Browsing by Issue Date, starting with "2005-03-05"

Now showing 1 - 20 of 67053

An improved approach for small-signal equivalent-circuit parameter determination of InGaP/GaAs HBT
(2005-03-05)
Chen, HY
;
Chen, KM
;
Huang, GW
;
Chang, CY
;
Huang, TY
In this paper, an improved method for extracting the small-signal equivalent-circuit elements of an HBT is proposed. A more general HBT equivalent circuit and a more general explicit equation on the total extrinsic elements are introduced. Linear least-square algorithms are cleverly adopted to reduce the number of error function. As a result, the modified approach can yield a better fit between the measured and simulated S-parameters over the conventional method. (C) 2005 Wiley Periodicals, Inc.
Iridium(III) complexes with orthometalated quinoxaline ligands: Subtle tuning of emission to the saturated red color
(2005-03-07)
Hwang, FM
;
Chen, HY
;
Chen, PS
;
Liu, CS
;
Chi, Y
Rational design and syntheses of four iridium complexes (1-4) bearing two substituted quinoxalines and an additional 5-(2-pyridyl) pyrazolate or triazolate as the third coordinating ligand are reported. Single-crystal X-ray diffraction studies of 1 reveal a distorted octahedral geometry, in which two dpqx ligands adopt an eclipse configuration, for which the quinoxaline N atoms and the C atoms of orthometalated phenyl groups are located at the mutual trans-and cis-positions, respectively. The lowest absorption band for all complexes consists of a mixture of heavy-atom Ir(III)-enhanced (MLCT)-M-3 and (3)pipi(*) transitions, and the phosphorescent peak wavelength can be fine-tuned to cover the spectral range of 622-649 nm with high quantum efficiencies. The cyclic voltarnmetry was measured, showing a reversible, metal-centered oxidation with potentials at 0.76-1.03 V, as well as two reversible reduction waves with potentials ranging from -1.61 to -2.06 V, attributed to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated CAN ligands. Complex 1 was used as the representative example to fabricate the red-emitting PLEDs by blending it into a PVK-PBD polymer mixture. The devices exhibited the characteristic emission profile of 1 with peak maxima located at 640 nm. The maximum external quantum efficiency was 3.15% ph/el with a brightness of 1751 cd/M-2 at a current density of 67.4 mA/cm(2) and the maximum brightness of 7750 cd/m(2) was achieved at the applied voltage of 21 V and with CIE coordinates of (0.64, 0.31).
Improved stability of organic electroluminescent devices by doping styrylamines in hole or electron transporting layer
(2005-03-07)
Lee, MT
;
Liao, CH
;
Tsai, CH
;
Chen, CH
;
應用化學系
The stability of green organic electroluminescent devices has been improved by doping styrylamine derivate, p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph) in hole or electron transporting layer. Compared with the undoped device, the stability of the electron transporting layer has increased by a factor of 1.8 without affecting the electroluminescence efficiency of 11 cd/A and color (CIEx,y=0.34, 0.62). The enhanced stability is believed to derive from the hole trapping nature of DSA-Ph which can reduce the residual hole carriers in tris(8-hydroquinolinato)aluminum (Alq(3)) and suppress the formation of fluorescent quencher of Alq(3) cationic species. (c) 2005 American Institute of Physics.
Synthesis and optoelectronic properties of arrayed p-type ZnO nanorods grown on ZnO film/Si wafer in aqueous solutions
(2005-03-07)
Lin, CC
;
Chen, HP
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Highly arrayed nitrogen-doped ZnO nanorods were fabricated on Si buffered with ZnO film by combining wet-chemical process with post-treated by NH3 plasma. The X-ray photoelectron spectroscopy measurement demonstrates that the nitrogen-doped ZnO nanorods have been formed due to nitrogen diffusion through surface adsorption or defect routes. The photoluminescence spectra indicate that a strong UV emission peak around 3.31 eV with negligible deep level emission can be obtained for the nitrogen-doped ZnO nanorods compared to that of the untreated sample. The I-V measurements indicate that the p-type ZnO nanorods with a smaller threshold voltage of 1.5 V can be obtained. (C) 2005 Elsevier B.V. All rights reserved.
Characterization of electronic structure of aluminum (III) bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq) for phosphorescent organic light emitting devices
(2005-03-07)
Chu, TY
;
Wu, YS
;
Chen, JF
;
Chen, CH
;
電子物理學系
The structure of the triplet host material, aluminum (111) bis(2-metliyl-8-quninotinato)-4-phenylphenolate (BAlq), has been optimized by density functional theory (DFT) with B3LYP methods to study the electronic distribution of its HOMO and LUMO energy states. Calculated triplet bandgap energy of BAlq is shown to be consistent with the experimental data. By analyzing the partial density states (PDOS) of these ligands contributing to the total density of states (TDOS), it is concluded that the HOMO and LUMO orbitals of BAlq are mainly localized on the 4-phenylphenol and 2-methyl-8-hydroxyquin oline ligands, respectively. (C) 2005 Elsevier B.V. All rights reserved.
Suppression of spatial hole burning in a solid-state laser with the degenerate resonator configuration
(2005-03-07)
Tai, PT
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
Under degenerate resonator configuration and tightly focused pump beam in a linear-cavity solid-state laser, the spatial hole-burning effect can be suppressed. This laser can attain very high intensity in the gain medium due to shrinkage of its beam waist to match the pump beam and therefore most of its gain is depleted even by a standing wave. This was demonstrated by a simulation with spatial dependent rate equations and experiment results of a plano-concave Nd: YVO4 laser. The suppression effect was observed up to 20 times the pump threshold. (C) 2005 Optical Society of America.
Molecular sensing with ultrafine silver crystals on hexagonal aluminum nitride nanorod templates
(2005-03-09)
Chattopadhyay, S
;
Shi, SC
;
Lan, ZH
;
Chen, CF
;
Chen, KH
マルチレベルメモリセルを組み合わせ、且つこれにエラー訂正メカニズムを具えさせる方法
(2005-03-10)
呉介▲そう▼
;
汪大暉
;
張錫嘉
【課題】記憶媒体のデータを保存する容量を増加し、アクセスするデータの正確性を確保し、記憶媒体の保存空間を十分に利用できる、マルチレベルメモリセルを組み合わせ、且つこれにエラー訂正メカニズムを具えさせる方法を提供する。【解決手段】ｎ段階の電圧レベルを具え、且つ該ｎが２の２乗値でなく、保存ビットを、数式１で表すことのできる少なくとも一以上のメモリセルを提供し、１よりも大きいｋ個のメモリセルを組み合わせて記憶媒体を形成し、データを該記憶媒体に保存する。該記憶媒体の保存ビットは、数式２で表示され、且つ該記憶媒体は更に余剰電圧レベル階数を具え、該余剰電圧レベル階数は保存ビットの電圧レベル階数の数値に含まれることなく、数式３で表示され、該データは該記憶媒体の保存ビットである該数式２に保存され、且つ該記憶媒体の有する該余剰電圧レベル階数に該データをチェックするエラー消去情報を表示する。【数１】【数２】【数３】【選択図】図３
Synthesis and characterizations of a vinyl-terminated benzoxazine monomer and its blending with polyhedral oligomeric silsesquioxane (POSS)
(2005-03-10)
Lee, YJ
;
Huang, JM
;
Kuo, SW
;
Chen, JK
;
Chang, FC
Benzoxazine was synthesized through the Mannich condensation of phenol, formaldehyde, and primary amines through ring-opening polymerization. Polybenzoxazines are phenolic-like materials that possess dimensional and thermal stability, and they release no toxic byproducts during their polymerization. To further improve the thermal stability of polybenzoxazines, a hydrosilane-functionalized polyhedral oligomeric silsesquioxane (H-POSS) was incorporated into the vinyl-terminated benzoxazine monomer (VB-a) which we then subjected to ring-opening polymerization. In addition, we also prepared hybrids from a non-reactive POSS (IB-POSS) and VB-a. The glass transition temperature (T-g) of a regular polymerized VB-a (i.e. PVB-a) is 307 degrees C, while the hybrid containing 5 wt% of H-POSS is 333 degrees C. The IB-POSS modified PVB-a hybrids, in general, results in lower T-g than the pure PVB-a due to poor missibility. (c) 2005 Elsevier Ltd. All rights reserved.
Electrocoagulation for removal of silica nano-particles from chemical-mechanical-planarization wastewater
(2005-03-10)
Den, W
;
Huang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
Continuous-flow electrocoagulation process with vertical flow-channels was investigated as a method to treat synthetic chemical-mechanical-planarization (CMP) wastewater containing highly charged ultrafine silica particles (zeta = -55 mV, mean R-p = 45 nm at pH 9.5). The parallel-plate, monopolar electrochemical cells resembled a series of closed electrical circuits such that the electrical field strength was highly dependent of the current density and aqueous conductivity, but independent of the inter-electrode gap. The residual turbidity of the CMP wastewater decreased with the increases in either hydraulic retention time or applied current density, and removal efficiency as high as 95% was achieved for wastewater with both low (70NTU) and high (400 NTU) initial turbidities. The charge loading linearly correlated with turbidity removal efficiency up to a level of 8 F m(-3), presenting an appropriate design parameter. Further analysis indicated that turbidity removal was limited by the quantity of liberated ferrous ions at lower range of current density, but seemingly reached a critical level of current density beyond which the process performance gradually deteriorated. Comparisons between the effective particle retention time and the estimated electrophoretic migration time revealed that the electrocoagulation process was predominantly controlled by the rate of particle aggregation occurring near the anodic surfaces. Furthermore, this process generates lesser amount of dry sludge as compared to chemical coagulation with polyaluminum chloride, and does not require pH adjustment prior to treatment. (C) 2004 Elsevier B.V.. All rights reserved.
Multi-wavelength external-cavity laser with digital and mode-hope-free fine tuning mechanisms
(2005-03-10)
Pan, Ci-Ling
;
Chao, Ru-Pin
;
Lan, Yu-Ping
An apparatus for electronically tuning of a single or multi-wavelength external-cavity laser, comprising: an AR-coated diode laser, a collimator, a liquid crystal cell, a dispersion grating, a focusing lens and a liquid crystal pixel mirror. Wavelength channels can be selected by opening the appropriate pixels of the liquid crystal pixel mirror. By turning on several pixels at the same time, the laser can generate output at several wavelengths. Wavelength switching between channels is also possible. Laser wavelength can further be tuned by varying the driving voltages of the liquid crystal cell or the appropriate pixel mirror. The liquid crystal cell and the liquid crystal pixel mirror in the laser cavity can be combined to form a sandwich-type liquid crystal pixel mirror that allows both step (digital) or fine tuning of the laser wavelength.
Thermal properties, specific interactions, and surface energies of PMMA terpolymers having high glass transition temperatures and low moisture absorptions
(2005-03-10)
Chen, JK
;
Kuo, SW
;
Kao, HC
;
Chang, FC
;
應用化學系
We have prepared a series of poly(methyl methacrylate) (PMMA)-based terpolymers that have high glass transition temperatures and low moisture absorptions by the free radical copolymerization of methyl methacrylate, methacrylamide, and styrene in dioxane. We have investigated the effects of the styrene content on the glass transition temperatures, hydrogen bonding interactions, surface energies, moisture absorption, and molecular weights of these poly(methyl methacrylate-co-methacryl ami de-co-styrene) (Poly(MMA-co-MAAM-co-S)) terpolymers by differential scanning calorimetry, Fourier transform infrared and X-ray photoelectron spectroscopies, contact angle measurements, and gel permeation chromatography. The results indicate that the glass transition temperatures, hydrogen bonding strengths, surface energies, molecular weights, and the moisture absorption decreased upon increasing the PS content in most of the terpolymer systems. In addition, the moisture absorptions of some selected terpolymers decreased even through they possess higher values of T, than pure PMMA. These selected terpolymers have the potential to replace pure PMMA in optical device applications. (c) 2005 Elsevier Ltd. All rights reserved.
Identification of V23RalA-Ser(194) as a critical mediator for aurora-A-induced cellular motility and transformation by small pool expression screening
(2005-03-11)
Wu, JC
;
Chen, TY
;
Yu, CTR
;
Tsai, SJ
;
Hsu, JM
Human Aurora kinases have three gene family members: Aurora-A, Aurora-B, and Aurora-C. It is not yet established what the specificity of these kinases are and what signals relayed by their reactions. Therefore, we employed small pool expression screening to search for downstream substrates of Aurora-A. Interestingly, all of the identified Aurora-A substrates were resistant to serve as substrates for Aurora-B or Aurora-C, suggesting that these Aurora family members may have distinct substrate specificity for propagation of diverse signaling pathways, even though they share a conserved catalytic kinase domain. Of the candidate substrates, Aurora-A could increase the functional activity of RalA. Mutational analysis revealed that RalA-Ser(194) was the phosphorylation site for Aurora-A. Ectopic expression of V23RalA-WT could enhance collagen I-induced cell migration and anchorage-independent growth in Madin-Darby canine kidney (MDCK) Aurora-A stable cell lines. In contrast, overexpression of V23RalA-S194A in MDCK Aurora-Astable cell lines abolished the intrinsic migration and transformation abilities of Aurora-A. To our knowledge, this is the first systematic search for the downstream substrates of Aurora-A kinase. Moreover, these results support the notion that Aurora-A may act in concert with V23RalA through protein phosphorylation on Ser(194) to promote collagen I-induced cell motility and anchorage-independent growth in MDCK epithelial cells.
利用控制偏振逐段曝照方法製作複雜的光纖光柵結構
(2005-03-11)
莊凱評
;
許立根
;
蔡孟璋
;
賴杰
本發明係提出一製造複雜光纖光柵曝照系統及方法，係於相位光罩製程或雙光束干涉製程中，加入一可旋轉之1/2波片以及一偏振分光稜鏡來完成，並將感光性光纖放置於相對位移可以準確控制至奈米等級之位移平台上，藉此組合可以達到任意相位和折射率變化之複雜光纖光柵結構之製作。本發明之特點在於整個曝照過程只需一次連續移動即可完成，並且在完成複雜折射率變化之控制上更為準確及穩定。
一種感光性光纖之曝照系統及方法
(2005-03-11)
莊凱評
;
許立根
;
蔡孟璋
;
賴杰
本發明係提出一種僅需旋轉一旋轉反射鏡即可達微調干涉角度目的之雙光束干涉曝照系統。本發明之曝照系統將經旋轉反射鏡反射並經分光後之兩分光束中之任一組分光束之光程中置入一可旋轉之1/2波長偏振片，再將感光性光纖置放於一相對位移可準確控制至奈米等級的移動平台上，之後僅需在逐段曝照的過程中，將不同的相對位置配合旋轉偏振片於不同角度，即可達到一次連續曝照可至做出平均折射率平坦化的光纖光柵，此外，更可藉由旋轉對換1/2波長偏振片快慢軸的方式，來製作具180°相位改變之相位移光纖光柵。
Growth of CaF2/a-C core/shell nanowires.
(2005-03-13)
Huang, CH
;
Chang, YH
;
Lee, CY
;
Chiu, HT
;
應用化學系
Enzymatic formation of multiple triterpenes by mutation of tyrosine 510 of the oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae.
(2005-03-13)
Chang, CH
;
Wu, TK
;
生物科技學系
;
Department of Biological Science and Technology
Synthetic approach to ellipticine.
(2005-03-13)
Ho, TL
;
Hsieh, SY
;
應用化學系
;
Department of Applied Chemistry
Material and interface engineering for high-performance light-emitting diodes.
(2005-03-13)
Jen, AKY
;
Niu, YH
;
Liu, MS
;
Yip, H
;
Kang, MS
書藝結緣．伊玉桂教官以筆會友
(國立陽明大學, 2005-03-15)
錢玨琄
去年十月間，校園內悄悄地開設了一個極小規模的書法練習班，由甫退休的伊玉桂教官帶領十餘位學員們共同切磋書法技藝。幾個月下來，參加的學員們都覺得受益匪淺.....