Soluble polyimide as liquid crystal perpendicular alignment layer

Journal of Materials Science - Three polyimides (PIs) were prepared from a diamine containing biphenyl ester group as a side chain and a corresponding dianhydride chosen from...     

Approximation Optimal Vibration Control with Applications to Jacket Offshore Platforms with Nonlinear Dynamic Characteristics

International Journal of Control, Automation and Systems - The vibration control problem of offshore jacket platforms is studied. The model of offshore platforms with nonlinear interactions of the...     

Copper(II) complexes with acetone picolinoyl hydrazones: Crystallographic insight into metalloligand formation

Complexes with free donor atoms, termed metalloligands, are important building blocks in the stepwise approach towards mixed-metal organic frameworks. In this work, the possibility of a metalloligand formation from nicotinic or isonicotinic acid hydrazides and copper(II) centers, is assessed. Syntheses, X-ray crystal structures and spectroscopic properties of two new copper(II) compounds with acetone 3- and 4-picolinoyl hydrazones are reported. The structural studies reveal the formation of a mononuclear cationic metalloligand in [Cu(Hisn)₂](NO₃)₂ (1) with a zwitterionic acetone isonicotinoyl hydrazone (Hisn), as well as a neutral, layered (2D) coordination polymer, [Cu(μ-nic)₂]_n (2), with a deprotonated acetone nicotinoyl hydrazone (Hnic). Heteroatom position in the hydrazide precursor and copper salt acidity influence the formation of pure products.     

Yolk–shell structured iron carbide/N-doped carbon composite as highly efficient and stable oxygen reduction reaction electrocatalyst

We report a simple route to synthesize iron carbide/carbon yolk–shell composite via a facile two-step process including polymerization of pyrrole using Fe₃O₄ as a sacrificial template to form a Fe₃O₄/polypyrrole composite, followed by annealing at high temperature in N₂ atmosphere. The yolk–shell composite, with iron carbide (Fe_2.5C) embedded in nitrogen-doped carbon layers, shows impressively high catalytic activity and stability for oxygen reduction reaction in alkaline solution. Both the pyridinic-N and graphic-N in the shell of Fe₃O₄–PPy-700, together with the Fe_2.5C confined in carbon layers are believed to be the active sites for the ORR.     

醛,2-异丁腈与硝基甲烷的多组分passerini反应

Passerini反应是一类重要的多组分反应,它可以快速的合成许多结构复杂的药物中间体,文章以苯甲醛,2-异丁腈和硝基甲烷为原料,氯化锌为催化剂,在微波作用下,发展新的多组分Passerini反应。     

（100）应变对正交相Ca2P0.25Si0.75能带结构及光学性质的影响

采用第一性原理赝势平面波方法对（100）应变下正交相Ca2P0.25Si0.75的能带结构及光学性质进行模拟计算.计算结果表明：（100）面在晶格发生100％～116％张应变时,带隙随着应变增加而减小;在晶格发生96％～100％压应变时,带隙随着张应变的增加而增加;88％～96％压应变时,带隙随着压应变的增加而减小;当压应变大于88％后转变为间接带半导体.当施加应变后光学性质发生显著的变化：随着压应变的增加静态介电常数、折射率逐渐减小,张应变则反之.施加压应变反射向低能方向偏移,施加张应变反射向高能方向偏移,但施加应变对反射区域的影响不显著.施压应变吸收谱、光电导率的变化与介电函数和折射率相反.综上所述,应变可以改变Ca2P0.25Si0.75的电子结构和光学常数,是调节Ca2P0.25Si0.75光电传输性能的有效手段.     

木质素热解中CO和CO2形成机理的理论研究

采用密度泛函理论方法(B3LYP)对含苯基的各种木质素模型化合物的脱羰基反应和脱羧基反应进行了理论研究。设计了8种模型化合物 R1-R8的8条脱羰基反应路径(1)-(8)和8种模型化合物 R9-R16的8条脱羧基反应路径(9)-(16)。计算了不同温度下各热解反应途径的标准热力学和动力学参数。计算结果表明,反应路径(1)-(4)的脱羰基反应能垒明显高于反应路径(5)-(8),CO 更可能通过苯基(对羟苯基、愈创木基和紫丁香基)乙醛的脱羰基反应而形成;反应路径(9)-(12)的脱羧基反应能垒低于反应路径(13)-(16),CO2的形成更可能通过苯基(对羟苯基、愈创木基和紫丁香基)甲酸的脱羧基反应而完成。     

钾离子电池炭负极材料的研究进展

随着社会对大规模储能系统需求的不断攀升，迫切需要开发可持续、低成本的新型电池技术。鉴于钾离子储量丰富、成本可控，钾离子电池近年来受到越来越多关注。不仅介绍了目前研究较多的几种炭基材料及其储钾性能，还尝试总结了炭基材料可能的储钾机理，展望了钾离子电池用炭基电极材料面临的问题及未来发展方向。     

Evanescent-field photonic microcells and their applications in sensing

This paper reports the results of our recent studies on evanescent-field photonic microcells (PMCs) made by post-processing commercial micro-structured optical fibers and by encapsulating tapered micro/nano fibers within glass capillaries. The PMCs have a wavelength/sub-wavelength scale wave-guiding core housed within a miniature hollow compartment. The housing isolates the waveguide core from external contamination and provides a robust platform for efficient evanescent field interaction with the materials filling the compartment. The techniques for fabrication are described and the applications of the PMCs for sensing temperature, gas pressure, refractive index and mechanical acceleration are discussed.     

Comparison between microwave and thermal curing of a polyimide adhesive end-caped with phenylethynyl groups

Microwave energy was investigated to cure phenylethynyl-end-capped polyimide adhesive using an industrial microwave oven at a frequency of 2.45 GHz and the adhesive properties, thermal performance and curing mechanism for bonding stainless steel were evaluated. The results are compared with those of thermal cured samples. It was demonstrated that while the lap shear strength properties and thermal performance of microwave cured samples were almost as good as those cured via a thermal process, the microwave curing process resulted in a significant reduction in the process cycle time and power consumption. The Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis of the cured resin structures suggested that there was no obvious difference in the chemical reactions taking place during the microwave and the thermal cure processes.