Desenvolvimento de revestimentos contendo adições de carepas de laminação de aços

Revestimentos orgânicos anticorrosão normalmente possuem cargas lamelares que aumentam o caminho de difusão do O2 e H2O até a interface polímero/metal atuando, portanto, como barreira. Em caso de avaria mecânica do revestimento e surgimento de micro-trincas, um novo método de reparação self-healing foi obtido pelo uso de revestimentos inteligentes (smart coatings). Estes revestimentos possuem inibidores de corrosão incorporados em sua matriz que promovem lenta e localizada liberação do agente inibidor. Neste trabalho se processou carepa de aço carbono laminado para utilização como carga em resina alquídica, com a finalidade de melhorar a propriedade de barreira. As carepas de aço AISI 316 e 420 também foram estudadas. Estas foram investigadas como possíveis fornecedoras de cromatos (AISI 420) e/ou molibdatos (AISI 316) por lenta liberação e solubilização destes inibidores anódicos. As carepas foram inicialmente lavadas, moídas e ustuladas. Depois caracterizadas química e morfologicamente por MEV-EDS, a distribuição de tamanhos de partículas foi determinada por espalhamento de luz, as fases foram quantificadas por análise de Raios-X e Rietveld e para as medições de taxa de cátions metálicos dissolvidos durante lixiviação, foi usado espectrometria de absorção atômica. A taxa de liberação de ions cromatos e molibdatos foram descriminadas por carepas ustuladas e não ustuladas. As lixívias foram realizadas em água deionizada e solução de ácido fosfórico com pH 4,5, simulando o pH que ocorre durante a corrosão do Fe. Os revestimentos desenvolvidos foram aplicados sobre placas de aço SAE 1006LF. Os métodos usados para a avaliação do desempenho destes revestimentos foram névoa salina e imersão das amostras em solução de NaCl 0,1M para medições periódicas de impedância (EIS). Os resultados indicam que a carepa de aço AISI 1020 aumenta a propriedade de barreira do filme polimérico, bem como uma redução da progressão na capacitância dos revestimentos que continham carepa de aço AISI 420, devido à permeação de H2O. Revestimentos contendo carepas de aços AISI 420 ou AISI 316 apresentaram maior resistência em amostras riscadas, revelando um efeito benéfico dos espinélios Cr e Mo, representando um possível efeito smart coating.Organic coatings for corrosion protection usually have additions of lamellar inorganic charges that should increase the diffusion path of O2 and H2O to the metal/polymer interface. In the case of mechanical damage of the coating by the occurrence of micro-cracks, a new method of self-healing has been developed, which involve the local release of inhibitors only in the case of corrosion attack of the metallic substrate, characterizing the so called smart coatings. In this work, hot-rolled carbon steel scales were processed for the use as lamellar charge in alkyd resins to improve the barrier property of the obtained coating. Additionally scales of the stainless steels AISI 316 and 420 were studied, but in this case, as possible sources of chromate (AISI 420) and/or molybdate (AISI 316) by slow solubilization and release of these anodic inhibitors. Scales were initially washed, milled and calcined. Later, the morphology was characterized by SEM-EDS, the size distribution of particles determined by light scattering, the phases quantified by XRD and Rietveld analysis [1], while for the measurement of release rates of dissolved metal cations, atomic absorption spectrometry was used. Long chained alkyd resin was used for the production of five different paints, four of these with the addition of 4.5 weight % of Fe-oxides, and for comparison, one free of additional inorganic charges. The release rate of chromate and molybdate ions was determined for calcined and non calcined scales. The aqueous extraction was carried out in deionized water and pH 4.5 phosphate solution, simulating the pH on a corroding Fe surface. The developed coatings were applied on SAE 1006LF steel plates and the corrosion resistance evaluated in salt spray and by periodic EIS measurements of samples immersed in NaCl 0,1M. The results indicate that the addition of “AISI 1020” scale increases the barrier property of the polymeric film, and the addition of “AISI 420” scale slow down the capacitance evolution due to water permeation. Coatings containing "AISI 420 or AISI 316 scales additions have clearly a higher corrosion resistance of scratched coupons, showing the beneficial action of the (Cr, Mo)-spinels additions and a possible smart coating effect

Desenvolvimento de revestimento inteligente com carepas dos aços AISI 420, 304 & 316

Solucionar o problema da geração e acúmulo de resíduos é um dos principais desafios da sociedade moderna. A indústria siderúrgica é uma das maiores geradoras de subprodutos e resíduos. Grande quantidade de óxidos são gerados nos processos de obtenção e conformação do aço, muitos deles com composição química de importante valor. Convergente a isso, para a nossa investigação, foram estudados alguns tipos de carepas provenientes de processos siderúrgicos. Para isso, foram processadas carepas de aço carbono SAE 1045 trefilado, com morfologia lamelar, testadas em resina alquídica para melhorar a propriedade de barreira do revestimento orgânico, analisadas por métodos eletroquímicos, como medidas da capacitância, potenciometria e espectroscopia de impedância eletroquímica para quantificar a permeação de água, difusão de cloretos e compreender os processos físicos das barreiras ao transporte de espécies nesse sistema. Para quantificar o transporte do cloreto na tinta, foi desenvolvida uma técnica baseada na medida do potencial AgAgCl. Foi medido o potencial de uma placa de prata de alta pureza anodizada em solução NaCl e revestida com o revestimento experimental contra outro eletrodo de referência AgAgCl, estando ambos os eletrodos imersos na mesma solução de cloreto. Foram também estudadas carepas provenientes de aços AISI 304, 316 e 420 na forma de carga mineral em tintas como liberadoras de cromato e molibdato, paralelamente à solubilização de outros ânios. Para isso, foi aumentada a área superficial dessas carepas, reduzindo-as a partículas micrométricas e submicrométricas, para então serem testadas em ensaios de solubilização em soluções tampão de pH 7,0 e 2,2. O acompanhamento da solubilização dos ânios nas soluções ensaiadas foi realizado por espectrometria de absorção atômica por chama. O efeito inibidor na corrosão do aço SAE 1006 proporcionado pelas espécies liberadas de carepas foi testado por voltametria cíclica em solução dos respectivos extratos. Por fim, a proteção promovida pela carepa liberadora de inibidores foi testada com o uso de micro células capilares em solução de NaCl 0,01 M.One of the main challenges of modern society is to reduce waste production and accumulation. The steel industry is one of the largest producers of by-products and waste. Large amounts of oxides are generated during the steel production and forming processes, and many of them have a functional chemical composition. Different types of steel scales were analyzed in this study as possible corrosion inhibitor sources and lamellar charges for paints. Scales industrially obtained from cold drawn SAE 1045 carbon steel were processed to have a lamellar morphology. These lamellae were added to alkyd resin for improving the barrier property of the organic coating and analyzed by electrochemical methods such as capacitance at a single frequency, potentiometry, and electrochemical impedance spectroscopy. Those methods helped to quantify water and chloride permeation through the paint. For this, a technique was developed by which an Ag|AgCl reference electrode's potential is compared against another Ag|AgCl reference coated with the modified paint, both immersed in the same solution. Additionally, scales from the forging of AISI 304, 316, and 420 steel were tested as chromate and molybdate releaser, among other cations. For this, the scale surface area was increased, reducing them to powder particles with granulometry in the micrometric/submicrometric range and later tested in solubilization tests in buffer solutions of pH 7.0 and 2.2. The solubilized cation in the tested solutions was determined by atomic absorption spectrometry, and, subsequently, the respective extracts were used to observe the behavior of these cations as corrosion inhibitors of the SAE 1006 steel by polarization techniques. Finally, the corrosion protection conferred by the inhibitor released by the scales was tested on the SAE 1006 steel in 0.0 1 M NaCl solution by the electrochemical microcapillary cell technique

Characterization and processing of scales from the mechanical descaling of carbon steels for recycling as coating pigments

Na produção de aços, cerca de 1% a 2% em peso é gerado como carepa. O grande volume deste resíduo sólido tem induzido estudos para reaproveitamento da carepa, usualmente gerando produtos com baixo valor agregado. Neste estudo, caracterizou-se a carepa proveniente da decapagem mecânica por roletes de fio máquina do aço SAE 1045 por MEV e por difração de Raios-X quantitativa (método de Rietveld), assim como por análise térmica diferencial, com o objetivo de desenvolver o processo de tratamento da carepa para posterior utilização como pigmento em tintas anticorrosivas de alto valor agregado. Razões de aspecto entre 1:50 e 1:100 foram obtidas no processo com transformação integral da carepa em hematita, o que permite a substituição de óxidos micáceos de ferro pelo produto obtido.The large volume of solid wastes generated as scales in Steel Mills accounts to circa 1% to 2% of the total steel production and has led to studies aiming the recycling of scales, usually resulting in products of low added value. In this study, scales from the mechanical descaling of SAE 1045 steel were characterized by SEM and by quantitative X-Ray diffraction (Rietveld method), as well as by differential thermal analysis, aiming to develop its pretreatment for the further use as lamellar pigments in anticorrosive coatings of high added value. Aspect ratios between 1:50 and 1:100 were obtained by the processing of scales, which allows the replacement of other micaceous iron oxides

One Health – an Ecological and Evolutionary Framework for tackling Neglected Zoonotic Diseases

Understanding the complex population biology and transmission ecology of multihost parasites has been declared as one of the major challenges of biomedical sciences for the 21st century and the Neglected Zoonotic Diseases (NZDs) are perhaps the most neglected of all the Neglected Tropical Diseases (NTDs). Here we consider how multihost parasite transmission and evolutionary dynamics may affect the success of human and animal disease control programmes, particularly neglected diseases of the developing world. We review the different types of zoonotic interactions that occur, both ecological and evolutionary, their potential relevance for current human control activities, and make suggestions for the development of an empirical evidence base and theoretical framework to better understand and predict the outcome of such interactions. In particular, we consider whether preventive chemotherapy, the current mainstay of NTD control, can be successful without a One Health approach. Transmission within and between animal reservoirs and humans can have important ecological and evolutionary consequences, driving the evolution and establishment of drug resistance, as well as providing selective pressures for spill‐over, host switching, hybridizations and introgressions between animal and human parasites. Our aim here is to highlight the importance of both elucidating disease ecology, including identifying key hosts and tailoring control effort accordingly, and understanding parasite evolution, such as precisely how infectious agents may respond and adapt to anthropogenic change. Both elements are essential if we are to alleviate disease risks from NZDs in humans, domestic animals and wildlife

The pathogenic mechanism of the Mycobacterium ulcerans virulence factor, mycolactone, depends on blockade of protein translocation into the ER.

Infection with Mycobacterium ulcerans is characterised by tissue necrosis and immunosuppression due to mycolactone, the necessary and sufficient virulence factor for Buruli ulcer disease pathology. Many of its effects are known to involve down-regulation of specific proteins implicated in important cellular processes, such as immune responses and cell adhesion. We have previously shown mycolactone completely blocks the production of LPS-dependent proinflammatory mediators post-transcriptionally. Using polysome profiling we now demonstrate conclusively that mycolactone does not prevent translation of TNF, IL-6 and Cox-2 mRNAs in macrophages. Instead, it inhibits the production of these, along with nearly all other (induced and constitutive) proteins that transit through the ER. This is due to a blockade of protein translocation and subsequent degradation of aberrantly located protein. Several lines of evidence support this transformative explanation of mycolactone function. First, cellular TNF and Cox-2 can be once more detected if the action of the 26S proteasome is inhibited concurrently. Second, restored protein is found in the cytosol, indicating an inability to translocate. Third, in vitro translation assays show mycolactone prevents the translocation of TNF and other proteins into the ER. This is specific as the insertion of tail-anchored proteins into the ER is unaffected showing that the ER remains structurally intact. Fourth, metabolic labelling reveals a near-complete loss of glycosylated and secreted proteins from treated cells, whereas cytosolic proteins are unaffected. Notably, the profound lack of glycosylated and secreted protein production is apparent in a range of different disease-relevant cell types. These studies provide a new mechanism underlying mycolactone's observed pathological activities both in vitro and in vivo. Mycolactone-dependent inhibition of protein translocation into the ER not only explains the deficit of innate cytokines, but also the loss of membrane receptors, adhesion molecules and T-cell cytokines that drive the aetiology of Buruli ulcer

Observation of inverse Compton emission from a long γ-ray burst.

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission1,2. Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands1-6. The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock7-9. Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C10,11. Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10-6 to 1012 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality