Search Results (317)

Punching shear failure in reinforced concrete RC slabs is one of the most significant and detrimental failure modes due to its sudden nature and its dependence on a complex interaction between concrete strength, the reinforcement, and the loading conditions. In recent years, there has been increasing interest in utilizing sustainable cementitious materials and steel fibers as a way of enhancing structural performance and improving the durability of concrete. The study aims to assess the structural behavior of RC slabs utilizing a partial cement substitution with limestone powder (LP) and granulated blast-furnace slag (GBFS), with the addition of steel fibers. Twelve RC slabs were examined under uniform concentric loading to analyze cracking behavior, load–deflection relationship, stiffness variation, and ultimate punching shear strength. The results demonstrated that using limestone powder (LP) had a significant impact on the crack distribution pattern and resulted in a slight reduction in initial stiffness, with the load-bearing capacity decreasing to approximately 55.8% of the control mixture at high replacement ratios. Due to a slower hydraulic reaction than with other mixtures, increasing additional granulated blast-furnace slag resulted in a decrease in crack resistance and relative deformation. With a load-bearing capacity of approximately 92.9% of the control mixture, a tertiary mixture of limestone powder and granulated blast-furnace slag (GBFS) demonstrated a better balance in structural behavior, leading to improved crack control while maintaining a sufficient level of load-bearing capacity. The steel fibers also significantly contributed to enhanced post-cracking behavior by decreasing crack width and improving the stress redistribution mechanism within the RC slab. This led to increased punching shear resistance and enhanced energy absorption, with the ultimate load increased to 119 kN compared to the control mixture. Overall, the findings show that combining sustainable cementitious materials with steel fibers can effectively improve punching shear performance and enhance the efficiency and durability of reinforced concrete. Full article

To improve the functional performance and digestibility of casein-rich ingredients, this study investigated the effects of trisodium citrate (TC) chelation and spray drying on the functional properties and in vitro digestibility of micellar casein isolate (MCI). TC chelation improved the foaming, emulsifying, gelling, and digestive properties of casein to different extents. Compared with MCI, trisodium citrate-chelated casein (TCC) exhibited significantly enhanced foaming capacity; specifically, the foaming capacities of TCC-40 and TCC-60 increased to 58.0% and 60.0%, respectively. TC reduced particle size, leading to increased foam volume, whereas foam stability decreased at higher chelation levels. In terms of emulsifying properties, TCC-10 exhibited optimal performance, with most emulsion droplet diameters distributed within 1–5 μm. TC chelation induced a significant negative shift in zeta potential (p < 0.05), suggesting improved emulsion stability. Gelation behavior was linked with concentration, showing TCC-40 induced the shortest gelation time (3.98 min) and the highest storage modulus. TC significantly enhanced casein digestibility in both adult and elderly in vitro digestion models, with digestion efficiency in the elderly model approaching that of the adult model. Confocal laser scanning microscopy (CLSM) pictures indicated that calcium chelation reduced gastric floc compactness, facilitating enzymatic access and improving protein hydrolysis efficiency. The study reveals the advantage of calcium chelation on the functional properties and digestibility of casein-based powder. Full article

The powder metallurgy route (PM route) for producing aluminum closed-cell foams has recently attracted significant scientific and industrial interest. The process involves mixing a blowing agent powder (e.g., TiH₂) with aluminum powder, then compacting the mixture to produce a high-density bulk foamable precursor (BFP). The BFP is then heated above the melting point of aluminum, where the hydrogen released from TiH₂ particles forms bubbles in the molten aluminum, which become closed pores (cells) upon solidification. Despite metal powder agglomeration being an important factor in powder metallurgy research that can significantly influence processing, it has surprisingly received little to no attention in the powder-based foaming of metals. To the best of our knowledge, this paper is the first to address aluminum powder agglomeration within the context of powder-based metallic foams. Results show that significant aluminum powder agglomeration not only leads to an inhomogeneous distribution of the TiH₂ particles within the BFP, but also to the formation of locally higher than nominal concentrations of TiH₂ particle-rich regions, which greatly influence foaming characteristics. The work, for the first time, highlights the need to seriously consider metal-powder agglomeration (even partial agglomeration) in future foaming research via the PM route, and its effect on foaming characteristics. Full article

To mitigate health hazards from pathogenic bacteria (Escherichia coli, Staphylococcus aureus) and fungi (Aspergillus niger) as well as the coating mildew issue in high-humidity indoor environments, and to overcome the challenges of particle agglomeration and non-uniform distribution in conventional benzalkonium chloride (BAC)-clay composites, this study proposes a wet chemical strategy to prepare BAC-hectorite antimicrobial composites using synthetic hectorite as a high-performance carrier, which is superior to natural clays such as montmorillonite and kaolin in structural uniformity, ion-exchange efficiency, and dispersion stability. Characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis confirmed the successful intercalation of BAC cations into the hectorite interlayers through ion exchange. This resulted in a significant expansion of the interlayer spacing from 1.0–1.2 nm to 1.5–1.8 nm, a marked alleviation of particle agglomeration, and an optimized pore structure. A clear structure–activity relationship between preparation conditions, microstructure regulation, and antimicrobial performance is systematically established. Antibacterial tests revealed superior efficacy against Gram-positive bacteria; the composite exhibited an inhibition zone of 13.31 mm and a minimum inhibitory concentration (MIC) of 4 μg/mL against S. aureus, compared to 11.62 mm and 32 μg/mL against E. coli. Practical application tests demonstrated that at an ultralow addition level of 0.4%, incorporating this composite into latex paint achieved an antibacterial rate exceeding 99.9% against both pathogens. When added to putty powder, it yielded Grade 0 mold resistance with no observable growth. Furthermore, compounding with polypropylene (PP) increased the elongation at break to approximately 600%, simultaneously realizing antibacterial, antifungal, and toughening functions, thereby not only conferring antibacterial functionality but also significantly enhancing toughness—resolving the typical polymer embrittlement caused by traditional inorganic antibacterial fillers. Short-term evaluations confirm that this composite offers a stable structure, high-efficiency antimicrobial properties, and improved substrate mechanics at low loading levels. These findings provide technical support and experimental guidance for the functional upgrading of indoor decorative coatings, putties, and polymer materials used in high-humidity scenarios such as kitchens and bathrooms. Full article

Aronia fruit dust, generated in the industrial environment during processing, is considered a by-product discharged as waste, but it still contains high amounts of bioactive compounds such as polyphenolics, particularly anthocyanins. For the efficient isolation of anthocyanins and other flavonoids from this type of material, ultrasound-assisted extraction, at previously established optimal conditions, with a temperature of 70 °C, extraction time of 80 min, and ultrasonic power of 206 W, was applied. The extraction solvent was acidified with organic acids (citric, malic, and ascorbic acids) at low concentrations (4% and 8%) prior to spray drying to investigate the effects of the liquid feed pH value on the quality of the obtained aronia powders. Three anthocyanins—cyanidin-3-O-galactoside, cyanidin-3-O-arabinoside, and cyanidin-3-O-glucoside—along with the flavonoids rutin, hyperoside, and isoquercitrin were identified. The use of malic and citric acids in combination with maltodextrin produced aronia powders with a higher bulk density, smaller particle size, and more uniform particle size distribution compared to formulations containing ascorbic acid. Full article

Powder coatings, as a widely used green surface treatment material, face significant combustion and explosion risks due to the simultaneous presence of high-concentration combustible dust clouds and electrostatic ignition sources in their application environments. With the advancement of new materials and emerging industrial sectors, research on powder coating explosions has become increasingly interdisciplinary, resulting in a somewhat fragmented knowledge base. To systematically reveal the knowledge structure, research hotspots, and development trends in this field, this study employs bibliometric methods based on 857 relevant publications retrieved from the Web of Science (WOS) Core Collection database between 2015 and September 2025. Using VOSviewer (Version 1.6.20) and CiteSpace (Version 6.4), the analysis examines institutional collaboration, journal distribution, author collaboration patterns, regional differences, co-citation relationships, knowledge foundations, and research frontiers. The results indicate that powder coating explosion research has gradually developed an integrated knowledge system centered on materials science, chemical engineering, and combustion science. Institutions from China, Russia, and India represent some of the most productive contributors in this field. Current research hotspots focus on the explosion mechanisms of powder coatings, explosion-proof materials, risk assessment, numerical simulation, and protective measures for emerging industrial applications. Future trends are expected to focus increasingly on intelligent explosion suppression systems, multi-scale coupling mechanisms, and international collaborative governance. This study provides a comprehensive knowledge map to support scientific planning and safety strategy development in powder coating explosion research. Full article

The pods of pea (Pisum sativum L.), an abundant agroindustry by-product, represents a sustainable source of bioactive compounds. To harness these compounds effectively, this study aimed to optimize the ultrasound-assisted extraction (UAE) of polyphenols and plant pigments (chlorophylls and carotenoids) from pea pod waste using response surface methodology, and to evaluate the encapsulation of the resulting extract with a novel pea-based carrier derived from whole pea grain powder. The optimal conditions for the extraction were a time of 45 min, a solid-to-solvent ratio of 1:48 (w/v), and an ethanol concentration of 58.51% (v/v). The extract obtained under these conditions was encapsulated using pea grain powder and compared with a conventional whey protein carrier. The resulting microencapsulates were characterized in terms of process yield, moisture content, particle size distribution, thermal properties, and phenolic composition. Pea grain powder as a carrier provided higher powder yield, lower moisture content, and improved thermal stability, whereas whey protein allowed slightly higher retention of most bioactive compounds, except for coumaric acid and kaempferol. Overall, these findings highlight pea grain powder as a promising plant-based carrier that supports the valorization of pea pod waste, contributing to the development of sustainable ingredients and a circular economy for legume processing by-products. Full article

Properties of composite materials with polymer matrix and inorganic filler are affected by preparation methods and starting components’ properties. For example, filler powder particle size distribution, phase composition and presence/absence of dopants can greatly affect properties of resulting composites. The present research attempts to clarify the influence of synthetic CaCO₃ powder properties on alginate/CaCO₃ composite material preparation process. Composite materials in the form of granules, networks and films were created from suspensions of synthetic powders of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate. Powders of calcium carbonates CaCO₃ were synthesized from 0.5 M aqueous solutions of calcium chloride CaCl₂ and aqueous solutions of potassium K₂CO₃ (at molar ratio Ca/CO₃ = 1), sodium Na₂CO₃ (at molar ratio Ca/CO₃ = 1), and ammonium (NH₄)₂CO₃ (at molar ratios Ca/CO₃ = 1 and Ca/CO₃ = 0.5) carbonates. Phase composition of powder synthesized from CaCl₂ and K₂CO₃ was presented by calcite. Phase composition of powders synthesized from other soluble carbonates included calcite and vaterite. The powder preparation protocol excluded the stage of synthesized powder washing for by-product removal. This preparation protocol provided preservation of reaction by-product in the synthesized powder at a very low level. The presence of NH₄Cl as a reaction by-product even in small quantities can be taken as a reason for visually observed subsequences of cross-linking reaction at the stage of suspensions preparation. Aqueous solution of sodium alginate and suspensions containing powders synthesized from potassium K₂CO₃ and sodium Na₂CO₃ carbonates demonstrated similar dependence of viscosities from shear rate. The presence of (NH₄)₂CO₃ in the powder synthesized at molar ratio Ca/CO₃ = 0.5 was the reason for the lower viscosity of the suspension in comparison with suspensions loaded with powders containing KCl, NaCl and (NH₄)₂Cl as reaction by-products due to decomposition of unstable (NH₄)₂CO₃ and gas phase formation. The presence of (NH₄)₂Cl in the powder synthesized at molar ratio Ca/CO₃ = 1 in contrast was a reason for the highest viscosity suspension in comparison with those under investigation. Additionally, (NH₄)₂Cl presence in synthetic powders shows the ability to facilitate partial dissolution of CaCO₃ providing a higher concentration of Ca²⁺ cations at the stage of suspension preparation, thus aiding the cross-linking process of alginate hydrogel. Granules, meshes and films were created via interaction of suspensions of calcium carbonates CaCO₃ in aqueous solutions of sodium alginate with 0.25 M aqueous solutions of calcium chloride CaCl₂ to provide the formation of matrix of composites via Ca-crosslinking of sodium alginate followed by washing and freeze drying under deep vacuum. The created composite materials in the form of granules, meshes and films based on Ca-cross-linked alginate and powders of synthetic calcium carbonate can be recommended for skin wound and bone defect treatment and drug delivery carriers. Full article

Achieving high density in complex powder metallurgy components like spur gears is often hindered by friction-induced density gradients and ejection defects. This study investigates a novel elastic die system designed to mitigate these issues through controlled radial deformation. Spur gears were compacted using Ancorsteel 2000 powder under pressures of 400–700 MPa, utilizing a tapered elastic sleeve to apply radial compression. Green and sintered densities were measured, while porosity distribution was quantified via image analysis. Additionally, a 3D finite element simulation using FORGE software was conducted to model the thermo-mechanical behavior and stress distribution during the process. Experimental trials demonstrated that the elastic relaxation of the sleeve enabled free ejection of the compacts without requiring an extraction force. Image analysis confirmed a homogenous porosity distribution across the gear teeth, and higher die pre-stressing strokes were found to correlate with increased sintered density. Finite element modeling accurately predicted critical stress concentrations of 700 MPa at the die–sleeve interface and validated the strain distribution. The results confirm that elastic die technology effectively eliminates ejection friction and improves density uniformity in complex gears, offering a viable solution for reducing tool wear and manufacturing defects in high-precision powder metallurgy. Full article

This study explored the enhancement of exopolysaccharide (EPS) production by Ganoderma lucidum through bidirectional liquid fermentation, employing Clinacanthus nutans (Burm. f.) Lindau leaves as a medicinal substrate. The optimal concentration of C. nutans leaf powder was determined to be 6 g/L, resulting in a significant increase in both mycelial biomass (61.78%) and EPS yield (116.6%). Structural analyses indicated that the EPS supplemented with C. nutans underwent notable modifications. Fourier-transform infrared spectroscopy suggested the introduction of potential carbonyl groups and a shift in glycosidic linkage configuration. Monosaccharide composition analysis revealed a significant transition from a glucose-dominated profile in the control to a galactose-rich, more diverse profile, including uronic acids and amino sugars, in the experimental group. High-performance gel permeation chromatography demonstrated a transformation from a low, homogeneous molecular weight (4.7 kDa) to a heterogeneous, bimodal distribution featuring a prominent high-molecular-weight fraction (38.5 kDa). Consequently, the modified EPS exhibited significantly enhanced antioxidant activities, with scavenging rates for DPPH, hydroxyl, and ABTS radicals increasing to 55.5%, 35.1%, and 88.0%, respectively, at a concentration of 2 mg/mL. These findings demonstrate that C. nutans is an effective supplement for modulating the fermentation process of G. lucidum, not only boosting EPS production but also tailoring its structural characteristics to obtain polysaccharides with superior bioactivities, highlighting its potential in functional food and nutraceutical applications. Full article

This study aims to investigate the biochemical and functional properties of innovative curd-based products prepared by the traditional method. In this study, four samples (raw curd, curd powder, curd balls, and curd drink) were analyzed using Kjeldahl method for protein, Soxhlet for fat, atomic absorption spectrophotometry for minerals, RP-HPLC for amino acids and organic acids, SDS-PAGE and HPLC for protein fractions, DPPH assay for antioxidant activity, antibacterial assays, and laser diffraction for particle size distribution. The raw curd contained 13.96 ± 0.15 g protein, 6.77 ± 0.19 g fat, and 0.42 ± 0.05 g calcium, corresponding to 30.08 mg Ca per gram of protein. Lactic acid was the major organic acid, with concentrations ranging from 16.04 to 32.00 mg/g in curd balls and powder, respectively. The highest antioxidant activity was observed in raw material (72.3 ± 1.50% DPPH inhibition) followed by curd balls (53 ± 2.00%). Particle size analysis revealed a monomodal distribution with a median diameter (D50) of 3.7 ± 0.20 µm. Antibacterial activity was observed in non-neutralized samples, indicating pH-dependent inhibitory effects. These findings support the potential of traditionally fermented curd as a functional dairy product that preserves bioactive peptides and antioxidant properties while adapting to modern consumer demands. Full article

Erbium-165 (¹⁶⁵Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing ¹⁶⁵Er by the ^natHo(p,n)¹⁶⁵Er nuclear reaction on a 16.5 MeV medical cyclotron. The target was prepared by pressing a Ho₂O₃:Al 1:1 (w/w) powder mixture on a Ag disc with a cylindrical depression in the center. With a 0.1 mm Nb foil in front, degrading the energy to 15 MeV, and water cooling at the back of the Ag disc, the target could withstand irradiation at currents up to 45 µA without showing any signs of damage. The beam tolerance of the target was also estimated by calculating the temperature and heat dissipation in the target via the numerical solution of the heat transport equations. For a 180 mg target, the production yield was 12.3 ± 1.9 MBq/µAh. The separation of two neighboring lanthanides is challenging, which led us to study the distribution coefficients for Er and Ho on commercially available LN2 resin for both HNO₃ and HCl eluents. Based on these values, we propose a purification procedure involving two successive LN2 columns for separating the ¹⁶⁵Er from Ho and Al, followed by a small TK221 column to concentrate the final eluate. No radionuclidic impurities were detected, and the chemical impurities found in the final formulation were traces of Ho, Er, Ca, Pb, and Fe. For three different chelators (DOTA, DTPA, and CHX-A″-DTPA), the effective molar activity of the final formulation was measured. The stability of the three complexes formed was also assessed upon incubation in mouse serum for 28 h. Full article

This study examined the geopolymerization behavior of granite waste powder and reactive silica powder (GWS), utilizing granite waste powder as a sustainable precursor material, to develop an environmentally friendly substitute for Ordinary Portland cement. To obtain this objective, a total of three different mixes of calcined granite waste with reactive silica (1:1, 3:2, 7:3) were cast to evaluate the aim of this study. Due to low inherent reactivity of granite waste powder, the alkali activation was achieved using a combined solution of alkali activators consisting of 8 mol/L concentration of NaOH and Na₂SiO₃ solution at mass ratio of 1:1.2 prepared 24 h in advance to ensure complete dissolution and stabilization prior to pouring it into the GWS paste. The finest particle size distribution for optimal reactivity performance was achieved by choosing lowest median particles size from 4.0 μm–4.2 μm among all mixtures. ICP-MS analysis of granite waste and reactive silica showed the presence of silica (0.11% and 0.26% respectively) and calcium (49.61% and 38.92% respectively) content adequate for effective geopolymerization of the paste. The elemental composition, new phase formation and microstructural analysis were examined using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) techniques and Scanning Electron Microscopy (SEM) analysis. XRD analysis revealed that all GWS mixes were predominantly amorphous, with crystalline quartz, feldspar and minor α-cristobalite peaks diminishing from GWS50 to GWS70 confirming increased reactivity due to enormous reactive silica content. FTIR spectra of GWS mixes displayed characteristics of O-H (3375 cm⁻¹), H-O-H (1645 cm⁻¹), and Si-O-T (982–1000 cm⁻¹) bands, with the main Si-O-T peak shifting to higher wavenumbers from GWS50 to GWS70 due to increased GW content, indicating reduced geopolymerization effect in GWS50. SEM analysis revealed that among all mixes, GWS70 exhibited the most ideal dense matrix with increasing content of granite waste along with strong N-A-S-H gel formation. Compressive strength at 28 days increased from 11.2 MPa for GWS50 to 14.2 MPa for GWS60 and 13.8 MPa for GWS70, demonstrating that higher reactive silica powder content significantly enhanced the mechanical performance of the alkali-activated paste. These findings demonstrated that alkali-activated geopolymers of GSW offer a viable alternative to Ordinary Portland cement with optimized mixes by valorizing industrial waste and reducing reliance on high-carbon cement production. Full article

Reactive Powder Concrete (RPC) exhibits mechanical failure behaviors distinct from those of ordinary concrete. To investigate the mechanical properties and damage evolution characteristics of RPC during failure, uniaxial compression, axial compression, splitting tensile, and four-point bending tests were performed on RPC specimens integrated with Acoustic Emission (AE) technology. Subsequently, damage stage identification models were established using Random Forest (RF) and Extreme Gradient Boosting (XGBoost) algorithms coupled with AE parameters—including ringing count (RC), energy, peak frequency, RA, and AF—and were optimized via the Ivy algorithm (IVY). Results indicate that RPC demonstrated the highest ductility and resistance to failure under four-point bending, compared to its weakest performance under axial compression. By integrating the evolution of AE ringing counts and energy, the damage process was divided into three stages: compaction-elastic, crack propagation, and failure. Under axial compression, AE activity peaked before reaching the peak stress, whereas splitting tension exhibited concentrated signal bursts during crack propagation, and bending failure was characterized by a sustained signal escalation. The proportion of high-frequency signals was highest in cubic compression specimens, while splitting tension was dominated by low-frequency signals. The RA-AF distribution revealed that steel fibers inhibited through-thickness tensile cracks, and a decrease in the b-value served as a precursor to unstable failure. Notably, the IVY-optimized XGBoost model achieved the best performance, with an accuracy improvement of 26%. Under compressive stress, AF was identified as the primary parameter, whereas peak frequency became critical under tensile-bending conditions, reflecting the distinct damage mechanisms associated with different loading modes. These findings provide a scientific basis for damage assessment and early warning strategies in RPC structures. Full article

Integrating waste materials into road infrastructure is essential for environmental sustainability and resource efficiency. This study addresses the modification of short-term-aged 50/70-penetration-grade bitumen using two sustainable additives: waste toner powder and lignin. Waste toner was added at weight percentages of 4%, 8%, 12%, and 16%, while lignin was added at 15% and 20%. Since these modifiers have individual uses, this study examines how they may strengthen the oxidized binder. It focuses on extending the lifespan of the mixture by combining industrial and bio-based polymers. The main aim was to delineate the impact of these modifiers on the physical consistency, low-temperature flexibility, and microstructural morphology of the binder. The results show that both modifiers increase binder stiffness by reducing penetration at all modification rates. The resins in the waste toner enhance the polymer matrix, and the lignin’s aromatic structure increases the elastic components, improving high-temperature stability. However, ductility tests showed a reduction in elongation capability, suggesting a brittle state at lower temperatures. Also, waste toner additive is identified as the ideal modifier for high-temperature applications. SEM analysis illuminated the mechanisms underlying these performance modifications. Both additives had homogeneous distribution and good bitumen matrix interfacial bonding at lower concentrations. Full article