Browsing by Issue Date, starting with "2010-08-02"

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Quantitative determination of anisotropic magnetoelectric coupling in BiFeO3-CoFe2O4 nanostructures
(2010-08-02)
Oh, Yoon Seok
;
Crane, S.
;
Zheng, H.
;
Chu, Y. H.
;
Ramesh, R.
The transverse and longitudinal magnetoelectric susceptibilities (MES) were quantitatively determined for (001) heteroepitaxial BiFeO3-CoFe2O4 nanostructures. Both of these MES values were sharply enhanced at magnetic fields below 6 kOe and revealed asymmetric line shapes with respect to the dc magnetic field, demonstrating the strain-induced magnetoelectric effect. The maximum transverse MES, which reached as high as similar to 60 mV/cm Oe, was about five times larger than the longitudinal MES. This observation signifies that transverse magnetostriction of the CoFe2O4 nanopillars is enhanced more than the bulk value due to preferred magnetic domain alignment along the [001] direction coming from compressive, heteroepitaxial strain. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3475420]
Growth of 3C-SiC on Si(111) using the four-step non-cooling process
(2010-08-02)
Liu, Jui-Min
;
Chen, Wei-Yu
;
Hwang, J.
;
Huang, C-F.
;
Wang, Wei-Lin
A modified four-step method was applied to grow a 3C-SiC thin film of high quality on the off-axis 1.5 degrees Si(111) substrate in a mixed gas of C(3)H(8), SiH(4) and H(2) using low pressure chemical vapor deposition. The modified four-step method adds a diffusion step after the carburization step and removes the cooling from the traditional threestep method (clean, carburization, and growth). The X-ray intensity of the 3C-SiC(111) peak is enhanced from 5 x 10(4) counts/s (the modified three steps) to 1.1 x 10(5) counts/s (the modified four steps). The better crystal quality of 3C-SiC is confirmed by the X-ray rocking curves of 3C-SiC(111). 3C-SiC is epitaxially grown on Si( 111) supported by the selected area electron diffraction patterns taken at the 3C-SiC/Si(111) interface. Some (111) stacking faults and twins appear inside the 3C-SiC, which may result from the stress induced in the 3C-SiC thin film due to lattice mismatch. The diffusion step plays roles in enhancing the formation of Si-C bonds and in reducing the void density at the 3C-SiC/Si(111) interface. (C) 2010 Elsevier B.V. All rights reserved.
Global Analyses of Small Interfering RNAs Derived from Bamboo mosaic virus and Its Associated Satellite RNAs in Different Plants
(2010-08-02)
Lin, Kuan-Yu
;
Cheng, Chi-Ping
;
Chang, Bill Chia-Han
;
Wang, Wei-Chi
;
Huang, Ying-Wen
Background: Satellite RNAs (satRNAs), virus parasites, are exclusively associated with plant virus infection and have attracted much interest over the last 3 decades. Upon virus infection, virus-specific small interfering RNAs (vsiRNAs) are produced by dicer-like (DCL) endoribonucleases for anti-viral defense. The composition of vsiRNAs has been studied extensively; however, studies of satRNA-derived siRNAs (satsiRNAs) or siRNA profiles after satRNA co-infection are limited. Here, we report on the small RNA profiles associated with infection with Bamboo mosaic virus (BaMV) and its two satellite RNAs (satBaMVs) in Nicotiana benthamiana and Arabidopsis thaliana. Methodology/Principal Findings: Leaves of N. benthamiana or A. thaliana inoculated with water, BaMV alone or coinoculated with interfering or noninterfering satBaMV were collected for RNA extraction, then large-scale Solexa sequencing. Up to about 20% of total siRNAs as BaMV-specific siRNAs were accumulated in highly susceptible N. benthamiana leaves inoculated with BaMV alone or co-inoculated with noninterfering satBaMV; however, only about 0.1% of vsiRNAs were produced in plants co-infected with interfering satBaMV. The abundant region of siRNA distribution along BaMV and satBaMV genomes differed by host but not by co-infection with satBaMV. Most of the BaMV and satBaMV siRNAs were 21 or 22 nt, of both (+) and (-) polarities; however, a higher proportion of 22-nt BaMV and satBaMV siRNAs were generated in N. benthamiana than in A. thaliana. Furthermore, the proportion of non-viral 24-nt siRNAs was greatly increased in N. benthamiana after virus infection. Conclusions/Significance: The overall composition of vsiRNAs and satsiRNAs in the infected plants reflect the combined action of virus, satRNA and different DCLs in host plants. Our findings suggest that the structure and/or sequence demands of various DCLs in different hosts may result in differential susceptibility to the same virus. DCL2 producing 24-nt siRNAs under biotic stresses may play a vital role in the antiviral mechanism in N. benthamiana.
Nanoparticle-doped polyimide for controlling the pretilt angle of liquid crystals devices
(2010-08-02)
Hwang, Shug-June
;
Jeng, Shie-Chang
;
Hsieh, I-Ming
;
影像與生醫光電研究所
;
Institute of Imaging and Biomedical Photonics
The pretilt angles of liquid crystal molecules can be controlled by using conventional polyimide (PI) alignment material doped with different concentrations of Polyhedral Oligomeric Silsequioxanes (POSS) nanoparticles, which have been observed to spontaneously induce vertical alignment. The addition of POSS in the homogenous PI changes the surface energy of the alignment layer and generates a variable pretilt angle. Experimental results demonstrate that the pretilt angle. p is a function of the POSS concentration, and can be tuned continuously over the range of 0 degrees
Quantitative determination of anisotropic magnetoelectric coupling in BiFeO(3)-CoFe(2)O(4) nanostructures
(2010-08-02)
Oh, Yoon Seok
;
Crane, S.
;
Zheng, H.
;
Chu, Y. H.
;
Ramesh, R.
The transverse and longitudinal magnetoelectric susceptibilities (MES) were quantitatively determined for (001) heteroepitaxial BiFeO(3)-CoFe(2)O(4) nanostructures. Both of these MES values were sharply enhanced at magnetic fields below 6 kOe and revealed asymmetric line shapes with respect to the dc magnetic field, demonstrating the strain-induced magnetoelectric effect. The maximum transverse MES, which reached as high as similar to 60 mV/cm Oe, was about five times larger than the longitudinal MES. This observation signifies that transverse magnetostriction of the CoFe(2)O(4) nanopillars is enhanced more than the bulk value due to preferred magnetic domain alignment along the [001] direction coming from compressive, heteroepitaxial strain. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3475420]
Extracting the abstraction pyramid from complex networks
(2010-08-03)
Cheng, Chia-Ying
;
Hu, Yuh-Jyh
;
分子醫學與生物工程研究所
;
資訊工程學系
;
Institute of Molecular Medicine and Bioengineering
Background: At present, the organization of system modules is typically limited to either a multilevel hierarchy that describes the "vertical" relationships between modules at different levels (e. g., module A at level two is included in module B at level one), or a single-level graph that represents the "horizontal" relationships among modules (e. g., genetic interactions between module A and module B). Both types of organizations fail to provide a broader and deeper view of the complex systems that arise from an integration of vertical and horizontal relationships. Results: We propose a complex network analysis tool, Pyramabs, which was developed to integrate vertical and horizontal relationships and extract information at various granularities to create a pyramid from a complex system of interacting objects. The pyramid depicts the nested structure implied in a complex system, and shows the vertical relationships between abstract networks at different levels. In addition, at each level the abstract network of modules, which are connected by weighted links, represents the modules' horizontal relationships. We first tested Pyramabs on hierarchical random networks to verify its ability to find the module organization pre-embedded in the networks. We later tested it on a protein-protein interaction (PPI) network and a metabolic network. According to Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), the vertical relationships identified from the PPI and metabolic pathways correctly characterized the inclusion (i.e., part-of) relationship, and the horizontal relationships provided a good indication of the functional closeness between modules. Our experiments with Pyramabs demonstrated its ability to perform knowledge mining in complex systems. Conclusions: Networks are a flexible and convenient method of representing interactions in a complex system, and an increasing amount of information in real-world situations is described by complex networks. We considered the analysis of a complex network as an iterative process for extracting meaningful information at multiple granularities from a system of interacting objects. The quality of the interpretation of the networks depends on the completeness and expressiveness of the extracted knowledge representations. Pyramabs was designed to interpret a complex network through a disclosure of a pyramid of abstractions. The abstraction pyramid is a new knowledge representation that combines vertical and horizontal viewpoints at different degrees of abstraction. Interpretations in this form are more accurate and more meaningful than multilevel dendrograms or single-level graphs. Pyramabs can be accessed at http://140.113.166.165/pyramabs.php/.
3-10 GHz ultra-wideband low-noise amplifier with new matching technique
(2010-08-05)
Liang, C-P.
;
Huang, C-W.
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Lin, Y-K.
;
Chung, S-J.
;
電信工程研究所
A low-power and low-noise amplifier with a new input-matching technique using 0.18 mu m CMOS technology for ultra-wideband applications is presented. A proposed broadband input match can be acquired easily by selecting an appropriate width of the transistor, which will effectively avoid the usage of the low-Q on-chip inductors in the input network. Moreover, demonstrated is the feasibility of the inter-stage resonator to accomplish bandwidth enhancement without additional power consumption. The IC prototype achieves good performances such as a power gain of 16.2 dB, a better than 10 dB input return loss, and 2.3 dB minimum noise figure while consuming a DC core power of only 6.8 mW.
交大e-News第076期
(2010-08-05)
Secretariat
;
國立交通大學秘書室
Preparation and Characterizations of Tantalum Pentoxide (Ta2O5) Nanoparticles and UV-Curable Ta2O5-Acrylic Nanocomposites
(2010-08-05)
Huang, Heh-Chang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
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Department of Materials Science and Engineering
Tantalum pentoxide (Ta2O5) nanoparticles with the sizes in the range of 20-50 nm were prepared via a chemical route in which the oleic acid (OLEA) was adopted as the surfactant for the synthesis process. X-ray diffraction (XRD) revealed the as-synthesized Ta2O5 transforms from amorphous to hexagonal and ortho-rhombic structures at the temperatures of 700 degrees C and 750 degrees C, respectively, illustrating the suppression of recrystallization temperature of Ta2O5 due to the particle size reduction. UV-curable nanocomposites containing the Ta2O5 nanoparticles and acrylic matrix were also prepared. Thermogravimetry analysis (TGA) found an about 10-20 degrees C improvement on the 5% weight-loss thermal decomposition temperatures (T(d)s). Dielectric measurement showed that the dielectric constant of nanocomposite increases with the increase in the filler loading without severe deterioration of dielectric loss. The increment of dielectric constants was ascribed to the addition of high-dielectric inorganic fillers as well as the presence of interfacial polarization at the organic/inorganic interfaces. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1252-1259, 2010
MANUFACTURE METHOD OF MULTILAYER STRUCTURE HAVING NON-POLAR A-PLANE III-NITRIDE LAYER
(2010-08-05)
Lee, Wei-I
;
Chen, Jenn-Fang
;
Chiang, Chen-Hao
A manufacture method of a multilayer structure having a non-polar a-plane {11-22} III-nitride layer includes forming a nucleation layer on a r-plane substrate, wherein the nucleation layer is composed of multiple nitride layers; and forming a non-polar a-plane {11-20} III-nitride layer on the nucleation layer. The nucleation layer features reduced stress, reduced phase difference of lattice, blocked elongation of dislocation, and reduced density of dislocation. Thus, the non-polar a-plane {11-20} III-nitride layer with flat surface can be formed.
Preparation and Characterizations of Tantalum Pentoxide (Ta(2)O(5)) Nanoparticles and UV-Curable Ta(2)O(5)-Acrylic Nanocomposites
(2010-08-05)
Huang, Heh-Chang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Tantalum pentoxide (Ta(2)O(5)) nanoparticles with the sizes in the range of 20-50 nm were prepared via a chemical route in which the oleic acid (OLEA) was adopted as the surfactant for the synthesis process. X-ray diffraction (XRD) revealed the as-synthesized Ta(2)O(5) transforms from amorphous to hexagonal and ortho-rhombic structures at the temperatures of 700 degrees C and 750 degrees C, respectively, illustrating the suppression of recrystallization temperature of Ta(2)O(5) due to the particle size reduction. UV-curable nanocomposites containing the Ta(2)O(5) nanoparticles and acrylic matrix were also prepared. Thermogravimetry analysis (TGA) found an about 10-20 degrees C improvement on the 5% weight-loss thermal decomposition temperatures (T(d)s). Dielectric measurement showed that the dielectric constant of nanocomposite increases with the increase in the filler loading without severe deterioration of dielectric loss. The increment of dielectric constants was ascribed to the addition of high-dielectric inorganic fillers as well as the presence of interfacial polarization at the organic/inorganic interfaces. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1252-1259, 2010
Hydrogen Bond-Mediated Self-Assembly of Polyhedral Oligomeric Silsesquioxane-Based Supramolecules
(2010-08-05)
Shih, Ruey-Sheng
;
Lu, Chu-Hua
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
應用化學系
In this study, a functionalized pentaerythritol star polyester compound [tetrakis(nicotinoxymethyl)methane, TNMM] and an octakis[dimethyl(4-hydroxyphenethyl)siloxy]silsesquioxane (OP-POSS) were synthesized and used as tetrahedral and cubic building blocks, respectively, for three-dimensional, hydrogen-bond-mediated, polyhedral oligomeric silsesquioxane- (POSS-) based supramolecular network structures. With noncovalent chain extension of hydrogen bonds between its pyridine and phenol groups, the PUSS-based supramolecular networks exhibited thermally reversible properties. Compared with the glass transition temperature of OP-POSS (ca. 20 degrees C) and the melting temperature of TNMM (ca. 70 degrees C), the hydrogen-bond-mediated miscible blend of 40 wt % TNMM in OP-POSS exhibited a single and higher glass transition temperature (37 degrees C). Because of its strong intermolecular hydrogen bonding, the dewetting pattern of the blend of 40 wt % TNMM in OP-POSS formed ringlike structures rather than the droplets formed by pure OP-POSS. A transparent, brittle, and glassy solid at room temperature, the blend of 40 wt % TNMM in OP-POSS is an explicit and successful example of a PUSS-based hydrogen-bonded supramolecular network.
Covalent linkage of nanodiamond-paclitaxel for drug delivery and cancer therapy
(2010-08-06)
Liu, Kuang-Kai
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Zheng, Wen-Wei
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Wang, Chi-Ching
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Chiu, Yu-Chung
;
Cheng, Chia-Liang
A nanoparticle-conjugated cancer drug provides a novel strategy for cancer therapy. In this study, we manipulated nanodiamond (ND), a carbon nanomaterial, to covalently link paclitaxel for cancer drug delivery and therapy. Paclitaxel was bound to the surface of 3-5 nm sized ND through a succession of chemical modifications. The ND-paclitaxel conjugation was measured by atomic force microscope and nuclear magnetic resonance spectroscopy, and confirmed with infrared spectroscopy by the detection of deuterated paclitaxel. Treatment with 0.1-50 mu g ml(-1) ND-paclitaxel for 48 h significantly reduced the cell viability in the A549 human lung carcinoma cells. ND-paclitaxel induced both mitotic arrest and apoptosis in A549 cells. However, ND alone or denatured ND-paclitaxel (after treatment with strong alkaline solution, 1 M NaOH) did not induce the damage effects on A549 cells. ND-paclitaxel was taken into lung cancer cells in a concentration-dependent manner using flow cytometer analysis. The ND-paclitaxel particles were located in the microtubules and cytoplasm of A549 cells observed by confocal microscopy. Furthermore, ND-paclitaxel markedly blocked the tumor growth and formation of lung cancer cells in xenograft SCID mice. Together, we provide a functional covalent conjugation of ND-paclitaxel, which can be delivered into lung carcinoma cells and preserves the anticancer activities on the induction of mitotic blockage, apoptosis and anti-tumorigenesis.
Carrier dynamics of Mg-doped indium nitride
(2010-08-09)
Ahn, H.
;
Yu, K. -J.
;
Hong, Y. -L.
;
Gwo, S.
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光電工程學系
Recently, we have reported a significant enhancement (>500 times in intensity) in terahertz emission from Mg-doped indium nitride (InN:Mg) films compared to undoped InN. It was found that the intensity of terahertz radiation strongly depends on the background electron density. In this letter, we present the results on ultrafast time-resolved reflectivity measurement employed to investigate the carrier dynamics of InN:Mg. We find that the decay time constant of InN:Mg depends on background electron density in the same way as terahertz radiation does. The spatial redistribution of carriers in diffusion and drift is found to be responsible for the recombination behavior as well as terahertz radiation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479523]
A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens
(2010-08-09)
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
We demonstrated a fast response and large tunable focusing imaging system consisting of a lens module and a liquid crystal (LC) lens based on the switching of two modes of a LC lens: the negative LC lens and positive LC lens. By discarding the conventional operation of a positive LC lens only in the imaging system, large tunable focusing range can be achieve from 300 to 10 cm owning to the phase change between the positive and the negative LC lens; meanwhile, the response time is fast (similar to 433 ms). The potential applications are autofocused cell phones, and cameras. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479051]
Synthesis and Characterization of Pyrido[3,4-b]pyrazine-Based Low-Bandgap Copolymers for Bulk Heterojunction Solar Cells
(2010-08-10)
Yuan, Mao-Chuan
;
Chiu, Mao-Yuan
;
Chiang, Chien-Ming
;
Wei, Kung-Hwa
;
材料科學與工程學系
We have used Stille polycondensation to prepare a series of low-bandgap copolymers, P1-P4, by conjugating the electron-accepting pyrido[3,4-b]pyrazine (PP) moieties with the electron-rich benzo[1,2-b:3,4-b']dithiophene (BDT) or cyclopentadithiophene (CPDT) units. P1 and P3 are based on PP and BDT units while P2 and P4 are based on PP and CPDT units. All of these polymers exhibited excellent thermal stability and sufficient energy offsets for efficient charge transfer and dissociation, as determined through thermogravimetric analyses and cyclic voltammetry, respectively. The bandgaps of the polymers could be tuned in the range 1.46-1.60 eV by using the two different donors, which have different electron-donating abilities. The three-component copolymers, P3 and P4, incorporating the thiophene and bithiophene segments, respectively, absorbed broadly, covering the solar spectrum from 350 to 800 nm. The morphologies of the blends of P3 and P4 with [6,6]-phenyl-C(70)-butyric acid methyl ester (PC(70)BM) were more homogeneous than those of P1 and P2; in addition, devices incorporating the P3 and P4 blends exhibited superior performance. The best device performance resulted from an active layer containing the P4:PC(70)BM blend; the short-circuit current was 10.85 mA cm(-2) and the power conversion efficiency was 3.15%.
Beginnings of modern mathematics in India
(2010-08-10)
Dauben, Joseph W.
;
Parikh, Rohit
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人文與社會科學研究中心
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Center for Humanities and Social Sciences Research
Toward Optimization of Oligothiophene Antennas: New Ruthenium Sensitizers with Excellent Performance for Dye-Sensitized Solar Cells
(2010-08-10)
Yin, Jen-Fu
;
Chen, Jian-Ging
;
Lu, Zong-Zhan
;
Ho, Kuo-Chuan
;
Lin, Hong-Cheu
This paper reports on the design and synthesis of three new ruthenium sensitizers, as well as the optimization of their linear or dendritic light-harvesting oligothiophene antennas to achieve superior device performance. The three new ruthenium sensitizers, [Ru(dcbpy)(obtip)(NCS)(2)] (JF-5, dcbpy = 4,4'-dicarboxylic obtip = 2-(5-octyl-(2,2'-bithiophen)-5'-yl)-1H-imidazo[4,51][1,10]-phenanthroline), [Ru(dcbpy)(ottip)(NCS)(2)] (JF-6, ottip = 2-(5-octyl-2,2',5',2 ''-terthiophen)-5 ''-yl)-1H-imidazo[4,5-f][1,10]-phenanthroline), and [Ru(dcbpy)(dottip)(NCS)(2)] (JF-7, dottip = di-(5-octylthiophen-2-ypthiophen-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), were synthesized in a typical one-pot reaction. The ruthenium sensitizer JF-5 incorporating a linear and planar 2,2'-bithiophene antenna showed the best DSCs performance (9.5%; compared to N3, 8.8%). The difference in the performance of these sensitizers demonstrates that elongating the linear and planar light-harvesting antenna result in an enhancement in MLCT intensity, but a reduction in the quantity of dye-loading. This finding not only permitted the power-conversion efficiency in ruthenium sensitizers containing oligothiophene antennas to be optimized, but also points to a promising direction for molecule engineering in DSCs.
Vertical organic transistor
(2010-08-10)
Meng
;
Hsin-Fei
;
Horng
;
Sheng-Fu
;
Chao
A vertical organic transistor and a method for fabricating the same are provided, wherein an emitter, a grid with openings and a collector are sequentially arranged above a substrate. Two organic semiconductor layers are interposed respectively between the emitter and the grid with openings and between the grid with openings and the collector. The channel length is simply decided by the thickness of the organic semiconductor layers. The collector current depends on the space-charge-limited current contributed by the potential difference between the emitter and the openings of the grid. And the grid voltage can thus effectively control the collector current. Further, the fabrication process of the vertical organic transistor of the present invention is simple and exempt from using the photolithographic process.
應用於低密度奇偶校驗解碼器之迴旋比較方法
(2010-08-11)
洪瑞徽
;
洪瑞鴻
;
陳紹基
本發明提供一種應用於低密度奇偶校驗解碼器之迴旋比較方法，其係在應用奇偶校驗檢查碼(Low density parity check code,LDPC)之解碼器中使用比較器，此比較器利用迴旋比較演算法，從輸入之k個元素中依序去除第n個元素，n＝1...k－1，組成k個第一串列後，再將k個元素依次兩兩組合在一起，反覆組合k×log2(k－1)次直到組成k個結束串列，此結束串列與第一串列中皆包含k－1個元素，比較兩者是否相同，若相同則結束，若不相同則重新組合出結束串列。利用此種迴旋比較之方法只需比較k×log2(k－1)次即可取得結束串列，減少基本比較運算的次數，且任何數目之輸入皆適用，亦程式化且接近最佳解。