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1. chinaXiv:202102.00016 [pdf]

三维晶体中的演生粒子百科

余智明; 张泽英; 刘贵斌; 吴维康; 李小平; 张闰午; 杨声远; 姚裕贵
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems. Novel particles, emerged as excitations around exotic band degeneracy points, continue to be reported in real materials and artificially engineered systems, but so far, we do not have a complete picture on all possible types of particles that can be achieved. Here, via systematic symmetry analysis and modeling, we accomplish a complete list of all possible particles in time reversal-invariant systems. This includes both spinful particles such as electron quasiparticles in solids, and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks. We establish detailed correspondence between the particle, the symmetry condition, the effective model, and the topological character. This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.

submitted time 2021-02-02 Hits375Downloads171 Comment 0

2. chinaXiv:201709.00083 [pdf]

丙酮–乙醇–丁醇混合物向长链酮醇的高选择性转化

申春; 朱强强; 王杰; 苏海佳; 谭天伟
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

近年来随着石油资源的枯竭和环保意识的增强,如何实现以具有环境友好、可再生等诸多优势的生物质资源替代传统化石能源制备燃料和化学品,已经成为了学术界和工业界共同关注的焦点。生物质向生物基化学品和生物基燃料的催化转化过程中,催化材料的水环境下的稳定性一直是该领域的难点。例如丙酮–丁醇–乙醇发酵液(ABE)向生物基液体燃料的催化转化过程中,目前报到的最优的非均相催化材料为金属纳米颗粒负载的镁铝水滑石(M-HT),但是基于水滑石材料特有的结构记忆效应,该催化材料要求初始反应物中水含量不得超过0.5wt%,急剧增加了上游分离工艺的成本和操作难度。为了解决此共性问题,在我们的工作中,以丙酮–丁醇–乙醇发酵液向生物基液体燃料的催化转化为目标体系,设计了新型催化材料——氧化镁–二氧化硅混合氧化物负载金属纳米颗粒(M-MgO–SiO2),并系统地考察了金属元素种类(Ni,Cu,Fe,Zn和Co)和负载量以及反应温度对其催化活性的影响。研究结果表明,镍负载量为10 wt%的Ni-MgO–SiO2催化剂具有最优活性:在240 ℃下反应20 h后C5–C15的醇酮收率为81.5%。和预期一致,相比于水滑石系催化剂,该催化剂表现出了良好的耐水性:初始反应物中水含量为3 wt%时,转化率和产物分布完全不受影响。XRD和29Si MAS NMR结果显示形成的硅酸镁结构对于提高催化材料的耐水性发挥了重要作用。通过考察10 wt% Ni-SiO2,10 wt% Ni-MgO以及10 wt% Ni-MgO–SiO2的催化活性,揭示了氧化镁和氧化硅的作用。

submitted time 2017-09-20 Hits1257Downloads490 Comment 0

3. chinaXiv:201703.01168 [pdf]

通过8-羟基喹啉改性提高环氧富锌涂层的保护性能

韩桃庆; 左禹; 赵旭辉; 唐聿明
Subjects: Materials Science >> Materials Science (General)

利用电化学阻抗、红外光谱、电镜等方法研究了8-羟基喹啉改善环氧富锌涂层性能的作用。在环氧富锌涂层中用5%的8-羟基喹啉替代锌粉后,锌粉的电荷转移电阻Rct增加,且锌粉/溶液界面双电子层电容Qdl降低,锌粉的反应过程被抑制,因此,虽然锌粉的含量降低了,但是锌粉的阴极保护作用时间却明显延长。另一方面,8-羟基喹啉改性后的环氧富锌涂层的电阻Rc升高,电容Qc降低,涂层孔隙率P降低,涂层的屏蔽性增强。上述两方面的作用,可以显著改善涂层的保护性能,延长涂层寿命。

submitted time 2017-03-31 From cooperative journals:《腐蚀科学与防护技术》 Hits30550Downloads796 Comment 0

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