University of Minas Gerais

Belo Horizonte, Brazil

University of Minas Gerais

Belo Horizonte, Brazil
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Barreto M.F.O.,University of Minas Gerais | Barreto M.F.O.,University of Itaúna | Brandao P.R.G.,Federal University of Minas Gerais
Brick and Block Masonry: Trends, Innovations and Challenges - Proceedings of the 16th International Brick and Block Masonry Conference, IBMAC 2016 | Year: 2016

The need for research and characterization of materials aimed at the construction has been growing due to the need for proper selection of materials, based on the performance of the system under study. Thus, this paper proposes to go a little further on the microstructural characterization of surfaces and interfaces of Portland cement mortars used for flooring in construction works. The most important innovation in the field of scanning electron microscopy in recent years was the introduction of high-resolution SEM. Using scanning electron microscope high-resolution (SEM—FEG), will be used to clarify the micro and nanometric details of cementitious material in Portland cement mortars that have in their composition, and proved extremely important in the characterization of cementitious materials in the case of this study, Portland cement mortars. The technique of sample preparation is relatively simple compared to other devices and allows the analysis of samples in a natural state which ensures ideal conditions for the characterization of the material, moreover, the quality of the photomicrographs is substantially better than the conventional microscopes combined with the chemical microanalysis by energy-dispersive (X-ray) spectrometer (EDS), which allows a substantial advance in the search and characterization of cementitious materials. In photomicrographs using high resolution scanning electron microscope (SEM—FEG), increases of about 80 thousand times with great quality were possible, in this paper, we can see above, photomicrographs with an increase of up to 50 thousand times, which enables the visualization of nanopores in mortar matrix. Photomicrographs made in SEM—FEG dual FIB 3D and SEM—FEG Quanta confirm the predominance of euhedral crystals of ettringite in the block—ceramic mortar, characterized by their morphology of hexagonal crystals acicular interface region, and we can also check the lamellar morphology characteristic of portlandite in the top view of the mortar. © 2016 Taylor & Francis Group, London.

Barreto M.F.O.,University of Minas Gerais | Barreto M.F.O.,University of Itaúna | Brandao P.R.G.,Federal University of Minas Gerais
Brick and Block Masonry: Trends, Innovations and Challenges - Proceedings of the 16th International Brick and Block Masonry Conference, IBMAC 2016 | Year: 2016

The need for research and characterization of materials aimed at the construction has been growing due to the need for proper selection of materials, based on the performance of the system under study. In this sense this paper proposes to go further in the characterization and micro nanostructural surfaces and interfaces of Portland cement mortars used for flooring in civil works in a new way and the use of Atomic Force Microscopy (AFM) as a tool of characterization of Portland cement mortar. In recent decades, many new aspects of CSH were revealed with the advances in analytical techniques and application of new methods such as Nuclear Magnetic Resonance (NMR) and atomic force microscopy (AFM), the latter is the subject of this research. The nanostructure of CSH has been the subject of much research, but it is still not clearly understood, some suggested models point ranging from colloidal “layers—sheets”. The atomic force microscopy (AFM) was used in this work in an unprecedented way for cementitious materials, in the case of this study, Portland cement mortars. There are no bibliographic reports of successful attempts to characterize these materials using such important technique to nanostructures. The preparation of the samples showed a positive surprise because as we had no previous parameters, we chose the simplest possible preparation that consisted of embedding a fragment of fractured mortar in Bakelite and do the surface polishing. The topographic characterization is important because it shows the classical morphology of portlandite and calcite in the samples at the nanometer scale. These topographical micrographs and three-dimensional topographic profiles give us an exact picture of the morphology of cementitious materials in the interface ceramic block/mortar, interface roughcast mortar/mortar coating and top view of the mortar, being a powerful and effective characterization tool for micro and nanostructural. © 2016 Taylor & Francis Group, London.

Teles D.C.,University of Minas Gerais | Pimenta A.C.S.,University of Minas Gerais | Matinaga F.M.,University of Minas Gerais
Optics InfoBase Conference Papers | Year: 2016

Faraday rotation has been investigated in nonlinear materials and systems like GaAs microcavity lasers. We present in this work heavy and light hole polaritons effect on the Faraday rotation without external magnetic field. © OSA 2016.

Pino N.,University of Antioquia | Sitthisa S.,University of Oklahoma | Tan Q.,University of Oklahoma | Souza T.,University of Minas Gerais | And 2 more authors.
Journal of Catalysis | Year: 2017

The conversion of furfural has been investigated in vapor and liquid phases over a series of supported monometallic Pd and bimetallic Pd-Fe catalysts. Over the monometallic Pd/SiO2 catalyst, the decarbonylation reaction dominates, yielding furan as the main product. By contrast, over the bimetallic Pd-Fe/SiO2 catalyst a high yield of 2-methylfuran is obtained with much lower yield to furan. Interestingly, changing the catalyst support affects the product distribution. For instance, using γ-Al2O3 instead of SiO2 as support of the bimetallic catalyst changed the dominant product from 2-methylfuran to furan. That is, Pd-Fe/γ-Al2O3 behaves more like monometallic Pd/SiO2 than bimetallic Pd-Fe/SiO2. A detailed characterization of the catalysts via XPS, XRD, and TEM indicated that a Pd-Fe alloy is formed on the SiO2 support but not on the γ-Al2O3 support. Theoretical density functional theory calculations suggest that on the Pd-Fe alloy binding of the furan ring to the surface is weakened compared to on pure Pd. This weakening disfavors the ring hydrogenation and decarbonylation paths, while the oxophilic nature of Fe atoms enhances the interaction of the C[dbnd]O and the OH groups with the metal surface, which favors the C[dbnd]O hydrogenation and C–O bond cleavage paths. The presence of the solvent has a less pronounced effect, but clearly has a stronger inhibition on C–C bond cleavage (decarbonylation to furan) than on C–O bond cleavage (hydrogenolysis to methylfuran). © 2017 Elsevier Inc.

Reis F.M.,University of Minas Gerais | Petraglia F.,University of Siena
Human Reproduction Update | Year: 2013

Background: The recruitment of immune cells by chemokines and the regulation of endometrial cell apoptosis are critical aspects of endometriosis biology. Here, we review the local (paracrine) and systemic hormone (endocrine) modulation of these two specific, but highly related phenomena. Methods: We searched Pubmed for items published in English between September 1991 and September 2011 and selected the studies evaluating the effects of hormones on chemokines or apoptosis in normal human endometrium and endometriosis. Results: Estradiol has proinflammatory and antiapoptotic effects in endometrial cells, and these effects appear to be exacerbated in women with endometriosis. In these women, physiological estradiol concentrations are able to induce an enhanced inflammatory response mediated by local chemokine production and to reinforce mechanisms of cell survival mediated by extracellular signal-regulated kinases and Bcl-2. The main effect of progestogens is to inhibit interleukin-8 and other chemokines in stromal cells from both eutopic and ectopic endometrium. Progesterone is also effective in inducing apoptosis in endometrial and endometriotic cells through the inhibition of Bcl-2 and nuclear factor-kB. Conclusions: Estrogens and progestogens modulate chemotaxis and apoptosis in human endometrium and endometriotic cells and tissues. These endocrine and paracrine pathways are perturbed in women with endometriosis, contributing to inflammatory responses, abnormal tissue remodeling, therapeutic refractoriness and disease persistence. Ultimately, they promote adhesion formation and the clinical symptoms of pelvic pain and infertility. A more detailed understanding of the molecular mechanisms involved will offer new opportunities for novel pharmacological strategies to diagnose and treat endometriosis. © The Author 2013.

Carvalho H.,University of Minas Gerais | Fakury R.H.,University of Minas Gerais | Vilela P.M.L.,University of Minas Gerais
Latin American Journal of Solids and Structures | Year: 2017

The Hercílio Luz suspension bridge, built in 1926, has been out of service since 1991 due to high corrosion levels and structural element impairment. A complete rehabilitation project was developed which included the replacement of the impaired items and foundation strengthening. For this, an auxiliary structure was employed to support the central span during the rehabilitation process. A carefully studied load transfer process, where the central span loading is transferred from the eye-bar towards the auxiliary structure will be performed. For this purpose, a synchronized jacking sequence will be used, which was predefined by means of numerical model analysis. All structural elements had their designs evaluated and some geometric changes were implemented. This paper presents all the methodology developed in the rehabilitation project of Hercilio Luz bridge, as well as the development stages up to the present date. © 2017, Brazilian Association of Computational Mechanics. All rights reserved.

Nezhat F.R.,Mount Sinai School of Medicine | Pejovic T.,Oregon Health And Science University | Reis F.M.,University of Minas Gerais | Guo S.-W.,Shanghai JiaoTong University
International Journal of Gynecological Cancer | Year: 2014

Objectives: The objectives of this study were to evaluate the current evidence of the association of endometriosis and subsequent carcinoma of the ovary and to contextualize this evidence into daily practice issues. Methods: This study is a critical review of observational and in vitro studies. Results: Although the lifetime risk for ovarian cancer is low in general population and remains low in the broad spectrum of endometriosis, there may be clusters of individuals at higher risk of oncogenesis, whose identification would allow individualized surveillance and prophylactic interventions. Prevalence studies show that specific subtypes of ovarian cancer predominate in women with endometriosis. This has been validated in pathogenetic, genomic, immunobiologic, and hormonal studies. Conclusions: Taken together, these data provide a strong rationale for identifying, monitoring, counseling, and treating women with endometriosis who are at highest risk for cancer conversion. Copyright © 2014 by IGCS and ESGO.

Reis F.M.,University of Minas Gerais | Luisi S.,University of Siena | Abro M.S.,University of Sao Paulo | Rocha A.L.L.,University of Minas Gerais | And 5 more authors.
Human Reproduction | Year: 2012

Background Activin A is a growth factor, produced by the endometrium, whose actions are modulated by the binding protein follistatin. Both proteins are detectable in the peripheral serum and their concentrations may be increased in women with endometriosis. The present study was designed to evaluate whether serum levels of activin A and follistatin are altered, and therefore have a potential diagnostic value, in women with peritoneal, ovarian and deep infiltrating endometriosis. Methods We performed a multicenter controlled study evaluating simultaneously serum activin A and follistatin concentrations in women with and without endometriosis. Women with endometriosis (n 139) were subdivided into three groups: peritoneal endometriosis (n 28); ovarian endometrioma (n 61) and deep infiltrating endometriosis (n 50). The control group (n 75) consisted of healthy women with regular menstrual cycles. Blood samples were collected from a peripheral vein and assayed for activin A and follistatin using commercially available enzyme immunoassay kits. Results The ovarian endometrioma group had serum activin A levels significantly higher than healthy controls (0.22 ± 0.01 ng/ml versus 0.17 ± 0.01 ng/ml, P < 0.01). None of the endometriosis groups had serum follistatin levels which were significantly altered compared with healthy controls; however, levels found in the endometrioma group (2.34 ± 0.32 ng/ml) were higher than that in the deep endometriosis group (1.50 ± 0.17 ng/ml, P < 0.05). The area under the receiver operating characteristic curve of activin A was 0.700 (95 confidence interval: 0.6050.794), while that of follistatin was 0.620 (95 confidence interval: 0.5100.730) for the diagnosis of ovarian endometrioma. The combination of both markers into a duo marker index did not improve significantly their diagnostic accuracy. Conclusions The present study demonstrated that serum activin A and follistatin are not significantly altered in peritoneal or deep infiltrating endometriosis and have limited diagnostic accuracy in the diagnosis of ovarian endometrioma. © 2012 The Autho.

Ciarmela P.,Marche Polytechnic University | Islam M.S.,Marche Polytechnic University | Reis F.M.,University of Minas Gerais | Reis F.M.,National Institute of Hormones and Womens Health | And 5 more authors.
Human Reproduction Update | Year: 2011

Background: Growth factors are proteins secreted by a number of cell types that are capable of modulating cellular growth, proliferation and cellular differentiation. It is well accepted that uterine cellular events such as proliferation and differentiation are regulated by sex steroids and their actions in target tissues are mediated by local production of growth factors acting through paracrine and/or autocrine mechanisms. Myometrial mass is ultimately modified in pregnancy as well as in tumour conditions such as leiomyoma and leiomyosarcoma. Leiomyomas, also known as fibroids, are benign tumours of the uterus, considered to be one of the most frequent causes of infertility in reproductive years in women. Methods: For this review, we searched the database MEDLINE and Google Scholar for articles with content related to growth factors acting on myometrium; the findings are hereby reviewed and discussed. RESULTS: Different growth factors such as epidermal growth factor (EGF), transforming growth factor-α (TGF-α), heparin-binding EGF (HB-EGF), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), platelet-derived growth factor (PDGF) and TGF-β perform actions in myometrium and in leiomyomas. In addition to these growth factors, activin and myostatin have been recently identified in myometrium and leiomyoma. Conclusions: Growth factors play an important role in the mechanisms involved in myometrial patho-physiology. © The Author 2011. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.

Alencar-Silva T.,University of Minas Gerais | Maillard P.,University of Minas Gerais
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

Riparian forests play an important role in the ecological balance of river ecosystems. Given the narrow nature of these environments, medium resolution sensors such as Landsat have limited use. Conversely, products obtained from high-resolution images, such as Ikonos-2, have wide applications in riparian forest studies. The objective of this article is to describe a methodology for delineating riparian areas and extracting their biophysical parameters from an Ikonos scene. The methodology is divided into two stages. Firstly, the image is segmented into a riparian forest class and non-riparian classes using a segmentation algorithm and a river-based buffer. The segmentation package MAGIC (Map Guide Image Classification) was used to separate the riparian forest zones from the rest. In the second phase, texture features derived the co-occurrence matrix were used to estimate the biophysical parameters of the riparian forest. Allometric measurements were made in 70 plots of riparian area from both sides of the Pandeiros River, located in Northern Minas Gerais, Brazil. These plots were used to calibrate and validate our models based on texture parameters. The forest structure variables included height, diameter at breast height, basal area, stem density, volume, canopy openness and leaf area index which were acquired by direct measurements in the field. The results show that MAGIC segmented the riparian environment with an accuracy of more than 85% when compared with the map obtained by visual image interpretation. The best results for modeling riparian structure were obtained respectively for volume and basal area (R2=0.66 and R2=0.61) using Angular Second Moment, Entropy, Infrared band, distance analysis of four pixels and a window of 11×11 pixels.

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