Extreme Deformation Research Articles

A Metalgel with Liquid Metal Continuum Immobilized in Polymer Network.

Gels are formed by fluids that expand throughout the whole volume of 3D polymer networks. To unlock unprecedented properties, exploring new fluids immobilized in polymer networks is crucial. Here, a new liquid metal-polymer gel material termed "metalgel" is introduced via fluid replacement strategy, featuring 92.40%vol liquid metal fluid as a continuum immobilized by interconnected nanoscale polymer network. The unique structure endows metalgel with high electrical conductivity (up to 3.18×106 S·m‒1), tissue-like softness (Young's modulus as low as 70kPa), and low gas permeability (4.50×10‒22m2·s‒1·Pa‒1). Besides, metalgel demonstrates electrical stability under extreme deformations, such as being run over by a 4.5-metric-tonne truck, and maintains its integrity in various environments for up to 180 days. The immobilization of high-volume-fraction liquid metal fluid is realized by electrostatic interactions is further revealed. Potential applications for metalgel are diverse and include soft electromagnetic shielding, hermetic sealing, and stimulating/sensing electrodes in implantable bioelectronics, underscoring its broad applicability.

Cooperative dynamics of PARP-1 zinc-finger domains in the detection of DNA single-strand breaks

The DNA single-strand break (SSB) repair pathway is initiated by the multifunctional enzyme PARP-1, which recognizes the broken DNA ends by its two zinc-finger domains, Zn1 and Zn2. Despite a number of experiments performed with different DNA configurations and reduced fragments of PARP-1, many details of this interaction that is crucial to the correct initiation of the repair chain are still unclear. We performed Molecular Dynamics (MD) computer simulations of the interaction between the Zn1/Zn2 domains of PARP-1 and a DNA hairpin including a missing nucleotide to simulate the presence of an SSB, a construct used in recent experiments. The role of Zn1 and Zn2 interacting with the SSB ends is studied in detail, both independently and cooperatively. We also explored, PARP-1 operating as a dimer, with the two Zn-fingers coming from two separate copies of the enzyme. By an extensive set of all-atom molecular simulations employing state-of-the art force fields, assisted by empirical docking and free-energy calculations, we conclude that the particular conformation of the DNA hairpin can indeed spontaneously open up by thermal fluctuations, up to extremely kinked deformations. However, such extreme localized deformations are rarely observed in free, long DNA fragments. Protein side-loops make contact with the DNA hairpin grooves, and help Zn2 to penetrate deep in the SSB gap. In this way, Zn2 can interact with the nucleotides opposite to the missing base. Overall, Zn1 plays a secondary role: the crucial factor for the interaction is rather the relative arrangement of the Zn1/Zn2 couple, and their mutual orientation with respect to the 3′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$3'$$\\end{document} and 5′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$5'$$\\end{document} SSB end terminals. This helps to obtain an early interacting configuration, which ultimately leads to molecular PARP-1-DNA structures similar to those observed experimentally. Such findings represent an important step toward defining the detailed function of PARP-1 in the early stages of SSB recognition.

On application of the relative entropy concept in reliability assessment of some engineering cable structures

The main research problem studied in this work is an uncertain response and reliability assessment of the spatial cable structures due to the environmental stochasticity as well as material and geometrical imperfections. Some popular cable structures are analyzed for this purpose using the Stochastic Finite Element Method (SFEM) implemented with the use of three different techniques, namely the iterative generalized perturbation method, semi-analytical approach as well as the Monte-Carlo simulation. Uncertainty quantification delivered in this study is based on the series of FEM analyses of both static and dynamic structural problems. They enable the Least Squares Method determination of the structural polynomial responses linking extreme stresses and deformations with several uncorrelated uncertainty sources. Reliability assessment, fundamental in durability and Structural Health Monitoring, is completed using a comparison of the First Order Reliability Method (FORM) with probabilistic distance formulated by Bhattacharyya. Input uncertainties are assumed to be Gaussian according to the Maximum Entropy Principle. They have specific expected values following engineering design demands or the provisions of designing codes, whereas their standard deviations do not exceed the 10% level. The methods presented and the results obtained in this study may serve for further reliability analyses of large-scale civil engineering structures completed with both steel cables and also reinforced concrete plates like suspended bridges, for instance.

Shear Band Formation with Split Hopkinson Bar Experiments

The essence of dynamic failure is closely linked to dramatic shear deformations which often lead to the formation of adiabatic shear bands (ASB). Under high loading velocities and the subsequent rapid temperature increase, the localization of shear strain is crucial in view of safety issues of systems in mechanical and aircraft engineering, especially with respect to fast rotating components and diverse crash scenarios. In this research, we perform high speed impact tests at the split Hopkinson pressure bar (SHPB) setup and use particular hat-shaped specimen geometries that resemble the stresses and failure conditions at the component level.In the first step, we specify a notched specimen geometry using finite element (FE) simulations to ensure pure shear. Further, quasi-static compressive tests and a series of impact tests at high strain rates of 103−104s−1 are conducted on specimens manufactured from a fine-grain structural steel with the properties of S355. Optical microscopy and electron backscatter diffraction (EBSD) of the sheared zones unveil significant localization to maximal shear strains of about 0.9 accompanied by grain refinement by factors 5 to 14. The displacements across the surface of the specimens are captured with subset-based local digital image correlation (DIC) during the impact time, and serve as an objective to validate a viscoplastic constitutive relationship. More precisely, the deformation distribution is accurately reproduced by the widely recognized Johnson-Cook (JC) model, which features an enhanced description of damage evolution. Thus, combining experimental and characterization techniques, continuum mechanics and reasonable optimization strategies for the identification of model parameters provides an efficient approach for comprehensive insights into the strain localization behaviour and its impact on the mechanical performance of S355 under extreme strain rates and deformations.

Outcomes of Charcot-Marie-Tooth Disease Cavovarus Surgical Reconstruction.

Charcot-Marie-Tooth (CMT) disease is a progressive inherited neurologic disorder causing muscle weakness and lower extremity deformity. The goal of foot and ankle surgical treatment is to create a stable, plantigrade foot, with the potential elimination of brace-wear for ambulation. The aim of this study was to report baseline CMT patient function and subsequent outcome improvement from surgical treatment, as determined by PROMIS physical function (PF), pain interference (PI), and mental health/depression (D) scores. Retrospective data were collected on consecutive CMT patients older than 18 years receiving surgical treatment by a single surgeon from 2018 to 2022 with minimum 1-year follow-up. Each patient prospectively completed PROMIS preoperatively and postoperatively after all planned surgical treatment was completed. Prospective clinical and radiographic data were collected to describe complications and correlation to outcome. Ninety-five feet in 64 patients older than 18 years were included for analysis. Mean follow-up was 21 months (range, 12-31) with 100% minimum 1-year follow-up. CMT patients had worse preoperative and baseline scores in all domains except PROMIS-D compared with population normal PROMIS scores. Significant improvements were identified in all PROMIS domains following surgical treatment. The mean PROMIS-PF score increased (40 to 45, delta = 4.9, P < .001), the mean PROMIS-PI score decreased (59 to 52, delta = 7.1, P < .001), and the mean PROMIS-D score decreased (50 to 47, delta = 3.0, P = .004). Subgroup analysis was performed for patients with severe radiographic deformity and those treated with arthrodesis in an attempt to demonstrate the impact of disease severity on outcome. Subgroup analysis demonstrated that arthrodesis led to worse overall PROMIS-PF outcome with the same change score. Surgical treatment for CMT patients provides significant clinical improvement in all measured outcome domains. CMT patients can be restored to normal population physical function and pain interference outcome scores. Patients with more severe deformity have similar improvement from surgical treatment, although their ultimate functional improvement is blunted due to a lower baseline.

Microstructural evolution and interfaces in cold sprayed hybrid aluminum alloy powders of different hardness

The development of thick cold sprayed deposits of hard amorphous/nanocrystalline Aluminum High Entropy Alloys (Al HEA) is limited by their poor plastic deformability. To address this, Al HEA powder (Al90.05Ni4.3Y4.4Co0.9Sc0.35 (at. %)) is blended with soft Al 6061 in a 1:1 wt% ratio and cold sprayed. The microstructure of the composite deposits reveals that while Al HEA splats undergo limited deformation, Al 6061 splats deform extensively. Extreme deformation of Al 6061 captures the hard Al HEA particles, resulting in a composite deposit of 5 mm thickness, compared to 0.2 mm for pure Al HEA. Within the composite, Al HEA particles deform through shear band propagation and viscous flow, whereas Al 6061 splats deform via dislocation slip motion. These deformation mechanisms induce interface nanocrystallization, leading to a 123 % increase in lattice strain, a 67 % reduction in crystallite size, and an 800 % increase in dislocation density compared to the initial feedstock. This microstructural evolution, combined with the presence of hard Al HEA regions, results in a mean hardness of 2.56 GPa and an elastic modulus of 76 GPa. These values represent a 47 % and 6 % improvement over conventional polycrystalline cold-sprayed aluminum deposits. Thus, this study provides insights into the microstructural and interface evolution and its effect on indentation characteristics for making high-strength Al HEA deposits.

Universal phase-field mixture representation of thermodynamics and shock-wave mechanics in porous soft biologic continua.

A continuum mixture theory is formulated for large deformations, thermal effects, phase interactions, and degradation of soft biologic tissues suitable at high pressures and low to very high strain rates. Tissues consist of one or more solid and fluid phases and can demonstrate nonlinear anisotropic elastic, viscoelastic, thermoelastic, and poroelastic physics. Under extreme deformations or shock loading, tissues may fracture, tear, or rupture. Existing models do not account for all physics simultaneously, and most poromechanics and soft-tissue models assume incompressibility of some or all constituents, generally inappropriate for modeling shock waves or extreme compressions. Motivated by these prior limitations, a thermodynamically consistent formulation that combines a continuum theory of mixtures, compressible nonlinear anisotropic thermoelasticity, viscoelasticity, and phase-field mechanics of fracture is constructed to resolve the pertinent physics. A metric tensor of generalized Finsler space supplies geometric insight on effects of rearrangements of microstructure, for example degradation, growth, and remodeling. Shocks are modeled as singular surfaces. Hugoniot states and shock decay are analyzed: Solutions account for concurrent viscoelasticity, fracture, and interphase momentum and energy exchange not all contained in previous analyses. Suitability of the framework for representing blood, skeletal muscle, and liver is demonstrated by agreement with experimental data and observations across a range of loading rates and pressures. Insight into previously unresolved physics is obtained, for example importance of rate sensitivity of damage and quantification of effects of dissipation from viscoelasticity and phase interactions on shock decay.

Stretchable complementary split-ring resonator using liquid metal and its application for cavity optomagnonics

Split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) are widely used in microwave devices. Considering its advantages of fluidity, high metallic conductivity, and extreme deformability, liquid metal is expected to enrich the tunability of SRR and CSRR. Here, a stretchable resonator based on CSRR, using liquid metal as the conducting layer and Ecoflex as the dielectric layer, is prepared by 3D printing. From the transmission spectra, we find that the resonant frequency can be continuously tuned from 3.77 to 3.40 GHz by stretching the resonator, which exhibits a stable quality factor, high ductility, excellent stretchability, and linearity. We then study the coupling between magnons in a yttrium iron garnet film and microwave photons in CSRRs. The anti-crossing effects are observed in transmission coefficient spectra by changing either the strength of the magnetic field or the size of the CSRR. The coupling strength g/2π is determined to be 63 MHz at a coupling frequency of 3.77 GHz and magnetic field of 800 Oe. Our findings could promote the development of reconfigurable metamaterials and cavity optomagnonics.

Clinical, Radiographic, and Biomechanical Evaluation of the Upper Extremity in Patients with Osteogenesis Imperfecta.

Introduction: Osteogenesis imperfecta (OI) is a hereditary disorder primarily caused by mutations in type I collagen genes, resulting in bone fragility, deformities, and functional limitations. Studies on upper extremity deformities and associated functional impairments in OI are limited. This cross-sectional study aimed to evaluate upper extremity deformities and functional outcomes in OI. Methods: We included patients regardless of their OI subtypes with a minimum age of 7 years. Radiographic analysis of radial head dislocation, ossification of the interosseous membrane, and/or radioulnar synostosis of the forearm were performed, and deformity was categorized as mild, moderate, or severe. Clinical evaluation was performed using the Quick Disabilities of Arm, Shoulder, and Hand (qDASH) questionnaire and shoulder-elbow-wrist range of motion (ROM). Three-dimensional motion analysis of the upper limb was conducted using the Southampton Hand Assessment Procedure (SHAP). The SHAP quantifies execution time through the Linear Index of Function (LIF) and assesses the underlying joint kinematics using the Arm Profile Score (APS). Additionally, the maximum active Range of Motion (aRoM) was measured. Results: Fourteen patients aged 8 to 73 were included. Radiographic findings revealed diverse deformities, including radial head dislocation, interosseous membrane ossification, and radioulnar synostosis. Six patients had mild, six moderate, and two severe deformities of the upper extremity. Severe deformities and radial head dislocation correlated with compromised ROM and worse qDASH scores. The qDASH score ranged from 0 to 37.5 (mean 11.7). APS was increased, and LIF was reduced in OI-affected persons compared with non-affected peers. APS and LIF also varied depending on the severity of bony deformities. aRoM was remarkably reduced for pro-supination. Conclusion: Patients with OI showed variable functional impairment from almost none to severe during daily life activities, mainly depending on the magnitude of deformity in the upper extremity. Larger multicenter studies are needed to confirm the results of this heterogeneous cohort. Level of evidence: Retrospective clinical study; Level IV.

Enhancing flexible electronics: Unveiling the role of strain rate in the performance of molybdenum-coated PET films

This work analyzes the mechanical and electrical properties of molybdenum (Mo) thin films at 100 and 200 nm thicknesses under different strain and strain rate circumstances. The study examines Mo film deposition by RF magnetron sputtering on PET substrates and their mechanical stress behavior. The investigation reveals distinct patterns of crack initiation and propagation, where primary cracks predominantly appear perpendicular to the direction of applied strain, and secondary cracks develop due to stress redistribution, displaying a complex interplay between film thickness, strain rate, and crack morphology. A key finding of this study is the observation of more advanced and irregular crack patterns in thicker films (200 nm) subjected to higher strain rates (1000 mm/min), suggesting a heightened sensitivity to mechanical stress and a more chaotic fracture process compared to thinner films or those under lower strain rates. Additionally, instances of film edge delamination, particularly under high strain conditions, highlight the challenges in maintaining film-substrate adhesion and integrity under extreme mechanical deformation. The research provides critical insights into the mechanical robustness and electrical performance of Mo thin films, emphasizing the influence of microstructural properties, deposition parameters, and external stressors on their applicability in high-tech industries. The findings underscore the importance of optimizing deposition techniques and understanding material behavior under stress to enhance the durability and reliability of Mo thin films in practical applications, ranging from semiconductor devices to photovoltaic systems.

Model test of extreme deformation and failure mechanism of automatically formed roadway under thick-hard roof

Automatically formed roadways (AFR) are highly susceptible to extreme deformation and damage under thick-hard roof geological conditions. Taking the thick-hard roof of the Yushuquan coal mine as a case study, this paper mainly studies the extreme deformation, failure mechanism, and control technology of the AFR. First of all, through on-site monitoring, the maximum vertical convergence rate of the AFR in thick-hard roof reaches 44.8 mm/d. The failure of the AFR mainly focuses on the roof sinking, coal rib rupture, and deformation of gangue prevention structure. Then, a model test was employed to analyze the deformation characteristics of the AFR, including the roadway roof, roadway floor, solid coal rib, and gangue rib. Furthermore, the failure mechanism of the AFR in thick-hard roof is explored. The model test shows that the rotation and subsidence of the roadway roof strata are the main factors causing the AFR damage. In turn, the subsidence of the roadway roof strata is controlled by the movement and distribution characteristics of the hard rock blocks within the cutting range. Eventually, cooperative control technology was proposed, including increasing the gangue volume in the goaf and increasing the coal rib strength to control the extreme deformation of the AFR in thick-hard roof conditions. Field engineering application demonstrates that the deformation of AFR surrounding rock is effectively controlled under thick-hard roof. The research findings can serve as a valuable reference for the prevention and control of the stability of AFR under complex geological conditions.

General particle dynamics: On the correlation of nonlocal and local theories for large deformation problems

This paper presents a detailed investigation on the General Particle Dynamics (GPD) method and its implications for addressing challenges in large deformation mechanics and fracture modeling. The GPD method integrates nonlocal interactions and nonlocal differential operators to overcome limitations of classical continuum mechanics in capturing long-range interactions and material behaviors under extreme deformation conditions. Through a systematic examination of the physical and mathematical foundations of GPD, including its governing equations and constitutive relations, we elucidate the robust and applicability of the proposed method in simulating complex deformation phenomena. Furthermore, the relationships among GPD, conventional mechanical theories (Smoothed Particle Hydrodynamics), nonlocal theory (Peridynamics) and Molecular Dynamic theories are discussed. Numerical examples related to large deformation and fracture problems are tested to verify the ability of the proposed method. The numerical results show that GPD inherits the advantages of the classical method and also has its unique properties in solid fracture mechanics and large deformation problems, making it a promising approach in computational mechanics.

Flexible/Regenerative Nanosensor with Automatic Sweat Collection for Cytokine Storm Biomarker Detection.

The real-time monitoring of low-concentration cytokines such as TNF-α in sweat can aid clinical physicians in assessing the severity of inflammation. The challenges associated with the collection and the presence of impurities can significantly impede the detection of proteins in sweat. This issue is addressed by incorporating a nanosphere array designed for automatic sweat transportation, coupled with a reusable sensor that employs a Nafion/aptamer-modified MoS2 field-effect transistor. The nanosphere array with stepwise wettability enables automatic collection of sweat and blocks impurities from contaminating the detection zone. This device enables direct detection of TNF-α proteins in undiluted sweat, within a detection range of 10 fM to 1 nM. The use of an ultrathin, ultraflexible substrate ensures stable electrical performance, even after up to 30 extreme deformations. The findings indicate that in clinical scenarios, this device could potentially provide real-time evaluation and management of patients' immune status via sweat testing.

Identifying Lower Extremity Deformities in the Coronal Plane: Lessons From Remote Learning During the COVID-19 Pandemic.

Introduction During the COVID-19 pandemic, the AO Foundation, an orthopedic education organization, had to transition its live education programs to an online format. Skills that were previously evaluated and corrected in person by educators were now assessed through online lectures and discussion groups. Our goal was to evaluate an online course designed to teach the skill of "leg length and coronal deformity measurement" and to assess participants' ability to demonstrate this skill using online software. Methods An IRB-approved study was conducted during an online osteotomy course. A total of 176 participants were instructed on how to measure length and angulation through the course lectures and planning tutorials. The Bonesetter App (Detroit Bonesetter, Detroit, Michigan, USA) was used as the digital planning tool. Participants analyzed four cases of coronal deformity using long-leg standing radiographs. They were required to identify any deformities present, specify the type of deformity, and determine whether it affected the femur, tibia, or joint. Additionally, participants needed to calculate the deformity as part of the osteotomy planning process. Their measurements and drawings were saved and subsequently evaluated by two independent observers. Results Out of 176 online participants, 76% (315 out of 417) correctly completed the four exercises. The most frequent errors occurred in measuring total deformity and joint deformity. The average standard deviation of length measurements was ±0.29 cm (based on 244 measurements), while for angular measurements, it was ±0.71 degrees (based on 688 measurements). The intraclass correlation coefficient was greater than 0.96. Conclusions The online course effectively taught coronal deformity measurement, although participants struggled most with measuring joint angles and total deformity. Future courses should provide more detailed explanations for these measurements.

Assessing and predicting surrounding rock settlement troughs in the subsea tunnel: A case study of Haicang Tunnel

To ensure the safety of subsea tunnel construction, it is crucial to prevent extreme deformation of the surrounding rock. An assessment and prediction study on the surrounding rock deformation induced by the excavation of the subsea tunnel using the three-bench method was conducted, based on Haicang Subsea Tunnel in Xiamen, China. A series of numerical simulations and on-site monitoring were conducted to reveal the evolution of the displacement field of the surrounding rock. The influences of various factors on the settlement trough of the surrounding rock above the subsea tunnel were also investigated, including seawater, bench length, and bench spacing. The rapid ring closure of the primary support by adopting short benches is imperative to control the arch settlement and settlement trough width. The settlement resulting from the excavation of the upper and middle benches contributed to 90% of the total deformation, as revealed by both numerical simulation and in-situ monitoring. Subsequently, an empirical formula was proposed to predict the settlement trough curves of surrounding rock at different depths above the seabed tunnel.

Hierarchical design of auxetic metamaterial with peanut-shaped perforations for extreme deformation: Self-similar or not?

Hierarchical designs have exhibited great potential in reducing structural weight and improving mechanical properties. However, the hierarchical design of perforated auxetic metamaterials with curved holes is rarely investigated and the choice of self-similar hierarchical design or not still confuses us. In this study, two types of hierarchical designs with self-similar and non-self-similar features for the auxetic metamaterial with peanut-shaped perforations are realized and compared. First, the printed hierarchical auxetic metamaterials via additive manufacturing technology are tested by quasi-static tension to explore their mechanical performance in different directions. Correspondingly, the computational homogenization model is established to characterize their full elastic properties and its effectiveness is verified by the experimental results. Subsequently, the deformation mechanisms of the proposed hierarchical metamaterials are numerically analyzed to address the superiority of self-similar design over the non-self-similar design. Finally, the influences of microstructural parameters and hierarchy order on the effective elastic constants of the proposed hierarchical metamaterial are considered and the optimal topology with extreme auxetic behavior is recommended. The results indicate that the proposed self-similar hierarchical design exhibits significant anisotropic feature, which can serve the multidirectional mechanical requirements, and the remarkable enhancement in auxeticity can be attributed to the synergistic deformation of tetrachiral sub-elements. Besides, the increase of hierarchy order does not continuously enhance the auxetic behavior of hierarchical metamaterial, although it can effectively change the porosity of structure. Through such investigations, a meaningful guidance of property map is provided for the hierarchical design of auxetic metamaterial perforated by curved cuts.

Lower extremity deformity and its risk factors in patients with solitary osteochondromas

BackgroundThis study aimed to demonstrate the occurrence of lower extremity deformities and their risk factors in patients with solitary osteochondromas.MethodsWe retrospectively reviewed consecutive patients with solitary osteochondromas around the knee. The laterality (left or right), involved bone (femur or tibia), tumor type (pedunculated or sessile), and direction (medial or lateral) were examined. The whole limb length (WLL), mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle (MPTA) were measured using teleroentgenogram. Lower limb deformity was defined as a difference of more than 5° in mLDFA or MPTA in both lower extremities or a difference in WLL of more than 1 cm. Patients were divided into two groups, with deformity and without deformity.ResultsLower extremity deformities were observed in 8 of 83 patients. Significant difference in the type of osteochondroma (p = 0.004) between the groups was observed. Differences in sex, age, laterality, involved bone, direction, and distance from the physis to the osteochondroma between groups were not statistically significant. The sessile type of osteochondroma was a risk factor for lower limb deformity with an odds ratio of 24.0 according to Firth’s logistic regression analysis.ConclusionIn our cohort with solitary osteochondroma, lower limb deformities were observed in 8 (9.6%) out of the 83 patients and these were significantly associated with sessile-type tumors. Therefore, patients with sessile-type solitary osteochondroma around the knee require careful surveillance of lower limb alignment with whole leg teleroentgenogram.

Normal Development of Tibiofemoral Angle in Healthy South-Eastern Nigerian Children: A Clinical Study on 3147 Children.

Angular deformities of the lower extremities are common in children and are a frequent reason for orthopaedic referral. These deformities, which are usually encountered when children start to walk are typically measured using the tibiofemoral angle (TFA), which represents the angle formed by the intersection of the anatomical axis of the femur with the anatomical axis of the tibia. This study aimed to determine the TFA in healthy South-Eastern Nigerian children, and to determine the effect of gender and age on this angle. This cross-sectional study was done in Enugu metropolis with 3147 school children and adolescents aged 3-17 years. It was found that the majority of the subjects (97.6%) had valgus TFA. The maximum knee valgus angle from the study was 6.8° ± 0.80° at 4 years. Thereafter, the knee valgus angle declined to a mean of 2° at 17 years. There were physiological changes in TFAs noted, which vary with regards to both age and gender of the subject.

Ultrastable fluorinated copolypeptide nanodroplets of loaded mixed liquids with low vaporization threshold

The expansion of ultrasound molecular imaging applications warrants a reduction in ultrasound contrast agent size and significant advancement in the in vivo stability of shell-stabilized bubbles. The shift from first to second-generation ultrasound contrast agents was marked by an improvement in stability as air was replaced by hydrophobic gases like perfluoropropane and sulfur hexafluoride. Further enhancements may be facilitated by focusing on strategies to retain the encapsulated gas within the ultrasound contrast agent shell despite extreme mechanical deformations. In this study, we developed a novel ultrasound contrast agent with a unique shell structure and a specially-formulated, low-boiling fluorinated liquid interior, resulting in superior stability during repeated and prolonged ultrasound-induced oscillations. Our ultra-stable nanodroplets can withstand sustained in vitro ultrasound exposure with minimal signal attenuation and can induce significant signal enhancement and delay in signal attenuation in the kidney, liver, and tumor tissues during in vivo experiments. Furthermore, encapsulating photosensitizers within these nanodroplets and leveraging photothermal effects could further augment the ultrasound imaging signal and verify its efficacy in tumor therapy. The creation of highly stable nanodroplets opens immense potential to augment the role of ultrasound in molecular imaging, therapy, and drug delivery.

Versatile data-adaptive hyperelastic energy functions for soft materials

Applications of soft materials are customarily linked to complex deformation scenarios and material nonlinearities. In the bioengineering field, soft materials typically mimic the low stiffness of biological matter subjected to extreme deformations. Computational frameworks surge as a versatile tool to assist the design of functional applications. The constitutive model lies at the core of such frameworks. In this regard, the customary extreme non-linear behavior of elastomers poses an additional challenge to thoroughly capture the material behavior. Here, data-driven methodologies hold considerable promise for enhancing constitutive modeling when contrasted with phenomenological approaches. In this investigation, we introduce a versatile data-adaptive method tailored to the modeling of hyperelastic soft materials at finite strains. Specifically, our method substitutes an a priori chosen model for the strain energy function by a flexible interpolant defined on a discretized invariant space. Within this framework, the interpolation values assume the role of material parameters and are determined through finite element model updating to conform to measured experimental data — comprising full-field displacements coming from Digital-Image-Correlation and global reaction forces. We validate the method on uniaxial experimental tests of soft elastomers, encompassing ELASTOSILTM, DOWSILTM, and V HBTM. Overall, we aim to establish a new route for the construction of hyperelastic energy functions, untethered from any predefined existing models or assumptions regarding the shape of the energy.