Peak Force Research Articles

BIOMECHANICAL INFLUENCE OF RUNNING SHOES WITH MIDSOLE HOLLOW STRUCTURE ON LOWER LIMBS DURING RUNNING

The objective was to investigate the effects of running shoes with midsole hollow structure span and height on the biomechanics of the lower limbs during running. We collected 21 adults with running habits who wore two pairs of running shoes with different midsole hollow structures and ran at a speed of 3.3[Formula: see text]m/s on a force-measuring treadmill. The lower limb kinematics, ground reaction force (GRF) and lower limb muscle activation characteristics were simultaneously captured by a motion capture system, a 3D force treadmill, and a surface electromyography (sEMG) system. Paired t-tests were performed on data for the two shoe conditions that fit the normal distribution assumptions; otherwise, Wilcoxon signed-rank tests were used. The statistical parameter mapping (SPM) technology was used for the analysis of 1D parameters of kinematic, dynamic, and sEMG activation characteristics. The result showed that the time to the peak impact force at touchdown of Hollow shoe2 was significantly increased ([Formula: see text]), the maximum loading rate ([Formula: see text]) and average loading rate ([Formula: see text]) were significantly reduced, braking time ([Formula: see text]), push time ([Formula: see text]), contact time ([Formula: see text]) of Hollow shoe2 were significantly increased compared with Hollow shoe1. Hollow shoe2 push phase of the tibialis anterior muscle activation characteristics was significantly lower (SPM, [Formula: see text]) than Hollow shoe1. Our conclusion is that running shoes offer the solution as they have the advantage of the complex structure of the hollow midsole.

Valorisation of bamboo stalk waste: eco-friendly synthesis and characterisation of activated carbon monolith

ABSTRACT In contemporary waste management, the escalating volumes of bamboo stalk waste present a pressing environmental challenge, necessitating innovative and sustainable solutions. This research examined the properties of activated carbon monolith (ACM) derived from bamboo stalk (BS) using a facile method. Polystyrene resin and KOH were employed as an eco-binder and activator in the monolith synthesis, respectively. Analytical methods were employed to characterise the mechanical, morphological, elemental, and textual profiles of the monolith obtained. The study's results indicated the creation of a monolith characterised by a rough, amorphous shape firmly secured by the binder. It revealed a BET surface area measuring 265 m2/g and a pore diameter of 2.8 nm. The monolith displayed various irregular void pores, forming a mesoporous morphological network, along with sporadically distributed slivery-white dot-like particles on its heterogeneous surface. EDX analysis also revealed the BS-ACM is largely composed of carbon (77%), potassium (11%), oxygen (8%), and trace amounts of aluminium, gold, iron, and plutonium. The compressive strength test indicated a peak force of 21,536 N before any significant signs of appreciable deformation were observed, with the subsequent estimation of Young's modulus at 8.34 MPa. Beyond advancing bamboo waste valorisation, the research aligns with circular economy principles and sustainable practices, presenting a promising pathway for developing eco-friendly materials and contributing to a more sustainable and resource-efficient future.

Effects of Hormonal Contraception and the Menstrual Cycle on Maximal Strength and Power Performance.

To evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared to an eumenorrheic (EUM) cycle, on maximal strength and power between hormone phases. One repetition max (1RM) leg press and bench press, peak force (PF) from knee extension and upright row isometric dynamometry, and power from vertical jump height (VJH) and reactive strength index (RSI; cm/s) were measured in 60 healthy, active women (mean ± standard deviation [SD]; Age: 26.5 ± 7.0 yrs, BMI: 22.5 ± 3.7 kg/m2) who were monophasic OC users for ≥6 months (n = 21), had a H-IUD for ≥6 months (n = 20), or had regularly naturally occurring menstrual cycle for ≥3 months or were using a non-hormonal IUD (EUM; n = 19). Participants were randomly assigned to begin in the follicular phase/placebo pill (low hormone phase; LHP) or in the luteal phase/active pill (high hormone phase; HHP) and were tested once in each phase. Estimates of total lean mass (LM), leg LM, and arm LM were measured via dual energy x-ray absorptiometry. Separate univariate ANCOVAs were used to assess the change from HHP to LHP between groups, with LM and progesterone as covariates. Leg press 1RM was significantly different across phases between groups (p = 0.027), with higher leg press 1RM in the HHP for the OC group (mean difference[∆HHP-LHP] ± standard error: ∆7.4 ± 15.9 kg; p = 0.043) compared to the H-IUD group (∆-8.9 ± 23.8 kg; p = 0.043). All groups demonstrated similar bench press 1RM, PF, VJH, and RSI between phases (p > 0.05). Lower body strength was greater in the HHP for OC users (5.6% increase) suggesting lower body maximal strength outcomes may be influenced by hormonal contraception type.

Multi-Objective Optimization of Crashworthiness of Shrink Tube Energy Absorption Structure

By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube’s structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized.

Hydrodynamic analysis of sea-crossing bridge piers subjected to freak waves

Coastal areas are witnessing a surge in critical infrastructure development, such as sea-crossing bridges, to support growing populations and economic activities. However, these structures face ongoing challenges in harsh marine environments. Therefore, understanding the hydrodynamics of bridge structures under extreme freak wave conditions is imperative for designing effective countermeasures. This study investigates pier hydrodynamics using a three-dimensional numerical flume simulated by OpenFOAM, focusing on loading characteristics and wave climb differences under freak and linear waves. Results show that freak waves induce larger surges and forces compared to linear waves, with a notable “bell vibration” effect near the wave surface. Moreover, peak forces and bending moments increase nonlinearly with the wave height-to-significant wave height ratio. For double-column piers, transverse alignment concentrates wave climb on the rear side of the front pier, with forces increasing with spacing, while those on the rear pier decrease. Conversely, longitudinal arrangements show amplified loading effects. These findings provide valuable insights into the hydrodynamic behaviour of bridge piers under freak wave conditions, offering practical implications for the design and protection of sea-crossing bridges.

Behind Armor Blunt Trauma: Liver Injuries Using a Live Animal Model.

While the 44-mm clay penetration criterion was developed in the 1970s for soft body armor applications, and the researchers acknowledged the need to conduct additional tests, the same behind the armor blunt trauma displacement limit is used for both soft and hard body armor evaluations and design considerations. Because the human thoraco-abdominal contents are heterogeneous, have different skeletal coverage, and have different functional requirements, the same level of penetration limit does not imply the same level of protection. It is important to determine the regional responses of different thoraco-abdominal organs to better describe human tolerance and improve the current behind armor blunt trauma standard. The purpose of this study was to report on the methods, procedures, and data collected from swine. Live swine tests were conducted after obtaining approvals from the local institution and the Army Care and Use Review Office of the U.S. Department of Defense. Trachea tubes and an intravenous line were introduced before administering anesthesia. Pressure transducers were inserted into the lungs and aorta. An indenter simulating the backface deformation profiles produced by body armor from military-relevant ballistics to human cadavers was used to deliver impact loading to the liver region. A triaxial accelerometer was included in the indenter design. The animals were monitored for 6 hours, necropsies were performed, and injuries were identified. Biomechanical data of the energy, velocity, deflection, viscous criterion, force, and impulse variables were obtained for each test. Peak accelerations, velocities, deflections, forces, impulse, and energies ranged from 897 to 5,808 g, 21 to 59 m/s, 1.96 to 8.87 cm, 2.3 to 13.1 kN, 1.1 to 7.1 Ns, and 58 to 387 J, respectively. The peak viscous criterion ranged from 0.8 to 5.8 m/s. All animals survived the 6-hour survival period. Three animals responded with liver lacerations while the remaining 4 did not have any injuries. The experimental design based on parallel tests with whole body human cadavers and cadaver swine was found to be successful in delivering controlled impacts to the liver region of live swine and reproducing liver injuries. Previously used biomechanical measures as potential candidates for injury criteria development were obtained. Using this proven model, tests with additional samples are needed to develop injury risk curves for liver impacts and obtain regional (liver) injury criteria.

Thrust of a pulsed plasma jet measured from deviations of a ballistic pendulum

We measured the peak force of the plasma jet produced by a pulsed coaxial plasma gun operated at voltages up to 2 kV, using a home-made ballistic pendulum positioned in two locations, one in the proximity of the gun nozzle at 0.75 cm and the second at a distance of 9 cm from the gun nozzle. The force of the plasma wind is inferred and ranges from 11 to 60 N, which is almost an order of magnitude higher than that of typical ion-based thrusters. The results of various models of self-field magneto-plasmadynamic thrusters indicate that the magnetic component thrust tends to dominate over the thermal expansion, particularly at higher discharge voltages of 1.5 kV and 2 kV. The highest thrust of 60 N is obtained for a 2 kV discharging voltage. The plasma was ignited in CO2 at pressures between 1 and 5 Torr. The displacement of the pendulum pushed by the plasma wind force was measured using a high-speed camera.

Flexural behavior of textile reinforced 3D printed concrete under quasi-static and dynamic impact loads

There has been a growing interest in utilizing 3D printing technology for military and civil defense engineering, especially in enhancing the resilience of infrastructure against impacts. Due to its distinctive additive manufacturing process, 3D printed concrete (3DPC) shows anisotropic behavior when subjected to static loads. However, research on its performance under dynamic conditions remains limited. Therefore, this study explores the characteristics of 3DPC under static and dynamic loads. Quasi-static results showed that incorporating textile significantly enhanced the deformation capacity of specimens, with the ultimate deflection and flexural toughness of basalt textile reinforced specimens in the X direction reaching 1.07 mm and 4206.9 N·mm, which are 118 % and 117 % higher than control specimens without textiles, respectively. The mechanical properties of 3DPC specimens showed increasing trend from static to impact loads. The impact results indicated that the peak load increased with the increase in impact energy. Adding two types of textiles showed different anisotropic mechanical properties which are associated with the patterns of cracking and failure. The addition of basalt textiles primarily enhanced the energy dissipation properties of 3DPC, with increases up to 98.2 %. The AR-glass textile was superior in terms of maintaining peak force under multiple impacts.

Effect of Temperature and Strain on Bonding of Similar AA3105 Aluminum Alloys by the Roll Bonding Process

Accumulative roll bonding (ARB) is a severe plastic deformation process that enables the production of materials with ultrafine microstructures and enhances the characteristics of the base material, particularly in metal matrix composites. The primary objective of this study is to experimentally investigate the bonding strength in AA3105 strips that underwent the roll bonding process, with a specific focus on examining the influence of temperature and reduction rate on bonding. Three temperature levels (200 °C, 300 °C, and 400 °C) and three thickness reduction levels (35%, 50%, and 65%) were considered. The T-peel test was carried out to assess the bonding quality. It was employed to determine the peak force required to separate the two bonded strips. Additionally, ANOVA analysis was performed to develop a regression equation for analyzing peak force. Optical microscopy was used to evaluate the interface bonding quality in the longitudinal section. The results indicate that the bonding strength increases with both temperature and percentage reduction.

Early Versus Late Rapid Force Production During Single-Joint Isometric Hamstring Assessment Using Force Plates.

Ripley, NJ, Barber, R, Fahey, JT, and Comfort, P. Early versus late rapid force production during single-joint isometric hamstring assessment using force plates. J Strength Cond Res XX(X): 000-000, 2024-The aim of this study was to assess differences in time-matched early versus late rapid force (RF) development in female soccer players in the 90-90 isometric hamstring assessment. Twenty-one elite female soccer players (age: 20.7 ± 4.7 years; height: 168.2 ± 5.5 cm; body mass: 62.8 ± 7.0 kg), with no recent (>6 months) history of hamstring strain injury, volunteered to participate in the study. Following a standardized warm-up, each subject performed 3 maximal isometric unilateral hamstring contractions, with their heel resting on a force plate, elevated on a box, to ensure that their hips and knees were at 90°. Data were analyzed to determine peak force, early RF (ERF) 0-100 milliseconds and late RF (LRF) 100-200 milliseconds. Significant and large differences were observed in the percentage of peak force achieved between ERF (52.85 ± 11.53%; 54.99 ± 9.80%) and LRF (15.82 ± 5.58%; 15.25 ± 3.91%) for the left and right limbs, respectively (p < 0.001, g = 2.13-3.06). The large differences between ERF and LRF can be used by practitioners to streamline performance assessment, which in turn will allow practitioners to act upon data collected more effectively. Additionally, regular monitoring ERF production could inform practitioners of any interventions that maybe required, such as reduction of load or introduction of specific recovery modalities and during return to play protocols.

Nature-inspired 3D printing-based double-graded aerospace negative Poisson’s ratio metastructure: Design, Fabrication, Investigation, optimization

The advanced metamaterials concept has been widely explored and utilized in many industries, ranging from automotive applications to medicine, and has great potential in the aerospace field. Novel nature-inspired 3D printed double-graded aluminum foam-filled negative Poisson’s ratio metamaterials (DGAT) were designed, fabricated, and investigated. Their mechanical properties were examined by the finite element method and experiments. The geometrical parameters and combination types show different effects on the mechanical properties of DGAT metastructures. Under axial compressive loading, the DGAT structure has a lower peak force and higher specific energy absorption. Then, parametric analysis shows that several design parameters (e.g. m, T, θ, tmin, tmax) have a very strong effects on the mechanical performance. Finally, multi-objective optimization is performed to maximize specific energy absorption while reducing maximum impact force. Optimization results show that the novel graded metamaterials have stronger energy absorption capacity than the ordinary counterparts. Especially, the specific energy absorption can be increased to 80% with 15% peak loading force rising. Due to their unique structural design and excellent mechanical properties, the DGAT metastructures have great potential applications in the fields of transportation protection, military protection engineering, manned spacecraft cushioning and energy-absorbing boxes.

Does the short-term learning effect impact vertical jump performance assessment on a portable force plate system?

One of the reoccurring questions that arises during the countermovement vertical jump (CVJ) assessment is whether the learning effect has an impact on the accuracy of the results obtained. Thus, the purpose of the present investigation was to examine the impact of the short-term learning effect on the assessment of lower-body neuromuscular performance characteristics when performed on a portable one-dimensional force plate system. Sixteen recreationally active college-age males volunteered to participate in the present study. Each participant completed four sets of three non-consecutive CVJs with no arm swing throughout a single day. Besides strong verbal encouragement, participants were constantly instructed to focus on pushing the ground as explosively as possible. Fourteen force-time metrics were selected for CVJ performance analysis purposes: eccentric and concentric peak and mean force and power, eccentric and concentric duration, contraction time, jump height, reactive strength index-modified, and countermovement depth. Repeated measures multivariate analysis of variance was used to examine statistically significant differences across four testing time points (p < 0.05). The results indicate an absence of any meaningful differences across four testing time points in force-time metrics of interest during both eccentric and concentric phases of the CVJ. Moreover, no differences were observed in CVJ outcome metrics such as countermovement depth, suggesting that the movement strategy tends to remain consistent. Overall, these findings reveal that CVJ test repeatability is not affected by the short-term learning effect and that data are stable at least within the scope of this study and within this population.

Influence of interfacial bond between rebar and concrete on the lateral resistance of RC columns under different loading rates

The interfacial bond between rebar and concrete is a critical factor that influences the performance of reinforced concrete (RC) structures because it affects the effective force transfer between concrete and rebar and hence the composite actions. In finite element modelling of RC structures, the bond-slip relation between rebar and concrete is generally neglected due to the increased model complexity by considering debonding behaviours. Limited studies show the debonding performance is loading rate dependent, neglecting it in numerical modelling may lead to inaccurate structural response predictions, but there is no systematic investigation of bonding performance on responses of structures under load of different loading rates. The influences of neglecting debonding in structural response analysis are therefore not properly defined yet. In this study, the finite element model was established and validated by the available impact test data. The lateral resistance and damage modes of the column considering and neglecting bond-slip behaviour between rebar and concrete were examined under various loading rates ranging from 50 kN/s to 1.0 × 106 kN/s. It is found that neglecting bond-slip relation in finite element modelling of RC columns leads to underprediction of the peak force and damage. The assumption of perfect bond has a significant influence on predicting the peak force and damage of column under low loading rates, but its influence reduces with the increase in loading rate, especially when the loading rate exceeds 1.0 × 105 kN/s. The maximum relative difference in peak force between considering and neglecting bond-slip at 50 kN/s is 18.63 %. Parametric studies were conducted to investigate the effects of bonding performance on columns of different width, depth, height, and concrete strength. Based on the numerical results, an analytical formula is developed to quantitatively predict the errors in peak force predictions by neglecting debonding between concrete and rebars of RC columns. The results highlight the importance of considering bond-slip in finite element modelling of RC structures subjected to quasi-static and low-rate dynamic loadings, and demonstrate it is reasonable to neglect debonding in structural response analysis under high-rate dynamic loadings.

Analyzing Cooking Efficiency of Gradoli Purgatory Beans: Effects of Dehulling, Malting, and Monovalent Carbonates.

Legumes, rich in protein, fiber, and micronutrients, are increasingly popular in pulse-based and gluten-free foods despite global consumption stagnating at 21 g/day due to taste, low protein digestibility, anti-nutrients, and long cooking times. Bean resistance to cooking causes textural defects like the hardshell and hard-to-cook phenomena. The pectin-cation-phytate hypothesis explains why soaking beans in sodium salts reduces cooking time by enhancing pectin solubility in water. Gradoli Purgatory beans (GPB), from Italy's Latium region, were malted, reducing phytic acid by 32% and oligosaccharides by 63%. This study evaluated the hardness of cooked GPB seeds in various conditions, including decorticated or malted states, using a modified standard method. Cooking at 98 °C for 7-75 min on an induction hob with a water-to-seed ratio of 4 g/g was tested. Soaking was applied before cooking for conventional seeds only, followed by texture analysis. Conventional GPBs were adequately cooked if their cotyledons disintegrated upon pressing, requiring a force peak of 250 to 220 N and cooking times of 52 to 57 min. Malted, decorticated, and split GPBs cooked similarly to raw decorticated and split ones, with times of 32 and 25 min, respectively. Faster cooking was due to bean coat removal and splitting, not chemical changes. Sodium or potassium carbonate/bicarbonate at 1-2 g/L improved cooking efficiency, with 2 g/L of sodium carbonate reducing cooking time to 13 min. Higher concentrations caused non-uniform cooking. Cooking malted, decorticated, and split GPBs in sodium-carbonated water reduced greenhouse gas emissions from 561 to 368 g CO2e/kg, meeting the demand for eco-friendly and nutritionally enhanced plant protein sources.

Experimental and analytical investigations on single and repetitive impact failure responses of composite sandwich panels with orthogonal woven GFRP facesheets and PVC foam cores

Due to the unique design requirements for high load-bearing capacity of ship structures, composite materials used in the marine industry are gradually being developed with the characteristics of multi-layer sandwich structures with large thickness and cross-section, which are different from thin-walled composite materials widely applied in the aeronautical industry. However, sandwich composite materials used in marine structures have high susceptibility to impact event during in-service applications. The impact induced damage may seriously affect their mechanical performance and structural safety. Therefore, a comprehensive investigation in this paper on the failure mechanisms of composite sandwich panels with orthogonal woven GFRP facesheets and a PVC foam core layer is carried out with a series of single and repetitive low-velocity impact tests. The variations of impact force, dent depth, structural stiffness, failure modes, energy absorption and so on of composite sandwich panels against impact energy levels and impact numbers were explored. The results demonstrate that the delamination damage threshold at the first impact, the sudden drop of peak force and the slow descent process of impact force are the three typical characteristics of impact responses that corresponded to delamination initiation and fibre breakage of the upper panel, and compression damage of the core layer, respectively. The accumulated impact-induced damage has a significant negative effect on load-bearing and energy-absorption capabilities of composite sandwich panels. Moreover, an approximate theoretical analytical method is presented to solve the impact resistance of composite sandwich panels. The analytical results are compared well with experimental results. This research provides a detailed understanding of the damage mechanisms of composite sandwich panels under impact loadings and a guidance for impact resistant design of ship protective structures.

Simulation Of Mechanical Stress On A Solution-Annealed 15-15Ti Steel Using ABAQUS CAE Program

In addressing the problem of Ti steel (15-15Ti) proposed as the main candidate material for the manufacture of coatings and fuel wrappers for liquid LBE-cooled fast reactors at high temperatures related to material degradation, such as liquid metal embrittlement (LME) and liquid metal corrosion (LMC), Gong et al. conducted research related to the creep failure behavior of solution-annealed 15-15Ti steel exposed to LBE at temperatures of 550 and 600oC using a creep test facility. However, in this study, testing the mechanical properties of 15-15Ti steel through tensile testing was not really discussed, even though the mechanical properties of a material are one of the most important things in determining structural design. The mechanical properties obtained from previous research were then simulated using ABAQUS CAE software to determine the stress distribution profile (initial and final) and the mechanical stress-strain performance used to understand more about the 15–15Ti material. From the simulation results, it was found that the peak force received by the specimen for a strain rate of 1.1 x 10-5s-1 was 6.0 kN, while for a strain rate of 5 x 10-5s-1, it was 6.2 kN. This means that the specimen used cannot accept a force greater than the peak force value. A stress-strain difference graph was also obtained in the experimental results, with simulation results showing a decrease in the value of the fracture point. This is because the mesh setting in the simulation is not close to a more detailed value.

A crashworthy device for bridge protection under vessel impact and scour

ABSTRACT For Bridges spanning navigable waterways, scour can amplify damage in the event of a vessel impact. This work investigates the effectiveness of a designed steel crashworthy device in reducing damage to a bridge already affected by scour when subjected to a vessel impact. The findings reveal that the crashworthy device can diminish the peak impact force compared to the bridge system without a steel fender under the same scour conditions. Moreover, the crashworthy device effectively dampens the dynamic response of the bridge during a vessel impact under the same scour conditions. However, with increased scour depth, the impact displacement increases even if a steel fender is used, which may still affect the normal service of the bridge system after collision at a deeper scour depth. Consequently, it is recommended to implement maintenance measures aimed at strengthening and enhancing the horizontal load-carrying capacity of the scoured pile foundation in such cases.

Investigating fabric interlayer effects on tensile loading limits of adhesively bonded single-lap composite joints

This paper investigates enhancing the effectiveness of glass fiber/epoxy composite single-lap bonded joints by using fabric interlayers between the adherends. It was aimed to evaluate the changes in the joint tensile strength depending on the parameters such as different interlayer fabric types (S2-glass fabric and Kevlar fabric), numbers of interlayers (0, 1, 2, and 3), clamping pressure (0, 4, and 6 MPa), and temperature (20, 55, and 80°C) applied to the joint region throughout the curing period. Significant enhancements in peak tensile forces were observed by varying these parameters. The most substantial increase in tensile properties was achieved for the joint with two-layer S2 fabric fabricated at 4 MPa pressure and 55°C curing temperature, denoted as “2L-S2-P4-T55.” Compared to a non-layered joint, those with 1, 2, and 3 S2 fabric interlayers exhibited 35.5%, 39.6%, and 45.2% increases in tensile peak force, respectively. Increasing bonding pressure from 0 MPa to 4 MPa resulted in a 5.2% tensile failure load increase for double S2 fabric interlayered joints cured at 20°C, but a 6.7% decrease at 6 MPa. Using one-layer Kevlar fabric instead of one-layer S2 fabric caused a 15.2% drop in tensile peak force, still 14.9% higher than the non-layered joint.

Taking Photoacoustic Force into Account in Liquid-Phase Peak Force Infrared Microscopy.

The microscopic structure of the material's solid-liquid interface significantly influences its physicochemical properties. Peak force infrared microscopy (PFIR) is a powerful technique for analyzing these interfaces at the nanoscale, revealing crucial structure-activity relationships. PFIR is recognized for its explicit photothermal signal generation mechanism but tends to overlook other photoinduced forces, which can disturb the obtained infrared spectra, thereby reducing spectral signal-to-noise ratio (SNR) and sensitivity. We have developed a multiphysics-coupled theoretical model to assess the magnitudes of various photoinduced forces in PFIR experiments and have found that the magnitude of the photoacoustic force is comparable to that of the photothermal expansion force in a liquid environment. Our calculations show that through simple modulation of the pulse waveform it is possible to effectively suppress the photoacoustic interference, thereby improving the SNR and sensitivity of PFIR. This work aims to alert researchers to the potential for strong photoacoustic interference in liquid-phase PFIR measurements and enhance the performance of PFIR by clarifying the photoinduced forces entangled in the signals.

In-Shoe Sensor Measures of Loading Asymmetry during Gait as a Predictor of Frailty Development in Community-Dwelling Older Adults.

Clinical walk tests may not predict the development of frailty in healthy older adults. With advancements in wearable technology, it may be possible to predict the development of frailty using loading asymmetry parameters during clinical walk tests. This prospective cohort study aimed to test the hypothesis that increased limb loading asymmetry predicts frailty risk in community-living older adults. Sixty-three independently ambulant community-living adults aged ≥ 65 years were recruited, and forty-seven subjects completed the ten-month follow-up after baseline. Loading asymmetry index of net and regional (forefoot, midfoot, and rearfoot) plantar forces were collected using force sensing insoles during a 10 m walk test with their maximum speed. Development of frailty was defined if the participant progressed from baseline at least one grading group of frailty at the follow-up period using the Kihon Checklist. Fourteen subjects developed frailty during the follow-up period. Increased risk of frailty was associated with each 1% increase in loading asymmetry of net impulse (Odds ratio 1.153, 95%CI 1.001 to 1.329). Net impulse asymmetry significantly correlated with asymmetry of peak force in midfoot force. These results indicate the feasibility of measuring plantar forces of gait during clinical walking tests and underscore the potential of using load asymmetry as a tool to augment frailty risk assessment in community-dwelling older adults.