A facile “graft from” method to prepare molecular‐level dispersed graphene–polymer composites

Graphene–polymer composites of positive‐charged poly(dimethyl aminoethyl acrylate), negative‐charged poly(acrylic acid), and neutral polystyrene were prepared by “graft from” methodology using reversible addition fragmentation chain transfer (RAFT) polymerization via a pyrene functional RAFT agent (PFRA) modified graphene precursor. Fluorescence spectroscopy and attenuated total reflection infrared (ATR‐IR) evidenced that the PFRA was attached on the graphene basal planes by π–π stacking interactions, which is strong enough to anti‐dissociation in the polymerization mixture up to 80°C. Atomic force microscopy (AFM) revealed that the thickness of a graphene–polymer sheet was about 4.0 nm. Graphene composites of different polymers with the same polymerization degree exhibited similar conductivity; however, when the polymer chain was designed as random copolymer the conductivity was significantly decreased. It was also observed that the longer the grafted polymer chains the lower the conductivity. ATR‐IR spectroscopy and thermogravimetric analysis were also performed to characterize the as‐prepared composites. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Fabrication of Cobaltosic Oxide Nanoparticle-Doped 3 D MXene/Graphene Hybrid Porous Aerogels for All-Solid-State Supercapacitors

MXenes are a new family of 2 D transition metal carbides and nitrides, which have attracted enormous attention in electrochemical energy storage, sensing technology, and catalysis owing to their good conductivity, high specific surface area, and excellent electrochemical properties. In this work, a series of Co₃O₄-doped 3 D MXene/RGO hybrid porous aerogels is designed and prepared through a facile in situ reduction and thermal annealing process, in which the reduced graphene oxide (RGO) conductive network can electrically link the separated Co₃O₄-MXene composite nanosheets, leading to enhanced electronic conductivity. It is found that upon using the Co₃O₄-MXene/RGO hybrid porous aerogel prepared with a mass ratio of Co₃O₄-MXene/RGO of 3:1 (CMR31) as an electrode for a supercapacitor, a superior specific capacitance of 345 F g⁻¹ at the current density of 1 A g⁻¹ is achieved, which is significantly higher than those of Ti₃C₂T_x MXene, RGO, and MXene/RGO electrodes. In addition, a high capacitance retention (85 % of the initial capacitance after 10 000 cycles at a high current density of 3 A g⁻¹) and a low internal resistance R_s (0.44 Ω) can be achieved. An all-solid-state asymmetric supercapacitor (ASC) device is assembled using CMR31, and it has the ability to light up a blue LED indicator for 5 min if four ASCs are connected in series. Therefore, these novel Co₃O₄-MXene/RGO hybrid porous aerogels have potential practical applications in high-energy storage devices.     

基于环状DNA-银纳米簇荧光探针对微囊藻毒素-LR的传感检测

以新型环状DNA为模板, 制备了环状DNA-银纳米簇(Circular DNA-AgNCs)荧光探针, 构建了一种无酶无标记检测微囊藻毒素-LR(MC-LR)的荧光传感分析方法. 设计的环状DNA由MC-LR适体链(Apt)和适体链的互补链(cDNA)杂交形成, 且cDNA可作为DNA模板用于合成AgNCs. 利用透射电子显微镜(TEM)、 紫外-可见光谱(UV-Vis)和荧光光谱(FL)表征了AgNCs的形貌和光学特性.结果表明, 当存在目标物MC-LR时, 由于MC-LR与环状DNA中Apt高特异性和高亲和力结合, 导致环状DNA解体, 释放出的cDNA-AgNCs在610 nm处呈现强荧光. 在优化实验条件下, 环状DNA-AgNCs荧光探针对MC-LR检测的线性范围为0.005~500 μg/L, 检出限为1.7 ng/L(S/N=3). 该荧光探针具有制备简单、 无需任何标记和灵敏度高等特点, 为环境水样中微囊藻毒素-LR的快速和准确测定提供了一种简单、 可靠和有效的方法.     

Carbon Nanomaterials in Biosensors: Should You Use Nanotubes or Graphene?

From diagnosis of life‐threatening diseases to detection of biological agents in warfare or terrorist attacks, biosensors are becoming a critical part of modern life. Many recent biosensors have incorporated carbon nanotubes as sensing elements, while a growing body of work has begun to do the same with the emergent nanomaterial graphene, which is effectively an unrolled nanotube. With this widespread use of carbon nanomaterials in biosensors, it is timely to assess how this trend is contributing to the science and applications of biosensors. This Review explores these issues by presenting the latest advances in electrochemical, electrical, and optical biosensors that use carbon nanotubes and graphene, and critically compares the performance of the two carbon allotropes in this application. Ultimately, carbon nanomaterials, although still to meet key challenges in fabrication and handling, have a bright future as biosensors.     

Stepwise synthesis of Gly-Gly-His on gold surfaces modified with mixed self-assembled monolayers

Peptide-modified electrode surfaces have been shown to have excellent recognition properties for metal ions. An efficient method of screening a potential peptide for its selectivity for a given metal would involve the synthesis of the peptide directly on the electrode surface. This paper outlines a procedure in which the tripeptide Gly-Gly-His was synthesized one amino acid at a time on a gold surface modified with a self-assembled monolayer of the mixed alkanethiolates 3-mercaptopropionic acid (MPA) and 3-mercaptopropane (MP). Electrochemistry and high-resolution mass spectrometry were used to elucidate the structure of the adsorbed species and follow the synthesis. The amino acids can be attached only to MPA, but the presence of a diluting unreactive molecule of MP reduces steric crowding about the reaction center. The maximum coverage of synthesized tripeptide occurs at a ratio of MPA/MP of 1:1.     

Diatoms: self assembled silica nanostructures, and templates for bio/chemical sensors and biomimetic membranes

In this review we highlight recent advances in the understanding of biosilica production, biomodification of diatom frustules and their subsequent applications in bio/chemical sensors, and as a model membrane for filtration and separation.     

昆明白小鼠与F1代杂交鼠（昆明白×BALB／c）超排,移植效果的比较

本实验比较了昆明白小鼠与Ｆ_１代杂交鼠（昆明白×ＢＡＬＢ／ｃ）的排卵数、怀孕率、百枚卵产仔数．经统计分析,Ｆ_１代杂交鼠的平均排卵数、怀孕率、百枚卵产仔数均极显著的高于昆明白小鼠．     

Controllable corrugation of chemically converted graphene sheets in water and potential application for nanofiltration

A combination of AFM, SEM and permeation experiments suggests that the amplitude of corrugation of chemically converted graphene (CCG) sheets in water can be readily controlled by hydrothermal treatment, leading to a new class of permeation-tuneable nanofiltration membranes.     

一种钡金属有机框架材料的合成及其晶体结构和发光性能的研究

金属有机框架(MOFs)因其独特的结构和在晶体工程与材料科学领域中的潜在应用而成为研究热点。目前,大多数MOFs都以过渡金属为中心,而具有特殊构型的第Ⅱ主族金属(碱土金属)受到的关注则相对较少。本文采用溶剂热法,以异烟酸氮氧化物(HINO)为有机配体,与二水合氯化钡(BaCl₂·2H₂O)金属盐合成了一种新型的三维Ba(Ⅱ)-MOF材料[Ba(INO)₂]_n。通过单晶X射线衍射、X射线粉末衍射、红外光谱、元素分析、热重分析、荧光光谱等测试对该Ba-MOF进行了结构和性能表征。单晶X射线衍射结果表明:[Ba(INO)₂]_n为单斜晶系,Cc空间群,晶胞参数为a=1.636 14(7) nm,b=1.126 35(4) nm,c=0.742 40(3) nm,中心离子Ba(Ⅱ)为高配位数的九配位变形三帽三角棱柱体几何构型。[Ba(INO)₂]_n结构中的Ba—O一维链由B型INO配体连接形成二维平面层结构,再由A型INO配体沿着4个方向延伸连接形成三维框架。然而有趣的是,当Ba—O一维链直接由A型INO配体连接时即可形成三维微孔框架,而B型INO配体则进一步撑起该三维框架形成坚实稳定的柱撑结构。[Ba(INO)₂]_n表现出良好的热稳定性。此外,固态荧光测试显示,在330 nm紫外光激发下,[Ba(INO)₂]_n发出395 nm的蓝光,相比于HINO配体的437 nm最大发射峰,出现了明显的蓝移,这是由INO配体与Ba(Ⅱ)金属离子之间的电荷转移导致的。     

适用于ICF靶夹持的多用微夹持器

针对惯性约束聚变靶零件的特点和靶装配应用环境,研制了一种多用微夹持器。该微夹持器以压电陶瓷驱动柔性钳体,集成张合量和夹持力控制功能,可更换各种形状夹口和调整夹口初始开口距离,以适应多种靶零件的夹持。利用有限元分析方法对钳体柔性机构进行了优化设计。通过检测钳体张合时不同部位柔性铰链的应变量,实现了张合量和夹持力的独立控制,并对张合量和夹持力进行了精确标定。实验结果表明：微夹持器张合量达到1 320 m,其控制分辨力为5 m;夹持力为365.0 mN,其控制分辨力1.3 mN。