Browsing by Issue Date, starting with "2020-06-12"

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Oxidation-boosted charge trapping in ultra-sensitive van der Waals materials for artificial synaptic features
(2020-06-12)
Yang, Feng-Shou
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Li, Mengjiao
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Lee, Mu-Pai
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Ho, I-Ying
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Chen, Jiann-Yeu
Exploitation of the oxidation behaviour in an environmentally sensitive semiconductor is significant to modulate its electronic properties and develop unique applications. Here, we demonstrate a native oxidation-inspired InSe field-effect transistor as an artificial synapse in device level that benefits from the boosted charge trapping under ambient conditions. A thin InOx layer is confirmed under the InSe channel, which can serve as an effective charge trapping layer for information storage. The dynamic characteristic measurement is further performed to reveal the corresponding uniform charge trapping and releasing process, which coincides with its surface-effect-governed carrier fluctuations. As a result, the oxide-decorated InSe device exhibits nonvolatile memory characteristics with flexible programming/erasing operations. Furthermore, an InSe-based artificial synapse is implemented to emulate the essential synaptic functions. The pattern recognition capability of the designed artificial neural network is believed to provide an excellent paradigm for ultra-sensitive van der Waals materials to develop electric-modulated neuromorphic computation architectures. Developing efficient memory and artificial synaptic systems based on environmentally sensitive van der Waals materials remains a challenge. Here, the authors present a native oxidation-inspired InSe field-effect transistor that benefits from a boosted charge trapping behavior under ambient conditions.
Inhibiting autophagy potentiates the antitumor efficacy ofEuphorbia royleanafor canine mammary gland tumors
(2020-06-12)
Huang, Yu-Ya
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Chen, Chia-Hung
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Hsu, Chia-Hui
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Kuo, Tsun-Yung
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Liu, Cheng-Chi
Background Canine mammary gland tumors (cMGTs) are the most common neoplasms in intact female canines and viewed as a suitable model for studying human breast cancers.Euphorbia royleanahas been reported to have a variety of antitumor efficacies. We have prepared the crude extracts ofE. royleanain ethanol and hexane solvents to evaluate the anti-tumor effects for cMGT in vitro and in vivo. Results The results showed thatE. royleanacould inhibit cell proliferation and colony formation in cMGT cells. The suppression of tumor cell growth resulted from necrosis and cell cycle arrest. Moreover, autophagy appears to play a critical role inE. royleana-mediated cell death by triggering cell apoptosis. The in vivo results also revealed thatE. royleanatreatment could reduce the size of solid tumors while exhibiting low toxicity in cMGT-bearing nude mice. Conclusions The anti-tumor mechanisms ofE. royleanawere firstly verified to show it would cause autophagic cell death, apoptosis, and cell cycle arrest in canine mammary tumor cells. The in vitro and in vivo findings in the present study revealedE. royleanahas potential anticancer effects for the treatment of canine mammary gland tumors.
到底該不該換數位身分證
(2020-06-14)
詹庭瑄
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張筠婕
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Department of Communication and Technology
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傳播與科技學系
【資安戰的未爆彈】專題

你支持換發數位身分證嗎？是因為便利嗎？便利和資安是一體兩面的事情，當我們選擇整合身分證成為一張「一卡通」的晶片卡，資安問題也將不可小覷，甚至可能成為台灣資安的「阿基里斯腱」。
該如何面對高齡社會的衝擊
(2020-06-14)
王乃安
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Department of Communication and Technology
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傳播與科技學系
現在的你，有想過「老化」這件事嗎？有想過父母邁入老年後，你的日子會變得如何嗎？你知道政府有那些政策在保障老人生活的嗎？再深入一點思考，這些政策真的有幫助嗎？
茶葉新世代　台灣商用茶現況
(2020-06-14)
何雨潮
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Department of Communication and Technology
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傳播與科技學系
【茶葉新世代】專題

隨著手搖飲料的發展，商用茶的重要性逐漸增加。今年三月份茶葉改良場訂定了茶菁分級標準，用於提升茶葉交易秩序及提高台灣商用茶品質。
大專院校服務學習爭議
(2020-06-14)
高儷玲
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Department of Communication and Technology
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傳播與科技學系
服務學習自2007年被教育部推廣後，成為許多大專院校的必修課程。讓同學走出校外服務、回饋社會的同時，卻也引發一些爭議。2018年政大學生會提出連署，要求學校廢除服務學習零學分畢業門檻制度，也讓許多學校開始正式服務學習課程存在的問題。
總編輯的話
(2020-06-14)
許峰睿
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Department of Communication and Technology
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傳播與科技學系
本期為喀報342期，總共有4篇報導。其中有2篇社會議題，1則影音新聞，1則資訊圖表。本期頭題為詹庭瑄的《到底該不該換數位身分證》，題材新穎，有訪問到專家且貼近時事。本期其他篇文章及資訊圖表內容也都非常精彩，值得一讀。
Dinitrosyliron Complex [(PMDTA)Fe(NO)(2)]: Intermediate for Nitric Oxide Monooxygenation Activity in Nonheme Iron Complex
(2020-06-15)
Lu, Shan
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Chiou, Tzung-Wen
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Li, Wei-Liang
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Wang, Chun-Chieh
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Wang, Yun-Ming
Despite a comprehensive study on the biosynthesis and function of nitric oxide, biological metabolism of nitric oxide, especially when its concentration exceeds the cytotoxic level, remains elusive. Oxidation of nitric oxide by O-2 in aqueous solution has been known to yield NO2. On the other hand, a biomimetic study on the metal-mediated conversion of NO to NO2/NO3- via O-2 reactivity disclosed a conceivable pathway for aerobic metabolism of NO. During the NO-to-NO2-/NO3- conversion, transient formation of metal-bound peroxynitrite and subsequent release of (NO2)-N-center dot via O-O bond cleavage were evidenced by nitration of tyrosine residue or 2,4-di-tert-butylphenol (DTBP). However, the synthetic/catalytic/enzymatic cycle for conversion of nitric oxide into a nitrite pool is not reported. In this study, sequential reaction of the ferrous complex [(PMDTA)Fe(kappa(2) -O,O'- NO2)(kappa(1) -O-NO2)] (3; PMDTA = pentamethyldiethylenetriamine) with NO(g), KC8, and O-2 established a synthetic cycle, complex 3 -> {Fe(NO)(2)}(9) DNIC [(PMDTA)Fe(NO)(2)][NO2] (4) -> {Fe(NO)(2)}(10) DNIC [(PMDTA)Fe(NO)(2)] (1) -> [(PMDTA)(NO)- Fe(kappa(2)-O,N-ONOO)] (2) -> complex 3, for the transformation of nitric oxide into nitrite. In contrast to the reported reactivity of metal-bound peroxynitrite toward nitration of DTBP, peroxynitrite-bound MNIC 2 lacks phenol nitration reactivity toward DTBP. Presumably, the [(PMDTA)Fe] core in {Fe(NO)}(8) MNIC 2 provides a mononuclear template for intramolecular interaction between Fe-bound peroxynitrite and Fe-bound NO , yielding Fe-bound nitrite stabilized in the form of complex 3. This [(PMDTA)Fe]-core-mediated concerted peroxynitrite homolytic O-O bond cleavage and combination of the O atom with Fe- bound NO - reveals a novel and effective pathway for NO-to-NO2- transformation. Regarding the reported assembly of the dinitrosyliron unit (DNIU) [Fe(NO)(2)] in the biological system, this synthetic cycle highlights DNIU as a potential intermediate for nitric oxide monooxygenation activity in a nonheme iron system.
GREMA: modelling of emulated gene regulatory networks with confidence levels based on evolutionary intelligence to cope with the underdetermined problem
(2020-06-15)
Tsai, Ming-Ju
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Wang, Jyun-Rong
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Hoe, Shinn-Jang
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Shu, Li-Sun
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Huang, Wen-Lin
Motivation: Non-linear ordinary differential equation (ODE) models that contain numerous parameters are suitable for inferring an emulated gene regulatory network (eGRN). However, the number of experimental measurements is usually far smaller than the number of parameters of the eGRN model that leads to an underdetermined problem. There is no unique solution to the inference problem for an eGRN using insufficient measurements. Results: This work proposes an evolutionary modelling algorithm (EMA) that is based on evolutionary intelligence to cope with the underdetermined problem. EMA uses an intelligent genetic algorithm to solve the large-scale parameter optimization problem. An EMA-based method, GREMA, infers a novel type of gene regulatory network with confidence levels for every inferred regulation. The higher the confidence level is, the more accurate the inferred regulation is. GREMA gradually determines the regulations of an eGRN with confidence levels in descending order using either an S-system or a Hill function-based ODE model. The experimental results showed that the regulations with high-confidence levels are more accurate and robust than regulations with low-confidence levels. Evolutionary intelligence enhanced the mean accuracy of GREMA by 19.2% when using the S-system model with benchmark datasets. An increase in the number of experimental measurements may increase the mean confidence level of the inferred regulations. GREMA performed well compared with existing methods that have been previously applied to the same S-system, DREAM4 challenge and SOS DNA repair benchmark datasets.
Enhancing magnetoelectric effect in magneto-electro-elastic laminated composites via interface modulus and stress
(2020-06-15)
Kuo, H. Y.
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Shih, C. L.
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Pan, E.
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土木工程學系
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Department of Civil Engineering
Magnetoelectric (ME) coupling is of interest for a variety of applications, but it is weak in a single-phase material. Strain-coupled laminates are an efficient way to achieve a high ME coupling. In this paper, we first derive an exact solution for a simply supported multilayered anisotropic magneto-electro-elastic plate with interfacial magneto-electro-elasticity. It is expressed in terms of the extended pseudo Stroh formalism along with the propagator matrix method. The interface modulus and stress are considered by constructing an interface matrix. Based on this solution, sandwich plates made of different layups of piezoelectric and piezomagnetic materials are numerically studied. Our results indicate that for the given layup, it is possible to tune the ME coupling by the interface modulus and stress. Considering interface effect is common in nanoplate, this study could provide an extra channel for turning the ME coupling in the layered magneto-electro-elastic plates with possible device applications. (C) 2020 Elsevier Ltd. All rights reserved.
Femtosecond time-evolution of mid-infrared spectral line shapes of Dirac fermions in topological insulators
(2020-06-17)
Yeh, Tien-Tien
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Tu, Chien-Ming
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Lin, Wen-Hao
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Cheng, Cheng-Maw
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Tzeng, Wen-Yen
Mid-infrared (MIR) light sources have much potential in the study of Dirac-fermions (DFs) in graphene and topological insulators (TIs) because they have a low photon energy. However, the topological surface state transitions (SSTs) in Dirac cones are veiled by the free carrier absorption (FCA) with same spectral line shape that is always seen in static MIR spectra. Therefore, it is difficult to distinguish the SST from the FCA, especially in TIs. Here, we disclose the abnormal MIR spectrum feature of transient reflectivity changes (Delta R/R) for the non-equilibrium states in TIs, and further distinguish FCA and spin-momentum locked SST using time-resolved and linearly polarized ultra-broadband MIR spectroscopy with no environmental perturbation. Although both effects produce similar features in the reflection spectra, they produce completely different variations in the Delta R/R to show their intrinsic ultrafast dynamics.
Germanium Possessing Facet-Specific Trap States and Carrier Lifetimes
(2020-06-18)
Tan, Chih-Shan
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Lu, Ming-Yen
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Peng, Wei-Hao
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Chen, Lih-Juann
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Huang, Michael H.
Previously, the notable differences in the band structure and changes in bond length and bond distortion between the semiconducting and metal-like planes of germanium have been used to understand the facet-dependent electrical conductivity properties of germanium wafers. To gain further insights into the appearance of electrical facet behaviors, impedance measurements were performed on the Ge{111}, {110}, and {100} wafers. Impedance data and several conductivity-related parameters were used to produce a diagram showing the amount of trap states and the trap state energies. The trap states are found within the germanium band gap with a facet-specific distribution of energies. Compared to the {100} and {110} wafers, the Ge{111} wafer has the lowest trap state density in the probed voltage range. This is consistent with its best conductivity property, as trap states hinder the direct excitation of electrons to the conduction band. Carrier lifetime can also be obtained from the impedance data. The {111} surface generally has the shortest carrier lifetime, which is related to its high electrical conductivity. Interestingly, diffuse reflectance and ultraviolet photoelectron spectral (UPS) measurements yield the smallest Schottky barrier between Ag and the most conductive Ge{111} surface, showing this approach to understanding electrical facet effects can still be useful despite its inadequacy to account for the facet-specific conductivity behaviors of Si wafers. However, one should not rely solely on the experimentally determined Schottky barriers to explain electrical facet effects.
Effect of Lauric Acid on the Thermal and Mechanical Properties of Polyhydroxybutyrate (PHB)/Starch Composite Biofilms
(2020-06-19)
Adorna, Joemer A., Jr.
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Aleman, Camelle Kaye A.
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Gonzaga, Ian Lorenzo E.
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Pangasinan, Jamela N.
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Sisican, Kim Marie D.
Polyhydroxybutyrate (PHB) is a biopolymer of natural origin, one of the suitable alternatives for synthetic plastics. However, pure PHB has a high production cost, is relatively brittle, and has poor processability, hence its limited application. Combining PHB with biomass fillers and plasticizers can significantly improve the properties of the polymer, leading to its commercial usage. In this study, PHB was incorporated with starch (S) as a cheap biomass filler and lauric acid (LA) as a potential plasticizer. The PHB/S/LA composites were prepared using a modified solvent casting method with the incremental addition of LA. The PHB/S ratio was maintained at a ratio of 80/20 (w/w). Physicochemical characterization via EDS, XRD, and FTIR proved that the composite components have blended through nucleation and plasticization processes. The morphology of the PHB/S blends was found to be a heterogeneous matrix, with decreased inhomogeneity upon the addition of LA in the composite. Thermal characterization done by TGA and DSC showed that the thermal properties of PHB/S films improved with the addition of LA. Mechanical tests (UTM) proved that the elastic strain of the films also increased with the addition of LA, although the tensile strength decreased slightly compared to pure PHB/S. Overall, the results of this study provide baseline information on the improvement of PHB-based bioplastics.
Applications of Tamm plasmon-liquid crystal devices
(2020-06-20)
Jeng, Shie-Chang
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影像與生醫光電研究所
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Institute of Imaging and Biomedical Photonics
The Tamm-plasmon-polariton (TPP) occurs at the interface between a metallic film and the photonic-crystal (PC) substrate. Unlike conventional surface-plasmon-polariton (SPP), TPP can be directly excited by both the transverse electric (TE) and transverse magnetic (TM) electromagnetic waves without using additional coupling optics. The fact that the optical functionality of most plasmonics devices is determined after fabrication limits their applications. Tunable SPP devices by applying liquid crystals (LCs) have been widely demonstrated due to their large birefringence and easy controllability via external stimuli. However, actively tuning TPP is difficult because the localised electric field is between the metallic film and PC substrate, the change of refractive index above the metallic film has only small influences on TPP. This article is intended to briefly review recent progress towards using LCs for actively tuning TPP devices. Not only TPP devices can gain benefits from LCs, we will also discuss the applications of TPP for measuring the anisotropy of the alignment films of LC devices. The sensitivity of the proposed scheme will be discussed.
Liquid crystal-based capacitive, electro-optical and dielectric biosensors for protein quantitation
(2020-06-20)
Lee, Mon-Juan
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Lee, Wei
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光電學院
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College of Photonics
The electrical, electro-optical and dielectric properties of liquid crystals (LCs) are routinely manipulated in liquid-crystal display (LCD) devices, but their potential application in the development of biosensors is still in a nascent stage. In this review, utilising the electrical properties, electro-optical effect and dielectric anisotropy in LCs, we provide insights into several possible modes of label-free biodetection and describe how capacitance, electro-optical and dielectric measurements of various LCs assist in quantitative analysis of biomolecules. It is concluded that the electrically induced biosensing techniques proposed here provides new incentives for researchers to study the interaction between LCs and biomolecules and to resolve technical hurdles facing the development of LC-based biosensors.
Site-Selective Deposition of a Cobalt Cocatalyst onto a Plasmonic Au/TiO2 Photoanode for Improved Water Oxidation
(2020-06-22)
Okazaki, Megumi
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Suganami, Yoshiki
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Hirayama, Naoki
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Nakata, Hiroko
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Oshikiri, Tomoya
Plasmonic Au/TiO2 thin film works as a stable water oxidation photoanode. Here we show that site-selective deposition of nanosized CoOx as a water oxidation cocatalyst at the edge of Au nanoparticles on the TiO2 film improves the photoelectrochemical water oxidation activity. The nanosized CoOx was deposited by a photoassisted electrochemical method onto the Au/TiO2 thin film. The CoOx loading amount was controllable by changing the amount of electric charge that flowed during the deposition, which influenced the photoelectrochemical performance. Under visible light, the optimized CoOx/Au/TiO2 thin film generated stable photoanodic current, which was similar to 3 times higher than that obtained using Au/TiO2.
Quantifying sediment mass redistribution from joint time-lapse gravimetry and photogrammetry surveys
(2020-06-22)
Mouyen, Maxime
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Steer, Philippe
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Chang, Kuo-Jen
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Le Moigne, Nicolas
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Hwang, Cheinway
The accurate quantification of sediment mass redistribution is central to the study of surface processes, yet it remains a challenging task. Here we test a new combination of terrestrial gravity and drone photogrammetry methods to quantify sediment mass redistribution over a 1 km(2) area. Gravity and photogrammetry are complementary methods. Indeed, gravity changes are sensitive to mass changes and to their location. Thus, by using photogrammetry data to constrain this location, the sediment mass can be properly estimated from the gravity data. We carried out three joint gravimetry-photogrammetry surveys, once a year in 2015, 2016 and 2017, over a 1 km(2) area in southern Taiwan, featuring both a wide meander of the Laonong River and a slow landslide. We first removed the gravity changes from non-sediment effects, such as tides, groundwater, surface displacements and air pressure variations. Then, we inverted the density of the sediment with an attempt to distinguish the density of the landslide from the density of the river sediments. We eventually estimate an average loss of 3.7 +/- 0.4 x 10(9) kg of sediment from 2015 to 2017 mostly due to the slow landslide. Although the gravity devices used in this study are expensive and need week-long surveys, new instrumentation currently being developed will enable dense and continuous measurements at lower cost, making the method that has been developed and tested in this study well-suited for the estimation of erosion, sediment transfer and deposition in landscapes.
Electrical and optical properties of degenerate and semi-insulating ZnGa2O4: Electron/phonon scattering elucidated by quantum magnetoconductivity
(2020-06-22)
Look, David C.
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Leedy, Kevin D.
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Horng, Ray-Hua
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Santia, Marco D.
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Badescu, Stefan C.
We study the electrical and optical properties of degenerate ZnGa2O4 films grown by metalorganic chemical vapor deposition (MOCVD) on sapphire and semi-insulating films grown by pulsed laser deposition (PLD) on fused silica. After a forming-gas anneal at 700 degrees C, the MOCVD film is highly conducting, with a room-temperature carrier concentration of 2 x 10(20)cm(-3), a mobility of 20cm(2)/V s, and direct bandgap absorptions at 3.65eV and 4.60eV. Under the same annealing conditions, the PLD film is semi-insulating, with a direct bandgap absorption at 5.25eV. The phonon structure, important for electrical and thermal conduction as well as superconductivity and other quantum phenomena, is very complicated due to the large number of atoms (and, thus, phonon branches) in the unit cell. However, we show that the phonon contributions to electron mobility (mu(ph)) can be directly measured by quantum-based magnetoconductivity over the temperature span T=10-200 K. From an approximate analytical formula, mu(ph) = function (T-ph, T), we calculate an effective phonon energy kT(ph)(T) that takes account of all phonon contributions at temperature T. For T=10-200K, the value of kT(ph) ranges from about 10 to 90meV, consistent with the energy range of the ZnGa2O4 phonon density of states (at 0K) calculated by density functional theory. The total measured mobility can then be modeled by mu(-1)(tot) = mu(-1)(ii) + mu(-1)(ph), where mu(ii) is the mobility due to ionized-impurity scattering. With a high bandgap, controllable conductivity, high breakdown voltage, and bulk-growth capability, ZnGa2O4 offers opportunities for high-power electronics and UV detectors. Published under license by AIP Publishing.
Interfacial Structure-Modulated Plasmon-Induced Water Oxidation on Strontium Titanate
(2020-06-22)
Shi, Xu
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Li, Xiaowei
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Toda, Takahiro
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Oshikiri, Tomoya
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Ueno, Kosei
Plasmon-induced carrier transfer at metallic nanoparticle/semiconductor heterojunctions has received great attention because of its tremendous potential in applications, such as photocatalysis and photoelectric and energy conversion. The interfacial structure of the heterojunction is known to play an important role in charge transfer as well as the subsequent chemical reactions. Here, we studied the Au nanoparticle (Au-NP)-loaded (100)-, (110)-, and (111)-oriented single-crystalline strontium titanate (STO) as a model to investigate the effects of interfacial structure on the plasmon-induced charge separation between the metallic nanoparticles and semiconductors. Via photoelectrochemical characterizations, we found that the efficiency of the plasmon-induced water oxidation reaction on STO(100) is more than 1.4 times higher than that on the other two orientation facets. This enhancement was demonstrated to stem from the high oxidation ability of plasmon-induced holes captured in the surface states. Furthermore, the molecular processes of water oxidation were investigated by monitoring the surface oxidation status of Au-NP/STO as intermediates of plasmon-induced water oxidation using in situ electrochemical surface-enhanced Raman spectroscopy. The onset potential of Au-O vibrations on Au-NP/STO(100) was determined to be 0.4 V more negative than that of Au-NP/STO(110), further confirming the higher oxidation ability of the plasmon-induced holes. Our observation provides an opportunity to efficiently modulate plasmon-excited hot-carrier reaction processes for photochemical applications through interfacial engineering.
Switching between spectral broadening and narrowing of the exciton absorption band of a CH3NH3PbI3 film on altering the polarity of an applied electric field
(2020-06-22)
Awasthi, Kamlesh
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Kala, Kannankutty
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Rana, Shailesh
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Diau, Eric Wei-Guang
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Ohta, Nobuhiro
Electric field-induced broadening and narrowing of an exciton absorption band have been observed to depend on the polarity of the applied electric field for methylammonium lead triiodide perovskite (MAPbI(3)) as a thin film sandwiched between a conducting film of fluorine-doped tin oxide (FTO) and an insulating film of poly(methyl methacrylate) (PMMA). The width of the absorption band increased or decreased when the direction of the applied field was toward FTO or PMMA, respectively, indicating that the spectral broadening and narrowing become switchable on altering the direction of the applied electric field. When titanium oxide (TiO2) in a compact layer was introduced between the MAPbI(3) and FTO layers, the linear electric field effect that depended on the polarity was either not observed or decreased significantly although the quadratic field effects on the exciton absorption band were similarly observed with or without the TiO2 layer.