Browsing by Issue Date, starting with "2017-02-10"

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In-situ Multimodal Imaging and Spectroscopy of Mg Electrodeposition at Electrode-Electrolyte Interfaces
(2017-02-10)
Wu, Yimin A.
;
Yin, Zuwei
;
Farmand, Maryam
;
Yu, Young-Sang
;
Shapiro, David A.
We report the study of Mg cathodic electrochemical deposition on Ti and Au electrode using a multimodal approach by examining the sample area in-situ using liquid cell transmission electron microscopy (TEM), scanning transmission X-ray microscopy (STXM) and X-ray absorption spectroscopy (XAS). Magnesium Aluminum Chloride Complex was synthesized and utilized as electrolyte, where non-reversible features during in situ charging-discharging cycles were observed. During charging, a uniform Mg film was deposited on the electrode, which is consistent with the intrinsic non-dendritic nature of Mg deposition in Mg ion batteries. The Mg thin film was not dissolvable during the following discharge process. We found that such Mg thin film is hexacoordinated Mg compounds by in-situ STXM and XAS. This study provides insights on the non-reversibility issue and failure mechanism of Mg ion batteries. Also, our method provides a novel generic method to understand the in situ battery chemistry without any further sample processing, which can preserve the original nature of battery materials or electrodeposited materials. This multimodal in situ imaging and spectroscopy provides many opportunities to attack complex problems that span orders of magnitude in length and time scale, which can be applied to a broad range of the energy storage systems.
Contrast-sensitivity-based evaluation method of a surveillance camera's visual resolution: improvement from the conventional slanted-edge spatial frequency response method
(2017-02-10)
Qin, Zong
;
Wong, Po-Jung
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Chao, Wei-Chung
;
Lin, Fang-Cheng
;
Huang, Yi-Pai
Visual resolution is an important specification of a surveillance camera, and it is usually quantified by linewidths per picture height (LW/PH). The conventional evaluation method adopts the slanted-edge spatial frequency response (e-SFR) and uses a fixed decision contrast ratio to determine LW/PH. However, this method brings about a considerable error with respect to subjectively judged results because the perceptibility of the human vision system (HVS) varies with spatial frequency. Therefore, in this paper, a systematic calculation method, which combines the contrast sensitivity function characterizing the HVS and e-SFR, is proposed to solve LW/PH. Eight 720P camera modules in day mode, four 720P modules in night mode, and two 1080P modules in day mode are actually adopted. Corresponding to the three modes, mean absolute error between objective and subjective LW/PH are suppressed to as low as 26 (3.6% of 720P), 27 (3.8% of 720P), and 49 (4.5% of 1080P), while those of the conventional method are 68 (9.4% of 720P), 95 (13.2% of 720P), and 118 (10.9% of 1080P).(C) 2017 Optical Society of America
A Novel Read Scheme for Large Size One-Resistor Resistive Random Access Memory Array
(2017-02-10)
Zackriya, Mohammed, V
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Kittur, Harish M.
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Chin, Albert
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The major issue of RRAM is the uneven sneak path that limits the array size. For the first time record large One-Resistor (1R) RRAM array of 128x128 is realized, and the array cells at the worst case still have good Low-/High-Resistive State (LRS/HRS) current difference of 378 nA/16 nA, even without using the selector device. This array has extremely low read current of 9.7 mu A due to both low-current RRAM device and circuit interaction, where a novel and simple scheme of a reference point by half selected cell and a differential amplifier (DA) were implemented in the circuit design.
Ran-dependent TPX2 activation promotes acentrosomal microtubule nucleation in neurons
(2017-02-13)
Chen, Wen-Shin
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Chen, Yi-Ju
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Huang, Yung-An
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Hsieh, Bing-Yuan
;
Chiu, Ho-Chieh
The microtubule (MT) cytoskeleton is essential for the formation of morphologically appropriate neurons. The existence of the acentrosomal MT organizing center in neurons has been proposed but its identity remained elusive. Here we provide evidence showing that TPX2 is an important component of this acentrosomal MT organizing center. First, neurite elongation is compromised in TPX2-depleted neurons. In addition, TPX2 localizes to the centrosome and along the neurite shaft bound to MTs. Depleting TPX2 decreases MT formation frequency specifically at the tip and the base of the neurite, and these correlate precisely with the regions where active GTP-bound Ran proteins are enriched. Furthermore, overexpressing the downstream effector of Ran, importin, compromises MT formation and neuronal morphogenesis. Finally, applying a Ran-importin signaling interfering compound phenocopies the effect of TPX2 depletion on MT dynamics. Together, these data suggest a model in which Ran-dependent TPX2 activation promotes acentrosomal MT nucleation in neurons.
The structural and electrical comparison of Y2O3 and Ti-doped Y2O3 dielectrics
(2017-02-15)
Lee, Ming Ling
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Kao, Chyuan Haur
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Chen, Hsiang
;
Lin, Chan Yu
;
Chung, Yu Teng
A Ti-doped Y2O3(Y2Ti2O5) dielectric on polycrystalline silicon followed by rapid thermal annealing results in improved characteristics including a higher effective dielectric constant, higher breakdown electric field, lower electron trapping rate, and larger charge-to-breakdown when compared with Y2O3. The performance of high-k Y2O3 and Y2Ti2O5 dielectrics were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), capacitance-voltage, and current density-voltage. Incorporating Ti into the Y2O3 dielectric imparts improvements in the structural and electrical performance of the material. The Y2Ti2O5 dielectric with 800 degrees C annealing treatment has the best performance among all the samples tested.
Band-Engineered Local Cooling in Nanoscale Junctions
(2017-02-15)
Hsu, Bailey C.
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Chen, Yu-Chang
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電子物理學系
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Department of Electrophysics
The stability and performance of nanoscale junctions are closely related to the local effective temperature. The local effective temperature is mainly caused by the competition between heating and cooling processes in inelastic electron-phonon scat-tering. Local cooling occurs when the rate of energy in cooling exceeds that in heating. Previous research has been done using either specific potential configuration or an adatom to achieve local cooling. We propose an engineer-able localcooling mechanism in asymmetric two-terminal tunneling junctions, in which one electrode is made of metal, whereas the other is made of a selectable bad-metal, such as heavily-doped polysilicon. The width of energy window of the selectable material, defined as the width covering all possible energy states counting from the conduction band minimum, can be engineered through doping. Interestingly, we have shown that substantial local cooling can be achieved at room temperature when the width of energy window of the low-density electrode is comparable to the energy of the phonon. The unusual local cooling is caused by the narrowed width of energy window, which obstructs the inelastic scattering for heating.
Type-II GaAs0.5Sb0.5/InP Uni-Traveling Carrier Photodiodes With Sub-Terahertz Bandwidth and High-Power Performance Under Zero-Bias Operation
(2017-02-15)
Wun, Jhih-Min
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Chao, Rui-Lin
;
Wang, Yu-Wen
;
Chen, Yi-Han
;
Shi, Jin-Wei
We successfully demonstrate ultrafast uni-traveling carrier photodiodes (PD) with sub-terahertz bandwidth (similar to 170 GHz) and high-power performance under zero bias and at 1.55-mu m optical wavelength operation. By using a type-II (GaAs0.5Sb0.5/InP) absorption-collector interface and inserting an n-type (1 x 1018 cm(-3)) charge layer in the collector, the current blocking (Kirk) effect can be greatly minimized. A stack of undoped Al-x In0.52Ga0.48-x As layers with different Aluminum mole fractions (x: 0.2 to 0.08) and bandgaps is adopted as the collector layer. This graded-bandgap design can provide a built-in electric field and further shorten the internal collector transit time. The demonstrated PD structure achieves a 3-dB optical-to-electrical bandwidth of 170 GHz and subterahertz output power -11.3 dBm at 170 GHz, a record among all the reported zero-bias PDs.
High-Capacity Carrierless Amplitude and Phase Modulation for WDM Long-Reach PON Featuring High Loss Budget
(2017-02-15)
Wei, Chia-Chien
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Chen, Kuan-Zhou
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Chen, Li-Wei
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Lin, Che-Yu
;
Huang, Wan-Jou
This paper utilizes spectrally efficient carrierless amplitude and phase (CAP) modulation and four wavelength division multiplexing channels in formulation of a high-capacity transmission system. The dispersion and loss associated with a single-mode fiber of 60 km can result in severe power fading and insufficient loss budget, respectively. This study employed high launch power to overcome these issues and thereby achieve long-reach transmission without the need for dispersion compensation or an optical inline amplifier. Modified Volterra filtering is used to deal with the linear and nonlinear distortions within the system. This allowed for the inclusion of cost-effective 10-GHz-class electro-absorption modulators and p-i-n detectors for 4-lambda 224-Gb/s 32-CAP 60-km transmission with a loss budget of 26 dB/channel. The proposed system provides support for the 64 optical network units (ONUs) with downstream transmission of > 3 Gb/s/ONU for future long-reach passive optical networks. We also examined the transmission performance of each channel under various launch powers. Increasing launch power from 9 to 18 dBm/channel increases the loss budget by 9 dB and expands the total capacity by 42%.
光感測裝置及其應用
(2017-02-16)
楊裕雄
;
陳建宏
;
林志衡
本發明提供一種光感測裝置及其應用。光感測裝置包含電晶體、矽奈米通道以及濾光染料層。電晶體包含源極、汲極及閘極。矽奈米通道連接源極與汲極設置用於接收光照。濾光染料層位於矽奈米通道接收光照的表面上。
發光元件封裝結構
(2017-02-16)
林建中
;
郭浩中
;
佘慶威
;
韓皓惟
;
陳國儒
本發明提供一種發光元件封裝結構，其包含基板、發光元件陣列、封膠層、散射粒子以及螢光材料層。發光元件陣列位於基板上。封膠層覆蓋發光二極體陣列。散射粒子散佈於封膠層中。螢光材料層位於封膠層上。
Review of lattice results concerning low-energy particle physics
(2017-02-17)
Aoki, S.
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Aoki, Y.
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Becirevic, D.
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Bernard, C.
;
Blum, T.
We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the determination of the light-quark masses, the form factor f(+)(0), arising in the semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK / f pi and its consequences for the CKM matrix elements V-us and V-ud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2) L x SU(2) R and SU(3) L x SU(3) R Chiral Perturbation Theory. We review the determination of the B-K parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the StandardModel. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for m(c) and m(b) (also new compared to the previous review), as well as those for D- and B-meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant alpha(s).
交大e-News第226期-機車遊行嘉年華 2017年丁酉梅竹賽系列活動開跑
(2017-02-20)
國立交通大學秘書室
;
Secretariat
Polarization- selective ultra-broadband super absorber
(2017-02-20)
Zhong, Yan Kai
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Fu, Sze Ming
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Huang, Weiming
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Rung, Ding
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Huang, Jian Yi-Wen
While a broadband metamaterial perfect absorber (MPA) has been implemented and proposed intensively in recent years, an ultra-broadband perfect absorber with polarization selectivity has not been realized in literature. In this work, we propose a configuration of polarization-selective (PS) MPA with ultra-wide absorption bandwidth. The aluminum wire grid is integrated on top of the ultrathin-metal-dielectric stacking. The transverse electric (TE) wave is blocked due to the requirement of zero tangential electric field at the metal surface. The transverse magnetic field can pass the aluminum wire-grids because the normal electric field can be supported by the surface charge density at the metal surface, and full absorption of the TM wave is accomplished by the metal-dielectric stacking beneath. Theoretical calculation using rigorously coupled wave analysis demonstrates the wavelength selectivity from lambda = 1.98 mu m to lambda = 11.74 mu m where the TE absorption is <0.04 while TM absorption is >0.95, using 300 nm thick aluminum (Al) wire grid with 16-pair SiO2/Ti stacking. Additionally, the design is wavelength scalable by adjusting the dielectric thickness (t(sio2)) and the wire grid period (P) and height (t). The experimental result is demonstrated using Al grids and Ti/SiO2, and the measured result fully supports the calculated prediction. (C) 2017 Optical Society of America
Recombination Pathways in Green InGaN/GaN Multiple Quantum Wells
(2017-02-21)
Lin, Tao
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Kuo, Hao Chung
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Jiang, Xiao Dong
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Feng, Zhe Chuan
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光電工程學系
This paper reports the transient photoluminescence (PL) properties of an InGaN/GaN multiple quantum well (MQW) light-emitting diode (LED) with green emission. Recombination of localized excitons was proved to be the main microscopic mechanism of green emission in the sample. The PL dynamics were ascribed to two pathways of the exciton recombination, corresponding to the fast decay and the slow decay, respectively. The origins of slow decay and fast decay were assigned to local compositional fluctuations of indium and thickness variations of InGaN layers, respectively. Furthermore, the contributions of two decay pathways to the green PL were found to vary at different emission photon energy. The fraction of fast decay pathway decreased with decreasing photon energy. The slow radiative PL from deep localized exciton recombination suffered less suppression from non-radiative delocalization process, for the higher requested activation energy. All these results supported a clear microscopy mechanism of excitation-emission process of the green MQW LED structure.
Extracting trajectory equations of classical periodic orbits from the quantum eigenmodes in two-dimensional integrable billiards
(2017-02-21)
Hsieh, Y. H.
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Yu, Y. T.
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Tuan, P. H.
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Tung, J. C.
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Huang, K. F.
The trajectory equations for classical periodic orbits in the equilateral-triangular and circular billiards are systematically extracted from quantum stationary coherent states. The relationship between the phase factors of quantum stationary coherent states and the initial positions of classical periodic orbits is analytically derived. In addition, the stationary coherent states with noncoprime parametric numbers are shown to correspond to the multiple periodic orbits, which cannot be explicable in the one-particle picture. The stationary coherent states are further verified to be linked to the resonant modes that are generally observed in the experimental wave system excited by a localized and unidirectional source. The excellent agreement between the resonant modes and the stationary coherent states not only manifests the importance of classical features in experimental systems but also paves the way to manipulate the mesoscopic wave functions localized on the periodic orbits for applications.
Ag Doping of Organometal Lead Halide Perovskites: Morphology Modification and p-Type Character
(2017-02-23)
Shahbazi, Saeed
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Tsai, Cheng-Min
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Narra, Sudhakar
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Wang, Chi-Yung
;
Shiu, Hau-Shiang
We report a simple synthetic approach to grow uniform CH3NH3PbI3 perovskite (PSK) layers free of pinholes via ciE varied portions of silver iodide (AgI) added to the precursor solution. XRD/EDS elemental mapping experiments demonstrated nearly uniform Ag distribution inside the perovskite film. When the 1% AgI- assisted perovskite films were fabricated into a p-i-n planar device, the a) photovoltaic performance was enhanced by similar to 30% (PCE increased from 9.5% to 12.0%) relative to the standard cell without added AgI. . Measurement of electronic properties using a hall setup indicated that perovskite films show p-type character after Ag doping, whereas the film is n-type without Ag. Transients of photoluminescence of perovskite films with and without AgI additive deposited on glass, p-type (PEDOT:PSS), and n-type (TiO2) contact layers were recorded with a time-correlated single-photon counting (TCSPC) technique. The TCSPC results indicate that addition of AgI inside perovskite in contact with PEDOT:PSS accelerated the hole-extraction motion whereas that in contact with TiO2 led to a decelerated electron extraction, in agreement with the trend observed from the photovoltaic results. The silver cationic dopant inside the perovskite films had hence an effect of controlling the morphology to improve photovoltaic performance for devices with p-i-n configuration.
The electronic structure, optical absorption and photocatalytic water splitting of (Fe plus Ni)-codoped TiO2: A DFT + U study
(2017-02-23)
Lin, Yanming
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Jiang, Zhenyi
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Zhu, Chaoyuan
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Zhang, Ruiqin
;
Hu, Xiaoyun
The electronic and optical properties of Fe or/and Ni (co)doped anatase and rutile TiO2 were investigated using the spin-polarized density functional theory. Our calculated results indicate that the synergistic effect of (Fe + Ni) codoping can lead to a band gap narrowing and the hybridized states of Fe 3d and Ni 3d appearing in the forbidden gap, which enhances greatly the optical absorption of TiO2 nanomaterials from the ultraviolet-light to the infrared-light region and reduces the recombination of photogenerated electron hole pairs. In particular, (Fe + Ni) codoping can improve greatly the infrared-light absorption of TiO2 nanomaterials. Furthermore, the researches of electronegativity show that (Fe + Ni)codoped TiO2 system has a stronger redox power for hydrogen generation by photo catalytic water splitting compared with pure, Fe-doped, and Ni-doped TiO2 systems. These results lead to an outstanding solar energy photocatalytic water splitting for hydrogen generation in (Fe + Ni)-codoped TiO2 photocatalyst. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Honeysuckle aqueous extract and induced let-7a suppress dengue virus type 2 replication and pathogenesis
(2017-02-23)
Lee, Ying-Ray
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Yeh, Siao-Fen
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Ruan, Xiao-Ming
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Zhang, Hao
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Hsu, Sheng-Da
Ethnopharmacological relevance: Honeysuckle (Lonicera japonica Thunb.), a traditional Chinese herb, has widely been used to treat pathogen infection. However, the underlying-mechanism remains elusive. Aims of the study: To reveal the host microRNA (miRNA) profile with the anti-viral activity after honeysuckle treatment. Materials and methods: Here we reveal the differentially expressed miRNAs by Solexa (R) deep sequencing from the blood of human and mice after the aqueous extract treatment. Among these overexpressed innate miRNAs both in human and mice, let-7a is able to target the NS1 region (nt 3313-3330) of dengue virus (DENV) serotypes 1, 2 and 4 predicated by the target predication software. Results: We confirmed that let-7a could target DENV2 at the predicated NS1 sequence and suppress DENV2 replication demonstrated by luciferase-reporter activity, RT-PCR, real-time PCR, Western blotting and plaque assay. ICR-suckling mice consumed honeysuckle aqueous extract either before or after intracranial injection with DENV2 showed decreased levels of NS1 RNA and protein expression accompanied with alleviated disease symptoms, decreased virus load, and prolonged survival time. Similar results were observed when DENV2infected mice were intracranially injected with let-7a. Conclusion: We reveal that honeysuckle attenuates DENY replication and related pathogenesis in vivo through induction of let-7a expression. This study opens a new direction for prevention and treatment of DENY infection through induction of the innate miRNA let-7a by honeysuckle.
Nonlocal electrodynamics in Weyl semimetals
(2017-02-28)
Rosenstein, B.
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Kao, H. C.
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Lewkowicz, M.
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電子物理學系
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Department of Electrophysics
Recently synthesized three-dimensional materials with Dirac spectrum exhibit peculiar electric transport qualitatively different from its two-dimensional analog, graphene. By neglecting impurity scattering, the real part of the conductivity is strongly frequency dependent, while the imaginary part is nonzero unlike in undoped, clean graphene. The Coulomb interaction between electrons is unscreened as in a dielectric and hence is long range. We demonstrate that the interaction correction renders the electrodynamics nonlocal on a mesoscopic scale. The longitudinal conductivity sigma(L) and the transverse conductivity sigma(T) are different in the long-wavelength limit and consequently the standard local Ohm's law description does not apply. This leads to several remarkable effects in optical response. The p-polarized light generates in these materials bulk plasmons as well as the transversal waves. At a specific frequency the two modes coincide, a phenomenon impossible in a local medium. For any frequency there is a Brewster angle where total absorption occurs, turning the Weyl semimetals opaque. The effect of the surface, including the Fermi arcs, is discussed.
Time periodic saturated flow boiling heat transfer of R-134a in a narrow annular duct due to heat flux oscillation
(2017-03)
Chen, C. A.
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Lin, T. F.
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Yan, Wei-Mon
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機械工程學系
;
Department of Mechanical Engineering
The time periodic saturated boiling heat transfer in a horizontal annulus was investigated experimentally where the walls are under an oscillating heat flux. The fluid enters the duct with zero vapor quality (saturated liquid state). The amplitude of the imposed heat flux oscillation Delta q varies from 0% to 50% of mean imposed heat flux (q) over bar and four different periods of heat flux oscillation t(p) including 20, 30, 60 and 120 s are applied to the system. The measured data display that when the applied heat flux is close to that for the onset of stable flow boiling, intermittent flow boiling appears in which nucleate boiling on the heated surface only exists in a partial interval of each periodic cycle and the heat flux oscillation does not noticeably affect the time-average boiling curves and heat transfer coefficients. Besides, the heated wall temperature and evaporating flow pattern are found to oscillate periodically in time as well and at the same frequency as the imposed heat flux oscillation. Furthermore, in the persistent boiling the resulting oscillation amplitudes of the heated surface temperature, heat transfer coefficient gets larger for a longer period and larger amplitude of the imposed heat flux oscillation and for a higher mean imposed heat flux. The substantial time lag in the heated surface temperature oscillation is observed. In the first half of the periodic cycle in which the heat flux reduces with time, after the time lag the heated wall temperature decreases with time. The inverse processes occur in the second half of the cycle in which imposed heat flux increases with time. Finally, flow regime maps are provided to explain the boundaries separating different boiling regimes for the R-134a saturated boiling in the duct. (C) 2016 Elsevier Ltd. All rights reserved.