低碳钢大气腐蚀室内模拟加速腐蚀试验与锈蚀规律

建立实验室模拟大气腐蚀的干湿循环加速腐蚀方法.提出低碳钢锈蚀的分段演化规律,演化规律对应于锈层致密度转折和锈层结晶组分的形成,显示分段规律的合理性.实验室获得的低碳钢锈蚀演化规律与其在万宁和沈阳两个大气站现场曝晒的最新结果有相关性,证明加速腐蚀方法的可靠性.     

A Description of Vibrational Modes in Hexaphyrins: Understanding the Aromaticity Reversal in the Lowest Triplet State

Aromaticity reversal in the lowest triplet state, or Baird's rule, has been postulated for the past few decades. Despite numerous theoretical works on aromaticity reversal, experimental study is still at a rudimentary stage. Herein, we investigate the aromaticity reversal in the lowest excited triplet state using a comparable set of [26]‐ and [28]hexaphyrins by femtosecond time‐resolved infrared (IR) spectroscopy. Compared to the relatively simple IR spectra of [26]bis(rhodium) hexaphyrin ( R26H ), those of [28]bis(rhodium) hexaphyrin ( R28H ) show complex IR spectra the region for the stretching modes of conjugated rings. Whereas time‐resolved IR spectra of R26H in the excited triplet state are dominated by excited state IR absorption peaks, while those of R28H largely show ground state IR bleaching peaks, reflecting the aromaticity reversal in the lowest triplet state. These contrasting IR spectral features serve as new experimental aromaticity indices for Baird's rule.     

Paternò-Büchi反应的区域选择性

Paternò-Büchi(P-B)反应,即羰基-烯的[2+2]光环化加成反应,利用其特殊的区域及立体选择性可以合成一些结构精巧的取代氧杂环丁烷。随着P-B反应在有机合成中越来越广泛的应用,人们对P-B反应的区域选择性的研究也越来越深入。在P-B反应发现之初,人们一直用“最稳定的双自由基规则”解释其区域选择性,这一规则对有些体系却不适用,近年来有人开始运用“自旋化学”理论来解释区域选择性。本论文结合作者的研究工作,评述了近年来P-B反应的区域选择性的研究进展,重点阐述了反应温度、反应物的取代基对P-B反应区域选择性的影响及其规律。     

Normalization and Fermi–Coulomb and Coulomb hole sum rules for approximate wave functions

For approximate wave functions, we prove the theorem that there is a one‐to‐one correspondence between the constraints of normalization and of the Fermi–Coulomb and Coulomb hole charge sum rules at each electron position. This correspondence is surprising in light of the fact that normalization depends on the probability of finding an electron at some position. In contrast, the Fermi–Coulomb hole sum rule depends on the probability of two electrons staying apart because of correlations due to the Pauli exclusion principle and Coulomb repulsion, while the Coulomb hole sum rule depends on Coulomb repulsion. We demonstrate the theorem for the ground state of the He atom by the use of two different approximate wave functions that are functionals rather than functions. The first of these wave function functionals is constructed to satisfy the constraint of normalization, and the second that of the Coulomb hole sum rule for each electron position. Each is then shown to satisfy the other corresponding sum rule. The significance of the theorem for the construction of approximate “exchange‐correlation” and “correlation” energy functionals of density functional theory is also discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Making equation of state models predictive: Part 2: An improved PCP-SAFT equation of state

We use the PCP-SAFT equation of state, which is of the Van der Waals type and has a sound physical basis, to predict mixture properties, such as vapor–liquid and liquid–liquid equilibria, as well as excess enthalpies. We use molecular properties, such as dipole moment, quadrupole moment, polarizability and dispersion interaction coefficients, that have been determined quantum mechanically in Part I of this publication and adjust the remaining three pure compound parameters to pure compound data. We finally present a new combination rule for the dispersion energy parameter ? that is based on the quantum mechanically determined data. The predictions based on quantum mechanically determined pure compound properties along with the new combination rule show an improved performance compared to the original PCP-SAFT combination rule.     

Structure and Electronic Properties of Fullerenes C52q+: Is C522+ an Exception to the Pentagon Adjacency Penalty Rule?

The structure, vibrational spectra and electronic properties of the neutral, singly and doubly charged C52 fullerenes were studied by means of the Hartree-Fock method and density functional theory. Different isomers were considered, in particular those with the lowest possible number (five or six) of adjacent pentagons, and an isomer with a four-atom ring. For neutral and singly charged species, the most stable isomer is that with the lowest number of adjacent pentagons, namely five. However, for C(52)2+, the most stable structure has six adjacent pentagons. This finding, which contradicts the pentagon adjacency penalty rule, is a consequence of complete filling of the HOMO pi shell and the near-perfect sphericity of the most stable isomer. The simulated vibrational spectra show important differences in the positions and intensities of the vibrations for the different isomers.     

Effect of combining rules for cubic equations of state on the prediction of double retrograde vaporization

In this work, the phenomenon of double retrograde vaporization (DRV) is simulated using the Peng–Robinson equation of state with the classical mixing rules and several combining rules for the cross-energy and cross-co-volume parameters. The binary interaction parameters are set equal to zero in all cases, i.e., the calculations are entirely predictive. An interesting conclusion is that the predictions using the classical combining rules (geometric mean rule for a_ij and arithmetic mean rule for b_ij) provide the best agreement with the experimental data for all the systems tested: methane + n-butane, methane + n-pentane, ethane + limonene, and ethane + linalool. Another interesting observation is that several combining rules for b_ij, other than the arithmetic mean rule, predict the existence of three phases in equilibrium in a very narrow temperature range close to the critical temperature of methane in the methane + n-pentane system, even though, literature data indicates that n-hexane is the first n-alkane to present partial liquid phase immiscibility with methane.     

蒂巴茵衍生物的合成研究

The reaction of 7α-acetyl-6,14-endoethano-6,7,8,14-tetrahydrothebaine with 2-（thien-2-yl）ethylmagnesium bromide was investigated. The tertiary alcohol derivative 7α-[R-l-hydroxyl-l-methyl-3-（thien-2-yl）propyl]）-6,14- endoethano-6,7,8,14-tetrahydrothebaine （3） and a by-product 4 were isolated. The structure of 4 was elucidated by X-ray analysis. The Grignard reaction shows high degree of stereoselectivity according with Cram rule. The crystal structure of 4 indicates that dihydrofuran ring was opened to form a phenolic hydroxyl group and a three-membered ring structure. It maintains the main rigid structure of morphine and contains a C（6）-C（14） enthano bridge. The 1-hydroxyl-1-methyl-3-（thien-2-yl）propyl group at C（7） position adopted S-configuration.