.
Development of bio-based materials with advanced properties is required to replace synthetic and per- and polyfluoroalkyl-based ingredients, particularly for applications involving solid-liquid-gas interfaces. To enable alkaline-resistant materials with tunable aerophobicity, bio-based chitosan/dialdehyde starch hydrogels were prepared through covalent Schiff base crosslinking. Chitosan molecular weight (250-1800 kDa) and concentration (1.5-4.0% w/v) were varied at fixed crosslinker content (1.0% w/v) to investigate the effect on network formation, viscoelasticity and functionality. Rheological analysis shows that systems with low chitosan content require long gelation times (>30 min) to form viscous materials with storage moduli of 1 Pa and internal porous structure (10-100 μm). In contrast, highly concentrated chitosan gels formed rapidly (<4 min) reaching up to 150 Pa, indicating improved structural strength. Swelling experiments on freeze-dried hydrogels at pH 6.8, 10, and 12 showed water absorption with swelling ratios ranging from 5000 to 1300%, depending on composition. Most systems maintained structural stability over the 7-day swelling test, undergoing limited degradation in alkaline conditions (pH 12). Aerophobicity was evaluated by measuring contact angles of bubbles on submersed (in water or pH 12) hydrogels, which range from 130 to 170°, increasing with both chitosan concentration and molecular weight. The material features were demonstrated for electrode development, improving performance at higher overpotentials (−0.67 V) and increasing alkaline water-splitting efficiency by 15%. The prepared materials thus provide alkaline resistance and tunable properties offering potential for various applications, including gas-evolving electrode coatings, alkaline electrolyzer membranes, anti-corrosion coatings, pollutant absorption, environmental remediation, and sensing technologies.
Low-Temperature Proton Exchange Membrane Fuel Cells (LT-PEMFCs) are key to sustainable energy technologies, but their performance is highly dependent on cathode operating conditions and membrane hydration. This study employs Electrochemical Impedance Spectroscopy (EIS) and the Distribution of Relaxation Times (DRT) to analyze the effects of cathode stoichiometry, temperature, cathode feed composition, and hydration levels on key electrochemical processes. The findings highlight the impact of operational parameters on oxygen reduction reaction (ORR) kinetics, proton transport, and mass transport resistance. DRT analysis identifies flooding and membrane drying as dominant performance-limiting phenomena. Pure oxygen feed mitigates mass transport limitations, while variations in air stoichiometry and temperature influence charge transfer resistance and proton conductivity. This study enhances understanding of LT-PEMFC behavior under diverse conditions and provides insights for optimizing performance and durability. The results provide diagnostic features and fundamental insights that can guide the development of future diagnostic frameworks for improved fuel cell control, enhanced water management strategies, and long-term operational stability.
Orange peel waste, a byproduct of the citrus industry, can be valorized to obtain valuable compounds such as limonene, a terpene widely used in the food and cosmetics industry for its characteristic citrus aroma. Conventional extraction methods rely on organic solvents, which pose significant environmental concerns. To address this, deep eutectic solvents (DES) have emerged as a sustainable alternative. In this work, we screened various DES combinations using the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS), and the most promising systems containing compounds that are Generally Recognized as Safe (GRAS) or accepted by the Cosmetic Ingredient Review (CIR) were subsequently investigated experimentally. Polyethylene glycol 200 and 600 in combination with amino acids, sugars, carboxylic acids and urea were used for DES formulation. Among them, PEG200-urea showed a significantly higher extraction yield of limoneneper g of orange peel (2.7 mg g-1) which is approximately 1.4x higher than that obtained with the reference organic solvent, heptane (1.9 mg g-1). The limonene extracted with DES remained stable for at least five weeks when stored at room temperature and in the dark. In addition, hesperidin, a high-value flavonoid for cosmetic applications, was successfully quantified in the extracts, while bergapten (a phototoxic furanocoumarin) and several limonene oxidation products were not detected. Our results show that DES can achieve limonene yields comparable to, or higher than those of conventional extraction systems while presenting more sustainable metrics. This study emphasizes the potential of DES for the sustainable limonene extraction from dried orange peels and contributes to circular economy initiatives.
Biological membranes are crucial for cellular integrity and function, but their selective permeability can be compromised by various peptides and proteins, such as antimicrobial peptides (AMPs) and pore-forming proteins/toxins (PFPs/PFTs). These molecules induce membrane permeabilization through diverse mechanisms, ranging from the formation of well-defined pores to more nuanced disruptions of the lipid bilayer. Understanding molecular mechanisms underlying membrane integrity disruption is vital for developing novel tools to be applied in medicine, biotechnology, and agriculture. However, due to their transient and dynamic nature, characterizing membrane-disrupting mechanisms is a significant experimental challenge. In silico methods, particularly all-atom and coarse-grained molecular dynamics (MD) simulations, are an indispensable tool to complement and enrich experimental studies, and can offer detailed insights into peptide/protein-membrane interactions, insertion, oligomerization, and pore formation. This review provides a comprehensive overview of the structural and mechanistic diversity of AMPs and PFPs, highlighting representative case studies and discussing key challenges emerging from MD simulations.
Transforming ammonia (NH3) synthesis from the energy-intensive, fossil-fuel-dependent conventional Haber-Bosch (HB) process to a flexible, green hydrogen-based process is pivotal for decarbonization and enabling NH3 utilization in the energy sector. The conventional HB process, operating under high temperature and pressure, is incompatible with green hydrogen systems and economically unviable for downscaled NH3 production integrated with intermittent renewable energies . Therefore, developing alternatives capable of synthesizing NH3 under moderate conditions is crucial for achieving green NH3 production. This necessity has driven the development of a range of emerging technologies, including thermocatalytic, electrocatalytic, photocatalytic, and plasma-assisted processes, amongst which thermocatalysis stands out in terms of production rate, technology readiness, and economic feasibility, demonstrating the greatest potential for NH3 synthesis transformation. This review provides a comprehensive overview of advanced thermocatalytic NH3 synthesis beyond conventional HB process and the system integration with renewable sources. It highlights key limitations and advances in implementing new materials and auxiliary techniques, outlining the challenges and mitigation strategies for achieving high NH3 productivity under mild conditions. Alongside multiscale modeling studies, the review covers catalyst development, reactor intensification, process integration, and system evaluation, examining progress and conducting meta-analysis in reaction mechanisms, emerging separation technologies, and system integration. Scientific obstacles, economic analysis, and environmental impacts are thoroughly discussed, offering state-of-the-art insights into mild NH3 synthesis from fundamental research to practical applications. Additionally, recent industrial projects of green NH3 production are summarized, showcasing scalability and commercial viability. Finally, the remaining challenges and opportunities in advanced thermocatalytic NH3 synthesis are outlined, identifying future research frontiers.
