Powders

The solidification process is crucial for preparing high-performance superconductors and is strongly dependent on the characteristics of the starting powder, including particle size, morphology, and phase purity. This review concisely examines the study on four key superconductors: REBCO, Bi-2212, FeSeTe, and MgB₂. In REBCO, additives such as CeO₂, Pt, or BaO₂ powder can refine the RE-211 phase. In Bi-2212, Pb doping stabilizes the high-T_c phase. For FeSeTe, doping with F or Co modifies phase separation and introduces Δκ pinning. Meanwhile, in MgB₂, the incorporation of SiC nanoparticles powder generates effective pinning centers. Concurrently, processing conditions exert a decisive influence on the final microstructure, as demonstrated by the TSMG/TSIG route in REBCO, partial melting parameters for Bi-2212, specific cooling protocols and thermal treatments for FeSeTe, and optimized sintering and post-annealing processes for MgB₂. Future research directions should prioritize fundamental understanding of phase separation mechanisms during powder processing, development of multi-component doping strategies for powder modification, and advancement of scalable powder processing routes for practical conductor architectures. Full article

Nine elements found in 24 cumin samples from China, India, Syria and Turkey were measured by laser ablation–inductively coupled plasma–time-of-flight mass spectrometry (LA-TOF-MS) for the purpose of collecting data that could be used to discriminate among the origins. Pellets were prepared from the powdered samples and elemental abundances were measured. Discriminant function analysis (DFA) of this data was used to qualitatively differentiate the cumin from four different origins. This data was in agreement with that we obtained when calculating concentrations based on external calibration curves created using six National Institute of Standards and Technology (NIST) standards with ¹³C internal standardization. These curves were validated using NIST 1573a (tomato leaves) as a check standard. We highlight the usefulness of the information gained as well as its potential application to the analysis of trace evidence in a forensics laboratory. Full article

Wet stirred-media milling (WSMM) is among the most widely used techniques for producing high-drug-loaded stable nanosuspensions, owing to its ease of scale-up, good repeatability, operational versatility and broad applicability. However, WSMM is also associated with high energy demand, substantial heat generation, and extended milling times. To reduce energy consumption, optimize the process and gain a deeper understanding of breakage kinetics, robust mechanistic models should be investigated. In this study, a microhydrodynamic (MHD) model framework is examined, and the first closed-form analytical solution for granular temperature $\theta$, a key parameter in the MHD model, is derived. In addition, an existing power consumption correlation from the literature is adopted and extended by introducing an additional parameter that accounts for bead-size effects, and the resulting improved formulation is embedded into the analytical framework. This integration facilitates continuous evaluation of power consumption, $\theta$ and the additional MHD parameters across the milling parameter space. With backward compatibility and high-quality fitting performance, the improved power consumption model enables robust, reliable, and systematic evaluation of sensitivities and trade-offs over diverse milling conditions, including varying stirrer speeds, bead loadings, and bead sizes. Full article

In this work, the hydrogenation behavior of a near-equiatomic Ti-V-Zr-Nb-Mo-Hf-Ta-W refractory high-entropy alloy (R-HEA) exposed to pressurized hydrogen has been thoroughly investigated. Isothermal gas-phase hydrogen absorption experiments have been performed and a maximum uptake of 1.13 wt.% H has been achieved after exposure to a pure H₂ atmosphere at 350 °C and 60 bar H₂ for 6 h. This hydrogen absorption capacity is rather low compared to previous literature, where capacities as high as 2.7 wt.% have been reported. The presence of two distinct (Hf,Zr)-mixed oxides at the surface of the particles has been deduced from X-ray diffraction analyses and identified as the main reason for the relatively low H uptake and the minimal impact onto the mechanical integrity of the R-HEA after hydrogenation. The results hereby reported suggest that R-HEAs containing strong oxide-forming elements such as Hf, Zr, and Ti undergo surface hydrogenation-regeneration upon intermittent exposure to a hydrogen atmosphere. The cyclic nature of such phenomena should be further investigated, as it could lead to the development of novel, self-regenerating protective materials against hydrogen diffusion and embrittlement to be potentially used as permeation barriers. Full article

Nanoparticle powders of a Ce_1−xRu_xO₂ mixed oxide (3.0% w/w), were synthesized to be used as catalytic supports, on which Pt and Ir nanoparticles were deposited as the active phase. The catalytic supports were prepared through a route involving microwave heating, while the Pt or Ir nanoparticles were incorporated via the wet incipient method. The {Pt, Ir/Ce_1−xRu_xO₂} catalytic systems were successfully tested as catalysts for low-temperature CO oxidation. To provide adequate support to our results, the compounds were characterized by SEM, EDS, XRD, DRS-UV-vis, and XPS techniques. In addition, BET isotherms were carried out to determine specific surface area features. The CO oxidation evolution was tested in the range of 25–350 °C. Both Pt and Ir supported Ce_1−xRu_xO₂ catalysts that remarkably improved the CO oxidation, reaching and sustaining 100% conversion from 125 °C onwards. Remarkably, the mixed oxide support, by itself, showed outstanding performance, achieving 100% conversion to CO₂, at a temperature of 225 °C. Full article

An in-line process analytical technology that measures drag force exerted by wet mass in a high-shear granulator on a thin cylindrical probe enabled real-time identification of distinct stages in high-shear wet granulation of acetaminophen. The technology known as Lenterra in-line rheometer outputs two parameters, the mean force pulse magnitude (MFPM) and the coefficient of variation of force pulse magnitude (CVFPM), that characterize granule densification and size uniformity in real time, providing a process fingerprint. The MFPM and CVFPM evolutions measured during granulation of acetaminophen formulations for varied amounts of added water were compared with the results of particle size distribution (PSD) analysis of the powder released after granulation and with the tablet dissolution tests. The comparison demonstrated a correlation between salient features of the MFPM and CVFPM evolutions and particle size distributions for different water amounts. Based on the measured process fingerprints, it was possible to identify the water amount optimal for best granulation output. In addition, MFPM and CVFPM evolutions allowed for the prediction of a granulation endpoint. The results indicate that in-line rheometry can be a useful tool for formulation development and scale-up of high-shear wet granulation processes. Full article

Caking and powder adhesion are widespread challenges in dry powder processes. The influence of process parameters such as humidity and temperature on the adhesion behavior of dry powders has been extensively studied in numerous studies. Besides that, the impact of other process characteristics, such as additional process parameters or wall materials, has received little attention so far. In addition, existing methods to characterize caking behavior do not account for powders in a fluidized state. To address phenomena based on process and material behavior, a test rig was specifically designed to investigate the adhesion of dry particles to different metal walls at varying speeds at a 90° angle, representing the main novelty of this study. The deposition area, deposition mass, and maximum deposition thickness were evaluated, and the correlations were discussed. The investigations revealed that at low velocities (<12 m/s) and for smooth surfaces (Sq < 0.3–0.4 µm), wall materials with a high ratio of dispersive to polar surface energy components (D/P: 13–15.8) exhibit minimal powder adhesion. The test rig has demonstrated its effectiveness as a straightforward method for measuring adhesion across various powder–wall material pairs and could serve as a valuable preliminary test for industrial applications. Full article

The increasing demand for sustainable construction materials has intensified research on supplementary cementitious materials capable of reducing Portland cement consumption and associated CO₂ emissions. In this context, porcelain polishing residue (PPR), a fine ceramic waste generated by the tile industry, presents potential for valorization in cement-based composites. This study investigates the use of PPR as a supplementary cementitious material in self-compacting concrete (SCC), focusing on its pozzolanic activity and its influence on fresh, physical, and mechanical properties. Pozzolanic behavior was evaluated using strength-based indices with lime and Portland cement, as well as the modified Chapelle method. SCC mixtures were produced with partial replacement of cement by PPR at different levels and assessed in terms of self-compactability, compressive strength, elastic modulus, water absorption, and void index. The results showed that, although PPR did not meet strength-based pozzolanicity criteria at early ages, it exhibited significant calcium hydroxide consumption, indicating latent pozzolanic potential. Fresh-state properties were preserved in all mixtures, and an optimal replacement level of 20% resulted in improved long-term mechanical performance, reduced void content, and enhanced matrix compactness. These findings demonstrate that PPR can be effectively used as a functional supplementary cementitious material in SCC, contributing to more sustainable and eco-efficient concrete production. Full article

The influence of YB₄ particle addition on the microstructure and the associated thermal and mechanical properties of AISI 420 stainless steel composites fabricated using the vacuum induction melting technique was investigated. Microstructural analysis using scanning electron microscopy (SEM) confirmed the presence of YB₄ particles within the BCC-structured martensitic matrix and also along the grain boundaries across all weight fractions. In addition, YB₄ addition resulted in a pronounced refinement of the martensitic matrix, as evidenced by a progressive reduction in the size of the packets, i.e., a group of martensitic laths/plates sharing the same habit plane variants with the parent austenite grain. The presence of YB₄ particles induced internal stresses and microstrains, leading to peak shifting and broadening of the X-ray diffraction (XRD) peaks corresponding to that of the martensitic matrix phase. The coefficient of thermal expansion (CTE) decreased significantly from 13.4 × 10⁻⁶ K⁻¹ for monolithic AISI 420 to 8.06 × 10⁻⁶ K⁻¹ for the AISI 420/4 wt.% YB₄ composite and was attributed to the excellent dimensional stability of YB₄ particles. The maximum hardness (913.12 HV) and tensile strength (930 MPa) were achieved for the AISI 420/4 wt.% YB₄ composite. Fractographic analysis using SEM indicated a transition from ductile to brittle fracture with increasing YB₄ content, suggesting a reduction in strain-hardening capacity. The contributions of various strengthening mechanisms were quantified using the summation of strengthening and modified Clyne models, revealing that strengthening due to load bearing is dominant across all composites. Insights gained from these results are important to strategize the design of boride-based metal-matrix composites with enhanced strength–ductility synergy for structural applications. Full article

Metal additive manufacturing relies on fine powders whose properties influence flow, spreading, and airborne release during processing, yet published data on powder characteristics, reuse effects, and emissions remain fragmented and difficult to compare. This study reviews quantitative measurements reported for metallic feedstocks used in laser powder bed fusion and directed energy deposition. A numerical evaluation model is developed to connect powder properties, process conditions, dispersion tendency, and material recovery. Particle size distribution values, density metrics, flow test results, reuse-related oxidation, and nanoparticle counts were compiled from the literature and normalized on a 0–1 scale. Four independent indices were defined: Material Fingerprint, process–powder interaction, airborne dispersion potential, and recovery. Adaptiveness refers to index sensitivity to changes in powder, reuse, and process conditions. The results indicate stable spreading for gas-atomized feedstocks, while wider particle size distributions and rougher surfaces increase cohesion and agglomeration, particularly under humid conditions and during reuse. Emission data indicate nanoparticle formation during processing, with recovery efficiency dependent on cyclone or high-efficiency particulate air filtration selection. The proposed model offers a screening approach for comparing powders and planning recovery strategies using data already available in the literature. Full article

The use of monolithic alumina is limited by its intrinsic brittleness, which is commonly addressed through second-phase reinforcement. Silicon carbide (SiC) is an attractive reinforcement due to its high-temperature stability; however, its oxidation behavior strongly influences composite processing and properties. In this study, alumina/SiC composites containing 1, 5, and 10 wt.% SiC were prepared by conventional powder mixing, calcined at 800 °C for 1 h, and pressureless sintered at 1400 °C in air. Phase evolution, microstructure, densification, and mechanical properties were investigated using XRD, SEM/EDS, density–porosity measurements, and flexural testing. Air sintering led to SiC oxidation and the formation of silica-rich glassy phase and mullite, which significantly affected densification. The composite containing 1 wt.% SiC exhibited the best performance, with a flexural strength of 248.7 MPa, a Weibull modulus of 5.7, an average grain size of 1.86 µm, and a porosity of 11.08%. Higher SiC contents resulted in excessive porosity and severe degradation of mechanical properties. Full article

Photocatalysis is a process in which a material utilizes light energy to degrade contaminants through oxidation reactions that decompose impurities upon contact with its surface. Titanium dioxide is one of the most widely used semiconductor materials due to its abundance, chemical stability, and non-toxicity. However, its relatively wide bandgap restricts its photocatalytic activity to the ultraviolet region of the solar spectrum, limiting its overall efficiency under natural sunlight. The incorporation of copper nanoparticles into the TiO₂ matrix enhances light absorption by extending its activity into the visible range, thereby improving its energy conversion efficiency. In this study, undoped and Cu-doped TiO₂ powders were synthesized using the mechanochemical method. The characteristics of the prepared photocatalyst material were determined by XRD, SEM, absorbance, and chemical analysis. XRD analysis showed the formation of TiO₂ in its anatase and rutile phases. Sphere-like shapes with a size of 100 nm were inferred from SEM images. The photocatalytic tests revealed that the Cu-doped TiO₂ nanoparticles exhibited high photocatalytic activity in degrading contaminated water. This enhancement can be attributed to the formation of oxygen vacancies, which promote the photodegradation of organic compounds. Full article

This is a review article that covers the history of the development of the equation of motion for solid particles in fluids, starting with the early work, before the Navier–Stokes equations were developed. Particular emphasis is placed on the development of the transient equation of motion, which features the history (or memory) term and the added mass (virtual mass) term. The salient features of the equation and the methods of their derivation are pointed out. Creeping, non-inertia flows as well as advective flows are surveyed, with particular emphasis on their effects on the functional form of the history term. Modifications to the hydrodynamic force due to possible interface slip are also examined. The review also deals with the inclusion of the weaker lateral (lift) forces and the inclusion of the effects of Brownian movement, which gives rise to thermophoresis—an important source of nanoparticle movement and surface deposition. The drag on irregularly shaped particles—another important feature of nanoparticles—is also examined. The review concludes with a short section on significant unknown issues and work that may be carried out in the near future for the theoretical and computational development of the subject. Full article

Powder flow is a constant concern in the production of solid dosage forms. Its concise and reliable determination and improvement are challenges for the pharmaceutical industry. Lactose (Lac) and microcrystalline cellulose (MCC) are both widely used pharmaceutical fillers either alone or mixed. In this study, flow determination was performed through methods described on the European Pharmacopoeia. The results obtained showed poor flow and cohesive behavior for Lac and MCC powders and their mixtures (co-processed excipients). The 50% Lac_MCC mixture, with colloidal silicon dioxide (CSD) as the glidant in different proportions, showed relevant improvements in flow. In addition, the effective angle of wall friction (φx), the effective angle of internal friction (φe), arching, and ratholing were also determined, demonstrating the flow behavior in the discharge equipment. Outlet diameters that prevent blockages or insufficient powder flow were also determined. With this study, it was concluded that it was possible to prepare a co-processed excipient with optimal flow behavior composed of Lac_MCC and CSD as a glidant. Full article

Ammonium paratungstate (APT) was synthesized from scheelite ore concentrates from the Brejuí Mine in Currais Novos, Rio Grande do Norte, Northeast Brazil. The process involved acid leaching to obtain tungstic acid (H₂WO₄), followed by its conversion to APT. A 2³ factorial design evaluated the influence of temperature, HCl concentration, and reaction time on the leaching efficiency, revealing temperature and acid concentration as significant variables. Tungsten extraction reached 98.6% under moderate time and temperature conditions. The resulting H₂WO₄ phase exhibited a lamellar and porous morphology, facilitating its rapid dissolution and crystallization into APT at 60 °C. The produced nanometric APT exhibited high purity, a mixed rod-like/cubic morphology, and thermal stability above 600 °C. This work adds value to the Brazilian tungsten deposits by supporting more efficient and sustainable extraction routes for obtaining APT. Full article

This study assesses two Brazilian Type F fly ash samples (FA-A and FA-B), collected from the same thermoelectric complex in different years, to investigate their influence on the production of alkali-activated materials (AAMs). FA-A exhibited a slightly higher SiO₂/Al₂O₃ ratio (3.52 vs. 3.34) and a finer average particle size (D₅₀ = 19.7 μm vs. 30.8 μm) than FA-B. X-ray diffraction revealed that FA-A presented a broad amorphous halo between 15° and 35° (2θ), indicative of phases with low atomic ordering, which are more susceptible to dissolution and capable of supplying Si- and Al-rich species for the formation of alkali activation products. These differences directly affected reactivity and mechanical performance. After 1 day of curing, FA-A-based matrices achieved 88.5 MPa in compressive strength—approximately 100% higher than FA-B (44.2 MPa). However, FA-A suffered a 19.6% strength reduction after 28 days of curing, whereas FA-B showed only a 3.8% decrease over the same period, reflecting better long-term stability. FTIR confirmed Na₂CO₃ formation in FA-A, associated with excess sodium (Na/Al = 2.07 after 28 days), while SEM revealed unreacted spheres persisting in FA-B, consistent with its lower dissolution rate. Water absorption was also significantly different, with FA-B matrices reaching values up to 52% lower than FA-A after 7 days of curing. These results demonstrate that even slight variations in chemical composition and atomic ordering, even for ashes from the same plant, strongly influence the reactivity, microstructure, and mechanical performance of alkali-activated binders. Full article

This study presents an approach to synthesizing LTA-type zeolite from spodumene residue generated during a lithium extraction process. A residue was obtained after leaching β-spodumene with 2 mol/L phosphoric acid. After solid–liquid separation, the delithiated residue was first treated with 2 mol/L sodium hydroxide and then subjected to hydrothermal synthesis using sodium aluminate as an additional aluminum source. The resulting material was characterized by XRD, SEM-EDS, XPS, and FTIR, which collectively confirmed the formation of a crystalline material exhibiting the structural features, elemental composition, and morphological characteristics consistent with LTA-type zeolite. Additional analyses, including BET surface area, particle size distribution, and zeta potential measurements, were performed to further evaluate the physicochemical properties of the synthesized zeolite. The spodumene leach residue (SLR)-derived zeolite was further tested for its adsorption performance in heavy metal ions removal from a mixed ion solution containing Pb²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ ions. The zeolite demonstrated a high selectivity for Pb²⁺, followed by moderate uptake of Cu²⁺, while Zn²⁺ and Ni²⁺ adsorption was minimal. These findings demonstrate that spodumene residue, a waste by-product of lithium processing, can be effectively upcycled into LTA zeolite suitable for heavy metal remediation in water treatment applications. Full article

The growing regulatory scrutiny and the emerging trends towards natural products and clean labels have led to a particular focus on food supplements’ composition, including excipients. The objective of this study is to establish a methodological approach combining conventional techniques, i.e., tapped density and flowability testers, with more objective and quantitative ones to identify alternative powder excipients that can replace conventional ones in the development of solid-dose formulations without affecting their processing, workability, and mechanical properties. In the first phase, the alternative powder excipients were characterized in terms of cohesiveness, compressibility, and flow function coefficient. We then evaluated the possibility of using selected excipient combinations to totally and/or partially replace the conventional excipients within three nutraceutical formulations. Glyceryl behenate at 1–3% w/w could be considered as a viable alternative lubricant to magnesium stearate without compromising the rheological properties of the mixtures. Fructo-oligosaccharides showed a free-flowing behavior comparable to calcium phosphate and microcrystalline cellulose, improving the flowability and compressibility of the formulations. The study of powder rheology could be advantageous to formulate new products or reformulate existing ones in a time- and money-saving way, leading to high-quality products that can appeal to consumers in terms of health-functional effectiveness. Full article

In recent years, sustainable recycling approaches for chicken eggshell waste have increased significantly worldwide due to environmental and circular economy benefits. This work aimed to synthesize and characterize a new calcium aluminate powder using chicken eggshell waste as an alternative source of calcium carbonate through mechanical activation and subsequent calcination. The starting formulation consisting of the eggshell waste (CaCO₃):Al₂O₃ (1:1) ratio was subjected to a high-energy milling process for 0 h, 15 h and 30 h and subsequent calcination at 1200 °C for 4 h. The resulting calcium aluminate powders have been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and photoluminescence techniques. After calcination, a calcium aluminate-based composite powder with an average crystallite size between 46.45 nm and 52.27 nm and a predominance of the CaAl₂O₄ phase was found. The calcium aluminate powders produced (milled for 15 h and 30 h and calcined at 1200 °C) showed a luminescent behavior, emitting characteristic violet light with a wavelength between 380 and 418 nm. Our findings may provide a novel technical pathway for recycling chicken eggshell waste into calcium aluminate powder with luminescent properties. Full article