Browsing by Issue Date, starting with "2012-01-13"

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Histidine-containing Phosphotransfer Protein-B (HptB) Regulates Swarming Motility through Partner-switching System in Pseudomonas aeruginosa PAO1 Strain
(2012-01-13)
Bhuwan, Manish
;
Lee, Hui-Ju
;
Peng, Hwei-Ling
;
Chang, Hwan-You
;
生物科技學系
The histidine-containing phosphotransfer protein-B (HptB; PA3345) is an intermediate protein involved in transferring a phosphoryl group from multiple sensor kinases to the response regulator PA3346 in Pseudomonas aeruginosa PAO1. The objective of this study was to elucidate the biological significance of the HptB-PA3346 interaction and the regulatory mechanisms thereafter. The transcription profiling analysis of an hptB knock-out mutant showed that the expression of a number of motility-related genes was altered consistent with the non-swarming phenotype observed for the mutant. Domain analysis indicated that the PA3346 C-terminal region (PA3346C) exhibits similar to 30% identity with the anti-sigma factor SpoIIAB of Bacillus subtilis. The presence of Ser/Thr protein kinase activity targeting an anti-sigma antagonist, PA3347, at Ser-56 was confirmed in PA3346C using an in vitro phosphorelay assay. Furthermore, PA3346C and the anti-sigma(28) factor FlgM were found to interact with PA3347 individually both in vivo and in vitro. FlgM displaced PA3346C in binding of PA3347 and was then competitively displaced by sigma(28) from the PA3347-FlgM complex, forming a phosphorylation-dependent partner-switching system. The significance of PA3347 phosphorylation in linking the partner-switching system and swarming motility was established by analyzing the swarming phenotype of the PA3347 knock-out mutant and its complement strains.
Non-volatile organic field-effect transistor memory comprising sequestered metal nanoparticles in a diblock copolymer film
(2012-01-14)
Chen, Chia-Min
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Liu, Chih-Ming
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Wei, Kung-Hwa
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Jeng, U-Ser
;
Su, Chiu-Hun
In this study, we fabricated p-channel-type non-volatile organic field-effect transistor (OFET) memory devices featuring an asymmetric PS-b-P4VP diblock copolymer layer incorporating high- and low-work-function metal nanoparticles (NPs) in the hydrophilic and hydrophobic blocks, respectively. We chose the highly asymmetric diblock copolymer PS(56k)-b-P4VP(8k) as the polymer electret to create the memory windows, and used the different work functions of the ex situ-synthesized metal NPs to tune the memory window for either p- or n-channel applications. The transfer curves of non-volatile OFET memory devices incorporating an asymmetric PS(56k)-b-P4VP8k layer embedded with high-work-function Pt NPs (5.65 eV) in the P4VP block exhibited a positive threshold voltage shift and a large memory window (ca. 27 V). In contrast, the transfer curves of the corresponding non-volatile OFET memory devices featuring embedded low-work-function (4.26 eV) Ag NPs exhibited a negative threshold voltage shift and a smaller memory window (ca. 19 V). This approach provides a versatile way to fabricate p- or possibly n-channel-type non-volatile organic field-effect transistor (OFET) memory devices with the same processing procedure.
A new supramolecular film formed from a silsesquioxane derivative for application in proton exchange membranes
(2012-01-14)
Cheng, Chih-Chia
;
Yen, Ying-Chieh
;
Ko, Fu-Hsiang
;
Chu, Chih-Wei
;
Fan, Shih-Kang
A new polyhedral oligomeric silsesquioxane ionomer (HO-doped PUSS-C11-Py) has been investigated. This new ionomer is able to self-assemble through macromers by quadruple hydrogen bonding interactions into a physically crosslinked polymer-like material that can be easily fabricated into films with micro-phase separation. This HCl-doped POSS-C11-Py membrane exhibits higher proton conductivity than a typical Nafion membrane at high temperature, which is extremely rare for a non-sulfonic acid system. This newly developed material may provide an alternative route toward design and fabrication of a new type of proton exchange membranes.
低電能靜態隨機存取記憶體
(2012-01-16)
莊景德
;
楊皓義
;
夏茂墀
;
黃威
;
陳家政
一靜態隨機存取記憶體，包含：至少一記憶格電路，包含了具有至少二反相器的一閉鎖電路，且包含用以接收電能的兩電能接收端；以及一電能供應電路，用以提供該電能至該記憶格電路，使得當資料被寫入至該閉鎖電路時，該閉鎖電路的供應電壓低於一預定電壓。
Carrier dynamics in InN nanorod arrays
(2012-01-16)
Ahn, Hyeyoung
;
Yu, Chih-Cheng
;
Yu, Pyng
;
Tang, Jau
;
Hong, Yu-Liang
In this report, we investigated ultrafast carrier dynamics of vertically aligned indium nitride (InN) nanorod (NR) arrays grown by molecular-beam epitaxy on Si(111) substrates. Dominant band filling effects were observed and were attributed to a partial bleaching of absorption at the probe wavelengths near the absorption edge. Carrier relaxation in nanorod samples was strongly dependent on the rod size and length. In particular, a fast initial decay was observed for carriers in NRs with a small diameter (similar to 30 nm), the lifetime of which is much shorter than the carrier cooling time, demonstrating the substantial surface-associated influence on carrier relaxation in semiconductor nanostructures. (C)2012 Optical Society of America
錄製、還原與重播網路流量的方法
(2012-01-16)
林盈達
;
鄭宗寰
;
賴源正
;
陳一瑋
一種錄製、還原與重播網路流量的方法係用以處理多個網路連線的多個網路封包。錄製、還原與重播網路流量的方法可包括錄製程序、還原程序或是選擇性重播程序。其中錄製程序包括：接收錄製參數(N,M,P)；完整錄製每一網路封包的檔頭以及酬載，並累計每一網路連線的酬載總值；當酬載總值之一超過N時，對與酬載總值對應的網路連線的連續P個網路封包錄製每一網路封包的檔頭，以及酬載的前M個位元組；以及當酬載總值之一超過N並對與酬載總值對應的網路連線連續錄製P個網路封包之後，對與酬載總值對應的網路連線錄製每一網路封包的檔頭。
具有由資料控制之電源供應的靜態隨機存取記憶體
(2012-01-16)
莊景德
;
楊皓義
;
夏茂墀
;
林勇維
;
盧建宇
一種具有由資料控制之電源供應的SRAM，其包含一記憶格電路以及至少一寫入輔助電路。其中寫入輔助電路用以根據欲寫入至記憶格電路的資料提供電能至記憶格電路。
辨識電器狀態的電力監測裝置及其電力監測方法
(2012-01-16)
曹孝櫟
;
賴易聖
;
林明駿
;
陳勇旗
一種辨識電器狀態的電力監控裝置及其電力監控方法，電力監控裝置包括量測模組以及變化偵測與搜尋模組。量測模組測量電源的電耗特性，並且變化偵測與搜尋模組偵測並計算電耗特性的變化。當偵測到變化時，變化偵測與搜尋模組依據此變化來搜尋電器特徵資料庫，以取得對應此變化的電器及其電器狀態。電力監控裝置依據變化偵測與搜尋模組產生之電器變化資料，記載電器的狀態及記錄其耗電情形，並透過比對電器特徵資料庫得知一電器相對於其他相同電器或具備相同功能之其他電器運作是否有效率，以達到節能效果。
Reusable Amperometric Biosensor for Measuring Protein Tyrosine Kinase Activity
(2012-01-17)
Wang, Chung-Liang
;
Wei, Lan-Yi
;
Yuan, Chiun-Jye
;
Hwang, Kuo Chu
;
生物科技學系
This work presents a simple, low-cost and reusable label-free method for detecting protein tyrosine kinase activity using a tyrosinase-based amperometric biosensor (tyrosine kinase biosensor). This method is based on the observation that phosphorylation can block the tyrosinase-catalyzed oxidation of tyrosine or tyrosyl residue in peptides. Therefore, the activity of p60c-src protein tyrosine kinase (Src) on the developed tyrosine kinase biosensor could be quickly determined when its specific peptide substrate, p60c-src substrate I, was used. The tyrosine kinase biosensor was highly sensitive to the activity of Src with a linear dynamic range of 1.9-237.6 U/mL and the lowest detection limit of 0.23 U/mL. Interestingly, the tyrosine kinase activity can be measured using the developed tyrosine kinase biosensor repetitively without regeneration. The inhibitory effect of various kinase inhibitors on the Src activity could be determined on the tyrosine kinase biosensor. Src-specific inhibitors, PP2 and Src inhibitor I, effectively suppressed Src activity, whereas PD153035, an inhibitor of the epidermal growth factor receptor, was ineffective. Staurosporine, a universal kinase inhibitor, inhibited Src activity in an ATP concentration-dependent manner. These results suggests that the activities of tyrosine kinases and their behaviors toward various reagents can be effectively measured using the developed tyrosine kinase biosensor.
Strain-driven phase boundaries in BiFeO3 thin films studied by atomic force microscopy and x-ray diffraction
(2012-01-17)
Liu, Heng-Jui
;
Liang, Chen-Wei
;
Liang, Wen-I
;
Chen, Hsiang-Jung
;
Yang, Jan-Chi
We report a detailed study on the strain-driven phase transition between the tetragonal-like and rhombohedral-like phases in epitaxial BiFeO3 (BFO) thin films which focuses on their structural nature, thermodynamic stability, and ferroelectric/piezoelectric properties. We first show that the tetragonal-like phase, which has a large c/a ratio (similar to 1.2), in the compressively strained BFO is thermodynamically more favorable at high temperature and high strain state (small thickness). We also report a phase transition between two monoclinic phases at 150 degrees C. The two monoclinic phases are differentiated by their c-axis parameters and tilting angles: The low-temperature phase (M-C) has a c-axis parameter of 4.64 angstrom and a tilting angle (beta = 88.5 degrees) along the a axis, while the high-temperature phase (M-A) has a c-axis parameter of 4.66 angstrom and a tilting angle (beta = 86.8 degrees) along both of the a and b axes. We further show that samples undergoing the M-C-M-A phase transition exhibit ferroelectric polarization rotation and piezoelectric enhancement. Our findings directly unveil the close links between structural changes, polarization rotation, and large piezoelectricity at morphotropic phase boundaries in BiFeO3.
GPMiner: an integrated system for mining combinatorial cis-regulatory elements in mammalian gene group
(2012-01-17)
Lee, Tzong-Yi
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Chang, Wen-Chi
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Hsu, Justin Bo-Kai
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Chang, Tzu-Hao
;
Shien, Dray-Ming
Background: Sequence features in promoter regions are involved in regulating gene transcription initiation. Although numerous computational methods have been developed for predicting transcriptional start sites (TSSs) or transcription factor (TF) binding sites (TFBSs), they lack annotations for do not consider some important regulatory features such as CpG islands, tandem repeats, the TATA box, CCAAT box, GC box, over-represented oligonucleotides, DNA stability, and GC content. Additionally, the combinatorial interaction of TFs regulates the gene group that is associated with same expression pattern. To investigate gene transcriptional regulation, an integrated system that annotates regulatory features in a promoter sequence and detects co-regulation of TFs in a group of genes is needed. Results: This work identifies TSSs and regulatory features in a promoter sequence, and recognizes co-occurrence of cis-regulatory elements in co-expressed genes using a novel system. Three well-known TSS prediction tools are incorporated with orthologous conserved features, such as CpG islands, nucleotide composition, over-represented hexamer nucleotides, and DNA stability, to construct the novel Gene Promoter Miner (GPMiner) using a support vector machine (SVM). According to five-fold cross-validation results, the predictive sensitivity and specificity are both roughly 80%. The proposed system allows users to input a group of gene names/symbols, enabling the co-occurrence of TFBSs to be determined. Additionally, an input sequence can also be analyzed for homogeneity of experimental mammalian promoter sequences, and conserved regulatory features between homologous promoters can be observed through cross-species analysis. After identifying promoter regions, regulatory features are visualized graphically to facilitate gene promoter observations. Conclusions: The GPMiner, which has a user-friendly input/output interface, has numerous benefits in analyzing human and mouse promoters. The proposed system is freely available at http://GPMiner.mbc.nctu.edu.tw/.
Construction and analysis of a plant non-specific lipid transfer protein database (nsLTPDB)
(2012-01-17)
Wang, Nai-Jyuan
;
Lee, Chi-Ching
;
Cheng, Chao-Sheng
;
Lo, Wei-Cheng
;
Yang, Ya-Fen
Background: Plant non-specific lipid transfer proteins (nsLTPs) are small and basic proteins. Recently, nsLTPs have been reported involved in many physiological functions such as mediating phospholipid transfer, participating in plant defence activity against bacterial and fungal pathogens, and enhancing cell wall extension in tobacco. However, the lipid transfer mechanism of nsLTPs is still unclear, and comprehensive information of nsLTPs is difficult to obtain. Methods: In this study, we identified 595 nsLTPs from 121 different species and constructed an nsLTPs database - nsLTPDB - which comprises the sequence information, structures, relevant literatures, and biological data of all plant nsLTPs http://nsltpdb.life.nthu.edu.tw/. Results: Meanwhile, bioinformatics and statistics methods were implemented to develop a classification method for nsLTPs based on the patterns of the eight highly-conserved cysteine residues, and to suggest strict Prosite-styled patterns for Type I and Type II nsLTPs. The pattern of Type I is C X-2 V X5-7 C [V, L, I] x Y [L, A, V] X8-13 CC x G X-12 D x [Q, K, R] X-2 CXC X16-21 P X-2 C X13-15C, and that of Type II is C X-4 L X-2 C X9-11 P [S, T] X-2 CC X-5 Q X2-4 C[L, F] C X-2 [A, L, I] x [D, N] P X10-12 [K, R] X4-5 C X3-4 P X0-2 C. Moreover, we referred the Prosite-styled patterns to the experimental mutagenesis data that previously established by our group, and found that the residues with higher conservation played an important role in the structural stability or lipid binding ability of nsLTPs. Conclusions: Taken together, this research has suggested potential residues that might be essential to modulate the structural and functional properties of plant nsLTPs. Finally, we proposed some biologically important sites of the nsLTPs, which are described by using a new Prosite-styled pattern that we defined.
Strain-driven phase boundaries in BiFeO(3) thin films studied by atomic force microscopy and x-ray diffraction
(2012-01-17)
Liu, Heng-Jui
;
Liang, Chen-Wei
;
Liang, Wen-I
;
Chen, Hsiang-Jung
;
Yang, Jan-Chi
We report a detailed study on the strain-driven phase transition between the tetragonal-like and rhombohedral-like phases in epitaxial BiFeO(3) (BFO) thin films which focuses on their structural nature, thermodynamic stability, and ferroelectric/piezoelectric properties. We first show that the tetragonal-like phase, which has a large c/a ratio (similar to 1.2), in the compressively strained BFO is thermodynamically more favorable at high temperature and high strain state (small thickness). We also report a phase transition between two monoclinic phases at 150 degrees C. The two monoclinic phases are differentiated by their c-axis parameters and tilting angles: The low-temperature phase (M(C)) has a c-axis parameter of 4.64 angstrom and a tilting angle (beta = 88.5 degrees) along the a axis, while the high-temperature phase (M(A)) has a c-axis parameter of 4.66 angstrom and a tilting angle (beta = 86.8 degrees) along both of the a and b axes. We further show that samples undergoing the M(C)-M(A) phase transition exhibit ferroelectric polarization rotation and piezoelectric enhancement. Our findings directly unveil the close links between structural changes, polarization rotation, and large piezoelectricity at morphotropic phase boundaries in BiFeO(3).
Weak ferrimagnetism and multiple magnetization reversal in alpha-Cr(3)(PO(4))(2)
(2012-01-18)
Vasiliev, A. N.
;
Volkova, O. S.
;
Hammer, E.
;
Glaum, R.
;
Broto, J. -M.
The chromium(II) orthophosphate alpha-Cr(3)(PO(4))(2) is a weak ferrimagnet with the Curie temperature T(C) = 29 K confirmed by a lambda-type peak in specific heat. Dominant antiferromagnetic interactions in this system are characterized by the Weiss temperature Theta = 96 K, indicating an intermediate frustration ratio vertical bar Theta vertical bar/T(C) similar to 3. In its magnetically ordered states alpha-Cr(3)(PO(4))(2) exhibits a remarkable sequence of temperature-induced magnetization reversals sensitive to the protocol of measurements, i.e., either field-cooled or zero-field-cooled regimes. The reduction of the effective magnetic moment 4.5 mu(B)/Cr(2+), as compared to the spin-only moment 4.9 mu(B)/Cr(2+), cannot be ascribed to the occurrence of the low-spin state in any crystallographic site of the Jahn-Teller active 3d(4) Cr(2+) ions. X-ray absorption spectra at the K edge indicate divalent chromium and unravel the high-spin state of these ions at the L(2,3) edges. Weak ferrimagnetism and multiple magnetization reversal phenomena seen in this compound could be ascribed to incomplete cancellation and distortion of partial spontaneous magnetization functions of Cr(2+) in its six crystallographically inequivalent positions.
Weak ferrimagnetism and multiple magnetization reversal in alpha-Cr-3(PO4)(2)
(2012-01-18)
Vasiliev, A. N.
;
Volkova, O. S.
;
Hammer, E.
;
Glaum, R.
;
Broto, J. -M.
The chromium(II) orthophosphate alpha-Cr-3(PO4)(2) is a weak ferrimagnet with the Curie temperature T-C = 29 K confirmed by a lambda-type peak in specific heat. Dominant antiferromagnetic interactions in this system are characterized by the Weiss temperature Theta = 96 K, indicating an intermediate frustration ratio vertical bar Theta vertical bar/T-C similar to 3. In its magnetically ordered states alpha-Cr-3(PO4)(2) exhibits a remarkable sequence of temperature-induced magnetization reversals sensitive to the protocol of measurements, i.e., either field-cooled or zero-field-cooled regimes. The reduction of the effective magnetic moment 4.5 mu(B)/Cr2+, as compared to the spin-only moment 4.9 mu(B)/Cr2+, cannot be ascribed to the occurrence of the low-spin state in any crystallographic site of the Jahn-Teller active 3d(4) Cr2+ ions. X-ray absorption spectra at the K edge indicate divalent chromium and unravel the high-spin state of these ions at the L-2,L-3 edges. Weak ferrimagnetism and multiple magnetization reversal phenomena seen in this compound could be ascribed to incomplete cancellation and distortion of partial spontaneous magnetization functions of Cr2+ in its six crystallographically inequivalent positions.
Quantum Chemical Prediction of Reaction Pathways and Rate Constants for the Reactions of O-x (x=1 and 2) with Pristine and Defective Graphite (0001) Surfaces
(2012-01-19)
Xu, S. C.
;
Chen, Hui-Lung
;
Lin, M. C.
;
應用化學系分子科學碩博班
;
Institute of Molecular science
We present reaction pathways for adsorption reactions of the O atom and O-2 molecule in the pristine and monovacancy defective graphite (0001) based on quantum chemical potential energy surfaces (PESs) obtained by the dispersion-augmented density-functional tight-binding (DFTB-D) method. We use a dicircumcoronene C96H24 (L0D) graphene slab as the pristine graphite (0001) model and dicircumcoronene C95H24 (LIV) as the graphite (0001) monovacancy defect model. We found that the adsorption reactions of O and O-2 on the L0D surface can produce defects on the graphite surface. O can yield CO, while O-2 can yield both CO and CO2 molecules. The adsorption reactions of the O and O-2 on the LW surface can produce a 2-C defective graphite surface and CO, and CO and CO2, respectively. The O and O-2 more readily oxidize the defected surface, LIV, than the defect-free surface, L0D. On the basis of the computed reaction pathways, we predict reaction rate constants in the temperature range between 300 and 3000 K using Rice-Ramsperger-Kassel-Marcus (RRKM) theory. High-temperature quantum chemical molecular dynamics simulations at 3000 K based on on-the-fly DFTB-D energies and gradients support the results of our PES studies.
Optical Three-Dimensional Coordinate Sensor System and Method Thereof
(2012-01-19)
Chao Paul C.P.
;
Lin Tzu-Yang
;
Chen Wei-Dar
The present invention relates an optical three-dimensional coordinate sensor system and method thereof. A plurality of light-emitting modules produce a plurality of light signals, and then a plurality of reflected light signals reflected by an object are received by a plurality of photodetectors. After receiving the reflected light signals, the photodetectors generate a plurality of photocurrents. A plurality of active pixel circuits receive the photocurrents and transform the photocurrents to a plurality of reflective optical voltages. A plurality of differential amplifier circuits (DAC) compare the reflective optical voltages and the background voltages, and then output a plurality of DAC output voltages of the reflected light signals. Afterward, a processing module detects the DAC output voltages and uses an algorithm to calculate the top three of the DAC output voltages to determine the three-dimensional coordinate of the object.
交大e-News第110期
(2012-01-19)
Secretariat
;
國立交通大學秘書室
SCHMITT TRIGGER-BASED FINFET SRAM CELL
(2012-01-19)
Chuang Ching-Te
;
Hsieh Chien-Yu
;
Fan Ming-Long
;
Hu Pi-Ho
;
Su Pin
The present invention provides a Schmitt trigger-based FinFET static random access memory (SRAM) cell, which is an 8-FinFET structure. A FinFET has the functions of two independent gates. The new SRAM cell uses only 8 FinFET per cell, compared with the 10-FinFET structure in previous works. As a result, the cell structure of the present invention can save chip area and raise chip density. Furthermore, this new SRAM cell can effectively solve the conventional problem that the 6T SRAM cell is likely to have read errors at a low operating voltage.
畫素驅動電路及其驅動方法與應用
(2012-01-21)
蔡明憲
;
戴亞翔
本發明揭露一種畫素驅動電路及其驅動方法與應用，在不同的時序下，此畫素驅動電路中係分別藉由三個薄膜電晶體以做為儲存電容與液晶電容的開關，首先先對儲存電容充入足夠的電量，並且將液晶電容進行放電，最後，重置儲存電容與液晶電容之間的電荷以達到對液晶電容進行充電的目的。因此，藉由本發明之電路設計並同時配合上適當的時序控制，即使在應用色彩序列驅動法的顯示裝置中，係可避免停止逐列掃瞄來切換背光光源，故，畫素充電的時間與發光的時間皆不會縮短，同時亦可使顯示裝置在更高頻率下操作，以提供較佳的畫面品質。