Desempenho mecânico e ambiental de concretos e argamassas de cimento Portland com substâncias minerais, orgânicas e fotocatalíticas

Orientador: Prof. Dr. Kleber Franke PortellaTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia e Ciência dos Materiais - PIPE. Defesa: Curitiba, 30/10/2014Inclui referênciasÁrea de concentração: Engenharia e ciência de materiaisResumo: Um dos grandes problemas da sociedade moderna é a poluição do meio ambiente, seja pelo elevado volume de cimento produzido e consumido diariamente, pelos gases poluentes oriundos de veículos automotores e até mesmo pela quantidade de resíduos depositados a céu aberto por falta de reuso. Diante disto, tem-se uma constante busca por novos métodos e materiais sustentáveis, a fim de reduzir e/ou eliminar este impacto ambiental. Entre as técnicas promissoras, que permite a decomposição de poluentes orgânicos e inorgânicos e os transforma em substâncias menos agressivas e sais minerais, tem-se a fotocatálise. Outra possibilidade é a utilização de resíduos, assim como matéria-prima de baixo valor agregado e de grande volume no Brasil, na produção de concretos, propiciando a redução do consumo de cimento, e portanto, diminuindo a geração de gases poluentes. Assim, esta pesquisa está dividida em duas metodologias: desenvolvimento de misturas cimentícias com adições minerais do tipo cinza da casca de coco verde (CC) e adições orgânicas de fibras de coco (FC) e de sisal (FS) e, também, o desenvolvimento de aparato para a verificação da eficiência fotocatalítica em argamassas produzidas com nano-dióxido de titânio (TiO2) em diferentes teores. A metodologia empregada para verificar a viabilidade de utilização dos insumos em artefatos de concreto para redes de distribuição de energia em área litorânea e industrial foi: a caracterização da matéria-prima e das misturas cimentícias, como desempenho mecânico à compressão axial, à tração por compressão diametral e módulo de elasticidade estático, propriedades físicas, permeabilidade, durabilidade, microestrutura pós ruptura dos CPs (corpos de prova) envelhecidos e da armadura, além da perda de espessura da armadura. Para o acompanhamento da durabilidade, os CPs de concreto foram envelhecidos em câmaras de intemperismo acelerado, submetidos a ciclos de molhagem e secagem a temperaturas de até 40 °C em atmosfera agressiva de névoa salina e gás anidrido sulfuroso, que simularam condições do meio industrial e marinho. Para uma análise comparativa, alguns CPs foram acondicionados em dessecador, tornando-se esta condição como referência. A durabilidade foi avaliada pela técnica de potencial de corrosão da armadura em equipamento potenciostato/galvanostato ao longo de mais de 550 dias. Não houve diferença significativa nos potenciais obtidos para as diferentes dosagens. Os resultados obtidos indicaram uma alta probabilidade de corrosão para a atmosfera salina e, também, para o sulfato; no entanto, estes valores foram menos eletronegativos. Quanto às adições de FC, FS e CC, os resultados obtidos indicaram que é possível utilizá-las como insumos na produção de concretos e/ou argamassas, propiciando a redução do custo final de artefatos e de impactos ambientais. A redução do cimento, principal colaborador no custo do concreto e poluição ambiental, quando da utilização das melhores dosagens, atingiu valores de 4,3 e de 1,7%, respectivamente, para as FC e FS; e de 3,3% para a CC. Já o potencial fotocatalítico das argamassas com TiO2 foi analisado pela redução na concentração dos gases NOx e SO2 em uma câmara com ação ultravioleta. Os dados obtidos comprovaram uma oxidação entre 30 e 40% na concentração de NOx e de 28 a 43% para o SO2, demonstrando ser também uma alternativa para a despoluição do ar. Palavras-chave: fotocatálise, concreto com fibras de coco e sisal, potencial de corrosão, cloreto e sulfato, poluição atmosféricaAbstract: A major problem of modern society is the pollution of the environment, due to the high volume of cement produced and consumed daily by gaseous pollutants come from motor vehicles and even the amount of waste deposited in the open for lack of reuse. This, there is a constant search for new sustainable methods and materials in order to reduce and/or eliminate this environmental impact. Among the promising techniques that allows the decomposition of organic and inorganic pollutants transforming them into less harmful substances and minerals has photocatalysis. Another possibility is the use of waste as raw material of low value and high volume in Brazil, in the production of concrete, leading to reduction in cement consumption, and thus reducing the generation of greenhouse gases. Thus, this research is divided into two methodologies: development of cement mixtures with mineral additions kind of coconut husk ash (CC) and organic additions of coconut fibers (FC) and sisal (FS), and also development of supply physical to check photocatalytic efficiency of mortars produced with nano-titanium dioxide (TiO2) in different percentages. The methodology used to verify the feasibility of using the inputs into concrete artifacts for power distribution networks in marine and industrial area was: characterization of the raw material and mixtures by cement such as mechanical performance to axial compression, tensile strength by diametrical compression and static modulus of elasticity, physical properties, permeability, durability, microstructure after rupture of CPs and the armor, and the loss of thickness of the armor. To monitor the durability of concrete CPs were aged in accelerated weathering chambers, subjected to cycles of wetting and drying at temperatures up to 40 °C in an atmosphere of aggressive salt spray and sulfur dioxide gas, which simulated conditions of the industrial environment and marine. For a comparative analysis were placed CPs in a desiccator, becoming this condition as a reference. The durability was evaluated by the technique of the corrosion potential of the armor in a potentiostat /galvanostat equipment over more than 550 days. There was no significant difference in the potential obtained for the different dosages. The results indicated a high probability for corrosion in the salt atmosphere and also to sulfate; however, these values were less electronegative. As the additions of FC, FS and CC, the results indicated that it is possible to use them as inputs in the production of concrete and/or mortars, leading to reduction in the final cost of artifacts and environmental impacts. The reduction of the cement, the main contributor to the cost of concrete and environmental pollution when the use of best dosages, reached values of 4.3 and 1.7%, respectively for FC and FS; and 3.3% for CC. The photocatalytic potential of TiO2 mortars was analyzed by the reduction in NOx and SO2 gases in a chamber with ultraviolet action. The data obtained proved degradation between 30 and 40% in NOx and 28-43% for SO2, demonstrating also be an alternative to clean air. Key-words: photocatalysis, concrete with sisal and coconut fibers, corrosion potential, chloride and sulfate, air pollutio

Carbon pricing research in Brazil: advances and challenges / Pesquisa de preços de carbono no Brasil: avanços e desafios

Carbon pricing policies are currently considered to be implemented in Brazil, so understanding the present state of carbon pricing research focusing on the national perspective can support energy and environmental policy discussions and guide future research directions. Using the bibliometric method, we analysed 160 publications aiming at assessing the carbon pricing literature in Brazil by 2020. We found out a low and recent production of articles on carbon pricing in Brazil, concentrated from 2015 onwards. Climate Policy is the leading journal and the Federal University of Rio de Janeiro (UFRJ) leads the ranking of the top three authors. Most publications are related to land use change and deforestation, and few publications connect Brazil to carbon pricing policies instruments, like emission trading schemes (ETS) and carbon taxes. However, there is an increase in the number of articles relating Brazil to the energy and environmental policies considering the policy and governance approaches

Análise socioeconômica e de prevalência da mortalidade infantil por Meningite no Brasil ao longo de uma década

A doença conhecida como meningite é provocada pela inflamação das meninges que envolvem o sistema nervoso central, que inclui o cérebro e a medula espinhal. As taxas de mortalidade ainda permanecem altas, variando de 5 a 30% dos casos, e cerca de 50% dos sobreviventes desenvolvem sequelas neurológicas. Os efeitos mais comuns da meningite, variando na dependência do agente etiológico envolvido, em crianças que sobrevivem incluem perda auditiva, atrasos no desenvolvimento e baixo desempenho acadêmico. Neste contexto, objetivou-se na presente pesquisa avaliar o perfil epidemiológico dos casos de meningite infantil no Brasil, diagnosticados em crianças menores que 1 ano, no período de 2011 a 2020. A presente pesquisa foi realizada por meio de um estudo retrospectivo, quantitativo, com dados secundários temporais coletados da base de dados  do DATASUS  de  acordo  com  o  Sistema  de  Informação  de  Agravos  de  Notificação  (SINAN).  As variáveis avaliadas foram: Região do país, sexo, faixa etária, raça, peso ao nascer, idade gestacional e escolaridade da mãe. Os dados foram analisados por meio de estatística descritiva e foram representados na forma de gráficos. No Brasil entre o período de 2011 a 2020 foram diagnosticados 1.146 casos de meningite infantil (0 a 11 meses de vida). A região Sudeste apresentou o maior número de crianças  e  neonatos  com  meningite,  e  menor  número  na  Centro-Oeste. O sexo  masculino  e  das  raças  branca  e  parda  foram  os  mais  afetados  pela  doença. Ademais, peso ao nascer menor que 3 quilogramas, idade gestacional menor que 37 semanas e grau de escolaridade entre 8-11 anos de educação formal demonstraram maior prevalência

Incorporation of Arginine to Commercial Orthodontic Light-Cured Resin Cements—Physical, Adhesive, and Antibacterial Properties

(1) Background: The amino acid arginine is now receiving great attention due to its potential anti-caries benefits. The purpose of this in vitro study was to evaluate the shear bond strength (SBS), ultimate tensile strength (UTS), and antimicrobial potential (CFU) of two arginine-containing orthodontic resin cements. (2) Methods: Forty bovine incisors were separated into four groups (n = 10): Orthocem, Orthocem + arginine (2.5 wt%), Transbond XT, and Transbond XT + arginine (2.5 wt%). The brackets were fixed to the flat surface of the enamel, and after 24 h the SBS was evaluated using the universal testing machine (Instron). For the UTS test, hourglass samples (n = 10) were made and tested in a mini-testing machine (OM-100, Odeme). For the antibacterial test (colony forming unit-CFU), six cement discs from each group were made and exposed to Streptococcus mutans UA159 biofilm for 7 days. The microbiological experiment was performed by serial and triplicate dilutions. The data from each test were statistically analyzed using a two-way ANOVA, followed by Tukey’s test (α = 0.05). (3) Results: The enamel SBS mean values of Transbond XT were statistically higher than those of Orthocem, both with and without arginine (p = 0.02033). There was no significant difference in the SBS mean values between the orthodontic resin cements, either with or without arginine (p = 0.29869). The UTS of the Transbond XT was statistically higher than the Orthocem, but the addition of arginine at 2.5 wt% did not influence the UTS for either resin cement. The Orthocem + arginine orthodontic resin cement was able to significantly reduce S. mutans growth, but no difference was observed for the Transbond XT (p = 0.03439). (4) Conclusion: The incorporation of arginine to commercial orthodontic resin cements may be an efficient preventive strategy to reduce bacterial growth without compromising their adhesive and mechanical properties

Clinical and programmatic outcomes of HIV-exposed infants enrolled in care at geographically diverse clinics, 1997-2021: A cohort study

Background Although 1.3 million women with HIV give birth annually, care and outcomes for HIVexposed infants remain incompletely understood. We analyzed programmatic and health indicators in a large, multidecade global dataset of linked mother-infant records from clinics and programs associated with the International epidemiology Databases to Evaluate AIDS (IeDEA) consortium. Methods and findings HIV-exposed infants were eligible for this retrospective cohort analysis if enrolled at <18 months at 198 clinics in 10 countries across 5 IeDEA regions: East Africa (EA), Central Africa (CA), West Africa (WA), Southern Africa (SA), and the Caribbean, Central, and South America network (CCASAnet). We estimated cumulative incidences of DNA PCR testing, loss to follow-up (LTFU), HIV diagnosis, and death through 24 months of age using proportional subdistribution hazard models accounting for competing risks. Competing risks were transfer, care withdrawal, and confirmation of negative HIV status, along with LTFU and death, when not the outcome of interest. In CA and EA, we quantified associations between maternal/infant characteristics and each outcome. A total of 82,067 infants (47,300 EA, 10,699 CA, 6,503 WA, 15,770 SA, 1,795 CCASAnet) born from 1997 to 2021 were included. Maternal antiretroviral therapy (ART) use during pregnancy ranged from 65.6% (CCASAnet) to 89.5% (EA), with improvements in all regions over time. Twenty-four-month cumulative incidences varied widely across regions, ranging from 12.3% (95% confidence limit [CL], 11.2%,13.5%) in WA to 94.8% (95% CL, 94.6%,95.1%) in EA for DNA PCR testing; 56.2% (95% CL, 55.2%,57.1%) in EA to 98.5% (95% CL, 98.3%,98.7%) in WA for LTFU; 1.9% (95% CL, 1.6%,2.3%) in WA to 10.3% (95% CL, 9.7%,10.9%) in EA for HIV diagnosis; and 0.5% (95% CL, 0.2%,1.0%) in CCASAnet to 4.7% (95% CL, 4.4%,5.0%) in EA for death. Although infant retention did not improve, HIV diagnosis and death decreased over time, and in EA, the cumulative incidence of HIV diagnosis decreased substantially, declining to 2.9% (95% CL, 1.5%,5.4%) in 2020. Maternal ART was associated with decreased infant mortality (subdistribution hazard ratio [sdHR], 0.65; 95% CL, 0.47,0.91 in EA, and sdHR, 0.51; 95% CL, 0.36,0.74 in CA) and HIV diagnosis (sdHR, 0.40; 95% CL, 0.31,0.50 in EA, and sdHR, 0.41; 95% CL, 0.31,0.54 in CA). Study limitations include potential misclassification of outcomes in real-world service delivery data and possible nonrepresentativeness of IeDEA sites and the population of HIV-exposed infants they serve. Conclusions While there was marked regional and temporal heterogeneity in clinical and programmatic outcomes, infant LTFU was high across all regions and time periods. Further efforts are needed to keep HIV-exposed infants in care to receive essential services to reduce HIV infection and mortality

A catalogue of structural and morphological measurements for DES Y1

We present a structural and morphological catalogue for 45 million objects selected from the first year data of the Dark Energy Survey (DES). Single Sersic fits and non-parametric ´ measurements are produced for g, r, and i filters. The parameters from the best-fitting Sersic ´ model (total magnitude, half-light radius, Sersic index, axis ratio, and position angle) are mea- ´ sured with GALFIT; the non-parametric coefficients (concentration, asymmetry, clumpiness, Gini, M20) are provided using the Zurich Estimator of Structural Types (ZEST+). To study the statistical uncertainties, we consider a sample of state-of-the-art image simulations with a realistic distribution in the input parameter space and then process and analyse them as we do with real data: this enables us to quantify the observational biases due to PSF blurring and magnitude effects and correct the measurements as a function of magnitude, galaxy size, Sersic ´ index (concentration for the analysis of the non-parametric measurements) and ellipticity. We present the largest structural catalogue to date: we find that accurate and complete measurements for all the structural parameters are typically obtained for galaxies with SEXTRACTOR MAG AUTO I ≤ 21. Indeed, the parameters in the filters i and r can be overall well recovered up to MAG AUTO ≤ 21.5, corresponding to a fitting completeness of ∼90 per cent below this threshold, for a total of 25 million galaxies. The combination of parametric and non-parametric structural measurements makes this catalogue an important instrument to explore and understand how galaxies form and evolve. The catalogue described in this paper will be publicly released alongside the DES collaboration Y1 cosmology data products at the following URL: https://des.ncsa.illinois.edu/releases

Discovery of a z = 0.65 post-starburst BAL quasar in the DES supernova fields

We present the discovery of a z = 0.65 low-ionization broad absorption line (LoBAL) quasar in a post-starburst galaxy in data from the Dark Energy Survey (DES) and spectroscopy from the Australian Dark Energy Survey (OzDES). LoBAL quasars are a minority of all BALs, and rarer still is that this object also exhibits broad Fe II (an FeLoBAL) and Balmer absorption. This is the first BAL quasar that has signatures of recently truncated star formation, which we estimate ended about 40 Myr ago. The characteristic signatures of an FeLoBAL require high column densities, which could be explained by the emergence of a young quasar from an early, dust-enshrouded phase, or by clouds compressed by a blast wave. The age of the starburst component is comparable to estimates of the lifetime of quasars, so if we assume the quasar activity is related to the truncation of the star formation, this object is better explained by the blast wave scenario

VDES J2325−5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars showthe lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002.We model the system as a single isothermal ellipsoid and find the Einstein radius θE ∼ 1.47 arcsec, enclosed mass Menc ∼ 4 × 1011 M and a time delay of ∼52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1