Special attention has been paid to nanotubes and nanowires due to their interesting properties and potential applications. Since the discovery of carbon nanotubes [1] various nanotubes such as WS 2 , MoS 2 , BN, BC 2 N, and semiconductor nanowires such as CdTe and ZnCdSe have been synthesized.[2±7] The template technique is an important method of nanowire fabrication. Usually, there are two types of template: ªtrack-etchº polymer membranes, such as the polycarbonate membrane with 60 nm diameter pores, and the porous aluminum oxide membrane, with a pore diameter of 70 nm. [8,9] However, the challenges of fabricating semiconductor nanowires with a quantum confinement effect are great because technically useful quantum wires will require lateral dimensions less than 10 nm, and it is difficult to fabricate quantum wires on a scale lower than 10 nm.[10]Nanocables with a wire/sheath structure are another kind of potentially useful one-dimensional nanostructure. There have been a few reports on the preparation of semiconductor/insulator nanocables. For example, Si/SiO 2 nanocable has been prepared by combining laser-ablation cluster formation with vapor±liquid±solid (VLS) growth, [11] and b-SiC/SiO 2 nanocable has been obtained by the carbothermal reduction of sol±gel derived silica xerogels containing carbon nanoparticles at 1650 C. [12] In both cases, the outer layers of SiO 2 in nanocables are induced by the reaction atmosphere.In this communication, we design a new strategy for synthesizing a semiconductor/polymer nanocable in a heterogeneous solution system. In this system, an organic monomer with polar groups can self-organize into amphiphilic supramolecules, utilizing the difference in solubility of different fragments in the monomer molecule. Such supramolecules can polymerize to a pre-organized polymer tubule with a hydrophilic core and a hydrophobic sheath. Then the polymer tubule acts as both template and nanoreactor for the following growth of inorganic semiconductor nanowires in the hydrophilic cores from various water-soluble sources. Thus, a nanocable with semiconductor wire in a polymer sheath can be obtained. In this approach, g-irradiation offers an ideal means by which the supramolecules can be polymerized and the tubular structure can be solidified with the desired diameter at room temperature under ambient pressure. Based on the above strategy, a CdSe/poly(vinyl acetate) (PVAc) nanocable with a 6 nm core and an 80 nm diameter sheath was successfully synthesized from a heterogeneous system of vinyl acetate (VAc) monomer, cadmium sulfate (CdSO 4 ×8/3H 2 O), and sodium selenosulfate (Na 2 Se-SO 3 ) under g-irradiation at room temperature and ambient pressure. Appropriate amounts of analytically pure CdSO 4 [8/3H 2 O, Na 2 SeSO 3 , and isopropanol were dissolved in distilled water in a ground-glass stoppered flask, then mixed with VAc. Sodium selenosulfate can be synthesized by refluxing selenium powders in a sodium sulfite (Na 2 SO 3 ) solution according to the literature.[13] Isopropanol was used as ...
Large-scale synthesis and assembly of meso-, micro- and nanostructured building blocks with the desired orientations are of great interest for the next-generation nanoarchitecture design. On the consideration that the traditional synthetic methodologies for nanostructures often produce tangled nanounits, how to align the nanounits into the ordered orientation at high production yield is a great challenge to current methods. The present review describes a facile and controllable way to grow and assemble the 3D hollow nanoarchitectures, with the utilization of the synergic effects of hollowing process from the self-produced templates and the highly anisotropic growth of nanounits of the target materials in one-pot reaction. In this process, the building block nanounits spontaneously in-situ form owing to their highly anisotropic internal structure, while the self-produced templates act as the supporter and growth-direction guidance for the in-situ formed nanounits. Therefore, the whole assembly process is simple, controllable and without the complicated manipulations. Herein, in the light of the different kinds of self-produced templates involved in the assembly process, recent developments based on the new synergic-assembly strategy are reviewed according to the classifications: (1) self-produced gas bubble template strategy; (2) self-produced homogeneous solid template strategy; (3) self-produced heterogeneous solid template strategy. Notably, the synergic-assembly methodology described in this review provides a newly essential way to construct and assemble nanoarchitectures facilely and controllably, and is also a crucial step for the next-generation of nanoarchitecture design in the near future. In conclusion, the challenges and prospects for the future are discussed.
We investigate the dynamics of actin monomers that are assembled into long filaments via the particle-based Brownian dynamics simulations. In order to study the dynamics of long filaments containing up to several hundred protomers, a coarse-grained model for actin polymerization involving several simplifications is used. In order to overcome the large separation of time scales between the diffusive motion of the free monomers and the relatively slow polymerized and depolymerized processes at the two ends of the filaments, all polymerized and depolymerized rates are rescaled by a dimensionless parameter. Actin protomers within a filament generally possess three nucleotide states corresponding to a bound adenosine triphosphate (ATP), adenosine diphosphate with inorganic phosphate (ADP. Pi), and ADP molecules in the presence of ATP hydrolysis. Here in this paper, single nucleotide state and two nucleotide states of actin protomers are described by the simplified theoretical model, giving the dependence of the growth rate on actin concentration. The simplest case where all protomers are identical, is provided by the assembly of ADP-actins. In the simulations, the growth rate is found to increase linearly with free monomer concentration, which agrees quantitatively with in vitro experimental result. These surprised phenomena observed in the experiments, such as treadmilling processes and length diffusion of actin filaments at the steady state, are presented in detail by Brownian dynamics simulations. For free actin concentrations close to the critical concentration, cT ccr, T, the filaments undergo treadmilling, that is, they grow at the barbed end and shrink at the pointed end, leading to the directed translational motion of the filament. In the absence of ATP hydrolysis, the functional dependence of a length diffusion constant on ADP-actin monomer concentration implies that a length diffusion constant is found to increase linearly with ADP-actin monomer concentration. With the coupling of ATP hydrolysis, a peak of the filament length diffusion as a function of ATP-actin monomer concentration is observed i. e. , the length diffusion coefficient is peaked near to 35 mon2/s below the critical concentration and recovers to the expected estimate of 1 mon2/s above the critical concentration. These obtained results are well consistent with the experimental results and stochastic theoretical analysis. Furthermore, several other quantities and relations that are difficult to study experimentally but provide nontrivial crosschecks on the consistency of our simulations, are investigated in the particle-based simulations. The particle-based simulations developed in our studies would easily extend to study a variety of more complex systems, such as the assembly process of other dynamic cytoskeletons
One-dimensional ternary germanate nanomaterials exhibited wide application potential in the fields of magnetic devices, photocatalysis, sensors and lithium ion batteries owing to their good magnetic, photocatalytic, electrochemical and optical properties. The article reviewed the recent progress and patents on one-dimensional ternary germanate nanomaterials. The recent progress and patents on the synthesis of ternary germanate nanowires, nanorods and nanobelts synthesized by thermal evaporation, hydrothermal method and chemical vapor deposition process were demonstrated. The experimental progress and patents on the application of one-dimensional ternary germanate nanomaterials as magnetic devices, electrochemical sensors, photocatalysis and lithium ion batteries were discussed in detail. Finally, the future development direction of one-dimensional ternary germanate nanomaterials for the synthesis and application was also discussed.
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