Browsing by Issue Date, starting with "2012-07-15"

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A nano switch mechanism for the redox-responsive sulfotransferase
(2012-07-15)
Lin, Chih-Heng
;
Lin, En-Shyh
;
Su, Tian-Mu
;
Hung, Kuo-Sheng
;
Yang, Yuh-Shyong
Cellular redox signaling is important in diverse physiological and pathological processes. The activity of rat phenol sulfotransferase (rSULT1A1), which is important for the metabolism of hormone and drug, is subjected to redox regulation. Two cysteines, Cys232 and Cys66, nanometer away from each other and from the enzyme active site were proposed to form disulfide bond to regulate the activity of rSULT1A1. A nano switch, composed of a flexible loop from amino acid residues 59-70, explained how this long distance interaction between two cysteines can be achieved. The enzyme properties were investigated through site-directed muatagnesis, circular dichroism, enzyme kinetics and homologous modeling of the rSULT1A1 structures. We proposed that the formation of disulfide bond between Cys232 and Cys66 induced conformational changes of sulfotransferase, then in turn affected its nucleotide binding and enzyme activity. This discovery was extended to understand the possible redox regulation of other sulfotransferases from different organisms. The redox switch can be created in other redox-insensitive sulfotransferases, such as human phenol sulfotransferase (hSULT1A1) and human alcohol sulfotransferase (hSULT2A1), to produce mutant enzymes with redox regulation capacity. This study strongly suggested that redox regulation of drug and hormone metabolism can be significantly varied even though the sequence and structure of SULT1A1 of human and rat have a high degree of homology. (C) 2012 Elsevier Inc. All rights reserved.
Room-Temperature Electro-Luminescence of Type-II GaSb/GaAs Quantum Rings
(2012-07-15)
Lin, Wei-Hsun
;
Lin, Meng-Yu
;
Wu, Shung-Yi
;
Lin, Shih-Yen
;
光電工程學系
The influence of Sb/background As flux ratios on GaSb nano-structures is investigated in this letter. With decreasing Sb/background As flux ratios under high Sb irradiation during the post soaking procedure, ring formation, photoluminescence (PL) intensity enhancement, and PL peak red shift are observed. With further reduced Sb flux and Sb/background As ratios, the observed more intense PL intensities of the quantum-ring (QR) samples compared with quantum dots suggest that more electron-hole wave function overlapping is obtained. The observation of room-temperature electro-luminescence of a QR PIN diode has revealed the potential of the nano-structure in light-emitting device application.
miR-103/107 Promote Metastasis of Colorectal Cancer by Targeting the Metastasis Suppressors DAPK and KLF4
(2012-07-15)
Chen, Hsin-Yi
;
Lin, Yu-Min
;
Chung, Hsiang-Ching
;
Lang, Yaw-Dong
;
Lin, Ching-Jung
Metastasis is the major cause of poor prognosis in colorectal cancer (CRC), and increasing evidence supports the contribution of miRNAs to cancer progression. Here, we found that high expression of miR-103 and miR-107 (miR-103/107) was associated with metastasis potential of CRC cell lines and poor prognosis in patients with CRC. We showed that miR-103/107 targeted the known metastasis suppressors death-associated protein kinase (DAPK) and Kruppel-like factor 4 (KLF4) in CRC cells, resulting in increased cell motility and cell-matrix adhesion and decreased cell-cell adhesion and epithelial marker expression. miR-103/107 expression was increased in the presence of hypoxia, thereby potentiating DAPK and KLF4 downregulation and hypoxia-induced motility and invasiveness. In mouse models of CRC, miR-103/107 overexpression potentiated local invasion and liver metastasis effects, which were suppressed by reexpression of DAPK or KLF4. miR-103/107-mediated downregulation of DAPK and KLF4 also enabled the colonization of CRC cells at a metastatic site. Clinically, the signature of a miR-103/107 high, DAPK low, and KLF4 low expression profile correlated with the extent of lymph node and distant metastasis in patients with CRC and served as a prognostic marker for metastasis recurrence and poor survival. Our findings therefore indicate that miR-103/107-mediated repression of DAPK and KLF4 promotes metastasis in CRC, and this regulatory circuit may contribute in part to hypoxia-stimulated tumormetastasis. Strategies that disrupt this regulation might be developed to block CRC metastasis. Cancer Res; 72(14); 3631-41. (c) 2012 AACR.
Light Extraction Enhancement of GaN-Based Light-Emitting Diodes Using Crown-Shaped Patterned Sapphire Substrates
(2012-07-15)
Chiu, Ching-Hsueh
;
Hsu, Lung-Hsing
;
Lee, Chia-Yu
;
Lin, Chien-Chung
;
Lin, Bo-Wen
In this letter, we report the high performance GaN-based light-emitting diodes (LEDs) with embedded air void array grown by metal-organic chemical vapor deposition. The donut-shaped air void was formed at the interface between crown-shaped patterned sapphire substrates (CPSS) and the GaN epilayer by conventional photolithography. The transmission electron microscopy images demonstrate that the threading dislocations were significantly suppressed by epitaxial lateral overgrowth (ELOG). The Monte Carlo ray-tracing simulation reveals that the light extraction of the air-voids embedded LED was dramatically increased due to a strong light reflection and redirection by the air voids.
A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degrees twisted cell
(2012-07-15)
Lin, Yi-Hsin
;
Chen, Ming-Syuan
;
Lin, Wei-Chih
;
Tsou, Yu-Shih
;
光電工程學系
A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degrees twisted cell (T-PNLC) is demonstrated. T-PNLC consists of three layers. Liquid crystal (LC) directors in the two layers near glass substrates are orthogonal to each other and those two layers modulate two eigen-polarizations of an incident light. As a result, two eigen-polarizations of an incident light experience the same phase shift. In the middle layer, LC directors are perpendicular to the glass substrate and contribute no phase shift. The phase shift of T-PNLC is electrically tunable and polarization-independent. T-PNLC does not require any bias voltage for operation. The phase shift is 0.28 pi rad for the voltage of 30 V-rms. By measuring and analyzing the optical phase shift of T-PNLC at the oblique incidence of transverse magnetic wave, the pretilt angle of LC directors and the effective thickness of three layers are obtained and discussed. The potential applications are spatial light modulators, laser beam steering, and micro-lens arrays. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737260]
Design, Fabrication, and Characterization of Si-Based ARROW-B Photonic Crystal Sharp-Bend Waveguides and Power Splitters
(2012-07-15)
Chen, Jian-Hua
;
Huang, Yang-Tung
;
Yang, Yu-Lin
;
Lu, Ming-Feng
;
生物科技學系
Si-based type-B antiresonant reflecting optical waveguide (ARROW-B) photonic crystal waveguides (PCWs) with 60 degrees bend, 120 degrees bend, and Y-branch power splitter were first successfully fabricated and characterized. A simple capsule-shaped defect was designed to modulate the 60 degrees and 120 degrees photonic crystal (PC) bend corners and Y-branch PC power splitters. In the preliminary experiments, the average bend losses of 60 degrees and 120 degrees PC bend waveguides for both polarizations were lower than 1.5 and 4.2 dB/bend, respectively. For the Y-branch PC power splitters, power imbalances for both polarizations were all lower than 0.7 dB. It shows that the fabricated Si-based ARROW-B PCWs can provide good light sharp-bend ability and power-split ability.
The Influence of the Thermal Effect on CdSe/ZnS Quantum Dots in Light-Emitting Diodes
(2012-07-15)
Chen, Kuo-Ju
;
Chen, Hsin-Chu
;
Shih, Min-Hsiung
;
Wang, Chao-Hsun
;
Kuo, Ming-Yen
This study investigates the effect of temperature on CdSe/ZnS quantum dots (QDs) in GaN-based light-emitting diodes (LEDs) using the phosphor conversion efficiency (PCE) and LED junction temperature. In our simulation, the blue chip and CdSe/ZnS QDs temperature are similar because of their minimal thickness. Furthermore, to verify the effect of temperature on CdSe/ZnS QDs, we use continuous wave and pulsed current sources to measure the relationship between the temperature and relative PCE. Higher junction temperatures are observed with greater CdSe/ZnS QD volume in LEDs. This is attributed to the thermal conduction and nonradiative energy between CdSe/ZnS QDs and blue chip. Therefore, if thermal management is improved, CdSe/ZnS QDs are expected to be used as color converting material in LEDs.
Near-field scanning optical microscopy using a super-resolution cover glass slip
(2012-07-16)
Lin, Yu-Hsuan
;
Tsai, Din Ping
;
電子物理學系
;
Department of Electrophysics
This study presents a novel near-field optics technology. A near-field cover glass slip (NF-CGS) was developed to improve the resolution of optical microscopy beyond the diffraction limit. A multi-layered structure of cover glass/ZnS-SiO2 (130 nm)/AgOx (15 nm)/ ZnS-SiO2 (40 nm) was employed to generate the optical coupling effect for increasing the contrast and enhancing resolution of imaging. This novel innovation is expected to be employed in near-field imaging techniques for samples in different environments because of its simplicity, rapid laser scanning, and minimal costs. Experimental results of 500 nm, 200 nm, and 100 nm standard polystyrene nanospheres on NF-CGS and normal cover glass are demonstrated and imaged by using a laser scanning confocal microscope. (C) 2012 Optical Society of America
Control of growth and inflammatory response of macrophages and foam cells with nanotopography
(2012-07-16)
Mohiuddin, Mohammed
;
Pan, Hsu-An
;
Hung, Yao-Ching
;
Huang, Guewha Steven
;
材料科學與工程學系
Macrophages play an important role in modulating the immune function of the human body, while foam cells differentiated from macrophages with subsequent fatty streak formation play a key role in atherosclerosis. We hypothesized that nanotopography modulates the behavior and function of macrophages and foam cells without bioactive agent. In the present study, nanodot arrays ranging from 10aEuro to 200aEuronm were used to evaluate the growth and function of macrophages and foam cells. In the quantitative analysis, the cell adhesion area in macrophages increased with 10- to 50-nm nanodot arrays compared to the flat surface, while it decreased with 100- and 200-nm nanodot arrays. A similar trend of adhesion was observed in foam cells. Immunostaining, specific to vinculin and actin filaments, indicated that a 50-nm surface promoted cell adhesion and cytoskeleton organization. On the contrary, 200-nm surfaces hindered cell adhesion and cytoskeleton organization. Further, based on quantitative real-time polymerase chain reaction data, expression of inflammatory genes was upregulated for the 100- and 200-nm surfaces in macrophages and foam cells. This suggests that nanodots of 100aEuroaEuro parts per thousand and 200aEuronm triggered immune inflammatory stress response. In summary, nanotopography controls cell morphology, adhesions, and proliferation. By adjusting the nanodot diameter, we could modulate the growth and expression of function-related genes in the macrophages and foam cell system. The nanotopography-mediated control of cell growth and morphology provides potential insight for designing cardiovascular implants.
一種可見光複合觸媒組合物及其形成方法
(2012-07-16)
謝文彬
;
黃志彬
;
袁如馨
;
蘇育俊
;
朱敏嘉
本發明係提供一種可見光複合觸媒組合物及其形成方法。本發明之複合觸媒薄膜組合物包括光觸媒及有機或無機薄膜，且光觸媒擔載於薄膜表面。本發明之可見光複合觸媒薄膜組合物可用於水處理與水回收、空氣污染處理與室內空氣淨化或地下水整治。
一種平整化氮化物基板的方法
(2012-07-16)
李威儀
;
陳奎銘
;
吳尹豪
;
葉彥顯
本發明揭露一種平整化氮化物基板的方法,首先選擇獨立式氮化物基板的特定面向,對該面向進行蝕刻,在經過適度的蝕刻時間後,該特定面向的表面會產生特定的形貌,如柱狀或洞狀或平坦狀等結構,從而降低獨立式氮化物基板的翹曲程度以達到平整化氮化物基板的效果。
Extended-reach access network with downstream radio-over-fiber (ROF) signal and upstream NRZ signal using orthogonal-WDM
(2012-07-16)
Chow, C. W.
;
Huang, S. P.
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Yang, L. G.
;
Yeh, C. H.
;
光電工程學系
We propose and demonstrate an extended-reach radio-over-fiber (ROF) access network. The double-sideband carrier-suppressed (DSCS) optical signal carries the downstream ROF signal. A continuous wave (CW) optical carrier is embedded into the DSCS optical signal and transmitted to the colorless optical networking unit (ONU)/remote antenna unit (RAU) for the upstream signal generation. At the ONU/RAU, the upstream data is orthogonally wavelength division multiplexed (WDM) onto this CW carrier; hence mitigating the cross-talk generated by the downstream signal. Analyses about the optimum power difference between the downstream and the CW signals; as well as the split-ratio are also preformed. (C) 2012 Optical Society of America
光學全像資料讀取系統
(2012-07-16)
孫慶成
;
余業緯
;
吳啟守
;
林烜輝
本發明係關於一種光學全像資料讀取系統,係配合一記錄裝置,用於讀取儲存於記錄裝置之資料,該系統包括:一光發射裝置,用以發射一讀取光束至記錄裝置之複數個記錄位置以分別產生複數個反射光束,其中該等記錄位置係對應至記錄裝置表面一特定位置,並分別位於一預定深度;一感測裝置,係接收該等反射光束,且該等反射光束分別成像於感測裝置之不同位置;以及一控制裝置,係分別與光發射裝置及感測裝置耦合,以控制光發射裝置,並將該等反射光束於感測裝置的複數個成像對應轉換為複數個訊號,以讀取出記錄於記錄裝置上之資料。
Growth of sparse arrays of narrow GaN nanorods hosting spectrally stable InGaN quantum disks
(2012-07-16)
Chen, Yen-Ting
;
Tsai, Wen-Che
;
Chen, Wen-Yen
;
Hsiao, Ching-Lien
;
Hsu, Hsu-Cheng
Wafer-scale production of single InGaN quantum disks (QD) in-a-nanorod array with small rod diameter (> 9 nm) and low rod-density (< 10(8) cm(-2)) has been achieved without extensive processing steps. Excitation power-dependent mu PL spectrum of single QD reveals multi-excitonic peak with 0.75 meV blue-shift for 3 orders of magnitude increasing power, indicating the present system is spectrally stable and nearly free of quantum-confined Stark effects, due possibly to the strain relaxation induced by free surface of small rod diameters. The fully polarized emissions, a high working temperature (180 K), low rod density and good alignment, render this system promising as a potential quantum photon source. (C) 2012 Optical Society of America
Investigation of 4-ASK modulation with digital filtering to increase 20 times of direct modulation speed of white-light LED visible light communication system
(2012-07-16)
Yeh, C. H.
;
Liu, Y. F.
;
Chow, C. W.
;
Liu, Y.
;
Huang, P. Y.
In this demonstration, we propose and experimentally investigate the quaternary-amplitude-shift-keying (4-ASK) modulation with digital filtering to enhance the direct modulation speed of white-light light-emitting-diode (LED) in visible light communication (VLC) system. Here, an ordinary LED commercially available for lighting application with a direct modulation speed of 1 MHz is used. Data rate of 20 Mbit/s can be achieved in a 1 m free space transmission without using optical blue filter. In the previous studies, the transmission rate of LED VLC could only be increased by 2 to 10 times of the direct modulation speed of the white-light LED if using electrical equalization only. Moreover, the adaptive-controlled FIR filter makes the system closer to the matched filtering condition for reducing the inter-symbol-interference (ISI) for the LED VLC. A recorded 20 times enhancement of the direct modulation speed of white-light LED VLC system is demonstrated by using digital filter only and without using optical blue filter. (C) 2012 Optical Society of America
多軸慣性微動系統
(2012-07-16)
洪紹剛
;
鄭喬華
;
林建宇
本發明係有關於一種多軸慣性微動系統，包括有一基座、一第一固定板、一第二固定板、一第一壓電致動器、一第二壓電致動器、一承載台、及一控制器。第一壓電致動器與第二壓電致動器之每一者產生位移之二端係分別連接於第一固定板、與第二固定板。控制器係分別控制輸入第一壓電致動器之電壓、及第二壓電致動器之電壓，致使承載台相對於基座產生移動或旋轉位移。因此，本發明藉由將兩壓電致動器以並聯方式設置，以達到多自由度奈米級之定位同時，結構保持緊緻且體積保持小巧。
Nanoindentation of GaSe thin films
(2012-07-17)
Jian, Sheng-Rui
;
Ku, Shin-An
;
Luo, Chih-Wei
;
Juang, Jenh-Yih
;
電子物理學系
The structural and nanomechanical properties of GaSe thin films were investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The GaSe thin films were deposited on Si(111) substrates by pulsed laser deposition. XRD patterns reveal only the pure (000 l)-oriented reflections originating from the hexagonal GaSe phase and no trace of any impurity or additional phases. Nanoindentation results exhibit discontinuities (so-called multiple 'pop-in' events) in the loading segments of the load-displacement curves, and the continuous stiffness measurements indicate that the hardness and Young's modulus of the hexagonal GaSe films are 1.8 +/- 0.2 and 65.8 +/- 5.6 GPa, respectively.
Electroabsorption and Electrophotoluminescence of Poly(2,3-diphenyl-5-hexyl-p-phenylene vinylene)
(2012-07-19)
Mehata, Mohan Singh
;
Hsu, Chain-Shu
;
Lee, Yuan-Pern
;
Ohta, Nobuhiro
;
應用化學系
Electric-field-induced changes of the absorption, photoluminescence, and photoluminescence excitation spectra and the photoluminescence decay profile have been measured for poly(2,3-diphenyl-5-hexyl-p-phenylene vinylene). The magnitudes of the change of electric dipole moment and molecular polarizability of this compound have been determined for excitation into the first excited state having a strong absorption, and a large charge-separated character, which is relevant for photovoltaic devices, is confirmed. The photoluminescence of this compound is quenched by application of an electric field, and the quenching efficiency increases with decreasing excitation wavelength. Field-assisted dissociation is considered to occur from the photoexcited Franck-Condon state, resulting in the field-induced decrease in the population of the emitting state, which induce the quenching of photoluminescence.
Frame Prediction System and Prediction Method Thereof
(2012-07-19)
PENG WEN-HSIAO
;
CHEN YI-WEN
The present invention discloses a frame prediction system and a prediction method thereof. An initializing module initializes a first image block having a plurality of pixels. A providing module provides a first centroid and a first motion vector of a second image block. The location lookup module finds a location according to the first centroid, and generates a first weight and a second weight respectively according to a relationship between each of the pixels, the first centroid and the location. A vector lookup module finds a second motion vector, which gives a minimum pixel intensity error for the plurality of pixels in the first image block according to the first centroid, the first motion vector, the location, the first weight and the second weight. A processing module sequentially calculates a plurality of predictive intensity values according to the motion vectors and the weights.
Method for smoothing group lll nitride semiconductor substrate
(2012-07-19)
Lee Wei-I
;
Chen Kuei-Ming
;
Wu Yin-Hao
;
Yeh Yen-Hsien
The invention discloses a smoothing method to decrease bowing of group III nitride semiconductor substrate. The certain face of group III nitride semiconductor substrates is etched under the appropriate etching recipe and time, the certain morphology such as rod-type and other structures are appeared at the certain face. And such structures releases the compressive stresses at these certain faces, resulting in clearly increasing the bowing radius of the group III nitride semiconductor substrates, finally decreasing the bowing phenomenon of the group III nitride semiconductor substrate.