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Duplex stainless steel owns its denomination to the combination of two types of phases, ferritic and austenitic, whose main characteristic is the excellent resistance to corrosion in aggressive media due to its ability to form a passive layer. Because it has this characteristic, this material is mainly used in the petrochemical industries. This article studied the efficiency of the (3-indolimethyl) trimethylammonium iodide (DIMTI) ionic liquid, as a corrosion inhibitor in 1 M solution of hydrochloric acid (HCl) for UNS S31803 duplex stainless steel welded, and heat treated. The corrosive process was investigated by potentiodynamic polarization test. The samples were evaluated in the presence of 1 M HCl solution and with DIMTI ionic liquid at a concentration of 0.4 and 0.8 mM. The samples subjected to this corrosive medium obtained excellent rates of corrosion inhibition, of 87 and 94%, respectively. Based polarization curves, it was found that the DIMTI, ionic liquid acted as a mixed type of corrosion inhibitor. The inhibition efficiency increased with the increase in concentration, confirming its adsorption on the surface of the metal. With the present study it was concluded that ionic liquids are a green and sustainable alternative to replace traditional toxic corrosion inhibitors.

Background and objectives: The neurodevelopment of the offspring is suggested to be influenced by the maternal immune system's responses throughout pregnancy, which in turn is also vulnerable to maternal psychosocial stress conditions. Therefore, our main goal was to investigate whether maternal peripheral immunological biomarkers (IB) during two stages of gestation are associated with distinct neurodevelopmental trajectories in the first two years of life. As a second goal, we also explored the association between maternal distal (childhood) and proximal (gestation) stressful experiences and the immunological markers assessed during pregnancy. Methods: Maternal childhood trauma, depressive and anxiety symptoms, and peripheral IB (IFNγ, IL-10, IL1β, IL6, IL8, TNFα, EGF, IL13, IL17, IL1Ra and IL4) were measured at baseline (8–16 weeks of pregnancy) and at 30 weeks of pregnancy in 160 women. The participants had the blood samples collected from two randomized clinical trials conducted by the same team and methods in the same community. A Principal Component Analysis (PCA) was implemented to create meaningful composite variables that describe the cytokines joint variation. Finally, linear mixed-effects modeling was used to investigate the influence of inflammatory biomarkers, maternal childhood trauma, anxiety, and depressive symptoms on Bayley's III scores trajectories. Results: The IB profile during the 3rd trimester of pregnancy predicted the offspring's neurodevelopmental trajectories in the first two years of life. The components derived from PCA were important predictors and captured different immune responses, reflecting both pro- and anti-inflammatory states. Maternal stressful experiences did not correlate with the immunological markers. Although not a reliable predictor alone, maternal psychosocial stress at the 1st trimester of pregnancy interacted with the mother's immune response while predicting the neurodevelopmental scores during the first two years of life. Conclusions: Our results underscore the importance of the maternal immune response during pregnancy in shaping the neurodevelopmental trajectory of the offspring. Additionally, we observed that the maternal distress at the early stages of pregnancy has an incremental effect on the neurodevelopmental outcome but depends upon the immune response.

This article presents a study on the use of natural fibers and kaolin waste as sustainable alternatives in the manufacture of polymer matrix composites. In the present research, isophthalic unsaturated polyester matrix composites were manufactured in association with bamboo fibers (Bambusa vulgaris) and kaolin waste. The kaolin waste was used with a particle size of 50–100 MESH and the fibers in lengths of 15 mm and 30 mm, randomly arranged within the matrix. Bamboo fibers were used fresh and treated with NaOH (5%/2 h). The chemical characterization of the fibers was obtained followed by the morphological characterization using Scanning Electron Microscopy (SEM). The composites were mechanically evaluated through flexural and tensile tests. The mechanical properties obtained were treated by analysis of variance (ANOVA) and Tukey test. The fracture surfaces of the composites were verified by SEM. Bamboo fibers had a chemical composition similar to other natural fibers already studied, with 7.55% extractives, 17.95% total lignin and 74.5% holocellulose. Composites with 30 mm long treated fibers and 30% kaolin showed better flexural strength (137.0 MPa), with deformation of (1.59 mm) and flexural modulus of (19.27 GPa). Through tensile tests, it was possible to identify that the addition of kaolin waste provided a significant improvement in tensile strength of 66% (15BTKW20) and 54% (30BTKW20) compared to neat polyester. SEM micrographs of bamboo fibers, surface roughness, starch granules, micropores and parenchyma cells were identified. ANOVA reinforced the reliability of the results, highlighting the feasibility of manufacturing kaolin waste/bamboo fiber hybrid composites.

Abstract The use of natural fibers in cementitious composites has been gaining prominence in engineering. The natural lignocellulosic fibers (NLFs) used in these composites have advantages such as reduced density, reduced fragmentation and concrete cracking, thus improving flexural performance and durability. Coconut-fiber is one of those natural fibers and its use presents technical, ecological, social and economic benefits, as it is improperly disposed of, representing a large waste of natural resources, in addition to causing environmental pollution.. Thus, composites reinforced with natural fibers are promising materials for the construction industry, as in addition to meeting the sustainability of buildings, there will also be a reduction in urban solid waste generated and gains for structures with the use of environmentally friendly materials that meet to active efforts and with greater durability. This work aims to evaluate the tensile behavior of green coconut-fibers subjected to different drying temperatures through chemical, thermal (TG/DSC), morphological, visual and mechanical analysis. Drying temperatures of 70 °C, 100 °C and 130 °C were analyzed and the results indicated that the drying temperature at 70 °C was satisfactory, providing fiber-reinforced composites with good tensile strength, combined with good ductility.

Corrosion, a destructive electrochemical dissolution of metals, poses a significant problem impacting numerous industry sectors. It leads to economic losses, technical performance deterioration, and environmental damage. Employing corrosion inhibitors stands out as one of the most common strategies to shield metallic materials from corrosion. In recent times, imidazolium-based ionic liquids (IBILs) have garnered increasing attention as promising corrosion inhibitors due to their unique properties, including high thermal stability, ionic conductivity, and low volatility. This article provides an overview of recent studies on the utilization of IBILs as corrosion inhibitors for stainless steels in various corrosive environments. Initially, brief information on stainless steel corrosion resistance is presented, followed by a discussion of possible electrochemical attachment mechanisms. Furthermore, the mechanisms involved in corrosion protection are explored, along with factors influencing the efficiency of IBILs as corrosion inhibitors. This review emphasizes the potential of IBILs as corrosion inhibitors for stainless steels in diverse industrial applications.

This work presents an experimental investigation of the mechanical properties of composites reinforced with crocheted fabrics of miriti fibers (Mauritia flexuosa) in a polyester matrix. The fabrics were manufactured under different grammages, with and without alkaline fiber treatment. The composites were produced using two different viscosity conditions of the polyester matrix and part of these underwent post-cure treatment at 60 °C. In order to evaluate the effects of the input variables, the samples were produced by manual lamination with curing under vacuum, following a complete factorial experimental matrix type 24, tested according to the ASTM D 3039. The results showed that the variables alkaline treatment of the fibers and viscosity of the matrix presented statistically significant effects on the responses limit of tensile strength and modulus of elasticity. The highest level of tensile strength (13.02 MPa) was obtained in composites with alkaline treatment of the fibers, fabric grammage 473.9 g/cm2, matrix with higher viscosity and post-cure application, while the modulus of elasticity obtained the best performance (1.59 GPa) in samples without alkaline treatment of the fibers, manufactured with the fabric of lower grammage, with a more viscous matrix and that underwent post-curing.

Natural fibers show an increasing potential as reinforcement of polymeric composites, representing a promising concurrent to glass and carbon fibers extensively used in the construction of wind turbine blades synthetic fibers recyclability/disposability and high production energy cost have already been discussed in the main turbine producing centres. In particular, the development of wind turbines for low wind speed areas can increase the energy generation potential of regions not originally eligible for the installation of large turbines. This study proposes the evaluation of the use of jute fiber (Corchorus capsularis) reinforced epoxy composite in the construction of S1210 airfoil profile, of a small-scale wind turbine for low wind speed regions, considering the structural parameters, developed incorporating the Classical Laminate Theory (CLT) and Extended Bredt-Batho Shear Flow Theory (EBSFT).In order to raise the elastic properties and enable the use of the failure criteria, the composite blades were characterized according to ASTM standards. The mechanical properties surveyed, together with the elastic parameters of the cross section, torsional stiffness, axial stiffness, GJ 1873.6 N m2, EI 9.47 × 104 N m2, and flexural rigidity, Ely 4.97 × 104 N m2, Elz 1.45 × 106 N m2, respectively, demonstrated the feasibility of using the jute fiber reinforced epoxy composite in the blade construction, evaluated according to the maximum tension failure criterion.

Duplex stainless steels (DSSs), are used commonly under severe working conditions, subject to high stresses associated with corrosion. A typical DSS is composed of the combination involving two types of microstructures, ferritic and austenitic, which characterizes it as a material with corrosion resistance in aggressive media, due to its ability to passivate. The use of DSS has been increasingly exploited in the oil industry, and its use has occurred in numerous areas, standing out in the production of flexible pipelines, which in most applications, is associated with a welding process. They require special care when welded by the tungsten inert gas (TIG) welding process. Temperature variations in this process, along with heat treatment, promote the formation of precipitates in the matrix and change the phase balance. This significantly influences the mechanical and corrosion properties of DSSs. The objective of this work is to study the influence of two different parameters of solubilization heat treatment after welding on the microstructure and corrosion resistance of a DSSs welded joints. After the autogenous TIG welding process, the welds were subjected to thermal solubilization treatments for 10 and 25 s at 1050 °C. The conditions subjected to the solubilization heat treatment were compared with the as TIG welded control condition. The microstructure was analyzed by confocal microscopy and the corrosion resistance was evaluated by the ''A'' method of the ASTM G48 standard.

The influence of temperature variation on the adherence of granite slabs was simulated by a set of TBS tensile bond strength tests carried out using three types of rocks of established commercial use and with good technological qualities, known as “Branco Desireé”, “Vermelho Capão Bonito” and “Cinza Andorinha”. Specimens of these materials were fixed with two types of adhesive mortars, one commercial and the other produced in the laboratory, with white cement CPI. After the standardized cure, 186 TBS tests were carried out in 5 temperature ranges laboratory-controlled, ranging from 23 °C to 60 °C. The test results showed the temperature increase implies the loss of tensile strength. The commercial mortar presented TBS final values lower or nearby to 1 MPa, the standard threshold for ceramic slabs. The mortar prepared with white cement showed better performance, with adherence values above the 68% mentioned limit. This expressive result recommends the continuation of research with other types of rocks fixed with mortar prepared with white cement. The microstructure behavior of the material sets subjected to adherence tests was also investigated. The inspections showed clear contact between the stone plates (with both rough and smooth contact surfaces), without the occurrence of reaction edges or pervasion of the mortar in the stone. Anchoring, therefore, took place only in the contact between the standard substrate and mortar.

The work aims to observe the effect of waste ceramic brick (WCB), ground in two times, 60 and 120 min for use in mortar. The crystalline phases presented in clays of the north of Rio de Janeiro have already been identified, indicating that after firing at an adequate temperature, it is possible to apply it as a pozzolanic material. In this direction, in Brazil there is a single metakaolin industry in São Paulo operating in the domestic market supplying pozzolanic material for all regions of the country. The researched material was burned in the industry at approximately 700 °C, and its pozzolanic activity was tested by the Luxán test presenting 2.01 mS/cm (good pozzolanicity). The mortars proportions were 1:6 (cement: sand), with the addition of 0% (reference), 10%, 20% and 30% of WCB, and their crystalline phases were analyzed by XRD and it was not identified a kaolinite peak, a good indication of the transformation to metakaolinite. The tests in both fresh and hardened state were performed. For both grindings, the residue reacted with the paste, a fact confirmed by the nucleation calorimetry of particles

The properties of babassu (Attalea speciosa.) fiber was for the first time investigated for potential engineering application such as reinforcement for matrix composites. The diameter distribution of babassu fibers was analyzed and found to be associated with significant variation in fiber density and mechanical properties. Additionally, thermogravimetric and Fourier transform infrared spectrometry (FTIR) analyses were performed. The studied Weibull statistical method was used to analyze the acquired data. The surface morphology of the fibers was studied by scanning electron microscopy. From the diameter ranges, it was possible to confirm that the thinner fibers have higher values of density and mechanical properties, which was attributed to their lower presence of defects. The diameter range was found between of 0.18 and 0.47 mm, and the corresponding densities were 0.79 and 0.27 g/cm³ respectively. Furthermore, the maximum tensile strength found was 100.76 MPa with an elastic modulus of 6.33 GPa and an elongation of 2.98%. Thermogravimetric analyses revealed a three-step mass loss, the main one being the second where the fiber loses 69% of the mass at a temperature of 382 °C. The FTIR analysis showed a similarity with the bands generally found in the literature for natural lignocellulosic fibers.

This study aimed to evaluate the use of sewage treatment plant (STP) waste on the production of red ceramic. The raw materials used were clayey ceramic body and STP waste from Campos dos Goytacazes - RJ. The raw materials were characterized through techniques of X-ray fluorescence and X-ray diffraction; moreover. The thermal behavior of STP waste was evaluated by DSC/TG/DTG analysis. The formulations of the clayeys ceramics were prepared with use 0, 3, 5, 10 and 15 wt% STP waste. Through these formulations, specimens were prepared by extrusion with 30% moisture content and fired at 800 °C. The evaluated physical and mechanical properties of the fired ceramics were water absorption, linear shrinkage, flexion strength and relative density. The microstructure of fired pieces was investigated by scanning electron microscopy. The results showed the STP waste increased the resistance to flexion and water absorption. The use of the waste improved the mechanical strength of the ceramic mass and tended to increase the flexural strength with the increase in the waste content added to the specimen. This type of waste can be aproveited in red ceramic by up to 15% by mass.

Carbon steel is one of the most worldwide applied metallic alloy and commonly used in severe industrial condition specially in the extraction and processing of oil/gas, which make this alloy highly susceptible to corrosion. The use of corrosion inhibitors is mandatory to protect carbon steel in such condition. Conventional corrosion inhibitors, have been for decades the main solution to reduce the corrosive effect on carbon steel. However, the substances used in traditional inhibitors are highly toxic to humans and a threat to the environment. In this context, new substances are being used, such as ionic liquids. This class includes a wide range of molten salts that, owing to their useful combinations of properties are highly effective for many practical applications. In this first review, important advances reported in recent literature are presented, in which the authors applied ionic liquids as corrosion inhibitors for carbon steel in hydrochloric acid. As a comparative effect, all these discussed results were obtained from potentiodynamic polarization tests.

Abstract Pacific clam, Asaphis violascens is a benthic species present in the Indo‐pacific region. It is very much appreciated as food by the local community and its population is diminishing due to overfishing. The aim of this research is to establish suitable rearing conditions for its spawning and larviculture. Two different spawning induction methods were used, emersion and thermal shock. Two stocking densities of larvae were tested (10 and 20 larvae/mL) and three different microalgae diets, one consisting of Tisochrysis lutea as a single species diet and the other two with Ti. lutea combined with Nannochloropsis oculata and Tetraselmis suecica. Emersion of clams was established as a successful spawning induction method. Larval development of A. violascens is similar to other tropical bivalves, having a 10‐day planktonic period at 28°C. An initial stocking density of 10 larvae/mL showed significantly higher (p .05) in growth and survival were found between the diets, proving that the use of Ti. lutea alone or mixed is suitable for their nutrition. The results presented could contribute to the implementation of restorative aquaculture farms in the region, helping to mitigate food security issues in the communities and collaborating with the establishment of healthier coastal ecosystems.

The effect of different surface roughness for ceramic and metals on their adhesive bond strength is widely studied in the field of tribology, but still little investigated for stone claddings, which are natural and quite heterogeneous materials. The main objective of this study was to investigate the relationships between the surface roughness of ornamental stone slabs and their adhesion to mortars were determined by TBS tensile bond strength tests, including observation of types of failure in each test. Slabs with different roughness of the migmatitic stone, commercially known as in Brazil ''Jacarandá Rosado'', were fixed with two types of adhesive mortars, one commercial and the other produced in the laboratory (here referred to as “PM” mortar). Average TBS adhesion values were higher for the rougher plates, as expected, since in this condition there is a larger exposed surface of the minerals, resulting in a greater number of electrochemical charges available to interact with the adhesive mortars. In quantitative terms, the results indicate average values of 1.39 MPa and 1.16 MPa, respectively, for the higher and lower roughness of specimens fixed with Commercial mortar. Regarding the adhesion for PM mortar, values obtained in specimens with smooth, moderately rough and rough surfaces, respectively, were, on average TBS of 2.06 MPa, 1.42 MPa and 1.47 MPa, values higher than for the CM mortar. Importantly, in these last two test conditions, all failures occurred in the stone, indicating that the PM mortar adhered very well to rougher surfaces, i.e., the stone and the standard substrate. So, it is plausible to consider that TBS values of the PM Mortar should be, in practical terms, higher than measured in the tests, since they reflected more conditions of the rock than the mortar. Such information indicates that detailed evaluation of the types of failure in the adhesion tests was important to corroborate the better TBS results for the mortar prepared in the laboratory with CPV-ARI cement.

Tailings from bauxite extraction are worldwide of environmental concern, due to their open-air disposal in landfill dams. Although numerous studies have been dedicated to the application and reuse of wastes from bauxite processing tailings, there is still an important gap regarding the identification of properties that may, enable its application in the development of materials, especially as construction elements. The objective of this research is to characterize environmentally and microstructurally the bauxite waste from processing tailings produced in the state of Pará, Brazil, aiming at a combined characterization and discussion that evaluates its potential applications, as possible alternative to simple disposal in landfills. Chemical characterization analyzes were performed by X-ray fluorescence (XRF), mineralogical by X-ray diffraction (XRD), morphological by Scanning Electron Microcopy (SEM) and Transmission Electron Microscopy (TEM) combined with Energy Dispersive Spectroscopy (EDS). In addition, physical analyzes were performed by granulometry, surface area measurement (BET) and Luxán pozzolanicity. Environmental analyzes were carried out through solubilization and leaching. The results obtained by chemical and mineralogical analyzes indicate that the material is an aluminosilicate with a high content of amorphous components, which allows it to be used as a pozzolan in either cementitious materials or as a precursor in alkali activated materials or else as a plasticity reducer in red ceramics. The results were confirmed by thermal analysis and by pozzolanicity test. Thus, it is possible to conclude, based on the characterization of the bauxite waste, that the material has potential for use in alternative construction materials, contributing to the sustainable development of civil construction.