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991.
Strongly Coupled Pt–Ni2GeO4 Hybrid Nanostructures as Potential Nanocatalysts for CO Oxidation 下载免费PDF全文
Zhuo Wang Shuang Yao Jing Feng Dapeng Liu Shuyan Song Prof. Hongjie Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(42):14768-14771
A facile and low‐cost method has been developed to successfully fabricate 3D flower‐like and sphere‐like Ni2GeO4 nanostructures with tunable sizes and shapes. It is found that the hard template, polymethyl methacrylate (PMMA) nanopsheres, is essential to the formation of the final products. The as‐prepared nanostructures can serve as an outstanding support for Pt nanoparticles after surface modification with L ‐lysine. In the catalytic test of CO oxidation, Pt–Ni2GeO4 nanoflowers exhibited much higher catalytic performance compared with Pt–Ni2GeO4 nanospheres, representing a typical size‐dependent catalytic property. 相似文献
992.
Diastereoselective Synthesis of Cyclopentanoids: Applications to the Construction of the ABCD Tetracyclic Core of Retigeranic Acid A 下载免费PDF全文
Junlin Zhang Xiao Wang Shuang Li Dian Li Song Liu Prof. Dr. Yu Lan Dr. Jianxian Gong Prof. Dr. Zhen Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12596-12600
A concise and efficient approach for the construction of the tetracyclic carbon skeleton of retigeranic acid A is described. The key transformations include a novel Rh‐catalyzed [3+2] cycloaddition of enyol to afford cyclopentanoid E , bearing two contiguous quaternary stereocenters at the bridgehead positions, and an intramolecular Pauson–Khand reaction to construct the advanced tetracyclic core structure of retigeranic acid A. 相似文献
993.
Mesoporous Carbon Nanofibers Embedded with MoS2 Nanocrystals for Extraordinary Li‐Ion Storage 下载免费PDF全文
Dr. Shan Hu Prof. Wen Chen Dr. Evan Uchaker Prof. Jing Zhou Prof. Guozhong Cao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18248-18257
MoS2 nanocrystals embedded in mesoporous carbon nanofibers are synthesized through an electrospinning process followed by calcination. The resultant nanofibers are 100–150 nm in diameter and constructed from MoS2 nanocrystals with a lateral diameter of around 7 nm with specific surface areas of 135.9 m2 g?1. The MoS2@C nanofibers are treated at 450 °C in H2 and comparison samples annealed at 800 °C in N2. The heat treatments are designed to achieve good crystallinity and desired mesoporous microstructure, resulting in enhanced electrochemical performance. The small amount of oxygen in the nanofibers annealed in H2 contributes to obtaining a lower internal resistance, and thus, improving the conductivity. The results show that the nanofibers obtained at 450 °C in H2 deliver an extraordinary capacity of 1022 mA h g?1 and improved cyclic stability, with only 2.3 % capacity loss after 165 cycles at a current density of 100 mA g?1, as well as an outstanding rate capability. The greatly improved kinetics and cycling stability of the mesoporous MoS2@C nanofibers can be attributed to the crosslinked conductive carbon nanofibers, the large specific surface area, the good crystallinity of MoS2, and the robust mesoporous microstructure. The resulting nanofiber electrodes, with short mass‐ and charge‐transport pathways, improved electrical conductivity, and large contact area exposed to electrolyte, permitting fast diffusional flux of Li ions, explains the improved kinetics of the interfacial charge‐transfer reaction and the diffusivity of the MoS2@C mesoporous nanofibers. It is believed that the integration of MoS2 nanocrystals and mesoporous carbon nanofibers may have a synergistic effect, giving a promising anode, and widening the applicability range into high performance and mass production in the Li‐ion battery market. 相似文献
994.
Dioxygen Binding in the Active Site of Histone Demethylase JMJD2A and the Role of the Protein Environment 下载免费PDF全文
Wilian A. Cortopassi Robert Simion Charles E. Honsby Prof. Tanos C. C. França Prof. Robert S. Paton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18983-18992
JMJD2A catalyses the demethylation of di‐ and trimethylated lysine residues in histone tails and is a target for the development of new anticancer medicines. Mechanistic details of demethylation are yet to be elucidated and are important for the understanding of epigenetic processes. We have evaluated the initial step of histone demethylation by JMJD2A and demonstrate the dramatic effect of the protein environment upon oxygen binding using quantum mechanics/molecular mechanics (QM/MM) calculations. The changes in electronic structure have been studied for possible spin states and different conformations of O2, using a combination of quantum and classical simulations. O2 binding to this histone demethylase is computed to occur preferentially as an end‐on superoxo radical bound to a high‐spin ferric centre, yielding an overall quintet ground state. The favourability of binding is strongly influenced by the surrounding protein: we have quantified this effect using an energy decomposition scheme into electrostatic and dispersion contributions. His182 and the methylated lysine assist while Glu184 and the oxoglutarate cofactor are deleterious for O2 binding. Charge separation in the superoxo‐intermediate benefits from the electrostatic stabilization provided by the surrounding residues, stabilizing the binding process significantly. This work demonstrates the importance of the extended protein environment in oxygen binding, and the role of energy decomposition in understanding the physical origin of binding/recognition. 相似文献
995.
996.
997.
Abdul Raheem Keeri Dr. Andrea Gualandi Prof. Dr. Andrea Mazzanti Prof. Dr. Janusz Lewinski Prof. Dr. Pier Giorgio Cozzi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(52):18949-18952
The first catalytic asymmetric addition of TosMIC to unactivated ketones is presented. A combination of Me2Zn and aminoalcohol catalyst promoted the aldol addition/cyclization reaction to render oxazolines possessing a fully substituted stereocenter with excellent yields (up to 92 %), high enantioselectivities (up to 96 %), and complete diastereoselectivity. The chiral oxazolines were then used to give, after a straightforward acid hydrolysis, enantioenriched building blocks bearing tertiary alcohol motifs such as hydroxylaldehydes, hydroxylacids, and hydroxylesters without racemization. 相似文献
998.
999.
采用溶胶-凝胶法制备CaO-P2O5-SiO2-Na2O-B2O3体系前驱体粉末,用CaF2替代部分CaO再次制备前驱体粉末。 通过TG-DSC分析确定结晶温度为865 ℃,经过热处理获得主晶相为Na6Ca3Si6O18的玻璃陶瓷。 通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)等技术手段及体外生物活性实验分析玻璃陶瓷的显微结构及性能。 结果表明,CaF2的加入能提高玻璃陶瓷的体积密度、抗折强度和弹性模量,并且不会破坏玻璃陶瓷的生物活性。 相似文献
1000.
通过两步水热法合成了一种新型的还原氧化石墨烯(RGO)修饰的Bi2WO6(Bi2WO6-RGO), 结果表明其在可见光下的光催化性能得到了显著的提高. 研究了RGO在Bi2WO6-RGO中的含量对其光催化性能的影响, 从而确定出RGO相对于Bi2WO6的最佳掺杂质量比值为1%. 通过扫描电镜(SEM)研究发现, RGO并没有改变Bi2WO6光催化剂的结构和形貌. Bi2WO6-RGO在可见光下的光催化性能得以提高可以归功于RGO. 其可能的机理是石墨烯的存在有利于光生载流子(激子)的分离, 从而导致产生更多的O2·-用于有机染料污染物(如罗丹明B (RhB))的降解. RhB分子在石墨烯上的有效吸附可能也是导致Bi2WO6-RGO光催化性能提高的另一原因. 相似文献