环状和支链硬球链流体的状态方程

以单体缔合的统计力学理论为基础，建立了链状分子亥氏孙数和状态方程和空们相关函数的关系，并应用于环 状和支链硬球链流体。对这两类流体压缩因子的预测结果与计算机模型值相吻合。     

Sodium dialkyl phosphates: Surfactant properties and use in heavy duty detergents

A study of the physical and surface active properties of the sodium salts of dialkyl phosphates has been made. These compounds have been evaluated for use as surfactants in built detergents and their performance has been compared with commercial surfactants. The dialkyl hydrogen phosphates contained from 16–26 carbon atoms per molecule and were prepared from both straight chain alcohols and commercially available branched chain alcohols. In general, the surface active properties of the branched chain compounds are better than their corresponding straight chain compounds. Good detergency performance is obtained when the number of carbon atoms per molecule is between 17 and 23. Optimum performance is obtained with the symmetrical didecyl hydrogen phosphate salts made from commercial decyl alcohol produced by the oxo-process.     

钴基催化剂合成长链烃的选择性控制

F－T反应产物具有广泛的碳数分布，近年来，F－T合成研究的重点转移到高选择性地合成重质烃（C5^ 以上）产物。综述了钴基催化剂应用于F－T反应合成长链烃中链增长途径和F－T合成选择性的关系，从理论上评述了能有效提高长链烃选择性的制备催化剂的方法，指出了采用蛋壳型催化剂、添加合适的助剂及选择具有规整孔道分布的中孔载体材料均有利于提高F－T产物中长链烃的选择性。     

Polyethoxylated alkyl phenols: Relationship of structure to biodegradation mechanism

Using various isolation procedures and measurement by infrared spectroscopy, the mechanism of biodegradation of the polyethoxylated alkyl phenols (ABE) in the river water die-away test has been ascertained. Degradation is shown to proceed by carboxylation of the alkyl chain and, in certain cases, by degradation of the ethylene oxide chain. Degradation of the ether chain has been found to take place only when the chain contains ten or less units of ethylene oxide. The analytical evidence points to the degradation of the ether chain by a hydrolysis mechanism. The effect of ether chain degradation on the measurement of residual surfactant by ultraviolet spectroscopy and the cobalt thiocyanate procedures has been demonstrated. Ether chain degradation causes the ABE results to be high by ultraviolet measurement and low by the cobalt thiocyanate procedures. Results of this investigation emphasize the necessity of understanding the mechanism by which degradation takes place, and the significant importance of that degradation, in the various biodegradability tests, before the applicability and reliability of any test for measurement of the residual surfactant can be evaluated. Presented at AOCS Meeting in Cincinnati, October 1965.     

THE KRAMERS CHAIN MODEL FOR POLYMERS

The freely jointed bead-rod chain (the “Kramers chain”) is a fairly realistic model for a macromolecule, and therefore it has been finding increased use in polymer science, particularly in connection with the calculation of rheological properties. The equilibrium configurational distribution function is derived (not a “random-walk” function). Then some of the recent uses of the Kramers chain for understanding the nonequilibrium properties of solutions and melts are summarized.     

Cobaltothiocyanate colorimetric analysis for homologous polyoxyethylated alkyl amides

Cobaltothiocyanate colorimetry has been used for quantitative analysis of polyethoxylates in biodegradation and environmental studies. Usually, the calibration parameters (slope and intercept of a calibration line) for the cobaltothiocyanate colorimetry are dependent on ethylene oxide chain length. To make the colorimetric method useful for polyoxyethylated surfactant mixtures, where the average chain length is polydispersed, a condition was found yielding parameters independent of chain length in a homologous series of polyethoxylates within a limited chain length range. The dependency can be correlated to the thermodynamics of the ethylene oxide-cobaltothiocyanate complexation and the solvent extraction.     

Refinement of protein cores and protein-peptide interfaces using a potential scaling approach

Refinement of side chain conformations in protein model structures and at the interface of predicted protein-protein or protein-peptide complexes is an important step during protein structural modelling and docking. A common approach for side chain prediction is to assume a rigid protein main chain for both docking partners and search for an optimal set of side chain rotamers to optimize the steric fit. However, depending on the target-template similarity in the case of comparative protein modelling and on the accuracy of an initially docked complex, the main chain template structure is only an approximation of a realistic target main chain. An inaccurate rigid main chain conformation can in turn interfere with the prediction of side chain conformations. In the present study, a potential scaling approach (PS-MD) during a molecular dynamics (MD) simulation that also allows the inclusion of explicit solvent has been used to predict side chain conformations on semi-flexible protein main chains. The PS-MD method converges much faster to realistic protein-peptide interface structures or protein core structures than standard MD simulations. Depending on the accuracy of the protein main chain, it also gives significantly better results compared with the standard rotamer search method.     

Influence of Carbonate on the Ozone/Hydrogen Peroxide Based Advanced Oxidation Process for Drinking Water Treatment

The influence of carbonate on the ozone/hydrogen peroxide process has been investigated. Carbonate radicals, which are formed from the reaction of bicarbonate/carbonate with OH radicals, act as a chain carrier for ozone decomposition due to their reaction with hydrogen peroxide. The efficiency of bicarbonate/carbonate as a promoter for the radical-based chain reaction in presence of hydrogen peroxide has been calibrated and compared to a well-known chain promoter (methanol) and an inhibitor (tert-butanol). Relative to tert-butanol, the hydrogen peroxide induced ozone decomposition is accelerated by bicarbonate/carbonate. Relative to methanol, bicarbonate/carbonate in presence of hydrogen peroxide is less effective as a promoter under comparable experimental conditions.     

Aminimides: III antimicrobial effect of various hexadecyl and quaternary derivatives

Aminimides, a new class of surfactants, have been screened for in vitro antimicrobial activity. Greatest activity against gram (+) and yeast organisms is achieved when a chain length of C₁₆ is reached. This generalization is true whether or not the chain length is joined to the imide or amine group. The type of functional group associated with the surfactant is less important than chain length. Gram (-) organisms do not fit this generalization, since shorter (<C₁₆) rather than longer chain derivatives are more active. The importance of surfactant chain length to biodegrad-ability is discussed.     

Medium‐chain fatty acids – Nutritional function and application to cooking oil

Medium‐chain fatty acids, which are saturated fatty acids composed of 8–10 carbons, have unique nutritional characteristics different from those of long‐chain fatty acids. Medium‐chain triacylglycerol (MCT) is more readily digested and absorbed than long‐chain triacylglycerol (LCT), and easily utilized as energy. The use of MCT as an edible oil is limited because it has a low smoking point and easily foams during deep‐frying like lauric acid does. Medium‐ and long‐chain triacylglycerol (MLCT) prepared by transesterification between MCT and LCT has a higher smoking point and reduced foaming property. MLCT oil has been shown to result in less body fat accumulation in animal and human studies. It has been approved as a food for specified health use (FOSHU) and widely sold in Japan as a cooking oil less likely to lead to body fat accumulation.     

高压下长链分子的自扩散系数研究

在Lennard-Jones流体自扩散系数方程的基础上,结合链状硬球流体自扩散系数的分子模拟数据,提出了链状Lennard-Jones流体的自扩散系数方程。将所提出的方程应用于计算长链烷烃和硅油在0.1-600MPa下的自扩散系数,其平均相对偏差在10％以内,计算结果优于自扩散系数的粗糙Lennard-Jones模型。     

Small-angle neutron scattering from a polymer coil undergoing stress relaxation

Small-angle neutron scattering measurements have been made on samples of polystyrene in which the stress has been allowed to relax at a constant strain. The radii of gyration parallel and perpendicular to the stretch direction have been measured as a function of time after the strain has been applied. After an initial rapid change, the radii of gyration tend towards asymptotic values which are close to those for the undeformed chain. The deformation appears to behave as if the affine deformation theory holds only for distances separating effective crosslinks. It is proposed that after the initial change in radii of gyration the stress is relieved by reorientation of the chain segments.     

双子两性磷酸酯/十二烷基硫酸钠复配体系的表面活性

研究了阴离子表面活性剂十二烷基硫酸钠(SDS)和双子两性磷酸酯表面活性剂(C12GP)的形成胶束能力和降低表面张力能力的协同作用,发现C12GP与SDS摩尔比为4∶1时增效作用显著.考察了无机盐、醇对复配体系表面活性的影响.结果表明:加盐能够提高表面活性;短链脂肪醇作为添加剂应用于复配体系后,当混合表面活性剂的浓度较低时,其临界胶束浓度(ccm)比直接使用混合表面活性剂的ccm有所下降;同时长链脂肪醇作为添加剂应用于复配体系后,其ccm比直接使用混合表面活性剂的ccm下降显著.     

Nature of absorption bands of thiazolopyrimidinium polymethine dyes

Both symmetric and asymmetric thiazolopyrimidinium monomethine-, carbo- and dicarbo-cyanines have been synthesized. The wavelengths of the first two long-wave absorption bands have been investigated by physical and quantum-chemical methods. Electron density distributions for the ground, the first excited and second excited singlet states have been calculated. The electron redistribution diagrams were used to analyze the localization of electron transitions. The first band has been shown to be localized in the polymethine chain (Kühn's chain) while the second band is mainly localized in the thiazolopyrimidinium end-group.     

Studies of the fischer-tropsch synthesis on a cobalt catalyst i. evaluation of product distribution parameters from experimental data

Two models describing the distribution of linear and monomethyl alkanes in Fischer-Tropsch products from a cobalt catalyst are formulated. Distribution parameters for monomethyl isomers are derived by assuming either a post-branching effect on linear chain growth or a decreasing reactivity toward branching with increasing chain length. Distribution parameters for each of the models have been extracted from an extensive experimental data set. We find that the experimental results are well represented by both the models. A “break” in the distribution of linear paraffins has also been observed and is modelled as a sum of the yields of two Anderson-Schulz-Flory distributions. We postulate that the two chain growth processes which produce the distributions are governed by two kinds of termination.     

Branched methacrylate copolymers from multifunctional monomers: chemical composition and physical architecture distributions

Soluble, branched (meth)acrylic copolymers have been made via facile, one-step, batch solution polymerisations taken to high conversion. Methyl methacrylate has been copolymerised with a bifunctional monomer using a chain transfer agent to inhibit gelation. Conventional chain transfer using a mercaptan has been compared to catalytic chain transfer (CCT) using a cobalt porphyrin. The polymerisations have been monitored as a function of monomer conversion and the polymer prepared at high conversion has been fractionated across the molecular weight distribution. The polymerisations remain isotropic, with both the chemical composition and physical architecture distribution varying systematically as a function of monomer conversion and copolymer molecular weight. A mechanism for the polymerisation is proposed based on the experimental data.     

The origin of chain entanglement: Correlations between entanglement and chain structure

A pseudotopological theory of chain entanglement has recently been developed, which shows that the entanglement junction is a binary hooking contact between two chains, and explicitly relates the entanglement behavior to chain structure. On the other hand, many empirical correlations between entanglement and chain structure have also been proposed to date, including those of Fox and Allen, Porter and Johnson, Privalko and Lipatov, Boyer and Miller, Graessley and Edwards, Aharoni, Lin, and Zang and Carreau. In this work, we show that the various empirical equations cited are variations of the same function, and can be derived as special cases from the theoretical pseudotopological equation. The various forms of the function nevertheless reveal different essential aspects of the chain entanglement behavior, and show that the traditional hooking view of chain entanglement is correct, and also provides a basis for the recent reptation-tube model.     

Kinetics of the ring‐opening polymerization of D,L‐lactide using zinc (II) octoate as catalyst

The kinetics of ring‐opening polymerization of D ,L ‐lactide with 2‐ethylhexanoic acid zinc (II) salt as catalyst and methanol as co‐catalyst at different temperatures is investigated. A previously proposed kinetic model accounting for reactions such as activation, propagation, chain transfer, transesterification and thermal non‐radical random chain scission has been applied to simulate the experimental results of conversion and average molecular weights. The relevance of some side reactions, mainly transesterifications and chain scission, has been verified all over the studied temperature range and the corresponding rate constants have been estimated. Copyright © 2011 Society of Chemical Industry     

Exact and approximate eigenvalues and intrinsic functions for the Gaussian chain theory

Eigenvalues for the Gaussian chain theory for dilute solutions of linear polymers have been determined in an exact manner for chain segments up to 100 and for a wide range of hydrodynamic interaction. It is found that these exact results may be closely approximated by a simple equation. The intrinsic functions of the eigenvalues which describe the molecular weight dependence of the intrinsic viscosity and terminal relaxation time of the chain are presented using both the exact and the approximate eigenvalues. It is shown that by using the simple approximate calculation good results are easily determined. The approximate equation is available for manipulation and analysis of complex eigenvalue functions.     

Influence of molecular weight on the fracture of poly(methyl methacrylate) (PMMA)

A model is proposed to explain the dependence of fracture parameters on the molecular weight of glassy polymers. The model assumes that the fracture event occurs in two stages; the first involves the orientation of polymer chain segments between entanglement points and the second, the fracture itself. A value has been calculated, (～0.6J m^?2), for the fracture surface energy corresponding to the lower critical molecular weight between entanglements, M=M_e. Allowing for the simplifying assumptions made in its derivation, this value is in good agreement with that found experimentally. It is proposed that, after the chain segments between entanglements crossing a plane have been fully extended, two possible mechanisms are involved; chain ‘pull-out’ up to a maximum governed by the time scale of the local fracture event, or chain scission. Using the concept of a reptating chain it is proposed that above M ～2 M_e there is a relationship between the fracture energy (γ) and the molecular weight of the form γ∝ ∝M² up to a critical value of M, above which γ is constant. It has been shown that there is some agreement with experimental relationships determined independently.