-SPCEs exhibited better reproducibility of electrochemical response (a relative standard deviation (R.S.D.)< 6.0%) than freshly prepared Pds-SPCEs (R.S.D. > 10%). The glucose biosensor fabricated from Pd-modified electrodes could be stored for up to 108 days without loosing significant activity. The Pd-CV-SPCE also showed very reliable signal characteristics upon 50 consecutively repeated measurements of ascorbic acid. The electrocatalytic detection of the Pd-SPCE was combined with additional advantages of resistance to surface fouling and hence good stability. In conclusion, this study demonstrated that deposition of Pd thin film on SPCEs by electrodeposition or sputtering provided superior enhancement of electrochemical properties compared to Nafion/CNT-SPCEs. Despite their high electrochemical response, Pds-SPCEs required an activation process to improve stability and Pd-CV-SPCEs suffered from poor between electrode reproducibility. (c) 2006 Elsevier B.V. All rights reserved.
Low-temperature growth of ZnO nanorods in anodic aluminum oxide on Si substrate by atomic layer deposition
(2007-01-15)
Yang, Ching-Jung
;
Wang, Shun-Min
;
Liang, Shih-Wei
;
Chang, Yung-Huang
;
Chen, Chih
Low-temperature growth of self-organized ZnO nanorods on Si substrate is achieved using anodic aluminum oxide and atomic layer deposition at 250 degrees C without catalyst or seed layer. Photoluminescence spectrum indicates that the ZnO nanorod arrays exhibit a blue/green luminescence at 480 nm. In addition, the nanorod arrays demonstrate excellent field-emission properties with a turn-on electric field of 6.5 V mu m(-1) and a threshold electric field of 9.8 V mu m(-1), which are attributed to the perfectly perpendicular alignment of ZnO nanorods to the Si substrate. (c) 2007 American Institute of Physics.
An improved method for haptoglobin 1-1, 2-1, and 2-2 purification using monoclonal antibody affinity chromatography in the presence of sodium dodecyl sulfate
(2007-01-15)
Yueh, Sunny C. H.
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Lai, Yi An
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Chen, Wen Liang
;
Hsu, Hsiao Han
;
Mao, Simon J. T.
Human haptoglobin (Hp) is classified as three phenotypes: Hp 1-1, 2-1, and 2-2. Previously, we had isolated this protein by affinity columns using either hemoglobin or monoclonal antibody (mAb) prepared against Hp beta-chain (clone 8B1-3A). The isolated Hp from both methods, however, contaminates plasma apolipoprotein A-I (apoA-I). In the present report, we have developed a novel affinity column procedure using an mAb prepared against a-chain of Hp (clone 3H8) for Hp purification. Plasma was first chromatographed onto the column followed by a normal wash with a buffer containing 0.12 M NaCl and 0.02 M phosphate, pH 7.4 (PBS). The bound proteins were then prewashed with a 0.04% sodium dodecyl sulfate (SDS)-PBS, pH 7.4, to remove the low-affinity bound apoA-I from Hp. Finally, the bound Hp was eluted with a 0.1% SDS-PBS, pH 11, and collected in tubes containing 1 M Tris-HC1, pH 6.8. As a result, the isolated Hp was devoid of apoA-1 and was able to retain the biological function by forming an Hp-hemoglobin complex. The homogeneity of each isolated Hp 1-1, 2-1, or 2-2 was greater than 95% with an yield greater than 50%. The procedure described here is significantly improved in time consumption, recovery, and purity. The rationale, design, and optimization for each step are described in detail. (c) 2006 Elsevier B.V. All rights reserved.
Mutagenesis and mechanistic study of a glycoside hydrolase family 54 alpha-L-arabinofuranosidase from Trichoderma koningii
(2007-01-15)
Wan, Chin-Feng
;
Chen, Wei-Hong
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Chen, g-Ta Chen
;
Chang, Margaret Dah-Tsyr
;
Lo, Lee-Chiang
A GH (glycoside hydrolase) family 54 alpha-L-arabinofuranosidase from Trichoderma koningii G-39 (termed Abf) was successfully expressed in Pichia pastoris and purified to near homogeneity by cation-exchange chromatography. To determine the amino acid residues essential for the catalytic activity of Abf, extensive mutagenesis of 24 conserved glutamate and aspartate residues was performed. Among the mutants, D221N, E223Q and D299N were found to decrease catalytic activity significantly. The k(cat) values of the D221N and D299N mutants were 7000- and 1300-fold lower respectively, than that of the wild-type Abf. E223Q was nearly inactive. These results are consistent with observations obtained from the Aspergillus kawachii alpha-L-arabinofuranosidase three-dimensional structure. This structure indicates that ASp(221) of T. koningii Abf is significant for substrate binding and that Glu(223) as well as Asp(211) function as a nucleophile and a general acid/base catalyst for the enzymatic reaction respectively. The catalytic mechanism of wild-type Abf was further investigated by NMR spectroscopy and kinetic analysis. The results showed that Abf is a retaining enzyme. It catalyses the hydrolysis of various substrates via the formation of a common intermediate that is probably an arabinosyl-enzyme intermediate. A two-step, double-displacement mechanism involving first the formation, and then the breakdown, of an arabinosyl-enzyme intermediate was proposed. Based on the k(cat) values of a series of aryl-alpha-L-arabinofuranosides catalytically hydrolysed by wild-type Abf, a relatively small Br phi nsted constant, beta(lg) = -0.18, was obtained, suggesting that the rate-limiting step of the enzymatic reaction is the dearabinosylation step. Further kinetic studies with the D299G mutant revealed that the catalytic activity of this mutant depended largely on the pK(a) values (> 6) of leaving phenols, with beta(lg) = -1.3, indicating that the rate-limiting step of the reaction becomes the arabinosylation step. This kinetic outcome supports the idea that Asp(299) is the general acid/base residue. The pH activity profile of D299N provided further evidence strengthening this suggestion.
A study on the critical success factors for corporations embarking on knowledge community-based e-learning
(2007-01-15)
Chen, Ruey-Shun
;
Hsiang, Chin-Hsiao
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
Corporations have felt the pressure for fast-paced innovations and knowledge transfer as major driving forces in raising their sustainable competitive advantage and organizational total productivity. Thus, the development of the knowledge community through e-learning is an important strategy in implementing knowledge management policy. This paper illustrates an empirical study with which to conduct qualitative research of learning organization. From the case company's real progress and practical experience, some core principles were extracted from four managerial aspects, such as: strategy, technology, process, and personnel. These aspects were analyzed in order to understand the value chain framework and the major concerns of knowledge community development. Further, the main benefits are addressed and certain critical factors are proposed and shown in this paper to ensure the success of corporations embarking on knowledge community-based e-learning. (C) 2006 Elsevier Inc. All rights reserved.
Effect of growth conditions on the Al composition and quality of AlGaN film
(2007-01-15)
Huang, G. S.
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Yao, H. H.
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Kuo, H. C.
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Wang, S. C.
;
光電工程學系
Effects of growth conditions on Al composition and quality of AlxGa1-xN epilayer grown by low-pressure matelorganic vapor phase epitaxy (MOVPE) have been investigated. The dependences of Al composition, growth rate and quality on the NH3 flow rate, TMAl flow rate and growth temperature were studied. The Al composition and quality of AlxGa1-xN film depend not only on the TMAl flow rate, but also on the NH3 flow rate and on the growth temperature. The Al composition of AlxGa1-xN film becomes saturated when the gas-phase composition TMAl/(TMAl + TMGa) increases to 0.4, while quality of AlxGa1-xN film becomes much worse. The Al composition of AlxGa1-xN film increases with increase in the NH3 flow rate. The quality of AlxGa1-xN epilayer is improved when the growth temperature increases. Possible Al incorporation mechanism is discussed. (c) 2006 Elsevier B.V. All rights reserved.
Effect of substituents on the photoluminescent and electroluminescent properties of substituted cyclometalated iridium(III) complexes
(2007-01-15)
Hong, Hsiao-Wen
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Chen, Teng-Ming
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應用化學系
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Department of Applied Chemistry
The photophysics of octahedral 4d(6) and 5d(6) Complexes has been studied extensively. The d(6) iridium(III) complexes show intense phosphorescence at room temperature. Our goal of this research is to study the synthesis, characterization and applications of the light emitting dopants based on iridium(III) complexes. We have prepared and characterized a series of substituted (4-CF3, 4-Me, 4-OMe, 4-F, 3-F) 2-phenylbenzoxazole ligand. The intermediate di-irrido and the six-coordinated mononuclear iridium(III) dopants of the above ligands have been synthesized and characterized. These complexes are thermally stable between 280-320 degrees C depending upon the substituents and sublimable. They emit bright yellow to green light. The peak emission wavelengths of the dopants can be finely tuned depending upon the electronic properties of the substituents as well as their positions in the ring. The emission spectral diagrams show that the emissive states of the complexes have major contribution of MLCT state. In the absorption spectra, the (MLCT)-M-1 and (MLCT)-M-3 transitions have been resolved in the range, 385-500 nm. The physical parameters of the electroluminescent devices for the substituted and the unsubstituted complexes has been compared and discussed. (c) 2006 Elsevier B.V. All rights reserved.
On-the-fly TCP path selection algorithm in access link load balancing
(2007-01-15)
Lin, Ying-Dar
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Tsao, Shih-Chiang
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Leong, Un-Pio
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資訊工程學系
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Department of Computer Science
Many enterprises install multiple access links for fault tolerance or bandwidth enlargement. Dispatching connections through good links is the ultimate goal in utilizing multiple access links. The traditional dispatching method is only based on the condition of the access links to ISPs. It may achieve fair utilization on the access links but poor performance on connection throughput. In this work, we propose a novel approach to maximize the per-connection end-to-end throughput by the on-the-fly round trip time (RTT) probing mechanism. The end-to-end RTTs through all possible links are probed by duplicating the SYN packet during the three-way handshaking stage of a TCP connection. The experiment results show that the ratio to choose the best outgoing access link is 79% on the average. If the second best link is chosen, it is usually very close to the best, thus averagely achieving 94% of the maximum possible throughput. The ratio of the traditional round-robin (RR) algorithm is only 35%, and the link selected by RR algorithm could provide 69% of throughput. (c) 2006 Elsevier B.V. All rights reserved.
Performance evaluation of a multi-echelon production, transportation and distribution system: A matrix analytical approach
(2007-01-16)
Wang, Fong-Fan
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Su, Chao-Ton
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工業工程與管理學系
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Department of Industrial Engineering and Management
This study proposes an originative method to evaluate complex supply chains. A tentative multi-echelon production, transportation and distribution system with stochastic factors built-in is employed as a test bed for the proposed method. The supply subsystem formulated in this study is a two-stage production facility with constant probability of feedback and stochastic breakdowns. The transportation subsystem is a service facility with one server. The distribution subsystem under study is a single central warehouse with M retailers. All the participants of the supply chain use base-stock policies and single-server settings. We investigated both the make-to-order (MTO) and make-to-stock (NITS) policies for different base-stock levels, as adopted at different sites. Applying quasi-birth-and-death (QBD) processes as decomposed building blocks and then using the existing matrix analytical computing approach for the performance evaluation of a tandem queue constitutes the main procedure of this study. We also discuss the possibilities of extending the current model to account for other inventory control policies as well as for multi-server case. Numerical study shows our proposed analytical model is robust for practical use. (c) 2005 Elsevier B.V. All rights reserved.
以匯流排同步傳輸的去方塊濾波器架構及其傳輸方法
(2007-01-16)
張世騫
;
彭文孝
;
王士豪
;
蔣迪豪
本發明係揭露一種以匯流排同步傳輸的去方塊濾波器架構及其傳輸方法,其係建構在ARM平台式的H.264去方塊濾波器。本發明係利用匯排流同步傳輸之架構去減少巨方塊濾波處理時間;另外,本發明亦利用適應性傳輸方法去減少匯排流(Bus)的工作量。相較於先前技術而言,本發明可提升去方塊濾波器之效能,適合需要低成本同時又要達到即時的應用,並可整合到單晶片系統應用上。
利用NMOS來保護混合電壓輸入輸出介面之電路
(2007-01-16)
柯明道
;
蔡佳昇
本發明係一種利用NMOS來保護混合電壓輸入輸出介面之電路,用以使不同電壓間的積體電路介面能順利溝通,由於習知技術的混合電壓輸入輸出介面電路複雜,為了使不同電壓間的積體電路介面能順利溝通而設計出十分複雜的保護混合電壓輸入輸出介面的電路,由於繁雜的設計,要組成保護混合電壓輸入輸出介面的電路所需使用的材料與種類與本發明相較之下的相對的較多,出於節省成本與提高混合電壓更大範圍(兩電壓間的差距更大)的考量,本發明係設計將NMOS和閘極追蹤電路加在傳統的輸入輸出介面上,這樣的輸入輸出介面可以容忍高於內部電壓源2-3倍値得訊號。
Microscopic evidence for field-induced magnetism in CeCoIn5
(2007-01-19)
Young, B. -L.
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Urbano, R. R.
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Curro, N. J.
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Thompson, J. D.
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Sarrao, J. L.
We present NMR data in the normal and superconducting states of CeCoIn5 for fields close to H-c2(0)=11.8 T in the ab plane. Recent experiments identified a first-order transition from the normal to superconducting state for H > 10.5 T, and a new thermodynamic phase below 290 mK within the superconducting state. We find that the Knight shifts of the In(1), In(2), and the Co are discontinuous across the first-order transition and the magnetic linewidths increase dramatically. The broadening differs for the three sites, unlike the expectation for an Abrikosov vortex lattice, and suggests the presence of static spin moments in the vortex cores. In the low-temperature and high-field phase, the broad NMR lineshapes suggest ordered local moments, rather than a long-wavelength quasiparticle spin density modulation expected for an FFLO phase.
照度均勻的直下式背光模組裝置及其製法
(2007-01-21)
馮致華
;
陸懋宏
本發明提供一種直下式背光模組裝置，包括各式光源，如各型燈管、LED等，在光源上方之擴散板；其中，擴散板為鏤空之楔型構造，或引入多段式傾斜角，光經由光源發射後進入擴散板之鏤空區內，可將板內全反射的光及由鏤空構造導往兩旁的光，該區域光照度下降，但整個模組裝置之光均勻度上升。
雙抗諧振反射光波導馬赫任德干涉式感測器
(2007-01-21)
許世欣
;
黃遠東
本發明之雙抗諧振反射光波導(ARROW)馬赫任德干涉式感測器的用途在偵測外在環境的折射率變化，以供化學和生化感測之用。此一感測元件係由分光區域、感測區域及合光區域等三個區域構成，其中分光與合光區域的結構為具高耦合效率的雙抗諧振反射光波導，而感測區域則是不耦合之雙抗諧振反射光波導。藉由調整結構之對稱性以控制其耦合行為，可達成小巧且不使用彎折結構之積體化馬赫任德干涉式感測器。
助銲劑
(2007-01-21)
徐享文
;
黃和悅
;
曾光宏
;
林仁治
;
張肇芳
一種助銲劑，包含有一基質以及一活化添加物：基質係為氧化鉬，而活化添加物係選自氧化鐵、氧化矽，以及碳酸鎂所組成之群組；藉此，本發明可應用於碳鋼材料之銲接加工，提高銲接過程的銲道熔接深度，達到節省加工時間，減少整體製造成本之目的。
High power passively Q-switched ytterbium fiber laser with Cr4+: YAG as a saturable absorber
(2007-01-22)
Huang, J. Y.
;
Liang, H. C.
;
Su, K. W.
;
Chen, Y. F.
;
電子物理學系
We report an efficient high-peak-power and high-average-power passively Q-switched ytterbium fiber laser with a Cr4+: YAG crystal as a saturable absorber in an external-resonator configuration. At an incident pump power of 17.5 W, the passively Q-switched fiber laser produces an average power greater than 6.2 W with a pulse repetition rate of 48 kHz. The output pulses noticeably display a mode-locking phenomenon that leads to the maximum peak power to be higher than 20 kW. (c) 2007 Optical Society of America.