MSU-SMFI和MCM-41的催化裂化及烷基化活性比较

以MFI沸石前驱体作为基本结构单元组装介孔硅铝分子筛MSU-S_MFI. XRD和氮气吸附数据表明MSU-SMFI具有类似MCM-41的六方排列介孔孔道结构,而且其织构参数和以传统方法合成的含铝MCM-41也大体相当.NH₃-TPD显示由沸石前驱体组装的MSU-S_MFI较硅铝比相同的含铝MCM-41介孔分子筛的固体酸量显著提高.MSU-S_MFI上的异丙苯催化裂化转化率比含铝MCM-41提高31％, 1,3,5-三异丙苯在MSU-S_MFI上也发生了更深的裂解. MSU-S_MFI上萘的叔丁基化的转化率比含铝MCM-41提高了15％.以沸石前驱体作为基本结构单元是提高介孔分子筛固体酸性的有效方法.     

Fabrication and photoluminescence of hybrid organized molecular films of a series of gemini amphiphiles and europium(III)-containing polyoxometalate

Organic/inorganic hybrid monolayers, consisting of an oval decatungstoeuropate (EuW10) with photoluminescence and a series of gemini-type amphiphiles with various lengths of the flexible hydrophobic spacers, were formed through electrostatic interaction at the air/water interface. The ultrathin hybrid multilayer films could be fabricated through the horizontal transfer of the monolayers onto the solid substrates. The characteristic absorption band of EuW10 in the UV spectra of the hybrid films showed a slight red shift in comparison with that in solution, indicating the ordered arrangement of EuW10 in the hybrid films. FT-IR spectra of the hybrid films presented characteristic bands of EuW10, indicating that the structure of the cluster was kept in the films. X-ray diffraction measurements of the films revealed that the well-defined layer structures were formed in these multilayer films and the EuW10 cluster ions were orientated with their short axis parallel to the film surface. Typical photoluminescence of the 5D0 --> 7F2 and 5D0 --> 7F1 transitions of EuW10 was observed in the hybrid films. Interestingly, the relative intensity of the two emission bands varied with the spacer length of the gemini amphiphiles in the films. A size matching between EuW10 and the gemini amphiphile with a hexamethylene spacer was observed, which showed the lowest ratio of the emission intensity of 5D0 --> 7F2 to that of 5D0 --> 7F1. Circular nanoparticles were observed in the AFM images for all these hybrid films. In addition, the size of the formed nanoparticles showed a dependence on the spacer length.     

电感耦合等离子体原子发射光谱法测定镍基钎料中Cr,Si,B,Fe

建立了电感耦合等离子体原子发射光谱法测定镍基钎料中Cr,Si,B,Fe含量的新方法。以硝酸–氢氟酸溶解样品,分别选择267.716,288.158,249.677,259.940 nm作为分析谱线,不用进行基体匹配,可直接测定镍基钎料中Cr,Si,B,Fe含量。在优化的实验条件下,测定结果的相对标准偏差为0.71%~1.43%(n=11),加标回收率为97.0%~102.0%。该方法可满足日常分析对镍基钎料中Cr,Si,B,Fe含量的检测要求。     

Flame retardancy of epoxy resin nanocomposite with a novel polymeric nanoflame retardant

A wrapped nanoflame retardant, designated as polyhedral oligomeric silsesquioxane (POSS)‐poly(4‐bromostyrene) (PBS)‐carbon nanotubes (CNTs), was synthesized via π‐π stacking interactions between the walls of multiwalled carbon nanotubes and the silicon‐bromine containing hybrid copolymer (designated as POSS‐PBS) that was copolymerized by 4‐bromostyrene and acryloyloxyisobutyl polyhedral oligomeric silsesquioxane. The POSS‐PBS‐CNTs exhibited good dispersibility in epoxy resin (EP) without obvious aggregation. Furthermore, the fire behaviors of this flame‐retardant EP (FR‐EP) nanocomposites were examined via limited oxygen index (LOI) and cone calorimeter (CONE) tests. The FR‐EP had an ideal LOI value of 35.3% and its residual char yield obtained from CONE test was significantly enhanced from 5.9% to 15.3% with the incorporation of 4 wt% POSS‐PBS‐CNTs and 1.33 wt% Sb₂O₃ into EP matrix. Additionally, the addition of 4 wt% POSS‐PBS‐CNTs or POSS‐PBS can efficiently decrease the peak heat release rate (PHRR) of EP matrix by 41.0% or 45.6%, respectively.     

A Multifunctional Peptide‐Conjugated AIEgen for Efficient and Sequential Targeted Gene Delivery into the Nucleus

Gene therapy has immense potential as a therapeutic approach to serious diseases. However, efficient delivery and real‐time tracking of gene therapeutic agents have not been solved well for successful gene‐based therapeutics. Herein we present a versatile gene‐delivery strategy for efficient and visualized delivery of therapeutic genes into the targeted nucleus. We developed an integrin‐targeted, cell‐permeable, and nucleocytoplasmic trafficking peptide‐conjugated AIEgen named T_DNCP for the efficient and sequential targeted delivery of an antisense single‐stranded DNA oligonucleotide (ASO) and tracking of the delivery process into the nucleus. As compared with T_DNCP/siRNA‐NPs (siRNA functions mainly in the cytoplasm), T_DNCP/ASO‐NPs (ASO functions mainly in the nucleus) exhibited a better interference effect, which further indicates that T_DNCP is a nucleus‐targeting vector. Moreover, T_DNCP/ASO‐NPs showed a favorable tumor‐suppressive effect in vivo.     

Extraordinary Modulation of Disulfide Redox‐Responsiveness by Cooperativity of Twin‐Disulfide Bonds

Disulfide bonds have frequently been incorporated into synthetic materials to promote sensitivity of the systems towards different redox environments. Although many strategies have been developed to rationally tune the stability of disulfide linkers, methods to tune their responsiveness towards different redox environments remain elusive. In this work we have developed and explored a disulfide linker bearing two independent disulfide bonds, referred to as a twin‐disulfide linker. We have demonstrated that the twin‐disulfide linker displays an ultrahigh stability at lower concentrations of reducing agent or in weakly reducing environments without a significant compromise in the sensitivity of its response to highly reducing environments such as cytoplasm, a feature that is in remarkable contrast to the traditional single disulfide bonds. Such an extraordinary responsiveness arises from the cooperativity of the twin‐disulfide bonds, which should be of particular interest for applications such as controlled drug delivery and sensing, because relatively large differences in disulfide stability in different redox environments is desired in these applications.     

Design and tailoring of a three-dimensional reduced graphene oxide/helical carbon nanotube composite for electrochemical biosensing application

Journal of Solid State Electrochemistry - Herein, three-dimensional reduced graphene oxide/helical carbon nanotubes (RGO/HCNTs) nanocomposites were synthesized by a combined solution-based method...     

一步法制备铁氧化物/氮改性氧化石墨/碳纳米管异质结及其用于催化活化过一硫酸氢钾降解亚甲基蓝模型染料（英文）

随着较差的生物相容性和更高毒性有机染料的应用,如酚类化合物和抗生素,水污染和食品污染变得极其严重.这不仅危害人类健康,而且严重污染自然环境.过硫酸盐去污技术利用自由基活化降解过程,成为处理一系列污染物非常有效的方法;然而设计具有多功能性的高性能催化剂仍然面临着巨大的挑战.因此,本文借鉴铁基材料、氮改性石墨和碳纳米管独特的物化性质,以尿素、铁盐、氧化石墨、碳纳米管为原材料,通过一步水热法成功制备了三维多功能铁氧化物/氮改性氧化石墨/碳纳米管异质结,用作活化过一硫酸氢钾复合盐以降解有机模型污染物亚甲基甲蓝(MB),研究了高级氧化法(AOPs)作用机理和优化反应条件.XRD、红外光谱、SEM和XPS结果表明,铁氧化物通过物理静电作用力和化学键结合力已经被牢牢固定在了氮修饰的氧化石墨结构框架内.当加入了碳纳米管之后,它会与石墨形成类似于互穿聚合物网络的结构,从而具有三维材料的优点,且提升电子转移电导率,使得催化剂的结构和性能有了很大的改善.此外,优化了降解系统、PMS负载量、初始有机污染物浓度和催化剂用量等因素.结果表明,处于催化剂/PMS系统时,亚甲基蓝可以在12min之内有效地完全降解,可归结于碳、氮以及主要活性物质铁氧化物之间的协同作用.基于数据拟合分析,污染物氧化降解系统与拟一阶动力学相符合,其速率常数约为0.33 min~(-1).淬灭实验证明,硫酸根自由基和羟基自由基是主要的反应活性物种.这种同时富含铁/氮分级的多孔碳骨架异质结物质不仅可用作过渡金属催化剂,而且为制备其他异质结提供参考,以用于超级电容器、储能材料、电催化剂等领域     

Hydrogenated Bismuth Molybdate Nanoframe for Efficient Sunlight‐Driven Nitrogen Fixation from Air

Sunlight‐driven dinitrogen fixation can lead to a novel concept for the production of ammonia under mild conditions. However, the efficient artificial photosynthesis of ammonia from ordinary air (instead of high pure N₂) has never been implemented. Here, we report for the first time the intrinsic catalytic activity of Bi₂MoO₆ catalyst for direct ammonia synthesis under light irradiation. The edge‐exposed coordinatively unsaturated Mo atoms in an Mo?O coordination polyhedron can act as activation centers to achieve the chemisorption, activation, and photoreduction of dinitrogen efficiently. Using that insight as a starting point, through rational structure and defect engineering, the optimized Bi₂MoO₆ sunlight‐driven nitrogen fixation system, which simultaneously possesses robust nitrogen activation ability, excellent light‐harvesting performance, and efficient charge transmission was successfully constructed. As a surprising achievement, this photocatalytic system demonstrated for the first time ultra‐efficient (1.3 mmol g^?1 h^?1) and stable sunlight‐driven nitrogen fixation from air in the absence of any organic scavengers.     

Adsorption equilibrium,kinetics and mechanism of Pb(II) over carbon–silica composite biosorbent with designed surface oxygen groups

Research on Chemical Intermediates - Heavy metal contamination, especially contamination involving Pb(II), is a major environmental problem faced by modern society; hence, research on...