Browsing by Issue Date, starting with "2017-08-14"

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The origin and mitigation of volcano-like morphologies in micron-thick AlGaN/AlN heteroepitaxy
(2017-08-14)
Huang, Chia-Yen
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Chang, Kai-Shiang
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Huang, Cheng-Yao
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Lin, Yun-Hsiang
;
Peng, Wei-Chih
We investigated the origin of morphological instability in 2 mu m thick Al0.6Ga0.4N/AlN heteroepitaxy. The primary morphology was driven by the residual epitaxial strain, forming hill-like morphologies via surface diffusion. The secondary morphology was driven by the interaction between the primary morphology and dislocation clusters in the epitaxial layers. The difference in the local growth rate yields volcano-like morphologies centering on deep pits. Insertion of multi-stack superlattice transition layers between AlGaN and GaN effectively suppressed the secondary morphologies by simultaneously pre-relaxing the template and filtering treading dislocations. Published by AIP Publishing.
Direct measurement of site-specific rates of reactions of H with C3H8, i-C4H10, and n-C4H10
(2017-08-14)
Lin, Chia-Chieh
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Chen, Wei-Yu
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Matsui, Hiroyuki
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Wang, Niann-Shiah
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應用化學系
We measured the rates of abstraction of a hydrogen atom from specific sites in propane C3H8, 2-methyl propane (i-C4H10), and butane (n-C4H10); the sites are a primary hydrogen of C3H8 and i-C4H10 and a secondary hydrogen of n-C4H10. The excellent reproducibility of conditions of a diaphragm-less shock tube enabled us to conduct comparative measurements of the evolution of H atoms in three mixtures-(i) 0.5 ppm C2H5I + Ar, (ii) 0.5 ppm C2H5I + 50-100 ppm alkane as C3H8 or i-C4H10 or n-C4H10 + Ar, and (iii) the same concentrations of alkane + Ar without C2H5I-in the temperature range 1000-1200 K and at a pressure of 2.0 bars. The net profile of rise and decay of H atoms in the C2H5I + alkane mixture was derived on subtracting the absorbance of (iii) from that of (ii). Measurements of the mixture (iii) are important because the absorption of alkanes at 121.6 nm is not negligible. In the temperature range 1000-1100 K, the rate of decomposition of C2H5I was evaluated directly on analyzing the exponential growth of H atoms in the mixture (i). The rate of decomposition of C2H5I is summarized as ln(k/s(-1)) = (33.12 +/- 1.4) - (25.23 +/- 1.5) 10(3)/T (T = 1000-1100 K, P = 2.0 bars); the broadening factor F(T) in the Lindemann-Hinshelwood formula was evaluated in the fall-off region. The site-specific rates of H + (C-3-C-4) alkanes are summarized as follows: H + C3H8 -> H-2 + 1-C3H7, ln(k(1a)) = -(21.34 +/- 0.86) - (5.39 +/- 0.93) 10(3)/T, H + i-C4H10 -> H-2 + i-C4H9, ln(k(2a)) = -(20.50 +/- 1.36) - (6.14 +/- 0.13) 10(3)/T, H + n-C4H10 -> H-2 + 2-C4H9, ln(k(3b)) = - (21.37 +/- 1.15) - (4.83 +/- 1.26) 10(3)/T. The present experimental results are compared with published results from quantum-chemical calculations of potential-energy surfaces and transition-state theory. The present experiments are consistent with those calculations for the reaction rates for the attack at the primary site for H + C3H8 and H + i-C4H10, but for the attack at the secondary site of n-C4H10, our results are substantially smaller than the computational prediction, which might indicate a hindrance by the C-H bonds of the primary sites that serves to decrease the rate of abstraction from the secondary site of n-C4H10. The influence on the total rates of reactions H + alkane and the group additivity rule are discussed. Published by AIP Publishing.
Bubbling solutions for a skew-symmetric Chern-Simons system in a torus
(2017-08-15)
Han, Xiaosen
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Huang, Hsin-Yuan
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Lin, Chang-Shou
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應用數學系
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Department of Applied Mathematics
We establish the existence of bubbling solutions for the following skew-symmetric Chern Simons system Delta u(1) + 1/epsilon(2) e(u2) (1 - e(u1)) = 4 pi Sigma N-1 i=1 delta p(1/i) { Delta u(2) + 1/epsilon(2) e(u1) (1 - e(u2)) = 4 pi Sigma N-2 i=1 delta p(2/i) over a parallelogram Omega with doubly periodic boundary condition, where epsilon > 0 is a coupling parameter, and delta(p) denotes the Dirac measure concentrated at p. We obtain that if (N-1 - 1)(N-2 - 1) > 1, there exists an epsilon(o) > 0 such that, for any epsilon is an element of(0, epsilon(o)), the above system admits a solution (u(1),(epsilon), u(2),(epsilon)) satisfying u1,(epsilon) and u(2),(epsilon) blow up simultaneously at the point p*, and 1/epsilon(2) e(uj,k) (1 - e(ui,epsilon)) -> 4 pi N-i delta(p*) , 1 <= i, j <= 2 , i not equal j as epsilon -> 0, where the location of the point p* defined by (1.12) satisfies the condition (1.13). (C) 2017 Elsevier: Inc. All rights reserved.
Efficiency Enhancement in InGaN Photovoltaic Cells With Inverted Textured Surface
(2017-08-15)
Wu, Ming-Hsien
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Horng, Ray-Hua
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Liao, Wen-Yih
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Chang, Sheng-Po
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Chang, Shoou-Jinn
We report on the improvement of conversion efficiency of InGaN photovoltaic (PV) cells with inverted textured surface (ITS). InGaN PV cells with ITS showed short-circuit current density and conversion efficiency of 0.63 mA/cm(2) and 1.01%, which are 68.17% and 73.33% higher than the characteristics of conventional InGaN PV cells, respectively. The improvement can be attributed to the reduction of both the shading effect of the electrode contact pad and surface reflection of the incident irradiation under one-sun air-mass 1.5-G illumination (100 mW/cm(2)).
Ammonium chiral borate salt catalyzed asymmetric Friedel-Crafts alkylation of indoles with alpha,beta-disubstituted enals
(2017-08-15)
Ueda, Mitsuhiro
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Yagyu, Yoshitaka
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Ryu, Ilhyong
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應用化學系
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Department of Applied Chemistry
In, the presence of a catalytic amount of ammonium chiral borate salt, asymmetric Friedel-Crafts alkylation of indoles with alpha,beta-disubstituted enals proceeded to give the corresponding 1,4-addition products with moderate enantioselectivities. (C) 2017 Elsevier Ltd. All rights reserved.
Oxygen Passivation Mediated Tunability of Trion and Excitons in MoS2
(2017-08-16)
Gogoi, Pranjal Kumar
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Hu, Zhenliang
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Wang, Qixing
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Carvalho, Alexandra
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Schmidt, Daniel
Using wide spectral range in situ spectroscopic ellipsometry with systematic ultrahigh vacuum annealing and in situ exposure to oxygen, we report the complex dielectric function of MoS2 isolating the environmental effects and revealing the crucial role of unpassivated and passivated sulphur vacancies. The spectral weights of the A (1.92 eV) and B (2.02 eV) exciton peaks in the dielectric function reduce significantly upon annealing, accompanied by spectral weight transfer in a broad energy range. Interestingly, the original spectral weights are recovered upon controlled oxygen exposure. This tunability of the excitonic effects is likely due to passivation and reemergence of the gap states in the band structure during oxygen adsorption and desorption, respectively, as indicated by ab initio density functional theory calculation results. This Letter unravels and emphasizes the important role of adsorbed oxygen in the optical spectra and many-body interactions of MoS2.
性別辨識系統及其方法
(2017-08-16)
范倫達
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吳宗翰
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曾煜棋
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荊宇泰
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陳意翔
一種性別辨識方法包含以下步驟：藉由至少一影像深度擷取模組以擷取多個影像畫面並分析影像畫面中的多個人體骨架點資料，以取得對應人體骨架點資料的多個骨架點三維座標，藉由一伺服器依據骨架點三維座標計算至少一人體動態特徵及至少一人體靜態特徵，並依據人體動態特徵及人體靜態特徵以判斷一人體性別；其中，人體動態特徵包含至少一人體骨架點變異數，人體靜態特徵包含依據骨架點三維座標其中之二骨架點三維座標所計算出之至少一骨架寬度值。
阻抗至數位轉換器、阻抗至數位轉換裝置及方法
(2017-08-16)
邱俊誠
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徐舜熙
一種阻抗至數位轉換器包含一偵測阻抗單元、一偏移阻抗單元、一參考阻抗單元、一積分單元及一電壓轉數碼單元。偵測阻抗單元將輸入信號轉換成一第一電荷。偏移阻抗單元將偏移信號轉換成一第二電荷。參考阻抗單元將參考信號轉換成一參考電荷，該參考電荷的正負相關於數位信號的邏輯準位。積分單元接收該第一電荷、該第二電荷及該參考電荷，並於每一週期時間據以加總轉換成一積分電壓。電壓轉數碼單元判斷積分電壓的大小以產生一數位信號。多個週期的數位信號的序列平均值正比於待偵測阻抗的阻抗值。阻抗值的偵測範圍的中心值是正比於類比信號的比例。阻抗值的靈敏度是正比於類比信號的比例。
Real-time observation of interfragment vibration and charge transfer within the TCNQF(4) dimer
(2017-08-17)
Hashimoto, Sena
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Yabushita, Atsushi
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Iwakura, Izumi
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電子物理學系
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Department of Electrophysics
The organic electron acceptors, 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF(4)); are widely used to synthesize multivalent charge-transfer complexes. Their corresponding radical anion complexes have specific electronic, optical, and magnetic characters that have attracted attention in the field of materials development. In the present work,, we have performed time-resolved absorption spectroscopy of the (Na+)(2)(TCNQE(4)(center dot-))(2) radical anion complex to elucidate the reaction dynamics ([TCNQF(4)(center dot-)](2) -> TCNQF(4) + TCNQF(4)(2-)). A visible sub-10 fs laser pulse was used to observe the ultrafast dynamics of the charge transfer and real-time change of the molecular structure during the reaction. Unlike our previous work on the (Na+)(2)(TCNQ(.-))(2) radical anion complex, the interfragment vibrational mode was clearly observed for (Na+)(2)(TCNQP(4)(center dot-))(2). The difference in the intermolecular interaction is considered to reflect the difference in the pi-pi interaction and/or the difference in the flexibility of the molecular plane predicted by theoretical calculations. (C) 2017 Elsevier B.V. All rights reserved.
Andreev reflection in two-dimensional relativistic materials with realistic tunneling transparency in normal-metal/superconductor junctions
(2017-08-17)
Chang, Yung-Yeh
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Mou, Chung-Yu
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Chung, Chung-Hou
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電子物理學系
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Department of Electrophysics
The Andreev conductance across realistic two-dimensional (2D) normal-metal (N)/superconductor (SC) junctions with a relativistic Dirac spectrum is theoretically investigated within the Blonder-Tinkham-Klapwijk formalism with tunable tunneling transparency. It is known that due to the effect of Klein tunneling, impurity potentials at the interface of 2D relativistic materials will enhance (not suppress) the tunneling and therefore are not suitable to model a realistic tunnel junction of these materials. Here, we propose a way to construct a more realistic tunnel junction by adding a narrow, homogeneous local strain, which effectively generates a delta-gauge potential and variations of electron hopping at the interface, to adjust the transparency of the N/SC junction. Remarkable suppression of the Andreev conductance is indeed observed in the graphene N/SC junction as the strength of the local strain increases. We also explore the Andreev conductance in a topological N/SC junction at the two inequivalent Dirac points and predict the distinctive behaviors for the conductance across the chiral-to-helical topological phase transition. The relevance of our results for the adatom-doped graphene is discussed.
Musashi-1 Enhances Glioblastoma Cell Migration and Cytoskeletal Dynamics through Translational Inhibition of Tensin3
(2017-08-18)
Chen, Hsiao-Yun
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Lin, Liang-Ting
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Wang, Mong-Lien
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Laurent, Benoit
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Hsu, Chih-Hung
The RNA-binding protein Musashi-1 (MSI1) exerts essential roles in multiple cellular functions, such as maintenance of self-renewal and pluripotency of stem cells. MSI1 overexpression has been observed in several tumor tissues, including glioblastoma (GBM), and is considered as a well-established marker for tumor metastasis and recurrence. However, the molecular mechanisms by which MSI1 regulates cell migration are still undetermined. Here we reported that MSI1 alters cell morphology, promotes cell migration, and increases viscoelasticity of GBM cells. We also found that MSI1 directly binds to the 3'UTR of Tensin 3 (TNS3) mRNA, a negative regulator of cell migration, to inhibit its translation. Additionally, we identified that RhoA-GTP could be a potential regulator in MSI1/TNS3-mediated cell migration and morphological changes. In a xenograft animal model, high expression ratio of MSI1 to TNS3 enhanced GBM tumor migration. We also confirmed that MSI1 and TNS3 expressions are mutually exclusive in migratory tumor lesions, and GBM patients with MSI1(high)/TNS3(low) pattern tend to have poor clinical outcome. Taken together, our findings suggested a critical role of MSI1-TNS3 axis in regulating GBM migration and highlighted that the ratio of MSI1/TNS3 could predict metastatic and survival outcome of GBM patients.
Reactivity of carbonaceous nanocomposites for water purification and recovery applications
(2017-08-20)
Doong, Ruey-An
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環境工程研究所
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Institute of Environmental Engineering
Synthesis of biscalix[4]arene derivatives and their applications in molecular sensing and organogel materials
(2017-08-20)
Chung, Wen-Sheng
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交大名義發表
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National Chiao Tung University
Preparation and application of biochar for the removal of H2O2 from semiconductor wastewater
(2017-08-20)
Cheng, Hsiao-Fen
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Huang, Chihpin
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Guo, Cuixiang
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Huang, Chin-Pao
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環境工程研究所
Influences of polymorphism and low-angle grain boundary on OFET performances
(2017-08-20)
Wang, Chien-Lung
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Wu, Kuan-Yi
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Hsieh, Chou-Ting
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應用化學系
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Department of Applied Chemistry
Reduction of hydrogen peroxide over biochar surface in acidic solution
(2017-08-20)
Guo, Cuixiang
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Fan, Rui Mei
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Cheng, Hsiao-Fen
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Tzeng, Jing Hua
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Huang, Chihpin
Production and infrared spectra of hydrogenated free radicals and protonated species important in interstellar media
(2017-08-20)
Lee, Yuan-Pern
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Tsuge, Masashi
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Haupa, Karolina
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應用化學系
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Department of Applied Chemistry
Influences of out-of-plane lattice alignment on the OFET performance of TIPS-PEN crystal arrays
(2017-08-20)
Wu, Kuan-Yi
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Wang, Chien-Lung
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應用化學系
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Department of Applied Chemistry
Insights into linear supramolecular polymer formation via TPE and BODIPY containing host-guest interaction
(2017-08-20)
Gouda, Chinmayananda
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材料科學與工程學系
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Department of Materials Science and Engineering
交大e-News第238期-為世大運游泳選手張芳語同學加油
(2017-08-21)
國立交通大學秘書室
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Secretariat