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 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 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 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 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 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 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 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 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.