Structural and mechanical characterization of the hoof in Mongolian equids.

In this paper, the microstructure and mechanical properties (including nanoindentation, tensile test, and compression test) of Mongolian horse hooves were investigated. Many tubules and Intermediate Filaments (IF) were distributed longitudinally in the hoof of Mongolian horses, which could better help the hoof cushioning. The hardness and modulus of the hoof wall of Mongolian horses varied at different water contents. The hardness and modulus decreased with the increase in water content. The modulus of elasticity of the hoof wall decreased from 16.3% to 25.4%, and the hardness decreased from 17.8% to 29.3% from 10% to 20% water content. At 20-30% water content, the horseshoe wall modulus decreased by 3.5%-4.8%, and the hardness reduced by 4.1%-7.3%. The results of the tensile and compression experiments showed that the compression properties of Mongolian horse hooves were better than their tensile properties; their longitudinal compression energy absorption was better than their transverse compression properties; and Young's modulus and yield strength of the hoof wall increased as the compression rate increased. Finally, comparing the experiments belonging to this paper with hooves from other papers, it was found that the hardness of the tubular region and the intertubular region of Mongolian horse hooves was 17.7% and 39.4% higher than that of the hooves from the current study, respectively. The microstructural features of Mongolian horse-like hooves with superior mechanical properties provide a promising inspiration for the bionic design of lightweight and high-strength composites in engineering.

Biomimetic Study of a Honeycomb Energy Absorption Structure Based on Straw Micro-Porous Structure.

In this paper, sorghum and reed, which possess light stem structures in nature, were selected as biomimetic prototypes. Based on their mechanical stability characteristics-the porous structure at the node feature and the porous feature in the outer skin- biomimetic optimization design, simulation, and experimental research on both the traditional hexagonal structure and a hexagonal honeycomb structure were carried out. According to the two types of straw microcell and chamber structure characteristics, as well as the cellular energy absorption structure for the bionic optimization design, 22 honeycomb structures in 6 categories were considered, including a corrugated cell wall bionic design, a modular cell design, a reinforcement plate structure, and a self-similar structure, as well as a porous cell wall structure and gradient structures of variable wall thickness. Among them, HTPC-3 (a combined honeycomb structure), HSHT (a self-similar honeycomb structure), and HBCT-257 (a radial gradient variable wall thickness honeycomb structure) had the best performance: their energy absorption was 41.06%, 17.84%, and 83.59% higher than that of HHT (the traditional hexagonal honeycomb decoupling unit), respectively. Compared with HHT (a traditional hexagon honeycomb decoupling unit), the specific energy absorption was increased by 39.98%, 17.24%, and 26.61%, respectively. Verification test analysis revealed that the combined honeycomb structure performed the best and that its specific energy absorption was 22.82% higher than that of the traditional hexagonal structure.

Study on driver's active emergency response in dangerous traffic scenes based on driving simulator.

OBJECTIVE: A driver's active emergency response in dangerous traffic scenes consists of two parts, including reaction behavior and physiological state. In dangerous traffic scenes, the driver's active emergency response has an important impact on human collision injury. Clarifying the driver's active emergency response is an important prerequisite for the study of human collision injury under nonstandard posture. Therefore, this study investigates the driver's active emergency response in different inevitable collision scenes using driving simulator. METHODS: A driving simulator with a high-speed camera system and human physiological signal acquisition system was first built. Then, three typical vehicle dangerous collision scenes were developed, including frontal collision, side collision, and rear-end collision. Finally, twenty participants (15 males and 5 females) were recruited for a driving experiment, and their active emergency responses were recorded and analyzed. RESULTS: All subjects would rotate the steering wheel to the left or right in the active emergency state, and the rotation of the hand would also cause the subject's upper body to tilt in the same direction. The maximum angle for male subjects to rotate the steering wheel was 59.98°, while for the female subjects, it was 44.28°. In addition, the maximum grip force between the male subjects and the steering wheel was 280.5 N, compared to 192.5 N for female subjects. Compared to the female participants, the male participants not only have a greater rotation angle and a greater grip force on the steering wheel, but also have greater pressure on the brake pedal, and the foot moves quickly from the accelerator pedal to the brake pedal and presses the brake pedal. CONCLUSIONS: Drivers have different active emergency responses to different vehicle collision scenes. Quantitative statistics of driver's active emergency response will have important guiding significance for the analysis of the impact of human active emergency response on human injury characteristics in subsequent vehicle collision experiments.

Research on Impact Resistance of Aluminum Alloy New Rotating Thin-Walled Structures.

Honeycomb structures are widely used in the field of impact resistance and are constantly being developed and updated. In this paper, the design of three new aluminum alloy rotating thin-walled structures (NRTS) are examined. These structures combine common concave structures and rotating, rigid-body structures. The purpose of this study is to solve the problem of the poor energy absorption capacity of rotating, rigid-body structure due to small deformation and to provide a reference for honeycomb mechanism designs. The Young's modulus, the critical velocity, and the platform stress of the NRTS structure are derived from theoretical analysis. The dynamic response of the NRTS structure at different impact velocities is investigated using finite element simulation software. The results show that the rotating, thin-walled recessed honeycomb (RTRH) increases the plateau stress by 124% and 51% as compared to rotating, thin-walled square tubes (RTSTs) and the re-entrant hexagonal structure (RH), respectively; the rotating, thin-walled quadruple-arc honeycomb structure (RTQH) increases the SEA by 21% and 20% as compared to the RTST and RH, respectively; and the rotating thin-walled double-arc honeycomb structure (RTDH) increases the CEF by 54% and 51% as compared to the RTST and RH, respectively. During the study, it was demonstrated that NTRS also exhibits good energy absorption capacity. Then, the effect of rotation angle on the energy absorption performance was analyzed. The cell and wall thickness of the NTRS structure were optimized according to the gradient theory. It was proved that the gradient optimized structure has better energy absorption performance as compared to the uniform structure.

Relationship between adolescent depressive symptoms with childhood psychological trauma and maternal pregnancy / 中国学校卫生

Objective@#To explore the relationship between adolescent depressive symptoms, childhood psychological trauma and maternal illness during pregnancy, so as to provide scientific busis for the development of adolescent mental health.@*Methods@#A stratified cluster random sampling method was employed to select 2 092 primary and secondary school students in Wuhan City from January to July 2022. Questionnaires were administered to investigate adolescent depressive symptoms, childhood psychological trauma, and maternal illness during pregnancy. The influencing factors of adolescent depression were analyzed.@*Results@#A total of 139 adolescents reported depressive symptoms. The childhood trauma questionnaire (CTQ) score of the depression group was (57.49± 6.85 ), and the score in adolescents without depression group was (46.28±5.96)( t =21.14, P <0.05). Among the maternal diseases during pregnancy, hypertension accounted for 11.51% , diabetes 9.35%, cholestasis 7.19%, hypothyroidism/hyperthyroidism 7.91% , anemia 9.35% and viral hepatitis 3.60% in depression group, 5.79%, 4.71%, 3.64%, 3.07%, 4.30%, 1.18% in the group without depression, respectively, and the differences were statistically significant ( χ 2=7.35, 5.87, 4.42, 9.28, 7.49, 5.75, P <0.05). The proportion of academic stress in the depressed group and non-depressed group were 61.15% and 46.34%, respectively, and was statistically significant ( χ 2=16.04, P <0.05). Multivariate Logistic regression analysis showed that gestational hypertension ( OR=5.04, 95%CI =2.07-12.24), diabetes mellitus ( OR=4.49, 95%CI =1.85-10.91), anemia ( OR=3.68, 95%CI =1.51-8.94), high academic stress ( OR=3.52, 95%CI =1.45-8.56) and the Childhood Trauma Questionnaire ( OR=4.63, 95%CI = 1.91 -11.26) were the risk factors of depression in adolescents ( P <0.05).@*Conclusion@#Adolescent depression may be due to high academic stress, childhood psychological trauma, maternal hypertension, diabetes, thyroid dysfunction and anemia in pregnancy. It is suggested that relevant departments provide appropriate measures to reduce the risk of adolescent depression.

Study on the structural features and geometric parameters affecting the axial mechanical properties of the primary feather rachis.

The seagull feather shaft is an important part of the feather, which provides a good mechanical support for the excellent flight performance of seagull, and has the characteristics of lightweight and high strength. In this paper, the microstructure of the seagull feather rachis was observed firstly. Then, based on the structure of feather rachis, combined with the cortex that plays the main load-bearing role, a model with the characteristics of the cortex was proposed and its finite element model was established. Through analyzing the simulation, the effect of section shape of cortex on mechanical properties of feathers under axial impact was revealed. And the conclusion that the section shape with groove structure and non-equal wall thickness could have different effects on mechanical properties was drawn. Then, parameterized cortical models were studied, including different impact velocities and different cortical heights, to reveal the differences in mechanical properties of cortical models.

[Expression and Clinical Significance of Serum MiR-370 and MiR-203 in Patients with Acute Myeloid Leukemia].

OBJECTIVE: To investigate the expression of microRNA-370 (miR-370) and microRNA-203 (miR-203) in the serum of patients with acute myeloid leukemia(AML), and to analyze its clinical diagnosis and prognostic significance. METHODS: 57 patients with acute myeloid leukemia were enrolled as experimental group, and 21 healthy people were enrolled as control group. The fasting venous blood of the personal in the two groups were collected. The expression of miR-370 and miR-203 of the personal in each groups were detected by real-time fluorescent quantitative PCR. The receiver operating characteristic (ROC) curve was plotted to detected the diagnostic values of serum miR-370, miR-203, and the Kaplan-Meier method was used to estimate the relationship between expression and overall survival of the patients. RESULTS: Compared with healthy controls, serum miR-370 expression was significantly decreased in AML patients(P<0.05), and serum miR-203 expression was also significantly decreased (P<0.05). ROC curve analysis showed that the expression of serum miR-370 and miR-203 could be used to distinguish acute myeloid leukemia and healthy people. The area under the ROC curve of miR-370 was 0.909, and the sensitivity and specificity were 91.46% and 100.00%, respectively. The area under the ROC curve of miR-203 was 0.895, and the sensitivity and specificity were 83.45% and 89.71%, respectively. Serum levels of miR-370 and miR-203 were closely related to overall survival in AML patients. CONCLUSION: The expression of miR-370 and miR-203 is decreased in the serum of patients with AML and may be a new markers for the diagnosis and prognosis of AML.

Mechanical properties and failure deformation mechanisms of yak horn under quasi-static compression and dynamic impact.

In the natural environment, the horns of yak possess remarkable structural mechanical properties to protect the head from injury. In this paper, quasi-static compression and dynamic impact tests were conducted on yak horn in different regions under axial and lateral conditions to evaluate mechanical properties such as elastic modulus, ultimate strength and energy absorption. Meanwhile, the failure deformation mechanism under both low and high strain rates is explored. Moreover, experimental analysis of the correlation among mechanical properties, sampling position, strain rate and loading direction was conducted. Fracture surface of horn was observed with the scanning electron microscope (SEM). Research data demonstrate that specific energy absorption and mechanical properties are correlated with sampling position. Under quasi-static compression and dynamic impact, clear anisotropy behavior of horn was observed, which is evidently reflected in the load-displacement curve. Mechanical properties such as elastic modulus and ultimate strength are different under quasi-static compression and dynamic impact. The failure mode of lamellar buckling and delamination existed in the axial failure process. Brittle fracture and extrusion densification occurred more frequently in the process of lateral failure.

Bionic Design of the Bumper Beam Inspired by the Bending and Energy Absorption Characteristics of Bamboo.

This study conducted quasistatic three-point bending tests to investigate the effect of bamboo node on the energy absorption, bending, and deformation characteristics of bamboo. Results showed that the node had a reinforcing effect on the energy absorption and bending strength of the bamboo culm subjected to bending load. The experimental results demonstrated that nodal samples (NS) significantly outperform internodal samples without node (INS). Under the three-point bending load, the main failure mode of bamboo is the fracture failure. The node also showed split and fracture prevention function obviously. Based on that, a series of bionic bumper beams were designed inspired by the bamboo node. The FEM results indicated that the performance of bionic bumpers was better than that of a normal bumper with regard to bending strength, energy absorption, and being lightweight. In particular, the bionic bumper beam has the best performance with regard to bending, energy absorption, and being lightweight compared with the normal bumper under pole impact. The characteristic of the bionic bumper beam is higher than that of the normal bumper beam by 12.3% for bending strength, 36.9% for EA, and 31.4% for SEA; moreover, there was a mass reduction of 4.9%, which still needs further optimization.

Predicting pathogenic genes for primary myelofibrosis based on a system­network approach.

The aim of the present study was to predict pathogenic genes for primary myelofibrosis (PMF) using a system­network approach by combining protein­protein interaction (PPI) network and gene expression data with known pathogenic genes. PMF gene expression profiles, known pathogenic genes and protein­protein interactions were obtained. Using these data, differentially expressed genes (DEGs) were identified between PMF and normal conditions using significance analysis of microarrays, and seed genes were determined based on the intersection of known pathogenic genes and the PMF gene expression profile. A new network was constructed using the seed genes and their adjacent DEGs within the PPI network. Subsequently, a pathogenic network was extracted from the new network, and contained genes that interacted with at least two seed genes, and the candidate pathogenic genes were predicted based on the cohesion with seed genes. Cluster analysis was performed to mine the pathogenic modules from the pathogenic network, and functional analysis was performed to identify the putative biological processes of the candidate pathogenic genes. Results from the present study identified 845 DEGs between PMF and normal conditions, and 45 seed genes in PMF were screened. Subsequently, a pathogenic network comprising 103 nodes and 265 interactions was constructed, and 4 pathogenic modules (modules A­D) were mined from the pathogenic network. There were nine candidate pathogenic genes contained within Module A and four potential pathogenic genes, including E1A­binding protein p300, RAS­like proto­oncogene A, von Willebrand factor and RAF­1 proto­oncogene, serine/threonine kinase, were identified that may be involved in the same biological process with the seed genes. This study predicted 10 candidate pathogenic genes and several signaling pathways that may be related to the pathogenesis of PMF using a system­network approach. These predictions may shed light on the PMF pathogenesis and may provide guidelines for future experimental verification.

Are electric self-balancing scooters safe in vehicle crash accidents?

With the pressing demand of environmentally friendly personal transportation vehicles, mobility scooters become more and more popular for the short-distance transportation. Similar to pedestrians and bicyclists, scooter riders are vulnerable road users and are expected to receive severe injuries during traffic accidents. In this research, a MADYMO model of vehicle-scooter crash scenarios is numerically set up. The model of the vehicle with the scenario is validated in pedestrian-vehicle accident investigation with previous literatures in terms of throwing distance and HIC15 value. HIC15 values gained at systematic parametric studies. Injury information from various vehicle crashing speeds (i.e. from 10m/s to 24m/s), angles (i.e. from 0 to 360°), scooter's speeds (i.e. from 0m/s to 4m/s), contact positions (i.e. left, middle and right bumper positions) are extracted, analyzed and then compared with those from widely studied pedestrian-vehicle and bicycle-vehicle accidents. Results show that the ESS provides better impact protection for the riders. Riding ESS would not increase the risk higher than walking at the same impact conditions in terms of head injury. The responsible reasons should be the smaller friction coefficient between the wheel-road than the heel-road interactions, different body gestures leading to different contact positions, forces and timing. Results may shed lights upon the future research of mobility scooter safety analysis and also the safety design guidance for the scooters.