Browsing by Issue Date, starting with "2010-08-06"

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Covalent linkage of nanodiamond-paclitaxel for drug delivery and cancer therapy
(2010-08-06)
Liu, Kuang-Kai
;
Zheng, Wen-Wei
;
Wang, Chi-Ching
;
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.
;
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
;
人文與社會科學研究中心
;
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。
應用於低密度奇偶校驗（ＬＤＰＣ）解碼器之集合迴旋比較方法
(2010-08-11)
洪瑞徽
;
洪瑞鴻
;
陳紹基
本發明係揭露一種應用於低密度奇偶校驗解碼器之集合迴旋比較方法，其係應用在一查核節點單元(CNU)或變量節點單元(VNU)中。此種有系統化之方法係先對輸入之所有元素進行初始化以取得一個矩陣；再利用矩陣之對稱性與每列之近似性的特性，依序對所有元素之水平與垂直方向重覆數量最多、水平方向為連續元素者、非連續元素但為對稱之非邊界元素，以及邊界元素與其同列之端迴相鄰元素等原則形成不同類型之集合，以利用每個比較集合之間的高度重疊性，來有效降低基本比較運算量，並適用各種輸入數目，進而提高整體低密度奇偶校驗解碼器之效能。
微探針陣列結構
(2010-08-11)
邱俊誠
;
張志瑋
;
洪振鈞
本發明提供一種具自我固定功能之微探針陣列結構，用以感測各種生理訊號，其特色在於於蝕刻過程中控制蝕刻參數，製作出底部截面積縮小之微探針結構，使微探針可穩固於皮膚組織內，並於微探針上形成一導電層以供感測訊號之用。本發明更提出一種可使微探針間電性分離之設計，使微探針陣列可用於多種生理訊號的量測，同時也可作為刺激源使用。
Conductivity and tunneling density of states in granular Cr films
(2010-08-12)
Sun, Yu-Chen
;
Yeh, Sheng-Shiuan
;
Lin, Juhn-Jong
;
電子物理學系
;
物理研究所
We have measured the tunneling differential conductances, G(V), of four Al/AlOx/Cr planar tunnel junctions as well as the conductivities, sigma(T), of the Cr electrodes at liquid-helium temperatures. The Cr electrodes were made to be granular with dimensionless intergrain tunneling conductance spanning from g similar or equal to 1 to g >> 1, and the dimensionality of the granular array d=3. For the samples with g >> 1, we found that the measured G(V) curves display large zero-bias singularities which obey a ln V law at low bias voltages (less than or similar to a few millielectron volt) while crossing over to a root V law at high bias voltages. Simultaneously, the conductivities of the Cr electrodes reveal ln T dependence below a characteristic temperature. These results are explained in terms of the recent theory of granular metals. In a sample with g similar or equal to 1, in addition to the conductivity dependence sigma proportional to ln T, we observed a universal scaling behavior of the normalized differential conductance [G(V, T) -G(0, T)]/root T with the combined parameter root e vertical bar V vertical bar/k(B)T in a wide temperature interval of 2.5-32 K. This result is not yet understood.
Tonic and phasic EEG and behavioral changes induced by arousing feedback
(2010-08-15)
Lin, Chin-Teng
;
Huang, Kuan-Chih
;
Chao, Chih-Feng
;
Chen, Jian-Ann
;
Chiu, Tzai-Wen
This study investigates brain dynamics and behavioral changes in response to arousing auditory signals presented to individuals experiencing momentary cognitive lapses during a sustained-attention task. Electroencephalographic (EEG) and behavioral data were simultaneously collected during virtual-reality (VR) based driving experiments, in which subjects were instructed to maintain their cruising position and compensate for randomly induced lane deviations using the steering wheel. 30-channel EEG data were analyzed by independent component analysis and the short-time Fourier transform. Across subjects and sessions, intermittent performance during drowsiness was accompanied by characteristic spectral augmentation or suppression in the alpha- and theta-band spectra of a bilateral occipital component, corresponding to brief periods of normal (wakeful) and hypnagogic (sleeping) awareness and behavior. Arousing auditory feedback was delivered to the subjects in half of the non-responded lane-deviation events, which immediately agitated subject's responses to the events. The improved behavioral performance was accompanied by concurrent spectral suppression in the theta- and alpha-bands of the bilateral occipital component. The effects of auditory feedback on spectral changes lasted 30 s or longer. The results of this study demonstrate the amount of cognitive state information that can be extracted from noninvasively recorded EEG data and the feasibility of online assessment and rectification of brain networks exhibiting characteristic dynamic patterns in response to momentary cognitive challenges. (C) 2010 Elsevier Inc. All rights reserved.
Ultra-High Data-Rate 60 GHz Radio-Over-Fiber Systems Employing Optical Frequency Multiplication and OFDM Formats
(2010-08-15)
Lin, Chun-Ting
;
Chen, Jyehong
;
Shih, Po-Tsung
;
Jiang, Wen-Jr
;
Chi, Sien
The increasing demand for wireless video-based interactive and multimedia data services explains why 60-GHz millimeter-wave wireless system is a promising candidate to provide multi-gigabit-per-second wireless services. While attempting to generate and transmit 60 GHz signals in a wireless system cost effectively and increase the spectral efficiency to facilitate multi-gigabit-per-second services, this work reviews three radio-over-fiber (RoF) systems based on optical frequency multiplication (up to 6 times) to reduce the bandwidth requirement of optical transmitters. Additionally, orthogonal frequency division multiplexing (OFDM) signals with multi-level modulation formats (16 QAM) are utilized to achieve an ultrahigh data rate of 28 Gbps within the 7-GHz license-free band and compensate for an uneven frequency response of 60-GHz RoF systems. Negligible power penalty following 25-km standard single mode fiber (SSMF) transmission is observed, capable of significantly extending the service range to various applications within a building or campus.
Extracting photon periodic orbits from spontaneous emission spectra in laterally confined vertically emitted cavities
(2010-08-15)
Chen, Yung-Fu
;
Yu, Yan-Ting
;
Huang, Yu-Jen
;
Chiang, Po-Yi
;
Su, Kuan-Wei
We report our observation of the signature of photon periodic orbits in the spontaneous emission spectra of large-aperture vertical-cavity surface-emitting lasers (VCSELs). The high-resolution measurement clearly demonstrates that over a thousand cavity modes with a narrow linewidth can be perfectly exhibited in the spontaneous emission spectrum just below the lasing threshold. The Fourier-transformed spectrum is analyzed to confirm that the spontaneous emission spectra of large-aperture VCSELs can be exploited to analogously investigate the energy spectra of the 2D quantum billiards. (C) 2010 Optical Society of America
Label-free detection of DNA using novel organic-based electrolyte-insulator-semiconductor
(2010-08-15)
Lin, Tsung-Wu
;
Kekuda, Dhananjay
;
Chu, Chih-Wei
;
光電工程學系
;
Department of Photonics
In this study, we have constructed the first organic field effect sensor based on an electrolyte-insulator-semiconductor structure (OEIS) and applied this novel device to pH and DNA sensing. Variations in the insulator-electrolyte surface potential, which originate from either the change of the ionization states of the insulator surface groups or the binding of charged molecules to the insulator surface, modify the flat band voltage (V(FB)) of the OEIS sensor. The pH sensing experiments of OEIS sensor showed that the output signal linearly depended on pH solution in the range from pH 2 to pH 12, and an average sensitivity of 44.1 mV/pH was obtained. In the biosensing experiments, the absorption of positively charged poly-L-lysine on the insulator surface resulted in the reduction of the V(FB) value, whereas the subsequent binding of negatively charged single-stranded DNA probe (ssDNA) via electrostatic interaction increased the VFB value. Furthermore, the ssDNA-immobilized OEIS device was successfully used for the detection of DNA hybridization. The detection limit of complementary DNA was as low as 1 mu M, and the output signal of OEIS biosensor linearly increased with the logarithm of complementary DNA concentration in the range from 5 x 10(-5) to 10(-7) M. The easy and inexpensive fabrication of the OEIS device allows to be served as a potentially disposable and sensitive biosensor. (C) 2010 Elsevier B.V. All rights reserved.
Imaging brain hemodynamic changes during rat forepaw electrical stimulation using functional photoacoustic microscopy
(2010-08-15)
Liao, Lun-De
;
Li, Meng-Lin
;
Lai, Hsin-Yi
;
Shih, Yen-Yu I.
;
Lo, Yu-Chun
The present study reported the development of a novel functional photoacoustic microscopy (fPAM) system for investigating hemodynamic changes in rat cortical vessels associated with electrical forepaw stimulation. Imaging of blood optical absorption by fPAM at multiple appropriately-selected and distinct wavelengths can be used to probe changes in total hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) and hemoglobin oxygen saturation (SO(2)). Changes in CBV were measured by images acquired at a wavelength of 570 nm (lambda(570)), an isosbestic point of the molar extinction spectra of oxy- and deoxy-hemoglobin, whereas SO(2) changes were sensed by pixel-wise normalization of images acquired at lambda(560) or lambda(600) to those at lambda(570). We demonstrated the capacity of the fPAM system to image and quantify significant contralateral changes in both SO(2) and CBV driven by electrical forepaw stimulation. The fPAM system complements existing imaging techniques, with the potential to serve as a favorable tool for explicitly studying brain hemodynamics in animal models. (C) 2010 Elsevier Inc. All rights reserved.
Simple 14-Gb/s Short-Range Radio-Over-Fiber System Employing a Single-Electrode MZM for 60-GHz Wireless Applications
(2010-08-15)
Jiang, Wen-Jr
;
Lin, Chun-Ting
;
Ng'oma, Anthony
;
Shih, Po-Tsung
;
Chen, Jason Jyehong
This paper demonstrates the feasibility of a simple multigigabit-per-second (Gbps) radio-over-fiber (RoF) system employing multilevel orthogonal frequency-division-multiplexing (OFDM) signal modulation at 60 GHz and a single-electrode Mach-Zehnder modulator (MZM). In this paper, the impact of fiber chromatic dispersion and OFDM beat noise on the performance of the RoF system are investigated by theoretical analysis, VPI WDM-TransmissionMaker simulation and experimental demonstration. A 13.875-Gb/s QPSK OFDM signal occupying the full 7-GHz license-free band at 60 GHz with frequency multiplication for the RoF link is demonstrated. After 3 km of standard single-mode fiber transmission with no dispersion compensation, the power penalty is less than 3 dB.
Inactivation of E. coli and B. subtilis by a parallel-plate dielectric barrier discharge jet
(2010-08-15)
Chiang, M. H.
;
Wu, J. Y.
;
Li, Y. H.
;
Wu, J. S.
;
Chen, S. H.
Inactivation of Escherichia coli and Bacillus subtilis using the jet region of a parallel-plate air dielectric barrier discharge (DBD) driven by a distorted sinusoidal voltage power supply under atmospheric-pressure condition is reported. Various types of working gases, including pure N(2), pure O(2), and compressed air, were tested. Discharges were characterized electrically by measuring the discharge current, applied voltage and absorbed power, and optically by measuring the optical emission spectra in the UV-visible range and absorption spectra in the IR range. Results of survival rate show that both E. coil and B. subtilis cells (up to 10(7) CFU/mL) can be effectively inactivated using less than 18 passes (1.8 s of residence time in total) of exposure to the post-discharge jet region of compressed air and oxygen discharges at different treating distances in the range of 4-20 mm. Among these, the compressed-air discharge performs the best in inactivating both two types of the bacterial cells, because of the abundant ozone generation and probably through the assistance of nitrous oxide generated in the discharge. In summary, the post-discharge jet region of an oxygen-contained parallel-plate DBD driven by a distorted sinusoidal voltage power driven is very effective in inactivating both E. coli and B. subtilis cells under the present test conditions. Crown Copyright (c) 2010 Published by Elsevier B.V. All rights reserved.
Theory and Technology for Standard WiMAX Over Fiber in High Speed Train Systems
(2010-08-15)
Yeh, Chien-Hung
;
Chow, Chi-Wai
;
Liu, Yen-Liang
;
Wen, Sz-Kai
;
Chen, Shi-Yang
In this investigation, we propose and investigate the standard WiMAX access in high speed railway (HSR) using radio over fiber (RoF) link. We also discuss the theory of mobile WiMAX at a target speed of 300 km/hr in simulation. We also analyze the effect of the Doppler frequency shift over HSR. The effective transmission fiber length in the WiMAX-RoF system was limited due to the time-division-duplex (TDD) protocol in the practical WiMAX. Thus, we also demonstrate the transmission limitation and performance of the standard WiMAX access in RoF link. The performances of throughput and packet loss at different fiber lengths are also investigated and discussed. Furthermore, a WiMAX-RoF field trial is also demonstrated based on a simple two RAUs RoF architecture. It was tested and measured in the SongShan tunnel of the Taiwan high speed railway (THSR).
具有非極性三族－氮化物層的多層結構及其製法
(2010-08-16)
李威儀
;
陳振芳
;
江振豪
一種具有非極性三族-氮化物層的多層結構及其製法,包括在基板上形成複數成核層;以及於該成核層上形成非極性三族-氮化物層,其中,各該複數成核層係獨立選自下式(I)之氮化物:AxB1-xN (I) 式中,A和B係選自B、Al、Ga、IN或Tl之不相同的元素,且0≦x≦1。該複數成核層可有效減緩應力、減少晶格位差、阻擋差排延伸並降低差排密度,故可形成表面平坦且結晶品質佳之三族-氮化物層。