Nanotechnology 

About: Nanotechnology is an academic journal published by IOP Publishing. The journal publishes majorly in the area(s): Nanowire & Carbon nanotube. It has an ISSN identifier of 0957-4484. Over the lifetime, 22129 publications have been published receiving 720335 citations. The journal is also known as: nanotech & nanotechnology engineering.

The bactericidal effect of silver nanoparticles

Abstract: Nanotechnology is expected to open new avenues to fight and prevent disease using atomic scale tailoring of materials. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios and crystallographic surface structure. The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics. This has promoted research in the well known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work studies the effect of silver nanoparticles in the range of 1-100 nm on Gram-negative bacteria using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). Our results indicate that the bactericidal properties of the nanoparticles are size dependent, since the only nanoparticles that present a direct interaction with the bacteria preferentially have a diameter of approximately 1-10 nm.

Nanometre diameter fibres of polymer, produced by electrospinning

Abstract: Electrospinning uses electrical forces to produce polymer fibres with nanometre-scale diameters. Electrospinning occurs when the electrical forces at the surface of a polymer solution or melt overcome the surface tension and cause an electrically charged jet to be ejected. When the jet dries or solidifies, an electrically charged fibre remains. This charged fibre can be directed or accelerated by electrical forces and then collected in sheets or other useful geometrical forms. More than 20 polymers, including polyethylene oxide, nylon, polyimide, DNA, polyaramid, and polyaniline, have been electrospun in our laboratory. Most were spun from solution, although spinning from the melt in vacuum and air was also demonstrated. Electrospinning from polymer melts in a vacuum is advantageous because higher fields and higher temperatures can be used than in air.

A review on electrospinning design and nanofibre assemblies.

Abstract: Although there are many methods of fabricating nanofibres, electrospinning is perhaps the most versatile process. Materials such as polymer, composites, ceramic and metal nanofibres have been fabricated using electrospinning directly or through post-spinning processes. However, what makes electrospinning different from other nanofibre fabrication processes is its ability to form various fibre assemblies. This will certainly enhance the performance of products made from nanofibres and allow application specific modifications. It is therefore vital for us to understand the various parameters and processes that allow us to fabricate the desired fibre assemblies. Fibre assemblies that can be fabricated include nonwoven fibre mesh, aligned fibre mesh, patterned fibre mesh, random three-dimensional structures and sub-micron spring and convoluted fibres. Nevertheless, more studies are required to understand and precisely control the actual mechanics in the formation of various electrospun fibrous assemblies.

Size-dependent elastic properties of nanosized structural elements

Abstract: Effective stiffness properties (D) of nanosized structural elements such as plates and beams differ from those predicted by standard continuum mechanics (Dc). These differences (D-Dc)/Dc depend on the size of the structural element. A simple model is constructed to predict this size dependence of the effective properties. The important length scale in the problem is identified to be the ratio of the surface elastic modulus to the elastic modulus of the bulk. In general, the non-dimensional difference in the elastic properties from continuum predictions (D-Dc)/Dc is found to scale as αS/Eh, where α is a constant which depends on the geometry of the structural element considered, S is a surface elastic constant, E is a bulk elastic modulus and h a length defining the size of the structural element. Thus, the quantity S/E is identified as a material length scale for elasticity of nanosized structures. The model is compared with direct atomistic simulations of nanoscale structures using the embedded atom method for FCC Al and the Stillinger-Weber model of Si. Excellent agreement between the simulations and the model is found.

Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf

Abstract: The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.