相界面张力对两相聚合物熔体中分散相粒子粗化速度的影响研究

The coarsening process of the droplets in two\|phase polymer blend system was studied under 2\|dimensional conditions using a phase contrast microscope and computer image analyzer.It was found that the substrate (glass) has significant effect on the phase separation and droplets coarsening process.The interfacial interaction(wetting effects)will accelerate the droplets coarsening process when one phase has stronger affinity to the substrate than another phase,and the growth of the droplets radius with time follows r\+3～t\+a a >1.On the other hand,when there is almost the same interaction between the dispersed phase and the matrix with the substrate,i.e.the two phases have the same wettability to the substrate (such as the system of PP/PE),no effect of the substrate on the coarsening process of the droplets was observed,i.e.the growth law is r\+3～t according to Ostwald ripening theory.It is expected that there is a critical value for the interfacial tension between the components of blends under 2\|D condition.The growth law of the dispersed phase changes\|over above or below the critical point.

模拟技术在吹塑型坯成型中的研究进展

介绍了模拟技术在吹塑型坯成型中的研究和发展状况 ,针对型坯成型过程 ,对国内外学者进行数值分析的方法和理论依据进行了论述 ,着重论述了神经网络方法。并指出型坯成型是吹塑过程的核心 ,是一个受聚合物材料性能、熔融温度。

Influence of Energy on Solvent Diffusion in Polymer/Solvent Systems

The Vrentas-Duda free-volume theory has been extensively used tocorrelated or predict the solvent diffusion coefficient of apolymer/solvent system. The energy term in the free volume diffusionequation is difficult to estimate, so the energy term was usuallyneglected in previous predictive versions of the free volumediffusion coefficient equation. Recent studies show that the energyeffect is very important even above the glass transition temperatureof the system. In this paper, a new evaluating method of the energyterm is proposed, that is, the diffusion energy at different solventconcentrations is assumed to be a linear function of the solventdiffusion energy in pure solvents and that in polymers under thecondition that the solvent in infinite dilution.

Procedure for preparing peptide-major histocompatibility complex tetramers for direct quantification of antigen-specific cytotoxic T lymphocytes

AIM： To establish a simplified method for generating peptide-major histocompatibility complex （MHC） class I tetramers.METHODS： cDNAs encoding the extracellular domain of human lymphocyte antigen （HLA）-A＊0201 heavy chain （A2） and β2-microglobulin （132m） from total RNA extracted from leukocytes of HLA-A2＋ donors were doned into separate expression vectors by reverse transcription-polymerase chain reaction. The recombinant A2 and 132m proteins were expressed in ~/a oo/i^uain BL21（DE3） and recovered from the inclusion body fraction. Soluble A2 proteins loaded with specific antigen peptides were refolded by dilution from the heavy chain in the presence of light chain 132m and HLA-A2-restricted peptide antigens. The refolded A2 monomers were biotinylated with a commercial biotinylation enzyme （BirA） and purified by low pressure anion exchange chromatography on a Q-Sepharose （fast flow） column.The tetramers were then formed by mixing A2 monomers with streptavidin-PE in a molar ratio of 4：1. Flow cytometry was used to confirm the expected tetramer staining of CD8^＋ T cells.RESULTS： Recombinant genes for HLA-A＊0201 heavy chain （A2） fused to a BirA substrate peptide （A2-BSP） and mature β2m from HLA-A2＋ donor leukocytes were successfully doned and highly expressed in E. coli, Two soluble monomeric A2-peptide complexes were reconstituted from A2-BSP in the presence of 132m and peptides loaded with either human cytomegalovirus pp65495-503 peptide （NLVPMVATV,NLV; designated as A2-NLV） or influenza virus matrix protein Mp58-66 peptide （GILGFVFTL, GIL; designated as A2-GIL）. Refolded A2-NLV or A2-GIL monomers were biotinylated and highly purified by single step anion exchange column chromatography. The tetramers were then formed by mixing the biotinylated A2-NLV or A2-GIL monomers with streptavidin-PE, leading to more than 80% multiplicationas revealed by SDS-PAGE under non-reducing, unboiled conditions. Flow cytometry revealed that these tetramers could specifically bind to CD8^＋ T cells from a HLA-A2^＋ donor,but failed to bind to those from a HLA-A2- donor.CONCLUSION： The procedure is simple and efficient for generating peptide-MHC tetramers.

Thermodynamics of Systems： Photopolymers-Low-Molecular Liquids

Photopolymers （printing flexoforms） during their operation interact with solvents and properties and ultimately reduces printing quality. A purpose of the work was to study the photopolymer with low-molecular liquids by two independent methods （chromatography and mathematical model of the process the thermodynamic properties and Flory-Huggins polymer-solvent systems. swell. Swelling changes the elastic thermodynamics of interaction of swelling in solvents）. By using a parameters were determined for

A disubstituted-norbornene-based comonomer strategy to address polar monomer problem

The transition-metal-catalyzed copolymerization of olefins with polar comonomers is a direct strategy to access polar-functionalized polyolefins in an economical manner.Due to the intrinsic poisoning effect of polar groups towards Lewis acidic metal centers and the drastic reactivity differences of polar comonomers versus non-polar olefins,it is challenging to develop catalysts that provide the desired polymer molecular weight,comonomer incorporation,and activity.In this contribution,we tackle this issue from a comonomer perspective using 5,6-disubstituted norbornenes,which are highly versatile,easily accessible,inexpensive,and capable of introducing two functional groups in a single insertion.More importantly,they are only mildly poisoning due to the presence of long spacers between double bonds and polar groups,and are not prone to b-hydride elimination due to their cyclic structures.As strong pdonors,they can competitively bind to metal centers versus olefins.Indeed,phosphine-sulfonate palladium catalysts can catalyze the copolymerization of ethylene with 5,6-disubstituted norbornenes and simultaneously achieve a high polymerization activity,copolymer molecular weight,and comonomer incorporation.The practicality of this system was demonstrated by studying the properties of the resulting polymers,copolymerization in hydrocarbon solvents or in bulk,recovery/utilization of unreacted comonomer,molecular weight modulation,and large-scale synthesis.