Additive manufacturing of patient-specific tubular continuum manipulators

Tubular continuum robots, which are composed of multiple concentric, precurved, elastic tubes, provide more dexterity than traditional surgical instruments at the same diameter. The tubes can be precurved such that the resulting manipulator fulfills surgical task requirements. Up to now the only material used for the component tubes of those manipulators is NiTi, a superelastic shape-memory alloy of nickel and titan. NiTi is a cost-intensive material and fabrication processes are complex, requiring (proprietary) technology, e.g. for shape setting. In this paper, we evaluate component tubes made of 3 different thermoplastic materials (PLA, PCL and nylon) using fused filament fabrication technology (3D printing). This enables quick and cost-effective production of custom, patient-specific continuum manipulators, produced on site on demand. Stress-strain and deformation characteristics are evaluated experimentally for 16 fabricated tubes of each thermoplastic with diameters and shapes equivalent to those of NiTi tubes. Tubes made of PCL and nylon exhibit properties comparable to those made of NiTi. We further demonstrate a tubular continuum manipulator composed of 3 nylon tubes in a transnasal, transsphenoidal skull base surgery scenario in vitro. © 2015 SPIE

Thermodynamics of a Karatau and Aktobe phosphorites mixture interaction when producing phosphorus, calcium carbide and ferrosilicon

Relevance. Associated with the need to increase the level of comprehensive use of phosphorites during their electrothermal processing and to reduce the amount of slag waste generated during the production of phosphorus and polluting the environment. Aim. To conduct computer thermodynamic modeling of the effect of temperature and amount of iron on technological parameters of interaction of a Karatau and Aktobe phosphorites mixture with carbon and iron to produce phosphorus, calcium carbide and ferrosilicon. Objects. Phosphorites of the Karatau and Aktobe phosphorite-bearing basins. Methods. Thermodynamic computer modeling using the HSC Chemistry 6.0 software; rotatable second-order experiment planning technique; geometric optimization of technological parameters. Results. It has been established that depending on temperature in a mixture of Karatau and Aktobe phosphorites with carbon and iron, they participate in interaction:  CaSiO3, SiO2, Si, SiC, SiO(g), MgSiO3, Al2SiO5, Na2SiO3 , Ca(g), CaO, CaC2, CaF2, CaS, Fe, FeSi, FeSiO3, FeP, Fe2P, Fe3P, FeP2, FeO, Fe3Si; Ca3(PO4)2, P2(g), P4(g). An increase in iron amount leads to an increase in the degree of silicon extraction into the alloy, and at 2000 °C reduces the extraction degree of calcium in CaC2 and the silicon concentration in the alloy. Branded calcium carbide with a volume of more than 230 dm3/kg and ferrosilicon FeSi25 are formed from a mixture of phosphorites, carbon and iron at 2077...2088 °C in the presence of 20...21.4 % iron and 43 % carbon (in this case, phosphorus is completely distilled off into the gas phase). Using our proposed method of electric smelting of phosphorites with phosphorus distillation and associated production of ferroalloy, in comparison with the traditional method, the indicator of integrated use of raw materials increases from 43.9 to 62.7...73.6 %, that is 1.43...1 ,67 times. The proposed processing technology helps to increase active reserves of phosphorites and bring low-grade phosphorites of the Aktobe basin into production

Complex electrothermal processing of an oxide zinc-containing ore of the Shaymerden deposit

Oxide ores are potential world raw materials sources of zinc manufacture. Despite a sufficiently high extraction level of zinc and lead known pyrometallurgical methods are characterized by formation of large quantity of industrial wastes therefore a complex use level of these raw materials is low. Hydrometallurgical methods are mainly applied for extraction of nonferrous metals. The present article contains the research results of complex processing an oxide ore of the Shaymerden deposit (Kazakhstan), consisting in the simultaneous production of a ferroalloy, calcium carbide and zinc sublimates from the ore in a thermal-ore arc electric furnace. The researches have been carried out with use of a HSC 5.1 software package (based on a principle of Gibbs energy minimum) and electrical smelting the ore in a monoelectrode arc electric controlled-output furnace. It was found, that in equilibrium conditions in a system ore-carbon-iron gaseous zinc is formed at Т > 1073 K, FeSi at Т > 1573 K, CaC2 at Т > 2073 K, Si at Т > 1673 K. The electrosmelting of ore in an arc furnace using of 38.7-40% coke and 16-28.4% steel cuttings the conversion degree of silicon into an alloy is 75-77%, calcium to calcium carbide 77-81%, zinc to sublimates 99.3%. The ferroalloy obtained contains 19.6-41.3% of silicon, the calcium carbide is characterized by capacity of 110-250 m3/kg, and the zinc sublimates contain 66-67% of zinc. The -suggested method allows to increase the combined usage of the ore from 35.6 to 89.6%