bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of musa paradisiaca fibers for the preparation and chemical, physical and mechanical characterization of a biodegradable composite material
Authors: Martínez C , Ruiz W , Lesmes S , Laverde D , Pertuz A 
Published: November 2019

Abstract
Composite materials with comparable properties and low environmental impact have been at the forefront of research. In the present work, the mechanical, physics and chemical properties that allow knowing the potential applications of Musa Paradisiaca fibers are evaluated, through an experimental process that starts from the selection of the binder and its fiber/binder ratio through tensile tests. The finally formed material is composed of a matrix of gelatin type C and glycerin and a reinforcement of banana fibers. The compound obtained was characterized by infrared spectroscopy by the Fourier transform, thermogravimetry, scanning electron microscopy and mechanical tensile and hardness tests. The results obtained from this study allowed confirming the presence of lignin and hemicellulose and evidencing the presence of good mechanical properties with a modulus of elasticity equivalent to 0.57 MPa, a percentage of elongation of 56%, an ultimate tensile strength of 3.5 MPa and a hardness of 82 Shore A, which allows us to consider a biodegradable composite material for applications in which soft gums and elastomers perform. The results obtained allow us to consider other alternatives for the use of Colombian banana fibers, in addition to their use as a biodegradable compound.
Thixotropic behaviour study of clayey soils from the lacustrine deposits of Bogotá high plateau
Authors: Ruge J C , Molina-Gómez F , Rojas J P 
Published: November 2019

Abstract
Thixotropy is a distinctively rheological (time-dependent) phenomenon, which is found in many complex materials, especially colloidal systems as fine-grained soils. Clays are materials that can recover their initial strength after remoulding. The estimation of such recovering allows optimising the designs of geotechnical structures and then reducing the construction costs. This paper presents the results of a study that evaluates the thixotropy phenomenon of clayey soils. The work methodology involved an experimental plan composed of five phases: (i) extraction of samples; (ii) physical and mechanical characterisation of the undisturbed samples; (iii) remoulding of samples after testing; (iv) storage of remoulded samples; and (v) evaluation of undrained shear strength recovering for 0, 15, 30, and 60 days after remoulding. Undisturbed samples were collected using Shelby tube from the municipality of Madrid, near Bogotá, in Colombia. Results were analysed in terms of sensitivity degree because this parameter allows estimating the shear strength recovering. Findings show that clayey soils from lacustrine deposits of Bogota high plateau do not loss completely all of their original mechanical properties after remoulding and exhibit a medium sensitive behaviour. Conclusions indicate there is a recovering of undrained shear strength along the time, in which the samples will recover their original state about one year after remoulding.
Characterization of smart materials requirements for actuation in the robotic applications
Authors: Ramirez J L , Rubiano A , Cogollo J G 
Published: November 2019

Abstract
This paper presents the requirements specification of artificial muscles based on smart materials for a robotic finger prosthesis. The first part introduces the robotic finger, designed to mimic human precision grasping. A methodology to determine three critical parameters (strain, frequency and force) is presented. The methodology uses experimental data combined with kinematics and dynamics. Obtained values are calculated using the developed finger; as a result, we define that main requirements are: (i) Minimum active strain 5.5% for extension-based actuation or 60% bending-based actuation, (ii) Frequency (8.89 Hz, 22.2 Hz), and (iii) Force (4.80 N, 6.74 N) for bending-based actuation or force (17.81 N, 25.11 N) for extension-based actuation. Finally, a review of smart materials is presented with the aim of choosing the group of materials that can be used as artificial muscles for robotic hands. We show that shape memory Alloys can fulfill the established specifications. We also stand out Ionic polymer metal composites as a very promising actuation solution for robotic hands, due to their active strain and settling time, even though the blocking force is below the requirements.
Synthesis and size evolution of 1D hydroxyapatite crystals under surfactant-free hydrothermal conditions
Authors: García-Negrete C , Goméz R , Brun L , Barrera M , Arteaga G , Beltrán A , Fernández A 
Published: November 2019

Abstract
Hydroxyapatite nanoparticulate materials have received a great deal of scientific attention due to their dental and orthopedic applications but simple strategies to control particle characteristics (e.g., surface area, shape and size distribution) are still needed. Among several hydroxyapatite structures, one-dimensional nanoscale materials such as nanowires, nanorods and nanobelts can be synthesized in the presence of specific surfactants added during synthesis in order to alter the particle growth. This contribution is aim to explore strategies to obtain one dimensional hydroxyapatite crystals without the use of surfactants. Particularly, we study the effect of several variables such as temperature, reaction time and pH on shape and size of hydroxyapatite crystals produced under hydrothermal conditions. The results obtained show the formation of hydroxyapatite nanorods as well as some interesting insights about how to control particle sizes in samples obtained at temperatures between 180 °C and 220 °C. These results have potential benefits at the time of producing one dimensional hydroxyapatite crystals in a simple and not expensive way.
Evaluation of the effect of a hyperbranched polyester on the thermal, rheological, morphological and mechanical properties of polyvinyl chloride/hemp fiber blends
Authors: Tolosa R , Acevedo C , Murillo E A 
Published: November 2019

Abstract
The aim of this study was to investigate the effect of the hyperbranched polyester polyol from second generation content on the structural, thermal, rheological, morphological and mechanical properties of recycled polyvinyl chloride/hemp fiber/hyperbranched polyester polyol obtained from second generation blends. In all blends, the amounts of recycled polyvinyl chloride and hemp fiber were 70 wt% and 30 wt% respectively. The blends were obtained in a torque rheometer. The proportions of hyperbranched polyester polyol regards to those of the polyvinyl chloride and hemp fibers were 5 wt%, 10 wt%, 15 wt% and 20 wt%. Additionally, a recycled polyvinyl chloride/hemp fiber blend was prepared to be used as control blend. Infrared analysis was then used to evidence the interaction between components of the blends. The thermal stability of the recycled polyvinyl chloride/hemp fiber/hyperbranched polyester polyol blends was lower than that of the polyvinyl chloride. Furthermore, it was not observed a trend in the thermal behavior of the recycled polyvinyl chloride blends. Hyperbranched polyester polyol increased the glass transition temperature of the blends. Additionally, rheological analysis results indicated that the hyperbranched polyester polyol reduced the viscosity of the blends.
Methodology for simulating the process of microbiologically induced degradation of concrete by chemical exposure of specimens under controlled laboratory conditions
Authors: Cortés M , Vera E 
Published: November 2019

Abstract
Research studies on the kinetics of the corrosion process that attacks concrete coincide in the amount of variables that interfere with the process, such as the impact of the pH levels of the corrosive environment and the surface of the concrete and the concentrations of biogenic sulfuric acid at the site. For this reason, it is vitally important to know the resistance of concrete to this attack in controlled laboratory conditions, defining a methodology that contributes to the development of new research related, for example, to the degradation of concrete in component elements of a sewer system.
All-glass vacuum tube heat transfer simplified model
Authors: Ardila O , Quiroga J , Martínez O 
Published: November 2019

Abstract
This paper addresses the design of an algorithm that estimates the irradiance and the selective layer temperature of the all-glass vacuum tube as a function of the ambient temperature in Bucaramanga, Northern Colombia. A Matlab code to meteorological National Aeronautics and Space Administration data processing and to find a linear relationship between the irradiance and ambient temperature on the location of study, was developed. The behavior of this relationship for several hours of the day was studied, and it was found that it is possible to use this relationship as a reliable preliminary approach in water heating systems design using all-glass vacuum tube. This facilitates the design calculations and would encourage the use of solar energy in water heating systems in Colombia.
Synthesis of Cu2ZnSnSe4 from nitrate and selenite inks for use as an absorbent layer in the design of solar cells
Authors: Torres-Barahona E A , Castellanos-Báez Y , Gómez-Cuaspud J A , Vera-López E , Carda J B , Pineda-Triana Y 
Published: November 2019

Abstract
This research was conducted to identify two acceptable precursors and methods of synthesis for the manufacture of photovoltaic cells. The kesterite Cu2ZnSnSe4, a promising material for solar cell applications, was synthesized from metal salts of Cu, Zn, Sn, and Se, by two low-cost routes: the direct dissolution of metal nitrates, and coprecipitation of selenites. In both cases, inks were obtained and deposited as thin-films by the Doctor Blade technique on glass substrates coated with molybdenum. The films were annealed in an oven at 550 °C by 30 minutes. The phases of each thin film were analyzed by X-ray diffraction and Raman scattering. The morphology and the thickness of the layers were observed using a scanning electron microscope. The optical band gap was determined by ultraviolet-visible spectroscopy and the Tauc equation. The results confirmed the main phase of kesterite material, consistent with a tetragonal crystalline system oriented along the plane (112). These values are consistent with those found by Raman spectroscopy, where the main vibrational mode was identified at 173 cm−1 and 196 cm−1, characteristic of mode A vibration, and 243 cm−1 of mode B vibration; typical of kesterite. Simultaneously, a band gap of 0.89 eV was identified. These results demonstrate the effectiveness of the selenite’s coprecipitation method for synthesis of kesterite, without evidence of secondary phases. This determines the possibility of using this material in solar cell applications.
Design and characterization of a magneto-dielectric composite in high frequency with aligned magnetite powders
Authors: Lara L A , Mancipe D L , Pineda Y , Moreno J J , Peña-Rodríguez G 
Published: November 2019

Abstract
A magneto-dielectric material composed of a polyester resin-based microstrip (P115A), copper sheets and magnetite powders was designed in concentrations of 10, 20 and 30% Wt and with filters of 200, 325 and 500. The particles were aligned vertically and horizontally during the curing process using 300 mT magnetic fields. From a complete factorial design of 33, 27 microstrip-type circuits of 4 mm width, 70 mm length and 0.93 mm thickness were manufactured, characterized by scanning electron microscopy and vector network analysis. The cross-matrix analysis determined an optimal circuit response from the magneto-dielectric material with a concentration of 20% magnetite and an average particle size of 21.48 μm in horizontal alignment to the applied magnetic field and to the transmission line, obtaining a relative dielectric constant of Er 3.88 with a low dielectric loss of 0.054, within an operating range of 150 KHz to 4 GHz.
Characterization of biodeteriorating microorganisms in buildings in Bucaramanga, Colombia
Authors: Mantilla K , Suárez-Barrera M , Rueda-Forero N J , Guarín O D , Gómez F R , Durán S M , Tiria L C 
Published: November 2019

Abstract
The action of the microorganisms upon the integrity of the constructing material is termed Biodeterioration, concrete resistance to the action of the microorganisms is considered an indirect measurement of its durability and could be used as a marker of the integrity of the structure. In Colombia, the studies considering this parameter are rare. The objective of this study was to isolate and characterize the microbial communities present in areas with evident deterioration in the selected buildings. To accomplish this, isolation, culturing and molecular identification of the isolates was performed. Results showed that Cladosporium spp, Aspergillus spp, Mucor spp, Penicillium spp, Penicillium spp, Rhizopus spp, Fusarium spp, Geotrichum spp, and bacterial genera such as Bacillus spp and Amphibacillus spp, coexist within the biofilms sampled. This study is a description and a starting point to deepen the characterization of these communities and to understand the role they perform in the integrity of the building materials considering the climatic and environmental conditions.
Estimation of multiple parameters using algorithms expectation maximization
Authors: Ospina R , Correa G , Cárdenas P P 
Published: November 2019

AbstractIn this paper the strategy of the expectation maximization algorithm is developed in order to solve the problem of maximization of the likelihood which becomes a complex problem when it is expected to estimate multiple parameters at the same time. All this will be achieved with the introduction of basic concepts of statistical estimators and will be verified by simulations carried out in the MATLAB software.
Embedded quantum dots in semiconductor nanostructures
Authors: Paredes Gutiérrez H , Pérez Merchancano S T 
Published: November 2019

Abstract
In this work, we report the behavior of the tunneling current in a semiconductor nanostructure of (Ga, Al)As/GaAs which takes into account the behavior of the electrons and the Rashba’s spin orbit interaction in the presence of embedded quantum dots of different geometries (lens, pyramid and ring) in voltage function, magnetic field, and the different values of the interaction spin orbit (π/2, π/4 and 3π/4). The results that were obtained show, that the intensity of the current presents appreciable changes when is changed the configuration of the quantum dot as the intensities of external fields and spin polarization as well. All these internal and external effects that are studied in our model, significantly modify the transport of information of the semiconductor nanostructure, our results show that the spin effects and the quantum dot configuration contribute to the quantum memories efficiency and the spin filter devices of actual use on nanoscience and nanotechnology.
Structural study of hydrogen absorption properties using Thermocalc software for application in energy storage
Authors: Bellon D , Martínez-Amariz A , Montes E 
Published: November 2019

Abstract
The interest in developing experiments and processes in general through mathematical modelling or simulation, has been growing considerably in recent decades; the previous, insofar as it offers highly reliable results that have an impact on advantages such as reduction of the risk associated with the execution of costly or difficult to reproduce experiments since they handle many variables or even the elimination of times associated with the execution of said experiments. For its part, the study of hydrogen storage alloys represents a fundamental element in the so-called hydrogen economy, which seeks the integration of hydrogen as an alternative solution to dependence on fossil fuels, due that this energy vector has a high energy density when is compared to the gasoline and the only residue of this process is water vapor that will undoubtedly reduce CO2 emissions. Thus, in this study a simulation of the evolution of the microstructure of hydrogen storage alloys based on TiCrV is developed, using ternary systems at different temperatures; this evolution is the result of the phase change when the elements are subjected from high temperatures to room temperature, obtaining a body-centered cubic structure. Likewise, the solidification process of the components present in the alloy is studied to corroborate the final structure with experimental data. In preliminary results, it is observed that the simulation throws a body centered structure, and in the solidification process, a remnant of a compact hexagonal structure is observed. This Ti-Cr-V system is widely studied due to its large hydrogen storage capacity, which can be used for technological purposes.
Numerical modelling of guided waves dispersion curves in an aluminium flat plate by finite element analysis
Authors: Galvis L , Quiroga J , González-Estrada O A 
Published: November 2019

Abstract
This work presents a practical approach to obtain the dispersion curves for a plate via numerical modelling using the commercial software ANSYS. The method is based on the dynamic analysis of the waveguide to extract the mode shapes (eigenvectors) for each resonant frequency (eigenvalue) from the natural frequency response without damping. Each eigenvalue provides a frequency and the dimensions of the model (wavelength), which are the basis of the dispersion curves. Then, an algorithm is developed in MATLAB to stack the different mode solutions with its respective frequencies using the modal assurance criterion. The data obtained is compared with the dispersion curves provided by the GUIGW software.
Numerical simulation of electron cyclotron resonance phenomenon using an axisymmetric transverse electric field
Authors: Otero O , Orozco E A 
Published: November 2019

Abstract
As a contribution to the study of the resonant interaction between of an electron and the transverse electric field of a stationary electromagnetic wave in the presence of a static homogeneous magnetic field in this work we develop a numerical study of the acceleration of electrons by cylindrical mode TE011. In order to get a better understanding of the particle-wave interaction, the electric field of the microwave mode is decompose as the superposition of a left-and a right-hand circularly polarized standing wave because electrons interact effectively only with right-handed circular polarized wave. The trajectory, energy and phase-shift between the electron transverse velocity and the electric field are determined by the numerical solution of the relativistic Newton-Lorentz equation using a finite difference scheme. For an electron injected longitudinally with an energy of 5 keV and that starts at the radial midpoint of the cavity, it is accelerated up to an energy of about 90 keV using an electric field amplitude of 14 kV/cm and a frequency of 2.45 GHz. These results are compared with those obtained for another two points of injection located in different radial positions. This levels of energy can be used to produce soft X-ray which has some important medical applications like imageology. The results suggest that the particle-wave interaction using the cylindrical mode TE011 could be optimized through the application of a external magnetic field which is gradually growing in time to preserve the resonance condition and sustain the phase stability.
Modelling the effect of temperature on the physical and mechanical properties of ceramic composites filled with foundry sand waste
Authors: Roa KL , Paredes RA , Trejo F , Castro HF , Vera E , Peña G 
Published: November 2019

Abstract
The aim of this research is to describe the temperature effect on the water absorption, linear shrinkage, density and compressive strength of ceramic composites produced by mixing clay with additions of foundry sand waste from 20% to 40% wt. Previous studies have shown that foundry sands can be recycled due to the high content of SiO2 on its chemical composition, therefore, in this research is proposed as an alternative raw material in ceramic bodies. Prototypes were shaped by uniaxial pressing method and fired at three different temperatures (850°C, 950°C and 1,050°C) in order to promote the formation of the ceramic phases. Physical and mechanical properties were measured based on the procedures specified by standard ASTM C373 and ASTM C773-88. It was found that at 1,050°C properties such as mechanical strength and density reach its maximum values, effect that might be associated to the reduction in pore size inside the microstructure during calcination. The main merit of the models obtained is offer a valuable tool to set up a proper thermal process in order to obtain eco-friendly ceramic samples with physical and mechanical properties at its optimum values, reducing environmental problems related to landfill disposal and minimizing costs of manufacturing.
Design and simulation of an alternative aqueduct network for urban population
Authors: Orjuela Abril M S , Rojas Suárez J P , Prada Botia G C 
Published: November 2019

Abstract
Aqueduct systems help to record water consumption, being a connection between nature and the population, allowing water to be transported continuously; a good design of aqueduct networks is necessary to meet the purpose of providing the community with a technical report that can serve as a starting point to carry out a construction of the aqueduct for the public battery. This research presents the simulation of an aqueduct system by means of the epanet software according to the daily maximum flow, pressure, velocities of the distribution network, pumping time, with respect to the different pressures and diameters, diagnosing the routes, nodes, forms of access, restrictions and limitations that may affect the proper functioning of the system; In this way, the advantages and the magnitude of beneficiaries who will have this new access and improved service to meet the needs of the inhabitants are evident, according to the technical requirements of drinking water and sanitation of the technical regulation of the drinking water and basic sanitation sector, where it can be implemented by any public company in the country.
Fractal analysis in rural domestic wastewater quality under dissolved oxygen stability in wetlands planted with Chrysopogon zizanioides
Authors: Prada D A , Reátiga A , Correa S N , Acevedo A , Mantilla J , Florville T , Nuñez J 
Published: November 2019

Abstract
Chrysopogon zizanioides is a plant with adaptability characteristics in a variety of soils and climatic conditions, improves quality of wastewater and industrial water, due to the root system, allows the consumption of organic matter and capture pollutants. One of the water quality indicators is the amount of dissolved oxygen present. To analyze the recovery behavior of dissolved oxygen in wastewater, an artificial subsurface flow wetland was designed with stone as a filter material with dimensions 0.9 m wide, 2.5 m long and 0.60 m deep and 30 Vetiver plants. These dimensions and quantity of plants were considered appropriate in terms of space and low cost in order to replicate in rural and semi-urban areas, because in some of these they do not have an appropriate aqueduct, then this strategy becomes an option for people residing in these places. The water treated in this wetland is domestic wastewater from a rural house in the municipality of Floridablanca, Colombia. For 4 weeks the data of the dissolved oxygen present in said water was recorded using a multiparameter probe, to observe how effective the process is in a shorter time and using fractal dimension the volatility of this time series was observed.