Nunes L.C.S.,University Federal Fluminense
Optics and Lasers in Engineering | Year: 2011
The aim of this work is to estimate two important material properties of the polytetrafluoroethylene (PTFE) polymer by means of a single experimental test. The displacement fields around a crack tip are used for estimating the modulus of elasticity (or, Youngs modulus) and Poissons ratio. These parameters are evaluated by fitting linear fracture mechanic expression of displacement fields in the vicinity of the crack, for mode I, to the experimental data. Measurements of these displacements are carried out using digital image correlation (DIC) method. In this way, the experimental procedure is conducted by loading a double-edge-cracked plate specimen. In order to validate the results, two available experimental tests have been performed. The modulus of elasticity is determined by means of the tensile test, using a standard test machine. Moreover, the Poissons ratio is obtained by measuring lateral compressive and longitudinal extensional strain using DIC method. © 2011 Elsevier Ltd. All rights reserved.
Felix S.P.,Federal University of Rio de Janeiro |
Pereira Lopes F.R.,Federal University of Rio de Janeiro |
Marques S.A.,University Federal Fluminense |
Martinez A.M.B.,Federal University of Rio de Janeiro
Microsurgery | Year: 2013
Purpose The aim of this study was to evaluate and compare the effectiveness of classical suture and sutureless repair with fibrin glue, by using or not a resorbable collagen tube, after sciatic nerve transection. Material and methods Twenty-five mice were used in this study, divided in five groups. They were submitted to sciatic nerve transection and immediate repair of the nerve stumps by either direct suture or fibrin glue adhesion or by the tubulization technique in which the nerves stumps were sutured or glued to a collagen tube (experimental groups). A control group was designed as the best regeneration condition, by using a crush lesion (control group). After eight weeks, the regenerated nerves were processed for light and electron microscopy. Motor function analysis was performed using the sciatic functional index. Results Quantitative analysis of regenerated nerves between experimental groups showed that those repaired by direct contact of the stumps with fibrin glue showed significant increase in the myelin and fiber areas. The tubulization groups, repaired by suture or fibrin glue, provided similar results. G-ratio analysis revealed that the regenerating axons of all experimental groups presented values equivalent to control (crushing group). Conclusions These results suggest that the use of fibrin glue in nerve repair by either direct coaptation or tubulization is an alternative to conventional suture repair, particularly in case of small-size-nerve reconstruction. © 2013 Wiley Periodicals, Inc. Microsurgery 33:468-477, 2013. Copyright © 2013 Wiley Periodicals, Inc.
Bello M.L.,Federal University of Rio de Janeiro |
Aridio M.,Federal University of Rio de Janeiro |
Vieira B.A.,Federal University of Rio de Janeiro |
Dias L.R.S.,University Federal Fluminense |
And 4 more authors.
PLoS ONE | Year: 2015
Layered drug delivery carriers are current targets of nanotechnology studies since they are able to accommodate pharmacologically active substances and are effective at modulating drug release. Sodium montmorillonite (Na-MMT) is a clay that has suitable properties for developing new pharmaceutical materials due to its high degree of surface area and high capacity for cation exchange. Therefore Na-MMT is a versatile material for the preparation of new drug delivery systems, especially for slow release of protonable drugs. Herein, we describe the intercalation of several amine-containing drugs with Na-MMT so we can derive a better understanding of how these drugs molecules interact with and distribute throughout the Na-MMT interlayer space. Therefore, for this purpose nine sodium montmorillonite/amine-containing drugs complexes (Na-MMT/drug) were prepared and characterized. In addition, the physicochemical properties of the drugs molecules in combination with different experimental conditions were assessed to determine how these factors influenced experimental outcomes (e.g. increase of the interlayer spacing versus drugs arrangement and orientation). We also performed a molecular modeling study of these amine-containing drugs associated with different Na-MMT/drug complex models to analyze the orientation and arrangement of the drugs molecules in the complexes studied. Six amine-containing drugs (rivastigmine, doxazosin, 5-fluorouracil, chlorhexidine, dapsone, nystatin) were found to successfully intercalate Na-MMT. These findings provide important insights on the interlayer aspect of the molecular systems formed and may contribute to produce more efficient drug delivery nanosystems. © 2015 Bello et al.
Leta F.R.,University Federal Fluminense |
Clua E.,University Federal Fluminense |
Junior J.R.S.,University Federal Fluminense |
Moraes R.,University Federal Fluminense |
And 2 more authors.
Advanced Structured Materials | Year: 2015
While 3D stereoscopy can drastically increase the immersion in virtual environments, many features that were not relevant in other fields become important and should be considered in scientific visualization. Particularly, in virtual environments where there is a single object, the lack of spatial references makes it difficult to navigate and manipulate virtual elements. This work proposes a methodology for borehole breakouts and fracture visualization and analysis, using 3D stereoscopy. This is important in order to increase the precision of the environmental manipulation, considering important design and visualization concepts for a pipeline. With our proposal, tools and system manipulations that were complex to be used, due the nature of single elements in the environment, become much easier to operate. © Springer International Publishing Switzerland 2015.