[TPPFe(III)]~2O的合成及其对细胞色素P-450的模拟

TPPFe(III)Cl通过中性Al~2O~3色谱柱得到一个新化合物, 它在HPLC中的保留时间比TPPFe(III)Cl大得多, IR、UV-Vis和元素分析表明, 这个新化合物是[TPPFe(III)]~2O. 同TPPFe(III)Cl一样, 它具有在常温常压下催化碳氢化合物单充氧化的性质。[TPPFe(III)]~2O催化下PhIO氧化环己烷的反应, 在CH~2Cl~2和环己烷介质中, 氧化产率分别为14.97和62.6%, 高于TPPFe(III)Cl作催化剂时的产率。在环己烷溶剂中, 反应产率与反应时间呈线性关系, 且反应有大约3小时诱导期。但在CH~2Cl~2溶剂中不存在反应产物与时间的线性关系, 也不存在诱导期。与TPPFe(III)Cl比较,[TPPFe(III)]~2O对氧化剂更稳定。上述事实表明, [TPPFe(III)]~2O能够作为细胞色素P-450的模型化合物。     

双核铜蛋白模型化合物的合成、氧合和催化苯偶姻的氧化

在碱的作用下,2,4-双(N-咪唑甲基)-6-取代苯酚(1)和2,6-双(N-咪唑甲基)-4-氯苯酚(2)与1,2-二溴乙烷、1,3-二溴丙烷、1,4-二溴丁烷或α,α'-二溴间二甲苯反应,合成了新型的模型配体(3～9)。配体与[Cu(CH~3CN)~4]ClO~4反应,得到两个咪唑基与铜配位的双核铜蛋白模型化合物(10～16)。研究了模型物的氧合作用,发现模型物15和氧气反应,发生分子内的羟化,生成μ-酚氧基-μ-羟基的双核铜(Ⅱ)配合物,其它模型与氧气反应,生成双(μ-羟基)双核铜(Ⅱ)配合物。以4为例,详细研究了其模型物催化氧化苯偶姻的反应及反应动力学。考查了碱、外加配体、金属离子等对氧化反应的影响,发现模型物的活性是铜盐或单核铜配合物活性的近六倍。求出了反应的动力学参数V~m~a~x、k~m分别为9.47×10^-^5mol·dm^-^3·s^-^1和0.0418mol·dm^-^3,表明模型物催化的苯偶姻反应,遵从Michaelis-Menten动力学规律。     

扩散系数与内压

本文将Eyring的液体粘性流动分子模型推广到了液体混合物,并用热力学方法导出一个无限稀释溶液中溶质的的放散系数与溶剂内压间的关系式.推导表明,扩散所需的空穴大小适为一个溶质分子所占液体的体积.扩散的活化能不仅取决于溶剂对溶质分子的作用能,而且还与在溶剂中形成空穴的难易程度有关.     

Huckel-hubbard相关图

Huckel模型和Heisnberg-Dirac模型考虑了两种不同的相互作用,前者为单电子作用,而后者仅考虑了电子相关作用,它们是 Hubbard 模型的两种极限情形.本文以四轨道四电子体系为例讨论了三种模型,所得到的Huckel-Hubbard相关图展示了它们的适用范围及其相互关系,这样处理具有代表性,可以推广到较大的共轭体系.     

用计量置换吸附模型研究液-固色谱中的溶质保留机理

本文以表面物理化学吸附模式为基础, 推导出液-固色谱中溶质计量置换保留模型. 与其他模型进行比较的结果证明本模型为最佳. 提出用参数j作为区别反相色谱和液-固色谱的判据.     

Letter: Eigentensors of the Bel Tensor

The Bel tensor admits symmetries which can beidentified with the groups of the standard model. Theeigentensor problem is the SU(2) hiddensymmetry.     

Cosmological Models with Bulk Viscosity in the Presence of Particle Creation

The effect of bulk viscosity, with a time varying bulk viscous coefficient, on the evolution of frw models is investigated in the context of open thermodynamic systems, which allows for particle creation. It is seen that, by choosing an appropriate function for particle creation, the models presented exhibit non-singular beginnings.     

In situ observation of interfacial debonding process induced by matrix crack propagation in two-dimensional unidirectional model composites

Interfacial debonding behavior is studied for unidirectional fiber reinforced composites from both experimental and analytical viewpoints. A new type of two-dimensional unidirectional model composite is prepared using 10 boron fibers and transparent epoxy resin with two levels of interfacial strength. In situ observation of the internal mesoscopic fracture process is carried out using the single edge notched specimen under static loading. The matrix crack propagation, the interfacial debonding growth and the interaction between them are directly observed in detail. As a result, the interfacial debonding is clearly accelerated in specimens with weakly bonded fibers in comparison with those with strongly bonded fibers. Secondary, three-dimensional finite element analysis is carried out in order to reproduce the interfacial debonding behavior. The experimentally observed relation between the mesoscopic fracture process and the applied load is given as the boundary condition. We successfully evaluate the mode II interfacial debonding toughness and the effect of interfacial frictional shear stress on the apparent mode II energy release rate separately by employing the present model composite in combination with the finite element analysis. The true mode II interfacial debonding toughness for weaker interface is about 0.4 times as high as that for a stronger interface. The effect of the interfacial frictional shear stress on the apparent mode II energy release rate for the weak interface is about 0.07 times as high as that for the strong interface. The interfacial frictional shear stress and the coefficient of friction for weak interface are calculated as 0.25 and 0.4 times as high as those for strong interface, respectively.     

Effect of interfacial debonding and matrix cracking on mechanical properties of multidirectional composites

In composites, debonding at the fiber–matrix interface and matrix cracking due to loading or residual stresses can effect the mechanical properties. Here three different architectures — 3-directional orthogonal, 3-directional 8-harness satin weave and 4-directional in-plane multidirectional composites — are investigated and their effective properties are determined for different volume fractions using unit cell modeling with appropriate periodic boundary conditions. A cohesive zone model (CZM) has been used to simulate the interfacial debonding, and an octahedral shear stress failure criterion is used for the matrix cracking. The debonding and matrix cracking have significant effect on the mechanical properties of the composite. As strain increases, debonding increases, which produces a significant reduction in all the moduli of the composite. In the presence of residual stresses, debonding and resulting deterioration in properties occurs at much lower strains. Debonding accompanied with matrix cracking leads to further deterioration in the properties. The interfacial strength has a significant effect on debonding initiation and mechanical properties in the absence of residual stresses, whereas, in the presence of residual stresses, there is no effect on mechanical properties. A comparison of predicted results with experimental results shows that, while the tensile moduli E ₁₁, E ₃₃and shear modulus G ₁₂ match well, the predicted shear modulus G ₁₃ is much lower.     

EMG模型参数间的联系

通过色谱拖尾峰EMG数学模型的计算机数值计算, 建立了拖尾峰特征参数之间的三类不同性质的线性关系, 佐证并修正了一些经验公式, 提出了计算模型参数与保留时间之间线性关系的新方法。