A magnetic resonance compatible surgical manipulator: part of a unified support system for the diagnosis and treatment of heart disease

A prototype of a magnetic resonance (MR)-compatible surgical manipulator was designed and evaluated. The manipulator is designed so as to fit into vertical magnetic field open-configuration MR imagers. Moreover, it is designed to work without being fixed to an MR imager, and its electrical circuits and lines of actuators and sensors are independent of the room shield so that it could be installed in various kinds of settings at many MR imager sites without any additional construction. The MR compatibility of the manipulator was evaluated: no noticeable deformation was observed in the MR images even when the manipulator was in motion. Although the signal-to-noise deterioration ratio was higher than that previously reported, the MR images were thought to be good enough for recognizing the whole structure of a targeted organ and for following the relative position of the manipulator tip with regard to the target, i.e. MR tracking.     

New structure of automatic torch and new approach for controlling drop transfer in rotating spray welding arc

Abstract

Using computer aided design/computer aided manufacturing technology, an automatic welding system is designed and manufactured for high current, high speed, and high deposition metal arc active gas (MAG) welding. The welding torch structure is evaluated and optimised via the finite element method and practical welding technology experiments. Finally, the process of high deposition MAG welding is investigated, and it is highlighted that on application of a longitudinal magnetic field to the high deposition MAG welding process, a steady metal transfer and drop deposition condition can be achieved, which is suited to the demands of high current, high speed welding technology.     

MagneSil™ Paramagnetic Particles: Magnetics for DNA Purification

MagneSil™ Paramagnetic Particles are silica-paramagnetic particles with an affinity for nucleic acids under defined conditions. Particle structure and solution composition can be altered to selectively adsorb nucleic acids based upon type and size. These properties have been used to develop purification methods based on a three-step bind, wash, and elute process. The MagneSil™ technology is readily adaptable to robotic platforms, allowing complete automation of the purification process in either 96- or 384- well plate formats. This article introduces the basic physical and performance characteristics of the MagneSil™ Paramagnetic Particles.     

Mushy zone coarsening with fluid flow

Abstract

Cylindrical samples of a near-eutectic AlCu30 alloy are annealed applying constant axial temperature gradients to directionally molten samples in an aerogel furnace. During annealing with various times and gradients also a rotating magnetic field (RMF) of 6 mT was applied leading to azimuthal and meridional flows of well known magnitude. The specific surface area of the primary phase was measured on metallographic in section perpendicular to the sample axis with a fixed amount of fraction solid. The specific surface area varies as the inverse cube root of annealing time if no RMF is applied, but varies as an inverse forth root at 6 mT. The experimental procedure and results are presented in detail and compared to isothermal coarsening measurements of Voorhees and co-workers.     

Investigation of pitting potential of carbon steel using experimental design method

Abstract

The dependence of the pitting potential E_p of 1018 carbon steel on chloride concentration, pH and the temperature of the solution was studied by the potentiodynamic method in accordance with a statistical experimental design. The parameters of the empirical pitting potential model determined on the basis of Box-W ilson ex perimental design method were evaluated using the experimental data. Comparison of the predicted values from the model with the observed values showed that the model is a good fit. From the model equation the most noble pitting potential value of -225 mV (SCE) was obtained when the Cl^- ion concentration, temperature and pH of the solution were 205 ppm, 25°C, and 6·4, respectively. The Box-Wilson experimental design technique was proved to be applicable in modelling the pitting potential of carbon steel.     

Electrical and thermal properties of carbon nanotubes/PMMA composites induced by low magnetic fields

Abstract

Ni particles supported on carbon nanotubes (CNTs) were dispersed in a polymethyl methacrylate (PMMA) matrix by solution blending and then cast onto an electrode to get composite films under low magnetic fields. The orientation of CNTs in the films was characterised by scanning electron microscope and optical microscope. Multimeter and high resistance meter were used to study the electrical behaviour of the nanocomposites. The glass transition temperature T _g of PMMA was determined by differential scanning calorimetry. The results show that the alignment of the CNTs dispersed in the PMMA was achieved under a low magnetic strength below 0·5 T. Because of the ferromagnetism of Ni particles, the magnetic alignment of CNTs susceptibly changed. The magnetic alignment units in this work were rod-like CNTs aggregates instead of single CNTs, which took part in the buildup of a specific CNTs network structure in PMMA matrix. The network structure played a key role in significantly improving electrical conductivity and T _g of the nanocomposites.     

Microbial Corrosion Hazard in Fuel Storage Tanks in the Presence of Corrosion Inhibitors

Abstract

Tests were carried out in five light fuel oil storage tanks placed outdoors in the vicinity of Stockholm, Sweden, to study the effectiveness of some commercially available corrosion inhibitors in the presence of certain micro-organisms. Corrosion in the aqueous phase caused by Desulphovibrio desulphuricans, Thiobacillus ferro-oxidans and Cladosporium resinae was effectively stopped by the addition of a sodium nitrite-sodium tetraborate mixture, but was enhanced by each of three commercial oil-soluble inhibitors. In some cases the corrosion rate exceeded 3 mm/year. The results are of a preliminary nature, but give cause for alarm and suggest the need for further investigation.     

Application of bainite transformation model to estimation of processing window boundaries for Mn-Mo-Cu austempered ductile iron

Abstract

The processing window enables the heat treater to produce an austempered ductile iron that satisfies the ASTM standard A897M:1990. The aim of the present study is to determine whether a bainite transformation model developed for steels is applicable for calculating the extent of the processing window for an austempered ductile iron ADI of composition wt- Fe-3.55C-2.72Si-0.25Mn-0.25Mo-0.25Cu-0.04Mg. The bainitic model is calibrated for the start of the processing window, according to an autocatalysis factor that describes the extent to which the formation of one plate of ferrite activates others. The time interval between the beginning and the end of the processing window is used for estimation of the end of the processing window. Experimental data sourced from the literature for the ADI are used to calibrate the model, and it is shown that the bainitic model is applicable for calculation of the processing window. Further upgrading of the model is required for its application to ADIS of various compositions.     

Iron–manganese: new class of metallic degradable biomaterials prepared by powder metallurgy

Abstract

An Fe–35 wt-%Mn alloy, aimed to be used as a metallic degradable biomaterial for stent applications, was prepared via a powder metallurgy route. The effects of processing conditions on the microstructure, mechanical properties, magnetic susceptibility and corrosion behaviour were investigated and the results were compared to those of the SS316L alloy, a gold standard for stent applications. The Fe35Mn alloy was found to be essentially austenitic with fine MnO particles aligned along the rolling direction. The alloy is ductile with a strength approaching that of wrought SS316L. It exhibits antiferromagnetic behaviour and its magnetic susceptibility is not altered by plastic deformation, providing an excellent MRI compatibility. Its corrosion rate was evaluated in a modified Hank's solution, and found superior to that of pure iron (slow in vivo degradation rate). In conclusion, the mechanical, magnetic and corrosion characteristics of the Fe35Mn alloy are considered suitable for further development of a new class of degradable metallic biomaterials.     

Influence of static magnetic fields on the protective ability of phosphate coatings on aluminium alloys

Abstract

Phosphate coatings on aluminium are used to improve the corrosion resistance of aluminium before the latter is painted. Phosphate coatings deposited in phosphate solution treated with a magnetic field prior to deposition can take on new properties. A magnetic field can either improve or deteriorate the properties of the phosphate coating formed, depending on the composition of aluminium.