Search Results (10,783)

The utilization of encapsulated biopharmaceuticals, including peptides and proteins, has grown substantially in recent years. In this study, the influence of aliphatic polyester physicochemical properties, specifically crystallinity and hydrophobicity, on the development of protein-loaded microparticles was investigated. A series of polyesters, namely amorphous PDLLA and semicrystalline PLLA, PCL, and PPDL, were synthesized via chemical and enzymatic ring-opening polymerization. Bovine serum albumin (BSA)-loaded microparticles were fabricated using a water-in-oil-in-water (w/o/w) double emulsion solvent evaporation method. The size of microparticles obtained was determined by scanning electron microscopy and dynamic light scattering methods. The enzymatic degradation of the polymer microparticles was assessed through incubation in a lipase-containing buffer solution. BSA and α-chymotrypsin (ACHT) were used as model proteins for the preparation of encapsulated polymer microspheres and comparison of their characteristics and properties. Protein encapsulation efficacy, release rate, and enzyme activity retained after encapsulation were evaluated and compared for selected aliphatic polyesters. The release profiles were processed with the use of various mathematical models to reveal the possible mechanism(s) of protein release. Full article

Gelatin is a collagen-derived biopolymer widely used in food, pharmaceutical and biomedical applications due to its biocompatibility and gelling ability. However, gelatin hydrogels suffer from unstable mechanical strength, limited thermal resistance and susceptibility to microbial contamination. The main aim of the present study is to investigate the influence of gelatin cryostructuring followed by photo-induced menadione sodium bisulfite (MSB) chemical crosslinking on the structural and functional characteristics of mammalian and fish gelatin hydrogels. The integration of scanning electron microscopy, dielectric spectroscopy and rheological experiments provides a comprehensive view of the of molecular, morphological and mechanical properties of gelatin hydrogels under photo-induced chemical crosslinking. The SEM results revealed that crosslinked hydrogels are characterized by enlarged pores compared to non-crosslinked systems. For mammalian gelatin, multiple pores with thin partitions are formed, giving a dense and stable polymer network. For fish gelatin, large oval pores with thickened partitions are formed, preserving a less stable ordered architecture. Rheological data show strong reinforcement of the elastic and thermal stability of mammalian gelatin. The crosslinked mammalian system maintains the gel state at higher temperatures. Fish gelatin exhibits reduced elasticity retention even after crosslinking because of a different amino acid composition. Dielectric results show that crosslinking increases the portion of bound water in hydrogels considerably, but for fish gelatin, bound water is more mobile, which may explain weaker mechanical properties. Full article

Titanium and its alloys are widely used in biomedical implants due to their favorable mechanical properties and corrosion resistance; however, their natural surface lacks sufficient bioactivity and antibacterial performance. Micro-arc oxidation is a promising approach to producing bioactive coatings, and the incorporation of nanoparticles such as TiO₂ may further improve their functionality. This study aimed to determine the optimal TiO₂ nanoparticle concentration in the micro-arc oxidation electrolyte that ensures coating stability and biological safety. Calcium–phosphate coatings were fabricated on commercially pure titanium using micro-arc oxidation with two TiO₂ concentrations: 0.5 wt.% (MAO 1) and 1 wt.% (MAO 2). Surface morphology, porosity, and phase composition were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. Corrosion resistance was evaluated via potentiodynamic polarization in NaCl and Ringer’s solutions, while biocompatibility was assessed in vitro using HOS human osteosarcoma cells and MTT assays. Increasing the TiO₂ content to 1% decreased coating porosity (13.7% vs. 26.3% for MAO 1), enhanced corrosion protection, and reduced the friction coefficient compared to bare titanium. However, MAO 2 exhibited high cytotoxicity (81% cell death) and partial structural degradation in the biological medium. MAO 1 maintained integrity and showed no toxic effects (3% cell death). These results suggest that 0.5% TiO₂ is the optimal concentration, providing a balance between corrosion resistance, mechanical stability, and biocompatibility, supporting the development of safer implant coatings. Full article

The cold-rolled 2024 aluminum alloy sheets were subjected to solution treatments at different temperatures followed by artificial aging. The microstructure and mechanical properties were investigated using Vickers microhardness testing, tensile testing, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that as the solution temperature increases, the coarse particles gradually dissolved into the matrix. At a solution temperature of 500 °C, the grains become nearly equiaxed with an average size of ~16.47 μm, and no significant grain growth is observed compared to the as-rolled condition. The refined microstructure contributes to excellent mechanical properties. In contrast, when the solution temperature increases to 550 °C, the microstructure shows severe grain coarsening (up to ~61.39 μm), which indicates that overburning occurs, resulting in a drastic deterioration in mechanical performance. As the aging time increases, precipitates become more uniformly and densely distributed throughout the matrix, and the hardness initially increases and reaches a peak after approximately 6 h of aging at 180 °C. The optimal mechanical performance, characterized by a favorable combination of strength and ductility, is achieved at an aging time of 6 h. In summary, the optimal heat treatment condition for the cold-rolled 2024 aluminum alloy sheet is solution treatment at 500 °C for 1 h followed by aging at 180 °C for 6 h, resulting in a hardness of 154 HV, a tensile strength of 465 MPa and an elongation of 13%. Full article

Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is a conductive water-processable polymer with many important applications in organic electronics. The electrical conductivity of PEDOT:PSS layers is very diverse and can be changed by changing the processing and post-deposition conditions, e.g., by using different solvent additives, doping or modifying the physical conditions of the layer deposition. Despite many years of intensive research on the relationship between the microstructure and properties of these layers, there are still gaps in our knowledge, especially with respect to the detailed understanding of the charge carrier transport mechanism in organic semiconductor thin films. In this work, we investigate the effect of acid doping of PEDOT:PSS thin films on the intra-chain and inter-chain conductivity by developing a model that treats PEDOT:PSS as a nanocomposite material. This model is based on the effective medium theory and uses the percolation theory equation for the electrical conductivity of a mixture of two materials. Here its implementation assumes that the role of the highly conductive material is attributed to the intra-chain conductivity of PEDOT and its quantitative contribution is determined based on the optical Drude–Lorentz model. While the weaker inter-chain conductivity is assumed to originate from the weakly conductive material and is determined based on electrical measurements using the van der Pauw method and coherent nanostructure-dependent analysis. Our studies show that doping with methanesulfonic acid significantly affects both types of conductivity. The intra-chain conductivity of PEDOT increases from 260 to almost 400 Scm⁻¹. Meanwhile, the inter-chain conductivity increases by almost three orders of magnitude, reaching a critical state, i.e., exceeding the percolation threshold. The observed changes in electrical conductivity due to acid doping are attributed to the flattening of the PEDOT/PSS gel nanoparticles. In the model developed here, this flattening is accounted for by the inclusion shape factor. Full article

Conventional slurry wall protection exhibits reduced film performance upon exposure to water in saturated sand layers with high permeability, frequently resulting in hole wall instability. Optimizing the slurry ratio to enhance film performance is thus critical for borehole stability. A multiple regression model was developed to determine the optimal slurry ratio for saturated sand. Slurry permeability tests assessed filtration loss, film formation time, and film morphology changes. Scanning electron microscopy (SEM) further elucidated the film formation mechanism. Bentonite, clay, Na₂CO₃, and sodium carboxymethyl cellulose (CMC) significantly affected the slurry’s properties: specific gravity and sand content increased with bentonite/clay; viscosity increased with CMC; and pH increased with Na₂CO₃. The optimized slurry (water–bentonite–Na₂CO₃–clay–CMC = 1000:220:32:110:1; specific gravity, 1.20 g/cm³; viscosity, 29 s) demonstrated low filtration loss and stable film morphology. SEM revealed that simultaneous CMC and clay addition (ratio of 1:110) improved film surface flatness, reduced porosity and pore size, enhanced formation surface filling, and produced a denser film. The optimized slurry ratio significantly enhanced film performance in saturated sand layers. The findings provide a theoretical and engineering framework for bored pile wall protection slurry design and film formation mechanisms. Full article

Cu₂S has wide-ranging applications in the energy field, particularly as electrode materials and components of energy storage devices. However, the migration of copper ions is prone to component segregation and copper precipitation, impairing long-term thermal stability and service performance. Ce₂S₃ not only possesses the unique 4f electron layer structure of Ce but also has high thermal stability and chemical inertness. Here, we report for the first time that the thermal stability and mechanical properties of Cu₂S can be significantly enhanced by introducing the dispersed phase Ce₂S₃. Thermogravimetry—differential scanning calorimetry (TG-DSC) results show that the addition of 6 wt% Ce₂S₃ improves the thermal stability of Cu₂S sintered at 400 °C. X-ray diffraction (XRD) results indicate that the crystal structure of Cu₂S gradually transforms to tetragonal Cu_1.96S and orthorhombic Cu_1.8S phase at 400 °C with the increase of Ce₂S₃ addition. Scanning electron microscopy (SEM) results show that the particle size gradually decreased with the increase of Ce₂S₃ amount, indicating that the Ce₂S₃ addition increased the reactivity. The Ce content in Cu₂S increased gradually with the increase of Ce₂S₃ amount at 400–600 °C. The 7 wt% Ce₂S₃-Cu₂S exhibits paramagnetic behavior with a saturation magnetization of 1.2 µ_B/Ce. UV-Vis analysis indicates that the addition of Ce₂S₃ can reduce the optical energy gap and enrich the band structure of Cu₂S. With increasing addition of Ce₂S₃ and rising sintering temperature, the density of Ce₂S₃-Cu₂S gradually increases, and the hardness of Ce₂S₃-Cu₂S increases by 52.5% at 400 °C and by 34.2% at 600 °C. The friction test results show that an appropriate addition amount of Ce₂S₃ can increase the friction coefficients of Cu₂S. Ce₂S₃ modification offers a novel strategy to simultaneously enhance the structural and service stability of Cu₂S by regulating Cu ion diffusion and suppressing compositional fluctuations. Full article

Basalt fiber reinforced polymer (BFRP) is one of the new materials that can be used for making photovoltaic scaffolds, which can effectively solve the problem of the rapid deterioration of complex environmental performance and high maintenance cost of traditional scaffold materials. This paper focuses on the BFRP photovoltaic support in the cold and arid irrigation area of northwest China, carries out the durability test under the action of chloride salt, freeze-thaw cycle, and chloride salt freeze-thaw environment coupling, and it compares and analyzes the degradation law of the mechanical properties of BFRP sheets under different environmental effects. The performance degradation mechanism of BFRP materials under different environmental effects was revealed by SEM scanning electron microscopy and EDS energy spectrum analysis. The main conclusions are as follows: (1) Under the action of chloride salt, the tensile strength, elastic modulus and elongation at break of the specimen decreased by 11.46%, 7.02%, and 10.27%, respectively. Under the freeze-thaw cycle, the tensile strength and elongation at break of the specimen decreased by 9.62% and 6.85%, while the elastic modulus first increased and then decreased, with a maximum decrease of 12.95%. The degradation of mechanical properties is the most serious under the coupling effect of chloride salt and the freeze-thaw environment. The tensile strength, elastic modulus, and elongation at break of the specimens decreased by 25.73%, 9.55%, and 24.81%, respectively. (2) In the chloride environment, the distribution of elements on the surface of the specimen changed, the metal ions of the fibers precipitated, and ‘black spots‘ and corrosion pits appeared. The resin matrix forms ‘sponge-like‘ pores; under the freeze-thaw cycle, the fiber–resin interface cracks and fiber shedding intensifies; under the coupling effect of chloride freeze-thaw, ‘black spots‘, pits, resin holes, and interface cracks increased, and chloride penetration corrosion accelerated. Full article

Silicon (Si), the cornerstone semiconductor in the micro-electronics industry, can provide a cost-efficient platform with mature technologies for photodetection in visible and near-infrared regions. However, its intrinsic properties, such as a narrow bandgap and the shallow penetration depth of ultraviolet (UV) light into its surface with surface trap states, remain challenges, rendering it unsuitable for effective UV light detection. Various techniques have been reported to circumvent these surface defect-induced difficulties. In addition, wide-bandgap semiconductors that favor UV light absorption in a solar-blind way have been combined with Si for UV light detection in order to retain the device’s compatibility with Si-CMOS processes, though it still faces challenges that need to be overcome. This review starts with concepts of basic parameters of photodetectors and categorizes UV photodetectors according to their detection mechanisms. We also present a review of wide-bandgap semiconductor-based UV light detectors and those based on Si, with a discussion of surface defect minimization. In addition, we review the hybrid structure of the two kinds, i.e., wide-bandgap semiconductors and Si, and discuss their properties that produce synergistic effects. Lastly, we provide conclusions and outlooks for the possible development of next-generation UV light detectors based on Si. Full article

Background/Objectives: Cancer progression is characterized by the suppression of apoptosis, activation of metastatic processes, and dysregulation of cell proliferation. The proper functioning of these mechanisms relies on critical signaling pathways, including Phosphoinositide 3-kinase/Protein kinase B/mammalian Target of Rapamycin (PI3K/Akt/mTOR), Mitogen-Activated Protein Kinase (MAPK), and Signal Transducer and Activator of Transcription 3 (STAT3). Although curcumin and resveratrol exhibit anticancer properties and affect these pathways, their pharmacokinetic limitations, including poor bioavailability and low solubility, restrict their clinical application. The aim of our study was to evaluate the synergistic anticancer potential of curcumin and resveratrol through hybrid molecules rationally designed from these compounds to mitigate their pharmacokinetic limitations. Furthermore, we analyzed the multi-target anticancer effects of these hybrids on the AKT serine/threonine kinase 1 (AKT1), MAPK, and STAT3 pathways using in silico molecular modeling approaches. Methods: Three hybrid molecules, including a long-chain (ELRC-LC) and a short-chain (ELRC-SC) hybrid, an ester-linked hybrid, and an ether-linked hybrid (EtLRC), were designed using the Avogadro software (v1.2.0), and their geometry optimization was carried out using Density Functional Theory (DFT). The electronic properties of the structures were characterized through Frontier Molecular Orbital (FMO), Molecular Electrostatic Potential (MEP), and Fourier Transform Infrared (FTIR) analyses. The binding energies of the hybrid molecules, curcumin, resveratrol, their analogs, and the reference inhibitor were calculated against the AKT1, MAPK, and STAT3 receptors using molecular docking. The stabilities of the best-fitting complexes were evaluated through 100 ns molecular dynamics (MD) simulations, and their binding free energies were estimated using the Molecular Mechanics/Poisson–Boltzmann Surface Area (MM/PBSA) method. Results: DFT analyses demonstrated stable electronic characteristics for the hybrids. Molecular docking analyses revealed that the hybrids exhibited stronger binding compared to curcumin and resveratrol. The binding energy of −11.4 kcal/mol obtained for the ELRC-LC hybrid against AKT1 was particularly remarkable. Analysis of 100 ns MD simulations confirmed the conformational stability of the hybrids. Conclusions: Hybrid molecules have been shown to exert multi-target mechanisms of action on the AKT1, MAPK, and STAT3 pathways, and to represent potential anticancer candidates capable of overcoming pharmacokinetic limitations. Our in silico-based study provides data that will guide future in vitro and in vivo studies. These rationally designed hybrid molecules, owing to their receptor affinity, may serve as de novo hybrid inhibitors. Full article

In this study, hemolytically safe and antibacterial polyvinyl alcohol/kaolinite/chitosan (PVA/KAO/CS) hydrogels were obtained using the freeze–thaw method. The structure of the chemical bonds present in the developed hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) and optical microscopy study results showed the morphological and structural characteristics of the hydrogels’ surface. The thermal stability and phase transitions of the obtained hydrogel samples were determined by thermogravimetric analysis (TGA). Porosity, swelling, gel fractions, and mechanical properties were also examined. Biomedical properties of the samples were evaluated using in vitro and in vivo tests such as hemolytic activity, inhibition of protein denaturation, antimicrobial activity, and hemostatic activity. The obtained hydrogels demonstrated safe hemolytic activity, pronounced hemostatic activity, the ability to prevent thermal denaturation of albumin, as well as antimicrobial activity against Gram-positive bacteria Staphylococcus aureus ATCC BAA-39 and Streptococcus pyogenes ATCC 19615 and Gram-negative bacteria Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 8739. All the obtained characteristics confirmed the promising biomedical applications of the obtained hydrogels. Full article

An AA6061-7075 composite with a heterogeneous structure was fabricated via the additive friction stir deposition (AFSD) method, and in situ processing data were monitored during the manufacturing process. The results show that the cross-section of the composite subjected to AFSD exhibits a lower degree of plastic deformation behavior compared to the surface and side of the composite, owing to serious heat accumulation during the layer-by-layer stacking process. The denser, heterogeneous structure, consisting of finer (softer) and coarser (harder) grains, which correspond to AA6061 and AA7075, was formed according to transmission electron microscopy (TEM) analysis. Furthermore, the obtained composite subjected to AFSD in this work presents outstanding mechanical properties compared to other as-fabricated AA6061/AA7075 depositions acquired by other additive manufacturing methods along the horizontal building direction, with the ultimate tensile strength (266 MPa) being 89% of that of AA6061-T6 and the elongation 1.1 times that of AA7075-T6. The findings provide useful guidelines for the in situ preparation of Al-based composites and offer ideas for manufacturing high-strength heterostructures for large-scale practical engineering applications. Full article

ZrO₂-MgO-Al₂O₃ ceramics, despite a long history of research, still attract the attention of researchers due to the high potential of their applications as refractories and matrices for metal ceramics. A unique composition combining high strength and temperature stability is particularly in demand. In this paper, a comprehensive study of ceramics of the composition (90−x)·ZrO₂-10·MgO-x·Al₂O₃ (x = 10–80 wt.%) obtained by solid-phase sintering with preliminary annealing is carried out. Preliminary annealing was used for the possible formation of metastable phases with outstanding mechanical properties. Using the X-ray diffraction method, it was found that most of the samples consist of monoclinic zirconium oxide, magnesium–aluminum spinel, and corundum phases. The exception is the sample with x = 10 wt.%, in which the main phase was a cubic modification of zirconium oxide. By formation this type of ZrO₂ polymorph in the composition hardness and flexural strength significantly increased from 400 to 1380 and 50 to 210 MPa, respectively. The total porosity of ceramics under study lies in the range 6–28%. Using the scanning electron microscopy method, it was found that the phase composition significantly affects the morphology of the microstructure of the sintered bodies. Thus, for sintered ceramics with a high corundum content, the microstructure is characterized by high porosity and a large grain size. For the first time, by applying preliminary annealing, a new type of ternary ceramic ZrO₂-MgO-Al₂O₃ was sintered with potentially outstanding mechanical properties. The presence of a stabilized zirconium oxide phase, stresses in the crystal lattice of the matrix phase, and the formation of cracks in the microstructure are the main factors influencing shrinkage, porosity, microhardness, and biaxial flexural strength. Full article

Control of the friction process in stretch-forming conditions, when creating sheet metal, is essential for obtaining components of the quality required. This paper presents an approach to modelling the friction phenomenon at the rounded edges of stamping dies. The aim of the study is to compare the coefficient of friction (CoF) determined from numerous analytical models available in the literature. Experimental studies were conducted using self-developed bending under tension friction testing apparatus. The test material was low-carbon DC01 steel sheeting. Tests were conducted under lubricated conditions, using industrial oil intended for deep drawing operations. The surfaces of countersamples made of 145Cr6 substrate were modified using the ion implantation of Pb (IOPb) and electron beam melting processes. Variation in the CoF in BUT tests was related to continuous deformation-induced changes in surface topography and changes in the mechanical properties of sheet metal due to the work-hardening phenomenon. Under friction testing with a stationary countersample, the largest increase in average roughness (by 19%) was found for the DC01/IOPb friction pair. The friction process caused a significant decrease in kurtosis values. The results show that the difference between the highest and lowest CoF values, determined for the analytical models considered, was approximately 40%. Full article

The present paper compares the microstructure and mechanical properties of Inconel 625 alloy samples produced by using wire-arc additive manufacturing (WAAM) and wire electron beam additive manufacturing (WEBAM). The obtained wall-shaped samples did not contain any macroscopic defects in the form of cracks, delaminations and geometry distortions. The WAAM-built “wall” exhibits finer dendritic structures (WAAM—10–16 μm; WEBAM—20–25 μm). Also, the WAAM-built one is characterized by the more homogeneous-sized distribution of microstructure components. In both cases, the material is represented by the γ-phase, with large precipitates of MC-type carbides in the interdendritic spaces. Additionally, the sample obtained using the WAAM contained aluminum oxide. It was found that the intrinsic periodic heat treatment is not sufficient for the formation of the γ″-phase, and it is necessary to perform a subsequent long-term aging. However, the overall mechanical properties of both samples show similar levels of yield stress and ultimate tensile strength, and demonstrate the same degree of anisotropy. Full article