On the copolymerization of acrylates in the modified microemulsion process

Copolymerization of methyl methacrylate, methyl acrylate, butyl methacrylate, and butyl acrylate in turn was performed in the modified microemulsion polymerization process, i.e., continuous addition of monomer to a preemulsified system. It was found that the particle size of the copolymer microlatex did not change distinctly with the monomer composition. The estimation of emulsifier coverage on the microlatex particles indicated that the process switched from a traditional microemulsion to a normal seeded emulsion polymerization very soon after monomer dropping began. Therefore, a longer dropping time is needed to produce a microlatex with narrow dispersed particle size. Besides, in the modified microemulsion polymerization less emulsifier is needed to produce a stable microlatex. This behavior is related to the mechanism of normal seeded emulsion polymerization during monomer dropping.     

基于离子液体的炭材料制备、改性及应用

离子液体因其熔点低、液态温域宽、蒸气压低、热稳定性高、电导率高、电化学窗口宽、结构可设计及对许多化合物的亲和性等系列性能而引起人们广泛关注。离子液体在炭材料制备、改性领域展示出了良好的前景及巨大的应用潜力,可直接作为碳源,经过高温炭化实现杂原子掺杂制备多孔炭材料;离子液体也可充当反应介质和致孔剂,将生物质转化为多孔炭材料;此外,由于离子液体与炭材料相容性较好,可以用于多孔炭材料改性制备炭复合材料。基于离子液体的炭材料在电催化、超级电容器、吸附分离及生物医学等领域具有潜在的应用价值。本文总结了基于离子液体炭材料的制备、改性及应用最新研究进展,并着重介绍了其在能源和环境相关领域的应用。     

Hydrogenated polybutadiene–polymethyl methacrylate (HPB–PMMA) block copolymer. I. Synthesis of polybutadiene–polymethyl methacrylate (PB–PMMA) block copolymer

To get hydrogenated polybutadiene-polymethyl methacrylate (HPB-b-PMMA) block copolymer to be used as a compatibilizer for blends of polyolefin/polar polymer, PB-b-PMMA was synthesized by anionic-free radical mechanism transformation polymerization. Selective extraction, gradient elution thin layer chromatography, and oil-oil emulsion separation techniques were tried to attempt to separate the copolymerization products. Hydrogenation of the PB sequence in PB-b-PMMA yielded HPB-b-PMMA. The compatibilizing function of PB-b-PMMA was shown in blending experiments. © 1993 John Wiley & Sons, Inc.     

Spectrophotometric study of the interaction of tetraphenylporphyrin tetrasulfonate (TPPS4) with proteins

The interaction of water-soluble porphyrin TPPS(4) (tetraphenylporphyrin tetrasulfonate) with proteins in acidic solution was studied by spectrophotometry. The absorption spectra of TPPS(4)-protein complexes, the aggregation of TPPS(4) in acidic solution, and comparison of the absorption spectra of TPPS(4)-protein conjugate with that of the TPPS(4)-protein complex was investigated in detail. The effects of denaturants including urea and SDS were also examined. A mechanism was proposed that TPPS(4) would be distributed between microphase of protein and the aqueous solution and then aggregated in the microphase.     

Systematic quantification of the dynamics of newly synthesized proteins unveiling their degradation pathways in human cells

Proteins are continuously synthesized during cell growth and proliferation. At the same time, excessive and misfolded proteins have to be degraded, otherwise they are a burden to cells. Protein degradation is essential to maintain proteostasis in cells, and dysfunction of protein degradation systems results in numerous diseases such as cancer and neurodegenerative diseases. Despite the importance of protein degradation, the degradation pathways of many proteins remain to be explored. Here, we comprehensively investigated the degradation of newly synthesized proteins in human cells by integrating metabolic labeling, click chemistry, and multiplexed proteomics, and systematic and quantitative analysis of newly synthesized proteins first revealed the degradation pathways of many proteins. Bioinformatic analysis demonstrates that proteins degraded through two major pathways have distinct properties and functions. Proteins degraded through the ubiquitin-proteasome pathway contain more disordered structures, whereas those through the autophagy-lysosome pathway have significantly higher hydrophobicity. Systematic and quantitative investigation of the dynamics of newly synthesized proteins provides unprecedented and valuable information about protein degradation, which leads to a better understanding of protein properties and cellular activities.

Systematic quantification of the dynamics of newly synthesized proteins first reveals the degradation pathways of many proteins in human cells, and proteins degraded through each of the two major pathways have distinct properties and functions.     

Limits of One-dimensional Interacting Particle Systems with Two-scale Interaction*

This paper characterizes the limits of a large system of interacting particles distributed on the real line. The interaction occurring among neighbors involves two kinds of independent actions with different rates. This system is a generalization of the voter process, of which each particle is of type A or a. Under suitable scaling, the local proportion functions of A particles converge to continuous functions which solve a class of stochastic partial differential equations driven by Fisher-Wrig...     

An identification of the connections of Quillen and Beilinson-Schechtman

Given a family of Riemann surfaces and a holomorphic vector bundle Beilinson and Schechtman construct a canonical connection on the associated determinant bundle. We prove the conjecture which states that their connection coincides with the Quillen connection. This is done by reducing to the case where along fibers are invertible. Both connection forms become more accessible in this case.Supported in part by N.S.F. Grant No. DMS-9201022Supported in part by National Science Council of Republic of China Grant No. NSC 82-0208-M-002-125-T, and NSERC of Canada Grant No. OGP 0121883