ABSTRACT
The influence of grain structure and quenching rates on the exfoliation corrosion (EXCO) susceptibility of 7085 alloy was studied using immersion tests, optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM). The results show that as the cooling rate decreases from 1048 °C/min to 129 °C/min; the size of grain boundary precipitates (GBPs); the width of precipitate-free zones (PFZ); and the content of Zn, Mg, and Cu in GBPs rise, leading to an increase in EXCO depth and consequently higher EXCO susceptibility. Meanwhile, there is a linear relationship between the average corrosion depth and the logarithm of the cooling rate. Corrosion cracks initiate at the grain boundaries (GBs) and primarily propagate along the HAGBs. In the bar grain (BG) sample at lower cooling rates, crack propagation along the sub-grain boundaries (SGBs) was observed. Compared to equiaxed grain (EG) samples, the elongated grain samples exhibit larger GBPs, a wider PFZ, and minor compositional differences in the GBPs, resulting in higher EXCO susceptibility.
ABSTRACT
Objective@#To investigate the association of the risk of overweight/obesity in children and adolescents with their early life factors and parental weight.@*Methods@#From June 1 to June 30 of 2022, the stratified randomized cluster sampling method was used to collect information using questionnaires from 5 370 primary and secondary school students in Hohhot City, Inner Mongolia Autonomous Region, and multivariate analysis were performed using multiple Logistic regression model estimation in a generalized linear model for parental BMI and early life factors in children and adolescents.@*Results@#The prevalence of overweight/obesity was 32.2% , and the prevalence of overweight/obesity among male students was 37.8%, which was higher than that of female students 26.1% χ 2= 84.59 , P <0.01). The results of the multirariate Logistic regression anaysis showed that the prevalence of overweight/obesity was higher in only paternal overweight ( OR=1.52, 95%CI =1.30-1.77), only maternal overweight ( OR=1.61, 95%CI = 1.31 -1.97), and parentl overweight ( OR=2.42, 95%CI =2.03-2.87)( P <0.05). The risk of overweight/obesity was higher in children with high birth weight ( OR=1.29, 95%CI =1.08- 1.55 ), children born by caesarean section ( OR=1.32, 95%CI =1.17- 1.48 ), and children whose mothers gained excessive weight during pregnancy ( OR=1.24, 95%CI =1.06-1.46), and the results were statistically significant ( P <0.05).@*Conclusions@#Overweight parents, excessive maternal weight gain during pregnancy, cesarean delivery, and high birth weight are associated with increased risk of overweight/obesity in children and adolescents. Attention should be paid to these aspects in obesity prevention and control.
