Search Results (139)

Fine soy protein isolate (SPI) powders exhibit poor handling and reconstitution properties, while excessive liquid loading can destabilize fluidized-bed agglomeration. This study evaluated an outlet-air relative humidity (RH)-triggered binder-diversion strategy during pulsed fluidized-bed agglomeration of SPI. Atomization pressure (0.5, 1.0, and 1.5 bar), nominal binder pump setting (3.8, 4.7, and 5.6 mL·min⁻¹), and operating mode (continuous spraying or RH-triggered control at a 70% set point) were investigated. Under continuous spraying, outlet RH showed an overall increase throughout the 30 min process. RH-triggered operation maintained outlet RH near the set point after threshold attainment by reducing the spray duty cycle to 0.67–0.96. This corresponded to 102.6–131.0 mL of sprayed water per run, approximately 4–33% less than continuous spraying at the same nominal pump setting. Compared with continuous spraying, RH-triggered operation produced a lower mean final moisture content in all nine conditions, a higher mean process yield in seven conditions, higher D₅₀ values in all conditions, and a lower mean particle size span in seven conditions. Agglomeration reduced the packing-derived CI and HR and shortened wetting time relative to raw SPI, whereas the effects of RH-triggered operation on flow indices, wetting time, and dispersibility depended on atomization pressure and effective binder delivery. Because the feedback action changed both cumulative binder addition and spray history, the observed product differences represent the performance of the complete RH-triggered control strategy rather than an independent effect of RH stabilization. The findings demonstrate the feasibility of outlet-RH-based adaptive binder delivery during pulsed fluidized-bed agglomeration of SPI. Full article

Water atomization is widely used for producing FeSiCr alloy powder, in which melt delivery conditions strongly influence jet breakup and powder refinement. In this study, a coupled volume of fluid-discrete phase model (VOF-DPM) was established to investigate the effect of delivery tube diameter (3, 4, 5, and 6 mm) on flow characteristics, interfacial instability, and droplet evolution at a constant water pressure of 120 MPa, and the simulation results were validated by industrial trials. As the tube diameter increased from 3 to 6 mm, the melt mass flow rate rose from 0.100 to 0.368 kg/s, the primary breakup position shifted downstream from 94.6 to 236.5 mm, and the peak negative pressure along the centerline decreased from −41.12 to −31.65 kPa. The simulated average particle size increased from 9.176 to 22.791 μm, while the experimentally measured mean particle size increased from 9.0 to 19.6 μm and the fine-powder yield decreased from 43.77% to 22.28%. Although the 3 mm tube produced the finest powder, it showed a higher tendency for clogging and unstable melt delivery. Overall, the 4 mm delivery tube provided the best balance between powder refinement, size uniformity, and production stability. Full article

Micro-structured SAE H13 tool steel inserts for polymer injection molding require accurate replication of sub-millimeter features while retaining adequate densification and heat-treatment response. This study compared two powder-based routes on the same hemispherical insert containing pyramidal features of approximately 0.145 mm base width: hot embossing (HE) of water-atomized SAE H13 powder (supplier d50 = 5.7 µm, irregular morphology) compounded with a commercial M1 binder, and material extrusion (MEX) of a commercial gas-atomized SAE H13 filament processed on a Markforged Metal X. Rheological screening selected a 57:43 vol% powder-to-binder ratio for the in-house HE feedstock, and DSC/TGA measurements defined two-step debinding windows. The best HE conditions were 220 °C, 8 MPa, and 45 min for the in-house mixture, and 210 °C, 8 MPa, and 30 min for the granulated commercial filament; the latter showed a 0.15% linear deviation from the silicone replica diameter among the best-rated samples. Under the tested commercial MEX configuration, the pyramidal features were not resolved because the 0.40 mm deposition line width exceeded the target feature base width, causing the slicer to omit the sub-line-width geometry. The defect populations differed qualitatively: HE specimens showed porosity and local cracking associated with powder morphology and pressureless sintering, whereas MEX specimens showed build-direction-aligned inter-raster voids associated with the toolpath. Microhardness and tensile data are therefore interpreted as process-history-specific results rather than as a direct route ranking, because sintering conditions were not uniform across all specimens. The study defines an experimentally bound process-selection limit for SAE H13 micro-tooling: HE remains preferable for sub-nozzle surface features, whereas MEX remains attractive for macro-scale geometric freedom, if resolution, densification, and post-sintering consolidation are addressed. Full article

The excessive emission of greenhouse gases (CO₂, CH₄, SF₆, and CF₄.) is a primary driver of global climate change, making the development of efficient adsorption and separation technologies critically important for achieving carbon reduction goals. Metal–organic frameworks (MOFs) have attracted considerable attention in this field due to their crystalline porous structures, ultrahigh surface areas, and tunable pore architectures. However, pristine MOFs face significant bottlenecks including poor water stability, high bed pressure drops caused by their powdered form, and limited mass transfer, which severely hinder their industrial application. The integration of MOFs with functional materials such as carbon materials, polymers, metal oxides, and porous SiO₂ offers a synergistic strategy to overcome these limitations. Carbon materials provide hydrophobic barriers and mesoporous transport channels, polymers enhance processability and mechanical strength, metal oxides introduce basic sites for enhanced chemisorption, and MOF-on-MOF heterostructures enable atomic-level interfacial integration and pore synergy. This review systematically summarizes recent advances in MOF composites for the separation of CO₂, CH₄, and fluorinated greenhouse gases (SF₆, CF₄.), with an emphasis on design strategies, structure–performance relationships, and synergistic mechanisms across different composite types. Finally, the current challenges including scalable synthesis, long-term stability, and separation performance under realistic conditions are discussed, and future directions toward rational design and functional synergy for industrial carbon capture and fluorinated gas emission reduction are envisioned. Full article

Postbiotics, a type of fermented functional food, are attracting attention alongside the more common pro- and prebiotics. The main production stages—fermentation, thermal inactivation, and drying—significantly influence the functional effects of these foods. This study investigated the impact of pH control during the fermentation of oat flour suspension and optimized spray-drying parameters to produce oat-based postbiotic powders. A Lacticaseibacillus paracasei CBA L74 fermented hydrolyzed oat suspension was analyzed at 37 °C for 24 h, with and without pH control. Both pH conditions produced similar bacterial growth (~10⁹ CFU/mL) and lactic acid (~9 g/L). No significant differences were observed in polyphenols, flavonoids, or antioxidant activity, indicating that pH control did not noticeably improve productivity or the phytochemical properties. The best results—57.40% drying yield and 3.9% relative humidity—were achieved when the postbiotic suspension (diluted 1:4 with water) was mixed 1:1 with maltodextrins, and the spray drying process was conducted with 50 L/min air flow, 200 °C, 3.2 bar atomization pressure, and 5 L/min feed flow. These results support the possibility of scaling the production process from laboratory-optimized parameters and represent a first step toward a cost-effective and industrially feasible route for manufacturing stable oat-based postbiotic powders. Full article

Zinc deficiency is recognized as a global public health concern, affecting populations of all ages. This study aims to develop zinc supplements (nutraceuticals) based on by-products of the fruit and vegetable processing industry. Dehydrated apple and beetroot pomace powders were enriched with vitamin C and zinc via fluid-bed wet granulation, producing granules with substantially improved flowability (Carr’s index reduced by up to 45%, Hausner ratio by up to 25%, while the bulk and tapped density were reduced by up to 25% and 40%, respectively). Microbiological and long-term storage stability was demonstrated by low water activity (aw) (≤0.3), moisture content (<10%), and glass transition temperatures (T_g = 29–34 °C) that were well above standard storage conditions. The formulated nutraceuticals exhibited stronger antioxidant activity compared to the starting powders, as well as significant anti-hyperglycemic activity. Furthermore, the enhanced bioaccessibility of zinc was confirmed upon in vitro digestion of granulated samples, using atomic absorption spectrometry and differential pulse voltammetry. The present findings demonstrate that apple and beetroot pomaces can be successfully valorized as sustainable and functional matrices for zinc enrichment, being free of gluten, artificial sweeteners, colorants, preservatives, anti-caking agents, and anti-nutritional factors such as phytic acid. Full article

Gas atomization is one method for producing fine metal powder. In close-coupled gas atomization, a high-speed gas jet is ejected near the molten metal, and the molten metal is further broken down in the shear layer at the outer edge of the jet, producing fine metal powder of several micrometers to several tens of micrometers. By the way, in close-coupled gas atomization, if the protrusion length of the molten metal nozzle is short, a backflow occurs that goes around the melt delivery nozzle tip and reaches the gas nozzle tip, and the small droplets of molten metal that are atomized at the exit of the melt delivery nozzle are carried by this backflow to the gas nozzle tip, causing it to erode. In this study, we experimentally clarified the existence of the backflow for the first time through measurements of velocity distribution, then the flow state of the gas flow inside the gas atomizer was visualized approximately using the atomized water flow, and the existence of a backflow was confirmed. It was shown that microdroplets of water are carried by the backflow and reach the gas nozzle tip. This was also clarified through numerical analysis results for the air flow. Furthermore, the protrusion length of the melt delivery nozzle at which backflow does not occur was determined, and this was verified in actual gas atomization experiments using molten copper. In addition, the length of the melt delivery nozzle at which backflow does not occur, i.e., the gas nozzle tip does not melt, was found. Furthermore, molten-copper experiments were conducted using this gas atomizer to evaluate its performance. Full article

Nanocrystalline CeO₂ exhibits size-dependent lattice distortions linked to defect chemistry and surface effects. However, the relationships between the oxidation state, surface interactions, and nanoparticle structure remain unclear in the existing literature, particularly when inferred from conventional nanoparticle diffraction techniques, including powder X-ray diffraction. As a result, the atomistic origin of lattice expansion or contraction with the crystallite size of ceria nanoparticles is still debated. Here, synchrotron X-ray powder diffraction data are analyzed using Rietveld refinement supported by advanced peak profile modeling based on whole powder pattern modeling (WPPM), including thermal diffuse scattering (TDS). The latter provides direct access to information on lattice dynamics. Indeed, we simultaneously determine the size distributions of crystalline domains and their atomic displacements, which are then compared and quantitatively validated with molecular dynamics (MD) simulations. Reactive MD simulations further reveal that vacancy-rich surfaces induce lattice contraction at small particle sizes under vacuum, whereas water adsorption causes surface hydroxylation and lattice expansion. These results explain lattice parameter variations in nanocrystalline ceria through the interplay of surface chemistry and environment. This insight is critical for the correct interpretation of diffraction-derived structural parameters in oxide nanocatalysts used in redox and oxygen storage applications. Full article

N₂O emissions exacerbate the greenhouse effect, urgently demanding advances in abatement technologies. Catalytic decomposition of N₂O over cobalt-based oxides with alkali metal promoters remains challenging because these catalysts are used in pelletized form, limiting their activity to a narrow outer-shell region due to internal diffusion limitations. However, research efforts continue to focus on enhancing Co–alkali metal contact on unsupported powder samples under inert conditions, even though, under industrial conditions, catalysts are exposed to inhibitory components of waste gases and N₂O, and the powder form is unsuitable for practical application. This study aims at testing N₂O decomposition over catalysts with a Co₃O₄-Cs active phase supported on a ceramic foam. For this purpose, we characterized these catalysts by H₂ temperature-programmed reduction, H₂O and NO temperature-programmed desorption, atomic absorption spectroscopy, and X-ray diffraction and assessed their catalytic performance under an inert-gas atmosphere and with O₂, water vapor, and NO to simulate industrial conditions. Using a pseudo-homogeneous, one-dimensional model of an ideal plug flow reactor in an isothermal regime, the simulation calculations for a full-scale catalytic reactor for N₂O abatement in waste gas from HNO₃ production were performed. The Cs₂CO₃ precursor significantly enhanced catalyst reducibility and electron transferability, increasing N₂O decomposition efficiency in inert gas, but its high hygroscopicity decreased resistance to water vapor and NO, overriding its advantages under industrial conditions. Conversely, glycerol-assisted impregnation enhanced catalyst performance regardless of Cs precursor. These foam-supported catalysts offered several other advantages, including lower pressure drop and lower active phase loading with matching catalytic activity. Based on our findings, depositing Cs₂CO₃ on ceramic foam through glycerol-assisted impregnation may facilitate catalytic N₂O decomposition at the industrial level and, therefore, promote environmental sustainability by reducing N₂O emissions. Full article

This paper presents a focused review of a closed-loop system for sustainable hydrogen production utilizing the reaction between metallic aluminum powders and water, coupled with renewable energy-driven recycling of aluminum hydroxide (or alumina) byproducts back to metallic aluminum powders. A green energy closed-loop system based on aluminum could be achieved if the converting process is accomplished by a green Hall–Héroult process, where a cermet inert anode was used. Meanwhile, the byproduct alumina is converted back to the liquid form of aluminum at high temperature (up to 960 °C), producing pure oxygen. A high-pressure atomization process is then used to break the aluminum droplets into powder using argon gas. The technical feasibility, thermodynamic efficiency, economic viability, environmental sustainability, and comparison of this green aluminum cycle with existing hydrogen production and energy storage technologies are discussed. The aluminum–water reaction offers exceptional energy density (29.7 kJ/g of Al), ambient temperature operation, and zero direct carbon emissions. However, commercial implementation faces substantial challenges including overall round-trip energy efficiency (estimated 34.5–46.6%), technological maturity of the recycling process, passivation layer management, and economic competitiveness with conventional water electrolysis. Despite these challenges, the system demonstrates advantages for seasonal energy storage, off-grid applications, and integration with intermittent renewable energy sources. This analysis provides a framework for researchers, engineers, and policymakers to assess the potential role of aluminum-based energy cycles in the global energy transition toward carbon neutrality. Full article

This study investigated the impact of pH adjustment and carrier type on the physicochemical properties, antioxidant activity, thermal stability, hygroscopicity, and particle size distribution of spray-dried model solutions and carrot juice formulations. Model systems were created at varying pH levels (3, 4, 6, 8, and 10) using water alone or with carriers such as octenyl succinic anhydride (OSA)-modified starch (O), trehalose (T), or a combination (OT in a 1:1 ratio at 9–10%). These systems were compared to carrot juice and formulations of carrot juice that included the same carriers. Spray drying was performed at 160 °C using constant feed flow and atomization conditions. In the liquid samples, we measured pH, dry matter, density, conductivity, and color parameters, while the bioactive compounds were analyzed in carrot juice systems. For the powders, we evaluated the dry matter content, color, particle size distribution, morphology, thermal stability, hygroscopicity, and antioxidant activity. Results showed that in model systems, dry matter, density, and conductivity were more affected by the carrier chemistry than pH. Formulations with OSA had lower pH and higher conductivity due to ionizable groups, while trehalose acted neutrally. OSA-trehalose mixtures yielded the highest solids content and stable properties across pH levels, with particle size (D₅₀ range of 18–21 µm) and morphology of the model powders remaining largely unaffected by pH. In carrot juice formulations, however, particle properties were pH-dependent. Acidic conditions (pH 3–4) led to agglomeration and broader size distributions (indicated by increased span values), while neutral to alkaline conditions produced smaller, more uniform particles with improved thermal stability. Neutral to alkaline conditions favored the formation of smaller, more homogeneous particles and improved thermal resistance. The carotenoid content in carrot juice powders increased from approximately 21–23 mg/100 g dry matter (d.m.) under acidic conditions to about 27–30 mg/100 g d.m. at pH 8–10, which was accompanied by higher ABTS antioxidant activity (around 6–9 mg Trolox equivalents (TE)/g d.m.). In contrast, the polyphenol content was highest at low pH levels (approximately 350–420 mg chlorogenic acid (CA)/100 g d.m.), corresponding to elevated DPPH scavenging activity and reducing power, both of which decreased under alkaline conditions. These findings indicate that pH levels and carrier choice significantly affect spray-dried powders. This highlights the importance of validating model system observations in complex food matrices. By adjusting pH and selecting suitable carriers, we can create powders with improved structures, stability, and antioxidant functionality, particularly in foods like carrot juice. Full article

Cavitation resistance in hydraulic machinery requires the turbine and water pump surface to simultaneously possess high hardness and plasticity. To keep the FCC structure of the Al_xCoCrFeNi alloy matrix and introduce the particle strengthening effects, the suitable weight content of Cr₂AlC particles was calculated and added into Al_0.3CoCrFeNi powders. Due to the decomposition of Cr₂AlC during laser cladding, the microhardness of Al_0.3CoCrFeNi was enhanced by Al atoms and the eutectic-like Cr₇C₃ structure. In comparison with 5.81 GPa of Al_0.3CoCrFeNi coating measured by nanoindentation, the values of the eutectic-like structure and the matrix were measured as 7.76 GPa and 5.93 GPa in 12 wt.% Cr₂AlC/Al_0.3CoCrFeNi coating. Attributed to the pinning effect of hard Cr₇C₃ and high plastic matrix, the mass loss was reduced from 7.25 × 10⁻⁴ g/mm² for Al_0.3CoCrFeNi coating to 1.91 × 10⁻⁴ g/mm² Cr₂AlC/Al_0.3CoCrFeNi coating with a ratio of 73.8%. Full article

This study systematically benchmarks the performance of four single soft magnetic powders—water-atomized Fe–Si–Cr (FeSiCr), silica-coated reduced iron powder (RIP), silica-coated carbonyl iron powder (CIP), and phosphate-coated CIP (CIP-P)—to establish quantitative relationships between powder attributes, deformation substructure, and high-frequency loss for molded power inductors (100 kHz–1 MHz). We prepared toroidal compacts at 200 MPa and characterized them by initial permeability (μ_i), core-loss (P_cv(f)), partitioning (P_cv(f) = K_hf + K_ef², K_h, $K_{\mathrm{e}}$: hysteresis and eddy-current loss coefficients), and EBSD (electron backscatter diffraction)-derived microstrain metrics (Kernel Average Misorientation, KAM; low-/high-angle grain-boundary fractions). Corrosion robustness was assessed using a 5 wt% NaCl, 35 °C, 24 h salt-spray protocol. Our findings reveal that FeSiCr achieves the highest μ_i across the frequency band, despite its lowest compaction density. This is attributed to its coarse particle size (D₅₀ ≈ 18 µm) and the resulting lower intragranular pinning. The loss spectra are dominated by hysteresis over this frequency range, with FeSiCr exhibiting the largest K_h, while the fine, silica-insulated Fe powders (RIP/CIP) most effectively suppress K_e. EBSD analysis shows that the high coercivity and hysteresis loss in CIP (and, to a lesser extent, RIP) are correlated with dense, deformation-induced subgrain networks, as evidenced by higher mean KAM and a lower low-angle grain boundary fraction. In contrast, FeSiCr exhibits the lowest KAM, with strain confined primarily to particle contact regions. Corrosion testing ranked durability as FeSiCr ≳ CIP ≈ RIP ≫ CIP-P, which is consistent with the Cr-rich passivation of FeSiCr and the superior barrier properties of the SiO₂ shells compared to low-dose phosphate. At 15 A, inductance retention ranks CIP (67.9%) > RIP (55.7%) > CIP-P (48.8%) > FeSiCr (33.2%), tracking a rise in effective anisotropy and—for FeSiCr—lower M_s that precipitate earlier roll-off. Collectively, these results provide a microstructure-informed selection map for single-powder formulations. We demonstrate that particle size and shell chemistry are the primary factors governing eddy currents (K_e), while the KAM-indexed substructure dictates hysteresis loss (K_h) and DC-bias superposition characteristics. This framework enables rational trade-offs between magnetic permeability, core loss, and environmental durability. Full article

Two nitrogen-modified mesoporous MCM-41-type silicas were synthesized by the sol–gel route and post-grafting surface modification procedure, obtaining an aminopropyl-modified MCM-41 (denoted MCM-41-N) and an aminoethyl-aminopropyl-modified MCM-41 (denoted MCM-41-NN). Hexavalent chromium removal from acidified water by adsorption and reduction to Cr(III) on the solid mesophases was analyzed. The modified silicas were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectra (FT-IR), nitrogen adsorption–desorption measurements at −196 °C, X-ray photoelectron spectroscopy (XPS), ²⁹Si solid state Nuclear Magnetic Resonance (²⁹Si-RMN), and thermogravimetric analysis (TGA). Both samples exhibited very high capacities for decreasing Cr(VI) concentrations in water, according to the Langmuir isotherm model: 129.9 mg·g⁻¹ for MCM-41-N and 133.3 mg·g⁻¹ for MCM-41-NN. The chromium speciation in the supernatant after 24 h indicates that MCM-41-N had a higher capacity to reduce Cr(VI) to the less toxic Cr(III) species than MCM-41-NN: 92.9% vs. 72.5% when the initial Cr(VI) concentration was 10 mg·g⁻¹. These differences were related to the different capacity of nitrogen atoms in MCM-41-N and MCM-41-NN to interact with the surrounding surface silanols which are required for the chemical reduction in the hexavalent species to take place, as evidenced by FT-IR and XPS analysis. Also, the Cr(III)/Cr(VI) atomic ratios on the solid’s surfaces were higher for MCM-41-N. These results highlight the characteristics that nitrogen atoms incorporated into silica matrices must possess in order to maximize the transformation of Cr(VI) into the trivalent species, thereby reducing the generation of toxic waste harmful to living organisms. Full article

Lepidolite is one of a small number of minerals that contains a significant amount of lithium. Some areas, like the Apuseni and Metalifer Mountains in Romania, present dark red layers intercalated with reddish-yellow clay soils with interesting aspects. X-ray diffraction (XRD) analysis coupled with polarized light optical microscopy (POM) revealed that this dark red soil contains a large amount of fine microstructured lepidolite (24–35%) mixed with quartz sand and fine traces of kaolinite and muscovite. Scanning electron microscopy (SEM) elemental analysis revealed a typical clay composition with Mn traces (specific to red lepidolite), confirming POM observation. SEM also revealed fine tabular platelets of lepidolite with a maximum size of 1.5 µm surrounding quartz particles (5–50 µm), indicating the presence of numerous nano fractions. Their presence was confirmed by atomic force microscopy (AFM), which showed particle sizes ranging from 40 to 60 nm, closely matching the crystallite size estimated using the Scherrer formula. The finest fraction allows easy separation from the quartz sand through bi-distilled water washing. Quartz particles settle at the bottom of the container, while the finest lepidolite particles are easily separated. Water evaporation ensures their recovery. Thus, the enriched lepidolite powder could be utilized for specific applications in the lithium industry. On the other hand, the large number of the finest particles found in the samples investigated presents the risk of PM1, PM2.5m, and PM10 emission, with impacts on atmospheric environmental safety. Full article