Cognitive impairment associated with individual and joint exposure to PM_(2.5)constituents in a Chinese national cohort

Nationwide longitudinal evidence linking cognitive decline with exposure to fine particulate matter(PM_(2.5))constituents remains scarce in China.By constructing a dynamic cohort based on the China Health and Retirement Longitudinal Study,we aimed to assess individual and joint associations of PM_(2.5)constituents with cognitive function among middle-aged and older adults in China.Linear mixed-effects models incorporated with quantile-based g-computation were applied to investigate individual and joint associations of long-term exposures to PM_(2.5)constituents with cognitive function.Among 13,507 respondents,we evaluated 38,950 follow-up records of cognitive function tests.Declines in global cognitive score associated with an interquartile range(IQR)increase in exposure were−1.477(95%CI:−1.722,−1.232)for nitrate,followed by−1.331(−1.529,−1.133)for ammonium,−1.033(−1.184,−0.883)for sulfate,−0.988(−1.144,−0.832)for organic matter and−0.822(−0.946,−0.699)for black carbon.An IQR-equivalent increase in joint exposure to these PM_(2.5)constituents was associated with a decline of−1.353(−1.659,−1.048)in global cognitive score.Female,younger,and well-educated individuals were at greater vulnerability to cognitive impairment related to individual and joint exposure to PM_(2.5)constituents.This study suggested that later-life exposures to PM_(2.5)constituents were associated with cognitive decline in middle-aged and older adults in China.

Seepage Mitigation in Hydropower Dams by Optimization in Roller Compacted Concrete Interlayer (Monoliths) Joint Bonding Technology

Roller Compacted Concrete (RCC) has gained favorable recognition in hydropower and water resource dam construction. With optimization in construction technology and materials used for RCC Dams, cost is no longer a major disadvantage as compared to environmental impact, that is, wildlife habitat disruption. In as much as it has become optimal for investment in hydropower dam construction, the scourge for dam failure is still eminent, which is as a result of excessive seepage compromising the integrity of the mechanical properties of the dam. The aim of the paper is to highlight successful application methods in joint bonding to avoid excessive seepage and reduce the autogenous healing to a few years of operation. In view of optimization, this paper presents a comprehensive study on the influences of interlayer joints bonding quality from RCC mix performances and how it consolidates the RCC layers to withstand the shear strength along the interface, especially on the high dams. The case study is the RCC dam at the 750 MW Kafue Gorge Lower Hydropower Station. The scope of the study reviews the joint type judged by Modified Maturity Factor (MMF) with joint surface long time exposed in regions with dry and high temperature, technical measures of layer bonding quality control under condition of long time joint surface exposure, effects of joints shear strength and impermeability of the RCC layers when under the conditions of plastic and elasticity. The subtle observations made during the dam construction phases were with respect to the optimal use of materials in relation to RCC mix designs and the basis for equipment calibration for monitoring important data that can be referenced during analysis of shear forces acting on the RCC dam over time.