Browsing by Issue Date, starting with "2016-09-15"

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CRP-Cyclic AMP Regulates the Expression of Type 3 Fimbriae via Cyclic di-GMP in Klebsiella pneumoniae
(2016-09-15)
Lin, Ching-Ting
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Lin, Tien-Huang
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Wu, Chien-Chen
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Wan, Lei
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Huang, Chun-Fa
Klebsiella pneumoniae is the predominant pathogen isolated from liver abscesses of diabetic patients in Asian countries. However, the effects of elevated blood glucose levels on the virulence of this pathogen remain largely unknown. Type 3 fimbriae, encoded by the mrkABCDF genes, are important virulence factors in K. pneumoniae pathogenesis. In this study, the effects of exogenous glucose and the intracellular cyclic AMP (cAMP) signaling pathway on type 3 fimbriae expression regulation were investigated. The production of MrkA, the major subunit of type 3 fimbriae, was increased in glucose-rich medium, whereas cAMP supplementation reversed the effect. MrkA production was markedly increased by cyaA or crp deletion, but slightly decreased by cpdA deletion. In addition, the mRNA levels of mrkABCDF genes and the activity of P-mrkA were increased in Delta crp strain, as well as the mRNA levels of mrkHIJ genes that encode cyclic di-GMP (c-di-GMP)-related regulatory proteins that influence type 3 fimbriae expression. Moreover, the activities of P-mrkHI and P-mrkJ were decreased in Delta lacZ Delta crp strain. These results indicate that CRP-cAMP down-regulates mrkABCDF and mrkHIJ at the transcriptional level. Further deletion of mrkH or mrkI in Delta crp strain diminished the production of MrkA, indicating that MrkH and MrkI are required for the CRP regulation of type 3 fimbriae expression. Furthermore, the high activity of P-mrkHI in the Delta lacZ Delta crp strain was diminished in Delta lacZ Delta crp Delta mrkHI, but increased in the Delta lacZ Delta crp Delta mrkJ strain. Deletion of crp increased the intracellular c-di-GMP concentration and reduced the phosphodiesterase activity. Moreover, we found that the mRNA levels of multiple genes related to c-di-GMP metabolism were altered in Delta crp strain. These indicate that CRP regulates type 3 fimbriae expression indirectly via the c-di-GMP signaling pathway. In conclusion, we found evidence of a coordinated regulation of type 3 fimbriae expression by the CRP-cAMP and c-di-GMP signaling pathways in K. pneumoniae.
Nanomechanical, structural, and transport properties of Bi3Se2Te thin films
(2016-09-15)
Phuoc Huu Le
;
Chiu, Shao-Pin
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Jian, Sheng-Rui
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Luo, Chih Wei
;
Lin, Jiunn-Yuan
New ternary phase of Bi3Se2Te thin films were successfully grown through pulsed laser deposition with a single Bi2Se2Te crystal as the target. Bi-rich and Se-and Te-deficient compositions deposited at a substrate temperature (T-s) of 250 degrees C and helium gas pressures (P-He) ranging from 2.0 x 10(-5) to 6.5 x 10(-1) Torr aided the formation of the dominant Bi-rich phase: Bi3Se2Te. The films were grown epitaxially on Al2O3 (001) substrates with Bi3Se2Te [001]//Al2O3 [001] and Bi3Se2Te [110]//Al2O3 [210]. An increase in P-He remarkably enhanced the hardness and Young\'s modulus of the films, primarily because of the decrease in nanograin size, following the HallePetch relationship. Moreover, the Bi3Se2Te films present linear magnetoresistance under a high perpendicular magnetic field (B >= 4 T) and twodimensional weak antilocalization effect under a low B (+/- 1 T) which may be attributed to topological insulator surface state (TSS). Clearly, further theoretical calculations and experiments are needed to confirm the suggested interpretation. (C) 2016 Elsevier B.V. All rights reserved.
Oxygen Vacancy in Hafnia as a Blue Luminescence Center and a Trap of Charge Carriers
(2016-09-15)
Gritsenko, Vladimir A.
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Islamov, Damir R.
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Perevalov, Timofey V.
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Aliev, Vladimir Sh.
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Yelisseyev, Alexander P.
The electronic properties of HfO2, in particular, luminescence and charge transport, are determined by defects and traps. The origin of luminescence centers and traps of charge carriers in a HfO2 crystal was studied using luminescence spectroscopy, charge transport, and quantum chemical calculation. The 2.7 eV luminescence band and 5.2 eV absorption/luminescence excitation band are associated with an oxygen vacancy. The thermal activation energy 1.25 eV, estimated from the charge transport and thermoluminescence experiment, is equal to half of the Stokes shift in photoluminescence spectra. Hence, oxygen vacancies are supposed to operate as electron traps in HfO2, and the charge transport is described by phonon-assisted tunneling between traps.
Study of electromigration-induced formation of discrete voids in flip-chip solder joints by in-situ 3D laminography observation and finite-element modeling
(2016-09-15)
Chang, Yuan-Wei
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Cheng, Yin
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Xu, Feng
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Helfen, Lukas
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Tian, Tian
In the microelectronics industry the flip-chip (FC) technology is broadly used to enhance the packaging density. However, the small size and the unique geometry of the FC solder joints induce the electro-migration (EM) reliability issue. In this study, a pair of lead-free solder joints (SAC1205) was EM tested by a current of 7.5 x 10(3) A/cm(2). During the tests, X-ray laminography was applied to observe the microstructure evolution in-situ. Laminography enables the non-destructive observation of the bump microstructure and allows for a quantitative three-dimensional (3D) analysis. After EM testing for 650 h, a new EM failure mechanism was found, differing from the two well-known models, the pancake void propagation and the under-bump-metallization dissolution. Here, a few pre-existing small voids grew and simultaneously many new voids formed and grew over the entire EM testing period. Most of the nucleating voids were distributed in the current crowding region, a few also located in the low-current density region. As the testing time increased, voids increasingly coalesced with each other, forming a porous network which occupied a large part of the interface area and caused the EM failure. A finite element (FE) method was then applied to analyze the interplay between the microstructure evolution and current density redistribution. A series of 3D FE models was built based on the laminography images for the different testing stages. The current density distribution from the FE analysis indicates that the formation of discrete voids did not affect the global current density distribution until a major coalescence of the voids occurred. The relieving of the global current crowding in the pancake void model was not found in this new EM failure mechanism. It was the local current crowding around individual void found in the new mechanism that is held responsible for the EM retardation. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
製備高分子球的方法
(2016-09-16)
陳俊太
;
邱俞靜
;
張鈞?
製備高分子球的方法，包含將高分子溶液塗佈於基板上以形成高分子薄膜。接著，將高分子薄膜置於非溶劑中進行熱退火處理，使高分子薄膜形變成複數個高分子球。非溶劑不溶解高分子，且沸點高於高分子之玻璃轉化溫度。熱退火處理係在高於高分子之玻璃轉化溫度且低於非溶劑之沸點下進行，且熱退火處理的時間約為1~180分鐘。
薄型平面生醫感測器
(2016-09-16)
林進燈
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游奕欣
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呂紹瑋
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廖倫德
一種薄型平面生醫感測器，其係包括至少一用以接觸受測者之皮膚，以量測其生醫訊號之可撓性電極。此種可撓性電極係以矽膠銀玻璃導電材質製成，且矽膠與銀玻璃組成比例係為七比三。導電薄板係電性連接該可撓性電極，一緩衝層係包覆該可撓性電極與導電薄板，且一電路基板係可接收測得之生醫訊號。利用此種創新之薄型平面生醫感測器，不僅可應用於生醫訊號的量測，由於電極更兼具有輕、薄、可彎曲、導電性佳且不誘發皮膚過敏之特性，有別於已知之濕式電極與微結構乾式電極，用以量測腦波、心電、肌電、眼動等生醫訊號，實具有極佳之發展潛力與產業利用性。
A Comparison of Independent Event-Related Desynchronization Responses in Motor-Related Brain Areas to Movement Execution, Movement Imagery, and Movement Observation
(2016-09-16)
Duann, Jeng-Ren
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Chiou, Jin-Chern
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Electroencephalographic (EEG) event-related desynchronization (ERD) induced by movement imagery or by observing biological movements performed by someone else has recently been used extensively for brain-computer interface-based applications, such as applications used in stroke rehabilitation training and motor skill learning. However, the ERD responses induced by the movement imagery and observation might not be as reliable as the ERD responses induced by movement execution. Given that studies on the reliability of the EEG ERD responses induced by these activities are still lacking, here we conducted an EEG experiment with movement imagery, movement observation, and movement execution, performed multiple times each in a pseudorandomized order in the same experimental runs. Then, independent component analysis (ICA) was applied to the EEG data to find the common motor-related EEG source activity shared by the three motor tasks. Finally, conditional EEG ERD responses associated with the three movement conditions were computed and compared. Among the three motor conditions, the EEG ERD responses induced by motor execution revealed the alpha power suppression with highest strengths and longest durations. The ERD responses of the movement imagery and movement observation only partially resembled the ERD pattern of the movement execution condition, with slightly better detectability for the ERD responses associated with the movement imagery and faster ERD responses for movement observation. This may indicate different levels of involvement in the same motor-related brain circuits during different movement conditions. In addition, because the resulting conditional EEG ERD responses from the ICA preprocessing came with minimal contamination from the non-related and/or artifactual noisy components, this result can play a role of the reference for devising a brain-computer interface using the EEG ERD features of movement imagery or observation.
信號分解方法及其電子裝置
(2016-09-16)
張家齊
;
蕭子健
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許弘毅
本發明提出一種信號分解方法及其電子裝置。所述方法包括下列步驟：取得第一信號；對第一信號執行確定性濾波操作以分解第一信號為至少一主要信號，其中至少一主要信號包括具有固定趨勢的第二信號；以及對第二信號執行非確定性濾波操作以分解第二信號為至少一次要信號，其中至少一次要信號的其中之一具有固定趨勢，且至少一主要信號及至少一次要信號的總和為第一信號。
廢水處理系統
(2016-09-16)
黎德明
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江明桂
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陳金得
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宋耿全
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藍茜茹
本發明的廢水處理系統是用以去除廢水中至少一部份的化學需氧量及含氮化合物，其包括一除碳厭氧流體化床反應器及一除氮流化床反應器，除碳厭氧流體化床反應器主要用以將廢水中大部分的化學需氧量依序水解、酸化及甲烷化為甲烷，除氮流化床反應器則是用以將廢水中的氨氮及剩餘的化學需氧量經由部分硝化反應、自營性脫硝反應及異營性脫硝反應而轉化為氮氣。
生物感測裝置及分離生物分子的方法
(2016-09-16)
李耀坤
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張家瑜
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李博仁
本發明提供一種生物感測裝置及分離生物分子的方法。生物感測裝置包含胺基酸序列以及信號產生元件。胺基酸序列包含SEQ ID NO：1或SEQ ID NO：2所示之序列，係用以與標記於生物分子上之UlaG蛋白鍵結。信號產生元件係與胺基酸序列連接。
Water-Soluble Dinitrosyl Iron Complex (DNIC): a Nitric Oxide Vehicle Triggering Cancer Cell Death via Apoptosis
(2016-09-19)
Wu, Shou-Cheng
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Lu, Chung-Yen
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Chen, Yi-Lin
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Lo, Feng-Chun
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Wang, Ting-Yin
Nitric oxide (NO) is an important cellular signaling molecule that modulates various physiological activities. Angiogenesis-promoting activities of NO-donor drugs have been explored in both experimental and clinical studies. In this study, a structurally well characterized and water-soluble neutral {Fe-(NO)(2)}(9) DNIC [(S(CH2)(2)OH)(S(CH2)(2)NH3)Fe(NO)(2)] (DNIC 2) was synthesized to serve as a NO-donor species. The antitumor activity of DNIC 2 was determined by MTT assay, confocal imaging, and Annexin-V/PI staining. The IC50 values of DNIC 2 were 18.8, 42.9, and 38.6 mu M for PC-3, SKBR-3, and CRLS866 tumor cells, respectively. Moreover, DNIC 2 promoted apoptotic cell death via activation of apoptosis-associated proteins and inhibition of survival associated proteins. In particular, DNIC 2 treatment suppressed PC-3 tumor growth by 2.34- and 19.3-fold at 7 and 21 days, in comparison with the control group. These results indicate that water-soluble DNIC 2 may serve as a promising drug for cancer therapy.
Synchronized self-mode-locked 1061-nm and 1064-nm monolithic Nd:YAG laser at cryogenic temperatures with two orthogonally polarized emissions: generation of 670 GHz beating
(2016-09-19)
Huang, T. L.
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Sung, C. L.
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Cheng, H. P.
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Cho, C. Y.
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Liang, H. C.
A dual-wavelength self-mode-locked monolithic Nd: YAG laser at 1061 and 1064 nm is realized at cryogenic temperatures. At an incident pump power of 5.5 W, the total output power can reach 2.5 W and the mode-locked pulse width is 29 ps at a pulse repetition rate of 7.75 GHz. The synchronization of the dual-wavelength emissions leads to a beat frequency of 670 GHz in the individual mode-locked pulse. It is further discovered that the laser output consists of two orthogonally polarized components with a central frequency difference of 127 MHz. The central frequency difference between two orthogonal polarizations mainly arises from the external mechanical stress introduced by the copper holder for the laser crystal. (C) 2016 Optical Society of America
Combination of Raman Spectroscopy and Mass Spectrometry for Online Chemical Analysis
(2016-09-20)
Meher, Anil Kumar
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Mass spectrometry (MS) and Raman spectroscopy are complementary analytical techniques used to provide information related to chemical structures and functional groups of target analytes. Each instrument provides specific chemical information. If these two analytical tools are coupled online, comprehensive structural information can be simultaneously collected from the analytes of interest without losing any important chemical information. Nevertheless, exploring a suitable interface for coupling of these analytical tools, which are governed with different operation principles, remains challenging. In this study, we used a small piece of tissue paper as an: interface for hyphenating a Raman spectroscope and a mass spectrometer online. The paper played multiroles as sample loading substrate and an emitter to generate electrospray. Furthermore, it can facilitate surface-enhanced Raman spectroscopic analysis to improve analyte signals in Raman spectra. A sample droplet was placed on the tissue paper located close to the laser of the Raman spectroscope and the inlet of mass spectrometer. Raman spectra were first collected by the Raman spectroscope through laser irradiation followed by generation of electrospray on the edge of the paper for MS analysis. Positional isomers were used as model samples to demonstrate the effectiveness of the hyphenated analytical tool in distinguishing isomers. The feasibility of using this Raman-MS hyphenated technique for monitoring chemical reactions online in real time was also investigated.
交大e-News第217期-台德共研多鐵材料鐵酸鉍薄膜獲刊《Nature Communications》
(2016-09-20)
國立交通大學秘書室
;
Secretariat
Electrodeposited Fe2TiO5 nanostructures for photoelectrochemical oxidation of water
(2016-09-20)
Lin, Yan-Gu
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Hsu, Yu-Kuei
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Lin, Yu-Chang
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Chen, Ying-Chu
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材料科學與工程學系
Electrodeposition was used to fabricate nanostructured films of Ti-containing hematite for application to the photoelectrochemical (PEC) splitting of water. The morphology and microstructure of Ti-doped hematite were examined with a scanning electron microscope, X-ray diffraction, Raman spectra and X-ray photoelectron spectra. Optical absorption spectra indicated an enhanced light absorbance in Ti-doped hematite. This Ti doping increased the carrier concentration about ten-fold, confirmed with a Mott-Schottky analysis. The prepared Ti-doped hematite showed a photocurrent enhanced four-fold relative to pristine hematite. Synchrotron-based soft X-ray absorption spectra clearly revealed that a local Fe2TiO5 structure in hematite formed a heterojunction, which decreased the accumulation of photogenerated holes and improved the performance. (C) 2016 Elsevier Ltd. All rights reserved.
Electrodeposited Fe2TiO5 nanostructures for photoelectrochemical oxidation of water
(2016-09-20)
Lin, Yan-Gu
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Hsu, Yu-Kuei
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Lin, Yu-Chang
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Chen, Ying-Chu
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材料科學與工程學系
Electrodeposition was used to fabricate nanostructured films of Ti-containing hematite for application to the photoelectrochemical (PEC) splitting of water. The morphology and microstructure of Ti-doped hematite were examined with a scanning electron microscope, X-ray diffraction, Raman spectra and X-ray photoelectron spectra. Optical absorption spectra indicated an enhanced light absorbance in Ti-doped hematite. This Ti doping increased the carrier concentration about ten-fold, confirmed with a Mott-Schottky analysis. The prepared Ti-doped hematite showed a photocurrent enhanced four-fold relative to pristine hematite. Synchrotron-based soft X-ray absorption spectra clearly revealed that a local Fe2TiO5 structure in hematite formed a heterojunction, which decreased the accumulation of photogenerated holes and improved the performance. (C) 2016 Elsevier Ltd. All rights reserved.
Functional Supramolecular Polymers: A Fluorescent Microfibrous Network in a Supramolecular Hydrogel for High-Contrast Live Cell-Material Imaging in 3D Environments
(2016-09-21)
Hsu, Shu-Min
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Wu, Fang-Yi
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Cheng, Hsun
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Huang, Yu-Tang
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Hsieh, Yi-Ru
A new bottom-up strategy based on aromatic peptide amphiphile is developed for a high-contrast visualization of 3D live cell-material imaging-something that has been difficult to achieve previously because of the problems associated with the diffraction of light by the nanosized peptide materials and the aggregation-caused quenching of aggregated pi-conjugated fluorophores in the nanostructures. This study reports an example of a novel supramolecular hydrogelator, naphthaleneimide-phenylalanine (NI-Phe), which forms a self-supporting hydrogel displaying a unique microfibrous network and promising aggregation-induced emission characteristics at pH 7.4. The storage modulus of the NI-Phe gel supports the mass of a cell for 3D cell culturing. This work illustrates a new dopant-free supramolecular approach, complementary to well-established doping procedures that should facilitate the development of live cell imaging in 3D scaffolding materials.
Online monitoring of chemical reactions by polarization-induced electrospray ionization
(2016-09-21)
Meher, Anil Kumar
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Polarization-induced electrospray ionization (PI-ESI) is a simple technique for instant generation of gas-phase ions directly from a microliter-sized droplet for mass spectrometric analysis. A sample droplet was placed over a dielectric substrate and in proximity (2-3 mm) to the inlet of a mass spectrometer. Owing to the polarization effect induced by the high electric field provided by the mass spectrometer, the droplet was polarized and the electrospray was generated from the apex of the droplet. The polarization-induced electrospray could last for tens of seconds, which was sufficiently long to monitor fast reactions occurring within few seconds. Thus, we demonstrated the feasibility of using the droplet-based PI-ESI MS for the online monitoring of fast reactions by simply mixing two droplets (5-10 mu L) containing reactants on a dielectric substrate placed in front of a mass spectrometer applied with a high voltage (-4500 V). Schiff base reactions and oxidation reactions that can generate intermediates/products within a few seconds were selected as the model reactions. The ionic reaction species generated from intermediates and products can be simultaneously monitored by PI-ESI MS in real time. We also used this approach to selectively detect acetone from a urine sample, in which acetone was derivatized in situ. In addition, the possibility of using this approach for quantitative analysis of acetone from urine samples was examined. (C) 2016 Elsevier B.V. All rights reserved.
Self-Assembled BiFeO3-epsilon-Fe2O3 Vertical Heteroepitaxy for Visible Light Photoelectrochemistry
(2016-09-21)
Le Thi Quynh
;
Chien Nguyen Van
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Bitla, Yugandhar
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Chen, Jhih-Wei
;
Thi Hien Do
Self-assembled vertical heterostructure with a high interface-to-volume ratio offers tremendous opportunities to realize intriguing properties and advanced modulation of functionalities. Here, a heterostructure composed of two visible-light photocatalysts, BiFeO3 (BFO) and epsilon-Fe2O3 (epsilon-FO), is designed to investigate its photoelectrochemical performance. The structural characterization of the BFO-FO heterostructures confirms the phase separation with BFO nanopillars embedded in the epsilon-FO matrix. The investigation of band structure of the heterojunction suggests the assistance of photoexcited carrier separation, leading to an enhanced photoelectrochemical performance. The insights into the charge separation are further revealed by means of ultrafast dynamics and electrochemical impedance spectroscopies. This work shows a delicate design of the self-assembled vertical heteroepitaxy by taking advantage of the intimate contact between two phases that can lead to a tunable charge interaction, providing a new confi guration for the optimization of photoelectrochemical cell.
Block Copolymer-Tuned Fullerene Electron Transport Layer Enhances the Efficiency of Perovskite Photovoltaics
(2016-09-21)
Lin, Hsi-Kuei
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Su, Yu-Wei
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Chen, Hsiu-Cheng
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Huang, Yi-Jiun
;
Wei, Kung-Hwa
In this study, we enhanced the power conversion efficiency (PCE) of perovskite solar cells by employing an electron transfer layer (ETL) comprising [6,6]phenyl-C-61-butyric acid methyl ester (PC61BM) and, to optimize its morphology, a small amount of the block copolymer polystyreneb-poly(ethylene oxide) (PS-b-PEO), positioned on the perovskite active layer. When incorporating 0.373 wt, % PS-b-PEO into PC61BM, the PCE of the perovskite photovoltaic device increased from- 9.4% to 13.4%, a relative increase of 43%, because of a large enhancement in the fill factor of the device. To\' decipher the intricate morphology of the ETL, we used synchrdtron grazing-incidence small-angle X-ray scattering for determining the PC61BM cluster site, atomic force microscopy and scanning electron microscopy for probing the-surface, and transmission electron microscopy for observing the aggregation of PC61BM in the ETL. We found that the interaction between PS-b-PEO and PC61BM resulted in smaller PC61BM dusters that further aggregated into dendritic structures in some domains, a result of the similar polarities of the PS block and PC61BM; this behavior could \'be used to tune the morphology of the ETL. The optimal PS-b-PEO-mediated PC61BM cluster size in the ETT, was 17 nm, a large reduction from 59 nin for the pristine PC61BM layer. This approach ofincorporating a small amount of nanostructured block copolymer into a fullerene allowed us to effectively tune the morphology of the ETL on the perovskite active layer and resulted in enhanced fill factors of the devices and thus their device efficiency.