Mental health and meaning in life in Chinese military personnel: a cross-lagged analysis.

BACKGROUND: The burgeoning field of research on the dual-factor model of mental health (DFM) has highlighted its significance, yet the applicability of the DFM in military personnel and its longitudinal relationships with different dimensions of meaning in life remains unclear. This study aimed to clarify the applicability of the DFM for military personnel and to investigate longitudinal relationships between the dual factors of mental health (negative factor, positive factor) and the two dimensions of meaning in life (presence of meaning, search for meaning) in military personnel. METHODS: In this study, data were collected in two waves (April and August 2023) from 227 Chinese military personnel. We constructed a dual-factor model with depression as the negative factor and subjective well-being as the positive factor, and we compared it with a single-factor model to determine if DFM could be applied to military personnel. We also constructed a cross-lagged model to investigate longitudinal relationships between depression, subjective well-being, presence of meaning, and search for meaning. RESULTS: According to the findings, military personnel fit better with the DFM than with the single-factor model. Cross-lagged analysis results revealed that both the presence of meaning and the search for meaning negatively predicted depression and positively predicted subjective well-being. CONCLUSIONS: The DFM had good applicability among military personnel. Both the presence of meaning and the search for meaning could improve military mental health, suggesting that both dimensions of meaning in life may be potential targets for improving military mental health.

Exposure risks of lead and other metals to humans: A consideration of specific size fraction and methodology.

Particle size is a critical influencing factor in assessing human exposure risk as fine particles are generally more hazardous than larger coarse particles. However, how particle composition influences human health risk is only poorly understood as different studies have different utilised different definitions and as a consequence there is no consensus. Here, with a new methodology taking insights of each size fraction load (%GSFload), metal bioaccessibility, we classify which specific particle size can reliably estimate the human exposure risk of lead and other metals. We then validate these by correlating the metals in each size fraction with those in human blood, hair, crop grain and different anthropogenic sources. Although increasing health risks are linked to metal concentration these increase as particle size decrease, the adjusted-risk for each size fraction differs when %GSFload is introduced to the risk assessment program. When using a single size fraction (250-50 µm, 50-5 µm, 5-1 µm, and < 1 µm) for comparison, the risk may be either over- or under-estimated. However, by considering bulk and adjusting the risk, it would be possible to obtain results that are closer to the real scenarios, which have been validated through human responses and evidence from crops. Fine particle size fractions (< 5 µm) bearing the mineral crystalline or aggregates (CaCO3, Fe3O4, Fe2O3, CaHPO4, Pb5(PO4)3Cl) alter the accumulation, chemical speciation, and fate of metals in soil/dust/sediment from the different sources. Loaded lead in the size fraction of < 50 µm has a significantly higher positive association with the risk-receptor biomarkers (BLLs, Hair Pb, Corn Pb, and Crop Pb) than other size fractions (bulk and 50-250 µm). Thus, we conclude that the < 50 µm fraction would be likely to be recommended as a reliable fraction to include in a risk assessment program. This methodology acts as a valuable instrument for future research undertakings, highlighting the importance of choosing suitable size fractions and attaining improved accuracy in risk assessment results that can be effectively compared.

Operational method of reliability and content-validity analysis: Taking "trait-symptoms" screening of individuals at high-risk for OCD as an example.

A well-designed self-reported scale is highly applicable to current clinical and research practices. However, the problems with the scale method, such as quantitative analysis of content validity and test-retest reliability analysis of state-like variables are yet to be resolved. The main purpose of this paper is to propose an operational method for solving these problems. Additionally, it aims to enhance understanding of the research paradigm for the scale method (excluding criterion-related validity). This paper used a study that involved screening of high-risk groups for OCD (Obsessive-Compulsive Disorder), conducted 5 rounds of tests, and developed scales, reliability, and validity analysis (using sample sizes of 496, 610, 600, 600 and 990). The operational method we propose is practical, feasible, and can be used to develop and validate a scale.

Potential toxic trace element (PTE) contamination in Baoji urban soil (NW China): spatial distribution, mobility behavior, and health risk.

Rapid urbanization and industrialization may cause increased exposure levels to potential toxic trace elements (PTEs) and associated health risks for population living in cities. The main objectives of this study are to investigate systematically the occurrence, source, fate, and risk of PTE contamination from industrial influence in Baoji urban soil. Seven PTE levels (Pb, Zn, Cu, Cr, V, Sb, and As) were surveyed in 50 composite samples from Baoji urban soil by wavelength dispersive X-ray fluorescence spectrometry. Results reveal that the long-term industrial activities have increased PTEs Pb (409.20 mg/kg mean value), Cu (107.19 mg/kg mean value), Zn (374.47 mg/kg mean value), and Sb (26.00 mg/kg mean value) to enrich in urban soil at the different extents. The same results concur with the significant similarity of spatial distribution patterns of Pb, Zn, Cu, and Sb (slightly similar distribution) interpolated by GIS, implying a considerable Pb, Zn, Cu, and Sb contamination pool in urban soil disturbance from local metallic industrial activities. Whereas As in study area mainly controls parent material leaching and therefore has natural sources. Cr and V with the heterogeneous spatial distributions are possibly inclined to coal combustion sources. Those conclusions are also confirmed by the results of multivariate analysis. The chemical forms of PTEs fractionated by BCR three-stage sequential extraction procedure show that Pb and Cu are highly associated to the reducible phase (62.55 and 36.41%, respectively). However, Zn is highly associated to the oxidizable phase (33.68%), and a significant concentration is associated to acid and water extractable fractionation of 15.93% for Zn and 34.40% for Pb. In contrast, As, Cr, V, and Sb are mainly bound to the residual phase (>65% for all elements) with low concentrations retained to water extractable fractionation. The health risk assessed by a new classification Modified Integrate Risk Assessment Code (MI-RAC) reveals that the Pb poses the extremely high risk for human health than others. The results of PTE leaching in organic acids (artificial chelating agent and LMMOAs) indicate that low pH and more carboxyl groups of organic acid can quickly increase the PTEs release from soil and induce more mobility. By comparison, DTPA and EDTA are the effective extractant for Pb and Sb. The leaching kinetics of most PTEs are best described with the Elovich equation model and which involve the ligand exchange (LE) and ligand-enhanced dissolution (LED) two major process. It is a conclusion that long-term metallic industrial activities would accelerate the PTE accumulations in Baoji urban soil and enhance their mobility in a local scale. The considerable mobility and extremely high risk of Pb in Baoji ecoenvironment should be paid more attentions, and the phytoremediation with organic acid leaching assistant could be used to reduce total metal content of multiPTE contaminants in Baoji soils. The research will give the scientific knowledge for controlling the pollution of PTEs in urban soil and can be used as guidance to control the soil pollution in similar cities worldwide.