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31.
纳米结构Au/Fe_2O_3的制备、表征及催化氧化性能 总被引:1,自引:0,他引:1
分别以纳米和块状氧化铁为载体,通过沉积沉淀法制备了Au/Nano-Fe2O3和Au/Bulk-Fe2O3,并对其进行了表征和催化氧化性能测试。结果表明:对于Au/Nano-Fe2O3,5 nm Au颗粒被尺寸相当的Nano-Fe2O3所包覆,形成新颖的类似核壳结构;对于Au/Bulk-Fe2O3,3 nm Au颗粒高度分散于Bulk-Fe2O3的表面。在1-苯乙醇的氧化反应中,Au/Nano-Fe2O3显示出比Au/Bulk-Fe2O3更好的催化活性。活性的增强主要与小尺寸的Nano-Fe2O3以及Au和Nano-Fe2O3更大的接触界面有关。相比于广泛受到重视的Au的尺寸效应来说,对于Au/Nano-Fe2O3而言,Fe2O3尺寸的影响更大。 相似文献
32.
A three-coordinate Ag(I) complex, [Ag(Mepzpy)(PAr3)]BF4·H2O(1, Mepzpy = 3-methyl-1-(2-pyridyl)pyrazole, PAr3 = tri(o-tolyl)phosphine), was synthesized from the reaction of Ag(CH3CN)4BF4, PAr3 and Mepzpy in CH3 CN at room temperature. The compound was characterized by UV-vis, NMR and X-ray single-crystal structure analysis. It crystallizes in triclinic space group P1 with a = 10.2251(5), b = 10.6014(5), c = 15.7012(5) , α = 92.963(3), β = 92.641(3), γ = 114.647(4)o, V = 1540.6(1) 3, Z = 2, Mr = 676.24, Dc = 1.458 g/cm3, F(000) = 688, μ = 6.187 mm-1, GOOF = 1.038, the final R = 0.0530 and w R = 0.1493 for 6371 observed reflections with I 2σ(I). Compound 1 is ionic. It is composed of a BF4- anion and a [Ag(Mepzpy)(PAr3)]+ cation. The Ag(I) ion adopts a distorted trigonal pyramidal coordination geometry defined by two nitrogen atoms and a phosphorous atom. The complex emits blue luminescence with maximum peaks at 470 nm in solid state at room temperature. 相似文献
33.
Mengjiao Huang Dr. Juanjuan Yang Teng Wang Dr. Jia Song Jinglu Xia Dr. Lingling Wu Dr. Wei Wang Dr. Qiaoyi Wu Prof. Zhi Zhu Dr. Yanling Song Prof. Chaoyong Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4830-4835
Immunotherapy has revolutionized cancer treatment, but its efficacy is severely hindered by the lack of effective predictors. Herein, we developed a homogeneous, low-volume, efficient, and sensitive exosomal programmed death-ligand 1 (PD-L1, a type of transmembrane protein) quantitation method for cancer diagnosis and immunotherapy response prediction (HOLMES-ExoPD-L1). The method combines a newly evolved aptamer that efficiently binds to PD-L1 with less hindrance by antigen glycosylation than antibody, and homogeneous thermophoresis with a rapid binding kinetic. As a result, HOLMES-ExoPD-L1 is higher in sensitivity, more rapid in reaction time, and easier to operate than existing enzyme-linked immunosorbent assay (ELISA)-based methods. As a consequence of an outstanding improvement of sensitivity, the level of circulating exosomal PD-L1 detected by HOLMES-ExoPD-L1 can effectively distinguish cancer patients from healthy volunteers, and for the first time was found to correlate positively with the metastasis of adenocarcinoma. Overall, HOLMES-ExoPD-L1 brings a fresh approach to exosomal PD-L1 quantitation, offering unprecedented potential for early cancer diagnosis and immunotherapy response prediction. 相似文献
34.
对小学科学课程标准与五年制专科小学教育专业“科学·化学”教学大纲中对化学知识内容的要求,以及小学《科学》和高等专科学校《科学·化学》教材中涉及的化学知识内容进行了对比。同时就五年制专科层次小学教育专业化学课程存在的问题进行了讨论,并提出了选择合适的课程教学内容、加强化学实验和化学教材建设、建立理论课程和实验教学新体系模块等建议。 相似文献
35.
36.
天然气管道泄漏可调谐二极管激光遥感探测的研究 总被引:2,自引:0,他引:2
天然气管道泄漏不仅造成经济损失而且是危险之源。传统的天然气管道泄漏检测技术效率低、速度慢,难以满足实际应用的需要。近年来以近红外二极管激光吸收光谱为基础的光学传感器由于具有灵敏度高、体积小、重量轻和无需维护等优点而得到了广泛的应用。文章以可调谐二极管激光吸收光谱和谐波探测技术为基础进行天然气管道泄漏遥感探测技术的研究,采用二次谐波与一次谐波信号的比值作为系统浓度标定,结果显示浓度与比值之间具有较好的一致性。文章还就不同地形散射体对探测结果的影响进行了测量和分析,实验结果表明二次谐波与一次谐波信号比值标定技术对便携式二极管激光光学测量能够很好的满足实际应用的需要。 相似文献
37.
ABSTRACTThe stable configurations, electronic structures and catalytic activities of single-atom metal catalyst anchored silicon-doped graphene sheets (3Si-graphene-M, M?=?Ni and Pd) are investigated by using density functional theory calculations. Firstly, the adsorption stability and electronic property of different gas reactants (O2, CO, 2CO, CO/O2) on 3Si-graphene-M substrates are comparably analysed. It is found that the coadsorption of O2/CO or 2CO molecules is more stable than that of the isolated O2 or CO molecule. Meanwhile, the adsorbed species on 3Si-graphene-Ni sheet are more stable than those on the 3Si-graphene-Pd sheet. Secondly, the possible CO oxidation reactions on the 3Si-graphene-M are investigated through Eley–Rideal (ER), Langmuir–Hinshelwood (LH) and new termolecular Eley–Rideal (TER) mechanisms. Compared with the LH and TER mechanisms, the interaction between 2CO and O2 molecules (O2?+?CO → CO3, CO3?+?CO → 2CO2) through ER reactions (< 0.2?eV) are an energetically more favourable. These results provide important reference for understanding the catalytic mechanism for CO oxidation on graphene-based catalyst. 相似文献
38.
Teng Fang Jiazhan Xin Chenguang Fu Dongsheng Li Xinbing Zhao Claudia Felser Tiejun Zhu 《Annalen der Physik》2020,532(11):1900435
Lattice thermal conductivity can be reduced by introducing point defect, grain boundary, and nanoscale precipitates to scatter phonons of different wave-lengths, etc. Recently, the effect of electron–phonon (EP) interaction on phonon transport has attracted more and more attention, especially in heavily doped semiconductors. Here the effect of EP interaction in n-type P-doped single-crystal Si has been investigated. The lattice thermal conductivity decreases dramatically with increasing P doping. This reduction on lattice thermal conductivity cannot be explained solely considering point defect scattering. Further, the lattice thermal conductivity can be fitted well by introducing EP interaction into the modified Debye–Callaway model, which demonstrates that the EP interaction can play an important role in reducing lattice thermal conductivity of n-type P-doped single-crystal Si. 相似文献
39.
采用基于密度泛函理论的第一性原理赝势平面波方法,对稀土元素La,Y单掺杂和La和Y共掺杂GaN的晶格常数、电子结构及光学性质进行了计算与分析.计算结果表明:掺杂改变了GaN的能带结构,未掺杂和Y掺杂形成导带底和价带顶位于G点的直接带隙半导体,而La掺杂和La和Y共掺杂形成导带底位于G点,价带顶位于Q点的间接带隙半导体.可以通过掺杂元素来调制GaN的禁带宽度和带隙类型,掺杂均提高GaN在低能区的静态介电常数、反射率、折射率,使光子的跃迁强度增大,说明稀土元素La,Y掺杂可有效调制GaN的光电性质. 相似文献
40.
Teng Wang Chi Zhang LiangCai Xu JinHua Wang Shan Jiang ZengWei Zhu ZhaoSheng Wang JiaNan Chu JiaXin Feng LingLing Wang Wei Li Tao Hu XiaoSong Liu Gang Mu 《中国科学:物理学 力学 天文学(英文版)》2020,(2):124-129
Recently, 12442 system of Fe-based superconductors has attracted considerable attention owing to its unique double-Fe As-layer structure. A steep increase in the in-plane upper critical field with cooling has been observed near the superconducting transition temperature, Tc, in KCa2Fe4As4F2 single crystals. Herein, we report a high-field investigation on upper critical field of this material over a wide temperature range, and both out-of-plane(H∥c, Hc2c) and in-plane(H∥ab, Hc2ab ) directions have been measured.A sublinear temperature-dependent behavior is observed for the out-of-plane Hc2c , whereas strong convex curvature with cooling is observed for the in-plane Hc2ab . Such behaviors could not be described by the conventional Werthamer-Helfand-Hohenberg(WHH) model. The data analysis based on the WHH model by considering the spin aspects reveals a large Maki parameter α=9,indicating that the in-plane upper critical field is affected by a very strong Pauli paramagnetic effect. 相似文献