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Ultramarathons are a unique model to study the effects of systemic fatigue in athletes. This investigation applied the spring-mass template to study runners before and 2 days after a road ultramarathon to characterize the effects of fatigue on systemic gait patterns. Overground kinetics were captured 7 days before and 2 days after the event in 14 runners. Traditional kinetic and spring-mass parameters were calculated, along with nonlinear regression-derived parameters and spring-mass model fit metrics. After the ultramarathon, vertical force magnitudes and loading rates were unchanged, but impact peaks increased (1.88 ± 0.08–1.95 ± 0.10 bodyweight). Ground contact times were modestly shorter (−3 ± 1 ms), resulting in increased leg stiffness (10.0 ± 0.5–10.3 ± 0.5 kN/m) with equivocal vertical stiffnesses. The deviation from the modeled spring-mass kinetics also increased (171.3 ± 15.0–181.4 ± 16.5 N). Overall, the systemic mechanical behaviors of the runners persisted despite the fatigue and stress induced by a road ultramarathon. These findings support previous observations that runners maintain gross mechanical behavior when fatigued with small compensatory changes in spatiotemporal and traditional spring-mass characteristics. However, these findings also suggest that the variability within that gross behavior may increase after stress, suggesting new opportunities for quantifying those deviations. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the test–retest reliability and usefulness of the foot–ankle rebound-jump test (FARJT) for measuring foot–ankle reactive strength metrics in athletes. Methods: Thirty-six highly trained, healthy athletes (5 female; 21.5 [3.9] y; 1.80 [0.10] m; 72.7 [10.4] kg) performed 8 repeated bilateral vertical foot–ankle rebound jumps on 2 testing days. Testing days were 1 week apart, and these sessions were preceded by a familiarization session. Reactive strength metrics were calculated by dividing jump height (in meters) by contact time (in seconds) for the reactive strength index (RSI) and flight time (in seconds) by contact time (in seconds) for the reactive strength ratio (RSR). The mean of 4 jumps (excluding the first and last 2 jumps) on each testing session were considered for RSI and RSR reliability and usefulness analysis. Results: We found a high reliability of the FARJT for RSI (intraclass correlation coefficient [ICC] >.90 and coefficient of variation [CV] = 12%) and RSR (ICC ≥.90 and CV = 8%). Regarding their usefulness, both RSI and RSR were rated as "marginal" in detecting the smallest worthwhile change (typical error > smallest worthwhile change) and "good" in detecting a moderate change in performance. Conclusions: The results showed that a FARJT is a highly reliable test for measuring foot–ankle reactive strength in athletes and useful for quantifying changes, for example, following a training block. However, its usefulness as an accurate daily or weekly monitoring tool in practice is questionable. [ABSTRACT FROM AUTHOR]

Pancreatic ductal adenocarcinoma (PDAC) accounts for about 90% of all pancreatic cancer cases. Five-year survival rates have remained below 12% since the 1970s, in part due to the difficulty in detection prior to metastasis (migration and invasion into neighboring organs and glands). Mechanical memory is a concept that has emerged over the past decade that may provide a path toward understanding how invading PDAC cells "remember" the mechanical properties of their diseased ("stiff", elastic modulus, E ≈ 10 kPa) microenvironment even while invading a healthy ("soft", E ≈ 1 kPa) microenvironment. Here, we investigated the role of mechanical priming by culturing a dilute suspension of PDAC (FG) cells within a 3D, rheologically tunable microgel platform from hydrogels with tunable mechanical properties. We conducted a suite of acute (short-term) priming studies where we cultured PDAC cells in either a soft (E ≈ 1 kPa) or stiff (E ≈ 10 kPa) environment for 6 h, then removed and placed them into a new soft or stiff 3D environment for another 18 h. Following these steps, we conducted RNA-seq analyses to quantify gene expression. Initial priming in the 3D culture showed persistent gene expression for the duration of the study, regardless of the subsequent environments (stiff or soft). Stiff 3D culture was associated with the downregulation of tumor suppressors (LATS1, BCAR3, CDKN2C), as well as the upregulation of cancer-associated genes (RAC3). Immunofluorescence staining (BCAR3, RAC3) further supported the persistence of this cellular response, with BCAR3 upregulated in soft culture and RAC3 upregulated in stiff-primed culture. Stiff-primed genes were stratified against patient data found in The Cancer Genome Atlas (TCGA). Upregulated genes in stiff-primed 3D culture were associated with decreased survival in patient data, suggesting a link between patient survival and mechanical priming.

Purpose: Advanced footwear technology is prevalent in distance running, with research focusing on these "super shoes" in competitive athletes, with less understanding of their value for slower runners. The aim of this study was to compare physiological and biomechanical variables between a model of super shoes (Saucony Endorphin Speed 2) and regular running shoes (Saucony Cohesion 13) in recreational athletes. Methods: We measured peak oxygen uptake (VO2peak) in 10 runners before testing each subject 4 times in a randomly ordered crossover design (ie, Endorphin shoe or Cohesion shoe, running at 65% or 80% of velocity at VO2peak [vVO2peak]). We recorded video data using a high-speed camera (300 Hz) to calculate vertical and leg stiffnesses. Results: 65% vVO2peak was equivalent to a speed of 9.4 km·h−1 (0.4), whereas 80% vVO2peak was equivalent to 11.5 km·h−1 (0.5). Two-way mixed-design analysis of variance showed that oxygen consumption in the Endorphin shoe was 3.9% lower than in the Cohesion shoe at 65% vVO2peak, with an interaction between shoes and speed (P =.020) meaning an increased difference of 5.0% at 80% vVO2peak. There were small increases in vertical and leg stiffnesses in the Endorphin shoes (P <.001); the Endorphin shoe condition also showed trivial to moderate differences in step length, step rate, contact time, and flight time (P <.001). Conclusions: There was a physiological benefit to running in the super shoes even at the slower speed. There were also spatiotemporal and global stiffness improvements indicating that recreational runners benefit from wearing super shoes. [ABSTRACT FROM AUTHOR]

The cornea, as a dynamic and responsive tissue, constantly interacts with mechanical forces in order to maintain its structural integrity, barrier function, transparency and refractive power. Cells within the cornea sense and respond to various mechanical forces that fundamentally regulate their morphology and fate in development, homeostasis and pathophysiology. Corneal cells also dynamically regulate their extracellular matrix (ECM) with ensuing cell-ECM crosstalk as the matrix serves as a dynamic signaling reservoir providing biophysical and biochemical cues to corneal cells. Here we provide an overview of mechanotransduction signaling pathways then delve into the recent advances in corneal mechanobiology, focusing on the interplay between mechanical forces and responses of the corneal epithelial, stromal, and endothelial cells. We also identify species-specific differences in corneal biomechanics and mechanotransduction to facilitate identification of optimal animal models to study corneal wound healing, disease, and novel therapeutic interventions. Finally, we identify key knowledge gaps and therapeutic opportunities in corneal mechanobiology that are pressing for the research community to address especially pertinent within the domains of limbal stem cell deficiency, keratoconus and Fuchs' endothelial corneal dystrophy. By furthering our understanding corneal mechanobiology, we can contextualize discoveries regarding corneal diseases as well as innovative treatments for them.

In recent years, significant research has been conducted to explore the use of 3D triply periodic minimal surface (TPMS) structures for their exceptional vibrational damping properties and their ability to provide a continuous, smooth surface. The emergence of 3D printing has enabled the application of TPMS structures in fields such as medicine and aviation. In civil engineering, the compressive capacity of structures is a fundamental parameter in structural design. To evaluate the potential of porous TPMS structures in civil engineering, we have designed and manufactured four types of Skeletal-TPMS units using Stereolithography (SLA) technology. Axially loaded tests and nonlinear finite element method (NFEM) simulations have been performed to investigate the compressive strength and stiffness of the units. Our findings indicate that compared to solid blocks, the compressive strength of Skeletal-TPMS units decreases by 71.3% to 82.6%, and the stiffness decreases by 64.9% to 79.2%. The Skeletal-SP units show better compressive resistance than Skeletal-IWP units. This study provides new valuable insights for structural design and applications using TPMS structures in civil engineering. [ABSTRACT FROM AUTHOR]

This study aimed: (i) to investigate the impact of fatigue, triggered by maximal isometric contraction exercises, on the active and passive stiffness of plantar flexors (PF), and (ii) to examine the relationship between changes in mechanical parameters and neuromuscular alterations after fatigue. A healthy cohort (n = 12; age = 27.3 ± 5.5 y; BMI = 24.4 ± 2.35 kg/m²) was instructed to perform 60 isometric contractions, each lasting 4 s with a 1-s rest interval, using an ergometer. Several measures were taken before and after the fatigue protocol. First, the stiffness of the PF-tendon complex (PFC) was quantified during passive ankle mobilization both during and after the fatigue protocol using the ergometer. Additionally, from shear wave elastography, the active and passive stiffness of the gastrocnemius medialis (GM) were measured during passive ankle mobilization and isometric maximal voluntary contraction (MVC), respectively. Finally, the peak torque and the rate of torque development (RFD) of PF were assessed during the MVC using the ergometer. Ankle muscle activities (surface electromyograph [SEMG]) were recorded during all evaluations using electromyography. After the fatigue protocol, the results revealed a decline in active stiffness, peak torque of PF, RFD and SEMG activity of the GM (p < 0.001). Furthermore, significant correlation was identified between the decrease of the peak torque of PF and the active stiffness of the GM (r = 0.6; p < 0.05). A decrease in the PFC stiffness (p < 0.001) and a decrease in the shear modulus of the GM at 20° (p < 0.001) were also observed. Isometric fatiguing exercises modify the mechanical properties of both the contractile and elastic components. Notably, decreases in both passive and active stiffness may be critical for athletes, as these changes could potentially increase the risk of injury. [ABSTRACT FROM AUTHOR]

This paper presents a study on strengthening infill walls using composite materials to enhance shear capacity. The cementitious matrix-grid (CMG) material was employed for this purpose. Various configurations of the CMG, including single or double layers, applied to one or both sides of the wall, with or without anchorage, were tested. The study consisted of two stages. Initially, the mechanical properties of the bricks, mortar, and CMG mortar were determined using twenty-seven specimens. In the second stage, ten specimens, divided into five groups with one group left unstrengthened, underwent shear tests. Shear strength and shear strain relationships were determined for each specimen. Comparative analysis between strengthened and unstrengthened specimens revealed the effectiveness of the strengthening technique. The strengthened specimens exhibited superior structural performance compared to the control specimens. Specifically, the average maximum shear strength of all strengthened specimens surpassed that of the controls. Moreover, double-layer strengthening notably improved ductility. The findings suggest that applying a double layer of CMG to both sides of the wall with anchorage is the most effective method for strengthening. CMG composites significantly enhance the shear strength of infill walls and promote ductile failure. The comparisons of different strengthening combinations can contribute significantly to the existing literature and the construction sector by offering retrofitting options that can be tailored to address various economic and temporal, as well as target strengthening considerations. [ABSTRACT FROM AUTHOR]

Tranexamic acid (TXA) reduces bleeding and hematoma rates in open elbow arthrolysis. However, its effects on arthroscopic elbow arthrolysis remain unclear. This study aims to evaluate the effect of TXA on elbow arthroscopic procedures and compare bleeding volume, hemarthrosis, visual analog scale (VAS) for pain, range of motion (ROM), and Mayo Elbow Performance Score (MEPS) in the early postoperative period between patients who received intra-articular TXA and those who did not. A prospective, double-blind, randomized controlled trial enrolling 80 patients with stiff elbows who underwent arthroscopic arthrolysis was performed from January 2021 to December 2022. Intra-articularly, 1 g of TXA in 100 ml of saline or placebo (control group) was administered after the arthroscopic operation according to randomization. Parameters were recorded and compared between the groups, including bleeding volume of drainage, hemoglobin (Hgb) level, ratio of arm and forearm circumference of the surgical side to the contralateral side, grading of hematoma, VAS, ROM, and MEPS within 1 week postoperatively. And during 1 year follow-up, ROM and MEPS were recorded. All patients enrolled in this study demonstrated significant improvements in ROM (flexion-extension) and MEPS 1 week postoperatively, with no significant differences observed between the 2 groups. Compared to the control group, the TXA group exhibited significant differences in the bleeding volume of drainage (61.45 ± 47.7 ml vs. 89.8 ± 47.0 ml, P =.030) and a higher Hgb level 24 hours postoperatively (13.5 ± 1.5 g/dL vs. 12.6 ± 1.8 g/dL P =.049). While the ratio of arm and forearm circumferences significantly increased 24 hours postoperatively compared to preoperative values in TXA group (1.05 ± 0.06 vs. 1.02 ± 0.04 and 1.02 ± 0.06 vs. 0.98 ± 0.04, with P =.019 and P =.005, respectively), this difference vanished 1 week postoperatively for the ratio of arm circumference. However, it persisted for the ratio of forearm circumference (1.02 ± 0.07 vs. 0.98 ± 0.04, P =.003). Furthermore, there was no significant difference in MEPS, VAS, or ROM between the 2 groups 1 week postoperatively. Patients with stiff elbows who underwent arthroscopic arthrolysis achieved satisfactory clinical outcomes very early postoperatively. Compared to the control group, patients who underwent arthroscopic elbow arthrolysis with intra-articular administration of TXA exhibited significantly less bleeding volume of drainage and slightly higher Hgb levels postoperatively. One week postoperatively, slightly more swelling in the upper arm region was noted in the control group compared to the TXA group. These findings suggest that the intra-articular injection of TXA after arthroscopic release for elbow stiffness may statistically reduce complications related to postoperative bleeding. However, it's clinical relevance needs further investigation. [ABSTRACT FROM AUTHOR]

The main objective of this study was to compare the interface pressure applied by four different compression bandages (two elastic, one inelastic, and one multi-layer system), in various static and dynamic conditions and over time. The second objective was to compare their Static Stiffness Index and their Dynamic Stiffness Index. The compression bandages were applied on 20 legs of healthy females. Interface pressure was measured at two different points of the leg (ankle and calf), at rest in two positions (standing, supine), and during walking sequences. Interface pressure depends mainly on the mechanical properties of compression devices and on the subject morphology. Both elastic and multilayer compression devices exhibited a pressure gradient loss from the ankle to the calf. Over time, pressure loss was higher for inelastic compression bandages (p < 0.001) than for elastic and multilayer compression systems. Pressure variation from a supine to a standing position, and during walking, was higher for both inelastic bandage and multilayer system, than for elastic bandages (p < 0.01) whatever the measurement time and the measurement point. For all compression devices, pressure variation during walking at the ankle was about 25% of the pressure variation when switching from a supine to a standing position. These results provide a better understanding of the behavior of various bandage types. The pressure variations measured during walking are lower than those obtained when the subject switches from a supine to a standing position. This study suggests that the efficacy of compression bandages relies on the interface pressure that they exert on the legs, and the capacity of the patient to walk, which activates calf muscle. [ABSTRACT FROM AUTHOR]

Due to increasing demands regarding higher manufacturing accuracy and the machining of high-strength materials, the stiffness and load-carrying capacity of main spindles must be enhanced. One approach is to replace the conventionally used angular contact ball bearings, so called spindle bearings, with tapered roller bearings of the same size, which have a higher stiffness and load carrying capacity due to their larger rolling contact. In case the speed requirement is below a speed parameter n · d m = 0.9 × 10 6 mm/min, the poorer speed parameter of tapered roller bearings can be compensated by a sufficiently high lubrication quantity. However, the stiffness increase by using this bearing type in main spindles has not yet been quantified in field tests. Therefore, the aim of this paper is to demonstrate the stiffness advantage of a spindle with an elastically arranged tapered roller bearing compared to a conventional spindle with angular contact ball bearings by machining tests. First, the radial load displacement characteristic of the newly developed tapered roller bearing spindle is tested in advance on an isolated test rig. In machine cutting tests, full slots are milled in an aluminum block. During the tests, the axial and radial displacements of the spindle shaft relative to the housing are measured and evaluated in radial and axial direction. These tests are repeated and compared with the conventional spindle. By varying the process parameters such as cutting depth, feed rate or rotational speed, the increased stiffness of the tapered roller bearing spindle compared to the conventional spindle is illustrated based on the measured displacements. Moreover, frequency response measurements at different speeds underpin the improved damping of the tapered roller bearing spindle. Assuming that the speed requirements are not too high and the tapered roller bearing is sufficiently lubricated, the use of this type of bearing can significantly increase the stiffness and thus the manufacturing precision in the long term for main spindles. [ABSTRACT FROM AUTHOR]

Aging-induced aortic stiffness has been associated with altered fatty acid metabolism. We studied aortic stiffness using cardiac magnetic resonance (CMR)-assessed ventriculo-arterial coupling (VAC) and novel aortic (AO) global longitudinal strain (GLS) combined with targeted metabolomic profiling. Among community older adults without cardiovascular disease, VAC was calculated as aortic pulse wave velocity (PWV), a marker of arterial stiffness, divided by left ventricular (LV) GLS. AOGLS was the maximum absolute strain measured by tracking the phasic distance between brachiocephalic artery origin and aortic annulus. In 194 subjects (71 ± 8.6 years; 88 women), AOGLS (mean 5.6 ± 2.1%) was associated with PWV (R = −0.3644, p < 0.0001), LVGLS (R = 0.2756, p = 0.0001) and VAC (R = −0.3742, p <0.0001). Stiff aorta denoted by low AOGLS <4.26% (25th percentile) was associated with age (OR 1.13, 95% CI 1.04–1.24, p = 0.007), body mass index (OR 1.12, 95% CI 1.01–1.25, p = 0.03), heart rate (OR 1.04, 95% CI 1.01–1.06, p = 0.011) and metabolites of medium-chain fatty acid oxidation: C8 (OR 1.005, p = 0.026), C10 (OR 1.003, p = 0.036), C12 (OR 1.013, p = 0.028), C12:2-OH/C10:2-DC (OR 1.084, p = 0.032) and C16-OH (OR 0.82, p = 0.006). VAC was associated with changes in long-chain hydroxyl and dicarboxyl carnitines. Multivariable models that included acyl-carnitine metabolites, but not amino acids, significantly increased the discrimination over clinical risk factors for prediction of AOGLS (AUC [area-under-curve] 0.73 to 0.81, p = 0.037) and VAC (AUC 0.78 to 0.87, p = 0.0044). Low AO GLS and high VAC were associated with altered medium-chain and long-chain fatty acid oxidation, respectively, which may identify early metabolic perturbations in aging-associated aortic stiffening. Trial registration: ClinicalTrials.gov Identifier: NCT02791139 [ABSTRACT FROM AUTHOR]

Recently, plasma process-induced damage (PID) has garnered significant interest in the design of thin dielectric films implemented in semiconductor devices. Silicon nitride (SiN) films, a material of interest in strain engineering, are found to suffer from PID because they are exposed to various plasmas during device manufacturing processes. Only a limited amount of experimental evidence is available at present regarding plasma-induced mechanical property changes of SiN films. In this study, we investigated the mechanical property change in SiN and SiO2 films using a cyclic nanoindentation technique. We focused on the contact stiffness (S) as the principal mechanical property parameter. Firstly, a single loading/unloading test confirmed an increase in S after Ar and He plasma exposures. Subsequently, we examined the time-dependent features of damaged SiN and SiO2 films under cyclic loading/unloading. From the cyclic test, an increase in S was seen with the number of loading/unloading cycles (N) for both SiN and SiO2 films. A larger increase in S was observed for the damaged SiN, while no significant increase was seen for the damaged SiO2 films. The observed increase in S and its time dependence are attributed to the strain developed by the created defects (e.g. interstitial species) and the reconstruction and stabilization of plasma-damaged Si–N networks with created defects, respectively. The time-dependent S analysis under cyclic loading/unloading is useful for evaluating the effects of PID on the mechanical properties of thin films. [ABSTRACT FROM AUTHOR]

The ultimate load-carrying capacity of concrete-filled steel tubular (CFST) columns exposed to monotonic loadings can be greatly increased by strengthening those columns, and the occurrence of the steel tube's outward buckling can be postponed. The current research aims to study the possibility of improving the structural characteristics of CFST columns exposed to cyclic loadings in terms of lateral load capacity and absorbed energy by strengthening them with different patterns of fiber-reinforced polymer (FRP) sheets. The ABAQUS software was used to create a three-dimensional (3D) non-linear finite element model (FEM) to simulate the behavior of FRP-strengthened CFST columns exposed to monotonic and cyclic loadings. After ascertaining the accuracy of the proposed model's results in successfully predicting failure patterns and lateral loads compared to the experimental results of tested specimens available in the literature, the model was used to create a parametric study. The parametric study focused on the impacts of the thickness, location, and length of the strengthening sheets on the failure pattern, lateral load-carrying capacity, stiffness, cumulative energy, absorbed energy, and viscous damping factor of the CFST columns exposed to cyclic loadings. The results revealed that the un-strengthened specimen displayed a maximum lateral load of 185 kN and a viscous damping factor of 45.2% at a lateral drift of 5.7%. On the other hand, strengthening the CFST column using five layers of FRP sheets exhibited the highest lateral load of all investigated columns (50% more than the un-strengthened specimen). Additionally, at a lateral drift of 5.7%, the decrease in viscous damping factor of CFST specimens due to strengthening using 1, 2, 3, 4, and 5 layers of FRP sheets with respect to the control specimen was 7.9%, 14.9%, 20.8%, 27.7%, and 30.3%, respectively. [ABSTRACT FROM AUTHOR]

Time‐varying metamaterials offer new degrees of freedom for wave manipulation and enable applications unattainable with conventional materials. In these metamaterials, the pattern of temporal inhomogeneity is crucial for effective wave control. However, existing studies have only demonstrated abrupt changes in properties within a limited range or time modulation following simple patterns. This study presents the design, construction, and characterization of a novel temporal elastic metamaterial with complex time‐varying constitutive parameters induced by self‐reconfigurable virtual resonators (VRs). These VRs, achieved by simulating the resonating behavior of mechanical resonators in digital space, function as virtualized meta‐atoms. The autonomously time‐varying VRs cause significant temporal variations in both the stiffness and loss factor of the metamaterial. By programming the time‐domain behavior of the VRs, the metamaterial's constitutive parameters can be modulated according to desired periodic or aperiodic patterns. The proposed time‐varying metamaterial has demonstrated capabilities in shaping the amplitudes and frequency spectra of waves in the time domain. This work not only facilitates the development of materials with sophisticated time‐varying properties but also opens new avenues for low‐frequency signal processing in future communication systems. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the influence of intrinsic compositional parameters on the viscoelastic compliance by employing three-point bending creep tests on clear, i.e., defect-free, spruce samples with a dimension of 15 × 15 × 280 mm3. In addition to the regular samples, a prominent wood variation was investigated: so-called compression wood, stemming from an adaptive response of the growing tree to maintain structural stability. Tests were conducted at constant ambient conditions: isothermal at 20 degrees Celsius and at a relative humidity of 65 percent. These conditions were also employed during sample conditioning, leading to an equilibrium moisture content of the specimens of approximately 12 percent. Hence, so-called basic creep properties were investigated. Furthermore, we show that the experimentally observed compliance can be exceptionally well-modeled by a Scott Blair fractional-type element, with the latter calibrated by a mere number of two independent material parameters. This allows to render rather explicit dependencies of these parameters with respect to the dry density and the volumetric content of the compression wood. There, the quasi-instantaneous stiffness of the employed Scott Blair element is an increasing function of the dry density. While this primary dependency is also observed for compression wood, the quasi-instantaneous stiffness is significantly smaller over the investigated density range. [ABSTRACT FROM AUTHOR]

Background: Elevated spleen stiffness may be seen in patients with portal hypertension due to cirrhosis. In patients with Fontan physiology, elevated liver stiffness has been shown to correlate poorly with liver fibrosis. It is unknown whether spleen stiffness may instead serve as a surrogate marker of liver fibrosis in these patients. Objective: To compare spleen stiffness determined by shear wave elastography (SWE) with histological findings of an ultrasound-guided liver biopsy in patients who had undergone Fontan palliation as a potential surrogate for Fontan-associated liver disease. Materials and methods: This was an IRB-approved single-center, retrospective study. Patients with Fontan palliation who had undergone both a spleen SWE study and a percutaneous liver biopsy between 2016 and 2020 were included. Biopsy, performed during cardiac catheterization, within 3 months of the SWE was required for inclusion. Using Kruskal–Wallis tests, spleen stiffness was compared with three liver biopsy scoring methods: Ishak, METAVIR, and congestive hepatic fibrosis score (CHFS). When available, Pearson's correlation was also used to compare collagen deposition determined using Sirius Red stain (%SR) with SWE values. A P-value < 0.05 was considered statistically significant. Results: Twenty-two patients (15 males) were included in the study, with a median age of 17 years (IQR is 14.8–20.5 years; age range: 7 years to 30.2 years). The median spleen stiffness was 2.94 m/s (IQR: 2.57–3.61 m/s; range: 1.48–4.27 m/s). The median Fontan pressure was 11 mm Hg (IQR: 10–13.3 mm Hg; range: 7–19 mm Hg) obtained within a median of 10 days (IQR: 1–41 days) of SWE. Splenic stiffness did not correlate with the extent of fibrosis determined by histology (all P > 0.05). There was also no statistically significant correlation between the %SR staining and SWE-determined spleen stiffness (Pearson's correlation of 0.165, P = 0.59, n = 13). Conclusions: In this preliminary study, SWE spleen stiffness values did not correlate with biopsy-determined scoring of liver fibrosis in patients with Fontan physiology. [ABSTRACT FROM AUTHOR]

Confined brick masonry structures have garnered considerable attention as an effective solution for earthquake-prone regions due to their robust construction, efficient wall-to-column connections, and optimised utilisation of material strength. Within the realm of building design and construction, openings play a pivotal role, serving as essential elements for facilitating natural light and fresh air into the structure. However, the presence of openings within confined brick masonry walls causes a significant reduction in their seismic resistance. Hence, striking the right balance between these openings and structural strength is crucial. For this purpose, it is necessary to investigate the influence of size, shape, and position of the openings in confined brick masonry walls on their seismic performance. In this work, a comprehensive finite element macro-model is adopted that treats the wall and tie members as a unified system. A concrete damage plasticity approach is employed to predict damage progression in confined brick masonry walls. Using a pushover analysis in finite element framework, the ultimate strength, stiffness, and energy absorption capacity of confined brick masonry with different types of openings is assessed. Furthermore, a parametric study is conducted incorporating various scenarios, such as aspect ratios of confined brick masonry walls, diverse shapes of opening and variations in the positions of windows, doors, and combinations of both openings. Based on the results, simplified equations are developed to facilitate analytical estimation of ultimate strength, along with recommendations for optimising opening shape, size, and placement to enhance the design of confined brick masonry walls with openings. The study highlights that larger openings in confined brick masonry walls diminish ultimate strength, stiffness, and energy dissipation due to reduced load distribution and increased stress concentrations. Openings smaller than 10% of the masonry area maintain load paths, but larger openings require additional support. Rectangular openings with greater height than width exhibit superior performance. Furthermore, the positioning of windows significantly influences wall strength, with placements farther from the loading point proving favorable. Door placement also impacts ultimate strength, with central placement compromising stiffness. Combining window openings with a centrally located door maintains consistent ultimate strength but affects stiffness. Overall, this research contributes to a better understanding of the seismic behaviour of confined brick masonry structures with openings, offering valuable insights for engineers and architects working in regions susceptible to seismic activity. [ABSTRACT FROM AUTHOR]

Introduction: In the early postoperative period after total knee arthroplasty (TKA), joint range of motion (ROM) limitation and increased stiffness due to pain are commonly observed. Previous studies have reported that a single bout of foam rolling (FR) can acutely increase ROM and pain threshold on the contralateral (non-intervention) side in healthy participants. In this study, we aimed to expand this knowledge for TKA rehabilitation and investigated the acute effects of FR intervention on the non-operative side on ROM, stiffness, and pain of the operative side in postoperative patients within the first week after TKA. Materials and methods: The study employed a randomized crossover design: 20 patients (mean age 75.0 ± 7.8 years) in the first postoperative week after TKA were divided alternately into Roll_Break and Break_Roll groups in the order of prescription. In the Roll_Break group, after the initial evaluation, a 180-s (60-s × three sets) FR intervention using a roller massager by a physiotherapist for the knee extensors was performed on the contralateral side (non-operative side), followed by the measurement. Afterwards, after 180-s of supine at rest, the measurement was performed again (i.e., control phase). In the Break_Roll group, after the initial evaluation, each patient was placed in a seated resting position for 180-s, and then another measurement was performed (i.e., control phase). After this, the FR intervention was performed for 180-s, and then the measurement was performed again. The intensity of the FR intervention was set to the maximum intensity that did not cause pain. We measured pain using the visual analogue scale at rest and during the knee joint ROM measurements, knee joint active movement ROM, knee joint passive ROM, and stiffness during the knee joint active movement. Results: All outcome variables showed significant improvements after the FR intervention (intervention phase) when compared pre- to post-intervention, and significantly favourable effects were found compared to the control condition. Conclusion: The results showed significant improvements in ROM, pain, and stiffness of the operative side after the FR intervention on the non-operative side. For future therapy approaches for TKA patients, FR treatment of the non-operative side should be employed in the first weeks after surgery. [ABSTRACT FROM AUTHOR]

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations. [ABSTRACT FROM AUTHOR]

Children under the age of 14 years (U14) are particularly susceptible to musculoskeletal disorders because of growth spurts. Plyometric training has been shown to be beneficial for both injury reduction and performance enhancement. The aim of this study was to evaluate the effects of plyometric training on the jumping ability and running biomechanics of U14 track-and-field athletes. A single-blind randomized controlled trial was conducted. Thirty-five (18 female and 17 male) U14 athletes (age: 12.561.2 years; height: 152.367.7 cm; body mass: 47.366.9 kg) were randomized into experimental and control groups. All subjects completed their usual training for 4 weeks, and those in the intervention group added a low-volume plyometric program twice a week. Preintervention and postintervention assessments included a countermovement jump (CMJ) to determine maximum jump height, 10-second repeated jumps to assess reactive strength index (RSI), and a 3-minute run at 12 km·h21 to analyze running kinematics contact time, flight time, step length (SL), step frequency (SF), mean power output, vertical spring stiffness, and leg spring stiffness (LSS). The results revealed no main effect of time for any of the variables. A group-by-time interaction was found for RSI (p 5 0.045) in the intervention group, whereas a significant increase in LSS was also found after the intervention (p50.031). However, no changes in CMJ height or other running parameters were observed. The significance level for the study was set at r # 0.05. Plyometric-jump training may improve the stretch-shortening cycle in U14 athletes by increasing RSI and LSS. Athletes and coaches in running-related sports should be aware of these short-term effects when aiming to optimize the energy storage and release mechanism. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate changes in muscle contractile properties during a training microcycle in semi-professional female football players and explore their relationship with training load variables. Nineteen players (age: 23.9 ± 3.9 years; body mass: 60.6 ± 6.9 kg; height: 164.5 ± 6.7 cm) underwent myotonometric assessments of the biceps femoris (BF) and rectus femoris (RF) before and after the following training sessions: MD1 (i.e., 1 day after the match), MD3, MD4, and MD5. Training loads were quantified for each session, revealing significant variations, with MD4 exhibiting the highest values for high-speed running distance, number of sprints, and accelerations. Notably, MD3 showed the highest perceived exertion (RPE), while MD5 recorded the lowest total distance run. Myotonometric assessments indicated significant differences in stiffness of the RF in MD3 and BF in MD5, as well as RF tone in MD5. The findings underscore a notable relationship between training load and myotometric variables, particularly in muscle stiffness and tone. These results emphasize the need for further research to clarify how training loads affect muscle properties in female athletes. [ABSTRACT FROM AUTHOR]

Artificial cementation of granular soils results in improved stabilization, increased stiffness, and greater mechanical strength. The porosity index and volumetric cement content η / C i v a is presented as a key measure to study the evolution of different soil stabilization types. However, this index had not been previously studied or adjusted for sands in Colombia. Therefore, this study evaluates the applicability of the η / C i v a index on unconfined compressive strength (q u ) and stiffness ( G o ), complemented by microstructural analysis, in four sandy soils from Luruaco (Atlántico), Lorica (Córdoba), Medellín (Antioquia), and Bogotá D.C. The soils were stabilized with Type III Portland cement in dosages of 3%, 5%, 7%, and 9%, and subjected to UCS, ultrasound, and SEM-EDS tests after a curing period of 7 days. It was found that increasing cement content results in higher q u values for the samples, and higher molding density also leads to higher q u values. Additionally, the grain size distribution influenced the adjustment of parameter "a". In the sands from Bogotá and Lorica, with high uniformity, the value of "a" was 1.00. In contrast, mineralogy and particle shape played a predominant role in the sands from Medellín and Luruaco, where the coefficient of uniformity is higher, suggesting a possible inverse relationship between particle angularity and the value of "a". [ABSTRACT FROM AUTHOR]

Purpose: Most athletes experience short-term training cessation because of illness, injury, post-season vacation, or other reasons. Passive muscle stiffness is a potential risk factor for a sprint-type hamstring strain injury, but limited information is available about the effect of short-term training cessation on passive muscle stiffness. The present study aimed to identify whether and how passive muscle stiffness of the biceps femoris long head (BFlh) would vary due to 2 weeks of training cessation in sprinters. Methods: Passive BFlh shear-wave speed (a proxy for stiffness) was measured using ultrasound shear-wave elastography in 28 male sprinters, before and after 2 weeks of intervention. During the 2 weeks, the participants in the training-cessation group (n = 14) were allowed to maintain their normal daily activities but not to perform any physical training, including stretching and resistance exercises. The participants in the training continuation group (n = 14) performed the training (including maximum speed sprint, plyometric, and weight training) prescribed by their coaches 5 days per week. Results: In the training-cessation group, passive BFlh shear-wave speed increased after the 2 weeks of training cessation (4.75 ± 0.77 to 5.00 ± 0.88 m/s, P < 0.001). In contrast, there was no significant difference before and after the 2 weeks of training continuation (4.90 ± 0.85 to 4.93 ± 0.85 m/s, P = 0.521). Conclusions: The present findings indicate that muscles stiffen by training cessation in sprinting athletes. [ABSTRACT FROM AUTHOR]

This study investigated the effectiveness of carbon fibre-reinforced polymer (CFRP) materials in strengthening the diagonal tension members of steel-truss bridges. Monotonic tensile and cyclic loading tests were performed on CFRP-strengthened specimens with variations in the CFRP-bonding range on the flanges. This study focused on the strengthening methods A and B, which were proposed to address insufficient CFRP anchoring near gusset plates by bonding CFRP sheets to both sides of the flanges of the diagonal tension members. The results of the monotonic tensile loading tests indicated a significant increase in tensile stiffness and substantial improvements in yield strength (27%) and ultimate load-bearing capacity (51%) when the strengthening methods A and B were employed. Delamination of the bonded CFRP sheets was effectively delayed, occurring only after the steel yielded, owing to the use of a ductile adhesive (polyurea putty). On the other hand, the cyclic loading tests demonstrated a significant enhancement in the load-bearing capacities (33% for tensile, 32% for compressive) of the strengthened specimens. Moreover, the energy dissipation capacities of the specimens strengthened by methods A and B exhibited linear increases, with 12% and 14% higher values respectively than those of the non-strengthened specimen. Although the stiffnesses (tensile and compressive) of the strengthened specimens decreased in each loading loop, the strengthening methods A and B maintained the stiffness values at approximately 35% higher than those of the non-strengthened specimen. [ABSTRACT FROM AUTHOR]

The large particle sizes of railway ballast and rock fill have meant that conventional techniques used to measure the small-strain stiffness of finer geomaterials have not been adopted, with the consequence that their stiffnesses are poorly defined. In a series of tests on a UK railway ballast, simple adaptations were made to existing local strain measuring systems to account for the larger particle sizes. The study showed that the small-strain stiffnesses are different in second loading compared to virgin loading, but multiple cycles had little further effect on the stiffness. The large particle size was found rarely to have any detrimental effect on the quality of the strain measurements and the two independent measurements of axial strain taken at diametrically opposite locations were generally as consistent as for finer grained soils. As for other soils, the 'external' measurements of strain across the apparatus platens were of little use in determining stiffness. The presence of water did not have a significant effect on the behaviour, and this was confirmed by inter-particle loading tests on single particle contacts. Despite the use of lubricated end platens, there was a significant barrelling of the sample at large shear strains so that the internal measurement of the volumetric change diverged from the external measurement at large strains. The very small volumetric strains that occurred during isotropic loading meant that each sample could only be used to obtain one measurement of the virgin loading stiffness. [ABSTRACT FROM AUTHOR]

This research paper proposes a unique way to safeguard delicate systems on submerged platforms from the undesirable effects of underwater explosion shock loads. The underwater detonation of an explosive charge and mines produce devastating underwater shocks against underwater platforms. Shock load developed underwater has been analyzed, and a shock response spectrum (SRS) approach to compute shock peak responses has been adopted. SRS shock absorption frequency satisfies requirements for both shock absorption and delicate systems. The shock load was reduced to 2g by altering the delicate system stiffness and damping properties. The analytical model for a single DOF system was formulated, and simulation was carried out using ANSYS solver. The stiffness has been spread across various points along the length of the delicate system, allowing it to undergo translational oscillations when subjected to shock loads. This research paper presents an innovative design approach for a shock absorption system intended for underwater sensitive objects, emphasizing simplicity, distinctiveness, compactness, reliability, and electromagnetic compatibility. Experimental testing validated the shock absorption design on the prototype. Shock testing determined the absorber's maximum displacement and sensitive object acceleration. [ABSTRACT FROM AUTHOR]

The process by which placental trophoblasts fuse to form the syncytiotrophoblast around the chorionic villi is not fully understood. Mechanical features of the in vivo and in vitro culture environments have recently emerged as having the potential to influence fusion efficiency, and considering these mechanical cues may ultimately allow predictive control of trophoblast syncytialization. Here, we review recent studies that suggest that biomechanical factors such as shear stress, tissue stiffness, and dimensionally-related stresses affect villous trophoblast fusion efficiency. We then discuss how these stimuli might arise in vivo and how they can be incorporated in cultures to study and enhance villous trophoblast fusion. We believe that this mechanical paradigm will provide novel insight into manipulating the syncytialization process to better engineer improved models, understand disease progression, and ultimately develop novel therapeutic strategies. • Biomechanical stress has recently been suggested to influence trophoblast fusion. • These stresses may arise from fluid shear, matrix stiffness, and 3D architectures. • Recreating such stresses in culture models may improve in vitro syncytialization. [ABSTRACT FROM AUTHOR]

Complications following surgical repair of pelvic organ prolapse (POP) with polypropylene mesh (PPM) are common. Recent data attributes complications, in part, to stiffness mismatches between the vagina and PPM. We developed a 3D printed elastomeric membrane (EM) from a softer polymer, polycarbonate urethane (PCU). EMs were manufactured with more material given the low inherent material strength of PCU. We hypothesized that the EMs would be associated with an improved host response as compared to PPM. A secondary goal was to optimize the material distribution (fiber width and device thickness) within EMs, in regards to the host response. EM constructs (2 × 1 cm2) with varied polymer stiffness, fiber width, and device thickness were implanted onto the vagina of New Zealand white rabbits for 12 weeks and compared to similarly sized PPMs. Sham implanted animals served as controls. Mixed effects generalized linear models were used to compare the effect of construct type accounting for differences in independent variables. EMs had an overall superior host response compared to PPM as evidenced by preservation of vaginal smooth muscle morphology (p -values<0.01), decreased total cellular response to construct fibers (p -values<0.001), and a reduced percent of macrophages (p -values<0.02) independent of how the material was distributed. Both PPM and EMs negatively impacted vaginal contractility and glycosaminoglycan (GAG) content relative to Sham (all p -values<0.001) with EMs having less of an impact on GAGs (p -values<0.003). The results suggest that softer PCU EMs made with more material are well tolerated by the vagina and comprises a future material for POP repair devices. Prolapse is a debilitating condition in which loss of support to the vagina causes it and the organs supported by it to descend from their normal position in the pelvis. Surgical solutions to rebuild support involves the use of polypropylene mesh which is orders of magnitude stiffer than the vagina. This mismatch results in complications including exposure of the mesh into the vagina and pain. To provide an innovative solution for women, we have developed an elastomeric membrane from a soft polymer that matches the stiffness of the vagina. Here, we show in a rabbit animal model that this device incorporates better into the vagina and is associated with an overall improved host response as compared to polypropylene mesh. [Display omitted] [ABSTRACT FROM AUTHOR]

In modern infrastructure construction, the socket joint of concrete pipelines is a critical component in ensuring the overall stability and safety of the pipeline system. This study conducted monotonic and cyclic bending loading tests on DN300 concrete pipeline socket joints to thoroughly analyse their bending mechanical properties. The experimental results indicated that during monotonic loading, the relationship between the joint angle and bending moment exhibited nonlinear growth, with the stress state of the socket joint transitioning from the initial contact between the rubber ring and the socket to the eventual contact between the spigot and socket concrete. During the cyclic loading phase, the accumulated joint angle, secant stiffness, and bending stiffness of the pipeline interface significantly increased within the first 1 to 7 cycles and stabilised between the 8th and 40th cycles. After 40 cycles of loading, the bending stiffness of the joint reached 1.5 kN·m2, while the stiffness of the pipeline was approximately 8500 times that of the joint. Additionally, a finite element model for the monotonic loading of the concrete pipeline socket joint was established, and the simulation results showed good agreement with the experimental data, providing a reliable basis for further simulation and analysis of the joint's mechanical performance under higher loads. This study fills the gap in research on the mechanical properties of concrete pipeline socket joints, particularly under bending loads, and offers valuable references for related engineering applications. [ABSTRACT FROM AUTHOR]

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Accurate characterization of mechanical properties is crucial in the evaluation of therapeutic effects for problematic skin conditions. A pilot study was carried out using a novel optical coherence elastography (OCE) device, combining mechanical characterization through suction‐based deformation and imaging through optical coherence tomography. Using AI‐assisted image segmentation and a power‐law model, we were able to describe the mechanical behavior, comparing with measurements from the most commonly used commercial instrument (Cutometer) and subjective analyses of stiffness using the Patient and Observer Scar Assessment Scale. Twenty subjects were included with either keloids or hypertrophic scars. Measurements were fast and produced no discomfort. Mechanical and structural (epidermal thickness and rugosity) descriptors in pathologic skin conditions differed significantly from those in control tissue. We showed for the first time, the clinical feasibility of this novel suction‐based OCE device in evaluating mechanical and structural properties in pathological skin conditions such as scars. [ABSTRACT FROM AUTHOR]

The texture of meat is one of the most important features to mimic when developing meat analogs. Both protein source and processing method impact the texture of the final product. We can distinguish three types of mechanical tests to quantify the textural differences between meat and meat analogs: puncture type, rheological torsion tests, and classical mechanical tests of tension, compression, and bending. Here, we compile the shear force and stiffness values of whole and comminuted meats and meat analogs from the two most popular tests for meat, the Warner–Bratzler shear test and the double-compression texture profile analysis. Our results suggest that, with the right fine-tuning, today's meat analogs are well capable of mimicking the mechanics of real meat. While Warner–Bratzler shear tests and texture profile analysis provide valuable information about the tenderness and sensory perception of meat, both tests suffer from a lack of standardization, which limits cross-study comparisons. Here, we provide guidelines to standardize meat testing and report meat stiffness as the single most informative mechanical parameter. Collecting big standardized data and sharing them with the community at large could empower researchers to harness the power of generative artificial intelligence to inform the systematic development of meat analogs with desired mechanical properties and functions, taste, and sensory perception. [ABSTRACT FROM AUTHOR]

This article discusses the rationale and design of the study "Methotrexate, blood pressure, and arterial function in rheumatoid arthritis". The recognition that immune activation and excess inflammation favor atherosclerosis has stimulated a significant body of research not only to identify new drugs targeting these pathways but also to repurpose (reposition) existing immunomodulatory medications as atheroprotective agents. Observational studies in patients with rheumatoid arthritis have reported that treatment with methotrexate, a traditional disease-modifying antirheumatic drug, is associated with a significantly lower risk of cardiovascular morbidity and mortality when compared with other disease-modifying antirheumatic drugs. One potential mechanism accounting for the reduced cardiovascular risk associated with methotrexate is the lowering effect on arterial blood pressure. However, such effect has only been observed in cross-sectional and observational studies. Given the established role of hypertension as a leading cardiovascular risk factor, these observations justify an intervention comparison study, the focus of this article, investigating the temporal effects of methotrexate on blood pressure and various surrogate markers of atherosclerosis in patients with rheumatoid arthritis. The results of this study might lead to the repurposing of methotrexate for cardiovascular prevention in patients with and without autoimmune disorders. Clinical Trial Registration:NCT03254589 (ClinicalTrials.gov). Plain Language Summary This article describes a research study looking at the effects of a well-established antirheumatic drug, methotrexate, on blood pressure and blood vessels in patients with rheumatoid arthritis, a disabling condition affecting the joints as well as other organs and tissues. Methotrexate is commonly used in rheumatoid arthritis, given its ability to suppress inflammation and the activation of the immune system. However, excessive inflammation and immune activation are linked to atherosclerosis, a condition characterised by the build-up of plaques in blood vessels and the development of clots. Therefore, methotrexate might also be helpful in combating atherosclerosis because of its ability to suppress inflammation and immune system activation. We have previously observed that patients with rheumatoid arthritis receiving methotrexate have lower blood pressure when compared with patients receiving other antirheumatic drugs. However, in this study we could not prove that methotrexate directly reduces blood pressure. Given that high blood pressure is well known to damage the blood vessels and promote atherosclerosis and its devastating manifestations, for example, heart attack and stroke, this article will discuss a new study that compares blood pressure for individuals assigned to different treatments to assess whether methotrexate can lower blood pressure over time and exert additional beneficial effects on blood vessels in patients with rheumatoid arthritis. The results of this study will be helpful in determining whether methotrexate can be routinely used to combat atherosclerosis and consequently reduce the risk of heart attack and stroke in patients with rheumatoid arthritis and, potentially, other patient groups. Article highlights There is an ongoing search for new drugs and the repurposing of marketed drugs with immunomodulatory effects conferring atheroprotection. The study "Methotrexate, blood pressure and arterial function in rheumatoid arthritis" will investigate whether methotrexate reduces blood pressure and markers of atherosclerosis in patients with rheumatoid arthritis. The results of this study will be helpful to determine whether methotrexate can be repurposed for cardiovascular prevention. [ABSTRACT FROM AUTHOR]

Discarded medical face masks endanger the environment worldwide. In this study, experiments were conducted to investigate the effect of a shredded face mask (SFM) at 0% (control mix), 0.5%, 1.0%, and 2.0% by volume of concrete in the form of pieces that were 1 cm wide and 2 cm long on the properties of fresh and hardened concrete. After performing experimental testing on the materials, finite element masonry prisms with dimensions of 400 × 200 × 560 mm3 were modeled on the ANSYS platform. Four prisms with different fabric contents were numerically examined to study the compressive behavior, and 12 prisms with three different mortar joints were analyzed under an incremental horizontal load in the presence of four vertical displacements of 0.5, 1.0, 3.0, and 4.5 mm. The results revealed that increasing the SFM content in concrete led to a decrease in fresh and hardened concrete properties, including density, slump, split‐tensile strength, and compressive strength, by 9.5%, 20%, 24%, and 34%, respectively, compared with the control concrete at 0.5%. Moreover, the addition of 0.5% SFMs to the prism bricks reduced the maximum compressive load, deflection, and strain energy by 24%, 10%, and 39%, respectively. Altering the mortar type and vertical load affected the lateral cyclic behavior of the prisms. Compared with the M3 prism subjected to the same axial displacement, the M2 prism had 21.36%, 11%, 27.2%, and 10.48% higher lateral peak load, lateral peak displacement, equivalent stress, and strain energy, respectively. Furthermore, the lateral stiffness of the prism increases as the axial pressure increases. The lateral peak load of the M3 prism measured at 1.0, 3.0, and 4.5 mm axial displacement was raised by 60%, 142%, and 182%, respectively, as compared with the same prism at 0.5 mm axial displacement. The outcome provides a feasible concept for reusing masks in concrete construction with controllable strength deterioration on the masonry prism at 0.5% recycled SFM, resulting in attractive responses of these composites at the nonstructural scale [ABSTRACT FROM AUTHOR]

In carbon allotropes, interfacial engineering of various sp2 nanocarbon building blocks has shown great promise in designing and fabricating creative nanocarbon assemblies with novel structural and functional properties. Here, a robust, flexible, metal‐like heterostructured carbon nanotube (CNT) film formed of amorphous graphene nanosheets (AGNs) on CNT networked film is demonstrated, presenting a sp3‐sp2 dominated interfacial heterostructure. Extensive characterization reveals that AGN exhibits a complete absence of long‐range periodicity with twisty six‐member rings. Such 2D graphene mailed 1D CNT structure endows the heterostructured carbon nanocomposite film with a combination of unique properties, including surface nano‐flattening (flatness fourfold of the raw CNT film), excellent anti‐wear performance, greatly enhanced modulus (enhanced by 400%), hardness (enhanced by 300 times), and conductivity (enhanced by 270%). Unlike conventional carbon‐based materials, such flexible films show distinct substantial deformability and rapid resilience over wide temperatures (−196–≈1300 °C), which facilitate the design of new‐concept lightweight high‐temperature resistant and shape‐transformable materials for advanced aerospace applications under extreme conditions. [ABSTRACT FROM AUTHOR]

Microfluidics cell encapsulation offers a way to mimic a 3D microenvironment that supports cell growth and proliferation, while also protecting cells from environmental stress. This technique has found extensive applications in tissue engineering and cell therapies. Several studies have demonstrated the advantages of graphene oxide (GO) as an osteogenic inducer; however, the significance of GO on stem cell fate in the single-cell state is still unclear. Here, a microfluidics-based approach is developed for continuous encapsulation of mesenchymal stem cells (MSCs) at the single-cell level using alginate microgels. So, single-layer graphene oxide (slGO) nanosheet is used to be encapsulated inside the alginate droplets. The results of AFM and SEM show that slGO can increase the roughness and reduce the stiffness of alginate hydrogels. The Young's modulus of the alginate and alginate-slGO was obtained as 1414 kPa and 985.9 kPa, respectively. Live/dead assay and fluorescence microscopy images illustrate that slGO can maintain the viability and proliferation of microencapsulated hBMSCs. The obtained results show that slGO increases the mineralization of the encapsulated hBMSCs, so that microgels containing hBMSCs gradually became opaque during 21 days of culture. RT-qPCR results indicate that the expression of OCN, Runx2, and ALP in the alginate-slGO microgels is significantly higher than in the alginate microgels. The expression of OCN and Runx2 in the alginate-slGO microgels is 4.27 and 5.87-fold higher than in the alginate microgels, respectively. It can be concluded that low doses of slGO nanosheets have the potential to be utilized in the development of tissue engineering and bone regeneration. This finding offers a new method for creating injectable tissue transplants that are minimally invasive. [ABSTRACT FROM AUTHOR]

Steel shear wall (SSW) is an efficient system used to construct and improve many structures over the past decades. The main weakness of the traditional flat plate SSW is the premature buckling of the plate, for which the corrugated steel shear wall (CSSW) is a suitable alternative. However, the reduced resistance of CSSW compared to flat SSWs is a disadvantage. In this research, their reinforcement by flat steel plates with different dimensions and thicknesses has been used to improve the behavior of vertical trapezoidal steel shear walls (VTSSW). The samples studied in this research were subjected to cyclic loading after verification in Abaqus finite element software. The outcomes showed that reinforcing CSSWs with flat plates increased strength and energy absorption between 6 to 63% and 16 to 92%, respectively. Also, the equivalent viscous damping has increased between 5 and 82%. Also, due to strengthening the CSSWs, the pinching phenomenon in the hysteresis curves has been reduced, and the sudden decrease in strength after buckling in the CSSWs without stiffener has been significantly reduced. [ABSTRACT FROM AUTHOR]

Introducing novel advancements in hybrid nanocomposites, this paper presents a comprehensive theoretical investigation into the stiffness and coefficient of thermal expansion (CTE) of nanotube (NT) and nanoplatelet (NP)‐reinforced materials. Employing the Mori–Tanaka method, the study unveils the effective stiffness and CTE values. With the developed modeling approach, the research delves into hybrid nanocomposites of diverse configurations, ranging from unidirectional arrangements to intricate 2D and 3D random structures. By exploring the effects of hybridization across these configurations, valuable insights into the optimal design and performance of the hybrid nanocomposites are uncovered. [ABSTRACT FROM AUTHOR]

This paper presents a multiscale experimental study integrated with numerical simulations examining the mechanics of polydisperse granular mixtures composed of coarse‐grained particles mixed with varying percentages of fines. The study includes macroscale wave propagation tests using bender elements on isotopically compressed granular samples to investigate the stiffness variation with changes in size ratio (SR) and fines content (FC). Empirical equations were developed to predict stiffness based on the experimental data, using the concept of equivalent void ratio to represent the influence of void ratio on stiffness. A newly introduced parameter called size disparity indicator was used to consider the coupled effects of size disparity and fines content on stiffness. Microscale assessment of the individual contacting grains revealed that stiffness (at grain scale) is affected by changes in grain size, even when the SR is less than 6, however, the experimental observations of the shear modulus behavior from the macroscale test results reveal minimal effect of FC. Furthermore, numerical simulations using the discrete element method were conducted on the polydisperse granular mixtures to demonstrate the coupled effect of SR and FC on the structural matrix formation, thereby influencing the force transfer among contacts resulting in varying stiffness behavior. Our findings provide valuable insights into the behavior of polydisperse granular mixtures in engineering applications. [ABSTRACT FROM AUTHOR]

Background: Musculoskeletal alterations causing reduced range of motion of the ankle joint are common in children with cerebral palsy (CP). Objective measurements of passive joint resistance and three-dimensional skeletal muscle volume and muscle architecture can lead to a comprehensive understanding of which factors influence joint range of motion. Research question: To investigate the relation between the passive dorsiflexion of the ankle joint, biomechanical contributing factors to the passive joint resistance, and muscular architectural properties of the triceps surae muscle in children with CP. Methods: In this cross-sectional observational study, 14 children with spastic CP (bilateral: 5, unilateral: 9, Gross Motor Function Classification System (GMFCS) level I:11, II:3) naïve to intramuscular tone reducing treatment, and 14 TD children were included. The passive dorsiflexion of the ankle was measured with a goniometer. Passive joint resistance and related parameters were estimated based on a biomechanical model and measurements using a motorized device, the Neuroflexor. Three-dimensional muscle architecture was quantified with diffusion tensor magnetic resonance imaging (DT-MRI). Results: In the CP group, the median [min, max] passive dorsiflexion was decreased in the most affected leg (MAL) compared to the less affected leg (LAL) (2.5° [-25°, 20°] vs. 12.5° [5°, 30°], p = 0.001). The stiffness coefficient (Nm/rad) in the MAL was significantly higher in children with CP compared to TD children (7.10 [3.39, 62.00] vs. 2.82 [1.24, 10.46], p = 0.015). Muscle architecture properties did not differ between CP and TD, except for pennation angle in the medial gastrocnemius (MG) of the MAL (CP 17.64° (2.29) vs. TD 21.46° (3.20), p = 0.017). The stiffness coefficient, in the MAL, correlated negatively to passive dorsiflexion (rs=-0.638) and pennation angle in medial gastrocnemius (rs=-0.964), and the non-linear coefficient (Non-linear 1) correlated negatively to the fascicle length of the medial gastrocnemius (rs=-0.857). Conclusion: This study shows that stiffness of the plantarflexors is related to decreased passive dorsiflexion of the ankle and muscle structure of the MG in high-functioning children with spastic CP. Assessments of how dynamic components as well as microscopic muscle alterations contribute to joint stiffness in the plantarflexors in individuals with CP are warranted. Trial registration: Retrospectively registered in ClinicalTrials.gov, NCT05447299. Observational study. Study start: 2019-01-15, register date: 2022-07-01. [ABSTRACT FROM AUTHOR]

In view of the high cost of bridge load test and the high professional requirements for test personnel, in order to provide more realistic theoretical data for bridge monitoring, a method of correcting theoretical parameters based on structural static test results was proposed. This method can consider the shear deformation between T-beams, and is more suitable for the actual connection between beams than the hinged T-beam method, which greatly improves the analysis accuracy and reduces the professional requirements for the test personnel. The proposed method was applied to the transverse distribution coefficient and stiffness analysis of plexiglass hinged T-beam bridge model. The results show that without considering the influence of shear force between beams, the calculation results of the influence line of load transverse distribution are consistent with those of the hinged T-beam method under the analysis and calculation of the simplified analysis model, which ensures the accuracy of the simplified model and analysis results. The load transverse distribution coefficient obtained by the proposed method is better than that of the hinged T-beam method, and it can more accurately reflect the actual stiffness of the bridge. Based on the static measured response value of the plexiglass model, the key control parameters of the simplified analysis model are identified. Based on the measured data, the modified theoretical model and the lateral distribution coefficient calculated by the software extraction value, the difference is small. It is proved that the method can better reflect the actual stiffness of the bridge and provide more realistic theoretical data for monitoring. It can be seen that the static model optimization analysis of the simply supported T-beam bridge, the optimization rate of the deflection of the beam under the most unfavorable load is 27. 71%. Under the three working conditions, the numerical optimization rate of the influence line of the beam with the largest deflection is 34. 82%, 13. 07% and 5. 46%, respectively. [ABSTRACT FROM AUTHOR]

The development of an arthrofibrosis (AF) is reported as one of the most common complications of orthopedic operations with special emphasis on total knee replacement and anterior cruciate ligament reconstructions. Even though all joints may be involved, most cases involve the knee joint. Patients feel a painful decrease in the range of motion caused by fibrotic tissue formation within and outside the joint. The healing process is disturbed by mechanical and emotional stress and strong pain. Most AF cases show the typical symptoms of pain and decreased range of motion within the first days after surgery, causing failure to pass the quality standards. Physiotherapy and rehabilitation do not ameliorate symptoms, limiting activities of daily living (ADL). Clinical diagnosis, differential diagnosis and a novel pahogenetic- and staging model of primary arthrofibrosis with therapeutic principles and preventive measures are introduced in this article. [ABSTRACT FROM AUTHOR]