Reduction In Pore Size Research Articles

Impact of cellulose nanofibers on cellulose acetate membrane performance

Membranes find applications across a wide spectrum of industries, including water treatment, energy production, and biomedicine. In this study, nonwoven membranes were fabricated using cellulose acetate (CA) as the primary component, with varying percentages of cellulose nanofibers (CNFs) embedded as reinforcement. These CNFs were prepared through an oxalic acid pretreatment (Oxalic-CNFs). Their incorporation into electrospun membranes represents an innovative approach, enhancing their mechanical properties for applications subjected to high loads and improving its functionalization capabilities. The impact of Oxalic-CNFs on membrane properties was investigated at nanofiber loadings ranging from 0 to 18 wt%. Membranes produced with 6 wt% Oxalic-CNF exhibited the superior physical and mechanical properties. This improvement can be attributed to the formation of threads with higher intrinsic strength, a reduction in pore size, and an increase in density. When higher percentages of CNFs were added, the membranes were not properly formed, because filaments were not continuous and the needle became clogged. The substructure of the membrane proved to be a critical factor for mechanical properties, with remarkable increases in tensile strength and elastic modulus (around 300%) when comparing 4–6 wt% Oxalic-CNF-loaded membranes to CA membranes.

Rosacea is More than Just a Red Face: Microbotox's Role in Minimizing Enlarged Facial Pores for a Rosacea Patient

Enlarged facial pores are a cosmetic concern and a prominent feature of skin aging that impacts patient quality of life. Microbotox has emerged in multiple studies as a solution for reducing pore size and improving skin texture. A case of 29 years old female with papulopustular rosacea and enlarged skin pores was reported. From the patient's anamnesis, it was found that the patient has been complaining of a reddish patch with pimples on the nose and both cheeks for the past 4 years. The patient has also had enlarged pores on both cheeks for the past 3 years. On dermatologic state there were erythematous macule, erythematous papules and enlarged pores on both of the cheek. Global Flushing Severity Score (GFSS) was 3, Investigator’s Global Assessment (IGA) of Rosacea Severity for papules and pustules is grade 2 and erythema grade 2. Visual Assessment for Pore was 6. Patient received a single session of microbotox. Dermoscopy examination showed linear vessels (telangiectasia), a pustule, and also follicles filled with sebum. Follow up of the patient was done for 6 weeks. Patients reported a decrease in issues such as flushing, papules, pustules, and erythema. A noticeable improvement in pore size was also observed. This action can be repeated every 3 months to maintain clinical improvement and good skin texture. Botulinum toxin exhibits a satisfying level of efficacy and safety in rosacea treatment. A single microbotox session proves to be a safe and effective approach for reducing facial pore size, along with notable improvements in skin texture.

Algal cellulose reinforced polyvinyl alcohol composite hydrogel with controlled niacinamide release for cosmeceutical applications

Niacinamide, a multi-functional cosmeceutical ingredient, has been extensively formulated in skincare products. To enhance the efficacy of niacinamide penetration into the skin, numerous hybrid hydrogels and drug delivery systems have been extensively developed as carriers for efficient entrapment and release of niacinamide. However, the mechanical properties and limited capacity of achieving high loading and sustained drug release are predominantly determined by synthetic polymers. Hence, it becomes imperative to develop innovative hybrid materials. Here, we successfully fabricated algal cellulose/Polyvinyl alcohol (PVA) composite hydrogels by employing cellulose extracted from Cladophora spp. and Ulva spp. through alkaline treatment. The physiochemical characteristics and properties of the composite hydrogels including niacinamide entrapment and release efficiency were examined. The results found that reinforcing PVA with algal cellulose resulted in a reduction in pore size with an increase in both number and distribution. The reinforcement also led to enhanced thermal stability and improved swelling properties. The Ulva cellulose/PVA composite hydrogel exhibited a higher swelling ratio and encapsulation efficiency compared to Cladophora cellulose/PVA composite hydrogel. Furthermore, the results of release kinetics confirmed that the Ulva cellulose/PVA composite hydrogel showed the most effective mechanism of niacinamide release from hydrogel, transitioning from non-Fickian to Fickian model. This suggests that it is a suitable material for niacinamide delivery as a cosmeceutical ingredient via the transdermal route. This study implies that the Ulva cellulose/PVA composite hydrogel could serve as a promising vehicle for niacinamide delivery across the skin.

Controlling the Architecture of Freeze-Dried Collagen Scaffolds with Ultrasound-Induced Nucleation.

Collagen is a naturally occurring polymer that can be freeze-dried to create 3D porous scaffold architectures for potential application in tissue engineering. The process comprises the freezing of water in an aqueous slurry followed by sublimation of the ice via a pre-determined temperature-pressure regime and these parameters determine the arrangement, shape and size of the ice crystals. However, ice nucleation is a stochastic process, and this has significant and inherent limitations on the ability to control scaffold structures both within and between the fabrication batches. In this paper, we demonstrate that it is possible to overcome the disadvantages of the stochastic process via the use of low-frequency ultrasound (40 kHz) to trigger nucleation, on-demand, in type I insoluble bovine collagen slurries. The application of ultrasound was found to define the nucleation temperature of collagen slurries, precisely tailoring the pore architecture and providing important new structural and mechanistic insights. The parameter space includes reduction in average pore size and narrowing of pore size distributions while maintaining the percolation diameter. A set of core principles are identified that highlight the huge potential of ultrasound to finely tune the scaffold architecture and revolutionise the reproducibility of the scaffold fabrication protocol.

Preparation of ZrP2O7-CePO4 composite porous ceramics and their excellent thermal insulation and wave-transmission performance for supersonic aircraft

In this study, a two-step method combining the direct foaming process with the control of solid content and heat treatment temperature was employed to prepare ZrP2O7-CePO4 composite porous materials with varying porosities. The results indicate that an increase in solid content and heat treatment temperature leads to a reduction in porosity and average pore size while simultaneously improving the mechanical properties. The porosities, compressive strengths, thermal conductivities, ε and Tanδ ranged from 63.2 to 85.3 vol%, 19.43 to 0.99 MPa, 0.089 to 0.088 W/(m·K), 1.64 to 2.72, and 0.88 × 10−3 to 1.99 × 10−3, respectively. Electromagnetic simulations have validated that ZrP2O7-CePO4 composite porous ceramics, when used as the core layer material for A-sandwich antenna radomes, exhibit excellent transmittance properties. This suggests the potential application of these materials for supersonic aircraft antenna radomes.

Photocatalytic driven ‘self-cleaning’ IPN membranes infused with a ‘host-guest’ pair consisting of metal-organic framework encapsulated anionic ‘nano-clusters’ for water remediation

Traditional water treatment membranes frequently encounter challenges in attaining an ideal equilibrium between permeability and selectivity. The performance of membranes is further hampered by hydrophobicity, scalability, and fouling problems, as well as excessive energy consumption. Hence, the current research is dedicated to the development of highly effective antifouling membranes, aiming for a significant balance between water permeance and separation efficiency, and featuring exceptional photocatalytic self-cleaning properties to ensure the sustainable reuse of membranes. In this study, a unique nanocomposite-based membrane is designed containing metal-organic frameworks (MOFs) MIL-101 (Fe) encapsulated copper-containing polyoxometalate (Cu-POM) incorporated into an interpenetrating polymer networks (IPNs) membrane. POMs are highly electronegative, oxo-enriched nanosized metal-oxygen cluster species and when composited with MOF yields POMOF which can help in the removal of pollutants from water through electrostatic site-specific binding. The IPN membrane designed by polymerizing aniline in the presence of polyvinylidene fluoride (PVDF) offers tunable pores of the membrane. The infusion of POMOF imparts a strong negative charge to the membrane surface, improving membrane hydrophilicity. This enhances pollutant removal through the Donnan exclusion principle and adds anti-fouling properties. Furthermore, the reduced pore size achieved by the IPN architecture in the POMOF@IPNs membrane effectively sieves out both cationic and anionic dyes, as well as pharmaceutical pollutants. Additionally, POMOF enhances the photocatalytic degradation of CR and MB dyes, coupled with essential self-cleaning attributes vital for separation processes. The IPNs structure, apart from housing POMOF, fortifies the membrane's mechanical strength with its distinctive network-like configuration. Furthermore, these advanced membranes showcase robust antibacterial and antiviral characteristics, while remaining non-cytotoxic to mammalian cells. Our findings indicate that the state-of-the-art POMOF@IPNs membrane is scalable and holds substantial promise for industrial wastewater treatment.

Metal ion effect on pore size reduction in Mesoporous Aluminosilicate in the presence of TETA as a template and its catalytic performance of CO2 decomposition at lower temperature

AbstractMesoporous AlSiO4‐33 and Co2+ incorporated Co‐AlSiO4‐15 catalysts are synthesized at room temperature using Triethylenetetramine (TETA) as a template for the purpose of CO2 decomposition. The prepared materials are characterized by FT‐IR, XRD, UV‐DRS, BET, TGA, 27Al NMR and TEM. Based on XRD data, the materials are crystalline in nature. The mesoporosity of the materials with pore sizes of 33 nm (AlSiO4) and 15 nm (Co‐AlSiO4) are confirmed by BET analysis. Consequently, we designated AlSiO4 and Co‐AlSiO4 as AlSiO4‐33 and Co‐AlSiO4‐15. This lowered diameter value for Co‐AlSiO4‐15 may be due to the octahedral coordination of Co2+ ion. In the tetrahedral aluminosilicate framework, the template directs the Co2+ towards octahedral coordination. Due to the octahedral coordination, the bond angle between Si−O−Co is reduced. Due to this reduction, the pore size reduced from 33 nm (AlSiO4‐33) to 15 nm (Co‐AlSiO4‐15). These two catalysts are applied for CO2 decomposition. AlSiO4‐33 is active at 100 °C while Co‐AlSiO4‐6 is active at 150 °C. Co‐AlSiO4‐15 has produced more oxygen than AlSiO4‐33. It may be due to the Co‐AlSiO4‐15 has more bronsted acidic sites than the AlSiO4‐33. Co‐AlSiO4‐15 is reduced the activation energy 67 % while AlSiO4‐33 is reduced 78 % for CO2 decomposition at lower temperatures compare to conventional methods.

Tuning the surface charge and pore size of IPNs arrests covalent organic nanostructures through in situ exchangeable bonds for the removal of persistent contaminants

Novel SH-COF and exchangeable bonds enabled recyclable IPN membrane for effective molecular sieving and water remediation via pore size reduction and surface charge enhancement.

Reduction-enhanced water flux through layered graphene oxide (GO) membranes stabilized with H3O+ and OH- ions.

Graphene oxide (GO) is one of the most promising candidates for next generation of atomically thin membranes. Nevertheless, one of the major issues for real world application of GO membranes is their undesirable swelling in an aqueous environment. Recently, we demonstrated that generation of H3O+ and OH- ions (e.g., with an external electric field) in the interlayer gallery could impart aqueous stability to the layered GO membranes (A. Gogoi, ACS Appl. Mater. Interfaces, 2022, 14, 34946). This, however, compromises the water flux through the membrane. In this study, we report on reducing the GO nanosheets as a solution to this issue. With the reduction of the GO nanosheets, the water flux through the layered GO membrane initially increases and then decreases again beyond a certain degree of reduction. Here, two key factors are at play. Firstly, the instability of the H-bond network between water molecules and the GO nanosheets, which increases the water flux. Secondly, the pore size reduction in the interlayer gallery of the membranes, which decreases the water flux. We also observe a significant improvement in the salt rejection of the membranes, due to the dissociation of water molecules in the interlayer gallery. In particular, for the case of 10% water dissociation, the water flux through the membranes can be enhanced without altering its selectivity. This is an encouraging observation as it breaks the traditional tradeoff between water flux and salt rejection of a membrane.

Thermo‐mechanical performance of wolframite mineral reinforced siloxane‐modified epoxy‐based intumescent coating for structural steel

AbstractThis study investigated the effects of wolframite on the fire resistance and adhesion strength of intumescent fire‐retardant coating (IFRC) using a siloxane‐modified epoxy binder. The modification of bisphenol A epoxy was confirmed via Hydrogen‐Nuclear Magnetic Resonance Analysis. The IFRC samples were developed with wolframite (0.25–2.0 wt%) and evaluated for Thermogravimetric analysis (TGA), fire resistance test, furnace fire test for char expansion, morphology and chemical composition, adhesion test and water immersion test. This study identified a coating formulation containing 2.0 wt% of wolframite that showed 57.2% improvement in the residual weight, substrate temperature of 176.7°C and produced a compact char. Field Emission Scanning Electron Microscopy showed that the addition of wolframite reduced pore size thereby increasing the char strength. X‐ray diffraction identified iron neodymium compounds in the char layers, which lowered the pore size resulting in lower substrate temperature. X‐ray photoelectron spectroscopy indicated that the antioxidant capability and the carbon content were increased by 6.9% and 50.3% respectively. The adhesion strength was reduced, however, was within the industrial standards of 2.07 MPa. The water immersion test showed a maximum 66.7% reduction (WF2.0) in the water permeation through the coating.

Enhancing concrete resilience and sustainability through fly ash-assisted microbial biomineralization for self-healing: From waste to greening construction materials

This study presents a pioneering approach that enables remarkable crack closure up to 0.8 mm through stimulated biomineralization aiming to enhance the self-healing capacity of concrete. The innovative synergy tackles the pressing environmental challenges head-on investigates the intriguing germination process of endospores in a cementitious environment and underscores the function of calcareous fly ash in promoting Microbially Induced Calcium Carbonate Precipitation (MICP) by providing additional Ca2+ ions, that are converted into carbonate phases through bacterial metabolic processes. These phenomena are thoroughly examined using an in-situ model particularly concerning MICP in bio-concrete, and thermodynamic modelling is performed to forecast the influence of fly ash on the quantity of Ca-bearing (carbonation sensitive) phases present in the hydrated phases of fly ash-blended cement system. Incorporating 30 % class C fly ash significantly amplifies the biomineralization activity, with 6.5 % calcium carbonate deposition in bio-concrete leds to significant healing activity. Concurrently, MICP contributes to a significant reduction in pore sizes, thereby enhancing the overall durability of concrete. Beyond structural improvements, this innovative bio-concrete formulation showcases an impressive 39 % reduction in CO2 emissions, aligning with sustainability goals. Additionally, repurposing fly ash, typically consigned to landfills, seamlessly adheres to the tenets of a circular economy, despite incurring a 7 % rise in the initial production cost. That promising advanced methodology can deliver transformative environmental benefits, ushering in a paradigm shift in sustainable construction practices, and finding the synergistic interplay between microbial activity and calcium-dependent fly ash.

Fluorocarbon-driven pore size reduction in polyurethane foams: an effect of improved bubble entrainment

Fluorocarbon-driven pore size reduction in polyurethane foams: an effect of improved bubble entrainment

Breaking Free - Unlocking the Potential of Dynamic Hydrogen Bubble Templating Materials

In recent years, porous electrodes for electrochemical conversion devices, such as low-temperature fuel cells or water electrolyzers, have been engineered to address issues related to mass transport to and within the catalyst. For example, the addition of a layer with reduced pore size facing the catalyst layer (i.e., microporous layer) results in an increased performance[1–3]. Furthermore, chemical[4], as well as mechanical[5,6]. methods of creating dedicated liquid and gas pathways in the porous electrodes, have been investigated with promising results, highlighting the need for further optimization of state-of-the-art materials with regards to multi-phase transport. The range of possible modifications is intrinsically limited by the microstructure of the material they are applied to and add cost and complexity to the already costly electrode production procedure, motivating the development of novel materials which contain these desired features, offer a large morphological design space, and are cost competitive.To tackle these stringent targets, we investigate the dynamic hydrogen bubble templating (DHBT) method to generate hierarchical structures containing both a pore size gradient as well as dedicated water and gas pathways in the form of bimodal pore size distributions. It leverages simultaneous deposition of a metal and gas evolution on the same surface to form complex structures from solution using electricity. It results in a hierarchical structure of primary pores (~5-40 µm) separated by porous walls containing secondary pores (10-1000 nm) . This type of material has been used successfully to improve boiling heat transfer[7], another process limited by the counterflow of liquid and gas. They have also been investigated as high surface area material for microbial anodes[8] and have been postulated to be appealing in other electrochemical devices such as batteries or fuel cells[9]. A significant hurdle to unlock the full potential of DHBT foams is the attachment of the foam to the solid electrode surface it is generated on. The presence of the electrode blocks the transport of media in the through-plane direction of the foam and thereby prevents its use in many electrochemical applications. Due to its fragile nature, separation of the foam from this surface easily damages the structure, which is why previous research was done exclusively in the presence of the electrode. Overcoming this limitation would enable new applications for DHBT foams and has the potential to address a wide range of problems in electrochemical systems related to porous media.In this talk, I will discuss our work towards creating free-standing, hierarchically structured metal electrodes through DHBT and the developments needed to adapt this material for the use in electrochemical systems. Owing to its well-studied synthetic parameters and facile electrodeposition, we chose copper foams to advance DHBT materials in terms of characterization and mechanical properties. As a key step of the synthesis route, we realized a method to manufacture free-standing sheets from this material from copper metal while preserving its delicate microstructure. This was supported by an optimization of synthesis parameters to improve and ensure adequate mechanical stability of the freestanding foams after isolation. This development enables the application of a wide range of characterization methods such as XTM, BET, SEM and interferometry and I will discuss how the synthesis parameters link to the resulting material microstructure. Building on this initial success, current work focuses on the transferring this knowledge to the synthesis of foams made from other metals which are more relevant to electrochemical applications such as nickel for the use in alkaline electrolyzers and paves the way to develop DHBT material into the next generation transport layer for electrochemical systems.

Structural Formation and Pore Control of Freeze-Cast Directional Graphene Aerogel (DGA).

Directional graphene aerogels (DGAs) are proposed as electrode materials to alleviate ionic and mass transport issues in organic redox flow batteries (ORFBs). DGAs with high pore directionality would provide low resistance channels for effective ionic charge and liquid electrolyte transport in these devices. DGAs' porous and directional characteristics can be controlled by the growth of ice crystals during freeze casting, which is influenced by the self-diffusivity of water, phase change driving forces, water-ice graphene interactions, and convection in the water-graphene media. It is found that mass transport-related properties of DGAs, including pore size and directionality, show a significant dependence on freezing temperature, graphene oxide (GO) loadings, and synthesis vessel diameter-to-height ratio (D/H). For the freezing temperature change from -20 to -115 °C, the average pore size progressively decreased from 120 to 20 μm, and the pore directionality transitioned from lamellar to ill-defined structures. When GO loadings were increased from 2 to 10 mg/mL at a fixed freezing temperature, pore size reduction was observed with less defined directionality. Furthermore, the pore directionality diminished with an increased width-to-height aspect ratio of DGA samples due to the buoyancy-driven convective circulation, which interfered with the directional ice/pore growth. Understanding the comprehensive effects of these mechanisms enables the controlled growth of ice crystals, leading to graphene aerogels with highly directional microstructures.

Influence of Anatomy, Microstructure, and Composition of Natural Fibers on the Performance of Thermal Insulation Panels.

The growing interest in environmentally friendly materials is leading to a re-evaluation of natural fibers for industrial applications in order to meet sustainability and low-cost objectives, especially for thermal insulation of buildings. This paper deals with the chemical and physical characterization of fibers extracted from seagrass (Posidonia oceanica) and alfa grass (Stipa tenacissima) for a possible substitution of synthetic materials for thermal insulation. Hemp (Cannabis sativa), a fiber broadly used, was also studied for comparison. The parameters characterized include porosity, thermal degradation, elemental composition, skeletal and particle density of the fibers as well as investigation of the thermal conductivity of fiber-based panels. Several technologies were involved in investigating these parameters, including mercury intrusion, thermogravimetric analysis, fluorescence spectroscopy, and fluid pycnometry. The fibers showed a degradation temperature between 316 and 340 °C for Posidonia, between 292 and 326 °C for alfa, and between 300 and 336 °C for hemp fibers. A high porosity allied with a reduced pore size was revealed for Posidonia (77%, 0.54 μm) compared to hemp (75%, 0.61 μm) and alfa (57%, 2.1 μm) raw fibers, leading to lower thermal conductivity values for the nonwoven panels based on Posidonia (0.0356-0.0392 W/m.K) compared to alfa (0.0365-0.0397 W/m.K) and hemp (0.0387-0.0427 W/m.K). Bulk density, operating temperature, and humidity conditions have been shown to be determining factors for the thermal performance of the panels.

Constructing hierarchically elongated porous structure in ultrathin ultrahigh molecular weight polyethylene membrane: Achieving high selectivity with remained permeability

Anisotropic pores with a high aspect ratio exhibit higher permeability as well as selectivity than circular pores. Herein, highly selective porous membranes exhibiting elongated slit-like pores and disk-like interlayer large pores are fabricated successfully by biaxial stretching and further constrained uniaxial stretching of ultrahigh molecular weight polyethylene gel films. The thickness and the surface roughness of the porous membrane decrease, and the pore size distribution become narrow during biaxial stretching, while the porous structure become elongated during constrained uniaxial stretching. The thickness decreases from 173.23 μm to 2.33 μm, which reduces the resistance to water passage and then increases the water permeability from approximately 540 L/ (m2 h bar) to 780 L/ (m2 h bar). Due to the presence of mineral oil, the porosity is maintained and even high ratios of constrained uniaxial stretching do not close the pores. The elongation of the porous structure resulted in a significant reduction of the membrane pore size. At a total stretching ratio of 144 times, the pore size of the porous membrane with only biaxial stretching is 0.098 μm, while that of the porous membrane with biaxial stretching and further constrained uniaxial stretching is 0.048 μm. The separation accuracy and stability of the porous membrane improve distinctly, ascribing that the small pore size can reject small particles and prevent the particles from entering the membrane. This study provides one novel strategy to regulate the porous structure of porous polymer membranes for improving the separation efficiency.

Exploration of a two-stage polymerization mechanism in construction of dense polyester membranes for drinking water treatment

Due to the relatively low reactivity of hydroxyls with acyl chloride groups, the synthesized polyester (PE) membranes commonly have loose structures, only capable of removing large-molecule organics with low rejection of inorganic salts. In this study, the pore size reduction of the synthesized PE membrane was successfully achieved by optimizing the interfacial polymerization (IP) reaction between erythritol and trimesoyl chloride (TMC). The optimized membrane was able to maintain a high xylose rejection (∼60 %) and acceptable water permeance (7.85 L m−2 h−1 bar−1), which was suitable for drinking water treatment. Through comprehensive characterizations, a two-stage membrane formation process was demonstrated regarding the reaction between aqueous monomers with different reactive functional groups and TMC. The highly reactive primary hydroxyls more preferentially participated in the initial reaction stage, leading to a linear cross-linking pattern of polyester. When the molecular diffusion was inhibited, the participation of secondary hydroxyls made the reaction proceed toward partial or full cross-linking. The distinct roles of the two kinds of hydroxyl groups were further verified by the energy barrier differences obtained by density functional theory (DFT) calculation. The exploration of membrane-optimized preparation and formation mechanisms can promote the structural regulation and tailored synthesis of PE membranes for various applications.

Study on the Residence Time and Texture Prediction of Pea Protein Extrusion Based on Image Analysis.

This paper initially involves three main processing parameters: screw speed, feeding speed, and initial material moisture content, exploring the RTD of materials inside the extruder barrel under varying parameters and clarifying the impact of parameter variations on RTD. Finally, machine vision technology was utilized to link extruded product images to texture features, and a texture prediction model based on image features was established using a Back Propagation (BP) neural network. Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) were applied to optimize the BP neural network. The results indicate that the feeding speed has a stronger impact than the screw speed on the extrusion process, and an increase in the initial material moisture content tends to shorten the RTD. Specifically, an increase in screw speed results in a denser product structure, while higher feeding speeds lead to reduced pore size in the microstructure. As the initial material moisture content increased from 55% to 70%, the average residence time MRT decreased from 265.21 s to 166.62 s. Additionally, elevated moisture content causes a more porous microstructure. After optimizing the texture prediction model of extruded products through the application of Particle Swarm Optimization and Genetic Algorithm models, it was discovered that the Genetic Algorithm was more effective in reducing errors (p < 0.05) than the Particle Swarm Optimization algorithm. It was found that the Particle Swarm Optimization model exhibited better prediction performance. The results of the prediction indicated a significant association between the image features of the product and hardness, resilience, and chewiness, as corroborated by correlation coefficients of 0.93913, 0.94040, and 0.94724, respectively.

Can cryogenic freezing preserve the quality of fruit matrices during long-term storage compared to the mechanical method?

This study compares cryogenic freezing (–80 °C and 0.5 m/s air velocity) and mechanical freezing (–40 °C and 4 m/s air velocity) conditions/methods on the quality of melon and apple tissues during a 90-day storage. Samples were analysed on the 7th, 30th, 60th, and 90th day for various qualities: pH, TSS, titratable acidity, total quality index, enzymology, vitamin C, firmness, colour, exudate, soluble protein, and microstructure. Results show pH, °Brix, titratable acidity, and total quality index changes after freezing. Trends differed between melon and apple. Melon pH increased after freezing, while apple pH decreased. Titratable acidity decreased post-freezing for both. °Brix in melon initially decreased but increased in apples with longer storage. Freezing conditions and storage durations affected total quality index. Melon firmness increased, while apple firmness decreased compared to fresh samples post-freezing. Freezing condition did not affect firmness, but storage duration impacted it. Colour was influenced by both freezing treatment and methods, as well as the duration of frozen storage for melons. The L* value decreased for both matrices following freezing treatment. The a* and b* values of apples increased after post-freezing treatment compared to fresh. The a* value of fresh and cryogenically frozen melons was similar. Colour differences were more pronounced for mechanically frozen samples, increasing during storage for apples, while a fluctuating trend was observed for melons. Apple samples exhibited a reduction in polyphenol oxidase (PPO) activity post-freezing, while peroxidase activity (POD) displayed some increase in melons. PPO activity was lower for cryogenic freezing, decreasing with storage, while POD activity was storage-duration impacted. Exudation was lower in cryogenic freezing for both matrices. Soluble protein content was higher in cryogenic frozen samples, though fluctuating. Cryogenic freezing slightly reduced pore sizes in apples, preserving microstructure better, unlike mechanical freezing which damaged cellular structure.

Investigation of the electrochemical performance of Mg-ion batteries based on PVDF-HFP thin polymer electrolyte films

In the present work, poly(vinylidene fluoride-hexafluoropropylene):magnesium trifluoromethanesulfonate (PVDF-HFP:MgTf) polymer electrolytic films with a porous structure were developed using the solution-casting method. With its high performance and versatility, PVDF-HFP has been widely employed in the development of solid polymer electrolyte films (SPEFs). In this study, metal salt particles are successfully included as an inorganic filler into solid PVDF-HFP films, reducing pore size and boosting the amorphous character of the films. Fourier transform infrared spectroscopy is used to examine the chemical structure of the produced SPEFs, and scanning electron microscopy is used to evaluate the surface morphology and locate pores in the SPEFs. The surface nature of the PVDF-HFP films and the PVDF-HFP:MgTf is confirmed by X-ray diffraction. The electrochemical stability of PVDF-HFP and PVDF-HFP:MgTf films is studied through a differential scanning calorimetry experiment. Results revealed that PVDF-HFP:MgT films could be stabilized when filled with electrolytes and electrodes and made less porous by adding inorganic salt particles. Further, electrochemical impedance spectroscopy is used to measure electrical conductivity between 303 and 423 K. At room temperature, PVDF-HFP and PVDF-HFP/Mg2+ SPEFs have optimal ionic conductivities of 3.38 × 10−7 and 1.08 × 10−6 SS ccmm−1−1 respectively. Ionic conductivity was found to increase with temperature. The modulus of the imaginary part of the loss tangent (M′ and M″) was found to be related to dielectric and conductivity relaxation.