Prevalence and Risk Factors of Primary Dysmenorrhea in Students: A Meta-Analysis.

OBJECTIVES: Primary dysmenorrhea (PD), as the most common complaint among students, is also one of the public problems worldwide. Prevalence and risk factors of PD were variant between studies; as the main population, no meta-analysis for PD has hitherto been conducted in students. METHODS: We searched the published literature in PubMed, Embase, the Cochrane Library, Web of Science, National Knowledge Infrastructure, WANFANG, and VIP database. After screening and assessing the quality of studies, data from eligible studies were extracted for meta-analysis via the R language. RESULTS: A total of 96 studies published from 1991 to 2021 with 78 068 students were included, the mean age of participants was 19.4, and 79.9% were university students. The pooled overall prevalence of PD was 66.1% (95% confidence interval [CI] 63.4-68.9), and 31.1% (CI 28.1-34.3), 25.7% (CI 23.4-28.0), and 8.3% of students (CI 7.4-9.3) reported mild, moderate, and severe PD, respectively. Besides, the prevalence of PD was estimated at 58.8% (CI 54.3-63.7) before 2010, but ascended to 68.5% (CI 65.5-71.6) after 2010 and rose to 71.5% (CI 65.8-76.6) in 2015 to 2021. About risk factors for PD, underweight, skipping breakfast, poor sleep quality, staying up late, lack of physical exercise, exposure to cold and eating cold or spicy foods during menstruation, dietary bias, prefer snacks, family history of dysmenorrhea, irregular menstrual cycle, heavy stress, negative emotion during menstruation, and anxiety were significantly related to PD. CONCLUSIONS: The overall prevalence of PD among students was 66.1% and had a rising tendency in the last 10 years. Our findings helped understand the current prevalence and improve the administration of PD among students.

Element-doped graphitic carbon nitride: confirmation of doped elements and applications.

Doping is widely reported as an efficient strategy to enhance the performance of graphitic carbon nitride (g-CN). In the study of element-doped g-CN, the characterization of doped elements is an indispensable requirement, as well as a huge challenge. In this review, we summarize some useful characterization methods which can confirm the existence and chemical states of doped elements. The advantages and shortcomings of these characterization methods are discussed in detail. Various applications of element-doped g-CN and the function of doped elements are also introduced. Overall, this review article aims to provide helpful information for the research of element-doped g-CN.