Search Results (1,484)

Background/Objectives: This study developed a macitentan (MAC)–tadalafil (TAD) dry powder inhalation preparation using suspension-based spray drying to enhance pulmonary delivery and reduce systemic exposure to oral combination therapy in patients with pulmonary arterial hypertension (PAH). Methods: MAC–TAD composite powders were prepared by physically mixing or spray-drying aqueous ethanol suspensions at various MAC:TAD ratios. The lead M2-T8 was co-spray-dried with 5, 25, or 50% (w/w) L-leucine. Results: Spray-dried formulations exhibited narrower and more uniform particle size distributions (Dv50 2–6 µm; Dv90~10 µm) and higher emitted dose values than the physical mixtures. In the M2-T8 spray-dried formulation, TAD exhibited an elevated fine particle dose (FPD) (3073.45 ± 1312.30 μg), demonstrating improved aerosolization relative to the physical mixture, even outperforming the TAD-higher M1-T9 formulation (2896.83 ± 531.38 μg), suggesting that favorable interparticle adhesive interactions were developed during co-drying. The incorporation of 25% L-leucine produced the greatest improvement in dispersibility, increasing the FPD by ~31% for MAC and 17% for TAD, whereas excessive L-leucine (50%) reduced the aerosol performance. Powder X-ray diffraction and differential scanning calorimetry confirmed the retention of the MAC and TAD crystallinities, with L-leucine remaining either amorphous or partially crystalline. Conclusions: Suspension-based spray drying yielded MAC–TAD composite formulations with improved uniformity and aerosol performance. The optimized 2:8 formulation containing 25% L-leucine demonstrated the most efficient pulmonary deposition, supporting its potential as an inhaled combination therapy for the treatment of PAH. Full article

This study explores the influence of precursor nature on the structural and mechanical characteristics of hydroxyapatite–yttria partially stabilized zirconia (HAp–YSZ) nanocomposites designed for biomedical applications. Precursor powders for obtaining these ceramic composites were synthesized via wet coprecipitation, using different calcium phosphate precursors: dibasic and monobasic ammonium phosphates for hydroxyapatite, and zirconyl chloride with yttrium acetate for YSZ. The dried precipitated powders were thermally treated at 600 °C and 800 °C and characterized by X-ray diffraction (XRD), thermal analysis (DTA–TG), transmission electron microscopy (TEM), and BET surface area measurements. The nanocomposites containing 70–90 wt.% HAp and 10–30 wt.% YSZ were sintered between 1000 °C and 1400 °C. Microstructural and physical properties were evaluated using scanning electron microscopy (SEM), open porosity, and compressive strength testing. Results revealed that precursor type and calcination temperature strongly affected crystallinity, particle size, and phase composition, influencing both porosity and mechanical strength of the final materials. An optimal sintering temperature of approximately 1200 °C was identified, balancing densification and phase stability. The findings demonstrate that controlling precursor chemistry and heat treatment enables fine-tuning of nanocomposite structure and performance, supporting their potential as bioactive, mechanically enhanced ceramics for orthopedic implant applications. Full article

This work investigates the effect of titanium content and the duration of mechanical alloying on the structural and phase state of powder mixtures in the Ni–Al–Ti system. The initial mixtures of Ni₆₈Al₂₅Ti₇, Ni₇₂Al₂₂Ti₆, Ni₇₀Al₂₁Ti₉, and Ni₇₅Al₂₅ were subjected to high-energy milling in a planetary ball mill for 1–6 h. It was found that the addition of titanium accelerates the dissolution of components and promotes the formation of a supersaturated fcc Ni(Al,Ti) solid solution. The most pronounced effects were observed for the Ni₇₀Al₂₁Ti₉ composition, where after 6 h of alloying, the minimum crystallite size (11.3 nm) and maximum lattice strain (1.52%) were achieved. It is shown that titanium reduces the tendency for cold welding and promotes more uniform particle refinement. The optimal conditions for synthesizing a nanocrystalline solid solution with a homogeneous structure are a titanium content of 9 at.% and a mechanical alloying duration of 6 h. The resulting powders are promising for subsequent sintering and application in structural and heat-resistant intermetallic alloys and coatings. Full article

The construction sector faces the dual challenge of reducing energy consumption and mitigating the environmental burden of construction and demolition waste (CDW). Geopolymers offer a low-carbon alternative to Portland cement, yet their performance depends strongly on precursor composition. This study presents an extensive investigation of precursor chemistry, mechanical performance and phase composition, focusing on the partial substitution of ground granulated blast furnace slag (GGBFS) with mechanically activated CDW powder (15% and 30% by weight) alongside fly ash (FA). The oxide composition, amorphous content and particle size distribution were analyzed, using XRF, XRD and laser diffraction to evaluate the reactivity. Mortar samples were subsequently synthesized and tested for compressive and flexural strength, ultrasonic pulse velocity, density and porosity. The results demonstrate that while mechanically activated CDW incorporation decreases early strength compared with GGBFS-rich systems, compressive strengths above 45 MPa were attained at 28 days, with continuous improvement to >69 MPa for aged composites. The relationship between precursor chemistry, precursor sizes and mechanical performance highlights the feasibility of CDW valorization in geopolymer binders, contributing to energy efficiency, circular economy strategies and sustainable construction materials. Full article

In this study, a W–polyethylene terephthalate glycol (PETG)-based 3D-printed composite was designed for medical radiation shielding, and syringe shielding components were fabricated to evaluate shielding performance and particle dispersion characteristics. Up to 70 wt% of tungsten powder was incorporated into the PETG polymer matrix to produce W–PETG filaments suitable for 3D printing. Using the fused deposition modeling (FDM) method, a 3.0 mm-thick radiation shielding cover for a 10 mL syringe was fabricated. Radiation shielding performance was assessed using a ^99mTc (200 µCi) source at distances of 30, 50, and 100 cm. While a conventional 1.0 mm Pb shield exhibited shielding efficiencies of 92.24%, 94.26%, and 95.13% at each distance, the 3.0 mm W–PETG shield demonstrated efficiencies of 70.67%, 75.64%, and 77.57%, respectively. Higher temperatures improved shielding efficiency by approximately 5.48 percentage points. When processed above 160 °C, tungsten particle clustering decreased and a more uniform dispersion was achieved, enhancing shielding performance. The interrelationship among filament fabrication parameters, particle dispersion behavior, and shielding performance of W–PETG composites was quantitatively demonstrated. The lightweight, geometric design flexibility, and compatibility with 3D-printing processes of W–PETG composites suggest strong potential as alternative materials for custom medical radiation shielding devices. Full article

Aluminum nitride (AlN) possesses an exceptional combination of high thermal conductivity and an ultra-wide band gap, rendering it highly attractive for electronic packaging and semiconductor substrate applications. In this study, surface chemical modification of AlN powders was performed employing low-molecular-weight organic acids, successfully yielding hydrolysis-resistant AlN powders. The underlying mechanisms responsible for the improved anti-hydrolysis performance imparted by both single organic acids and the composite acid were systematically investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM), characterization techniques. The results reveal that Oxalic acid within the concentration range of 0.25 M to 1.50 M partially inhibits the hydrolysis of aluminum nitride (AlN); however, hydrolysis products such as aluminum hydroxide are still formed. In the case of citric acid, a higher concentration leads to a stronger anti-hydrolysis effect on the modified AlN. No significant hydrolysis products were detected when the AlN sample was treated in a 1 M aqueous citric acid solution at 80 °C. The effectiveness of the organic acids in enhancing the hydrolysis resistance of AlN follows the order: composite acid (citric acid + oxalic acid) > citric acid > oxalic acid. Under the action of the composite acid, the AlN diffraction peaks exhibit the highest intensity. Furthermore, TEM observations reveal the formation of an amorphous protective layer on the surface, which contributes to the improved hydrolysis resistance. Analytical results confirmed that the surface modification process, mediated by citric acid, oxalic acid, or the composite acid, involved an esterification-like reaction between the surface hydroxyl groups on AlN and the chemical modifiers. This reaction led to the formation of a continuous protective coordination layer encapsulating the AlN particles, which serves as an effective diffusion barrier against water molecules, thereby significantly inhibiting the hydrolysis reaction. Full article

This research examined the development and testing of hot-melt adhesives incorporating metallic (Al and Fe powders averaging 800 nm) and ferrite additives, designed for reversible bonding technology of polyolefins through electromagnetic energy. The experimental models with Al displayed smooth particles that were fairly evenly distributed within the polymer matrix. Experimental models with Fe suggested that Fe nanopowders are more difficult to disperse within the polymer matrix, frequently resulting in agglomeration. For ferrite powder, there were fewer agglomerations noticed, and the dispersion was more uniform compared to similar composites containing Fe particles. Regarding water absorption, the extent of swelling was greater in the composites that included Al. Because of toluene’s affinity for the matrices, the swelling measurements stayed elevated even with reduced exposure times, and the composites with ferrite showed the lowest swelling compared to those with metallic particles. A remarkable evolution of the dielectric loss factor peak shifting towards higher frequencies with rising temperatures was observed, which is particularly important when the materials are exposed to thermal activation through electromagnetic energy. The reversible bonding experiments were performed on polyolefin samples which were connected longitudinally by overlapping at the ends; specialized hot-melts were employed, using electromagnetic energy at 2.45 GHz, with power levels between 140 and 850 × 10³ W/kg and an exposure duration of up to 2 min. The feasibility of bonding polyolefins using homologous hot-melts that include metallic/ferrite elements was verified. Composites with both matrices showed that the hot-melts with Al displayed the highest mechanical tensile strength values, but also had a relatively greater elongation. All created hot-melts were suitable for reversible adhesion of similar polyolefins, with the one based on HDPE and Fe considered the most efficient for bonding HDPE, and the one based on PP and Al for PP bonding. When bonding dissimilar polyolefins, it seems that the technique is only effective with hot-melts that include Al. According to the reversible bonding diagrams for specific substrates and hot-melt combinations, and considering the optimization of energy consumption in relation to productivity, the most cost-effective way is to utilize 850 × 10³ W/kg power with a maximum exposure time of 1 min. Full article

Liquid gallium (Ga) enables low-temperature transient liquid phase bonding (TLPB), but optimizing microstructure and joint performance remains challenging. Here, we developed a copper (Cu)-powder/liquid-Ga composite paste for Cu/Cu interconnects and systematically studied the effects on the interconnect joint performance of Cu powder particle size (Cu_PS, 10–20, 20–30 and 30–40 μm) and Cu mass fraction (Cu_MF, 10–30 wt%). The microstructure, electrical conductivity, and shear strength of the joint were evaluated, followed by an assessment of bonding temperature, pressure, and time. Under bonding conditions of 220 °C, 5 MPa and 720 min, a dense intermetallic compound (IMC) microstructure predominantly composed of Cu₉Ga₄ and CuGa₂ was formed, yielding an electrical conductivity of approximately 1.1 × 10⁷  S·m⁻¹ and a shear strength of 52.2 MPa, thereby achieving a synergistic optimization of electrical and mechanical properties; even under rapid bonding conditions of 220 °C, 5 MPa and 1 min, the joint still attained a shear strength of 39.2 MPa, demonstrating the potential of this process for high-efficiency, short-time interconnection applications. These results show that adjusting the composite paste formulation and dosage enables Cu–Ga TLPB joints that combine high conductivity with robust mechanical integrity for advanced packaging. Full article

Al₂O₃-TiC/6061Al composites were fabricated via in situ powder metallurgy using 6061 Al, TiO₂, and graphite powders as starting materials. The effects of sintering temperature and ceramic particle content on the microstructure and mechanical properties of the composites were investigated. The wear performance of composites sintered at 1200 °C with varying ceramic particle content was also examined. The results indicate that the microstructure of the composite varied with the sintering temperature. At 1000 °C and 1100 °C, the microstructure primarily consisted of Al₃Ti, Al₂O₃, and TiC phases. At 1200 °C and 1250 °C, the microstructure was predominantly composed of Al₂O₃ and TiC phases. The 6061 Al-12% (TiO₂ + C) composite sintered at 1200 °C exhibited a tensile strength of 246 MPa, an elongation of 12.7%, and a microhardness of 104.2 HV_0.1. Regarding wear performance, the wear behavior of the composites under different loads at 1200 °C was studied. Under a 30 N load, the 6061 Al-12% (TiO₂ + C) composite demonstrated the lowest friction coefficient and wear rate, measured at 0.253 and 0.396 mm³·N⁻¹·m⁻¹, respectively. Analysis of the worn surface morphology under a 30 N load indicates that the dominant wear mechanism for the 6061 aluminum alloy is delamination wear, whereas for the 6061 Al-12% (TiO₂ + C) composite, it is primarily abrasive wear. Full article

Cementitious materials prepared by the ice-templating method appear to have difficulty simultaneously possessing good mechanical properties and an oriented microstructure with microchannels. Surface micro-ceramicization of TiB₂ and the decomposed products of cement hydrates at high temperatures can be regarded as in situ solid–solid reactions involving oxygen, thereby enhancing mechanical properties. This study investigates the mechanical property changes in cement paste with different water-to-cement ratios containing 25% TiB₂ micron powder before and after high-temperature treatment. Cementitious samples are prepared using both freeze-casting (F-CAST) and regular casting (R-CAST) methods with and without the heating post-treatment. The average compressive strength of samples with a W/C of 0.65 prepared by the freeze-casting method at −60 °C with a heating post-treatment is much larger than that of samples prepared by the regular casting method with and without the same heating process. The freeze-casting process for preparing cementitious composites with TiB₂ not only reorders the distribution of water molecules but also redistributes the concentrations of the TiB₂ particles and the main hydrates in the frozen samples. Due to the concentration increase near ice crystal channels within the samples, led by the freeze concentration effect, the new products are formed and cover the channel surfaces after high-temperature treatment. This enhances both the overall and internal properties of the cement-based TiB₂ composite material. The variation in TiB₂ content within the specimens is of paramount importance. Full article

Constipation is a global health issue, with a prevalence of approximately 16%, and insufficient dietary fiber intake is a major contributing factor. Citrus peel residue contains a high proportion of dietary fiber, accounting for about 20–44% of its composition. In this study, the constipation-relieving effects of three functional components derived from citrus peel residue—cellulose (CEL), pectin (PEC), and citrus peel powder (CPP)—were systematically compared using a loperamide-induced mouse model. All groups were administered an equivalent dose of 200 mg/kg daily. The results showed that supplementation with CEL, PEC, and CPP improved defecation parameters. Among these, PEC effectively modulated the SCF/C-kit and Nrf2/HO-1 pathways. Compared with the model group, PEC increased Akkermansia abundance by approximately 34% and reduced Desulfovibrio abundance by about 26% Additionally, the smaller particle size and improved solubility of PEC promote the production of beneficial metabolites, thereby alleviating constipation. In contrast, CEL primarily alleviates constipation through its physical properties. At equivalent doses, CPP provides less constipation relief due to its lower component concentrations and a primary composition of insoluble dietary fiber. These findings provide preliminary mechanistic insights and support further exploration of citrus by-products as functional food candidates for the management of constipation. Full article

Metal-organic frameworks (MOFs) offer high porosity for water remediation but face challenges in handling as powders. We address these limitations by physically immobilizing Fe–BTC MOF within calcium-crosslinked low-methoxyl pectin matrices (PE–Ca–MOF). Solvent-cast films and freeze-dried foams were fabricated using water-based and polyvinylpyrrolidone (PVP)-assisted Fe–BTC dispersions, preserving MOF and pectin structures confirmed by FT–IR. PVP improved Fe–BTC dispersion and reduced particle size, enhancing distribution and plasticizing the matrix proved by DSC. Incorporation of water-dispersed Fe–BTC increased the equilibrium adsorption capacity but reduced the initial adsorption rate, while the PVP-assisted foam further enhanced uptake in comparative batch tests through its more open porous structure. At pH 7, PE–Ca–5%MOF films showed high adsorption capacities and removal efficiencies for paraquat (35.5 mg/g, 70.6%) and tetracycline (14.5 mg/g, 46.8%), while maintaining Zn²⁺ uptake compared to calcium-pectin films without MOF. Adsorption followed pseudo-first-order kinetics and Langmuir isotherms. Green regeneration with acetic acid enabled >80% capacity retention over five adsorption–desorption cycles. Foam architectures increased porosity and active-site accessibility (SEM), improving performance even at lower MOF loadings. Overall, controlling MOF dispersion and composite morphology enables efficient, reusable, and environmentally friendly bio-based adsorbents for water purification. Full article

This research reports the development of photocatalytic active composites for hydrogen evolution obtained through high-energy mechanical milling of a mixture of the organic semiconductor g-C₃N₄ (CN) and the metal–organic framework ZIF-67. These composites, called CNZ-x (X = mass proportion of ZIF-67), were characterized using powder XRD, which showed that the crystalline phases of both the g-C₃N₄ and ZIF-67 precursors are present in the composites. SEM was used to determine the morphology, revealing that the ZIF-67 octahedral particles adhere to the surface of the CN sheets due to the intimate interfacial contact induced by high-energy mechanical grinding. The results of the photocatalytic evolution of H₂ indicate that the CNZ-50 composite produced 261 μmol g⁻¹ of H₂, which is higher than the 229.5 and 124 μmol g⁻¹ produced by the precursors ZIF-67 and CN, respectively. The higher efficiency in H₂ evolution is due to the composite having better electron-hole separation than the precursor materials. Full article

This study reports the fabrication and characterization of copper–silicon carbide (Cu–SiC) metal matrix composites produced using powder metallurgy (PM) combined with thermo-compression processing (TCP), a dual route that remains limited in Cu–SiC research. Micro-sized SiC particles (1–25 wt.%) were incorporated into Cu, compacted, sintered, and subsequently subjected to sequential forging and annealing. Unlike conventional PM-only processing, TCP significantly reduced porosity, promoted more uniform reinforcement dispersion, and relieved residual stresses, creating a strong synergy between densification and microstructural refinement. SEM, EDS, XRD, and Raman analyses confirmed phase stability, homogeneous reinforcement distribution, and the absence of deleterious interfacial phases. The integrated PM + TCP route achieved an ultimate tensile strength of ~209 MPa, hardness of ~65 HRB, and toughness of ~35 MJ/m³ at approximately 3 wt.% SiC. The superior performance at this composition resulted not from the lowest porosity but from the combined effects of uniform particle dispersion, improved particle–matrix bonding, and deformation-driven refinement. These findings establish TCP as an effective post-sintering strategy that overcomes intrinsic porosity and interfacial limitations in Cu–SiC composites. Overall, powder metallurgy combined with the thermo-compression processing is identified as a promising processing pathway for developing high-strength, thermally stable Cu–SiC materials for structural and thermal management applications. Full article

This study presents a comprehensive investigation of turbidity monitoring using two different types of polymer optical fiber (POF) sensors: the reflection–refraction type (RR-POF) and the gap type (Gap-POF). Both sensors were used to visualize and monitor the turbidity changes in suspensions with varying concentrations and different particle compositions, namely silica powder and clay particles. The experiments were conducted by introducing silica powder and clay into water at various concentrations, and the resulting turbidity was measured using both types of POF sensors. The results revealed a significant correlation between particle concentration and light intensity for both kinds of POF sensors. As the particle concentration increased, the light intensity decreased due to increased scattering and absorption effects. For both silica powder and clay suspensions, the light intensity stabilized at lower values as the concentration increased, with the Gap-POF sensor exhibiting higher sensitivity to turbidity changes, particularly at high particle concentrations. Additionally, the study found that the particle composition influenced the sensor response. Silica powder particles caused more irregular fluctuations in light intensity at higher concentrations due to their larger particle size and tendency to aggregate, while clay particles, due to their smaller size and better dispersion, resulted in more stable and gradual changes in light intensity. This highlighted the differences in optical responses between different particle types. Furthermore, the multi-wavelength measurements showed consistent results, with white and green lights exhibiting the strongest response to turbidity changes, while red and blue lights were less sensitive. This wavelength-dependent response was attributed to the scattering and absorption properties of the particles in the suspensions. Both RR-POF and Gap-POF sensors proved to be effective for turbidity monitoring, with Gap-POF demonstrating superior performance in high-concentration suspensions. The findings suggest that POF sensors, particularly Gap-POF, are highly suitable for real-time turbidity monitoring in various particle suspension systems. Full article