Browsing by Issue Date, starting with "2005-04-22"

Now showing 1 - 20 of 66837

Anti-HCV activities of selective polyunsaturated fatty acids (vol 318, pg 275, 2004)
(2005-04-22)
Leu, GZ
;
Lin, TY
;
Hsu, JTA
;
生物科技學系
;
Department of Biological Science and Technology
New soluble poly(2,3-diphenylphenylene vinylene) derivatives for light-emitting diodes
(2005-04-22)
Yang, SH
;
Chen, JT
;
Li, AK
;
Huang, CH
;
Chen, KB
Soluble poly(2,3-diphenylphenylene vinylene) (DP-PPV) derivatives, poly(2,3-diphenyl-5-(4-heptyloxy-4'-oxytrimethylenediphenyl)phenylene vinylene) (P1), poly(2,3-diphenyl-5-[4-(4-pentylcyclohexyl)phenoxyl-propyl-p-phenylene vinylene) (P2) and poly(2,3-diphenyl-5-(2-(1, 4, 5-triphenyl-1H-2-imidazoloyl)-1-oxytrimethylene phenyl) phenylene vinylene) (P3), were synthesized. P1 and P2 contain liquid crystal side groups; while P3 contains a charge transport group. The polymers showed solid state UV-Visible absorption and photoluminescence in the range of 370-380 and 480-510 nm, corresponding to blue green emission. Similar to many other reported systems, the solution fluorescence spectra of P1 and P2 showed slight solvent dependency and blue-shifted with respect to those of the films. These were not the case for P3 which showed little solvent dependency and little blue shift in solution. Two-layer light-emitting devices with a simple ITO/PEDOT/polymer/Ca (Al) configuration were fabricated and characterized. (c) 2004 Elsevier B.V. All rights reserved.
Anticontrol and synchronization of chaos for an autonomous rotational machine system with a hexagonal centrifugal governor
(2005-04-22)
Ge, ZM
;
Lee, CI
;
機械工程學系
;
Department of Mechanical Engineering
Anticontrol and synchronization of chaos for an autonomous rotational machine system with a hexagonal centrifugal governor are studied in the paper. Two different procedures for the design of the controller are proposed to anticontrol the governor system effectively. Finally, five methods are studied for chaos synchronization. (c) 2004 Elsevier Ltd. All rights reserved.
Polypeptide-shelled poly(propylene imine) dendrimers and their complexing properties towards copper(II) ions
(2005-04-22)
Appelhans, D
;
Komber, H
;
Kirchner, R
;
Seidel, J
;
Huang, CF
Polypeptide-shelled poly(propylene imine) dendrimers were realized by ring-opening polymerization of alpha-amino acid N-carboxyanhydrides, initiated by dendrimers as core molecules. Polypeptides with 2nd generation core were used as model compounds to investigate interior complexes between metal ion and surface-modified dendrimers. Microcalorimetric measurements outlined the formation of approximate 1:1 complexes between Cu-II and polypeptide-shelled dendrimers and the influence of polypeptide chain compositions on differential molar heats of complexation.
Dry sliding wear behaviors of Al-25Si-2.5Cu-1Mg alloys prepared by powder thixocasting
(2005-04-25)
Chen, CM
;
Yang, CC
;
Chao, CG
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The wear performance of an Al-25Si-2.5Cu-1Mg alloy prepared by powder thixocasting was studied using a pin-on-disc machine. LM13 and an Al-25Si-2.5Cu-lMg alloy prepared by conventional ingot metallurgy were also investigated for comparison. The sliding tests were performed under ambient conditions and without lubricant. During the tests, the applied load was increased stepwise until wear seizure occurred. Experimental data reveal that the powder thixocast alloys exhibit better wear performance than that of conventional alloys, especially under heavy load conditions and following T6 treatment. This work demonstrates the potential of the new method, powder thixocasting, for fabricating hypereutectic Al-Si-X alloys with a high wear resistance. Moreover, the variation in the wear rate with the applied load for the alloy can be divided into three regions. The mechanisms associated with these wear regions were discussed based on the investigations of the worn subsurface and the wear debris. (c) 2005 Elsevier B.V. All rights reserved.
Transient analysis of reactant gas transport and performance of PEM fuel cells
(2005-04-27)
Yan, WM
;
Soong, CY
;
Chen, FL
;
Chu, HS
;
機械工程學系
The dynamic performance of PEM fuel cells is one of the most important criteria in the design of fuel cells with application to mobile systems. To study this issue, we extend our previous steady model of gas reactant transport to an unsteady one and employ it to examine the transient transport characteristics and the system performance of the PEM fuel cells. With the assumption of the two-dimensional mass transport in the cathode side of PEMFC, the effects of the channel width fraction, lambda = l(c)/l(b), the porosity of the gas diffuser layer, epsilon(1), and the surface overpotential of the catalyst layer, eta, on the transient characteristics of the resultant current density and mass transport are focused in this work. It is disclosed that an increase in lambda, or eta may lead to a faster dynamic response for the fuel cell when the PEM fuel cell system is started up. Results of a typical case demonstrate that, although the dynamic response time may be as long as 10 s due to the mass transport lag, the fuel cell system needs only less than 0.4 s to reach the 90% response. (c) 2005 Elsevier B.V. All rights reserved.
Burglarproof security system
(2005-04-28)
Wu, Bing-Fei
;
Chen, Chao-Jung
;
Peng, Hsin-Yuan
A burglarproof security system is disclosed, wherein a video for a target object is recorded and transmitted to a mobile device at the far end at the first time via a wireless communication. The mobile device has a display device for displaying the video, so that a user can monitor and assure the safety of the target object.
二次元アレイ導波管構造
(2005-04-28)
荘晴光
;
陳志強
【課題】マイクロ波集積回路の小型化を達成できる二次元アレイ導波管構造を提供する。【解決手段】本発明の二次元アレイ導波管構造は、第一金属層、第二金属層と誘電体層（dielectric layer）を有する。誘電体層は、第一金属層と前記第二金属層の間に位置し、第一金属層と前記第二金属層を隔てる。第一金属層及び第二金属層は、それぞれ複数の第一ユニットセル及び複数の第二ユニットセルによって、ローとコラム方向に沿って二次元アレイ導波管構造を形成する。各第一ユニットセルは、主体と複数の接続アームによって構成され、各第二ユニットセルは、金属線ループによって構成される。第二金属層は第一金属層の下方に位置し、且つ、各第二ユニットセルはそれぞれ一対一の方式で各第一ユニットセルに対応し、完全なユニットセルを形成する。【選択図】図１ａ
Characterization and conductive coating of phosphors for improved brightness
(2005-04-30)
Chang, CH
;
Chiou, BS
;
Chen, KS
;
Ho, JC
;
電子工程學系及電子研究所
In this study, the phosphors used in CRTs are coated with In2O3 conductive layer derived from the hydrolysis of indium chloride. The conductive coating retards/eliminates charging-up on the phosphor surface during the bombardment of the electrons and improves the cathodoluminescent brightness of the phosphor. However, the non-emissive conductive coating also degrades the cathodoluminescent brightness when it is too thick. The cathodoluminescent brightness increases initially with the amount of coating, reaches a maximum at 10 wt.% InCl3, and decreases with further increase of coating. It is found that with a 10 wt.% InCl3 coating, the brightness of phosphor increases by 20% at 500 V and 1 mu A. (c) 2004 Published by Elsevier B.V.
Hybrid S- to L-band fiber amplifier module with coupled structure
(2005-05-01)
Yeh, CH
;
Chi, S
;
光電工程學系
;
Department of Photonics
Reoxidation behavior of high-nitrogen oxynitride films after O-2 and N2O treatment
(2005-05-01)
Lin, BC
;
Chang, KM
;
Lai, CH
;
Hsieh, KY
;
Yao, JM
Reoxidation of a high-nitrogen ultrathin oxynitride (similar to 1.3nm) has been studied. The reoxidation is conducted using an alternation of nitrous oxide and oxygen gas in rapid thermal oxidation (RTO). The new finding in this study is the zig-zag characteristic of the oxidation rate by O-2 and N2O. It is clear that the N2O oxidation rate is almost independent of the concentration of nitrogen in oxynitride through out the rapid thermal oxidation process, but the O2 oxidation rate is not.
Influence of dislocation density on photoluminescence intensity of GaN
(2005-05-01)
Falth, JF
;
Gurusinghe, MN
;
Liu, XY
;
Andersson, TG
;
Ivanov, IG
The influence of dislocation density on photoluminescence intensity is investigated experimentally and compared to a model. GaN samples were grown by molecular beam epitaxy and metal-organic chemical vapour deposition. Different growth parameters and thicknesses of the layers resulted in different dislocation densities. The threading dislocation density, measured by atomic force microscopy, scanning electron microscopy and X-ray diffraction, covered a range from 5 x 10(8) to 3 x 10(10) cm(-2). Carrier concentration was measured by capacitance-voltage-, and Hall effect measurements and photoluminescence at 2 K was recorded. A model which accounts for the photoluminescence intensity as a function of dislocation density and carrier concentration in GaN is developed. The model shows good agreement with experimental results for typical GaN dislocation densities, 5 x 10(8)-1 x 10(10) cm(-2), and carrier concentrations 4 x 10(16)-1 x 10(18) cm(-3). © 2005 Elsevier B.V. All rights reserved.
Switchable dual-wavelength NRZ-to-RZ data-format transformer using non-DC-biased and synchronously modulated laser diode
(2005-05-01)
Chang, YC
;
Lin, YH
;
Liao, YS
;
Lin, GR
;
光電工程學系
The switchable dual-wavelength and wavelength-converted nonretum-to-zero-to-return-to-zero (NRZ-to-RZ) data transformation is demonstrated by externally seeding a synchronously sinusoidal-modulated laser diode with an optical pseudorandom bit sequence data at 1 Gbps. A maximum wavelength tuning range of 30 nm with an SMSR of greater than 36 dB is obtained. 1 Gbps on/off keying of single-mode RZ data pulse-train generated by externally seeding synchronously sinusoidal-modulated laser diode is demonstrated.
The molecular mechanism of actinomycin D in preventing neointimal formation in rat carotid arteries after balloon injury
(2005-05-01)
Wu, CH
;
Pan, JS
;
Chang, WC
;
Hung, JS
;
Mao, SJT
The pathological mechanism of restenosis is primarily attributed to excessive proliferation of vascular smooth muscle cells (SMC). Actinomycin D has been regarded as a potential candidate to prevent balloon injury-induced neointimal formation. To explore its molecular mechanism in regulating cell proliferation, we first showed that actinomycin D markedly reduced the SMC proliferation via the inhibition of BrdU incorporation at 80 nM. This was further supported by the G1-phase arrest using a flowcytometric analysis. Actinomycin D was extremely potent with an inhibitory concentration IC50 at 0.4 nM, whereas the lethal dose LD50 was at 260 mu M. In an in vivo study, the pluronic gel containing 80 nM and 80 lMactinomycin D was applied topically to surround the rat carotid adventitia; the thickness of neointima was substantially reduced (45 and 55%, respectively). The protein expression levels of proliferating cell nuclear antigen ( PCNA), focal adhesion kinase (FAK), and Raf were all suppressed by actinomycin D. Extracellular signal-regulated kinases (Erk) involved in cell-cycle arrest were found to increase by actinomycin D. These observations provide a detailed mechanism of actinomycin D in preventing cell proliferation thus as a potential intervention for restenosis.
A novel algal toxicity testing technique for assessing the toxicity of both metallic and organic toxicants
(2005-05-01)
Lin, JH
;
Kao, WC
;
Tsai, KP
;
Chen, CY
;
環境工程研究所
This study presents a closed-system algal toxicity test technique that is capable of detecting the effects of both organic and metallic toxicants. Toxicity testing was conducted by transferring adequate amounts of algal suspension, dilution water (with culture growth medium), and toxicants into 300-mL BOD bottles. The BOD bottles were completely filled up with no head-space left. The initial cell density and the exposure time were 15,000 cells/mL and 48 h, respectively. The performance of the above test method was evaluated using three heavy metals and six organic toxicants based on three different test endpoints, i.e., dissolved oxygen production, algal growth rate, and cell density. The proposed test revealed excellent test sensitivity and reproducibility. Currently, none of the existing algal toxicity test protocols is adequate for assessing the toxicity of organic chemicals. The closed-system algal toxicity tests developed by previous researchers also may not be ideal because the enlarged headspace and/or enriched bicarbonate buffer may result in either underestimations of the exposure concentrations or insensitive responses to both heavy metals and organic toxicants. Compared to the aforementioned algal toxicity test methods, the proposed technique in the present study has a more general applicability under conditions such as effluent samples containing both metals and organic toxicants or samples with unknown compositions. (c) 2005 Elsevier Ltd. All rights reserved.
Aplication of plasma immersion ion implantation on seeding copper electroplating for multilevel interconnection
(2005-05-01)
Chiu, SY
;
Wang, YL
;
Chang, SC
;
Feng, MS
;
材料科學與工程學系
In this study, an effective seeding technology, plasma immersion ion implantation of palladium (PIII Pd), was proposed to achieve defect-free gap filling for copper electroplating (Cu-ECP). It was found that a threshold dosage (similar to 5.2 x 10(18) m(-2)) of PIII I'd was required to drive Cu-ECP and the dependence of Pd dosage on the implantation time was quasi-linear. The thickness of electroplated copper films increased as the Pd dosage increased. Too high a Pd dosage caused a rough copper film with high resistivity (> 10 mu Omega cm) while too low a I'd dosage resulted in an insufficient nucleation site for Cu-ECP, leading to poor film adhesion. In addition, a higher substrate bias of PIII was suggested to enhance the gap-filling capability of Cu-ECP and the Cu(111) formation of electroplated copper films. (c) 2004 Elsevier B.V. All rights reserved.
Ti2ZrO phases formed in the titanium and zirconia interface after reaction at 1550 degrees C
(2005-05-01)
Lin, KL
;
Lin, CC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Hot-pressed 3 mol% Y2O3 partially stabilized ZrO2 was reacted with titanium at 1550&DEG; C/30 min. The interface was characterized by analytical transmission microscopy (transmission electron microscopy/energy-dispersive spectroscopy). The lamellar and the spherical Ti2ZrO as well as the orthorhombic β'-Ti were found to exist in the titanium side after cooling down to room temperature. The crystal structures of the lamellar and the spherical Ti2ZrO were orthorhombic and hexagonal, respectively. On heating, the dissolution of a large amount of zirconium and oxygen into titanium gave rise to the metastably supersaturated disordered α-Ti(Zr, O) solid solution where two different Ti2ZrO phases subsequently precipitated, while the β-Ti coexisting with α-Ti at high temperatures was transformed to the orthorhombic β'-Ti during cooling. The spherical hexagonal Ti2ZrO was an ordered structure, with Zr and O occupying substitutional and interstitial sites, respectively. The orientation relations between oc-Ti and the lamellae orthorhombic Ti2ZrO were determined to be [0001](α-Ti)//[110](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(1 (1) over bar0)Ti2ZrO; meanwhile, those between the α-Ti and the spherical hexagonal Ti2ZrO were [0001](α-Ti)//[0001](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(10 (1) over bar0)(Ti2ZrO).
Individual and combined toxicity of nitriles and aldehydes to Raphidocelis subcapitata
(2005-05-01)
Chen, CY
;
Chen, SL
;
Christensen, ER
;
環境工程研究所
;
Institute of Environmental Engineering
A closed- system algal toxicity test with no headspace was applied to evaluate the toxicity of I I aldehydes and two nitrites to Raphidocelis subcapitata. Algal growth rate and dissolved oxygen (DO) production were used as the test endpoints. Compared to literature data, our test results based on the endpoint of DO production is 2.5 to 257 times more sensitive than the conventional algal batch tests. In addition, our analyses show that different relative toxicity relationships may be observed when different test methods or different endpoints are applied. The test alga was found to be quite sensitive to aldehydes, and a quantitative structure- activity relationship (QSAR) relationship was established based on the n-octanol/water partition coefficient (log K,,.). This study also evaluated the combined effects of aldehydes and nitriles. Four synergistic joint actions related to majononitrile were identified. On the other hand, most of the combined effects between aldehydes and acetonitrile were antagonistic. In general, we find that greater-than-additive effects mainly are associated with toxicants displaying flat dose-response curves, and less-than-additive effects may be related to certain steep-slope chemicals. Model analyses show that the above mixture toxicity behavior may be due to response addition or response multiplication joint action modes.
Freezing phase scheme for fast adaptive control and its application to characterization of femtosecond coherent optical pulses reflected from semiconductor saturable absorber mirrors
(2005-05-01)
Chen, MC
;
Huang, LY
;
Yang, QT
;
Pan, CL
;
光電工程學系
herent control with a femtosecond pulse shaper. The operational principle is based on a concept that the highest peak intensity will correspond to a frozen phase state of all spectral components involved in a coherent optical pulse. Our experimental and theoretical results reveal this new scheme to be fast and immune to the noise and laser power fluctuation. The freezing phase method has been used to investigate three types of semiconductor saturable absorber Bragg reflector (SBR). The optical pulses reflected from the SBR can be distorted in the spectral phase by a minor structural change of the SBR devices and can be clearly resolved with our method. The technique is useful for a variety of applications that require complete-field characterization and adaptive coherent control on the same setup. © 2005 Optical Society of America.
Wafer bonding for high-brightness light-emitting diodes via indium tin oxide intermediate layers
(2005-05-01)
Liu, PC
;
Hou, CY
;
Wu, YCS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A direct wafer-bonding technique has been used to fabricate high-brightness light emitting diodes (LEDs). However, bonding processes were usually performed at elevated temperatures, possibly causing degradation in the quality of the LED structure. In addition to this, misorientation between the two bonded wafers may have caused defects between the wafers. In this study, these two problems were solved by bonding the InGaP/GaAs and GaAs wafers with an indium tin oxide (ITO) polycrystalline film at temperatures below 650 degrees C. It was found that the bonding occurred mainly through the In transport from the InGaP to ITO, and that the electrical resistance decreased with the bonding temperature. (c) 2004 Elsevier B.V. All rights reserved.