Inhibition of K-Ras4B-plasma membrane association with a membrane microdomain-targeting peptide

The association of K-Ras4B protein with plasma membrane (PM) is required for its signaling activity. Thus, direct inhibition of K-Ras4B–PM interaction could be a potential anti-Ras therapeutic strategy. However, it remains challenging to modulate such protein–PM interaction. Based on Ras isoform-specific PM microdomain localization patterns, we have developed a potent and isoform-selective peptide inhibitor, Memrasin, for detachment of K-Ras4B from the PM. Memrasin is one of the first direct inhibitors of K-Ras4B–PM interaction, and consists of a membrane l_d region-binding sequence derived from the C-terminal region of K-Ras4B and an endosome-escape enhancing motif that can aggregate on membrane. It forms peptide-enriched domains in the l_d region, abrogates the tethering of K-Ras4B to the PM and accordingly impairs Ras signaling activity, thereby efficiently decreasing the viability of several human lung cancer cells in a dose-responsive and K-Ras dependent manner. Memrasin provides a useful tool for exploring the biological function of K-Ras4B on or off the PM and a potential starting point for further development into anti-Ras therapeutics.

A membrane l_d microdomain-targeting hybrid peptide displays potent inhibition effect toward K-Ras4B-plasma membrane interaction and impairs Ras signaling output.     

空心ZnMn2O4纳米球和纳米立方体的室温合成及氧还原催化性能

室温条件下,在含有Zn2+的溶液中,以空心结构的MnO2作为前驱体,使用NaBH4作为还原剂,合成了尖晶石型的ZnMn2O4纳米空心球和纳米空心立方体. 通过XRD,SEM,TEM,BET等测试手段对合成产物的结构、形貌、组成、表面性质进行了表征. 实验结果表明,所制备的空心结构ZnMn2O4纳米球和纳米立方体的尺寸在400?600 nm, 空心结构的壳层是由5?6 nm颗粒紧密堆积而形成,厚度约为40 nm. 将所制备的纳米ZnMn2O4空心结构应用于氧还原（ORR）反应中,研究了其在碱性溶液中的氧还原电催化性能,结果显示,相对于ZnMn2O4纳米空心立方体,ZnMn2O4纳米空心球在氧还原反应中表现出较大的电流密度和高的电子转移数 (n=3.5), 具有较好的氧还原电催化性能,有望成为一种新型的氧还原电极电催化剂.     

多孔碳负载镍纳米颗粒的制备及催化氨硼烷水解制氢

合成了蜂窝状的分级多孔碳,并以多孔碳为载体通过浸渍-化学还原法制备碳载镍(Ni/C)作为催化氨硼烷水解制氢的催化剂。采用XRD、BET、SEM、Raman、TEM等手段对样品进行了表征并研究了Ni/C室温催化性能。结果显示,多孔碳比表面积高达737 m2·g-1,具有部分石墨化结构;负载的非晶态镍纳米颗粒平均粒径约为10 nm,均匀分布在碳基材。碳载镍对氨硼烷水解反应具有良好的催化活性,镍负载量为30wt%时催化性能最佳,298 K温度下放氢速率达到1 304.67 m L·min-1·g-1,活化能为29.1 k J·mol-1,并且具备一定的催化稳定性,表明Ni/C可作为一种廉价高效的催化剂应用于催化氨硼烷水解制氢。     

Preparation and characterization of poly(ether sulfone)/sulfonated poly(ether ether ketone) blend membranes

Polymer blends of sulfonated poly(ether ether ketone) (SPEEK) and poly(ether sulfone) (PES) in N-methyl-2-pyrrolidinone (NMP) were prepared by solution casting. The investigation on water uptake, methanol uptake, permeability and proton conductivity has been conducted. The spin-lattice relaxation time in the rotating frame of PES/SPEEK blend was obtained from the results of cross-polarization magic angle spinning (CP/MAS) solid state ¹³C NMR. SPEEK blended with PES resulted in increasing , indicating the molecular motion of polymer chain was reduced. The glass transition temperature of the PES/SPEEK blend membranes were predicted by the Kwei equation. PES plays an important role in the decreasing water uptake, methanol uptake and methanol permeability while enhancing the thermal stability of the blend membrane, which shows the feasibility for direct methanol fuel cell.     

La1-xCaxMnO3纳米颗粒的制备及氧还原催化性能

本文采用溶胶凝胶法制备了一系列不同Ca含量的钙钛矿型氧化物La1-xCaxMnO3(x=0~0.4)纳米颗粒,X射线粉末衍射及精修、扫描电镜表征显示其相纯度和结晶度高,颗粒平均粒径约40 nm。在0.1 mol.L-1KOH水溶液中进行的氧还原电催化性能测试显示,La0.7Ca0.3MnO3样品催化活性最高,表观电子转移数接近4,还原电流密度与Pt/C催化剂相当,而催化稳定性优于Pt/C。进一步研究了La1-xCaxMnO3样品中Mn价态、晶胞参数的改变对氧还原催化活性的影响,结果表明当x=0.3时,催化剂中Mn处于混合价态,Mn-O键长适中,最有利于电催化反应。     

Effect of P/Si polymeric silsesquioxane and the monomer compound on thermal properties of epoxy nanocomposite

The unique polymeric silsesquioxane/4,4′-diglycidyether bisphenol A (DGEBA) epoxy nanocomposites have been prepared by sol-gel method. The structure of nanocomposites was characterized by attenuated total reflectance (ATR) and solid state ²⁹Si NMR. The characteristic intensity of trisubstituted (T) structure was higher than that of tetrasubstituted (Q) structure from solid state ²⁹Si NMR spectra of 3-isocyanatopropyltriethoxysilane (IPTS) modified epoxy. The activation energies of curing reaction of epoxy system and IPTS modified epoxy system are 28-66 kJ/mol and 57-75 kJ/mol, respectively, by Ozawa’s and Kissinger’s methods. The triethyoxysilane side chain of IPTS modified epoxy might interfere the curing reaction of epoxy/amine and increase the activation energy of curing. The thermal degradation of nanocomposites was investigated by Thermogravimetric analysis (TGA). The char yield of nanocomposites was proportional to the 2-(diphenylphosphino)ethyltriethoxysilane (DPPETES) moiety content at high temperature. A higher char content could inhibit thermal decomposition dramatically and enhance the thermal stability. Moreover, the nanocomposites possess high optical transparency.     

储氢材料第一性原理计算的研究进展

综述了第一性原理计算在储氢材料研究中取得的成果和最新的进展。 第一性原理计算在储氢材料研究中的应用主要有以下4个方面： 1）研究纳米结构的储氢性能; 2） 研究储氢材料中掺杂和缺陷的作用及对储氢性能的影响; 3）研究储氢机理; 4）确定氢化物的几何结构以及预测新型储氢材料。 同时展望了第一性原理计算在储氢领域中的应用前景。     

基于等离子体的定向天线阵理论与实验研究

当前国内学者对等离子体天线的研究主要集中于柱状天线和反射面天线, 而在国外已有学者以等离子体阵列结构设计了功能多样的智能天线系统. 为了较系统地了解这一新的设计思路, 基于等离子体散射理论对中心单元激励的圆形定向天线阵进行了理论和实验研究. 设计了一个16元等离子体无源振子的圆形天线阵, 实现了天线电磁波单波束和多波束的定向辐射. 通过理论计算和分析, 阐述了天线电磁波单波束和多波束辐射的原理. 通过建立实验系统, 测试了圆形天线阵的定向辐射特性. 实验结果和理论值接近, 说明该等离子体圆形天线阵可以实现天线电磁波的定向辐射和多波束辐射. 另外, 该天线阵还具有快速切换辐射方向、参数快速重构、雷达隐身性良好的优点. 关键词： 等离子体 定向天线阵 单波束 多波束     

聚乙烯醇缩丁醛准固态电解质薄膜的制备和性能表征

研究了聚乙烯醇缩丁醛准固态电解质薄膜的制备及相关性能.通过向聚乙烯醇缩丁醛中加入适量造孔剂和辅助剂制备电解质薄膜,研究了薄膜制备过程中的相关影响因素和不同孔隙率的电解质薄膜对电池光电转换效率的影响.实验表明,通过向0.200g聚乙烯醇缩丁醛中加入6.000g碳酸钙、0.310g氯化钙和0.150g葡萄糖所制备的电解质薄膜性能最优,用其制备的染料敏化太阳能电池光电转换效率η=4.720%(开路电压Voc=0.7194V,短路电流密度Jsc=10.014mA·cm-2,填充因子FF=0.6559),达到相同条件下液态电解质电池的88%以上.薄膜电解质制备简单,封装方便,所用原料无毒无害,具有一定的发展潜力.     

Synthesis,Self-Assembly,and Cell Responses of Aromatic IKVAV Peptide Amphiphiles

Synthetic bioactive aromatic peptide amphiphiles have been recognized as key elements of emerging biomedical strategies due to their biocompatibility, design flexibility, and functionality. Inspired by natural proteins, we synthesized two supramolecular materials of phenyl-capped Ile-Lys-Val-Ala-Val (Ben-IKVAV) and perfluorophenyl-capped Ile-Lys-Val-Ala-Val (PFB-IKVAV). We employed UV-vis absorption, fluorescence, circular dichroism, and Fourier-transform infrared spectroscopy to examine the driving force in the self-assembly of the newly discovered materials. It was found that both compounds exhibited ordered π-π interactions and secondary structures, especially PFB-IKVAV. The cytotoxicity of human mesenchymal stem cells (hMSCs) and cell differentiation studies was also performed. In addition, the immunofluorescent staining for neuronal-specific markers of MAP2 was 4.6 times (neural induction medium in the presence of PFB-IKVAV) that of the neural induction medium (control) on day 7. From analyzing the expression of neuronal-specific markers in hMSCs, it can be concluded that PFB-IKVAV may be a potential supramolecular biomaterial for biomedical applications.