Multiple preparative chromatography. II. Dual-step system

Summary The capacity of dual-step preparative chromatographic separation systems is considered. It is shown that dualstep separation makes it possible to enhance the capacity of preparative installations as compared with single- and dual-stage purification of the compounds.     

Reverse-phase high-performance liquid chromatography of virus proteins and other hydrophobic proteins

Summary So far most solvents generally used in reverse phase chromatography (RPC) for separation of peptides and water soluble polypeptides could not be utilized for hydrophobic proteins such as membrane proteins and structural polypeptides of viruses due to their insufficient solubility. But we have introduced a new RP-HPLC solvent system which was very useful in our studies on poliovirus polypeptides. Formic acid in high concentration is an extremely potent solvent for proteins, particularly those that are hydrophobic. Preliminary estimates are made of the concentration of formic acid which is required to completely dissolve hydrophobic proteins. For example, solubilization of structural polypeptides of poliovirus which are absolutely water insoluble requires 60% formic acid. Therefore, we used a proportion of 60% formic acid in all solvents for reversed phase chromatography and applied propanol-2 or acetonitrile as the organic modifiers for gradient elution. Using this mobile phase all four poliovirus polypeptides of three serological types were obtained in high purity by this rapid procedure. In each case, polypeptides were quantitatively eluted independent of the amount of protein (1–1000 μg) injected onto the columns. The solvents used were volatile and easily removed in a short evaporation step. Therefore this solvent system is suited for analytical and for micropreparative separation of proteins for chemical, biochemical and immunological studies. Rechromatography and electrophoresis in SDS-polyacrylamide gels of the separated polypeptides demonstrated that this solvent system with its high proportion of formic acid did not alter their primary structure. There may have been major changes in secondary and tertiary structure. In contrast, alterations of the elution characteristics were observed after reduction of disulfide bridges and several modifications of proteins. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Sol-gel transition of polyacrylonitrile/propylene carbonate solution

The thermoreversible gelation of polyacrylonitrile (PAN)/propylene carbonate (PC) solution was investigated by calorimetric, thermomechanical, optical, and rheological measurements. Two endothermic signals are observed for PAN/PC gels in DSC thermograms, and the peak temperature of the higher melting endotherm coincides with the gel melting temperature determined from the TMA thermogram. SEM micrographs show that the overall structure is separated into two phases and is composed of sperical domains, which may be formed upon passing through the thermodynamically unstable or metastable state via the liquid-liquid phase separation. The gelation rate increases with the aging temperature. This is also discussed on the basis of the elasticity theory of the fishnet gel. © 1994 John Wiley & Sons, Inc.     

The evolution of starting vortex and secondary separation on an elliptic cylinder

Flow visualization was used to investigate experimentally the evolution process from symmetrical shedding to staggered shedding of the starting vortex and the phenomenon of secondary separation on an elliptic cylinder at moderate Reynolds numbers. The vortex structure of the flow separation was studied. The temporal variation of separation angle and length of wake vortex were given. The photographs and experimental results provided basis for further investigation of the complicated feature of the starting process of unsteady separated flows around an elliptic cylinder. The project supported by the National Natural Science Foundation of China.     

Effects of organic modifiers on the chiral recognition by different types of silica-immobilized bovine serum albumin

We prepared three columns containing bovine serum albumin immobilized on silica by different means and the effects of organic modifiers in the eluent on chiral separation were studied using N-substituted amino acids. Adsorption on silica, covalent immobilization to diol-silica with carbonyldiimidazole (CSP-II) and covalent immobilization to amino-silica with glutaraldehyde were studied. CSP-II had the highest stereoselectivity and was the most affected by organic modifiers in the eluent. The hydrophobicity of amino acid moiety affected the chiral recognition of N-benzoylamino acids and the aromaticity of the N-substituted group was important.     

Proper efficiency with respect to cones

Strict separation by a cone is used here to redefine proper efficiency. Two versions of the properness, which unify and generalize known definitions, are presented. Necessary and sufficient conditions for the existence of the set of properly efficient decisions and characterization of this set in terms of the supports of the decision set are given.The research was done while the author was a visiting professor at the University of British Columbia, Vancouver, British Columbia, Canada.     

接触问题中的快速凝缩消元法

用分离解法求解弹性接触问题时，在增量加载和迭代过程中，由于接触区某些节点的状态发生改变而导致方程组的系数矩阵某些行和列元素随之变化。根据此特点，本推导了一种新的自适应迭代算法-快速凝缩消元法，并给出具体的迭代步骤，避免了系数矩阵变化时必须重新形成矩阵的重复计算。     

Exotic Localized Coherent Structures of New (2+1)-Dimensional Soliton Equation

The variable separation approach is used to obtain localized coherent structures of the new (2 1)-dimensional nonlinear partialdifferential equation. Applying the Backlund transformation and introducing the arbitraryfunctions of the seed solutions, the abundance of the localized structures of this model are derived. Some special types ofsolutions solitoff, dromions, dromion lattice, breathers and instantons are discussed by selecting the arbitrary functionsappropriately. The breathers may breath in their amplititudes, shapes, distances among the peaks and even the numberof the peaks.