Browsing by Issue Date, starting with "2014-01-22"

Now showing 1 - 20 of 27755

The Elusive Three-Coordinate Dicationic Hydrido Boron Complex
(2014-01-22)
Chen, Wen-Ching
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Lee, Ching-Yu
;
Lin, Bo-Chao
;
Hsu, Yu-Chen
;
Shen, Jiun-Shian
The formation of a hitherto unknown three-coordinate dicationic hydrido boron complex is described. Interestingly, supporting ligand carbodicarbene gave unprecedented reaction with BH3 without using more highly electrophilic Lewis acid precursors. Spectroscopic, crystallographic, and computational analysis was performed to understand the electronic features of these species.
Reducing Regioisomers of Fullerene-Bisadducts by Tether-Directed Remote Functionalization: Investigation of Electronically and Sterically Isomeric Effects on Bulk-Heterojunction Solar Cells
(2014-01-22)
Liao, Ming-Hung
;
Lai, Yin-Yu
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Lai, Yu-Ying
;
Chen, Yen-Ting
;
Tsai, Che-En
C-60 bis-adduct containing a mixture of regio-isomers with different LUMO energy levels and steric geometries could greatly affect the morphological and bulk properties. To investigate the regio-isomer effect on solar cell performance, we have successfully designed and synthesized a regio-selective 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct (S-APM-CBA) by "tether-directed remote functionalization" strategy and a random 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct denoted as R-APM-CBA by traditional cyclopropanation. The dramatic reduction in the number of regio-isomers in S-APM-CBA is confirmed by the H-1 NMR and HPLC measurements and theoretical calculation. Compared to the R-APM-CBA-based device with a J(sc) of 6.63 mA/cm(2), an FF of 44.3% and a PCE of 2.46%, the device using S-APM-CBA yielded a much lower J(sc) of 1.48 mA/cm(2), an FF of 32.2%, and a PCE of 0.38%. Consistently, the electron-only device using S-AMP-CBA exhibited lower electron mobility than the R-AMP-CBA-based device. These results imply that the electronic shallow-trap effect ascribed to the LUMO energy variations turned out to be insignificant in the AMP-CBA system. The lower efficiency and mobility of S-AMP-CBA might due to the assumption that the most probable trans-4-III isomer in S-AMP-CBA prevents the intermolecular facial contact of fullerenes, thereby hindering the electron transporting. Furthermore, the nanomorphology of S-AMP-CBA and R-AMP-CBA active layers could be different because of their different three-dimensional structures. This research demonstrated that steric effect of regio-isomers in a given C-60 bis-adduct is more crucial than electronic shallow-trap effect.
Method For Selecting Transmitting Points In A Communication System
(2014-01-23)
Huang Chung-Jung
;
Sung Chih-Sheng
;
Lee Ta-sung
The present invention provides a method for identifying a specific number of communicating points having relatively smallest accumulated path values from a plurality of transmitting points for a receiving point in a communication system. The method includes steps of: (a) defining a first coordination of each of the plurality of transmitting points and the receiving point on a complex plane; (b) transferring the first coordination of the receiving point to a second coordination thereof, in which the second coordination of the receiving point is near an origin of the complex plane; and (c) identifying the specific number of transmitting points having relatively smallest accumulated path values based on the second coordination of the receiving point.
Ultrahigh-Gain Photodetectors Based on Atomically Thin Graphene-MoS2 Heterostructures
(2014-01-23)
Zhang, Wenjing
;
Chuu, Chih-Piao
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Huang, Jing-Kai
;
Chen, Chang-Hsiao
;
Tsai, Meng-Lin
Due to its high carrier mobility, broadband absorption, and fast response time, the semi-metallic graphene is attractive for optoelectronics. Another two-dimensional semiconducting material molybdenum disulfide (MoS2) is also known as light-sensitive. Here we show that a large-area and continuous MoS2 monolayer is achievable using a CVD method and graphene is transferable onto MoS2. We demonstrate that a photodetector based on the graphene/MoS2 heterostructure is able to provide a high photogain greater than 108. Our experiments show that the electron-hole pairs are produced in the MoS2 layer after light absorption and subsequently separated across the layers. Contradictory to the expectation based on the conventional built-in electric field model for metal-semiconductor contacts, photoelectrons are injected into the graphene layer rather than trapped in MoS2 due to the presence of a perpendicular effective electric field caused by the combination of the built-in electric field, the applied electrostatic field, and charged impurities or adsorbates, resulting in a tuneable photoresponsivity.
New free-air and Bouguer gravity fields of Taiwan from multiple platforms and sensors
(2014-01-25)
Hwang, Cheinway
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Hsu, Hung-Jui
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Chang, Emmy T. Y.
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Featherstone, W. E.
;
Tenzer, Robert
We construct 1' x 1' grids of free-air and Bouguer gravity anomalies around Taiwan with well-defined error estimates for quality assessment. The grids are compiled from land, airborne and shipbome gravity measurements, augmented with altimeter gravity at sea. Three sets of relative land gravity measurements are network-adjusted and outlier-edited, yielding accuracies of 0.03-0.09 mGal. Three airborne gravity sets are collected at altitudes 5156 and 1620 m with accuracies of 2.57-2.79 mGal. Seven offshore shipborne gravity campaigns around Taiwan and its offshore islands yield shallow-water gravity values with 0.88-2.35 mGal accuracies. All data points are registered with GPS-derived geodetic coordinates at cm-dm accuracies, allowing for precise gravity reductions and computing gravity disturbances. The various datasets are combined by the band-limited least-squares collocation in a one-step procedure. In the eastern mountainous (or offshore) region, Bouguer anomalies and density contrasts without considering the oceanic (or land) topographic contribution are underestimated. The new grids show unprecedented tectonic features that can revise earlier results, and can be used in a broad range of applications. (C) 2013 Elsevier B.V. All rights reserved.
Forming-free bipolar resistive switching in nonstoichiometric ceria films
(2014-01-27)
Ismail, Muhammad
;
Huang, Chun-Yang
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Panda, Debashis
;
Hung, Chung-Jung
;
Tsai, Tsung-Ling
The mechanism of forming-free bipolar resistive switching in a Zr/CeO (x) /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO (y) layer at the Zr/CeO (x) interface. X-ray diffraction studies of CeO (x) films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO (x) film and in the nonstoichiometric ZrO (y) interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).
Polarized emission of quantum dots in microcavity and anisotropic Purcell factors
(2014-01-27)
Lee, Yi-Shan
;
Lin, Sheng-Di
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We study the polarization properties of quantum dot (QD) emission coupled with the fundamental cavity modes. A rotation of polarization axis and a change of polarization degree are observed as the coupling is varied. To explain this observation, we derive an analytical model considering the polarization misalignment between QD dipole and cavity mode field. Our model also provides a new approach to extract the anisotropic Purcell factors by analyzing the polarization of detected quantum dot emission coupled to the cavity mode, which paves the way to develop high-efficiency polarized single photon sources. (C) 2014 Optical Society of America
Resonant modes of 12-fold symmetric defect free photonic quasicrystal
(2014-01-27)
Chen, Minfeng
;
Li, Yun-Jing
;
Cheng, Yuh-Jen
;
Chang, Yai-Chung
;
Chang, Chun-Yen
This work investigates the resonant modes of a 12-fold symmetric defect free photonic quasicrystal (PQC) nanorod array using finite difference time domain (FDTD) simulation. Localized modes can exist in PQC without introducing defects due to the lack of translational symmetry. The resonant modes of the unit cell PQC and the one time expanded PQC from unit cell are systematically examined. The resonant spectrum is that of a single rod modified by the interaction among PQC nanorods. The mode confinement is contributed by guided resonance and destructive interference scattering. The self-scaling similarity of resonant spectrum and mode profile are also investigated. (C) 2014 Optical Society of America
Method for carry estimation of reduced-width multipliers
(2014-01-28)
Liao Yen-Chin
;
Chang Hsie-Chia
A low-error reduced-width multiplier is provided by the present invention. The multiplier can dynamically compensate the truncation error. The compensation value is derived by the dependencies among the multiplier partial products, and thus, can be analyzed according to the multiplication type and the multiplier input statistics.
Elliptic flow from thermal photons with magnetic field in holography
(2014-01-28)
Mueller, Berndt
;
Wu, Shang-Yu
;
Yang, Di-Lun
;
物理研究所
;
丘成桐中心
We compute the elliptic flow v(2) of thermal photons in a strongly coupled plasma with constant magnetic field via gauge/gravity duality. The D3/D7 embedding is applied to generate the contributions from massive quarks. By considering the cases in 2 + 1 flavor super Yang-Mills analogous to the photon production in quark gluon plasma, we obtain the thermal photon v(2), which is qualitatively consistent with the direct photon v(2) measured at the relativistic heavy ion collider at intermediate energy. However, due to the simplified setup, the thermal photon v(2) in our model should be regarded as the upper bound for the v(2) generated by solely a magnetic field in the strongly coupled scenario.
Communication: Three-dimensional model for phonon confinement in small particles: Quantitative bandshape analysis of size-dependent Raman spectra of nanodiamonds
(2014-01-28)
Korepanov, Vitaly I.
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Witek, Henryk
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Okajima, Hajime
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Osawa, Eiji
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Hamaguchi, Hiro-O
Raman spectroscopy of nano-scale materials is facing a challenge of developing a physically sound quantitative approach for the phonon confinement effect, which profoundly affects the phonon Raman band shapes of small particles. We have developed a new approach based on 3-dimensional phonon dispersion functions. It analyzes the Raman band shapes quantitatively in terms of the particle size distributions. To test the model, we have successfully obtained good fits of the observed phonon Raman spectra of diamond nanoparticles in the size range from 1 to 100 nm. (C) 2014 AIP Publishing LLC.
Coupling between Protein Conformation and Local Unfolding Highlights the Role of Disorder in Protein Function and Suggests a New Target for Tuberculosis Treatment
(2014-01-28)
Morrell, Thomas E.
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Rafalska-Metcalf, Ilona U.
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Chu, Jhih-Wei
;
Yang, Haw
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交大名義發表
Live Cell Imaging with Rab-Gtpases Elucidates Intracellular Pathways of RGD and iRGD Tagged Cationic Lipid-DNA Nanoparticles
(2014-01-28)
Majzoub, Ramsey N.
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Ewert, Kai K.
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Kotamraju, Venkata R.
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Chan, Chia-Ling
;
Liang, Keng S.
A Single-Step Digital Nucleic Acid Amplification Platform by Digital Plasma Separation on a Chip
(2014-01-28)
Yeh, Erh-Chia
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Yeh, Chi-Cheng Fu
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Hu, Lucy
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Huang, Meng-Yao
;
Lee, Luke P.
Kinetic Ising Model Study of Protein Aggregation
(2014-01-28)
Tsai, Min-Yeh
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Yuan, Jian-Min
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Lin, Sheng-Hsien
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應用化學系
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Department of Applied Chemistry
Method for Making Porous Materials
(2014-01-30)
LEU Jih-Perng
;
CHEN Yu-Han
A method for manufacturing a porous material is disclosed, which comprises the following steps: providing a substrate; coating the substrate with a precursor solution to form a precursor film, wherein the precursor solution includes a precursor compound, a porogen, and a solvent, and the porogen is modified by a surface modification to have an absolute surface electric potential of >25 mV; and treating the precursor film with a thermal curing profile to remove the porogen and form a porous material.
METHOD FOR MANUFACTURING A NOZZLE PLATE CONTAINING MULTIPLE MICRO-ORIFICES FOR CASCADE IMPACTOR
(2014-01-30)
TSAI Chuen-Jinn
;
CHEN Sheng-Chieh
;
CHEN Hong-Dar
A nozzle plate containing multiple micro-orifices for the cascade impactor and a method for manufacturing the same are disclosed. The nozzle plate is formed by a series of semiconductor processes, including lithography, etching and electroplating. The nozzle plate comprises a plate body and a plurality of micro-orifices formed on the plate body. The orifice has a diameter which gradually expands in the direction away from the bottom of the plate body to achieve a smooth inner surface, allowing particles to pass therethrough smoothly without being clogged in the nozzle plate.
MOTION PARAMETER ESTIMATING METHOD, ANGLE ESTIMATING METHOD AND DETERMINATION METHOD
(2014-01-30)
Huang Chung-Jung
;
Dai Chia-Wei
;
Tsai Tsung-Yu
;
Lee Ta-Sung
A motion parameter estimating method, an angle estimating method and a determination method are provided. The methods are adapted for an electronic device. In the angle estimating method, a first frequency modulation continuous wave signal is first transmitted, and at least one antenna receives a second frequency modulation continuous wave signal resulted by a target reflecting the first frequency modulation continuous wave signal. Multiple motion parameters associated with the target are then obtained according to the first frequency modulation continuous wave signal and the second frequency modulation continuous wave signal. Multiple measured values corresponding to the at least one antenna are obtained according to the motion parameters and configuration parameters of the at least one antenna, respectively. Afterwards, the measured values are substituted into a formula to obtain an estimated angle between a preset direction of the electronic device and the target.
METHOD OF PROTEIN PURIFICATION
(2014-01-30)
LI Yaw-Kuen
;
WU Yue-Jin
A method for producing a target protein is provided, which includes steps described below. A crude extract including a fusion protein is provided. The fusion protein includes a tag, a target protein and a linker inserted between the tag and the target protein. The fusion protein and magnetic particles are then bound to form a magnetic particle-binding fusion protein. Finally, the linker of the magnetic particle-binding fusion protein undergoes autocleavage by using a cleavage buffer solution to release the target protein. A one-pot process for producing a purified target protein is also provided.
An efficient synthesis of the C27-C45 fragment of lagunamide A, a cyclodepsipeptide with potent cytotoxic and antimalarial properties
(2014-01-31)
Liu, Hui-Ming
;
Chang, Chieh-Yu
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Lai, Ya-Chi
;
Yang, Mei-Due
;
Chang, Ching-Yao
An efficient and stereoselective synthesis of the entire C27-C45 moiety of lagunamide A has been achieved from 1-[(4S)-4-benzyl-2-thioxothiazolidin-3-yl]propan-1-one in six steps with 22% overall yield. The key step in the synthesis is an asymmetric acetal aldol reaction featuring the enantioselective addition of a chiral thiazolidinethione-derived titanium enolate to an acetal to establish the stereochemistry at C39. (C) 2013 Elsevier Ltd. All rights reserved.