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Ye Linglong Li Xueshan Cai Yunhao Ryu Hwa Sook Lu Guangkai Wei Donghui Sun Xiaobo Woo Han Young Tan Songting Sun Yanming 《中国科学:化学(英文版)》2020,63(4):483-489
Benzo[1,2-b:4,5-b′]dithiophene(BDT) has been widely used to construct donor-acceptor(D-A) copolymers in organic solar cells(OSCs). However, benzo[1,2-b:4,5-b′]difuran(BDF), an analogue of BDT, has received less attention than BDT. The photovoltaic performance of BDF copolymers has lagged behind that of BDT copolymers. Here, we designed and synthesized two BDF copolymers, PBF1-C and PBF1-C-2Cl. PBF1-C-2Cl, which is composed of BDF and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione connected by a chlorinated thiophene π-bridge, displays a low-lying highest occupied molecular orbital energy level,which helps in yielding a high open-circuit voltage(V_(oc)) in OSCs. As a result, when blended with Y6, PBF1-C-2Cl-based devices showed a high V_(oc) of 0.83 V and a power conversion efficiency(PCE) of 13.10%. To the best of our knowledge, the PCE of 13.10% is among the highest efficiency values for OSCs based on BDF copolymers. 相似文献
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Yuanbo Li Fengshou Dong Xingang Liu Jun Xu Wuying Chen Li Cheng Ping Ning Jing Li Yunhao Wang Yongquan Zheng 《Journal of separation science》2010,33(13):1973-1979
A simple enantioselective HPLC method was developed for measuring carfentrazone‐ethyl enantiomers. The separation and determination was accomplished on an amylose tris[(S)‐α‐methylbenzylcarbamate] (Chiralpak AS) column using n‐hexane/ethanol (98:2, v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 248 nm. The effects of mobile‐phase composition and column temperature on the enantioseparation were discussed. The accuracy, precision, linearity, LODs, and LOQ of the method were also investigated. LOD was 0.001 mg/kg in water, 0.015 mg/kg in soil and wheat, with an LOQ of 0.0025 mg/kg in water and 0.05 mg/kg in soil and wheat for each enantiomer of carfentrazone‐ethyl. SPE was used for the enrichment and cleanup of soil, water, and wheat samples. Recoveries for two enantiomers were 88.4–106.7% with RSDr of 4.2–9.8% at 0.1, 0.5, and 1 mg/kg levels from soil, 85.8–99.5% with the RSDr of 4.4?9.6% at 0.005, 0.025, and 0.05 mg/kg levels from water, and from wheat the recoveries were 86.3?91.3% with RSDr below 5.0% at 0.2, 0.5, and 1 mg/kg levels. This method could be used to identify and quantify the carfentrazone‐ethyl enantiomers in food and environment. 相似文献
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Li Y Dong F Liu X Xu J Li J Lu C Wang Y Zheng Y 《Analytical and bioanalytical chemistry》2011,400(9):3097-3107
A rapid and simple miniaturized liquid–liquid extraction method has been developed for the determination of topramezone in
soil, corn, wheat, and water samples using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-electrospray
ionization (ESI)/MS/MS). The established method for the extraction and purification procedure was based on liquid–liquid partitioning
into an aqueous solution at a low pH (pH ≈ 2.5), followed by back-partitioning into water at pH > 9. Two precursor, product
ion transitions for topramezone were measured and evaluated to provide the maximum degree of confidence in the results. Under
negative ESI conditions, quantitation was achieved by monitoring the fragment at m/z = 334 and the qualitative fragment at m/z = 318, whereas also collecting the corresponding parent ion at m/z = 362. Chromatographic separation was achieved using gradient elution with a mobile phase consisting of methanol and a 0.01%
aqueous ammonium hydroxide solution. Recovery studies for soil, corn, wheat, and water were conducted at four different topramezone
concentrations (5 or 10, 50, 100, and 1,000 μg kg−1); the overall average recoveries ranged from 79.9% to 98.4% with intra-day relative standard deviations (RSD) of 3.1~8.7%
and inter-day RSD of 4.3~7.5%. Quantitative results were determined from calibration curves of topramezone standards containing
1–500 μg L−1 with an R
2 ≥ 0.9994. Method sensitivities expressed as limits of quantitation were typically 6, 8, 9, and 1 μg kg−1 in soil, corn, wheat, and water, respectively. The results of the method validation confirmed that this proposed method was
convenient and reliable for the determination of topramezone residues in soil, corn, wheat, and water. 相似文献
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In this paper, compressive imaging based on spatial correlation (CISC), which uses second-order correlation with the measurement matrix, is introduced to improve the signal-to-noise ratio performance of compressive imaging (CI). Numerical simulations and experiments are performed as well. Referred to the results, it can be seen that CISC performs much better than CI in three common noise environments. This provides the great opportunity to pave the way for real applications. 相似文献
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本文采用市售纳米硅为硅源,以软化点低、得碳率高、价格便宜的煤沥青作为碳源,通过两步包覆法制备了煤沥青基硅/碳(Si/C/C)复合物,并研究其作为锂离子电池负极材料的电化学性能。 结果表明,所得复合物的粒径在300~350 nm间,Si纳米粒子被C包覆并相互连结成C-Si-C网络结构,其中Si含量为27%的硅/碳复合物(Si/C/C-27%)作为锂电池电极材料表现了良好的储锂性能。 在0.1 A/g的小电流密度下,Si/C/C-27%的放电比容量为1281 mA·h/g;在3 A/g的大电流密度下,其放电比容量仍能保持在582 mA·h/g,表现了良好的倍率性能。Si/C/C-27%在2 A/g的电流密度下经过100次的循环后其比容量保持率为76.61%,表现了良好的循环稳定性。 相比于煤沥青基碳的一次包覆所得的硅/碳复合材料(Si/C),Si/C/C有效提高了Si纳米粒子的导电性并抑制了其在嵌锂和脱锂过程中的体积膨胀。 本文提出的二次包覆的新方法为制备具有优异电化学性能的锂离子电池负极材料提供了新的研究思路。 相似文献
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Entropy Production Analysis of a Vertical Mixed-Flow Pump Device with Different Guide Vane Meridians
With the aim of investigating the influence of guide vane meridians on the external characteristics and internal flow field of the mixed-flow pump device, this research constructed seven guide vane meridians and applied computational fluid dynamic (CFD) and entropy production theory to investigate the spread of hydraulic loss in a mixed-flow pump. As observed, when the guide vane outlet diameter Dgvo decreased from 350 mm to 275 mm, the head and efficiency increased by 2.78% and 3.05% at 0.7 Qdes, respectively. At 1.3 Qdes, when Dgvo increased from 350 mm to 425 mm, the head and efficiency increased by 4.49% and 3.71%, respectively. At 0.7 Qdes and 1.0 Qdes, the entropy production of the guide vane increased with the increase of Dgvo due to flow separation. When Dgvo < 350 mm, at 1.0 Qdes and 1.3 Qdes, entropy production of the outlet channel increased as Dgvo decreased owing to the excessive flow rate, but at 0.7 Qdes, entropy production did not change much. When Dgvo > 350 mm, at 0.7 Qdes and 1.0 Qdes, due to the expansion of the channel section, the flow separation intensified, which resulted in an increase of the entropy production, but the entropy production decreased slightly at 1.3 Qdes. These results provide guidance for improving the efficiency of pumping stations. 相似文献
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Building Polymeric Framework Layer for Stable Solid Electrolyte Interphase on Natural Graphite Anode
Yunhao Zhao Yueyue Wang Rui Liang Guobin Zhu Weixing Xiong Honghe Zheng 《Molecules (Basel, Switzerland)》2022,27(22)
The overall electrochemical performance of natural graphite is intimately associated with the solid electrolyte interphase (SEI) layer developed on its surface. To suppress the interfacial electrolyte decomposition reactions and the high irreversible capacity loss relating to the SEI formation on a natural graphite (NG) surface, we propose a new design of the artificial SEI by the functional molecular cross-linking framework layer, which was synthesized by grafting acrylic acid (AA) and N,N′−methylenebisacrylamide (MBAA) via an in situ polymerization reaction. The functional polymeric framework constructs a robust covalent bonding onto the NG surface with —COOH and facilitates Li+ conduction owing to the effect of the —CONH group, contributing to forming an SEI layer of excellent stability, flexibility, and compactness. From all the benefits, the initial coulombic efficiency, rate performance, and cycling performance of the graphite anode are remarkably improved. In addition, the full cell using the LiNi0.5Co0.2Mn0.3O2 cathode against the modified NG anode exhibits much-prolonged cycle life with a capacity retention of 82.75% after 500 cycles, significantly higher than the cell using the pristine NG anode. The mechanisms relating to the artificial SEI growth on the graphite surface were analyzed. This strategy provides an efficient and feasible approach to the surface optimization for the NG anode in LIBs. 相似文献
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文章作者主持的国家级精品教材《热学》第3版和国家级精品课程热学的目标和特色是要教好活的物理学.热学教材和教学内容的"实"、"新"、"宽"就是从物理现象着手教好活的物理学的重要体现,而在此基础上进一步强调科学思维方法的训练,特别是强调创新能力的培养,这就是"活".课堂讨论是热学课程又一特色. 相似文献