Browsing by Issue Date, starting with "2011-06-06"

Now showing 1 - 20 of 41116

Observation of spontaneous polarization misalignments in periodically poled crystals using second-harmonic generation microscopy
(2011-06-06)
Tzeng, Yu-Yi
;
Zhuo, Zong-Yan
;
Lee, Ming-Yin
;
Liao, Chien-Sheng
;
Wu, Pei-Chun
Periodically poled crystal (PPC) is a key component for nonlinear optical applications. Its poling quality relies largely on successful domain inversion and the alignment of spontaneous polarization (SP) vectors in each domain. Here we report the unexpected observation of bulk second harmonic generation (SHG) in PPC when excitation propagating along its optical axis. Based on its tensorial nature, SHG is highly sensitive to the orientation of SP, and therefore the misalignment of SP in each domain of PPC can be revealed noninvasively by SHG microscopy. This nonlinear imaging modality provides optical sectioning capability with 3D sub-micrometer resolution, so it will be useful for in situ investigation of poling quality in PPC. (C) 2011 Optical Society of America
Regioselective, Unconventional Pictet-Spengler Cyclization Strategy Toward the Synthesis of Benzimidazole-Linked Imidazoquinoxalines on a Soluble Polymer Support
(2011-06-06)
Chen, Chih-Hau
;
Kuo, Jaren
;
Yellol, Gorakh S.
;
Sun, Chung-Ming
;
應用化學系
A novel strategy for an unconventional Pictet-Spengler reaction has been developed for the regioselective cyclization of the imidazole ring system at the C2 position. The developed strategy was utilized to develop a diversity-oriented parallel synthesis for bis(heterocyclic) skeletal novel analogs of benzimidazole-linked imidazoquinoxalines on a soluble polymer support under microwave conditions. Condensation of polymer-immobilized o-phenylenediamines with 4-fluoro-3-nitrobenzoic acid followed by nucleophilic aromatic substitution with an imidazole motif affords bis(heterocyclic) skeletal precursors for the Pictet-Spengler reaction. The unconventional Pictet-Spengler cyclization with various aldehydes was achieved regioselectively at the C2 position of the imidazole ring to furnish rare imidazole-fused quinoxaline skeletons. During the Pictet-Spengler cyclization, aldehydes bearing electron-donating groups afford 4,5-dihydro-imidazoquinoxalines, which then auto-aromatize into benzimidazole-linked imidazo[1,2-a]quinoxalines. However, interestingly, aldehydes bearing electron-withdrawing groups directly provide aromatized imidazo[1,2-a]quinoxalines, which unexpectedly afford novel benzimidazole-linked 4-methoxy-4,5-dihydro-imidazo[1,2-a] quinoxalines after polymer cleavage.
Long-reach radio-over-fiber signal distribution using single-sideband signal generated by a silicon-modulator
(2011-06-06)
Chow, C. W.
;
Yeh, C. H.
;
Lo, Stanley M. G.
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Li, C.
;
Tsang, H. K.
The integration of passive optical network (PON) and radio-overfiber (ROF) networks could provide broadband services for both fixed and mobile users in a single and low-cost platform. Combining the long-reach (LR)-PON (>100 km) and the LR-ROF can further reduce the cost by simplifying the network architecture, sharing the same optical components and extending the coverage of ROF network. However, the transmission and distribution of ROF signal in LR network is very challenging due to the chromatic dispersion generated periodic power fading and code time-shifting effects in the optical fiber. In this work, we propose and experimentally demonstrate a LR-ROF signal distribution using single-sideband (SSB)-ROF signal generated by a silicon ring-modulator. The silicon modulator is compact and has low power consumption. Besides, one unique feature of the silicon ring-modulator is that it only modulates the signal wavelength at the resonant null. This makes it very suitable for the generation of the SSB-ROF signal. Numerical comparison of the SSB-ROF with the double-sideband (DSB)-ROF and optical carrier suppress (OCS)-ROF signals; as well as the fabrication of the silicon ring-modulator will be discussed. (C)2011 Optical Society of America
Synthesis for catalysis of bifunctional perovskite compound
(2011-06-07)
Wu Pu-Wei
;
Chang Yun-Min
This invention discloses the synthesis of a bifunctional La0.6Ca0.4Co1-xIrxO3 (x=0˜1) perovskite compound with a superb bifunctional catalytic ability for the oxygen reduction and generation in alkaline electrolytes. Synthetic routes demonstrated include solid state reaction, amorphous citrate precursor, and mechanical alloying. The interested compound demonstrates notable enhancements over commercially available La0.6Ca0.4CoO3.
Computational Investigation of O-2 Reduction and Diffusion on 25% Sr-Doped LaMnO3 Cathodes in Solid Oxide Fuel Cells
(2011-06-07)
Chen, Hsin-Tsung
;
Raghunath, P.
;
Lin, M. C.
;
應用化學系
;
應用化學系分子科學碩博班
The oxygen reduction reaction (ORR) and diffusion mechanisms on 25% Sr-doped LaMnO3 (LSM) cathode materials as well as their kinetic behavior have been studied by using spin-polarized density functional theory (DFT) calculations. Bader charge and frequency analyses were carried out to identify the oxidation state of adsorbed oxygen species. DFT and molecular dynamics (MD) results show that the fast O-2 adsorption/reduction process via superoxide and peroxide intermediates is energetically favorable on the Mn site rather than on the Sr site. Furthermore, the higher adsorption energies on the Mn site of the (110) surface compared to those on the (100) surface imply that the former is more efficient for O-2 reduction. Significantly, we predict that oxygen vacancies enhance O-2 reduction kinetics and that the O-ion migration through the bulk is dominant over that on cathode.
Computational Investigation of O(2) Reduction and Diffusion on 25% Sr-Doped LaMnO(3) Cathodes in Solid Oxide Fuel Cells
(2011-06-07)
Chen, Hsin-Tsung
;
Raghunath, P.
;
Lin, M. C.
;
應用化學系
;
應用化學系分子科學碩博班
The oxygen reduction reaction (ORR) and diffusion mechanisms on 25% Sr-doped LaMnO(3) (LSM) cathode materials as well as their kinetic behavior have been studied by using spin-polarized density functional theory (DFT) calculations. Bader charge and frequency analyses were carried out to identify the oxidation state of adsorbed oxygen species. DFT and molecular dynamics (MD) results show that the fast O(2) adsorption/reduction process via superoxide and peroxide intermediates is energetically favorable on the Mn site rather than on the Sr site. Furthermore, the higher adsorption energies on the Mn site of the (110) surface compared to those on the (100) surface imply that the former is more efficient for O(2) reduction. Significantly, we predict that oxygen vacancies enhance O(2) reduction kinetics and that the O-ion migration through the bulk is dominant over that on cathode.
Anisotropic power-law inflation for a two scalar fields model
(2011-06-07)
Do, Tuan Q.
;
Kao, W. F.
;
Lin, Ing-Chen
;
物理研究所
;
Institute of Physics
A special class of Bianchi type I expanding solutions in a string motivated theory with a single scalar field has been speculated to break the cosmic no-hair theorem that will not approach the late time isotropic expanding solution. We will show by a new perturbation approach that an unstable mode for the inflationary solutions exists when an additional phantom field is introduced. The result indicates that the existence of an unstable mode is closely related to the extra fields that could be present during the very early Universe.
Spontaneous emission dynamics in an omnidirectional waveguide made of photonic crystals
(2011-06-08)
Huang, Chih-Hsien
;
Cheng, Szu-Cheng
;
Wu, Jing-Nuo
;
Hsieh, Wen-Feng
;
光電工程學系
The spontaneous emission dynamics of atoms embedded in an omnidirectional waveguide (ODWG), a novel optical waveguide, is studied on the basis of the complete reflection of one-dimensional photonic crystals. With the dispersion curve of the single waveguide mode within the photonic band gap and various extents of background dissipation, we characterize the photon-atom interaction in the ODWG. The photon emitter of the system is a two-level atom embedded in the low-index medium of the multilayer-film ODWG or the atom-ODWG system. Fractional calculus, an innovative mathematical method in optical systems, is applied to solve the equation of motion for this atom-ODWG system. Two kinds of states with different group velocities exhibit totally distinctive dynamical behavior. The high frequency waveguide mode with a fast group velocity shows fast exponential decay in propagation while the band-edge mode with a slow group velocity displays non-Markovian dynamics with non-exponential oscillating time evolution. We therefore suggest different functions of this atom-ODWG system for these two kinds of states. The richness of the physical content of the system is also revealed through investigating the dynamical behavior of the band-edge mode. These results aid in further application and fundamental understanding of the atom-ODWG system.
NeurphologyJ: An automatic neuronal morphology quantification method and its application in pharmacological discovery
(2011-06-08)
Ho, Shinn-Ying
;
Chao, Chih-Yuan
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Huang, Hui-Ling
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Chiu, Tzai-Wen
;
Charoenkwan, Phasit
Background: Automatic quantification of neuronal morphology from images of fluorescence microscopy plays an increasingly important role in high-content screenings. However, there exist very few freeware tools and methods which provide automatic neuronal morphology quantification for pharmacological discovery. Results: This study proposes an effective quantification method, called NeurphologyJ, capable of automatically quantifying neuronal morphologies such as soma number and size, neurite length, and neurite branching complexity (which is highly related to the numbers of attachment points and ending points). NeurphologyJ is implemented as a plugin to ImageJ, an open-source Java-based image processing and analysis platform. The high performance of NeurphologyJ arises mainly from an elegant image enhancement method. Consequently, some morphology operations of image processing can be efficiently applied. We evaluated NeurphologyJ by comparing it with both the computer-aided manual tracing method NeuronJ and an existing ImageJ-based plugin method NeuriteTracer. Our results reveal that NeurphologyJ is comparable to NeuronJ, that the coefficient correlation between the estimated neurite lengths is as high as 0.992. NeurphologyJ can accurately measure neurite length, soma number, neurite attachment points, and neurite ending points from a single image. Furthermore, the quantification result of nocodazole perturbation is consistent with its known inhibitory effect on neurite outgrowth. We were also able to calculate the IC50 of nocodazole using NeurphologyJ. This reveals that NeurphologyJ is effective enough to be utilized in applications of pharmacological discoveries. Conclusions: This study proposes an automatic and fast neuronal quantification method NeurphologyJ. The ImageJ plugin with supports of batch processing is easily customized for dealing with high-content screening applications. The source codes of NeurphologyJ (interactive and high-throughput versions) and the images used for testing are freely available (see Availability).
Improvement of quantum efficiency in green light-emitting diodes with pre-TMIn flow treatment
(2011-06-08)
Lee, Ya-Ju
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Chen, Yi-Ching
;
Lu, Tien-Chang
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光電工程學系
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Department of Photonics
The effects of pre-trimethlyindium (TMIn) flow on the improved electrical characteristics and highly stable temperature properties of InGaN green light-emitting diodes (LEDs) are discussed. For the LED sample with a pre-TMIn flow treatment, the tunnelling of injected carriers associated with threading defects is significantly reduced, which promotes the diffusion-recombination of injected carriers, as well as the overall emission efficiency of the LED. In addition, the pre-TMIn flow treatment evidently reduces the dependence of external quantum efficiency on temperature and efficiency droop of green LEDs. As a result, we conclude that the pre-TMIn flow treatment is a promising scheme for the improvement of output performance of InGaN-based green LEDs.
交大e-News第095期
(2011-06-08)
Secretariat
;
國立交通大學秘書室
A crystalline low-bandgap polymer comprising dithienosilole and thieno[3,4-c] pyrrole-4,6-dione units for bulk heterojunction solar cells
(2011-06-08)
Yuan, Mao-Chuan
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Chou, Yi-Jen
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Chen, Chia-Min
;
Hsu, Chang-Lung
;
Wei, Kung-Hwa
We have used Stille coupling polymerization to synthesize a new low-bandgap conjugated polymer, PDTSTPD, that consists of an electron-rich dithieno[3,2-b:2',3'-d]-silole (DTS) unit and an electron-deficient thieno[3,4-c]pyrrole-4,6-dione (TPD) moiety. The polymer exhibited an excellent thermal stability, crystalline characteristics, a broad spectral absorption, and a deep highest occupied molecular orbital (HOMO) energy level, resulting from combination of the rigid TPD and the coplanar DTS units in the polymer backbone. Moreover, the presence of the silicon atoms along the polymer chain ensured PDTSTPD having strong interchain stacking and good hole mobility. An optimal device incorporating the PDTSTPD:PC(71)BM blend at a weight ratio of 1:1 provided a power conversion efficiency of 3.42%. (c) 2011 Elsevier Ltd. All rights reserved.
Room-temperature synthesis of single-crystalline Se nanorods with remarkable photocatalytic properties
(2011-06-09)
Chiou, Yao-De
;
Hsu, Yung-Jung
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材料科學與工程學系
;
Department of Materials Science and Engineering
We demonstrated for the first time that single-crystalline Se nanorods (NRs), prepared with a facile chemical reduction approach at room temperature. may display noticeable catalytic activities toward methylene blue degradation in dark environment after subjected to a short period of irradiation. Such capability of photocatalysis in the dark for Se NRs was attributed to the memory effect related to pre-irradiation treatment. The result of spin-trapping electron paramagnetic resonance measurement suggests that a sustained supply of center dot OH radicals could be attained for Se NRs upon the cease of irradiation, which is accountable for the memory photocatalytic effect as revealed in the dark. As compared to the commercial P-25 TiO(2) powder and Se nanoparticles, the as-synthesized Se NRs exhibited superior photocatalytic performance under UV illumination, demonstrating their potential as active photocatalysts in relevant redox reactions. Furthermore, the recycling test reveals that Se NRs could be promisingly utilized in the long-term course of photocatalysis. The present Se NRs may find potential use for unique photocatalytic applications, in which typical photocatalysis prevails under light illumination, while memory photocatalytic effect takes over when irradiation is interrupted. (C) 2011 Elsevier B.V. All rights reserved.
Small Molecule Amiloride Modulates Oncogenic RNA Alternative Splicing to Devitalize Human Cancer Cells
(2011-06-09)
Chang, Jan-Gowth
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Yang, Den-Mei
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Chang, Wen-Hsin
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Chow, Lu-Ping
;
Chan, Wen-Ling
Alternative splicing involves differential exon selection of a gene transcript to generate mRNA and protein isoforms with structural and functional diversity. Abnormal alternative splicing has been shown to be associated with malignant phenotypes of cancer cells, such as chemo-resistance and invasive activity. Screening small molecules and drugs for modulating RNA splicing in human hepatocellular carcinoma cell line Huh-7, we discovered that amiloride, distinct from four pH-affecting amiloride analogues, could "normalize" the splicing of BCL-X, HIPK3 and RON/MISTR1 transcripts. Our proteomic analyses of amiloride-treated cells detected hypo-phosphorylation of splicing factor SF2/ASF, and decreased levels of SRp20 and two un-identified SR proteins. We further observed decreased phosphorylation of AKT, ERK1/2 and PP1, and increased phosphorylation of p38 and JNK, suggesting that amiloride treatment down-regulates kinases and up-regulates phosphatases in the signal pathways known to affect splicing factor protein phosphorylation. These amiloride effects of "normalized" oncogenic RNA splicing and splicing factor hypo-phosphorylation were both abrogated by pretreatment with a PP1 inhibitor. Global exon array of amiloride-treated Huh-7 cells detected splicing pattern changes involving 584 exons in 551 gene transcripts, many of which encode proteins playing key roles in ion transport, cellular matrix formation, cytoskeleton remodeling, and genome maintenance. Cellular functional analyses revealed subsequent invasion and migration defects, cell cycle disruption, cytokinesis impairment, and lethal DNA degradation in amiloride-treated Huh-7 cells. Other human solid tumor and leukemic cells, but not a few normal cells, showed similar amiloride-altered RNA splicing with devitalized consequence. This study thus provides mechanistic underpinnings for exploiting small molecule modulation of RNA splicing for cancer therapeutics.
CATALYTIC SEEDING CONTROL METHOD
(2011-06-09)
Chen C.C.
;
Cheng Yu-Ting
;
Hsu Lun-Hao
;
Rern Kai
A catalytic seeding control method is disclosed. A catalytic metal film is deposited on a substrate with a nonwettable inclined surface. The catalytic metal film is then melted to form metal droplets. The metal droplets roll along the nonwettable inclined surface and aggregate to form a singular catalytic seed on the bottom of the nonwettable inclined surface. Then, the location of the singular catalytic seed is precisely controlled. Also, the size of the catalytic seed is controlled by adjusting the size of the inclined surface and the thickness of the catalytic metal layer to grow a one-dimensional structure with specific localization and single well-aligned manipulated size. The structure is utilized for the integrated microelectronic device fabrication.
記憶裝置及其迴圈緩衝器
(2011-06-11)
吳奕緯
;
田濱華
;
鍾崇斌
;
單智君
本發明係揭露一種記憶裝置及其迴圈緩衝器(loop buf-fer)。在一實施例中，此迴圈緩衝器包含一緩衝記憶體單元及一分支目的緩衝區(BTB)，緩衝記憶體單元可儲存最內層迴圈指令(innermost loop instruction)，而分支目的緩衝區(BTB)可儲存此緩衝記憶體單元內之指令之追跡資料(track)。藉此，此迴圈緩衝器可儲存包含向前分支(forward branch)及函式(subroutine)之迴圈指令，以進一步減少指令提取之耗能。
部落課輔　陪伴的力量
(2011-06-12)
陳文玲
;
Department of Communication and Technology
;
傳播與科技學系
交通大學山地文化服務團每周固定上山，對偏遠地區的原住民小朋友進行課業輔導。山上部落物資缺乏，缺少資訊刺激，課業輔導對小朋友們而言，必要且需要但是這樣做到底有沒有成效？
延續傳統產業　需要你和我
(2011-06-12)
康甯
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Department of Communication and Technology
;
傳播與科技學系
傳統行業的發展於今位居弱勢，現代科技的發達以及流行趨勢的改變讓不少傳統產業近乎消逝。值得慶幸的是，政府和不少人回過頭來著重這方面文化的保存。社會是否重視對傳統產業的保存擁有很大的影響力，想要將古早的技藝繼續傳承給下一代，需要靠社會大眾一起努力。
發揚傳統文化　小兵立大功
(2011-06-12)
李庭蕙
;
Department of Communication and Technology
;
傳播與科技學系
透過兒童歌仔戲班的成立，秀朗歌仔戲班讓小朋友能對歌仔戲有多一份的認識，也藉此讓歌仔戲向下紮根。期盼日後歌仔戲不再僅是老人專屬，而更是一種充滿新生代活力的傳統戲曲。
霹靂熱潮　戲迷謹慎接招
(2011-06-12)
王雅涵
;
Department of Communication and Technology
;
傳播與科技學系
隨著霹靂布袋戲的經營越走向商業化，也越趨向用心在劇情中塑造人氣角色，並讓旗下的精品能搭上這一代又一代高人氣角色的順風車，以抓住戲迷們的荷包，近來更颳起一陣瘋狂的蒐藏熱潮。