Browsing by Issue Date, starting with "2017-06-01"

Now showing 1 - 20 of 13809

Unveiling the influence of inner spacer length of the non-linear S-shaped chiral oligomers on liquid crystalline phase
(2017-06-01)
Yeap, Guan-Yeow
;
Osman, Faridah
;
Maeta, Nobuyuki
;
Ito, Masato M.
;
Lin, Chien-Min
A series of S-shaped liquid crystal oligomers consisting of biphenylene, catechol and cholesterol moieties have been synthesized and characterized. The members in this series differ by the length of inner spacers -(CH2)(n)-where n are varied from 4 to 9 whereas the outer spacer of undecanoate chain is remained intact. The texture and phase transition temperatures with associated enthalpy changes are recorded. Increase in the number of carbon atom at the inner spacer affects the stability of liquid crystalline phase. The homologues with shorter inner spacers n = 4 and 5 exhibit monotropic N* whilst the analogue with medium spacer n = 6 exhibits monotropic N* and SmC* phase. However, the oligomers with longer spacers n = 7, 8 and 9 exhibit enantiotropic N* and SmC* phase. The I -N* transition temperatures were found to depend on the parity of the inner spacers. An Xray diffraction study reveals that the S-shaped oligomers exist as a monolayer chiral smectic C phase. (C) 2017 Elsevier B.V. All rights reserved.
Photothermal imaging of skeletal muscle mitochondria
(2017-06-01)
Tomimatsu, Toru
;
Miyazaki, Jun
;
Kano, Yutaka
;
Kobayashi, Takayoshi
;
電子物理學系
The morphology and topology of mitochondria provide useful information about the physiological function of skeletal muscle. Previous studies of skeletal muscle mitochondria are based on observation with transmission, scanning electron microscopy or fluorescence microscopy. In contrast, photothermal (PT) microscopy has advantages over the above commonly used microscopic techniques because of no requirement for complex sample preparation by fixation or fluorescent-dye staining. Here, we employed the PT technique using a simple diode laser to visualize skeletal muscle mitochondria in unstained and stained tissues. The fine mitochondrial network structures in muscle fibers could be imaged with the PT imaging system, even in unstained tissues. PT imaging of tissues stained with toluidine blue revealed the structures of subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria and the swelling behavior of mitochondria in damaged muscle fibers with sufficient image quality. PT image analyses based on fast Fourier transform (FFT) and Grey-level co-occurrence matrix (GLCM) were performed to derive the characteristic size of mitochondria and to discriminate the image patterns of normal and damaged fibers. (C) 2017 Optical Society of America
The study of wet etching on GaN surface by potassium hydroxide solution
(2017-06-01)
Lai, Yung-Yu
;
Hsu, Shih-Chieh
;
Chang, Hua-Sheng
;
Wu, YewChung Sermon
;
Chen, Ching-Hsiang
Potassium hydroxide solution was used to etch un-doped GaN grown on the sapphire substrate at 180 and 260 A degrees C. We illustrated the etching phenomenon in detail and probed its mechanism in the wet etching process. By multiplying the planar density and the number of dangling bonds on the N atom, we proposed the etching barrier index (EBI) to describe the difficulty degree of each lattice facet. The raking of EBI will be +c-plane > a-plane > m-plane > -c-plane > (10-1-1) plane > r-plane. Combining the EBI with SEM results, we thoroughly studied the whole etching process. We confirmed that in our research, KOH wet etching on GaN starts from the r-plane instead of the +c-plane or -c-plane, which differs from other studies. We also found that during the high-temperature etching process, there are two etching approaches. In one, the etching begins vertically from the top to the bottom, then horizontally, and finally reversely from the bottom to the top. In the other, etching pits will develop into a hexagonal hole of the sidewall of m-plane.
Randomized, Multicenter Trial of ARTSS-2 (Argatroban With Recombinant Tissue Plasminogen Activator for Acute Stroke)
(2017-06-01)
Barreto, Andrew D.
;
Ford, Gary A.
;
Shen, Loren
;
Pedroza, Claudia
;
Tyson, Jon
Background and Purpose-We conducted a randomized exploratory study to assess safety and the probability of a favorable outcome with adjunctive argatroban, a direct thrombin-inhibitor, administered to recombinant tissue-type plasminogen activator (r-tPA)-treated ischemic stroke patients. Methods-Patients treated with standard-dose r-tPA, not receiving endovascular therapy, were randomized to receive no argatroban or argatroban (100 mu g/kg bolus) followed by infusion of either 1 (low dose) or 3 mu g/kg per minute (high dose) for 48 hours. Safety was incidence of symptomatic intracerebral hemorrhage. Probability of clinical benefit (modified Rankin Scale score 0-1 at 90 days) was estimated using a conservative Bayesian Poisson model (neutral prior probability centered at relative risk, 1.0 and 95% prior intervals, 0.33-3.0). Results-Ninety patients were randomized: 29 to r-tPA alone, 30 to r-tPA+low-dose argatroban, and 31 to r-tPA+high-dose argatroban. Rates of symptomatic intracerebral hemorrhage were similar among control, low-dose, and high-dose arms: 3/29 (10%), 4/30 (13%), and 2/31 (7%), respectively. At 90 days, 6 (21%) r-tPA alone, 9 (30%) low-dose, and 10 (32%) high-dose patients were with modified Rankin Scale score 0 to 1. The relative risks (95% credible interval) for modified Rankin Scale score 0 to 1 with low, high, and either low or high dose argatroban were 1.17 (0.57-2.37), 1.27 (0.63-2.53), and 1.34 (0.68-2.76), respectively. The probability that adjunctive argatroban was superior to r-tPA alone was 67%, 74%, and 79% for low, high, and low or high dose, respectively. Conclusions-In patients treated with r-tPA, adjunctive argatroban was not associated with increased risk of symptomatic intracerebral hemorrhage and provides evidence that a definitive effectiveness trial is indicated.
Fabrication of hydrothermally reduced graphene oxide/chitosan composite membranes with a lamellar structure on methanol dehydration
(2017-06-01)
Hung, Wei-Song
;
Chang, Sue-Mm
;
Lecaros, Rumwald Leo G.
;
Ji, Yan-Li
;
An, Quan-Fu
Reduced graphene oxide (rGO) has been prepared through hydrothermal reduction, an environmentally safe reduction of graphene oxide (GO). rGO is used to fabricate a highly compatible and orderly stacked lamellar structure of composite membranes with chitosan (CS). This method also facilitates a continuous large-scale fabrication of membranes. Conventionally, GO and CS are the preferred compounds for this type of fabrication because of their hydrophilic nature. Nevertheless, when they are mixed together, the occurrence of ionic complexation (-COO-H3+N-R) between the negatively charged carboxylate ions of GO and the positively charged protonated amines of CS create extreme membrane aggregation. Hydrothermal reduction is useful for preventing undesired ionic complexation from mixing rGO and CS because it can remove most carboxylate ions from GO. Consequently, the hydrophilic CS molecular chain is inserted in between the rGO laminates, improving the dispersion and enabling the rGO/CS to stack-up and self-assemble into a lamellar structure. Furthermore, excellent methanol dehydration can be observed through pervaporation, which is attributed to the selective water channels formed in the rGO laminates. (C) 2017 Elsevier Ltd. All rights reserved.
Compact coupling scheme to achieve the synchronously dual self-mode-locked operation with a 35.2 THz optical beating
(2017-06-01)
Cheng, Hao Ping
;
Huang, Tzu Lin
;
Sung, Cheng Lin
;
Cho, Chun Yu
;
Liang, Hsing Chih
A synchronously dual self-mode-locked (SML) operation at 946 and 1064 nm is experimentally accomplished by using a compact coupling scheme to obtain the optical beating frequency up to 35.2 THz. The SML emissions at 946 and 1064 nm are established by a monolithic Nd:YAG cavity and a Nd: YVO4 crystal in a flat-flat cavity, respectively. Two gain media are butt adjoined to be longitudinally pumped by a single laser diode. The monolithic Nd: YAG crystal is used not only as the 946 nm laser cavity, but also as the output coupler of the Nd: YVO4 1064 nm laser. More importantly, the output surface of the monolithic Nd: YAG laser is coated to generate the optical feedback for the synchronization of the dual SML operation. At a pump power of 10.7 W, the output powers at 1064 and 946 nm can simultaneously reach 1.5 W by controlling the focal position of the pump waist. (C) 2017 Optical Society of America
NON-EQUIVALENCE OF SPECIFIC AND AD VALOREM TAXATION IN THE COMPETITIVE MARKET WITH TAX EVASION
(2017-06-01)
Huang, Che-Chiang
;
Ueng, K. L. Glen
;
Hu, Jin-Li
;
經營管理研究所
;
Institute of Business and Management
The well-known equivalence between specific and ad valorem taxation in competitive markets may not hold in the presence of tax evasion. Evading specific taxes has to take place via concealing quantities sold, whereas evading ad valorem taxes can take place via concealing selling prices as well as quantities sold. We show that in the competitive market (i) this difference could make the equivalence of these two taxes break down, and (ii) specific taxation may be superior to ad valorem taxation if it causes firms to channel fewer resources into tax evasion, given other things being equal.
Recovery of failed resistive switching random access memory devices by a low-temperature supercritical treatment
(2017-06-01)
Du, Xiaoqin
;
Wu, Xiaojing
;
Chang, Ting-Chang
;
Chang, Kuan-Chang
;
Pan, Chih-Hung
The successful recovery of resistive switching random access memory (RRAM) devices that have undergone switching failure is achieved by introducing a low-temperature supercritical-fluid process that passivates the switching layer. These failed RRAM devices, which are incapable of switching between high-and low-resistance states, were treated with supercritical carbon dioxide with pure water at 120 degrees C for 1 h. After the treatment, the devices became operational again and showed excellent current-voltage (I-V) characteristics and reliability as before. On the basis of the current conduction mechanism fitting results, we propose a model to explain the phenomenon. (C) 2017 The Japan Society of Applied Physics
Dimension dependent immunity of X-ray irradiation on low-temperature polycrystalline-silicon TFTs
(2017-06-01)
Wei, Yin-Chang
;
Li, Yi-Chieh
;
Lee, I-Che
;
Cheng, Huang-Chung
;
電子工程學系及電子研究所
Typically, each element in a large-area flat-panel X-ray image sensor consists of a photodetector and amorphous silicon (a-Si) thin-film transistor (TFT) switches. In order to reduce noise, increase sensor dynamic range, and increase carrying capacity, the low-temperature polycrystalline-silicon (LTPS) TFTs have been proposed as a candidate to replace the a-Si TFTs. However, there are concerns regarding the impact of X-ray radiation in LTPS-TFTs, and several studies have been conducted to inquire into the same. In this paper, we show that LTPS TFTs with small channel length (<2 mu m) are almost immune to X-ray radiation. (C) 2017 The Japan Society of Applied Physics
Characterization of LOCOS Field Oxide on 4H-SiC Formed by Ar Preamorphization Ion Implantation
(2017-06-01)
Tseng, Yuan-Hung
;
Lin, Chung-Yu
;
Tsui, Bing-Yue
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, the electrical properties of local oxidation of silicon (LOCOS) field oxide formed on 4H-SiC are reported. Moreover, unlike the conventional Si LOCOS process, a simpler method based on Ar preamorphization implantation is proposed. In addition to direct characterization of the field oxide, device properties achieved using LOCOS isolation are compared with those achieved using the conventional chemical vapor deposition oxide isolation to clarify the impact of isolation technology. The results of this letterwould be insightful for silicon-carbide-basedvery-large-scale integration technology.
Enhanced Light Extraction of High-Voltage Light Emitting Diodes Using a Sidewall Chamfer Structure
(2017-06-01)
Wu, Ping-Chen
;
Ou, Sin-Liang
;
Horng, Ray-Hua
;
Wuu, Dong-Sing
;
電子工程學系及電子研究所
High-voltage light-emitting diodes (HV-LEDs) were prepared with 4 x 2 microcells. A novel technique for enhancing the light extraction of HV-LEDs by using wet-etched chamfer structures in the sidewalls of each cell is proposed. The thicknesses of the u-GaN layers used were in the range of 3-7 mu m. Simulations revealed that the light extraction of the HV-LEDs with chamfer structures would be enhanced by increasing the u-GaN thickness. The output power (@ 80 mA) of the HV-LEDs without chamfer structures was 538.0-539.1 mW. However, the output powers (@ 80 mA) of the HV-LEDs with chamfer structures and u-GaN thicknesses of 3, 5, and 7 mu m were increased to 555.3, 573.1, and 561.6 mW, respectively. The 7 mu m thick u-GaN layer led to an extremely large thickness of the HV-LED epitaxial structure, which caused difficulties during the wet etching process. Because of the apparent decrease in the wet etching rate of GaN, the damages to the epitaxial structures of the HV-LED with the 7 mu m thick u-GaN was more obvious. Therefore, the device's light extraction was slightly reduced. The results confirm that chamfer structures are highly useful for improving the performance of HV-LEDs, especially for the u-GaN thickness of 5 mu m.
My Experiences of Learning at NYMU
(國立陽明大學, 2017-06)
Dlamini Lindiwe Felicity
Geocenter motion estimated from GRACE orbits: The impact of F10.7 solar flux
(2017-06-01)
Tseng, Tzu-Pang
;
Hwang, Cheinway
;
Sosnica, Krzysztof
;
Kuo, Chung-Yen
;
Liu, Ya-Chi
We assess the impact of orbit modeling on the origin offsets between GRACE kinematic and reduced-dynamic orbits. The origin of the kinematic orbit is the center of IGS network (CN), whereas the origin of the reduced-dynamic orbit is assumed to be the center of mass of the Earth (CM). Theoretically, the origin offset between these two orbits is associated with the geocenter motion. However, the dynamic property of the reduced-dynamic orbit is highly related to orbit parameterizations. The assessment of the F10.7 impact on the geocenter motion is implemented by using different orbit parameterization setups in the reduced-dynamic method. We generate two types of reduced-dynamic orbits using 15 and 240 empirical parameters per day from 2005 to 2012. The empirical parameter used in Bernese GNSS Software is called piece-wise constant empirical acceleration (PCA) and is mainly to absorb the non-gravitational forces mostly related to the atmospheric drag and solar radiation pressure. The differences between kinematic and dynamic orbits can serve as a measurement for geocenter. The RMS value of the geocenter measurement in the 15-PCA case is approximately 3.5 cm and approximately 2 cm in the 240-PCA case. The correlation between the orbit difference and F10.7 is about 0.90 in the 15-PCA case and -0.10 to 0 in the 240-PCA case. This implies that the reduced-dynamic orbit modeled with 240 PCAs absorbs the F10.7 variation, which aliases to the 15-PCA orbit solution. The annual amplitudes of the geocenter motion are 3.1, 3.1 and 2.5 mm in the 15-PCA case, compared to 0.9, 2.0 and 1.3 mm in the 240-PCA case in the X, Y and Z components, respectively. The 15-PCA solution is thus closer to the geocenter motions derived from other space-geodetic techniques. The proposed method is limited to the parameterizations in the reduced-dynamic approach. (C) 2016 COSPAR. Published by Elsevier Ltd. All rights reserved.
Time-Gated Imaging on Live Cancer Cells Using Silicon Quantum Dot Nanoparticles with Long-Lived Fluorescence
(2017-06-01)
Tu, Chang-Ching
;
Awasthi, Kamlesh
;
Chen, Kuang-Po
;
Lin, Chih-Hsiang
;
Hamada, Morihiko
In this work we demonstrate time-gated confocal fluorescence imaging on live cancer cells immunostained by antibody-conjugated silicon quantum dot nano particles (SiQD-NPs) and organic dyes, for simultaneous detection of two biological targets and removal of background autofluorescence. With almost all radiative recombinations occurring through oxide-related defect states located on the SiQD surface, the SiQD-NPs have very long photoluminescence lifetimes of about 25 its, in contrast to the nanosecond range lifetimes of other commonly used biological fluorophores. This drastic lifetime difference enables a time-gated imaging method here, in which the time-resolved photon distribution of each pixel of a fluorescence image is measured by using a time-correlated single-photon counting technique. Then, by integrating the photon histogram of each pixel over respective time windows, the long-lived component of the fluorescence image comprising only the fluorescence emitted from the SiQD-NPs is separated from all other short-lived signals resulting from the organic dyes and the cell endogenous luminescence. For instance, the membrane and nucleus of a single cancer cell or two types of cancer cells, immunostained with the SiQD-NPs and the organic dyes, respectively, can be clearly distinguished from each other by time-gating, which otherwise cannot be accomplished by conventional multiplexing due to spectral overlap in the wavelength domain.
Web Application Security: Threats, Countermeasures, and Pitfalls
(2017-06-01)
Huang, Hsiu-Chuan
;
Zhang, Zhi-Kai
;
Cheng, Hao-Wen
;
Shieh, Shiuhpyng Winston
;
交大名義發表
Penetration testing is a crucial defense against common web application security threats such as SQL injection and cross-site scripting attacks. A proposed web vulnerability scanner automatically generates test data with combinative evasion techniques, significantly expanding test coverage and revealing more vulnerabilities.
Solution for Soil Vapor Extraction from a Pressure-Controlled Well
(2017-06-01)
Kuo, Ching-Lin
;
Fen, Chiu-Shia
;
Chen, Kai-Hsin
;
Yeh, Hund-Der
;
環境工程研究所
This paper presents a new solution for a soil venting problem, in which a vertical, partially penetrating well is operated at a fixed pressure under covered, uncovered, or leaking ground surface conditions. The method of domain decomposition is applied to solve the problem of a mixed-type boundary condition imposed along a well screen, which in previous solutions was usually handled by discretization of the screen. The new solution is also capable of predicting the flow field beneath the well bottom, which is commonly neglected by other solutions. The authors found that the present solution may predict different pressure distributions from those given by a solution employing a constant flux rate at a well screen. The radius of influence for soil vapor extraction (SVE) operations is strongly affected by the radial permeability, the vertical permeability, and the ratio between the two. Vacuum pressure values were predicted with the proposed solution and compared against measurements at different observation wells and depths under venting tests at a former SVE-operated site. The measured vacuum pressure and gas flow velocity values around the wells were found to be substantially lower than the predicted values. Thus, the wellbore soils of the site were suspected to be positive skin zones. (C) 2017 American Society of Civil Engineers.
Effectiveness and Relay Efficiency of Opportunistic Multipoint Relaying on Cooperative ARQ
(2017-06-01)
Wu, Sau-Hsuan
;
Chiu, Hsin-Li
;
Li, Jin-Hao
;
電信工程研究所
;
Institute of Communications Engineering
This paper studies the effectiveness and relay efficiency of using opportunistic multipoint relaying and distributed space-time coding (ODSTC) for cooperative Automatic Repeat reQuest (ARQ). According to the complexities for diversity exploration in retransmissions, three types of ARQ protocols are studied herein, allowing us to examine the effectiveness of the protocols and the efficiencies of using ODSTC relaying for ARQ. The efficiency is studied from the viewpoint of the signal quality enhancement per active relay, while the effectiveness is investigated from the perspectives of diversity and throughput improvements with the different protocols. The results show that both are closely related to the link qualities of the forwarding channels. When the link quality between the source and relays is considerably higher than the quality between the relays and the destination, a simple protocol that opportunistically chooses two active relays for ODSTC (ODSTC2) at the beginning of retransmissions is good enough to yield a significant throughput improvement. Otherwise, when the performance is limited by the number of successfully decoding relays, then having relays of unsuccessful decoding to overhear the signals sent by active relays plays a crucial role in resolving the limitation. By having the new successfully decoding relays to participate in the subsequent retransmissions, both diversity and throughput can be significantly improved. According to our analysis and simulation studies, an appropriate protocol with ODSTC2 in general can provide effective throughput improvements in two times retransmissions.
DNN-Driven Mixture of PLDA for Robust Speaker Verification
(2017-06-01)
Li, Na
;
Mak, Man-Wai
;
Chien, Jen-Tzung
;
電機工程學系
;
Department of Electrical and Computer Engineering
The mismatch between enrollment and test utterances due to different types of variabilities is a great challenge in speaker verification. Based on the observation that the SNR-level variability or channel-type variability causes heterogeneous clusters in i-vector space, this paper proposes to apply supervised learning to drive or guide the learning of probabilistic linear discriminant analysis (PLDA) mixture models. Specifically, a deep neural network (DNN) is trained to produce the posterior probabilities of different SNR levels or channel types given i-vectors as input. These posteriors then replace the posterior probabilities of indicator variables in the mixture of PLDA. The discriminative training causes the mixture model to perform more reasonable soft divisions of the i-vector space as compared to the conventional mixture of PLDA. During verification, given a test i-vector and a target-speaker's i-vector, the marginal likelihood for the same-speaker hypothesis is obtained by summing the component likelihoods weighted by the component posteriors produced by the DNN, and likewise for the different-speaker hypothesis. Results based on NIST 2012 SRE demonstrate that the proposed scheme leads to better performance under more realistic situations where both training and test utterances cover a wide range of SNRs and different channel types. Unlike the previous SNR-dependent mixture of PLDA which only focuses on SNR mismatch, the proposed model is more general and is potentially applicable to addressing different types of variability in speech.
Cost-Effective Time-to-Digital Converter Using Time-Residue Feedback
(2017-06-01)
Lai, Jung-Chin
;
Hsu, Terng-Yin
;
資訊工程學系
;
Department of Computer Science
This paper proposes a time-residue feedback scheme to balance resolution and complexity in a cell-based time-to-digital converter (TDC). The time residue is amplified and fed back into a cyclic-ring Vernier recursively until it cannot be detected correctly. Only one variable-resolution cyclic-ring Vernier and one tunable delay-chain time amplifier (TA) are adopted. Both coarse and fine oscillators of the proposed Vernier which are designed by the same variable-resolution digital controlled oscillator can be switched off to decrease ground bounce during TA activities. With various control codes, the TDC resolution is also programmable. The test application-specified integrated circuit which has a 13-b resolution and occupies 0.02 mm(2) in TSMC 65-nm CMOS process can operate in either feedback or feedforward mode. In feedback mode, the measurements of sampling rate, resolution, input range, differential nonlinearity, and integral nonlinearity are 10 MHz, 0.98 ps, 5.76 ns, +/- 0.8 LSB, and +/- 2.2 LSB, respectively; it also consumes 3 mW at 1 V supply voltage. The sampling rate, resolution, and power dissipation of the feedforward operation are 250 MHz, 6.01 ps, and 17.5 mW, respectively.
A Fully Integrated Wireless SoC for Motor Function Recovery After Spinal Cord Injury
(2017-06-01)
Lo, Yi-Kai
;
Kuan, Yen-Cheng
;
Culaclii, Stanislav
;
Kim, Brian
;
Wang, Po-Min
This paper presents a wirelessly powered, fully integrated system-on-a-chip (SoC) supporting 160-channel stimulation, 16-channel recording, and 48-channel bio-impedance characterization to enable partialmotor function recovery through epidural spinal cord electrical stimulation. A wireless transceiver is designed to support quasi full-duplex data telemetry at a data rate of 2 Mb/s. Furthermore, a unique in situ bio-impedance characterization scheme based on time-domain analysis is implemented to derive the Randles cell electrode model of the electrode-electrolyte interface. The SoC supports concurrent stimulation and recording while the high-density stimulator array meets an output compliance voltage of up to +/- 10 V with versatile stimulus programmability. The SoC consumes 18 mW and occupies a chip area of 5.7 mm x 4.4 mm using 0.18 mu m high-voltage CMOS process. In our in vivo rodent experiment, the SoC is used to perform wireless recording of EMG responses while stimulation is applied to enable the standing and stepping of a paralyzed rat. To facilitate the system integration, a novel thin film polymer packaging technique is developed to provide a heterogeneous integration of the SoC, coils, discrete components, and high-density flexible electrode array, resulting in a miniaturized prototype implant with a weight and form factor of 0.7 g and 0.5 cm(3), respectively.