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Surface modification with ions

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Miryam Rincón-Joya
added 2 research items
Copper oxide (CuO) has been broadly used in different technological and biological applications. However, based on the literature review, there are few reports describing the synthesis of tungsten doped copper oxide and its biological applications, although CuO and W (tungsten) based nanomaterials have been reportedly already synthesized. In this study we synthesized novel CuO and CuO/W (at.1%, 2% and 4%) nanoparticles and explored their tungsten content-dependent bactericide activity. In order to obtain the materials, was used a co-precipitation method which is of low cost. The synthesized materials were characterized by x-ray diffraction (XRD); XRD results indicated that only the sample with at.1% of W presented pure Tenorite phase. Diffuse reflectance spectroscopy (DRS) allowed to obtain the band gap energy values; CuO/W (at.2%) sample exhibited the minimum value of 2.62 eV. Grains sizes ranging from 39.78 to 53.47 nm were established through field emission-scanning electronic microscopy (FE-SEM), and these sizes were confirmed by transmission electron microscopy (TEM). Doping with W also influenced the morphology obtained in all cases. BET (Brunauer, Emmett, Teller) analysis allowed to establish an increase in specific surface area and pore size with W doping. The particle size was determined by dynamic light scattering (DLS). The bactericidal properties were tested using well diffusion method for Escherichia coli and Staphylococcus aureus bacteria. Bactericide response of CuO nanoparticles was improved by the inclusion of W dopant into the CuO structure, leading to an expansion in the inhibition zone for the CuO/W (at.1%) sample; inhibition halo diameters were 1.5 and 12 mm for CuO and CuO/W (at.1%), respectively. Hence, it was possible to infer the remarkable importance of the crystalline phase, morphology, particle size and specific superficial area of the CuO/W (at.1%) nanoparticles in its bactericide performance. WO3 secondary phase affected the bactericide response of the materials obtained at at.2% and at.4% of tungsten content.
Ely Dannier V. Niño
added a research item
The hybrid method of three-dimensional ion implantation and electric arc is presented as a novel plasma-ion technique that allows by means of high voltage pulsed and electric arc discharges, the bombardment of non-metallic and metallic ions then implanting upon the surface of a solid surface, especially out of metallic nature. In this study AISI/SAE 4140 samples, a tool type steel broadly used in the industry due to its acceptable physicochemical properties, were metallographically prepared then surface modified by implanting titanium and simultaneously titanium and nitrogen particles during 5 min and 10 min. The effect of the ion implantation technique over the substrate surface was analysed by characterization and electrochemical techniques. From the results, the formation of Ti micro-droplets upon the surface after the implantation treatment were observed by micrographs obtained by scanning electron microscopy. The presence of doping particles on the implanted substrates were detected by elemental analysis. The linear polarization resistance, potentiodynamic polarization and total porosity analysis demonstrated that the samples whose implantation treatment with Ti ions for 10 min, offer a better protection against the corrosion compared with non-implanted substrates and implanted at the different conditions in this study.
Jose Jose Barba Ortega
added 4 research items
The Ginzburg-Landau theory, applied to superconducting materials is based on thermo-magneto-electro-dynamic concepts as phase transitions that enrich the class on this subject. Thus, in this contribution we expose the Ginzburg-Landau time-dependent equations, show the mathematical form for two nano-scale superconducting systems, one bi-dimensional homogeneous al sample with applied external current at zero magnetic field, and one three-dimensional cube in presence of a tilted magnetic fiel at zero applied current. This analysis shows the applicability of the three and two-dimensional model to superconductors. The conveniently Ginzburg-Landau theory show that the magnetic response behavior of the sample is very useful for applications in fluxtronica, SQUIDS design, magnetic resonance, among others.
We study the superconducting state of a thin film at zero external applied magnetic field under a transport electric current, J a . By taking into account the roughness percentage of its surface R, we show that the value of J a =J c1 at which the first vortex-antivortex (V-Av) pair penetrates the sample, the superconducting-normal transition current J a =J c2 , as well as their average velocities and dynamics, strongly depend on the R values. It will be shown that J c1 and J c2 follows a scaling law for different values of R. Our investigation was carried out by numerically solving the two-dimensional generalized time-dependent Ginzburg-Landau equations.
We consider a mesoscopic superconducting three-dimensional cube immersed in a tilted magnetic field H oriented along an angle θ with respect to the z-axis, in the xz plane. The sample is in contact with a metallic material or with another superconductor in the xz and yz planes, while the z=0 plane remains in contact with a dielectric material. These boundary conditions are simulated by the de Gennes extrapolation length b. We analyzed the magnetic induction, the superconducting electron density, and the magnetization curves as functions of H for different values of b on the lateral surfaces of the sample. We show that the magnetization and the vortex configuration depend on θ and b. An analytical linear and exponential dependence of the maximum of the magnetization on θ and b, respectively, was found.
Luis Armando Hernandez Molina
added a research item
T he three-Dimensional Ion Implantation technique (3DII) causes ions to collide with a solid surface in a perpendicular way regardless of the geometry of the solid (Khvesyuk & Tsygankov, 1997; Dougar-Jabon, Dulce-Moreno & Tsygankov, 2002). The steel AISI SAE 4140 has been used as substrate because of its wide use in the transport of oil industry, the specimens of steel underwent surface modification with Titanium ions (Ti) and the combined ions of titanium and nitrogen (Ti+N), with an energy of 10keV for 5min and 10min. The superficially modified and unmodified specimens were characterized by Electrochemical Impedance Spectroscopy (EIS), noting among the most outstanding results the electrochemical double layer system capacitive characteristics under all tested conditions, the best corrosion performance was obtained for implanted substrates with Ti ions for 10min, having a charge transfer resistance much higher than those implanted with Ti+N and the non-implanted. Additionally, it was determined that all the implanted systems can be simulated by using one equivalent circuit with a constant phase element instead of a capacitor and the non implanted substrate from day 15 can be simulated through another equivalent circuit.