长江经济带工业集聚对水环境污染的影响——基于空间计量与门槛效应的检验

经济发展与生态环境动态良性循环已经成为社会经济发展的重要议题。为实现长江经济带高质量发展，以2007—2018年长江经济带11个省市为样本，采用空间计量和面板门槛模型考察工业集聚与水环境污染之间的关系。研究表明：长江经济带各省市水环境污染具有显著的空间自相关性；长江经济带工业集聚水平和水环境污染表现出先降低后增强的“U”形变化特征，说明工业集聚水平对水环境污染的影响存在一个阈值；长江经济带工业集聚产生的规模效应和结构效应对水环境污染存在显著的双门槛效应，在不同的工业集聚水平下，规模效应和结构效应表现出不同的外部性特征；工业集聚产生的技术溢出效应对水环境污染的影响同样具有显著的双门槛作用；随着各地区工业集聚水平的提高，技术溢出效应对水环境污染的减排作用表现出先强后弱的趋势。     

Accelerating water dissociation kinetic in Co9S8 electrocatalyst by mn/N Co-doping toward efficient alkaline hydrogen evolution

Electrocatalytic hydrogen evolution under alkaline media holds great promising in hydrogen energy production. Transition-metal sulfides (TMSs) are attractive for electrocatalytic alkaline hydrogen evolution, yet their catalytic performance is unsatisfactory owing to the sluggish water dissociation kinetics. Herein, a Mn/N co-doping strategy is proposed to regulate the water dissociation kinetics of Co₉S₈ nanowires array grown on nickel foam thus improve the activity of hydrogen evolution reaction (HER). The optimal Mn/N co-doping Co₉S₈ (Mn–N–Co₉S₈) catalyst achieves low overpotentials of 102 and 238 mV at 10 and 100 mA cm^?2 in the 1 M KOH solution, respectively, remarkably higher than the single-doping Mn–Co₉S₈ and N–Co₉S₈ as well as superior to many reported Co₉S₈-based HER electrocatalysts. Density functional theory (DFT) calculation results confirm that the water dissociation barrier of the Mn–N–Co₉S₈ is reduced significantly owing to the synergistic co-doping of Mn and N, which accounts for the enhanced alkaline HER performance. This study offers an effective strategy to enhance the alkaline HER activity of TMSs by accelerating water dissociation kinetic via the cation and anion co-doping strategy.     

Prophylactic effects of probiotics on respiratory viruses including COVID-19: a review

Food Science and Biotechnology - Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is mainly transmitted through respiratory droplets....     

Potassium ions stabilized hollow Mn-based prussian blue analogue nanocubes as cathode for high performance sodium ions battery

Mn-based Prussian blue analogue is regarded as one of the promising cathodes for sodium ions battery owing to its high theoretical capacity and low cost. However, the unstable structure during charging/discharging process and the poor cycle life hinder its commercial application. In this work, potassium ions stabilized hollow Mn-based Prussian blue analogue is synthesized through a simple sodium citrate assisted method using for cathode of sodium-ions batteries. Although unique hollow structure could suffer volume variation during charging/discharging process, the K⁺ is introduced to further stabilize its structure. The PBAs cathode exhibits a high reversible specific capacity of 128 mA h g^?1 at 50 mA and superior rate performance of 72 mA h g^?1 at a high current density of 3200 mA g^?1, which is attributed to its stable structure and enhanced sodium ions transport kinetics. Ex-situ XRD/Raman tests and electrochemical measurements further prove the synergistic effect of various alkali ions (K⁺/Na⁺) and unique hollow structure. They work together to improve the structural stability and promote sodium ions diffusion rate of Mn-based PBAs.     

The influence of small hydrogen addition on the structural and magnetocaloric properties of high-purity nanocrystalline terbium

Hydrogen absorption often induces changes of various properties of rare-earth metals. In this paper, we study the influence of hydrogenation on the structural, magnetic and magnetocaloric properties of high-purity nanocrystalline terbium. Strong (00l) texture present in the parent Tb sample is practically destroyed after the hydrogenation procedure. We observe formation of agglomerates of different sizes and shapes depending on the hydrogen content in the samples. We find traces of β-hydride (TbH₂) in the main α-hydride TbH_x phase. For TbH_x with x = 0.25 and 0.5 at.H/f.u. The effect of hydrogenation on the magnetocaloric properties is studied in magnetic fields up to 9 T. The magnetocaloric effect decreases after hydrogenation. The -ΔS_M(T) curves feature a table-like effect in the vicinity of the magnetic phase transitions in magnetic fields exceeding 1 T.     

Three-dimensional finite element analysis of geosynthetic-reinforced soil walls with turning corners

The paper presents in-depth three-dimensional finite element analyses investigating geosynthetic-reinforced soil walls with turning corners. Validation of the 3D numerical procedure was first performed via comparisons between the simulated and reported results of a benchmark physical modeling built at the Royal Military College of Canada. GRS walls with corners of 90°, 105°, 120°, 135°, 150°, and 180° were simulated adopting the National Concrete Masonry Association guidelines. The behaviors of the GRS walls with corners, including the lateral facing displacement, maximum reinforcement load, factor of safety, potential failure surface, vertical separation of facing blocks, and types of corners were carefully evaluated. Our comprehensive results show (i) minimum lateral displacement occurs at the corner; (ii) lower strength of reinforcements are required at the corner; (iii) higher corner angles lead to lower stability; (iv) potential failure surface forms earlier at the end walls; (v) deeper potential failure surfaces are found at the corners; (vi) larger numbers of vertical separations are found at walls with smaller corner angles. The paper highlighted the salient influence of the corners on the behaviors of GRS walls and indicated that a 3D analysis could reflect the required reinforcement length and the irregular formation of the potential failure surfaces.     

用背角准弹散射研究近库仑势垒能区重离子核反应

利用背角准弹散射的方法开展了近库仑势垒（近垒）能区重离子核反应机制的研究。高精度测量了深垒下能区16O+152,154Sm、184W、¹⁹⁶Pt和²⁰⁸Pb等体系的背角准弹散射激发函数，用耦合道计算抽取了核势的表面弥散参数，结果表明考虑耦合道效应得到的表面弥散参数值正常。基于背角准弹散射势垒分布对核结构的敏感性，尝试用深垒下能区16O+152Sm、170Er和174Yb等体系的背角准弹散射来抽取形变靶核的十六极形变参数，所抽取值与已有结果趋势一致，说明了该方法的可行性。此外，研究了弱束缚核体系的破裂效应，其表现为背角准弹势垒分布较全熔合势垒分布向低能移动，所得结果进一步说明势垒分布同时含有核结构和核反应机制的信息。     

我国部分省份环境气溶胶中239+240 Pu的测定

采用阴离子交换树脂分离结合α谱仪测量的方法对我国7个省份环境气溶胶中^239+240Pu含量进行测定,实验全程回收率为60.8%～94.6%,对气溶胶中^239+240Pu的最小可探测限为0.008 μBq/m³。普通环境气溶胶采样量需要达到30 000 m³以上,在应急情况等特殊环境气溶胶采样量为10 000 m³可满足要求。一般情况下气溶胶中²¹⁰Po含量比^239+240Pu高4～6个数量级,在分析和测量中要关注²¹⁰Po对^239+240Pu测量的影响。测量结果显示,我国普通省份环境气溶胶中^239+240Pu含量为0.009～0.099 μBq/m³,与美国、韩国和西班牙等国家空气气溶胶中的Pu含量处于同一水平。