Single palladium atoms stabilized byβ-FeOOH nanorod with superior performance for selective hydrogenation of cinnamaldehyde

Atomically dispersed single atom catalysts represent an ideal means of converting less valuable organics into value-added chemicals of interest with high efficiency.Herein,we describe a facile synthetic approach to create defect-containingβ-FeOOH doped with isolated palladium atoms that bond covalently to the nearby oxygen and iron atoms.The presence of singly dispersed palladium atoms is confirmed by spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements.This single palladium atom catalyst manifests outstanding catalytic efficiency(conversion:99%;selectivity 99%;turnover frequency:2,440 h^(-1))in the selective hydrogenation of cinnamaldehyde to afford hydrocinnamaldehyde.Experimental measurements and density functional theory(DFT)calculations elucidate the high catalytic activity and the strong metal-support interaction stem from the unique coordination environment of the isolated palladium atoms.These findings may pave the way for the facile construction of single atom catalysts in a defect-mediated strategy for efficient organic transformations in heterogeneous catalysis.

Gosport必须成为改变医疗卫生行业等级制度的转折点

"如果要杜绝类似Mid Staffordshire和Morecambe Bay的丑闻,所有医疗行业员工都应有权质疑各级同事的决策,并表达他们的担忧而不会受到任何报复",Philip Darbyshire和David Thompson写道。

河流污染混合区特性计算方法及排污口分类准则Ⅰ：原理与方法

在连续点源离岸排放条件下,从考虑河流纵向移流、横向扩散的简化二维方程解析解出发,对基于环境扩散的宽阔河流探讨了污染混合区的计算方法。给出了污染混合区边界曲线的标准方程及无量纲形式;分别给出了离岸系数0≤η≤2和η>2两种类型污染混合区5个特征点各参数及面积与离岸系数η的关系曲线,分析了各参数的变化规律,提出了以离岸系数η作为判据的分类参数和临界条件。给出了河流岸边、离岸与中心排放的分类判别准则:(1)当0≤η≤0.7时,简化为岸边(近岸)排放类型;(2)当0.7<η<2.3时,称为离岸排放类型;(3)当η≥2.3时,简化为中心排放类型。对河流离岸排放提出了达到全断面均匀混合距离的计算公式,比现行公式有所改进。为河流排污口位置的优化设计和控制排污量计算提供了分类、简便、快捷的理论方法,具有重要实用价值。

如何优化脓毒症患者的抗生素使用疗程?

机体对感染的反应失衡时,就可能发生脓毒症。脓毒症可造成危及生命的器官功能障碍。2017年全球约有49000000例脓毒症患者,其中11000000例因该病死亡。因脓毒症住院的患者中,17%在医院内死亡,另有15%的患者在出院后一年内死亡。