The relationship between search for meaning in life and symptoms of depression and anxiety: Key roles of the presence of meaning in life and life events among Chinese adolescents.

BACKGROUND: Meaning in life has been associated with greater mental health. However, previous findings are inconsistent regarding how the search for meaning in life (SML) is related to mental health issues such as symptoms of depression and anxiety. This study proposed and tested a new model to explain how the relationship between SML and symptoms of depression as well as anxiety can be moderated by life events and mediated by the presence of meaning in life (PML). METHODS: Middle and high school students (N = 1,705, 836 girls and 869 boys; Mage = 14.37, SD = 1.70) were administrated the Meaning in Life Questionnaire, Adolescent Self-Rating Life Events Checklist, Center for Epidemiologic Studies Depression Scale, and the State Anxiety Inventory. RESULTS: Results showed that the relationship between SML and symptoms of depression (or anxiety) depended on the impact of the life events experienced by the individual. In general, SML served as a beneficial or unrelated factor for those experiencing low impactful life events, but as a harmful factor for those experiencing high impactful life events. For those experiencing middle impactful life events, SML had a positive direct effect, but a negative indirect effect (through PML) on symptoms of depression (or anxiety). LIMITATIONS: Data are cross-sectional, and the present study examined only middle school students, which may limit generalizability. CONCLUSIONS: The findings indicate a complex relationship between SML and mental health. Symptoms of depression, anxiety, and other related problems may be diminished by applying training programs and policies aimed at increasing PML and reducing negative life events.

Slash-and-char: An ancient agricultural technique holds new promise for management of soils contaminated by Cd, Pb and Zn.

Heavy metal contamination of agricultural soils is of worldwide concern. Unfortunately, there are currently no efficient and sustainable approaches for addressing this concern. In this study, we conducted a field experiment in which an agricultural soil highly contaminated by cadmium (Cd), lead (Pb) and zinc (Zn) was treated on-site by an ancient agricultural technique, 'slash-and-char', that was able to convert the biomass feedstock (rice straw) into biochar in only one day. We found evidence that in comparison to the untreated soil, the treated soil was associated with decreased bioavailability of the heavy metals and increased vegetable yields. Most importantly, the treatment was also coupled with dramatic reductions in concentrations of the heavy metals in vegetables, which made it possible to produce safe crops in this highly contaminated soil. Collectively, our results support the idea that slash-and-char offers new promise for management of soils contaminated by Cd, Pb and Zn.

Ecological effects of combined pollution associated with e-waste recycling on the composition and diversity of soil microbial communities.

The crude processing of electronic waste (e-waste) has led to serious contamination in soils. While microorganisms may play a key role in remediation of the contaminated soils, the ecological effects of combined pollution (heavy metals, polychlorinated biphenyls, and polybrominated diphenyl ethers) on the composition and diversity of microbial communities remain unknown. In this study, a suite of e-waste contaminated soils were collected from Guiyu, China, and the indigenous microbial assemblages were profiled by 16S rRNA high-throughput sequencing and clone library analysis. Our data revealed significant differences in microbial taxonomic composition between the contaminated and the reference soils, with Proteobacteria, Acidobacteria, Bacteroidetes, and Firmicutes dominating the e-waste-affected communities. Genera previously identified as organic pollutants-degrading bacteria, such as Acinetobacter, Pseudomonas, and Alcanivorax, were frequently detected. Canonical correspondence analysis revealed that approximately 70% of the observed variation in microbial assemblages in the contaminated soils was explained by eight environmental variables (including soil physiochemical parameters and organic pollutants) together, among which moisture content, decabromodiphenyl ether (BDE-209), and copper were the major factors. These results provide the first detailed phylogenetic look at the microbial communities in e-waste contaminated soils, demonstrating that the complex combined pollution resulting from improper e-waste recycling may significantly alter soil microbiota.

Interaction and its solution in individual matching case-control study.

OBJECTIVE: To indicate the deficiency of the classical method for analyzing data on individual matching case-control study in consideration of the interaction between the study factor (exposure) and the matching factor, and to find out a proper method for handling this deficiency. METHOD: First, experimental data with 50 pairs of cases and controls were used for strata analysis according to the values of a matching factor to illustrate the possible interaction between a risk factor (exposure) and the matching factor. Second, a detailed procedure was proposed for analyzing such data. RESULTS: Interaction between the study factor and matching factor was demonstrated by using strata analysis and unconditional logistic regression analysis. Therefore the results from the classical analysis for such data might be incorrect. CONCLUSION: Data from individual matching case-control study design should be dealt with strata analysis or multivariate analysis to explore and evaluate the possible interaction between the study factor and matching factor. The conclusion would be valid only after such analysis is conducted.