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931.
Haozhou Yang Deren Yang Xun Wang 《Angewandte Chemie (International ed. in English)》2020,59(36):15527-15531
Utilizing sustainable energy for chemical activation of small molecules, such as CO2, to produce important chemical feedstocks is highly desirable. The simultaneous production of CO/H2 mixture (syngas) from photoreduction of CO2 and H2O is highly promising. However, the relationships between structure, composition, crystallinity, and photocatalytic performance are still indistinct. Here, amorphous ultrathin CoO nanowires and polyoxometalate incorporated nanowires with even lower crystallinity were synthesized. The POM‐incorporated ultrathin nanowires exhibit high photocatalytic syngas production activity, reaching H2 and CO evolution rates of 11555 and 4165 μmol g?1 h?1 respectively. Further experiments indicate that the ultrathin morphology and incorporation of POM both contribute to the superior performance. Multiple characterizations reveal the enhanced charge–hole separation efficiency of the catalyst would facilitate the photocatalysis. 相似文献
932.
Xinyu Li Lianghao Song Daowei Gao Baotao Kang Prof. Huaiqing Zhao Prof. Cuncheng Li Prof. Xun Hu Prof. Guozhu Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4419-4424
Heterogeneously catalyzed, selective hydrogenation in the liquid phase is widely used in industry for the synthesis of chemicals. However, it can be a challenge to prevent active nanoparticles (e.g., palladium) from aggregation/leaching and meanwhile achieve high conversion as well as selectivity, especially under mild conditions. To address these issues, a CeO2 nanotube/Pd@MIL-53(Al) sandwich-structured catalyst has been prepared in which the MIL-53(Al) porous shell can efficiently stabilize the palladium nanoparticles. When this catalyst was used in a tandem catalytic reaction involving the dehydrogenation of ammonia borane and the hydrogenation of phenylacetylene, remarkably, the hydrogen released from the dehydrogenation of ammonia borane boosted the catalytic process, with 100 % conversion of phenylacetylene and a selectivity of 96.2 % for styrene, even at room temperature and atmospheric pressure, within 1 min. This work therefore provides an alternative strategy for balancing the conversion and selectivity of liquid-phase hydrogenation reactions. 相似文献
933.
Dr. Bo Xu Dr. Wen Xun Shaobin Su Prof. Dr. Hongbin Zhai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(38):16617-16621
Cyclopianes are novel diterpenes featuring a highly strained 6/5/5/5 tetracyclic core embedded with 6–8 consecutive stereocenters. The concise total syntheses of (−)-conidiogenone B, (−)-conidiogenone, and (−)-conidiogenol have been accomplished in 14–17 steps. The present work features a HAT-mediated alkene–nitrile cyclization to access the cis-biquinane, a Nicholas/Pauson–Khand reaction to construct the linear triquinane, and a Danheiser annulation to afford the congested angular triquinane skeleton. 相似文献
934.
Yuying Gao Wei Nie Qianhong Zhu Xun Wang Shengyang Wang Prof. Fengtao Fan Prof. Can Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18375-18380
Controlling the interaction of polarization light with an asymmetric nanostructure such as a metal/semiconductor heterostructure provides opportunities for tuning surface plasmon excitation and near-field spatial distribution. However, light polarization effects on interfacial charge transport and the photocatalysis of plasmonic metal/semiconductor photocatalysts are unclear. Herein, we reveal the polarization dependence of plasmonic charge separation and spatial distribution in Au/TiO2 nanoparticles under 45° incident light illumination at the single-particle level using a combination of photon-irradiated Kelvin probe force microscopy (KPFM) and electromagnetic field simulation. We quantitatively uncover the relationship between the local charge density and polarization angle by investigating the polarization-dependent surface photovoltage (SPV). The plasmon-induced photocatalytic activity is enhanced when the polarization direction is perpendicular to the Au/TiO2 interface. 相似文献
935.
本文描述了一种新的测量二氧化硫的荧光型光纤传感器。溶于内充液的奎宁被用作敏感物,通过气透膜将内充液与水溶液分开。传感器对二氧化硫的响应范围是3×10~(-6)~3×10~(-4)mol/L。报道了传感器的重现性、稳定性、响应时间和选择性。用该传感器测定了含二氧化硫的实际样品并与碘量法进行了比较。 相似文献
936.
Chen J Zhou X Snyder GJ Uher C Chen N Wen Z Jin J Dong H Qiu P Zhou Y Shi X Chen L 《Chemical communications (Cambridge, England)》2011,47(44):12173-12175
Lithium intercalation and de-intercalation processes have been used to fabricate bulk Bi(2)Se(0.3)Te(2.7) with internal nanostructures. The doped Li content can be precisely controlled through this method. It provides a chance to directly optimize electrical properties when preparing nano-structured materials, leading to the optimum carrier concentration for improved thermoelectric figure of merit. 相似文献
937.
Hong‐Bo Huang Ze‐En Xiao Xiao‐Jun Feng Cai‐Huan Huang Xun Zhu Jian‐Hua Ju Meng‐Feng Li Yong‐Cheng Lin Lan Liu Zhi‐Gang She 《Helvetica chimica acta》2011,94(9):1732-1740
Four new dimeric naphtho‐γ‐pyrones, named rubasperone D ( 1 ), rubasperone E ( 2 ), rubasperone F ( 3 ), and its atropisomer rubasperone G ( 4 ), together with four known monomeric naphtho‐γ‐pyrones, TMC 256 A1 ( 5 ), rubrofusarin B ( 6 ), fonsecin ( 7 ), and flavasperone ( 8 ), were isolated from the mangrove endophytic fungus Aspergillus tubingensis (GX1‐5E) cultivated in solid rice medium. Their structures were elucidated by spectroscopic methods, including IR, 1D‐ and 2D‐NMR, and MS. In the in vitro cytotoxicity assays, 5 displayed inhibitory activities against tumor cell lines of MCF‐7, MDA‐MB‐435, Hep3B, Huh7, SNB19, and U87 MG with IC50 values between 19.92 and 47.98 μM . Compounds 1, 6 , and 8 also showed mild cytotoxic activity. 相似文献
938.
Jian‐Xin Guo Li Guan Fang Bian Qing‐Xun Zhao Ying‐Long Wang Bao‐Ting Liu 《Surface and interface analysis : SIA》2011,43(6):940-944
The adsorption possibilities of oxygen atoms at Al (111) surface for different oxygen atom coverages (Θ) from 0.25 to 1 ml have been studied using first principles based on density functional theory with generalized gradient approximation. The results show that the interstitial sites on Al (111) surface are relatively stable, in which binding energies are 0.6 ~ 1 eV/atom lower than those on surface face centered cubic (fcc) sites for the different coverages. The binding energy and work function of the oxygen‐adsorbed surface increase with the oxygen atom coverage. Moreover, the oxygen atom at one tetrahedral site of Al (111) subsurface becomes more and more unstable with the decrease of the coverage, and it moves up to the Al (111) surface hexagonal close packed (hcp) site at Θ = 0.25. All the octahedral absorption sites are also unstable in relatively lower coverages (Θ = 0.5 and 0.25). The bond length and overlap population between Al and O, including the relaxation effects on the oxygen atom coverage are discussed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
939.
采用三层共压-共烧结法, 并涂覆La0.8Sr0.2MnO3 (LSM)阴极, 制备了梯度Ni-YSZ阳极结构的固体氧化物燃料电池(SOFC)(大孔Ni-YSZ|微孔Ni-YSZ|YSZ|LSM) (YSZ: Y2O3稳定的ZrO2; LSM: Sr 掺杂的LaMnO3).通过浸渍法在大孔Ni-YSZ 基底中沉积占总重量约1%的Cu-CeO2抗积碳催化剂, 形成梯度Cu-CeO2-Ni-YSZ复合阳极. 分别以CH4和H2为燃料, 空气为氧化剂, 测定了构造的SOFC输出电性能和长期稳定性. 结果表明,三层共压-共烧结法制备的梯度阳极SOFC, 层间结合紧密无缺陷, 阳极梯度孔结构明显, YSZ膜致密无缺陷.在850℃下操作, 以梯度Ni-YSZ 阳极制备的SOFC, 燃料由H2切换为甲烷时, 最大功率密度由284 mW·cm-2下降到143 mW·cm-2; 而以Cu-CeO2-Ni-YSZ 复合阳极构造的SOFC出现相反趋势, H2切换为甲烷后最大输出由176 mW·cm-2增加到196 mW·cm-2. 在250 mA·cm-2负荷下, 梯度Ni-YSZ阳极支撑的直接甲烷SOFC仅稳定运转10 h 便出现明显衰减, 阳极中积碳严重; 但Cu-CeO2-Ni-YSZ 复合阳极支撑SOFC连续运转50 h, 输出电压与输出功率密度基本不变, 电镜观察不到积碳. 相似文献
940.
为了解重庆地区自身免疫性甲状腺疾病(AITD)患者外周血sFas与sFasL的表达情况与尿碘的关系,探讨AITD发病的机制,采用病例对照研究,检测并分析各组人群外周血sFas和sFasL及尿碘的含量。结果表明,GD与HT组体内的碘营养状况高于对照组(P〈0.0001),GD组的sFas含量高于对照组,GD和HT组的sFasL含量高于对照组,其差异具有统计学意义。外周血中sFas与sFasL之间存在负相关关系,随着尿碘含量的增高,sFas含量下降,sFasL含量升高。提示AITD患者体内存在高碘营养状况,高碘可能导致细胞的过度凋亡,从而诱发AITD。 相似文献