Browsing by Issue Date, starting with "2010-03-29"

Now showing 1 - 20 of 46606

High pressure effect on the ultrafast energy relaxation rate of LDS698 (C19H23N2O4Cl) in a solution
(2010-03-29)
Liu, Bingguo
;
He, Chunyuan
;
Jin, Mingxing
;
Wang, Qiaoqiao
;
Lin, Sheng Hsien
Effects of high pressure in a range of up to 1.7 GPa on ultrafast energy relaxation of LDS698 (C19H23N2O4Cl) molecules in solution have experimentally been illustrated by a method of femtosecond time-resolved absorption spectroscopy. The rates of the intramolecular and intermolecular energy relaxations show quite different pressure dependences. The observed results are in good agreement with the theoretical interpretation based on the pressure influences on the molecular energy gaps, the intermolecular H-bond interaction, and the solution viscosity. (C) 2010 Optical Society of America
High pressure effect on the ultrafast energy relaxation rate of LDS698 (C(19)H(23)N(2)O(4)Cl) in a solution
(2010-03-29)
Liu, Bingguo
;
He, Chunyuan
;
Jin, Mingxing
;
Wang, Qiaoqiao
;
Lin, Sheng Hsien
Effects of high pressure in a range of up to 1.7 GPa on ultrafast energy relaxation of LDS698 (C(19)H(23)N(2)O(4)Cl) molecules in solution have experimentally been illustrated by a method of femtosecond time-resolved absorption spectroscopy. The rates of the intramolecular and intermolecular energy relaxations show quite different pressure dependences. The observed results are in good agreement with the theoretical interpretation based on the pressure influences on the molecular energy gaps, the intermolecular H-bond interaction, and the solution viscosity. (C) 2010 Optical Society of America
Study of electric characteristics and diffusion effects of 2-methyl-9,10-di(2-naphthyl)anthracene doped with cesium fluoride by admittance spectroscopy
(2010-03-29)
Hsieh, Ming-Ta
;
Ho, Meng-Huan
;
Lin, Kuan-Heng
;
Chen, Jenn-Fang
;
Chen, Teng-Ming
In this work, the admittance spectroscopy studies show that doping cesium fluoride (CsF) into 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) can greatly decrease the resistance of MADN and raises the Fermi level from deep level to only 0.1 eV below the lowest unoccupied molecular orbital, resulting in enhancing the electron injection. In addition, the diffusion width of CsF from doped MADN layer into tris(8-quinolinolato)aluminium is clearly observed by capacitance-frequency measurement and is about 9.4 nm. Moreover, the diffusion width is significant to be affected by external thermal.
Direct backward third-harmonic generation in nanostructures
(2010-03-29)
Chang, Chieh-Feng
;
Chen, Hsing-Chao
;
Chen, Miin-Jang
;
Liu, Wei-Rein
;
Hsieh, Wen-Feng
Direct-backward third harmonic generation (DBTHG) has been regarded as negligible or even inexistent due to the large value of wave-vector mismatch. In the past, BTHG signals were often interpreted as back-reflected or back-scattered forward-THG (FTHG). In this paper, we theoretically and experimentally demonstrate that backward third harmonic waves can be directly generated, and that their magnitude can be comparable with FTHG in nanostructures. Experimental data of DBTHG from ZnO thin films, CdSe quantum dots and Fe(3)O(4) nanoparticles agree well with simulation results based on the Green's function. An integral equation was also derived for fast computation of DBTHG in nano films. Our investigation suggests that DBTHG can be a potentially powerful tool in nano-science research, especially when combined with FTHG measurements. (C) 2010 Optical Society of America
Electrically surface-driven switchable wettability of liquid crystal/polymer composite film
(2010-03-29)
Chiu, Ya-Ping
;
Shen, Cheng-Yu
;
Wang, Wen-Ching
;
Chu, Ting-Yu
;
Lin, Yi-Hsin
This study demonstrates the electrical control of the surface wettability of liquid crystal and polymer composite film. The application of external voltages significantly affects the surface wettability of the film. This study uses atomic force microscopy to quantitatively characterize the fundamental mechanism responsible for the structurally driven changes in surface properties at various applied voltages. The surface wettability transitions of the film are electrically driven, as shown by reorganized liquid crystal molecules. Measurements of the voltage-dependent surface wettability of the composite film suggest approaches to supporting control applications of future electro-optical nanotechnology devices.
Microstructure of a-plane ZnO grown on LaAlO3 (001)
(2010-03-31)
Wang, Wei-Lin
;
Peng, Chun-Yen
;
Ho, Yen-Teng
;
Chang, Li
;
材料科學與工程學系
The microstructure of a-plane ZnO grown on LaAlO3 (LAO) (001) has been systematically investigated by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the results of XRD and TEM, only a-plane ZnO has been found to grow on LAO (001). and it consists of two types of domains perpendicular to each other The crystal orientation relationships of a-plane ZnO domains with LAO have been verified to be (0001)(ZnO)//[110](LAO) and [1 (1) over bar 00](ZnO)// [1 (1) over bar0](LAO). The domain boundaries in the a-plane ZnO are along the direction in a rotation angle of about 45 degrees from the c-axes of ZnO. The surface morphology of ZnO films in SEM exhibits domain structure in stripe-like shape The formation of two domains can be attributed to the cubic symmetry of the surface configuration of LAO (001). 0 2009 Elsevier B V All rights reserved
Substrate engineering of LaAlO3 for non-polar ZnO growth
(2010-03-31)
Ho, Yen-Teng
;
Wang, Wei-Lin
;
Peng, Chun-Yen
;
Chen, Wei-Chun
;
Liang, Mei-Hui
We demonstrate that growth of non-polar ZnO in a-plane and m-plane can be achieved through substrate engineering of LaAlO3 with (001) and (112) surface X-ray diffraction, reflection high energy electron diffraction and cross-sectional transmission electron microscopy with selected area diffraction reveal that a-plane ZnO on LaAlO3 (001) consists of two types of domains perpendicular to each other with in-plane orientation relationships of [000](ZnO)//[1 (1) over bar0](LAO) and [1 (1) over tilde 00](ZnO)//[1 (1) over bar0](LAO) Single domain epitaxy of m-plane ZnO on LaAlO3 (112) can be obtained with in-plane orientation relationships of (10 (1) over bar0)(ZnO)//(112)(LAO), [0001](ZnO)//[(1) over bar 10](LAO) and [1 (2) over bar 10](ZnO)//[(1) over bar(1) over bar1](LAO). (C) 2009 Elsevier B.V All rights reserved
Microstructure of a-plane ZnO grown on LaAlO(3) (001)
(2010-03-31)
Wang, Wei-Lin
;
Peng, Chun-Yen
;
Ho, Yen-Teng
;
Chang, Li
;
材料科學與工程學系
The microstructure of a-plane ZnO grown on LaAlO(3) (LAO) (001) has been systematically investigated by employing X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the results of XRD and TEM, only a-plane ZnO has been found to grow on LAO (001). and it consists of two types of domains perpendicular to each other The crystal orientation relationships of a-plane ZnO domains with LAO have been verified to be (0001)(ZnO)//[110](LAO) and [1 (1) over bar 00](ZnO)// [1 (1) over bar0](LAO). The domain boundaries in the a-plane ZnO are along the direction in a rotation angle of about 45 degrees from the c-axes of ZnO. The surface morphology of ZnO films in SEM exhibits domain structure in stripe-like shape The formation of two domains can be attributed to the cubic symmetry of the surface configuration of LAO (001). 0 2009 Elsevier B V All rights reserved
Substrate engineering of LaAlO(3) for non-polar ZnO growth
(2010-03-31)
Ho, Yen-Teng
;
Wang, Wei-Lin
;
Peng, Chun-Yen
;
Chen, Wei-Chun
;
Liang, Mei-Hui
We demonstrate that growth of non-polar ZnO in a-plane and m-plane can be achieved through substrate engineering of LaAlO(3) with (001) and (112) surface X-ray diffraction, reflection high energy electron diffraction and cross-sectional transmission electron microscopy with selected area diffraction reveal that a-plane ZnO on LaAlO(3) (001) consists of two types of domains perpendicular to each other with in-plane orientation relationships of [000](ZnO)//[1 (1) over bar0](LAO) and [1 (1) over tilde 00](ZnO)//[1 (1) over bar0](LAO) Single domain epitaxy of m-plane ZnO on LaAlO(3) (112) can be obtained with in-plane orientation relationships of (10 (1) over bar0)(ZnO)//(112)(LAO), [0001](ZnO)//[(1) over bar 10](LAO) and [1 (2) over bar 10](ZnO)//[(1) over bar(1) over bar1](LAO). (C) 2009 Elsevier B.V All rights reserved
The C-Terminus of a Subunit Determines The Catalytic Activity of AMP-activated Protein Kinase
(2010-04-01)
Cui, Xiaopei
;
Gao, Haiqing
;
Hwang, Jenn-Kang
;
Shyy, John Y-J
;
生物資訊及系統生物研究所
A Robust Channel Estimator for High-Mobility STBC-OFDM Systems
(2010-04-01)
Chen, Hsiao-Yun
;
Ku, Meng-Lin
;
Jou, Shyh-Jye
;
Huang, Chia-Chi
;
電機工程學系
In this paper, a robust channel estimator for high-mobility space-time block code-orthogonal frequency division multiplexing (STBC-OFDM) systems is proposed and applied in IEEE 802.16e systems. A high-performance two-stage channel estimation method is adopted. The proposed architecture reduces computational complexity effectively and improves 85.2% of the hardware implementation. The performances of the proposed design have been demonstrated through the simulation of an STBC-OFDM system with two transmit antennas and one receive antenna. At the vehicle speed of 120 and 240 km/hr for quadrature phase shift keying (QPSK) modulation, the proposed design can achieve the bit-error rate (BER) of about 10(-4) and 10(-3) without using channel coding. Moreover, it has significant performance improvement as compared with interpolation-based channel estimation methods. The proposed channel estimator implemented in 90 nm CMOS technology can support up to 29.03 Mbps (uncoded) downlink data transmission. The design only requires 859.6 K gates and dissipates 43.71 mW at 83.3 MHz operating frequency with 1 V power supply.
Impacts of Coulomb Interactions on the Magnetic Responses of Excitonic Complexes in Single Semiconductor Nanostructures
(2010-04-01)
Chang, Wen-Hao
;
Lin, Chia-Hsien
;
Fu, Ying-Jhe
;
Lin, Ta-Chun
;
Lin, Hsuan
We report on the diamagnetic responses of different exciton complexes in single InAs/GaAs self-assembled quantum dots (QDs) and quantum rings (QRs). For QDs, the imbalanced magnetic responses of inter-particle Coulomb interactions play a crucial role in the diamagnetic shifts of excitons (X), biexcitons (XX), and positive trions (X (-) ). For negative trions (X (-) ) in QDs, anomalous magnetic responses are observed, which cannot be described by the conventional quadratic energy shift with the magnetic field. The anomalous behavior is attributed to the apparent change in the electron wave function extent after photon emission due to the strong Coulomb attraction by the hole in its initial state. In QRs, the diamagnetic responses of X and XX also show different behaviors. Unlike QDs, the diamagnetic shift of XX in QRs is considerably larger than that of X. The inherent structural asymmetry combined with the inter-particle Coulomb interactions makes the wave function distribution of XX very different from that of X in QRs. Our results suggest that the phase coherence of XX in QRs may survive from the wave function localization due to the structural asymmetry or imperfections.
Pulsed Electromagnetic Fields Accelerate Proliferation and Osteogenic Gene Expression in Human Bone Marrow Mesenchymal Stem Cells During Osteogenic Differentiation
(2010-04-01)
Sun, Li-Yi
;
Hsieh, Dean-Kuo
;
Lin, Po-Cheng
;
Chiu, Hsien-Tai
;
Chiou, Tzyy-Wen
Osteogenesis is a complex series of events involving the differentiation of mesenchymal stem cells to generate new bone. In this study, we examined the effect of pulsed electromagnetic fields (PEMFs) on cell proliferation, alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and gene expression in bone marrow mesenchymal stem cells (BMMSCs) during osteogenic differentiation. Exposure of BMMISCs to PEMFs increased cell proliferation by 29.6% compared to untreated cells at day 1 of differentiation. Semi-quantitative RT-PCR indicated that PEMFs significantly altered temporal expression of osteogenesis-related genes, including a 2.7-fold increase in expression of the key osteogenesis regulatory gene cbfa1, compared to untreated controls. In addition, exposure to PEMFs significantly increased ALP expression during the early stages of osteogenesis and substantially enhanced mineralization near the midpoint of osteogenesis. These results suggest that PEMFs enhance early cell proliferation in B M MSC-mediated osteogenesis, and accelerate the osteogenesis. Bioelectromatmetics 31:209-219, 2010. (C) 2009 Wiley-Liss, Inc.
Crystal quality improvement of a-plane GaN using epitaxial lateral overgrowth on nanorods
(2010-04-01)
Ling, Shih-Chun
;
Chao, Chu-Li
;
Chen, Jun-Rong
;
Liu, Po-Chun
;
Ko, Tsung-Shine
The crystal quality of a-plane GaN films was improved by using epitaxial lateral overgrowth on nanorod GaN template. The scanning electron microscope images showed the fully coalesced regrowth process completed within only 2 mu m thickness. The a-plane GaN films grown on nano-rod template showed superior surface quality and less surface pits. The on-axis and off-axis FWHMs of X-ray rocking curves decreased with the increase in the etching depth of the nano-rod template. TEM analysis revealed that the dislocation density was reduced to around 1.2 x 10(9) cm(-2) by the nano-rod epitaxial lateral overgrowth. In addition, the photoluminescence intensity of the a-plane GaN was enhanced significantly. These results demonstrated the opportunity of achieving a-plane GaN films with high crystal quality via nano-rod epitaxial lateral overgrowth. (C) 2009 Elsevier B.V. All rights reserved.
Hemoglobin induced oxidative stress is associated with both endogenous peroxidase activity and H2O2 generation from polyunsaturated fatty acids
(2010-04-01)
Cheng, Tsai-Mu
;
Pan, Ju-Pin
;
Chen, Hong-Wei
;
Chang, Yi-Chun
;
Chang, Chia-Ching
AN OPTIMAL MARKET ENTRY/EXIT EVALUATION MODEL WITH PARTIAL FINANCING FUNDS
(2010-04-01)
Lin, Tyrone T.
;
Ko, Chuan-Chuan
;
Liu, Chien-Yu
;
經營管理研究所
;
Institute of Business and Management
The paper mainly aims to introduce the real options approach to construct an evaluation model for the firm value under partial financing funds. The paper examines that production volume follows the geometric Brownian motion and considers that both the market entry of investment cost and the market exit of withdrawal cost match the linear function with production volume. Then the paper evaluates the potential firm value before market entry, the operational value with the firm's operating, and the market exit value with the firm's stopping to operate so as to assess the whole firm value, shareholder value, and bondholder value hereafter. The results show that different debt ratios will affect the firm's investment decision. The paper figures out the optimal decision-making based on the maximum profit of shareholders or the maximum profit of shareholders-and-bondholders. The factor is finance leverage; although interest expenses are tax deductible, an overly high leverage may trigger agency costs for a firm, which will offset the tax shields associated with leverage. Therefore, a firm should not leverage too much. Furthermore, the paper constructs an innovative evaluation model in a dynamic financing environment in order to provide the management team with a decision-making mechanism for their decisions in market entry or market exit in a timely manner in the face of uncontrollable exogenous variables.
Experimental and theoretical studies of Sn(3-delta)Pb(delta)Bi(2)Se(6) (delta=0.0-0.7)
(2010-04-01)
Chen, Kuei-Bo
;
Lee, Chi-Shen
;
應用化學系
;
Department of Applied Chemistry
New ternary and quaternary chalcogenides, Sn(3-delta)Pb(delta)Bi(2)Se(5) (delta=0.0-0.7), were synthesized from pure elements using the solid-state method. Their crystal structures, determined using single crystal X-ray diffraction, belong to the orthorhombic space group Pnma (No. 62). The structure is related to Pb(3)Bi(2)S(6), which contains NaCl [311] layer units and zigzag arrays of metal atoms along the c-axis. A correlation between the Pb composition and the shifted position of a metal site was observed. Band structure calculations confirmed that the structure is stabilized when the position of the M5 site is farther from the mirror plane. Thermopower and conductivity measurements indicated that all of the compounds are n-type semiconductors with small band gaps. (C) 2010 Elsevier Inc. All rights reserved.
Magnetic fluctuations in FeSe1-delta and Cu-doped FeSe1-delta: Se-77 NMR experiments
(2010-04-01)
Young, Ben-Li
;
Wu, Jack
;
Huang, Tzu-Wen
;
Yeh, Kuo-Wei
;
Wu, Maw-Kuen
The roles of Se deficiency and Fe atoms, for the superconductivity of FeSe, have been, respectively, investigated in FeSe1-delta and (Fe1-xCux)Se1-delta, by our NMR experiments. The data, for nuclear spin-lattice relaxation rate (1/T-1), show that the spin fluctuations are weakened at a larger delta, and are correlated with the superconductivity in FeSe. The superconducting volume fraction, estimated by our ac susceptibility experiments, is found to vary inversely with delta. Our findings suggest that the Se-deficient FeSe has an inhomogeneous phase, where the superconductivity is associated with the regions having few or no Se vacancies. As for (Fe1-xCux)Se1-delta, T-c is rapidly suppressed by Cu doping and vanishes around x=0.03. The Se-77 and the Cu-63 NMR linewidths suggest that a local moment is induced at the Fe sites and not at the Cu sites. However, 1/T-1 shows no obvious change with the Cu doping. We suspect that other effects, such as disorder or change in the density of states, have more influence on T-c suppression since a metal-insulator transition, induced by Cu substitution, occurs in the resistivity measurements.
A multi-subwaveform parametric retracker of the radar satellite altimetric waveform and recovery of gravity anomalies over coastal oceans
(2010-04-01)
Guo JinYun
;
Gao YongGang
;
Hwang, CheinWay
;
Sun JiaLong
;
土木工程學系
The quality of satellite radar altimetric data is very important in studies of geodesy, geophysics, and oceanography. Over coastal oceans, altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open oceans. Here we develop a new multi-subwaveform parametric retracker (MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal oceans. The least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric data. The waveform data records from Geosat/GM around Taiwan Island are practically retracked with MSPR. When compared with the Taiwan geoid height, the results retracked by MSPR are more accurate than those retracked by the well-known beta-5-parmeter method and from the geophysical data records (GDRs). The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares collocation. When we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean, we found that the results from retracked data are more accurate than those from GDRs.
Asymmetric gate capacitance and dynamic characteristic fluctuations in 16 nm bulk MOSFETs due to random distribution of discrete dopants
(2010-04-01)
Lee, Kuo-Fu
;
Li, Yiming
;
Hwang, Chih-Hong
;
傳播研究所
;
電機工程學系
Characteristic variability of a transistor is a crucial issue for nanoscale metal-oxide-semiconductor field-effect transistors (MOSFETs). In this study, we explore the asymmetric sketch of the random dopant distribution near the source end and the drain end in 16 nm MOSFETs. Discrete dopants near the source and drain ends of the channel region induce rather different fluctuations in gate capacitance and dynamic characteristics. Based upon the observed asymmetry properties, a lateral asymmetry channel doping profile engineering is then proposed to suppress the random-dopant-induced characteristic fluctuations in the examined devices and circuits. The results of this study indicate that the fluctuations in average gate capacitance, circuit gain, 3 db bandwidth and unity-gain bandwidth for the cases with dopants near the drain side could be simultaneously reduced by 62.6%, 22.2%, 63.1% and 41.4%, respectively. Consequently, such a lateral asymmetry channel doping profile could be considered to design intrinsic parameter fluctuation resistant transistors.