[Investigation on dust pollution and pneumoconiosis incidence in a steel enterprise]

Objective: To analyze the change trend of underground dust concentration, the incidence and survival status of pneumoconiosis patients, and provide reference for improving the working environment of dust-exposed workers and the prevention and treatment of pneumoconiosis patients in the future. Methods: In February 2020, a retrospective investigation was conducted on the dust data of underground mining operations in a steel enterprise in Jiangsu Province from 1991 to 2019, and the case data of patients diagnosed with pneumoconiosis from 1956 to 2019 were collected. The time trends of the number of pneumoconiosis patients and dust concentration, the stage of pneumoconiosis and survival status of patients were analyzed. Results: From 1956 to 2019, a total of 241 patients with pneumoconiosis were diagnosed in the steel enterprise. From 1991 to 2019, the annual average dust concentration in the mine showed a downward trend as a whole. Compared with the transportation platform (14.28%, 1447/10132) , the average dust concentration exceeding rate of the mining platform (43.68%, 8415/19263) was significantly higher (χ(2)=2674.84, P<0.01) . The average age of pneumoconiosis patients was (73.54±10.42) years old, and the average working age of dust exposure was (21.41±8.68) years, of which 85 cases (35.27%) survived and 156 cases (64.73%) died. The main type of pneumoconiosis was silicosis (90.46%, 218/241) , and the main stage of pneumoconiosis was the stage I (96.68%, 233/241) ; The higher the stage of pneumoconiosis, the younger the diagnosis age (P<0.01) . The average survival time of patients was (27.264±1.982) years, and the median survival time was 28 years. The cumulative survival rates of patients with pneumoconiosis in different diagnosis time periods were significantly different (χ(2)=35.57, P<0.01) . Conclusion: The improved dust-proof measures have a significant effect on reducing the concentration of underground dust. We need to focus on the dust control of underground mining platforms and the treatment of patients with stage Ⅲ pneumoconiosis.

[Numerical simulation modeling of middle ear-eustachian tube ventilation based on Chinese digital visual human body]

Objective: To establish a three-dimensional model of middle ear-eustachian tube based on Chinese digital visual human dataset, and the deformation and pressure changes of the middle ear-eustachian tube system after eustachian tube opening are simulated by computer numerical simulation. Methods: The first female Chinese Digital Visual Human data was adopted. The images were imported by Amira image processing software, and the images were segmented by Geomagic software to form a three-dimensional model of middle ear-eustachian tube system, including eustachian tube, tympanum, tympanic membrane, auditory ossicles, and mastoid air cells system. The 3D model was imported into Hypermesh software for meshing and analysis. The structural mechanics calculation was carried out by Abaqus, and gas flow was simulated by Xflow. The tissue deformation and middle ear pressure changes during eustachian tube opening were numerically simulated by fluid-solid coupling algorithm. Several pressure monitoring points including tympanum, mastoid, tympanic isthmus, and external auditory canal were set up in the model, and the pressure changes of each monitoring point were recorded and compared. Results: In this study, a three-dimensional model of middle ear-eustachian tube and a numerical simulation model of middle ear ventilation were established, including eustachian tube, tympanum, mastoid air cells, tympanic membrane, and auditory ossicles. The dynamic changes of the model after ventilation could be divided into five stages according to the pressure. In addition, the pressure changes of tympanum and tympanic isthmus were basically synchronous, and the pressure changes of mastoid air cells system were later than that of tympanum and tympanic isthmus, which verified the pressure buffering effect of mastoid. The extracted pressure curve of the external auditory canal was basically consistent with that of tympanometry in terms of value and trend, which verified the effectiveness of the model. Conclusions: The numerical simulation model of middle ear-eustachian tube ventilation established in this paper can simulate the tissue deformation and middle ear pressure changes after eustachian tube opening, and its accuracy and effectiveness are also verified. This not only lays a foundation for further research, but also provides a new research method for the study of middle ear ventilation.