排序方式: 共有23条查询结果,搜索用时 15 毫秒
1.
Zhang Kailun Wu Hongjuan Wang Tian Yao Meng Xie Jixing Jiao Yunhong 《Journal of Thermal Analysis and Calorimetry》2021,145(6):3067-3075
Journal of Thermal Analysis and Calorimetry - A phosphazene-based flame retardant (PBFA) was synthesized by hexachlorocyclotriphosphazene and N-aminoethylpiperazine. To improve the flame retardancy... 相似文献
2.
Han Wang Lifeng Lin Qian Sun Qingqiang Lin Xiaofan Xiong Kailun Wu 《International journal of environmental analytical chemistry》2013,93(12):1173-1182
An ion-pair high-performance liquid chromatography with ultraviolet detection method for the determination of cyromazine, melamine and its biodegradation products (ammeline, ammelide, cyanuric acid and biuret) was developed. C18 column was utilised to separate the six analytes with a mobile phase consisting of perchloric acid-ammonia solution and acetonitrile, under gradient elution and variable flow rate. The detection wavelengths were 205 nm for cyanuric acid and biuret and 222 nm for cyromazine, melamine, ammeline and ammelide. For analysis of sediment samples, the extraction solution containing acetonitrile, ammonia and water (80:10:10 by volume) was used to extract the analytes from sediment matrix. Using the extraction method for the spiked sediment sample, high linearity of matrix-matched standard curve could be obtained for the six analytes. The method detection limit was 0.1 μg g?1 for melamine and cyromazine, 0.2 μg g?1 for ammeline and ammelide, 1.2 μg g?1 for cyanuric acid and 1.0 μg g?1 for biuret in sediment matrix. The recoveries of these compounds were 70.1–98.3% and the relative standard deviations were 0.5–4.4%. Finally, the proposed method was successfully applied to the analysis of the sediment sample near the wastewater outlet of a melamine-producing factory. 相似文献
3.
Charge, orbital, and spin ordering of multiferroic BiMn(2)O(5) are investigated by the full-potential linearized augmented plane-wave (FPLAPW) method as implemented in the WIEN2K package. Both the generalized gradient approximation (GGA) as well as GGA plus the one-site Coulomb interaction (GGA+U) methods are considered for the exchange-correlation energy functional. The obtained results show that BiMn(2)O(5) is found stable in ferrimagnetic state with band gap about 1.23 eV. The results suggest that BiMn(2)O(5) contains two kinds of manganese: the ionicity of Mn1 (Mn(4+)) is +3.6 with magnetic moment of 2.40 μ(B) and the ionicity of Mn2 (Mn(3+)) is +3.4 with magnetic moment of 3.22 μ(B). While charge disproportion between Mn1 and Mn2 is small, the difference between e(g) minority occupancies of Mn(3+) and Mn(4+) cations is large. Both these two properties give direct evidence of charge ordering. The analysis of the Born effective charge reveals that the partial ferroelectric polarization (P(ele)) originates from the charge ordering, which is in agreement with a recent work by Brink and Khomskii [J. Phys.: Condens. Matter, 2008, 20, 434217]. 相似文献
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针对圆柱壳结构的减振问题,本文提出一种局域共振型圆柱壳类声子晶体结构,通过在圆柱壳圆周方向布置弹簧振子实现.该声子晶体的能带结构研究结果表明,该结构能够形成两条低频带隙,一条带隙的起始频率低至650 Hz,带宽为330 Hz,另一条带隙具有更低的频率范围,为0~371 Hz,带隙的形成是由于圆柱壳和弹簧振子振动的耦合.进一步分析了声子晶体的圆柱壳质量与弹簧振子的质量比、弹簧振子的刚度和元胞宽度对带隙的影响.对有限周期圆柱壳结构的传输特性分析,验证了局域共振型圆柱壳声子晶体在带隙范围内的抑制振动的能力.研究结果为圆柱壳结构的减振问题提供了理论参考. 相似文献
5.
The next-nearest-neighbor hopping interactions of ρ-electrons in quasi-onedimensional organic polymer ferromagnet are considered by Peierls-Hubbard model, and a set of self-consistent equations are established to optimize the system. The competition between the SDW and CDW states, which is determined by the interplay between the electron-electron correlation and the next-nearest-neighbor hopping interaction, is studied. At the CDW state,the SDW along the main chain will be tuned by the CDW. Consequently the ferromagnetic state, in which all the spins of the unpaired electrons at side freeradicals are arranged parallelly,will be no longer a stable ground state of the system. 相似文献
6.
Xiaolin Zhang Pengwei Gong Fangqi Liu Kailun Yao Jian Wu Sicong Zhu 《Frontiers of Physics》2022,17(5):53510
Due to the unique electronic structure of half-metals, characterized by the conductivity of majority-spin and the band gap of minority-spin, these materials have emerged as suitable alternatives for the design of efficient giant magnetoresistive (GMR) devices. Based on the first-principles calculations, an excellent GMR device has been designed by using two-dimensional (2D) half-metal Mn2NO2. The results show that Mn2NO2 has sandwiched between the Au/nMn2NO2 (n = 1, 2, 3)/Au heterojunction and maintains its half-metallic properties. Due to the half-metallic characteristics of Mn2NO2, the total current of the monolayer device can reach up to 1500 nA in the ferromagnetic state. At low voltage, the maximum GMR is observed to be 1.15 × 1031 %. Further, by increasing the number of layers, the ultra-high GMR at low voltage is still maintained. The developed device is a spintronic device exhibiting the highest magnetoresistive ratio reported theoretically so far. Simultaneously, a significant negative differential resistance (NDR) effect is also observed in the heterojunction. Owing to its excellent half-metallic properties and 2D structure, Mn2NO2 is an ideal energy-saving GMR material. 相似文献
7.
Weifeng Liu Kailun Zhang Hong Fan Wen‐Jun Wang Bo‐Geng Li Shiping Zhu 《Journal of polymer science. Part A, Polymer chemistry》2013,51(2):405-414
Living copolymerization of ethylene and 1‐octene was carried out at room temperature using the fluorinated FI‐Ti catalyst system, bis[N‐(3‐methylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] TiCl2/dried methylaluminoxane, with various 1‐octene concentrations. The comonomer incorporation up to 32.7 mol % was achieved at the 1‐octene feeding ratio of 0.953. The living feature still retained at such a high comonomer level. The copolymer composition drifting was minor in this living copolymerization system despite of a batch process. It was found that the polymerization heterogeneity had a severe effect on the copolymerization kinetics, with the apparent reactivity ratios in slurry significantly different from those in solution. The reactivity ratios were nearly independent of polymerization temperature in the range of 0–35 °C. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
8.
Huijun Liu Kailun He Jing Zhou 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):933-936
AbstractStrecker reaction of various substituted aromatic aldehydes, heteroaromatic aldehydes, aliphatic aldehydes and α,β-unsaturated aldehydes with trimethylsilyl cyanide (TMSCN) was realized in the presence of 5?mol % of MgI2 etherate in a mild, efficient and highly chemoselective manner under solvent-free conditions. 相似文献
9.
Nengju Mi Xiangwei Meng Haokun Pan Kailun He 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1176-1179
AbstractThree-component Mukaiyama–Mannich reaction of aldehydes, amines, and silyl enol diazoacetoacetate was efficiently carried out to afford δ-amino substituted-α-diazoacetoacetate derivatives catalyzed by 5?mol% of MgI2 etherate (MgI2?(OEt2)n) under mild and neutral reaction conditions in good to excellent yields. 相似文献
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