The rapid growth of offshore wind energy, motivated by the demand for sustainable energy solutions and the aim of achieving greenhouse gas neutrality, has led to increased attention to the impact of marine biofouling on substructures such as monopiles and jacket structures. Although the effects of hard biofouling have been studied, soft biofouling remains underexplored. This study investigates flow dynamics and vorticity patterns around eight cylindrical structures subjected to wave loading, with hard and soft biofouling surrogates. Soft biofouling is further divided into stiff and flexible models. Physical experiments are conducted with slender piles (D/L = 0.07) in a mid-scale wave flume, covering Reynolds numbers of Re = 2 104-2 105 and Keulegan-Carpenter numbers of KC = 2-50. Volumetric flow velocities are measured using Particle-Tracking Velocimetry with the Shake-the-Box method. Results show that biofouling alters flow patterns, creating recirculation zones with reverse flow velocities. Vorticity analysis reveals vortex formation in the wake, expanding with wave period and roughness. For the same fibre lengths, flexible biofouling models allow high levels of vorticity to spread further downstream (up to 133%), while stiff models create distinctive recirculation zones with a 18% larger recirculation length. These findings improve understanding of wave-induced wake development for rough surfaces.

Pellet-specific behavior in filamentous cultivations cannot be resolved in pilot-scale bioreactors because measurements are population-averaged and pellet populations exhibit stochastic heterogeneity. This work therefore aimed to establish a micro-scale cultivation platform for pellet-resolved investigations of filamentous microorganisms. For this purpose, a previously developed micro bubble column reactor (MBCR) was adapted for multi-day cultivation of the filamentous actinomycete Actinomadura namibiensis, the sole natural producer of the antiviral lantibiotic labyrinthopeptin A1. Reactor operation was characterized at gas flow rates of 4.7, 10.7, and 18.0mLmin−1 by determining volumetric mass transfer coefficients and performing online image analysis of bubble and pellet size distributions. A gas flow rate of 10.7mLmin−1 provided the best compromise between oxygen supply, hydrodynamic stability, and reproducible pellet morphology. During cultivation, dissolved oxygen decreased by only 2–3 %, indicating sufficient oxygen availability in the MBCR. The platform enabled determination of substrate consumption and product formation metrics normalized to both projected pellet area and inoculated pellet number throughout cultivation. Overall, the presented extension of the MBCR platform broadens its application to pellet-forming actinomycetes and demonstrates the potential of pellet-resolved characterization during filamentous cultivations, providing a basis for future mechanistic investigations of pellet-scale bioprocess behavior

The biomechanics and dielectric properties of mammalian oocytes are key determinants of developmental competence. However, conventional approaches such as optical deformation cytometry are limited by their reliance on high-resolution imaging, requiring complex image analysis techniques and making them unsuitable for large, optically dense cells like oocytes. Here, we present a differential microfluidic impedance cytometry platform that integrates frequency-resolved dielectric profiling with constriction-based deformation analysis. The hybrid glass-SU-8 chip with integrated coplanar electrodes enables high-fidelity measurements up to 30 MHz. Using hydrogel microspheres for calibration, we confirmed that their impedance response was largely frequency-independent. In contrast, porcine oocytes displayed classical β-dispersion, reflecting membrane capacitance and cytoplasmic conductivity, as well as pressure-dependent impedance dynamics indicating viscoelastic resistance. Two-dimensional impedance mapping enabled robust discrimination between hydrogels and oocytes. In addition, fresh oocytes and oocytes recovered from a severe freeze–thaw injury model showed separable electrical and transit-dynamic signatures. Impedance-derived peak-to-valley transit (PVT) analysis notably provided a fully electrical surrogate for deformation dynamics, eliminating the need for video-based tracking. To our knowledge, this is the first application of impedance cytometry to mammalian oocytes and the first demonstration of frequency-resolved differential impedance analysis of mammalian oocytes during pressure-driven constriction transit. Compared with subjective morphological assessment and imaging-dependent deformation analysis, this approach provides objective electrical readouts of dielectric and transit-dynamic phenotypes without labelling. Uniting dielectric profiling with mechanically coupled transit metrics in a single, label-free assay enables discrimination of individual treatment-associated electromechanical phenotypes within oocyte populations. These findings establish the technical feasibility of label-free single-oocyte electromechanical phenotyping.

When cultivating filamentous pellets, the mechanical behaviour during cultivation is of particular interest for high process productivity under turbulent hydrodynamic flow conditions. However, the exact mechanical interactions between the pellets or between the pellets and the reactor walls are still not fully understood and can hardly be resolved using experimental methods. This study therefore presents a combined numerical approach to investigating the mechanical behaviour of soft biological pellets in highly turbulent flows. Unlike conventional models, which focus on rigid particles, this approach captures the complex interactions between culture fluid and pellet, pellet and pellet, and pellet and reactor wall. The developed model efficiently calculates the conditions in shake flask cultivations while providing a realistic representation of them by modelling the motion of particles on a large scale and capturing the free surface. By incorporating turbulence-induced mechanical effects, the model sheds light on the impact of fluid and contact forces on changes in pellet morphology. These findings contribute to the optimisation of large-scale biotechnological processes, increasing productivity and operating efficiency in microbial cultivation systems.

In this study, we investigate the mechanical elastic and failure behavior of porcine small intestinal walls (SIWs). In order to comprehensively examine the small intestine (SI) mechanically, all three sections of the SI, the duodenum, jejunum, and ileum, are examined. Single-edge notched tensile (SENT) experiments are performed on the entire wall structure as well as on the individual layers (serosal, muscular, and mucosal layer). In addition, the experiments are carried out in different loading directions (0°, 45°, and 90°) with respect to the tissue orientation. Overall, the elastic mechanical behavior for all regions and all layers is characterized by a typical, exponential, nonlinear behavior in combination with a partially distinct anisotropic behavior, featuring an broad elastic region λmax of 1.1 to 1.7, with corresponding stresses Pe of approximately 2 to 330 kPa. Failure behavior, as characterized by the critical energy release rate GC, exhibits obvious layer dependence. The average GC value of the mucosal layer is approximately four times higher than that of the muscular layer (1-2 N/mm), while the serosal layer has the highest values, reaching 6-10 N/mm. Additionally, the fracture behavior of the combined muscular and serosal layers of the duodenum, jejunum and ileum can be explained by classical laminate theory. However, the results of the entire wall indicate complicated interlayer behavior between the mucosal and muscular layers. Furthermore, the crack-tip tracking method and local deformation obtained from optical measurements help achieve a clearer understanding of crack initiation and propagation. These results provide a comprehensive dataset about the failure characteristics of the SI that can be used as input or for validating failure models in the future. Statement of Significance: This study is the first to report on experiments involving the failure of the porcine small intestine. The study investigates the region-, orientation-, and layer-specific mechanical properties of the small intestine in order to gain insight into its behavior under intact and failed conditions. Although layer-specific experimental studies are essential for a comprehensive understanding of small intestine function, they have received little attention to date. Additionally, this study examines crack propagation direction during uniaxial tensile tests. The study provides a unique database that improves our understanding of small intestine failure behavior and serves as a basis for corresponding models.

Accurate knowledge of brain tissue mechanics is essential for understanding mechanically induced pathologies and developing reliable computational models of brain injury and neurosurgical interventions. However, the age-related changes in brain mechanics and their microstructural basis are not fully understood. In this study, we examined age-related changes in brain mechanics and microstructure in porcine tissue across five age groups, from early development to young adulthood. Mechanical tests in tension and compression were performed in different anatomical regions, including an anisotropic characterization of the corpus callosum. We used Bayesian parameter identification to estimate material parameters based on isotropic Ogden and anisotropic Gasser-Ogden-Holzapfel models. Meanwhile, histological analyses quantified myelin, cell, glia, and neuron measures. Our results revealed nonlinear age dependencies of tensile and compressive mechanics accompanied by clear age-dependent microstructural differences. Notably, myelin- and glia-related measures were the most consistent positive correlates of stiffness. Mediation analysis further suggested that microstructure, particularly glia-related features, serves as a measurable intermediate link between age and mechanics. These findings provide a microstructurally informed basis for more realistic, age-dependent, computational brain models.

Aponeuroses are thin, tendinous sheets that connect muscle bellies to tendons, playing a central role in force transmission. In order to improve the understanding of these mechanics, the present study examined the deformation of rabbit aponeuroses during passive muscle elongation and isometric and isotonic contractions against increasing forces. The strains of the aponeurosis from 99 isometric and isotonic muscle contractions were analysed in the rabbit gastrocnemius medialis (GASM) and plantaris (PLA) muscles, which have unipennate and multipennate fascicle architectures, respectively. Three-dimensional digital image correlation was employed to quantify aponeurosis strain between defined points along longitudinal and transverse paths on digitised muscle surfaces. Passive muscle elongation was characterised by longitudinal elongation and transverse narrowing, whereas muscle contraction generally resulted in longitudinal and transverse expansion of the aponeuroses. During isometric contraction, longitudinal strain ranged from 1% to 2%, whereas transverse strain averaged between 0% and 15%, depending on the muscle examined. Ultimately, active deformation exhibited a linear relationship between longitudinal aponeurosis strain and muscle force. The relative contributions of longitudinal and transverse deformation during passive and active states were muscle-specific. Together, these findings provide new insight on the shape change of aponeuroses and their interactions with the muscle tissue, while also providing indirect information on deformation patterns associated with force generation and transmission in pennate muscles.

Smooth muscle (SM) exhibits rapid mechanical adaptation in response to various stimuli, posing challenges for reproducible experimental results and consistent material parameter determination in biomechanical modeling. Preconditioning involving repeated loading and unloading cycles is commonly used to stabilize mechanical responses before testing. However, their influence on tissue properties and data variability remains underexplored. This study compares the effects of three preconditioning routines-passive cycling (PCYC), no preconditioning (PNPC), and free contraction (PFC)-on the active and passive force responses of porcine urinary bladder (UB) SM tissue. Three tissue strips from 12 UBs were randomly assigned to one of the routines and underwent an identical protocol involving a passive stretch ramp and two isometric contractions (IC1, IC2) to evaluate active and passive force development. After PCYC, the tissue generated the highest active (IC2: 44.7 ± 29.4 kPa) and passive tensions (IC2: 5.6 ± 4.3 kPa), though it also showed the highest variance in active tension. PNPC resulted in the lowest variance in active tension, with a coefficient of variation (CV) of 45%, and PFC showed the lowest variance in passive tension, CV = 57%. These findings imply that the decision for a certain preconditioning protocol influences the observed mechanical properties. In this context, PFC appears promising for minimizing passive force variability and preventing creep-induced lengthening. This could offer a more reliable foundation for subsequent experiments analyzing mechanical parameters. This study underscores the importance of customized preconditioning strategies to enhance consistency and comparability in SM research and organ modeling.NEW & NOTEWORTHY This study investigates how different preconditioning routines (passive cycling, no preconditioning, and free contraction) affect active and passive force generation in porcine urinary bladder smooth muscle. Using a subsequent standardized protocol, we show that the preconditioning choice influences both force magnitude and variability, with free contraction minimizing passive force variance and avoiding creep-induced lengthening. Our findings highlight the need for tailored preconditioning strategies to improve reproducibility in smooth muscle experiments and enhance biomechanical organ modeling.

Smooth muscle tissue is an important component of the involuntary muscle in hollow organs. Its ability to undergo extensive deformation while maintaining mechanical integrity is crucial for ensuring various functional activities of these organs. The functionality of smooth muscle tissue is determined by its major components, including elastin, collagen, and smooth muscle cells, which exhibit different mechanical properties, orientations and compositions within the tissue. In order to treat pathological conditions associated with smooth muscle tissue fracture, it is necessary to understand the failure behaviour of the individual components. This study proposes a three-dimensional multi-phase field model to investigate the fracture behaviour of smooth muscle tissue. The damage (failure) mechanism of each component is described by individual phase field descriptors. Furthermore, the model considers the anisotropic nature of fibrous components in elastic and fracture behaviour, as well as the different compositions within smooth muscle tissue. To demonstrate the applicability of the model, numerical simulations are performed on tissue strips, including uniaxial and biaxial testing. Additionally, the impact of varying fracture-related material properties and geometric configurations (notch orientations) is analysed to demonstrate the model’s ability to simulate fractures under diverse physiological and pathological conditions of smooth muscle tissue.

Mechanical interactions in shaken culture systems have been shown to actively drive the morphological restructuring of filamentous microbial pellets. This, in turn, has been demonstrated to influence thereby influencing productivity, including enzyme formation and the final concentration of secondary metabolites. The present study proposes a novel hybrid CFD-DEM-VOF framework for quantifying interactions between pellets with specific mechanical properties within populations. The framework assigns unique stiffnesses, densities and sizes to each pellet, computing the contact forces between the pellets themselves as well as between the pellets and the shake flask walls. The primary function of the approach is to calculate the corresponding contact frequencies within an evolving hydrodynamic field. Using mechanical measurements obtained for the filamentous actinomycete A. namibiensis at culture days D1, D3 and D8, the simulations reflect the measured evolution of the pellet population and quantify the associated changes in collision dynamics, kinetic energy levels and contact forces. The results reveal a distinct shift from highly dynamic, collision-intensive behaviour in the early stage of cultivation, to reduced pellet mobility and altered collision statistics in mature cultures. Subsequent analysis of the conditions on cultivation day D8 demonstrates how the shaking intensity and pellet mechanical properties modulate this mechanical landscape beyond changes arising from natural culture development. The framework provides a mechanistic basis for linking operating conditions to pellet restructuring and serves as a predictive tool for guiding the design and improvement of filamentous bioprocesses.

The stomach is a hollow organ within the gastrointestinal tract that plays a central role in the breakdown of ingested food. Its secretion of gastric acid facilitates chemical digestion, while the contraction of its smooth muscle aids in mechanical digestion. The upper, cranial part of the stomach acts as a reservoir for ingested food, while the lower, caudal part grinds the food through peristaltic contractions. Understanding the mechanical properties of the stomach is critical to gaining insight into its function and the overall digestive process. In this study, we performed equibiaxial tensile tests on porcine stomach tissue samples (n = 28) from the fundus, representing the cranial area, and the corpus, representing the central area. We analyzed the passive and active stress-stretch relationship as well as the force-velocity relationship. The main findings of our experiments are: (1) fundus samples show more isotropic mechanical properties, i.e., similar stress-stretch and force-velocity relationships in both directions (longitudinal vs. circumferential), (2) corpus samples show more anisotropic mechanical properties, i.e., there are direction-dependent differences in optimal stretch, maximal stress and the maximal shortening velocity, and (3) the corpus is much stiffer than the fundus. This study is the first to use biaxial tensile experiments to determine the active stress-stretch relationship in stomach smooth muscle and the first to characterize the biaxial force-velocity relationship in smooth muscle in general. The data provided advance our understanding of both smooth muscle and organ-level mechanics and provide more comprehensive insights than existing uniaxial tests in the literature. These findings are critical for the development and validation of constitutive muscle models that can predict stomach function in health and disease.

This study examines the passive mechanical behaviour of the porcine urinary bladder at various length scales. Biaxial tensile tests on square urinary bladder wall specimens are compared with whole urinary bladder inflation experiments. Both measurements are compared using finite element analysis to propagate layer properties across the entire organ, and local strain measurements are taken during inflation experiments to create comparable testing conditions to those of the biaxial tests. Biaxial tension tests at tissue level (n=6) and whole bladder tests (n=6) yielded an average Cauchy stress of 12.9 ± 4.1 kPa and 13.4 ± 1.7 kPa, respectively, for a stretch of λ=1.7 representing the maximum stretch during inflation. In addition, the properties of the bladder wall's different layers were investigated to gain insight into its individual components. The variability observed in the experimental results was incorporated into the analysis using a material model and Bayesian inference. The resulting range of material parameters formed the basis for simulations, allowing for further interpretation due to the simplicity of the material model. This study links tissue-level measurements to the entire organ, as well as layer properties to the entire urinary bladder wall.

Abstract The filamentous actinomycete Actinomadura namibiensis has attracted increasing interest as the only known natural producer of the carbocyclic lantibiotic labyrinthopeptin A1, a secondary metabolite with a broad antiviral spectrum of activity. Developing a model of microbial growth and product formation at the pellet level requires a deeper mechanistic understanding of the interactions between cultivation conditions, substrate availability, and oxygen limitation. These factors influence the cultivation process and product formation. As part of this work, a predictive model in the form of diffusion–reaction equations is developed to quantitatively describe nutrient uptake, oxygen diffusion limitation, and pellet growth. This framework couples the consumption kinetics of carbon sources, such as glucose and glycerol, to pellet growth, maintenance metabolism, and the formation of the secondary metabolite labyrinthopeptin A1. The model is calibrated based on the results of multiscale experiments, i.e., offline analysis of shake flask cultures and oxygen profiling of pellets at different time points under various conditions. This forms the basis for understanding nutrient uptake, metabolic heterogeneity, and mass transfer limitations within the pellets. Thus, the model provides a quantitative basis for predicting productivity. The validated multiscale model reproduces the experimental results well and can be used to predict pellet growth, substrate uptake, and product formation.

The urinary bladder is a hollow organ that undergoes significant deformation as it receives, stores, and releases urine. To understand the organ mechanics, it is necessary to obtain information about the material properties of the tissues involved. In displacement-controlled tensile tests, tissue samples are mounted on a device that applies stretches to the tissue in one or more directions, resulting in a specific stress response. For this study, we performed uniaxial and biaxial stretch experiments on tissue samples (n = 36) from the body region of the porcine urinary bladder. We analyzed the stress-relaxation, activation dynamics, and passive and active stretch-stress response. Main findings of our experiments are: (1) For uniaxial and biaxial stretching, the time constants for stress-relaxation depend on the stretch amplitude, (2) biaxially stretched samples experienced slower activation with tau act increasing by +63% compared to uniaxial stretching, (3) biaxial tests are characterized by reduced optimum stretches lambda optby-18%, and (4) biaxial and uniaxial tests showed no significant difference in maximum active stresses sigma opt. To interpret the results, we present a continuum mechanical model based on a viscoelastic, isotropic solid extended by a set of active muscle fibers. Model predictions show that results (3) and (4) can be explained by a uniform distribution of fiber orientations and a specific shape of the active fiber stress-stretch relationship. This study highlights how deformation modes during tensile testing affects smooth muscle mechanics, proving insights for interpreting experimental data and improving organ modeling. Statement of Significance: In this study, we examined the mechanical properties of porcine bladder smooth muscle using uniaxial and equibiaxial tensile tests. To our knowledge, this is the first instance where the active stress- stretch relationships of smooth muscle tissue have been analysed under equibiaxial stretch. The data collected offer a detailed understanding of the connection between deformation and active stress production, surpassing the insights provided by existing uniaxial tests in the literature. These findings are crucial for comprehending the physiology of smooth muscle tissue and for developing constitutive muscle models that can make more accurate predictions about the functionality of hollow organs in both health and disease. Additionally, our findings on smooth muscle active stress could aid in the creation of biomaterials that interact with or even replace natural muscle.

In order to meet the requirements of body weight and height and the associated changing tasks and movement patterns during the growth of living bodies, significant changes in the skeletal musculature occur during this phase. In this study, the age-dependent (between 21 and 100 days) mechanical and microstructural tissue behaviour of the calf musculature, consisting of soleus muscles (SOL), gastrocnemius muscles (GAS) and plantaris muscles (PLA), was examined. To this end, cubic muscle tissue samples were examined using axial and semi-confined compression experiments. In addition, the essential muscle tissue components (muscle fibres, extracellular matrix, remaining components) were analysed. In a final step, these results were linked to morphological properties of the animals and muscles (animal mass, muscle mass, tibia length). Interestingly, the mechanical properties of the individual muscle types hardly differ from each other during growth, while both the morphological and microstructural properties change significantly. Thus, a clear increase of all morphological parameters (animal mass by 850%, muscle mass by 1000% (SOL), 1183% (GAS) and 1050% (PLA), tibia length by 235%) can be seen. In comparison, the microstructural parameters show a less consistent trend. The proportion of muscle fibres in the tissue cross-section increases by about 138% in the SOL, whereas the fibre proportion in both the GAS and PLA increases by only 109%. Consequently, the ECM proportion in the tissue cross-section decreases by 48%, 58% and 52% for SOL, GAS and PLA. Overall, the data obtained her e provides a deeper understanding of muscle growth and, in particular, of different muscle types that have different functions inside the calf. On the other hand, these data represent a good and comprehensive basis for later model developments.

Labyrinthopeptin A1, a promising broad-spectrum antiviral, is produced exclusively by the filamentous actinomycete Actinomadura namibiensis. In submerged cultures of A. namibiensis, supplementation with 50 mM ammonium sulfate resulted in a 6.3-fold increase in product formation, accompanied by enhanced glycerol consumption, lower dissolved oxygen tension, and changes in pellet morphology. This study aims to elucidate the underlying mechanisms of this bioprocess intensification method using novel tools such as oxygen microprofiling, plate-plate compression, and sedimentation experiments to investigate pellet characteristics possibly associated with product formation. Oxygen microprofiling revealed steeper profiles in salt-supplemented pellets, indicating heightened metabolic activity and potential oxygen limitation in pellet cores during exponential growth phase, which affects the subsequent secondary metabolite production. For the first time, pellet density was estimated using sedimentation experiments. While control pellets showed no density trends, saltsupplemented pellets became more porous over time, suggesting a link to the increased glycerol uptake during product formation. Additionally, the compression experiments showed greater increase in stiffness in saltsupplemented pellets over time, suggesting the development of stiffer structures within the hyphal network and increased pellet stability. This observation was previously inferred only through image analysis and cell dry weight concentration. Ultimately, the results presented here contribute to the development of numerical simulations and predictive models for the productivity and growth behavior of filamentous pellet cultures in the future.

Piezoelectric (0-3) composites typically consist of a polymer matrix that contains piezoceramic particles. They can be used as sensors for structural health monitoring due to their lower acoustic impedance and ability to detect high-frequency waves. These composites have two thin electrodes on their surfaces, and cable connections that require electrical insulation. This insulation increases the durability of the sensor and provides additional protection. One way to achieve this is by encapsulating the sensor in polymer films. However, the sensitivity of the sensor may decrease due to an increase in overall stiffness after encapsulation, so this must also be evaluated. This study experimentally investigates and compares three different encapsulation designs with a non-encapsulated reference sample. The designs include (i) gluing and laminating the sensor onto a pre-prepared flexible printed circuit board, (ii) lamination of the sensor with polyethylene terephthalate, and (iii) lamination with polyetherimide. The sensitivity of the encapsulated sensors to low and high frequency vibrations was evaluated. The results show that an encapsulation sensor with adhesive tape and polyetherimide results in slightly lower sensitivity at lower frequencies, but almost no difference at higher frequencies. These results suggest that the proposed method is suitable for encapsulating sensors for use in structural health monitoring applications.

Mechanical organ models are crucial for understanding organ function and clinical applications. These models rely on input data regarding smooth muscle properties, typically gathered from experiments involving stimulations at different muscle lengths. However, reproducibility of these experimental results is a major challenge due to rapid changes in active and passive smooth muscle properties during the measurement period. Usually, preconditioning of the tissue is employed to ensure reproducible behavior in subsequent experiments, but this process itself alters the tissue's mechanical properties. To address this issue, three protocols (P1, P2, P3) without preconditioning were developed and compared to preserve the initial mechanical properties of smooth muscle tissue. Each protocol included five repetitive experimental cycles with stimulations at a long muscle length, varying in the number of stimulations at a short muscle length (P1: 0, P2: 1, P3: 2 stimulations). Results showed that P2 and P3 successfully reproduced the initial active force at a long length over five cycles, but failed to maintain the initial passive forces. Conversely, P1 was most effective in maintaining constant passive forces over the cycles. These findings are supported by existing adaptation models. Active force changes are primarily due to the addition or removal of contractile units in the contractile apparatus, while passive force changes mainly result from actin polymerization induced by contractions, leading to cytoskeletal stiffening. This study introduces a new method for obtaining reproducible smooth muscle parameters, offering a foundation for future research to replicate the mechanical properties of smooth muscle tissue without preconditioning.

Filamentous bacteria and fungi are attracting increasing attention due to their medicinal value. Among these microorganisms, Actinomadura namibiensis has attracted great interest due to its ability to produce Labyrinthopeptin A1 with antiviral activity. In order to increase productivity and shorten the development cycle, recent studies have shown that the production of Labyrinthopeptin A1 can be enhanced by optimising the cultivation processes of filamentous pellets with the help of morphology engineering techniques including the appropriate preparation of the culture medium and the flow conditions for agitation, as well as the contact mechanisms during the flow-induced movements of the pellets. From a mechanical point of view, contact energy is positively correlated with productivity and is determined by the mechanical and morphological properties of the pellets, which have a string influence on the stresses, contact frequency and structure for mass transfer of nutrients. To gain a deeper understanding of the stress-induced pellet growth mechanisms during cultivation, experimental characterisation of Actinomadura namibiensis pellets was performed using a micromechanical setup. Considering that filamentous pellets exhibit an irregular geometry with tightly intertwined and branched hyphal networks, the measured force responses of cyclic compression experiments were analysed in correlation with the morphological properties. In addition, the process-dependent mechanical behaviour was investigated by comparing the mechanical behaviour at different cultivation times. The results obtained provide sufficient information to propose a contact model of the pellets and to derive the process-dependent material parameters for further numerical simulations of the cultivation process.

As part of the digestive system, the stomach plays a crucial role in the health and well-being of an organism. It produces acids and performs contractions that initiate the digestive process and begin the break-up of ingested food. Therefore, its mechanical properties are of interest. This study includes a detailed investigation of strains in the porcine stomach wall during passive organ filling. In addition, the observed strains were applied to tissue samples subjected to biaxial tensile tests. The results show inhomogeneous strains during filling, which tend to be higher in the circumferential direction (antrum: 13.2%, corpus: 22.0%, fundus: 67.8%), compared to the longitudinal direction (antrum: 4.8%, corpus: 24.7%, fundus: 50.0%) at a maximum filling of 3500 ml. Consequently, the fundus region experienced the greatest strain. In the biaxial tensile experiments, the corpus region appeared to be the stiffest, reaching nominal stress values above 400 kPa in the circumferential direction, whereas the other regions only reached stress levels of below 50 kPa in both directions for the investigated stretch range. Our findings gain new insight into stomach mechanics and provide valuable data for the development and validation of computational stomach models.