Browsing by Issue Date, starting with "2020-02-18"

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High Performance All Nonmetal SiNx Resistive Random Access Memory with Strong Process Dependence
(2020-02-18)
Yen, Te Jui
;
Chin, Albert
;
Gritsenko, Vladimir
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
All-nonmetal resistive random access memory (RRAM) with a N+-Si/SiNx/P+-Si structure was investigated in this study. The device performance of SiNx developed using physical vapor deposition (PVD) was significantly better than that of a device fabricated using plasma-enhanced chemical vapor deposition (PECVD). The SiNx RRAM device developed using PVD has a large resistance window that is larger than 10(4) and exhibits good endurance to 10(5) cycles under switching pulses of 1 mu s and a retention time of 10(4) s at 85 degrees C. Moreover, the SiNx RRAM device developed using PVD had tighter device-to-device distribution of set and reset voltages than those developed using PECVD. Such tight distribution is crucial to realise a large-size cross-point array and integrate with complementary metal-oxide-semiconductor technology to realise electronic neurons. The high performance of the SiNx RRAM device developed using PVD is attributed to the abundant defects in the PVD dielectric that was supported by the analysed conduction mechanisms obtained from the measured current-voltage characteristics.
Covariant Bethe-Salpeter approximation in models of strongly correlated electron systems
(2020-02-20)
Fan, Zhenhao
;
Sun, Zhipeng
;
Li, Dingping
;
Berenstein, Itzhak
;
Leshem, Guy
Strongly correlated electron systems are generally described by tight-binding lattice Hamiltonians with strong local (onsite) interactions, the most popular being the Hubbard model. Although the half-filled Hubbard model can be simulated by Monte Carlo (MC), physically more interesting cases beyond half-filling are plagued by the sign problem. One therefore should resort to other methods. It was demonstrated recently that a systematic truncation of the set of Dyson-Schwinger equations for correlators of the Hubbard, supplemented by a "covariant" calculation of correlators leads to a convergent series of approximants. The covariance preserves all the Ward identities among correlators describing various condensed matter probes. While first-order (classical), second-order (Hartree-Fock or Gaussian), and third-order (Cubic) covariant approximation were worked out, the fourth-order (quartic) seems too complicated to be effectively calculable in fermionic systems. It turns out that the complexity of the quartic calculation in local interaction models,is manageable computationally. The quartic (Bethe-Salpeter-type) approximation is especially important in 1D and 2D models in which the symmetry-broken state does not exists (the Mermin-Wagner theorem), although strong fluctuations dominate the physics at strong coupling. Unlike the lower-order approximations, it respects the Mermin-Wagner theorem. The scheme is tested and exemplified on the single-band 1D and 2D Hubbard model.
Electronic State and Photophysics of 2-Ethylhexyl-4-methoxycinnamate as UV-B Sunscreen under Jet-Cooled Condition
(2020-02-20)
Muramatsu, Satoru
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Nakayama, Shingo
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Kinoshita, Shin-nosuke
;
Onitsuka, Yuuki
;
Kohguchi, Hiroshi
The title compound, 2-ethylhexyl-4-methoxycinnamate (2EH4MC), is known as a typical ingredient of sunscreen cosmetics that effectively converts the absorbed UV-B light to thermal energy. This energy conversion process includes the nonradiative decay (NRD): trans-cis isomerization and finally going back to the original structure with a release of thermal energy. In this study, we performed UV spectroscopy for jet-cooled 2EH4MC to investigate the electronic/geometrical structures as well as the NRD mechanism. Laser-induced-fluorescence (LIF) spectroscopy gave the well-resolved vibronic structure of the S-1-S-0 transition; UV-UV hole-burning (HE) spectroscopy and density functional theory (DFT) calculations revealed the presence of syn and anti isomers, where the methoxy (-OCH3) groups orient in opposite directions to each other. Picosecond UV-UV pump-probe spectroscopy revealed the NRD process from the excited singlet (S-1((1)pi pi*)) state occurs at a rate constant of similar to 10(10)-10(11) s(-1), attributed to internal conversion (IC) to the (1)n pi* state. Nanosecond UV-deep UV (DUV) pumpprobe spectroscopy identified a transient triplet (T-1 ((3)pi pi*)) state, whose energy (from S-0) and lifetime are 18 400 cm(-1) and 20 ns, respectively. These results demonstrate that the photoisomerization of 2EH4MC includes multistep internal conversions and intersystem crossings, described as "S-1 (trans, (1)pi pi*) -> (1)n pi* -> T-1 ((3)pi pi* -> S-0 (cis)".
Ventricular divergence correlates with epicardial wavebreaks and predicts ventricular arrhythmia in isolated rabbit hearts during therapeutic hypothermia
(2020-02-21)
Hsieh, Yu-Cheng
;
Hsieh, Wan-Hsin
;
Li, Cheng-Hung
;
Liao, Ying-Chieh
;
Lin, Jiunn-Cherng
Introduction High beat-to-beat morphological variation (divergence) on the ventricular electrogram during programmed ventricular stimulation (PVS) is associated with increased risk of ventricular fibrillation (VF), with unclear mechanisms. We hypothesized that ventricular divergence is associated with epicardial wavebreaks during PVS, and that it predicts VF occurrence. Method and results Langendorff-perfused rabbit hearts (n = 10) underwent 30-min therapeutic hypothermia (TH, 30 degrees C), followed by a 20-min treatment with rotigaptide (300 nM), a gap junction modifier. VF inducibility was tested using burst ventricular pacing at the shortest pacing cycle length achieving 1:1 ventricular capture. Pseudo-ECG (p-ECG) and epicardial activation maps were simultaneously recorded for divergence and wavebreaks analysis, respectively. A total of 112 optical and p-ECG recordings (62 at TH, 50 at TH treated with rotigaptide) were analyzed. Adding rotigaptide reduced ventricular divergence, from 0.13 +/- 0.10 at TH to 0.09 +/- 0.07 (p = 0.018). Similarly, rotigaptide reduced the number of epicardial wavebreaks, from 0.59 +/- 0.73 at TH to 0.30 +/- 0.49 (p = 0.036). VF inducibility decreased, from 48 +/- 31% at TH to 22 +/- 32% after rotigaptide infusion (p = 0.032). Linear regression models showed that ventricular divergence correlated with epicardial wavebreaks during TH (p<0.001). Conclusion Ventricular divergence correlated with, and might be predictive of epicardial wavebreaks during PVS at TH. Rotigaptide decreased both the ventricular divergence and epicardial wavebreaks, and reduced the probability of pacing-induced VF during TH.
Antifouling strategies in advanced electrochemical sensors and biosensors
(2020-02-21)
Lin, Pei-Heng
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Li, Bor-Ran
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交大名義發表
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National Chiao Tung University
Electrochemical biosensors have been applied in a broad range of clinical applications for pathogen biomarker detection and medical applications and diagnosis due to the sensitivity of electrochemical methods and the bioselectivity of the components. The complexity of clinical conditions with various biofoulants (proteins, cells, polysaccharides and lipids) severely influences the reliability and stability of sensors for direct detection or immersion under changing conditions. Therefore, designing an antifouling sensing platform that can effectively reduce undesired binding to maintain biosensor performance in optimized analysis is necessary. For this purpose, the fundamental mechanisms of fouling materials and commonly used biocompatible antifouling components have been discussed, and the relevant effective modification strategies are introduced in this review. Recent advances in these strategies are demonstrated in examples with analysis of essential modification methods for reliable sensing in non-specific binding solutions or complex biofluids. The challenges and future perspectives of modification strategies for current clinical application are also discussed in this review.
Spatiotemporal integration of visual stimuli and its relevance to the use of a divisional power supply scheme for retinal prosthesis
(2020-02-21)
Tsai, Yueh-Chun
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Wu, Jose Jiun-Shian
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Lin, Po-Kang
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Lin, Bo-Jyun
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Wang, Pin-Shiou
A wireless photovoltaic retinal prosthesis is currently being studied with the aim of providing prosthetic vision to patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The major challenge of a photovoltaic device is its limited power efficiency. Our retinal prosthetic design implements a unique divisional power supply scheme (DPSS) system that provides the electrical power generated by all of the solar cells to only a subset of electrodes at any moment in time. The aim of the present study was to systematically characterize the spatiotemporal integration performance of the system under various DPSS conditions using human subjects and a psychophysical approach. A 16x16 pixels LED array controlled by Arduino was used to simulate the output signal of the DPSS design, and human performance under different visual stimulations at various update frequencies was then used to assess the spatiotemporal capability of retinal prostheses. The results showed that the contrast polarity of the image, image brightness, and division number influenced the lower limit of the update frequency of the DPSS system, while, on the other hand, visual angle, ambient light level, and stimulation order did not affect performance significantly. Pattern recognition by visual persistence with spatiotemporal integration of multiple frames of sparse dots is a feasible approach in retinal prosthesis design. These findings provide an insight into how to optimize a photovoltaic retinal prosthesis using a DPSS design with an appropriate update frequency for reliable pattern recognition. This will help the development of a wireless device able to restore vision to RP and AMD patients in the future.
Numerical investigation of thermal and hydraulic performance of shell and plate heat exchanger
(2020-02-25)
Abbas, Ali
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Lee, Howard
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Sengupta, Mash
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Wang, Chi-Chuan
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機械工程學系
Detailed single-phase performance of the shell and plate heat exchangers is presented in this study with corresponding chevron angles (beta) of 45 degrees and 75 degrees, respectively. Unlike those conventional plate heat exchanger, the thermofluids characteristics perform quite differently between shell and inner channel. For a larger chevron angle (75 degrees), the friction factor is comparable amid shell and inner channel. Yet the friction factor in the shell channel is much lower than that in inner channel at a smaller chevron angle (45 degrees). The shell channel contains more unidirectional flow pattern while some flow re-circulation may occur at the entrance/exit port of the inner channel. The flow pattern and temperature distribution in the shell channel are generally more uniform than those in inner channel. The shell channel with beta = 45 degrees shows a better overall performance for its much lower friction factor when the Reynolds number is low. The heat transfer performance for shell channel exceeds the inner channel appreciably when the chevron angle is high (75 degrees). The heat transfer performance depends on the corrugation aspect ratio, and an optimum ratio is derived. For the inner channel, the optimum value is around 0.75 while it is 0.53 for the shell channel.
Improvement on dehumidifier performance using a plastic assisted condenser
(2020-02-25)
Chu, Wen-Xiao
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Chiu, Chuang-Hui
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Wang, Chi-Chuan
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機械工程學系
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Department of Mechanical Engineering
This paper proposed a new design concept for improving daily moisture removal rate and energy-efficiency factor of a dehumidifier. The plastic straws with diameters of 12 mm, 8.0 mm and 6.0 mm are inserted between the evaporator and condenser as an assisted condenser. A total of four cases are experimentally investigated, and the numerical analysis is conducted to further explain the performance improvement mechanism. Compared to the original dehumidifier, the assisted condenser with twelve straws having a diameter of 12 mm can pronouncedly improve the moisture removal rate of the dehumidifier by 6.9-9.2% and 1.2-6.4% at the standard condition and over-loading condition, respectively. By reducing the straw diameter to 8.0 mm, the improvement is reduced and the assisted condenser even reveal deteriorated effect at a high fan speed condition. Yet more pronounced degradation is seen when introducing 8.0 mm straws having two rows with staggered layout. It can be explained from numerical analysis that the pressure drop across the assisted condenser plays an important role. The optimum design depends on the balance between the main airflow, entrained airflow, and the flow resistance of the assisted condenser.
Redeveloping a global MOOC to be more locally relevant: design-based research
(2020-02-26)
Chen, Ken-Zen
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Oakley, Barbara
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教育研究所
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Institute of Education
This study demonstrated a globally and locally relevant MOOC design model. By redeveloping a culturally responsive MOOC based on the course "Learning How to Learn (LHTL)" on the Coursera, the researchers created a sister MOOC to meet the local needs of Chinese learners. In this three-year design-based research study, four major iterations were conducted: (1) to analyze and prototype culturally responsive course contents for Chinese MOOCs learners; (2 and 3) to redevelop, pilot, field-test, and improve the new MOOC; and (4) to develop research-supported instructional practice for continued growth. This research contributed to the study of MOOCs by providing a thorough understanding of the design principles of, and theoretical claims about, the development of a culturally responsive MOOC. We hope this effort will help underpin further studies involving culturally responsive and comparable sister courses to advance MOOC research.
Self-Powered, Self-Healed, and Shape-Adaptive Ultraviolet Photodetectors
(2020-02-26)
Tsai, Meng-Shian
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Shen, Tien-Lin
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Wu, Hsing-Mei
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Liao, Yu-Ming
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Liao, Yu-Kuang
The emergence of self-healing devices in recent years has drawn a great amount of attention in both academics and industry. Self-healed devices can autonomically restore a rupture as unexpected destruction occurs, which can efficiently prolong the life span of the devices; hence, they have an enhanced durability and decreased replacement cost. As a result, integration of wearable devices with self-healed electronics has become an indispensable issue in smart wearable devices. In this study, we present the first self-powered, self-healed, and wearable ultraviolet (UV) photodetector based on the integration of agarose/poly(vinyl alcohol) (PVA) double network (DN) hydrogels, which have the advantages of good mechanical strength, self-healing ability, and tolerability of multiple types of damage. With the integration of a DN hydrogel substrate, the photodetector enables 90% of the initial efficiency to be restored after five healing cycles, and each rapid healing time is suppressed to only 10 s. The proposed device has several merits, including having an all spray coating, self-sustainability, biocompatibility, good sensitivity, mechanical flexibility, and an outstanding healing ability, which are all essential to build smart electronic systems. The unprecedented self-healed photodetector expands the future scope of electronic skin design, and it also offers a new platform for the development of next-generation wearable electronics.
劉冠澤、陳彥儒同學分獲「醫學生暑期研究計畫」競賽亞軍、傑作
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
由健康科學文教基金會與國家衛生研究院合辦之「第14屆醫學系學生暑期研究計畫」，日前公布競賽結果，本校醫學系五年級劉冠澤同學...
大手牽小手，青幼社反毒宣導
(國立陽明大學, 2020-02-27)
陳念平
;
陽明電子報編輯小組
依稀記得一次與教官的談話中，被問了一句：「念平，聽說你們青幼社專門帶國小生，那願不願意一起去石牌國小宣導反毒教育？」「好啊！當然可以！」雖然這件事情有點突然，但我還是馬上答應了！能向國小生宣導極為重要的反毒教育，對我們青幼社的夥伴們來說，是一件好玩又有意義的活動！
【生技醫療創新創業講座】知己知彼的募資準備
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
【健康一體研究中心演講】
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
科技部「愛因斯坦培植計畫」，神研所郭曉縈研究員入選
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
本校神經科學研究所研究員郭曉縈博士，專注於大腦基底核的神經系統研究，研究成果豐碩，陸續發表於”Nature Neuroscience”、”FA...
台灣腫瘤分割挑戰賽，陽明醫學系團隊獲第二
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
本校醫學系五年級高家祥、郭宜欣與黃玠淳同學組成的「Very Good Tumor」團隊，參加「第二屆台灣腫瘤分割挑戰賽」，使用預訓練（pr...
我們在同個世界中，共享健康
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
沒有什麼事情能夠比今年武漢新型冠狀病毒（COVID-19）疫情更能夠說明「One World, One Health」這個理念。就像當年金恩博士說的一...
【防疫大作戰，全民動起來】～防疫知識英語口說大賽
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
激勵工作士氣，優秀行政人員獲表揚
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組
為激勵行政人員工作士氣，人事室於2月25日舉行「108年度優秀行政服務人員頒獎典禮」，表揚本年度「最佳服務獎」與「工作績優獎」...
【神研所40週年系列講座】
(國立陽明大學, 2020-02-27)
陽明電子報編輯小組