Search Results (612)

MnCo₂O₄ and CoMn₂O₄ were successfully synthesized on a stainless-steel substrate using the hydrothermal method. The structural and morphological characteristics of the spinel samples were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electronic and vibrational properties were studied through X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Electrochemical properties were also evaluated using a three-electrode system associated with an electrochemical workstation. The studies revealed that the inversion of Mn and Co cation distribution between the spinel structure sites not only modifies the crystal structure and morphology but also alters specific functional properties. MnCo₂O₄ crystallized in a cubic spinel phase, exhibiting spherical particles, pronounced microstrain, and stronger metal–oxygen bonding. In contrast, CoMn₂O₄ adopted a tetragonal spinel structure with rod-like crystallites, lower microstrain, and more flexible bonding environments. Electrochemical impedance spectroscopy further revealed distinct charge-transfer dynamics, indicating differences in surface redox activity. This comparative analysis elucidates how cation site occupancy governs the performance of the synthesized spinel oxides and underscores their potential as efficient catalysts or catalyst supports for redox and energy-related applications. Full article

This work highlights the feasible fabrication of translucent ceramics from un-doped and Nd³⁺-doped BaLaLiWO₆ (BLLW) and BaLaNaWO₆ (BLNW) cubic tungstates using the Spark Plasma Sintering (SPS) method. Ceramics were sintered using pure-phase, homogeneous powders with submicron particle sizes, obtained via the solid-state reaction method. The present study investigated the microstructural, structural, and spectroscopic properties of both un-doped and Nd³⁺-doped sintered specimens. All the ceramic materials exhibited certain drawbacks that significantly contributed to their low transparency in both sample types. However, initial spectroscopic tests on sintered translucent ceramics doped with Nd³⁺ ions revealed promising properties, comparable to those of the powdered samples. Therefore, we believe that producing higher-quality ceramics would improve their spectroscopic properties. For that, further optimization of the manufacturing conditions is necessary. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) are commonly produced through wet-chemical methods that require high temperature and pressure and involve multiple synthesis steps. Our research group has developed an innovative, sustainable, and patented one-step aqueous synthesis operating at ambient temperature and pressure, enabling the direct production of SPIONs in suspension. In this work, we investigated the extension of this method to obtain polymer-coated SPIONs for biomedical imaging applications. Two water-soluble and biocompatible polymers—poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA)—were selected and prepared into twelve samples varying in polymer concentration and iron precursor molarity. Each formulation was characterized and compared to bare SPIONs synthesized with the same approach using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and alternating gradient magnetometry (AGM). The results confirm that the one-step method yields polymer-coated nanoparticles with a cubic spinel magnetite core. PEG produced spherical, monodisperse particles (10–30 nm) exhibiting superparamagnetic behavior but lower magnetization values (1–5 emu/g). In contrast, PVA-coated nanoparticles showed a morphology dependent on polymer concentration and reagent molarity, while maintaining an average size of ~10 nm and superparamagnetic behavior, with magnetization comparable to bare SPIONs (25–50 emu/g). A preliminary MRI evaluation of a selected PVA-coated sample revealed relaxivity values of r₁ = 0.12 mM⁻¹ s⁻¹ and r₂ = 6.44 mM⁻¹ s⁻¹, supporting the potential of this synthesis route for imaging-oriented nanomaterials. Full article

Axion warm inflation is studied within the framework of Logamediate inflation. Using a novel approach, we constrain the parameter space of the model and find a reasonable region of free parameters compatible with the temperature, polarization, and lensing CMB data. We focus on an inflaton evolution characterized by a high dissipative regime, where particle production impacts the inflaton dynamics more than the expansion rate. Specifically, we consider the cubic form of the dissipation coefficient, $\mathrm{{\rm Y}}={\mathrm{{\rm Y}}}_0{T}^3$, as proposed in minimal warm inflation. We show that this parameter remains large during the slow-roll epoch for a broad range of the free parameter ${\mathrm{{\rm Y}}}_0$, as indicated by our data analysis. Full article

Understanding the extent of cadmium (Cd) contamination and its impact on the food industry and ecosystems is crucial; to this end, electrochemical methods provide sensitive and rapid responses for the in situ detection of heavy metal ions. In this paper, a sensitive Cd²⁺ electrochemical sensor was constructed by using a composite material composed of biomass-derived porous carbon and manganese dioxide (MnO₂/KLSC). The composite was demonstrated to have a porous structure with quasi-cubic MnO₂ particles evenly distributed on the carbon matrix. Using MnO₂/KLSC as the electrode material, a simple electrochemical sensing platform was fabricated for the detection of Cd²⁺. The electrochemical analysis showed that the Cd²⁺ sensor has good performance, with a linear detection range of 0.01–80.0 μmol/L and a detection limit of 9.8 nmol/L. Furthermore, the sensor shows excellent repeatability, reproducibility, and good anti-interference. The sensor was successfully applied to analyze rice and sea water samples, demonstrating satisfactory recovery rates. The good performance of MnO₂/KLSC/GCE can be attributed to the excellent electrical conductivity, enlarged active surface area, and good electron transfer capability. Full article

Constituent phases and their corresponding phase transformations are important in developing alloys. This study investigates the phase transformations of a Cr₃₉Co₁₈Fe₁₈Ni₁₈Al₇ HEA after annealing at and quenching from 1100 °C, 1200 °C and 1300 °C. The as-quenched alloy exhibits major body-centered cubic (BCC) and minor face-centered cubic (FCC) structures. The volume fraction of the BCC phase progressively increases as the annealing temperature is elevated. Upon cooling, the occurrence of spinodal decomposition in the high-temperature BCC phase leads to the formation of two distinct disordered BCC phases, BCC1 and BCC2, at a high temperature regime. The BCC1 phase acts as the matrix and is lean in Ni and Al concentrations, while the BCC2 phase presents as fine particles and is enriched in Ni and Al. As the temperature decreases, sequential spinodal decompositions occur in both BCC phases, giving rise to other product BCC phases. Upon further cooling, the Ni–Al-enriched BCC phases undergo ordering reactions, transforming into B2 phases. Consequently, the major phases in the matrix and fine particles are BCC and B2, respectively. In addition, the BCC matrix and B2 fine particles also contain B2 and BCC nanoparticles, respectively. The co-clustering and ordering effects of Ni and Al participate in the phase transformations of the as-quenched HEA. Correspondingly, the hardness increases with annealing temperature, which is attributed to the higher BCC phase fraction and the increasing number density of ordered B2 precipitates that collectively strengthen the matrix by impeding dislocation motion. Full article

Cu-modified ferrites, prepared by solvothermal syntheses, at up to 200 °C, show the presence of copper metal particles, embedded in ferrite nanocrystalline particle agglomerates. Notably, these metallic copper micron-sized crystallites were dramatically reduced in size, down to a few tens of nanometers, when part of the copper dopant was replaced by zinc. All materials were magnetic due to the presence of the cubic spinel phase, being ferrimagnetic, measured with external fields up to 6000 Oe, showing a narrow hysteresis of 89 Oe for the largest particle size copper ferrite material of 15 nm. Superparamagnetic behavior was observed for the smallest size, e.g., 11 nm, Cu-doped and the zinc-doped, 9–10 nm average particle size ferrites. The redox activity of the materials was studied in free-radical oxidation reactions (pH 7.4, physiological and pH 8.5, optimal) by the chemiluminescent method with (i) Fenton’s reagent (^·OH, ^·OOH); (ii) H₂O₂; and (iii) O₂^·− radicals. All materials presented extremely strong inhibitory activities (converted to prooxidant only at pH 7.4 in system iii, excluding the largest isolated copper-particle-containing material, which remained inhibitory). The materials’ antimicrobial potential was checked on Gram-positive and Gram-negative bacteria, Escherichia coli ATCC 25922, and Staphylococcus aureus ATCC 25923 via two classical methods, namely the spot and well diffusion tests in agar medium. The above tests included a nanocrystalline CuO, tenorite, as a reference material too. The Daphnia magna ecotoxicity test showed that all of the investigated materials are rather toxic, and since daphnia is a key component in freshwater ecosystems, the toxicity even at low concentrations may have significant consequences for the ecological balance. This requires careful monitoring and assessment of the possible use or disposal of these nanomaterials in the environment. Full article

This study employed atmospheric plasma spraying (APS) technology to successfully fabricate CoCrFeNiMo high-entropy alloy (HEA) coatings under varying spraying currents and systematically investigated the effects of the spraying current on the microstructure, mechanical properties, and tribological behavior of the coatings. Results showed that the material composition remained consistent across different current levels, primarily consisting of face-centered cubic (FCC) solid solution phases, FeCr₂O₄ spinel phases, and Cr-rich FCC1 phases. The FCC matrix was dispersed with spherical Cr oxide particles smaller than 30 nm in diameter, which significantly enhanced the strength of the coatings. As spraying current increased, both porosity and microhardness exhibited a non-monotonic trend—initial optimization followed by deterioration. At 500 A spraying current, the coating achieved optimal performance, with the lowest porosity (0.42%) and highest microhardness (569.8 HV). Correspondingly, this condition also yielded the best wear resistance, with stable friction coefficients and wear rates reaching 0.49 and 6.91 × 10⁻⁵ mm³/N m, respectively. Abrasion surface analysis revealed that excessively low or high currents triggered distinct wear mechanisms leading to reduced wear resistance. Full article

Green synthesis methods of silver nanoparticles have gained great attention because they offer sustainable, eco-friendly, and less-toxic alternatives to traditional methods. This study sheds light on the green synthesis of chitosan silver nanoparticle composites, providing a comparative evaluation of microwave-assisted (M1) and a one-pot (M2) reduction methods. The morphological, crystallinity, and structural uniformity characteristics were evaluated by UV-Visible, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) with employing image processing pipeline based on deep learning model for segmentation and particles size estimation. The UV-visible spectrum exhibited independent SPR peaks ranging from 400 to 450 nm for all samples; however, microwave assisted-synthesis possessed narrower and more intense peaks indicative of better crystallinity and mono-dispersity. SEM depicted smaller, more uniformly dispersed particles for microwave-assisted (M1), while deep learning segmentation showed lower particle size variability (σ ≈ 24–43 nm), compared to polydisperse (σ ≈ 16–59 nm) in M2 samples. XRD showed crystalline face-centered cubic (FCC) silver with dominant peaks in M1 samples, whereas M2 had broader, less intense peaks with amorphous features. Raman vibrations revealed more structural order and homogenous capping in M1 than M2. Therefore, microwave-assisted (M1) showed better control on nucleation, particle size, crystallinity, and homogeneity due to a faster and uniform energy distribution. The future research would focus on the antimicrobial evaluation of such nanoparticles in agronomy. Full article

Sinomenine (SIN) is a promising candidate for the treatment of rheumatoid arthritis (RA). Although it possesses the advantage of being non-addictive, its poor aqueous solubility and low oral bioavailability have limited its clinical application. To address these issues, SIN was encapsulated into lipid cubic liquid crystal nanoparticles (LCNPs) and systematically characterized. Molecular dynamics (MD) simulations were first employed to screen suitable excipients for formulation development. Combined with single-factor optimization and Box–Behnken response surface design, the optimal composition and preparation process were determined. The resulting SIN-LCNPs exhibited a particle size of 149.7 ± 0.9 nm, a polydispersity index (PDI) of 0.223 ± 0.01, a zeta potential of −18.9 mV, and an encapsulation efficiency (EE%) of 92.2%. Spectroscopic analyses confirmed successful incorporation of SIN into the lipid matrix. Pharmacodynamic studies revealed that SIN-LCNPs enhanced targeted drug delivery to inflamed joints, significantly alleviating inflammation and suppressing disease progression in rats. In vivo single-pass intestinal perfusion (SPIP) experiments further demonstrated that SIN was primarily absorbed through the small intestine and that the LCNP carrier effectively improved its intestinal permeability. Collectively, this study provides a novel strategy and theoretical foundation for developing efficient formulations of poorly water-soluble drugs, highlighting the potential clinical application of SIN-LCNPs in RA therapy. Full article

The local segmental mobility of polymer chains in polydimethylsiloxane (PDMS) plays a critical role in determining the material’s behaviour. Incorporation of zeolite particles can modify these local dynamics, which is crucial as they affect the overall performance of the resulting composite material with potential for various industrial applications. The aim of this study was to investigate the influence of zeolite addition on the local dynamic behaviour of PDMS chain segments in PDMS–zeolite composites. To investigate the effect of zeolite morphology and loading on the segmental dynamics and phase behaviour of PDMS, Zeolite A (with cubic and spherical morphologies) and Zeolite X were incorporated into the PDMS matrix at 20, 30, and 40 wt%. The electron spin resonance (ESR)-spin probe method was used to study molecular dynamics, while the thermal behaviour was analysed using differential scanning calorimetry (DSC). ESR results revealed that the presence of zeolites increases the isothermal crystallisation rate affecting segmental mobility in the amorphous phase below the crystallisation temperature. This effect was found to depend more strongly on zeolite morphology than on filler content. DSC measurements showed no change in glass transition temperature with the addition of zeolite; however, shifts in cold crystallisation and melting behaviour were observed, indicating changes in crystal structure and its degree of perfection. These findings suggest that zeolites act as heterogeneous nucleation agents, with their structural properties playing a critical role in the crystallisation behaviour of PDMS. Full article

Packed granular materials absorb sound. In previous studies, granular materials sized a few millimeters and samples of grain size as a powder were studied; however, the grain sizes in between have not been addressed. In this study, the sound absorption coefficients of materials ranging from granular materials with a grain size d = 4 mm to powder materials with d = 0.05 mm were analyzed theoretically and experimentally. In addition, five packing types were studied: four types of regular packing and random packing. For these packing structures, the propagation constants and characteristic impedances were substituted within a one-dimensional transfer matrix for sound wave propagation, from which the normal-incidence sound absorption coefficient was calculated. Furthermore, our analysis accounted for particle longitudinal vibrations due to sound pressure. According to analyses of cross-sectional CT images considering tortuosity, the theoretical values for random packing tended to be close to the experimental values for d = 0.8 mm and smaller. For random packing structures with d = 0.3 mm or smaller, the experimental values were closer to the theoretical values for simple cubic lattice than the theoretical values for random packing. Full article

Garnet-type Li₇La₃Zr₂O₁₂ (LLZO) is a solid electrolyte candidate for ASSLBs, owing to its wide electrochemical window and intrinsic safety. Yet phase-pure LLZO remains difficult because secondary phases form, and the transition towards the tetragonal phase, aliovalent doping, mitigates these issues. Still, the phase formation pathway is not fully understood. Here, we present comparative in situ and ex situ studies of Nb- and Ta-doped LLZO (LLZNO and LLZTO) that were synthesized by a solid-state reaction. In situ/ex situ XRD reveals that the lithium precursor dictates the reaction path: differing decomposition temperatures of the lithium precursor define reaction windows that control cubic-phase purity and particle morphology. In air, limited Li diffusion favors oxycarbonates and pyrochlore, necessitating 950–1050 °C to achieve phase-pure cubic LLZO. Under N₂, faster Li availability and diffusion enable uniform nucleation and a route to cubic LLZO without detectable secondary phases. These findings demonstrate the coupled effects of temperature, precursor, dopant, and atmosphere, guiding process optimization and scalable production. Full article

This article reports on the synthesis and physicochemical characterization of a novel complex ferrite material, LiCr₃.₄Fe₁.₆O₈, prepared via the sol-gel method. X-ray diffraction (XRD) analysis confirmed that the synthesized compound is a single-phase material with a spinel-type structure and cubic symmetry. Raman spectroscopy was employed to investigate the vibrational modes, and the observed peaks corresponding to Fe–O and Cr–O bonds further validated the spinel-like structure of the compound. The microstructure and elemental composition were examined using scanning electron microscopy (SEM). Multiple regions of the LiCr₃.₄Fe₁.₆O₈ crystals were analyzed, revealing a homogeneous phase and providing detailed insight into the morphology and chemical composition of the surface. The synthesized ferrite particles exhibited relatively large dimensions, with sizes measured at approximately 5, 30, 100, and 200 μm. The dielectric behavior was studied to assess the material’s response to an external electric field, demonstrating its capacity for electric charge polarization. Both capacitance and electrical conductivity were found to increase with rising temperature. Electrophysical measurements were conducted using the LCR-800 system over a temperature range of 293–483 K and at frequencies of 1.5 kHz and 10 kHz. An increase in frequency to 10 kHz resulted in a decrease in the dielectric constant (ε) across the entire temperature range. Full article

La³⁺/Bi³⁺ co-doped BaTiO₃ ceramics were synthesized via ball milling followed by heat treatment at 1200 °C according to the Ba_1−3xLa_2xTi_1−3xBi_4xO₃ formula, with dopant levels ranging from x = 0.0 to 0.006. X-ray diffraction and Rietveld refinement confirmed a ferroelectric tetragonal phase for all compositions, with the highest tetragonality (c/a = 1.009) observed for x = 0.001 exceeding that of pure BaTiO₃ (1.0083). High-resolution electron microscopy analysis revealed faceted particles with mean sizes between 362.5 nm and 488.3 nm. Low-doped samples (x = 0.001 and 0.002) exhibited higher permittivity than undoped BaTiO₃, with the maximum dielectric constant (ε_r = 2469.0 at room temperature and 7499.7 at the Curie temperature) recorded for x = 0.001 at 1 kHz. At x = 0.006, minimal permittivity variation indicated a stable dielectric response. A decrease in the Curie temperature was observed with increasing doping levels, indicating a progressive tendency toward the cubic phase. Critical exponent γ values (0.94–1.56) indicated a sharp phase transition for low-doped samples and a diffuse transition for highly doped BaTiO₃. These results showed that La³⁺/Bi³⁺ co-doping effectively tunes the structural and dielectric properties of BaTiO₃ ceramics. Full article