Browsing by Issue Date, starting with "2002-12-05"

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Crystallization behavior of syndiotactic polystyrene nanocomposites for melt- and cold-crystallizations
(2002-12-05)
Tseng, CR
;
Wu, SC
;
Wu, JJ
;
Chang, FC
;
應用化學系
Analyses of the effects of montmorillonite (clay) on the crystallinity and crystallization behavior of syndiotactic polystyrene (s-PS) were investigated by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The dispersibility of the clay in s-PS nanocomposites was studied by X-ray and transmission electron microscopy (TEM). The clay was dispersed into the s-PS matrix by melt blending on a scale of 1-2 nm or few tenths-100 nm, depending on the surfactant treatment. On adding clay, the crystallization behavior of the s-PS tends to convert into the beta-crystal from the alpha-crystal after being cold-crystallized because the clay plays a vital role in facilitating the formation of the thermodynamically favored beta-form crystal when the s-PS is cold- or melt-crystallized. This phenomenon leads to a change in a conventional mechanism of molecular packing for the s-PS. Evidently, the clay significantly affects the crystallinity and crystallization behavior of the s-PS. (C) 2002 Wiley Periodicals, Inc.
「四小門閥」展覽
(2002-12-06)
本報訊
四小門閥作品展明登場
(2002-12-06)
本報訊
Analysis of chitin oligosaccharides by capillary electrophoresis with laser-induced fluorescence
(2002-12-06)
Wang, CY
;
Hsieh, YZ
;
應用化學系
;
Department of Applied Chemistry
A method, using capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection for analyzing chitin oligosaccharides is described. Chitin oligosaccharides were derivatized with 9-aminopyrene-1,4,6-trisulfonate (APTS) via reductive amination at 37 degreesC for 16 h (optimized conditions). The APTS-chitin oligosaccharides were analyzed using either an acidic citric acid-phosphate buffer or an alkaline borate buffer. The effects of buffer types, buffer pH values, and buffer concentrations on the separation were examined. The analytes were successfully separated by using a pH 4.6 citric acid-phosphate within 19 min. The APTS-derivatized chitin monosaccharide (D-glucosamine) migrated first. The analytes were also completely separated by using a pH 9.0 borate buffer within 24 min. Moreover, the specificity of enzyme digestion on chitin polysaccharides using the optimized APTS labeling procedure and the CE-LIF method was demonstrated. (C) 2002 Elsevier Science B.V. All rights reserved.
月亮小手外一章
(2002-12-07)
管管
管管等人舉辦 <四人門閥>聯展
(2002-12-07)
本報訊
Elastic solutions for stresses in a transversely isotropic half-space subjected to three-dimensional buried parabolic rectangular loads
(2002-12-10)
Wang, CD
;
Liao, JJ
;
土木工程學系
;
Department of Civil Engineering
In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half-space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half-space, induced by three-dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian coordinate system for a transversely isotropic half-space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half-spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright (C) 2002 John Wiley Sons, Ltd.
Numerical range of Aluthge transform of operator
(2002-12-15)
Wu, PY
;
應用數學系
;
Department of Applied Mathematics
For any operator A on a Hilbert space, let (A) over tilde denote its Aluthge transform. In this paper, we prove that the closure of the numerical range of (A) over tilde is always contained in that of A. This supplements the recently proved case for dim ker A less than or equal to dim ker A* by Yamazaki, and partially confirms a conjecture of Jung, Ko and Pearcy. (C) 2002 Elsevier Science Inc. All rights reserved.
尖石黑色部落植入文學步道
(2002-12-15)
李令儀
New nanometer T-gate fabricated by thermally reflowed resist technique
(2002-12-15)
Lee, HM
;
Chang, EY
;
Chen, SH
;
Chang, CY
;
電子工程學系及電子研究所
Novel nanometer T-gate process has been developed utilizing electron beam (EB) lithography and thermally reflowed resist technique. Through well-controlled EB exposure dosage, heating time and reflow temperature; the resist structures can be efficiently reflowed to form the desired T-gate configuration with dimension ranging from 150 nm to 30 nm. After Ti/Pt/Au metal deposition by electron gun evaporation and lift-off process, the nanometer T-gates with thickness of about 500 nm were formed. With the optimized conditions, ultra-short 30 nm T-shaped gate was clearly demonstrated on the GaAs substrate. This is the smallest T-gate reported with the thermally reflowed technique in the literature so far and can practically be used in the GaAs monolithic microwave integrated circuit (MMIC) fabrications.
Fabrication of light-shaping diffusion screens
(2002-12-15)
Lu, YT
;
Chi, S
;
光電工程學系
;
Department of Photonics
This study presents the fabrication of alight-shaping diffuser, made by recording the far field laser speckles projected from a ground glass on photoresist plate. Elliptical speckles are created by illuminating the ground glass with a line shape He-Cd laser beam. The recorded elliptical speckles can diffuse incident light into different spread angles in vertical and horizontal directions. The speckles are inscribed with the appropriate density and depth on the surface, to diffuse incident light uniformly without a hot spot, by controlling the separation and duration of exposures. A nickel master is then electro-formed from the speckled plate for embossing the pattern on plastic plate for mass production. The diffuser is used in front and rear projection screens with high gain, the displays of ATMs, LED display illumination shapers, LCD backlight and laser beam shaping homogenizers as well as other applications. (C) 2002 Elsevier Science B.V. All rights reserved.
Generalization of Yang et al.'s method for fuzzy programming with piecewise linear membership functions
(2002-12-16)
Lin, CC
;
Chen, AP
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Li and Yu (Fuzzy Sets and Systems 101 (1999) 109) argued that the model of Yang et al. for fuzzy programming (Fuzzy Sets and Systems 41 (1991) 39) is correct only for a specific type of piecewise linear membership function and proposed their model for other type of membership functions. This study generalizes the model of Yang et al. A numerical example indicates that the model of Li and Yu is inapplicable to a fuzzy programming problem that involves more than one membership function, whereas the proposed model gives the optimal solution. (C) 2002 Elsevier Science B.V. All rights reserved.
Ring embedding in faulty honeycomb rectangular torus
(2002-12-16)
Cho, HJ
;
Hsu, LY
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
Assume that m and n are positive even integers with n greater than or equal to 4. The honeycomb rectangular torus HReT(m,n) is recognized as another attractive alternative to existing torus interconnection networks in parallel and distributed applications. It is known that any HReT(m, n) is a 3-regular bipartite graph. We prove that any HReT(m, n) - e is hamiltonian for any edge e is an element of E(HReT(m, n)). Moreover, any HReT(m, n) - F is hamiltonian for any F = {a, b} with a is an element of A and b is an element of B where A and B are the bipartition of HReT(m, n), if n greater than or equal to 6 or m = 2. (C) 2002 Elsevier Science B.V. All rights reserved.
Polycrystalline silicon thin-film transistor with self-aligned SiGe raised source/drain
(2002-12-16)
Peng, DZ
;
Chang, TC
;
Shih, PS
;
Zan, HW
;
Huang, TY
We have fabricated a polycrystalline silicon thin-film transistor with self-aligned SiGe raised source/drain (SiGe-RSD TFT). The SiGe-RSD regions were grown selectively by ultrahigh vacuum chemical vapor deposition at 550 degreesC. It was observed that, with SiH4 and GeH4 gas flow rates of 5 and 2 sccm, respectively, the poly-SiGe could be selectively grown up to 100 nm for source/drain regions. The resultant transistor structure features an ultrathin active channel region (20 nm) and a self-aligned thick source/drain region (120 nm), which is ideally suited for optimum performance. The significant improvements in electrical characteristics, such as higher turn-on current, lower leakage current, and higher drain breakdown voltage have been observed in the SiGe-RSD TFT, compared to the conventional TFT counterpart. These results indicate that TFTs with SiGe raised source/drain structure would be highly promising for ultrathin TFTs applications. (C) 2002 American Institute of Physics.
Synthesis and characterization of dendronized polyfluorenes
(2002-12-17)
Chou, CH
;
Shu, CF
;
應用化學系
;
Department of Applied Chemistry
A series of polyfluorenes containing pendant poly(benzyl ether) dendritic wedges of different generations was synthesized via the macromonomer approach, and then they were characterized by their structures and properties. The dendritic monomers were prepared by coupling benzyl bromide functionalized dendrons with 9,9-bis(4-hydroxyphenyl)-2,7-dibromofluorene and were subsequently copolymerized with a 9,9-dioctylfluorene diboronate derivative by the Suzuki coupling reaction to give the target alternating copolymers. Photophysical studies reveal that the photoluminescent properties of the dendronized polymers are greatly affected by the size of the dendritic side chains. Polymers appended with higher generation dendrons exhibit an enhanced photoluminescence efficiency and an improved luminescent stability. This is attributed to the shielding effect induced by the bulky dendrimer side chains, which prevent self-quenching and suppress the formation of aggregates/excimers.
下放的海外一首
(2002-12-18)
管管
Fiber-ring laser-based fiber grating sensor system using self-healing ring architecture
(2002-12-20)
Peng, PC
;
Tseng, HY
;
Chi, S
;
光電工程學系
;
Department of Photonics
This paper presents a self-healing fiber grating sensor system and demonstrates its effectiveness. The self-healing function is constructed by using a primary ring architecture incorporated with several ring sub-networks. To enhance the sensing signal when a breakpoint suddenly occurs in the network, we employ a fiber-ring laser-based sensor system. The network survivability of an 11-point FBG sensor is experimentally examined. The proposed fiber grating sensor system can increase the reliability of a sensing network. (C) 2002 Wiley Periodicals, Inc.
Effect of titanium substitution on film structure and ferroelectric properties of Sr-deficient Sr0.75Bi2.35Ta2O9 thin films
(2002-12-20)
Chen, SY
;
Lan, BC
;
Taso, CS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Ferroelectric films of bismuth-containing layered perovskite Sr0.75Bi2.35(Ta2-x,Ti-x)O-9 (x=0-0.8) have been prepared using a metal organic decomposition method. The effects of Ti substitution on the rnicrostructure evolution and ferroelectric properties of Sr0.75Bi2.35Ta2O9 films were investigated. A maximum remanent polarization of 2P(r)=30.7 muC/cm(2) was obtained for the Sr0.75Bi2.35Ta1.8Ti0.2O9 film as compared to Sr0.75Bi2.35Ta2O9 films (19.6 muC/cm(2)) annealed at 800 degreesC in air. The Ti substitution for Ta leads to charge compensation for the self-produced positive Bi-Sr(.), due to the occupation of Bi on Sr vacancies and is responsible for the increase in leakage resistance. The leakage current density as low as 2 X 10(-8) A/cm(2) can be obtained at an applied electric field of 100 kV/cm. Substitution of Ti for Ta shows a positive effect on the fatigue endurance of Sr-deficient Sr0.75Bi2.35Ta2O9 film. (C) 2002 Elsevier Science B.V. All rights reserved.
Low-temperature series expansions for square-lattice Ising model with first and second neighbour interactions
(2002-12-20)
Kao, YM
;
Chen, M
;
Lin, KY
;
物理研究所
;
Institute of Physics
We have calculated the low-temperature series expansions of the spontaneous magnetization and the zero-field susceptibility of the square-lattice ferromagnetic Ising model with first-neighbour interaction J(1) and second-neighbour interaction J(2) to the 30th and 26th order respectively by computer. Our results extend the previous calculations by Lee and Lin to six more orders. We use the Pade approximants to estimate the critical exponents and the critical temperature for different ratios of R = J(2)/J(1). The estimated critical temperature as a function of R agrees with the estimation by Oitmaa from high-temperature series expansions.
Thermal decomposition of iso-propanol: First-principles prediction of total and product-branching rate constants
(2002-12-22)
Bui, BH
;
Zhu, RS
;
Lin, MC
;
交大名義發表
;
National Chiao Tung University
The unimolecular decomposition of iso-C3H7OH has been studied with a modified GAUSSIAN-2 method. Among the six low-lying product channels identified, the H2O-elimination process (2) via a four-member-ring transition state is dominant below 760 Torr over the temperature range 500-2500 K. At higher pressures and over 1200 K, the cleavage of a C-C bond by reaction (1) producing CH3+CH3C(H)OH is predicted to be dominant. The predicted low- and high-pressure limit rate constants for these two major product channels can be given by k(1)(0)=6.3x10(42) T-16.21 exp(-47 400/T), k(2)(0)=7.2x10(44) T-14.70 exp(-35 700/T) cm(3) molecule(-1) s(-1), k(1)(infinity)=8.0x10(29) T-3.75 exp(-45 800/T), and k(2)(infinity)=2.0x10(6) T-2.12 exp(-30 700/T) s(-1), respectively. Predicted k(1) values compare reasonably with available experimental data; however, k(2) values are lower than the experimentally determined apparent rate constant for C3H6 formation, which may derive in large part from secondary radical reactions. Other minor decomposition products were predicted to have the barriers H-2+CH3C(O)CH3, E-3(0)=82.8 kcal/mol; H2O+(CH3CCH3)-C-1, E-4(0)=77.9 kcal/mol; CH4+CH3C(H)O, E-5(0)=84.3 kcal/mol; and CH4+(CH3COH)-C-1, E-6(0)=81.9 kcal/mol. The triplet-singlet energy gap for CH3CCH3 was predicted to be 5.2 kcal/mol, favoring the singlet state. (C) 2002 American Institute of Physics.