钴掺杂MoSe2共生长中氢气的作用分析及磁电特性研究

采用原位共生长化学气相沉积法,以Co3O4、MoO3、Se粉末为前驱物,710℃下在SiO2衬底上生长掺钴MoSe2纳米薄片,分析讨论氢气含量对其生长及调节机理的影响.表面形貌分析表明,氢气的引入促进了成核所需的氧硒金属化合物以及横向生长中需要的CoMoSe化合物分子的生成;AFM(Atomic Force Microscope)结果表明氢气有利于生长单层二维超薄掺钴MoSe2.随着Co3O4前驱物用量的增加,样品的拉曼和PL(Photoluminescence)谱图分别表现出红移和蓝移现象,带隙实现从1.52—1.57 eV的调制.XPS(X-ray photoelectron spectroscopy)结果分析得到Co的元素组分比为4.4%.通过SQUID-VSM(Superconducting QUantum Interference Device)和器件电学测试分析了样品的磁电特性,结果表明Co掺入后MoSe2由抗磁性变为软磁性;背栅FETs器件的阈值电压比纯MoSe2向正向偏移5 V且关态电流更低;为超薄二维材料磁电特性研究及应用拓展提供了基础探索.     

基于连续量子级联激光器的1103.4cm–1处NH3混叠吸收光谱特性研究

由于NH3在大气气溶胶化学中具有重要作用,所以快速和精确反演NH3浓度对环境问题非常重要.本文以9.05μm的室温连续量子级联激光器(quantum cascade laser,QCL)作为光源,采用波长扫描直接吸收可调谐二极管激光吸收光谱(tunable diode laser absorption spectroscopy,TDLAS)技术,研究了QCL在1103.4 cm–1的光谱特性,获得了激光器控制的温度电流与波长的关系.设计了QCL二级温控的低压实验平台,测量氨气在1103.4 cm–1处的6条混叠吸收线,在降低压强的情况下谱线展宽变小,使混叠光谱分离,由此计算各条吸收线的线强,进一步对测量不确定度进行分析.针对混叠严重的光谱提出了低压分离单光谱精确反演气体浓度的方法,并进行了实验验证.通过与HITRAN数据库进行结果对比,得出氨气在1103.4 cm–1的实验测量线强值与数据库偏差为2.71%-4.71%,实验测量线强值的不确定度在2.42%-8.92%,极低压条件下反演浓度与实际值的偏差在1%-3%.     

Luminescent Thin Films Enabled by CsPbX3 (X=Cl,Br, I) Precursor Solution

Inorganic cesium lead halide perovskite nanocrystals are candidates for lighting and display materials due to their outstanding optoelectronic properties. However, the dissolution issue of perovskite nanocrystals in polar solvents remains a challenge for practical applications. Herein, we present a newly designed one-step spin-coating strategy to prepare a novel multicolor-tunable CsPbX₃ (X=Cl, Br, I) nanocrystal film, where the CsPbX₃ precursor solution was formed by dissolving PbO, Cs₂CO₃, and CH₃NH₃X into the ionic liquid n-butylammonium butyrate. The as-designed CsPbX₃ nanocrystal films show high color purity with a narrow emission width. Also, the blue CsPb(Cl/Br)₃ film demonstrates an absolute photoluminescence quantum yields (PLQY) of 15.6 %, which is higher than 11.7 % of green CsPbBr₃ and 8.3 % of red CsPb(Br/I)₃ film. This study develops an effective approach to preparing CsPbX₃ nanocrystal thin films, opening a new avenue to design perovskite nanocrystals-based devices for lighting and display applications.     

基于无机纳米材料的抗菌抗病毒功能涂层和薄膜

COVID-19在全球的大流行对人类的健康生活和社会的正常运行都造成了严重的危害. 阻断致病微生物通过受污染表面与人类间接接触传播, 或者避免与其直接接触是保护我们免受伤害的主要方法. 目前的解决措施包括设计开发抗菌抗病毒表面涂层和研发由自清洁薄膜或织物制成的个人防护设备. 综述了近年来几种研究广泛的金属、金属氧化物、金属有机框架材料等用于抗菌抗病毒涂层或薄膜的工作, 对其作用机制和微生物灭活效果进行了总结讨论, 并且评估了其本身的毒性以及实际应用的局限性, 最后就抗菌抗病毒涂层和薄膜开发的挑战和新兴研究方向提出了未来展望.     

Determination of cobalt ion based on polyethyleneimine modified silver nanoclustersEI北大核心CSCD

PolyethyleneiminePEImodified silver nanoclustersAg NCswere synthesized through chemical reduction method by using PEI as stabilizerAgNO3 as silve source and ascorbic acid as reducing agentand it was applied to the detection of cobalt ions. It was found that the fluorescence of the silver nanoclusters was quenched by Co2+ for the aggregation of PEI-Ag NCs caused by the coordination between cobalt ion and amino group on polyethyleneimine. Under the optimized experimental conditionsthe fluorescence quenching degree of PEI-Ag NCs was piecewise linear with the concentration of cobalt ion in the range of 8.30×10-7-4.17×10-4 mol/L and the detection limit was 0.41 μµmol/L. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

On the metabolites produced by Colletotrichum gloeosporioides a fungus proposed for the Ambrosia artemisiifolia biocontrol; spectroscopic data and absolute configuration assignment of colletochlorin A

Ambrosia artemisiifolia L. is responsible for serious allergies induced on humans. Different approaches for its control were proposed during the COST Action FA1203 “Sustainable management of Ambrosia artemisiifolia in Europe” (SMARTER). Fungal secondary metabolites often show potential herbicidal activity. Three phytotoxins were purified from the fungal culture filtrates of Colletotrichum gloeosporioides, isolated from infected leaves of A. artemisiifolia. They were identified by spectroscopic and chemical methods as colletochlorin A, orcinol and tyrosol (1, 2 and 3). The absolute configuration 6’R to colletochlorin A was assigned for the first time applying the advanced Mosher’s method. When assayed by leaf-puncture on A. artemisiifolia only 1 caused the appearance of large necrosis. The same symptoms were also induced by 1 on ambrosia plantlets associated with plant wilting. On Lemna minor, colletochlorin A caused a clear fronds browning, with a total reduction in chlorophyll content.     

Smarandache函数在两数列上的下界估计

设S(n)是Smarandache函数,其中n是一正整数.讨论Smarandache函数S(n)在数列F((2k),1)=F(n,1)=n2n+1(n=2k)与数列G(2n,1)=(2n)2n+1上的下界估计.基于初等方法证明了:当偶数n≥6时,有S(F((2k),1))=S(F(n,1))≥6×2n+1;当n≥4时,有S(G(2n,1))≥6×2n+1.     

Nitrogen Doping and Carbon Coating Affects Substrate Selectivity of TiO2 Photocatalytic Organic Pollutant Degradation

A series of carbon-coated, nitrogen-doped titanium dioxide photocatalysts was produced and characterized. N-doped TiO₂ powder samples were prepared using a sol-gel method and subsequently used for making doped-TiO₂ thin films on glass substrates. Carbon layers were coated on the films by a thermal decomposition method using catechol. Diffuse reflectance spectra and Mott-Schottky analyses of the samples proved that nitrogen doping and carbon coating can slightly lower the band gap of TiO₂, broaden its absorption to visible light and enhance its n-type character. According to photocatalytic tests against model contaminants, carbon-coated nitrogen-doped TiO₂ films have better performance than simple TiO₂ on the degradation of Rhodamine B dye molecules, but are poorly effective for degrading 4-chlorophenol molecules. Several possible explanations are proposed for this result, supported by scavenging experiments. This reveals the importance of a broad substrate scope when assessing new photocatalytic materials for water treatment, something which is often overlooked in many literature studies.     

Study of nucleon-nucleon and alphanucleon elastic scattering by the Manning-Rosen potential

Although often used in molecular dynamics, in this work the Manning–Rosen potential is parameterized to compute the scattering phase shifts for the nucleon–nucleon and the alpha-nucleon systems by exploiting the standard phase function method. We obtain excellent agreement in phase shifts with the more sophisticated calculations up to partial waves ${\ell }=2.$