Search Results (5,772)

Multifunctional polymer–ferrite composites based on poly(vinylidene fluoride) (PVDF) and magnetic fillers are of increasing interest for applications requiring coupled electrical, dielectric, and magnetic responses. However, the relationship between magnetic filler concentration, PVDF phase composition, and the resulting multifunctional properties remains insufficiently understood. In this work, PVDF/BaFe₁₂O₁₉ (PVDF/BaF) composite membranes containing 2–20 wt.% BaF were fabricated using a combined non-solvent and thermally induced phase-inversion (NIPS–TIPS) method. Structural evolution was analyzed by X-ray diffraction and quantitative FTIR spectroscopy, thermal behavior by differential scanning calorimetry, optical properties by diffuse reflectance spectroscopy, dielectric response in the frequency range 10³–10⁶ Hz, and magnetic characteristics by vibrating sample magnetometry. At moderate filler concentrations (2–10 wt.%), BaFe₁₂O₁₉ nanoparticles acted as effective β-phase nucleating centers, leading to electroactive phase fractions of 97.7–99.9% and a maximum β-phase content of 86.7% for PVDF/BaF10. At higher loadings (15–20 wt.%), particle agglomeration and restricted chain mobility promoted a transition toward α-phase-dominated crystallization. Thermal analysis indicated competing nucleation and confined crystallization processes, while optical and dielectric measurements revealed nonmonotonic changes associated with interfacial interactions and Maxwell–Wagner–Sillars polarization. Magnetic measurements showed a linear increase in saturation magnetization with filler concentration and a nonmonotonic coercivity dependence with a pronounced change near the critical agglomeration concentration. These results demonstrate that the multifunctional response of PVDF/BaFe₁₂O₁₉ membranes is governed by the interplay between β-phase nucleation, interfacial polarization, and magnetic particle interactions, with approximately 10 wt.% ferrite providing the most balanced electrical, dielectric, and magnetic characteristics. Full article

This study investigates the mechanical, structural, and thermal performance of bio-based composite laminates reinforced with nonwoven fibrous materials derived from polylactic acid (PLA), poly(butylene succinate) (PBS), and polyamide 1010 (PA1010). The fibrous reinforcements, produced using melt-blown and electrospinning techniques, were characterized in terms of morphology, fibre diameter distribution, and wettability, and subsequently incorporated into bio-resin laminates to strengthen them. The curing behaviour of the composites was evaluated using differential scanning calorimetry (DSC). The results demonstrate that fibre structure and morphology strongly influence resin impregnation and interfacial interactions. Mechanical properties varied significantly depending on the reinforcement type. PA1010-based laminates exhibited the highest strength and stiffness due to their compact and uniform fibrous structure. PBS-based systems showed intermediate behaviour, while PLA-based composites displayed lower strength but higher deformability. DSC results indicated that fibre type affected crosslinking efficiency. Thermogravimetric analysis (TGA) revealed similar initial thermal stability of laminates (T₅% ≈ 299–313 °C), governed by the resin matrix, while differences at higher temperatures reflected the type of reinforcement used. These findings highlight the importance of fibre morphology and interfacial compatibility in designing sustainable composite laminates reinforced with recycled fibrous materials. Full article

Background: Baicalein (BA) is a poorly soluble flavonoid with limited oral bioavailability. This study aimed to enhance the solubility and nasal absorption of the compound using a dual-carrier system that combines cyclodextrin inclusion complexes and thermosensitive hydrogels. Methods: The inclusion complexes of BA with hydroxypropyl-β-cyclodextrin (HP-β-CD) or sulfobutyl-β-cyclodextrin (SBE-β-CD), namely BA-HP-β-CD and BA-SBE-β-CD, were prepared via solution stirring and characterized by solubility, dissolution, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-differential scanning calorimetry (TG-DSC), and Madin-Darby canine kidney (MDCK) cell permeation. The optimal complexes were incorporated into chitosan/β-glycerophosphate thermosensitive hydrogels (BA/HP-Gel and BA/SBE-Gel), followed by evaluations of gelation properties, in vitro release, and in vivo pharmacokinetics in rats. Results: The water solubility of BA-HP-β-CD and BA-SBE-β-CD increased 572 and 582 times, with MDCK permeability enhanced by 5.3 and 2.9 times, respectively. Both hydrogels showed rapid solution-gel transition at nasal temperature and sustained release. Following intranasal administration, BA/HP-Gel and BA/SBE-Gel achieved relative bioavailabilities of 623.5% and 697.8%, respectively, compared with BA-Gel. Conclusions: The dual-carrier platform effectively improved BA solubility, permeability, and nasal bioavailability, offering a promising strategy for nasal delivery of poorly soluble drugs. Full article

This study examines the influence of scale effects on the thermomechanical and structural performance of chemically cured, glass-fibre-reinforced polyester composites. Two reinforcement architectures—plain 0/90° fabric and biaxial fabric—were analysed to assess differences in resin flow, curing behaviour, and mechanical characteristics. Differential Scanning Calorimetry (DSC) was employed to characterise cross-linking kinetics at 15 °C, 19 °C, and 25 °C, demonstrating that higher cure temperatures markedly accelerate gelation and cross-linking. Composite plates were manufactured by Light Resin Transfer Moulding (L-RTM), and static tensile tests were conducted in accordance with PN-EN ISO 527-4. The results confirm that reinforcement architecture strongly affects processability and mechanical performance. The 0/90° fabric provided superior resin permeability and shorter infusion times, whereas the biaxial fabric required higher injection pressure and exhibited longer curing duration. Statistical analysis based on Weibull’s brittle strength theory verified the presence of scale effects: larger specimens displayed lower nominal strength due to a higher probability of internal flaws. Multiple regression modelling further revealed relationships between geometric and mechanical parameters: maximum (destructive) stress, Rm, was the dominant factor influencing both specimen thickness and number of layers, while deformation at maximum stress (εm) primarily determined specimen length. These findings highlight the necessity of accounting for size-dependent behaviour when designing and testing polymer composites. Considering scale effects enables more reliable extrapolation from laboratory-scale tests to full-scale components, thereby improving predictability and structural reliability in engineering applications. Full article

Polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) films plasticized with glycerin or polyethylene glycol (PEG) were investigated to elucidate structure–property relationships in hydrophilic polymeric film systems. Films were prepared by solution casting at a fixed polymer concentration of 2.7% w/w with plasticizer contents ranging from 0.49 to 1.33% w/w, yielding continuous, free-standing films with good surface integrity. Polymer type and plasticizer dosage strongly affected film breakdown behavior. HPMC films with high plasticization swelled and disintegrated. Effective plasticization was shown by a steady drop in tensile strength and elastic modulus and a significant rise in elongation at break. PVA films plasticized better than HPMC films in PEG-containing solutions. Fourier transform infrared spectroscopy verified hydrogen bonding-driven polymer–plasticizer interactions, with glycerin outperforming PEG. Increasing plasticizer percentage reduced crystallographic order and thermal transition temperature in X-ray diffraction and differential scanning calorimetry. Scanning electron microscopy indicated smooth and uniform surfaces at intermediate plasticizer levels, but variability at higher loadings. Among the studied formulations, PVA films containing 1.33% w/w plasticizer and HPMC films containing 1.05% w/w plasticizer provided the most balanced combination. These findings support physiochemically rational PVA and HPMC film design for pharmaceutical applications. Full article

Beyond gas transport, red blood cells (RBCs) have emerging roles regarding innate immunity, regulating blood flow, and participating in nutrient transport, which can be engineered as drug delivery systems since they contribute to maintaining water homeostasis. Following extensive thermoanalytical studies of human blood plasma, our working group investigated the properties of RBCs, examining their role in healthy and in different disease states by using differential scanning calorimetry (DSC) and the deconvolution of the resulting thermal curve. In the first study, guinea pigs were treated with intraperitoneal chemotherapy. Cyclophosphamide treatment showed a dose-dependent difference between the thermal parameters of control and treated samples, indicating that DSC can be used in this area. Following deconvolution of the DSC studies, the changes can be attributed to the damaged compounds. In the second part of our study, a method for the thermal analysis and deconvolution of RBCs in patients with lower limb ischemia during a three-month cilostazol treatment was developed. The control DSC curve showed 5-6 distinct thermal domains, and in contrast to other drug treatments, this remained stable throughout the entire study period. No effects of stiffness or compact were caused by the anticancer drug cyclophosphamide were observed in the structure of RBCs. These preliminary results highlight the uniqueness of thermodynamic studies of RBCs and provide a fingerprint-like identification of a given individual or disease state. Full article

Conventional thermal recovery techniques face challenges in low-permeability heavy oil reservoirs due to low recovery factors and poor economic viability. To address these challenges, low-temperature oxidation (LTO) during oxygen-reduced air flooding was employed to achieve in situ oil upgrading and enhance oil recovery. Static oxidation tests at oxygen concentrations of 5%, 10%, 15%, and 21% were designed to analyze the produced gas composition and the physical properties of the oil following oxidation. We further employed Differential Scanning Calorimetry (DSC) and Thermogravimetric (TG) analysis to evaluate the oxidation behavior of crude oil under the same oxygen concentration conditions. Finally, long-core displacement experiments were performed to assess how the oxygen concentration influences the recovery efficiency. The results showed that under the tested conditions, oxygen consumption exceeded CO₂ generation, indicating that low-temperature oxygen addition reactions (formation of oxygenated species) dominated over complete oxidation. As the oxygen concentration increased, the oxidized crude oil exhibited a higher viscosity. At higher oxygen concentrations (15% and 21%), the asphaltene content increased significantly, resulting in poorer fluidity. The activation energy in the LTO stage decreased with increasing oxygen concentration, as revealed by kinetic analysis over the range of 5% to 21%. The LTO stage dominated the crude oil oxidation process. However, the heat release during this stage was less affected by the oxygen concentration. Consequently, increasing the oxygen concentration contributed only marginally to elevating the reservoir temperature. For the studied reservoir, oxygen-reduced air flooding with a 5% oxygen concentration achieved a final recovery factor of 34.82%. This represented a 1.76% improvement over conventional air flooding, thereby enabling economically efficient reservoir development. Full article

This study addresses a persistent challenge in polymer joining: the laser welding of two incompatible thermoplastics, polypropylene (PP) and high-density polyethylene (HDPE). The key innovation lies in modifying HDPE with 3 wt% graphene nanoplatelets (GNPs) via material extrusion (MEX), which raises its melting temperature from 136.8 °C to 138.8 °C and increases crystallinity from 46.9% to 51.4%, as confirmed by differential scanning calorimetry (DSC). This thermal adjustment brings HDPE closer to PP’s melting behavior, enabling effective laser butt welding using a pulsed CO₂ laser. A Box–Behnken design within response surface methodology (RSM) was employed to model the individual and interactive effects of laser power (30–50 W), welding speed (15–25 mm/s), and pulse frequency (25–35 Hz) on the flexural and impact strength of the welded joints. Scanning electron microscopy (SEM) revealed that optimal welding conditions—laser power of 49 W, welding speed of 20 mm/s, and pulse frequency of 35 Hz—produce a defect-free interface with complete polymer chain interdiffusion. Under these optimized conditions, the regression models predicted a flexural strength of 69.7 MPa and an impact strength of 21.9 kJ/m². Confirmation experiments yielded 68.2 MPa and 22.6 kJ/m², with relative errors below 4%, validating the predictive capability of the models. This work demonstrates that GNP-mediated thermal property modification, coupled with statistical process optimization, offers a viable pathway for manufacturing high-performance dissimilar polymer joints for lightweight structural applications. Full article

Objective: Developing foundational biomaterial platforms for cultured meat research requires 3D co-culture systems capable of supporting multiple relevant cell types in a spatially organized manner. This study aimed to establish a compartmentalized tri-culture hydrogel disc incorporating a lipid-containing barrier phase as a proof-of-concept in vitro model. Methods: Beeswax/alginate (Bw/Algi) hydrogels were fabricated and evaluated for morphology and cytocompatibility as a lipid-containing scaffold component. Fucoidan/alginate (Fu/Algi) hydrogels were prepared at varying fucoidan concentrations and screened to identify conditions compatible with C2C12 viability and early-stage differentiation. A composite beeswax/fucoidan/alginate disc (Bw/Fu/Algi) was then assembled by casting cell-laden Fu/Algi regions (myoblasts, fibroblasts, and endothelial cells), separated by Bw/Algi barrier layers and ionically crosslinked with CaCl₂. Scaffold performance was assessed using standard assays for morphology, cytocompatibility, myogenic marker expression, protein production, and thermal stability. Results: Bw/Algi supported cytocompatible C2C12 attachment and growth, while Fu/Algi exhibited concentration-dependent effects on myogenic marker expression, enabling selection of an optimized fucoidan concentration for 3D assembly. The final Bw/Fu/Algi disc maintained viable compartmentalized tri-culture and supported indirect co-culture through spatial separation by the Bw barrier. Myogenic regions exhibited myogenic marker expression with measurable protein production, and differential scanning calorimetry confirmed structural stability under heating. Conclusion: This work establishes a Bw/Fu/Algi tri-culture disc integrating a lipid-containing barrier component with hydrogel-based myogenic compartments, providing a preliminary platform for multicellular in vitro modeling and scaffold design relevant to cultured meat research. Full article

High-amylose rice starch (HARS) complexation with fatty acids and emulsifiers was evaluated using differential scanning calorimetry (DSC), Rapid Visco Analyzer (RVA) pasting, X-ray diffraction (XRD), and in vitro digestibility. DSC confirmed amylose–lipid complex formation for both additive types, with emulsifiers more effective than fatty acids. Lysolecithin produced the largest amylose–lipid complex endotherm with no detectable uncomplexed melting peak. Complexation increased up to 2.5% (w/w) and then plateaued, accompanied by a reduced gelatinization endotherm. Fatty-acid effects depended on chain length and included overlapping melting from uncomplexed lipids; higher additive levels generally increased complex stability. RVA results indicated that emulsifiers, but not fatty acids, increased pasting temperature by approximately 10 °C and delayed pasting. Lysolecithin markedly reduced viscosity breakdown, suggesting restricted granule swelling due to stabilized complexes. Myristic acid and lysolecithin caused the greatest changes in thermal and pasting parameters. XRD patterns shifted from mixed A + V to predominantly V-type reflections, confirming V-amylose complex formation. In vitro digestion showed decreases of 7.5–15.8% in rapidly digestible starch and increases of 4.7–12.3% in slowly digestible starch and 2.4–39.5% in resistant starch, with the strongest effects for lysolecithin (and myristic acid). These results support emulsifier-assisted production of RS5 from HARS, enhancing its utilization. Full article

Oxyresveratrol (Oxy) exhibits a diverse range of biological activities. However, its practical application is constrained by low aqueous solubility and chemical instability. In this work, Oxy-loaded zein (Z) nanoparticles (NPs) stabilized by a sodium alginate (Alg) coating (Oxy-Z/Alg NPs) were fabricated using an antisolvent precipitation method. The absence of crystalline peaks in X-ray diffraction analysis suggested that Oxy was dispersed as an amorphous phase in NPs, while the Fourier transform infrared spectra identified strong interfacial associations between the components. The stabilization of the NPs is attributed to the site-specific binding of Oxy with Z’s SER-162 and GLN-174 residues. Molecular docking, molecular dynamics simulations, and differential scanning calorimetry profiles evidenced the formation of intermolecular hydrogen bonds. Dynamic light scattering analysis showed that the nanocomplexes had a nano-scale dimension (243 ± 6 nm) and a zeta potential of −36 mV. SEM micrographs revealed that the NPs possessed a spherical morphology. The NPs exhibited colloidal stability against prolonged heating (80 °C for 75 min), ionic strengths (up to 100 mM NaCl), and pH range (2.0–10.0). Encapsulation within the Alg coating enhanced Oxy’s antioxidant capacity over its unprotected form by shielding its core bioactivity from degradation. The Oxy-Z/Alg nano-system shows significant promise for the encapsulation of Oxy, providing a practical basis for its integration into nutraceuticals and functional food fields. Full article

This study investigates the feasibility of incorporating wood-based waste in cementitious composites for extrusion-based three-dimensional (3D) printing through the production of artificial aggregates. Because lignocellulosic residues can retard cement hydration, wood dust was chemically modified with a calcium nitrate-based accelerator and granulated into aggregates using disc granulation. The resulting aggregates were characterized for mechanical robustness, and their influence on cement hydration and microstructural development was evaluated using X-ray diffraction (XRD) and thermogravimetric/differential scanning calorimetry (TG/DSC). The modified aggregates were then incorporated into 3D printable cementitious mixtures to assess fresh-state properties, printability, and mechanical performance. The accelerator affected hydration by increasing bound water content and altering the development of hydration products. The produced aggregates exhibited sufficient crushing resistance for practical handling. The incorporation of artificial aggregates resulted in reduced compressive and flexural strengths compared to the reference mixture. However, the differences between mechanical properties measured in different loading directions were reduced, indicating a more uniform structural response in printed elements. The findings demonstrate that chemically treated wood-based aggregates can be successfully integrated into 3D printable cementitious systems, offering a promising pathway toward more sustainable construction materials. Full article

Kefiran is a bioactive exopolysaccharide produced by kefir grains, whose synthesis is strongly influenced by culture medium composition. In this study, cheese whey was evaluated as an alternative fermentation substrate for kefiran production, and the effect of supplementation with fermentable sugars (glucose, galactose, and lactose) and casein was assessed under controlled conditions. Kefir grains were cultivated in whey- and milk-based media, and kefiran production was quantified using an anthrone-based method, while grain growth and carbohydrate consumption were monitored. Supplementation with sugars and casein reduced kefiran production by up to 34.6% and did not improve yield, whereas unsupplemented whey supported the highest kefiran concentration (86.9 ± 3.7 mg/L), comparable to that obtained in semi-skimmed milk (84.0 ± 3.0 mg/L). The recovered polysaccharide was characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹H NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), showing structural and physicochemical properties comparable to kefiran obtained from semi-skimmed milk. These results indicate that whey constitutes a feasible and simple fermentation medium for kefiran production, and that increased medium complexity does not necessarily improve process performance. Full article

The present work investigates the composition-dependent thermoresistive behavior of polylactic acid/polycaprolactone (PLA/PCL) composites reinforced with 4 wt.% graphene nanoplatelets (GNP), prepared by twin-screw extrusion at PLA/PCL ratios of 95/5, 70/30, 60/40, and 30/70 wt.%/wt.%. Their morphology, thermal properties, and structure were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. Thermoresistive measurements over four cycles (30–130 °C) revealed two distinct regimes: PLA-rich compositions exhibited a stable, monotonic positive temperature coefficient (PTC) response after the first conditioning cycle, with TCR values up to 0.38% °C⁻¹, whereas compositions with 40–70 wt.% PCL displayed a non-monotonic PTC-to-NTC transition linked to PCL melting and subsequent conductive network rearrangement. The magnitude of both PTC and NTC responses increased systematically with PCL content. These results demonstrate that the thermoresistive characteristics of biodegradable PLA/PCL/GNP composites, including the sign, magnitude, and switching temperature of the TCR, can be effectively tuned through blend composition, offering a practical route for designing thermally responsive sensing materials. Full article

This study investigates the effect of cold rolling on precipitation behavior and mechanical properties in a pre-aged Al–Mg–Si–Cu alloy. Following pre-aging at 35 °C, samples were subjected to various cold-rolling reductions (0–80%) and subsequently aged at 160 °C. Hardness measurements reveal that increasing deformation significantly enhances peak hardness and accelerates aging kinetics, with the 80% cold-rolled sample reaching peak hardness within 6 h compared to 1 week for the undeformed condition. Differential scanning calorimetry (DSC) analysis shows that all precipitation peaks shift to lower temperatures with increasing level of deformation, accompanied by a reduction in activation energy and narrowing of the full width at half-maximum, indicating accelerated precipitation reactions. Transmission electron microscopy (TEM) observations demonstrate that cold rolling introduces a high density of dislocations, which act as preferential nucleation sites for precipitates. As a result, a refined and more uniform distribution of nanoscale precipitates is obtained, with increasing number density and decreasing size at higher deformation levels. The combined results indicate that deformation-induced dislocations play a critical role in modifying precipitation pathways, promoting rapid formation of metastable phases, and enhancing the overall strengthening response of the alloy. Full article