Structured spheres generated by an in-fibre fluid instability

From drug delivery to chemical and biological catalysis and cosmetics, the need for efficient fabrication pathways for particles over a wide range of sizes, from a variety of materials, and in many different structures has been well established. Here we harness the inherent scalability of fibre production and an in-fibre Plateau-Rayleigh capillary instability for the fabrication of uniformly sized, structured spherical particles spanning an exceptionally wide range of sizes: from 2?mm down to 20?nm. Thermal processing of a multimaterial fibre controllably induces the instability, resulting in a well-ordered, oriented emulsion in three dimensions. The fibre core and cladding correspond to the dispersed and continuous phases, respectively, and are both frozen in situ on cooling, after which the particles are released when needed. By arranging a variety of structures and materials in a macroscopic scaled-up model of the fibre, we produce composite, structured, spherical particles, such as core-shell particles, two-compartment 'Janus' particles, and multi-sectioned 'beach ball' particles. Moreover, producing fibres with a high density of cores allows for an unprecedented level of parallelization. In principle, 10(8) 50-nm cores may be embedded in metres-long, 1-mm-diameter fibre, which can be induced to break up simultaneously throughout its length, into uniformly sized, structured spheres.     

金纳米颗粒修饰的固定化葡萄糖氧化酶酶膜制备

分别利用柠檬酸钠和NaBH4作为还原剂、以PVP作为包覆剂制备不同类型、不同包覆情况的金纳米粒子,并用紫外可见分光光谱仪、透射电微镜等手段对制备的金纳米粒子的粒径、形貌和分散性进行表征。用金纳米粒子对葡萄糖氧化酶膜进行修饰,并在SBA生物传感分析仪上进行感应测量。研究结果表明,粒径小、分散性好的球状金纳米粒子可以极大地提高葡萄糖酶膜的灵敏度。     

DNA-guided crystallization of colloidal nanoparticles

Many nanometre-sized building blocks will readily assemble into macroscopic structures. If the process is accompanied by effective control over the interactions between the blocks and all entropic effects, then the resultant structures will be ordered with a precision hard to achieve with other fabrication methods. But it remains challenging to use self-assembly to design systems comprised of different types of building blocks-to realize novel magnetic, plasmonic and photonic metamaterials, for example. A conceptually simple idea for overcoming this problem is the use of 'encodable' interactions between building blocks; this can in principle be straightforwardly implemented using biomolecules. Strategies that use DNA programmability to control the placement of nanoparticles in one and two dimensions have indeed been demonstrated. However, our theoretical understanding of how to extend this approach to three dimensions is limited, and most experiments have yielded amorphous aggregates and only occasionally crystallites of close-packed micrometre-sized particles. Here, we report the formation of three-dimensional crystalline assemblies of gold nanoparticles mediated by interactions between complementary DNA molecules attached to the nanoparticles' surface. We find that the nanoparticle crystals form reversibly during heating and cooling cycles. Moreover, the body-centred-cubic lattice structure is temperature-tuneable and structurally open, with particles occupying only approximately 4% of the unit cell volume. We expect that our DNA-mediated crystallization approach, and the insight into DNA design requirements it has provided, will facilitate both the creation of new classes of ordered multicomponent metamaterials and the exploration of the phase behaviour of hybrid systems with addressable interactions.     

Hierarchical self-assembly of metal nanostructures on diblock copolymer scaffolds.

Self-assembly is emerging as an elegant, 'bottom-up' method for fabricating nanostructured materials. This approach becomes particularly powerful when the ease and control offered by the self-assembly of organic components is combined with the electronic, magnetic or photonic properties of inorganic components. Here we demonstrate a versatile hierarchical approach for the assembly of organic-inorganic, copolymer-metal nanostructures in which one level of self-assembly guides the next. In a first step, ultrathin diblock copolymer films form a regular scaffold of highly anisotropic, stripe-like domains. During a second assembly step, differential wetting guides diffusing metal atoms to aggregate selectively along the scaffold, producing highly organized metal nanostructures. We find that, in contrast to the usual requirement of near-equilibrium conditions for ordering, the metal arranged on the copolymer scaffold produces the most highly ordered configurations when the system is far from equilibrium. We delineate two distinct assembly modes of the metal component-chains of separate nanoparticles and continuous wires-each characterized by different ordering kinetics and strikingly different current-voltage characteristics. These results therefore demonstrate the possibility of guided, large-scale assembly of laterally nanostructured systems.     

Shape control technology during electrochemical synthesis of gold nanoparticles

Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuCl₄) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KNO₃, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuCl₄, respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH? catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.     

RAFT 分散聚合诱导自组装制备 PDMAs-PSx 嵌段共聚物纳米颗粒

可逆加成-断裂-链转移(reversible addition-fragmentation-chain transfer, RAFT)聚合诱导自组装(polymerization-induced self-assembly, PISA)是制备具有特定形貌嵌段共聚物纳米颗粒的高效手段. 以苯乙烯(styrene, St)为分散聚合的单体, PDMA可逆加成-断裂-链转移(reversible addition-fragmentation-chain transfer,RAFT)聚合诱导自组装(polymerization-induced self-assembly,PISA)是制备具有特定形貌嵌段共聚物纳米颗粒的高效手段.以苯乙烯(styrene,St)为分散聚合的单体,PDMA_(23)和PDMA_(38)为大分子链转移剂(chain transfer agent,CTA),乙醇为溶剂,在70℃下探究了纳米颗粒的形貌随不同聚合度(degree of ploymerizations,DPs)的转变情况.由实验结果可知:以PDMA_(23)为链转移剂,可调控苯乙烯的聚合度,得到球、虫、囊泡、复合囊泡等形貌;以PDMA_(38)为链转移剂,可在较宽的聚合度范围内得到均匀的球形纳米颗粒.     

Relativistic effects in homogeneous gold catalysis

Transition-metal catalysts containing gold present new opportunities for chemical synthesis, and it is therefore not surprising that these complexes are beginning to capture the attention of the chemical community. Cationic phosphine-gold(i) complexes are especially versatile and selective catalysts for a growing number of synthetic transformations. The reactivity of these species can be understood in the context of theoretical studies on gold; relativistic effects are especially helpful in rationalizing the reaction manifolds available to gold catalysts. This Review draws on experimental and computational data to present our current understanding of homogeneous gold catalysis, focusing on previously unexplored reactivity and its application to the development of new methodology.     

Mn_7C_3@C核壳型纳米粒子制备及其超级电容器电极特性

以甲烷作为碳源气体,块体锰作为原料,采用一种简单的直流电弧等离子体法成功制备了Mn_7C_3@C核壳型纳米粒子,用于高性能超级电容器的电极材料.所制备的Mn_7C_3@C核壳型纳米粒子平均直径为30~35nm.拉曼光谱结果显示石墨碳壳具有良好的导电性.通过循环伏安、恒电流充放电及电化学交流阻抗谱对Mn_7C_3@C核壳型纳米粒子电极材料进行电化学性能分析,结果表明其具有高比电容、快速充放电等优异的电化学性能.在扫描速率为1mV/s时,比电容最高可达185.8F/g.同时具有良好的循环稳定性,在100mV/s扫描速率下1 000次循环伏安测试后,比电容仍保持为最初的88%,与单纯Mn_7C_3(79%)相比,有明显提高.Mn_7C_3@C核壳型纳米粒子电极材料优异的电化学性能归因于其良好的核壳结构,富缺陷碳层具有良好的导电性,有助于离子的传输和结构的稳定,而内核Mn_7C_3主要产生赝电容,在C和Mn_7C_3的协同作用下产生双电层和赝电容双模式储能机制.     

Synthesis of carbon 'onions' in water.

The fabrication of carbon nanomaterials usually calls for expensive vacuum systems to generate plasmas and yields are disappointingly low. Here we describe a simple method for producing high-quality spherical carbon nano-'onions' in large quantities without the use of vacuum equipment. The nanoparticles, which have C60 cores surrounded by onion-like nested particles, are generated by an arc discharge between two graphite electrodes submerged in water. This technique is economical and environmentally benign, and produces uncontaminated nanoparticles which may be useful in many applications.     

生物法合成纳米金的研究进展

纳米金以它独特的光学、电学和催化性质受到人们越来越多的关注.目前,生物合成的纳米金具有经济、无毒、环境友好等特点而成为研究热点.综述了利用细菌、真菌、放线菌、酵母菌以及各种植物材料合成纳米金的方法,并将各种方法进行了比较,讨论了每种方法的特点、尺寸和形貌的控制以及合成机理.最后,展望了生物合成纳米金的应用以及未来的发展方向.     

用图形知识库方法建立智能教育系统

我们研制了图形知识库并为其构造了一些工具。这种方法可使结构化和分布式的知识更方便地表达和检索。结构化的知识表示，可以以层次和网状形式表示教学系统中的知识。知识的分布式表示可以用于在图形背景上描述知识。有时，这种形式对于有的智能教育系统也是必要的。我们的方法允许相同或不同的类型的知识表示嵌套。在多任务太阳工作站的大屏幕站上实现这些设想容易使用是建立智能教育系统的有力工具。，我们较详细地描述了图形知识库方法，并用简略的教育系统的例子，加以图解说明，这些系统也是用上述设想设计的。     

基于Java EE的棉纺织业管理信息系统开发

针对传统的信息系统开发方式不能满足棉纺织企业发展需求以及国外管理软件本地化后技术相对落后等问题，采用结构化生命周期法牙口面向对象法结合的方法开发了棉纺织企业员工个人管理系统．结果表明，Java EE为搭建具有可伸缩性、灵活性、易维护性的信息系统提供了良好的机制，该管理信息系统可以降低成本，提高绩效和管理水平．     

自组装制备磁性复合微球聚集体

用部分还原法制得纳米Fe3O4,用微乳液聚合法制备聚（苯乙烯-丙烯酸）高分子微球P（St-co-AA）,再以球形P（St-co-AA）为模板与Fe3O4磁粉通过静电自组装和氢键自组装制得磁性复合微球聚集体Fe3O4／P（St-co-AA）;利用XRD、TEM、SEM、IR等对样品进行表征,采用VSM对样品进行磁性能测试．结果表明所得样品为Fe3O4单相,平均粒径约10nm．P（St-co-AA）平均尺寸为约70nm,表面含有羧基,所制磁性复合聚集体Fe3O4/P（St-co-AA）的形貌为球形、多孔、粒径约5μm,磁粉含量为29％．磁性能测试表明当外加磁场为6KOe时,磁化强度达到饱和,饱和磁化强度为69emu.g^-1．研究表明pH、搅拌等对磁性复合微球聚集体的形成有重要影响．     

表面增强拉曼光谱研究尼古丁与金属纳米粒子的相互作用

以金、银纳米及Au@Ag、Au-Ag合金复合纳米粒子为基底,研究尼古丁分子的表面增强拉曼光谱,讨论分子在4种纳米粒子表面的作用方式及可能的吸附取向.结果表明,分子在金纳米和Au-Ag合金纳米粒子表面的吸附取向相同——垂直吸附,不同的是与金纳米粒子形成了稳定的N-Au键;由于银纳米粒子和Au@Ag核壳纳米粒子表面均富含大...     

Carbon nanothermometer containing gallium

Many applications have been found for carbon nanotubes, and we can now add a role as a 'nanothermometer' to this list. We describe how the height of a continuous, unidimensional column of liquid gallium inside a carbon nanotube (up to about 10 micrometres long and about 75 nanometres in diameter) varies linearly and reproducibly in the temperature range 50-500 degrees C, with an expansion coefficient that is the same as for gallium in the macroscopic state. We chose gallium as our thermal indicator because it has one of the greatest liquid ranges of any metal (29.78-2,403 degrees C) and a low vapour pressure even at high temperatures. This nanothermometer should be suitable for use in a wide variety of microenvironments.     

X-ray analysis of beta B2-crystallin and evolution of oligomeric lens proteins

The beta, gamma-crystallins form a class of homologous proteins in the eye lens. Each gamma-crystallin comprises four topologically equivalent, Greek key motifs; pairs of motifs are organized around a local dyad to give domains and two similar domains are in turn related by a further local dyad. Sequence comparisons and model building predicted that hetero-oligomeric beta-crystallins also had internally quadruplicated subunits, but with extensions at the N and C termini, indicating that beta, gamma-crystallins evolved in two duplication steps from an ancestral protein folded as a Greek key. We report here the X-ray analysis at 2.1 A resolution of beta B2-crystallin homodimer which shows that the connecting peptide is extended and the two domains separated in a way quite unlike gamma-crystallin. Domain interactions analogous to those within monomeric gamma-crystallin are intermolecular and related by a crystallographic dyad in the beta B2-crystallin dimer. This shows how oligomers can evolve by conserving an interface rather than connectivity. A further interaction between dimers suggests a model for more complex aggregates of beta-crystallin in the lens.     

金纳米粒子与谷胱甘肽相互作用及其分析应用

通过谷胱甘肽的巯基(-SH)与金纳米粒子的共价结合和氨基(-NH3+)与金纳米粒子的静电作用,使金纳米粒子自组装为有序的网状超分子结构,导致金纳米粒子的最大吸收波长从520 nm红移到668 nm,且在668 nm处的吸光度与谷胱甘肽的浓度在一定范围内呈正比.由此建立了以金纳米粒子为探针,简便、灵敏的测定谷胱甘肽的分析方法.本方法线性范围为0.01～0.20 mg/L,检出限3.0 μg/L(3 σ,9.8 nmol/L).     

DNA-programmable nanoparticle crystallization

It was first shown more than ten years ago that DNA oligonucleotides can be attached to gold nanoparticles rationally to direct the formation of larger assemblies. Since then, oligonucleotide-functionalized nanoparticles have been developed into powerful diagnostic tools for nucleic acids and proteins, and into intracellular probes and gene regulators. In contrast, the conceptually simple yet powerful idea that functionalized nanoparticles might serve as basic building blocks that can be rationally assembled through programmable base-pairing interactions into highly ordered macroscopic materials remains poorly developed. So far, the approach has mainly resulted in polymerization, with modest control over the placement of, the periodicity in, and the distance between particles within the assembled material. That is, most of the materials obtained thus far are best classified as amorphous polymers, although a few examples of colloidal crystal formation exist. Here, we demonstrate that DNA can be used to control the crystallization of nanoparticle-oligonucleotide conjugates to the extent that different DNA sequences guide the assembly of the same type of inorganic nanoparticle into different crystalline states. We show that the choice of DNA sequences attached to the nanoparticle building blocks, the DNA linking molecules and the absence or presence of a non-bonding single-base flexor can be adjusted so that gold nanoparticles assemble into micrometre-sized face-centred-cubic or body-centred-cubic crystal structures. Our findings thus clearly demonstrate that synthetically programmable colloidal crystallization is possible, and that a single-component system can be directed to form different structures.     

小型电缆电视传输系统设计方法

本文从信号分配和前端设备配置两方面,介绍了小型电缆电视多路传输系统的设计方法。该方法以一个实例为线索,其信号分配灵活多样,既反映了系统设计的一般方法,又体现了小型系统简便易行的设计特点,因而,对设想安装小型电缆电视系统的单位具有参考价值。同时,该方法也可作为小型共用天线电视系统的设计参考。     

Two-dimensional self-organization of 1-nonanethiol-capped gold nanoparticles

A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl₄^-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammonium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nucleation and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.