Browsing by Issue Date, starting with "2001-03-07"

Now showing 1 - 20 of 76643

The role of mammalian Ste20-like kinase MST3 in apoptosis
(2001-03-07)
Yuan, CJ
;
Hsu, CY
;
Huang, CYF
;
交大名義發表
;
National Chiao Tung University
Syntheses and properties of PI/clay hybrids
(2001-03-07)
Gu, AJ
;
Kuo, SW
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A new organomontmorillonite (CM) for PI hybrids has been developed by ion-exchange reaction of cetyl pyridum chloride with Na+ montmorillonite (MMT). Polyimide/clay hybrids have been synthesized by employing two methods. Method I is by first blending a dimethylacetamide (DMAC) solution of 4,4'-oxydianiline diamine (ODA) with a DMAC dispersion of CM before adding pyromellitic dianhydride (PMDA). Method II is by blending a DMAC solution of poly(amic acid) with a DMAC dispersion of CM. Tensile, thermal, dielectric, and water-absorption properties of hybrids prepared by these two methods have been studied in detail. Results show that these properties depend on the clay type (organophilic or not), clay concentration, and the method to synthesis hybrids. The CM concentration of 3 wt% in the hybrid by Method II results in optimum properties in tensile strength, modulus, elongation, coefficient of thermal expansion (CTE), and water absorption. (C) 2001 John Wiley & Sons, Inc.
Role of haptoglobin in formation of atherosclerosis
(2001-03-07)
Mao, SJT
;
Yang, SJ
;
Wu, CH
;
交大名義發表
;
National Chiao Tung University
Nucleotides as cofactor, inhibitor, and antioxidation and stabilization reagent of phenol sulfotransferase
(2001-03-07)
Lin, ES
;
Li, TS
;
Yang, YS
;
交大名義發表
;
National Chiao Tung University
Functional analysis of alanine-scanning and site-directed mutations in the oxidosqualene-lanosterol cyclase gene of Saccharomyces cerevisiae
(2001-03-07)
Wu, TK
;
Wang, HJ
;
Chiu, FH
;
交大名義發表
;
National Chiao Tung University
Effect of pH, metal and temperature on the substrate specificity of a thermophilic imidase from pig liver
(2001-03-07)
Yang, YS
;
Lin, SW
;
Huang, CY
;
交大名義發表
;
National Chiao Tung University
Effects of thermal annealing on Ni/Ta/n-GaN Schottky diodes
(2001-03-15)
Chen, GL
;
Chang, FC
;
Chung, WC
;
Huang, BR
;
Chen, WH
The thermal effects of Ni/Ta/n-GaN Schottky diodes have been investigated for the first time using current-voltage, X-ray photoemission spectroscopy and Auger electron spectroscopy (AES) methods. Their barrier height is found to increase monotonously with increasing annealing temperature up to 800 degreesC. Preliminary results indicate that when a Th intermediate layer is added into the Ni/GaN diodes, it can prevent the metal-semiconductor interdiffusion and Ni accumulation adjacent to GaN substrate to a large extent so that a more thermally stable device can be obtained.
A new locality-based IP multicasting scheme for mobile hosts
(2001-03-15)
Tseng, CC
;
Chi, KH
;
Huang, TL
;
資訊工程學系
;
Department of Computer Science
Internet protocol multicasting is a mechanism widely used in the Internet to disseminate information. Multicast delivery paths may need to be frequently restructured along with host migrations, at the expense of nontrivial overhead or multicast latency. This paper presents a scheme with short multicast latency, while retaining acceptable overhead in adapting the delivery paths to mobile host locations. We exploit the locality in host movements and keep active the networks that mobile hosts have most recently visited. As long as hosts migrate within these active networks, multicast delivery paths can remain unchanged upon host movements. Performance results show that, compared with the best known proposal, our scheme is promising. (C) 2001 Elsevier Science B.V. All rights reserved.
Heterogeneous and homogeneous catalytic oxidation by supported gamma-FeOOH in a fluidized bed reactor: Kinetic approach
(2001-03-15)
Chou, SS
;
Huang, CP
;
Huang, YH
;
環境工程研究所
;
Institute of Environmental Engineering
Oxidation of benzoic,acid (BA) by H2O2 was performed with a never supported gamma -FeOOH catalyst in a circulating fluidized-bed reactor (CFBR).; This study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in this CFBR. Also studied herein was how pH, H2O2 concentration, and BA concentration affect the oxidation of BA. Experimental results indicate that the decomposition rate of H2O2 was proportional to its concentration and that the oxidation rate of BA depended on both H2O2 and BA concentrations. The change in the rate constant of heterogeneous catalysis by pH was described in terms of ionization fractions of surface hydroxyl group. From the mathematical deduction, we-can infer that the reaction rate associated with equivalent toF(III)OH(2)(+) is markedly higher than that with equivalent toF(III)OH. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of BA at pH 4.4-7.0, the homogeneous catalysis is of increasing importance below pH 4.4 because of the reductive dissolution of gamma -FeOOH.
Comparison of ultrathin CoTiO3 and NiTiO3 high-k gate dielectrics
(2001-03-15)
Pan, TM
;
Lei, TF
;
Chao, TS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
High-k cobalt-titanium oxide (CoTiO3) and nickel-titanium oxide (NiTiO3) were formed by directly oxidizing sputtered Co/Ti and Ni/Ti film. Al/CoTiO3/Si3N4/Si and Al/NiTiO3/Si3N4/Si capacitor structures were fabricated and measured. The effective dielectric constant (k value congruent to 45) with buffer layer for CoTiO3 is larger than that of NiTiO3. In addition, CoTiO3 depicts excellent electrical properties at the same time. This metal oxide thus appears to be a very promising high-k gate dielectric for future ultralarge scale integrated devices. (C) 2001 American Institute of Physics.
Field emission properties of two-layer structured SiCN films
(2001-03-15)
Tarntair, FG
;
Wu, JJ
;
Chen, KH
;
Wen, CY
;
Chen, LC
The electron emission characteristics of two-layer structured silicon carbon nitride (SiCN) films, which were composed of amorphous and nanocrystalline phases, were studied. Rutherford backscattering spectroscopy (RBS) was used to determine the composition of the SiCN film. The ratio (Si;C)/N of the SiCN film was kept at approximately 0.75, which is identical to that of Si3N4 him. High resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to investigate the bonding structures of the SiCN films. In comparison with silicon nitride films, the turn-on Voltage (for an emission current of 0.01 mA/cm(2)) of the SiCN films was rower and the emission current densities of the SiCN significantly enhanced. The promising emission properties of the SiCN film could be due to the unique two-layer structure wherein nanocrystalline SiCN was grown on top of the amorphous interlayer with sp(2) CN bond in the SiCN film. (C) 2001 Elsevier Science B.V. All rights reserved.
Temperature dependence of the penetration depth and effective dielectric constant measured by YBa2Cu3O7-delta microstrip ring resonators
(2001-03-15)
Zeng, HK
;
Juang, JY
;
Lin, JY
;
Wu, KH
;
Uen, TM
YBa2Cu3O7-delta(YBCO) superconducting ring resonators with a YBCO ground plane were successfully fabricated using double-side YBCO films deposited on LaAlO3 (LAO) substrates. The temperature dependent London penetration depth, Delta lambda = lambda (T) - lambda (5 K), was systematically studied by varying the oxygen content of the same resonator structure. For fully oxygenated case (delta = 0.05), the resonator exhibits a quality factor Q > 10(4) at 16 K, and Delta lambda (T) displays a linear behavior over a wide range of temperatures. With increasing delta (e.g. delta = 0.2, 0.4), although Delta lambda is still linear in temperature, the slope changes with increasing oxygen deficiency. The results suggest that, in the underdoped regime, the inelastic scattering of charged carriers may become increasingly prominent. From the effective dielectric constant obtained from the ring resonator the dielectric constant of the LAO substrate was estimated to be epsilon (r) congruent to 25.5 at 5 K and a frequency of about 3.6 GHz. (C) 2001 Elsevier Science B.V. All rights reserved.
ODCHP: a new effective mechanism to maximize parallelism of nested loops with non-uniform dependences
(2001-03-15)
Pean, DL
;
Chen, C
;
資訊工程學系
;
Department of Computer Science
There are many methods for nested loop partitioning. However, most of them perform poorly when partitioning loops with nonuniform dependences. This paper proposes a generalized and optimized loop partitioning mechanism to exploit parallelism from nested loops with non-uniform dependences. Our approach, based on dependence convex theory, will divide the loop into variable size partitions. Furthermore, the proposed algorithm partitions a nested loop by using the copy-renaming and the optimized partitioning techniques to minimize the number of parallel regions of the iteration space. Consequently, it outperforms the previous partitioning mechanisms of nested loops with non-uniform dependences. Many optimization techniques are used to reduce the complexity of the algorithm. Compared with other popular techniques, our scheme shows a dramatic improvement in the preliminary performance results. (C) 2001 Elsevier Science Inc. All rights reserved.
Effect of substrate concentration on bioleaching of metal-contaminated sediment
(2001-03-19)
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
The remediation of metal-contaminated sediment wits studied using the bioleaching process with a mixed culture of sulfur-oxidizing bacteria. The effects of substrate concentration (elemental sulfur) on sediment acidification, sulfur oxidation and metal solubilization from contaminated sediment during the bioleaching process were investigated with free-cell suspensions. Sulfur concentration greater than 0.5% (w/v) was found to be inhibitory to bacterial activity and metal solubilization from sediment. The sulfate production was well described by a substrate inhibition expression and Haldane's equation. In addition, an empirical equation related to sulfur concentration was also used to describe the metal solubilization in the bioleaching process. (C) 2001 Elsevier Science B.V. All rights reserved.
Reactive compatibilization of PP/PBT blends by a mixture of PP-g-MA and epoxy resin
(2001-03-21)
Shieh, YT
;
Liao, TN
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
In this study, dual compatibilizers composed of the commercially available maleic anhydride-grafted polypropylene (PP-MA) and a multifunctional epoxy resin were demonstrated to effectively compatibilize the immiscible and incompatible blends of PP and poly(butylene terephthalate) (PBT). The PP-MA with a low MA content is totally miscible with PP to make the PP phase quasi-functionalized, so that the multifunctional epoxy has the chance to react with PBT and PP-MA simultaneously to form PP-MA-co-epoxy-co-PBT copolymers at the interface. These desired copolymers are able to anchor along the interface and serve as efficient compatibilizers. The compatibilized blends, depending on the quantity of dual compatibilizers employed, exhibit higher viscosity, finer phase domain, and improved mechanical properties. Epoxy does not show compatibilization effects for the PP/PBT blends without the presence of PP-MA in the blends. (C) 2001 John Wiley & Sons, Inc.
Disproving a conjecture on planar visibility graphs
(2001-03-28)
Chen, CY
;
Wu, KP
;
應用數學系
;
Department of Applied Mathematics
Two vertices A and B of a simple polygon P are (mutually) visible if AB does not intersect the exterior of P. A graph G is a visibility graph if there exists a simple polygon P such that each vertex of G corresponds to a vertex of P and two vertices of G are joined by an edge if and only if their corresponding vertices in P are visible, No characterization of visibility graphs is available. Abello, Lin and Pisupati conjectured that every hamiltonian maximal planar graph with a 3-clique ordering is a visibility graph. In this paper, we disprove this conjecture. (C) 2001 Elsevier Science B.V. All rights reserved.
Structural identification from ambient vibration measurement using the multivariate AR model
(2001-03-29)
Huang, CS
;
土木工程學系
;
Department of Civil Engineering
A procedure for identifying the dynamic characteristics of a structural system using the multivariate AR (ARV) model is presented in the paper. A least-squares approach to determine the coefficient matrices of the ARV model is proposed, which is a modification of the traditional one. The modification is based on the equivalence between the correlation function matrix for the responses of a linear system subjected to white-noise input and the deterministic free vibration responses of the system. Then, the dynamic characteristics of the system are evaluated directly from the coefficient matrices of the ARV model by adopting the concept behind Ibrahim's system identification technique. The superiority of the proposed procedure over the traditional one is demonstrated through numerical studies on a six-story shear building. Finally, the present identification procedure is applied to identify the dynamic characteristics of a three-span highway bridge from its ambient vibration responses subjected to traffic flow. The validity of the present procedure is confirmed by the excellent agreement between the identified results obtained in the present study and those obtained from an impulse test. (C) 2001 Academic Press.
Origin of size effect on superconductivity in (R-0.8 Pr-0.2)Ba2Cu3O7 studied by soft X-ray absorption spectroscopy
(2001-03-30)
Chen, JM
;
Nachimuthu, P
;
Lin, JY
;
Hong, IP
;
Chang, CF
O K-edge X-ray absorption near-edge structure (XANES) spectroscopy of (R-0.8 Pr-0.2)Ba2Cu3O7 (R = Y, Tm, Dy, Gd, Eu and Sm) has been performed to investigate the dependence of hole distribution on ionic size of the R3+ ions. Near the O Is absorption edge, pre-peaks at similar to 527.8 and similar to 528.5 eV are assigned to transitions into O 2p hole states located in the CuO3 ribbons and CuO2 planes, respectively. As deduced from O K-edge X-ray absorption spectra, the hole concentrations in the CuO2 planes decrease monotonically with increasing ionic size of the rare-earth elements. The present XANES results clearly demonstrate that the suppression of superconductivity in (R1-x Pr-x)Ba2Cu3O7 With ionic radius of the R3+ ions results predominantly from the hole-depletion effect. (C) 2001 Elsevier Science B.V. All rights reserved.
Exact Green function of Aharonov-Bhm billiard system
(2001-03-30)
Chuu, DS
;
Lin, DH
;
電子物理學系
;
Department of Electrophysics
The exact Green functions of the relativistic spherical quantum Aharonov-Bohm billiard systems in two- and three-dimensional spaces are given by the path integral approach. The transcendental equations for determining the energy spectra are discussed.
Discrepancies between different response parameters in batch and continuous algal toxicity tests
(2001-03-30)
Chao, MR
;
Chen, CY
;
環境工程研究所
;
Institute of Environmental Engineering
The test sensitivities and reproducibilities based on different response endpoints (cell density and total cell volume) were compared using both bath and continuous algal toxicity tests. Parameters related to algal cell density are found to be more sensitive and reproducible than total cell volume which bears a direct correlation to algal biomass or dry weight. The magnitude of differences in the median effective concentration values could be upto six folds. The main cause for the above discrepancies is because the cell density and total cell volume are two response endpoints reflecting the degree of inhibition on the binary fission mechanism and overall photosynthesis, respectively. At low toxicant concentrations, the inhibitory effect is primarily on the cell division rather than on the cellular photosynthesis. Thus, more severe toxic effects are expected to be observed based on the cell density than the total cell volume. The results of this study clearly demonstrate that sensitivity and reproducibility can be significantly improved if response parameters are calculated based on the cell density. Traditionally, cell density data are often converted into biomass before assessing the effects of toxicants. This procedure may not be necessary and may reduce the test sensitivity. (C) 2001 Elsevier Science B.V. All rights reserved.