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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.

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.

In this study, the response surface method (RSM) was used to determine the best reaction conditions for the gas-phase hydrogenation of carbon dioxide on a commercial nickel-based catalyst. The RSM was applied in our previous study to find the optimal conditions for the same process carried out in laboratory-scale tubular reactors. The main benefits observed were fast detection of optimal conditions and the high precision of the optimum detected (which was experimentally confirmed). These advantages were due to the small number of experiments conducted and the simplicity of the models employed; only linear and quadratic models were developed. The successful result encouraged us to carry out experiments in a larger-scale reactor—an intermediate between a laboratory plant and a pilot plant. This approach helped us to fix some problems resulting from the larger scale of the process conducted. Despite the difficulties described in the main part of this article, we can recommend using the RSM as a tool for supporting experimentation and substantially speeding up the analysis of results and their introduction into practice. At the process scale considered, maximum carbon dioxide conversion was obtained at a temperature of 354 °C and a ratio of molar fluxes of H₂ to CO₂ equal to 3.9. It should be emphasized that this result was confirmed experimentally.