Browsing by Issue Date, starting with "2016-08-09"

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Novel Water-Soluble Cyclodextrin-Based Conjugated Polymer for Selective Host-Guest Interactions of Cationic Surfactant CTAB and Reverse FRET with Rhodamine B Tagged Adamantyl Guest
(2016-08-09)
Dwivedi, Atul Kumar
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Singh, Ravinder
;
Singh, Ashutosh
;
Wei, Kung-Hwa
;
Wu, Chu-Ya
A new water-soluble pi-conjugated main-chain polymer P1 bearing a beta-cyclodextrin (beta-CD) pendant was designed and synthesized. The aggregation and disaggregation of P1 generated faded yellow-greenish and bright-yellow emissions, respectively. The inclusion complexation capability of P1 through beta-CD pendant with a cationic surfactant cetyltrimethylammonium bromide (CTAB) guest and associative interactions of P1 with Fe3+ through triazole spacers resulted in significantly enhanced and completely diminished emission profiles of P1 in pure water, respectively. Interestingly, ADRhB as another rhodamine B (RhB) tagged adamantyl guest was transformed into ADRhB(0), i.e., the open form of ADRhB, to generate RhB emission in the presence of Fe3+ ion selectively for the pendent host beta-CD of PI, and the further interaction of.ADRhB(0)/Fe3+ with P1 prevailed a completely quenched RhB emission via the inclusion complexation of adamantyl terminal of ADRhB (0) in beta-CD. Moreover, stronger interactions of CTAB with beta-CD further generated RhB emission of ADRhB(0) even in the presence of acceptor Pl. Finally, a novel beta-CD bearing water-soluble P1 with selective and strong interactions of CTAB toward disaggregation events in pure water, and further electrostatic repulsion and utilization of RhB via RhB-tagged adamantyl guest ADRhB(0) as a donor revealed the reverse fluorescence resonance energy transfer (FRET) process of P1.
Functional Supramolecular Polypeptides Involving pi-pi Stacking and Strong Hydrogen-Bonding Interactions: A Conformation Study toward Carbon Nanotubes (CNTs) Dispersion
(2016-08-09)
Huang, Cheng-Wei
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Mohamed, Mohamed Gamal
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Zhu, Chao-Yuan
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Kuo, Shiao-Wei
;
應用化學系
New supramolecular polypeptides have been prepared through simple ring-opening polymerization and "click" reactions. Postfunctionalization with diaminopyridine (DAP) moieties, capable of multiple hydrogen bonding, was an efficient approach toward forming a-helical-dominant polypeptides. The physically cross-linked networks produced upon self-organization of the DAP units increased the glass transition temperature (T-g) of the polymers and sustained the secondary structures of the polypeptides. Additional thermal responsivity resulted from dynamic noncovalent bonding on the polymer side chains. Molecular recognition through heterocomplementary DAP thymine (T) base pairs was revealed spectroscopically and then used to construct poly(y-propargylL-glutamate)-g-N-(6-acetamidopyridin-2-y1)-11-undecanamide/thyminylpyrene (PPLG-DAP/Py-T) supramolecular complexes. Transmission electron microscopy images revealed that this complex was an efficient dispersant of carbon nanotubes (CNTs). Indeed, it could disperse CNTs in both polar and nonpolar media, the direct result of combining two modes of secondary noncovalent bonding: multiple hydrogen bonding and pi-pi interactions. Furthermore, CNT composites fabricated with biocompatible polymers and high value of T-g should enable the development of bio-inspired carbon nanostructures and lead the way toward their biomedical applications.
Packing Principles for Donor-Acceptor Oligomers from Analysis of Single Crystals
(2016-08-09)
Huang, Chi-Feng
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Wu, San-Lien
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Huang, Yi-Fan
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Chen, Ying-Chen
;
Chang, Shu-Ting
D-A conjugated molecules are complicated in both their molecular and their packing structures. In this perspective, we summarize more than 40 crystal lattices of conjugated oligomers to identify the morphological influence of each building block on the D-A molecules. These lattice structures reveal not only the packing preferences of the conjugated oligomers but also the conformational disorder in the lattices. The presence of this disorder in slowly grown crystals implies that attaining total long-range conformational order is challenging for D-A oligomers, which are structurally complicated and readily distorted and which have building blocks of incommensurate packing dimensions. In optoelectronic applications, a decreased duration of processing can prevent ordering and trap the thin films of D-A oligomers from becoming crystalline phases. Although D-A oligomers conform to packing principles in the formation of a single crystal, their phase behaviors in the formation of active thin films are much more difficult to comprehend. Continuous advances in methods of characterization are still strongly required for the steps of attaining a true structure property relation of D-A oligomers in active films for optoelectronic applications.
Anti-Hyperglycemic Agents and New-Onset Acute Myocardial Infarction in Diabetic Patients with End-Stage Renal Disease Undergoing Dialysis
(2016-08-11)
Lin, Ting-Tse
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Wu, Chih-Chen
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Yang, Yao-Hsu
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Lin, Lian-Yu
;
Lin, Jiunn-Lee
Background Diabetes and chronic kidney disease (CKD) are a high-stakes combination for cardiovascular disease. Patients with decreased kidney function and end-stage renal disease ( ESRD) have increased risk of hypoglycemia when attaining better glycemic control, leading to higher risk of myocardial infarction (MI). For these patients, which kinds of anti-hyperglycemic agents would be associated with higher risk of MI is not clear. Methods We identified patients from a nation-wide database called Registry for Catastrophic Illness, which encompassed almost 100% of the patients receiving dialysis therapy in Taiwan from 1995 to 2008. Patients with diabetes and ESRD were selected as the study cohort. Propensity score adjustment and Cox's proportional hazards regression model were used to estimate the hazard ratios (HRs) for new-onset MI. Results Among 15,161 patients, 39% received insulin, 40% received sulfonylureas, 18% received meglitinides and 3% received thiazolidinedione (TZD). After a median follow-up of 1,357 days, the incidence of MI was significant increase in patients taking sulfonylureas (HR =1.523, 95% confidence interval [CI]=1.331-1.744), meglitinides ( HR=1.251, 95% CI=1.048-1.494) and TZD (HR=1.515, 95% CI=1.071-2.145) by using patients receiving insulin therapy as the reference group. The risk of MI remains higher in other three groups in subgroup analyses. Conclusions In conclusion, among diabetic patients with ESRD undergoing dialysis, the use of sulfonylureas, meglitinides and TZD are associated with higher risk of new-onset MI as compared with insulin.
Determination of the total absorption peak in an electromagnetic calorimeter
(2016-08-11)
Cheng, Jia-Hua
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Wang, Zhe
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Lebanowski, Logan
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Lin, Guey-Lin
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Chen, Shaomin
A physically motivated function was developed to accurately determine the total absorption peak in an electromagnetic calorimeter and to overcome biases present in many commonly used methods. The function is the convolution of a detector resolution function with the sum of a delta function, which represents the complete absorption of energy, and a tail function, which describes the partial absorption of energy and depends on the detector materials and structures. Its performance was tested with the simulation of three typical cases. The accuracy of the extracted peak value, resolution, and peak area was improved by an order of magnitude on average, relative to the Crystal Ball function. (C) 2016 Elsevier B.V. All rights reserved.
Photoinduced diffusion molecular transport
(2016-08-14)
Rozenbaum, Viktor M.
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Dekhtyar, Marina L.
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Lin, Sheng Hsien
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Trakhtenberg, Leonid I.
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應用化學系
We consider a Brownian photomotor, namely, the directed motion of a nanoparticle in an asymmetric periodic potential under the action of periodic rectangular resonant laser pulses which cause charge redistribution in the particle. Based on the kinetics for the photoinduced electron redistribution between two or three energy levels of the particle, the time dependence of its potential energy is derived and the average directed velocity is calculated in the high-temperature approximation (when the spatial amplitude of potential energy fluctuations is small relative to the thermal energy). The thus developed theory of photoinduced molecular transport appears applicable not only to conventional dichotomous Brownian motors (with only two possible potential profiles) but also to a much wider variety of molecular nanomachines. The distinction between the realistic time dependence of the potential energy and that for a dichotomous process (a step function) is represented in terms of relaxation times (they can differ on the time intervals of the dichotomous process). As shown, a Brownian photomotor has the maximum average directed velocity at (i) large laser pulse intensities (resulting in short relaxation times on laser-on intervals) and (ii) excited state lifetimes long enough to permit efficient photoexcitation but still much shorter than laser-off intervals. A Brownian photomotor with optimized parameters is exemplified by a cylindrically shaped semiconductor nanocluster which moves directly along a polar substrate due to periodically photoinduced dipole moment (caused by the repetitive excited electron transitions to a non-resonant level of the nanocylinder surface impurity). Published by AIP Publishing.
A crossover adjustment for improving sea surface height mapping from in-situ high rate ship-borne GNSS data using PPP technique
(2016-08-15)
Guo, Jinyun
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Dong, Zhenghua
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Tan, Zhengguang
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Liu, Xin
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Chen, Chuanfa
Ship-borne global navigation satellite system (GNSS) technique can overcome the weakness of satellite altimetry and tide gauge in measuring sea surface heights (SSHs) over coastal seas. Ship-borne GNSS technique can be used to calibrate SSHs determined by the satellite altimetry and tide gauge. The ship borne GNSS data are processed with the single-epoch precise point positioning (PPP) method to estimate SSHs which are filtered by the Gaussian filter to weaken and/or remove effects of sea wind and wave field. Tidal corrections are also taken into consideration to improve SSHs. One crossover adjustment method is put forward to calculate the bias and drift along the ship route and assess the accuracy of SSHs. We processed the in-situ ship-borne GPS data over the offshore sea around Keelung to compute precisely SSHs with the single-epoch PPP. Statistical results of SSH differences of crossover points indicate that the root mean squares error of SSHs determined by the ship-borne GPS is up to level of 12.9 cm over the offshore sea similar to 30 km far away to land. (C) 2016 Elsevier Ltd. All rights reserved.
用於製備氫氣之觸媒及其製法
(2016-08-16)
李積琛
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蔡品雯
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謝和諶
;
陳昀聲
;
張原嘉
一種用於製備氫氣之觸媒及其製法，該製法係包括於包含界面活性劑之第一有機溶劑中加入第一金屬源、第二金屬源、第三金屬源及鈰源，以形成膠體混合物，其中，該第一金屬源之金屬係IIIB族金屬，該第二金屬源之金屬係選自鹼金屬、鹼土金屬及IIIB族金屬所組成群組之其中一者，該第三金屬源係過渡金屬；?燒該膠體混合物，以形成金屬固溶體；以及使載體承載該金屬固溶體，以得到該觸媒。將本發明所製備之觸媒用於乙醇氧化重組時，能使該乙醇氧化重組的反應溫度明顯下降，且該觸媒經長時間使用後，該乙醇氧化重組仍維持在高的乙醇轉換率及氫氣選擇率，顯示出該觸媒具有長時間使用的穩定性。
A study on the plating and wetting ability of ruthenium-tungsten multi-layers for advanced Cu metallization
(2016-08-16)
Kuo, Tai-Chen
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Su, Yin-Hsien
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Lee, Wen-Hsi
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Liao, Wei-Hsiang
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Wang, Yu-Sheng
In this study, the plating and wetting ability of Cu/Ruthenium-Tungsten (RuW)/silicon oxide (SiO2) multi-layer stacks were investigated. RuW alloy films were prepared on a SiO2 layer by sputtering, followed by a deposition of a Cu thin film by electro-plating. Scanning electron microscopy (SEM) top view images shows that Cu films can be electroplated on RuW, with smaller Cu nuclei size but in a more highly concentrated and uniform distribution than Cu films electroplated on Ta or TaN. The rate of Cu nucleation decreases and larger Cu clusters were formed on the RuW alloy films with increasing W content. Cu/RuW/SiO2 samples were annealed at 400 degrees C for 30 min and then characterized using SEM. There were fewer pin holes on the surface of a pure Cu/Ru stack compared to Cu/RuW multilayers. Cu/RuW/SiO2 multi -layers had fewer pin holes than Cu/Ta/SiO2 structures processed under similar conditions. The wetting angle, measured by SEM, of Cu on a RuW substrate (43) was still lower than that of Cu on a Ta substrate (123 degrees), which suggests that the adhesion strength of Cu onto RuW alloy is better than that onto Ta. Preliminary studies of Cu diffusion through 25 nm RuW layers at 650 degrees C showed no Cu penetration into the underlying Si in a Cu/RuW/Si multi-layer test structure. (C) 2016 Elsevier B.V. All rights reserved.
Scalable Patterning of MoS2 Nanoribbons by Micromolding in Capillaries
(2016-08-17)
Hung, Yu-Han
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Lu, Ang-Yu
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Chang, Yung-Huang
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Huang, Jing-Kai
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Chang, Jeng-Kuei
In this study, we report a facile approach to prepare dense arrays of MoS2 nanoribbons by combining procedures. of micromolding in capillaries (MIMIC) and thermolysis of thiosalts ((NH4)(2)MoS4) as the printing ink. The obtained MoS2 nanoribbons had a "thickness reaching as. low as 3.9 nm, a width ranging from 157 to 465 nm, and a length up to 2 cm. MoS2 nanoribbons with an extremely high aspect ratio (lengthiwidtfi) of similar to 7.4 X 10(8) were achieved. The MoS2 pattern can be printed on versatile substrates, such as SiO2/Si, sapphire, Au film, FTO/glass, and graphene-coated glass. The degree of crystallinity of the as-prepared MoS2 was discovered to be adjustable by varying the temperature through postannealing. The high-temperature thermolysis (1000 degrees C) results in high-quality conductive samples, and field-effect transistors, based on the patterned MoS2 nanoribbons were demonstrated and characterized, where the carrier mobility was comparable to that of thin-film MoS2. In contrast, the low-temperature-treated samples (170 degrees C) result in a unique nanocrystalline MOSx structure (x approximate to 2.5), where the abundant and exposed edge sites were obtained from highly dense arrays of nanoribbon structures by this MIMIC patterning method,: The patterned MoSx was revealed to have superior electrocatalytic efficiency (an overpotential of similar to 211 mV at 10 mA/cm(2) and a Tafel slope of 43 mV/dec) in the hydrogen evolution reaction (HER) when compared to the thin-film MoS2. The report introduces a new concept for rapidly fabricating cost-effective and high-density MoS2/MoSx natiostructures on versatile substrates, which may pave the way for potential applications in nanoelectronics/optoelectronics and frontier energy materials.
Coherent acoustic phonon oscillation accompanied with backward acoustic pulse below exciton resonance in a ZnO epifilm on oxide-buffered Si(111)
(2016-08-17)
Lin, Ja-Hon
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Shen, Yu-Kai
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Liu, Wei-Rein
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Lu, Chia-Hui
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Chen, Yao-Hui
Unlike coherent acoustic phonons (CAPs) generated from heat induced thermal stress by the coated Au film, we demonstrated the oscillation from c-ZnO epitaxial film on oxide buffered Si through a degenerate pump-probe technique. As the excited photon energy was set below the exciton resonance, the electronic stress that resulted from defect resonance was used to induce acoustic wave. The damped oscillation revealed a superposition of a high frequency and long decay CAP signal with a backward propagating acoustic pulse which was generated by the absorption of the penetrated pump beam at the Si surface and selected by the ZnO layer as the acoustic resonator.
Highly Sensitive and Selective Detection of Nanomolar Ferric Ions Using Dopamine Functionalized Graphene Quantum Dots
(2016-08-17)
Chowdhury, Ankan Dutta
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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
The good stability, low cytotoxicity, and excellent photoluminescence property of graphene quantum dots (GQDs) make them an emerging class of promising materials in various application fields ranging from sensor to drug delivery. In the present work, the dopamine-functionalized GQDs (DA-GQDs) with stably bright blue fluorescence were successfully synthesized for low level Fe3+-ions detection. The as-synthesized GQDs are uniform in size with narrow-distributed particle size of 4.5 +/- 0.6 nm and high quantum yield of 10.2%. The amide linkage of GQDs with dopamine, confirmed by using XPS and FTIR spectra, results in the specific interaction between Fe3+ and catechol moiety of dopamine at the interfaces for highly sensitive and selective detection of Fe3+. A linear range of 20 nM to 2 mu M with a detection limit of 7.6 nM is obtained for Fe3+ detection by DA-GQDs. The selectivity of DA-GQDs sensing probe is significantly excellent in the presence of other interfering metal ions. In addition, the reaction mechanism for Fe3+ detection based on the complexation and oxidation of dopamine has been proposed and validated. Results obtained in this study clearly demonstrate the superiority of surface functionalized GQDs to Fe3+ detection, which can pave an avenue for the development of high performance and robust sensing probes for detection of metal ions and other organic metabolites in environmental and biomedical applications.
Photocreating supercooled spiral-spin states in a multiferroic manganite
(2016-08-18)
Sheu, Y. M.
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Ogawa, N.
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Kaneko, Y.
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Tokura, Y.
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電子物理學系
We demonstrate that the dynamics of the ab-spiral-spin order in a magnetoelectric multiferroic Eu0.55Y0.45MnO3 can be unambiguously probed through optical second harmonic signals, generated via spin-induced ferroelectric polarization. In the case of weak excitation, the ferroelectric and the spiral-spin order remains interlocked, both relaxing through spin-lattice relaxation in the nonequilibrium state. When the additional optical pulse illuminating the sample is intense enough to induce a local phase transition thermally, the system creates ametastable state of the bc-spiral-spin order (with the electric polarization P parallel to c) via supercooling across the first-order phase transition between the ab and bc spiral. The supercooled state of the bc-spiral spin is formed in the thermodynamical ground state of the ab spiral (P parallel to a), displaying a prolonged lifetime with strong dependence on the magnetic field along the a axis. The observed phenomena provide a different paradigm for photoswitching between the two distinct multiferroic states, motivating further research into a direct observation of the photocreated supercooled bc-spiral spin in multiferroic manganites.
Nanochips of Tantalum Oxide Nanodots as artificial-microenvironments for monitoring Ovarian cancer progressiveness
(2016-08-18)
Dhawan, Udesh
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Wang, Ssu-Meng
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Chu, Ying Hao
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Huang, Guewha S.
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Lin, Yan Ren
Nanotopography modulates cell characteristics and cell behavior. Nanotopological cues can be exploited to investigate the in-vivo modulation of cell characteristics by the cellular microenvironment. However, the studies explaining the modulation of tumor cell characteristics and identifying the transition step in cancer progressiveness are scarce. Here, we engineered nanochips comprising of Tantalum oxide nanodot arrays of 10, 50, 100 and 200 nm as artificial microenvironments to study the modulation of cancer cell behavior. Clinical samples of different types of Ovarian cancer at different stages were obtained, primary cultures were established and then seeded on different nanochips. Immunofluorescence (IF) was performed to compare the morphologies and cell characteristics. Indices corresponding to cell characteristics were defined. A statistical comparison of the cell characteristics in response to the nanochips was performed. The cells displayed differential growth parameters. Morphology, Viability, focal adhesions, microfilament bundles and cell area were modulated by the nanochips which can be used as a measure to study the cancer progressiveness. The ease of fabrication of nanochips ensures mass-production. The ability of the nanochips to act as artificial microenvironments and modulate cell behavior may lead to further prospects in the markerless monitoring of the progressiveness and ultimately, improving the prognosis of Ovarian cancer.
Infrared Spectroscopic Investigation of the Acidic CH Bonds in Cationic n-Alkanes: Pentane, Hexane, and Heptane
(2016-08-18)
Xie, Min
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Matsuda, Yoshiyuki
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Fujii, Asuka
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應用化學系
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應用化學系分子科學碩博班
Radical cations of n-alkanes (pentane, hexane, and heptane) in the gas phase are investigated by infrared predissociation spectroscopy with the argon Or nitrogen tagging. All-trans and gauche-involving conformers are identified for these cations by comparisons of observed infrared spectra and vibrational simulations. Intense CH stretch bands are observed in the frequency region lower than the normal alkyl CH stretch frequency. These low frequencies and high intensities of the CH stretch bands are caused by the CH bond weakening and the enhanced positive charge of the hydrogen atoms through the delocalization of the sigma electron in the CH bonds. These effects of the delocalization of the a electron result in the enhanced acidity of the CH bonds. The conformation as well as alkyl chain length dependence of the acidity of the CH bonds is demonstrated by the CH stretch frequency shift trend.
Humidity-switch chromism of aniline-pentamer in Nafion
(2016-08-19)
Lin, Yen-Hao
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Hsiao, Yu-Sheng
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Lu, Hsiao-Chi
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Chen, Peilin
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Whang, Wha-Tzong
Aniline-pentamer (AP) in Nafion triggered with humidity content displays an interesting chromism from blue to pink, which is much wider of color shift than general polyaniline. Thermogravimetric analysis confirms the reversal color change related to the moisture content in the sample. IR absorption spectra make known AP having high degree of protonation at lower water content. UV-Vis absorption expose the chromism process having something more than just protonation. The change of electronic energy levels and PL spectra reveal that there must be a complex interaction in NaAP. Raman scattering mapping confirms that drying causes the - SO3- hydrophilic channels transforming to isolated domains dispersed in matrix, which induces heavy protonation and complexation of AP with - SO3- groups. We can infer that the interesting humidity-switch chromism is due to the reversible protonation/deprotonation as well as complexation of AP with - SO3- groups through the reversible change of Nafion\'s morphology.
Status and Prospects of ZnO-Based Resistive Switching Memory Devices
(2016-08-19)
Simanjuntak, Firman Mangasa
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Panda, Debashis
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Wei, Kung-Hwa
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Tseng, Tseung-Yuen
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材料科學與工程學系
In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.
Green synthesis of multifunctional mesoporous composites from display panel glasses for selective adsorption of metal ions
(2016-08-20)
Tsai, Cheng Kuo
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Doong, Ruey-an
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Hung, Huan-Yi
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環境工程研究所
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Institute of Environmental Engineering
Ultrathin flexible silicon photodetector with silver nanowires plasmonic structure for chemiluminescence sensing
(2016-08-20)
Liu, Lai-Yi
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Lin, Ching-Chnag
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Liu, Shuenyu
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Sun, Wen-Hsien
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Cheng, Chieh
Fabrication of alpha-MnO2 nano-particle and nano-rod composite electrodes for capacitive deionization
(2016-08-20)
Chen, Yi-Han
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Juang, Yaju
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Huang, Chihpin
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環境工程研究所
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Institute of Environmental Engineering