Browsing by Issue Date, starting with "2020-03-03"

Now showing 1 - 20 of 5479

Nanowear Mechanisms of Mg Alloyed with Al and Y at Elevated Temperatures
(2020-03-03)
Gokhale, Aditya
;
Meena, Trapesh
;
Lee, Soo Yeol
;
Huang, E-Wen
;
Gosvami, Nitya N.
We examine the role of important alloying elements (Al, Y), on friction and wear mechanisms of Mg as a function of temperature. Friction and wear tests of Mg-5%Al and Mg-5%Y alloys performed at room temperature, 100 degrees C and 150 degrees C reveal that addition of Al and Y significantly reduces the coefficient of friction. However, despite higher hardness of Mg-5%Y alloy, its wear rate was found to be higher than Mg-5%Al alloy at elevated temperatures. We show that this behaviour, observed for Mg-5%Y alloy at elevated temperature, can be attributed to its higher surface energy than Mg-5%Al and pure Mg, leading to enhanced adhesive wear, which is detrimental to tribological applications.
Comparing PI3K/Akt Inhibitors Used in Ovarian Cancer Treatment
(2020-03-03)
Wu, Yi-Hui
;
Huang, Yu-Fang
;
Chen, Chien-Chin
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Huang, Chia-Yen
;
Chou, Cheng-Yang
Epithelial ovarian carcinoma (EOC) is the most lethal gynecological malignancy. Herein, we sought to determine the efficacy of phosphoinositide 3-kinase (PI3K)/Akt inhibition using three AZD compounds in a NOD-SCID xenograft mouse model and Akt regulation in a panel of eight ovarian cancer cell lines. Elevated Akt phosphorylation on Ser473 but not on Thr308 in cancerous tissues correlated with short progression-free survival (PFS), overall survival (OS), and death. AZD8835 and AZD8186 inhibited Akt phosphorylation while AZD5363 augmented its phosphorylation on Ser473. To add, all compounds inhibited the Akt downstream effectors 4E-BP1 and p70S6 kinase. AZD8835 and AZD5363 sensitized chemoresistant ovarian cancer cells to cisplatin and paclitaxel treatment. Only AZD5363 could inhibit COL11A1 mRNA and promoter activity, which are important factors in Akt regulation and chemoresistance in ovarian cancer. By using a mouse xenograft model, AZD8835 and AZD5363, but not AZD8186, caused a significant reduction in tumor formation. AZD compounds did not change the mRNA expression of BRCA1/BRCA in ovarian cancer cells, but AZD8835 inhibited BRCA1/BRCA2 mRNA expression and p-ERK protein expression in OVCAR-8 cells with the KRAS mutation. This study highlights the importance of PI3K/Akt in ovarian tumor progression and chemoresistance and the potential application of AZD compounds, especially AZD8835 and AZD5363, as therapeutic agents for the treatment of ovarian cancer.
Multi-Stimuli Responsive FRET Processes of Bifluorophoric AlEgens in an Amphiphilic Copolymer and Its Application to Cyanide Detection in Aqueous Media
(2020-03-04)
Nhien, Pham Quoc
;
Chou, Wei-Lun
;
Cuc, Tu Thi Kim
;
Khang, Trang Manh
;
Wu, Chia-Hua
A novel amphiphilic aggregation-induced emission (AIE) copolymer, that is, poly(NIPAM-co-TPE-SP), consisting of N-isopropylacrylamide (NIPAM) as a hydrophilic unit and a tetraphenylethylene-spiropyran monomer (TPE-SP) as a bifluorophoric unit is reported. Upon UV exposure, the close form of non-emissive spiropyran (SP) in poly(NIPAM-co-TPE-SP) can be photo-switched to the open form of emissive merocyanine (MC) in poly(NIPAM-co-TPE-MC) in an aqueous solution, leading to ratiometric fluorescence of AlEgens between green TPE and red MC emissions at 517 and 627 nm, respectively, via Forster resonance energy transfer (FRET). Distinct FRET processes of poly(NIPAM-co-TPE-MC) can be observed under various UV and visible light irradiations, acid-base conditions, thermal treatments, and cyanide ion interactions, which are also confirmed by theoretical studies. The subtle perturbations of environmental factors, such as UV exposure, pH value, temperature, and cyanide ion, can be detected in aqueous media by distinct ratiometric fluorescence changes of the FRET behavior in the amphiphilic poly(NIPAM-co-TPE-MC). Moreover, the first FRET sensor polymer poly(NIPAM-co-TPE-MC) based on dual AlEgens of TPE and MC units is developed to show a very high selectivity and sensitivity with a low detection limit (LOD = 0.26 mu M) toward the cyanide ion in water, which only contain an approximately 1% molar ratio of the bifluorophoric content and can be utilized in cellular bioimaging applications for cyanide detections.
Controlled synthesis and CO sensing potentials of size-tunable highly-uniform mesoporous Co3O4 nanospheres
(2020-03-05)
Chen, Kuan-Wei
;
Tsai, Ju-Heng
;
Chen, Chun-Hua
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A series of highly-uniform and mesoporous Co3O4 nanospheres comprising porously-assembled tiny building blocks, and more importantly, with widely tunable sizes from 50 nm up to 500 nm were successfully synthesized for the first time via single facile polyol approach. The crucial synthesizing factors including molecular weight and concentrations of polyvinylpyrrolidone, the fraction of cobalt precursor, and the subsequent calcination temperature and time were systematically varied over a very wide range for extensively understanding their effects on growth mechanisms, uniformity and particularly the minimum assembled size. The present unique mesoporous nanoassemblies evidently lead to not only a higher surface-to-volume ratio for a variety of potential applications but a lower operating temperature for CO sensing compared with that reported for a variety of intrinsic or heterogeneous Co3O4 nanostructures. (C) 2019 Elsevier B.V. All rights reserved.
Virtual-freezing fluorescence imaging flow cytometry
(2020-03-06)
Mikami, Hideharu
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Kawaguchi, Makoto
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Huang, Chun-Jung
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Matsumura, Hiroki
;
Sugimura, Takeaki
By virtue of the combined merits of flow cytometry and fluorescence microscopy, imaging flow cytometry (IFC) has become an established tool for cell analysis in diverse biomedical fields such as cancer biology, microbiology, immunology, hematology, and stem cell biology. However, the performance and utility of IFC are severely limited by the fundamental trade-off between throughput, sensitivity, and spatial resolution. Here we present an optomechanical imaging method that overcomes the trade-off by virtually freezing the motion of flowing cells on the image sensor to effectively achieve 1000 times longer exposure time for microscopy-grade fluorescence image acquisition. Consequently, it enables high-throughput IFC of single cells at >10,000 cells s(-1) without sacrificing sensitivity and spatial resolution. The availability of numerous information-rich fluorescence cell images allows high-dimensional statistical analysis and accurate classification with deep learning, as evidenced by our demonstration of unique applications in hematology and microbiology. High throughput imaging flow cytometry suffers from trade-offs between throughput, sensitivity and spatial resolution. Here the authors introduce a method to virtually freeze cells in the image acquisition window to enable 1000 times longer signal integration time and improve signal-to-noise ratio.
Polydopamine and Its Composite Film as an Adhesion Layer for Cu Electroless Deposition on SiO2
(2020-03-09)
Chou, Shih-Cheng
;
Chung, Wei-An
;
Fan, Tzu-Ling
;
Dordi, Yezdi
;
Koike, Junichi
We explore dopamine (DA) and its mixtures with polyethylene glycol (PEG) or polyethylenimine (PEI) as an adhesion layer for bonding between Cu and SiO2. The DA is oxidized to form polydopamine (PDA) which deposits as aggregates on SiO2 surface with notable surface roughness. After mixing with PEG or PEI, the morphology of PDA aggregates is altered considerably. Electroless Cu deposition in a mild alkaline bath is employed to deposit Cu atop the adhesion layer. The Cu films reveal an fcc lattice with (111) preferred orientation and their thickness was around 650 nm. From measurements of four-point probe, breaking strength, and tape-peeling tests, the PDA/PEG mixture reveals impressive performance serving as a strong adhesive for robust Cu bonding. We attribute the unique adhesive ability of PDA/PEG to the hydrogen bonds established between the catechol and amine groups of DA with PEG that renders desirable film formation on the SiO2 surface for optimized interaction between Cu and SiO2. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
Easy-cone magnetic structure in (Cr0.9B0.1)Te
(2020-03-09)
He, Yangkun
;
Fecher, Gerhard H.
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Kroder, Johannes
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Borrmann, Horst
;
Wang, Xiao
Although stoichiometric CrTe is difficult to synthesize because of the appearance of Cr vacancies, ferromagnetic Cr1-x Te compounds have attracted increasing attention. This work investigates single crystalline (Cr-0.9 B-0.1)Te with the Cr vacancies filled by B to stabilize the hexagonal crystal structure and shift the Fermi energy. The structural and magnetic properties have been characterized by experimental measurements and ab initio calculations. A collinear spin structure with an easy axis along c is observed at high temperature, whereas the magnetic moments localized at the Cr atoms gradually tilt away from the c-axis below 140K. A maximum tilt angle of 30 degrees is observed at a temperature of 2K. (C) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http:// creativecommons.org/licenses/by/4.0/).
Putative Abscopal Effect in Three Patients Treated by Combined Radiotherapy and Modulated Electrohyperthermia
(2020-03-10)
Chi, Mau-Shin
;
Mehta, Minesh P.
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Yang, Kai-Lin
;
Lai, Hung-Chih
;
Lin, Ying-Chu
Purpose: True abscopal responses from radiation therapy are extremely rare; the combination of immune checkpoint inhibitors with radiation therapy has led to more reports of the abscopal effect, but even in this setting, the genuine magnitude remains unknown and is still considered generally uncommon. We report the occurrence of what appears to be putative, durable abscopal tumor responses with associated auto-immune systemic reactions resulting from the combination of local radiotherapy (RT) and modulated electrohyperthermia (mEHT). Materials and Methods: Data from advanced cancer patients treated palliatively with RT and mEHT between January and December 2017 were collected as part of a post-marketing safety monitoring program of mEHT therapy. We specified a minimum RT dose of 30 Gy and at least four mEHT treatments for reporting toxicities, which was the primary aim of the larger study. Results: Thirty-three patients treated with RT and mEHT, both applied to the same lesion, were included. The median RT dose was 45.5 Gy in 20 fractions (fxs) and the median number of mEHT treatments was 12 (range, 4-20). Most patients had subsequent systemic therapy after one course of RT and mEHT. Three patients (9.1%) developed autoimmune toxicities. Case number 1 received RT and mEHT only; case number 2 had two cycles of concurrent low dose chemotherapy during RT; and case number 3 received concurrent immune checkpoint inhibitors. None of the three patients received any further systemic treatment due to obvious treatment-related autoimmune reactions which occurred rapidly after RT; one had autoimmune hepatitis, one had dermatitis herpetiformis and the third developed severe myasthenia gravis. Interestingly, what we surmise to be long-lasting abscopal responses outside the irradiated area, were noted in all three patients. Conclusion: RT combined with mEHT could putatively result in enhancing immune responsiveness. These preliminary observational findings lead to the generation of a hypothesis that this combination induces both an in-situ, tumor-specific immune reaction and an anti-self-autoimmune reaction, in at least a small proportion of patients, and of those who experience the auto-immune response, tumor response is a concomitant finding. Mechanisms underlying this phenomenon need to be investigated further.
Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS2 Nanosheets for a Highly Efficient Hydrogen Evolution Reaction
(2020-03-11)
Nguyen, Van-Truong
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Le, Phuoc Anh
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Hsu, Yung-Chi
;
Wei, Kung-Hwa
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交大名義發表
With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS2 nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS2). The resultant OGNs@MoS2 structures not only increased the number of active sites of the semiconducting MoS2 nanosheets but also enhanced their conductivity. Our OGNs@MoS2 composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm(-2), a Tafel slope of 73 mV dec(-1), and long-time stability of 10(5) s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS2 composite GNsgMoS(2) (182 mV, 82 mV dec(-1)) and is among the best ever reported for composites involving MoS2 and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER. This approach appears to be an effective and simple strategy for tuning the morphologies of composites of graphene and transition metal dichalcogenide materials for a broad range of energy applications.
Atomic Imaging of Molybdenum Oxide Nanowires with Unique and Complex Periodicity by Advanced Electron Microscopy
(2020-03-11)
Ting, Yi-Hsin
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Huang, Chun-Wei
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Yasuhara, Akira
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Chen, Sheng-Yuan
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Chen, Jui-Yuan
Crystalline Mo5O14 exhibits distinctive structural features such as tunnel structure and pseudolamellar arrangement according to the ideal model. However, the spatial resolution of the conventional technique of transmission electron microscopy (TEM) is insufficient to distinguish the actual positions of atoms. In this work, we aimed to systematically analyze and identify the Mo5O14 nanowires fabricated by the chemical vapor deposition (CVD) process. Utilizing high-angle annular dark-field (HAADF), annular bright-field (ABF), and enhanced annular bright-field (E-ABF) within the scanning transmission electron microscope (STEM) mode reveals the structural features at the atomic scale. In addition, the ultrahigh resolution images have confirmed the crystallographic insights in [001] growth direction for the Mo5O14 nanowires with a tunnel structure throughout the nanowire. The cross-sectional images show the unique close-packed plane and atomic arrangement with a network of MoO6 octahedra and MoO7 pentagonal bipyramids. These results are consistent with the theoretical atomic arrangement, supporting the realization of Mo5O14-type catalysts used in the selective oxidation process and battery applications.
【動物飼養管理課程】
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
陽明攜手遠雄，打造自貿區國際醫療中心
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
陽明與遠雄自由貿易港區股份有限公司2月27日簽署「國際醫療暨生技產業發展合作備忘錄」，將以遠雄自由貿易港區為基地，共同打造自...
Cholesteryl alpha-D-glucoside 6-acyltransferase enhances the adhesion of Helicobacter pylori to gastric epithelium
(2020-03-13)
Jan, Hau-Ming
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Chen, Yi-Chi
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Yang, Tsai-Chen
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Ong, Lih-Lih
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Chang, Chia-Chen
Helicobacter pylori, the most common etiologic agent of gastric diseases including gastric cancer, is auxotrophic for cholesterol and has to hijack it from gastric epithelia. Upon uptake, the bacteria convert cholesterol to cholesteryl 6 '-O-acyl-alpha-D-glucopyranoside (CAG) to promote lipid raft clustering in the host cell membranes. However, how CAG appears in the host to exert the pathogenesis still remains ambiguous. Herein we identified hp0499 to be the gene of cholesteryl alpha-D-glucopyranoside acyltransferase (CGAT). Together with cholesteryl glucosyltransferase (catalyzing the prior step), CGAT is secreted via outer membrane vesicles to the host cells for direct synthesis of CAG. This significantly enhances lipid rafts clustering, gathers adhesion molecules (including Lewis antigens and integrins alpha 5, beta 1), and promotes more bacterial adhesion. Furthermore, the clinically used drug amiodarone was shown as a potent inhibitor of CGAT to effectively reduce the bacterial adhesion, indicating that CGAT is a potential target of therapeutic intervention. Jan et al. identify cholesteryl alpha-D- glucopyranoside acyltransferase as a key enzyme in Helicobacter pylori's synthesis of cholesteryl 6'-O-acyl-alpha-D-glucopyranoside, which promotes bacterial adhesion. This study provides insights into the H. pylori-induced pathogenesis and therapeutic strategies against it.
【陽明九景文學與攝影獎】
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
加強校園防疫，將採體溫量測與線上授課
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
因應武漢新型冠狀病毒疫情升溫，本校防疫小組3月9日決議，在人潮眾多的學餐一樓，將採用紅外線熱像儀全面量測體溫。同時，若校園...
【內在力量工作坊】～身體感知與生命敘說
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
本校第17屆傑出校友當選名單出爐
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
恭賀蔡錦華校友、顏鴻順校友、賈淑麗校友、林故廷校友、劉瑞玲校友、劉靜怡校友和謝景祥校友，榮獲本(17)屆「國立陽明大學傑出校...
Functional analysis of Clostridium difficile sortase B reveals key residues for catalytic activity and substrate specificity
(2020-03-13)
Kang, Chia-Yu
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Huang, I-Hsiu
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Chou, Chi-Chi
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Wu, Tsai-Yu
;
Chang, Jyun-Cyuan
Most of Gram-positive bacteria anchor surface proteins to the peptidoglycan cell wall by sortase, a cysteine transpeptidase that targets proteins displaying a cell wall sorting signal. Unlike other bacteria, Clostridium difficile, the major human pathogen responsible for antibiotic-associated diarrhea, has only a single functional sortase (SrtB). Sortase's vital importance in bacterial virulence has been long recognized, and C. difficile sortase B (Cd-SrtB) has become an attractive therapeutic target for managing C. difficile infection. A better understanding of the molecular activity of Cd-SrtB may help spur the development of effective agents against C. difficile infection. In this study, using site-directed mutagenesis, biochemical and biophysical tools, LC-MS/MS, and crystallographic analyses, we identified key residues essential for Cd-SrtB catalysis and substrate recognition. To the best of our knowledge, we report the first evidence that a conserved serine residue near the active site participates in the catalytic activity of Cd-SrtB and also SrtB from Staphylococcus aureus. The serine residue indispensable for SrtB activity may be involved in stabilizing a thioacyl-enzyme intermediate because it is neither a nucleophilic residue nor a substrate-interacting residue, based on the LC-MS/MS data and available structural models of SrtB?substrate complexes. Furthermore, we also demonstrated that residues 163?168 located on the ?6/?7 loop of Cd-SrtB dominate specific recognition of the peptide substrate PPKTG. The results of this work reveal key residues with roles in catalysis and substrate specificity of Cd-SrtB.
【安全是回家唯一的路】~交通安全教育宣導講座
(國立陽明大學, 2020-03-13)
陽明電子報編輯小組
Comparison of alternative approaches for difference, noninferiority, and equivalence testing of normal percentiles
(2020-03-13)
Shieh, Gwowen
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管理科學系
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Department of Management Science
Background Percentiles are widely used in scientific research for determining the comparative magnitude and reference limit of quantitative measurements. The investigations for point and interval estimation of normal percentiles are well documented in the literature. However, the corresponding statistical tests of hypothesis have received relatively little attention. Methods To facilitate data analysis and design planning of percentile study, this paper aims to present hypothesis testing procedures and associated power functions for assessing the difference, noninferiority, and equivalence of normal percentiles. Results Numerical illustrations about drug dissolution are provided to demonstrate the usefulness of the suggested exact approaches and the deficiency of approximate methods. Conclusions The exact approaches are superior to the approximate methods on the basis of control of Type I errors. Computer algorithms are constructed to implement the recommended test procedures and sample size calculations for percentile analysis.