Search Results (2,292)

In the last thirty years, tissue engineering (TI) has emerged as an alternative method to regenerate tissues and organs and restore their function by implanting specific lineage cells, growth factors, or biomolecules functionalizing a matrix scaffold. Recently, several pathologies have led to bone loss or damage, such as malformations, bone resorption associated with benign or malignant tumors, periodontal disease, traumas, and others in which a discontinuity in tissue integrity is observed. Bone tissue is characterized by different stiffness, mechanical traction, and compression resistance as a function of the different compartments, which can influence susceptibility to injury or destruction. For this reason, research into repairing bone defects began several years ago to find a scaffold to improve bone regeneration. Different techniques can be used to manufacture 3D scaffolds for bone tissue regeneration based on optimizing reproducible scaffolds with a controlled hierarchical porous structure like the extracellular matrix of bone. Additionally, the scaffolds synthesized can facilitate the inclusion of bone or mesenchymal stem cells with growth factors that improve bone osteogenesis, recruiting new cells for the neighborhood to generate an optimal environment for tissue regeneration. In this review, current state-of-the-art scaffold manufacturing based on the use of polycaprolactone (PCL) as a biomaterial for bone tissue regeneration will be described by reporting relevant studies focusing on processing techniques, from traditional—i.e., freeze casting, thermally induced phase separation, gas foaming, solvent casting, and particle leaching—to more recent approaches, such as 3D additive manufacturing (i.e., 3D printing/bioprinting, electrofluid dynamics/electrospinning), as well as integrated techniques. As a function of the used technique, this work aims to offer a comprehensive overview of the benefits/limitations of PCL-based scaffolds in order to establish a relationship between scaffold composition, namely integration of other biomaterial phases’ structural properties (i.e., pore morphology and mechanical properties) and in vivo response. Full article

In this work, we focused on the characterization of closed-cell Al foams and aluminum honeycomb panels, in particular their energy absorption capacity under conditions of static compressive stress. Through experimental tests, the specific energy absorbed by different samples was evaluated: in the honeycomb panels the mechanical behavior was analyzed both for large assemblies and for structures with a reduced number of cells, and the effect of the number of cells was studied too. Furthermore, for larger structures, the specific energy absorbed was calculated from stress–strain compressive graphs. For the closed-cell Al foams, manufactured in the laboratory using the powder compaction method with different percentages of SiC and TiH₂ and characterized by different relative densities, the specific energy absorbed was evaluated too. The experimental results showed that the specific energy absorbed by the Al honeycomb was always higher than that of the different types of closed-cell foams. However, when selecting the material for each specific application, it is necessary to take into account numerous parameters such as the relative density, absorbed energy, peak stress, plateau stress, plateau extension, densification strain and so on. Consequently, the overall performance must be evaluated from time to time based on the type of application in which the best compromise between strength, stiffness and lightness can be achieved. Full article

Starch foam has attracted significant attention as an alternative to expanded styrene (EPS) foam owing to its abundance and biodegradability. Despite these merits, its limited thermal insulation and flexibility compared to EPS have hindered its utilization in packaging. Herein, we report the effect of blending with starch/PBAT on foaming behavior and physical properties during foaming processing. We fabricated a starch/PBAT blend with systematically controlled blending ratios (0, 10, 15, 20, and 25 wt%) to analyze their effect on the interaction and characteristics of blended foam. The blending of starch and PBAT significantly reduced complex viscosity, enhancing resin flow during the foaming process. This improvement in resin flow led to increases in expansion ratio while reducing density and cell wall thickness. The thermo-insulation performance improved to 0.043 W/mK with 20 wt% of PBAT due to the enhanced expansion ratio and cell morphology. Additionally, the flexural strain at break improved significantly from 2.8 ± 0.6% to 9.6 ± 1.0% with increasing PBAT content. Enhanced water resistance was also observed, demonstrated by a reduction in water absorption and an extension of dissolution time. Overall, these findings underscore the potential of starch/PBAT foam to improve the thermal-insulating property, flexibility, and water resistance while maintaining their biodegradability and sustainability. Full article

The electrochemical CO₂ reduction reaction (CO₂RR) to formate offers a promising pathway to mitigate the energy crisis and realize carbon neutrality. Bismuth (Bi), as a metal catalyst for the CO₂RR, is considered to have great potential in producing formate, yet hindered in low current density and selectivity. Herein, we constructed an oxide-derived copper foam substrate (OD-Cu) to improve the electrocatalytic properties of Bi dendrites loaded on its surface. Bi electrodeposited on the OD-Cu (Bi/OD-Cu) grows as pinecone-like dendrites, exhibiting a high formate faradaic efficiency (FE_formate) of 97.2% and a formate partial current density of ~24 mA·cm⁻² at −0.97 V vs. RHE (reversible hydrogen electrode) in an H-cell. Notably, the Bi/OD-Cu electrode demonstrates an FE_formate of 95.8% at −0.97 V vs. RHE and a total current density close to 90 mA·cm⁻² at −1.17 V vs. RHE in a neutral flow cell. The experimental studies reveal that the remarkable CO₂RR performance of the Bi/OD-Cu results from the electron transfer from Cu to Bi, which optimizes adsorption of the CO₂^•− and boosts reaction kinetics. This study emphasizes the crucial role of substrate engineering strategies in enhancing catalytic activity and shows the possibility for a porous metal electrode in advancing the industrialization of formate production. Full article

Due to the soft mechanical properties of soft rock strata, roof fall accidents are frequent, causing great hazards to production. In order to eliminate hazards in the actual mining process, a new type of bag-filling scheme was designed by analyzing the mechanisms of roof falls in soft rock strata. By testing the filling material, the optimal ratio of foam filling material was determined, and the corresponding filling process was formulated. Through the field verification of this filling process, better support was achieved in the roof fall area, providing useful guidance and support for mines with similar conditions. Full article

This study examined the effects of varying microwave treatment durations (0–120 s) on the structural and functional properties of glycosylated soybean 7S protein. The results indicated that microwaving for 60 s significantly altered the structure of 7S, resulting in a more ordered protein configuration. The treated protein exhibited the largest particle size (152.3 nm), lowest polydispersity index (0.248), highest α-helix content (47.86%), and lowest β-sheet, β-turn, and random coil contents (12.33%, 16.07%, and 22.41%, respectively). It also showed the lowest endogenous fluorescence and surface hydrophobicity, and the highest thermal denaturation temperature (76.8 °C). Additionally, microwaving for ≤90 s led to increased peptide modifications, with carbamylation and deamidation being the most prevalent. A microwave treatment time of 60 s also notably enhanced the functional properties of glycosylated soybean 7S protein, optimizing water-holding capacity (6.060 g/g), emulsification activity, and stability (45.191 m²/g and 33.63 min). The foaming capacity was second only to the 120 s treatment (32% at 60 s versus 34% at 120 s), though the oil-holding capacity (22.73 g/g) and foaming stability (33.42%) were significantly lower than those of the controls. Microwave treatment durations exceeding or below 60 s led to the structural disintegration of the protein, diminishing most of its functional properties. This study explores the mechanism of how microwave processing time affects the structure and functional properties of glycosylated soybean 7S protein and identifies 60 s as the optimal microwave processing time. It meets the demands for healthy and delicious food in home cooking, providing scientific evidence for using microwave processing technology to enhance the nutritional value and quality of food. Full article

Dibenzyltoluene/perhydro-dibenzyltoluene (H₀DBT/H₁₈DBT) is considered a promising liquid organic hydrogen carrier (LOHC) pair for the storage and transportation of green hydrogen (H₂). However, at the point of use, the catalytic dehydrogenation of H₁₈DBT is still limited by mass transport limitations. To address this issue, the dehydrogenation of H₁₈DBT was successfully conducted on Pt/Al₂O₃-coated foams in both an unstirred tank reactor and a fixed-bed reactor (FBR). A performance comparison between coated foams and pellets in the tank reactor revealed that H₂ productivities were 12–59% higher in the foam-based reactor than in the pellet-based reactor. Since the textural properties of the foam-supported and pellet-based catalysts were similar, the higher degree of dehydrogenation (DoD) and H₂ productivity achieved by the former were attributed to the geometric properties of the foam structure. Long-term tests performed in the FBR demonstrated the ability of the coated foams to maintain steady activity for >16 h on stream. However, the single-pass DoDs achieved were 34–38%. By recycling the partially dehydrogenated products three times into the FBR, the DoD improved to 63%. The results of this study demonstrated the capabilities of the coated foams in the process intensification of LOHC dehydrogenation reactors. Full article

Nowadays, electromobility has a significant role in transportation; different electrically driven vehicles are spreading continuously. Due to this form of drivetrain, fire safety hazards have also changed when compared to those of conventional vehicles. Lately, electric vehicle fires have become more common; thus, we have chosen to investigate the negative impacts of these fires on humans and the environment, in addition to the toxic properties of the resulting combustion products. In our research work, we conducted a full-scale fire experiment on an electric passenger car. Fire extinguishing was executed with fire-fighting foam, and its efficiency was examined. After extinguishing the fire, we took samples from the combustion gases and soil. Samples were subjected to laboratory investigations. Our results and experiences are presented in this article. Full article

The growing interest in a plant-based diet leads to the search for new sources of protein in the human diet as an alternative to animal proteins. Plant materials that can supplement protein as additives in food products are being studied. Watermelon seeds (Citrillus lanatus L.) are rich in proteins and waste from the food industry; however, their extraction is not completely cost-free, and the flour production process may involve additional costs related to their extraction and processing. The studies showed that watermelon seed protein concentrate, obtained using the alkaline extraction method, contained 82.52 g/100 g of protein and 1.51 g/100 g of fat. The polyphenol content in the protein preparation from defatted watermelon seeds was 1.9 mg gallic acid/g, and the antioxidant activity of the concentrate was 29.26 µmol Trolox/g (by the ABTS+). The obtained watermelon seed protein concentrate was characterised by solubility of more than 80% (at pH = 10), water absorption at the level of 2.46 (g water/g) and oil absorption equal to 2.1 (ml oil/g), showed poor foaming properties (1.51%), and was characterised by low emulsification. Full article

Armor blocks are extensively deployed to shield vital coastal facilities against wave erosion. Evaluating the wave run-up and reflection under wave impact is essential for the engineering design of new ecological quadrangular hollow blocks. This study constructs a three-dimensional numerical model employing the open-source CFD software OpenFOAM-v2206 to analyze these processes for the new blocks. The model’s accuracy was confirmed by comparing its predictions with physical modelling tests. Model results accurately captured the variation in hydrodynamic parameters, as well as the energy dissipation properties of the new blocks. Sensitivity analysis indicated that both the wave reflection coefficients and run-up are considerably affected by mesh sizes, while velocity distributions and pressure fields were less affected by mesh. Finally, the model was utilized to examine how wave run-up and reflection for the new ecological quadrilateral hollow block are influenced by factors such as wave period, water depth, wave height, wave breaking characteristics, and wave steepness. The findings in this study provide valuable insights into novel design and safety assessment of new ecological quadrangular hollow blocks. Full article

Bead-foaming technology effectively addresses production cycles, polymerization control, and cellular structure defects in conventional bulk foaming, especially in high-performance PMI foams. In this work, highly expandable PMI beads were synthesized based on the aqueous suspension polymerization of methacrylic acid-methacrylonitrile-tert-butyl methacrylate (MAA-MAN-tBMA) copolymers. The suspension polymerization was stabilized by reducing the solubility of MAA by the salting-out effect and replacing formamide (a common PMI foaming agent) with tBMA. The polymerization process was optimized by varying salting-out agents, dispersants, water-to-oil ratio (WOR), and stirring speed to achieve uniform bead sizes (0.2–0.4 mm) and high bead yields (>70%). The expansion ratio of the beads can be easily tuned by adjusting tBMA content and foaming time and temperature. Beads with 10%tBMA can reach up to 64 times under a free-forming process at 240 °C, which serves as an excellent precursor toward high-performance in-mold foaming PMI. The beads exhibit excellent in-mold foaming capabilities, thermal stability (Td = 392 °C), and mechanical properties. This work provides a technical foundation for the bead-foaming technology of PMI foams, reducing the cost of PMI foam production and providing the possibility to expand the application of PMI foam in civilian use. Full article

This study optimized the process of extracting protein from black garlic using an alkaline dissolution and acid precipitation method through response surface methodology. The optimal extraction conditions were determined as a solid-to-liquid ratio of 1:50, an extraction time of 100 min, an extraction temperature of 30 °C, and an alkaline extraction pH of 9.0. Under these optimized conditions, the actual black garlic protein (BGP) extraction yield was 12.10% ± 0.21%, and the isoelectric point of the obtained BGP was 3.1. Subsequently, this study extracted black garlic protein under optimal conditions and subjected it to enzymatic hydrolysis using different enzymes (trypsin, pepsin, and their mixed enzymes). The functional characteristics, antioxidant activity, and hypoglycemic activity of black garlic protein before and after enzymatic hydrolysis were compared. Among the hydrolysates, the pepsin hydrolysate (BGPH-P) had the smallest particle size (188.57 ± 1.93 nm) and the highest Zeta potential (−29.93 ± 0.42 mV). Scanning electron microscopy showed that BGPH-P had the smallest and most dispersed particles. Fourier-transform infrared (FTIR) spectroscopy revealed that the dual enzymatic hydrolysis hydrolysate (BGPH-PT) exhibited the most stable structure. Compared to BGP, the hydrolysates demonstrated significantly improved solubility, water-holding capacity, and foaming ability (p < 0.05), while their emulsifying activity, emulsion stability, DPPH radical scavenging capacity, and hypoglycemic activity decreased. In summary, the BGP extracted using the optimized process demonstrated good antioxidant and hypoglycemic activities, while its enzymatic hydrolysate BGPH-P exhibited excellent solubility, water-holding capacity, and emulsifying properties, providing valuable insights for the further development of black garlic protein and its hydrolysates. Full article

In response to global energy, resource, and climate challenges, foamed concrete—a sustainable, low-carbon building material—offers advantages due to its lightweight nature and high thermal insulation. This study focused on alkali-activated foamed concrete (A07 grade, average density of 723 kg/m³) prepared from slag and fly ash under alkaline conditions. Using S95-grade slag powder and I-grade ground fine fly ash as raw materials, a sodium silicate and NaOH solution as the activator, and YS-200 composite cement foaming agent, alkali-activated foamed concrete with a density grade of A07 was prepared by physical foaming. The effects of water–binder ratio, fly ash content, and alkali equivalent on compressive strength, water absorption, drying shrinkage, and frost resistance were investigated. With a dry density of 300–1800 kg/m³ (1/10 to 1/3 of conventional concrete), it reduced building weight by 25–40%. Full article

This study explores the different techniques used to manufacture porous clay-based ceramics, examining their properties such as porosity, strength, permeability and filtration efficiency. Different techniques are discussed in this review, with additive manufacturing being one of the most innovative techniques for manufacturing porous ceramics. Porous ceramics have their applications in numerous domains. Such ceramic filters have the advantages of retaining heavy materials, suspended particles, bacteria, viruses and, water turbidity. Thus, the choice of the technique and propriety is a crucial step in obtaining a porous ceramic with the best performance. Barry et al. prepared porous phyllosilicate-based ceramics by freeze-tape casting on four samples and obtained porosity values in the range of 67–79% and diametrical compressive strength in the range of 3–7 MPa. Manni et al. prepared porous red ceramics from Moroccan clay and coffee waste (10, 20 and 30 wt.%) via uniaxial pressing and sintering at 1150 °C. They obtained porosities ranging from 30.2 to 63.8% and flexural strength values from 1.8 to 19.5 MPa. Medri et al. prepared ZrB2-based porous bodies with the use of sponges and polyurethane foams as templates via the replica method and obtained high porosity over 80% and compressive strength up to 4.8 MPa. The use of clay and peanut shell mixtures was used in preparing porous silicate ceramics after unidirectional pressing and sintering at 1100 °C. These samples included 25 mass% of peanut shells, and exhibited porosity in the range of 40 to 60% and diametrical compressive strength in the range of 1–6 MPa. Such properties are suitable for domestic use of these types of clay-based ceramic filters. Moreover, the permeability values and removal of some pollutants, like arsenic, have been satisfactory for the first set of samples. Full article

Recently, electromagnetic wave (EMW)-absorbing materials have obtained increasing attention for both military and civil applications. This study adopted the powder sintering method and the concept of recycled wastes in fabricating functional ceramic foam (CF). Firstly, a ceramic green body composed of pulverized granite residues, waste glass, and a foaming agent was sintered. The influence of the sintering temperature and SiC addition on CF was investigated, and then surface graphitization post-treatment of CF was performed as well. The truly enhanced compressive strength and EMW-absorbing property of surface graphitization ceramic foam (SG-CF) with a homogeneous porous structure was realized in the present work, which is promising as a candidate in EMW absorption systems. Full article