Browsing by Issue Date, starting with "2020-02-04"

Now showing 1 - 20 of 5655

Rapid Extraction and Analysis of Volatile Solutes with an Effervescent Tablet
(2020-02-04)
Elpa, Decibel P.
;
Wu, Shu-Pao
;
Urban, Pawel L.
;
交大名義發表
;
National Chiao Tung University
Extraction of volatile compounds from complex liquid matrices is a critical step in volatile compound analysis workflows. Recently, green chemistry principles are increasingly implemented in extraction processes. Some of the available approaches are solvent-free but still require concentration or trapping of analytes. Here, we propose effervescent tablet-induced extraction (ETIE) as a method of transferring volatile/semivolatile compounds from liquid matrices to the gas phase for analysis. This technique relies on the release of carbon dioxide produced in situ during a neutralization reaction, which occurs when a tablet is inserted into an aqueous sample matrix. In this process, many bubbles of carbon dioxide are instantly formed in the sample matrix. The bubbles rapidly extract and liberate volatile compounds from the sample. The gaseous effluent is then immediately transferred to a detector (atmospheric pressure chemical ionization mass spectrometry (MS) or gas chromatography (GC) hyphenated with MS). ETIE-GC-MS can be used for analysis of volatile compounds present in real samples. The method was validated for analysis of selected ethyl esters present in a yogurt drink. The calibration data set was linear over a range from 5 x 10(-7) to 1 X 10(-5) M. The limits of detection ranged from 1.51 X 10(-7) to 6.82 X 10(-7) M, while the recoveries ranged from 71 to 118%. Inter- and intraday precision of selected ethyl esters in aqueous solution was satisfactory (relative standard deviation, 3.6-18.3%). Furthermore, it is shown that ETIE improves the performance of headspace solid-phase microextraction while eliminating the need for heating and shaking samples.
Observation of Femtosecond Acoustic Anomaly in a Solid Liquid Interface
(2020-02-06)
Sun, Chi-Kuang
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Yao, Yi-Ting
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Shen, Chih-Chiang
;
Ho, Mu-Han
;
Lu, Tien-Chang
Here we report a femtosecond anomaly observed at a solid liquid interface: femtosecond acoustic echo being advanced by the application of a viscous liquid to the solid surface. Through extensive simulation and experiments, we attribute this new discovery to the effect introduced by the surface-adsorbed water layer, switching between properties more viscous than water and more solid-like than ice. Our study further indicates a new technology paradigm: the femtosecond acoustic system to probe the viscoelastic properties of the surface-adsorbed water layer, which is not achievable by any available current technology.
Role of Depolarization Factors in the Evolution of a Dipolar Plasmonic Spectral Line in the Far- and Near-Field Regimes
(2020-02-06)
Januar, Mochamad
;
Liu, Bei
;
Cheng, Jui-Ching
;
Hatanaka, Koji
;
Misawa, Hiroaki
In this article, the excitation of dipolar localized surface plasmon resonances (LSPRs) in both the far- and near-field regions is described in terms of the relevant static, dynamic, and radiative depolarization factors. This approach offers a direct relationship between the evolution of the LSPR spectral line and the depolarization components in an analogous sense to a harmonic oscillator. The static, dynamic, and radiative terms reflect the coefficients of the "stiffness", effective mass, and damping in the oscillator system, respectively. Hence, one can immediately perceive that the static part of the depolarization factor is mainly responsible for the shifts in the resonant frequency, and the radiative part is responsible for the change in bandwidth. Additionally, the dynamic part behaves like an effective mass, acting as an inertial weighting factor that decides how significant the changes taking place in the system are. From this model, we can rationalize that the qualitative behavior of the far-field efficiency primarily depends on the shifting resonant frequencies, and the corresponding near-field efficiency is highly sensitive to the presence of damping. The model also clarifies the discrepancy in the resonant frequency and bandwidth between the far- and near-field spectra, which is due to the significant presence of the radiative component. These basic descriptions can be used as a guiding principle for handling more sophisticated structures and gaining more rationalized designs for novel applications related to the LSPR mechanism.
Insight into the Expanded Mislinked Porphyrins with High Second Order Nonlinear Optical Response
(2020-02-06)
Li, Bo
;
Sathishkumar, Palanivel
;
Gu, Feng Long
;
Zhu, Chaoyuan
;
應用化學系
Materials with outstanding nonlinear optical (NLO) response exhibit excellent prospects in electrooptic devices. Thus, it is essential to find a high-performance NLO material to meet the growing demand for high-speed data transmission. In this study, theoretical investigations on the second order NLO properties of the novel expanded mislinked thia-norhexaphyrin, sulfur-free pentaphyrin, and their substituted derivatives were performed using density functional theory. Theoretical calculations display that the approximate planar structures of sulfur-free pentaphyrin embedded with two five-membered rings exhibits a remarkable NLO response and holds large dipolar contribution (Phi(J=1) = 63.5%) to the first hyperpolarizability among four parent expanded mislinked porphyrins. The static first hyperpolarizability values of these expanded porphyrins were found to range from 3490 to 14 229 au. In addition, the second order NLO response of these porphyrins has greatly improved except for minority electron-releasing- and electron-withdrawing-group substituted cases, and the static first hyperpolarizability value has increased to 47 950 au after installing the donor and acceptor groups. Unambiguous evidence reveals that expanded mislinked porphyrin can serve as a potential candidate for NLO materials.
Pregnenolonyl-alpha-glucoside exhibits marked anti-cancer and CYP17A1 enzymatic inhibitory activities
(2020-02-07)
Chou, Feng-Pai
;
Hsu, Wen-Chen
;
Huang, Sheng-Cih
;
Chang, Chin-Yuan
;
Chiou, Ya-Sheng
We report here that pregnenolonyl-alpha-glucoside (2), a steryl glycoside synthesized directly from pregnenolone and glucose via a consecutive multienzyme-catalyzed process, exhibits marked dose-dependent cytotoxic activity against HT29, AGS, and ES-2 cells with IC50 values of 23.5 to 50.9 mu M. An in vitro CYP17A1 binding pattern assay and protein-ligand docking model support that 2, like abiraterone, binds in the active site heme iron pocket of CYP17A1.
Mechanically tunable exchange coupling of Co/CoO bilayers on flexible muscovite substrates
(2020-02-07)
Thai Duy Ha
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Yen, Min
;
Lai, Yu-Hong
;
Kuo, Chang-Yang
;
Chen, Chien-Te
The employment of flexible muscovite substrates has given us the feasibility of applying strain to heterostructures dynamically by mechanical bending. In this study, this novel approach is utilized to investigate strain effects on the exchange coupling in ferromagnetic Co and anti-ferromagnetic CoO (Co/CoO) bilayers. Two different Co/CoO bilayer heterostructures were grown on muscovite substrates by oxide molecular beam epitaxy, with the CoO layer being purely (111)- and (100)-oriented. The strain-dependent exchange coupling effect can only be observed on Co/CoO(100)/mica but not on Co/CoO(111)/mica. The origin of this phenomenon is attributed to the anisotropic spin re-orientation induced by mechanical bending. The strain-dependent magnetic anisotropy of the bilayers determined by anisotropic magnetoresistance measurements confirms this conjecture. This study elucidates the fundamental understanding of how magnetic exchange coupling can be tuned by externally applied strain via mechanical bending and, hence, provides a novel approach for implementing flexible spintronic devices.
Operando Spectral and Electrochemical Investigation into the Heterophase Stimulated Active Species Transformation in Transition-Metal Sulfides for Efficient Electrocatalytic Oxygen Evolution
(2020-02-07)
Wang, Miao
;
Dong, Chung-Li
;
Huang, Yu-Cheng
;
Shen, Shaohua
;
交大名義發表
In-depth understanding of electrocatalytically active species transformation during oxygen evolution reaction (OER) is highly guidable to design effective electrocatalysts for water splitting. Herein, cobalt sulfide (CoSx) nanovesicles decorated with iron sulfide (FeSx) heterophases were successfully synthesized by using a metal-organic framework precursor through a solvothermal method. The obtained CoSx/FeSx exhibited much elevated OER activity as compared to pristine CoSx and even most previously reported cobalt-based electrocatalysts, with the overpotential of 304 mV at 10 mA cm(-2) in 1 M KOH. As revealed by operando Raman and X-ray absorption spectroscopy measurements, the electrocatalytically active species transformation in CoSx nanovesicles could be stimulated by the incorporated FeSx heterophases due to the increased average valence state of cobalt and lowered coordination of cobalt sites. As a result, the electrocatalytically active cobalt oxyhydroxides could be more easily formed on the catalyst surface during OER and thus contributed to the highly improved performance. This real-time spectral and electrochemical insight into the electrocatalytically active species transformation may guide the rational design of highly efficient electrocatalysts for water splitting from the viewpoint of electronic structure-electrocatalytic activity relationship.
Five-dimensional scalar-vector Kalb-Ramond black holes
(2020-02-10)
Do, Tuan Q.
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Kao, W. F.
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物理研究所
;
Institute of Physics
We will focus on a model with a scalar-vector coupling and a scalar Kalb-Ramond coupling. The Kalb-Ramond two-form is known to be equivalent to a U-1 gauge one-form in five dimensions. The model with both scalar-vector and scalar Kalb-Ramond interactions is hence effectively equivalent to an action with two independent vector fields. As a result, a new set of spherically symmetric black hole solutions will be presented for the scalar-vector Kalb-Ramond theory in five dimensions. We will show that the presence of the scalar fields and gauge fields affect the black hole structure in a nontrivial manner. Related implications will also be discussed in this paper.
Control of radial miscible viscous fingering
(2020-02-10)
Sharma, Vandita
;
Nand, Sada
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Pramanik, Satyajit
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Chen, Ching-Yao
;
Mishra, Manoranjan
We investigate the stability of radial viscous fingering (VF) in miscible fluids. We show that the instability is determined by an interplay between advection and diffusion during the initial stages of flow. Using linear stability analysis and nonlinear simulations, we demonstrate that this competition is a function of the radius r0 of the circular region initially occupied by the less-viscous fluid in the porous medium. For each r0, we further determine the stability in terms of Peclet number (Pe) and log-mobility ratio (M). The Pe-M parameter space is divided into stable and unstable zones: the boundary between the two zones is well approximated by Mc Dff.r0 /Pe 0:55 c. In the unstable zone, the instability is reduced with an increase in r0. Thus, a natural control measure for miscible radial VF in terms of r0 is established. Finally, the results are validated by performing experiments that provide good qualitative agreement with our numerical study. Implications for observations in oil recovery and other fingering instabilities are discussed.
FLAG Review 2019
(2020-02-11)
Aoki, S.
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Aoki, Y.
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Becirevic, D.
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Blum, T.
;
Colangelo, G.
We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. 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 f(K) / 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 Standard Model. For the heavy-quark sector, we provide results for m(c) and m(b) 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. We review the status of lattice determinations of the strong coupling constant as. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.
Full encapsulation or internal buffering in OpenFlow based hardware switches?
(2020-02-11)
Singh, Deepak
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Ng, Bryan
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Lai, Yuan-Cheng
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Lin, Ying-Dar
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Seah, Winston K. G.
Software-Defined Networking (SDN) enables programmability in the network through a software dependent control function. OpenFlow is a de-facto protocol for communication between an SDN switch and the controller. OpenFlow specifications generally allow two methods for packet encapsulation of data packets at the switch that require decisions from the controller, (a) full encapsulation, and (b) internal buffering. However, full encapsulation of data packets has been the default choice for packet processing, and internal buffering has not been explored much, especially for hardware switching. In this paper, we model and analyse the effect of internal buffering on the performance of an OpenFlow hardware switch. We compare queueing models for the switch with full encapsulation and internal buffering for hardware switching. The results show that internal buffering significantly reduces the average packet transfer delay by 85% and packet loss probability by 60%. The results further provide guidelines to network operators that internal buffering for hardware switching is useful for controllers with lower processing rates, especially in delay-sensitive applications running over SDN. For loss-sensitive applications running over SDN, the full encapsulation method is more robust handling flows with a high table miss probability. (C) 2019 Elsevier B.V. All rights reserved.
SLIM: Simultaneous Logic-in-Memory Computing Exploiting Bilayer Analog OxRAM Devices
(2020-02-13)
Kingra, Sandeep Kaur
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Parmar, Vivek
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Chang, Che-Chia
;
Hudec, Boris
;
Hou, Tuo-Hung
von Neumann architecture based computers isolate computation and storage (i.e. data is shuttled between computation blocks (processor) and memory blocks). The to-and-fro movement of data leads to a fundamental limitation of modern computers, known as the Memory wall. Logic in-Memory (LIM)/In-Memory Computing (IMC) approaches aim to address this bottleneck by directly computing inside memory units thereby eliminating energy-intensive and time-consuming data movement. Several recent works in literature, propose realization of logic function(s) directly using arrays of emerging resistive memory devices (example- memristors, RRAM/ReRAM, PCM, CBRAM, OxRAM, STT-MRAM etc.), rather than using conventional transistors for computing. The logic/embedded-side of digital systems (like processors, micro-controllers) can greatly benefit from such LIM realizations. However, the pure storage-side of digital systems (example SSDs, enterprise storage etc.) will not benefit much from such LIM approaches as when memory arrays are used for logic they lose their core functionality of storage. Thus, there is the need for an approach complementary to existing LIM techniques, that's more beneficial for the storage-side of digital systems; one that gives compute capability to memory arrays not at the cost of their existing stored states. Fundamentally, this would require memory nanodevice arrays that are capable of storing and computing simultaneously. In this paper, we propose a novel 'Simultaneous Logic in-Memory' (SLIM) methodology which is complementary to existing LIM approaches in literature. Through extensive experiments we demonstrate novel SLIM bitcells (1T-1R/2T-1R) comprising non-filamentary bilayer analog OxRAM devices with NMOS transistors. Proposed bitcells are capable of implementing both Memory and Logic operations simultaneously. Detailed programming scheme, array level implementation, and controller architecture are also proposed. Furthermore, to study the impact of proposed SLIM approach for real-world implementations, we performed analysis for two applications: (i) Sobel Edge Detection, and (ii) Binary Neural Network- Multi layer Perceptron (BNN-MLP). By performing all computations in SLIM bitcell array, huge Energy Delay Product (EDP) savings of approximate to 75x for 1T-1R (approximate to 40x for 2T-1R) SLIM bitcell were observed for edge-detection application while EDP savings of approximate to 3.5x for 1T-1R (approximate to 1.6x for 2T-1R) SLIM bitcell were observed for BNN-MLP application respectively, in comparison to conventional computing. EDP savings owing to reduction in data transfer between CPU <-> memory is observed to be approximate to 780x (for both SLIM bitcells).
Two new, near-infrared, fluorescent probes as potential tools for imaging bone repair
(2020-02-13)
Lin, Chien-Chou
;
Chang, Walter Hong-Shong
;
Cheng, Tsai-Mu
;
Chiu, Li-Hsuan
;
Wang, Yen-Hsun
A precise imaging technique to evaluate osteogenesis, osteodifferentiation, and osseointegration following peri-implant surgery is in high clinical demand. Herein, we report the generation of two new, near-infrared (NIR) fluorescent probes for use in the molecular imaging of bone repair. The first probe aims to monitor the in vitro differentiation of human mesenchymal stem cells (MSCs) into osteoblasts. A NIR fluorochrome was conjugated to a cyclic peptide that binds to integrin alpha 5 beta 1, a factor that promotes osteogenesis in MSCs and therefore functioned as an osteoblast-specific marker. The second probe aims to monitor osteogenesis, and was generated by conjugating the drug pamidronate to a NIR fluorescent gold nanocluster. Pamidronate specifically binds to hydroxyapatite (HA), a mineral present in bone that is produced by osteoblasts, and therefore provides a functional marker for new bone formation. Our results show that both probes bind to their specific targets in vitro-differentiated osteoblasts, and not to undifferentiated MSCs, and emit NIR fluorescence for functional detection. This in vitro work demonstrates the ability of these probes to bind to active osteoblasts and their mineral deposits and highlight their potential utility as clinical tools for the imaging of the osseointegration process at the molecular level.
Superhelices with tunable twisting power directed from supramolecular pairing of focal asymmetry in achiral dendron-jacketed block copolymers
(2020-02-14)
Lin, I-Ming
;
Chou, Che-Min
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Li, Ming-Chia
;
Guo, Rong-Hao
;
Lee, Cheng-Kuang
The formation of helical assemblies from achiral supramacromolecules has been a highly mysterious process, but is of interest for the generation of a variety of structures and properties. Herein, novel hierarchical superhelices are developed from self-assembly of achiral dendron-jacketed block copolymers (DJBCPs). The presence of focal asymmetry in both the stereochemistry of the dendrons (donors) and interactive binding sites of the copolymer chains (acceptors) plays a pivotal role in generating a spontaneous symmetry breaking through tailored donor-acceptor matching via hydrogen bonding. The focal asymmetry, on a scale of several nanometers, propagates to helical twists of the achiral DJBCP hierarchical assemblies over hundreds of nanometers, such that the primary molecular asymmetry sequentially triggers a secondary helical conformation of the dendron-jacketed blocks, then tertiary supramolecular helical assemblies and eventually quaternary superhelices. The helical twisting power of the superhelices is tunable using the dendron grafting ratio, indicating that the magnitude of helical twisting can be quantitatively adjusted from local to entire structures.
Fabrication of TiO2-coated nanostructured Ni foams for improved mechanical properties
(2020-02-15)
Hung, Pei-Sung
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Chou, Yu-Szu
;
Wang, Guang-Ren
;
Chung, Wei-An
;
Wu, Pu-Wei
We demonstrate a composite approach to improve the mechanical strength of nanostructured Ni foams by producing a conformal coating of TiO2 on the skeletons of the Ni foam. The nanostructured Ni foam is fabricated by a template approach in which colloidal crystals of polystyrene microspheres in 720 nm diameter are constructed by a vertical electrophoresis process, followed by electroplating of Ni to fill the interstitial voids among the closely-packed microspheres and removal of the colloidal template afterward. The formation of TiO2 overcoat is achieved by optimization of sol-gel synthesis to prepare desirable TiO2 sols and their subsequent electrophoresis toward the nanostructured Ni foam in a square wave pulsing mode. The thickness of the TiO2 deposit is proportional to the duration of pulsing electrophoresis. From nano-indentation, the TiO2 -coated nanostructured Ni foams exhibit notable improvements in hardness (53-68%) and reduced elastic modulus (26-37%) over those of pristine nanostructured Ni foams. This strategy of implementing a thin ceramic overcoat provides an effective mean to improve the mechanical properties of nanostructured metals.
《聲之形》（A Silent Voice）
(國立陽明大學, 2020-02-15)
黃柏威
;
陽明電子報編輯小組
榮陽交成立「新型冠狀病毒研發聯盟」，投入快篩試劑與藥物研發
(國立陽明大學, 2020-02-15)
陽明電子報編輯小組
為支援全球面對2019新型冠狀病毒（2019-nCoV）防疫需求，陽明與交通大學、臺北榮民總醫院2月6 日成立研發聯盟，將結合產業，首先...
牙醫學院院長交接，張國威教授出任新院長
(國立陽明大學, 2020-02-15)
陽明電子報編輯小組
牙醫學院2月3日舉行交接典禮，原任的許明倫院長功成身退，由牙醫系張國威特聘教授接任第七任院長。新任的張國威院長表示，43年前...
【2020春季智齡講堂】
(國立陽明大學, 2020-02-15)
陽明電子報編輯小組
【腦科所學術演講系列】
(國立陽明大學, 2020-02-15)
陽明電子報編輯小組