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101.
Yandong Wu Wei Chen Yimin Jiang Yanzhi Xu Bo Zhou Leitao Xu Chao Xie Ming Yang Mengyi Qiu Dongdong Wang Qie Liu Prof. Qinghua Liu Prof. Shuangyin Wang Prof. Yuqin Zou 《Angewandte Chemie (International ed. in English)》2023,62(30):e202305491
Synthesis of cyclohexanone oxime via the cyclohexanone-hydroxylamine process is widespread in the caprolactam industry, which is an upstream industry for nylon-6 production. However, there are two shortcomings in this process, harsh reaction conditions and the potential danger posed by explosive hydroxylamine. In this study, we presented a direct electrosynthesis of cyclohexanone oxime using nitrogen oxides and cyclohexanone, which eliminated the usage of hydroxylamine and demonstrated a green production of caprolactam. With the Fe electrocatalysts, a production rate of 55.9 g h−1 gcat−1 can be achieved in a flow cell with almost 100 % yield of cyclohexanone oxime. The high efficiency was attributed to their ability of accumulating adsorbed hydroxylamine and cyclohexanone. This study provides a theoretical basis for electrocatalyst design for C−N coupling reactions and illuminates the tantalizing possibility to upgrade the caprolactam industry towards safety and sustainability. 相似文献
102.
从分子结构设计出发,合成了一系列新型刚性、高自由体积的聚酰亚胺炭膜前驱体,并制备了炭膜.采用热重分析(TGA)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)和高分辨透射电子显微镜(HRTEM)研究了不同聚酰亚胺前驱体的热分解特性及在热解炭化过程中化学结构、微结构的变化规律;测试了所制备炭膜的气体分离性能.结果表明,前驱体的自由体积分数显著影响炭膜的气体分离性能;聚合物结构越具刚性,自由体积越大,所得炭膜结构越疏松,极微孔道尺寸越大,越有利于气体分子在炭膜极微孔道中的渗透、扩散与传输.其中,刚性大体积基团芴基、酚酞cardo基团和六氟异丙基的引入能有效破坏分子链间的堆积,提高聚合物的自由体积,所形成炭膜的结构较疏松,均表现出优异的气体渗透性和分离选择性,超越了Robeson上限,解决了传统炭膜气体渗透性能低的问题.特别是采用羟基官能化聚酰亚胺前驱体制备的炭膜在保持较高气体分离选择性的同时,CO_2气体的渗透性高达24770 Barrer(1 Barrer≈7.5×10-18m2·s-1·Pa-1),可实现对CO_2的有效分离和捕集,展现出良好的商业化应用前景. 相似文献
103.
104.
由配合物作前驱体(简称:前驱体配合物)来制备子代配合物是配合物定向合成的有效方法之一。与一般的有机配体相比,前驱体配合物拥有特定的、相对稳定的结构骨架,并且在一定的反应条件下能够与有机配体之间进行定向自组装,形成具有预期结构的配合物,同时还能把自己的结构特征"遗传"给子代配合物。本论文选择一个一维长链铜配合物{[Cu(bbbm)(CH_3COO)_2]·(CH_3OH)_2}n(Q)[bbbm=1,1’-(1,4-丁基)-二-(1-H-苯并咪唑)]作为前驱体配合物,通过小分子配体的取代、加成反应获得了一个新的子代配合物[Cu(bbbm)(N_3)_2(Py)]n(1)。单晶衍射分析结果显示子代配合物(1)"遗传"了前驱体配合物(Q)的一维长链结构。我们还进一步研究了反应前后配合物的配位方式、bbbm配体构象变化及其催化性能变化。 相似文献
105.
《Angewandte Chemie (International ed. in English)》2017,56(20):5620-5624
The metastable binary compound hp‐CuBi was obtained from the direct chemical reaction between copper and bismuth at a pressure of 5 GPa and a temperature of 720 K. The atomic arrangement comprises slabs of puckered Cu layers sandwiched between Bi planes. The QTAIM charges calculated for compounds of bismuth with transition metals reveal negligible charge transfer for hp‐CuBi. Analysis of the chemical bonding with position‐space techniques discloses multicenter interactions within the Bi‐Cu‐Bi slabs and lone‐pair interactions of the van der Waals type between these entities. hp‐CuBi exhibits metal‐type electrical conductivity with superconductivity below Tc=1.3 K. 相似文献
106.
The main object of this paper is to analyze the recent results obtained on the Neumann realization of the Schrödinger operator in the case of dimension 3 by Lu and Pan. After presenting a short treatment of their spectral analysis of keymodels, we show briefly how to implement the techniques of Helffer-Morame in order to give some localization of the ground state. This leaves open the question of the localization by curvature effect which was solved in the case of dimension 2 in our previous work and will be analysed in the case of dimension 3 in a future paper. 相似文献
107.
REN Zhi'an CHE Guangcan JIA Shunlian CHEN Hong NI Yongming ZHAO Zhongxian 《中国科学A辑(英文版)》2001,44(9):1205-1208
The effect of Mg and C contents on TC in MgCN3, and structure and superconductivity of MgCNi3-x Co x were studied. It is found that the excess of Mg and C in initial material mixture is favorable to improvement inT c and helps to obtain single-phase samples. For preparing MgCNi3 superconductor, the optimum composition of starting materials is MgC1.45Ni3 with excess of Mg (20 wt.%) of the stoichiometric composition. In gCNi3-x Co x system, a continuous solid solution is formed, lattice parameter decreases slightly andT c decreases obviously with increasingx. A suppression of superconductivity is observed due to the substitution of Co (Mn) for Ni. The suppression effect is smaller for the substitution of Co than that of Mn 相似文献
108.
Tohru Ozawa 《Mathematische Nachrichten》2013,286(17-18):1792-1796
We study an initial boundary value problem for a time‐dependent 3D Ginzburg‐Landau model of superconductivity with partial viscous terms. We prove the global existence of strong solutions. 相似文献
109.
In this paper the numerical approximations of the Ginzburg- Landau model for a superconducting hollow spheres are constructed using a gauge invariant discretization on spherical centroidal Voronoi tessellations. A reduced model equation is used on the surface of the sphere which is valid in the thin spherical shell limit. We present the numerical algorithms and their theoretical convergence as well as interesting numerical results on the vortex configurations. Properties of the spherical centroidal Voronoi tessellations are also utilized to provide a high resolution scheme for computing the supercurrent and the induced magnetic field.
110.
K.-U. Neumann F. Kusmartsev H.-J. Lauter O. Schärpf T.J. Smith K.R.A. Ziebeck 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(1):5-9
A polarized neutron scattering investigation of the flux line lattice in the type-II superconductor niobium is reported. A
modulation of the nuclear lattice has been detected, and the magnitude of the first Fourier component of the lattice distortion
established relative to the magnitude of the magnetic scattering. This constitutes the first experimental observation of lattice
distortions due to the presence of magnetic flux lines within the bulk of a type-II superconductor. Using a simple microscopic
model the lattice distortion in niobium is estimated. A new mechanism is suggested for the coupling of the flux line lattice
to the crystallographic lattice. The experimental technique opens up the possibility of investigating the microscopic mechanism
of flux line - nuclear lattice interactions, in particular the pinning of flux lines within the bulk of a type-II superconductor.
Received: 8 August 1997 / Accepted: 16 October 1997 相似文献