Development of a ~3He Gas Filling Station at the China Spallation Neutron Source

At the China Spallation Neutron Source(CSNS), we have developed a custom gas-filling station, a glassblowing workshop, and a spin-exchange optical pumping(SEOP) system for producing high-quality ~3He-based neutron spin filter(NSF) cells. The gas-filling station is capable of routinely filling ~3He cells made from GE180 glass of various dimensions, to be used as neutron polarizers and analyzers on beamlines at the CSNS. Performance tests on cells fabricated at our gas-filling station are conducted via neutron transmission and nuclear-magneticresonance measurements, revealing nominal filling pressures, and a saturated ~3He polarization in the region of 80%, with a lifetime of approximately 240 hours. These results demonstrate our ability to produce competitive NSF cells to meet the ever-increasing research needs of the polarized neutron research community.     

中空石墨碳材料作为电催化剂载体在直接乙醇燃料电池中的应用

以间苯二酚、苯酚与甲醛为前体,合成了一种中空石墨碳材料(hollow graphitic carbon,HGC).透射电镜(TEM)、N2吸附-脱附和Raman光谱测试结果表明,所制备的HGC为中孔结构,平均孔径为36nm.与商品Vulcan XC-72R相比,HGC中孔结构丰富,石墨化程度高.分别以HGC和XC-72R为载体制备了总金属载量为45%的PtSn/C电催化剂,X射线衍射和TEM结果表明这两个样品的平均粒径和晶格常数相近.单池性能测试表明,以45%PtSn/HGC为阳极催化剂的直接乙醇燃料电池的最大功率密度达到了62mW/cm2,与PtSn/XC-72R的54mW/cm2相比提高了近15%.     

碲化镓纳米片中单斜晶相和六方晶相共存的光谱特征（英文）

快速发展的二维层状材料为构建新型高效的微纳发光器件和光电探测器件提供了新的平台.其中碲化镓纳米片备受关注,这是因为碲化镓从少层到块体都具有极强的发光性能,因而可以降低二维微纳器件的制备条件.然而碲化镓纳米片具有单斜和六方等多种晶相,使其发光特性和光谱结构异常复杂,目前还缺少对不同厚度碲化镓纳米片荧光光谱的系统研究.本文研究了不同厚度碲化镓纳米片的荧光光谱和拉曼光谱,以及荧光光谱从低温(4 K)到室温的演化行为.通过光谱分析,发现单斜晶相和六方晶相可能同时共存于多层碲化镓纳米片中.为了阐述相关实验结果,构建了如下原子结构模型:其中六方晶相位于纳米片的顶层与底层,而单斜晶相位于纳米片的中间位置.基于温度依赖的荧光光谱,可以获得六方晶相的光学带隙为1.849 eV,且该激子峰只能在较高温度(>200 K)下和声子辅助下才能表现出显著的荧光发射行为.进一步的实验结果确定了六方晶相的激子-声子相互作用强度约为1.24 meV/K.本工作证实了碲化镓纳米片中单斜晶相与六方晶相共存的实验现象,为研究碲化镓纳米片的晶相变化和激子动力学,以及探究碲化镓的奇异物理化学特性,提供了新的见解.     

诺氟沙星-Tb3+-牛血清白蛋白相互作用的荧光光谱研究

采用诺氟沙星-Tb3 体系,在pH 9.0的Tris-HCl缓冲溶液中,利用牛血清白蛋白(BSA)能增强诺氟沙星的特征荧光的特性,建立了BSA的定量分析方法。结果表明:当诺氟沙星浓度/[Tb3 ]在1/8~1/12范围内时,BSA的加入量与体系的荧光增强(ΔF)有良好的线性关系,线性范围为0~25μg/mL,相关系数r=0.998。并初步探讨了BSA的存在对诺氟沙星-Tb3 体系荧光增强的作用机理。     

Synthesis of Halopyrazole Matrine Derivatives and Their Insecticidal and Fungicidal Activities

Matrine is a traditional botanical pesticide with a broad-spectrum biological activity that is widely applied in agriculture. Halopyrazole groups are successfully introduced to the C13 of matrine to synthesize eight new derivatives with a yield of 78–87%. The insecticidal activity results show that the introduction of halopyrazole groups can significantly improve the insecticidal activity of matrine on Plutella xylostella, Mythimna separata and Spodoptera frugiperda with a corrected mortality rate of 100%, which is 25–65% higher than matrine. The fungicidal activity results indicate that derivatives have a high inhibitory effect on Ceratobasidium cornigerum, Cibberella sanbinetti, Gibberrlla zeae and Collectot tichum gloeosporioides. Thereinto, 4-Cl-Pyr-Mat has the best result, with an inhibition rate of 23–33% higher than that of matrine. Therefore, the introduction of halogenated pyrazole groups can improve the agricultural activity of matrine.     

A guide to use fluorinated aromatic bulky cations for stable and high-performance 2D/3D perovskite solar cells: The more fluorination the better?

While serious stability issues impede the commercialization of perovskite solar cells(PSCs),twodimensional(2 D) perovskites based on fluorinated bulky cations have emerged as more intrinsically stable materials.However,the influence of fluorination degree of the bulky aromatic cation on the performance of resulting PSCs has not been scrutinized.Here,2 D perovskites(FxPEA)2 PbI₄(x=1,2,3,5) are grown in situ on the surface of the three-dimensional(3 D) perovskite and demonstrate effecti...     

Facile Synthesis of Porous Ag Crystals as SERS Sensor for Detection of Five Methamphetamine Analogs

Porous noble metal nanomaterials have attracted extensive attention due to their high specific surface area and surface plasmon resonance effect. However, it is difficult to form porous structures due to the high mobility and low reduction potential of noble metal precursors. In this article, we developed a facile method for preparing porous Ag with a controllable structure at room temperature. Two kinds of Ag crystals with different porous structures were successfully prepared by using AgCl cubes as sacrificial templates. Through the galvanic replacement reaction of Zn and AgCl, Ag crystals with a sponge-like porous structure were successfully prepared. Additionally, using NaBH₄ as the reducing agent, we prepared granular porous Ag cubes by optimizing the amount of reducing agent. Both the sponge-like and granular porous Ag cubes have clean and accessible surfaces. In addition, we used the prepared two porous Ag cubes as substrate materials for SERS detection of five kinds of methamphetamine analogs. The experimental results show that the enhancement effect of granular porous Ag is better than that of sponge-like porous Ag. Furthermore, we probed the hot spot distribution of granular porous Ag by Raman mapping. By using granular porous Ag as the substrate material, we have achieved trace detection of 5 kinds of methamphetamine analogs including Ephedrine, Amphetamine, N-Methyl-1-(benzofuran-5-yl)propan-2-amine (5-MAPB), N-Methyl-1-(4-methoxyphenyl)propan-2-amine (PMMA) and N-Methyl-1-(4-fluorophenyl)propan-2-amine (4-FMA). Furthermore, to achieve qualitative differentiation of analogs with similar structures we performed density functional theoretical (DFT) calculations on the Raman spectra of the above analogs. The DFT calculations provided the vibrational frequencies, Raman activities, and normal mode assignment for each analog, enabling the qualitative differentiation of the above analogs.     

DNA Interaction,DNA Photocleavage,Photocytotoxicity In Vitro,and Molecular Docking of Naphthyl-Appended Ruthenium Complexes

With the development of metal-based drugs, Ru(II) compounds present potential applications of PDT (photodynamic therapy) and anticancer reagents. We herein synthesized two naphthyl-appended ruthenium complexes by the combination of the ligand with naphthyl and bipyridyl. The DNA affinities, photocleavage abilities, and photocytotoxicity were studied by various spectral methods, viscosity measurement, theoretical computation method, gel electrophoresis, and MTT method. Two complexes exhibited strong interaction with calf thymus DNA by intercalation. Production of singlet oxygen (¹O₂) led to obvious DNA photocleavage activities of two complexes under 365 nm light. Furthermore, two complexes displayed obvious photocytotoxicity and low dark cytotoxicity towards Hela, A549, and A375 cells.     

具有聚集诱导发光特性的含氟有机金属配合物的研究进展

近年来,具有聚集诱导发光(aggregation-induced emission,AIE)特性的化合物由于在聚集态或固态发光量子效率较高而受到很多关注.含氟的功能化合物,由于氟原子的存在,往往具有独特的结构和物理、化学及生物学性质.根据中心金属和配体的种类,汇总了具有AIE性质的且含有氟代配体的有机金属配合物的研究进...     

Prisoner’s Dilemma Game with Cooperation-Defection Dominance Strategies on Correlational Multilayer Networks

As multilayer networks are widely applied in modern society, numerous studies have shown the impact of a multilayer network structure and the network nature on the proportion of cooperators in the network. In this paper, we use Barabási–Albert scale-free networks (BA) and Watts and Strogatz networks (WS) to build a multilayer network structure, and we propose a new strategy-updating rule called “cooperation-defection dominance”, which can be likened to dominant and recessive traits in biogenetics. With the newly constructed multilayer network structure and the strategy-updating rules, based on the simulation results, we find that in the BA-BA network, the cooperation dominance strategy can make the networks with different rs show a cooperative trend, while the defection dominance strategy only has an obvious effect on the network cooperation with a larger r. When the BA network is connected to the WS network, we find that the effect of strategy on the proportion of cooperators in the network decreases, and the main influencing factor is the structure of the network. In the three-layer network, the cooperation dominance strategy has a greater impact on the BA network, and the proportion of the cooperators is enhanced more than under the natural evolution strategy, but the promotion effect is still smaller than that of the two-layer BA network because of the WS network. Under the defection dominance strategy, the WS layer appears different from the first two strategies, and we conclude through simulation that when the payoff parameter is at the middle level, its cooperator proportion will be suppressed, and we deduce that the proportion of cooperators and defectors, as well as the payoff, play an important role.