Objective:To study the correction factor of the chamber wall of the reference air kerma rate reference ionization chamber (NIM-Ir-SG-100 type) for 192Ir radioactive source. Methods:The photon spectrum and ionization chamber wall correction factor of the radioactive source housing and irradiator model are calculated by Monte Carlo code. And then the photon energy, wall thickness and ionization chamber diameter, which affect the result of the chamber wall correction factor, are simulated.Results:After calculation, the simulation result of the correction factor of spherical graphite cavity ionization chamber wall was 1.037 7. Controlling a single variable, photon energy (0.3-1.3 MeV), wall thickness (0.2-0.5 cm), inner diameter (0.5 -15 cm), the maximum deviations of wall correction result were 1.62%, 3.30% and 2.86%, respectively.Conclusions:The self-made spherical graphite cavity ionization chamber has good performance, and the corrected kwall value of the chamber wall is within a reasonable range. The completion of the chamber wall correction factor is an important step to measure the reference air kerma rate of the 192Ir radioactive source and establish the measurement benchmark.

Objective:To investigate the correlation between psychological capital, job burnout and coping style of psychiatric nurses.Methods:Using cluster sampling method, 139 psychiatric nurses from a third grade a psychiatric hospital in Nanjing City, Jiangsu Province were selected as the objects of investigation. General information questionnaire, psychological capital questionnaire, job burnout scale and simple coping style questionnaire were used to investigate.Results:The psychological capital of psychiatric nurses was positively correlated with positive coping style ( r=0.801, P<0.01), negatively correlated with job burnout ( r=-0.864, P < 0.01), and negatively correlated with negative coping style ( r=-0.774, P < 0.01). The results of stepwise regression showed that job burnout, monthly income, positive coping style and negative coping style could predict 84.0% of the variance of psychological capital. Conclusion:Psychiatric nurses'psychological capital level is above the middle level. Monthly income and positive coping positively predicted nurses'psychological capital, job burnout and negative coping negatively predicted nurses' psychological capital. Managers can improve the coping style of nurses, rationally distribute the income of nurses, and improve the psychological capital of psychiatric nurses, so as to alleviate the burnout of psychiatric nurses.

Objective    To establish a model of tracheomalacia in beagle dogs. Methods    Six healthy male beagles were selected with a weight of 12-15 kg and age of 12-18 months. The dog was placed in supine position after being anesthetized. Then midline incision was performed on dogs' cervical skin and main trachea was dissected. Six continuous cartilage rings separated from the tracheal wall were removed. Finally, the endotracheal mucosal was examined and the wound was sutured layer by layer. Different degrees of cartilage were removed to simulate different degrees of tracheomalacia. The beagle dogs were classified into two groups (n=3 in each group): a mild tracheomalacia (MTM) group (part of the cartilage near the trachea membrane was retained) and a severe tracheomalacia (STM) group (cartilage was removed as much as possible). Results    The dogs in the MTM group survived for a long time after the operation, showing symptoms of airway stenosis such as wheezing and coughing. The dogs were killed at postoperative week 2, and the pathological examination was performed. In the STM group, severe asphyxia occurred in the experimental animals after tracheal intubation removed, and all dogs died within 1 hour after surgery. Postoperative bronchoscopy revealed that the trachea of the MTM group dogs collapsed in the phase of inhalation, but it could maintain a certain patency. The trachea of the STM group dogs collapsed completely in the phase of inhalation. Postoperative X-ray showed that the diameter of the airway in the MTM group was reduced and trachea did not completely collapse. In the STM group, the trachea collapsed completely at the cartilage removed segment. Pathological examination showed that the cartilage in the MTM group was partially removed and tracheomalacia was obvious in the cartilage removed segment. In the STM group, most of the cartilage was removed with only few cartilages left. Conclusion    The clinical symptoms of tracheomalacia in different degrees can be simulated and repeatable. Animal models can be established by controlling the degree of removal of tracheal cartilage ring in dogs. This method provides a simple, repeatable and standardized large animal model for the treatment and transformation of tracheomalacia.