Browsing by Issue Date, starting with "2008-03-10"

Now showing 1 - 20 of 56039

Intense terahertz emission from a-plane InN surface
(2008-03-10)
Ahn, H.
;
Ku, Y. -P.
;
Chuang, C. -H.
;
Pan, C. -L.
;
Lin, H. -W.
We report a significant enhancement in terahertz emission from the indium nitride (InN) films grown along the a axis (a-plane InN), relative to the InN films grown along the c axis. The primary radiation mechanism of the a-plane InN film is found to be due to the acceleration of photoexcited carriers under the polarization-induced in-plane electric field perpendicular to the a axis, which effectively enhances the geometrical coupling of the radiation out of semiconductor. In addition, azimuthal angle dependence measurement shows that the p-polarized terahertz output consists of a large angularly independent component and a weak component with a distinctive fourfold rotation symmetry. (c) 2008 American Institute of Physics.
Solvent mixtures for improving device efficiency of polymer photovoltaic devices
(2008-03-10)
Chen, Fang-Chung
;
Tseng, Hsin-Chen
;
Ko, Chu-Jung
;
光電工程學系
;
顯示科技研究所
In this work, we used solvent mixtures, consisting of 1-chloronaphthalene (Cl-naph), one solvent with a high boiling point, and o-dichlorobenzene, to prepare the polymer films for polymer photovoltaic devices. Because of the lower vapor pressure of the solvent mixtures, the polymer films dried slower. With higher Cl-naph concentration in the organic solvent, the polymer chains had longer time to self-organize themselves. As a result, the higher degree of crystalline led to lower device series resistance, thereby increasing the performance of the photovoltaic devices. (c) 2008 American Institute of Physics.
車輛動態預測系統與方法
(2008-03-11)
陳宗麟
;
許齡元
一種車輛動態預測系統與方法，係用以預測一車輛之運動行為，此車輛動態預測系統包含一感測部、一估測器與一預測器，其中感測部由三個感測器組成，用以測量質心的縱向速度與側向加速度，以及車輛懸掛彈簧之長度變化，並透過估測器而估算出多個車輛動態之物理量，並將這些物理量傳輸入預測器，進行車輛於未來時間動態之預測，因此，本發明之車輛動態預測系統與方法係量測三個物理量而進行車輛動態預測，更增加低成本與準確性之優勢。
Tumor cell cycle arrest induced by shear stress: Roles of integrins and Smad
(2008-03-11)
Chang, Shun-Fu
;
Chang, Cheng Allen
;
Lee, Ding-Yu
;
Leet, Pei-Ling
;
Yeh, Yu-Ming
interstitial flow in and around tumor tissue affects the mechanical microenvironment to modulate tumor cell growth and metastasis. We investigated the roles of flow-induced shear stress in modulating cell cycle distribution in four tumor cell lines and the underlying mechanisms. In all four cell lines, incubation under static conditions for 24 or 48 h led to G(0)/G(1) arrest; in contrast, shear stress (12 dyneS/cm(2)) induced G(2)/M arrest. The molecular basis of the shear effect was analyzed, and the presentation on molecular mechanism is focused on human MG63 osteosarcoma cells. Shear stress induced increased expressions of cyclin 11311 and p21(CIP1) and decreased expressions of cyclins A, D1, and E, cyclin-dependent protein kinases (Cdk)-1, -2, -4, and -6, and p27(KIP1) as well as a decrease in Cdk1 activity. Using specific antibodies and small interfering RNA, we found that the shear-induced G2/M arrest and corresponding changes in G2/M regulatory protein expression and activity were mediated by alpha(v)beta(3) and beta(1), integrins through bone morphogenetic protein receptor type IA-specific Smad1 and Smad5. Shear stress also down-regulated runt-related transcription factor 2 (Runx2) binding activity and osteocalcin and alkaline phosphatase expressions in MG63 cells; these responses were mediated by alpha(v)beta(3) and beta(1), integrins through Smad5. Our findings provide insights into the mechanism by which shear stress induces G(2)/M arrest in tumor cells and inhibits cell differentiation and demonstrate the importance of mechanical microenvironment in modulating molecular signaling, gene expression, cell cycle, and functions in tumor cells.
The IC-indices of complete bipartite graphs
(2008-03-12)
Shiue, Chin-Lin
;
Fu, Hung-Lin
;
應用數學系
;
Department of Applied Mathematics
Let G be a connected graph, and let f be a function mapping V(G) into N. We define f(H) = Sigma(nu is an element of V(H)) f(nu) for each subgraph H of G. The function f is called an IC-coloring of G if for each integer k in the set {1, 2, ... , f(G)} there exists and (induced) connected subgraph H of G such that f(H) = k, and the IC-index of G, M(G), is the maximum value of f(G) where f is an IC-coloring of G. In this paper, we show that M(K-m,K-n) = 3.2(m+n-2)-2(m-2)+2 for each complete bipartite graph K-m,K-n, 2 <= m <= n.
Cross-sectional shape modulation of physical properties in ZnO and Zn(1-x)Co(x)O nanowires
(2008-03-12)
Wu, Z. Y.
;
Chen, I. J.
;
Lin, Y. F.
;
Chiu, S. P.
;
Chen, F. R.
We have prepared comparable-diameter ZnO and Zn(1-x)Co(x)O nanowires with both circular and hexagonal cross-sections. The average diameters are similar to 113 and similar to 134 nm for cylindrical and hexagonal nanowires, respectively. The as-grown nanowires have been characterized via structure, electrical conductivity and photoluminescence (PL) spectrum measurements. Pure ZnO nanowires were Co-ion implanted to make magnetic Zn(1-x)Co(x)O nanowires for magnetization studies. Bumpier edge surfaces on a nanometre scale, higher densities of stacking faults and a bending feature along the growth direction have been found in cylindrical ZnO nanowires. As compared with hexagonal nanowires, we have observed relatively higher conductivities in cylindrical nanowires, which implied large numbers of shallow donors existing in the latter nanowires. The cylindrical ZnO nanowires also displayed intensified green defect emission and considerably more stacking faults in the crystalline structure. In addition, we have found increased magnetization and stronger ferromagnetic ordering in cylindrical than in hexagonal Zn(1-x)Co(x)O nanowires, and have experimentally identified that the point defects of either Zn interstitials or O vacancies played governing roles in ferromagnetism. We conclude that the cross-sectional shape effect originating a varied point defect density can profoundly modulate the structural, electrical, optical as well as magnetic properties of ZnO and Zn(1-x)Co(x)O nanowires.
Heterogeneity-projection hard-decision interpolation method for color reproduction
(2008-03-13)
Tsai, Chi-Yi
;
Song, Kai-Tai
The present invention discloses a heterogeneity-projection hard-decision interpolation method for color reproduction, which utilizes a heterogeneity-projection method to determine the optimal edge direction and then utilizes a hard-decision rule to determine the optimal interpolation direction and obtain the information of the green color elements. The high-frequency information of the plane of the green color elements is incorporated into the processing of the planes of the red color elements and the blue color elements to reduce the restoration errors of the red and blue color elements. Therefore, the present invention can decrease the interpolation-direction errors and achieve a higher PSNR and a better visual effect.
Highly saturated red-emitting Mn (IV) activated phosphors and method of fabricating the same
(2008-03-13)
Chen, Teng-ming
;
Luo, Juih-Tzer
The present invention provides a light emitting device comprising a semiconductor light source emitting radiation at about 250˜500 nm; and a phosphor composition radiationally coupled to the semiconductor light source, wherein the phosphor composition is selected from the group consisting of Mg14(Ge(5-a)Mna)O24, Sr(Ge(4-b)Mnb)O9, Mg2(Ti(1-c)Mnc)O4, Zn2(Ti(1-d)Mnd)O4, SrMg(Al(10-e)Mne)O17, and Y3(Ga(5-f)Mnf)O12.
Barrierless reactions between two closed-shell molecules. I. Dynamics of F(2)+CH(3)SCH(3) reaction
(2008-03-14)
Lu, Yu-Ju
;
Lee, Lance
;
Pan, Jun-Wei
;
Xie, Tingxian
;
Witek, Henryk A.
A detailed experimental and theoretical investigation of the first-reported barrierless reaction between two closed-shell molecules [J. Chem. Phys. 127, 101101 (2007)] is presented. The translational energy and angular distributions of two product channels, HF+CH(2)SFCH(3) and F+CH(3)SFCH(3), determined at several collision energies, have been analyzed to reveal the dynamics of the studied reaction. Detailed analysis of the experimental and computational results supports the proposed reaction mechanism involving a short-lived F-F-S(CH(3))(2) intermediate, which can be formed without any activation energy. Other possible reaction mechanisms have been discriminated. The decay of the intermediate and competition between the two product channels have been discussed. (c) 2008 American Institute of Physics.
A new approach for quantitative determination of glucose by using CdSe/ZnS quantum dots
(2008-03-14)
Huang, Chin-Ping
;
Liu, Shu-Wei
;
Chen, Teng-Ming
;
Li, Yaw-Kuen
;
應用化學系
Quantitative detection of glucose is an important issue in food industry, various biotechnological processes and medication of metabolic disorders. Many ways have been developed to approach this target. In this study, we demonstrated a simple assay system containing glucose oxidase (GOD) and CdSe/ZnS quantum dots (QDs) for specific and quantitative detection of glucose, The role of QDs functioned as an "indicator" to reveal the acidity change of the assay system resulting from the enzymatic oxidation of glucose. By controlling the initial buffer conditions of the assay system at 10 mM or 30 mM phosphate, pH 8.0, the quench ratio of PL intensity of QDs at 586 nm was found to be linear to the tested glucose in the range of 0.2-10 mM or 2-30 mM, respectively. The assay system also provides a convenient way to determine the glucose concentration by visuahzing the color change of QDs fluorescence. As compare to most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, high flexibility, and good sensitivity. Furthermore, no complicated chemical modification and enzyme immobilization were needed in this system. (C) 2007 Elsevier B.V. All rights reserved.
Effect of annealing temperature for Si0.8Ge0.2 epitaxial thin films
(2008-03-15)
Chang, Yuan-Ming
;
Dai, Ching-Liang
;
Cheng, Tsung-Chieh
;
Hsu, Che-Wei
;
機械工程學系
This study investigates the effect of annealing temperature on the Si0.8Ge0.2 epitaxial layers. The Si0.8Ge0.2 epitaxial layers were deposited by using ultrahigh vacuum chemical vapor deposition (UHVCVD) with different annealing temperatures ((400-1000 degrees C). Various measurement technologies, including high-resolution X-ray diffraction ((HRXRD), atomic force microscopy ((AFM) and interfacial adhesion tester, were used to characterize the materials properties of the SiGe epilayers. The experimental results showed that the SiGe epilayers gradually reduced lattice-mismatch to the underlying substrate as annealing temperature increased (from 400 to 800 degrees C), which resulted from a high temperature enhancing interdiffusion between the epilayers and the underlying substrate. In addition, the average grain size of the SiGe films increased from 53.3 to 58 nm with increasing annealing temperature. The surface roughness in thin film annealed at 800 degrees C was 0.46 nm. Moreover, the interfacial adhesion strength increased from 476 +/- 9 to 578 +/- 12 kg/cm(2) with increasing the annealing temperature. (c) 2007 Elsevier B.V. All rights reserved.
Improving dielectric loss and enhancing figure of merit of Ba0.5Sr0.5Ti0.95Mg0.05O3 thin films doped by aluminum
(2008-03-15)
Lee, Shean-Yih
;
Chiou, Bi-Shiou
;
Lu, Horng-Hwa
;
電子工程學系及電子研究所
;
Innovative Packaging Research Center
The different Al contents effects of Ba0.5Sr0.5Ti0.95Mg0.05O3 (BSTM) thin films grown on Pt/TiN/SiO2/Si substrates in the crystallographic structure, surface morphology, dielectric constant, loss tangent, leakage current, and figure of merit were investigated. The BSTM films properties are studied as a function of Al content and have remarkable improvements including dielectric loss, leakage current, and figure of merit (FOM) as well as films grain sizes. With increasing Al content, the dielectric constant (k), tunability (T), loss tangent (tan delta), and leakage current density (J(L)) decrease while the FOM, defined as T/tan delta, and breakdown strength increases. The maximum dielectric constant at zero bias, tunability, dielectric loss, FOM, and leakage current density of 1 mol% Al-doped BSTM films at 280 kV cm(-1) are 248, 40%, 0.0093, 43, and 3.76 x 10(-7) A cm(-2), however, the same measured conditions of undoped BSTM films are 341, 54%, 0.0265, 20, and 1.19 x 10(-6) A cm(-2), respectively. The dc resistivity increases from 2.33 x 10(11) Omega cm of the BSTM film to 6.08 x 10(12) Omega cm of the 5 mol% Al-doped BSTM film at 280 kV cm(-1). In addition, the tolerance factor (t) of Al-doped BSTM perovskite thin films is 0.97 as compared to 0.87 of the undoped BSTM thin films. The increasing of tolerance factor value indicates that the specimens with Al-doped BSTM films are more stable than undoped specimens. (C) 2007 Elsevier B. V. All rights reserved.
Growth and structural characterization of ZnO on Y2O3/YSZ by pulsed laser deposition
(2008-03-15)
Lin, Chih-Wei
;
Ho, Yen-Teng
;
Chang, Li
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Pulsed laser deposition was used to form epitaxial Y2O3 buffer layers on yttria-stabilized zirconia (YSZ) (111) substrates, followed by formation of epitaxial ZnO. Structural characterization by X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) shows that Y2O(3) has high-quality crystalline characteristics with a smooth (111) surface, providing a good buffer for deposition of ZnO films on YSZ. For ZnO deposition, a two-step growth process had been adopted, which consisted of low-temperature nucleation and high-temperature growth. ZnO films on Y2O3/YSZ have good structural qualities in c-axis orientation with smooth surfaces. Electron diffraction patterns show an orientation relationship of [2 (1) over bar(1) over bar0](ZnO)//[0 (1) over bar1](Y2O3) and (0002)(ZnO)//(222)(Y2O3). High-resolution TEM clearly reveals that both the interfaces of ZnO/Y2O3 and Y2O3/YSZ are flat without the formation of any interlayers. (C) 2007 Elsevier B.V. All rights reserved.
Self-protecting dual-ring-architecture in time-sharing passive optical network to prevent the occurrence of fiber failure
(2008-03-15)
Yeh, C. H.
;
Lee, C. S.
;
Chi, S.
;
光電工程學系
;
Department of Photonics
We propose and experimentally investigate a self-protecting dual-ring-architecture time-division-multiplexed passive optical network (TDM-PON) using bidirectional dual-fiber path against the fiber-fault. By the proposed access network, the ring-based TDM-PON system can be revived promptly under single fiber failure. This restorable time is achieved within a few ms in the proposed ring access network. Moreover, the performance of data traffic in the optical access network has also discussed. (C) 2007 Elsevier B.V. All rights reserved.
Synthesis and characterization of a novel proton-exchange membrane for fuel cells operating at high temperatures and low Humidities
(2008-03-15)
Chaung, Ching-Nan
;
Chao, Liang
;
Huang, Ying-Jie
;
Hsieh, Tar-Hwa
;
Chuang, Hung-Yi
The synthesis of a p-toluidine/formal dehyde (PTF) resin was performed, and the effects of the molar ratio of the individual monomers and the polymerization conditions on the structure of the PTF resin were studied. Fourier transform infrared and C-13-NMR spectra were used to characterize the PTF. Wide-angle X-ray diffraction patterns revealed the crystalline structures of various PTFs. Polarized optical microscopy revealed that the molar ratio of the monomers had a strong effect on the crystalline morphologies. A longer polymerization time turned out a polymer with a higher intrinsic viscosity and molecular weight, which led to differences in the proton conductivity. All of the PTFs showed a higher proton conductivity than a commercial Nafion membrane at 90-100 degrees C and 0% relative humidity. The proton conductivity of the PTF series could be improved by sulfonation with sulfuric acid and could be maintained after blending with polyurethane. Pure methanol could be used as a fuel source because of the insolubility and nonwetting properties of PTF in methanol to increase the output current density for a PTF membrane electrode assembly. (C) 2007 Wiley Periodicals, Inc.
Sphere-separable partitions of multi-parameter elements
(2008-03-15)
Golanya, Boaz
;
Hwang, Frank K.
;
Rothbluma, Uriel G.
;
應用數學系
;
Department of Applied Mathematics
We show the optimality of sphere-separable partitions for problems where n vectors in d-dimensional space are to be partitioned into p categories to minimize a cost function which is dependent in the sum of the vectors in each category; the sum of the squares of their Euclidean norms; and the number of elements in each category. We further show that the number of these partitions is polynomial in n. These results broaden the class of partition problems for which an optimal solution is guaranteed within a prescribed set whose size is polynormially bounded in n. Applications of the results are demonstrated through examples. (C) 2007 Elsevier B.V. All rights reserved.
肺結核─可怕不可怕
(2008-03-16)
沈昭邦
;
Department of Communication and Technology
;
傳播與科技學系
可是我怕
《事發的19分鐘》
(2008-03-16)
薛怡凡
;
Department of Communication and Technology
;
傳播與科技學系
茱迪‧皮考特用文字精湛地揭露出美國現代社會所隱藏的嚴重青少年問題。當青少年在得不到家庭的溫暖，又沒有同儕的認同與長輩的指引下，個人與社會的不幸就此醞釀、發酵。
哈囉你今天公仔了嗎?
(2008-03-16)
姜建亨
;
Department of Communication and Technology
;
傳播與科技學系
便利商店不停推陳出新搶客源對7-11來說從一開始的HELLO KITTY 到前陣子的小叮噹無不造成一股熱潮這樣的消費現象到底是好的還是壞的??
《姊姊的守護者》身體不是我的
(2008-03-16)
陳惠玟
;
Department of Communication and Technology
;
傳播與科技學系
書評姊姊的守護者