Effect of home-bleaching gels modified by calcium and/or fluoride and the application of nano-hydroxyapatite paste on in vitro enamel erosion susceptibility

This in vitro study compared the effect of bleaching agents modified by the addition of calcium and/or fluoride and the application of a nano-hydroxyapatite paste after bleaching, on the susceptibility of enamel to erosion. Bovine enamel cylindrical samples (3 mm diameter) were assigned to six groups (n = 20 specimens/group) according to the bleaching agent: no bleaching (C-control), 7.5% hydrogen peroxide gel (HP), HP with 0.5% calcium gluconate (HP+Ca), HP with 0.2% sodium fluoride (HP+F), HP with calcium and fluoride (HP+Ca+F) and HP followed by the application of a nano-hydroxyapatite agent (HP+NanoP). The gels were applied on the enamel surface (1 h) followed by cyclic erosive challenges (Sprite Zero®-2 min), for 14 days. The paste was applied after bleaching for 5 min (HP+NanoP). The enamel surface alteration was measured by contact profilometry (µm) (after 7 and 14 days). C-control (mean ± SD: 2.29 ± 0.37 at 7 days/4.86 ± 0.72 at 14 days) showed significantly lower loss compared to the experimental groups. HP+Ca (3.34 ± 0.37/6.75 ± 1.09) and HP+F (4.49 ± 0.92/7.61 ± 0.90) presented significantly lower enamel loss than HP (4.18 ± 0.50/10.30 ± 1.58) only for 14 days and HP+Ca+F (4.92 ± 1.03/8.12 ± 1.52) showed values similar to the HP+F group. The HP+NanoP (5.51 ± 1.04/9.61 ± 1.21) resulted in enamel loss similar to the HP after 14 days. It was found that 7.5% hydrogen peroxide increased the susceptibility of enamel to erosion. The addition of calcium or fluoride to the bleaching gel reduced the erosion effect, while the nano-hydroxyapatite agent did not provide any protective effect.

In vitro effect of low-fluoride toothpastes containing sodium trimetaphosphate on enamel erosion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potential use of polyacrylamide for soil erosion control in Brazil

Since soil erosion is currently a worldwide threat, its control has become a necessity. The performance and effectiveness of synthetic organic polymers such polyacrylamide (PAM), have been intensively studied, especially for erosion control in temperate climate conditions. In tropical regions, however, where climatic conditions are usually severe, very little research has been conducted. The Brazilian region is a good example, where few papers on this subject exist. In addition to the severe climatic conditions, careless land use has been prevalent for many years. The use of PAM for erosion control in Brazilian soils may be a good option to minimize the impacts of the soil degradation process, but more research is required to optimize its application.

Using landscape metrics to analyze micro-scale soil erosion processes

Methods of recording soil erosion using photographs exist but they are not commonly considered in scientific studies. Digital images may hold an expressive amount of information that can be extracted quickly in different manners. The investigation of several metrics that were initially developed for landscape ecology analysis constitutes one method. In this study we applied a method of landscape metrics to quantify the spatial configuration of surface micro-topography and erosion-related features, in order to generate a possible complementary tool for environmental management. In a 3.7 m wide and 9.7 m long soil box used during a rainfall simulation study, digital images were systematically acquired in four instances: (a) when the soil was dry; (b) after a short duration rain for initial wetting; (c) after the first erosive rain; and (d) after the 2nd erosive rain. Thirteen locations were established in the box and digital photos were taken at these locations with the camera positioned at the same orthogonal distance from the soil surface under the same ambient light intensity. Digital photos were converted into bimodal images and seven landscape metrics were analyzed: percentage of land, number of patches, density of patches, largest patch index, edge density, shape index, and fractal dimension. Digital images were an appropriate tool because they can generate data very quickly. The landscape metrics were sensitive to changes in soil surface micro-morphology especially after the 1st erosive rain event, indicating significant erosional feature development between the initial wetting and first erosive rainfall. The method is considered suitable for spatial patterns of soil micro-topography evolution from rainfall events that bear similarity to landscape scale pattern evolution from eco-hydrological processes. Although much more study is needed for calibrating the landscape metrics at the micro-scale, this study is a step forward in demonstrating the advantages of the method.

Mapeamento de ocorrências de eventos perigosos no município de Santos SP: integração com dados de vulnerabilidade socioambiental

This study is based on the mapping of occurrences associated with social vulnerability and natural risks, which refer to the resilience of populations and territories, regarding natural hazards associated with the functioning of natural systems (eg, earthquakes, flood, mass movements). According to UNISDR (2014), the state of São Paulo is a reference in working with Urban Resilience and Disaster in the Resilient Cities Campaign (2014), considering the high investment in Risk Areas Mapping and Public Education Campaigns implemented by the Civil Defense. Thus, this study aims to mapping the occurrence of events related to Tree Falls, Erosion, Landslides, Irregular Housing, Rocky Blocks Falls, Wall Falls, Unroofing and Irregular Construction, attended by the Civil Defense in the city of Santos, São Paulo State, from 2011 to 2014. Thereafter, correlated analyzes to the Environmental Vulnerabilities were generated. The Environmental Vulnerability databases used in this dissertation compose the results of the CNPQ Project - Environmental Vulnerability Mapping of the State of Sao Paulo - Brazil: a methodological contribution of Freitas (2013) and Bortolettoet al (2014), with information collected from the 2010 Census (IBGE, 2010), on a census sectors scale. The adopted methodological procedure involves document analysis followed by data integration in Geographic Information System, through algorithms analysis and mapscrossing.The results obtained in Maps of Social and Environmental Vulnerability Occurrences presented areas of High or Very High Vulnerability. The main variables obtained with such characteristics are Irregular Housing, Landslides and Rocky Blocks Falls, which was associated with hilly terrain formations, with slopes above 30%. To the areas of Medium, Low and Very Low Vulnerability were associated the variables Tree Falls, Wall Falls, Erosion, Unroofing and Irregular Construction, which are spatially distributed without an...

Análiseda percolação de água em barragem de terra pelo método da eletrorresistividade

Interventions in nature made by man are very common since the beginnings of human history, especially in the case regarding the storage of water. The construction of dams have been and still are fundamental in maintaining human life due to the vital importance that water plays. The size of these structures vary according to need, such as water catchment, fish-farming or electricity generation. Embankment dams are the most common type of these structures. Can be defined as dams natural material obtained from loan chambers located near the dam site. This type of barrier may be divided into earth dams and rockfill dams. The study area covers an earth dam located in Cordeirópolis (SP) and is essentially composed of diabases altered soil of the Serra Geral Formation of the Paraná Basin. With the aid of geophysics, more specifically of the Electrical Resistivity method, the aim is to check any water infiltration zones in the dam's body. Given the risks associated with water seepage in earth dams, that may generate breakdown structures, erosion, and consequently accidents and / or harmful factors in the nearby areas. One of the main structural problems married by water infiltration is the possible generation of pipes that could jeopardize the dam structure. This work aims to contribute towards the evaluation of the effectiveness of using an indirect technique of research and monitoring in aid to direct research techniques such as piezometers and drive stakes. The results are presented in the form of 2D and 3D geophysical models, the analysis shows a low resistivity zone with typical values of the presence of humidity originating upstream of the dam and downstream bottleneck trend, that are the basis for interpretation by percolation or not water in the dam

Análise morfométrica e definição do potencial de uso do solo da microbacia do rio Veríssimo, Veríssimo - MG

The morphometric study in watersheds is a key part to managing watersheds, because from the morphometric indices can determine the risks and potential of each watershed and assess environmental impacts on them generated mainly by human activities. This study aimed to characterize the watershed of the river Verissimo, located in the municipality of Verissimo - MG, analyze morphometric indices and propose how best to use the soil to minimize erosion impacts to resources hídricos.Foi used digital charts 1:100,000 scale and AutoCAD software for the quantification of vector data. The watershed has an area of 146.055 km2 , 55.902 km perimeter. According to the morphometric indices is considered 5th order, highly branched, slightly elongated format of little risk to floods occur, its main channel corresponds to 28.541 kilometers and has undulated, with an average slope of 8.59%. Through the results of morphometric indices and roughness coefficient, shows the potential of watershed land use on pastures for livestock, and soil conservation practices and water to minimize the impacts of erosion and contamination of water resources.

Geoprocessamento de variáveis morfométricas para caracterização da microbacia do Córrego do Petiço

This study aims to perform the morphometric characterization of the watershed stream Petiço, Botucatu-SP, through techniques of GIS by GIS IDRISI Selva and Charter planialtimetric Botucatu (SF-22-ZB-VI-3) , edited by IBGE (1969), scale 1: 50000 for ranking the drainage network and the morphometric analysis. The variables analyzed were the dimensions, the relief pattern, pattern of the drainage network and the shape variables. The results show that related to how the watershed has an oblong shape with environmental interpretation with low tendency to flooding and erosion. The sinuosity index of 1.22 shows that the channels of the micro tend to be somewhat sinuous, which allows to infer that is permeable soil with good water infiltration. Based on the results of the morphometric variables was found that the watershed is in good condition of conservation, however, presents certain risks of susceptibility to erosion, and environmental degradation in some points, being fundamental to the maintenance of vegetation cover, in view of the roughness coefficient (Rn). Thus, the evaluation of morphometric characteristics in the study watershed constitutes an important tool in conjunction with the use of GIS and Geographic Information Systems makes possible the planning and management of natural resources aimed at their conservation.

Genetic erosion risk by environmental and antropic factor applied on strategies for Lychnophora ericoides conservation

This study evaluated the genetic erosion risk factors and the strategic points for the conservation of Lychnophora ericoides population in “Paraíso Perdido” farm, Serra da Canastra (20° 37’ 54” S; 46° 19’ 37” W; 833 m height) in São João Batista do Glória City, Minas Gerais State, Brazil. The number of young and adult plants, the soil and the phenology were evaluated in two sample areas of 125 m2. Information about the species utilization was obtained with local informants. Data on the region were obtained through literature review, in loco evaluation, GPS and geo-referenced map. In addition, local use of the plant for mixtures of drug was evaluated. According to the results obtained, the soil of the population is lithic with a weathered portion of frank-sandy texture, very acidic and dystrophic. The population density is 0.16 individuals/m2, 0.078 young/adult plant. The predominant phenophase was fruiting (100% plants) followed by flowering (21.62% plants). The local community uses the leaves of the plant in the form of hydroalcoholic extracts, as anti-inflammatory. Based on the evaluated parameters, the population is at 73% risk of genetic erosion. The detected key points were the development of activities including the participation of the local community for habitat protection as well as germplasm collection, seedlings production and reintroduction, together with environmental education, supervision, and reduction in the propensity for fire.

Identificação de cavidades em voçoroca por meio da aplicação do método geofísico da eletrorresistividade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)