University of Applied Sciences Bingen

The design of physics-augmented neural networks (PANNs) for the purposes of constitutive modeling has received considerable attention as of late for a variety of material behaviors. Here, we revisit the classical framework of isotropic incompressible hyperelasticity in light of recent advances in the study of constitutive inequalities. We show that polyconvexity implies true-stress-true-strain monotonicity for a large class of incompressible strain-energy functions. The resulting elastic law obeys the physically reasonable Legendre-Hadamard (or ellipticity) condition as well as the notion of increasing stress with increasing strain. These results then inform the architecture of four distinct PANNs which are subsequently calibrated to three different sets of experimental data each. We show that different PANN parametrizations – satisfying the same constitutive constraints a priori – have varying approximation power for the description of material behavior. Moreover, even when distinct parametrizations perform comparatively well within the calibration regime, they show pronounced differences in extrapolation. This observation motivates a critical discussion about the predictive power of PANNs which also has implications for the modeling of more complex material behavior by virtue of neural networks.

A total of 192 weaned piglets (Topigs TN70), 26 days of age, with an initial body weight of 7.2 ± 0.5 kg, were used to determine the standardized ileal digestible (SID) histidine (His) to lysine (Lys) ratio required to maximize growth performance. Six dietary treatments with graded SID His to Lys ratios ranging from 0.2 to 0.38 were generated with the supplementation of L-His to a grain-based basal diet deficient in His. At the end of the trial (day 41 post weaning), 72 male piglets were euthanized for the analysis of histidine-containing dipeptides, particularly carnosine, in the M. longissimus dorsi. In addition, blood samples were collected from 72 piglets to determine plasma urea-nitrogen and hematological parameters. Piglets fed low dietary His (SID His to Lys < 0.27) exhibited hemoglobin concentrations below the reference value, indicating anemia. Muscle carnosine content increased linearly with increasing dietary His and did not reach a plateau within the tested range. Based on growth performance responses, the SID His to Lys ratio required to achieve maximum growth performance in fast-growing piglets is 0.34. These findings emphasize the importance of supervising the SID His to Lys ratio, particularly in practical piglet feed formulations.

Global population growth is expected to increase poultry meat demand, intensifying the need for sustainable protein sources. Soybean meal, the primary protein feed for poultry, has negative associations with deforestation and long transport distances. Duckweed has emerged as a possible, more sustainable alternative due to its high growth rate and protein yield. The nutrient digestibility and performance effects of the duckweed species Lemna minor (L. minor) in broiler diets were investigated in two experiments. Experiment 1 determined the ileal digestibility of crude protein, amino acids, phosphorus, and metabolizable energy in L. minor. The digestibility of most amino acids in L. minor ranged from 70% to 96%, with lysine and methionine at 87% and 86%, respectively. At 48%, the digestibility of cysteine was markedly lower than that of the other amino acids. However, the digestibility of P exceeded 90%. The energy values of dry matter were 7.05 MJ AME and 6.13 MJ. Experiment 2 tested the inclusion of L. minor (up to 10%) in isoenergetic and isonitrogenous diets. No significant effects on nutrient digestibility, weight gain, feed intake, or feed conversion ratio were observed. Both experiments demonstrate that L. minor cultivated under controlled conditions is a highly digestible, reliable feed source. Its inclusion in broiler diets is feasible, as it does not impair performance, yet provides amino acid balance whilst ensuring biomass quality. These findings support L. minor as a novel protein alternative and warrant further research on higher inclusion rates.

This study investigates the corrosion behaviour of a WC-6Co cemented carbide (94 wt% WC, 6 wt% Co) in acidic (pH 2) and alkaline (pH 13) electrolytes used for industrial PVD coating removal. The removal of the coating was not investigated, since no coatings were applied or analysed in this study. The objective was exclusively to simulate the corrosion response of the exposed substrate after the coating had been removed during electrochemical stripping. Potentiodynamic polarisation measurements were performed from OCP -0.2 V to +3 V at a scan rate of 1 mV.s(-1), followed by surface characterisation using SEM/EDS and laser profilometry to identify corrosion mechanisms and quantify material degradation. In an acidic solution, corrosion was dominated by cobalt dissolution, followed by the formation of a W-O-rich corrosion-product layer, as indicated by increased tungsten and oxygen contents in SEM/EDS analyses. The layer became increasingly porous and mechanically unstable at higher potentials. Progressive thickening of the corrosion-product layer and subsequent breakdown resulted in significant material loss, including surface abrasion up to similar to 8 mu m. In alkaline electrolytes, SEM/EDS analyses revealed a Co-O-rich surface layer, suggesting cobalt-containing hydroxide/oxide corrosion products. These results suggest that surface-layer formation on WC-Co does not necessarily provide reliable corrosion protection, as stability and morphology strongly depend on pH. These findings provide valuable guidance for the use of cemented carbides in electrochemical stripping processes for PVD coating removal.

Abstract The rearing of black soldier fly larvae represents a sustainable approach to organic waste valorisation and animal feed production. However, substrate composition is known to influence larval growth, nutrient assimilation and body composition. This study evaluated the effects of seven food industry by-products – carrot scraps, grape pomace, biscuit meal, bread crumbs, wheat bran, wheat pulp and rapeseed cake – compared to the standard Gainesville diet under commercial rearing conditions. Larvae were maintained in 144 containers (approximately 14 000 larvae per container) within a climate-controlled room. Each of the eight treatments was replicated 18 times, with six replicates harvested on days 4, 8 and 12 post-hatching for analysis. Substrate type significantly affected growth, survival and feed conversion, with interactions between substrate and harvest time ( ). Wheat bran yielded the highest survival rate, biomass gain and feed conversion efficiency, whereas carrot scraps and grape pomace resulted in the lowest values. Nitrogen retention was greatest in larvae fed wheat bran, while wheat pulp and rapeseed cake showed the lowest retention. Biscuit meal and bread crumbs improved energy retention compared to carrot scraps and grape pomace. Frass composition closely reflected substrate nutrient profiles, particularly nitrogen and energy content. Harvest timing also significantly influenced both larval and frass composition. These findings highlight the critical role of substrate selection in optimising nutrient utilisation, growth performance and biomass yield in BSFL production.