Duplex stainless steels (DSS) are so named because they exhibit a biphasic microstructure, with roughly equal volumetric proportions of ferrite and austenite. They find extensive use in industries such as oil, pulp and paper, chemical, nuclear, and others, typically when a material with high mechanical strength and corrosion resistance is required. Powder metallurgy can provide a means of recycling scraps and leftovers from production processes like machining. This study focused on investigating the influence of different particle sizes and pressing methods (uniaxial and isostatic) on the densification of a DSS composite, specifically the UNS S31803 grade, produced through powder metallurgy. The powders were subjected to milling for 20, 40, and 80 hours, with the addition of 3% vanadium carbide and 1% methanol as a process control agent. Heat treatment at 1050 ºC for 30 minutes was applied to relieve the stresses resulting from the milling process. The powders obtained at different milling times were classified and characterized in terms of morphology and particle size distribution using scanning electron microscopy and laser granulometry techniques. Subsequently, the powders with different particle sizes were pressed using uniaxial and isostatic pressing methods. Pellets were produced using powders milled for 20, 40, and 80 hours, as well as mixtures of equal weight fractions of powders milled for 20 and 40 hours, 40 and 80 hours, and 20, 40, and 80 hours. Green density measurements were conducted on the obtained pellets, which were then sintered at 1250 ºC for 1 hour. The sintered pellets were characterized in terms of porosity, pore size, and densification using optical microscopy, X-ray diffraction, and density measurements using the Archimedes method. The results showed that particle dimensions decreased with longer milling times. The average particle size decreased from 60.57 µm at 20 hours of milling to 52.35 µm at 40 hours and 39.02 µm at 80 hours. The porosity values were similar for uniaxial and isostatic pressing. The highest densification value (determined using the Archimedes method) was achieved with the mixture of powders milled for 20, 40, and 80
hours using isostatic pressing, resulting in a density of 6.9528 g/cm³. The density value for UNS S31803 DSS produced via casting is 7.80 g/cm³.

The aim of this study was to investigate how MIG (metal inert gas) welding impacts the corrosion resistance properties of UNS S41003 steel. The welds were performed with two energy levels. After welding, microstructural characterization, tensile, Vickers microhardness, ferritoscopy, and potentiodynamic polarization tests, were performed. Stress corrosion crack (SCC)and double-loop polarization (DL-EPR) tests were also carried out. From the potentiodynamic polarization tests, a lower pitting potential was observed in the heat affected zone (HAZ) of both welds: high energy weld (HE) and low energy weld (LE). A pronounced ferrite grain growth was observed in the HAZ of the welds, with the presence of martensite needles in their grain boundaries. In the fused zone (FZ), the microstructure was constituted by austenite, derived from the filler metal (AISI 309LSi), with islands of delta ferrite derived from the dilution of the base metal (UNS S41003). The HAZ exhibited lower pitting potential values compared to the BM. High values of ir/ia were found in the FZ, BM, and HAZ, indicating susceptibility to intergranular corrosion. Greater susceptibility to stress corrosion cracking (SCC) was evidenced in the HAZ compared to the FZ and BM.

The present work aims to identify cause(s) of failures that occurred in centrifugal pump shafts used in the pumping of iron ore pulp in a large mining plant. The breaks of this type of pump shaft can damage other components, leading to further performance compromises of the equipment. Thus, in the search for the proposed objective, a careful bibliographic review was performed on centrifugal pumps, types of fracture, fatigue and properties of structural steels used in centrifugal pump shafts (ABNT 1045 and ABNT 4140). Studies related to structural integrity, fatigue, failure modes, types of charges and morphology of fractures have also been done. Regarding the experimental part, a careful analysis of the fractured shafts using, among others, the following techniques: visual inspection, conventional mechanical tests (tensile test, Charpy impact test, hardness testing, rotary flexion fatigue test (S-N), micrographic analysis, SEM microfractography and computer simulation. Based on the studies, it was possible to conclude that the breaks of centrifugal pump shafts were motivated by a combination of fatigue potentiated by stress concentrations and occasional overloads.

The use of the surgical mask as we know it today began in Germany in 1897 and its effectiveness as a microbial barrier is recognized. However, there are some factors that can compromise the protective effect of a surgical mask, and this effect is only maintained when the surface layer of the mask is hydrophobic and dry. In this context, there is a need to replace masks that are wet from prolonged use or that have been contaminated with blood or other secretions with clean masks, which cannot always be done immediately during emergency procedures. In addition, the hands of healthcare workers can be contaminated during the removal of surgical masks. The coating of surfaces by different metals can give these coated materials antimicrobial activity. In this context, titanium dioxide (TiO2) has known antimicrobial activity and is used in a wide variety of biological applications. In addition, coatings made up of silica particles, TiO2 or other oxides to modify the roughness of surfaces in order to make them hydrophobic. The sol-gel method can be applied to obtain a hydrophobic coating and this method involves the hydrolysis of a silica precursor source, such as tetraethyl orthosilicate (SiO2), with alcohol at low temperatures. Therefore, the present dissertation aims to develop a coverage with antimicrobial properties, based on the preparation of particles (Ps) of TiO2 with SiO2, on the textile composition of 100% polypropylene (PP) used for making surgical masks. The study was carried out through the following treatments: (a) immersion of tissue in tetraethylorthosilicate (SIO2) solution, PP/SIO2 sample; (b) immersion of tissue in SIO2 solution and after curing, sample PP/SiO2-curing; (c) immersing the tissue in SIO2 solution and after curing the tissue is immersed in titanium isopropoxide solution, sample PP/SIO2-curing-TiO2; (d) immersion of tissue in SiO2 solution, followed by immersion in titanium isopropoxide solution and finally curing, sample PP/SiO2-TiO2-curing. The microcrystalline structure and morphology of the samples were analyzed by X-ray diffraction (XRD) and electron microscopy (SEM). The degree of hydrophobicity of the surface was evaluated by measuring the contact angle. Antimicrobial activity was evaluated by the bacterial growth inhibition technique. The data obtained by XRD confirmed the crystalline pattern of the PP tissue in all analyzed samples. The amorphous SiO2 diffraction peak was only observed in the PP/SiO2-Cure and PP/SiO2-TiO2-Cure samples. TiO2 diffraction peaks were only observed in the PP/SiO2-TiO2-cure sample. The SEM showed in all analyzed samples the PP non-woven, formed by 18.5m wide interwoven microfibers. The SEM-EDS showed the low incorporation of TiO2 in the PP non-woven. The contact angle showed the highest degree of hydrophobicity in the PP/SiO2-curing sample. There was no inhibition of bacterial growth in Kirby Bauer, however, in the biofilm analysis, the PP + TiO2 + SiO2 + Cura sample showed a decrease in bacterial biomass.

The search for solutions to equate the growing demand of civil construction and sustainability in the exploration of natural resources involves the search for new renewable sources and use of waste, especially those that are not yet satisfactorily absorbed by the recycling industry, such as the glass.
Widely used around the world, concrete and other cementitious composites are a good alternative for the absorption of waste from different origins, and have been improved in the last decades, as the case of Self-Compacting Concrete (SCC).
This study investigated the viability of producing Self-Compacting Mortars (SCM) as an initial phase for the production of SCC, replacing the sand with Ground Waste Glass (GWG) in the proportions of 5%, 10%, 15%, 20% and 30% by mass, using Silica Fume (SF) as a mineral addition and a superplasticizer (SPA) as a chemical additive. To achieve the objectives proposed in this study, tests were performed on the mortars in the fresh and hardened states, analysis of images generated by scanning electron microscopy, as well as the investigation of the occurrence of the Alkali-Aggregate Reaction (AAR), because the glass, in its nature, is considered potentially reactive. Regarding the GWG studies, its granulometry was manipulated so that it approximated to sand.
The results showed that it is viable to use GWG as a partial substitute for sand in the production of SCC, once the SCM produced met the requirements in fresh state and had their mechanical properties improved, furthermore, in most cases, could even meet structural applications such as in reinforcements and repairs.
In the occurrence of AAR, the expansions were within the established limit not to cause damage, with the occurrence of only one result that minimally exceeded this value, indicating a positive participation of the pozzolanic activity of the fine particles of the GWG, but mainly the essential composition of the SCM through its additives.

Nowadays, according to the United Nations Food and Agriculture Organization (FAO), Brazil, USA and China are the biggest consumers of pesticides around the globe. For being one of the world leaders in food production, our country consumed, only in 2020, around 370 thousand tons of pesticides. These compounds have high molecular stability and low biodegradability. They are also hard to remove from the aquatic environment. These factors made them a huge problem to fauna, flora, and human beings. Looking at this scenery, the development of public politics to control the use of these compounds are vitally important to the planet’s life. developing techniques and materials to remove these toxic materials from the aquatic environment is also important. In this sense, the copper oxide-coated silica nanoparticles (SBA16@CUO) were idealized as an innovator system to remove pesticides from water. It was observed that the samples produced are promising materials for adsorption purposes, presenting mesoporous networks with specific surface area values of up to 128.92 m2/g. Beyond this, using different techniques was possible to infer the average particle size of approximately 215.93 nm. The study of pesticide adsorption was evaluated using High-Performance Liquid Chromatography (HPLC) technique. For the quantification of pesticides, calibration curves with a coefficient of determination (r2) greater than 0.9628, revealed that the SBA16@CUO samples had adsorption capacity with an average percentage of pesticides Dieldrin, Paraquat, and DEET of 72%, 91%, and 87%, respectively. Considering the results obtained, the SBA16@CUO can be considered a potential system to be applied to remove pesticides, with an innovative character for the market.

Nowadays, infectious diseases are still a great challenge for human health.
Bacterial infections are one of the primary causes of worldwide mortality. Due to the
development of resistance processes, the search for therapeutic alternatives has focused on many researchers of biomedical areas. In this sense, antimicrobial drugs’ encapsulation has emerged as a relevant alternative, capable of improving the therapeutic effectiveness, while a significant reduction in the side effects can be observed. Following in the same direction, in the present work, mesoporous iron oxide nanoparticles (MIONs), loaded with ciprofloxacin, were prepared in order to evaluate the potential application of the system against bacterial infections.
MIONs and MIONs silanized with 3-amino-propyltriethoxysilane - APTES (MIONs@APTES)
were obtained with a mean size of 78.34 ± 1.83 nm and surface areas of 258.27 and 186.27
m2.g-1, respectively. Both samples allowed to load relevant amounts of the drug, reaching a high incorporation rate and a controlled release profile, with different kinetics behavior, when incubated with simulated body fluid (SBF). MIONs samples showed release behavior
compatible with second order kinetics, while the MIONs@APTES matrix allowed the release
following a first order kinetics. The in vitro cytotoxicity evaluation of the obtained matrices
revealed that both systems exhibit biocompatibility profiles under normal human cell lineage cells (HEK-293), where no significant cytotoxic profile was observed. On the other hand, MIONs containing the antibiotic drug incorporated showed relevant antibiofilm properties against a strain of Staphylococcus Aureus, when compared to controls consisting of free ciprofloxacin and nanoparticles without the drug. From all the results obtained in this work, the nanosystems produced can be considered as a potential system to be applied in the treatment of bacterial infections.

O estudo de compósitos de matriz polimérica reforçados com fibras vegetais curtas é interessante para países como o Brasil, que é geograficamente privilegiado, possui extensas áreas cultiváveis, boas condições climáticas e solo fértil para o cultivo de uma ampla variedade de espécies de plantas. O interesse pelo uso de fibras vegetais curtas em compósitos termoplásticos é atribuído às inúmeras vantagens que possuem em relação aos reforços inorgânicos, como as fibras de vidro. Além de sua capacidade de melhora das propriedades mecânicas do termoplástico, possui vantagens adicionais como, menor densidade, obtenção de fontes renováveis, biodegradáveis e menor abrasividade aos equipamentos de processamento. Neste trabalho, estudou-se a incorporação de 20 wt% (porcentagem em massa) de fibras curtas de curauá em PP-copolímero de etileno (PP/EPR), processados por extrusão a 200 rpm, em formulações com e sem agente de acoplamento, seguidos por injeção dos corpos de prova. A formulação de compósito contendo 2 wt% de agente de acoplamento apresentou melhores propriedades reológicas, mecânicas e térmicas em relação ao compósito não compatibilizado. Desse modo, o compósito compatibilizado apresentou um aumento na temperatura de deflexão térmica (HDT) de 16% em comparação ao não compatibilizado que apresentou 12,9%. O aumento da resistência à tração do compósito compatibilizado foi de 21,7 % e 16,9 % na resistência à tração, em comparação ao PP/EPR virgem e o compósito não compatibilizado, respectivamente. Nos ensaios de resistência à flexão, os resultados do compósito compatibilizado aumentaram 16,9 % e 9,3 % em relação ao PP/EPR virgem e o compósito não compatibilizado. As características geométricas e razão de aspecto das fibras antes e após o processamento foram medidas através de estereoscopia e analisados estatisticamente. A adesão entre as fases, na presença ou ausência de agente de acoplamento, foi estudada por microscopia eletrônica de varredura. As características reológicas dos materiais foram determinadas por medidas de índice de fluidez (MFR), onde o compósito compatibilizado apresentou uma melhor taxa de fluxo em relação ao compósito sem agente de acoplamento.