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Background: Malocclusion deformity and caries are common oral diseases in adolescents. In order to explore the correlation between malocclusion deformity and caries prevalence in adolescents, this study analyzed the influence of factors such as poor oral habits on caries in adolescents., Methods: In this study, 1,093 adolescents aged 11 to 14 enrolled in 2-3 schools in Zhangjiakou area from September 2020 to June 2021 were selected as the research subjects. The basic data of these adolescents were collected by questionnaires. Malocclusion and caries were examined by on-site inspection. Their bad oral habits were also investigated. After data collection, the chi-square test, logistic regression, the Mann-Whitney U test, and the Kruskal-Wallis H test were used for multivariate analysis., Results: The results showed that the incidence of malocclusion was 72.66% and the caries rate was 68.8% among adolescents aged 11-14 in this area. The 4 bad oral habits of biting, mandibular protrusion, lateral chewing, and mouth breathing were the influencing factors of malocclusion in adolescents. Bad oral habits, malocclusion, and frequent consumption of sugary beverages were independent risk factors for caries in adolescents, and significantly positively correlated with the caries rate., Conclusions: Malocclusion and the four bad oral habits were independent risk factors of caries in adolescents., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/tp-21-531). The authors have no conflicts of interest to declare., (2021 Translational Pediatrics. All rights reserved.)

Boil-off gas (BOG) compressors are among the most critical devices in transportation and receiving systems for liquid natural gas (LNG) because they are used to pump out excess BOG from LNG storage tanks to ensure safety. Because of the ultralow suction temperature, the influence of heat transfer between the cold gas and the compressor parts on the in-cylinder thermodynamic process cannot be ignored. This paper reports the effects of suction temperature on the thermodynamic process and performance of a BOG compressor with consideration of gas pulsation. A computational fluid dynamics (CFD) model with dynamic and sliding meshes was established, in which user-defined functions (UDFs) were used to calculate the real-time valve lift to realize coupling between the thermodynamic process and the gas pulsation, and a performance test rig was constructed to verify the proposed numerical model. The simulated results agreed well with the experimental ones. The results show that as the suction temperature decreased from 30 °C to -150 °C, the first-stage volumetric efficiency decreased to 0.69, and the preheating increased to 45.8 °C. These results should provide academic guidance and an experimental basis for the design and optimization of BOG compressors.