List of Abstracts

Self-assembled networks of nanoparticles have emerged as important candidate systems for brain-like (or neuromorphic) information processing. The essence of the approach is to take advantage of the intrinsic dynamical properties of these networks to implement brain-inspired approaches to computation.

Our percolating networks of nanoparticles (PNNs) are self-assembled via simple deposition processes that are completely CMOS compatible, making them attractive for integration. The key to our approach is to terminate the deposition at the onset of conduction (the percolation threshold) when the electrical properties of the network are dominated by tunnel gaps between groups of particles. At high voltages the memristive tunnel gaps turn out to have neuron-like properties, which means that PNNs can be viewed as networks of neurons.

Both the structural and dynamical properties of PNNs have been shown to be brain-like and, in particular, avalanches of neuron-like spiking events have been shown to be critical.¹ Criticality is a key feature of the biological brain that has been related to optimal information processing capability. We have explored brain-like computation with PNNs in two regimes, beginning with simulations that allow us to understand the processes and refine parameters, and then moving to experimental demonstrations^2.3. At low voltages, the devices are amenable to reservoir computation and we have successfully demonstrated time series prediction, non-linear transformation and spoken digit recognition.² In the high voltage regime, the spiking behaviour of the ‘neurons’ has been exploited to perform Boolean logic and MNIST classification_, and, most recently, optimization tasks such as integer factorisation³. 

Here will present results of new experiments and supporting simulations that demonstrate simultaneous neuron-like and synapse-like behaviour, which is achieved by incorporating molecular “synapses” into networks of metal nanoparticles. Both synaptic strengths and neuron spike rates are controlled by previous inputs to the system and so these new hybrid materials systems facilitate new kinds of learning behaviour and new opportunities for spike-based computation.

Carbon quantum dots (CQDs) are nanomaterials with sizes smaller than 10 nm; these dimensions are essential for enhancing their fluorescence and optical properties. In addition, they exhibit good water solubility, surface functional groups, and high biocompatibility, which contribute to their application in the biomedical field. Different synthesis methods, such as top-down and bottom-up approaches, enable the production of CQDs with tunable properties; however, controlling size, structure, and optical properties remains a challenge, potentially leading to variations in particle size, fluorescence intensity, and optical stability. Thus, a better understanding of these characteristics is essential to expand their use in bioimaging, sensors, and the development of new functional materials [1]. Despite the advantages of CQDs, many of these materials are still synthesized from fossil-based precursors, raising concerns about sustainability and environmental impact. In this context, the use of biomass has gained prominence as a viable alternative, enabling the synthesis of nanomaterials from renewable, low-cost, and abundant sources. Furthermore, biomass-derived materials may contain numerous functional groups, which contribute to the formation of CQDs with tunable properties and potential applications across various fields [2]. Among various biomass sources, onion peel stands out as an abundant agro-industrial waste product that can serve as a precursor for CQD synthesis, exhibiting stable fluorescence and potential applications in cellular bioimaging and wound healing, as demonstrated in the literature [3]. Thus, this research was conducted to produce CQDs from onion peel via a green, heat-treatment-based route for biomedical applications. Then, different heating times and temperatures were used to produce these CQDs. Moreover, characterizations of the nanoparticles were performed, including FTIR, RAMAN, PL, TEM, UV-Vis, Zeta Potential, DLS, XRD, XPS, and SEM. The carbon dots had an approximate size of 3 nm, blue photoluminescence, and a negative charge. Furthermore, the CQDs exhibited strong photoluminescence, demonstrating a low-cost, environmentally friendly chemical route. These findings hold promise for improved diverse biomedical applications.

Marine biofouling is a major challenge for naval and industrial sectors, leading to increased fuel consumption, corrosion processes, and maintenance costs[1-2]. Conventional antifouling coatings commonly employ toxic biocides, which may cause significant environmental impacts in aquatic ecosystems [3-4]. In this context, the development of sustainable alternatives based on natural compounds has gained increasing attention. This work investigates the potential application of bioactive compounds extracted from Camellia sinensis in the development of environmentally friendly antifouling coatings. Green tea is recognized as a rich source of phenolic compounds, especially catechins, which present antioxidant and antimicrobial properties that may contribute to the reduction of biofilm formation and marine bioincrustation. The study involves the extraction of natural compounds using different extraction approaches, followed by their incorporation into polymeric coating systems. Physicochemical, spectroscopic, and performance analyses are being conducted to evaluate the influence of the natural extract on coating properties and its potential antifouling behavior. Preliminary results indicate promising interactions between the bioactive extract and the polymeric matrix, highlighting the feasibility of developing sustainable coatings for marine applications. The proposed approach contributes to the advancement of green technologies aimed at reducing the environmental impact associated with traditional antifouling systems, while promoting the use of renewable natural resources in advanced material development[5].

Vat photopolymerization technologies, particularly Stereolithography (SLA), have gained significant attention due to their ability to manufacture components with high resolution, excellent surface finish, and complex geometries [1]. However, dimensional instability caused by polymerization shrinkage and warpage remains one of the primary challenges affecting the accuracy and reliability of printed parts [2]. The incorporation of natural fibers into photopolymer resins has emerged as a promising strategy to reduce dimensional changes while promoting the development of more sustainable composite materials [3]

This study aims to evaluate the effect of coconut fiber incorporation on the dimensional stability, warpage behavior, and geometric accuracy of SLA photopolymer resins. The objective is to investigate the influence of different fiber contents on dimensional deviation and shrinkage characteristics, identifying the formulation that provides the best balance between dimensional accuracy and processability.

The methodology consisted of preparing SLA resin composites containing different concentrations of coconut fiber, followed by specimen fabrication through stereolithography. Dimensional measurements were performed after printing and post-curing to evaluate geometric accuracy, dimensional deviation, warpage, and shrinkage behavior in the X, Y, and Z directions. The performance of the reinforced formulations was compared with that of the neat resin to determine the effect of fiber incorporation on dimensional stability.

The results demonstrated that the incorporation of coconut fiber significantly improved the dimensional stability of the SLA resin. The neat resin exhibited the highest dimensional deviation and warpage values, while the addition of coconut fiber reduced both parameters. The formulation containing 1.0 wt.% coconut fiber presented the lowest dimensional deviation and warpage values, resulting in the highest geometric accuracy among all evaluated groups. Directional shrinkage was observed in all formulations, with the greatest contraction occurring along the Z-axis, which is characteristic of the layer-by-layer photopolymerization process. The addition of coconut fiber reduced shrinkage in all evaluated directions up to the concentration of 1.0 wt.%. Above this concentration, a slight increase in dimensional deviation, warpage, and shrinkage was observed, that excessive fiber incorporation may interfere with resin homogeneity and light propagation during curing.

It can be concluded that coconut fiber is an effective natural reinforcement for improving the dimensional stability and geometric accuracy of SLA photopolymer resins. The formulation containing 1.0 wt.% coconut fiber demonstrated the best overall performance, exhibiting the lowest dimensional deviation, warpage, and shrinkage values. These findings indicate that agricultural waste-derived fibers can contribute not only to the development of more sustainable photopolymer composites but also to the production of additively manufactured components with enhanced dimensional precision and structural reliability [4–5].

The creation of a mesoporous system is important to promote carbon dioxide capture through mineralization. It is through these pores, which partially contain water, that, after gas permeation, the active sites can convert carbon dioxide into carbonate phases [1]. This is only possible by controlling the distribution of the number and size of the pores. Thus, an alternative material, called alkali-activated material, can act as a physicochemical adsorption substrate; in this way, fixation can occur within it, with the interaction between carbon dioxide and residual NaOH from the in-situ formation of the substrate. To promote porosity, hydrogen peroxide and a fixed content of nano-TiO₂ were applied. This work explores the synergistic effect between them evaluating its effect on pore size, their stability during the reaction and modifications on oscillation rheology measurement. New, smaller pores were recorded and may be partially associated with the formation of peroxo species on the surface of nano-TiO₂, which could regulate oxygen release and promote heterogeneous nucleation during geopolymer setting.

This study investigated the effects of incorporating tungsten trioxide (WO₃) nanoparticles into an epoxy resin matrix, focusing on the optical, thermomechanical, and viscoelastic properties of the composite. Samples of pure epoxy resin and epoxy resin functionalized with 0.3 wt% WO₃ were produced and characterized by dynamic mechanical analysis (DMA), UV-vis spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). DMA results showed a reduction in storage modulus and loss modulus for the composite, as well as an increase in glass transition temperature and a decrease in the tan δ peak, indicating restricted molecular mobility of the polymer chains and possible nanoparticle agglomeration. UV-Vis analyses revealed increased transmittance and reflectance in the visible region, associated with the semiconducting properties of WO₃ and changes in the optical interactions within the matrix. SEM analyses demonstrated a relatively homogeneous particle distribution with the presence of small agglomerates, while EDS confirmed the incorporation of tungsten into the epoxy matrix. Therefore, it was concluded that the addition of low concentrations of WO₃ significantly modifies the functional properties of epoxy resin, with particle dispersion being a determining factor in the composite performance.

Understanding how three-dimensional fibrous architectures govern electrical percolation remains a key challenge in conductive polymer composites. This study investigated the interplay between structure, percolation, and charge transport in polymethyl methacrylate (PMMA) microfibers functionalized with reduced graphene oxide (rGO) and fabricated via solution blow spinning (SBS) [1]. 

PMMA/ reduced graphene oxide (rGO) microfiber mat was produced with rGO loadings of 0.5, 1, and 2 wt% and characterized using scanning electron microscopy, micro-computed tomography (micro-CT), X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and four-point-probe electrical measurements [2,3]. The  resulting mats exhibit highly porous, interconnected networks, with increasing junction density and enhanced inter-fiber contact as rGO content rises. Micro-CT provided direct three-dimensional evidence of continuous conductive pathways within the fibrous scaffold. Electrical measurements reveal a sharp increase in conductivity from 0.00156 S/m (0.5 wt%) to 0.00986 S/m at 2 wt%, indicating the onset of the percolation threshold, likely governed by tunneling and contact resistance between adjacent fibers [4]. These findings demonstrate that percolation is controlled primarily by fiber architecture and spatial filler distribution rather than filler content alone [5]. This study provides new insights into structure–property relationships in SBS-processed systems and establishes PMMA/rGO microfibers as lightweight materials with tunable electrical behavior for applications in flexible electronics, sensing, and filtration systems.

Green synthesis of ceramic nanoparticles has emerged as a sustainable alternative to conventional nanomaterial production methods. This work aimed to synthesize aluminum oxide (Al₂O₃) nanoparticles via the sol-gel method using Cocos nucifera water as the reaction medium and as a natural auxiliary agent in particle formation. The process consisted of preparing the sol from an aluminum precursor, followed by drying and calcination steps. Scanning electron microscopy (SEM) micrographs of the xerogel revealed the amorphous nature of the material before calcination. X-ray diffraction (XRD) analyses of the calcined samples indicated the formation of structures compatible with ceramic oxides, showing peaks associated with the γ-alumina phase at nanometric dimensions. The results also suggested that increasing the calcination temperature favored progressive crystallization and structural development of the synthesized nanoparticles, with potential use in catalysis, adsorption processes, ceramic coatings, sensors, and as a potential strategy for advanced materials and sustainable nanotechnology applications in scientific and technological fields.

Carbon dots (CDs) prepared through green synthesis using natural materials show special properties that make them useful for many applications. In this study, hill galgal juice was used as a natural precursor to synthesize carbon dots through a simple and low-cost one-step hydrothermal method. The structure and optical properties of the prepared sample were studied using different techniques such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, UV–Vis spectroscopy, and photoluminescence analysis. The synthesized carbon dots showed a larger interlayer spacing of about 4.02 Å and a wide bandgap of around 3.2 eV, mainly due to oxygen-containing functional groups present on their surface. Under ultraviolet (UV) light, the carbon dots displayed strong bluish-green fluorescence with high photoluminescence intensity. A UV sensor was also developed using these carbon dots, which showed a sensing response of 9% at room temperature without requiring any complicated fabrication steps. In addition, the quantum yield of the prepared carbon dots was measured to be 22%.

The increasing demand for sustainable materials in high-performance applications has led to the development of natural fiber–reinforced polymer composites as alternatives to conventional synthetic systems [1,3]. Among these, ramie fiber–based composites have attracted attention due to their high strength, low density, and renewable origin [1]. However, their mechanical reliability and impact resistance can be enhanced through the incorporation of ceramic fillers, such as silicon carbide (SiC), which improve stress transfer and energy dissipation mechanisms [4].

This study investigates the effect of SiC particle size (micrometric and nanometric) and content on the impact and ballistic performance of epoxy composites reinforced with ramie fabric. The primary objective is to evaluate how filler size and concentration influence energy absorption, mechanical reliability, and failure mechanisms in hybrid composite systems, aiming to identify optimal configurations for protective applications.

Hybrid composites were fabricated using a hand lay-up process followed by compression molding, incorporating 30 vol% ramie fabric and 0–15 vol% SiC particles. Mechanical performance was evaluated using Izod impact testing, while ballistic resistance was assessed through absorbed energy and limit velocity measurements using .45 caliber projectiles. Statistical analysis was conducted using ANOVA and Tukey’s test to verify the significance of performance differences. Microstructural and failure mechanisms were examined by scanning electron microscopy to correlate mechanical behavior with particle dispersion and interfacial adhesion.

The results demonstrate that SiC addition significantly influences both impact and ballistic performance. Composites reinforced with micrometric SiC exhibited more consistent and reliable improvements, with the 15 vol% micrometric SiC formulation showing the highest impact strength (~110 J/m) due to enhanced stress transfer and crack deflection. In contrast, nanometric SiC at high contents led to increased absorbed ballistic energy (315 J) but introduced greater variability due to particle agglomeration and processing-induced heterogeneities, a phenomenon commonly reported for nanoparticle-filled polymer composites [5]. Moderate filler content, particularly 5 vol% micrometric SiC, provided the best balance between mechanical performance and reproducibility. Fractographic analysis confirmed that failure mechanisms are governed by fiber pull-out, matrix cracking, and void formation, with filler dispersion playing a critical role in controlling variability [5].

In conclusion, while nanometric SiC can maximize peak ballistic performance, micrometric SiC offers superior reliability and processing robustness. The optimal design of ramie fiber hybrid composites requires a balance between filler content, particle size, and microstructural uniformity to ensure consistent performance in impact and ballistic applications. These findings reinforce the potential of natural-fiber composites for protective structures [3] and highlight the importance of SiC reinforcement strategies for improving energy absorption and ballistic efficiency [2,4].

The capture of space debris is a challenging technological problem of great importance because, among many factors, it poses a threat to satellites and spacecraft. The potential of using  gecko-inspired reversible pillared structures developed for static applications is explored for the first time, by establishing their dynamic response following impact. The simulated debris was dropped in free fall at different velocities.  The subsequent gripping behavior exerted by the microscale pillared structure was characterized by adhesion measurements and by monitoring the deceleration  with a high-speed  camera. We varied parameters such as drop height, simulated debris mass, microscale pillared structure parameters, and backing layer. A range of relative velocities was identified that maximizes the resulting adhesive strength for a given pillared structure and backing material. The results suggest optimization strategies for pillared structure devices and backing materials under dynamic conditions and demonstrate the feasibility of using these adhesives for capturing moving objects, such as satellite debris in outer space.

Graphene-based nanocomposites have emerged as transformative materials for next-generation structural systems, offering an unprecedented balance of mechanical robustness, thermal stability, and multifunctionality. This potential arises from the unique two-dimensional architecture and extraordinary intrinsic properties of graphene and its derivatives, including high Young’s modulus, exceptional electrical and thermal conductivity, and impermeability to gases [1]. These attributes have inspired the development of graphene-based polymer nanocomposites tailored for applications ranging from aerospace and energy storage to protective coatings and innovative structures. Within this class, graphene nanoplatelets (GNPs) stand out as cost-effective and processable nanofillers that can substantially enhance the stiffness, toughness, and thermal stability of thermoset matrices, such as epoxy resins, even at very low concentrations [2]. Recent investigations have confirmed that GNP incorporation, typically in the range of 0.1–0.5 wt.%, produces synergistic improvements in tensile, compressive, and thermal responses due to crack deflection, constrained polymer chain mobility, and efficient load transfer across the filler–matrix interface [3]. This work employs a three-factor, three-level Box–Behnken Design (BBD) to investigate the combined effect of GNP content (0.5–3.5 wt.%), hardener concentration (9–17 phr), and post-curing temperature (30–120 °C) on DGEBA/TETA epoxy nanocomposites. Mechanical performance by flexural testing associated with microstructural characterization by SEM and TEM established structural-property correlation. The optimized formulation (2.0 wt.% GNP, 9 phr hardener, and 120 °C post-curing) exhibited superior reinforcement, with flexural strength of 322.0 ± 12.8 MPa, flexural modulus of 9.7 ± 0.5 GPa, and strain at break of 4.4 ± 0.2%, corresponding to increases of 197%, 155%, and 91% compared with neat epoxy. These results surpass those of GO- and CNT-based systems, demonstrating the superior efficiency of GNPs under optimized conditions. The proposed approach provides a robust pathway for developing epoxy nanocomposites with low filler content and enhanced multifunctional performance.

Lightweight composite materials, particularly those with fiber-reinforced polymer matrices, align well with current demands for combining low density with high mechanical strength. This has driven numerous studies focused on incorporating lignocellulosic natural fibers (NLFs) into polymeric matrices. In this context, the present study proposes the use of graphene oxide (GO) coating sedge fibers (Cyperus malaccensis) as reinforcement in an epoxy matrix composite. The mechanical performance was evaluated through Izod and Charpy impact tests. Morphological analysis of the fractured surfaces was performed to assess  the influence of fiber treatment on failure mechanisms, in  particular  delamination. This failure  mechanism provides evidence of a weak interfacial  adhesion  and is commonly present in composites reinforced by  natural  fibers. The results revealed asignificant improvement in impact resistance due to the GO coating. For example, the treated fiber group showed the highest impact energies, with values of 117.68 ± 30.71 J/m (Izod) and 154.12 ± 33.77 J/m (Charpy). SEM micrographs indicated a substantial reduction in interfacial delamination, suggesting enhanced fiber–matrix adhesion. 

The increasing demand for sustainable and high-performance materials has accelerated the development of natural fiber–reinforced polymer composites for structural and protective applications [1–3]. Among these, natural lignocellulosic fiber (NLF)-based composites offer advantages such as low density, renewability, and reduced environmental impact; however, their broader application is hindered by intrinsic variability, moisture sensitivity, and limited mechanical reliability [2,3]. To address these challenges, hybrid composite systems incorporating secondary ceramic fillers, particularly silicon carbide (SiC), have emerged as a promising solution to enhance both mechanical strength and impact resistance [4].

This study investigates the influence of silicon carbide (SiC) particle size (micrometric versus nanometric) and volume fraction on the mechanical behavior, reliability, and ballistic performance of epoxy composites reinforced with ramie fabric. The primary objective is to determine the optimal filler configuration that balances strength, ductility, and reliability for advanced engineering applications. Particular emphasis is placed on understanding how filler scale and dispersion affect tensile properties and resistance to high-velocity impact.

Hybrid laminates were fabricated using a hand lay-up and compression molding process, incorporating 30 vol% ramie fabric and varying SiC contents (1–15 vol%) in both micro- and nano-sized forms. Mechanical characterization was performed via tensile testing following standardized procedures, while ballistic performance was assessed using V₅₀ limit velocity tests with 7.62 mm projectiles. To ensure robustness in interpreting experimental variability, a comprehensive statistical framework combining parametric (ANOVA), non-parametric (Kruskal–Wallis), and reliability-based (Weibull) analyses was employed. Microstructural evaluation through scanning electron microscopy supported the interpretation of failure mechanisms.

Results indicate that SiC incorporation generally enhances tensile strength and ballistic limit velocity; however, excessive filler loading promotes embrittlement, increased variability, and reduced ductility due to particle agglomeration and stress concentration effects. Composites reinforced with nano-SiC consistently outperformed their micro-SiC counterparts in terms of strength and efficiency of stress transfer, in agreement with the superior reinforcing efficiency commonly reported for nanometric ceramic fillers [4]. Notably, the formulation containing 1 vol% nano-SiC (RN1) exhibited the best overall performance, achieving a balanced combination of mechanical strength, deformation capacity, and reliability. This configuration demonstrated an approximately 13% improvement in ballistic limit velocity relative to the unfilled composite, while maintaining lower variability and stable post-impact behavior.

The study concludes that optimal composite performance is governed not by maximizing filler content, but by achieving a microstructural balance that ensures efficient load transfer and controlled energy dissipation. Low-load nanoparticle reinforcement emerges as the most effective strategy for enhancing both mechanical reliability and ballistic resistance in sustainable composite systems. These findings corroborate the growing interest in natural fiber-reinforced composites for lightweight ballistic protection systems and advanced structural applications [5].

Epoxy resins are widely used as structural and functional matrices in advanced engineering applications due to their excellent adhesion, chemical resistance, and mechanical performance [1]. However, their curing behavior strongly influences final properties, processing windows, and long-term reliability. Recent studies have shown that the incorporation of ceramic fillers can significantly alter epoxy cure kinetics [2–4], yet the specific role of filler particle size remains insufficiently understood, particularly for silicon carbide (SiC), a ceramic known for its thermal stability and high surface reactivity [5].

The purpose of this work is to investigate how SiC particle size—micrometric versus nanometric—affects the cure kinetics of a diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured with triethylenetetramine (TETA). The primary goal is to clarify the competing catalytic and retarding effects induced by particle size and loading, thereby providing guidance for optimizing processing conditions in SiC–epoxy composite systems.

Epoxy formulations containing micro- and nano-sized SiC particles at controlled volume fractions were prepared through mechanical dispersion followed by sonication. The SiC powders were comprehensively characterized in terms of morphology, structure, and thermal stability using transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Cure kinetics were evaluated under non-isothermal conditions using differential scanning calorimetry, and kinetic parameters were determined through isoconversional approaches, enabling assessment of activation energy evolution throughout the curing process.

The results demonstrate that both SiC particle sizes influence the epoxy curing reaction, but in markedly different ways. At low filler contents, both micro- and nano-SiC reduce the apparent activation energy, indicating a catalytic effect during the early stages of cure compared with the control group (at 5 vol%, micro = 16.5% and nano = 18.9%), consistent with previous observations for particulate-filled epoxy systems [3,4]. However, as filler content increases, particle size becomes decisive: nanometric SiC maintains efficient curing behavior, whereas micrometric SiC leads to an increase in activation energy and a retardation of the later curing stages (at 10 vol%, micro = 43.5% higher Ea). These effects are attributed to differences in interfacial area, particle morphology, and mobility constraints imposed by the fillers [2–4]. Overall, nano-SiC exhibits a stronger and more consistent influence on cure kinetics, promoting earlier epoxy ring opening while avoiding severe diffusion limitations at higher loadings.

In conclusion, this study shows that SiC particle size is a critical parameter governing epoxy cure kinetics. Nanometric SiC enables finer control of the curing process and enhances thermal stability without significantly hindering network formation, whereas micrometric SiC is more suitable at low concentrations. These findings provide a fundamental basis for tailoring curing schedules and filler selection in high-performance epoxy–SiC composites and reinforce the importance of particle-size engineering in advanced ceramic-filled polymer systems [3–5].

The growing demand for sustainable construction materials has driven research into the use of agro-industrial waste as reinforcement in polymer composites. In this context, spent coffee grounds have emerged as a promising particulate filler for epoxy matrices due to their renewable nature, widespread availability, and low cost [1,2].

This study aims to compile evidence from the literature supporting the applicability of natural particulates in polymer composites, with an emphasis on a preliminary assessment of their mechanical feasibility in relation to the requirements of ABNT NBR 14050:1998. The objective is to identify the normative prerequisites for High-Performance Flooring Systems (HPFS) and to evaluate, based on previously published experimental data, whether coffee-ground-reinforced composites present sufficient technical potential to justify future experimental investigations [3].

The methodology consists of a literature review and comparative analysis between mechanical properties reported by different authors and the minimum requirements established by ABNT NBR 14050:1998 for monolithic High-Performance Flooring Systems (Types 1 and 2), namely flexural strength ≥ 20 MPa, compressive strength ≥ 40–45 MPa, and tensile strength ≥ 6.5–8.5 MPa [3].

The findings are promising. Nguyen and Nguyen [4] reported that epoxy composites containing 30 wt.% NaOH-treated coffee grounds achieved flexural, compressive, and tensile strengths of 80 MPa, 110 MPa, and 45 MPa, respectively [4]. Even without surface treatment, the composites exhibited values of 60 MPa, 90 MPa, and 35 MPa, respectively, remaining well above the normative thresholds. Cobuci et al. (2025) reported a compressive strength of 47.35 MPa for composites containing 20 wt.% coffee grounds, approaching the minimum requirement for Type 2 flooring systems [5]. These results suggest that alkaline treatment with NaOH is the most effective approach, promoting impurity removal, increasing surface roughness, and enhancing interfacial adhesion, thereby improving load transfer efficiency. However, this assessment remains preliminary. Properties such as abrasion resistance, water absorption, and impact resistance, which are also required by the standard, have not yet been systematically evaluated for these composites. Consequently, definitive conclusions regarding their compliance as High-Performance Flooring Systems cannot yet be established.

It can be concluded that the mechanical performance reported in the available literature justifies further experimental investigation of coffee-ground-reinforced polymer composites. The use of spent coffee grounds as a reinforcing phase is consistent with the principles of the Brazilian National Solid Waste Policy and the circular economy, representing a sustainable and technically motivated alternative for future research in the field of high-performance flooring and protective coating systems [3].

The contemporary theater of asymmetric military conflicts has been profoundly redefined by the proliferation of high-precision multi-spectral detection arrays, including third-generation Forward-Looking Infrared (FLIR) sensors, thermographic cameras operating in atmospheric windows, and tactical Lidar target-tracking systems [1]. Ground combat platforms, such as armored vehicles and strategic military equipment, present distinctively prominent thermal and radiative signatures due to high-temperature transient gradients  generated by internal combustion engines, exhaust pipes, and intense solar radiative heating over metallic armors [1, 2]. Conventional camouflage coatings fail to mitigate these vulnerabilities, as their high thermal emissivity efficiently dissipates thermal energy, producing unmistakable infrared signatures even under nocturnal or low-visibility tactical operations [2]. While state-of-the-art lithographic metamaterials and vacuum-deposited multi-layered dielectric films offer excellent optical seletivity, their translation to real combat scenarios is severely hindered by low cost-effectiveness, geometric angular vulnerability, and chemical instability under severe field weathering, mechanical abrasion, or corrosive chemical contact [3].

To overcome these operational limitations, this work addresses a passive engineering alternative based on the development and validation of functional composite liquid coatings embedded with electromagnetically active particulate additives. The primary objective is to implement a strict multi-criteria screening protocol to screen and select synthesized or processed micro- and nanostructured powders that fulfill three mandatory engineering thresholds: (i) possessing a reliable and reproducible lab-scale synthesis path; (ii) displaying suitable rheological properties for homogeneous dispersion into commercial polymeric paint vehicles; and (iii) exhibiting specific optical bandwidth interaction focused on significantly lowering thermal emissivity in the mid-wave bands, coupled with high absorption characteristics against tactical military laser wavelengths.

The proposed methodology evaluates prospective ceramic candidate formulations, with special emphasis on complex oxide families such as stable spinel-type cubic ferrites (MFe2O4), processed via Solution Combustion Synthesis (SCS)—a self-sustained redox reaction driven by metallic nitrates and organic fuel. The raw powders and cured coating films undergo systematic crystalline and structural validation through X-ray Diffraction (XRD) with Rietveld refinement, Scanning Electron Microscopy (SEM/EDS), Transmission Electron Microscopy (TEM), and Vibrating Sample Magnetometer (VSM).

The tactical performance is evaluated via Fourier-Transform Infrared Spectroscopy (FTIR) coupled with MCT detectors to calculate selective directional emissivity via Kirchhoff’s Law, alongside UV-Vis-NIR spectrophotometry. Thermal transport behavior and the suppression of the radiative contrast are validated under real-time thermographic camera tracking on power-gradient heating setups and radiative cooling verification inside specialized low-pressure vacuum chambers. Lastly, standard mechanical film tests (cross-cut adhesion, impact, and conical mandrel flexibility) combined with accelerated salt spray corrosion chambers are deployed to qualify the physical durability of the coating. The structured engineering framework aims to yield a scalable, low-cost, and easily deployable functional coating, providing a robust tactical alternative to flatten emission curves and enhance the battlefield survivability of modern armored platforms.

The contamination of global water resources by highly persistent emerging contaminants, particularly per- and polyfluoroalkyl substances (PFAS), has become one of the most pressing environmental and public health challenges of the past few decades. Conventional remediation technologies, such as granular activated carbon and reverse osmosis, frequently suffer from early saturation, low retention efficiency for short-chain fluorinated pollutants, high energy demands, and the generation of secondary toxic brines. In response, nanocellulose (NC) has emerged as a transformative, nature-based nanomaterial for sustainable water purification. Derived from diverse lignocellulosic biomass or bacterial synthesis, NC encompasses distinct classes, Cellulose Nanofibrils (CNF), Cellulose Nanocrystals (CNC), and Bacterial Nanocellulose (BNC), each offering unique morphological and physicochemical properties. The fundamental advantage of nanocellulose lies in its high specific surface area, inherent mechanical rigidity, and an abundance of surface hydroxyl groups. These groups serve as highly accessible sites for diverse chemical functionalization strategies, including 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, phosphorylation, amination, and carboxymethylation. Such modifications allow for the precise tuning of surface charge density, hydrophilicity, and the introduction of specific chelating or reactive moieties. Consequently, functionalized nanocellulose can interact with complex waterborne pollutants through a versatile array of mechanisms, including electrostatic attraction, ion exchange, hydrogen bonding, and coordination complexation. This chemical versatility enables NC to be engineered into multiple high-performance architectures. In its dispersed state, highly charged NC acts as an exceptional natural coagulant and flocculant. When assembled into highly porous three-dimensional networks, such as hydrogels and aerogels, NC exhibits rapid adsorption kinetics and massive uptake capacities for heavy metals and organic dyes. Furthermore, the robust fibrillar scaffolding of NC facilitates the uniform nucleation and immobilization of inorganic nanoparticles, creating advanced hybrid photocatalysts capable of degrading recalcitrant organic compounds without suffering from severe agglomeration or photocorrosion. In the advanced filtration, NC is increasingly utilized to fabricate self-standing nanopapers, mixed-matrix membranes, and Thin Film Nanofibrous Composites (TFNC). These sophisticated membrane designs offer exceptional water permeability and high selectivity, while the inherent hydrophilicity of the cellulosic network provides strong resistance to biofouling and organic scaling. The ability of nanocellulose-based systems to simultaneously target and remove multiple complex pollutants, often matching or exceeding the capacities of traditional petroleum-based or inorganic materials, positions it at the forefront of next-generation water treatment. Ongoing research into optimizing extraction routes, understanding the thermodynamics of pollutant-cellulose binding, and scaling up the production of these nanomaterials will undoubtedly expand the environmental engineer's armamentarium to manage severe water contamination scenarios while adhering to the principles of a circular economy. This work will present the fundamental physicochemical properties of nanocellulose, the evolution of its surface functionalization strategies to target emerging contaminants, the design of advanced NC-based adsorption and membrane filtration systems, and a critical analysis of current limitations and research gaps is also provided.

Potassium ferrite was synthesized by the sol-gel auto-combustion method followed by calcination at 750 °C for 2 h, based on previously reported combustion-assisted routes for the formation of KFeO₂ and related potassium ferrite phases [1–3]. The obtained powder was characterized by X-ray diffraction (XRD), Rietveld refinement, and Mössbauer spectroscopy to investigate the crystalline phases formed and the local chemical environment of iron. The XRD results indicated the formation of crystalline phases associated with the K–Fe–O system, attributed to potassium ferrite, together with secondary iron oxide phases. Rietveld refinement confirmed the coexistence of potassium ferrite and iron oxides, allowing phase identification, structural evaluation, and estimation of the relative phase fractions. Mössbauer spectroscopy indicated the predominance of Fe³⁺ species distributed in hyperfine environments compatible with ferrite-type structures and iron oxide phases. The combined results suggest that the sol-gel auto-combustion route followed by calcination at 750 °C for 2 h was effective in promoting the formation of potassium ferrite; however, the presence of secondary iron oxides indicates that further optimization of the synthesis parameters is required to improve phase purity and structural homogeneity.

Potassium ferrite was synthesized by the sol-gel auto-combustion method followed by calcination at 750 °C for 2 h, based on previously reported combustion-assisted routes for the formation of KFeO₂ and related potassium ferrite phases [1–3]. The obtained powder was characterized by X-ray diffraction (XRD), Rietveld refinement, and Mössbauer spectroscopy to investigate the crystalline phases formed and the local chemical environment of iron. The XRD results indicated the formation of crystalline phases associated with the K–Fe–O system, attributed to potassium ferrite, together with secondary iron oxide phases. Rietveld refinement confirmed the coexistence of potassium ferrite and iron oxides, allowing phase identification, structural evaluation, and estimation of the relative phase fractions. Mössbauer spectroscopy indicated the predominance of Fe³⁺ species distributed in hyperfine environments compatible with ferrite-type structures and iron oxide phases. The combined results suggest that the sol-gel auto-combustion route followed by calcination at 750 °C for 2 h was effective in promoting the formation of potassium ferrite; however, the presence of secondary iron oxides indicates that further optimization of the synthesis parameters is required to improve phase purity and structural homogeneity.