Browsing by Issue Date, starting with "2020-07-16"

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Infrared Spectra of (Z)- and (E)-(C2H3C)-C-center dot(CH3)I Radicals Produced upon Photodissociation of (Z)- and (E)-(CH2I)HC=C(CH3)I in Solid para-Hydrogen
(2020-07-16)
Haupa, Karolina Anna
;
Chen, Kuang-Po
;
Li, Yaw-Kuen
;
Lee, Yuan-Pern
;
交大名義發表
Ozonolysis of isoprene to produce Criegee intermediates such as methyl vinyl ketone oxide (MVKO), C2H3C(CH3)OO, is an important process in atmospheric chemistry. MVKO was recently produced and identified in laboratories after photolysis of a gaseous mixture of 1,3-diiodobut-2-ene, (CH2I)HC=C(CH3)I, and O-2, but the mechanism of its formation remains unexplored. We synthesized pure (Z)- and (E)-1,3-diiodo-but-2-ene and measured their distinct IR spectra. Upon irradiation at 280 nm of (Z)-and (E)-1,3-diiodo-but-2-ene in solid p-H-2 at 3.3 K, the fission of the terminal C.I bond yields (Z)- and (E)-3-iodo-but-2-en-1-yl [(C2H3C)-C-center dot(CH3)I] radicals, respectively. These radicals were characterized with infrared absorption lines at 2962.4, 1423.8, 1265.3, 1120.9/1127.0, 921.4/922.3, and 792.5/791.7 cm(-1), and 16 additional weaker lines for (Z)-(C2H3C)-C-center dot(CH3)I and 1405.2, 1208.2, 1106.0/1103.9, 934.2/933.4, and 785.1/784.9 cm(-1) and five additional weaker ones for (E)-(C2H3C)-C-center dot(CH3)I. The assignments were derived according to behavior on secondary photolysis and comparison of the vibrational wavenumbers and the IR intensities of observed lines with those calculated with the B2PLYP-D3/aug-cc-pVTZ-pp method. These observations confirmed that only the terminal I atom, not the central one, was photodissociated at 280 nm and, in solid p-H-2, the excess energy after photodissociation induced no change in conformation. These new spectra of center dot C2H3C(CH3)I radicals can provide valuable information for the understanding of the mechanism of formation of Criegee intermediate MVKO from the source reaction of photolysis of (CH2I)HC=C(CH3)I in O-2 in the laboratory.
Femtosecond Transient Absorption Spectra and Dynamics of Carrier Relaxation of Tin Perovskites in the Absence and Presence of Additives
(2020-07-16)
Narra, Sudhakar
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Jokar, Efat
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Pearce, Orion
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Lin, Chia-Yi
;
Fathi, Amir
The effects of additives SnF2 (10%) and EDAI(2) (1%) on the dynamics of carrier relaxation of formamidinium tin triiodide (FASnI(3)) perovskite were studied using femtosecond transient absorption spectra (TAS) with excitation at 600 and 870 nm. The TAS were analyzed according to a parallel sequential kinetic model with a global fit through singular-value decomposition. For excitation at 600 nm, two relaxation paths were found: one involved hot and cold carriers in the bulk state undergoing shallow bulk-defect-mediated charge recombination; the other involved trap carriers in the surface state undergoing deep surface-defect-mediated charge recombination. For excitation at 870 nm, only cold carriers were subjected to the bulk-state relaxation channel. Our spectral results indicate significant effects of the additives on retarding charge recombination in both bulk and surface states as well as decreasing the bandgap renormalization energy, the bandwidth of the photobleaching (PB) band, and the Stokes shift between the PB and photoluminescence bands, explaining how the device performance of FASnI(3) solar cells became enhanced in the presence of SnF2 and EDAI(2).
Experimental demonstration of broadband solar absorption beyond the lambertian limit in certain thin silicon photonic crystals
(2020-07-16)
Hsieh, Mei-Li
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Kaiser, Alex
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Bhattacharya, Sayak
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John, Sajeev
;
Lin, Shawn-Yu
The tantalizing possibility of 31% solar-to-electric power conversion efficiency in thin film crystalline silicon solar cell architectures relies essentially on solar absorption well beyond the Lambertian light trapping limit (Bhattacharya and John in Nat Sci Rep 9:12482, 2019). Up to now, no solar cell architecture has exhibited above-Lambertian solar absorption, integrated over the broad solar spectrum. In this work, we experimentally demonstrate two types of photonic crystal (PhC) solar cells architectures that exceed Lambertian light absorption, integrated over the entire 300-1,200 nm wavelength band. These measurements confirm theoretically predicted wave-interference-based optical resonances associated with long lifetime, slow-light modes and parallel-to-interface refraction. These phenomena are beyond the realm of ray optics. Using two types of 10-mu m thick PhC's, first an Inverted Pyramid PhC with lattice constant a=2,500 nm and second a Teepee PhC with a=1,200 nm, we observe solar absorption well beyond the Lambertian limit over lambda =950-1,200 nm. Our absorption measurements correspond to the maximum-achievable-photocurrent-density (MAPD), under AM1.5G illumination at 4-degree incident angle, 41.29 and 41.52 mA/cm(2) for the Inverted Pyramid and Teepee PhC, respectively, in agreement with wave-optics, numerical simulations. Both of these values exceed the MAPD (=39.63 mA/cm(2)) corresponding to the Lambertian limit for a 10-mu m thick silicon for solar absorption over the 300-1,200 nm band.
pi-Extended Coumarins Derived with Nonhydrolyzable Iminophosphoranes as Two-Photon-Excited Fluorophores
(2020-07-17)
Hsia, Liang-Yu
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Chen, Hsin-Ni
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Chiang, Chun-Hao
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Hung, Ming-Yang
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Wei, Hao-Keng
Novel coumarin-iminophosphorane (IPP) fluorophores that have stable resonance contributions from aza-ylides were formed by using the nonhydrolysis Staudinger reaction. The N=P formation reaction kinetics obey the conventional Staudinger reaction. The absorption and emission profiles of the coumarin-IPP derivatives can be fine-tuned: an electron-donating group at PPh3 enhances absorption and fluorescence, whereas an electron-withdrawing group at C-3 drives absorption and emission peaks toward blue-light wavelengths. Two-photon adsorption, accompanied by anti-Stokes fluorescence, is achieved under near-infrared femtosecond laser excitation.
Two Strategies to Improve the Differential Evolution Algorithm for Optimizing Design of Truss Structures
(2020-07-20)
Kao, Ching-Yun
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Hung, Shih-Lin
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Setiawan, Budy
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土木工程學系
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Department of Civil Engineering
The performance of differential evolution (DE) mostly depends on mutation operator. Inappropriate configurations of mutation strategies and control parameters can cause stagnation due to over exploration or premature convergence due to over exploitation. Balancing exploration and exploitation is crucial for an effective DE algorithm. This work presents an enhanced DE (EDE) for truss design that utilizes two new strategies, namely,integrated mutationandadaptive mutation factorstrategies, to obtain a good balance between the exploration and exploitation of DE. Three mutation strategies (DE/rand/1,DE/best/2, andDE/rand-to-best/1) are combined in theintegrated mutationstrategy to increase the diversity of random search and avoid premature convergence to a local minimum. Theadaptive mutation factorstrategy systematically adapts the mutation factor from a large value to a small value to avoid premature convergence in the early searching period and to increase convergence to the global optimum solution in the later searching period. The outstanding performance of the proposed EDE is demonstrated through optimization of five truss structures.
Forest biomass-to-biofuel factory location problem with multiple objectives considering environmental uncertainties and social enterprises
(2020-07-20)
Lin, Chun-Cheng
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Kang, Jia-Rong
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Huang, Guan-Lin
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Liu, Wan-Yu
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工業工程與管理學系
Forest biomass energy enjoys merit of large production, renewability, and clean combustion. However, most related works focused on only the objective of minimization of cost or pollution, but seldom on the social aspect. Social enterprise provides business models that cope with social or environmental problems, e.g., offering employment opportunities in disadvantaged areas. Therefore, this work considers social enterprises and environmental uncertainties in a forest biomass-to-biofuel factory location problem with multiple objectives, which determines whether to open forest biomass-to-biofuel factories at their potential locations to meet the energy demand and other practical constraints. Aside from minimization of cost and carbon emissions, the concerned problem additionally considers the objective of maximizing the job offers provided by opening factories from the social enterprise aspect. Additionally, based on the fuzzy theory, this problem includes the following environmental uncertainties: uncertain number of inventory days, uncertain job offers per unit of surplus factory scale, uncertain biomass production amount, and uncertain biofuel demand due to the price fluctuation of fossil fuels. This work employs the GIS to determine candidate locations of acquiring forest biomass and opening factories, and then solves the problem by fuzzy multi-objective linear programming. Through simulation, we observe the conflict among objectives, compare the differences between the proposed method and previous methods, and analyze the key factors that affect practical implementation. Simulation results show that when the total biofuel demand exceeds 200 million liters per year, the proposed method provides 16% more job offers than the previous method that focused on only cost minimization. (c) 2020 Elsevier Ltd. All rights reserved.
Varifocal augmented reality adopting electrically tunable uniaxial plane-parallel plates
(2020-07-20)
Wang, Yu-Jen
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Lin, Yi-Hsin
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Cakmakci, Ozan
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Reshetnyak, Victor
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光電工程學系
Vergence-accommodation conflict (VAC) is a major challenge in optical-see through augmented reality (AR) system. To resolve this conflict, many approaches are proposed, for instance, by means of adjustment of the projected virtual image to coincide with the surroundings, called image registration, which is more often referred to as varifocal function. In this paper, a varifocal AR system is demonstrated by adopting electrically tunable liquid crystal (LC) plane-parallel plates to solve VAC problem. The LC plates provide electrically tunable optical paths when the directors of LC molecules are re-orientated with applied voltages, which leads to a corresponding change of light speed for an extraordinary wave. To provide a sufficient tunable optical path, three pieces of multiple-layered LC structures are used with the total thickness of the active LC layers (similar to 510 mu m). In experiments, the projected virtual image can be adjusted from 1.4 m to 2.1 m away from the AR system, while the thickness of LC plane-parallel plates are only less than 3 mm without any mechanical moving part. When light propagates in the uniaxial LC layers, the wave vector and the Poynting vector are different. The longitudinal displacement of the image plane is determined by Poynting vectors rather than wave vectors. As a result, the analysis of the AR system should be based on Poynting vectors during geometrical optical analysis. Surprisingly, the tunable range of the longitudinal displacement of Poynting vectors is 2-fold larger than the tunable range of the wave vectors. Moreover, the virtual image shifts in opposite directions with respect to the Poynting vectors and wave vectors. The proposed AR system is not only simple but also thin, and it exhibits a large clear aperture. The investigation here paves the way to a simple solution of the VAC problem for augmented reality systems. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Color dependence of tensor and scalar glueball masses in Yang-Mills theories
(2020-07-20)
Bennett, Ed
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Holligan, Jack
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Hong, Deog Ki
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Lee, Jong-Wan
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Lin, C. -J. David
We report the masses of the lightest spin-0 and spin-2 glueballs obtained in an extensive lattice study of the continuum and infinite volume limits of Sp(N-c) gauge theories for N-c = 2, 4, 6, 8. We also extrapolate the combined results toward the large-N-c limit. We compute the ratio of scalar and tensor masses, and observe evidence that this ratio is independent of N-c. Other lattice studies of Yang-Mills theories at the same space-time dimension provide a compatible ratio. We further compare these results to various analytical ones and discuss them in view of symmetry-based arguments related to the breaking of scale invariance in the underlying dynamics, showing that a constant ratio might emerge in a scenario in which the 0(++) glueball is interpreted as a dilaton state.
Characteristics of low and high SUVA precursors: Relationships among molecular weight, fluorescence, and chemical composition with DBP formation
(2020-07-20)
Hua, Lap-Cuong
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Chao, Shu-Ju
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Huang, Kochin
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Huang, Chihpin
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環境工程研究所
Disinfection by-products (DBPs) formed upon water treatment is an emerging issue worldwide. While monitoring of DBP precursors can easily be achieved for high specific UV absorbance (SUVA) organic (>6 L/mg.m), low and extremely low SUVA precursors (<2 L/mg.m) are difficult to monitor or even to predict their DBP formation behaviour. This study investigated the relationships among NOM characteristics, such as molecular weight (MW), fluorescence, and chemical composition, with DBP formation resulting from the chlorination of relatively high and low SUVA precursors. High SUVA precursors were formed by C-rich substances (82-85% of total mass) corresponding with high C/N and C/O (>100 and >5, respectively). Such precursors exhibited the fluorescence of long-wavelength humic-like signal and occurred at a high MW range (>30 kDa). By contrast, low SUVA precursors were either N-rich and/or O-rich substances, associated with much lower carbon content (40-70%). Low SUVA, N-rich precursors particularly also occurred at a high MW region (>100 kDa) and produced a strong protein-like fluorescence signal. When SUVA values of O-rich precursors were extremely low (<1 L/mg.m) they were accompanyied by short-wavelength humic-like fluorescence. During DBP tests, high SUVA produced only high yields of carbonaceous DBPs (e.g trichloromethane, haloacetic acids, haloketones), whereas low SUVA Nrich precursors yielded high levels of both C and NDBPs (e.g. haloacetonenitrile, chloropicrin). By contrast, extremely low SUVA precursors produced significantly lowlevels of both C and NDBPs (total <30 mu g/mgC). Furthermore, 19 of 20 regression models of DBP formation using log-transformed MW gave R-2 = 0.50-0.97. The strong regressions and correlations of NOM characteristics with DBPs in this study provide a better understanding of the influence of precursors characteristics on DBP monitoring, especially for low SUVA NOM. (C) 2020 Elsevier B.V. All rights reserved.
Improved Error Reduction and Hybrid Input Output Algorithms for Phase Retrieval by including a Sparse Dictionary Learning-Based Inpainting Method
(2020-07-20)
Su, Jian-Jia
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Tien, Chung-Hao
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光電工程學系
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Department of Photonics
The phase retrieval (PR), reconstructing an object from its Fourier magnitudes, is equivalent to a nonlinear inverse problem. In this paper, we proposed a two-step algorithm that traditional ER/HIO iteration plays as the coarse feature reconstruction, whereas the KSVD-based inpainting technique deals with the fine feature set accordingly. Since the KSVD allows the content of oversampled dictionary with sparse representation to adaptively fit a given set of object examples, as long as the ER/HIO algorithms provide decent object estimation at early stage, the pixels violating the object constraint can be restored with superior image quality. The numerical analyses demonstrated the effectiveness of ER + KSVD and HIO + KSVD through multiple independent initial Fourier phases. With its versatility and simplicity, the proposed method can be generalized to be implemented with more PR state-of-the-arts.
Manipulation of Nitrogen-Heteroatom Configuration for Enhanced Charge-Storage Performance and Reliability of Nanoporous Carbon Electrodes
(2020-07-22)
Sutarsis
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Patra, Jagabandhu
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Su, Ching-Yuan
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Li, Ju
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Bresser, Dominic
In this study, various nitrogen-containing functional groups, namely, pyridine (N-6), pyrrole (N-5), oxidized N (N-O), and quaternary N (N-Q), are created on activated carbon (AC) surface via melamine, ammonia, and nitric oxide doping methods. N-5 and N-6 groups markedly alter the specific surface area and pore size of AC. N-O is found to affect electrolyte wettability, and the N-Q content is closely associated with AC electronic conductivity. The nitrogen-containing groups do not contribute to pseudocapacitance in propylene carbonate and acetonitrile electrolytes. However, the nitric-oxide-treated carbon (AC-NO) exhibits the best highrate charge-discharge performance among the investigated materials. The N-Q-enriched and N-5/N-6-depleted AC-NO most effectively suppresses the leakage current and gas evolution of supercapacitors. Online gas chromatography is used to analyze the gaseous species produced from AC electrodes. With an appropriate surface functionality on carbon, the cell voltage can be increased to similar to 3 V, increasing the energy and power densities. The aging behavior of the carbon electrodes with and without nitrogen modification after being floated at 2.5 V and 70 degrees C for 3 days is investigated. An effective strategy for enhancing supercapacitor performance and reliability is proposed.
Label-Free Bimetallic In Situ-Grown 3D Nickel-Foam-Supported NH2-MIL-88B(Fe2Co)-MOF-based Impedimetric Immunosensor for the Detection of Cardiac Troponin I
(2020-07-22)
Palanisamy, Sathyadevi
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Raja, Duraisamy Senthil
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Subramani, Boopathi
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Wu, Tung-Ho
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Wang, Yun-Ming
In this study, a simple and competent metal-organic framework (MOF)-based nickel foam (NF)-supported three-dimensional (3D) immunosensor (Ab-NH2-MIL-88B-(Fe2Co)-MOF/NF) was constructed and utilized for the specific recognition of the biomarker cardiac troponin (I) (cTnI). In the present work, biosensor fabrication was progressed through the modification of the NF substrate with the MOF material (NH2-MIL-88B(Fe2Co)-MOF) to enable an amine-functionalized electrode. This amine-functionalized NF electrodes (NH2-MIL-88B(Fe2Co)-MOF/NF) were then biointerfaced with anti-cTnI antibodies, which ended up as Ab-NH2-MIL-88B(Fe2Co)-MOF/NF electrodes. Analytical executions of the constructed bioelectrode were investigated for the quantitative analysis of cTnI in both buffered and serum solutions. Then, the electrochemical studies were carried out using the electrochemical impedance spectroscopy (EIS) method by monitoring changes concerning the charge transfer resistance (R-ct) characteristics. The limit of detection (LOD) of the Ab-NH2-MIL-88B(Fe2Co)-MOF/NF immunosensor was achieved to be 13 fg/mL with great specificity. This kind of immunosensor imparts a new platform for the construction and application of MOF-hybrid 3D electrode materials with enhanced electrochemical behavior in cTnI sensing for the first time.
The Anastomotic Angle of Hemodialysis Arteriovenous Fistula Is Associated With Flow Disturbance at the Venous Stenosis Location on Angiography
(2020-07-23)
Yang, Chih-Yu
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Li, Ming-Chia
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Lan, Chien-Wen
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Lee, Wang-Jiun
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Lee, Chen-Ju
The juxta-anastomotic stenosis of an arteriovenous fistula (AVF) is a significant clinical problem in hemodialysis patients with no effective treatment. Previous studies of AV anastomotic angles on hemodynamics and vascular wall injury were based on computational fluid dynamics (CFD) simulations using standardized AVF geometry, not the real-world patient images. The present study is the first CFD study to use angiographic images with patient-specific outcome information, i.e., the exact location of the AVF stenotic lesion. We conducted the CFD analysis utilizing patient-specific AVF geometric models to investigate hemodynamic parameters at different locations of an AVF, and the association between hemodynamic parameters and the anastomotic angle, particularly at the stenotic location. We analyzed 27 patients who used radio-cephalic AVF for hemodialysis and received an angiographic examination for juxta-anastomotic stenosis. The three-dimensional geometrical model of each patient's AVF was built using the angiographic images, in which the shape and the anastomotic angle of the AVF were depicted. CFD simulations of AVF hemodynamics were conducted to obtain blood flow parameters at different locations of an AVF. We found that at the location of the stenotic lesion, the AV angle was significantly correlated with access flow disturbance (r= 0.739;p< 0.001) and flow velocity (r= 0.563;p= 0.002). Furthermore, the receiver operating characteristic (ROC) curve analysis revealed that the AV angle determines the lesion's flow disturbance with a high area under the curve value of 0.878. The ROC analysis also identified a cut-off value of the AV angle as 46.5 degrees, above or below which the access flow disturbance was significantly different. By applying CFD analysis to real-world patient images, the present study provides evidence that an anastomotic angle wider than 46.5 degrees might lead to disturbed flow generation, demonstrating a reference angle to adopt during the anastomosis surgery.
Hybrid Composites of Quantum Dots, Monolayer WSe2, and Ag Nanodisks for White Light-Emitting Diodes
(2020-07-24)
Chang, Chiao-Yun
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Yu, Cheng-Li
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Lin, Chen-An
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Lin, Hsiang-Ting
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Lee, Andrew Boyi
We investigated hybrid zero-dimensional core-shell CdSe/ZnS quantum dot (QD)/two-dimensional monolayer WSe2 semiconductors with an Ag nanodisk (ND) for manipulating plasmonic-enhanced photoluminescence (PL) and color conversion efficiency. The absorption spectrum of the local surface plasmon resonance (LSPR) effectively overlaps with that of QDs or monolayer WSe2 to considerably enhance PL. The broad absorption spectrum of the LSPR simultaneously overlapped with the emission spectrum of QDs and the absorption spectrum of excitons in WSe2 to enhance the color conversion efficiency. The highest efficiency of color conversion from QDs to WSe2 with Ag ND was 53%. In the future, hybrid QD/transition metal dichalcogenide light emitters could be further integrated with GaN-based white light-emitting diodes to manipulate the color temperature and expand the color gamut to develop a miniature white light-emitting diode.
Heteroepitaxial growth and microwave plasma annealing of DC reactive sputtering deposited TiZrN film on Si (100)
(2020-07-25)
Chiu, Kun-An
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Fu, Chia-Wei
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Fang, Yu-Siang
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Thi Hien Do
;
Shih, Fu-Han
Epitaxial TiZrN films were successfully grown on Si (100) substrates at high temperature by using DC magnetron reactive sputtering with a Ti0.68Zr0.32 alloy target. Annealing of a grown TiZrN/Si specimen was performed by applying microwave plasma with a gas mixture of N-2 and H-2 to improve the film quality. The X-ray rocking curve (XRC) width of (200)(TiZrN) reflection can reach a minimum value of 1.18 degrees. The heteroepitaxial relationship of TiZrN with Si is {001}(TiZrN)//{001}(Si) and < 110 >(TiZrN)//< 110 >(Si). The (200)(TiZrN) XRC width of a 20 nm-thick TiZrN film reduces from 1.99 degrees to 0.85 degrees by microwave plasma annealing. As a result of the improvement of the film quality, the annealed film exhibits a much lower resistivity (28 mu Omega.cm) than that of the as-deposited one (44 mu Omega.cm). The surface morphologies of the TiZrN films are smooth with the surface roughness in the range of 1-2 nm.
Characteristic V-Mn conversion coating in reinforcing corrosion resistance of electroless Ni-P coated LZ91 Mg alloy
(2020-07-25)
Jian, Shun-Yi
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Chang, Jun-Kai
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Lin, Kung-Feng
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Chen, Ting-Yu
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Yuan, Jui-Hung
A V-Mn conversion coating was studied and furthermore employed to improve the corrosion resistance of electroless Ni-P coated LZ91 Mg alloy. A thin, continuous and compact V-Mn conversion coating was formed on LZ91 after the immersion of 60 s in the conversion coating solution. The results of electrochemical impedance spectroscopy (EIS) and salt spray test (SST) showed the enhanced corrosion resistance of LZ91. The impedance in EIS increased from 573 Omega.cm(2) to 11,319 Omega.cm(2), and moreover the deteriorated area ratio of the V-Mn conversion coated LZ91 decreased to < 5% after 120 h of SST exposures. Further study of a V-Mn conversion coating/electroless Ni-P composite coated LZ91 was used to investigate the improvement of the corrosion resistance in the electroless Ni-P coated LZ91. The composite coated LZ91 demonstrated better corrosion resistance of mere electroless Ni-P coated LZ91. Furthermore, the corrosion resistance of the composite coated LZ91 was greatly enhanced. The impedance of the composite coated LZ91 was 500 Omega.cm(2), larger than that of the electroless Ni-P coating of 5 Omega.cm(2). The composite coated LZ91 showed better corrosion resistance in the SST exposures in comparison to mere electroless Ni-P coated LZ91. The composite coating indicated that the positive characteristics of a V-Mn conversion coating usefully enhanced the corrosion resistance electroless Ni-P coated LZ91. Moreover, based on the above results, a mechanism for the conversion coating and corrosion resistance was proposed.
Premature Drug Release from Polyethylene Glycol (PEG)-Coated Liposomal Doxorubicin via Formation of the Membrane Attack Complex
(2020-07-28)
Chen, Even
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Chen, Bing-Mae
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Su, Yu-Cheng
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Chang, Yuan-Chih
;
Cheng, Tian-Lu
Anti-polyethylene glycol (PEG) antibodies are present in many healthy individuals as well as in patients receiving polyethylene glycol-functionalized drugs. Antibodies against PEG-coated nanocarriers can accelerate their clearance, but their impact on nanodrug properties including nanocarrier integrity is unclear. Here, we show that anti-PEG IgG and IgM antibodies bind to PEG molecules on the surface of PEG-coated liposomal doxorubicin (Doxil, Doxisome, LC-101, and Lipo-Dox), resulting in complement activation, formation of the membrane attack complex (C51/-9) in the liposomal membrane, and rapid release of encapsulated doxorubicin from the liposomes. Drug release depended on both classical and alternative pathways of complement activation. Doxorubicin release of up to 40% was also observed in rats treated with anti-PEG IgG and PEG-coated liposomal doxorubicin. Our results demonstrate that anti-PEG antibodies can disrupt the membrane integrity of PEG-coated liposomal doxorubicin through activation of complement, which may alter therapeutic efficacy and safety in patients with high levels of pre-existing antibodies against PEG.
Incorporating graphene quantum dots to enhance the photoactivity of CdSe-sensitized TiO2 nanorods for solar hydrogen production
(2020-07-28)
Chang, Yung-Shan
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Hsieh, Ping-Yen
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Chang, Tso-Fu Mark
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Chen, Chun-Yi
;
Sone, Masato
This work demonstrated that the incorporation of graphene quantum dots (GQDs) can greatly improve the photoelectrochemical (PEC) efficiency of CdSe-sensitized TiO2 nanorods (TiO2/CdSe), a TiO2-based visible light-responsive photoelectrode paradigm, for solar hydrogen production. For TiO2/CdSe, the accumulated holes at CdSe may induce photocorrosive oxidation to decompose CdSe, deteriorating the long-term stability of the photoelectrode and degrading the PEC performance. With the introduction of GQDs, the delocalized holes can further transfer from CdSe to the GQDs, which eases the hole accumulation at the CdSe sites, thus retarding photocorrosion. Compared to the binary TiO2/CdSe photoanode, the ternary TiO2/CdSe/GQD photoanode displays higher photocurrent and better photostability toward PEC hydrogen production. This superiority can be attributed to vectorial charge transfer and enhanced reaction kinetics provided by the introduction of GQDs. The findings from this work highlight the importance of the introduction of GQDs as a potential solution to the photocorrosion issue of chalcogenide-sensitized semiconductor photoelectrodes.
Synthesis of hyaluronic acid oligosaccharides with a GlcNAc-GlcA repeating pattern and their binding affinity with CD44
(2020-07-28)
Yeh, Che-Jui
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Zulueta, Medel Manuel L.
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Li, Yaw-Kuen
;
Hung, Shang-Cheng
;
應用化學系
Hyaluronic acid (HA) is a ubiquitous glycosaminoglycan in the extracellular matrix and a ligand of CD44, a transmembrane glycoprotein that is important in cell migration. Crystal and NMR studies found a hexasaccharide of the pattern (GlcA-GlcNAc)(3)as the shortest HA that could bind to CD44, but molecular dynamics simulations indicated that a tetrasaccharide of the pattern (GlcNAc-GlcA)(2)is the key structure interacting with CD44. Access to oligomers with such a repeat pattern is crucial in binding studies with CD44. Here we developed a synthetic procedure to afford the HA oligosaccharides with the GlcNAc-GlcA repeating unit and measured the binding interaction between these sugars and human CD44 by isothermal titration calorimetry (ITC). During the chemical synthesis, we successfully generated the beta-glycosidic bond in the absence of neighbouring group participation and overcome the issues in the oxidation step. In addition, ammonia-free dissolving metal reduction for debenzylation and azido reduction has been applied in carbohydrate synthesis for the first time. ITC analysis revealed that the HA tetrasaccharide (GlcNAc-GlcA)(2)could indeed interact and bind to the human CD44.
Correlation among photoluminescence and the electronic and atomic structures of Sr2SiO4:xEu(3+) phosphors: X-ray absorption and emission studies
(2020-07-29)
Zheng, Shi-Yan
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Chiou, Jau-Wern
;
Li, Yueh-Han
;
Yang, Cheng-Fu
;
Ray, Sekhar Chandra
A series of Eu3+-activated strontium silicate phosphors, Sr2SiO4:xEu(3+) (SSO:xEu(3+), x=1.0, 2.0 and 5.0%), were synthesized by a sol-gel method, and their crystalline structures, photoluminescence (PL) behaviors, electronic/atomic structures and bandgap properties were studied. The correlation among these characteristics was further established. X-ray powder diffraction analysis revealed the formation of mixed orthorhombic alpha'-SSO and monoclinic beta-SSO phases of the SSO:xEu(3+) phosphors. When SSO:xEu(3+) phosphors are excited under ultraviolet (UV) light (lambda=250 nm,similar to 4.96 eV), they emit yellow (similar to 590 nm), orange (similar to 613 nm) and red (similar to 652 and 703 nm) PL bands. These PL emissions typically correspond to 4f-4f electronic transitions that involve the multiple excited D-5(0)-> F-7(J) levels (J=1, 2, 3 and 4) of Eu3+ activators in the host matrix. This mechanism of PL in the SSO:xEu(3+) phosphors is strongly related to the local electronic/atomic structures of the Eu3+-O2- associations and the bandgap of the host lattice, as verified by Sr K-edge and Eu L-3-edge X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure, O K-edge XANES and K-alpha X-ray emission spectroscopy. In the synthesis of SSO:xEu(3+) phosphors, interstitial Eu2O3-like structures are observed in the host matrix that act as donors, providing electrons that are nonradiatively transferred from the Eu 5d and/or O 2p-Eu 4f/5d states (mostly the O 2p-Eu 5d states) to the D-5(0) levels, facilitating the recombination of electrons that have transitioned from the D-5(0) level to the F-7(J) level in the bandgap. This mechanism is primarily responsible for the enhancement of PL emissions in the SSO:xEu(3+) phosphors. This PL-related behavior indicates that SSO:xEu(3+) phosphors are good light-conversion phosphor candidates for use in near-UV chips and can be very effective in UV-based light-emitting diodes.