The rod-shaped plant virus tobacco mosaic virus (TMV) is widely used as a nano-fabrication template, and chimeric peptide expression on its major coat protein has extended its potential applications. Here we describe a simple bacterial expression system for production and rapid purification of recombinant chimeric TMV coat protein carrying C-terminal peptide tags. These proteins do not bind TMV RNA or form disks at pH 7. However, they retain the ability to self-assemble into virus-like arrays at acidic pH. C-terminal peptide tags in such arrays are exposed on the protein surface, allowing interaction with target species. We have utilized a C-terminal His-tag to create virus coat protein-templated nano-rods able to bind gold nanoparticles uniformly. These can be transformed into gold nano-wires by deposition of additional gold atoms from solution, followed by thermal annealing. The resistivity of a typical annealed wire created by this approach is significantly less than values reported for other nano-wires made using different bio-templates. This expression construct is therefore a useful additional tool for the creation of chimeric TMV-like nano-rods for bio-templating.
The electrical transport and structural properties of tobacco mosaic virus (TMV)-based nanostructures have been studied. Electroless deposition was used to coat the TMV outer surface with a 13 nm thick homogeneous Pt layer. SEM, TEM and electrical characterization of the obtained nanostructures has been performed. Using four independently controlled scanning tunnelling microscope tips we were able to perform four-point probe resistance measurements on linear virus assemblies and demonstrate the continuous nature of the metallic coating. The measured resistivity values of the virial nanowires exceeded the bulk value by 10-100 times; notwithstanding this the coated structure allowed high current densities, of the order of 10(5)-10(8) A cm(-2). The four-probe technique proved to be useful for analysing the electrical properties of bio-inorganic nanowires.
Electric arc furnace dust (EAFD) is a major issue for processing technologies: Several million tons per year are generated, it contains both valuable and hazardous metals and yet no available treatment process has proven to be superior to all others. Processes currently applied or being developed are either of hydro- or pyrometallurgical type, which are very costly. In the paper testing of some physical separation methods of electric arc furnace dust from Polish steel industry were investigated. SEM, EDX analyses as well as grain size observations of dust particles were additionally performed. All investigations confirmed a possibility of effective magnetic and mechanical separation of EAFD particles.
This work reports on deposition of transparent semi-insulating tin oxide thin films deposited by spray-pyrolysis over large area glass substrates. The precursors used are based on diluted chloride solutions. Bi-doped high resistivity tin oxide thin films are required in the fabrication process of an analog grey scale ferroelectric liquid crystal matrix display. Various parameters have been optimized in order to achieve good reproducibility and uniformity of the electrical and optical properties. Deposition temperature and the properties of the glass substrates have been found as the most critical variables which affect the deposition rate and the quality of the deposited films. The different substrates used, borosilicates and soda-lime glasses, lead to different electrical properties. A further investigation on the stability of the film properties versus different kind of aging procedures have been conducted. Preliminary results of the operation of the complete display making use of our films are shown.
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