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排序方式: 共有244条查询结果,搜索用时 390 毫秒
1.
Rongrong Li Hongjie Peng Qingping Wu Xuejun Zhou Jiang He Hangjia Shen Minghui Yang Chilin Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):12227-12236
Herein, we propose the construction of a sandwich-structured host filled with continuous 2D catalysis–conduction interfaces. This MoN-C-MoN trilayer architecture causes the strong conformal adsorption of S/Li2Sx and its high-efficiency conversion on the two-sided nitride polar surfaces, which are supplied with high-flux electron transfer from the buried carbon interlayer. The 3D self-assembly of these 2D sandwich structures further reinforces the interconnection of conductive and catalytic networks. The maximized exposure of adsorptive/catalytic planes endows the MoN-C@S electrode with excellent cycling stability and high rate performance even under high S loading and low host surface area. The high conductivity of this trilayer texture does not compromise the capacity retention after the S content is increased. Such a job-synergistic mode between catalytic and conductive functions guarantees the homogeneous deposition of S/Li2Sx, and avoids thick and devitalized accumulation (electrode passivation) even after high-rate and long-term cycling. 相似文献
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通过IR方法,观测并讨论了在不同条件下制备的超高分子量PE(WHMPE)凝胶膜中旁式(G构象)构象与超拉伸性的关系,提出了G构象浓度及分布对UHMPE凝胶膜超拉伸性影响的新概念,同时也讨论了它与链缠结之间的联系,发现:反映G构象的相对浓度的比值σ=I1303I1352随制膜浓度的增大而增加,在临界浓度C0(0.4~0.5g@100ml)附近所形成的膜,具有超高拉伸性(λ=200),其G构象的变化与Matsuo由比浓粘度提出的缠结链改变相对应;热处理温度比热处理时间对σ值的影响更显著,在一定温度下约4分钟后σ值基本不变;在σ值最低的温度范围拉伸,凝胶膜具有良好的超高拉伸性. 相似文献
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We report a comprehensive theoretical study on the decarbonylation of acetaldehyde by Fe+ and Cr+. Various intermediates, transition states, and products involved in the decarbonylation reactions are fully optimized at the B3LYP/6-311+G(2df,2pd) level of theory. The potential energy surfaces (PESs) corresponding to [M,O,C2,H4]+(M=Cr and Fe) are examined in detail using B3LYP and CCSD(T) methods, respectively. The validity of these theoretical methods is calibrated with respect to the available thermochemical data. Calculations suggest that the Cr+ mediated decarbonylation of acetaldehyde takes place in four steps on the sextet surface: encounter complexation, C-C activation, aldehyde H-shift, and nonreactive dissociation, in good accordance with the Co+ mediated decarbonylation of acetaldehyde [Zhao, Zhang, Guo, Wu, Lu, Chem. Phys. Lett. 2005, 414, 28], while for the Fe+/acetaldehyde system decarbonylation can occur on both the quartet and the sextet PESs. The quartet pathway, which experiences spin-orbit coupling between the two surfaces, is energetically more favorable; whereas along the sextet decarbonylation coordinate several high-energy barriers are revealed. The theoretical results are compared with the experimental product kinetic energy and angular distributions of decarbonylation of acetaldehyde by Fe+ and Cr+ measured using a crossed-beam technique [Sonnenfroh, Farrar, J. Am. Chem. Soc. 1986, 108, 3521]. 相似文献
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Xuan Hao Dr. Hongsen Zhang Dr. Qi Liu Dr. Jingyuan Liu Dr. Rongrong Chen Dr. Jing Yu Prof. Milin Zhang Peili Liu Prof. Jun Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):590-597
Enrichment of UVI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe7S8) on the graphitic carbon nitride nanosheet (CNNS), which were used for capturing UVI. The structural characterizations of Fe7S8/CNNS-1 indicated that the CNNS could prevent the aggregation of Fe7S8 and the saturation magnetization was 4.69 emu g−1, which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g−1 at 298 K. The results of X-ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: UVI is adsorbed on the surface of Fe7S8/CNNS-1 through surface complexation initially, then it was reduced to insoluble UIV. Thereby, this work provided an efficient and easy to handle sorbent material for extraction of UVI. 相似文献
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Rongrong Wang Yidan Duan Xiaopeng Xiong 《Journal of polymer science. Part A, Polymer chemistry》2021,59(20):2284-2294
Increasing hydrophilicity of hydrophobic membrane is one of the strategies to improve its antifouling performance. Herein we report a procedure of reactive-vapor induced phase separation to prepare an N-vinyl pyrrolidone (NVP) modified poly(vinylidene fluoride) (PVDF) membrane to improve its hydrophilicity. PVDF solution containing NVP monomer was cast in ammonia water vapor atmosphere to prepare the modified membrane. During the process, PVDF was dehydrofluorinated by the reactive vapor of ammonia water to generate double bond of FC═CH, and then NVP was grafted. The degree of grafting modification and the microstructure evolution of the membrane were studied by adjusting the amount of NVP addition. A possible mechanism of membrane formation from crystallization gelling to non-crystallization gelling has been proposed to understand the morphology change from nodular sphere to bi-continuous microstructure with fibril matrix. It has been found that rising the degree of modification has changed the polymorph of PVDF from β to α crystalline phase, as well as turned the hydrophobic PVDF membrane into hydrophilic. Moreover, the modified membrane displayed obvious reduction in bovine serum albumin adsorption, suggesting improvement in anti-fouling performance. Therefore, our work provides an easy strategy to prepare hydrophilic PVDF membrane, which may have promising potential applications. 相似文献
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Optical Review - The principle of hyperspectral imaging leads to a variety of stripe noise in hyperspectral images, especially the wide-stripe noise, which brings great obstacles to the... 相似文献
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Graphene‐sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii 下载免费PDF全文
A novel graphene‐sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high‐performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99–104%) and precision (1.1–10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii. 相似文献
10.
Jiankang Deng Jing Hu Juanjuan Zhao Nan An Kuijing Liang Qinghua Wang Zhiqiang Zhang Rongrong Wu Fuyuan Zhang 《Arabian Journal of Chemistry》2021,14(7):103195
This study established a ferric ion (Fe3+) detection method as a result of the fluorescence quenching effect of Fe3+ on carbon dots (CDs). Specifically, we proposed, a green microwave synthesis route towards fluorescent CDs that requires only the brewer’s spent grain as starting materials. Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectra and X-ray photoelectron spectroscopy were performed to investigate the CDs characteristic: morphology, size distribution, functional groups, and composition, respectively. The experimental results, which were run under optimal experimental conditions, indicated that the fluorescence intensity and concentration of Fe3+ were within the desired linear range (0.3–7 μM). The detection limit of this assay towards Fe3+ was 95 nM. The proposed method showed significant selectivity with respect to interfering ions. We evaluated the potential application of this method with tap water, lake water and fetal bovine serum as real samples. Additionally, the CDs could be served as superior bioimaging probes in Hela cells as a result of their excellent optical stability and good biocompatibility. In a word, the present study provides a new idea for CDs derived from the waste of agricultural products for detecting food or environmental contaminants and cell imaging. 相似文献