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.

Noise pollution is increasingly recognized as a public health issue, with studies linking excessive noise exposure to a range of adverse health problems, such as sleep disturbance, stress-related disorders, cardiovascular diseases, and cognitive impairment. This growing awareness of the detrimental effects of noise pollution has underscored the importance of acoustic comfort in buildings on a global scale, highlighting the control of noise propagation in determining the final quality of architectural projects.In response to this recognition of the importance of acoustic building comfort and the elevated frequency of complaints of users regarding noise generated, particularly in multi-story buildings, Brazilian Standard was implemented in 2013. This standard is designed to guarantee acoustic performance and meet the expectations of building users by setting forth acceptable noise transmission levels. Furthermore, in 2021, additional standards addressing acoustic insulation and field measurements of airborne noise were also introduced [7,8], further solidifying the commitment to ensuring optimal acoustic conditions within buildings and enhancing occupant comfort and well-being. The imperative of establishing conducive acoustic environments led to an increase in research and development efforts, resulting in novel materials and construction methodologies attuned to the exigencies of architecture. It is known that to achieve the goal of mitigating sounds transmitted through a building structure, it is essential to disrupt the rigid connection responsible for propagating mechanical vibration. The incorporation of highly porous materials into floors offers potential for bolstering sound absorption capabilities. Strategies such as altering the impact surface, using elastic separation, or introducing resilient materials between the floor covering and structural slab prove to be efficient and became common. Despite these solutions demanding specialized labor for execution, there remains a dearth of research assessing their actual acoustic performance.Integrating environmental awareness with advances in acoustic engineering, civil construction emerges as a leading sector actively integrating recycled solid waste into building components to promote sustainability, consequently enhancing acoustic performance [1,2]. These solutions not only exhibit superior soundproofing characteristics but also complement sustainability goals.An example of waste that is readily and abundantly found in Brazil, and, above all, must be handled properly, is the end-of-life tire. This material has been the focus of numerous studies exploring its integration into mortars [3-5]. According to Institute of Environment and Renewable Natural Resources [6], over a million new tires were manufactured, generating more than five hundred thousand tons of end-of-life tire waste in Brazil in 2017. Furthermore, tire rubber is classified as Class II non-hazardous waste, indicating that it poses no potential risks to the environment and public health [7].To actively contribute to the mitigation of noise in multi-story buildings and to further the goals of sustainability, this study delves into the incorporation of rubber derived from end-of-life tire waste into the mortar used for subfloor applications. The investigation aims to assess the effectiveness of this innovative approach in enhancing acoustic insulation and promoting environmentally conscious construction practices.

One of the most important applications of material processing has been the protection of humans and their facilities during times of war. With the creation of firearms, there arose a need for the enhancement of this protection, now known as ballistic protection. Materials for ballistic protection and their processing are the focus of research around the world. One of the biggest challenges is to develop materials light enough for personal protection. A promising material for this kind of application is silicon carbide, that absorbs approximately 55% of the energy by breaking upon projectile impact. However, one of the challenges in processing this material lies in the temperature required for sintering. Temperatures above 2000°C and small volume of economically accessible furnaces hinder parameter control and limit the size of the pieces. The additive manufacturing process, that up to now has been successfully applied to produce polymer and metal pieces, is now being studied as a possible processing method for ceramic materials. In this review, we discuss the evolution of additive manufacturing with a focus on the processing of ceramic materials and, primarily, silicon carbide, with the purpose of presenting existing technologies in the market and the stages of the process, as well as a brief comparison between the characteristics of materials submitted to conventional processing and additive manufacturing.

Advancements in materials research for the nuclear industry coincide with the rising energy demand [1],[2]. Consequently, discussions around new materials aim to enhance the efficiency of their applications within the nuclear domain. An essential aspect of reactor operation involves understanding the behavior of fuel rods during UO2 pellet fission reactions [3],[4], and consequently, the heat transfer mechanisms involved in this process. To delve into these pivotal characteristics, a study was conducted on the criticality of a fuel rod clad with Zircaloy doped with graphene nanotubes [6],[7] via simulation using the MCNP code. Simulations of the fuel element were conducted with enrichment distributions of 3.2%, 2.5%, and 1.9% of UO2, based on a hypothetical PWR type reactor model [5]. The hypothetical scenario considered a fuel for a PWR reactor comprising 25 fuel rods with UO2 pellets exhibiting three enrichment zones of 3.2%, 2.5%, and 1.9%, as illustrated in Figure 1, with a height of 3.6 m, simulated using the MCNP5 software. To fulfill the study's objective, the first simulation involved pure Zircaloy-4, serving as the reference standard for criticality of the fuel element. Subsequently, another simulation entailed this alloy doped with 10% of graphene nanotubes. The result obtained for the effective multiplication factor (keff) with the coated rod under study was keff = 1.39132 ± 0.00064. When compared to the reference value of the hypothetical fuel element keff = 1.39207 ± 0.05, a relative percentage deviation of approximately δ ≈ 0.1% was observed. Based on this analysis, it can be concluded that doping Zircaloy-4 with 10% graphene nanotubes does not significantly alter the criticality parameter, indicating no significant changes in the neutronic parameters. Subsequent steps of the study will focus on assessing the heat transfer efficiency of the doped cladding and any associated mechanical alterations.

The emergence of diseases caused by the advent of human aging has led to the development of materials in bone tissue engineering (BTE) that can aid in the development of clinical treatments. Among these materials is the development of synthetic bone grafts through additive manufacturing. In this study, the scaffolds were developed by fused deposition modeling (FDM) using polylactic acid (PLA) doped with hydroxyapatite (HA) extracted from the scales of the pirarucu (Arapaima gigas). Fourier transform infrared spectroscopy (FTIR) analysis reveals bands at 1096 cm-1; 1018-1011 cm-1, 602 - 555 cm-1 that are attributed to calcium phosphate and hydroxyapatite minerals. Thermal analysis reveals four periods of weight loss, related to moisture loss, elimination of organic compounds, carbonation and removal of hydroxyls from HA sites. The addition of HA resulted in a decrease of 20.38% in compressive strength and 25.67% in apparent compressive modulus. Obtaining compressive strength of 3.14 MPa and 2.5 MPa, respectively, for samples SFP and SF1H and, respectively, compressive modulus of 108.55 MPa and 80.68 MPa.

To complement the previous results, an analysis of the chemical and morphological properties of babassu fibers (Attalea speciosa Mart. ex Spreng.) was carried out in order to assess their potential as reinforcement in the production of epoxy matrix composites. The diameter distribution was analyzed in a sample of one hundred fibers, allowing its variation to be verified. Determination of the chemical properties involved experimental analysis of the constituent index and X-ray diffraction. The diffractogram was used to calculate the crystallinity index and microfibrillar angle, crucial parameters that indicate the consistency of the mechanical properties of babassu fibers and the viability of their use in composites. The results showed that babassu fiber has a chemical composition of 28.53% lignin, 32.34% hemicellulose and 37.97% cellulose. It also had a high crystallinity index of 81.06% and a microfibril angle of 7.67°. These characteristics, together with previous results, indicate that babassu fibers have favorable chemical and morphological properties for use as reinforcements in composites, highlighting their potential as an important material for applications in technological areas.

The ballistic performance of epoxy matrix composites reinforced with 10, 20 and 30% by volume of babassu fibers was investigated for the first time. The tests carried out included Izod impact tests and ballistic tests with 0.22 caliber ammunition. The Izod impact tests showed significant improvements with increasing babassu fiber content, indicating greater strength of the composites. Scanning electron microscopy analysis revealed the fracture modes of the composites, highlighting brittle fractures in the epoxy matrix, as well as other mechanisms such as fiber breakage and delamination in the fiber-reinforced composites. In the ballistic tests, a significant increase in the energy absorbed by the composites was observed. All composites outperformed pure epoxy by more than 3.5 times in ballistic energy absorption, highlighting the potential of babassu fibers for engineering and defense applications. These results indicate that babassu fibers can be an effective and sustainable alternative for improving the performance of composite materials.

Composite materials are engineered by combining two or more materials with distinct properties, yielding a material with superior characteristics compared to its individual components. These composites often find application in shielding against ionizing radiation [1]. This study aims to assess the transmission factors of an epoxy matrix composite embedded with silica (SiO2) nanoparticles, at proportions of 10%, 30%, and 40%, for electromagnetic radiation and neutron shielding purposes. A computational model was developed to evaluate radiation transmission through simulations using the Monte Carlo method with MCNP5 [2],[3]. Three composite configurations with varying silica nanoparticle concentrations in the matrix were analyzed. The experimental setup was chosen based on prior research, with a sphere radius of 1 cm adopted. The simulations encompassed fast neutrons (8 MeV, 6 MeV, and 1 MeV), epithermal neutrons (1 eV), and thermal neutrons (0.025 eV and 0.001 eV) [4],[5]. Tally F1 was utilized for both photons and neutrons, discretized into 100 energy intervals to gather transmission factor data [6]. Notably, no significant alteration was observed in electromagnetic radiation transmission with the addition of material across the studied energy levels. However, the composite materials exhibited favorable attenuation properties for fast and thermal neutrons. Particularly, a substantial enhancement in shielding efficiency against 1 MeV neutrons was noted with the incorporation of fibers. Consequently, the composite material demonstrated superior performance in shielding fast neutrons, aligning with existing literature [7]. Furthermore, the composite exhibited a notable upscattering rate, prompting further investigation into the contributing elements.

Materials and that can be used to protect against ionizing radiation. [1] The present work aimed to calculate the transmission factors of the epoxy matrix composite with graphene nanotubes at the proportions of 10%, 30%, and 40%, respectively, for use as shielding for electromagnetic and neutron radiation.A computational model was created to evaluate, through simulation using the Monte Carlo method with MCNP5, the radiation transmitted by epoxy-based polymer matrix composite materials and graphene nanotubes [2],[3]. Three study model compositions with 10%, 30%, and 40% graphene nanotubes in the matrix were analyzed. Initially, the designed setup was chosen because it had already been used in other works. The experiment was also simulated for fast neutrons (8 MeV, 6 MeV, and 1 MeV), epithermal neutrons (1 eV), and thermal neutrons (0.025 eV and 0.001 eV) with energies [5],[6]. For both photons and neutrons, the Tally F1 was discretized into 100 energy intervals to obtain data for calculating the transmission factor [4]. It is observed that for electromagnetic radiation, there is no significant change with the addition of material for the energy levels presented. However, the material composites behave relatively well for the attenuation of fast and thermal neutrons. It can be seen that for 1 MeV neutrons, the material composite had a significant improvement with the addition of fiber. Therefore, it is concluded that for fast neutron shielding, the material composite performed better. It can be seen that the composite in question showed a high upscattering rate, and it should be analyzed which element acted for this.

As energy demand rises, the drive for materials research in the nuclear industry intensifies [1],[2]. Consequently, discussions center on novel materials aimed at enhancing efficiency within the nuclear domain. Presently, ongoing studies focus on the utilization of SiC in nuclear power plants, owing to its proven efficacy in averting hydrogen gas emissions during LOCA-type accidents [3][4].  A concern in reactor operations is comprehending the behavior of fuel rods during the fission process of UO2 pellets [5],[6], and the ensuing heat exchange mechanisms. To unravel these key characteristics, a study scrutinized the criticality of a fuel rod sheathed in Zircaloy doped with SiC nanoparticles [7],[8], employing simulation via the MCNP code. Simulations of the fuel element encompassed an enrichment distribution of 3.2%, 2.5%, and 1.9% of UO2 based on a hypothetical PWR reactor model. Utilizing the MCNP5 software, a hypothetical fuel assembly for a PWR reactor was modeled with 25 fuel rods housing UO2 pellets across three enrichment zones (3.2%, 2.5%, and 1.9%) and standing 3.6 meters tall. The simulation employed the kcode method to compute the criticality of the simulated fuel, with 10,000 neutrons per cycle over a total of 100 cycles, half of which were passive. To fulfill the study's objective, the initial simulation employed pure Zircaloy-4 as a reference standard for fuel element criticality, with a subsequent simulation incorporating this alloy doped with 10% SiC. The resultant effective multiplication factor (keff) for the coated rod was calculated as keff = 1.39132 ± 0.00064, compared to the reference value of keff = 1.39207 ± 0.00072, yielding a relative percentage deviation of approximately |δ| ≈ 0.054%. Notably, doping Zircaloy with SiC nanoparticles demonstrated no significant alteration in neutron production, facilitating alloy enhancement without compromising energy production efficiency. The simulation results suggest that the addition of SiC nanoparticles can enhance the properties of Zircaloy alloy without sacrificing energy production efficiency. The minor relative deviation between the keff values for doped and undoped rods indicates insignificant impact on fuel rod criticality. Overall, this study underscores the promise of SiC nanoparticle doping in improving alloy properties, necessitating further research to validate these findings and explore potential benefits in greater detail.

Several applications were investigated, including fuel rod coatings, structural alloys, and cooling materials in nuclear reactors, with an emphasis on enhancing performance, safety, and durability [1]. The results demonstrated that niobium doping offers numerous benefits, such as improved corrosion resistance, increased stability in high-temperature and radiation environments, and a reduction in criticality of nuclear fuel elements [2-3]. These findings highlight the potential of niobium as a strategic material in the nuclear industry, providing promising solutions to the challenges of safe and efficient nuclear reactor operations, including those of small modular reactors (SMRs)[4]. The effective multiplication factor (keff) for a rod coated with 10% niobium was keff = 1.10807 ± 0.00058. Compared to the undoped reference value of keff = 1.12086 ± 0.00064, there is a relative reduction in criticality of approximately 1.14%. The computational simulation using MCNP5 with kcode provided a detailed analysis of nuclear fuel criticality. The results showed that doping Stainless Steel 316[5-6] with niobium reduced the effective multiplication factor (keff) by about 1.14%. This suggests that adding niobium significantly affects neutron production, crucial for PWR nuclear reactor operation. This reduction indicates niobium's effectiveness in controlling nuclear reactions and mitigating reactor operation risks[7-8]. Thus, niobium plays a key role in optimizing the performance and safety of nuclear fuel elements. The potential application of niobium in small modular reactors (SMRs) will be studied, as it could significantly enhance the safety, efficiency, and durability of next-generation nuclear energy systems. Its unique properties make it a valuable material for a wide range of applications in the nuclear industry.

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.

Three-dimensional (3D) composites have emerged as a solution to the limitations of two-dimensional (2D) laminates, such as low impact toughness, poor damage tolerance, and high susceptibility to delamination. The fabrication of 3D fibers involves techniques such as weaving, braiding, knitting, Z-pinning, and stitching. The stitching method consists of inserting reinforcing threads, typically made of carbon, glass, or aramid, in the thickness direction. Stitched 3D composites already have significant applications, primarily in the aerospace and aeronautical industries, but they are also being noted in the naval and automotive industries [1]. Under specific configurations, stitching has demonstrated the ability to improve impact resistance at different velocities. An increase in the Charpy impact resistance of 3D composites compared to laminates has been identified [3]. Additionally, an increase in the ballistic impact resistance of woven 3D composites has been observed. This improvement was associated with the stitching's ability to divert the projectile's path. Furthermore, the role of the reinforcing bundles in absorbing deformation energy and preventing interlaminar shear failures was highlighted, ensuring that the fibers reach their maximum tensile strength potential [4]. 

This study analyzed the configurations of 3D and 2D composites. Samples of aramid fabric fully stitched with aramid bundles were fabricated. Subsequently, all samples were impregnated with epoxy resin using the resin infusion technique. The preliminary results of the test firing of a .45 caliber projectile were promising. Both configurations demonstrated the ability to retain the projectile that struck the plates with 450 Joules. However, the 3D composites exhibited an indentation caused by the projectiles that was smaller than that of the 2D composites. Upon observing the composite, no delaminations were identified in the 3D composite plates, suggesting that the stitching capability contributes to containing the propagation of delamination.

Plastics are a necessity in today’s economy, being present in all the industrial and domestic sectors. The worldwide production of plastics about 200 million tons in 2000, 400 million tons in 2022 with an annual growth rate of 11% per annum. Basically, they are produced from petrol products and the disposal of pervasive plastic waste is a growing worldwide concern, and these materials generates large amounts of greenhouse emission which contributes to global pollution. This study examined the combined effects of coupling agent developed locally and Pineapple Leaf Fiber (PALF) different % loading on the mechanical and thermal characteristics of recycling polypropylene (r-PP) which was produced using twin screw extruder melt compounding. The PP grafted with maleic anhydride (MA) (PP -g-MA) was used as a coupling agent to improve the interfacial adhesion between recycling PP with PALF. The extent of grafting level was confirmed with FTIR. The results demonstrated the dependence of thermal stability and tensile properties on the grafting level of PP-g-MA, and weight percentage of PALF. Thus, it could be deduced that combination of PALF at high weight percentage (5, 10 and 15wt%) and PP-g-MA with high grafting level can significantly improve the thermal stability of recycling PP. The morphological analysis indicated better adhesion between PALF and recycling PP, in composites containing PP-g-MA with high grafting level. Overall, Recycling PP/PALF/PP-g-MA composites with improved interfacial adhesion and thermal stability and young’s modulus were successfully prepared, in the presence of PP-g-MA with high grafting level.

Fiber-reinforced polymer composites are widely used in various industries, such as defense, aeronautics, aerospace, civil construction, and sporting goods. These structures often face high mechanical stress situations, such as dynamic and static loads in structural applications. Generally, the matrix-fiber interface plays a crucial role in the mechanical strength of composites. Issues such as inadequate adhesion between the fiber and the polymer matrix can reduce load transfer, resulting in lower mechanical performance of these materials. In recent years, numerous studies have focused on optimizing this interface to enhance the properties of composites, including fiber surface treatments, the use of coupling agents, and improvements in matrix chemistry [1]. This work aims to review some of these parameters, which can be controlled by engineers during the design phase to improve the performance of fiber-reinforced polymer composites according to their applications [2]. The review highlights recent progress made to overcome the mechanical limitations presented by this class of materials, focusing on improving strength through the optimization of the matrix-fiber interface, presenting an updated overview of the state of the art on the topic [3].

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.

Nowadays, sustainability and good use of resources and waste are necessary. So, this work seeks to synthesize a ceramic material from natural waste, as well as its characterization and biological evaluation after all the steps that anticipate in vivo application. In this way, brushite, which is a dihydrate dicalcium phosphate mineral that is a calcium phosphate present in the natural mineralization of tissues, can be obtained synthetically from chicken eggshells. It is used as a biomaterial for different applications such as medical treatment, especially orthopedic treatment and bone repair, agrobiological inorganic fertilizers. Brushite has the property of adsorbing ions and changing its active sites with calcium, such as Zn and Ag ions, which can enhance the biocompatible and bactericidal potential of the biomaterial, respectively. In this work, we started with the synthesis of bruxite nanopowders (previously performed) that was characterization by microscopy and physical-chemistry analysis (MEV-topography, MET-nanoscale, FTIR-chemistry-group, XRD Rietveld- material identity). The cytotoxicity was then tested by in vitro microbiological analysis in a nutrient medium using 3 species of bacteria was made ISO-10993-5- ceramic tests. The results shows that was possible to obtain bruxite through the results of chemical-physical characterization and the initial results in vitro indicate that it is a biocompatible nanoceramic. 

Thanks to Faperj 203.409/2023 - SEl-260003/016585/2023 for supporting the research, to CAPES, CNPQ and to the student Ronald Palandi Cardoso for helping with the cultivation of microorganisms and to Prof. Yutao Xing for helping with the MET analysis.

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.

The golden mussel, Limnoperna fortunei (Dunker, 1857), an invasive species that arrived in South America in the 1990s, has caused significant impacts on Brazilian aquatic ecosystems [1]. The objective of this study was to investigate the potential of the herbicide glyphosate as a tool to control populations of golden mussels, whose proliferation results in environmental and economic damage. Two experiments were conducted to evaluate the toxic effects of glyphosate on golden mussels, revealing a direct correlation between the concentration of the herbicide and the mortality of the organisms [2]. Proliferation occurs at high population density, reaching populations of 150,000 specimens per square meter in natural environments and up to 240,000 specimens/m² in structures built by man [3]. Statistical analysis strengthened these observations, indicating significant differences in results. Furthermore, the feasibility of using glyphosate to contain fouling of golden mussels was discussed and the possibility of using these molluscs as a laboratory study model was explored. Importantly, the use of ultrasound to dislodge and eliminate golden mussels proved to be efficient and may represent an alternative to control the invasion of L. fortunei in your research [4]. Despite increasing information on biology, dispersal and control methods, studies on mussel behavior are still scarce in Brazil [5]. The findings highlight the importance of considering environmentally sustainable approaches to dealing with the spread of golden mussels, while highlighting the potential of glyphosate as a control option.

The use of cellulose nanofibers and post-use coffee capsules for composites is a sustainable option to minimize environmental impacts, reduce waste generated, and add value to the materials [1]. Applying these composites as adsorbent material is a promising solution to guarantee a circular economy aimed at sustainability, making it possible to integrate the environmental problems caused by plastic and forestry waste with the remediation of areas affected by oil spills [2]. In obtaining cellulose nanofibers, the bark fibers and chips were pre-treated with an alkaline solution to remove amorphous components such as lignin and hemicellulose and subjected to the steam explosion process for defibrillation [3,4]. Polymeric composites were obtained with a coffee capsule matrix reinforced with 5, 10, and 20% (m/m) of bark and chips. These composites were used to obtain test specimens and were subjected to tests to evaluate the oil adsorption capacity. The thermal analysis results (TG/DTG and DSC) showed that the alkaline treatment followed by steam explosion increased the thermal stability of the fibers present in the Eucalyptus bark and decreased the stability of the chip flakes. The micrographs showed better adhesion of cellulose nanofibers from the bark and chip chips to the polymer matrix than cellulose microfibers. The BET/ BJH results showed that the bark has a larger surface area and larger pore volume but a smaller pore size, which may influence adsorption. Alkaline and steam explosion treatments increased the crystallinity of all samples. Specimens obtained from composites reinforced with 20% m/m of exploded showed the best adsorption efficiency, representing an unprecedented and encouraging result.

SAE 5160 steel has applicability in several industrial branches due to its good tensile and fatigue resistance, as well as having good tenacity, high hardenability and ductility. However, in the case of a steel that has carbon contents between 0.65 and 0.64%, it becomes very hard and abrasive, wearing out the tool very quickly. In addition, it has relatively low levels of chromium, manganese, silicon, and other elements, alone or in combination. This naturally results in a steel that is more difficult to machine than common carbon steels ⁽¹⁾. 

Machining is a complex process that requires a significant level of preparation and experimentation, as it involves numerous variables. Thus, it is almost impossible to accurately predict the behavior of metals when they are machined ⁽²⁾. It is of great importance to try to minimize this unpredictability as much as possible, which is mainly since it is a plastic deformation process where the restriction is given by the cutting tool and by the variety of options of input parameters in the process. Some of these input parameters are characteristics of the material to be machined, coolant, machine used to perform the machining, cutting tool, machining speed, feed rate and more ⁽²⁾.

The knowledge acquired through experimentation is beneficial for several reasons, including increased operational safety, cost reduction, assertiveness of results and reduced time spent on finishing.

Some research available in the literature ^(3-5) has indicated the need to study the cutting parameters as well as to evaluate the behavior of tool wear, to outline strategies to facilitate the machining process. Herein, for the first time, this study is carried out for SAE 5160 steel.

In this work, the cutting parameters influences in the turning of a SAE 5160 steel bar were analyzed, using two different cutting tools starting from the parameters indicated by the manufacturers and adapting them to the best machining conditions, aiming at greater use of the cutting tools, evaluating the results and impacts on operational risk as well as material properties. At the end, find a working range where the industry can perform rough machining in an economical, efficient and safe way.

Commonly metals, ceramics, and polymers have been widely used in the manufacturing of armor components. However, due to the growing demand for components that provide comparable ballistic impact resistance with a significant reduction in weight, laminated composite structures have emerged as key substitutes. These composites have found significant application in the construction of components for bulletproof vests, ballistic panels, and military vehicle protection [1]. The mechanical performance of structural composites is strongly dependent on the volumetric fraction of their constituents and the presence of defects, such as voids, resulting from the manufacturing process. Optimal properties are generally achieved when the laminated composite structure has a high reinforcement volume fraction and a low void content. However, when addressing composites intended for ballistic applications, voids might not be detrimental. Indeed, in high-speed impact scenarios, a wave is generated and travels through the material. This wave induces stresses in the material, potentially resulting in
strain, as well as partial or complete perforation of the target. Voids generated during the molding process do not necessarily have a detrimental effect [2]. On the contrary, they have the ability to induce a change in the wave medium, altering the stress imposed on the material. Therefore, manufacturing techniques that are simpler and economically viable, tending to generate composites with a higher void volume, may prove efficient for the production of ballistic components. In the present work, composite plates made of aramid fiber and impregnated with epoxy resin were produced using the vacuum-assisted resin transfer molding and compression molding techniques. Subsequently, a residual velocity test was conducted by firing a .45 caliber projectile using a pressure rifle. Preliminary results revealed that although there was no statistically significant difference in the absorbed energy value between the samples, and no sample was completely perforated, there was a clear distinction in the fracture mode. The sample produced by compression molding exhibited a much greater indentation compared to that manufactured by infusion, which, in turn, dissipated the shot's energy through total layer delamination. This suggests that, in terms of application in bulletproof vests, the infusion-manufactured sample showed superior performance, as it would result in less trauma for the user [3].

Commonly metals, ceramics, and polymers have been widely used in the manufacturing of armor components. However, due to the growing demand for components that provide comparable ballistic impact resistance with a significant reduction in weight, laminated composite structures have emerged as key substitutes. These composites have found significant application in the construction of components for bulletproof vests, ballistic panels, and military vehicle protection [1]. The mechanical performance of structural composites is strongly dependent on the volumetric fraction of their constituents and the presence of defects, such as voids, resulting from the manufacturing process. Optimal properties are generally achieved when the laminated composite structure has a high reinforcement volume fraction and a low void content. However, when addressing composites intended for ballistic applications, voids might not be detrimental. Indeed, in high-speed impact scenarios, a wave is generated and travels through the material. This wave induces stresses in the material, potentially resulting in strain, as well as partial or complete perforation of the target. Voids generated during the molding process do not necessarily have a detrimental effect [2]. On the contrary, they have the ability to induce a change in the wave medium, altering the stress imposed on the material. Therefore, manufacturing techniques that are simpler and economically viable, tending to generate composites with a higher void volume, may prove efficient for the production of ballistic components. In the present work, composite plates made of aramid fiber and impregnated with epoxy resin were produced using the vacuum-assisted resin transfer molding and compression molding techniques. Subsequently, a residual velocity test was conducted by firing a .45 caliber projectile using a pressure rifle. Preliminary results revealed that although there was no statistically significant difference in the absorbed energy value between the samples, and no sample was completely perforated, there was a clear distinction in the fracture mode. The sample produced by compression molding exhibited a much greater indentation compared to that manufactured by infusion, which, in turn, dissipated the shot's energy through total layer delamination. This suggests that, in terms of application in bulletproof vests, the infusion-manufactured sample showed superior performance, as it would result in less trauma for the user [3].

Natural fibers have been widely studied and used in polymeric biocomposites, aiming to enhance their mechanical and thermal properties. These fibers stand out for their relatively low cost and sustainable characteristics. However, when used as reinforcement, they present adhesion issues to polymer matrices due to their hydrophilic nature, contrasting with hydrophobic matrices. Surface treatments are a feasible solution to enhance this interaction. In this study, the effectiveness of three surface treatments applied to coffee husk fiber waste (CHFW) was evaluated to enhance the performance of green polyurethane (GPU) biocomposites based on castor oil. The analyzed treatments were: i) chemical with sodium hydroxide (NaOH) solutions, ii) hydrothermal under high temperatures and pressures (HYD), and iii) biological with solid-state fermentation by the fungus Phanerochaete chrysosporium (BIO. For evaluation, biocomposites were fabricated with 20% by weight of CHFW (in natura and with each of the proposed treatments: NaOH, HYD, and BIO). The tensile strength of the biocomposites was analyzed based on ASTM D3039 [2], the water absorption, and morphology through scanning electron microscopy. A superior increase of over 60% in tensile strength was observed in biocomposites reinforced with CHFW-HYD, compared to in natura CHFW, with achieved strength of 16.3 MPa. Surface treatments on lignocellulosic fibers or particles contribute to enhancing the interface between particles and the matrix, thus increasing mechanical properties. There were no significant modifications in the water absorption of the biocomposites. Scanning electron microscopy analyses showed an improvement in the interface between GPU and CHFW-HID compared to other treatments. Based on the results, it can be concluded that the HIDRO treatment was the only one resulting in increases in tensile strength. SEM images confirmed better adhesion of polyurethane to lignocellulosic particles, which is related to the reduction of extractive compounds on the surface of the coffee husk.

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.

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 research examined the simulated transmission factor of depleted uranium dioxide for gamma radiation shielding. Depleted uranium dioxide, a dense and mildly radioactive material mainly consisting of uranium-238, finds extensive use in military contexts, notably in armor-piercing munitions[1-2]. However, it also serves civilian purposes like radiation shielding in medical settings, counterweights in aerospace and naval vessels, radiation protection in shielding, and stabilizers in construction[3]. The investigation validated its efficacy in shielding gamma radiation emitted by cesium-137 and cobalt-60 isotopes[4]. The increase in transmission factor for cobalt-60 is not linear, a phenomenon attributed to the manner in which gamma radiation interacts with matter at energies of 1.17 and 1.33 MeV. As gamma ray or electromagnetic radiation energy escalates, its penetrative capacity intensifies. Moreover, the interaction of radiation with matter, particularly the formation of pairs emitting positrons of annihilation, contributes to the heightened transmission factor observed for cobalt-60 energies[5]. With the consideration of the obtained transmission factor results of 11.01% for cesium-137 and 65.56% for cobalt-60, it is apparent that depleted uranium dioxide demonstrates efficacy in shielding against gamma radiation across various energy spectrums[6]. Its exceptional density and inherent radiation absorption capabilities render it indispensable in environments necessitating robust radiation protection measures, such as nuclear facilities, research laboratories, radioactive material storage locales, and space missions. However, prudence mandates a comprehensive evaluation of potential health and environmental risks associated with depleted uranium dioxide utilization[7-8]. The possibility of radioactive particle release underscores the imperative for meticulous safety protocols and rigorous risk assessment frameworks. Consequently, while depleted uranium dioxide stands as a viable option for gamma radiation shielding applications, strategic deployment strategies and stringent safety measures remain pivotal considerations in maximizing its benefits while mitigating associated risks.

The quest for enhanced materials in the nuclear industry is escalating alongside the surge in energy demand. This drive has led to the exploration of novel materials aimed at optimizing nuclear applications[1-2]. Among these, niobium has long been scrutinized as an alloying agent due to its advantageous attributes, including low thermal neutron absorption and robustness under the extreme conditions prevailing within nuclear reactors. A pivotal aspect of reactor operation revolves around comprehending the behavior of fuel rods during the fission process of UO2 pellets and, by extension, the dynamics of heat transfer therein. To delve into these critical parameters, a study delved into the crucial matter of a fuel rod sheathed in niobium-doped Zircaloy, employing MCNP code simulations. These simulations encompassed a variety of enrichment levels (3.2%, 2.5%, and 1.9% UO2) based on a hypothetical PWR reactor model[3]. The investigation focused on assessing the criticality of fuel rods encased in Zircaloy-4 doped with niobium nanoparticles. MCNP5 code facilitated the simulations, modeling a fuel element comprising 25 rods housing UO2 pellets across three enrichment zones[4-5]. The fuel element's height stood at 3.6 meters. Utilizing the kcode method, the criticality of the simulated fuel was evaluated. A total of 10,000 neutrons per cycle were employed over 100 cycles, half of which were passive. The analysis yielded an effective multiplication factor (keff) of 1.380303 ± 0.0007 for the coated rod, compared to 1.39207 ± 0.00072 for the reference undoped rod, reflecting a relative deviation of approximately |δ| ≈ 0.84%. Notably, doping Zircaloy with niobium nanoparticles showcased no substantial influence on neutron production, preserving the alloy's energy production efficiency.  This observation underscores the potential for enhancing Zircaloy's properties through niobium nanoparticle doping without compromising energy production efficiency [6-8]. The marginal relative deviation in keff values between doped and undoped rods suggests minimal impact on criticality. Hence, niobium nanoparticle doping emerges as a promising avenue for refining alloy properties while maintaining energy production efficiency. Nonetheless, further research is warranted to validate these findings and delve deeper into the advantages of niobium doping.

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 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.

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 comparative study aimed to explore the thermal neutron transmission factor utilizing the Watt spectrum for uranium-235 fission[1-3]. In the course of the analysis, a noteworthy observation emerged, revealing that borated polyethylene exhibited a notably lower efficiency compared to regular polyethylene counterparts[4-5]. This disparity implies that while boron offers advantageous moderating properties, its incorporation may introduce other characteristics that detract from its efficacy in facilitating thermal neutron transmission[6]. This outcome underscores the critical necessity of evaluating not solely the moderating capabilities of materials but also other intrinsic traits that might impact the behavior of thermal neutrons. Specifically, boron-polyethylene (referred to as E-boron) displayed a marginally elevated transmission factor at 79.48% in contrast to common polyethylene (PE) at 78.68%. This finding suggests that the presumed homogeneity of boron-polyethylene, containing an approximate 1% boron-10 concentration, failed to exert any discernible effect on neutron flux attenuation[7]. Such a phenomenon could potentially stem from the material's inherent incapacity to maintain its uniformity in the solid state. Despite the considerable neutron-absorbing capacity conferred by carbon within the polymer, the post-reaction homogeneity of the material surprisingly facilitated radiation passage. These observations necessitate a deeper exploration into the intricate interplay between material composition, structural integrity, and neutron transmission efficiency. Furthermore, they underscore the need for a comprehensive understanding of the multifaceted factors influencing the behavior of thermal neutrons within varying material matrices. This study not only sheds light on the complexities surrounding boron-enhanced polyethylene but also underscores the broader importance of considering diverse material characteristics in the design and optimization of neutron-modulating materials for nuclear applications.

The search for synthetic materials with bioactive, osteoconductive, and biocompatible characteristics is becoming highly desirable for various biomedical applications. Hydroxyapatite (HA), a biomaterial, is an inorganic ceramic that closely resembles the mineral apatite, primarily found in human bones and teeth. Its characteristics, such as biocompatibility, cell adhesion, bioactivity, and degradation, are fundamental for potential applications as a biomaterial, particularly in bone regeneration [1][2]. Thus, this study aims to synthesize and characterize hydroxyapatite using the precipitation technique by the wet method, with the use of acid/base reagents. In order to analyze the chemical elements and microstructure of the obtained material, techniques such as X-Ray Diffraction (XRD), Rietveld Refinement, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS) were employed. The XRD results showed peaks of hydroxyapatite and calcium oxide. The FTIR analysis revealed vibration bands of carbonates (CO₃^2-) and phosphates (PO₄^3-), characteristic of the material. SEM indicated irregular morphologies with different shapes and forms. Additionally, EDS analysis showed the presence of calcium, phosphorus, and oxygen, and through this result, the Ca/P molar ratio was determined to be 1.60. The characterizations indicated the presence of B-type carbonated hydroxyapatite, suggesting a nanometric form with good crystallinity and density. Furthermore, it is suggested that the hydroxyapatite obtained in this study has great potential to be applied as a biomaterial.

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.

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%.

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.

Composites with natural lignocellulosic fibers (NLFs) currently have extremely diverse applications, including in engineering industries, due to their lower cost and density, as well as ease of processing. Another notable material, graphene oxide, has attracted considerable attention for its properties, mainly as a coating to improve interfacial adhesion in polymer composites. Therefore, this research focuses on investigating the dynamic mechanical (DMA) and thermomechanical analysis (TMA) for epoxy matrix composites containing 30% by volume of CM sedge fiber incorporated with graphene oxide. Compared to the control group (untreated epoxy) the damping factor (Tan δ), being the ratio of the loss modulus under storage, is significantly increased from (0.55-0.75) for the composites reinforced with 30% of CM sedge fibers incorporated with graphene oxide. The Tg found at 127°C for condition 30 FJGO/EP was higher than the other EP conditions, 30 FJ/EP and 30 SF/EP-GO, as well as the coefficient of thermal expansion (208.52 to 248.95 x 10−6/°C). The mass loss for the 30 SFGO/EP condition in the first stage was slightly higher than the EP condition (1.63%). These DMA and TMA results prove to be promising.

Currently, all over the world, intensive development of new materials is being carried out for the development of industry. Of particular note are materials containing metal borides. In our case, Hf and Sc borides, which have a unique set of physicochemical properties: high melting point, mechanical strength, thermal stability and exceptional wear resistance, corrosion and oxidation. These unique properties make them ideal for high temperature applications in key areas, such as the aerospace industry, nuclear power, the automotive industry and the latest electronic devices, and also as a component of light heat-resistant alloys.

In most cases, the production of composite and nanostructured materials is carried out as a result of various oxide reduction reactions and therefore the study of processes of this type is one of the main tasks.

The purpose of this work was to conduct a thermodynamic analysis of the formation of Hf and Sc borides, and based on this analysis, to conduct experiments on the manufacture of nanostructured composite materials in the future.

A thermodynamic analysis of the Sc-Hf-B-O-C system at high temperatures in vacuum was performed for the following reactions: 1. Sc₂O₃+HfO₂+3B₂O₃+14C=2ScB₂+HfB₂+14CO;

2. Sc₂O₃+HfO₂+6H₃BO₃+23C=2ScB₂+HfB₂+9H2+23CO.

Information about the FTA of the system in question has not been found in the available literature. Therefore, it is of great interest to carry out the FTA of these reactions. The calculations were carried out using the ASTRA-4 program [3] in the temperature range of 1000-3000 K with a step of 200⁰ in vacuum.

When studying the equilibrium of a reaction, knowledge of the properties and accurate, reliable thermodynamic data of the components and compounds involved in the system is necessary. However, data on some thermodynamic characteristics of these borides (H⁰₂₉₈-H⁰₀, ∆H_mel, C_p, C_p(liq))  are not observed in reference books.In this regard, we calculated the values of these thermody-namic characteristics of the indicated borides, the calculation methods for which were developed in [1] and entered into the ASTRA-4 program database.

The main results of FTA are presented in the form of diagrams (dependence of the content of components on temperature in the range of 1000-3000 K).

Thus, it can be concluded that the method of complete thermodynamic analysis used by us makes it possible to judge not only the equilibrium conditions of the processes occurring in the system, but also the mechanism of interaction of components in complex systems and, consequently, adjust the composition of the final product, and it is also possible to minimize the number of experiments.

This study aims to evaluate the performance characteristics of polymer composite materials composed of light-curing acrylic resin utilized in additive manufacturing through the AM method via vat polymerization employing a DLP process, alongside flax fibers, using dynamic mechanical analysis (DMA). DMA measures the viscoelastic properties of a material in terms of stiffness and damping, including storage modulus (E'), loss modulus (E"), and the ratio between these moduli, tangent δ, as well as the glass transition temperature (Tg). The samples were printed to dimensions of 65x12x3.5 mm and in fractions of 0%, 0.5%, 1%, 1.5%, and 2% flax fiber. After printing, they underwent exposure to UV light (405 nm) for 12 hours. Subsequently, the specimens were subjected to dynamic mechanical analysis, which revealed an increase in initial E' between the 0% and 2% samples to 2041 MPa and 2083 MPa, respectively. The loss modulus (E") showed values of 214 MPa at 45° and 176 MPa at 58°, while Tg recorded values of 80°C and 88°C. In comparison to other composites, a reduction of up to 59% was observed in the storage modulus (E'), alongside a significant decrease in the loss modulus peak (E"). The composites exhibited more pronounced peaks in the tan δ graph compared to the pure resin. Notably, the composite with a 2% mass fraction demonstrated an 8°C increase in the glass transition temperature (Tg) when contrasted with the pure resin. The remaining composites maintained a glass transition temperature within the range of 72°C to 76°C.