Background Social media has been widely used for health-related purposes, especially during the COVID-19 pandemic. Previous reviews have summarized social media uses for a specific health purpose such as health interventions, health campaigns, medical education, and disease outbreak surveillance. The most recent comprehensive review of social media uses for health purposes, however, was conducted in 2013. A systematic review that covers various health purposes is needed to reveal the new usages and research gaps that emerge in recent years. Objective This study aimed to provide a systematic review of social media uses for health purposes that have been identified in previous studies. Methods The researchers searched for peer-reviewed journal articles published between 2006 and 2020 in 12 databases covering medicine, public health, and social science. After coding the articles in terms of publication year, journal area, country, method, social media platform, and social media use for health purposes, the researchers provided a review of social media use for health purposes identified in these articles. Results This study summarized 10 social media uses for various health purposes by health institutions, health researchers and practitioners, and the public. Conclusions Social media can be used for various health purposes. Several new usages have emerged since 2013 including advancing health research and practice, social mobilization, and facilitating offline health-related services and events. Research gaps exist regarding advancing strategic use of social media based on audience segmentation, evaluating the impact of social media in health interventions, understanding the impact of health identity development, and addressing privacy concerns.

Vegetation is the terrestrial ecosystem component most sensitive to climate change. The Qinghai–Tibet Plateau (QTP), characterized by a cold climate and vulnerable ecosystems, has experienced significant warming in previous decades. Identifying the variation in vegetation coverage and elucidating its main driving factors are critical for ecological protection on the QTP. In this study, MOD13A2 Normalized Difference Vegetation Index (NDVI) data in the growing season (May to September) was used to represent QTP vegetation coverage during 2000–2019. The univariate linear regression, partial correlation analysis, residual analysis, and the Hurst exponent were used to detect the vegetation spatiotemporal dynamic, analyze the relationship between the vegetation and main driving factors, and predict the future vegetation dynamic. The growing season NDVI (GNDVI) of the QTP showed an extremely significant rate of increase (0.0011/a) during the study period, and 79.29% of the vegetated areas showed a greening trend. Over the past 20 years, the northeast, mid-east, and western edges of the plateau have been cooling and wetting, while the southwest, mid-west, and southeast have been warming and drying. Different climatic conditions lead to spatial differences in the response of plateau vegetation to climatic factors with generally 1–4 months lag time. The vegetation in the north of the plateau was mainly positively correlated with moisture, and negatively correlated with temperature, while the southern part showed positive correlation with temperature and negative correlation with moisture. Due to the enhancement of cooling and wetting trend in the last decade (2010–2019), especially in the south of the plateau, the greening trend of the plateau vegetation slowed down appreciably and even degraded in some areas. Human activities were mainly concentrated in the eastern part of the plateau—and its positive effect on vegetation was gradually increasing in most areas during study period, especially in the northeastern part. However, vegetation degradation caused by human activities in the southeast of the plateau should not be ignored. The future vegetation dynamic based on the Hurst exponent showed that the plateau faces a higher risk of vegetation degradation, which deserves more attention. This study explored the effect of climatic factors and human activities on vegetation of the QTP, thereby providing some guidance for the study of vegetation dynamic in the alpine areas.

Background Depressive symptoms are the most prevalent mental health concern among older adults (possibly heightened during the COVID-19 pandemic), which raises questions about how such symptoms can be lowered in this population. Existing research shows that offline social connectedness is a protective factor against depression in older adults; however, it is unknown whether web-based social connectedness can have similar effects. Objective This study investigates whether social connectedness on a support website protects older adults against depressive symptoms over the course of a year, above and beyond the protective effect of offline social connectedness. The secondary aim is to determine whether older adults with increased depressive symptoms are more likely to engage in social connectedness on this website. Thus, we examine depressive symptoms as both an outcome and predictor of web-based social connectedness to fully understand the chain of causality among these variables. Finally, we compare web-based social connectedness with offline social connectedness in their ability to lower depressive symptoms among older adults. Methods A total of 197 adults aged 65 years or older were given access to a social support website, where they were able to communicate with each other via a discussion forum for a year. Participants’ social connectedness on the web-based platform, conceptualized as message production and consumption, was measured using behavioral log data as the number of messages participants wrote and read, respectively, during the first 6 months (t 1 ) and the following 6 months (t 2 ) of the study. Participants self-reported their offline social connectedness as the number of people in their support networks, and they reported their depressive symptoms using the Patient Health Questionnaire-8 both at baseline (t 1 ) and at 12-month follow-up (t 2 ). To ascertain the flow of causality between these variables, we employed a cross-lagged panel design, in which all variables were measured at t 1 and t 2 . Results After controlling for the effect of offline support networks at t 1 , web-based message consumption at t 1 decreased older adults’ depressive symptoms at t 2 ( β =−.11; P =.02), but web-based message production at t 1 did not impact t 2 depressive symptoms ( β =.12; P =.34). Web-based message consumption had a larger effect ( β =−.11; P =.02) than offline support networks ( β ...

Bimetallic catalysts play important roles in the selective growth of single-walled carbon nanotubes (SWNTs). Using the simple salts (NH4)6W7O24·6H2O and Co(CH3COO)2·4H2O as precursors, tungsten-cobalt catalysts were prepared. The catalysts were composed of W6Co7 intermetallic compounds and tungsten-dispersed cobalt. With the increase of the W/Co ratio in the precursors, the content of W6Co7 was increased. Because the W6Co7 intermetallic compound can enable the chirality specified growth of SWNTs, the selectivity of the resulting SWNTs is improved at a higher W/Co ratio. At a W/Co ratio of 6 : 4 and under optimized chemical vapor deposition conditions, we realized the direct growth of semiconducting SWNTs with the purity of ∼96%, in which ∼62% are (14, 4) tubes. Using salts as precursors to prepare tungsten-cobalt bimetallic catalysts is flexible and convenient. This offers an efficient pathway for the large-scale preparation of chirality enriched semiconducting SWNTs.