La掺杂和空位对ZnS磁性和光学性能影响的第一性原理研究

利用密度泛函理论框架下的平面波超软赝势法,通过第一性原理对La掺杂与Zn空位(V_(Zn))及La掺杂与S空位(V_S)共存的ZnS体系的电子结构、磁性机理、形成能及吸收光谱进行了研究.结果表明, La掺杂与空位(V_(Zn)或V_S)的空间位置最近时,掺杂体系的形成能最低,体系最稳定.另外,La掺杂与Zn空位共存时,体系具有磁性,且体系的净磁矩与La原子与Zn空位的相对位置有关;La掺杂与S空位共存时,掺杂体系无磁性,但此时体系的禁带宽度最窄且吸收光谱红移最显著.     

Controllably asymmetric beam splitting via gap-induced diffraction channel transition in dual-layer binary metagratings

In this work, we designed and studied a feasible dual-layer binary metagrating, which can realize controllable asymmetric transmission and beam splitting with nearly perfect performance. Owing to ingenious geometry configuration, only one meta-atom is required to design for the metagrating system. By simply controlling air gap between dual-layer metagratings, high-efficiency beam splitting can be well switched from asymmetric transmission to symmetric transmission. The working principle lies on gap-induced diffraction channel transition for incident waves from opposite directions. The asymmetric/symmetric transmission can work in a certain frequency band and a wide incident range. Compared with previous methods using acoustic metasurfaces, our approach has the advantages of simple design and tunable property and shows promise for applications in wavefront manipulation, noise control and one-way propagation.     

An improved evaluation of the neutron background in the PandaX-Ⅱ experiment

In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.     

Dynamics of partially obstructed breakup of bubbles in microfluidic Y‐junctions

For revealing the dynamics of partially obstructed breakup of bubbles in microfluidic Y‐junctions, the combination of dimensionless power‐law and geometric model was applied to study the effects of capillary number, bubble length, and channel angle on the bubble rupture process. In the squeezing process, the gas‐liquid interface curve follows the parabolic model. For the evolution of the bubble neck during breakup, the increase of the bubble length, the channel angle, and the capillary number leads to the decrease of the focus distance α. The chord m increases with the increase of the capillary number and the decrease of the bubble length, and it would reach the maximum value when the channel angle is 90°. In the fast pinch‐off stage during bubble breakup, the bubble's neck curve no longer conforms to the parabolic model so the focus and chord no longer exist. For the evolution of the bubble head during breakup, the value of γ approaches 1 with the increase of the capillary number and the bubble length, and with the close of the channel angle to 90°. It is found that the quadrilateral model can be applied for the partially obstructed rupture of bubbles in the symmetrical microfluidic Y‐junction.     

Influence of neodymium on mitochondrial metabolism: a thermokinetic perspective

Journal of Thermal Analysis and Calorimetry - Nd compounds have been widely used for the promotion of growth of plant due to their excellent biophysical and biochemical properties. Mitochondria are...     

大处着眼，小处入手——基金委化学科学部2019年基金项目会议评审工作的几点尝试和思考

The National Natural Science Foundation of China (NSFC) is a vital government agency supporting basic research and people to create knowledge and meet major national needs, where a rigorous and objective merit-based peer review mechanism is the key to funding the most promising research proposals. This invited comment overviews some recent attempts aimed at bettering the academic evaluation environment at the Department of Chemical Science in 2019, through measures such as grouped panel committee meetings, standardized panel committee meeting procedures, and review process refinement to improve the project review at panel committee meeting levels.     

Precise measurement and control of the pressure-driven flows for microfluidic systems

The pressure-driven device is designed and the flow rates of the microfluidic systems can be supplied by the pressure-driven flows, which can significantly reduce the flow-rate fluctuations coming from the pump source. For pressure-driven flows, the flow rates of the fluids can be predicted by measuring the pressure drop along a polytetrafluoroethylene (PTFE) tubing. Especially, by varying the geometrical parameters of the PTFE tubing, the predicted flow rates of the fluids are compared with the experimental measurements, and the testing precision of the pressure-driven flows can be obtained. Meanwhile, the dynamic characteristics of the open-loop and closed-loop control pressure-driven device are comparatively studied. Particularly, a proportional and integral (PI) controller is integrated with the closed-loop control pressure-driven device, and the effects of the parameters of the PI controller on the dynamic characteristics of the pressure-driven devices are mainly discussed. Most importantly, by improving the dynamic characteristics of the pressure-driven devices, precise measurement and control of the pressure-driven flows can be achieved for microfluidic systems.     

Silica microbeads capture fetal nucleated red blood cells for noninvasive prenatal testing of fetal ABO genotype

ABO hemolytic disease of the newborn (ABO-HDN), which may cause neonatal jaundice and polycythemia, or even stillbirth or neonatal death, is widespread in China. Prenatal testing for the fetal ABO blood group can reduce unnecessary concerns or ensure prompt treatment. Herein, we presented a method to employ high-density silica microbeads (SiO₂ MBs) for capturing fetal nucleated red blood cells (fnRBCs) in maternal peripheral blood, and we detected the ABO genotype of the fetus using these captured cells. We evaluated 52 patients using the SiO₂ MBs. Among 26 pregnant women with type O blood, 8 (30.8%) of the fetuses had type A blood, 5 (19.2%) had type B blood, and 13 (50%) had type O blood. SRY genes were detected in all 27 male fetuses. This study represents a simple and effective method for noninvasive prenatal detection of the fetal ABO genotype. We believe that this method has great potential for noninvasive prenatal testing of the fetal Rh blood group and other fetal diseases as well.     

Hierarchical Carbon Nanowire/Ni@MnO2 Nanocomposites for High-Performance Asymmetric Supercapacitors

A 3D hierarchical carbon cloth/nitrogen-doped carbon nanowires/Ni@MnO₂ (CC/N-CNWs/Ni@MnO₂) nanocomposite electrode was rationally designed and prepared by electrodeposition. The N-CNWs derived from polypyrrole (PPy) nanowires on the carbon cloth have an open framework structure, which greatly increases the contact area between the electrode and electrolyte and provides short diffusion paths. The incorporation of the Ni layer between the N-CNWs and MnO₂ is beneficial for significantly enhancing the electrical conductivity and boosting fast charge transfer as well as improving the charge-collection capacity. Thus, the as-prepared 3D hierarchical CC/N-CNWs/Ni@MnO₂ electrode exhibits a higher specific capacitance of 571.4 F g⁻¹ compared with those of CC/N-CNWs@MnO₂ (311 F g⁻¹), CC/Ni@MnO₂ (196.6 F g⁻¹), and CC@MnO₂ (186.1 F g⁻¹) at 1 A g⁻¹ and remarkable rate capability (367.5 F g⁻¹ at 10 A g⁻¹). Moreover, asymmetric supercapacitors constructed with CC/N-CNWs/Ni@MnO₂ as cathode material and activated carbon as anode material deliver an impressive energy density of 36.4 W h kg⁻¹ at a power density of 900 W kg⁻¹ and a good cycling life (72.8 % capacitance retention after 3500 cycles). This study paves a low-cost and simple way to design a hierarchical nanocomposite electrode with large surface area and superior electrical conductivity, which has wide application prospects in high-performance supercapacitors.     

Supramolecular Assembly of TPE-Based Glycoclusters with Dicyanomethylene-4H-pyran (DM) Fluorescent Probes Improve Their Properties for Peroxynitrite Sensing and Cell Imaging

Two red-emitting dicyanomethylene-4H-pyran (DM) based fluorescent probes were designed and used for peroxynitrite (ONOO⁻) detection. Nevertheless, the aggregation-caused quenching effect diminished the fluorescence and restricted their further applications. To overcome this problem, tetraphenylethylene (TPE) based glycoclusters were used to self-assemble with these DM probes to obtain supramolecular water-soluble glyco-dots. This self-assembly strategy enhanced the fluorescence intensity, leading to an enhanced selectivity and activity of the resulting glyco-dot comparing to DM probes alone in PBS buffer. The glyco-dots also exhibited better results during fluorescence sensing of intracellular ONOO⁻ than the probes alone, thereby offering scope for the development of other similar supramolecular glyco-systems for chemical biological studies.