An Empirical Study of Economic Cycle, Air Quality, and National Health Since Reform and Opening Up.

Since the reform and opening up of China, the economy has continued to grow, and diverse needs have generated different types and periods of economic activities. This has caused people to have an unhealthy diet, lack of exercise, irregular work and rest, lack of sleep, mental stress, high psychological pressure, long-term bad moods, and other health problems. The proportion of the sub-healthy population continues to increase and health problems are becoming increasingly prominent. Based on this, we examine the internal mechanism of the economic cycle on national health since the reform and opening up of China. For a long time, China has actively responded to the UN's call for environmental protection and proposed that "clear waters and lush mountains are invaluable assets." Therefore, this study combines air quality in the process of environmental governance in China to investigate national health. Data from 22 provinces, five autonomous regions, and four municipalities from 2004 to 2017 are selected as research samples to examine the relationship between economic cycles, air quality, and national health for empirical testing. Studies have shown that the economic cycle is significantly correlated with national health. The better the macroeconomy, the better the health of the human body; that is, the lower the unemployment rate, the lower the mortality rate. After introducing air quality, it was found to have a significant regulating effect on the relationship between the economic cycle and national health. Our conclusions reveal that economic development is closely related to national health. China should attach great significance to the environment and air quality in the process of economic development to achieve sustainable development and create a green economy.

Impact of managerial overconfidence on abnormal audit fee: From the perspective of balance mechanism of shareholders.

Overconfidence, as a psychological feature that is difficult to measure, means that managers are overconfident in their management ability, investment judgment ability and knowledge richness, thus overestimating their ability and making irrational behavior. Based on the sample of Chinese listed firms from 2014 to 2018, we measure managerial overconfidence in terms of age, gender, education, position and salary, and analyzed the relationship between overconfidence, abnormal audit fees, and the balance mechanism of shareholders. The research results show that there is a significant positive correlation between managerial overconfidence and abnormal audit fees, and the balance mechanism of shareholders can significantly inhibit the positive correlation between managerial overconfidence and abnormal audit fees. The research results of this paper are conducive to the supervision department to further improve the relevant supervision measures, improve the audit quality, and provide theoretical support for the more specific requirements of audit fee information disclosure.

Vertebral plate regeneration induced by radiation-sterilized allogeneic bone sheets in sheep / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the effects and mechanism of radiation-sterilized allogeneic bone sheets in inducing vertebral plate regeneration after laminectomy in sheep.</p><p><b>METHODS</b>Twelve adult male sheep (aged 1.5 years and weighing 27 kg on average) provided by China Institute for Radiation Protection underwent L3-4 and L4-5 laminectomy. Then they were randomly divided into two groups: Group A (n=6) and Group B (n=6). The operated sites of L4-5 in Group A and L3-4 in Group B were covered by "H-shaped" freeze-drying and radiation-sterilized allogeneic bone sheets (the experimental segments), while the operated sites of L3-4 in Group A and L4-5 in Group B were uncovered as the self controls (the control segments). The regeneration process of the vertebral plate and the adhesion degree of the dura were observed at 4, 8, 12, 16, 20 and 24 weeks after operation. X-ray and CT scan were performed in both segments of L3-4 and L4-5 at 4 and 24 weeks after operation.</p><p><b>RESULTS</b>In the experimental segments, the bone sheets were located in the anatomical site of vertebral plate, and no lumbar spinal stenosis or compression of the dura was observed. The bone sheets were absorbed gradually and fused well with the regenerated vertebral plate. While in the control segments, the regeneration of vertebral plate was not completed yet, the scar was inserted into the spinal canal, compressing the dura and the spinal cord, and the epidural area almost disappeared. Compared with the control segments, the dura adhesion degree in the experimental regenerated segments was much milder (P less than 0.01), the internal volume of the vertebral canal had no obvious change and the shape of the dura sack remained well without obvious compression.</p><p><b>CONCLUSIONS</b>Freeze-drying and radiation-sterilized allogeneic bone sheets are ideal materials for extradural laminoplasty due to their good biocompatibility, biomechanical characteristics and osteogenic ability. They can effectively reduce formation of post-laminectomy scars, prevent recurrence of post-laminectomy spinal stenosis, and induce regeneration of vertebral plates.</p>

Preparation of porous polylactic-acid/ bone matrix gelatin composite as scaffold materials for bone-tissue engineering / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a novel porous poly lactic-acid(PLA)/bone matrix gelatin (BMG) bioactive composite biomaterial with supercritical carbon dioxide (SC-CO2) extraction and determine the optimal proportion of the ingredients by evaluating the physical and chemical characteristics and cellular compatibility of the composites.</p><p><b>METHODS</b>The PLA/BMG composite biomaterials with various PLA/BMG proportions were prepared with SC-CO2 technique and evaluated by macroscopic observation, porosity and mechanical assessment, and scanning electron micrograph (SEM). The optimal proportion of PLA/BMG was determined in conjunction with the results of cellular compatibility evaluation.</p><p><b>RESULTS</b>BMG proportion in BLA/BMG composite biomaterials prepared with SC-CO2 technique was positively associated with the cellular compatibility and porosity, and inversely with the mechanics of the prepared composite. The results showed BMG content of 30% in PLA/BMG composite was optimal.</p><p><b>CONCLUSION</b>The composite with PLA and BMG proportion of 7:3 possesses good physical and chemical characteristics and cellular compatibility, suggesting its potential as the bone implant biomaterial and bone-tissue engineering scaffold.</p>