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 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.

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.

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 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.