Self-Assembly Behavior and Application of Terphenyl-Cored Trimaltosides for Membrane-Protein Studies: Impact of Detergent Hydrophobic Group Geometry on Protein Stability

Amphipathic agents are widely used in various fields including biomedical sciences. Micelle-forming detergents are particularly useful for in vitro membrane-protein characterization. As many conventional detergents are limited in their ability to stabilize membrane proteins, it is necessary to develop novel detergents to facilitate membrane-protein research. In the current study, we developed novel trimaltoside detergents with an alkyl pendant-bearing terphenyl unit as a hydrophobic group, designated terphenyl-cored maltosides (TPMs). We found that the geometry of the detergent hydrophobic group substantially impacts detergent self-assembly behavior, as well as detergent efficacy for membrane-protein stabilization. TPM-Vs, with a bent terphenyl group, were superior to the linear counterparts (TPM-Ls) at stabilizing multiple membrane proteins. The favorable protein stabilization efficacy of these bent TPMs is likely associated with a binding mode with membrane proteins distinct from conventional detergents and facial amphiphiles. When compared to n-dodecyl-β-d -maltoside (DDM), most TPMs were superior or comparable to this gold standard detergent at stabilizing membrane proteins. Notably, TPM-L3 was particularly effective at stabilizing the human β₂ adrenergic receptor (β₂AR), a G-protein coupled receptor, and its complex with G_s protein. Thus, the current study not only provides novel detergent tools that are useful for membrane-protein study, but also suggests a critical role for detergent hydrophobic group geometry in governing detergent efficacy.     

Synthesis of asymmetrically substituted head‐to‐head polyacetylenes from 2,3‐disubstituted‐1,3‐butadienes

Asymmetrically substituted head‐to‐head polyacetylenes with phenyl and triphenylamine, thienyl or pyrenyl side groups were synthesized through anionic or controlled radical polymerization of 2,3‐disubstituted‐1,3‐butadienes and subsequent dehydrogenation process. Anionic polymerizations of the designed monomers bearing pendent triphenylamine and thienyl group gave narrow disperse disubstituted precursor polybutadienes with exclusive 1,4‐ or 4,1‐structure, which were confirmed by GPC and NMR measurements. In addition, the monomers possessing pyrenyl group were polymerized via nitroxide mediated radical polymerization and the resulting polymers were obtained with controlled molecular weight and low polydispersities. These polybutadiene precursors were then dehydrogenated in the presence of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone. Thus asymmetrically substituted head‐to‐head polyacetylenes were obtained as indicated by ¹H NMR. The properties of polybutadiene precursors and the corresponding polyacetylenes were analyzed by UV–vis, DSC, and TGA. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 395–402     

Ultrastretchable and conductive core/sheath hydrogel fibers with multifunctionality

Conductive hydrogels with ionic compounds possess great potential for the development of soft smart devices. A dielectric scarfskin is typically required for these devices to prevent short circuiting, leading to devices with lower stretchability than the hydrogel. Henceforth, commonly used dielectric materials, such as PDMS and Ecoflex, cannot be largely stretched. Hydrogel devices with ultrastretchability are required to accommodate hostile application environments. Herein, we propose a hydrogel fiber coated with a dielectric layer that can be stretched to over 2000% of its initial length. The fiber remains conductive when stretched to ~1300%. In addition, the core/sheath hydrogel fiber can be endowed with a variety of functional properties, such as electroluminescence (EL), photoluminescence (PL), and magnetic‐responsiveness, demonstrating scalability of the resultant fiber. The present work can pave the way for numerous next‐generation soft devices, such as smart textiles and wearable electronics. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 272–280     

A path-oriented encoding evolutionary algorithm for network coding resource minimization

Network coding is an emerging telecommunication technique, where any intermediate node is allowed to recombine incoming data if necessary. This technique helps to increase the throughput, however, very likely at the cost of huge amount of computational overhead, due to the packet recombination performed (ie coding operations). Hence, it is of practical importance to reduce coding operations while retaining the benefits that network coding brings to us. In this paper, we propose a novel evolutionary algorithm (EA) to minimize the amount of coding operations involved. Different from the state-of-the-art EAs which all use binary encodings for the problem, our EA is based on path-oriented encoding. In this new encoding scheme, each chromosome is represented by a union of paths originating from the source and terminating at one of the receivers. Employing path-oriented encoding leads to a search space where all solutions are feasible, which fundamentally facilitates more efficient search of EAs. Based on the new encoding, we develop three basic operators, that is, initialization, crossover and mutation. In addition, we design a local search operator to improve the solution quality and hence the performance of our EA. The simulation results demonstrate that our EA significantly outperforms the state-of-the-art algorithms in terms of global exploration and computational time.     

大口径石英基底衍射透镜的高精度制备方法

针对传统接触式曝光过程中掩模版因自身重力产生形变从而引入不可忽视的线宽误差和位置误差的问题,提出了一种大口径石英基底衍射透镜的高精度制备方法.采用背面具有真空道的高平面度、高强度金属校正工装吸附在掩模版上,利用掩模版上下表面的压强差使其与工装高度贴合,确保掩模版的高平面度.待石英基底所有区域均与掩模版结构面紧密贴合后取下工装.完成接触式曝光和显影后,采用反应离子刻蚀技术对大口径石英基底进行刻蚀,最终得到高精度微纳米结构.经有限元分析,使用该校正工装后,掩模版的形变量由28.85μm减小为0.88μm.实验结果表明,采用该方法制备的口径430mm两台阶石英基底菲涅尔衍射透镜波像差优于1/25λ,平均衍射效率为38.24%,达到理论值的94.35%,具有良好的聚焦和光学成像效果.     

Growth of Hydrophilic CuS Nanowires via DNA‐Mediated Self‐Assembly Process and Their Use in Fabricating Smart Hybrid Films for Adjustable Chemical Release

Facile growth of CuS nanowires through self‐assembly and their application as building blocks for near‐infrared light‐responsive functional films have been demonstrated. It is found that DNA is a key factor in preparing the CuS material with defined nanostructure. An exclusive oriented self‐aggregate growth mechanism is proposed for the growth of the nanowires, which might have important implications for preparing advanced, sophisticated nanostructures based on DNA nanotechnology. By employing the hydrophilic CuS nanowire as an optical absorber and thermosensitive nanogel as guest reservoir inside alginate film, a new platform for the release of functional molecules has been set up. In vitro studies have shown that the hybrid film possesses excellent biocompatibility and the release rate of chemical molecules from the film could be controlled with high spatial and temporal precision. Our novel approach and the resulting outstanding combination of properties may advance both the fields of DNA nanotechnology and light‐responsive devices.     

Formation of Cr(VI) compounds during the thermal decomposition of amorphous chromium hydroxide

Chromium hydroxide (CH) was prepared by the reduction of purified sodium chromate using starch. CH was then used to prepare chromium oxide (Cr₂O₃). Results of thermogravimetric, X-ray diffraction, Fourier transform infrared spectroscopy, and chemical analyses suggested that a small amount of the initial Cr(VI) content speeds up the oxidation and reduction reactions, thereby promoting the purity and crystallization of Cr₂O₃. Cr(VI) in CH induced the evolution of CH and the formation of Cr(VI) containing compounds including CrO₃, NaCr(CrO₄)₂, Cr₃O₈, and Cr₅O₁₂ at low sintering temperature. Furthermore, homogeneous Cr₂O₃ nanoparticles with 99 % purity and particle size of 50 nm were obtained.     

EAST上由垂直不稳定性引发破裂的分析与预测

从EAST 装置2016 年的放电实验中，选取了119 次等离子体破裂放电数据，分析诱发等离子体破裂的原因，发现约60%的破裂是由垂直不稳定性直接引起的，其破裂后将会产生更大的晕电流，从而产生更大的电磁应力损坏装置。对由垂直不稳定性引起的破裂(简称为VID)(72 次放电)进行了研究，建立了分别基于单变量(垂直位移)和两维变量(垂直位移、垂直位移增长率)的预测模型用于对VID 破裂的预测。离线测试表明，基于两维变量的预测模型可以在破裂发生前20ms 给出破裂预警信号，预测成功率达93%。