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Examinando por Materia "article"

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Architecture and microstructure of cortical bone in reconstructed canine mandibles after bone transport distraction osteogenesis
(SPRINGER, 2011-11-01) Zapata, Uriel; Halvachs, Emily K.; Dechow, Paul C.; Elsalanty, Mohammed E.; Opperman, Lynne A.; Zapata, Uriel; Halvachs, Emily K.; Dechow, Paul C.; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
Reconstruction of the canine mandible using bone transport distraction osteogenesis has been shown to be a suitable method for correcting segmental bone defects produced by cancer, gunshots, and trauma. Although the mechanical quality of the new regenerate cortical bone seems to be related to the mineralization process, several questions regarding the microstructural patterns of the new bony tissue remain unanswered. The purpose of this study was to quantify any microstructural differences that may exist between the regenerate and control cortical bone. Five adult American foxhound dogs underwent unilateral bone transport distraction of the mandible to repair bone defects of 30-35 mm. Animals were killed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical cortical samples were extracted from the superior, medial, and inferior aspects of the lingual and buccal plates of the reconstructed aspect of the mandible, and 21 specimens were collected similarly from the contralateral aspect of the mandible. Specimens were evaluated using histomorphometric and micro-computed tomographic techniques to compare their microstructure. Except for differences in haversian canal area, histomorphometric analyses suggested no statistical differences in microstructure between regenerate and control cortical bone. Morphological evaluation suggested a consistent level of anisotropy, possibly related to the distraction vector. After 12 weeks' consolidation, bone created during bone transport distraction osteogenesis was comparable to native bone in microstructure, architecture, and mechanical properties. It is proposed that, after enough time, the properties of the regenerate bone will be identical to that of native bone. © Springer Science+Business Media, LLC 2010.
Architecture and microstructure of cortical bone in reconstructed canine mandibles after bone transport distraction osteogenesis
(SPRINGER, 2011-11-01) Zapata, Uriel; Halvachs, Emily K.; Dechow, Paul C.; Elsalanty, Mohammed E.; Opperman, Lynne A.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
Reconstruction of the canine mandible using bone transport distraction osteogenesis has been shown to be a suitable method for correcting segmental bone defects produced by cancer, gunshots, and trauma. Although the mechanical quality of the new regenerate cortical bone seems to be related to the mineralization process, several questions regarding the microstructural patterns of the new bony tissue remain unanswered. The purpose of this study was to quantify any microstructural differences that may exist between the regenerate and control cortical bone. Five adult American foxhound dogs underwent unilateral bone transport distraction of the mandible to repair bone defects of 30-35 mm. Animals were killed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical cortical samples were extracted from the superior, medial, and inferior aspects of the lingual and buccal plates of the reconstructed aspect of the mandible, and 21 specimens were collected similarly from the contralateral aspect of the mandible. Specimens were evaluated using histomorphometric and micro-computed tomographic techniques to compare their microstructure. Except for differences in haversian canal area, histomorphometric analyses suggested no statistical differences in microstructure between regenerate and control cortical bone. Morphological evaluation suggested a consistent level of anisotropy, possibly related to the distraction vector. After 12 weeks' consolidation, bone created during bone transport distraction osteogenesis was comparable to native bone in microstructure, architecture, and mechanical properties. It is proposed that, after enough time, the properties of the regenerate bone will be identical to that of native bone. © Springer Science+Business Media, LLC 2010.
Biomechanical characteristics of regenerated cortical bone in the canine mandible
(WILEY-BLACKWELL, 2011-07-01) Zapata, Uriel; Opperman, Lynne A.; Kontogiorgos, Elias; Elsalanty, Mohammed E.; Dechow, Paul C.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
To test the mechanical properties of regenerate cortical bone created using mandibular bone transport (MBT) distraction, five adult male American foxhound dogs underwent unilateral distraction of the mandible with a novel MBT device placed to linearly repair a 30-35 mm bone defect. The animals were sacrificed 12 weeks after the beginning of the consolidation period. Fourteen cylindrical specimens were taken from the inner (lingual) and outer (buccal) plates of the reconstructed mandible and 21 control specimens were removed from the contralateral aspect of the mandible. The mechanical properties of the 35 cylindrical cortical bone specimens were assessed by using a non-destructive pulse ultrasound technique. Results showed that all of the cortical mechanical properties exhibit higher numerical values on the control side than the MBT regenerate side. In addition, both densities and the elastic moduli in the direction of maximum stiffness of the regenerate cortical bone specimens are higher on the lingual side than the buccal side. Interestingly, there is no statistical difference between elastic modulus (E1 and E2) in orthogonal directions throughout the 35 cortical specimens. The data suggest that not only is the regenerate canine cortical bone heterogeneous, but the elastic mechanical properties tend to approximate transverse isotropy at a tissue level, as opposed to control cortical bone, which is orthotropic. In addition, the elastic mechanical properties are higher not only on the control side but also in the lingual anatomical position, suggesting a stress shielding effect from the presence of the reconstruction plate. © 2011 John Wiley & Sons, Ltd.
Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible
(W.B. Saunders Ltd, 2012-01-01) Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
Purpose: Bone transport distraction osteogenesis provides a promising alternative to traditional grafting techniques. However, existing bone transport distraction osteogenesis devices have many limitations. The purpose of this research was to test a new device, the mandibular bone transport reconstruction plate, in an animal model with comparable mandible size to humans and to histologically and mechanically examine the regenerate bone. Materials and Methods: Eleven adult foxhounds were divided into an unreconstructed control group of 5 animals and an experimental group of 6 animals. In each animal, a 34-mm segmental defect was created in the mandible. The defect was reconstructed with a bone transport reconstruction plate. Histologic and biomechanical characteristics of the regenerate and unrepaired defect were analyzed and compared with bone on the contralateral side of the mandible after 4 weeks of consolidation. Results: The reconstructed defect was bridged with new bone, with little bone in the control defect. Regenerate density and microhardness were 22.3% and 42.6%, respectively, lower than the contralateral normal bone. Likewise, the anisotropy of the experimental group was statistically lower than in the contralateral bone. Half the experimental animals showed nonunion at the docking site. Conclusion: The device was very stable and easy to install and activate. After 1 month of consolidation, the defect was bridged with new bone, with evidence of active bone formation. Regenerate bone was less mature than the control bone. Studies are underway to identify when the regenerate properties compare with normal bone and to identify methods to augment bone union at the docking site. © 2012 American Association of Oral and Maxillofacial Surgeons.
Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible
(W.B. Saunders Ltd, 2012-01-01) Nagashima, L.K.; Rondon-Newby, M.; Zakhary, I.E.; Nagy, W.W.; Zapata, U.; Dechow, P.C.; Opperman, L.A.; Elsalanty, M.E.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
Purpose: Bone transport distraction osteogenesis provides a promising alternative to traditional grafting techniques. However, existing bone transport distraction osteogenesis devices have many limitations. The purpose of this research was to test a new device, the mandibular bone transport reconstruction plate, in an animal model with comparable mandible size to humans and to histologically and mechanically examine the regenerate bone. Materials and Methods: Eleven adult foxhounds were divided into an unreconstructed control group of 5 animals and an experimental group of 6 animals. In each animal, a 34-mm segmental defect was created in the mandible. The defect was reconstructed with a bone transport reconstruction plate. Histologic and biomechanical characteristics of the regenerate and unrepaired defect were analyzed and compared with bone on the contralateral side of the mandible after 4 weeks of consolidation. Results: The reconstructed defect was bridged with new bone, with little bone in the control defect. Regenerate density and microhardness were 22.3% and 42.6%, respectively, lower than the contralateral normal bone. Likewise, the anisotropy of the experimental group was statistically lower than in the contralateral bone. Half the experimental animals showed nonunion at the docking site. Conclusion: The device was very stable and easy to install and activate. After 1 month of consolidation, the defect was bridged with new bone, with evidence of active bone formation. Regenerate bone was less mature than the control bone. Studies are underway to identify when the regenerate properties compare with normal bone and to identify methods to augment bone union at the docking site. © 2012 American Association of Oral and Maxillofacial Surgeons.
Creation of a three-dimensional model of the mandible and the TMJ in vivo by means of the finite element method.
(Quintessenz Verlags GmbH, 2002-04-01) Castaño MC; Zapata U; Pedroza A; Jaramillo JD; Roldán S; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
The aim of this study was to develop a three-dimensional finite element model of the mandible, including its TMJ. The model consisted of 7942 nodes and 41,010 elements, which were obtained from a convergence test, done to minimize the result error. It included cancellous and cortical bone, periodontal ligament, masticatory muscles (masseters, temporalis, lateral and internal pterygoids), teeth and the articular disk. All characteristics such as dental, mandibular, and muscle geometry were obtained from a computerized tomography (CT) of a living person. CT sections were scanned and digitized with a CAD software program. After images were adequately assembled, a vertical tracing was done which allowed the definition of a three-dimensional mesh. Modeling of teeth was carried out independently and the periodontal ligament was later included, limiting the alveolar area. Muscles were modeled based on flat-scale photographs and total muscle force was distributed in multiple vectors. The articular disk was generated having 2 mm of thickness with the combination of spring-type (axial stiffness) and gap-type (contact) elements. The model was then analyzed with finite element method (FEM) software where a mesh was generated and values for Poisson's ratio, elasticity, and shear modulus were assigned. These were orthotropic for cancellous and cortical bone, and isotropic for dentin, periodontal ligament, articular disk, and temporal bone. The boundary conditions were defined restricting the nodes on the periphery of the temporal bone. It was therefore possible to generate a three-dimensional finite element model based on information obtained in vivo.
Decent work and healthy employment: a qualitative case study about Colombian millennials
(Emerald Group Publishing Ltd., 2020-01-01) Gallo Ó.; Gonzales–Miranda D.R.; Roman-Calderon J.P.; García G.A.; Universidad EAFIT. Departamento de Economía y Finanzas; Research in Spatial Economics (RISE)
Purpose: The purpose of this article is to show how a group of Colombian millennials perceive different aspects of working life and how their ideas about job satisfaction, professional expectations and levels of autonomy are related to contemporary demands about inclusion, diversity, equity, autonomy and control. Design/methodology/approach: With this objective, 167 semi-structured interviews were conducted with millennials who work at 10 Colombian companies from the manufacturing and service sectors, located in the five main cities of the country. With a qualitative approach, in the interviews, the research team used a strategy inspired by the technique of generating visual structures associated with grounded theory. Findings: It is concluded that new generations of Colombian workers know of the importance of rewards and autonomy in work and are more critical and less passive in the face of unhealthy working conditions. At the same time, their conduct and speeches are the consequence of the characteristics of the Colombian labour market. The document responds to the need to deepen the debates on welfare and happiness in organizations and to include the demands of millennials in the reflective and political horizon of the ideas of healthy employment and decent work. In practice, this article seeks to demystify ideas about millennials in Colombia and critically contribute to reflection on intergenerational relations in organizations and salary and welfare models. As a Latin American case, it is an original contribution that avoids the common places and the frivolity with which the insertion of the new generations into the working world has been analysed. Practical implications: In practice, this paper seeks to demystify ideas about millennials in Colombia and critically contribute to reflection on intergenerational relations in organizations and salary and welfare models. Originality/value: As a Latin American case, it is an original contribution that avoids the common places and the frivolity with which the insertion of the new generations into the working world has been analysed. © 2020, Emerald Publishing Limited.
Decent work and healthy employment: a qualitative case study about Colombian millennials
(Emerald Group Publishing Ltd., 2020-01-01) Gallo Ó.; Gonzales–Miranda D.R.; Roman-Calderon J.P.; García G.A.
Purpose: The purpose of this article is to show how a group of Colombian millennials perceive different aspects of working life and how their ideas about job satisfaction, professional expectations and levels of autonomy are related to contemporary demands about inclusion, diversity, equity, autonomy and control. Design/methodology/approach: With this objective, 167 semi-structured interviews were conducted with millennials who work at 10 Colombian companies from the manufacturing and service sectors, located in the five main cities of the country. With a qualitative approach, in the interviews, the research team used a strategy inspired by the technique of generating visual structures associated with grounded theory. Findings: It is concluded that new generations of Colombian workers know of the importance of rewards and autonomy in work and are more critical and less passive in the face of unhealthy working conditions. At the same time, their conduct and speeches are the consequence of the characteristics of the Colombian labour market. The document responds to the need to deepen the debates on welfare and happiness in organizations and to include the demands of millennials in the reflective and political horizon of the ideas of healthy employment and decent work. In practice, this article seeks to demystify ideas about millennials in Colombia and critically contribute to reflection on intergenerational relations in organizations and salary and welfare models. As a Latin American case, it is an original contribution that avoids the common places and the frivolity with which the insertion of the new generations into the working world has been analysed. Practical implications: In practice, this paper seeks to demystify ideas about millennials in Colombia and critically contribute to reflection on intergenerational relations in organizations and salary and welfare models. Originality/value: As a Latin American case, it is an original contribution that avoids the common places and the frivolity with which the insertion of the new generations into the working world has been analysed. © 2020, Emerald Publishing Limited.
Decolorization and mineralization of Diarylide Yellow 12 (PY12) by photo-Fenton process: the Response Surface Methodology as the optimization tool.
(IWA PUBLISHING, 2012-01-01) GilPavas, Edison; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; GilPavas, Edison; Dobrosz-Gomez, Izabela; Angel Gomez-Garcia, Miguel; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
The Response Surface Methodology (RSM) was applied as a tool for the optimization of the operational conditions of the photo-degradation of highly concentrated PY12 wastewater, resulting from a textile industry located in the suburbs of Medellin (Colombia). The Box-Behnken experimental Design (BBD) was chosen for the purpose of response optimization. The photo-Fenton process was carried out in a laboratory-scale batch photo-reactor. A multifactorial experimental design was proposed, including the following variables: the initial dyestuff concentration, the H(2)O(2) and the Fe(+2) concentrations, as well as the UV wavelength radiation. The photo-Fenton process performed at the optimized conditions resulted in ca. 100% of dyestuff decolorization, 92% of COD and 82% of TOC degradation. A kinetic study was accomplished, including the identification of some intermediate compounds generated during the oxidation process. The water biodegradability reached a final DBO(5)/DQO = 0.86 value.
Design and construction of a transducer for bite force registration.
(ELSEVIER SCI LTD, 2009-05-29) Isaza JF; Throckmorton GS; Roldán SI; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
This study describes the development of a system for quantification of human biting forces by (1) determining the mechanical properties of an epoxy resin reinforced with carbon fiber, (2) establishing the transducer's optimal dimensions to accommodate teeth of various widths while minimizing transducer thickness, and (3) determining the optimal location of strain gages using a series of mechanical resistance and finite element (FE) analyses. The optimal strain gage location was defined as the position that produced the least difference in strain pattern when the load was applied by teeth with two different surface areas. The result is a 7.3-mm-thick transducer with a maximum load capacity beyond any expected maximum bite force (1500N). This system includes a graphic interface that easily allows acquisition and registration of bite force by any health-sciences or engineering professional.
Design and construction of a transducer for bite force registration.
(ELSEVIER SCI LTD, 2009-05-29) Isaza JF; Throckmorton GS; Roldán SI; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
This study describes the development of a system for quantification of human biting forces by (1) determining the mechanical properties of an epoxy resin reinforced with carbon fiber, (2) establishing the transducer's optimal dimensions to accommodate teeth of various widths while minimizing transducer thickness, and (3) determining the optimal location of strain gages using a series of mechanical resistance and finite element (FE) analyses. The optimal strain gage location was defined as the position that produced the least difference in strain pattern when the load was applied by teeth with two different surface areas. The result is a 7.3-mm-thick transducer with a maximum load capacity beyond any expected maximum bite force (1500N). This system includes a graphic interface that easily allows acquisition and registration of bite force by any health-sciences or engineering professional.
Designed for resistance to puncture: The dynamic response of fish scales
(ELSEVIER SCIENCE BV, 2019-01-01) Ghods S.; Murcia S.; Ossa E.A.; Arola D.; Ghods S.; Murcia S.; Ossa E.A.; Arola D.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
Natural dermal armors are serving as a source of inspiration in the pursuit of “next-generation” structural materials. Although the dynamic strain response of these materials is arguably the most relevant to their performance as armors, limited work has been performed in this area. Here, uniaxial tension and transverse puncture tests were performed on specimens obtained from the scales of Asian carp over strain rates spanning seven decades, from 10-4 to 103 s-1. The importance of anatomical variations was explored by comparing the performance of scales from the head, middle and tail regions. In both loading orientations, the scales exhibited a significant increase in the resistance to failure with loading rate. The rate sensitivity was substantially higher for transverse loading than for in-plane tension, with average strain rate sensitivity exponents for measures of the toughness of 0.35 and 0.08, respectively. Spatial variations in the properties were largest in the puncture responses, and scales from the head region exhibited the greatest resistance to puncture overall. The results suggest that the layered microstructure of fish scales is most effective at resisting puncture, rather than in-plane tension, and its effectiveness increases with rate of loading. X-ray microCT showed that delamination of plies in the internal elasmodine and stretching of the fibrils were key mechanisms of energy dissipation in response to puncture loading. Understanding contributions from the microstructure to this behavior could guide the development of flexible engineered laminates for penetration resistance and other related applications. © 2018 Elsevier Ltd
Deterministic SIR (Susceptible-Infected-Removed) models applied to varicella outbreaks.
(CAMBRIDGE UNIV PRESS, 2008-05-01) Giraldo JO; Palacio DH; Giraldo JO; Palacio DH; Universidad EAFIT. Departamento de Ciencias; Lógica y Computación
Deterministic SIR models were applied to simulate Susceptible-Infected-Removed and to estimate the threshold condition for varicella outbreaks in children, reported in Medellin, Colombia. The expected numbers of susceptible, infected and removed individuals were compared with observed cases from notification of varicella outbreaks to the local Board of Health and from survey data. The threshold condition was estimated by the basic reproductive ratio and by the relative removal rate, through which measures for preventing and curtailing the outbreaks were identified. The model demonstrated a reasonable fit to the observations, except in two of the six outbreaks which probably reflected under-registration of cases. In order to have prevented these outbreaks, between 4.4% and 52.9% of the susceptible population should have been vaccinated assuming an 85% vaccine effectiveness. Similarly, isolation of affected children should have been increased to between 4.3% and 44.8% per week.
Drug dosage individualization based on a random-effects linear lodel
(TAYLOR & FRANCIS INC, 2012-01-01) Diaz, Francisco J.; Cogollo, Myladis R.; Spina, Edoardo; Santoro, Vincenza; Rendon, Diego M.; de Leon, Jose; Universidad EAFIT. Escuela de Ciencias; Modelado Matemático
This article investigates drug dosage individualization when the patient population can be described with a random-effects linear model of a continuous pharmacokinetic or pharmacodynamic response. Specifically, we show through both decision-theoretic arguments and simulations that a published clinical algorithm may produce better individualized dosages than some traditional methods of therapeutic drug monitoring. Since empirical evidence suggests that the linear model may adequately describe drugs and patient populations, and linear models are easier to handle than the nonlinear models traditionally used in population pharmacokinetics, our results highlight the potential applicability of linear mixed models to dosage computations and personalized medicine. Copyright © Taylor & Francis Group, LLC.
Ejecución de un sistema piloto de tele-radiología en Medellín, Colombia
(Corporacion Editora Medica del Valle, 2006-01-01) García, A.; Isaza, J.F.; Zapata, U.; Roldán, S.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
Objective: To implement a teleradiology pilot system in Medellín city using software for remote access, this allows the communication and interpretation of biomedical images at distance. Materials and methods: Images from different magnetic resonance and computed tomography studies stored in DICOM format were used. Data were transmitted in a point-to-point network using an integrated services digital network (ISDN) line between two radiological diagnostic centers. The system was developed under PC Intel's ×86 architecture, with Windows® 2000 as the operating system. Results: In order to read and visualize images stored in DICOM format, a Java application with functions that allow their manipulation and the option to export them to other formats such as JPEG, TIFF and BMP was developed. Conclusion: The system allows a clinically reliable diagnostic and remote interpretation for modalities such as computed tomography (CT) and magnetic resonance (MR) images, with acceptable response times. © 2006 Corporación Editora Médica del Valle.
Evaluation of the structural behavior of three and four implant-supported fixed prosthetic restorations by finite element analysis.
(ELSEVIER IRELAND LTD, 2012-04-01) Correa S; Ivancik J; Isaza JF; Naranjo M; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
PURPOSE: There is much controversy about the minimum number of implants and maximum cantilever length in mandible prosthetic restoration. Finite elements analysis of three and four implant-supported prostheses was performed to determine the stresses in the superstructure, implants and cortical bone and, therefore, the failure prediction for each restoration. METHODS: An edentulous mandible was modeled from CT scan images. Two finite element models of three and four implant-supported prostheses with cantilever lengths of 10 and 15 mm were created. Occlusal loads in different parts of the superstructure were applied and shear and normal stresses were calculated. RESULTS: Two failure criteria were analyzed: the von Mises criterion for isotropic materials (superstructure and implants) and the Tsai-Wu criterion for transversely isotropic material (cortical bone). Both criteria predict failure in the three implant-supported prosthesis for all cases analyzed. The same applies for the four-implant prosthesis of 15 mm cantilever length. However, four implants and a cantilever length of 10mm passed the failure criteria and were considered safe. CONCLUSIONS: The results from the patient analyzed showed that fixed support prostheses on three implants are not recommended from a structural point of view because they do not adequately support occlusal loads. Excessive stress in the superstructure and the cortical bone can be expected, which would anticipate the failure of the restoration. Fixed support prostheses on four implants with a cantilever length of 10mm properly resist occlusal loading.
Evaluation of the structural behavior of three and four implant-supported fixed prosthetic restorations by finite element analysis.
(ELSEVIER IRELAND LTD, 2012-04-01) Correa S; Ivancik J; Isaza JF; Naranjo M; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
PURPOSE: There is much controversy about the minimum number of implants and maximum cantilever length in mandible prosthetic restoration. Finite elements analysis of three and four implant-supported prostheses was performed to determine the stresses in the superstructure, implants and cortical bone and, therefore, the failure prediction for each restoration. METHODS: An edentulous mandible was modeled from CT scan images. Two finite element models of three and four implant-supported prostheses with cantilever lengths of 10 and 15 mm were created. Occlusal loads in different parts of the superstructure were applied and shear and normal stresses were calculated. RESULTS: Two failure criteria were analyzed: the von Mises criterion for isotropic materials (superstructure and implants) and the Tsai-Wu criterion for transversely isotropic material (cortical bone). Both criteria predict failure in the three implant-supported prosthesis for all cases analyzed. The same applies for the four-implant prosthesis of 15 mm cantilever length. However, four implants and a cantilever length of 10mm passed the failure criteria and were considered safe. CONCLUSIONS: The results from the patient analyzed showed that fixed support prostheses on three implants are not recommended from a structural point of view because they do not adequately support occlusal loads. Excessive stress in the superstructure and the cortical bone can be expected, which would anticipate the failure of the restoration. Fixed support prostheses on four implants with a cantilever length of 10mm properly resist occlusal loading.
Fengycin C produced by Bacillus subtilis EA-CB0015.
(AMER CHEMICAL SOC, 2013-04-26) Villegas-Escobar, Valeska; Ceballos, Isabel; Mira, John J.; Edith Argel, Luz; Orduz Peralta, Sergio; Romero-Tabarez, Magally; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)
Bacillus subtilis EA-CB0015 was isolated from the phyllosphere of a banana plant and tested for its potential to produce bioactive compounds against Mycosphaerella fijiensis. Using a dual plate culture technique the cell-free supernatant of B. subtilis EA-CB0015 produced inhibition values of 89 +/- 1%. The active compounds were purified by solid-phase extraction and HPLC, and their primary structures determined using mass spectrometry and amino acid analysis. A new fengycin isoform, fengycin C, with the amino acid sequence Glu-Orn-Tyr-Thr-Glu-Val-Pro-Gln-Thr-Ile was isolated. The peptidic moiety differs from fengycin B at position 9 and from fengycin A at positions 6 and 9. The beta-hydroxy fatty acyl chain is connected to the N-terminal of the decapeptide and can be saturated or unsaturated, ranging from 14 to 18 carbons. The C-terminal residue of the peptidic moiety is linked to the tyrosine residue at position 3, forming the branching point of the acyl peptide and the eight-membered cyclic lactone.
The global impact of sutures assessed in a finite element model of a macaque cranium
(WILEY-LISS, 2010-09-01) Wang, Qian; Smith, Amanda L.; Strait, David S.; Wright, Barth W.; Richmond, Brian G.; Grosse, Ian R.; Byron, Craig D.; Zapata, Uriel; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
The biomechanical significance of cranial sutures in primates is an open question because their global impact is unclear, and their material properties are difficult to measure. In this study, eight suture-bone functional units representing eight facial sutures were created in a finite element model of a monkey cranium. All the sutures were assumed to have identical isotropic linear elastic material behavior that varied in different modeling experiments, representing either fused or unfused sutures. The values of elastic moduli employed in these trials ranged over several orders of magnitude. Each model was evaluated under incisor, premolar, and molar biting conditions. Results demonstrate that skulls with unfused sutures permitted more deformations and experienced higher total strain energy. However, strain patterns remained relatively unaffected away from the suture sites, and bite reaction force was likewise barely affected. These findings suggest that suture elasticity does not substantially alter load paths through the macaque skull or its underlying rigid body kinematics. An implication is that, for the purposes of finite element analysis, omitting or fusing sutures is a reasonable modeling approximation for skulls with small suture volume fraction if the research objective is to observe general patterns of craniofacial biomechanics under static loading conditions. The manner in which suture morphology and ossification affect the mechanical integrity of skulls and their ontogeny and evolution awaits further investigation, and their viscoelastic properties call for dynamic simulations. © 2010 Wiley-Liss, Inc.
Implementation of system operation modes for health management and failure prognosis in cyber-physical systems
(MDPI AG, 2020-01-01) Ruiz-Arenas, S.; Rusák, Z.; Mejía-Gutierrez, R.; Horváth, I.; Universidad EAFIT. Departamento de Ingeniería de Diseño; Ingeniería de Diseño (GRID)
Cyber-physical systems (CPSs) have sophisticated control mechanisms that help achieve optimal system operations and services. These mechanisms, imply considering multiple signal inputs in parallel, to timely respond to varying working conditions. Despite the advantages that control mechanisms convey, they bring new challenges in terms of failure prevention. The compensatory action the control exerts cause a fault masking effect, hampering fault diagnosis. Likewise, the multiple information inputs CPSs have to process can affect the timely system response to faults. This article proposes a failure prognosis method, which combines time series-based forecasting methods with statistically based classification techniques in order to investigate system degradation and failure forming on system levels. This method utilizes a new approach based on the concept of the system operation mode (SOM) that offers a novel perspective for health management that allows monitoring the system behavior, through the frequency and duration of SOMs. Validation of this method was conducted by systematically injecting faults in a cyber-physical greenhouse testbed. The obtained results demonstrate that the degradation and fault forming process can be monitored by analyzing the changes of the frequency and duration of SOMs. These indicators made possible to estimate the time to failure caused by various failures in the conducted experiments. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

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