To analyze the reverse mechano-electric effect of the layered structure of articular cartilage and its influencing factors.

The cartilage samples were classified according to their physiological thickness (approximately 0.4 mm for the upper layer, 1 mm for the middle layer, and 0.6 mm for the lower layer). Through a non-contact external electric field testing method, how different influencing factors affected the reverse mechano-electric effect of articular cartilage was analyzed.

When the electric field spacing decreased, water content increased, and in vitro time decreased, the displacement of normal layered cartilage in a non-contact electric field increased by 18, 10, 15 μm, respectively. In the case of simulated arthritis defects, as the defect depth and radius increased, the overall deviation deflection of articular cartilage gradually decreased by about 7 μm.

The three-layer cartilage differed in their reverse mechano-electricity effects, showing the greatest deflection in the middle layer at 90% water content, under 7 mm electric field spacing, and after 12 hours ex vivo.

To investigate the effects of patient bone mass differences on the stability of unicondylar knee arthroplasty (UKA) prostheses.

A UKA finite element model was established to quantify the effects of five different bone quality conditions on the proximal tibial von Mises stress, bone-prosthesis fixation interface contact stress, and bone-prosthesis fixation interface micromotion, using the medial knee force and joint motion predicted by the individualized UKA musculoskeletal multibody dynamics model as boundary conditions.

The influences of bone strength on the proximal tibia von Mises stress and bone-prosthesis fixation interface contact stress were not obvious, and the difference in peak values of the proximal tibia von Mises stress between two groups of models with the largest difference in bone strength was not more than 5%, and the difference in peak values of the bone-prosthesis fixation interface contact stress was only 2.37 MPa. However, the influence of bone strength on the bone-prosthesis fixation interface micromotion was significant, and the weaker bones were more prone to cause the bone-prosthesis fixation interface micromotion. However, bone strength had a significant effect on the bone-prosthesis fixation interface micromotion, and weak bone was more likely to cause changes in the bone-prosthesis fixation interface micromotion. Compared to patients with the neutral bone quality, the prosthesis fixation interface micromotion increased by 84.67% at 20% gait cycles for patients with the weakest bone quality.

UKA patients with a weaker bone quality have a higher risk of prosthesis loosening. It is recommended that surgeons should carefully choose their surgical strategy in order to reduce the rate of postoperative revision in UKA.

To investigate stress distributions of the knee joint at 0 and 15^th day after anterior cruciate ligament reconstruction (ACLR) under a compressive force through the axis of the femoral shaft onto the proximal femur.

A three-dimensional (3D) finite element model of the human knee joint incorporating viscoelastic material properties was developed. The one-dimensional (1D) Prony series viscoelastic constitutive model parameters for articular cartilage, menisci, ligaments, and anterior cruciate ligament (ACL) grafts were determined by fitting experimental creep curves. The viscoelastic parameters of ACL grafts at 15^th day after ACLR surgery were extrapolated. Finite element simulations were then performed to analyze the von Mises stress distributions in knee ligaments, ACL grafts, articular cartilage, and menisci under 1.5 kN vertical downward compressive load applied to the femur, with loading durations of 1 second and 600 seconds.

At 15^th day after ACLR surgery, the initial relaxation modulus and equilibrium modulus of human ACL grafts remained elevated compared to native ACL tissues, resulting in a significantly higher stress concentration within the grafts relative to healthy ACL. Despite the compromised mechanical properties of the grafts after ACLR surgery, the vertical downward compressive force applied to the femur under both short-term (1 s) and prolonged (600 s) loading durations, exhibited a minimal biomechanical impact on articular cartilage and meniscal structures.

Following ACLR, vertical compressive loads during weight-bearing rehabilitation exercises such as standing demonstrate minimal impact on articular cartilage and meniscus, while promoting fibrous regeneration of the graft. This renders such exercises a prudent early-stage rehabilitation strategy. Graft preparation requires balanced consideration of elastic and viscous properties, with grafts exhibiting higher relaxation modulus and viscosity coefficient than healthy ACL proving more effective in maintaining early postoperative knee stability.

To study the effect of medial collateral ligament (MCL) release on the squatting motion followling total knee arthroplasty (TKA) and provide reference data for ligament release during knee replacement surgery.

Based on CT and MRI images of a volunteer, a three-dimensional (3D) geometric anatomical model of the natural knee joint including bone tissues and major soft tissues was established. A finite element model of the artificial knee joint was established by simulating TKA surgery. The squatting motion after 30% release of the upper end, lower end, and both ends of the MCL was simulated, and motion characteristic data of the knee joint at flexion/extension angles from 0° to 135° were obtained.

The effects of ligament release at different locations on knee squatting motion varied. After releasing the lower end, the medial translation, posterior translation, superior translation, and adduction of the femur relative to the tibia increased by 13.74%, 3.83%, 9.74%, and 2.37%, respectively, while the external rotation decreased by 36.8%. After releasing the upper end, the medial translation and posterior translation increased by 10.65% and 10%, respectively, while the superior translation, adduction, and external rotation decreased by 4.52%, 33.89%, and 67.1%, respectively. After releasing both ends, the medial translation, posterior translation, and superior translation increased by 14.77%, 9.39%, and 22.56%, respectively, while the adduction and external rotation decreased by 15.62% and 47.3%, respectively.

After MCL released, the medial translation, anterior translation, superior translation, and abduction of the femur relative to the tibia increased, while the external rotation decreased. Releasing the lower end had the least effect on these femoral movements, showing an obvious advantage.

To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.

From patients who underwent hip replacement surgery for femoral neck fractures, a total of 26 femoral head slice specimens were obtained. The central axis of the primary compressive trabeculae was defined as the 0° group, with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center. By rotating the specimens to simulate different reduction angles, the cut femoral head slice specimens were randomly divided into five groups: -10°, -5°, 0°, 5°, and 10°, representing femoral heads with varying reduction qualities. The specimens were subjected to single compression load tests and fatigue load tests. The load was set from 70 N to 1 400 N, at a frequency of 1 Hz, with 10 000 cycles. Axial stiffness, displacement, and the number of collapse cycles were measured, to compare the biomechanical properties of femoral head specimens under different reduction qualities.

There were differences in the axial stiffness, displacement, and number of collapse cycles among the femoral head specimens in different groups. Under 800 N load, the axial stiffness of 0° group was significantly greater than that of ±10° groups (P<0.05). The axial stiffness of 0° group was also greater than that of the ±5° groups, but the differences were not statistically significant (P>0.05). The axial stiffness of ±5° groups was greater than that of ±10° groups (P<0.05). 0° group had a lower displacement than ±5° groups and ±10° groups. However, the differences in displacement between 0° group and ±5° groups were not statistically significant (P>0.05), while the differences between the 0° group and ±10° groups were statistically significant (P<0.05). The differences in displacement between ±5° groups and ±10° groups were also statistically significant (P<0.05). 0° group had a significantly higher number of collapse cycles than ±10° groups (P<0.05). The number of collapse cycles in 0° group was also higher than that in ±5° groups, but the differences were not statistically significant (P>0.05). The number of collapse cycles in ±5° groups was significantly higher than that ±10° groups (P<0.05).

The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head. This study provides a scientific basis for optimizing treatment and postoperative management, aiming to improve clinical outcomes and patients’ quality of life.

To investigate the effects of inclined axial compressive force and flexion moment on the anterior and posterior shear stiffness of the lumbosacral segment.

Six fresh-frozen human cadaveric L5-S1 segments were tested under intact and two progressively impaired structural conditions: intact, a 4-mm bilateral facet joint gap, and anterior discectomy with nucleus pulposus removal plus circumferential release of the inner annular fibers (disc injury). A 300 N axial compressive force was applied either vertically downward or with a 10° or 20° anterior inclination through the disc's shear center. Anterior (0 N to 250 N) and posterior (-50 N to 0 N) shear tests were conducted using a material testing machine. These tests were repeated under a 5 N·m flexion moment. The relative motion between L5 and S1 was measured using a three-dimensional motion capture system.

In the intact state, the inclination of the axial compressive force did not significantly alter anterior or posterior shear stiffness. However, the application of a flexion moment increased anterior shear stiffness by 49.3%. Progressive structural damage resulted in incremental increases in anteroposterior shear translation and corresponding reductions in stiffness. Notably, under combined loading with axial compression and flexion moment, anterior stiffness decreased from 939 N/mm (intact) to 224 N/mm (disc injury), while posterior stiffness decreased from 572 N/mm to 217 N/mm. Within the low-load range, no significant differences in shear stiffness were observed across any structural conditions, regardless of axial force inclination or combined with a flexion moment.

This study supports the clinical view that retro-inclination of the pelvis serves as a compensatory mechanism to enhance segmental shear stability. However, this compensatory capacity gradually diminishes and ultimately fails as spinal degeneration progresses.

To investigate the protective effect of cerebrospinal fluid (CSF) on the spinal cord in patients with scoliosis and evaluate its buffering effect during gravitational traction surgery and in daily life, so as to provide a theoretical guidance for surgical planning and postoperative rehabilitation of scoliosis.

A three-dimensional coupled spinal cord-CSF finite element model was established to simulate the biomechanical responses of the spine under two scenarios: gravitational traction surgery and daily life. Comparative analyses were conducted for conditions with and without CSF, and the buffering effect of CSF was quantitatively assessed.

During simulated gravitational traction surgery, CSF significantly reduced the stress and deformation of the spinal cord, with the stress in spinal cord white and gray matter decreasing by 65%-90% and deformation decreasing by 70%-95%. In the daily life scenario, CSF provided greater protective effects in lateral flexion and anterior-posterior flexion directions, with stress reductions of 60%-85%. However, in torsion, the buffering effect of CSF was relatively weaker, with stress reductions of only 10%-25%.

CSF significantly reduces spinal cord stress and deformation during gravitational traction surgery and in daily life, reducing the risk of injury.

The analgesic effect of manual acupuncture on acute adjuvant arthritis (AA) rats was evaluated using flurbiprofen cataplasm as a positive control, and the role of mast cells in the mechanism of analgesia was explored.

24 SD rats were randomly divided into model group, 10-minute manual acupuncture group, and 30-minute flurbiprofen cataplasm treatment group. AA rat models were established, and treatments were applied at the Zusanli acupoint, while the model group received no treatment. The rats' pain thresholds under mechanical and thermal stimuli were measured before and after the therapy. Acupoint tissue sections were collected and stained, and the mast cell degranulation rate at the acupoint tissue was calculated for each experimental group.

Mechanical and thermal pain thresholds were significantly increased in 10-minute manual acupuncture group compared to those before therapy (P<0.000 1), while there was no significant difference in mechanical and thermal pain pain threshold recovery rates between 10-minute manual acupuncture group and 30-minute flurbiprofen cataplasm treatment group (P>0.05). The mast cell degranulation rate in 10-minute manual acupuncture group and the 30-minute flurbiprofen cataplasm treatment group was significantly higher than that of the model group (P<0.001).

Short-term application of manual acupuncture provides immediate analgesia in AA rats, comparable to flurbiprofen cataplasm treatment. The analgesic effects of manual acupuncture and flurbiprofen cataplasm treatment may be closely related to the degranulation of mast cells in the Zusanli acupoint tissue. This study provides an optimized clinical protocol for treating inflammatory joint diseases while laying the groundwork for future research on treatment mechanisms, long-term outcomes, and combination therapy applicability in varied patient groups.

To study the characteristics of gait behavior in a mouse model of chronic ankle instability and provide a reference for the study of the mechanism of chronic ankle instability as well as drug screening and evaluation.

Thirty C57BL/6J male mice were randomly divided into a control group (n=15) and an injury group (n=15). In the control group, the ankle joint underwent sham operation, and in the injury group, the anterior talofibular ligament and calcaneofibular ligament of the left ankle joint were transected. Gait parameters were analyzed in each group using TreadScan passive gait analysis system.

Compared with the control group, the injury group showed a 28.43% increase (P<0.05) in average standing time and a 23.07% increase (P<0.05) in the percentage of standing time, whereas the average swing time and the percentage of swing time were shortened by 50.63% (P<0.001) and 19.75% (P<0.01), respectively. The average braking time and average stride time in the injury group were also shortened by 18.37% (P<0.01) and 37.86% (P<0.001), respectively. The injury group exhibited a decrease in step length, anterior-posterior step width, and mediolateral step width by 36.96%, 13.66%, and 8.10%, respectively. The total movement speed and instantaneous speed decreased by 8.05% and 11.12%, respectively, while the stride frequency increased by 51.41%. The average footprint area and average maximum standing area decreased by 8.8% and 13.24%, respectively, and foot pressure decreased by only 3%. The plantar pressure distribution in the injury group was uneven, with a more obvious decrease in plantar pressure in the hindfoot, especially a 13.92% decrease in plantar pressure in the right posterior quadrant.

Mice with chronic ankle instability adopt a more conservative walking pattern during the motion, reducing movement volume and amplitude to improve coordination and stability during walking.

To realize real-time monitoring and evaluation of muscle strength, this study designed and validated a wearable muscle strength monitoring system based on muscle perimeter changes.

Six healthy college students who are not sports majors wore the monitoring gear based on the change of muscle perimeter to perform the isokinetic muscle strength test, the real-time data of the change of muscle perimeter during the isokinetic exercise was obtained. After analyzing and processing the curve of muscle perimeter change over time, namely, the peak muscle perimeter change (PP), the peak velocity of muscle perimeter change (PVP) and the accumulation of muscle perimeter change (AP) over time in a single exercise, Pearson correlation analysis was conducted with the peak torque (PT), the peak torque to body weight ratio (PT/BW), the torque at 0.18 s (T0.18) and the endurance ratio (ER) obtained by the isokinetic muscle strength test. The reliability of wearable system for real-time muscle strength monitoring was verified. The muscle perimeter changes were sampled with the arm and leg wearable protectors, and the muscle perimeter monitoring positions corresponded to the largest muscle perimeter changes when the strength of biceps in the upper arm was applied, as well as the largest muscle perimeter changes when the strength of quadriceps above the knee was applied. The isokinetic muscle strength test was performed on elbow and knee joints using the Biodex System 4 pro device.

Dynamic muscle perimeter changes could be used to monitor the muscle strength level of the human body. There was a significant correlation between arm muscle perimeter and elbow muscle strength index (P≤0.01), and the maximum correlation coefficient was 0.91. Leg muscle perimeter was significantly correlated with knee muscle strength (P≤0.01), and the maximum correlation coefficient was 0.99.

The wearable muscle strength monitoring system has a high reliability and can be used for real-time monitoring of the elbow and knee muscle strength during isokinetic exercise.

The biological characteristics and action mechanisms underlying the excellent performance of skeletal muscles were studied through experiments to provide a scientific basis for the development of flexible actuators with performance comparable to that of skeletal muscles.

A frog skeletal muscle sample was contracted by applying electrical stimulation, and then tensile load was applied to it to analyze the relationship between the driving properties (such as contraction length and output force) of skeletal muscle and its structure from three aspects: skeletal muscle dimensions, tendon, and epimysium.

The contraction lengths of these skeletal muscle samples were approximately 28.92% and 20% under unloaded conditions and under 50% of their maximum output force, respectively. When the load on the skeletal muscles did not exceed 20% of their maximum output force, they also exhibited the property of rapid reduction (approximately 1.25 s). The active tendon increased contraction by approximately 19.68% compared with the inactive tendon, and the integrity of the epimysium protected the force transfer efficiency of skeletal muscles.

By simulating the structural and biomechanical properties of skeletal muscles, flexible actuators can achieve better driving performance, thus greatly promoting the development of bionic robots.

To explore the correlation between single-leg standing posture control and ankle plantar flexor muscle stability, so as to provide a new theoretical basis for improving the ability of human posture control.

A total of 20 healthy male college students were randomly selected as the experimental subjects. The iBalance tester and training system was used to test the trajectory data of the center of pressure (COP) of the foot standing on one leg. The CON-TREX MJ multi-joint isokinetic test and training system was used to test the moment amplitude data during the contraction of ankle plantar flexor muscles. Univariate repeated measures variance analysis was used to analyze the standard deviation data of ankle plantar flexor moment amplitude between groups. The Pearson correlation coefficient was used to study the correlation.

The greater the intensity of the muscle stabilization task performed by the ankle plantar flexor muscle, the greater the standard deviation of the moment amplitude. The C90 area was positively correlated with the coefficient of variation (CV) of the 10% maximum voluntary contraction (MVC) moment of ankleplantar flexor muscle (r=0.761, P<0.05) during single-leg standing without interference. The C90 area was positively correlated with the CV (r=0.632, P<0.05) of the 30% MVC moment of ankle plantar flexor muscle during single-leg standing. When the proprioception was interfered during single-leg standing, the C90 area was positively correlated with the CV (r=0.583, P<0.05) of the 20% MVC moment amplitude of ankleplantar flexor muscle.

With the increasing difficulty of muscle strength stabilization performed by the ankle plantar flexor muscles, muscle stability decreases. There is a positive correlation between ankle plantar flexor strength stability and single-leg standing posture control. Compared with the case without interference, under visual and proprioceptive interference, an additional information input is reduced or disturbed, and it is more difficult to maintain body balance, and the ankle plantar flexor muscle needs a higher muscle stability in the force mode to participate in the posture control of the human body during single-leg standing.

To explore the impact of vision impairment (VI) on the gait of hemiplegic patients, assess their walking ability and fall risks, and provide a basis for developing effective rehabilitation strategies.

Thirty hemiplegic patients were enrolled and stratified by the severity of visual acuity impairment into three groups (unimpaired, mildly impaired, and severely impaired). The gait data of patients under uncorrected vision were collected using the Qualisys motion capture system and the Kistler three-dimensional force platform, and the balance ability of patients was assessed simultaneously. Subsequently, the gait and assessment data were statistically analyzed to compare inter-group differences.

Compared with the visually unimpaired group, significant differences in step length, symmetry, and walking speed were observed in hemiplegic patients of the mild visual impairment group and severe visual impairment group. As VI increased, gait abnormalities became more pronounced, with a longer double-limb support phase, a longer swing phase of the affected limb, and a shorter single-limb support phase of the affected limb in the gait cycle. Compared with the visually unimpaired group, significant differences in center of pressure (COP) and COP symmetry were found between the mild visual impairment group and severe visual impairment group, with gait abnormalities intensifying. The Berg balance scale (BBS) scores showed that there was a significant difference between the visually unimpaired group and severe visual impairment group, indicating that the group with visual impairment had poorer balance ability.

VI has a significant negative impact on the gait and walking ability of hemiplegic patients. This study emphasizes the importance of focusing on the impact of VI in the rehabilitation of hemiplegic patients, with regular vision assessments and personalized interventions being conducted, which are of great significance in enhancing patients' walking quality.

To investigate the dynamic balance ability of healthy young adults under different obstacle-crossing strategies, thereby providing a theoretical basis for fall prevention training and public facility design.

Twenty healthy young adults participated in the experiment using F-scan plantar pressure analysis insoles. The subjects were required to cross three obstacles with different combinations of height and width. With their dominant foot serving as the leading foot and the non-dominant foot as the trailing foot, the subjects performed both lateral and forward crossing maneuvers, and their plantar pressure data were collected.

Different crossing strategies significantly affected the adjustment speed of the leading foot's center of pressure in the medial-lateral direction (COP_ML), the area of the 95% confidence circle, ML amplitude, and anterior-posterior (AP) amplitude (P<0.05). These strategies also significantly impacted the trailing foot's COP_ML adjustment speed, the area of the 95% confidence circle, and the range between the maximum and minimum swings (P<0.05). For the leading foot, during lateral and forward crossing, the balance parameter values under different heights and widths were statistically significant (P<0.05), increasing as the height and width increased. For the trailing foot, during forward crossing, the balance parameter values under different heights were statistically significant (P<0.05), increasing with height, while during lateral crossing, the differences in balance parameter values were not statistically significant (P>0.05).

Healthy young adults demonstrate better balance ability with the leading foot during forward obstacle crossing, which aligns with the movement habits of the dominant foot and daily activity patterns. The trailing foot exhibits a more stable plantar pressure distribution during lateral obstacle crossing, likely due to a larger contact area and more even center of gravity distribution.

The sample entropy (SEn) was used to explore standing balance ability and balance control characteristics of the human body under different time scales, in order to reveal the influence of different support conditions and standing tasks on balance control mechanisms.

Twenty-two young adults (11 males, 11 females) performed standing tasks on hard and soft support surfaces using both legs, the left leg, and the right leg. Each task lasted 30 seconds. Center of pressure (COP) data in the anterior-posterior (AP) and medial-lateral (ML) directions were collected, and sample entropy (SEn), entropic half-life (EnHL), and entropy change rate were calculated.

When males stood on their left leg on a soft support surface, significant differences in EnHL were observed in both the AP and ML directions (P<0.05). Significant differences in EnHL in the AP direction were also found for both males and females standing on their right leg on a soft support surface (P<0.05). Under all standing conditions, EnHL values for both males and females exceeded 100 ms. During one-legged standing on a soft support surface, males exhibited significantly higher SEn values in both the AP and ML directions compared to females (P<0.05). During double-legged standing on a hard support surface, males showed an entropy change rate of -0.005, indicating a backward movement trend and fewer posture adjustments. Additionally, during double-legged standing on a soft support surface, the time to reach EnHL in the ML direction was 194 ms for males and 192 ms for females, while females had a shorter EnHL time in the AP direction (168 ms). Changes in the support surface had a minor impact on EnHL.

Reduced proprioception may lead to variations in balance control strategies between genders and limbs. Males tended to adjust forward, whereas females tended to adjust backward. Gender did not significantly affect the stability of balance control during double-leg standing. Males may require more intervention and adjustment to maintain balance under specific disruptive conditions.

To address the limitations of conventional physics-informed neural network (PINN) in handling hemodynamic boundary constraints, an improved hard boundary-constrained PINN (HBC-PINN) framework was proposed to achieve precise prediction of blood flow fields within stenotic arteries.

An idealized stenosed vessel geometry model was established and computational fluid dynamic simulation was performed to obtain a validation dataset. Appropriate boundary dependent trial functions were designed according to the hard constraint method to embed the flow boundary conditions into the network output. Thus, an HBC-PINN model with the hard boundary constraint method was constructed to predict the velocity field and pressure field of stenosed blood flow. Meanwhile, an original PINN model with the soft constraint method was also built for comparison. By evaluating the accuracy of the two models on the validation dataset, the capability of the HBC-PINN model to simulate hemodynamics without using any labeled data for training was verified.

The effectiveness of the HBC-PINN method in predicting hemodynamic parameters in stenosed blood flow tasks was validated. The relative L₂ errors of the flow velocity and pressure predicted by the HBC-PINN in two different stenosis scenarios were both lower than 0.5%, representing an improvement of over 48.8% in accuracy compared to the original PINN model. Additionally, the prediction accuracy of the transverse velocity also increased by more than 35.4%.

Implementing hard constraints on boundary conditions in the PINN modeling process can effectively improve the prediction accuracy of hemodynamic parameters and the efficiency of model solving.

To analyze the effects and differences of two veno-arterial extracorporeal membrane oxygenation (VA-ECMO) cannulation methods and subsequent left ventricular unloading on cardiac function and hemodynamics.

The lumped parameter model (LPM) of VA-ECMO integrated with the cardiovascular system in the MATLAB/Simulink environment was extended to simulate and analyze the changes in ventricular function and blood flow in the heart failure patient model under central VA-ECMO or peripheral VA-ECMO support. The effects of using arterial vasodilators or a left atrial drainage cannula on left ventricular function under central VA-ECMO support at a pump flow rate of 3 L/min were compared.

Under central VA-ECMO or peripheral VA-ECMO support, left ventricular pressure and volume increased, and stroke volume and ventricular work decreased. Both arterial vasodilators and the left atrial drainage cannula could reduce left ventricular pressure and volume. Arterial vasodilators additionally increased stroke volume and improved left ventricular ejection fraction from 11.6% to 19.5%.

Both VA-ECMO cannulation methods provide effective circulatory support in the heart failure patient model, with similar effects on ventricular function. Under central VA-ECMO support, arterial vasodilators can improve left ventricular function more effectively than the left atrial drainage cannula.

To achieve non-invasive and precise prediction of mean arterial pressure (MAP) based on a fully convolutional neural network (FCNN).

A high-precision blood pressure data acquisition system compliant with international metrological standards was used in conjunction with the ‘gold standard’ auscultation method to collect blood pressure and pulse waveform data from patients. True MAP values were derived via Gaussian fitting of pulse waveform data, constructing a traceable dataset. The FCNN was applied to this dataset to develop a novel MAP prediction method. Additionally, the predictive accuracy of the FCNN was compared with linear regression and conventional empirical formulas.

The mean squared errors (MSE) for MAP prediction using the FCNN, linear regression, and empirical formulas were 19.76, 21.40, and 30.97, respectively. The coefficients of determination (R²) were 0.90, 0.89, and 0.84, and the prediction accuracies were 0.90, 0.89, and 0.85, respectively.

By using systolic blood pressure, diastolic blood pressure, age, and arm circumference as input parameters, the FCNN-based MAP prediction method significantly reduces the bias of empirical formulas. This approach not only improves the accuracy of hemodynamic boundary condition acquisition but also contributes to refining the metrological traceability system of non-invasive blood pressure measurement.

To study the hemodynamic characteristics of autologous arteriovenous fistula (AVF) and provide a theoretical basis for reducing its stenosis rate.

Bidirectional fluid-structure interaction (FSI) simulations were conducted on a modified AVF model. Flow field and wall shear stress (WSS) distributions in the internal fistula at different periods and angles in a cardiac cycle were analyzed for retrograde flow (confluence) and anterograde flow (shunt) modes in models with varying anastomosis angles.

Under confluence modes, the WSS<1 Pa area in the 60° anastomosis angle model was the smallest (7.027 mm²), while the 45°, 60°, and 90° models showed no significant differences in eddy current size and intensity. Under shunt modes, the 45° anastomosis angle model had the smallest WSS<1 Pa area (9.079 mm²), but the 60° model exhibited the lowest eddy current intensity and distribution area. In addition, the difference in the WSS<1 Pa area between the 60° and 45° models was only 2.661 mm².

Under both confluence and shunt flow modes, establishing an AVF with 60° anastomosis angle is conducive to reducing the risk of vascular stenosis in arteriovenous fistula.

To investigate the feasibility of parallel capillary bundle arrays for physiomimetic impedance modeling and establish a parametric quantification framework, thereby providing a customizable impedance characterization methodology for diverse in-vitro mock circulation researches.

Based on the parallel flow resistance and Poiseuille equation, a tube resistance element with multiple parallel-aligned capillary glass tubes was designed and fabricated. The resistance values of the capillary-bundle and a ball valve were measured through constant flow experiments analogous to electrical resistance measurement method. Moreover, a simple lumped-parameter mock circulation loop was constructed and the pressure and flow rate for each node of the loop were measured under different input flow waveforms. An 0D-Windkessel model corresponding to the experiment was developed. The impedance and compliance were adjusted to match the simulated and experimental pressure and flow waveforms. The accuracy of the capillary bundle impedance in pulsatile experiments was verified by using the computational resistance values.

The constant-flow impedance calibration experiments revealed that the capillary bundle impedance remained unaffected by flow rate variations over a wide flow range. When the capillary bundle impedance was integrated into the pulsatile circulatory system and the same impedance value obtained from the constant-flow calibration was applied in the computational model, the resulting pressure and flow waveforms showed good agreement with those measured in the pulsatile experiments. However, when the ball valves with nominally identical impedance values were inserted in the pulsatile system, the calculated impedance exhibited a two-fold difference, and significant discrepancies were observed between the simulated and experimental terminal flow waveforms.

The capillary bundle impedance maintains a constant value regardless of flow rate variations. Once the calibrated resistance value is determined through constant flow experiments, it can be directly applied to pulsatile systems. This approach can provide quantitative pulsatile flow conditions for testing various medical devices.

To design and verify an implantable dialysis port that enables the central venous catheter to no longer be placed on the body surface, and to study the effect of the central venous catheter's structural design on its performance.

The feasibility of the dialysis port was verified by flow and pressure experiments. Four representative catheter structures were analyzed by finite element method. The recirculation rate, flow rate-pressure ratio and proportion of indwelling particles were recorded, and performance differences were analyzed. An experimental platform was built to verify the simulation conclusion, and the fluid flow direction of the arteriovenous cavity was quantified by the salinity measurement method.

The dialysis port could reach the flow requirement of 300 mL/min under the 45 kPa pressure. The recirculation rate of the measured central venous catheter was between 10.7% and 23.5%, and the residual value of heparin was between 2.3% and 2.8%. The performance of the catheter with bundle mouth, positive position and side hole structure was better.

The implantable dialysis port can potentially cooperate with central venous catheters to establish a new vascular access approach. The structure of the central venous catheter should adopt the design of bundle mouth, positive position and side hole, which has better recirculation rate and heparin locking performance with low flow rate-pressure ratio. This study provides a theoretical and experimental basis for structural design and clinical selection of the central venous catheter.

To elucidate the regulatory effects of titanium surface modification on the immune function of immature dendritic cells (imDCs), different crystalline nanomorphologies were constructed on titanium surface to investigate the mechanobiological response of imDCs to nanomorphologies with different crystalline phases.

Nanomorphologies with different crystalline phases were constructed on the titanium surface by anodic oxidation and calcination. The changes of the cytoskeleton F-actin, cell adhesion and morphology of imDCs cultured on nanomorphologies with different crystalline phases were observed by fluorescence staining. The relative gene expression of adhesion molecules was detected by quantitative real-time PCR. The migration behaviors of imDCs were observed using real-time live-cell imaging, and the membrane fluidity was detected by fluorescence polarization.

Nanomorphologies with different crystalline phases, namely amorphous phase, anatase and rutile, were obtained on the titanium surface by anodic oxidation and calcination. The cytoskeleton of imDCs on nanomorphologies with different crystalline phases was remodeled. The spreading area of cells on anatase crystalline phase was relatively small, which was (353.3±148.5) μm². The number of adherent cells was the largest, which was 587±132. The expression of adhesion molecules such as CD11a, integrin β2, ICAM1, and VCAM1 were also increased in cells which cultured on anatase crystalline phase. The imDCs cultured on anatase crystalline phase were equipped with strong migration ability. The accumulative migration distance was (383.6±177.7) μm, and the Euclidean migration distance was (51.82±50.13) μm. The membrane fluidity was relatively weak, and the fluorescence polarization was 0.348 5±0.041 8.

imDCs can respond to nanomorphologies with different crystalline phases on the titanium surface and exhibit different biomechanical behaviors. The results might provide a theoretical basis for the design of titanium biomaterials with immunomodulatory functions.

To investigate the therapeutic effects of copper-doped barium titanate (BaCuTiO₄) piezoelectric materials combined with low-intensity pulsed ultrasound (LIPUS) to activate their piezoelectric-catalytic synergistic effect for treating implant-associated infections.

BaCuTiO₄ coatings were synthesized on the surface of Ti-6Al-4V substrates using a hydrothermal method, and their surface morphology was characterized by scanning electron microscopy. The piezoelectric characteristics of the coatings were analyzed using a piezoresponse force microscope. An in vitro biofilm model of methicillin-resistant staphylococcus aureus (MRSA) was used, with barium titanate (BaTiO₃) coatings serving as the control group. Under LIPUS intervention (1.0 W/cm², 1 MHz, 10 min), the bacterial viability was assessed using colony counting to evaluate the antibacterial performance of the BaCuTiO₄ coatings. Confocal microscopy was used to observe biofilm viability in different groups, assessing the biofilm removal capability of the coatings. Reactive oxygen species (ROS) generation in each group was detected using Rhodamine b as a probe to evaluate the catalytic efficiency of the coatings in generating ROS.

Copper doping significantly reduced the piezoelectric coefficient of the coating (from 17.7 pm/V to 7.8 pm/V), bringing its piezoelectric performance closer to the requirements of natural bone tissues. Under LIPUS activation, the BaCuTiO₄ coatings increased the generation efficiency of reactive oxygen species by 67.5% and effectively disrupted and removed biofilms formed by MRSA, achieving an antibacterial rate of 90.5%.

The BaCuTiO₄ coatings achieve efficient antibacterial and biofilmclearing functions through a piezoelectric-catalytic synergistic mechanism. Their piezoelectric properties are well-matched with natural bone tissues, promoting implant osseointegration.

To analyze the fluid resistance characteristics of different drafting formations in marathon swimming using computational fluid dynamics (CFD) method, and provide theoretical guidance for selecting optimal drafting strategies in competitions and training.

Multi-swimmer models were established via three-dimensional body scanning technology, and various formation models (I-, A-, V-, L-, H-type) were created by adjusting lateral and longitudinal distances between swimmers. The ANSYS Discovery Live software was used to simulate the overall resistance of different models and the resistance of individual swimmers within formations.

The I3-type formation exhibited an overall drag reduction effect, reducing total resistance by 55.21%, whereas other formations increased overall resistance. The V-type formation showed the most significant resistance increase (31.88%). During drafting, the lowest resistance position was the rear position in the I3-type formation, while the highest resistance position was the middle position in the L-type formation. When leading, the fluid resistance of the leading swimmer in the A-type formation was significantly greater than that of an individual swimmer (P<0.05).

Longitudinal drafting formations demonstrated superior drag reduction effects, with the rear position in a three-person longitudinal arrangement showing the optimal drag reduction. Considering both tactical considerations and drag reduction effects, swimmers are advised to avoid the middle position in lateral formations.

By applying the long short-term memory (LSTM) neural network model and using lower body landmark coordinates obtained from a markerless motion capture system as inputs, to estimate ground reaction force (GRF) curves during running.

The video images and GRF data of 59 amateur runners during running were collected by the markerless motion capture system and three-dimensional (3D) force plates. The LSTM model was established, and the 3D coordinates of 11 lower body landmarks, obtained via the Theia3D markerless system, were used as inputs to estimate the 3D GRF curves during the stance of running. The estimation performance was evaluated using correlation coefficients r, root mean square error (RMSE), and normalized root mean square error (nRMSE) by comparing LSTM model estimation and force plate measurement. Statistical parametric mapping was used to analyze differences in GRF curves estimated by the LSTM model and measured by the force plate, while paired t-tests were used to assess differences in GRF characteristics between model estimation and actual measurement.

A strong correlation (r>0.85, P<0.001) and lower error (RMSE<0.3 body weight, nRMSE<15%) was found between the LSTM model estimation and actual measurements. No significant difference was found in GRF curve intervals between LSTM model estimation and actual measurements. There was no significant difference in GRF characteristics between LSTM model estimation and actual measurements (P>0.05).

Based on the LSTM model, the 3D GRF curves can be effectively estimated by lower body landmark coordinates obtained from the makerless motion capture system, thereby acquiring the highly accurate GRF characteristics. The LSTM model developed in this study can be used to monitor injury risks during running in outdoor environments.

To study how lipid bilayer fluidity modulates the interaction between β1 integrin and CD40L, as well as the formation of CD40L-mediated tumor cell contact interfaces.

Supported lipid bilayers (SLB) with different fluidities were prepared through adjusting the 1, 2-dioleoyl-sn-glycero-3-[N-(5-amino-1-carboxypentyl) iminodiacetic acid] succinyl nickel salt (DGS-NTA) content. The functionalization of lipid bilayers was achieved by anchoring fluorescently labeled CD40L molecules onto the membrane surface. The contact interface formation of PC9 cells on the functionalized lipid bilayers was observed through confocal fluorescence imaging and fluorescence recovery after photobleaching (FRAP) experiments, and data of two dimensional (2D) reaction kinetics of β1 integrin and CD40L were extracted from Zhu-Golan plots.

The diffusion coefficient of molecules in lipid bilayer was negatively correlated with DGS-NTA content. High fluidity of lipid bilayer promoted CD40L accumulation at cell contact interface and expanded the cell contact area. The 2D dissociation constants (2D K_d) of β1 integrin-CD40L complexes were approximately 13, 31 and 65 molecules/μm² for the three lipid bilayers with high, moderate and low fluidities, respectively.

High fluidity of lipid bilayers significantly facilitates diffusion and aggregation of CD40L to the cell contact interface, thus enhancing β1 integrin-CD40L interaction and the stability of cell contact interfaces.

To investigate the risk of thoracoabdominal injuries in six-year-old child occupants in a reclined seating posture during frontal collisions, and provide a reference for developing child restraint systems (CRS).

Three validated biomechanical models of six-year-old child occupants in different seating postures with detailed anatomical structures were used. The acceleration curve from a sport utility vehicle crash test was applied to analyze the effects of seating posture on thoracic motion trajectory, chest acceleration, thoracoabdominal compression, viscous criterion (VC) of the chest and abdomen, internal organ strain, and spinal stress.

Thoracic motion trajectories varied in the Z-direction under three seating postures. As the upper torso angle increased, thoracoabdominal kinematic injury parameters showed an upward trend. The thoracic and abdominal VC under 120° and 135° posture increased by 67% and 113%, 10.7% and 25% compared with that under 105° standard sitting posture. The risk of thoracic internal organ injury was inversely related to the seating angle, while the risk of abdominal internal organ injury was positively related to the seating angle. The primary spinal injury mechanism was compression-flexion.

CRS protection evaluation should comprehensively consider thoracoabdominal kinematic parameters, internal organ biomechanics, and spinal injury risk. These findings have important implications for CRS development in intelligent driving systems and occupant protection strategy formulation.

To propose a transfer learning-based method for breath sound feature recognition and autonomous determination of sputum suction timing.

An electronic stethoscope was used to collect breath sounds from the main airways of clinically ventilated patients before and after sputum suction, with pre-suction breath sounds labeled as requiring suction. The collected data underwent high-pass filtering and wavelet soft-threshold denoising, followed by the extraction of log-Mel spectrograms. A VGGish model pretrained on the Audio Set dataset was then employed to extract feature vectors from these spectrograms, which were subsequently classified using a support vector machine to determine whether suction was required.

The precision, recall and F₁ score for recognition of breath sounds requiring sputum suction were 86.73%, 93.06% and 89.78%, respectively.

The proposed breath sound recognition method based on transfer learning effectively determines the timing of sputum suction and shows a significant clinical potential.

To investigate the flow field characteristics of peritoneal fluid flowing in the cavity between the liver and the inner wall of the diaphragm peritoneum in patients with ovarian cancer and the effects on deformation of the liver and diaphragm peritoneum.

A bidirectional fluid-structure interaction (FSI) analysis was conducted using COMSOL to investigate the interaction between the peritoneal fluid and the liver and diaphragm peritoneum under varying inlet velocities and viscosity functions.

The accuracy of the simulation was validated by comparing the simulation results with the contour lines of the CT scans, and the displacement error between the two was smaller than 5%. When the inlet velocity of the abdominal fluid increased from 0.1 m/s to 0.15 m/s, convex deformation of the diaphragm peritoneum increased by 193.3 μm, and concave deformation decreased by 304.1 μm. Meanwhile, the increase of the inlet velocity made the viscosity near the wall of deformed area increased, which improved the probability of the metastatic implantation of the cancer cells. The higher the viscosity in the main body region of the viscosity function, the larger convex deformation of the diaphragm peritoneum; the larger the linear fitting value in the tail, the smaller the concave deformation. The viscosity of the concave deformation area near the outlet of the right lobe was much larger than that of other areas, and cancer cells were more likely to metastasise in this area.

This study elucidates the relationship between peritoneal fluid flow and solid deformation, predicting the regions prone to cancer cell metastasis and implantation under various conditions. The findings provide a theoretical foundation for studying the motion of cancer cells within the flow field.