Browsing by Issue Date, starting with "2012-02-17"

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Quenching effects of gold nanoparticles in nanocomposites formed in water-soluble conjugated polymer nanoreactors
(2012-02-17)
Yang, Po-Jen
;
Chu, Hsuan-Chih
;
Lee, Yu-Hsien
;
Kobayashi, Takayoshi
;
Chen, Te-Cheng
In this paper we describe the first example of the in situ synthesis of gold nanoparticles (AuNPs) in the presence of a water-soluble conjugated polyfluorene (NPF) presenting pendent ammonium groups, with the polymer acting as an aqueous surfactant and providing fluorescent nanoreactors. Using this approach, we produced well-dispersed NPF-AuNP nanocomposites without the need for any additional reducing agents. The photoluminescence emission intensity of NPF-AuNP nanocomposite solution was quenched to a greater extent upon increasing the concentration of AuNPs, presumably through energy transfer or electron transfer from the fluorescent polymer to the metal nanoparticles. Through variations in the degrees of protonation and deprotonation of the amino groups of NPF at different values of pH, we found that the extent of quenching of AuNPs in NPF-AuNP nanocomposite solutions was directly related to the adsorption and desorption behavior of NPF on the metal surfaces. Transmission electron microscopy revealed that the greatest aggregation of AuNPs in the nanocomposite solution occurred at pH 3. suggesting that the ammonium groups (RNMe2 at pH 8.5; RNMe2H+ at pH 3) of the polymer side chains adsorbed onto the AuNP surfaces under these conditions. Distinct time-resolved fluorescence signals of the AuNP-quenched NPF polymers at different values of pH confirmed the interactions between these species. (C) 2012 Elsevier Ltd. All rights reserved.
障害乗越え補助装置
(2012-02-17)
鄭璧瑩
;
黄健寶
白色発光蛍光体およびその発光装置
(2012-02-17)
陳登銘
;
張峻魁
交大e-News第112期
(2012-02-20)
Secretariat
;
國立交通大學秘書室
具環境光感測功能之液晶顯示器及其方法
(2012-02-21)
戴亞翔
;
何漢清
;
鄭枷彬
本發明係揭露一種具環境光感測功能之液晶顯示器及其方法。本方法首先將一電容耦接於一薄膜電晶體之源極，然後計算電容之電位因電荷減少而產生轉態所需要之轉態時間，再根據轉態時間來計算環境光的強度。本發明另揭露一種環境光感測電路，包括一薄膜電晶體、一電容及一讀出開關。當環境光變化時，薄膜電晶體之漏電流亦隨之變化，而使電容之電位轉態所需要的轉態時間產生變化，讀出開關便將電容之電位傳遞到資料讀出線，因而從轉態時間中計算出環境光的強度。本發明之液晶顯示器，則包括複數個電容、複數個讀出開關及一處理模組。
數位式快速鎖定頻率合成器
(2012-02-21)
陳巍仁
;
楊松諭
本發明主要為一種數位式鎖相迴路頻率合成裝置，具有高速鎖定以及低相位雜訊特性。其中鎖相迴路由一相位偵測器、可控制振盪器、自動動態調整迴路增益之迴路濾波器、回授相位積分電路、參考相位積分電路所組成。在迴路鎖定過程中，透過自動動態調整迴路增益之迴路濾波器，偵測積分電路輸出資訊以及相位偵測電路輸出資訊，動態的調整迴路濾波器中直饋路徑以及積分路徑的增益，使迴路鎖定速度加快。本案並提出一種高速計數器的電路，透過一組非同步計數器、資料擷取暫存器與取樣相位產生器，達成高速低功率之計數器。
No more CKY two-forms in the NHEK
(2012-02-21)
Mitsuka, Yoshihiro
;
Moutsopoulos, George
;
電子物理學系
;
Department of Electrophysics
We show that in the near-horizon limit of a Kerr-NUT-AdS black hole, the space of conformal Killing-Yano two-forms does not enhance and remains of dimension 2. The same holds for an analogous polar limit in the case of extremal NUT charge. We also derive the conformal Killing-Yano p-form equation for any background in an arbitrary dimension in the form of parallel transport.
微型光學讀取裝置
(2012-02-21)
陳政寰
;
蘇雅妮
本發明係揭露一種微型光學讀取裝置，用以提供一入射光至一光學記錄媒體，並接收來自此光學記錄媒體之反射光，此微型光學讀取裝置包含：一光源產生元件以產生此入射光；一軸向式分光元件用以根據入射光及反射光之極化方向，使此入射光完全穿透，並使此反射光發生偏折；一光偏極元件係設置於軸向式分光元件及光學記錄媒體之間，用以改變入射光及來自光學記錄媒體之反射光之極化方向；一像散式反射鏡係接收並像散聚焦來自軸向式分光元件之反射光，且進行反射；一光感測元件用以接收來自像散式反射鏡之反射光，並將其轉換為相應之電訊號。
Generalized path integral method for Elliott-Yafet spin relaxations in quantum wells and narrow wires
(2012-02-22)
Tsai, Jengjan
;
Chang, Cheng-Hung
;
物理研究所
;
Institute of Physics
We generalized the semiclassical path integral method originally used in the D'yakonov-Perel' mechanism to study the spin relaxation of the Elliott-Yafet mechanism in low-dimensional systems. In quantum wells, the spin properties calculated by this method confirmed the experimental results. In two-dimensional narrow wires, size and impurity effects on the Elliott-Yafet relaxation were predicted, including the wire-width-dependent relaxation time, the polarization evolution on the sample boundaries, and the relaxation behavior during the diffusive-ballistic transition. These properties were compared with those of the D'yakonov-Perel' relaxation calculated under similar conditions. For ballistic narrow wires, we derived an exact relation between the Elliott-Yafet relaxation time and the wire width, which confirmed the above simulations.
ADDRESS GENERATION APPARATUS AND METHOD FOR QUADRATIC PERMUTATION POLYNOMIAL INTERLEAVER
(2012-02-23)
LEE SHUENN-GI
;
WANG CHUNG HSUAN
;
SHEEN WERN-HO
An address generation apparatus for quadratic permutation polynomial (QPP) interleaver receives several configurable parameters and uses a plurality of QPP units to compute and outputs a plurality of interleaving addresses according to a QPP function Π(i)=(f1i+f2i2) mod k, where f1 and f2 are QPP coefficients, k is information block length of an input sequence, 0≦i≦k−1, and mod is a modulus operation. Each of the plurality of QPP units is a parallel computation unit, and outputs in parallel a corresponding group of interleaver addresses, where Π(i) is also a ith interleaving address generated by the apparatus.
DRY ELECTRODE FOR BIOMEDICAL SIGNAL MEASURING SENSOR
(2012-02-23)
LIN CHIN-TENG
;
LIAO LUN-DE
A dry electrode for biomedical signal measuring sensor includes a conductive sponge, a conductive fabric, and a thin metal film. The conductive fabric covers the whole conductive sponge, and the thin metal film is disposed on one face of the conductive fabric opposite to the conductive sponge. When using the dry electrode in measuring biomedical signal, it is not necessary to apply a conductive gel on a patient's skin, at where the biomedical signal is to be measured. Without the need of applying the conductive gel, the dry electrode is readily for measuring biomedical signal at any time and can be conveniently used in measuring signal over a long period of time without the problem of an attenuated signal due to gradually becoming dried conductive gel.
DATA-AWARE DYNAMIC SUPPLY RANDOM ACCESS MEMORY
(2012-02-23)
Chuang Ching-Te
;
Yang Hao-I
;
Lin Yi-Wei
;
Hwang Wei
;
Shih Wei-Chiang
A Random Access Memory (RAM) with a plurality of cells is provided. In an embodiment, the cells of a same column are coupled to a same pair of bit-lines and are associated to a same power controller. Each cell has two inverters; the power controller has two power-switches. For the cells of the same column, the two power-switches respectively perform independent supply voltage controls for the two inverters in each cell according to data-in voltages of the bit-lines during Write operation.
Extended object tunneling: Current-carrying states of Abrikosov vortices in a superconductor with artificial nanobarriers
(2012-02-24)
Rosenstein, B.
;
Shapiro, I.
;
Shapiro, B. Ya.
;
Li, Dingping
;
Frydman, A.
We consider the structure and dynamics of two-dimensional fluxons created by a magnetic field in a type-II superconductor film with critical temperature T-1 in the presence of nanostripes of material with a higher critical temperature T-2. The width of the stripes is of the order of the coherence length xi. Such a stripe plays the role of a potential barrier for vortices. When subjected to the current J parallel to the stripe, vortices move toward the barrier. Below the critical current J(c), the flux flow is effectively halted by the barrier, while above J(c), flux penetrates the stripe and passes the barrier. The mechanism of the barrier penetration ("soliton tunneling" occurs even at zero temperature) is rather unusual: the vortices adjust their shape, and upon passing the barrier, they shrink their cores. The critical current and the I-V curves are calculated numerically and analytically using variational approach.
サスペンデッドナノワイヤチャネルを有するトランジスタ構造とその製造方法
(2012-02-24)
林鴻志
;
蘇俊榮
;
徐行徽
;
李冠樟
Seismic spectral acceleration assessment of masonry in-filled reinforced concrete buildings by a coefficient-based method
(2012-02-25)
Su, R. K. L.
;
Lee, C. L.
;
Wang, Y. P.
;
土木工程學系
;
Department of Civil Engineering
This study explores a coefficient-based seismic capacity assessment method with a special emphasis on low-rise masonry in-filled (MI) reinforced concrete (RC) buildings subjected to earthquake motion. The coefficient-based method without requiring any complicated finite element analysis is a simplified procedure to assess the maximum spectral acceleration capacity of buildings. This paper first compares the fundamental periods of MI RC structures obtained, respectively, from experimental period data and empirical period-height formulas. The coefficient-based method for low-rise masonry buildings is then calibrated by the published experimental results obtained from shaking table tests. The comparison of the experimental and estimated results indicates that the simplified coefficient-based method can provide good approximations of the maximum spectral accelerations at peak loads of the low-rise masonry reinforced concrete buildings if a proper set of drift factors and initial fundamental vibration periods of structures are used.
Annealing Effect on Electrospun Polymer Fibers and Their Transformation into Polymer Microspheres
(2012-02-27)
Fan, Ping-Wen
;
Chen, Wan-Ling
;
Lee, Ting-Hsien
;
Chen, Jiun-Tai
;
應用化學系
Electrospinning is a simple and convenient technique to produce polymer fibers with diameters ranging from several nanometers to a few micrometers. Different types of polymer fibers have been prepared by electrospinning for various applications. Among different post-treatment methods of electrospun polymer fibers, the annealing process plays a critical role in controlling the fiber properties. The morphology changes of electrospun polymer fibers under annealing, however, have been little studied. Here we investigate the annealing effect of electrospun poly(methyl methacrylate) (PMMA) fibers and their transformation into PMMA microspheres. PMMA fibers with an average size of 2.39 mu m are first prepared by electrospinning a 35 wt% PMMA solution in dimethylformamide. After the electrospun fibers are thermally annealed in ethylene glycol, a non-solvent for PMMA, the surfaces of the fibers undulate and transform into microspheres driven by the Rayleigh instability. The driving force of the transformation process is the minimization of the interfacial energy between the polymer fibers and ethylene glycol. The sizes of the microspheres fit well with the theoretical predictions. Longer annealing times are found to be required at lower temperatures to obtain the microspheres.
Orthogonally polarized dual-wavelength Nd:LuVO4 laser at 1086 nm and 1089 nm
(2012-02-27)
Huang, Y. P.
;
Cho, C. Y.
;
Huang, Y. J.
;
Chen, Y. F.
;
電子物理學系
A comparison between the fluorescence spectra of the Nd-doped vanadate crystals (Nd:YVO4, Nd:GdVO4, Nd:LuVO4) for the F-4(3/2) -> I-4(11/2) transition is studied. We numerically analyze the condition of gain-to-loss balance via an uncoated intracavity etalon to achieve the dual-wavelength operation. We further experimentally demonstrate the orthogonally polarized dual-wavelength laser with a single Nd:LuVO4 crystal. The simultaneous dual-wavelength Nd:LuVO4 laser at 1085.7 nm in sigma polarization and 1088.5 nm in pi polarization is realized. At an incident pump power of 12 W, the average output power obtained at 1085.7 nm and 1088.5 nm is 0.4 W and 1.7 W, respectively. (c) 2012 Optical Society of America
Two-step photoionization of trans-stilbene in acetonitrile via an ion-pair precursor studied with picosecond time-resolved absorption and Raman spectroscopies
(2012-02-27)
Miki, Hiroko
;
Yoshida, Kyousuke
;
Kawate, Chieko
;
Shimada, Rintaro
;
Takaya, Tomohisa
Picosecond time-resolved visible absorption and Raman spectra of trans-stilbene in acetonitrile have been measured. A new transient absorption band is observed at 440 nm, whose decay time constant coincides with that of the rise of the radical cation. In addition to the known Raman bands of the radical cation, a new Raman feature showing a fast decay is found at 1599 cm(-1). We assign the 440 nm absorption band and the 1599 cm(-1) Raman band to a precursor of the radical cation. The precursor may well be an ion pair that holds an ejected electron still around the cation. (C) 2012 Elsevier B. V. All rights reserved.
Room temperature polariton lasing vs. photon lasing in a ZnO-based hybrid microcavity
(2012-02-27)
Lu, Tien-Chang
;
Lai, Ying-Yu
;
Lan, Yu-Pin
;
Huang, Si-Wei
;
Chen, Jun-Rong
We report on the room temperature polariton lasing and photon lasing in a ZnO-based hybrid microcavity under optical pumping. A series of experimental studies of the polariton lasing (exciton-photon detunings of delta = -119meV) in the strong-coupling regime are discussed and compared to a photon lasing (delta = -45meV) in the weak-coupling regime obtained in the same structure. The measured threshold power density (31.8kW/cm(2)) of polariton lasing is one order of magnitude lower than that of the photon lasing (318.2kW/cm(2)). In addition, the comparison between polariton lasing and photon lasing is done in terms of the linewidth broadening, blue-shift of the emission peak, and polarization. (C) 2012 Optical Society of America
Optimal Te-doping in GaSe for non-linear applications
(2012-02-27)
Ku, Shin An
;
Chu, Wei-Chen
;
Luo, Chih Wei
;
Andreev, Yu. M.
;
Lanskii, Grigory
Centimeter-sized Te-doped GaSe ingots were grown from the charge compositions of GaSe with nominals 0.05, 0.1, 0.5, 1, and 3 mass% Te, which were identified as e -GaSe: Te (0.01, 0.07, 0.38, 0.67, and 2.07 mass%) single crystals. The evolution of the absorption peaks of the phonon modes E'((2)) (similar to 0.584 THz) and E"((2)) (1.77 THz) on Te-doping in GaSe: Te crystals was studied by THz time-domain spectroscopy. This study proposes that the evolution of both E'((2)) and E"((2)) absorption peaks correlates well with the optical quality of Te-doped GaSe crystals, which was confirmed by experimental results on the efficiency of THz generation by optical rectification. Maximal intensity of the absorption peak of the rigid layer mode E'((2)) is proposed as a criterion for identification of optimal Te-doping in GaSe crystals. (C) 2012 Optical Society of America