Browsing by Issue Date, starting with "2018-02-15"

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Structure of coherent Mg3TiO4 oxide formed between TiN and MgO
(2018-02-15)
Wei, Lin-Lung
;
Chang, Li
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Solid state reaction in nanometer scale at the interface between TiN and MgO can result in formation of Mg3TiO4 particles which has not reported before. The structure of the newly found oxide is characterized with spherical-aberration corrected scanning transmission electron microscopy at atomic resolution with X-ray energy dispersive spectroscopy. The nanosized Mg3TiO4 oxide particles formed in MgO underneath the epitaxial TN film with cube-on-cube coherent relationship with both MgO and TiN, i.e. TiN(0 0 1) parallel to Mg-Ti-O(0 0 1) parallel to MgO(0 0 1) and TiN[1 1 0] parallel to| Mg-Ti-O[1 1 0] parallel to MgO[1 1 0]. Mg3TiO4 is identified to have cubic structure (lattice parameter a = 0.842 nm) with space group of Fd (3) over barm. (C) 2017 Elsevier B.V. All rights reserved.
METHOD AND SYSTEM FOR DATA TRANSMISSION
(2018-02-15)
Hsie-Chia Chang
;
Kuo-Kuang Yen
;
Yen-Chin Liao
A method and a system for data transmission are provided. The method includes: determining a size of a first block and a first degree distribution for a first data transmission according to a parameter which is related to a hardware specification of a receiving node; determining a channel loss rate of a channel between a sending note and the receiving node when completing the first data transmission; determining a size of a second block and a second degree distribution for a second data transmission according to the channel loss rate; and performing, by the sending node and the receiving node, the second data transmission according to the size of the second block and the second degree distribution.
Unveiling the hydrodechlorination of trichloroethylene by reduced graphene oxide supported bimetallic Fe/Ni nanoparticles
(2018-02-15)
Sahu, Rama Shanker
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Li, Dong-Lin
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
Reduced graphene oxide (rGO) is a promising support for electrochemical and environmental applications. However, the role of rGO in dechlorination of chlorinated hydrocarbon by zerovalent iron-based nanoparticles remains unclear. Herein, the rGO-supported bimetallic Fe/Ni nanocomposites were fabricated by chemical reduction method and the microstructures as well as the electrochemical properties of rGO/Fe/Ni, were investigated to elucidate the dechlorination behaviors of trichloroethylene (TCE) under various environmental conditions. Results show that the 10-60 nm Fe/Ni nanoparticles with average particle size of 32 nm are homogeneously dispersed onto the rGO surface. The rGO/Fe/Ni exhibits excellent dechlorination efficiency and rate of TCE is 2.4 times higher than that of free Fe/Ni nanoparticles. Cyclic voltammetric curves and electrochemical impedance spectra indicate that the superior dechlorination activity is attributed to the strong interaction between Fe/Ni and rGO, low internal resistance and rapid diffusion rate of electrons and ions. In addition, the capacitive behavior of rGO can store and transfer 2.7-3.4 electrons produced from Fe-0 to the adsorbed TCE more readily, and then converts TCE to non-toxic ethane via hydrodechlorination in the presence of Ni nanoparticles. The rGO/Fe/Ni can be recycled for at least 8 times to effective dechlorinate TCE. Moreover, the reaction rate of TCE dechlorination can be enhanced 1.26-1.49 times when 5-10 mg L-1 humic acid are added. Results obtained in this study have clearly unveiled the role of rGO in hydrodechlorination of TCE and can provide a new insight into the development of rGO-supported bimetallic Fe/Ni nanoparticles for the enhanced removal of chlorinated pollutants in water and wastewater treatment.
Discovery of a magnetic conductive interface in PbZr0.2Ti0.8O3 /SrTiO3 heterostructures
(2018-02-15)
Zhang, Yi
;
Xie, Lin
;
Kim, Jeongwoo
;
Stern, Alex
;
Wang, Hui
Emergent physical properties often arise at interfaces of complex oxide heterostructures due to the interplay between various degrees of freedom, especially those with polar dis-continuities. It is desirable to explore if these structures may generate pure and controllable spin currents, which are needed to attain unmatched performance and energy efficiency in the next-generation spintronic devices. Here we report the emergence of a spin-polarized two-dimensional electron gas (SP-2DEG) at the interface of two insulators, SrTiO3 and PbZr0.2Ti0.8O3. This SP-2DEG is strongly localized at the interfacial Ti atoms, due to the interplay between Coulomb interaction and band bending, and can be tuned by the ferroelectric polarization. Our findings open a door for engineering ferroelectric/insulator interfaces to create tunable ferroic orders for magnetoelectric device applications and provide opportunities for designing multiferroic materials in heterostructures.
資料傳輸方法與系統
(2018-02-16)
張錫嘉
;
顏國光
;
廖彥欽
本發明提出一種資料傳輸方法與系統。本方法包括：根據與接收端的硬體規格相關的參數，決定用於第一資料傳輸的第一區塊的大小以及第一度分佈；當第一資料傳輸完成時，判斷發送端與接收端之間的通道的通道漏失率；根據通道漏失率，決定用於第二資料傳輸的第二區塊的大小以及第二度分佈；以及藉由發送端與接收端根據第二區塊的大小以及第二度分佈進行第二資料傳輸。
Palladium/Light Induced Radical Alkenylation and Allylation of Alkyl Iodides Using Alkenyl and Allylic Sulfones
(2018-02-16)
Sumino, Shuhei
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Uno, Misae
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Huang, Hsin-Ju
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Wu, Yen-Ku
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Ryu, Ilhyong
Alkenylation and allylation of alkyl iodides with alkenyl and allyl sulfones, respectively, took place under Pd/photoirradiation system. The initial alkyl radical, derived from a single electron transfer between Pd(0) and RI, underwent the title transformations. Pd(0) was regenerated through a reductive elimination of PhSO2PdI, which is formed by the combination of the sulfonyl radical and the palladium radical. The addition of water was effective, presumably by pushing the equilibrium through hydrolysis of PhSO2I.
A general strategy for diverse syntheses of anhydrolandomycinone, tetrangulol, and landomycinone
(2018-02-21)
Sie, Cheng-Jhe
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Patteti, Venukumar
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Yang, Yi-Ru
;
Mong, Kwok-Kong Tony
;
應用化學系
A general synthetic strategy based on a protecting group-promoted CH arylation method was developed for total syntheses of anhydro-landomycinone (1), tetrangulol (2), and landomycinone (3) from the same set of starting materials.
Formation and identification of borane radical anions isolated in solid argon
(2018-02-21)
Lin, Meng-Yeh
;
Huang, Tzu-Ping
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Chin, Chih-Hao
;
Wu, Yu-Jong
;
應用化學系
The infrared (IR) spectrum of borane(3) anions (BH3-) isolated in solid Ar was recorded; two vibrational modes were observed at 2259.4 and 606.6 cm(-1), which were assigned to the BH2 stretching (nu(3)) and out-of-plane large-amplitude (nu(2)) modes, respectively. These anions were produced by the electron bombardment of an Ar matrix sample containing a small proportion of B2H6 and H-2 during matrix deposition or by the photolysis of single-bridged-B2H5 fi in an Ar matrix with the selected ultraviolet light. The band positions, relative intensity ratios, isotopic splitting pattern, and isotopic shift ratios of the observed IR features of BH3- are generally in good agreement with those predicted by the B2PLYP/aug-cc-pVTZ method.
Precise syntheses of structurally possible all tetrablock quaterpolymers by a methodology combining living anionic polymerization with linking chemistry using 1: 1 addition reaction
(2018-02-21)
Goseki, Raita
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Matsuo, Yuri
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Hirao, Akira
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應用化學系
;
Department of Applied Chemistry
A methodology combining living anionic polymerization with linking chemistry using 1 : 1 addition reaction has been developed for the syntheses of tetrablock quaterpolymers composed of A, B, C, and D blocks. With this methodology using the omega-chain-end-(alpha-phenylacrylate (PA))-functionalized D, alpha,omega-chain-end-(2-tetrahydropyranyl ether and PA)-functionalized D, and omega-chain-end-PA-functionalized AD as the building blocks, the following all structurally possible twelve tetrablock quaterpolymers were successfully synthesized: ABCD, ABDC, ACBD, ACDB, ADBC, ADCB, BACD, BADC, BCAD, BDAC, CABD, and CBAD. Polystyrene, poly(2-vinylpyridine), poly(tert-butyl methacrylate) (or poly(methyl methacrylate)), and poly(1,2-butylene oxide) prepared by living anionic polymerization were used as A, B, C, and D blocks, respectively. The polymers synthesized in this study are quite new tetrablock quaterpolymers and well-defined in structure.
Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization
(2018-02-21)
Weng, Jing-Ting
;
Yeh, Tso-Fan
;
Samuel, Ashok Zachariah
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Huang, Yi-Fan
;
Sie, Jyun-Hao
A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.26 nm were produced via co-assembling POSS-AD with hydrophilic liquids, such as H2O and HEMA in hydrophobic solvents. Taking the HEMA/POSS-AD cylindrical micelles as nano-reactors, polymerization of HEMA within the micelles results in polymer nano-cylinders (POSS-AD NPs) with a diameter of 2.24 nm and a length of 5.02 nm. The study confirmed that despite the inability to maintain specific shape in solution, low generation dendrimers form well-defined nano-containers or nano-reactors, which relies on co-assembling with hydrophilic guest molecules. These nano-reactors are robust enough to maintain their shape during the polymerization of the guest molecules. Polymer nano-cylinders with dimensions less than 10 nm can thus be produced from the HEMA/POSS-AD micelles. Since the chemical structure of low-generation dendrimers and the contents of the co-assembled nano-reactors can be easily adjusted, the concept holds the potential for the further developments of low-generation amphiphilic dendrimers.
Excited-state dissociation dynamics of phenol studied by a new time-resolved technique
(2018-02-21)
Lin, Yen-Cheng
;
Lee, Chin
;
Lee, Shih-Huang
;
Lee, Yin-Yu
;
Lee, Yuan T.
Phenol is an important model molecule for the theoretical and experimental investigation of dissociation in the multistate potential energy surfaces. Recent theoretical calculations [X. Xu et al., J. Am. Chem. Soc. 136, 16378 (2014)] suggest that the phenoxyl radical produced in both the X and A states from the O-H bond fission in phenol can contribute substantially to the slow component of photofragment translational energy distribution. However, current experimental techniques struggle to separate the contributions from different dissociation pathways. A new type of time-resolved pump-probe experiment is described that enables the selection of the products generated from a specific time window after molecules are excited by a pump laser pulse and can quantitatively characterize the translational energy distribution and branching ratio of each dissociation pathway. This method modifies conventional photofragment translational spectroscopy by reducing the acceptance angles of the detection region and changing the interaction region of the pump laser beam and the molecular beam along the molecular beam axis. The translational energy distributions and branching ratios of the phenoxyl radicals produced in the X, A, and B states from the photodissociation of phenol at 213 and 193 nm are reported. Unlike other techniques, this method has no interference from the undissociated hot molecules. It can ultimately become a standard pump-probe technique for the study of large molecule photodissociation in multistates. Published by AIP Publishing.
Latent Dirichlet mixture model
(2018-02-22)
Chien, Jen-Tzung
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Lee, Chao-Hsi
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Tan, Zheng-Hua
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電機工程學系
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Department of Electrical and Computer Engineering
Text representation based on latent topic model is seen as a non-Gaussian problem where the observed words and latent topics are multinomial variables and the topic proportionals are Dirichlet variables. Traditional topic model is established by introducing a single Dirichlet prior to characterize the topic proportionals. The words in a text document are represented by a random mixture of semantic topics. However, in real world, a single Dirichlet distribution may not faithfully reflect the variations of topic proportionals estimated from the heterogeneous documents. To address these variations, we propose a new latent variable model where latent topics and their proportionals are learned by incorporating the prior based on Dirichlet mixture model. The resulting latent Dirichlet mixture model (LDMM) is constructed for topic clustering as well as document clustering. Multiple Dirichlets provide a solution to build structural latent variables in learning representation over a variety of topics. This study carries out the inference for LDMM according to the variational Bayes and the collapsed variational Bayes. Such an unsupervised LDMM is further extended to a supervised LDMM for text classification. Experiments on document representation, summarization and classification show the merit of structural prior in LDMM topic models. (C) 2017 Elsevier B. V. All rights reserved.
Recent advances in machine learning for non-Gaussian data processing
(2018-02-22)
Ma, Zhanyu
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Chien, Jen-Tzung
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Tan, Zheng-Hua
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Song, Yi-Zhe
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Taghia, Jalil
WATER-SOLUBLE PEPTIDE FLUORESCENCE MATERIAL
(2018-02-22)
Hsin-Chieh LIN
;
Shu-Min HSU
A water-soluble peptide fluorescence material having a structure of formula (I):$$$$In formula (I), n is an integer greater than or equal to 1, R1 is independently selected from hydrogen or a nitrogen-containing functional group, R2 is independently selected from hydrogen or alkyl, and A1 is polymerized by at least one amino acid monomer and having a structure of formula (II):$$$$In formula (II), m is an integer greater than or equal to 1, and R3 in each, of the amino acid monomers of A1 is independently selected from hydrogen, alkyl, aralkyl, alkylthioaalkyl, hydroxyaralky, heteroaralkyl, carboxylalkyl, or guanidinylalkyl, A2 is —OR5 or —N(R4)2, and R4 is independently selected from hydrogen, alkyl, aralkyl, alkylthioaalkyl, hydroxyaralky, heteroaralkyl, carboxylalkyl, guanidinylalkyl, monoglycosyl, biglycosyl, or oligosaccharyl, and R5 is hydrogen, alkyl, aralkyl, alkylthioaalkyl, hydroxyaralky, heteroaralkyl, carboxylalkyl, or guanidinylalkyl.
The deformation behavior and fracture toughness of single crystal YSZ(111) by indentation
(2018-02-25)
Yen, Cheng-Yo
;
Jian, Sheng-Rui
;
Tseng, Yu-Chin
;
Juang, Jenh-Yih
;
電子物理學系
The nano-scale deformation behaviors and indentation-induced fracture features of the (111)-oriented yttrium-stabilized zirconia single crystal (YSZ(111)) were investigated by Berkovich and micro-Vicker indentations, respectively. The load-displacement curves in the Berkovich nano-indentation experiments evidently exhibited indentation-induced single "pop-in" phenomenon during loading, indicating that the nano-scale deformation in the YSZ(111) crystals is due primarily to the activities of dislocation nucleation and propagation. Based on this scenario, the number of nanoindentation-induced dislocation loops giving rise to the pop-in event was estimated to be around 2 x 10(5) with a critical radius of similar to 2 nm. The hardness and Young's modulus of YSZ(111) single crystal obtained by the continuous contact stiffness measurements (CSM) mode were 22.3 +/- 1.1 GPa and 270.6 +/- 8.5 GPa, consistent with those reported previously in the literature. In addition, the fracture toughness of YSZ(111) single crystal was estimated to be about 1.4-1.6 MPa m(1/2). (C) 2017 Elsevier B.V. All rights reserved.
Enhanced immersion cooling using two-tier micro- and nano-structures
(2018-02-25)
Hsu, Ya-Tzu
;
Li, Jia-Xiong
;
Lu, Ming-Chang
;
機械工程學系
;
Department of Mechanical Engineering
Continual increases in the functionality and miniaturization of electronic devices have resulted in a rapid increase in the power density of such devices. Thus, an efficient cooling technology is required to maximize heat dissipation and prevent electronic failure. Immersion cooling is a promising technique for the thermal management of high-power-density electronics. However, common working fluids in immersion cooling have high global warming potential, and the heat transfer performance of immersion cooling requires improvement to achieve efficient cooling of state-of-the-art high-power-density electronics. In this study, Novec 649, which has low global warming potential and a low boiling point, was applied as a working fluid for immersion cooling. A Si nanowire (SiNW) array, Si micropillar (SiMP) array, and Si nanowires on a Si micropillar (SiNW/MP) two-tier structure were employed to enhance boiling performance. The SiMP surface exhibited the highest critical heat flux (CHF) of 23.5 +/- 1.3 W/cm(2), whereas the SiNW surface exhibited the lowest CHF but a relatively high heat transfer coefficient (HTC). The SiNW/MP surface exhibited the highest HTC of 23611.7 +/- 1586.2 W/m(2) K and a relatively large CHF of 17.4 +/- 1.2 W/cm(2). Compared with a plain SiO2 surface, the CHF and HTC of the SiNW/MP two-tier structure could be enhanced by 30% and 455%, respectively. These results suggest that the SiNW/MP surface is effective for enhancing immersion cooling. (C) 2017 Elsevier Ltd. All rights reserved.
Relationship Between Earthquake b-Values and Crustal Stresses in a Young Orogenic Belt
(2018-02-28)
Wu, Yih-Min
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Chen, Sean Kuanhsiang
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Huang, Ting-Chung
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Huang, Hsin-Hua
;
Chao, Wei-An
It has been reported that earthquake b-values decrease linearly with the differential stresses in the continental crust and subduction zones. Here we report a regression-derived relation between earthquake b-values and crustal stresses using the Anderson fault parameter (A) in a young orogenic belt of Taiwan. This regression relation is well established by using a large and complete earthquake catalog for Taiwan. The data set consists of b-values and A values derived from relocated earthquakes and focal mechanisms, respectively. Our results show that b-values decrease linearly with the A values at crustal depths with a high correlation coefficient of -0.9. Thus, b-values could be used as stress indicators for orogenic belts. However, the state of stress is relatively well correlated with the surface geological setting with respect to earthquake b-values in Taiwan. Temporal variations in the b-value could constitute one of the main reasons for the spatial heterogeneity of b-values. We therefore suggest that b-values could be highly sensitive to temporal stress variations.
Zinc oxide-based current spreading layer behavior on the performance of P-side-up thin-film red light emitting diodes
(2018-02-28)
Tseng, Ming-Chun
;
Wuu, Dong-Sing
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Chen, Chi-Lu
;
Lee, Hsin-Ying
;
Horng, Ray-Hua
Transparent conductive layers deposited on a GaP window layer were used to fabricate high-brightness p-side-up thin-film AlGaInP light emitting diodes (LEDs). Zinc oxide (ZnO) and aluminum-doped zinc oxide (ZAO) with an Zn:Al cycle ratio of 20:1 were grown by atomic layer deposition for comparison. The ZAO thin films reduced the droop in the external quantum efficiencies of the LEDs as well as the junction temperature, which result in increases in the light output power and thermal stability of the LEDs. The efficiency droops of the LEDs with the ZnO and ZAO thin films were 41% and 15%, respectively. The junction temperature of the LED with the ZAO thin film can be reduced to 39.6 degrees C at an injection current of 700 mA, which is lower than that of the LED with the ZnO thin film (58.1 degrees C). The above results are promising for the development of ZAO thin films for applications in AlGaInP LEDs. (C) 2017 Elsevier B.V. All rights reserved.
Microstructure evolution determined by the crystalline phases competition in self-assembled WO3-BiVO4 hetero nanostructures
(2018-02-28)
Song, Haili
;
Li, Chao
;
Chien Nguyen Van
;
Dong, Wenxia
;
Qi, Ruijuan
A series of self-assembled WO3-BiVO4 nanostructured thin films were grown on the (001) yttria-stabilized zirconia (YSZ) substrate at the substrate temperatures of 400 degrees C, 500 degrees C, 550 degrees C, 600 degrees C, 650 degrees C and 700 degrees C by a pulsed laser deposition method. The microstructures including crystalline phases, epitaxial relationships, surface morphologies and interface structures were investigated by a combination of x-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The sample grown at 400 degrees C was amorphous due to the low driving forces for nucleation and diffusion. For the samples made at 500 degrees C, 550 degrees C and 600 degrees C, the monoclinic BiVO4 matrix epitaxially grew on YSZ, forming the matrix, where the WO3 nanopillars were embedded in with a specific orientation relationship among BiVO4, WO3 and YSZ. However, in thin films deposited at 650 degrees C and 700 degrees C, the WO3 grains randomly grew on the YSZ substrate, which dominated the microstructures of the resultant thin films. Quantitative analyses of the microstructures revealed that the lateral grain sizes of BiVO4 and WO3 increased and the volume fraction of BiVO4 in the thin films decreased with the increase of the deposition temperature. A three-regime growth mechanism of the WO3-BiVO4 composite thin film was proposed based on the growth dynamics determined by the competition between BiVO4 and WO3. Published by AIP Publishing.
Ultrafast intersystem crossing for nitrophenols: ab initio nonadiabatic molecular dynamics simulation
(2018-02-28)
Xu, Chao
;
Gu, Feng Long
;
Zhu, Chaoyuan
;
應用化學系
;
應用化學系分子科學碩博班
Ultrafast intersystem crossing mechanisms for two p- and m-nitrophenol groups (PNP and MNP) have been investigated using ab initio nonadiabatic molecular dynamics simulations at the 6SA-CASSCF level of theory. Trajectory surface hopping simulation has been performed within an intersystem crossing network constructed from two low-lying singlets (S-0 and S-1) and two low-lying triplets (T-1 and T-2). It is found that the dominant relaxation S-1 -> T-2 pathway accounts for 65.4% (85.0%) of the quantum yield with a time constant of 13.4 fs (22 fs) and the S-1 -> T-2 -> S-0 pathway accounts for 33.1% (13.5%) with a time constant of 275 fs ( 375 fs) for PNP ( MNP). In comparison with the previously studied excited-state proton transfer process for ONP, the dominant relaxation S-1 -> T-2 -> T-1 pathway accounts for 49.3% with a time constant of 40 fs and the S-1 -> T-2 -> T-1 -> S-0 pathway accounts for 47.5% with a time constant of 300 fs. The relaxation mechanisms and electronic structures of the intersystem crossings are in close relation with the relative motion between the torsion motions of the nitro-group and the hydroxyl group. The present simulation provides new physical insight for understanding ultrafast photochemical intersystem crossing dynamics.