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171.
The fruit of Crataegus dahurica Koehne was used to treat the disease of infantile indigestion and dyspepsia as an ethnic medicine and food. As a continuous work on finding the active constituents from the edible herbs, four new biphenyl derivatives ( 1 – 4 ), together with two known compounds ( 5 and 6 ), were obtained from the petroleum ether fraction of the fruits of C. dahurica. Their structures were determined by the extensive 1D and 2D NMR spectra and HR‐MS spectrometry. Furthermore, the anti‐inflammatory activities of all the isolated compounds were investigated, in which compound 4 showed moderately inhibitory effects on NO production in RAW264.7 cells without inducing cytotoxicity. 相似文献
172.
Wei Wu Xiao‐Hui Jia Sha Zhang Chun‐Mao Dong Feng‐Hua Kang Zhen‐Xing Zou Kang‐Ping Xu 《化学与生物多样性》2020,17(6)
Two new abietane diterpenoids, (3S,5R,10S)‐3‐hydroxy‐12‐O‐demethyl‐11‐deoxy‐19(4→3)‐abeo‐cryptojaponol, 12,19‐dihydroxyabieta‐8,11,13‐trien‐7‐one, were isolated from Selaginella moellendorffii Hieron., together with one known abietane diterpenoid and four known tetracyclic triterpenoids. Their structures were characterized by their 1D‐ and 2D‐NMR, ECD and mass spectral studies. All compounds were tested for their inhibitory effects on proliferation of three human cancer cells (human non‐small‐cell lung carcinoma cell lines A549 and human breast adenocarcinoma cell lines MDA‐MB‐231 and MCF‐7) in vitro. Among them, three compounds displayed modest cytotoxic activities against the above three human cancer cell lines with IC50 values ranging from 16.28 to 40.67 μM. 相似文献
173.
174.
Karnpiwat Tantratian Daxian Cao Ahmed Abdelaziz Xiao Sun Jinzhi Sheng Avi Natan Lei Chen Hongli Zhu 《Liver Transplantation》2020,10(5)
The application of lithium (Li) metal anodes in rechargeable batteries is primarily restricted by Li dendrite growth on the metal's surface, which leads to shortened cycle life and safety concerns. Herein, well‐spaced nanotubes with ultrauniform surface curvature are introduced as a Li metal anode structure. The ultrauniform nanotubular surface generates uniform local electric fields that evenly attract Li‐ions to the surface, thereby inducing even current density distribution. Moreover, the well‐defined nanotube spacing offers Li diffusion pathways to the electroactive areas as well as the confined spaces to host deposited Li. These structural attributes create a unique electrodeposition manner; i.e., Li metal homogenously deposits on the nanotubular wall, causing each Li nanotube to grow in circumference without obvious sign of dendritic formation. Thus, the full‐cell battery with the spaced Li nanotubes exhibits a high specific capacity of 132 mA h g?1 at 1 C and an excellent coulombic efficiency of ≈99.85% over 400 cycles. 相似文献
175.
Xu Luo Pengxia Ji Pengyan Wang Ruilin Cheng Ding Chen Can Lin Jianan Zhang Jianwei He Zuhao Shi Neng Li Shengqiang Xiao Shichun Mu 《Liver Transplantation》2020,10(17)
Rational design and construction of bifunctional electrocatalysts with excellent activity and durability is imperative for water splitting. Herein, a novel top‐down strategy to realize a hierarchical branched Mo‐doped sulfide/phosphide heterostructure (Mo‐Ni3S2/NixPy hollow nanorods), by partially phosphating Mo‐Ni3S2/NF flower clusters, is proposed. Benefitting from the optimized electronic structure configuration, hierarchical branched hollow nanorod structure, and abundant heterogeneous interfaces, the as‐obtained multisite Mo‐Ni3S2/NixPy/NF electrode has remarkable stability and bifunctional electrocatalytic activity in the hydrogen evolution reaction (HER)/oxygen evolution reaction (OER) in 1 m KOH solutions. It possesses an extremely low overpotential of 238 mV at the current density of 50 mA cm?2 for OER. Importantly, when assembled as anode and cathode simultaneously, it merely requires an ultralow cell voltage of 1.46 V to achieve the current density of 10 mA cm?2, with excellent durability for over 72 h, outperforming most of the reported Ni‐based bifunctional materials. Density functional theory results further confirm that the doped heterostructure can synergistically optimize Gibbs free energies of H and O‐containing intermediates (OH*, O*, and OOH*) during HER and OER processes, thus accelerating the catalytic kinetics of electrochemical water splitting. This work demonstrates the importance of the rational combination of metal doping and interface engineering for advanced catalytic materials. 相似文献
176.
Ya‐Qian Zhang Yaosen Tian Yihan Xiao Lincoln J. Miara Yuichi Aihara Tomoyuki Tsujimura Tan Shi M. C. Scott Gerbrand Ceder 《Liver Transplantation》2020,10(27)
The interfacial instability between a thiophosphate solid electrolyte and oxide cathodes results in rapid capacity fade and has driven the need for cathode coatings. In this work, the stability, evolution, and performance of uncoated, Li2ZrO3‐coated, and Li3B11O18‐coated LiNi0.5Co0.2Mn0.3O2 cathodes are compared using first‐principles computations and electron microscopy characterization. Li3B11O18 is identified as a superior coating that exhibits excellent oxidation/chemical stability, leading to substantially improved performance over cells with Li2ZrO3‐coated or uncoated cathodes. The chemical and structural origin of the different performance is interpreted using different microscopy techniques which enable the direct observation of the phase decomposition of the Li2ZrO3 coating. It is observed that Li is already extracted from the Li2ZrO3 in the first charge, leading to the formation of ZrO2 nanocrystallites with loss of protection of the cathode. After 50 cycles separated (Co, Ni)‐sulfides and Mn‐sulfides can be observed within the Li2ZrO3‐coated material. This work illustrates the severity of the interfacial reactions between a thiophosphate electrolyte and oxide cathode and shows the importance of using coating materials that are absolutely stable at high voltage. 相似文献
177.
178.
As performance of halide perovskite devices progresses, the device structure becomes more complex with more layers. Molecular interfacial structures between different layers play an increasingly important role in determining the overall performance in a halide perovskite device. However, current understanding of such interfacial structures at a molecular level nondestructively is limited, partially due to a lack of appropriate analytical tools to probe buried interfacial molecular structures in situ. Here, sum frequency generation (SFG) vibrational spectroscopy, a state‐of‐the‐art nonlinear interface sensitive spectroscopy, is introduced to the halide perovskite research community and is presented as a powerful tool to understand molecule behavior at buried halide perovskite interfaces in situ. It is found that interfacial molecular orientations revealed by SFG can be directly correlated to halide perovskite device performance. Here how SFG can examine molecular structures (e.g., orientations) at the perovskite/hole transporting layer and perovskite/electron transporting layer interfaces is discussed. This will promote the use of SFG to investigate molecular structures of buried interfaces in various halide perovskite materials and devices in situ nondestructively with a sub‐monolayer interface sensitivity. Such research will help to elucidate structure–function relationships of buried interfaces, aiding in the rational design/development of halide perovskite materials/devices with improved performance. 相似文献
179.
Bing‐Qing Xiong Xinwei Zhou Gui‐Liang Xu Yuzi Liu Likun Zhu Youcheng Hu Shou‐Yu Shen Yu‐Hao Hong Si‐Cheng Wan Xiao‐Chen Liu Xiang Liu Shengli Chen Ling Huang Shi‐Gang Sun Khalil Amine Fu‐Sheng Ke 《Liver Transplantation》2020,10(4)
Alloy materials such as Si and Ge are attractive as high‐capacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during discharge–charge processes. Compared to the over‐emphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solid‐electrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloy‐based anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li3Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiF‐dominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sb‐coated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh g?1 after 200 cycles at 500 mA g?1, compared to only 72% and 170 mAh g?1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve long‐term cycling stability for alloy‐based anode materials. 相似文献
180.
Hao Wang Jianmin Li Xiaoxiao Kuai Liangmin Bu Lijun Gao Xu Xiao Yury Gogotsi 《Liver Transplantation》2020,10(35)
Although 2D Ti3C2Tx is a good candidate for supercapacitors, the restacking of nanosheets hinders the ion transport significantly at high scan rates, especially under practical mass loading (>10 mg cm?2) and thickness (tens of microns). Here, Ti3C2Tx‐NbN hybrid film is designed by self‐assembling Ti3C2Tx with 2D arrays of NbN nanocrystals. Working as an interlayer spacer of Ti3C2Tx, NbN facilitates the ion penetration through its 2D porous structure; even at extremely high scan rates. The hybrid film shows a thickness‐independent rate performance (almost the same rate capabilities from 2 to 20 000 mV s?1) for 3 and 50 µm thick electrodes. Even a 109 µm thick Ti3C2Tx‐NbN electrode shows a better rate performance than 25 µm thick pure Ti3C2Tx electrodes. This method may pave a way to controlling ion transport in electrodes composed of 2D conductive materials, which have potential applications in high‐rate energy storage and beyond. 相似文献