Dynamic mechanical response and failure characteristics of coal and rock under saltwater immersion conditions.

The stability of coal and rock masses in water-rich mines is affected by both mine water erosion and dynamic disturbances. Thus, it is necessary to study the dynamic mechanical response and failure characteristics of coal and rock under the combination of saltwater and a high strain rate. To this end, a split Hopkinson pressure bar device was employed to investigate the effects of impact velocity, water content, and immersion liquid on the dynamic mechanical behaviours of coal and rock. The results revealed that the weakening effect of saltwater on the dynamic mechanical properties of coal and rock is much greater than that of distilled water. With increasing moisture content, the dynamic compressive strength of the coal specimens decreases monotonically, while that of the rock shows a trend of first increasing and then decreasing. The failure process and destruction of coal and rock are comprehensively affected by both the external impact load and the physical and mechanical properties of the material. The degree of damage of the coal and rock specimens increases with increasing impact velocity and water content. Moreover, the influence of various factors on the impact fracture mechanism of coal and rock under saltwater immersion conditions was revealed. These findings are highly important for the design and maintenance of underground coal and rock building structures.

'Environmental standard limit concentration' arsenic exposure is associated with anxiety, depression, and autism-like changes in early-life stage zebrafish.

Arsenic is a worldwide environmental pollutant that can impair human health. Previous studies have identified mental disorders induced by arsenic, but the environmental exposure concentrations in the early life stages associated with these disorders are poorly understood. In the present study, early-life stage zebrafish were used to explore the effects on mental disorders under 'environmental standard limit concentrations' arsenic exposures of 5, 10, 50, 150, and 500 µg/L. The results showed that arsenic exposure at these concentrations changed the locomotor behavior in larval zebrafish and was further associated with anxiety, depression, and autism-like behavior in both larval and juvenile zebrafish. Changes were noted at benchmark dose limit (BMDL) concentrations as low as 0.81 µg/L. Transcriptomics showed that immediate early genes (IEGs) fosab, egr1, egr2a, ier2b, egr3, and jund were decreased after arsenic exposure in larval and juvenile zebrafish. Nervous system impairment and anxiety, depression, and autism-like behaviors in early-life stage zebrafish at 'environmental standard limit concentrations' may be attributed to the downregulation of IEGs. These findings in zebrafish provided new experimental support for an arsenic toxicity threshold for mental disorders, and they suggest that low levels of environmental chemicals may be causative developmental factors for mental disorders.

A Bayesian benchmark concentration analysis for urinary fluoride and intelligence in adults in Guizhou, China.

Environmental fluoride exposure has been linked to numerous cases of fluorosis worldwide. Previous studies have indicated that long-term exposure to fluoride can result in intellectual damage among children. However, a comprehensive health risk assessment of fluorosis-induced intellectual damage is still pending. In this research, we utilized the Bayesian Benchmark Dose Analysis System (BBMD) to investigate the dose-response relationship between urinary fluoride (U-F) concentration and Raven scores in adults from Nayong, Guizhou, China. Our research findings indecate a dose-response relationship between the concentration of U-F and intelligence scores in adults. As the benchmark response (BMR) increased, both the benchmark concentration (BMCs) and the lower bound of the credible interval (BMCLs) increased. Specifically, BMCs for the association between U-F and IQ score were determined to be 0.18 mg/L (BMCL1 = 0.08 mg/L), 0.91 mg/L (BMCL5 = 0.40 mg/L), 1.83 mg/L (BMCL10 = 0.83 mg/L) when using BMRs of 1 %, 5 %, and 10 %. These results indicate that U-F can serve as an effective biomarker for monitoring the loss of IQ in population. We propose three interim targets for public policy in preventing interllectual harm from fluoride exposure.

Variations of serum bone resorption biomarkers of children of the coal-burning fluorosis area / 中国学校卫生

Objective@#To investigate the concentration of serum bone resorption markers NTX and TRACP-5b of children aged 8-14 years in a coal-burning fluorosis area and its relationship with age, and to provide population data for the study of pathogenesis of skeletal fluorosis.@*Methods@#Totally 123 children of 8-14 schoolage in the two primary schools in Doujing Township, Shuicheng County, Liupanshui City, Guizhou Province were randomly selected as the exposed group. According to the matching principle, 64 children were randomly selected as a control from a primary school in a nondisease area Huaga Town. The dental fluorosis was investigated, and the concentrations of serum NTX and TRACP-5b were measured.@*Results@#The detection rate of dental fluorosis in the fluorosis area was 94.3% and 0 in the control area. The concentrations of serum NTX in fluorosis area children were 13.04 (10.76, 15.64), 14.82 (12.15, 18.26)nmol/L in the early adolescence and middle-aged period, which lower than the control area 15.73(14.36, 18.61), 16.45(15.45, 22.02)nmol/L( P <0.05); The serum TRACP-5b levels in children with fluorosis were 276.74(237.63, 312.75), 270.14(242.82, 321.97), 305.95(259.78, 339.87)nmol/L in prepubertal, early adolescence and middle youth, lower than the control area 370.88 (304.47, 452.84), 353.30 (262.05, 393.19), 420.22 (376.96, 544.60)nmol/L( Z =-3.03, -2.66, -3.10, P <0.05). Serum NTx and TRACP-5b in fluorosis area were negatively correlated with dental fluorosis in children( r =-0.51, -0.37, P <0.01).@*Conclusion@#Fluorosis can reduce the concentrations of serum bone resorption markers NTX and TRACP-5b in children of different age groups. TRACP-5b may be more sensitive to fluoride exposure than NTX, but the specific mechanism remains to be further studied.