Objective To establish the dose-effect curves of chromosome aberrations in human peripheral blood lymphocytes induced by different LET rays,including 60Co γ-rays,252Cf neutrons,14MeV neutrons and 12C heavy ions at low doses,respectively,in order to assess radiation-induced damages after occupational and accidental exposure.Methods Heparinized whole blood samples were irradiated with the various radiation devices and doses ranged from 0 to 1 Gy with the interval of 0.25 Gy.Conventional chromosome culture method was applied with adding colchicines at the beginning and chromosome specimens were prepared after 48 h incubation.The Metafer scanning system was used for automatical finder of chromosome metaphases.The mathematic models were fitted according to aberration data obtained.Results At the dose range of 0 - 1 Gy,the math models of dic + r were linear for 60 Co γrays and linear-quadratics for 252 Cf neutrons,14 MeV neutrons and 12 C heavy ions.The models of ace were linear-quadratic for 60Co γ-rays and 12C heavy ion beams,and linear for 252Cf and 14 MeV neutrons.The models of total aberrations were linear-quadratic for all types of radiation.Conclusions High LET rays have higher biological effects in inducing chromosome aberrations yields compared with low LET rays.Moreover,the severity of damage is 252Cf ＞ 14 MeV neutrons ＞ 12C heavy ions ＞ 60Co γ-rays in turn.Therefore,in the range of low doses,the dic + r may be a better target of radiation damage for high LET radiation.

Objective To explore the common safety concerns and effective nursing intervention in patients with intelligence score defect during hospitalization. Methods A total of 63 patients with intelligence score defect in nerve one ward in our hospital was carried out targeted safety management as the observation group,the common medical ward, the nursing assessment was carried out by head of department,the head nurse,the competent doctor, primary nurse, rehabilitation nurse and the health education. For personalized nursing measures, patients went through neurological nursing, safety management and rehabilitation guidance, etc. A total of 62 patients with intelligence score defect in nerve two ward were treated as the control group, nursing care in the traditional way of nursing. The Mini-Mental State Examination (MMSE) were assessed at the time of admission and discharge, and the occurrence of nursing accidents during hospitalization was observed, and the patient′s satisfaction with service was investigated. Results The occurrence of nursing accidents during hospitalization in the observation group was lower than that in the control group:4.76%(3/63) vs.1.77%(11/62), and there was significant difference, χ2=5.29,P < 0.05. MMSE score and patient′s satisfaction at the time of discharge in the observation group were higher than those in the control group:(25.12±1.59) points vs. (21.63±1.87) points,96.82%(61/63) vs. 85.48%(53/62), and there were significant differences, t=11.250,P < 0.01 and χ2=3. 87,P < 0.05. Conclusions Scientific assessment of safety risk and targeted nursing intervention are important means to ensure the safety of patients with intelligent scoring defect. These measures could improve patients quality of life and the improvement of the relationship between nurses and patients.

Objective : To study the relationship between different doses of subchronic sodium fluoride exposure and lung histopathological changes in rats，and to explore the effect and related mechanism of sodium fluoride induced lung tissue injury in rats． Methods: Thirty-two Wistar male rats were randomly divided into control，low，medium and high dose groups，each group included 8 rats，intragastric administration of sodium fluoride toxin solution 0， 12，24，and 48 mg / (kg · d) ．The experiment lasted for 16 weeks．The incidence of dental fluorosis and weight in each group of rats was recorded，the lung coefficient was calculated，the pathological changes of lung tissue was observed by HE staining，enzyme-linked immunosorbent assay(ELISA) was used to detect the content of superoxide dismutase (SOD) and malondialdehyde (MDA) levels in rats serum，apoptosis level of lung cells was assessed by TUNEL staining，and the Caspase-3 protein expression levels in lung tissues were determined by immunohistochemistry. Results: At the end of exposure，the upper and lower incisors of rats in different dose groups showed different degrees of dental fluorosis．The increase in body weight of the rats in the high-dose group was lower than that in the other three groups (P＜0. 05) ．The coefficient of lung organs and the content of MDA in serum of the rats in the high-dose group were higher than those in the control group (P＜0. 05) ．The rats in the low，medium and high dose groups had different degrees of pulmonary interstitial inflammatory infiltration and alveolar morphological changes．Compared with the control group，the lung cell apoptosis rate and Caspase-3 protein expression of the rats in the low ，middle and high groups significantly increased ，and the differences were statistically significant ( P < 0. 05) ． Conclusion Subchronic exposure to sodium fluoride can cause the lung tissue damage in rats ，and the mechanism may be related to the apoptosis induced by oxidative stress.

Objective:To identify tooth number abnormalities on pediatric panoramic radiographs based on deep learning.Methods:Eight hundred panoramic radiographs of children aged 4 to 11 years meeting the inclusion and exclusion criteria were selected and randomly assigned by writing programs in Python (version 3.9) to the training set (480 images), verification set (160 images) and internal test set (160 images), taken in Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology between November 2012 to August 2020. And all panoramic radiographs of children aged 4 to 11 years taken in the First Outpatient Department of Peking University School and Hospital of Stomatology from June 2022 to December 2022 were collected as the external test set (907 images). All of the 1 707 images were obtained by operators to determine the outline and to label the tooth position of each deciduous tooth, permanent tooth, permanent tooth germ and additional tooth. The deep learning model with ResNet-50 as the backbone network was trained on the training set, validated on the verification set, tested on the internal test set and external test set. The images of test sets were divided into two categories according to whether there was abnormality of tooth number, to calculate sensitivity, specificity, positive predictive value and negative predictive value, and then divided into four types of extra teeth and missing permanent teeth both existed, extra teeth existed only, missing permanent teeth existed only, and normal teeth number, to calculate Kappa values. Results:The sensitivity, specificity, positive predictive value and negative predictive value were 98.0%, 98.3%, 99.0% and 96.7% in the internal test set, and 97.1%, 98.4%, 91.9% and 99.5% in the external test set respectively, according to whether there was abnormality of tooth number. While images were divided into four types, the Kappa value obtained in the internal test set was 0.886, and that in the external test set was 0.912. Conclusions:In this study, a deep learning-based model for identifying abnormal tooth number of children was developed, which could identify the position of additional teeth and output the position of missing permanent teeth on the basis of identifying normal deciduous and permanent teeth and permanent tooth germs on panoramic radiographs, so as to assist in diagnosing tooth number abnormalities.