In this study, a simple and accessible computational method, the constrained geometries simulate external force (CoGEF), was used to simulate the impact of mechanical stress on model mechanophores and predict their mechanochemical reactivity. The development of force-responsive molecules enables the design of polymers for applications such as damage reporting, stress sensing, and self-healing. Experimental development of mechanophores is often hindered due to a lack of understanding of structure-activity correlations. Simulation can assist in understanding such relationships and designing better mechanophores. A series of mechanophores were proposed and computationally studied using the CoGEF method at the B3LYP/6-31* level of theory, which applies an external tensile force to the molecule to predict mechanochemical bond rupture. This study provides insights into the roles of electron-withdrawing groups, linear hydrocarbon or ester groups, and solvents in the design of new mechanophores before synthesis.

Comparison of One- and Two-knot Techniques in Eight-Strand Flexor Tendon Repair Using Looped Sutures: A Biomechanical Study in a Porcine Model.

Currently, the use of the superficial musculoaponeurotic system (SMAS) is a major trend for the longevity of rhytidectomy. We aimed to compare changes in outcomes over 1 year according to the degree of tension (Newton, N) applied to the composite flap during deep-plane rhytidectomy or composite rhytidectomy. This study included 70 patients, divided into 2 groups. Group 1 comprised 45 patients who underwent composite flap fixation under maximal tension. Group 2 consisted of 25 patients who underwent surgery with minimal tension on the composite flap. Tension applied to the flap was measured intraoperatively using a tensiometer. All patients also underwent facial photographic assessment for objective evaluation. The patients' medical records and photographs were retrospectively reviewed. In both groups, tension in the lower face and neck was statistically significant (P<0.05). However, there was no statistical significance between the 2 groups for any of the details (P>0.05). Also, there was no difference between the 2 groups in the subjective satisfaction survey of patients regarding the surgery (P>0.05). In Asian rhinoplasty, modest tensile forces applied to the face and neck yielded similar surgical outcomes, regardless of force magnitude within the specified range.

Abstract Acute sport-related avulsion fractures and osteochondral injuries are common in athletes, particularly in the pediatric population, and may present diagnostic challenges when radiographic findings are subtle. These injuries occur because of excessive tensile, shear, or impaction forces and most frequently involve apophyses, osteochondral junctions, or articular surfaces. Accurate characterization of injury location, fragment morphology, displacement, and associated soft-tissue abnormalities is essential to guide management, promote healing, and facilitate safe return to play (RTP). Radiographs are the initial imaging modality for evaluation and are useful for identifying osseous avulsion fragments and assessing alignment. Computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) may serve as complementary modalities depending upon the suspected injury. Common injury sites include the shoulder, elbow, pelvis, knee, foot, and ankle. Recognition of characteristic imaging patterns, associated injuries, and potential mimics, particularly in skeletally immature patients, is critical for accurate diagnosis. Management ranges from conservative therapy to surgical fixation or cartilage restoration procedures. This review summarizes the mechanisms, imaging features, treatments, pitfalls, and RTP implications when available of acute sport-related avulsion fractures and osteochondral injuries.

Quantitative understanding of tensile mobilisation and stress redistribution in geocoir systems remains limited despite increasing interest in sustainable alternatives. This study presents an integrated experimental-numerical investigation of geocoir cell-reinforced sand subgrades under monotonic loading. Laboratory plate load tests were performed for two pocket sizes of geocoir cell (210 × 210 mm and 300 × 300 mm), and validated three-dimensional finite element simulations were used to quantify stress redistribution and tensile force mobilisation within the honeycomb structure. The 210 × 210 mm configuration achieved a 2.8-fold enhancement in bearing capacity and an 86% decrease in settlement relative to the unreinforced subgrade. Numerical analyses reveal pronounced stress attenuation beneath the reinforced layer and tensile force concentration near stitching regions of geocoir cells, with peak mobilisation ranging from 56% to 79% of the ultimate tensile capacity, indicating efficient structural utilisation without rupture. Prototype-scale modelling confirmed scale-consistent behaviour (<10% variation), demonstrating that soil-cell interactions, rather than boundary effects, govern confinement and tensile mobilisation.

Based on spatially-temporally resolved polarized optical microscopy (str-POM) measurements, we studied the fracture behavior of ductile and brittle glassy polymers as well as highly crosslinked rubbers to draw the following conclusions: (1) there is no tip plasticity below a threshold load in ductile plastics such as polyethylene terephthalate. (2) In ductile polymer glasses, before tip yielding at a common tip stress, the remote load scales with notch length a as a-1/2, in agreement with the Inglis solution. (3) A finite stress saturation zone is observed in elastomers at loading levels even well below fatigue threshold due to significant crack tip blunting. (4) When the thickness is small enough for the plane stress condition to prevail at crack tip, in double-edge notch tension (DENT) for both ductile glassy polymers and rubbers that is characterized by ligament length l, nominal strain in the ligament is defined by εlig = X/l, where X is tensile displacement; tensile force F increases linearly with X independent of l; tip stress increases linearly with the far-field σlig (∼εlig). By demonstrating stress concentration at the crack tip in DENT in elastic materials and characterizing crack propagation in ductile polymers, the present study fills the missing gap in our understanding of fracture behavior in a wider range of polymeric materials. The acquired knowledge may be useful to guide specific design for packaging materials.

To investigate short-term scleral response to expanded polytetrafluoroethylene (ePTFE) sutures using the dynamics of its mechanical stabilization in an animal model. Ten rabbits underwent unilateral lens extraction followed by implantation of two knotless scleral fixation techniques using ePTFE (Gore-Tex CV-8): Z-suture and chain-of-knots. Both techniques were implanted in each eye. At postoperative days 1, 5, 10, 20, and 30, two rabbits were analyzed per time point (n = 10), each contributing one independent dynamometric measurement per technique. The tensile force required to disinsert the implanted material from the sclera was quantified using a dynamometer. Dynamometric evaluation of tensile force of the Z-suture ranged from 0.12 to 0.32N, whereas the chain-of-knots scleral fixation ranged from 0.07 to 0.27N. Both techniques showed an increase in the force required to disinsert fibers from the sclera in the early postoperative period. In this rabbit model, knotless ePTFE scleral fixation demonstrated increasing early mechanical stabilization. The differences between the two fixation techniques may be caused by a combination of mechanical factors and tissue adaptation, although these findings remain exploratory. Both techniques may provide sufficient early fixation strength in an experimental setting and support further preclinical and clinical evaluation.

The need to develop high-performance optoelectronic and semiconductor materials drives the search for new materials with tunable electronic and optical properties. The alkaline earth metal tellurides (AEMTe, where AEM = Be, Mg, Ca, Sr, and Ba) are particularly appealing among the group II-VI binary semiconductors because of their unique electrical structures and potential for band gap engineering. This study employs a thorough DFT-based methodology to examine the structural and optical characteristics of these structures. To guarantee high-fidelity findings, we combined scalar-relativistic ONCV pseudopotentials with RRKJ ultrasoft in the PBE-GGA framework. The core of our analysis centers on how the material shifts under strain; specifically, we evaluated electronic band structures at -5%, 0%, and +5% strains. This allowed us to determine exactly how compressive and tensile forces modify the compounds' fundamental characteristics. Phonon dispersion calculations confirm the dynamical stability of the cubic phases of BeTe, CaTe, SrTe, and BaTe, but suggest structural instability of the cubic Zinc Blende phase of MgTe. Notably, the band gap pressure coefficients are found to be anomalous, with most compounds showing negative pressure coefficients except for MgTe, which shows a strong positive pressure coefficient due to its dynamical unstable character. The exhaustive computational results demonstrate that the dynamical stable members of the AEMTe series offer very responsive and tunable electronic and dielectric environments. The strict qualitative trends offer strong evidence that epitaxial strain engineering might find successful applications to systematically tune absorption thresholds, dielectric screening and static refractive indices. Therefore, these strained alkaline earth metal tellurides are found to be very promising foundational candidates for future theoretical explorations and experimental integrations in advanced optoelectronics and strain-sensitive sensory architectures.

Bone is a major mechanosensitive organ that continuously responds to physical cues in the body. Although mechanical stimulation plays important roles in skeletal development, homeostasis, and injury repair, the specific responses of skeletal stem cells (SSCs) to mechanical stress remain incompletely understood. To address this question, we established an in vitro model to isolate mouse periosteal SSCs and apply mechanical stimulation. Mouse periosteal cells were first obtained by enzymatic digestion, and SSCs were subsequently isolated by fluorescence-activated cell sorting (FACS) based on established surface markers. After attachment to culture, SSCs were subjected to tensile mechanical stimulation using a cyclic cell stress-tension system. This system enables the reproducible application of tensile force to cultured cells and provides a platform for analyzing SSC responses to mechanical input. Using this approach, we found that the expression of the cellular senescence-associated genes p16 and p21 was markedly reduced in SSCs following mechanical stimulation. These findings suggest that tensile stimulation may influence senescence-related changes in SSCs under in vitro conditions. Overall, this protocol provides a useful and suitable platform for studying SSC behavior under mechanical stimulation and for investigating how mechanical cues affect SSC function.

Adhesion-controlled mechanics of the glial niche regulate neural stem cell proliferative potential.

The mechano-sensitivity of bone marrow-derived macrophages (BMDMs) is crucial for bone remodeling. In addition to force strength, BMDMs also showed a force-direction-dependent response. However, how anisotropic force regulates the function and differentiation of BMDMs is still under debate. Herein, a single-cell-level force-application system was developed to manipulate cells in a noncontact model based on biospecific magnetic microbeads. By adjusting the magnetic field parameters, the microbeads attached to the cell surface can generate controllable forces with specific directions. BMDMs exhibited differential responses to tensile and compressive forces regarding cell spreading. Surprisingly, although less potent than tensile force, compressive force demonstrated a significant suppressive effect on the osteoclast differentiation of BMDMs. The results suggest that this cellular behavior results from distinct pathways through which BMDMs sense and transduce tensile and compressive forces. BMDMs sense tensile force signals through α5β1 integrin and transduce them via the Rac-pPAK pathway. Compressive force, however, initially activates αvβ3 integrin on BMDMs, leading to signal transduction through the RhoA/ROCK-pMLC signaling axis that regulates BMDM differentiation. Furthermore, both in vitro coculture and in vivo subcutaneous ectopic osteogenesis studies suggest that tensile and compressive forces not only individually regulate the fate specification of BMDMs and BMSCs but also simultaneously mediate the crosstalk between these cell types. These findings provide novel insight into the mechanoresponsive mechanisms of BMDMs, deepening our understanding of mechanically induced bone remodeling.

This study aimed to compare the effect of PTFE tape wrapping and PTFE-coated titanium alloy screws on the removal torque after cyclic loading and on preload values under repetitive tightening. A total of 60 titanium abutment screws were allocated to three surface-treatment groups (n = 20 each): untreated (Control), PTFE tape-wrapped (Wrap), and PTFE-coated (Coat). Within each group, 10 specimens underwent cyclic loading, whereas 10 were assigned to preload evaluation. Cyclic loading followed ISO 14801:2016. Screws were tightened to 30 N·cm, retightened after 10 min, and subjected to 300 000 cycles at 200 N using a fatigue testing machine (DYNA-MESS Prüfsysteme GmbH, Aachen, Germany). Removal torque was measured with a digital torque gauge (BTGE50CN, Tohnichi, Japan). For preload assessment, each specimen completed 10 tightening-loosening cycles at the same torque during which tensile force was recorded using a customized device. One representative screw per group was analyzed by SEM and micro-CT before and after loading to evaluate surface and structural changes. After cyclic loading, the removal torque did not differ significantly between the Control group (17.58 ± 1.85 N·cm) and the Wrap group (17.50 ± 1.77 N·cm), whereas the Coat group demonstrated significantly lower removal torque (14.71 ± 2.35 N·cm; p < 0.05). In the preload test, preload progressively decreased in the Control (-3.13 N per cycle) and Coat groups (-0.51 N per cycle), while the Wrap group showed a consistent increase with repeated tightening (+8.22 N per cycle). SEM revealed surface wear and partial loss of PTFE material after loading, particularly in the coated specimens. Micro-CT analysis showed no detectable differences in internal adaptation among groups before or after cyclic loading. PTFE tape wrapping increased preload during repeated tightening but did not improve removal torque after cyclic loading compared with those of untreated screws. Although PTFE-coated screws produced the highest initial preload, they were associated with reduced removal torque after loading. SEM analysis confirmed coating deterioration, whereas internal fit remained comparable across groups.

One-dimensional (1-D) tension stiffening is a fundamental behavior of structural concrete. It refers to the composite uniaxial behavior of a slender, symmetric concrete member of constant cross-section, bonded to a single reinforcing bar (rebar) along its axis. The rebar is subjected to tension by a pair of axial tensile forces applied at its ends. Despite the apparent simplicity of this configuration, the problem represents a cornerstone in RC mechanics. During the loading process, cracks are formed at different cross-sections along the structural member at stages where the tensile stress in the concrete at these cross-sections reaches the concrete tensile strength level. Each crack formation reduces the overall axial stiffness of the RC member, while inducing stress and strain redistributions in both the concrete and the rebar. The interaction between the concrete and the rebar is governed by the bond–slip relationship along their interface, which plays a critical role in controlling the transfer of stresses, the development of strains and the evolution of cracking. Most existing analytical and numerical models addressing this problem are based on simplifying assumptions assuming constant (deterministic) material properties and are denoted herein as “deterministic models”. Comparisons between analysis results of such models and experimental observations reveal substantial discrepancies in terms of the number of cracks, their spatial distribution, crack spacing, and the order of crack formation. Considering these inconsistencies, the present study postulates that the inherent variability of concrete properties, particularly its tensile strength, has a decisive influence on the structural response. To address this issue, the tensile strength of concrete is treated as a random variable characterized by the prescribed mean tensile strength and the coefficient of variation (CoV). The “stochastic analyses” with the variable tensile strength are conducted using an exact one-dimensional finite element formulation that explicitly accounts for discrete crack formation within the structural domain. These analyses yield results that differ markedly from those predicted by the deterministic approaches and exhibit characteristics that are in closer agreement with experimental evidence. These analyses indicate a more complex behavior of real structural members. It demonstrates that the CoV significantly influences the magnitude of cracking loads, crack locations, crack spacing, and the order of crack formation. The findings highlight the critical role of even slight material variability in tension stiffening behavior and justify the incorporation of concrete strength variability in tension stiffening modeling.

Stochastic thresholds in hemostasis and thrombosis: A multiscale biophysical framework from transcriptional bursting to thrombin propagation.

Implant-supported overdentures improve denture retention and patient satisfaction, but debonding of attachment housings from the denture base remains a frequent prosthetic complication. This in vitro study evaluated the influence of attachment-housing and denture-base materials on debonding occurrence and maximum tensile force in resin-cemented attachment housing denture-base complexes subjected to cyclic mechanical loading. Thirty standardized specimens were digitally designed and fabricated from three denture-base materials—polymethylmethacrylate (PMMA) (n = 12), polyetheretherketone (PEEK) (n = 12), and cobalt-chromium (Co-Cr) (n = 6)—and combined with either titanium or PEEK attachment housings, which were bonded with a dual-polymerized resin cement. The specimens were subjected to 1100 cycles of alternating tensile and compressive loading, and debonding occurrence and maximum tensile force were recorded. Debonding occurred in 60% of the specimens and differed significantly among denture base materials. No debond-ing was observed in the Co-Cr specimens, whereas debonding occurred in 75% of the PMMA and PEEK specimens. The Co-Cr specimens also demonstrated significantly higher maximum tensile force values than the PMMA and PEEK groups, while regarding the attachment-housing material, no significant main effect was detected. Within the limitations of this in vitro study, the denture-base material, fabrication, and surface treatment combinations significantly influenced debonding and tensile force during cyclic loading, whereas the attachment-housing material did not demonstrate a significant main effect.

Lumbar disc herniation (LDH) is a prevalent spinal disorder. As a non-pharmacological therapy in traditional Chinese medicine (TCM), manipulation is widely employed in the conservative management of LDH and has garnered considerable attention due to its notable clinical efficacy. This paper aims to review the mechanism of TCM manipulation in the treatment of LDH, and analyze the existing evidence from the multi-dimensional integration of "biomechanical stimulation, cell signal transduction, system physiological response". At the biomechanical level, TCM manipulation can adjust the spinal force line, improve the relative position relationship between nerve roots and protrusions, and relieve mechanical compression by applying precise tensile, rotational and shear forces. At the level of cell signal transduction, mechanical stimulation is sensed by mechanoreceptors such as integrins and Piezo1/2 channels on the membrane of nucleus pulposus and annulus fibrosus, and starts Ca2+ influx and intracellular cascade reaction. By regulating Hippo/Yes-associated protein, etracellular signal-regulated kinase1/2 and other key pathways, mechanical signals are transformed into chemical signals, thereby inhibiting cell apoptosis, promoting extracellular matrix synthesis, and regulating inflammatory response. At the level of system physiological response, TCM manipulation intervention can regulate the nerve immune two-way network and alleviate chemical nerve root inflammation;At the same time, by reducing peripheral noxious input, it can reverse the structural and functional remodeling of the central nervous system in patients with LDH, thus breaking the vicious circle of "pain-dysfunction". In conclusion, TCM manipulation exerts therapeutic effects through a multi-level integrated mechanism involving mechanical decompression, regulation of cellular signal transduction, modulation of neuroimmune inflammation, and central functional remodeling. This paper also points out the existing problems and challenges in this research field, and provides suggestions for future research directions. This review provides a richer scientific basis for the clinical application of TCM manipulation and promotes its popularization and application.

This study aimed to investigate the tissue elastic properties of the orbicularis oris muscle inferior during physical growth and development in children. The orbicularis oris muscle inferior was examined at rest and during muscle contraction generating maximal tensile force (MCT) through a button-pull exercise using sonographic elastography. The inclusion criteria for participants were the absence of organic disorder in the orbicularis oris muscle and the presence of stable occlusion. A total of 146 participants (77 males and 69 females) aged 4-17years were included. The strain ratio of the orbicularis oris muscle inferior was measured at rest and during MCT, and the average values for each age were calculated. The average strain ratio for all ages was 0.77 ± 0.15 at rest and 1.22 ± 0.29 during MCT through a button-pull exercise. The average strain ratio of the orbicularis oris muscle inferior at rest ranged from 0.67 to 0.87 across all ages, whereas that during MCT through a button-pull exercise ranged from 1.14 to 1.36. The tissue elasticity of the orbicularis oris muscle inferior in children was found to remain almost constant at rest and during MCT, regardless of age. These findings indicated that tissue elasticity was stable and that the average strain ratio at rest and during MCT can be used to evaluate perioral muscles, particularly the orbicularis oris muscle inferior in the maxillofacial region during physical growth and development in children.

Catch bonds-dynamic molecular interactions whose lifetimes increase under mechanical load-are central to biological mechanotransduction but remain challenging to replicate synthetically. Here, we report a covalent catch-bonding mechanism in a low-molecular-weight motif based on hydroxyethyl phosphate (HEP) triesters. Our design uses force-mediated inhibition of a neighboring group participation (NGP) pathway: mechanical tension suppresses intramolecular assistance, thereby increasing the reaction barrier and prolonging bond lifetimes. Density Functional Theory calculations confirm that tensile force hinders the geometric contraction required for NGP, providing a mechanistic basis for catch-bond behaviour. Single-molecule force spectroscopy reveals that HEP triester lifetimes increase over threefold at 400 pN. This work establishes a molecular mechanism for engineering covalent catch bonds, offering opportunities to design force-responsive polymer networks. By translating a biological concept into a synthetic framework, our findings open new avenues for adaptive materials and mechanochemical sensing.

Impaired wound healing in type 2 diabetes is largely attributed to dysregulated cellular responses, defective extracellular matrix (ECM) remodeling, insufficient angiogenesis, and a prolonged inflammatory microenvironment. Understanding how these processes can be modulated at the cellular and tissue levels remains essential for improving diabetic wound repair. In this study, we examined the effects of a decellularized dermal scaffold (DDS) combined with photobiomodulation therapy (PBM), applied as an adjunct biophysical stimulus, on angiogenic, inflammatory, and matrix remodeling responses in a type 2 diabetic rat wound model. Full-thickness excisional skin wounds were created and assigned to control, DDS-treated, PBM-treated, or combined DDS + PBM groups. Wound tissues were harvested on days 8 and 16 post-injury for macroscopic evaluation, biomechanical testing, histological and histochemical analyses, and cytokine quantification. Morphometric assessment revealed that wounds receiving the combined intervention exhibited significantly accelerated wound contraction compared with single-modality and untreated groups at both timepoints. Biomechanical analyses demonstrated improved tissue integrity in treated wounds, with the combined group showing the highest values of tensile strength, maximum force, energy absorption, and bending stiffness, indicative of enhanced structural organization. Histological evaluation showed that DDS combined with PBM markedly increased fibroblast density and neovascularization while reducing inflammatory cell infiltration. Histochemical staining further demonstrated more advanced and organized collagen deposition in the combined group, reflecting accelerated ECM maturation and remodeling. At the molecular level, treated wounds displayed elevated levels of pro-regenerative mediators, including transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor (VEGF), with maximal expression observed in the combined group. Conversely, the expression of proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) was significantly attenuated. Collectively, these findings indicate that integrating a decellularized dermal scaffold with adjunct photobiomodulation effectively modulates cellular behavior, angiogenic signaling, inflammatory responses, and ECM remodeling in diabetic wounds. This study provides mechanistic insight into scaffold-based microenvironmental regulation of impaired wound healing under diabetic conditions.

Strategy based on liquid crystal elastomer active tensile to accelerate bone repair: Mechanistic analysis of LAMB1-ITGB4 mediated PI3K-AKT signaling