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901.
We examined the thermal stability of amorphous silicon oxycarbide (SiOC) and crystalline Fe composite by in situ and ex situ annealing. The Fe/SiOC multilayer thin films were grown via magnetron sputtering with controlled length scales on a surface-oxidized Si (100) substrate. These Fe/SiOC multilayers were in situ or ex situ annealed at temperature of 600 °C or lower. The thin multilayer sample (~10 nm) was observed to have a layer breakdown after 600 °C annealing. Diffusion starts from low groove angle triple junctions in Fe layers. In contrast, the thick multilayer structure (~70 nm) was found to be stable and an intermixed layer (FexSiyOz) was observed after 600 °C annealing. The thickness of the intermixed layer does not vary as annealing time goes up. The results suggest that the FexSiyOz layer can impede further Fe, Si and O diffusion, and assists in maintaining morphological stability. 相似文献
902.
We propose and analyze an efficient high-dimensional quantum state transfer protocol in an XX coupling spin network with a hypercube structure or chain structure. Under free spin wave approximation, unitary evolution results in a perfect high-dimensional quantum swap operation requiring neither external manipulation nor weak coupling. Evolution time is independent of either distance between registers or dimensions of sent states, which can improve the computational efficiency. In the low temperature regime and thermodynamic limit, the decoherence caused by a noisy environment is studied with a model of an antiferromagnetic spin bath coupled to quantum channels via an Ising-type interaction. It is found that while the decoherence reduces the fidelity of state transfer, increasing intra-channel coupling can strongly suppress such an effect. These observations demonstrate the robustness of the proposed scheme. 相似文献
903.
Theoretical analysis of the mode coupling induced by heat of large-pitch micro-structured fibers 下载免费PDF全文
In this paper,a theoretical model to analyze the mode coupling induced by heat,when the fiber amplifier works at high power configuration,is proposed.The model mainly takes into consideration the mode field change due to the thermally induced refractive index change and the coupling between modes.A method to predict the largest average output power of fiber is also proposed according to the mode coupling theory.The largest average output power of a large pitch fiber with a core diameter of 190 μm and an available pulse energy of 100 mJ is predicted to be 540 W,which is the highest in large mode field fibers. 相似文献
904.
A Novel L‐Cysteine Electrochemical Sensor Using Sulfonated Graphene‐poly(3,4‐Ethylenedioxythiophene) Composite Film Decorated with Gold Nanoparticles 下载免费PDF全文
Xiaoqiang Wang Yangping Wen Limin Lu Jingkun Xu Long Zhang Yuanyuan Yao Haohua He 《Electroanalysis》2014,26(3):648-655
By exploiting the electrostatic interaction between positively charged 3,4‐ethylenedioxythiophene cation radicals and negatively charged sulfonated graphene (SG) sheets, we prepared a poly(3,4‐ethylenedioxythiophene)‐sulfonated graphene (SG‐PEDOT) composite film by a one‐step electrochemical process. The composite was further decorated with gold nanoparticles (AuNPs) and employed as an electrode material for the detection of L ‐cysteine (Cys). The SG‐PEDOT composite film is shown to provide a rough surface for the electrodeposition of AuNPs and to improve substrate accessibility and interaction with Cys. Moreover, the AuNPs‐decorated composite exhibits better electrocatalytic performance than that of a SG‐PEDOT composite only. Under optimum experimental conditions, the amperometric current of the sensor is linearly related to the concentration of Cys in the 0.1 to 382 µM range, and the detection limit is 0.02 µM (at S/N=3). The modified electrode displays favorable selectivity, good stability and high reproducibility. The method was successfully applied to the detection of Cys in spiked human urine. 相似文献
905.
Approach to the study of flavone di‐C‐glycosides by high performance liquid chromatography‐tandem ion trap mass spectrometry and its application to characterization of flavonoid composition in Viola yedoensis 下载免费PDF全文
Jie Cao Chengle Yin Yan Qin Zhihong Cheng Daofeng Chen 《Journal of mass spectrometry : JMS》2014,49(10):1010-1024
The mass spectrometric (MS) analysis of flavone di‐C‐glycosides has been a difficult task due to pure standards being unavailable commercially and to that the reported relative intensities of some diagnostic ions varied with MS instruments. In this study, five flavone di‐C‐glycoside standards from Viola yedoensis have been systematically studied by high performance liquid chromatography‐electrospray ionization‐tandem ion trap mass spectrometry (HPLC‐ESI‐IT‐MSn) in the negative ion mode to analyze their fragmentation patterns. A new MS2 and MS3 hierarchical fragmentation for the identification of the sugar nature (hexoses or pentoses) at C‐6 and C‐8 is presented based on previously established rules of fragmentation. Here, for the first time, we report that the MS2 and MS3 structure‐diagnostic fragments about the glycosylation types and positions are highly dependent on the configuration of the sugars at C‐6 and C‐8. The base peak (0,2X10,2X2? ion) in MS3 spectra of di‐C‐glycosides could be used as a diagnostic ion for flavone aglycones. These newly proposed fragmentation behaviors have been successfully applied to the characterization of flavone di‐C‐glycosides found in V. yedoensis. A total of 35 flavonoid glycosides, including 1 flavone mono‐C‐hexoside, 2 flavone 6,8‐di‐C‐hexosides, 11 flavone 6,8‐di‐C‐pentosides, 13 flavone 6,8‐C‐hexosyl‐C‐pentosides, 5 acetylated flavone C‐glycosides and 3 flavonol O‐glycosides, were identified or tentatively identified on the base of their UV profiles, MS and MSn (n = 5) data, or by comparing with reference substances. Among these, the acetylated flavone C‐glycosides were reported from V. yedoensis for the first time. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
906.
HF:H2O2:H2O solution (40%wt.HF: 30wt.%H2O2: H2O, 3:2:1 by volume) was used to reveal extended defects (line, face and volume defects) in bulk ZnTe crystals grown from Te solution. The etch patterns were analyzed based on their size, shape and distribution. The etch figures, both in the shape of pits and hillocks with high resolution, show forms controlled by the symmetries of the respective faces were produced. Two different sizes of pits were observed, the larger‐size pits correspond to dislocations penetrating the surface, however, the smaller‐size texture pits are produced on the defect‐free region, which serve as standard pits on respect faces. The face defects, such as grain boundaries, sub‐grain boundaries, dislocation walls, twins and stacking faults, can be all displayed clearly. Another essential feature of the etchant is that, it can effectively dissolve Te‐rich phase (Te inclusion/precipitates), which makes it promising to reveal the shape of this volume defect. 相似文献
907.
Na Wang Yuhu Wu Long Mi Jing Zhang Xuri Li Qinghong Fang 《Journal of Thermal Analysis and Calorimetry》2014,116(1):349-357
The mechanisms of the thermal degradation of polyhedral oligomeric octaphenylsilsesquioxane (OPS), octa(nitrophenyl)silsesquioxane (ONPS), and octa(aminophenyl)silsesquioxane (OAPS) were investigated. The –NO2 or –NH2 substituents on the phenyl group affected the mechanism of the POSS thermal degradation. The thermal stabilities of OPS, ONPS, and OAPS were characterized by TG and FTIR. Thermal degradation of OPS included mainly the degradation of caged polyhedral oligomeric silsesquioxane structures and phenyl groups. Nitro or amino substituents decreased its thermal stability. The thermal degradation processes of OPS, ONPS, and OAPS differed. Phenyl groups and cyclobutadiene were observed in the OPS degradation products. Oxygen radicals that caused intensive CO2 release between 350 and 450 °C were generated by the degradation of ONPS –NO2. OAPS released mainly aminophenyl groups at 370 °C, whereas a small number of phenyl groups decomposed at 500 °C. The OAPS reactivity could enhance the thermal stability of POSS structure in the polyimide OAPS composites. 相似文献
908.
Fangyang Liu Can Han Liangxing Jiang Jie Li Yexiang Liu 《Journal of Solid State Electrochemistry》2014,18(7):1833-1845
Based on the basic principles of kinetics and some reasonable assumptions about the electrodeposition process, a dynamic model for metal selenide electrodeposition (kink site selected model) was constructed. This model is of universal significance in realizing the compositional prediction and dynamic behavior analysis of deposited films for different main salt concentration ratios and was applied to the ternary Cu–In–Se system. For CuInSe2 electrodeposition, in the Cu–Se system, the co-deposition of Cu and Se can be carried out within a large range of main salt concentration ratio; in the Cu–In system, the mole fraction of Cu in deposited thin films is always higher than that of Cu2+ in electrolyte, while in the In–Se system, the co-deposition of In and Se can be achieved only when the In3+ concentration is much higher than the H2SeO3 concentration. As for the compositional estimation of CuInSe2, the predictive results of our dynamic model agree well with the experimental data. It is then found that by correcting the difference of kink site selectivity constants caused by the change of deposition potential, the error of the predictive results can be reduced. 相似文献
909.
Guishan Zou Xiukang Yang Xianyou Wang Long Ge Hongbo Shu Yansong Bai Chun Wu Haipeng Guo Liang Hu Xin Yi Bowei Ju Hai Hu Di Wang Ruizhi Yu 《Journal of Solid State Electrochemistry》2014,18(7):1789-1797
The Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres are firstly prepared and subsequently transferred into the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x sample has a typical α-NaFeO2 layered structure with the existence of Li2MnO3-type integrated component, and the Al2O3 layer is uniformly coated on the surface of the spherical Li-rich Li1.3[Ni0.35Mn0.65]O2+x particles with a thickness of about 4 nm. Importantly, the Al2O3-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al2O3-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al2O3-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al2O3-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g?1 even at 10 C. Besides, the thin Al2O3 layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li1.3[Ni0.35Mn0.65]O2+x . 相似文献
910.
Large Hexagonal Bi‐ and Trilayer Graphene Single Crystals with Varied Interlayer Rotations 下载免费PDF全文
Zheng Yan Yuanyue Liu Long Ju Zhiwei Peng Dr. Jian Lin Dr. Gunuk Wang Dr. Haiqing Zhou Changsheng Xiang E. L. G. Samuel Carter Kittrell Dr. Vasilii I. Artyukhov Prof. Feng Wang Prof. Boris I. Yakobson Prof. James M. Tour 《Angewandte Chemie (International ed. in English)》2014,53(6):1565-1569
Bi‐ and trilayer graphene have attracted intensive interest due to their rich electronic and optical properties, which are dependent on interlayer rotations. However, the synthesis of high‐quality large‐size bi‐ and trilayer graphene single crystals still remains a challenge. Here, the synthesis of 100 μm pyramid‐like hexagonal bi‐ and trilayer graphene single‐crystal domains on Cu foils using chemical vapor deposition is reported. The as‐produced graphene domains show almost exclusively either 0° or 30° interlayer rotations. Raman spectroscopy, transmission electron microscopy, and Fourier‐transformed infrared spectroscopy were used to demonstrate that bilayer graphene domains with 0° interlayer stacking angles were Bernal stacked. Based on first‐principle calculations, it is proposed that rotations originate from the graphene nucleation at the Cu step, which explains the origin of the interlayer rotations and agrees well with the experimental observations. 相似文献