Following a brief description of personal background, a timeline of academic, administrative and scientific activities during 60 years will be presented. Initially, as a graduate student, contributing to the creation of the Master and Doctoral Program in Metallurgical Engineering at the Federal University of Rio de Janeiro, COPPE/UFRJ. Following a post doctorate at the University of Stuttgart, Germany, assumed administrative positions as Head of Department, Coordinator of COPPE, Under-Rector for Research of UFRJ and Under-Secretary of the Ministry of Education in Brasilia, Brazil. Since MSc and PhD graduate period, at the Department of Materials Science and Engineering of the University of Florida, has published more than 2,300 articles associated with more than 20,000 citations and a H index of 72 (Google Scholar). Received several awards, including ASM Fellowship, Brazilian Army Medal as well as several TMS distinctions. Consultant of the main Brazilian R&D agencies and Executive Editor of Elsevier’s Journal of Materials Research and Technology. Finally life-learned lessons will be described.

Pollution has profound impacts on human health, the environment, and Earth's systems, including climate regulation. Its reach is global, affecting our well-being through contaminated food, water, and air. Material engineers and scientists play a crucial role in addressing these challenges through innovative materials and manufacturing techniques. One promising sustainable solution involves utilizing eco-friendly materials sourced from nature.

In this presentation, we delve into natural fibers, exploring their fundamentals to practical applications for engineering. Natural fibers are more environmentally conscious and sustainably produced. These fibers and their composites offer a sustainable alternative, being both environmentally conscious and responsibly manufactured. They can be transformed into functional materials suitable for various uses, displaying their versatility and potential.

Most of the fibers have been used for centuries by ancient communities, forming a fascinating field known as cultural materials research. It will focused on fibers sourced from the Andes Mountains and the Amazon River region, in the traditional uses, microstructure, properties, and their potential applications in modern materials engineering. 

The processing of solid wood generates a large amount of waste, which alternatively to disposal and burning in the open air, these can be used in the manufacture of wood products. Among the various stages of production of particleboards, the homogenization process requires consumption of energy, time and labor, and its eventual suppression would certainly result in a reduction in the cost of manufacturing these materials. As there are several properties resulting from the characterization of panels, obtained in equipment generally available in large research centers and branch companies, the relation of properties through mathematical models makes it possible to reduce the volume of tests, as recommended by the Brazilian standard [1]. This research aimed, with the use of a mix of wood shavings (fine particle formed in processes such as planing and thinning wood) in the integral form (without dimensional classification) of Pinus elliottii and Pinus taeda woods (12% moisture content) and of the urea-formaldehyde adhesive, to evaluate the feasibility of producing medium and high density particleboards, the influence of density (medium and high) of composites on the physical and mechanical properties as well as evaluating the possibility of estimating properties as a function of others by linear regression models, also considering colorimetric parameters. Six medium and six high density particleboards were produced considering the use of 15% adhesive content, with the proper use of only 11% adhesive. The physical and mechanical properties were obtained according to the assumptions and calculation methods of the Brazilian standard [2], with the requirements being evaluated based on this and some international standards. In general, the density of the panels was significant in practically 50% of the determined properties. The particleboards can be classified as P2 by the Brazilian standard [2], it should be noted that in some properties the values exceeded the P7 class. The results of thermal conductivity show the potential for application of the panels in buildings. The surface roughness was considered intermediate (class N7 of Brazilian standard [3]). From the regression models, only four of the twenty generated had a coefficient of determination close to 70%, however, because they are all considered significant, a greater number of samples and experimental conditions should be considered for more robust conclusions, should be the objective of future research.

This research summarizes results regarding a vegetable natural fiber from Colombia, produced in the leaves of the fique plant, a species from the genus Furcraea andina. Fique is a strong natural fiber used for centuries for local indigenous peoples in Colombia, and later used for farmers and locals to produce crafts, clothes, shoes, and bags, among other traditional objects. Recently, fique has been used in combination with clays and cements as a construction material, and also as a reinforcement in polymer matrix composite in a strong collaboration between Colombia and Brazil, particularly for ballistic protection and other dynamic applications. Tensile tests and scanning electron microscopy characterization is presented here, with a discussion of possibilities for fique in engineering.

Polymeric materials are essentially insulating, but they have unique properties such as low density, high resistance to corrosion, ease of processing and lower cost compared to metallic and ceramic materials. Polymethyl methacrylate (PMMA), a polymer commercially known as acrylic, is known as a low-cost material with very interesting properties to be applied in engineering, such as transparency, mechanical resistance, electrical insulation and good thermal stability [1] [2]. Since the discovery of graphene, polymeric composite materials based on graphene and its derivatives have been explored in both academic and industrial research, due to the possible dispersion of carbon in the polymeric material, offering thermal and electrical properties to the polymer. The structure of graphene is made up of a two-dimensional sheet with a network of hexagons, formed by carbon atoms with sp^2 hybridization [3]. Graphene oxide can be obtained by functionalizing graphene through its exfoliation, presenting intercalated regions with sp^2 and sp^3 hybridized carbons, as well as hydroxyl and epoxy functional groups on its basal planes, which increase its interaction with the polymer matrix. This interaction improves the mechanical fit at the interface between the filler and the matrix, and its two-dimensional geometry may be responsible for increasing the stiffness of the composite [4].

Therefore, microcomposite films of PMMA and rGO with different concentrations were produced. The physicochemical changes were evaluated by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). The morphological characteristics were observed by scanning electron microscopy (SEM).

The DSC test showed that the addition of filler to the polymer made the material (microcomposite) more thermally stable and indicated greater rigidity of the PMMA macromolecules in the microcomposites as the concentration of rGO increased.  FT-IR analysis revealed the characteristic groupings of both PMMA and rGO, indicating that the matrix interacted with the filler, as was also observed in the topography of the material by SEM. These factors indicate that the higher the concentration of rGO, the greater the chance that PMMA, being an insulating material, will be transformed into a semiconductor/conductor material.

The genus Sporobolus (Poaceae Chloridoideae) consists of approximately 160 species of tropical and subtropical grasses. In Brazil, this genus is represented by 28 species, among which Sporobolus indicus stands out, a perennial species, made up of two varieties (indicus and pyramidalis), distributed throughout the national territory. In a 1979 botanical survey, in degraded pastures, in the northeast (Paragominas) and south (Santana do Araguaia) of the state of Pará, Brazil, Sporobolus indicus is not listed as a frequent species, although it is present in Santana do Araguaia. That said, this work aims to present a study on a polyester composite reinforced by Sporobolus indicus fibers. The composites were manufactured with fiber in different lengths, 5, 10 and 15 mm, added discontinuously. A tensile test was carried out following the ASTM D 638M standard. A composite of the same matrix was also manufactured with the aforementioned fiber, unidirectionally aligned. The tensile test was carried out according to the ASTM D 3039 standard, in order to compare results. It was possible to notice the behavior of the composite by varying the length of the reinforcement introduced into the matrix. The mechanical resistance showed growth proportional to the growth of the fibers, with the values found for the composite reinforced with discontinuous fibers being 11.33, 12.10 and 14.95 MPa, respectively, in increasing order according to the size of the fibers, while the results for the specimens reinforced with unidirectionally aligned fibers were 18.84 MPa. This occurs due to the alignment of the reinforcement within the mold, where in a length of 5 mm, many fibers were arranged transversely to the direction of application of the load on the specimen, not cooperating with the resistance and causing failure mechanisms. At a length of 15 mm, the fibers were distributed longitudinally in the center of the specimen, coinciding with the direction of load application and enabling greater tensile strength.

Due to the development of novel technologies, there emerges a demand in the industrial sector for new materials with enhanced properties. In this context, new applications are being explored for structural composites, typically involving continuous fibers characterized by low density, high strength, and high elasticity modulus, such as carbon fibers, extensively utilized in industries such as automotive, food, aerospace, household goods, and others. However, environmental concerns are also on the rise, prompting the substitution of synthetic fibers with lignocellulosic fibers (LF) like jute fibers, sugarcane bagasse, coconut, banana, among others. The use of natural fibers instead of synthetic fibers brings about various benefits to the industrial sector. Apart from being a renewable source, LF is biodegradable and cost-effective, given their common discard and lack of market value. Within the realm of many fibers scrutinized in composite materials, one finds the fibers extracted from the açaí palm stem (FEFAPS). According to Embrapa (Brazilian Agricultural Research Corporation), Brazil stands as the leading producer, consumer, and exporter of açaí globally, with consumption primarily concentrated in the northern regions of the country. A study conducted by Embrapa indicates a 675% increase in the planted area of açaí cultivars (Euterpe oleracea) for upland regions developed through agricultural research in the past 12 years. Within this backdrop, this study aims at producing polymeric composites with polyester matrix reinforced with FEFAPS at varying weight concentrations (0, 10, 20, and 30%). Tensile tests were conducted following ASTM D3039 standards, alongside impact energy assessment via Charpy testing based on ASTM D6110-18 norms, and thermogravimetric analyses (TGA) under inert N2 atmosphere, ranging from 30°C to 600°C with a heating rate of 10°C/min. For morphological evaluation, the fracture surfaces post-tensile tests were scrutinized utilizing Scanning Electron Microscopy (SEM). The tensile test results depict a linear increase in maximum tensile strength of composites with FFSAPT addition, reaching up to 48 MPa. Regarding Charpy impact tests, a progressive rise in absorbed energy until rupture was observed, with 30% composites exhibiting growth of up to 2301% compared to pure polyester. Thermal analysis demonstrated no alteration in thermal resistance with FEFAPS inclusion, with degradation onset temperatures hovering around 300°C. Lastly, SEM micrographs exhibited weak interaction between fibers and the matrix, a characteristic trait of lignocellulosic fiber-reinforced composites. In conclusion, this study establishes the successful application of FEFAPS in polymeric composites, ushering in a new perspective for their utilization and the valorization of residues generated during açaí ice cream production, commonly employed in Brazil.

This study explores the importance of simulations conducted with MCNP5 and the modifications implemented in 316 steel to optimize energy efficiency in nuclear power production. Molybdenum (Mo) is investigated as a promising additive due to its low absorption cross-section for thermal neutrons, which enhances neutron participation in fission and heat generation. Using the MCNP5 code, simulations were performed to analyze a hypothetical UO2 fuel element with different enrichment zones to evaluate its performance[1-3]. The results indicate that incorporating molybdenum into the fuel cladding alloy significantly impacts neutron production, suggesting that this addition might affect energy generation efficiency. In summary, this study highlights the potential of molybdenum as an additive to improve nuclear fuel performance[4-8], promoting safer, more efficient, and sustainable nuclear energy. The comparison of the results from the two simulations allowed for the assessment of the impact of molybdenum inclusion on the criticality of the simulated fuel. Conversely, if the inclusion of molybdenum does not positively influence or even reduce the fuel's criticality, this suggests that such a strategy is not viable for optimizing nuclear fuel performance. Therefore, the results of this analysis have significant implications for the development of more efficient and environmentally sustainable nuclear fuels. The effective multiplication factor (keff) obtained for the clad rod under study was keff=1.12086 ± 0.00064, while the reference value without doping was keff=1.04355 ± 0.00076, resulting in a relative percentage deviation of approximately 6.897%. Doping 316 steel with molybdenum nanoparticles presented a significant alteration in neutron production, suggesting that this addition may compromise energy generation efficiency.

The advancement of materials research for the nuclear industry is growing as energy demand increases [1],[2]. As a result, new materials are being explored to improve the efficiency of nuclear applications. Molybdenum has been studied for decades as an alloying element due to its low thermal neutron absorption cross-section and high strength under nuclear reactor temperature conditions [3],[4]. A critical reactor condition is understanding how fuel rods behave during the fission reaction of UO2 pellets [5],[6] and, consequently, how heat transfer occurs in this process. To understand these key characteristics, a study was conducted on the criticality of a fuel rod clad with Zircaloy doped with molybdenum nanoparticles [7],[8] using MCNP code simulations. Simulations of the fuel element were performed with a 3.2%, 2.5%, and 1.9% UO2 enrichment distribution based on a hypothetical PWR reactor model [6]. A hypothetical fuel element for a hypothetical PWR reactor was simulated using the MCNP5 software. The element consisted of 25 fuel rods with UO2 pellets with three enrichment zones (3.2%, 2.5%, and 1.9%), as shown in Figure 1, and a height of 3.6 m. The kcode was used in the simulation to calculate the criticality of the simulated fuel. 10,000 neutrons per cycle and a total of 100 cycles were used, with 50 of them being passive. To achieve the objective of the work, the first simulation was performed with pure Zircaloy-4, and this result was considered as the reference standard criticality for the fuel element. The second simulation was performed with this alloy doped with 10% molybdenum.The result obtained for the effective multiplication factor (kef f ) with the coated rod under study was equal to kef f = 1.314503 ± 0.0007, which when compared to the reference value without doping kef f = 1.39207 ± 0.00072, a relative percentage deviation of approximately |δ| ≈ 5.57% is obtained. Doping Zircaloy with molybdenum nanoparticles does not significantly alter neutron production. This enables the improvement of the alloy without loss of energy production efficiency. The results of the simulations indicate that the doping of Zircaloy with molybdenum nanoparticles does not significantly alter the neutron production of the fuel rod. This is an important finding, as it suggests that the addition of molybdenum nanoparticles can improve the properties of the Zircaloy alloy without sacrificing its efficiency in terms of energy production. The relative percentage deviation of |δ| ≈ 5.57% between the kef f values for the doped and undoped rods is considered to be small. This suggests that the doping of Zircaloy with molybdenum nanoparticles does not have a significant impact on the criticality of the fuel rod. Overall, the results of this study suggest that the doping of Zircaloy with molybdenum nanoparticles is a promising approach for improving the properties of the alloy without sacrificing its efficiency in terms of energy production. Further research is needed to confirm these findings and to explore the potential benefits of molybdenum doping in more detail.

This study explored the influence of incorporating silicon carbide (SiC) nanoparticles into Stainless Steel 316 on the performance of nuclear fuel using computational simulations with the MCNP5 software[1]. The findings revealed that the introduction of SiC had minimal impact on the effective multiplication factor (keff), suggesting that this modification could be a viable approach to enhancing fuel characteristics without compromising efficacy[2-3]]. Furthermore, the integration of SiC could provide added advantages such as improved thermal stability and resistance to corrosion. These results underscore the potential of SiC as a promising additive for enhancing the safety and efficiency of nuclear fuel elements in reactors, opening avenues for future advancements and research in nuclear energy[4-5]. The results for the effective multiplication factor (keff) with a rod coated and doped with 10% SiC showed keff = 1.12759 ± 0.00064. Compared to the undoped reference value of keff = 1.12086 ± 0.00064, there is a relative increase in criticality of approximately 0.6%. The computational simulation using MCNP5 with kcode provided a detailed analysis of nuclear fuel criticality. The data indicate that doping Stainless Steel 316 with SiC nanoparticles increased the effective multiplication factor (keff) by about 0.6%. This suggests that adding SiC significantly affects neutron production, which is crucial for the safety and efficiency of nuclear reactors[6]. These results point to potential improvements in nuclear fuel performance. Including SiC may offer additional benefits such as greater thermal stability, corrosion resistance, and reduced deformation, contributing to the safety and longevity of fuel elements[7-8]. Moreover, maintaining energy production without compromising neutron efficiency is promising, allowing for advancements in the materials used in nuclear reactor construction. Therefore, the neutron results obtained in this simulation highlight SiC's potential as an effective additive to enhance nuclear fuel properties, paving the way for future research and developments in nuclear energy.

This study explores the significance of simulations performed in MCNP5 and the modifications applied to 316 steel to enhance energy efficiency in nuclear power production. Graphene Nanotubes (GNTs) are examined as promising additives owing to their low absorption cross-section for thermal neutrons, facilitating increased neutron involvement in fission and heat generation. Using the MCNP5 code[1], simulations were carried out to analyze a hypothetical UO2 fuel element with varying enrichment zones to assess its performance[2,3]. The findings underscore the substantial impact of incorporating graphene nanotubes[4] into the fuel cladding alloy on neutron production, implying a potential compromise in energy generation efficiency. The comparison between the results of two simulations allowed us to assess the impact of including graphene nanotubes[5,6] on the criticality of the simulated fuel. If the addition of these nanotubes [7] results in an improvement in criticality, this may indicate superior performance of the nuclear reactor, with higher fuel efficiency and reduced nuclear waste generation. On the other hand, if the inclusion does not positively affect or even reduces criticality, this suggests that this strategy is not viable for optimizing nuclear fuel performance [8]. Therefore, the results of this analysis have significant implications for the development of more efficient and environmentally sustainable nuclear fuels. The result of the effective multiplication factor (keff) for the studied clad rod was keff=1.12086 ± 0.00064, while the reference value without doping was keff=1.13565 ± 0.00076, resulting in a relative percentage deviation of approximately Δ = -1.32%. Doping 316 steel with graphene nanotubes causes a significant alteration in neutron production, which may compromise efficiency in energy generation.

In this research, the relevance of polymers in our daily lives, in the industrial market, in the development of new technologies, and the harmfulness of the waste generated by these polymers to human health and the environment are observed. By applying and analyzing techniques such as thermal analysis, microscopy, spectroscopy, and diffraction, we explore a composite that contains polymers, organic residues, and metallic residues. Thermal analysis, microscopy, spectroscopy, and diffraction highlight essential behaviors of the material for a process focused on sustainability. Understanding the characteristics of this type of material is crucial for developing processes that transform polluting materials into relevant and economically viable products, with the aim of mitigating human health impacts and environmental impacts. This research validates the use of thermal analysis, microscopy, spectroscopy, and diffraction techniques to characterize and understand complex polluting composites and enhance their applications in new processes and consequently in new sustainable products worldwide, respecting and preserving the environment for future generations.

The embira bark fiber is routinely used in Brazil to construct simple structures because of its ease of extraction, flexibility, and considerable strength. It plays an important role, somewhat similar to duct tape, and is commonly used for temporary repairs and tying objects. The flexible bark is removed from the tree by making two cuts into it and manually pulling off the fibrous structure. Three similar but distinct embira bark fibers are characterized structurally and mechanically: embira branca, embira capa bode, and embira chichá.  The bark separates readily into strips with thicknesses between 0.3 and 1 mm, enabling it to be twisted and bent without damage. The structure consists of aligned cellulose fibers bound by lignin and hemicellulose. Thus, it is a natural composite. The tensile strength of the three fibers varies in the range of  25 to 100 MPa, with no clear difference between them. There is structural and strength consistency among them. The mechanical strength of embira branca is measured with other lignocellulosic fibers X-ray diffraction identifies two major components: the monoclinic crystalline structure of cellulose and an amorphous phase; the crystallinity index is approximately 50%.