Quantum degenerate Bose–Fermi atomic gas mixture of 23Na and 40K

We report a compact experimental setup for producing a quantum degenerate mixture of Bose23Na and Fermi40K gases. The atoms are collected in dual dark magneto–optical traps(MOT) with species timesharing loading to reduce the light-induced loss, and then further cooled using the gray molasses technique on the D2line for23Na and D1line for40K. The microwave evaporation cooling is used to cool23Na in |F = 2, mF= 2〉 in an optically plugged magnetic trap, meanwhile,40K in |F = 9/2, mF= 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where23Na atoms are immediately transferred to |1, 1〉 for further effective cooling to avoid the strong three-body loss between23Na atoms in |2, 2〉 and40K atoms in |9/2, 9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of40K with 1.9 × 10^(5) atoms at T/TF= 0.5 in the |9/2, 9/2〉 hyperfine state coexists with a Bose–Einstein condensate(BEC) of23Na with 8 × 10^(4) atoms in the |1, 1〉 hyperfine state at 300 n K. We also can produce the two species mixture with the tunable population imbalance by adjusting the 23Na magneto–optical trap loading time.

Electrocatalytic conversion of CO_(2)to CH_(4)over Cu-based cluster via atomically precise local environment modulation

The development of low-cost,high-performance catalysts at the atomic scale has become a challenging issue for the large-scale applications of renewable clean energy technologies.Herein,on the basis of density functional theory calculation,we systematically investigate the effect of the local environment on the activity and selectivity of electrochemical carbon dioxide reduction reaction over single/multi-atom alloy clusters formed by the transition metal(Fe,Co,and Ni)-doped Cu13/55 clusters.Our findings reveal that the catalytic performance of multi-atom alloy clusters far exceeds that of Cu(211)surface.Notably,the Co666 configuration exhibits exceptional performance with a remarkably low free energy barrier of just 0.33 eV.Furthermore,our investigations demonstrate that catalytic performance is predominantly determined by the relative proportion of modifying metallic dopant species that generate a coordination number of 6.This ratio principally influences the adsorption strength of key intermediates(HCOO*and H2COO*).Bader charge analyses and free energy calculations elucidate a new mechanistic pathway,wherein the hydrogenation of CO_(2)at C-sites catalyzes the reduction of CO_(2)to CH_(4).This theoretical research provides valuable insights into the fundamental processes and energy landscapes involved in converting CO_(2)to CH_(4)on the studied catalytic structure,potentially paving the way for more efficient and sustainable carbon dioxide utilization strategies.

眼表微环境与泪膜稳态对视觉质量影响的新认识

2020年发布的中国干眼专家共识第一次将眼表微环境的概念新增到了干眼的定义中。强调了泪膜不稳定和眼表微环境失衡在干眼发病机制中的重要地位,并将视功能障碍作为干眼病情发展的重要结局之一。为了加强对新共识的认识,推动相关的基础与临床研究的开展及转化,为广大干眼患者提供更为细致的诊疗建议,专家组于2021年3年26日在江西吉安召开讨论会,对眼表微环境和泪膜稳态这两方面的研究现状及存在的问题进行分析,主要围绕干眼的这两个核心机制的新认识、与视觉质量的关系、临床的评估和治疗手段的建议和未来发展新方向等提出建议和推荐意见。