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Fumaric acid is one of the most important bio-based chemicals, with applications in the food, feed, polymer, pulp, and pharmaceutical industries. To overcome the limitations of the current petrochemical production process, alternative methods are being developed. Biotechnological production using wild-type fungi like Rhizopus sp. is a promising alternative. In this study, apple pomace was used as a carbohydrate source for fumaric acid production using Rhizopus arrhizus NRRL 1526. Our focus was on the use of free, non-structurally bound carbohydrates present in high amounts in apple pomace originating from direct apple juice processing. Three processes were compared: pressing, extraction, and a combination of both. Two cultivation strategies were applied: pre-culture and separate upstream biomass production. Using the pre-culture approach, a fumaric acid titer of 68.3 g/L was achieved with a yield of 0.53 g/g and a productivity of 0.29 g/(L·h) from synthetic apple pomace juice. Separate biomass production enabled growth-decoupled fumaric acid production, yielding 50.2 g/L and 79.3 g/L with yields of 0.82 g/g and 0.54 g/g and productivities of 0.17 g/(L·h) and 0.27 g/(L·h) from synthetic and real apple pomace juice, respectively. Thus, the efficient use of apple pomace for the fermentative production of fumaric acid is shown.

Exploring effective oxygen reduction reaction (ORR) electrocatalysts is essential for advancing solid-state alkaline zinc–air batteries (ZABs). This paper presents the synthesis of silver–manganese dioxide–carbon nanotubes (SMC) ternary composites as an electrocatalyst for air electrodes, achieved through one-step pyrolysis of silver permanganate under microwave irradiation. Characterization techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersion spectrometer (EDS) consistently confirmed the composition of SMC, comprising silver and alpha-manganese dioxide anchored on the surface of carbon nanotubes (CNTs). Electrochemical tests including polarization and chronoamperometry curves demonstrated the superior electrocatalytic activity of SMC for ORR compared to chemically produced electrocatalysts in alkaline conditions. Furthermore, the performance of a solid-state zinc–air cell with SMC as the electrocatalyst was evaluated, showing a long discharge voltage plateau and a capacity of 60.03 mAh at 30 mA·cm⁻². The study also delves into the mechanism behind the enhanced electrocatalytic activity, concluding that the strategy and electrocatalyst developed in this research offer a promising approach for creating efficient oxygen reduction catalysts for solid-state zinc–air batteries.

The stability of perovskite materials in humid conditions significantly hinders their practical deployment. This study employed ab initio molecular dynamics (AIMD) simulations based on the Car–Parrinello approach to elucidate the adsorption mechanisms within two systems: CH₃NH₃PbI₃-15O₂-2H₂O and CH₃NH₃PbI₃-15O₂-5H₂O. The findings indicate that in the system with a higher water content (5H₂O), the degradation of the perovskite skeleton is more severe. Additionally, the adsorption energy of oxygen molecules significantly increases, along with more pronounced charge transfer between the oxygen and the perovskite material. The study also reveals that although water molecules contribute to the damage of the perovskite skeleton, oxygen molecules are the primary culprits. These insights not only clarify the specific impacts of various components in a mixed-gas environment on perovskite stability but also provide an essential theoretical basis for future modifications and optimizations of perovskite materials.