Browsing by Issue Date, starting with "2017-08-23"

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Electrically sign-reversible transverse g-factors of holes in droplet epitaxial GaAs/AlGaAs quantum dots under uniaxial stress
(2017-08-23)
Wu, Yu-Nien
;
Wu, Ming-Fan
;
Ou, Ya-Wen
;
Chou, Ying-Lin
;
Cheng, Shun-Jen
We present a theoretical investigation of anisotropic g-factor tensors of single holes confined in droplet epitaxial GaAs/AlGaAs quantum dots under electrical and mechanical controls using the gauge-invariant discretization method within the framework of four-band Luttinger-Kohn (k) over right arrow.(p) over right arrow theory. We reveal an intrinsic obstacle to realize the electrical sign reversal of the hole g-factors, being a key condition required for a full spin control in the scheme of g-tensor modulation, for the quantum dots solely with electrical bias control. Constructively, our studies show that, besides electrical gating, slightly stressing an inherently unstrained droplet epitaxial GaAs/AlGaAs quantum dot can offset the transverse hole g-factor to be nearly zero and make the electrical sign reversal of the hole g-factors feasible.
METHOD FOR PARAMETER EXTRACTION OF A SEMICONDUCTOR DEVICE
(2017-08-24)
Jyh-Chyurn GUO
;
Yen-Ying LIN
A method is provided for parameter extraction of a semiconductor device with a multi-finger gate. The method includes measuring gate-to-source and gate-to-drain capacitances and performing 3D simulation to compute fringing capacitances, thereby computing an overlap capacitance between the gate and a source/drain extension region, and computing a length of the source/drain extension region according to the overlap capacitance.
Sulfur-Doped Graphene Oxide Quantum Dots as Photocatalysts for Hydrogen Generation in the Aqueous Phase
(2017-08-24)
Gliniak, Jacek
;
Lin, Jia-Hoa
;
Chen, Yi-Ting
;
Li, Chuen-Ru
;
Jokar, Efat
Sulfur-doped graphene oxide quantum dots (S-GOQDs) were synthesized and investigated for efficient photocatalytic hydrogen generation application. The UV/Vis, FTIR, and photoluminescence spectra of the synthesized S-GOQDs exhibit three absorption bands at 333, 395, and 524 nm, characteristic of C=S and C=S stretching vibration signals at 1075 and 690 cm(-1), and two excitation-wavelength-independent emission signals with maxima at 451 and 520 nm, respectively, confirming the successful doping of S atom into the GOQDs. Electronic structural analysis suggested that the S-GOQDs exhibit conduction band minimum (CBM) and valence band maximum (VBM) levels suitable for water splitting. Under direct sunlight irradiation, an initial rate of 18166 mu molh(-1) g(-1) in pure water and 30519 mu molh(-1) g(-1) in 80% ethanol aqueous solution were obtained. Therefore, metal-free and inexpensive S-GOQDs hold great potential in the development of sustainable and environmentally friendly photocatalysts for efficient hydrogen generation from water splitting.
MANUFACTURING, UTILIZATION, AND ANTIFOULING COATING OF HYDROXYL-COVERED SILICON QUANTUM DOT NANOPARTICLE
(2017-08-24)
CHANG-CHING TU
;
KUANG-PO CHEN
;
YAW-KUEN LI
A hydroxyl-covered silicon quantum dot nanoparticle having a silicon core, a plurality of silicon quantum dots, and a plurality of hydrocarbon chains is illustrated. A first portion of a surface associated with the silicon core is passivated by a plurality of silicon hydroxyl groups (Si—OH). The silicon quantum dots are attached to a second portion of the surface associated with the silicon core. The hydrocarbon chains are bonded to each of the silicon quantum dots through a plurality of silicon carbide bonds (Si—C), wherein each termination of the hydrocarbon chains has a carbon hydroxyl group (C—OH), such that the hydroxyl-covered silicon quantum dot nanoparticle is thoroughly covered by the carbon hydroxyl groups (C—OH) and the silicon hydroxyl groups (Si—OH).
Direct Reprogramming of Human Suspension Cells into Mesodermal Cell Lineages via Combined Magnetic Targeting and Photothermal Stimulation by Magnetic Graphene Oxide Complexes
(2017-08-25)
Chiang, Min-Yu
;
Lin, Yi-Zhen
;
Chang, Shwu-Jen
;
Shyu, Woei-Cherng
;
Lu, Huai-En
Suspension cells can provide a source of cells for cellular reprogramming, but they are difficult to transfect by nonviral vectors. An efficient and safe nonviral vector (GO-Fe3O4-PEI complexes) based on iron oxide nanoparticle (Fe3O4)-decorated graphene oxide (GO) complexed with polyethylenimine (PEI) for the first time is developed for delivering three individual episomal plasmids (pCXLE-hOCT3/4-shp53, pCXLE-hSK, and pCXLE-hUL) encoding pluripotent-related factors of Oct3/4, shRNA against p53, Sox2, Klf4, L-Myc, and Lin28 into human peripheral blood mononuclear cells (PBMCs) simultaneously. The combined treatment of magnetic stirring and near-infrared (NIR)-laser irradiation, which can promote contact between the complexes and floating cells and increase the cell membrane permeability, respectively, is used to conduct multiple physical stimulations for suspension PBMCs transfection. The PCR analysis shows that the combinatorial effect of magnetic targeting and photothermal stimulation obviously promoted the transfection efficiency of suspension cells. The transfected cells show positive expression of the pluripotency markers, including Nanog, Oct4, and Sox2, and have potential to differentiate into mesoderm and ectoderm cells. The results demonstrate that the GO-Fe3O4-PEI complex provides a safe, convenient, and efficient tool for reprogramming PBMCs into partially induced pluripotent stem cells, which are able to rapidly transdifferentiate into mesodermal lineages without full reprogramming.
Synthesis of multicomponent asymmetric star-branched polymers by iterative methodology with new diblock copolymer in-chain anions as building blocks
(2017-08-25)
Goseki, Raita
;
Ito, Shotaro
;
Hirao, Akira
;
應用化學系
;
Department of Applied Chemistry
New AB diblock copolymer in-chain anions having poly(2-vinylpyridine) (P2VP) and/or poly(methyl methacrylate) (PMMA) blocks, whose anion is located at the junction between the A and B blocks, have been prepared by the 1:1 addition reaction of the living polymer (A) with the omega- or alpha-terminal 1-phenyl1-( 2-pyridinyl) ethylene-functionalized polymer (B). The P2VP-block-PS, PS-block-P2VP, P2VP-blockpoly( 4-tert-butyldimethylsilyloxystyrene), PS-block-PMMA, and P2VP-block-PMMA in-chain anions could be practically prepared for the first time. Based on this preparation, a newly synthesized 1,4-bis(1-(2pyridinyl) ethenyl) benzene satisfactorily works as a key core agent, with which the polymers (A) can be connected to the polymer (B), and the in-chain anion can be generated between the A and B polymers. By developing the iterative methodology with such new block copolymer in-chain anions as the building blocks, the successive synthesis of the 3-arm ABC and 5-arm ABCDE mu-star polymers having PMMA and P2VP arms, which were synthetically difficult by the previous systems, have been successfully achieved. The success of the developed methodology demonstrates the further possibility to synthesize more component mu-star polymers. (C) 2017 Elsevier Ltd. All rights reserved.
DDX3 localizes to the centrosome and prevents multipolar mitosis by epigenetically and translationally modulating p53 expression
(2017-08-25)
Chen, Wei-Ju
;
Wang, Wei-Ting
;
Tsai, Tsung-Yuan
;
Li, Hao-Kang
;
Lee, Yan-Hwa Wu
The DEAD-box RNA helicase DDX3 plays divergent roles in tumorigenesis, however, its function in mitosis is unclear. Immunofluorescence indicated that DDX3 localized to centrosome throughout the cell cycle and colocalized with centrosome-associated p53 during mitosis in HCT116 and U2OS cells. DDX3 depletion promoted chromosome misalignment, segregation defects and multipolar mitosis, eventually leading to G2/M delay and cell death. DDX3 prevented multipolar mitosis by inactivation and coalescence of supernumerary centrosomes. DDX3 silencing suppressed Ser(15) phosphorylation of p53 which is required for p53 centrosomal localization. Additionally, knockout of p53 dramatically diminished the association of DDX3 with centrosome, which was rescued by overexpression of the centrosomal targeting-defective p53 S15A mutant, indicating that centrosomal localization of DDX3 is p53 dependent but not through centrosomal location of p53. Furthermore, DDX3 knockdown suppressed p53 transcription through activation of DNA methyltransferases (DNMTs) along with hypermethylation of p53 promoter and promoting the binding of repressive histone marks to p53 promoter. Moreover, DDX3 modulated p53 mRNA translation. Taken together, our study suggests that DDX3 regulates epigenetic transcriptional and translational activation of p53 and colocalizes with p53 at centrosome during mitosis to ensure proper mitotic progression and genome stability, which supports the tumor-suppressive role of DDX3.
Exciton-polariton Josephson junctions at finite temperatures
(2017-08-25)
Lebedev, M. E.
;
Dolinina, D. A.
;
Hong, Kuo-Bin
;
Lu, Tien-Chang
;
Kavokin, A. V.
We consider finite temperature effects in a non-standard Bose-Hubbard model for an exciton-polariton Josephson junction (JJ) that is characterised by complicated potential energy landscapes (PEL) consisting of sets of barriers and wells. We show that the transition between thermal activation (classical) and tunneling (quantum) regimes exhibits universal features of the first and second order phase transition (PT) depending on the PEL for two polariton condensates that might be described as transition from the thermal to the quantum annealing regime. In the presence of dissipation the relative phase of two condensates exhibits non-equilibrium PT from the quantum regime characterized by efficient tunneling of polaritons to the regime of permanent Josephson or Rabi oscillations, where the tunneling is suppressed, respectively. This analysis paves the way for the application of coupled polariton condensates for the realisation of a quantum annealing algorithm in presently experimentally accessible semiconductor microcavities possessing high (105 and more) Q-factors.
Controlled self-assemblies of polystyrene-block-polydimethylsiloxane micelles in cylindrical confinement through a micelle solution wetting method and Rayleigh-instability-driven transformation
(2017-08-28)
Ko, Hao-Wen
;
Higuchi, Takeshi
;
Chang, Chun-Wei
;
Cheng, Ming-Hsiang
;
Isono, Komei
Block copolymer micelles have been extensively discussed for many decades because of their applications, such as lithography and drug delivery. However, controlling the morphologies of nanostructure assembly using block copolymer micelles as building elements remains a great challenge. In this work, we developed a novel route to induce micelle assembly in confined geometries. Polystyrene-block-polydimethylsiloxane (PS-b-PDMS) micelle solutions were used to prepare micelle nanostructures, and the critical parameters affecting the morphologies were determined. Micelle nanorods, micelle nanospheres, and multi-component nanopeapods were prepared by wetting anodic aluminum oxide (AAO) templates with micelle solutions. Rayleigh-instability-driven transformation was discovered to play an important role in controlling the morphologies of the micelle nanostructures. This study not only proposes a versatile approach to preparing block copolymer micelle nanostructures, but it also provides deeper insight into the controlling factors of block copolymer micelle morphologies in cylindrical confinement.
Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement
(2017-08-28)
Li, Jung-Yu
;
Chen, Shih-Pu
;
Siao, Huei-Jhen
;
Wu, Jin-Han
;
Chen, Guan-Yu
In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m(2), which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity. Published by AIP Publishing.
AC stress and electronic effects on SET switching of HfO2 RRAM
(2017-08-28)
Liu, Jen-Chieh
;
Magyari-Kope, Blanka
;
Qin, Shengjun
;
Zheng, Xin
;
Wong, H. -S. Philip
An AC stress test was performed to investigate the accompanying electronic effects in a HfO2 resistive random access memory during the SET transition, which featured a sudden decrease in resistance. Comparing the DC and AC measurement results indicated the pronounced influence of interrupted stress on both the mean values and variations of time to SET. First-principles calculations suggested that the charge states (+2, +1, or neutral) of oxygen vacancies affect the migration barrier for forming oxygen vacancy clusters. Therefore, a charge-state-dependent SET model is proposed to include the additional electronic effects induced by the dynamics of electron trapping and detrapping in oxygen vacancies during AC stress. A trimodal Weibull fitting based on the proposed model reproduced the experimental time to SET distributions obtained in a wide range of AC stress conditions. Published by AIP Publishing.
Gate tunable spin-orbit coupling and weak antilocalization effect in an epitaxial La2/3Sr1/3MnO3 thin film
(2017-08-28)
Chiu, Shao-Pin
;
Yamanouchi, Michihiko
;
Oyamada, Tatsuro
;
Ohta, Hiromichi
;
Lin, Juhn-Jong
Epitaxial La2/3Sr1/3MnO3 (LSMO) films have been grown on SrTiO3 (001) substrates via pulsed laser deposition. In a 22-nm-thick LSMO film with a low residual resistivity of rho(0) approximate to 59 mu Omega cm, we found a zero-field dip in the magnetoresistance (MR) below 10 K, manifesting the weak antilocalization (WAL) effect due to strong spin-orbit coupling (SOC). We have analyzed the MR data by including the D'yakonov-Perel' spin-relaxation mechanism in the WAL theory. We explain that the delocalized spin-down electron sub-band states play a crucial role for facilitating marked SOC in clean LSMO. Moreover, we find that the SOC strength and gate voltage tunability are similar to those in a two-dimensional electron gas at the LaAlO3/SrTiO3 interface, indicating the presence of an internal electric field near the LSMO/SrTiO3 interface. In a control measurement on a 5-nm-thick high resistivity (rho(0) approximate to 280 mu Omega cm) LSMO film, we observe only a small zero-field peak in MR from weak localization effect, indicating negligible SOC.
Hyperscaling violating black hole solutions and magneto-thermoelectric DC conductivities in holography
(2017-08-28)
Ge, Xian-Hui
;
Tian, Yu
;
Wu, Shang-Yu
;
Wu, Shao-Feng
;
電子物理學系
We derive new black hole solutions in Einstein-Maxwell-axion-dilaton theory with a hyperscaling violation exponent. We then examine the corresponding anomalous transport exhibited by cuprate strange metals in the normal phase of high-temperature superconductors via gauge-gravity duality. Linear-temperature-dependence resistivity and quadratic-temperature-dependence inverse Hall angle can be achieved. In the high-temperature regime, the heat conductivity and Hall Lorenz ratio are proportional to the temperature. The Nernst signal first increases as temperature goes up, but it then decreases with increasing temperature in the high-temperature regime.
Co-delivery of paclitaxel and cetuximab by nanodiamond enhances mitotic catastrophe and tumor inhibition
(2017-08-29)
Lin, Yu-Wei
;
Raj, Emmanuel Naveen
;
Liao, Wei-Siang
;
Lin, Johnson
;
Liu, Kuang-Kai
The poor intracellular uptake and non-specific binding of anticancer drugs into cancer cells are the bottlenecks in cancer therapy. Nanocarrier platforms provide the opportunities to improve the drug efficacy. Here we show a carbon-based nanomaterial nanodiamond (ND) that carried paclitaxel (PTX), a microtubule inhibitor, and cetuximab (Cet), a specific monoclonal antibody against epidermal growth factor receptor (EGFR), inducing mitotic catastrophe and tumor inhibition in human colorectal cancer (CRC). ND-PTX blocked the mitotic progression, chromosomal separation, and induced apoptosis in the CRC cells; however, NDs did not induce these effects. Conjugation of ND-PTX with Cet (ND-PTX-Cet) was specifically binding to the EGFR-positive CRC cells and enhanced the mitotic catastrophe and apoptosis induction. Besides, ND-PTX-Cet markedly decreased tumor size in the xenograft EGFR-expressed human CRC tumors of nude mice. Moreover, ND-PTX-Cet induced the mitotic marker protein phospho-histone 3 (Ser10) and apoptotic protein active-caspase 3 for mitotic catastrophe and apoptosis. Taken together, this study demonstrated that the co-delivery of PTX and Cet by ND enhanced the effects of mitotic catastrophe and apoptosis in vitro and in vivo, which may be applied in the human CRC therapy.
Functional Connectivity of the Corpus Callosum in Epilepsy Patients with Secondarily Generalized Seizures
(2017-08-30)
Peng, Syu-Jyun
;
Hsin, Yue-Loong
;
電子工程學系及電子研究所
;
生醫電子轉譯研究中心
;
Department of Electronics Engineering and Institute of Electronics
The corpus callosum (CC) plays an important role in generalization of seizure activity. We used resting-state function magnetic resonance imaging (rs-fMRI) to investigate the regional and interregional functional connectivity of CC in patients with magnetic resonance imaging (MRI)-negative and secondarily generalized seizures. We measured the multi-regional coherences of blood oxygen level-dependent (BOLD) signals via rs-fMRI, cortical thickness via high-resolution T1-weighted MRI, and white matter (WM) integrity via diffusion-tensor imaging in 16 epilepsy patients as well as in 16 age-and gender-matched healthy subjects. All patients had non-lesional MRI, medically well-controlled focal epilepsy and history of secondarily generalized convulsions. Individuals with epilepsy had significant differences in regional and interregional hypersynchronization of BOLD signals intrahemispherically and interhemispherically, but no difference in cortical thickness and WM integrity. The only area with increased regional hypersynchrony in WM was over the anterior CC, which also exhibited lower activation of neighboring resting-state networks. The present study revealed abnormal local and distant synchronization of spontaneous neural activities in epileptic patients with secondarily generalized seizures.
NERVE IMPULSE SIGNAL STIMULATION DEVICE AND METHOD FOR FABRICATING THE SAME
(2017-08-31)
Yu-Ting Cheng
;
Chung-Yu Wu
;
Jui-Sheng Sun
;
Yu-Min Fu
;
Che-Yu Chen
A nerve impulse signal stimulation device and a method for fabricating the same are provided. The nerve impulse signal stimulation device includes: a substrate having a first surface and a second surface opposite to the first surface; a first metal layer formed on the first surface of the substrate; a second metal layer formed on the first metal layer; a plurality of openings exposing a portion of the first surface of the substrate, a portion of the first metal layer and a portion of the second metal layer; and a ferromagnetic material attached to the second surface of the substrate. The openings cause the nerve impulse signal stimulation device to obtain a parallel circuit structure, thereby increasing the current load and the magnetic field intensity, reducing the size of the device, and ensuring the safety of operations.
METHOD FOR PROCESSING IMAGE WITH DEPTH INFORMATION AND COMPUTER PROGRAM PRODUCT THEREOF
(2017-08-31)
Jiun-In GUO
;
Po-Yu CHIEN
The present invention proposes a method for processing an image with depth information and a computer program product thereof, wherein a filtering template is used to extract a gesture region and filter the image, and wherein the hue values of the pixels of the current gesture region are used to modify the self-adaptive thresholds of the filtering template, and wherein the size of the filtering template at the next time point is modified according to the depth at the current time point and the depth at the former time point.
Negative correlation of cortical thickness with the severity and duration of abdominal pain in Asian women with irritable bowel syndrome
(2017-08-31)
Chua, Chian Sem
;
Bai, Chyi-Huey
;
Shiao, Chen-Yu
;
Hsu, Chien-Yeh
;
Cheng, Chiao-Wen
Background & aims: Irritable bowel syndrome (IBS) manifests as chronic abdominal pain. One pathophysiological theory states that the brain-gut axis is responsible for pain control in the intestine. Although several studies have discussed the structural changes in the brain of IBS patients, most of these studies have been conducted in Western populations. Different cultures and sexes experience different pain sensations and have different pain responses. Accordingly, we aimed to identify the specific changes in the cortical thickness of Asian women with IBS and to compare these data to those of non-Asian women with IBS. Methods: Thirty Asian female IBS patients (IBS group) and 39 healthy individuals (control group) were included in this study. Brain structural magnetic resonance imaging was performed. We used FreeSurfer to analyze the differences in the cortical thickness and their correlations with patient characteristics. Results: The left cuneus, left rostral middle frontal cortex, left supramarginal cortex, right caudal anterior cingulate cortex, and bilateral insula exhibited cortical thinning in the IBS group compared with those in the controls. Furthermore, the brain cortical thickness correlated negatively the severity as well as duration of abdominal pain. Conclusions: Some of our findings differ from those of Western studies. In our study, all of the significant brain regions in the IBS group exhibited cortical thinning compared with those in the controls. The differences in cortical thickness between the IBS patients and controls may provide useful information to facilitate regulating abdominal pain in IBS patients. These findings offer insights into the association of different cultures and sexes with differences in cortical thinning in patients with IBS.
Phosphonic Acid and Lithium Salt as Effective p-Dopants to Oxidize Spiro-OMeTAD for Mesoscopic Sb2S3 Solar Cells
(2017-08-31)
Chung, Chih-Chun
;
Tsai, Ting -Wei
;
Wu, Hui -Ping
;
Diau, Eric Wei-Guang
;
應用化學系
1-Decyl phosphonic acid (DPA) proved an effective p-doping additive to oxidize spiro-OMeTAD as a hole-transporting material (HTM) for nanostructured Sb2S3 extremely thin absorber (ETA) solar cells. DPA had the effect of enhancing the hole conductivities of spiro-OMeTAD in the presence of lithium bis(trifluoromethyl- sulfonyl)-imide (LiTFSI) to significantly improve the device performance. Transient photoelectric measurements and electrochemical impedance spectra of devices fabricated with varied additive conditions provided information about the charge- transport and recombination kinetics and hole conductivities for Sb2S3 devices with additives DPA and LiTFSI that exhibited superior performance. Thirty-five identical devices were fabricated to show the excellent reproducibility and long-term stability in air; the best Sb2S3 ETA device attained efficiency of power conversion 6.0%, which is twice that of a device using other typical additives (LiTFSI and 4-tert-butyl-pyridine) for spiro-OMeTAD serving as HTM.
Optical properties of plasma-enhanced chemical vapor deposited SiCxNy films by using silazane precursors
(2017-08-31)
Chang, Wei-Yuan
;
Chang, Chieh-Yu
;
Leu, Jihperng
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In this study, amorphous silicon carbonitride (SiCxNy) films were fabricated by radio frequency (RF) chemical vapor deposition (PECVD) using a single silazane precursor and a low power density (0.15W/cm(3)) for better compositional control. The effects of the precursor chemical structure (C/Si ratio, C-Si-N structure, and vinyl groups) and deposition temperature (T-s) on the chemical structure and optical properties of SiCxNy films were examined using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Specifically, two new single precursors; namely, n-methyl-aza-2,2,4-trimethylsilacyclopentane (MTSCP) and 1,3-divinyl-1,1,3,3-tetramethyl-disilazane (DVTMDS) were studied and compared. SiCxNy films deposited using MTSCP involving Si-C-3-N rings formed Si-N and Si-(CH2)(3)-crosslinked structures at T-s <= 100 degrees C, and were then changed to predominantly Si-CH2-N-Si crosslinked structures at Ts > 300 degrees C, leading to a wide range of optical band gap from 5.2 to 3.7 eV. Compared to DVTMDS-deposited SiCxNy films, their relatively higher percentage of Si-C-N structure accounted for the lower optical band gap and reduced transmission. DVTMDS with di-vinyl groups readily formed a Si-(CH2)(2)-bridge in SiCxNy films Ts <= 200 degrees C, resulting in excellent optical transmittance. The transmittance in the visible wavelengths of 400 degrees C-deposited SiCxNy film using DVTMDS still showed 85%. Also, tunable refractive index between 1.44 and 2.10 were obtained for SiCxNy films deposited at T-s <= 400 degrees C. (c) 2017 Elsevier B.V. All rights reserved.