Properties Of Foams Research Articles

Application Properties of Gemini Quaternary Ammonium Salt with Quadra‐cationic Sites and Sodium Fatty Alcohol Polyoxyethylene Ether Carboxylate Mixed Systems

AbstractThe application properties such as foam property, electrolyte tolerance, antibacterial activity and antistatic performance of the mixed systems of a novel Gemini quaternary ammonium salt with quadra‐cationic sites (TC‐GS) and sodium fatty alcohol polyoxyethylene ether carboxylate (AE9CNa) at various molar fraction of TC‐GS (αTC‐GS), were investigated systematically. Results show that TC‐GS/AE9CNa mixed systems with different ratios form a homogeneous and transparent solution, which exhibits excellent foam stability and antibacterial activity. The foam volume of the mixed system remains nearly constant from 400 s to 1000 s, and even when TC‐GS is 10 mg/L in the mixed systems, the antibacterial rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) for 2 min. are all exceeded 99 %. The mixed systems of TC‐GS/AE9CNa at various αTC‐GS also demonstrate the superior electrolyte tolerance, their maximum tolerance of NaCl, CaCl2 and MgCl2 is severally beyond 270 g/L, 180 g/L and 180 g/L. In addition, both TC‐GS solution and the mixed systems have good antistatic properties, which can reduce the surface resistance of polyester fabric to ≤1010 Ω.

PH-induced conformational changes of lupin protein-pectin mixtures and its effect on air-water interfacial properties and foaming functionality

Lupin protein isolate (LPI) has high nutritional value and good foaming properties around neutral pH; however, its functionality becomes poor at acidic pH, due to reduced protein solubility. The addition of pectin to LPI can increase its solubility at acidic pH and hence improve protein functionality. Here, we investigated the air-water interfacial and foaming properties of LPI-pectin (1:1) mixtures at pH 3.5–7.0. We used interfacial shear and dilatational rheology, characterized the air-water interfacial microstructure with AFM of Langmuir-Blodgett films, and linked the results to the foaming properties of the LPI-pectin mixtures. Based on the phase diagram, LPI and pectin formed co-soluble mixtures at pH 6.0 and 7.0, while LPI-pectin electrostatic complexes were formed at pH 3.5 and 4.0. In the co-soluble mixtures, proteins diffused faster towards the air-water interface than the electrostatic complexes, due to smaller particle sizes of the proteins. Their air-water interfaces showed distinct differences with respect to microstructure and mechanical properties. The interfaces stabilized by co-soluble mixtures were dominated by protein aggregates, leading to weaker interfaces in response to shear and dilatational deformation, while the complexes formed thicker and denser polymeric air-water interfaces that were stiffer and more solid-like. As a result, the complex-stabilized foams were more stable than those stabilized with co-soluble mixtures. Findings from this study indicate that soluble LPI-pectin complexes formed at pH 3.5 and 4.0 were more efficient in improving interfacial and foaming properties of LPI than the co-soluble mixtures at pH 6.0 and 7.0, which can be used to tailor the properties of acid aerated products stabilized by LPI.

Effect of ultrasound on the characterization and peptidomics of foxtail millet bran protein hydrolysates

Protein hydrolysates have attracted much attention for their high biological activity and are a crucial product form for the utilization of foxtail millet bran by-products. In this study, changes in the structure, functionality, activity and peptide profile of foxtail millet bran protein hydrolysates (FMBPHs) at different ultrasound powers (0 – 600 W) were investigated. The results showed that ultrasound promoted the transformation of α-helix and β-sheet to random coils and β-turn, and the exposure of hydrophobic groups and sulfhydryl groups in FMBPHs. The average particle size of the samples decreased, and the absolute value of the ζ-potential increased significantly. Simultaneously, smaller porous particles and loose fragments appeared on the surface of FMBPHs when the ultrasonic power was increased to 450 W. Additionally, 450 W ultrasound treatment improved solubility, foaming properties, emulsifying properties, thermal stability of FMBPHs. The DPPH, ABTS and hydroxyl radical scavenging ability (IC50, 2.65, 1.06 and 3.02 mg/mL), Fe2+ chelating activity (IC50, 2.62 mg/mL), and reducing power of the samples were also enhanced. The peptidomics results demonstrated that ultrasonication increased the number of active peptides in the hydrolysate, and the relative abundance of 17 active peptides was obviously elevated at 450 W. Peptide map analysis showed that ultrasound-induced structural modifications affected the peptide profiles of Ubiquitin-like domain-containing protein, Cupin type-1 domain-containing protein, 40S ribosomal protein S19, and Oleosin 1, showing changes in the abundance of certain peptides, which may be related to changes in the characterization of FMBPHs.

Air-water interfacial and foaming properties of nanoparticles based on commercial and lab-scale isolated maize (Zea mays L.) zein

Maize zein based nanoparticles (ZNPs) can have applications as food dispersion stabilizers. It has not been documented to what extent the used zein isolation method and conditions thereof impact the structure and functionality of nanoparticles (NPs) based thereupon. Here, zein extracted from maize flour on lab scale (LS-zein) was compared with a commercial zein powder (CS-zein). On a dry matter basis, CS-zein contained 96.5% protein, while LS-zein contained 74.5% protein, 12.7% lipid, 2.9% ash, and a residual fraction, likely starch remnants. SE-HPLC analysis showed that 27.8% of CS-zein protein occurred in an aggregated and insoluble form, while LS-zein mainly contained mono-/dimeric proteins but also approximately 30% hydrophilic peptides. These differences resulted in notably different behavior in the functionality of ZNPs based on CS- and LS-zein (CS-ZNPs and LS-ZNPs, respectively) produced via liquid antisolvent precipitation. CS-ZNPs had poor foaming properties regardless of the pH, in line with their low interfacial dilatational moduli (12.9–15.0 mN/m). The foaming properties of LS-ZNPs were notably better. The high LS-ZNP foam stability (FS) at pH 8.0 and 10.0 was attributed to electrostatic repulsive effects between interfaces of adjacent air bubbles due to the adsorption of peptides and to synergistic protein-lipid interaction effects at the air–water interface. The LS-ZNP FS at pH 4.0 was low despite a high interfacial dilatational modulus (52.6 mN/m). It is hypothesized that intact LS-ZNPs in the liquid thin films between gas bubbles negatively affect FS by a bridging de-wetting effect. Overall, it can be concluded that the (partial) co-isolation of lipids with zein may positively influence foaming properties of NPs based thereupon, while extensive zein purification as applied in industrial zein isolation leads to (partial) zein aggregation and overall low foaming capacity of the obtained CS-ZNPs.

Comparison of plastic and glass cages on volatile compounds in protein extracted from Protaetia brevitarsis larvae

Edible insects, known for their high-protein production efficiency, are vital for enhancing food security. However, standardized breeding protocols are lacking, and research on the impact of cage materials on insect product composition is limited. This study investigated the volatile compounds and processing properties of protein from Protaetia brevitarsis larvae reared in plastic and glass cages. Protein extracts from larvae reared in plastic cages contained 14 types of hydrocarbons, 4 types of ketones, and 1 type of phenol. Those reared in glass cages contained two types of acids, seven types of alcohols, and five types of aldehydes. Notably, plastic-derived compounds, such as p-xylene (110.87 μg/mL) and o-xylene (37.98 μg/mL), were significantly higher in the extracts from plastic cages, indicating potential plastic exposure. Processing properties, including protein solubility, pH, color, foaming properties, and emulsion characteristics, showed no significant differences between the two rearing conditions (P > 0.05). Therefore, considering the detection and potential accumulation of plastic-derived volatile compounds, using glass cages may be more beneficial for rearing insects for protein production.

Irradiation-induced modifications of apple seed protein isolate: Exploring techno-functional, structural, thermal, and morphological characteristics

Waste valorization of apple seeds for protein extraction is a sustainable approach to the management of apple seed waste in the apple processing industry. The purpose of the research is to study the modification of apple seed protein isolates under different doses of irradiation on functional, structural, thermal, and morphological characteristics. Different irradiation doses of 8, 15, 20 25, and 50 kGy showed significant variations in protein content (88.70%–86.45%), total phenolic content (774.13–285.42 mg GAE/100g), and color profile of the apple seed protein. Irradiation altered the apple seed protein isolates' functional properties with increased foaming properties and emulsifying properties and decreased water and oil absorption properties. Irradiation induces denaturation and cross-linking in the apple seed protein structures, which increase surface hydrophobicity (708.66–1740.66), decreased zeta potential (−18.60 to −39.39 mV), and alteration in protein secondary structures with decreased α-helix (11.52–10.43 %), β-sheet content (60.82–60.13%), and random coils (16.82–16.19%), and increased β turns (10.79–13.22 %). DSC and TGA analysis revealed improved thermal properties using irradiation doses of 8–20 kGy whereas reduction for 25–50 kGy in irradiated apple seed proteins. Scanning electronic microscopy showed pores and aggregated structures of irradiated apple seed protein isolates. The study revealed the potential of irradiation as one of the non-thermal techniques for modifying apple seed protein isolates for protein valorization in various food applications.

Corn silk as an underutilized sustainable source of plant proteins: Extraction, fractionation, structure, and techno-functional properties

Plant proteins extracted from agro-industrial waste are gaining importance in the food industry due to environmental, sustainability, and economic reasons. These proteins can be extracted and then converted into high-value ingredients, thereby promoting a circular economy. Corn silk, often regarded as an underutilized waste stream, currently has limited applications beyond its uses as a traditional medicine in some regions of the world. The present study characterized the structural, physicochemical, thermal, techno-functional, and in vitro digestibility properties of corn silk protein (CSP) and its three major fractions (albumin, globulin, and glutelin). Glutelin (67.5%) was the major protein fraction of CSP, followed by albumin (23.2%) and globulin (9.2%). A purity greater than 60% could be achieved for all fractions. The structural and techno-functional properties of the different protein fractions were impacted by their composition. The glutelin fractions had higher foaming and thermal properties but lower emulsification properties than the other fractions. However, the albumin fraction had higher in vitro digestibility and better nutritional quality. Nevertheless, the CSPs did have lysine levels below the recommended values. These findings extend the current understanding of the structural and functional properties of corn silk protein and its fractions, thereby expanding their potential applications in the food and other industries.

Axial Impact Performances of Composite Aluminum Foam Tubes

An improved melt foaming method is employed to fabricate composite aluminum foam tubes (CAFTs) with varying diameter ratios, achieving metallurgical bonding between the aluminum foam and aluminum tubes. Based on the structural characteristics of aluminum foam‐filled tubes and traditional numerical formula for calculating the energy absorption properties of metal foams, a new calculation formula is proposed to accurately evaluate energy absorption performance of CAFTs under axial load, enabling more precise numerical calculation of total energy absorption. Furthermore, drop weight impact tests and finite element simulations are conducted to investigate the axial impact performance and deformation mechanism of CAFTs. The influence of diameter ratio on crashworthiness and energy absorption performance is also analyzed. As the diameter ratios decrease, both the impact resistance and total energy absorption of CAFTs increase, while the degree of tube damage gradually decreases. Moreover, finite element simulation results demonstrate that metallurgical combination between aluminum foam and aluminum tubes effectively transfers stress to thin‐walled tubes with better load‐bearing performance, preventing concentrated collapse of aluminum foam core. Additionally, the presence of aluminum foam provides robust restraint against deformation or rupture in thin‐walled tubes.

Liquefaction optimization of grape pulp using response surface methodology for biopolyol production and bio-based polyurethane foam synthesis.

Both environmental and economic disadvantages of using petroleum-based products have been forcing researchers to work on environmentally friendly, sustainable, and economical alternatives. The purpose of this study is to optimize the solvothermal liquefaction process of grape pomace using response surface methodology coupled with a central composite design. After investigating the physicochemical properties of the liquified products (biopolyol) in detail, a bio-based rigid polyurethane foam (RPUF) was synthesized and characterized. The hydroxyl and acid numbers and viscosity values of all the biopolyols were analyzed. According to variance analysis results (%95 confidence range), both the reaction temperature and catalyst loading were determined as significant parameters on the liquefaction yield (LY). The model was validated experimentally in the following reaction conditions: 4.25% catalyst loading, 50 min reaction time, and 165 °C reaction temperature, which yields an LY of 81.3%. The biopolyols produced by the validation experiment display similar characteristics (hydroxyl number: 470.5 mg KOH/g; acid number: 2.31 mg KOH/g; viscosity: 1785 cP at 25 °C) to those of commercial polyols widely preferred in the production of polyurethane foam. The physicochemical properties of bio-based foam obtained from the biopolyol were determined and the thermal conductivity, closed-cell content, apparent density, and compressive strength values of bio-based RPUF were 31.3 mW/m·K, 71.1%, 33.4 kg/m3, and 105.3 kPa, respectively.

Mechanical Characteristics of Multi-Level 3D-Printed Silicone Foams.

Three-dimensional-printed silicone rubber foams, with their designable and highly ordered pore structures, have shown exceptional potential for engineering applications, particularly in areas requiring energy absorption and cushioning. However, optimizing the mechanical properties of these foams through structural design remains a significant challenge. This study addresses this challenge by formulating the research question: How do different 3D-printed topologies and printing parameters affect the mechanical properties of silicone rubber foams, and how can we design a novel topological structure? To answer this, we explored the mechanical behavior of two common structures-simple cubic (SC) and face-centered tetragonal (FCT)-by varying printing parameters such as filament spacing, filament diameter, and layer height. Furthermore, we proposed a novel two-level 3D-printed structure, combining SC and FCT configurations to enhance performance. The results demonstrated that the two-level SC-SC structure exhibited a specific energy absorption of 8.2 to 21.0 times greater than the SC structure and 2.3 to 7.2 times greater than the FCT structure. In conclusion, this study provides new insights into the design of 3D-printed silicone rubber foams, offering a promising approach to developing advanced cushioning materials with superior energy absorption capabilities.

Impact of pH on the structure, interfacial and foaming properties of pea protein isolate: Investigation of the structure – Function relationship

This study explored the relationship between pea protein foaming properties and their structure and physicochemical properties under neutral and acidic pH. Results showed that pH modified the zeta potential, particle size and surface tension due to electrostatic changes. FT-MIR and fluorescence spectra revealed pH-induced conformational changes, exposing hydrophobic groups and increasing sulfhydryl content, promoting protein aggregation. At pH 3, the highest foaming capacity (1.273) and lowest foam expansion (6.967) were observed, associated with increased surface hydrophobicity and net charges, ideal for creating light foams with high liquid incorporation for acidic beverages or fruit-based mousses. Pea protein isolate generated stable foams with foam volume stability between 86.662 % and 94.255 %. Although neutral pH conditions showed the highest foam volume stability, their air bubbles increased in size and transitioned from spherical to polyhedral shape, suitable for visual-centric applications, like cappuccino foam and beer-head retention. Foams at pH 5 exhibited the smallest bubbles and maintained their spherical shape, enhancing drainage resistance, beneficial for whipped toppings. Strong correlations (Pearson correlation coefficient higher than 0.600) were noted between the structure, surface and foaming properties, providing crucial insights into optimizing pea protein functionality across various pH conditions, enabling the development of plant-based foamed products with tailored properties.

Preparation of microgel particles from egg yolk components by combining phospholipase A2 with high-pressure homogenization: Physicochemical, structural properties and their effects on foaming, processing stability of egg white protein

In this study, two types of microgel particles from egg yolk components were prepared by combining enzymatic hydrolysis with high-pressure homogenization (HPH), and their differences in physicochemical properties, foaming properties, and microstructure were compared. Results showed that the particle size of both types of microgel particles had decreased from 2744.07 ± 408.26 nm (egg yolk, EY) to 144.97 ± 3.19 nm (PLA2 hydrolyzed egg yolk microgel particles, PYM) and 535.07 ± 46.07 nm (egg yolk microgel particles hydrolyzed by PLA2, YMP), from 736.24 ± 34.61 nm (EG) to 182.76 ± 4.12 nm (PLA2 hydrolyzed egg yolk granules microgel particles, PGM) and 443.98 ± 27.09 nm (egg yolk granules microgel particles hydrolyzed by PLA2, GMP). Besides, their interfacial adsorption abilities were significantly improved, reflected in the increase values in overrun, from161.90 % ± 9.84 % (EY) to 269.64 % ± 16.73 % (PMY) and 307.20 % ± 16.09 % (YMP), from 189.21 % ± 5.02 % (EG) to 280.38 % ± 36.05 % (PGM) and 261.91 % ± 34.03 % (GMP). Their structural properties showed higher stabilities after treatments. When the microgel particles are applied to cakes, the specific volume was increased from 2.05 ± 0.1 mL/g (EY) to 2.25 ± 0.13 mL/g (PYM) and 2.45 ± 0.03 mL/g (YPM), and from 2.00 ± 0.09 mL/g (EG) to 2.51 ± 0.13 mL/g (PGM) and 2.75 ± 0.21 mL/g (GMP), respectively. The hardness and chewiness were reduced with both types of microgel particles from egg yolk components, which indicated their potential value as edible foam stabilizers in the baking industry.

Effects of ultrasound pretreatment on the structure, IgE binding capacity, functional properties and bioactivity of whey protein hydrolysates via multispectroscopy and peptidomics revealed

Whey protein is an important food ingredient, but it is also considered a major food allergen. The aim of this study was to investigate the effect of ultrasound pretreatment on the structure, IgE binding capacity, functional properties and biological activity of whey protein isolate (WPI) hydrolysates (WPH), including WPI hydrolyzed by a combination of enzymes from Bromelain and ProteAXH (BA-WPI) and WPI hydrolyzed by a combination of enzymes from Papain W-40 and ProteAXH (PA-WPI). The IgE binding capacity of BA-WPI and PA-WPI was reduced to 40.28% and 30.17%, respectively, due to disruption/exposure/shielding of conformational and linear epitopes. The IgE binding capacity of sonicated WPI was increased, but ultrasound pretreatment further reduced the IgE binding capacity of the hydrolysates to 32.89% and 28.04%. This is due to the fact that ultrasound pretreatment leads to conformational changes including increased α-helix and β-sheet structure, exposure of aromatic amino acids, surface hydrophobicity, and increased sulfhydryl content, which increases the accessibility of allergenic epitopes to WPI by the enzyme. Multispectral and LC-MS/MS results further indicated that ultrasound pretreatment altered the conformational and primary structural changes of the hydrolysates. The thermograms showed that ultrasound pretreatment mainly altered the epitope spectra of β-lactoglobulin hydrolysates, while it had less effect on the epitope spectra of α-lactalbumin hydrolysates. Additionally, ultrasound pretreatment significantly improved the foaming properties, antioxidant activity, and α-glucosidase inhibition of the hydrolysates without impairing the solubility and emulsification properties of the hydrolysates. Therefore, ultrasound pretreatment is a feasible method to reduce the allergenicity of WPH and to improve their functional properties and bioactivity. Notably, ultrasonic pretreatment improved the effectiveness and efficiency of WPI hydrolysis, which is a feasible method to produce high-quality protein feedstock in a green, efficient, and economical way.

Complexation of Olive Protein with Soluble Dietary Fibers: A Way to Improve the Functional Properties of Proteins and Efficiently Utilize Olives.

High-value resources beyond oil extraction for the olive industry need to be developed due to increased olive production. Soluble dietary fibers (SDFs) and olive proteins (OPIs) are important components of olives. However, the commercial production process partially damages OPIs' emulsifying and foaming properties. Thus, the preparation of SDF-OPI complexes would help protect and even improve the emulsifying and foaming properties. The effects of pH and thermal-ultrasonic treatment on the complexation were explored, which showed that the SDF-OPI complexes prepared at pH 5 exhibited superior solubility (p < 0.05). SDF addition noticeably improved OPI thermal stability, emulsifying properties, and foaming properties. Moreover, the complexes prepared by thermal-ultrasonic treatment exhibited higher emulsion stability and lower emulsification activity than those prepared without thermal-ultrasonic treatment. In the acidic system, the electrostatic interaction was considered the main driving factor, assisted by the hydrophobic interaction. Additionally, after thermal-ultrasonic treatment, the covalent binding was observed by infrared spectroscopy. These results revealed the interaction mechanism between SDF and OPI, and the complexes significantly enhanced the functional properties of OPI. This study provides a reference for the high-value utilization of olives, thus broadening their potential uses in the food sector and beyond.

Harnessing ultrasonic power to optimize quinoa byproduct protein for sustainable utilization

The objective of this study was to elucidate the impact of ultrasonic treatment on quinoa by-product protein (QBP). Ultrasound treatment resulted in decreases in the moisture, lipid content, water activity, bulk and compact densities, and turbidity of the QBP. This treatment disrupted the compact protein structure and hydrophobic regions, thereby releasing a greater quantity of amino acids. Chemical analysis revealed that subjecting QBP aggregates to 400 W ultrasound transformed them into smaller and more uniformly distributed aggregates. Ultrasound significantly affected the secondary structure of QBP, increasing the relative proportions of α-helix and β-turn, while reducing β-pleated sheet and random coil proportions. Additionally, it altered the intrinsic fluorescence intensity and increased the sulfhydryl-group content. Notably, at 400 W, the protein exhibited optimal solubility, foaming properties, water and oil-binding capacity, and in vitro digestibility. These findings suggest that ultrasonic treatment can effectively enhance the quality and functional characteristics of quinoa protein byproducts, offering new perspectives for the comprehensive utilization of quinoa waste.

Assessing the influence of extrusion processing on functional properties and phytochemical profiles in diverse rice bran varieties

AbstractBackground and ObjectivesThe aims of this study were to assess the functional and phytochemical characteristics, as well as the antioxidant properties, of bran from five distinct rice varieties. Additionally, it evaluated the impact of extrusion cooking on the composition and quantity of individual phytochemicals in both free and bound states in the bran of these varieties.FindingsThe functional properties and phytochemical profiles of raw and extruded rice bran from different rice varieties differed significantly. The extrusion process significantly influenced the color, protein solubility, foaming properties, polyphenolics, and amino acid composition of rice bran. Total phenolics ranged from 3.18 to 4.80 mg GAE/g, increased by 12.6%–17% postextrusion. Similarly, total flavonoid content ranged from 15.22 to 17.37 mg RTE/100 g, with a 30%–33% increase after extrusion cooking. Throughout the extrusion process, a rise in the concentration of free phenolics accompanied by a decrease in the concentration of bound phenolics was observed.ConclusionThe study revealed the impact of extrusion cooking on the distribution of total phytochemicals, particularly phenolics and flavonoids, and the levels of antioxidant activity in free and bound phenolics, as well as amino acid composition and functional properties. The extrusion cooking increased levels of free phenolics and 2,2‐diphenyl‐1‐picrylhydrazyl activity, while bound forms decreased. Extrusion cooking variably impacted the functionality and phytochemical content of bran from different rice varieties, thus influencing their likely applications.Significance and NoveltyThis study established the foundation for producing food products using extruded rice bran, offering health benefits and meeting the growing demand in the functional food sector.

Impact of raw material on thermo‐physical properties of carbon foam

AbstractCarbon foam materials are currently used in several industrial and engineering applications due to their outstanding properties. The properties of carbon foam can be altered through the manufacturing processes applied in specific applications. In this paper, we collected and analyzed four samples manufactured by CFOAM and one sample developed by Ohio University (OU) to understand the behaviour of this material and determine its properties. We utilized advanced techniques to experimentally measure and determine the following properties: pore size and volume, porosity, specific surface area, mass, density, and thermal conductivity. Among the samples, the low‐porosity CFOAM (CF35) and the OU sample exhibited higher specific surface areas and densities compared to the others. However, CF35 demonstrated the highest thermal conductivity, while OU displayed the lowest. As a result, CF35 emerges as the optimal choice for applications requiring high‐rate heat transfer, while the remaining CFOAM samples are well‐suited for lightweight applications. Thus, OU foam proves to be a highly suitable candidate for insulation applications such as building sidewalls.

Multi-scale experimental study on properties of compressed air foam and pressure drop in the long-distance vertical pipe

Compressed air foam has been gradually applied in super high-rise buildings due to its high extinguishing efficiency and great transportation ability. However, the transport characteristics of compressed air foam are unclear because the foam is a complex gas-liquid two-phase fluid. In this study, multi-scale experiments were conducted to investigate the foam properties of compressed air foam and pressure drop in the long-distance vertical pipe. The results show that the foam is compressed as a whole when pressure increases, resulting in a significantly increased foam density. At higher pressures, the bubble coarsening degree decreases, accompanied by a narrower particle size distribution and an increased foam size homogenization. Moreover, a critical pressure phenomenon is observed in foams with different foam expansion ratios. The average foam diameter stabilizes gradually with pressure changes after exceeding the critical pressure. A theoretical model for foam density is developed, considering various pressures, temperatures and foam expansion ratios. When the compressed air foam is transported in the vertical long-distance pipe, the pressure decreases in a slightly downward curve, which is due to the decrease in foam density. Finally, a prediction model for the pressure drop of compressed air foam in the long-distance vertical pipe is proposed, which considers changes in foam density. The accuracy of the prediction model is verified by the multi-scale experimental results. The results deepen the understanding of foam flow in the long-distance vertical pipe and provide useful guidance for applications of compressed air foam in super high-rise buildings.

Effect of diacylglycerol on partial coalescence of aerated emulsions: Fat crystal-membrane interaction and air-liquid Interface interaction insights

Currently, the poor whipping capabilities of anhydrous milk fat (AMF) in aerated emulsion products are a major obstacle for their use in beverages like tea and coffee, as well as in cakes and desserts, presenting fresh hurdles for the food industry. In this study, the mechanism of action of diacylglycerols (DAGs) with different carbon chain lengths and degrees of saturation on the partial coalescence of aerated emulsions was systematically investigated from three fundamental perspectives: fat crystallization, air-liquid interface rheology, and fat globule interface properties. The optimized crystallization of long carbon chain length diacylglycerol (LCD) based on stearate enhances interactions between fat globules at the air-liquid interface (with an elastic modulus E' reaching 246.42 mN/m), leading to a significantly reduced interface membrane strength. This promotes fat crystal-membrane interactions during whipping, resulting in a thermally stable foam structure with excellent shaping capability due to enhanced partial coalescence of fat globules. Although Laurate based medium carbon chain length diacylglycerol (MCD) promoted fat crystallization and optimized interface properties, it showed weaker foam properties because it did not adequately encapsulate air bubbles during whipping. Conversely, oleate long carbon chain length diacylglycerol (OCD) proved to be ineffective in facilitating fat crystal-membrane interaction, causing foam to have a subpar appearance. Hence, drawing from the carefully examined fat crystal-membrane interaction findings, a proposed mechanism sheds light on how DAGs impact the whipping abilities of aerated emulsions. This mechanism serves as a blueprint for creating aerated emulsions with superior whipping capabilities and foam systems that are resistant to heat.

Modification of polyurethane foams with zinc sulfide nanoparticles and their novel composites with multani mitti and charcoal for oil spill cleanup.

With the rapid growth of the automobile industry, the excessive number of industrial pollutants, particularly oil spills, has become a huge threat to the natural environment. Therefore, an environmentally benign and sustainable solution is required for an effective oil spill cleanup. To enhance the sorption capacity of pristine polyurethane (PU) foam used in oil spill cleanup, ZnS nanoparticles were deposited on PU foam via a coprecipitation approach. Additionally, the effect of Fuller's earth, locally known as Multani Mitti (MM), and charcoal (CC) on the sorption properties of the PU foam were investigated and compared. Polyvinyl alcohol (PVA) was used as a binder during the modification procedure. The morphology, chemical composition, and thermal stability of ZnS/MM/PVA- and ZnS/CC/PVA-modified PU sorbents were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and X-ray photon spectroscopy (XPS). The modified PU foam exhibited outstanding properties including a high sorption capacity, high selectivity to different types of used oils such as vegetable oil, hydraulic oil, lube oil, and gear oil, and superior reusability in comparison to pristine PU foam. ZnS/CC/PVA has a sorption capacity of 16.78 g g-1 while ZnS/MM/PVA exhibited a sorption capacity of 16 g g-1. In addition, after 10 cycles of oil sorption-squeezing experiments, the oil sorption capacity remained unchanged, and the absorbed used oil could be removed and collected by an easy squeezing procedure prior to reuse. This work reveals that the ZnS/CC/PVA- and ZnS/MM/PVA-modified PU foams have a promising potential for oil spill removal and environmental protection.