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 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 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 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 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.

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 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.