官能团修饰对MOF-5的气体分子吸附影响

采用紧束缚近似计算方法,研究了金属有机骨架(MOF-5)和不同官能团(―NO2,―NH2,―CH3,―OZn)修饰后的MOF-5不同吸附位点的CO2等温室气体和部分工业废气吸附性能以及对不同气体的选择性吸附能力.结果表明,对于未修饰的MOF-5,位点I和II是主要的吸附位点,最大吸附能可达-0.25eV.官能团修饰提高了MOF-5对CO2的吸附能力,其与官能团活性和局部位型密切相关.其中―NO2修饰使各位点的CO2吸附能力都有一定提高.同时,―NO2修饰后MOF-5对空气环境(O2,N2,H2O,CO2),工业废气环境(CO2,CO,NO,NO2,SO2,SO3)中不同气体有明显的选择性吸附能力.     

高选择性的1,3-二取代芳烃的-锅法碳氢活化三氟甲基化反应

Angew.Chem.Int.Ed.2012,51,540～543将三氟甲基官能团引入药物分子和农药分子等生物活性分子可以带来很多意想不到的生物活性和代谢特性.目前,对于芳烃的直接碳氢活化三氟甲基化方法仅有为数不多的报道,并且对非官能团诱导底物的高选择性碳氢活化三氟甲基化是一个具有挑战性的课题.中国科学院上海有机化学研究所有机氟化学重点实验室沈其龙小组采用通过     

官能团化N,C双齿N-杂环卡宾配合物研究进展

综述了官能团化N,C双齿N-杂环卡宾金属配合物研究的最新进展,着重讨论了这些配合物对各种化学反应的催化性能.     

红外光谱分析用于双酚A型环氧树脂的实验教学

通过红外光谱的实验教学,学生掌握了在高温和空气中氧的共同作用下,环氧树脂会发生一系列化学变化,从而发生老化甚至失效。通过特定官能团的跟踪分析,学生全面学习和掌握了环氧树脂从固化到老化红外光谱分析的全过程。     

烟气脱硫活性炭微波再生特性的实验研究

研究了烟气脱硫活性炭的微波再生特性。通过扫描电镜、N₂吸附、元素分析、Boehm滴定表征微波再生对活性炭孔隙结构和表面化学性质的影响,分析微波再生对活性炭吸附烟气中SO₂的影响规律。结果表明,微波再生功率越高,SO₂再生曲线越窄,峰值浓度越高,有利于载硫活性炭的解吸和高浓度再生气的获取。微波再生对活性炭起到了活化作用,使活性炭的孔结构变狭长。随着微波再生功率的提高,活性炭的微孔比表面积、微孔孔容增加,酸性官能团含量上升,碱性官能团含量下降。100 W再生后,活性炭再生不完全,残留的H₂SO₄影响了活性炭的吸附,活性炭的SO₂吸附性能下降。200、300、400 W工况下,活性炭的SO₂吸附容量均得到提高,且随着再生功率的提高,活性炭的碱性官能团含量上升,微孔比表面积、微孔孔容增加,SO₂吸附性能逐渐增强。     

SO2和NO对ACF低温脱除模拟燃煤烟气中VOC的影响

采用H₂O₂浸渍的方法对活性炭纤维(ACF)进行改性,并利用氮吸附等温线和XPS(X-ray photoelectron spectroscopy)的方法对ACF样品进行表征。通过实验测定改性前后ACF脱除VOC(甲苯作为VOC的代表物)的效果,同时考察二氧化硫(SO₂)和一氧化氮(NO)对ACF脱除甲苯的影响。研究发现,双氧水浸渍改性对ACF的BET表面积和孔容没有影响,但使得ACF样品表面的含氧官能团含量大量增加。实验数据也表明,SO₂和NO对VOC在ACF上的吸附具有抑制作用,且随着两者浓度的增加,抑制作用也增强。 研究还发现,SO₂和NO同时存在比单一的SO₂或NO对VOC在ACF上吸附的抑制作用更为明显。     

Crack-tip field on mode Ⅱ interface crack of double dissimilar orthotropic composite materials

Two systems of non-homogeneous linear equations with 8 unknowns are obtained.This is done by introducing two stress functions containing 16 undetermined coefficients and two real stress singularity exponents with the help of boundary conditions.By solving the above systems of non-homogeneous linear equations,the two real stress singularity exponents can be determined when the double material parameters meet certain conditions.The expression of the stress function and all coefficients are obtained based on the uniqueness theorem of limit.By substituting these parameters into the corresponding mechanics equations,theoretical solutions to the stress intensity factor,the stress field and the displacement field near the crack tip of each material can be obtained when both discriminants of the characteristic equations are less than zero.Stress and displacement near the crack tip show mixed crack characteristics without stress oscillation and crack surface overlapping.As an example,when the two orthotropic materials are the same,the stress singularity exponent,the stress intensity factor,and expressions for the stress and the displacement fields of the orthotropic single materials can be derived.     

Interface crack problems for mode II of double dissimilar orthotropic composite materials

The fracture problems near the similar orthotropic composite materials are interface crack tip for mode Ⅱ of double disstudied. The mechanical models of interface crack for mode Ⅱ are given. By translating the governing equations into the generalized hi-harmonic equations, the stress functions containing two stress singularity exponents are derived with the help of a complex function method. Based on the boundary conditions, a system of non-homogeneous linear equations is found. Two real stress singularity exponents are determined be solving this system under appropriate conditions about bimaterial engineering parameters. According to the uniqueness theorem of limit, both the formulae of stress intensity factors and theoretical solutions of stress field near the interface crack tip are derived. When the two orthotropic materials are the same, the stress singularity exponents, stress intensity factors and stresses for mode II crack of the orthotropic single material are obtained.     

Necking of anisotropic micro-films with strain-gradient effects

Necking of stubby micro-films of aluminum is investigated numerically by considering tension of a specimen with an initial imperfection used to onset localisation. Plastic anisotropy is represented by two different yield criteria and strain-gradient effects are accounted for using the visco-plastic finite strain model. Furthermore, the model is extended to isotropic anisotropic hardening （evolving anisotropy）. For isotropic hardening plastic anisotropy affects the predicted overall nominal stress level, while the peak stress remains at an overall logarithmic strain corresponding to the hardening exponent. This holds true for both local and nonlocal materials. Anisotropic hardening delays the point of maximum overall nominal stress.     

Stress field of orthotropic cylinder subjected to axial compression

Based on the constancy hypothesis of material volume, the circumferential and radial stresses of a cylinder specimen are analyzed when the cylinder is subject to a loading along the axial direction. The circumferential and radial stress distribution is a power function of radius parameter when the constitutive relation of specimen material is orthotropic. The stress distribution is a quadratic function of radius parameter for transversely isotropic material. Along the cylinder axial line, the circumferential and radial stresses are maximum and equal to each other. In the circumference boundary surface, the radial stress is zero and the circumferential stress value is minimal. The failure theory of maximum tensile circumferential strain is applied to calculate the critical axial loading. The circumference-boundary-layer failure criterion of orthotropic cylinders is described with the Hill-Tsai strength theory. The obtained strength theory is related to axial stress and mechanical properties of specimen material and to the specimen axialdeformation strain rate and the change rate of strain rate.