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Publisher: Universidad Pedagógica y Tecnológica de Colombia   (Total: 17 journals)   [Sort by number of followers]

Showing 1 - 17 of 17 Journals sorted alphabetically
Apuntes del CENES     Open Access   (Followers: 2)
Ciencia en Desarrollo     Open Access  
Ciencia y Agricultura     Open Access  
Cuadernos de Psicopedagogía     Open Access  
Cuestiones de Filosofía     Open Access  
Educación y Ciencia     Open Access   (Followers: 1)
Ingeniería Investigación y Desarrollo     Open Access   (Followers: 3)
Inquietud Empresarial     Open Access  
La Palabra     Open Access  
Perspectiva Geográfica     Open Access   (Followers: 1)
Praxis y Saber     Open Access  
Revista Colombiana de Ciencias Hortícolas     Open Access  
Revista de Investigación, Desarrollo e Innovación     Open Access  
Revista Facultad de Ingeniería     Open Access   (Followers: 1)
Revista Historia de la Educacion Latinoamericana     Open Access   (Followers: 2)
Salud & Sociedad     Open Access   (Followers: 1)
Salud Historia Sanidad     Open Access  
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Revista Facultad de Ingeniería
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0121-1129
Published by Universidad Pedagógica y Tecnológica de Colombia Homepage  [17 journals]
  • Effect of copper-enriched layers on localized corrosion of
           aluminium-copper alloys

    • Authors: María Ángeles Arenas-Vara, Peter Skeldon, Sandra Judith García-Vergara
      Abstract: Copper-enriched layers were developed onto aluminum-copper alloys using alkaline etching in sodium hydroxide, for both, sputter deposited and bulk conditions. Enriched alloys were evaluated by potentiodynamic polarization in sodium chloride solution in order to determine the effect of the enriched layers on the pitting potential of the alloys. Rutherford backscattering spectroscopy was employed to quantify the enrichments and their locations just beneath the alumina-based oxides remaining from the etching. For the sputter deposited aluminum-copper alloys, the results show some scattering of the pitting potential data, and no correlation between pitting potential and the alloy enriched layer. In the case of bulk Al-2wt.%Cu alloy, with the copper in solid-solution, the pitting potential increased for the enriched specimens, indicating also a different pit morphology, with respect to the non-enriched alloy.
      PubDate: 2018-05-20
      DOI: 10.19053/01211129.v27.n48.2018.8016
      Issue No: Vol. 27, No. 48 (2018)
       
  • Manufacture of titanium dioxide scaffolds for medical applications

    • Authors: Giovanni Cuervo-Osorio, Ana María Jiménez-Valencia, Cristian Mosquera-Agualimpia, Diana Marcela Escobar-Sierra
      Abstract: The skeletal system is vulnerable to injuries and bone loss over the years, making the use of autologous or allogeneic implants necessary. However, these implants have complications, such as the limited amount of bone to be extracted and the cell death at the extraction site; hence, biomaterials have been developed as platforms for cell growth (scaffolds). Biomaterials and bones have similar properties that facilitate the integration between the material and the bone tissue, helping the tissue to regenerate. Traditional ceramic implants are hydroxyapatite, but given their low mechanical properties, they have been replaced with better inert ceramics. Therefore, this study aims at manufacturing titanium dioxide scaffolds through various techniques, using collagen, polyvinyl alcohol (PVA), sodium chloride, and corn flour as binders to influence pore size. Scaffolds were characterized by a Scanning Electron Microscope (SEM) and evaluated by compression and degradability tests in a Simulated Body Fluid (SBF). The prepared scaffolds had mechanical behaviors with ranges within the bone parameters; among them, the scaffold obtained by infiltration with 10% PVA presented values of compression strength (6.75 MPa), elastic modulus (0.23 GPa), and porosities (54-67%) closer to the values of the trabecular bone.
      PubDate: 2018-05-20
      DOI: 10.19053/01211129.v27.n48.2018.8017
      Issue No: Vol. 27, No. 48 (2018)
       
  • Implementation of an electromagnetic system for controlling resistance and
           speed in indoor cycling

    • Authors: Jairo A. Moreno-González, Andrea Catherine Alarcón-Aldana, Mauro Callejas-Cuervo
      Abstract: Advances in knowledge and technology in various fields of human life and, particularly, in sports have resulted in innovative systems for professional sportsmen training. Here, we designed an electromagnetic system for practicing indoor cycling; this system can precisely simulate on the track the ascents and descents that allow the users to feel like they are training outdoors. Furthermore, this system connects to a web application that allows access from any mobile device to predefine the training routines and thus improve the user experience.
      PubDate: 2018-05-20
      DOI: 10.19053/01211129.v27.n48.2018.7982
      Issue No: Vol. 27, No. 48 (2018)
       
  • Degradation, water uptake, injectability and mechanical strength of
           injectable bone substitutes composed of silk fibroin and hydroxyapatite
           nanorods

    • Authors: Maritza Buitrago-Vásquez, Claudia Patricia Ossa-Orozco
      Abstract: Injectable bone substitutes are generally composite materials capable of being extruded through a device; they consist of a solid phase inside a matrix that allows the easy movement of particles. Injectable bone substitutes have the advantage of allowing its application in situ without the need of invasive surgical techniques, guaranteeing a good recovery; for this reason, they are a promising alternative to replace conventional techniques to repair bone defects. Conventional techniques include the use of allografts and autografts, which often cause adverse reactions, and are disadvantageous for both the patient and the doctor. Furthermore, there are no reports regarding bone substitute development in Colombia, creating the necessity to research composite materials that could become injectable bone substitutes. In this study, we manufactured injectable bone substitutes with hydroxyapatite and calcium phosphate, which is most similar to bone tissue, and synthesized them in nanorods with shape and size similar to the natural hydroxyapatite found inside the body. Additionally, we used extracted silk fibroin from silkworm cocoons of Bombyx mori, a natural polymer of protein nature with high mechanical properties and excellent biocompatibility. For the materials manufactured, we evaluated degradation, in a simulated body fluid (SBF) at normal body temperature, water uptake, injectability and mechanical strength. The manufactured bone substitutes showed good degradation and water uptake properties, an approximate 97% injectability, and low mechanical resistance, indicating promising properties to be used as an injectable bone substitute.
      PubDate: 2018-05-05
      DOI: 10.19053/01211129.v27.n48.2018.8072
      Issue No: Vol. 27, No. 48 (2018)
       
  • Morphology, mechanical strength and degradation of polyhydroxyalkanoate
           scaffolds

    • Authors: Liliana Maria Arroyave-Muñoz, Claudia Patricia Ossa-Orozco
      Abstract: Tissue engineering (TE) seeks to improve the unsatisfactory development of implants and medical procedures to solve bone and cartilage injuries. TE aims at regenerating tissues using cell growth platforms (scaffolds), which may consist of natural polymers such as polyhydroxyalkanoate (PHA). PHA is an innovative material useful in medical applications due to its degradation capability and bacterial origin that allows large-scale production and control final properties. In this research, we developed commercial PHA scaffolds using the lyophilization technique with a factorial experimental design. We used dichloromethane as PHA solvent, tergitol as surfactant, and liquid nitrogen (N2) for the freezing process. We characterized the PHA by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA); and the scaffolds by scanning electron microscopy (SEM) and mechanical compression and hydrolysis degradation tests. The characterization of the PHA indicated that the material is a mixture of PHA and polylactic acid (PLA). The results showed a suitable pore distribution for migration of chondrocytes through the scaffold, in addition to a behavior similar to that of the articular cartilage, although it presented lower mechanical strength. Also, the scaffolds displayed mass loss in a non-linear way related to the percentage of PHA present in the sample. In conclusion, PHA scaffolds have a potential use in tissue engineering for restoring articular cartilage.
      PubDate: 2018-05-05
      DOI: 10.19053/01211129.v27.n48.2018.8073
      Issue No: Vol. 27, No. 48 (2018)
       
  • Night air conditioning of buildings by external air ventilation

    • Authors: Debrayan Bravo-Hidalgo
      Abstract: Buildings contain the environment in which almost all human activities take place, and therefore, nowadays, they represent a great sink of energy. Establishing thermal comfort conditions within these buildings is responsible for a large portion of their energy demand. This paper aims at providing a theoretical framework of the performance and the trends in research and implementation of night air conditioning by outside air ventilation. The bibliographic search was conducted in the academic directory Scopus, and the information extracted was processed in the VOSviewer software, through which text mining, map of terms and networks of investigative action were carried out. The literature showed that direct ventilation has a more significant cooling potential in regions characterized by a high difference between day and night air temperatures. The effectiveness of night cooling and the reliable prediction of thermal behavior are strongly related to the model adopted for the convection algorithm. A reliable prediction of heat transfer by convection requires an approach based on computational simulations of fluid dynamics, which are much more demanding in terms of computational power, compared to simulations of the variation of energy flows as a function of time. Most studies showed that the position of the thermal mass is not significant, while the amount of ventilation air is of great importance. In particular, the energy demand for cooling a building decreases sharply if the air flow rates increase.
      PubDate: 2018-05-04
      DOI: 10.19053/01211129.v27.n48.2018.8071
      Issue No: Vol. 27, No. 48 (2018)
       
 
 
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