Magnetic iron oxide nanoparticles (Fe3O4) functionalized with anacardic acid (AAc), producing Fe3O4@AAc nanoparticles, were synthesized via chemical coprecipitation to improve the performance of biolubricants. The nanoparticles were characterized in terms of their structure, morphology, thermal properties, and magnetism. They exhibited a spherical morphology with an average diameter of 14.7 +/- 4.2 nm, demonstrated good thermal stability, and contained approximately 12.4 wt % surface-bound AAc. Superparamagnetic behavior was preserved for the functionalized nanoparticles. To evaluate their effectiveness as performance-enhancing additives, Fe3O4@AAc nanoparticles were incorporated into a trimethylolpropane trioleate (TMPTO)-based biolubricant at concentrations of 0.05 and 0.15 wt %. Adding 0.05 wt % improved thermal resistance, and adding 0.15 wt % enhanced rheological stability, reducing both the coefficient of friction (COF) and wear. The nanoparticles lowered the activation energy for viscous flow and maintained Newtonian behavior up to 80 degrees C at 0.15 wt %. Tribological tests indicated that the 0.15 wt % formulation exhibited the lowest COF (0.036), a reduced wear scar diameter (WSD) (0.342 mm), and formation of a more stable protective tribofilm compared to pure biolubricant and reference mineral oil. These results confirm that anacardic acid functionalization promotes effective nanoparticle dispersion, with the magnetic nanoparticles acting as efficient additives that improve the thermal and tribological performance of the biolubricant.

Magnetic hyperthermia relies on the conversion of magnetic energy into heat by nanoparticles exposed to alternating magnetic fields, with specific loss power (SLP) being the key metric for heating efficiency. However, SLP can be evaluated at different levels of physical description, either from microscopic magnetic energy dissipation models or from macroscopic thermal analyses of calorimetric measurements, often without a clear distinction between their respective domains of validity. Here, we experimentally investigate how microscopic magnetic energy dissipation described by Linear Response Theory (LRT) and the macroscopic thermal response obtained from calorimetric energy-balance modeling provide complementary frameworks for interpreting SLP in superparamagnetic nanoparticle systems. By combining structural, morphological, magnetic, and magnetothermal characterizations, we determine parameters governing energy dissipation and evaluate the applicability of the LRT formalism under controlled small-field conditions. LRT predictions are directly compared with SLP values extracted from calorimetric heating curves analyzed using progressively more physically complete thermal energy-balance descriptions, from the adiabatic approximation to nonadiabatic regimes including conductive, convective, and radiative heat losses. We show that LRT calculations and calorimetric analyses reproduce consistent qualitative trends in heating efficiency, whereas quantitative differences arise from the distinct physical quantities represented by each framework. LRT describes microscopic magnetic energy dissipation under small-field conditions in terms of magnetic parameters that characterize the nanoparticle ensemble, whereas calorimetric energy-balance models capture the macroscopic thermal response of the nanoparticle suspension under realistic experimental conditions. Estimates of Neel and Brownian relaxation times indicate that relaxation is dominated by the Neel mechanism in the investigated systems with proximity to dynamic matching conditions governing relative heating efficiencies. As a consequence, the extracted SLP depends not only on magnetic relaxation processes but also on the level of physical completeness adopted in the thermal energy-balance description. These results demonstrate that LRT and calorimetric approaches should not be regarded as competing methods but as complementary levels of description of magnetic hyperthermia, providing experimental guidance for the consistent interpretation, comparison, and reporting of SLP values in magnetic nanoparticle systems.

The proton exchange membrane electrolysis cell (PEMEC) is a practical approach for sustainable hydrogen production. To date, several studies have aimed to improve hydrogen production efficiency. This work examined the impact of electrolyte type and ultrasonics on hydrogen generation under static mode using a PEMEC. Therefore, the effects of three electrolytes (water, sulfuric acid, and phosphoric acid) were studied. The influence of electrolysis time, voltage, electrolyte concentration, and current intensity was optimized. Using the optimized parameters, the sono-electrochemical process under indirect sonolysis was explored to improve the enhancement of hydrogen production efficiency. The results showed that electrolysis time and voltage significantly affect hydrogen generation in the PEMEC. Hydrogen production was highest with sulfuric acid at a concentration of 0.15 M, and a more concentrated solution negatively affected the mass transfer. Ultrasonic-assisted electrochemistry also helped reduce electrolysis time from 30 to 10 min while increasing hydrogen efficiency. When using sulfuric acid 0.15 M, low electrolysis time (10 min), a current intensity of 55.0 mA, and a potential of 1.9 V, the maximum hydrogen efficiency was 92.9%. On the other hand, these parameters combined with the ultrasound effect allow reaching the maximum hydrogen efficiency of 99.9% at only 10 min of electrolysis. At the same time, the energy efficiency under sono-electrolysis was increased from 24.2% to 32.8%. Our findings highlight the potential of the sono-electrochemical process with PEMEC as a promising, efficient, and low-time method for green hydrogen production compared to traditional hydrogen production methods.

Magnetic iron oxide nanoparticles (Fe3O4) functionalized with anacardic acid (AAc), producing Fe3O4@AAc nanoparticles, were synthesized via chemical coprecipitation to improve the performance of biolubricants. The nanoparticles were characterized in terms of their structure, morphology, thermal properties, and magnetism. They exhibited a spherical morphology with an average diameter of 14.7 ± 4.2 nm, demonstrated good thermal stability, and contained approximately 12.4 wt % surface-bound AAc. Superparamagnetic behavior was preserved for the functionalized nanoparticles. To evaluate their effectiveness as performance-enhancing additives, Fe3O4@AAc nanoparticles were incorporated into a trimethylolpropane trioleate (TMPTO)-based biolubricant at concentrations of 0.05 and 0.15 wt %. Adding 0.05 wt % improved thermal resistance, and adding 0.15 wt % enhanced rheological stability, reducing both the coefficient of friction (COF) and wear. The nanoparticles lowered the activation energy for viscous flow and maintained Newtonian behavior up to 80 °C at 0.15 wt %. Tribological tests indicated that the 0.15 wt % formulation exhibited the lowest COF (0.036), a reduced wear scar diameter (WSD) (0.342 mm), and formation of a more stable protective tribofilm compared to pure biolubricant and reference mineral oil. These results confirm that anacardic acid functionalization promotes effective nanoparticle dispersion, with the magnetic nanoparticles acting as efficient additives that improve the thermal and tribological performance of the biolubricant.

This work explored a TiNb2O7/NiFe heterostructure prepared by integrating the tape-casting and magnetron sputtering techniques. Using various experimental setups, the TiNb2O7 layer was systematically characterized from the structural, morphological, electrical, and dielectric perspectives. The TiNb2O7 sheets were submitted to polishing processes to improve the surface's quality for future anode integration applications. This surface improvement was tested through the deposition of Ni81Fe19 thin films. For this purpose, electric and magnetic properties were also investigated for the heterostructures. The employed process induces a decrease of around 80 % in the surface roughness, yielding a reduction of around 90 % in the electric resistance. The electric resistance decreases from 4.38 kc2 for the TiNb2O7/NiFe heterostructure with a low level of polishing to around 0.27 kc2 with the highest level of polishing sheet. Similar results were observed for the magnetic properties, in which a drastic decrease of the coercive and saturation fields was observed as the polishing process was realized. While the coercive field for the TiNb2O7/NiFe heterostructure with a low level of polishing was around 13 Oe, for the highest level of polishing sheet, this value decreased to around 4 Oe. The findings demonstrate a promissory route to integrate TiNb2O7 sheets to ferromagnetic layers for future technological battery applications.

Current therapies for colorectal cancer (CRC) are often limited by drug resistance, systemic toxicity, and tumor recurrence. To address these challenges, a multifunctional nanosystem for enhanced drug delivery was developed. The system is composed of cashew gum nanoparticles (CGNPs) coloaded with oxaliplatin (OXA) and retinoic acid (RA), combined with magnetic core-shell nanoparticles (CSNPs). Following synthesis and characterization, in vitro assays in CT-26 cells showed efficient nanoparticle internalization and significant dose-dependent viability reduction, with magnetic stimulation increasing late apoptosis. In vivo studies using a murine CRC model revealed enhanced tumor necrosis, reduced anaplastic cell frequency, suppressed COX-2 expression, and altered oxidative stress markers, such as SOD and GPX-1. Although tumor volume did not differ significantly between groups, histological and molecular analyses confirmed substantial antitumor effects, particularly with RA-functionalized formulations. The data suggest magnetic stimulation improved nanoparticle uptake, while RA acted as both a cytotoxic agent and a modulator of cellular uptake and inflammation. Overall, the nanosystem promoted apoptosis, tumor necrosis, and biochemical modulation. These findings lay a promising foundation for future research to investigate the nanosystem's biodistribution, pharmacokinetics, and synergistic effects with immunotherapeutic agents.

This study reports the use of graphene-decorated boron nitride (GBN) as an efficient adsorbent for azo dyes, with the aim of treating textile wastewater. GBN was synthesized by a facile route and characterized by XRD, SEM/EDS, TGA-DTA, and BET analyses, revealing a microporous and crystalline structure. Methyl orange (MO) was adopted as a model dye, and batch adsorption experiments were optimized by using response surface methodology (RSM) with pH, adsorbent mass, and initial MO concentration as variables. Results showed that the pH and adsorbent mass were the main factors influencing MO removal. Under optimal conditions (pH 2, 0.062 g of adsorbent, 100 mg/L MO), GBN reached a high adsorption capacity of 322.5 mg/g in 20 min and retained good performance after 10 reuse cycles. The synergistic properties of graphene and boron nitride make GBN a promising material for efficient textile wastewater treatment.

The present work aimed to optimize the preparation of activated carbons (ACs) from two main precursors, used in our city (chicken bone, CB and cashew nut shells, CNS). The ACs were prepared according to the chemical and physical activation. A central composite design based on the response surface methodology was employed to determine the optimal conditions for producing activated carbons. The results showed that for the production of optimized materials, the operating conditions were a carbonization temperature of 800 ^∘ C and 690 ^∘ C an activation time of 30 and 49 min, for CB and CNS, respectively, and a NaOH concentration of 60

The challenge of utilizing green energy sources remains relevant nowadays, especially in developing new catalysts for hydrogen production through complete water decomposition. For this purpose, an electrocatalyst based on an Fe-Ni alloy supported by graphene was synthesized. The catalyst was prepared by using the sol-gel technique. Physicochemical characterization showed that the main crystalline phase was the FeNi alloy with an equimolar ratio. EDS showed that the elements were well distributed on the graphene matrix. Analyzing the structural properties of the catalysts revealed that the GFeNi 1:1.0 catalyst, which has the smallest average crystalline size and lowest lattice strain, exhibited superior catalytic activity due to its high density of exposed active sites. This promotes excellent mass and charge transport during oxygen evolution reaction kinetics. Consequently, the catalysts demonstrated an overpotential of 0.268 V vs RHE at 10 mA/cm2 and maintained good stability in an alkaline 1 M KOH medium. The GFeNi 1:1.0 electrocatalyst showed electrochemical efficiency comparable to that of recently reported catalysts in the literature. These findings advance our understanding of ferromagnetic alloy-based materials for electrolysis applications and other electrochemical devices and highlight the potential of graphene-supported systems synthesized by sol-gel routes as cost-effective alternatives to noble metals.

The asymmetrical magnetoimpedance effect has a great appeal for sensor application due to the possibility of tuning a linear response near zero magnetic field. Usually, for a given thin film geometry, this response is obtained considering two distinct ferromagnetic materials separated by a non-ferromagnetic metal. Here a new route to obtain the asymmetrical magnetoimpedance response considering just one ferromagnetic material is presented. More specifically, Ni81Fe19 (Py)/Ag multilayer where the modification of the ferromagnetic properties of the successive Py layers is responsible for the biphasic behavior. These modifications lead to quasi-static magnetization curves with plateaus, which are reflected in the magnetization dynamics as the asymmetrical magnetoimpedance response. To support the presented findings, structural and morphological characterization is considered. The strong linearity at a low magnetic field range allowed to reach the sensitivity of 38 m Omega/Oe for a frequency of 2.06 GHz. The results simplify the experimental procedure to produce sensor elements with tunable linearity response.

In this work, the influence of Sn content on the formation and identification of phases present in Cu50Mn25Al25-ySny alloys was investigated. The predicted phases were analyzed using tools based on the CALPHAD method, which allowed the selection of four compositions for experimental synthesis. The alloys produced were characterized according to their structural, mechanical, electrical, thermodynamic and magnetic properties. The results indicate that the equilibrium phases predicted by the simulations were observed experimentally, although with different percentages from those simulated. It was also found that increasing the Sn content reduces the peak melting temperature, in agreement with the behavior predicted in the simulation, increases the microhardness values, decreases the electrical conductivity and the electronic component of the thermal conductivity, in addition to reducing the coercivity and the saturation and remanent magnetizations. Our results indicate that the modification of the structural, mechanical, thermal, electrical and magnetic properties of the alloy Cu50Mn25Al25-ySny is strongly influenced by the Sn content, thus indicating a way to adjust the properties according to the application.

Impact of partial substitution of Sn by Cu on the mechanical, electrical, and magnetic properties of Ni44Mn44Sn12 Heusler alloys was analyzed in this study. The alloys Ni44Mn44Sn12, Ni44Mn44Sn10.5Cu1.5, and Ni44Mn44Sn9Cu3 were produced through casting without atmosphere control and characterized using microscopy scanning electron microscopy, X-ray diffraction, Vickers microhardness tests, electrical resistivity measurements, and vibrating sample magnetometry. The results showed that the partial substitution of Sn with Cu did not affect the solidification microstructure or the phases present at room temperature. However, this substitution increased the transition temperatures from austenite to martensite and from martensite to austenite, increasing the proportion of the martensitic phase from 56.04 to 77.67

This study presents the experimental development of a simple and low-cost system for measuring the thermomagnetic energy conversion based on the Anomalous Nernst Effect. The approach aims to provide an easy-to-implement alternative for teaching modern physics phenomena, such as the Anomalous Nernst Effect (ANE) and Longitudinal Spin-Seebeck Effect (LSSE), highlighting its educational potential and applicability in high school and higher education settings. The proposed system is validated through experimental measurements performed on specific samples, using advanced characterization techniques. The results demonstrate the system’s effectiveness, making experimentation accessible and relevant for students’ formation in physics, nanotechnology, and sustainable energy fields.

The present study focused on optimizing the biosorbent production through chemical modification of natural coconut fibers (NCFs) using a biorefinery process combined with nanoparticle impregnation and its adsorptive performance for removing Rhodamine B (Rh-B) and methylene blue. NCF was chemically modified via the formosolv process using formic acid (85

The ferroelectric topological crystalline insulator SnTe is a promising material for ferronics and spintronics studies and applications because of the strong spin-orbit coupling and surface states protected by the mirror symmetry of the crystal. In this paper, we report ferromagnetic resonance-driven spin-pumping experiments in several bilayers and trilayers having one layer of SnTe with thickness varying in the range 3-30 nm and different ferromagnetic layers used to inject the spin-pumped spin current. In all samples x-ray-diffraction spectra strongly indicate that the SnTe films grown are topological crystalline insulators and consequently have preserved topological surface states. The spin-pumping studies reveal that the dominant spin to charge conversion mechanism in SnTe is the inverse Rashba-Edelstein effect (IREE), evidencing that the topological surface states are preserved. From the data in all samples, we obtain for the IREE parameter values in the range 1.1-2.8 pm, which are comparable to the ones measured in graphene, Bi2Se3, 2 Se 3 , and others topological insulators.

Aqui abordamos o efeito Magnetoimpedância e demonstramos que este pode nos auxiliar no estudo da dinâmica da magnetização em sistemas nanoestruturados. Especificamente, exploramos uma forma acessível, mas robusta, de calcular o fenômeno da Magnetoimpedância em sistemas na forma de filmes finos. Para verificar a robustez de nossa abordagem teórica, produzimos um filme fino ferromagnético de Ni81Fe19, uma liga amplamente conhecida na comunidade de magnetismo, e realizamos sua caracterização magnética quase-estática e dinâmica. Nosso resultados, além de mostrar a concordância entre teoria e experimento, trazem uma forma simples para descrever sistema ferromagnéticos e suas interações com campos magnético estáticos e alternados, simultaneamente. Através da investigação das propriedades magnéticos de diferentes sistemas podemos produzir uma ampla gama de dispositivos sensores para diferentes aplicações tecnológicas.

The thermomagnetic coefficients play a pivotal role in converting heat to electricity in ferromagnetic systems. Specifically, the Anomalous Nernst Effect and Longitudinal Spin-Seebeck Effect show promise for energy conversion. However, traditionally, calculating thermomagnetic coefficients relies on a limited value of thermal gradient measurements due to experimental constraints. In this study, we introduce a novel experimental setup aimed at generating thermomagnetic curves with a significantly higher density of data points, enhancing the reliability of coefficient calculations. Our proposed setup enables the attainment of Delta T values of up to 40 K without the thermal annealing on the films, due to the highly efficient thermal dissipation.