bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of titanium oxide nanotubes growth through anodization in organic solvents
Authors: Lopez-Jaime K A , Peña-Ballesteros D Y , Sandoval-Amador A 
Published: November 2019

Abstract
The titanium oxide nanotubes have generated great interest in recent years because to the wide variety of applications in which they are used. The reason for this is the excellent surface properties that this material gets after of grow in the anodizing process. These properties can easily modify the electrochemical anodizing process. For this reason, we have analyzed the effect of electrolyte on the morphology and corrosion resistance of titanium oxide nanotubes grown at glycerol with 0.3% w/w ammonium fluoride and 2% v/v distilled water at 30 volts for 1 hour and ethylene glycol with 0.3% w/w ammonium fluoride and 2% v/v distilled water at 40 volts for 30 minutes. The morphology of the surfaces is observed by scanning electron microscopy. The resistance to corrosion of the samples is evaluated by potentiodynamic polarization curves in Hanks solution at 37 °C. The results of the nanotubes grew in glycerol have a length of 0.7 μm with a morphology of the bamboo type, while the nanotubes grown in ethyleneglycol they have a length of 3.3 μm and their morphology is smooth wall. Regarding the corrosion rate, it was determined that the nanotubes grown in glycerol have a higher corrosion rate. Because to these low corrosion rates it is considered that the two surfaces can be used as alternatives to modify orthopedic implant materials.
Electrochemical and bioactive evaluation of polycaprolactone/multi-walled carbon nanotubes coatings on titanium alloy
Authors: Montañez-Supelano N D , Herrera-Ardila P A , López-Lozada M J , Carreño-García H , García-Vergara S J , Estupiñan-Durán H A , Peña-Ballesteros D Y 
Published: November 2019

AbstractComposite materials of polymer – carbon nanotubes have been widely studied for biomedical applications due to the versatility of polymers in this field and the excellent mechanical, thermal and electrical properties of carbon nanotubes. However, carbon nanotubes are materials which can provide some toxicity in biological systems, since they have low solubility in water and organic solvents, tend to form aggregates in solution, are bioincompatible and limited compatibility with polymeric matrices. For this reason, carbon nanotubes considered for biomedical applications must comply with this basic requirement of solubility. To improve the compatibility of the carbon nanotubes, they were exposed to treatment with HNO3, NaOH and HCl to eliminate impurities and improve the solubility in other solvents. Polycaprolactone coatings at 2.5% w/v and multi-wall carbon nanotubes (0.5, 1.0 and 1.5 g/L) were developed to evaluate the electrochemical and bioactive properties. Techniques such as infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, electrochemical impedance spectroscopy using simulated body fluid as electrolyte and the bioactivity of human osteoseosarcoma cells (HOS ATCC® CRL-1543) by alkaline phosphatase were used. From the reported characterizations, it was observed that the resistance to polarization increases according to the degree of dispersion of carbon nanotubes present in the polymer matrix, decreasing the degradation rate of the material.
Formation of a combined bioceramics layer on titanium implants
Authors: Tsygankov P A , Skryabin A S , Krikorov A A , Chelmodeev R I , Vesnin V R , Parada-Becerra F F 
Published: November 2019

Abstract
Titanium and its alloys are currently the main materials for prosthetics, despite the fact that they, like other metals, have significant drawbacks: they cause metallosis, can provoke the formation of fibrous tissues and bone resorption in the contact zone, are toxic and, in some cases, allergenically dangerous. The noveday trend in implant technology is the prevention of direct contact of living tissues with the metal surface. For this reason, various types of protective coatings are used, usually on the base of ceramics or carbon. It is known that in the contact zone it is preferable to create a well-developed or even porous surface with osteoconductive and osseointegrative properties. This paper discusses the combined technology of modification of titanium. Implant surface treatment includes two main stages: 1) growing a porous protective layer of titanium dioxide deep into the material surface and 2) filling the pores formed on the surface of titanium dioxide with hydroxyapatite to ensure high osseointegrative properties. The formation of a layer of titanium dioxide is provided by micro arc oxidation processing with controllable density of pulsed current; then the pores are filled with crystalline hydroxyapatite by detonation spraying. The results of studying the structure and surface properties of the modified titanium samples are presented and discussed.
Fabrication of a hydrophobic smart nanocontainer with pH-sensitive surface activation for controlled release
Authors: Jimenez-Caballero M A , Nieto-Soto A M , Rios-Angarita F A 
Published: November 2019

Abstract
A hydrophobic pH sensitive nanocontainer was fabricated using smart surfaces covalently attached to a porous alumina support. The smart surface was synthesized using a mixture of aliphatic and aminated silanes and optimized to be hydrophobic at pH<7 and hydrophilic at pH<5. The hydrophobic nanocontainer thus synthesized was able to retain a cargo of the model molecule safranine at neutral pH. When pH decreased, safranine was liberated at a high rate due to the large pores of the alumina. It is expected that the nanocontainer here presented could constitute the basis of a cancer treatment as an effective drug delivery system in chemotherapy.
Obtention of a cobalt-bearing coating using spent batteries as raw materials
Authors: Villamizar E , Jiménez-Martínez J , Blanco S , Delvasto P 
Published: November 2019

Abstract
The extensive use of smartphones is increasingly generating technological waste, such as the spent lithium-ion spent batteries, which contains potentially toxic metals that may affect the environment. These metals can be recovered and used as raw material for new industrial applications, such as the production of metal coatings. In this work, a sample of spent lithiumion batteries was manually disassembled, to extract transition metal-rich cathodes. The cathodes were separated and crushed in a blade mill, to obtain a cobalt-rich concentrate powder by sieving. The powder was leached using a 1.11 M citric acid solution amended with hydrogen peroxide (1.25% volume), at 74°C under stirring at 300 rpm. The obtained polymetallic liquor was analyzed for Co, Li, Mn, and Ni, then it was submitted for electrolysis to produce metal coatings over pure copper substrates. This electrochemical electrodeposition was studied by means of cyclic voltammetry and chronoamperometry, using electrolytic Cu as a working electrode (substrate), a reference electrode Ag/AgCl and an auxiliary graphite electrode. The visual appearance of the obtained coatings was analyzed by an Olympus SZ61 stereoscope, with images at a magnification of 120x. The results showed that by applying a -950 mV vs Ag/AgCl electrodeposition potential, a homogeneous coating with good adhesion and better visual appearance was obtained. In addition, at this potential, there was little influence of the reaction of hydrogen evolution reaction during the production of the coatings.
Behavior to wear and corrosion of steel with chromium silicon nitride coatings
Authors: Villate J J , Vera E , Olaya J J 
Published: November 2019

Abstract
Chromium silicon nitride coatings were deposited via physical vapor deposition using a reactive sputtering magnetron, on steel specimens, with a chromium silicate target, purity of 99.5% and argon/nitrogen gas ratio (%) of 80/20. The coating characterization was carried out by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and nano hardness. The erosion-corrosion analysis was performed with a pin on disc tribometer, with a zircon pin, load of 1 N, applying three rotation speeds of the system (250 rpm, 400 rpm and 500 rpm) with an electrolyte composed of water, silica sand (0.05 mm, 0.1 mm and 0.15 mm) and 1% of sodium chloride. The electrochemical techniques used were resistance to polarization, electrochemical impedance spectroscopy and potentiodynamic polarization. The coating decreases the rate of substrate wear between 32% and 56%. The coefficient of friction decreases by almost 50% with the application of the film. Finally, the coating reduces by an order of magnitude the corrosion rate of steel in systems subject to wear and in 3 orders of magnitude in steel systems in static conditions, increasing the useful life of industrial facilities.
Characterization of the anticorrosive properties in bismuth-titanate films obtained by the sol-gel method
Authors: Bautista-Ruiz J , Chaparro A , Sánchez J 
Published: November 2019

Abstract
Sol-gel synthesis has been used since 1950 to prepare oxides. The method is attractive because the processes of obtaining the oxides are developed at room temperature; products with high purity and homogeneity are obtained, and allow the combination of several types of oxides: silicon, zirconium, titanium, aluminum, bismuth, and cerium. Sol-gel has been used to make ceramic composites with anticorrosive properties on stainless steel substrates. A class of stainless steel widely used in biomedical applications, especially in the treatment of fractures, 316L is its low economic cost relative to other materials such as titanium. Once the steel implant is inside the human body it comes into contact with body fluids that contain chloride ions. The fluid-implant interaction develops a corrosive process on the metal surface. The corrosive products of iron diffuse in the body causing tissue damage. As a possible solution to this problem, the objective of the investigation was to obtain a bismuth-titanium oxide using the sol-gel method and apply it on 316L stainless steel substrates. Bismuth nitrate pentahydrate and titanium tetrabutoxide were used as precursors. The anticorrosive response was evaluated in a simulated physiological solution, Ringer’s solution, by electrochemical impedance spectroscopy and potentiodynamic polarization curves. It is concluded that the coatings function as a corrosion barrier preventing the chloride ions Ringer’s solution reach the metal surface.
Characterization of bismuth-silicate soles
Authors: Bautista-Ruiz J , Chaparro A , Bautista W 
Published: November 2019

AbstractThe bismuth silicate compound was synthesized by the sol-gel method from bismuth nitrate pentahydrate and tetraethoxysilane, as precursors. The sol-gel method is attractive because the processes for obtaining oxides are developed at room temperature. In addition, it allows precise control over the composition, homogeneity, and deposition of coatings. The impact of bone-related diseases and trauma has increased significantly, in recent decades in developed and developing countries. There are materials such as bioactive glasses, especially silica compounds, which are called to play a very important role in this area, due to properties such as osteoconductivity, osteoproduction, and osteoinduction. For 20 years, the sol-gel method and the supramolecular chemistry of surfactants have been incorporated into the field of bioceramics, which allows the control, on a nanometric scale, of porosity in bioglasses. The sol-gel method has allowed obtaining bioactive materials with high surface area and high porosity. The study consisted of shaping soles by varying the molar concentrations of tetraethoxysilane and assessing the effect on aging, viscosity, determining the presence of specific functional groups and establishing the transformations that take place as a function of temperature. The results allowed characterizing each of the sol for possible application in bioglasses.
Effect of the number of layers on surface topography of bismuth-titanium coatings
Authors: Garzón P , Bautista-Ruiz J , Chaparro A 
Published: November 2019

AbstractThe objective of this research is to perform a topographic characterization by atomic force microscopy of the surface of bismuth titanate (Bi/Ti) coatings varying the number of layers deposited on the substrates, considering that there were not results of reported studies in which these precursors were used. It is important to analyze the surface behavior of these coatings as a first phase of future researches to establish the viability of possible uses and applications in biomedical industry. The films were synthesized by the sol-gel method from bismuth nitrate pentahydrate and titanium tetrabutoxide. Subsequently, by means of the spin- coating technique, the coatings were deposited on 316L stainless steel in monolayer and bi- layer, as this type of steel has been widely used for medical applications due to its good compatibility. The roughness values of each of the coatings were also determined. It is concluded that there is a relationship between the topography of the surface and the roughness values of the films with respect to the concentration of the precursors, the number and the speed of centrifugation of the layers deposited on the substrate. High concentrations of titanium tetrabutoxide effect on the good densification characteristics of the coatings.
Obtaining and characterizing of WC-Co coatings obtained from thermal spray by flame
Authors: Ferrer M , Peña G , Rodríguez L F 
Published: November 2019

Abstract
Tungsten carbide is used in the production of cutting tools for steel and as protection against wear due to its extremely high hardness. High speed oxygen fuel spraying process has been widely used to deposit WC-Co coatings. However, the decomposition and oxidation of WC-Co has been reported during the process, where carbon and tungsten are released, resulting in the formation of an amorphous matrix with the cobalt of the compound. This is attributed to the high heating and cooling rates suffered by the raw material. An alternative method is the thermal spray by flame, which allows controlling the working temperature and the residence time of the particles in the hot flame, avoiding the decomposition of tungsten carbide, on the other hand, it is a versatile and a low cost method. In this study projection parameters of a WC-18Co coating sprayed with a thermal flame spraying process from a commercial feedstock powder were determined to decide the conditions under which compact coatings are obtained with low porosity, avoiding dissociation of the tungsten carbide. The composition of the powders and substrates was determined by X-ray fluorescence microscopy and optical emission, respectively, X-ray diffraction studies were performed to characterize compositions and microstructures the coatings sprayed; the morphology was by scanning electron microscope. It was found that the best condition for this type of coatings is a neutral flame at a projection distance of 12 cm.
Coating of tricalcium phosphates by flame spray
Authors: Ferrer M , García I H , Rodríguez L F 
Published: November 2019

Abstract
The metal alloys used for prostheses with high mechanical requirements are bioinerts, it means they have low integration with bone tissue, therefore, bioactive coatings are used in order to improve this integration. Hydroxyapatite is one of the most studied materials for this application with good results, however, sometimes there are problems due to wear or tear of the coating leading prostheses loss. Tricalcium phosphate, Ca3(PO4)2, in its different phases shows osteoconductivity and higher solubility than hydroxyapatite, however, few studies have been carried out to determine its behavior as a coating for this type of applications. In this work, a study of the behavior of tricalcium phosphate as a coating on Ti6Al4V substrates obtained by flame spraying was carried out. As raw material were used tricalcium phosphate powders obtained by precipitation from calcium nitrate and ammonium phosphate dihydrogen solution, and subsequent calcination at 1,100°C. The Ca/P molar ratio obtained is 1.48 and the only present crystalline phase is beta -tricalcium phosphate. The coatings obtained have alpha tricalcium phosphate as only crystalline phase, they have compact morphology with low porosity and good wettability with the substrate, which is an index of good adhesion and good mechanical behavior. The transformation from beta- to alpha- tricalcium phosphate is product of the high temperatures used in the process, which are higher than 1,125°C where this transformation occurs.
Investigation on fired clay bricks by replacing clay with recycled glass and sludge ash
Authors: Mozo W , Cortés M , Vera E 
Published: November 2019

Abstract
Depositing the solid waste generated by wastewater treatment in landfills presents an environmental problem due to the leaching of nitrogen and subsequent eutrophication and contamination of aquafers. Glass is a material with a wide array of uses which is often disposed of after completing its use. This study evaluates an alternative to the production of bricks by replacing clay for recycled glass and sludge ash in proportions of 10% and 20%. The physical properties of the fabricated bricks (compressive strength, water absorption, and the initial rate of absorption) were then measured. The temperature used in the firing process was 950 °C. The fabricated bricks utilizing the proposed mixtures complied with the Colombian technical code for structural and non-structural brick exceeding 20 MPa. This alternative method of brick fabrication reduces the environmental impact of glass and solid waste on the ecosystem and reduce freshwater contamination. It will also solve the issue of the sludge waste produced by wastewater treatment plants.
Structural and magnetic in c-AlN and c-GaN compound doped with Ti
Authors: Espitia Rico M J , Sánchez P L C , Salcedo Parra O 
Published: November 2019

Abstract
We report the results of a study with Ti-doped AlN and GaN in the cubic-zincblende phase of the Al0.9375Ti0.0625N and Ga0.9375Ti0.0625N concentrations. All calculations were carried out using the Quantum ESPRESSO code through the pseudopotential method within the framework of density functional theory. The structural results show that the lattice constants of the Al0.9375Ti0.0625N and Ga0.9375Ti0.0625N compounds do not change compared to pure forms of c-AlN and c-GaN, yet the bond length of Ti-N increases compared to the bond length of Ga-N in pure c-AlN and c-GN. The electronic analyses reveal that both the Al0.9375Ti0.0625N and Ga0.9375Ti0.0625N compounds are ferromagnetic. The Al0.9375Ti0.0625N compound exhibits a metallic behavior with a total magnetic moment of 0.85 μ
β
/cell, whereas Ga0.9375Ti0.0625N exhibits a halfmetallic character with a magnetic moment of 1.0 μ
β
/cell. The magnetic effect in the Al0.9375Ti0.0625N and Ga0.9375Ti0.0625N compounds is the result of a strong hybridization between Ti-3d and N-2p. It is concluded that the Ga0.9375Ti0.0625N compound is a suitable candidate for a diluted magnetic semiconductor with potential use in applications such as spintronics, spin injection or magnetic memories.
Ab initio invesgations of the electronic and magnetic behavior of 1x1-MnN/GaN superlattice under hydrostatic pressure
Authors: Espitia Rico M J , Ortega López C , Salcedo Parra O 
Published: November 2019

Abstract
In this paper, Ab-initio calculations are reported on the electronic and magnetic behavior of a 1x1-MnN/GaN superlattice in the wurtzite structure under hydrostatic pressure. The calculations were performed using the formalism of density functional theory with the generalized gradient approximations in the Perdew, Burke and Ernzerhof model, as well as the Wien2k computational package. The density of state shows that the electronic structure and the magnetic moment are affected by the hydrostatic pressure, because there is an abrupt change in the magnetic moment, which goes from 0 to 2.86 μβ/cell under a pressure of ∼ 24.45 GPa. When the pressure decreases to 0 GPa, the magnetic moment of the superlattice rises to 4.0 μβ/cell. Therefore, the superlattice exhibits a half-metallic behavior for a pressure of 0 GPa, while it acquires a metallic behavior when pressure surpasses 24.45 GPa.
Iron slag as fine aggregate replacement and nanosilica particles in self-compacting concrete mixtures
Authors: Mantilla Díaz M F , Villamizar Pabón J A , Ruiz Martínez S , Zapata Orduz L E 
Published: November 2019

Abstract
A study of the mechanical behavior of self-compacting concrete mixtures under sand replacement (as fine aggregate) by iron slag (residue from industrial machining) from 0.0% to 50.0% of mass, variations of water/cementitious material ratio between 0.3 and 0.5 and nano SiO2 incorporation between 0.0% and 2.0% by mass of cementitious materials is presented. Fresh state tests of slump flow were performed, and the main rheological parameters: static yield stress and plastic viscosity were determined from a rheometer. For the hardened state, compressive strength tests were performed. The study of iron slag incorporation and water/cementitious materials ratio variation was developed based on a statistical methodology of central composite design from axial points based on a 2k factorial with central points, besides a posterior analysis of variance and Tukey’s multiple comparison tests. The optimization of these variables was developed using response surface methodology on 7 days compressive strength results, from the statistical design, besides the posterior determination of nano SiO2 effects on the optimized proportions. Among the most relevant results regarding the presence of iron slag, an increase in the early age compressive strength was found, with the optimized mixture strength being more than 100% higher than mixtures without iron slag at 7 days of curing. Regarding the effect of nano SiO2 addition to the optimized mixture, a detriment of the rheological parameters and a consequent reduction of the workability were the most remarkable findings. With the obtained results, iron slag proves to be a feasible sand replacement in self-compacting concrete mixtures.
Blast furnace dust: An alternative for the improvement of granular material for pavements
Authors: Ochoa Díaz R , Romero Farfan M 
Published: November 2019

Abstract
The boom in the construction of infrastructure works has encouraged the demand for materials such as steel and natural aggregates, which in turn has generated an increase in the exploitation of materials and the generation of residual iron and steel. This situation has caused double the environmental impact due to the accumulation of these residual materials and the indiscriminate exploitation of non-renewable natural resources. This study was carried out with the aim of analyzing the possibility of using blast furnace dust to improve the properties of granular materials used in the construction of roads, as an alternative to mitigate the environmental problems caused by poor disposal and accumulation of this waste, affecting the areas of influence of these companies. To achieve this objective the physical and chemical properties of fine blast furnace dust was determined and mixtures of materials with a granular base with 0, 2, 4, 6, 8, and 10 percent blast furnace dust were analyzed to find the properties of resistance (California Bearing Ratio and resilient module), plasticity and expansion in the presence of water. The results of this study indicate that blast furnace dust can be used to improve some properties of natural aggregates for use in road construction.