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#adhesion

1 post1 participant0 posts today
Public
Rxiv mechanobio

📰 "Implicit Incompressible Porous Flow using SPH"
arxiv.org/abs/2504.07739 #Physics.Flu-Dyn #Adhesion #Forces #Cs.Gr

arXiv.orgImplicit Incompressible Porous Flow using SPHWe present a novel implicit porous flow solver using SPH, which maintains fluid incompressibility and is able to model a wide range of scenarios, driven by strongly coupled solid-fluid interaction forces. Many previous SPH porous flow methods reduce particle volumes as they transition across the solid-fluid interface, resulting in significant stability issues. We instead allow fluid and solid to overlap by deriving a new density estimation. This further allows us to extend modern SPH pressure solvers to take local porosity into account and results in strict enforcement of incompressibility. As a result, we can simulate porous flow using physically consistent pressure forces between fluid and solid. In contrast to previous SPH porous flow methods, which use explicit forces for internal fluid flow, we employ implicit non-pressure forces. These we solve as a linear system and strongly couple with fluid viscosity and solid elasticity. We capture the most common effects observed in porous flow, namely drag, buoyancy and capillary action due to adhesion. To achieve elastic behavior change based on local fluid saturation, such as bloating or softening, we propose an extension to the elasticity model. We demonstrate the efficacy of our model with various simulations that showcase the different aspects of porous flow behavior. To summarize, our system of strongly coupled non-pressure forces and enforced incompressibility across overlapping phases allows us to naturally model and stably simulate complex porous interactions.
Public
Rxiv mechanobio

📰 "Nanodroplet Dynamics: Coalescence and Impact"
arxiv.org/abs/2503.13659 #Physics.Flu-Dyn #Dynamics #Adhesion

arXiv.orgNanodroplet Dynamics: Coalescence and ImpactThis study aims to investigate the coalescence-induced jumping of water nanodroplets in a high Ohnesorge number regime (0.4 < Oh < 1) on a superhydrophobic surface and the dynamics of droplets when a stationary droplet on a solid surface is struck by another droplet of similar size from above, using molecular dynamics simulation. The first part of this study identified the critical droplet size below which coalescence-induced jumping terminates, developed a universal jumping mechanism for droplets of all types, explained a special phenomenon of jumping velocity becoming maximum before it approaches zero, and investigated how jumping terminates due to the size difference between droplets. These findings align well with prior micro-level studies and experimental predictions. The second part of this study investigated the jumping process of the merged droplet after the impact of a moving droplet upon a stationary one. The impact velocity, droplet size, surface textures, and wettability are influential factors on the jumping velocity in this case. Scaling laws for maximum spreading time, spreading factor, and restitution coefficient are formulated based on the Weber (We) number and the Reynolds (Re) number. These laws differ from those established for single-droplet impacts. For superhydrophobic surfaces, the spreading time is approximated by three times the droplet radius and impact velocity, and with the dimensionless spreading time, it exhibits a linear relationship with We 0.31. For both cases, the jumping process is primarily governed by the energy available for conversion into the kinetic energy of the merged droplet following dissipation. For the droplet impact case, the energy conversion efficiency becomes constant at high-impact droplet velocities. About 1% of the energy is dissipated due to surface adhesion, which reduces at higher impact velocity.
Public
Rxiv mechanobio

📰 "Perfect Stabilization of Biomolecular Adhesions under Load"
arxiv.org/abs/2503.11510 #Physics.Bio-Ph #Cond-Mat.Soft #Mechanical #Adhesion

arXiv.orgPerfect Stabilization of Biomolecular Adhesions under LoadCells attach to their environment by means of focal adhesions, which are molecular complexes that exhibit the remarkable ability to adapt to mechanical load by changing their size. Drawing from the biomolecular mechanisms underlying this behavior, we present a generic model for mechanically induced adhesion growth where conformational states of molecules already in the adhesion cluster are coupled to the adsorption of further molecules. For sufficiently strong coupling, an instability arises and unbounded system growth ensues in the absence of mechanical load. Unexpectedly, the same type of instability can lead to perfect stability under mechanical load, whereby adhesion clusters adjust their size to withstand arbitrarily large forces without breaking, a phenomenon we term perfect stabilization. We derive state diagrams that characterize adhesion stability under stationary loads and show that perfect stabilization also occurs under dynamic loading on physiologically relevant timescales. Finally, we show that perfect stabilization and related instabilities are generic phenomenona that can be realized in many different ways if internal molecule states are coupled to adsorption in nonequilibrium.
Public
Nicole Sharp

Anti-Icing Polar Bear Fur

Despite spending their lives in and around frigid water, snow, and ice, polar bears are rarely troubled by ice building up on their fur. This natural anti-icing property is one Inuits have long taken advantage of by using polar bear fur in hunting stools and sandals. In a new study, researchers looked at just how “icephobic” polar bear fur is and what properties make it so.

The key to a polar bear’s anti-icing is sebum — a mixture of cholesterol, diacylglycerols, and fatty acids secreted from glands near each hair’s root. When sebum is present on the hair, the researchers found it takes very little force to remove ice; in contrast, fur that had been washed with a surfactant that stripped away the sebum clung to ice.

The researchers are interested in uncovering which specific chemical components of sebum impart its icephobicity. That information could enable a new generation of anti-icing treatments for aircraft and other human-made technologies; right now, many anti-icing treatments use PFAS, also known as “forever chemicals,” that have major disadvantages to human and environmental health. (Image credit: H. Mager; research credit: J. Carolan et al.; via Physics World)

Polar bears secrete chemicals that make their fur naturally ice-resistant, suggesting new anti-icing tech for us, too.
#adhesion#biology#chemistry
Public
Rxiv mechanobio

📰 "Focal adhesion in the tumour metastasis: from molecular mechanisms to therapeutic targets"
doi.org/doi:10.1186/s40364-025
pubmed.ncbi.nlm.nih.gov/400453
#Extracellular #Mechanical #Adhesion

BioMed CentralFocal adhesion in the tumour metastasis: from molecular mechanisms to therapeutic targets - Biomarker ResearchThe tumour microenvironment is the “hotbed” of tumour cells, providing abundant extracellular support for growth and metastasis. However, the tumour microenvironment is not static and is constantly remodelled by a variety of cellular components, including tumour cells, through mechanical, biological and chemical means to promote metastasis. Focal adhesion plays an important role in cell-extracellular matrix adhesion. An in-depth exploration of the role of focal adhesion in tumour metastasis, especially their contribution at the biomechanical level, is an important direction of current research. In this review, we first summarize the assembly of focal adhesions and explore their kinetics in tumour cells. Then, we describe in detail the role of focal adhesion in various stages of tumour metastasis, especially its key functions in cell migration, invasion, and matrix remodelling. Finally, we describe the anti-tumour strategies targeting focal adhesion and the current progress in the development of some inhibitors against focal adhesion proteins. In this paper, we summarize for the first time that focal adhesion play a positive feedback role in pro-tumour metastatic matrix remodelling by summarizing the five processes of focal adhesion assembly in a multidimensional way. It is beneficial for researchers to have a deeper understanding of the role of focal adhesion in the biological behaviour of tumour metastasis and the potential of focal adhesion as a therapeutic target, providing new ideas for the prevention and treatment of metastases.
Public
Rxiv mechanobio

📰 "High Speed Imagery Analysis of Droplet Impact on Soft Oil Infused Surface"
arxiv.org/abs/2503.02871 #Physics.Flu-Dyn #Adhesion #Dynamics

arXiv.orgHigh Speed Imagery Analysis of Droplet Impact on Soft Oil Infused SurfaceDroplet impact on solid liquid-infused surfaces (LIS) has been widely explored due to its significant scientific implications and industrial relevance. In most studies, the predominant impact behavior observed is complete droplet rebound. In This study we investigated the influence of octadecyltrichlorosilane (OTS) functionalization and oil coatings on the droplet impact dynamics of smooth polydimethylsiloxane (PDMS) surfaces. We conducted droplet impact experiments on smooth PDMS functionalized with OTS and subsequently coated or absorbed with two different oils, silicone oil (5cSt) and hexadecane, to create Van der Waals and non-Van der Waals SLIP surfaces. Contact angle measurements revealed that OTS functionalization reduced adhesion and increased water repellency, facilitating partial droplet rebound upon impact. Oil-coated surfaces exhibited reduced droplet spreading due to viscous resistance, while absorbed oils altered surface flexibility, influencing impact dynamics. PDMS samples absorbed with silicone oil demonstrated complete droplet rebound at all Weber numbers, whereas hexadecane-absorbed surfaces exhibited limited spreading and no rebound, highlighting the significance of oil-PDMS interactions. High-speed imaging and quantitative analysis confirmed that surface functionalization and oil interactions critically affect droplet spreading, recoil, and rebound behavior. These findings provide insights into optimizing liquid-repellent surfaces for applications such as self-cleaning coatings and droplet transport systems.
Public
Rxiv mechanobio

📰 "A highly sensitive, self-adhesive, biocompatible DLP 3D printed organohydrogel for flexible sensors and wearable devices"
arxiv.org/abs/2502.17208 #Cond-Mat.Mtrl-Sci #Physics.App-Ph #Mechanical #Adhesion

arXiv.orgA highly sensitive, self-adhesive, biocompatible DLP 3D printed organohydrogel for flexible sensors and wearable devicesWith the increasing demand for personalized health monitoring, wearable sensors have gained attention in medical diagnostics and physiological tracking. Hydrogels, known for their mechanical properties and similarity to biological tissues, are ideal for flexible sensing. However, conventional hydrogels face challenges in stability, biocompatibility, adhesion, and long-term comfort, especially in dynamic conditions.This study presents a highly sensitive, self-adhesive, and biocompatible organohydrogel fabricated via DLP 3D printing. By integrating an entanglement-dominated crosslinking mechanism with chemical and physical crosslinking, the hydrogel achieves high elasticity, mechanical strength, and durability. Methacrylic anhydride-grafted \k{appa}-carrageenan serves as the primary network, with optimized grafting rates enhancing tensile properties and strain modulation. The copolymer network of MA-kappa-CA and ACMO benefits from steric hindrance effects, improving swelling integrity and long-term stability.Experimental results confirm sustained adhesion and structural integrity under prolonged skin exposure, making it suitable for extended wear. The hydrogel exhibits excellent tensile resilience, flexibility, and strain-sensing capabilities. In vitro studies validate its biocompatibility, supporting its biomedical potential. Furthermore, its integration into wearable smart devices demonstrates promise for cervical spine monitoring and sports rehabilitation. A CNN-based system enables real-time, multi-channel analysis of cervical motion, proving its viability as a high-sensitivity flexible sensor for health monitoring and injury prevention.The proposed DLP 3D-printed hydrogel offers significant applications in flexible electronics, wearable sensors, and biomedical technologies, paving the way for next-generation health-monitoring systems.
Public
Rxiv mechanobio

📰 "Advanced 3D-Printed Multiphasic Scaffold with Optimal PRP Dosage for Chondrogenesis of BM-MSCs in Osteochondral Tissue Engineering"
arxiv.org/abs/2502.11130 #Mechanical #Q-Bio.To #Adhesion

arXiv.orgAdvanced 3D-Printed Multiphasic Scaffold with Optimal PRP Dosage for Chondrogenesis of BM-MSCs in Osteochondral Tissue EngineeringIn osteochondral tissue engineering (OCTE), simultaneously regenerating subchondral bone and cartilage tissue presents a significant challenge. Multiphasic scaffolds were created and manufactured using 3D printing to address this issue. Excellent interfacial mechanical properties and biocompatibility enhance the growth and chondrogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs). The subchondral bone bottom layer is mimicked by incorporating varying concentrations of graphene oxide (GO) (0%, 1%, and 2% w/v) into a bioink composed of alginate (Alg) and gelatin (Gel). Based on evaluations of mechanical and biocompatibility properties, 1% GO is selected for further studies. Subsequently, the GO concentration is kept constant while varying the platelet-rich plasma (PRP) dosage in the multiphasic scaffolds. Different PRP dosages (0%, 1%, 2%, and 3% w/v) are integrated into the Alg-Gel bioink to simulate cartilage tissues. Results indicate that 3D-printed scaffolds containing 1% or 2% PRP exhibit favorable biomechanical properties, with no significant differences observed. However, BM-MSCs exposed to 2% PRP demonstrate enhanced adhesion, growth, and viability. Additionally, real-time PCR and Alcian blue staining confirm increased chondrogenic expression and glycosaminoglycans (GAGs) synthesis. This work highlights the promising potential of 3D-printed multiphasic frameworks in the development of OCTE.
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