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From amides to urea derivatives or carbamates with chemospecific C–C bond cleavage at room temperature

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Organic Chemistry Frontiers 2022年第5期9卷 1354-1363页

作者： Cong Lv Dan Liu Tegshi Muschin Chaolumen Bai Agula Bao Yong-Sheng Bao College of Chemistry and Environmental Science Inner Mongolia Key Laboratory of Green catalysisInner Mongolia Normal UniversityHohhot010022China

Ureas and carbamates are common motifs in pharmaceuticals,agrochemicals,biologically active com-pounds and organocatalysis ***,we report a significant advancement in this area and present a general method for copper-catalyzed chemospecific C–C bond cleavage of amides to syn-thesize urea derivatives and carbamates at room temperature.

关键词： temperature cleavage bond

The application of C–H bond functionalization in the total syntheses of indole natural products

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Organic Chemistry Frontiers 2022年第4期9卷 1195-1210页

作者： Dong-Xing Tan Fu-She Han CAS Key Lab of High-Performance Synthetic Rubber and its Composite Materials Changchun Institute of Applied ChemistryChinese Academy of Sciences5625 Renmin StreetChangchunJilin 130022China

The direct functionalization of unactivated C–H bonds has been a rapidly growing field in organic chem-istry in recent years because of its indisputable advantages in bond forming reactions in terms of step and atom-... 详细信息

关键词： functionalization bonds bond

bond PARAMETER AND ELECTRONIC STRUCTURE OF Sc,Y,Ti,Zr AND Hf METALS

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中国有色金属学会会刊：英文版 1998年第3期8卷 18-22页

作者： Yingjun, Gao Zhenghua, Chen Peiyun, Huang Xiaping, Zhong Central South Univ of Technology Changsha China

１ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ，ｔｈｅＰａｕｌｉｎｇ’ｓｖａｌｅｎｃｅｂｏｎｄ（ＶＢ）ｔｈｅｏｒｙｈａｓｂｅｅｎｍａｄｅａｇｒｅａｔｐｒｏｇｒｅｓｉｎｄｅｓｉｇｎｉｎｇａｎｄｄｅｔｅｒｍｉｎｉｎ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ，ｔｈｅＰａｕｌｉｎｇ’ｓｖａｌｅｎｃｅｂｏｎｄ（ＶＢ）ｔｈｅｏｒｙｈａｓｂｅｅｎｍａｄｅａｇｒｅａｔｐｒｏｇｒｅｓｉｎｄｅｓｉｇｎｉｎｇａｎｄｄｅｔｅｒｍｉｎｉｎｇｔｈｅａｔｏｍｉｃｓｔａｔｅ，ａ...

关键词： Sc Y Ti Zr Hf metals one atom state method electronic structure bond parameter

Thermal-hydraulic modeling and analysis of spool valve with sloping U-shape notch by bond graph

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Journal of Central South University 2015年第11期22卷 4205-4212页

作者：娄磊吴万荣王兆强梁向京 College of Mechanical and Electrical Engineering Central South University State Key Laboratory of Fluid Power Transmission and Control (Zhejiang University)

To increase the efficiency and reliability of the thermodynamics analysis of the spool valve, the precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke and thermal-hydraulic bond graph based on the conservation of mass and energy were introduced. Subsequently, the connection rule for the bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing the spool valve, the lumped parameter for mathematical model of the system was given. At last, the reliability of the mathematical model of the flow area and the thermal-hydraulic system for the sloping U-shape notch orifice on the spool were demonstrated by the test. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.

关键词： thermodynamics hydraulic system spool valve bond g

The effect of carbon nanotubes and polypropylene fibers on bond of reinforcing bars in strain resilient cementitious composites

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Frontiers of Structural and Civil Engineering 2016年第2期10卷 214-223页

作者： Souzana P. TASTANI Maria S. KONSTA-GDOUTOS, Stavroula J. PANTAZOPOULOU Victor BALOPOULOS Department of Civil Engineering Democritus University oJ Thrace Vas. Sofias Street #12 Xanthi 67100 Greece

Stress transfer between reinforcing bars and concrete is engaged through rib translation relative to concrete, and comprises longitudinal bond stresses and radial pressure. The radial pressure is equilibrated by hoop tension undertaken by the concrete cover. Owing to concrete＇s poor tensile properties in terms of strength and deformability, the equilibrium is instantly released upon radial cracking of the cover along the anchorage with commensurate abrupt loss of the bond strength. Any improvement of the matrix tensile properties is expected to favorably affect bond in terms of strength, resilience to pullout slip, residual resistance and controlled *** aim of this paper is to investigate the local bond of steel bars developed in adverse tensile stress conditions in the concrete cover. In the tests, the matrix comprises a novel, strain resilient cementitious composite （SRCC） reinforced with polypropylene fibers （PP） with the synergistic action of carbon nano-tubes （CNT）. Local bond is developed over a short anchorage length occurring in the constant moment region of a four-point bending short beam. Parameters of investigation were the material structure （comprising a basic control mix, reinforced with CNTs and/or PP fibers） and the age of testing. Accompanying tests used to characterize the cementitious material were also conducted. The test results illustrate that all the benefits gained due to the synergy between PP fibers and CNTs in the matrix, namely the maintenance of the multi-cracking effect with time, the increased strength and deformability as well as the highly increased material toughness, were imparted in the recorded bond response. The local bond response curves thus obtained were marked by a resilient appearance exhibiting sustained strength up to large levels of controlled bar-slip; the elasto-plastic bond response envelope was a result of the confining synergistic effect of CNTs and the PP fibers, and it occurred even without bar yielding.

关键词： carbon nanotubes strain resilient cementitious composite polypropylene fibers tensile bending bond

Redox-neutral photocatalytic strategy for selective C–C bond cleavage of lignin and lignin models via PCET process

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Science Bulletin 2019年第22期64卷 1658-1666页

作者： Yinling Wang Yue Liu Jianghua He Yuetao Zhang State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University

It remains challenging to achieve the selective cleavage of C–C bonds in lignin or lignin model compounds to produce aromatic products in high yield and *** have developed a redox-neutral photocatalytic strategy to accomplish this goal in both b-O-4 and b-1 lignin models at room temperature(RT)via proton-coupled electron transfer(PCET)process without any pretreatments of substrate,by adjusting the alkalinity of base to obtain a lignin models/base PCET pair with a bond dissociation free energy close to 102 kcal/*** breaking down C_b–Ccbond and any C–O bonds,this PCET method is 100%atom economy and produces exclusive Ca–C_bbond cleavage products,such as benzaldehydes(up to 97%)and phenyl ethers(up to 96%),in high to excellent yields and *** studies indicated that the PCET strategy is also effective for the depolymerization of native lignin at RT,thus providing significantly important foundation to the depolymerization of lignin.

关键词： C–C bond cleavage Lignin depolymerization Photocatalysis Proton-coupled electron transfer Redox-neutral

Separation of m-cresol from aromatic hydrocarbon and alkane using ionic liquids via hydrogen bond interaction

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2675-2686页

作者： Qian Liu Xianglan Zhang Wei Li School of Chemical and Environmental Engineering China University of Mining and TechnologyBeijing 100083China School of Chemical Engineering Beijing Institute of Petro-Chemical TechnologyBeijing 102600China

Low temperature coal tar contained a large amount of phenols, aromatic hydrocarbons and alkanes;the separation of phenols from coal tar has a great significance to the deep processing of coal tar. In this work, the separation of m-cresol from cumene and n-heptane by liquid–liquid extraction using ionic liquids(ILs) as extractants was studied. The suitable ILs were screened by conductor-like screening model for real solvents(COSMO-RS)model and the liquid–liquid phase equilibrium(LLE) experiments were to verify the accuracy of the screening results. The extraction conditions such as extraction time, extraction temperature and mass ratio of ILs to model oils were evaluated. An internal mechanism of the m-cresol extract by ILs was revealed by COSMO-RS calculation and FT-IR. The results showed that the selected ILs can extract m-cresol effectively from cumene and nheptane, 1-ethyl-3-methylimidazolium acetate(emim CH3 COO) was the best extraction solvent. A hydrogen bond between anion of ILs and phenolic hydroxyl groups was observed. M-cresol in model oils could be extracted with extraction efficiencies up to 98.85% at an emim CH3 COO: model oils mass ratio of 0.5 and 298.15 K,emim CH3 COO could be regenerated and reused for 4 cycles without obvious decreases in extraction efficiency and extractant mass.

关键词： Extraction M-cresol Ionic liquids Separation COSMO-RS Hydrogen bond

Synthesis and Properties of Reversible Disulfide bond-based Self-healing Polyurethane with Triple Shape Memory Properties

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Chinese Journal of Polymer Science 2019年第11期37卷 1119-1129页

作者： Han Jia Kun Chang Shu-Ying Gu Department of Polymeric Materials School of Materials Science and Engineering Tongji University Shanghai 201804 China Key Laboratory of Advanced Civil Engineering Materials Ministry of Education Tongji University Shanghai 201804 China

A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone)(PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG), and 4,4,-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (^1H-NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal properties, selfhealing properties, triple-shape memory effect, and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments, and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 50℃(with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. As-prepared polyurethane is expected to have potential applications in multi-shape coatings, films, and step-by-step deploying structures.

关键词： Self-healing Reversible disulfide bond Triple shape memory Polyurethane

Effects of nano-AlN on phase transformation of low temperature vitrified bond during sintering process

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中国有色金属学会会刊：英文版 2009年第S3期19卷 706-710页

作者：尚勇侯永改乔桂英邹文俊肖福仁廖波 Key Laboratory of Metastable Materials Science and Technology College of Material Science and EngineeringYanshan University College of Materials Science and Engineering Henan University of Technology School of Environment and Chemical Engineering Yanshan University

The effects of nano-AlN and sintering temperature on bending strength and wear resistance of low temperature vitrified bond for diamond grinding tools were studied. Furthermore, the phase transformation during sintering process was investigated by means of thermo-gravimetric analysis (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD). The results show that the higher bending strength and wear resistance of low temperature vitrified bond are obtained by adding nano-AlN in bonds and sintering at optimum temperature. Nano-AlN added in bonds promotes the crystallization during sintering process and refines the grain sizes of crystalline phase.

关键词： low temperature vitrified bond nano-AlN sintering phase transformation