Effective cell adhesion under challenging mechanical situations is critical for a vital soft tissue sealing of the transmucosal parts of dental implants and thus essential for oral wound healing. To investigate this process in vitro, we developed a versatile flow chamber model that applies defined shear stress to assess the adhesion strength of relevant cell types. The system focuses mainly on primary human gingival fibroblasts, with preliminary experiments including also gingival keratinocytes. The chamber accommodates standard-sized titanium sample geometries used in projects dedicated to develop surface modifications preventing peri-implantitis. Actual shear stress was determined through computational fluid dynamics software, targeting a central 5×5mm region used for cell seeding. Shear stress ranged from 0.05Pa (0.4ml/min) to 0.49Pa (4ml/min). Key variables studied included shear stress magnitude and duration of the dynamic phase. We assessed two titanium surface topographies-polished and nanodiamond-coated-to explore the role of nano-roughness in resisting detachment. Results demonstrated that topography significantly influences cell retention, with highest differences observed under 0.36Pa shear stress for 1 to 2h of dynamic phase. Furthermore, we adapted the model to simulate wound healing, revealing that surface topography impacts repopulation dynamics. Of two compared arrangements for the co-culture of fibroblasts and keratocytes, either sequential seeding of keratinocytes on top of pre-seeded fibroblast or simultaneously in adjacent regions, we prefer the latter approach for this specific dynamic model. Overall, in all model modifications the nanorough surfaces supported a more stable attachment of both fibroblasts and keratinocytes, with greater shear sensitivity of the keratinocytes. This model offers a reproducible, physiologically relevant platform to evaluate adhesion strength and wound healing, with potential for future application in biomaterial screening and implant design.

Decoding vascular aging: Substrate stiffness and shear stress orchestrate endothelial inflammation and remodelling via mechanosensitive pathways.

Cross-laminated timber (CLT) panels can provide two-way span resistance in point-supported floor applications where the panels are directly supported by columns, providing increased free story height and a flexible room layout. Previous research has shown that in the vicinity of point supports, CLT punching shear resistance under bi-axial loading is enhanced when compared to the CLT rolling shear resistance under uniaxial shear stress. In addition, due to the two-way bending of the panels and the resulting deformed shape, the effect of support condition on the resistance should be considered when designing point-supported CLT floors. In this research, 164 full-scale CLT panels were tested under punching shear to study the impact of column location, point-support area, out-of-plane stiffness of the load distribution plate, and timber species on CLT punching shear resistance. Punching shear resistance was primarily influenced by column location and point support area; and using a load distribution plate with a smaller out-of-plane stiffness helped to reduce stress concentrations. An analytical model is proposed for point-supported CLT floor design in punching shear, which accounts for the increased rolling shear strength and the shear stress concentrations for different column conditions. • The rolling shear strength of CLT exhibits enhanced performance under localized shear stresses and punching shear loading. • Material-strength and column-condition related adjustment factors are required to calculate CLT punching shear resistance. • The transformed-section method precisely estimates CLT shear-stress distribution while accounting its orthotropic nature .

Innovating stents for aneurysm repair: New implant designs informed by thrombosis modeling.

Cell therapies and 3D bioprinting often require suspended cells to be delivered through needles of 20-gauge and smaller. This often damages cells, affecting their short and long-term viability. Most researchers have attributed this to excessive viscous stresses encountered entering or within the needle, but the experimental evidence contradicts that, as higher viscosity suspension fluids generally yield higher cell viabilities when injected at the same flow rate. We therefore sought to determine the most relevant fluid flow parameter influencing cell mechanical damage. A combination of reprocessing published results and cell injection experiments were conducted. Human umbilical vein endothelial cells (HUVECs) were suspended in Newtonian fluids of varying viscosities and injected through 30-gauge syringe needles in experiments that controlled for either shear stress or shear rate (a kinematic quantity expressing relative velocity of adjacent fluid layers). Based on evidence from injection experiments using a variety of fluids, it is shown that increasing shear rate better explains reductions in cell viability than increasing shear stress. Knowledge that shear rate is a more relevant fluid mechanical parameter governing mechanical damage provides a rational basis for designing injection protocols (injectors and suspension fluid rheological properties) to maximize cell viability.

Anatomically parameterised statistical shape modelling of LVAD-supported left ventricles for thrombosis risk assessment.

Impact of injection time and protein modality on particle formation when using closed system transfer devices.

Inhalation exposure and particle deposition across 16 nonhuman primate airway models using computational fluid-particle dynamics for allometric extrapolation.

Pulsating flow of a Maxwell fluid through a tube with a homogeneous porous medium

Effect of barium sulfate, thickener type, and saline solution on the rheological properties of liquids used for instrumental swallowing assessment.

Improving water resistance of acrylate adhesive joints through atmospheric plasma treatment for civil engineering applications

Computational Fluid Dynamics Predicting Intraprosthetic Thrombus Formation and Burden Following Endovascular Aortic Repair: A Two-Center Retrospective Study.

In silico modelling of changes in spinal cord blood flow after endovascular aortic aneurysm repair.

Numerical study of swash dynamics: Development of a porous layer boundary treatment for rough surfaces modelling

Numerical study on the variations of bed shear stress and its effects on scour characteristics around offshore monopile under combined wave-current actions

The dynamic sink: How settling-resuspension cycles drive offshore transport of high-density microplastics.

Experimental and numerical investigation of shear-driven fracture in hybrid tape/fabric-laminate end-loaded-split specimens

Over the past 70 years, riparian vegetation has progressively encroached onto braided gravel bars in the Sagae River, Japan, indicating a planform shift from a braided to a more meandering pattern. This study clarifies the mechanisms driving riparian vegetation encroachment by disentangling the combined effects of multiple catchment-scale management interventions. The construction and operation of the Sagae Dam upstream reduced high flows, especially in the recurring 2–5-year period. This coincides with the onset of vegetation expansion, with the riparian vegetation cover in the channel increasing from 5% pre-dam to 56% post-dam. To assess the combined impacts of the hydrological and hydraulic regulations on the mobility of bed material, dimensionless shear stress during high flows was estimated. Riverbed stabilisation works resulted in the post-dam conditions exhibiting lower dimensionless shear stresses, thereby reducing the frequency and spatial area of sediment mobilisation. Additionally, sediment from upstream is largely trapped in the dam reservoir and in a series of check dams in the catchment. In combination, these interventions stabilised gravel bars by allowing the establishment and succession of pioneer vegetation, which then further reinforced bar stability, thereby enabling the development of woody vegetation within the channel and promoting the progression of a meandering planform that accelerates flow accumulation. These results indicate how multiple anthropogenic interventions can interact to cumulatively alter fluvial conditions. The results also offer an important example of biogeomorphological feedback at a large scale, with important implications for river processes and the management of hydrological hazards in braided systems. • Aerial images over 70 years reveal substantial expansion of in-channel vegetation. • The channel planform shifted from a braided to a meandering pattern. • Regulated floods influenced vegetation survival and stabilised the riverbed. • Check dams and the Sagae dam disconnected sediment, reshaping vegetation patterns. • The braiding-to-meandering shift further accelerated vegetation expansion.

The durability evaluation of permafrost infrastructure heavily relies on interfacial strength characterization. However, existing constitutive models systematically underestimate the damage accumulation rate during freeze–thaw cycling while overestimating residual strength, leading to significantly increased structural safety risks and severely shortened engineering service life. This study investigates shear behavior at concrete–crushed rock soil interfaces under freeze–thaw cycles through laboratory direct shear tests. The shear stress–displacement relationship is analyzed as a function of cycle number, with nuclear magnetic resonance quantifying interfacial pore structure evolution. A four-parameter modified Duncan–Chang model is developed to establish a higher-order nonlinear constitutive framework that integrates freeze–thaw damage effects. Unlike traditional one- or two-parameter hyperbolic models, the proposed model captures complex deformation phases including plastic hardening and incipient strain softening, which are empirically observed in freeze–thaw-damaged interfaces. A two-stage energy decoupling mechanism was proposed to separately describe interfacial debonding energetics and particulate friction thermodynamics, establishing a direct correlation that correlates microstructural ice cementation rupture patterns with continuum-scale elastoplastic deformation characteristics under freeze–thaw cycles. Interfacial shear strength exhibits dual dependence on normal stress magnitude and freeze–thaw history, showing a 40.5% increase in strength at 300 versus 100 kPa normal stress after 15 cycles, followed by stabilized degradation rates attributed to self-organized ice recrystallization patterns. Porosity progressively expands by 0.9%–2.3% with cycling, driven by phase transition–induced microcrack bifurcation and bidirectional pore restructuring (micropore coalescence/macropore fragmentation), which inversely correlates with cohesion reduction. The four-stage constitutive model with cubic–hyperbolic cyclic damage corrections achieves R2 > 0.95 via nonlinear least-squares validation. The model can explain the stress–displacement process of the interface and the strain softening phenomenon in detail, which can provide a basis for the numerical simulation and theoretical calculation of the structure in the frozen soil ground.

Tumor microenvironment and mechanotransduction pathways: Novel targets and new directions for cancer therapy.