Atherosclerotic plaque rupture is the main cause of many cardiovascular diseases, and biomechanical factors play an important role in the process of plaque rupture. In the study of plaque biomechanics, there are relatively few studies based on fatigue fracture failure theory, and most of them mainly focus on the whole fatigue propagation process from crack initiation to plaque rupture, while there are few studies on the influence of crack on plaque rupture at a certain time in the process of fatigue propagation. In this paper, a two-dimensional plaque model with crack was established. Based on the theory of fracture mechanics and combined with the finite element numerical simulation method, the stress intensity factor (SIF) and related influencing factors at the crack tip in the plaque were studied. The SIF was used to measure the influence of crack on plaque rupture. The results show that the existence of crack can lead to local stress concentration, which increases the risk of plaque rupture. The SIF at the crack tip in the plaque was positively correlated with blood pressure, but negatively correlated with fibrous cap thickness and lipid pool stiffness. The effect of the thickness and angle of lipid pool on the SIF at the crack tip in the plaque was less than 4%, which could be ignored. This study provides a theoretical basis for the risk assessment of plaque rupture with cracks.
Alveolar bone reconstruction simulation is an effective means for quantifying orthodontics, but currently, it is not possible to directly obtain human alveolar bone material models for simulation. This study introduces a prediction method for the equivalent shear modulus of three-dimensional random porous materials, integrating the first-order Ogden hyperelastic model to construct a computed tomography (CT) based porous hyperelastic Ogden model (CT-PHO) for human alveolar bone. Model parameters are derived by combining results from micro-CT, nanoindentation experiments, and uniaxial compression tests. Compared to previous predictive models, the CT-PHO model shows a lower root mean square error (RMSE) under all bone density conditions. Simulation results using the CT-PHO model parameters in uniaxial compression experiments demonstrate more accurate prediction of the mechanical behavior of alveolar bone under compression. Further prediction and validation with different individual human alveolar bone samples yield accurate results, confirming the generality of the CT-PHO model. The study suggests that the CT-PHO model proposed in this paper can estimate the material properties of human alveolar bone and may eventually be used for bone reconstruction simulations to guide clinical treatment.
With the post-disaster psychological crisis has aroused wide attention, psychological first aid which can relieve psychological trauma and prevent post-traumatic disorder has been valued by many countries. However, mainly domestic psychological first aid training is simply theoretical training while its popularizing rate is low, it is urgent to learn from international experience to carry out more effective psychological first aid training. In the context of combination of medicine and industry, the paper majorly embodied virtual simulation’s potential in improving psychological intervention ability, deep learning level and self-efficacy. Furthermore, the paper analyzed and illustrated theoretical basis and function module of constructing psychological first aid training platform in detail, and prospected further improvement, which laid foundations for follow-up studies.
An implantable axial blood pump was designed according to the circulation assist requirement of severe heart failure patients of China. The design point was chosen at 3 L/min flow rate with 100 mm Hg pressure rise when the blood pump can provide flow rates of 2-7 L/min. The blood pump with good hemolytic and anti-thrombogenic property at widely operating range was designed by developing a structure that including the spindly rotor impeller structure and the diffuser with splitter blades and cantilevered main blades. Numerical simulation and particle image velocimetry (PIV) experiment were conducted to analyze the hydraulic, flow fields and hemolytic performance of the blood pump. The results showed that the blood pump could provide flow rates of 2-7 L/min with pressure rise of 60.0-151.3 mm Hg when the blood pump rotating from 7 000 to 11 000 r/min. After adding the splitter blades, the separation flow at the suction surface of the diffuser has been reduced efficiently. The cantilever structure changed the blade gap from shroud to hub that reduced the tangential velocity from 6.2 m/s to 4.3-1.1 m/s in blade gap. Moreover, the maximum scalar shear stress of the blood pump was 897.3 Pa, and the averaged scalar shear stress was 37.7 Pa. The hemolysis index of the blood pump was 0.168% calculated with Heuser’s hemolysis model. The PIV and simulated results showed the overall agreement of flow field distribution in diffuser region. The blood damage caused by higher shear stress would be reduced by adopting the spindle rotor impeller and diffuser with splitter blades and cantilevered main blades. The blood could flow smoothly through the axial blood pump with satisfactory hydraulics performance and without separation flow.
Medical simulation teaching is a bridge course from theoretical knowledge to clinical practice. At present, the medical simulation teaching is facing many problems. The iSIM is a systematic method to optimize medical simulation teaching. It aims to maximize the effect of medical simulation teaching by various teaching methods and assistant technologies. The combination of iSIM and medical simulation teaching can develop the correct clinical thinking, improve the clinical skills and strengthen the communication skills, so as to improve the medical quality in the real clinical environment. Based on experience Center of Experimental Teaching on Clinical Skills of West China Hospital , this paper introduces how to use iSIM to optimize medical simulation teaching.
The rotation center of traditional hip disarticulation prosthesis is often placed in the front and lower part of the socket, which is asymmetric with the rotation center of the healthy hip joint, resulting in poor symmetry between the prosthesis movement and the healthy lower limb movement. Besides, most of the prosthesis are passive joints, which need to rely on the amputee’s compensatory hip lifting movement to realize the prosthesis movement, and the same walking movement needs to consume 2–3 times of energy compared with normal people. This paper presents a dynamic hip disarticulation prosthesis (HDPs) based on remote center of mechanism (RCM). Using the double parallelogram design method, taking the minimum size of the mechanism as the objective, the genetic algorithm was used to optimize the size, and the rotation center of the prosthesis was symmetrical with the rotation center of the healthy lower limb. By analyzing the relationship between the torque and angle of hip joint in the process of human walking, the control system mirrored the motion parameters of the lower on the healthy side, and used the parallel drive system to provide assistance for the prosthesis. Based on the established virtual prototype simulation platform of solid works and Adams, the motion simulation of hip disarticulation prosthesis was carried out and the change curve was obtained. Through quantitative comparison with healthy lower limb and traditional prosthesis, the scientificity of the design scheme was analyzed. The results show that the design can achieve the desired effect, and the design scheme is feasible.
Artificial bone replacement has made an important contribution to safeguard human health and improve the quality of life. The application requirements of rapid prototyping technology based on reverse engineering in individualized artificial bone with individual differences are particularly urgent. This paper reviewed the current research and applications of rapid prototyping and reverse engineering in artificial bone. The research developments and the outlook of bone kinematics and dynamics simulation are also introduced.
A method of ultrasonic simulation based on the FIELD II software platform for carotid artery plaque was proposed according to the analysis for geometrical shape, tissue characteristics and acoustic properties of carotid artery plaques in clinic, and then a simulation system was developed by using the MATLAB graphical user interface (GUI). In the simulation and development, a three-dimensional geometric model of blood vessel with plaques was set up by using the metaball implicit surface technique, and a tissue model was established based on the scatterers with spatial position of gamma random distribution. Comparison of the statistical and geometrical characteristics from simulated ultrasound B-mode images with those based on clinical ones and preset values, the results fully demonstrated the effectiveness of the simulation methods and system.
Pulse waves contain rich physiological and pathological information of the human vascular system. The pulse wave diagnosis systems are very helpful for the clinical diagnosis and treatment of cardiovascular diseases. Accurate pulse waveform is necessary to evaluate the performances of the pulse wave equipment. However, it is difficult to obtain accurate pulse waveform due to several kinds of physiological and pathological conditions for testing and maintaining the pulse wave acquisition devices. A pulse wave generator was designed and implemented in the present study for this application. The blood flow in the vessel was simulated by modeling the cardiovascular system with windkessel model. Pulse waves can be generated based on the vascular systems with four kinds of resistance. Some functional models such as setting up noise types and signal noise ratio (SNR) values were also added in the designed generator. With the need of portability, high speed dynamic response, scalability and low power consumption for the system, field programmable gate array (FPGA) was chosen as hardware platform, and almost all the works, such as developing an algorithm for pulse waveform and interfacing with memory and liquid crystal display (LCD), were implemented under the flow of system on a programmable chip (SOPC) development. When users input in the key parameters through LCD and touch screen, the corresponding pulse wave will be displayed on the LCD and the desired pulse waveform can be accessed from the analog output channel as well. The structure of the designed pulse wave generator is simple and it can provide accurate solutions for studying and teaching pulse waves and the detection of the equipments for acquisition and diagnosis of pulse wave.
Objective To explore the application effect of virtual reality simulation technology (VRST) combined with problem-based learning (PBL) mode in knee arthroscopy teaching in sports medicine department. Methods A total of 76 trainees in sports medicine at Sichuan Provincial Orthopedic Hospital from June 2021 to June 2022 were retrospectively selected. According to the different teaching modes, they were divided into the research group and the control group with 38 trainees in each group. The traditional teaching mode was implemented in the control group, while VRST and PBL mode were implemented in the research group. The objective assessment results and teaching effect feedback of the two groups were compared. Results There was no statistical difference between the two groups in the average theoretical score of the trainees (91.35±1.05 vs. 90.94±1.12, P>0.05). The scores of the three manipulating parts of the research group (9.03±0.24, 9.12±0.31, and 9.24±0.27, respectively) were higher than those of the control group (8.76±0.36, 8.44±0.57, and 8.35±0.51, respectively), moreover, trainees in the research group had higher scores for study enthusiasm, teaching satisfaction, three-dimensional space sense, and virtual reality conversion degree (9.12±0.16, 9.67±0.11, 9.34±0.22, and 9.56±0.18, respectively) than those of the control group (8.89±0.27, 9.16±0.34, 8.67±0.37, and 8.42±0.23, respectively), and the differences were all statistically significant (P<0.05). Conclusion VRST combined with PBL mode could improve trainees’ ability to operate arthroscopy significantly, and stimulate trainees’ subjective learning ability to improve teaching effect.
