bluuebunny/crossref_metadata_2025 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

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

Composite 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

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

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

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

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

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

The 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

The 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

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

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

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

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

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

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

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.
Removal of dyes from aqueous solutions by adsorbent prepared from coffee residues
Authors: López L , Ramirez A P , Giraldo S , Flórez E , Acelas N Y
Published: November 2019

This study reports the production of an adsorbent material derived from extracted coffee residues using phosphoric acid and zinc chloride as activating agents. The structural features of the materials were characterized using different analytical techniques. The BET surface areas were found between 3.81 m2.g−1 y 176.27 m2.g−1, while the FTIR analysis showed the formation of oxygenated functional groups, which are active in the adsorption process. These materials were evaluated as adsorbents for the removal of methylene blue from aqueous solution. Batch adsorption tests were performed at room temperature and the effects of contact time and, initial dye concentration was investigated. The equilibrium adsorption results were complied with Langmuir isotherm model and its maximum monolayer adsorption capacity was 15.92 mg.g−1. Adsorption kinetics studies indicated that the pseudo second order model yielded the best fit for the kinetic data. This typical dependence of methylene blue uptake on kinetic studies indicated the adsorption process to be both chemisorption and diffusion controlled. The experimental data obtained in the present study indicate that coffee residues are suitable candidates for use as adsorbents in the removal of cationic dyes.
Synthesis and characterization of a derivative of carbazole obtained from bromobenzyl alcohol
Authors: Cantillo R , Percino J , Murillo E A
Published: November 2019

Carbazole and their derivatives are compounds that have a great importance in the industry because their potential applications in solid-state lighting technologies. These materials have photorefractive and photoconductive properties, it is charge transporter (hole) and it is employed in organic light emission diodes. Therefore, with the aim of to contribute in the art state of this type of materials was done the synthesis of a carbazole-based material, from carbazole and bromobenzyl alcohol, employing as catalyzer sodium hydroxide and as solvent sulfoxide dimethyl. The material obtained was characterized by hydroxyl value, infrared analysis, nuclear magnetic resonance, thermogravimetric, X ray diffraction and ultraviolet- visible analyses. By infrared and proton nuclear magnetic resonance analyses was evidenced the formation of the carbazole-based material. The carbazole-based material presented fluorescent properties, since when was taken to ultraviolet lamp, this material emitted light. The thermal stability exhibited by this material may facilitate its use under conditions of high temperature. The results obtained in this study are very important since so many fluorescent materials such as organic light emission diodes are doing imported in Colombia. Therefore, the carbazole-based material may be an alternative for substitution of importations of this type of materials.
Removal of cadmium in wastewater through geopolymeric materials based on pumice.
Authors: Grillo J , Montaño A M , González C P , Barón G C
Published: November 2019

Heavy metal pollution in the effluent water due to industrial waste product of various economic activities is not adequately regulated in Colombia, this is because the agencies do little control track discharge and easily granting environmental licenses. As a result of this little regulation currently they do not have updated figures that provide real information on the amount of waste that ends up in the resort, causing health effects of living beings. In the tanning industry, in particular, there cadmium residual concentration higher than the maximum allowed by the Ministry of the environment. This work considers the use of a geopolymeric material based on pumice stone, to capture cadmium ions present in wastewater and thus reduce its concentration in the water resource in order to reduce the population’s exposure to diseases that are associated with accumulation of cadmium in the body. The synthesis of geopolymer began from the alkaline activation of pumice stone with commercial sodium silicate, the use of sand:pumice stone in a 1:1 ratio and 31 hours of reaction, these proportions were defined in a previously work by the authors. The morphological and crystallographic characterization of the sorbent geopolymeric material was performed by scanning electron microscopy and X-ray diffraction. To assess the sorption process, a study of the geopolymer’s contact time with a known solution of cadmium was performed. Cadmium concentration was determined using atomic absorption spectroscopy and the geopolymer was characterized after removal.
Carbon structures obtained from acetylene in a continuous current abnormal glow
Authors: Alvarez B , Sarmiento-Santos A , Hernández Y
Published: November 2019

Carbon is the great constituent of all organic matter and a key element of the compounds that make up the enormous and very complex discipline of organic chemistry. It was already known in antiquity to be obtained as a by-product of the incomplete combustion of organic materials. At present the properties of this atom constitutes a potential source for research due to its promising application in nanotechnology and new materials because of its unique mechanical, electrical and optical properties. Carbon has several structural configurations that are known as allotropes, these allotropes have the same basic component, but its molecular conformation is different. Other elements of the fourth column of the periodic table such as silicon, germanium and tin have characteristics similar to those of carbon, however, this is unique in the variety of its allotropes. The different allotropes of carbon can be produced, among other methods, by the chemical vapor deposition method, however, the energy cost of this type of growth is relatively high. Another technique that would allow to obtain deposits of carbon in the laboratory is the plasma of the glow discharge of direct current in abnormal regime, which also offers a wide range of applications in plasmo-chemistry and in the thermochemical treatment of materials. The application of the abnormal glow discharge in the deposition of synthetic materials is a recent technique that represents a decrease in the time and in the energy consumption of the process, because the heating is carried out directly by the bombardment of the ions and neutral atoms on the surface of the cathode where the sample is usually located. The technique of abnormal glow discharge was used in this work with the objective of studying the possibility of formation of carbon deposits, in a copper substrate, from an atmosphere of argon, hydrogen and acetylene. Thus, in the temperature of 600 °C, deposits of graphite, graphene and an acetylene polymer compound were obtained. These were identified by infra-red spectrometry and Raman spectrometry.
Synthesis of oxygenated compounds from methane, carbon dioxide and water in liquid phase using a plasma-catalytic system
Authors: Gelves J F , Dorkis L , Marquez M , Fourré E , Batiot-Dupeyrat C
Published: November 2019

Direct synthesis of methanol and other oxygenated compounds (ethanol, propanol, acetaldehyde, formic acid, acetic acid and propanoic acid) was carried out through the partial oxidation of methane process using carbon dioxide (greenhouse gas) and water in liquid phase (water has only been used in the form of steam). The activation process was carried out with dielectric barrier discharge plasma (sinusoidal power) and in the presence of a catalyst. A Colombian natural zeolite, glass wool and a material composed of magnesium oxide and alumina were used in this scientific investigation as catalysts. Tests in the presence/absence of catalyst, presence/absence of liquid water and combinations of the previous tests were carried out in order to establish which conditions allow to obtain the highest conversion of reagents and selectivity to oxygenated compounds. It was evidenced that the glass wool allows to obtain the highest levels of reagent conversion, followed by the magnesium catalyst and finally the natural zeolite. Regarding selectivity, the natural zeolite showed to be efficient for the obtaining of oxygenated compounds. It was also established that the presence of liquid water in the reactor decreases the conversion of the reactants, but favors the formation of carbon monoxide, hydrogen and especially oxygenated compounds.
Mechanical characterization of the rachis fiber obtained from the African palm elaeis guineensis
Authors: Apoveda L C , Bohórquez O , González- Estrada O A , Pertuz A , Rueda Y
Published: November 2019

In the present work, experimental tests are carried out to determine the tensile strength of the fiber obtained from the African palm clusters. The tests were performed on a MTS BIONIX universal test machine under the ASTM standard, which characterizes the tensile strength and stiffness of the fiber in relation to its weight. Once the mechanical properties of the fiber are characterized, it is proposed to carry out studies as a reinforcement material in composite materials, reducing the amount of waste which generates health problems in this industry. Organic fibers have mechanical properties such as lightness, high mechanical strength and durability, for these reasons it has been used as a reinforcing element in polymeric matrices, being a potential replacement for some materials in the industry in general. By 2015, Colombia had 466000 hectares of African palm planted, highlighting the potential for acquiring this fiber in Colombia, to achieve positive results in the application of the fiber, a whole series of new industrial products can be developed with the social and economic impact that this represents.
Influence of mechanical milling on the hydrogen absorption properties of TiCrV – based alloys
Authors: Martinez-Amariz A , Peña Ballesteros D
Published: November 2019

The hydrogen economy is a concept focused on this element as a carrier of clean and cheap energy, one of the keys is the storage of this gas safely. In this sense, TiCrV-based alloys have great capacity to store hydrogen. In the present working studied the influence of the process of mechanical milling of high energy in the storage capacity of hydrogen of TiCr1.1 V0.9 alloy. The alloy was synthesized by arc fusion and manually crushed. The effects of mechanical milling were studied for periods of time of 1 hour and 3 hours at 300 revolutions per minute with a weight/weight ratio of the sample 10: 1. The x-ray diffraction analyzes revealed solid phase formation of body center cubic phase, characteristic of TiCrV base alloys, and formation of TiCr1.8H5.3 hydrides and TiH2 hydrides with orthorhombic structure and body center cubic, respectively. The hydrogen storage capacity of the TiCr1.1 V0.9 alloy decreased with the increase in grinding time. The reasons for the drop in hydrogen storage capacity are mainly two: contamination of the surface of the alloy powder and changes in the microstructure generated by the plastic deformation in the grinding process. However, an increase in absorption kinetics was observed at longer milling times because the surface area increases since the crystallite size decreases. This phenomenon can be explained by the catalytic effect produced by the decrease in the particle size of the samples. The differential scanning calorimetry analysis was able to determine that the TiCr1.8H5.3 hydride stored a greater amount of hydrogen and has a lower desorption temperature compared to the TiH2 hydride.
Analysis of the behavior of Tunja diatoms, before dispersive effect, acidity and suction
Authors: Jiménez O J , Abril W F
Published: November 2019

The present article analyzes some physical and chemical properties, which can influence the behavior of the diatoms present in the eastern part of the city of Tunja, by identifying and exploring three outcrops arranged in the territory, three characteristics to be evaluated and defined their respective laboratory tests were carried out in order to be able to estimate their behavior, analyzing parameters such as the dispersive effect using the pinhole test, acidity with hydrogen potential measurement and suction using the filter paper method. Prior to this, general characterization tests were developed, that is: Atterberg limits, specific gravity and hydrometer granulometry, carried out according to the respective regulations, the analysis of the results obtained and the pertinent recommendations are made in a particular way for each outcrop and in general form for the deposit of the city, defining the predominant values of the characteristics considered.
Localized states induced by variations in the curvature of the path of an electron in a closed nanoscopic loop
Authors: Torres J F , Morales N L , Espitia J S , Páez C J , Gutiérrez W
Published: November 2019

We analyzed the effect of the curvature of the path on the energy spectrum of an electron confined in a closed nanoscopic loop in the presence of magnetic and electric external fields has been studied. The system was modeled using the stationary Schrödinger equation in the framework of the approximation of effective mass and enveloping function, which was solved using the finite element method. The closed loop has been modeled theoretically as a flat waveguide, whose width is small compared to the length of the path. These geometries allowed putting in evidence the variation in the confinement potential of the electron due to changes in the curvature. The variation of the electronic spectrum and the electronic densities for some low-lying energy states were analyzed as a function of the intensity of a magnetic field applied in the direction of growth and an electric field applied in the structural plane. The results demonstrate, with clarity, the high sensitivity of the electronic spectrum of a closed nanoscopic loop in the presence of changes in the curvature of the path, which translates into high sensitivity in electronic, magnetic and optical properties.
Biofertilizing potential of a fertilizer based on cienego and native microorganisms in corn seeds
Authors: Diaz C E , Daza D , Arámbula C I
Published: November 2019

In the development of the productive process of stone aggregates, during the stage of washing and extraction of sludge from the decanter wells, a “cienego” sand is produced in an approximate quantity of 24.75 tons per day, of which only 10% per day is commercialized, the remaining 90% must be discarded, causing financial detriment, impact on the environment in terms of pollution by handling the product that is discarded, occupation of useful areas and landscape degradation, among other impacts negatively affecting the companies in the sector, and their environment. The objective of this research was to evaluate a fertilizer based on cienego and three native microorganisms (Azotobacter sp, 1 Azotobacter sp, 2 and Pseudomonas sp) in corn seeds. For this purpose, three native strains of diazotrophic bacteria were isolated from soil samples of oil palm crops in Tibú, located at Norte de Santander, Colombia, which were biochemically identified using traditional culture media. These isolates were inoculated into corn seeds in trays with sterile soil plus ciénego at 70/30 ratio respectively, and the plant growth-promoting effect was recorded every 4 days, by measuring morphological variables such as height, number of leaves, number of roots, length and germination rate. The results showed that Azotobacter sp, 2 treatment presented a higher production of roots, reached greater height (cm), number of leaves and germination rate in comparison to control treatment after 12 days of monitoring, besides directly influencing the percentage of organic matter in the substrate and elements such as calcium, potassium and phosphorus, allowing greater productivity and corn seed yield once these were germinated.
Performance, chemical composition and antibacterial activity of the essential oil of Ruta chalepensis and Origanum vulgare
Authors: Arámbula C I , Diaz C E , Garcia M I
Published: November 2019

The antibacterial effectiveness of Origanum vulgare and Ruta chalepensis essential oils cultivated in three municipalities of Norte de Santander, Colombia, on gram positive and gram-negative bacteria was determined in vitro. The oil extraction process was carried out at zoey perfumery company by the steam dragging method from 5 kg of vegetable material, the oil yield obtained compared with the vegetable material collected was calculated using mathematical formulas and its chemical composition was determined by mass spectrometry since is an analytical technique with great potential that allows to elucidate the structure and chemical properties of molecules. For the determination of the minimum inhibitory concentration and the minimum bactericidal concentration of the extracted oils, the mother solution of 2.5 g/mL was prepared and from this solution, the different dilutions at concentrations from 1000 mg/mL up to 15.62 mg/mL were made. A suspension equal to tube 0.5 of the McFarland scale of each of the microorganisms (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) was then prepared with sterile saline solution and inoculated in microplates with volumes of diluted solution, soy tripticasa broth and dimethyl sulfoxide, was then incubated at 37 °C for 18 hours and proceeded to inoculate in Müeller-Hinton agar to verify its minimum bactericidal concentration. The results show that the yield of Origanum vulgare essential oil was 0.8% and for Ruta chalepensis 0.1%. The chemical analysis of the oils revealed the major components of Origanum vulgare such as β-mircene 1.6%, ∝-terpinene 15.7%, 1.8-cineol 3.8%, yterpineno 2.6%, terpine-4-ol 1.1%, timol methyl ether 17.4%, timol 30.6%, carvacrol 8.1%, trans-β-caryophyllene 6.3%, ∝-humulene 1%, cariophylene oxide 3.1% and Ruta chalepensis as nonanone 37.1%, undecanone 39.4%, nonanyl acetate 2.2%, decanone 2.8%. The results obtained show that essential oil of Ruta chalepensis at concentration of 500 mg/mL stop growth of Escherichia coli and seudomonas aeruginosa and at a concentration of 1000 mg/mL stop growth of S. aureus while the essential oil of Origanum vulgare was the most effective for the inhibition of all the microorganisms evaluated, requiring a concentration of 15.62 mg/mL for Escherichia coli and Staphylococcus aureus and for Pseudomonas aeruginosa, a concentration of 125 mg/mL was necessary. It is concluded that according to the chemical composition, materials of vegetable origin such as Ruta chalepensis and Origanum vulgare essential oils can be taken for the elaboration of products with potential in artisanal cosmetics and even in pharmaceutical products.
Application of maturity method to estimate compressive strength of mass concrete
Authors: Gamba O , Peña G , Pineda Y
Published: November 2019

The correlation between the maturity index and the compressive strength of concrete is validated for mixtures with strengths of 2000, 2500, 3000 and 3500 PSI, which are the most used in the civil engineering field. Temperature probes DS18B20 connected by the 1-Wire protocol to the Raspberry Pi 3 card were used to census the data and calculate the maturity index. The concrete mixtures presented A/C ratios of 0.820, 0.748, 0.680 and 0.623, which are consistent with those used in the construction industry. Compressive strength tests were performed every 24 hours during a 28-day test scenario in order to understand the behavior of concrete throughout the curing process. From the values of mechanical resistance to compression obtained in the control ages of 7 and 14 days it is inferred that the concrete has a normal hardening, likewise when comparing the experimental results of the resistance to compression, with those found using the method of maturity, it was possible to identify that at early ages (less than 10 days) they present uncertainties greater than 10% while at ages greater than 10 days of curing this error does not exceed 5%. In general, it was evidenced that the assembly carried out with the Raspberry pi 3 card and DS18B20 probes reliably allowed the monitoring, recording and storage of temperature and time data during the entire curing process.
Metal hydrides with body-centered cubic structure: Advantages and challenges
Authors: Martinez-Amariz A , Peña Dario , Montes Vera E
Published: November 2019

Metal hydrides are considered an easy and safe way to store hydrogen. Storage is one of the keys to the large-scale implementation of the so-called hydrogen economy, which will undoubtedly revolutionize the new vision of sustainable development towards a more environmentally friendly world. This paper presents a general review of some alloys based on TiCrV and TiCrVZr showing their advantages and challenges that must be developed for their implementation. The capacity of absorption and desorption as a function of time is shown using a Sieverts type device, the structure is studied by means of X-ray diffraction as well as its morphology by means of scanning electron microscopy. This paper shows the advantages and disadvantages of alloy synthesis methods based on transition metals, it is observed that hydrogen capacity increases in the process of fusion synthesis and decreases in the process by mechanical grinding, however the capacity desorption is not optimal at room temperature.
Market analysis of the target population for the creation of waterproof paint to mitigate environmental impacts in Bucaramanga, Colombia
Authors: Tiria L C , Zamudio W H , Bellon D , Useche I E
Published: November 2019

In this study, a target population of hardware stores that sell paint in the city of Bucaramanga, Colombia was determined. Through a survey, we proceeded to investigate in business the different uses that give expanded polystyrene that generally serves as a product packaging element. A univariate and bivariate analysis of the variables used in this study was carried out with statistical package for the social sciences to make a diagnosis of the different uses of expanded polystyrene and its use in construction materials. Therefore, use the expanded polystyrene to reduce the volume in sanitary landfills through the creation of waterproofing paint. The gradual process of industrialization of the new paint based on expanded polystyrene EPS will allow mitigating the transit of these wastes to sanitary landfills to reduce environmental impact, will allow the emergence of a new production chain as a commitment to a social industry that will receive economic benefits for the improvement of the quality of life of the actors that will intervene in said productive chain. It has not been implemented because some scientists believe that the inputs required to mix expanded polystyrene are expensive and the industry would not be willing to take on. It is observable that the scientific community is also not interested in exploring limonene alternatives so that the criteria of a mixture with environmentally friendly expanded polystyrene are maintained.
Development and characterization of a polymer based on the biomimicry of the intervertebral disc
Authors: Angulo K P , Villegas D F , Ramírez G E
Published: November 2019

The development and characterization of a functional graded composite material based on the biomimicry of the human intervertebral disc is reported in this research. The material consists of concentric radial polyurethane layers, synthesized using a condensation polymerization chemical reaction, found on methylene diphenyl diisocyanate, glycerol and castor oil as reagents. The proportions in the components of the polyol, glycerol and castor oil, were modified to generate a change in the degrees of cross-linking in the chains of the material, resulting in slightly rigid layers, as in the structure of the intervertebral disc. Two radial gradations were made through a rotating assembly and the complex modulus of the constituent polyurethane layers was used as the gradation criteria since the complex modulus provides a general description of the mechanical behaviour. After the gradation process, the graded material was characterized by means of a dynamic mechanical analysis that determines its viscoelastic properties, like storage modulus, loss modulus, complex modulus and tan δ. Moreover, with its behavioural pattern to compression and flexion, we performed a comparative analysis of the improvement of the mechanical properties of its constituent materials. The development of this study under biomechanical and chemical guidelines came together with two proposals of graded materials with high versatility and functionality in terms of frugality and stability for temperatures changes, as well as absorption and dissipation of mechanical energy. Furthermore, it serves as a tool for the elaboration of machines elements under combined load of compression and flexion at a low cost.