Open Access

This paper shows how probabilistic limit analysis of statically indeterminate frame structures can be done with the same simplicity as the deterministic limit analysis.

Bioelectrochemical systems (BESs) offer a sustainable method for chemical production, including the enhanced production of succinic acid. By combining fermentation with BES, it could be possible to achieve sustainable succinic acid production and CO2 fixation using Actinobacillus succinogenes. In literature, the potential application of BES is commonly associated with increased succinate yields, as it is expected to enhance the availability of NADH, thereby influencing the intracellular nicotinamide adenine dinucleotide (NADH/NAD+) balance. However, it remains unclear whether BES can improve NADH regeneration and achieve higher NADH/NAD+ ratios across all growth phases of A. succinogenes. This study investigates the impact of an applied electrical potential on the intracellular NADH/NAD+ ratio during an electrochemical-assisted fermentation process. Using an adapted high-performance liquid chromatography method with a Supelcosil LC-18-T column, it was demonstrated that NADH availability in BES, particularly during the stationary growth phase, improved by up to 1.98-fold compared to the control. This enhancement in reducing power led to a succinate yield of 0.747 ± 0.01 g g−1, representing a 15.65% increase compared to a fermentation without electrochemical assistance. These findings support the expectation that the use of BES could enhance the competitiveness of bio-based succinate production.

Many industrial processes are performed using harmful chemicals. The current technical synthesis of N-acyl-amino acids relies on acyl chlorides, which are typically obtained from phosgene chemistry. A greener alternative is the application of whole cells or enzymes to carry out synthesis in an environmentally friendly manner. Aminoacylases belong to the hydrolase family and the resolution of racemic mixtures of N-acetyl-amino acids is a well-known industrial process. Several new enzymes accepting long-chain fatty acids as substrates were discovered in recent years. This article reviews the synthetic potential of aminoacylases to produce biobased N-acyl-amino acid surfactants. The focus lays on a survey of the different types of aminoacylases available for synthesis and their reaction products. The enzymes are categorized according to their protein family classification and their biochemical characteristics including substrate spectra, reaction optima and process stability, both in hydrolysis and under process conditions suitable for synthesis. Finally, the benefits and future challenges of enzymatic N-acyl-amino acid synthesis with aminoacylases will be discussed.

This paper deals with the problem of determining the optimal capacity of concentrated solar power (CSP) plants, especially in the context of hybrid solar power plants. This work presents an innovative analytical approach to optimizing the capacity of concentrated solar plants. The proposed method is based on the use of additional non-dimensional parameters, in particular, the design factor and the solar multiple factor. This paper presents a mathematical optimization model that focuses on the capacity of concentrated solar power plants where thermal storage plays a key role in the energy source. The analytical approach provides a more complete understanding of the design process for hybrid power plants. In addition, the use of additional factors and the combination of the proposed method with existing numerical methods allows for more refined optimization, which allows for the more accurate selection of the capacity for specific geographical conditions. Importantly, the proposed method significantly increases the speed of computation compared to that of traditional numerical methods. Finally, the authors present the results of the analysis of the proposed system of equations for calculating the levelized cost of electricity (LCOE) for hybrid solar power plants. The nonlinearity of the LCOE on the main calculation parameters is shown

This work examines the electrochemically enhanced production of succinic acid using the bacterium Actinobacillus succinogenes. The principal objective is to enhance the metabolic potential of glucose and CO2 utilization via the C4 pathway in order to synthesize succinic acid. We report on the development of an electro-bioreactor system to increase succinic acid production in a power-2-X approach. The use of activated carbon fibers as electrode surfaces and contact areas allows A. succinogenes to self-initiate biofilm formation. The integration of an electrical potential into the system shifts the redox balance from NAD+ to NADH, increasing the efficiency of metabolic processes. Mediators such as neutral red facilitate electron transfer within the system and optimize the redox reactions that are crucial for increased succinic acid production. Furthermore, the role of carbon nanotubes (CNTs) in electron transfer was investigated. The electro-bioreactor system developed here was operated in batch mode for 48 h and showed improvements in succinic acid yield and concentration. In particular, a run with 100 µM neutral red and a voltage of −600 mV achieved a yield of 0.7 gsuccinate·gglucose−1. In the absence of neutral red, a higher yield of 0.72 gsuccinate·gglucose−1 was achieved, which represents an increase of 14% compared to the control. When a potential of −600 mV was used in conjunction with 500 µg∙L−1 CNTs, a 21% increase in succinate concentration was observed after 48 h. An increase of 33% was achieved in the same batch by increasing the stirring speed. These results underscore the potential of the electro-bioreactor system to markedly enhance succinic acid production.