Prediction model for atmospheric corrosion of 7005-T4 aluminum alloy in industrial and marine environments

Accelerated corrosion tests of the 7005-T4 aluminum alloy were conducted to determine a suitable service life prediction method by using alternating wet–dry cycles in three kinds of solutions. The morphology and composition analysis of the corrosion product revealed that slight corrosion occurred on the surfaces of the samples immersed in a 0.25 wt% Na_2S_2O_8 solution. However, pitting corrosion occurred on the surfaces of the samples immersed in a 3.5 wt% NaCl solution, whereas exfoliation corrosion occurred on the surfaces of the samples immersed in a mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions. A power exponent relationship was observed between the mass loss and exposure time of the 7005-T4 aluminum alloy immersed in the three kinds of solutions. In the mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions, the mass loss of the aluminum alloy yielded the maximum value. Based on the calculation of the correlation coefficients, the alternating wet–dry procedure in a 3.5 wt% NaCl solution could be used to predict the corrosion behavior of 7005-T4 aluminum alloy exposed in the atmosphere of Qingdao, China. The prediction model is as follows: T = 104.28×t^(0.91), where T is the equivalent time and t is the exposure time.

Pretreatment HIV drug resistance in adults initiating antiretroviral therapy in China,2017

Background:After the scale-up of antiretroviral therapy(ART)for HIV infected people,increasing numbers of patients have pretreatment drug resistance(PDR).In this study,the prevalence of PDR was evaluated in adults initiating antiretroviral therapy in China.Methods:Blood samples were obtained from 1943 patients who initiated antiretroviral therapy(ART)in 2017 from 13 provinces or cities in China.Pol sequences were used to analyze drug resistance and construct transmission networks.Logistic regression model was used to estimate the potential factors associated with PDR.Results:In total,1711 eligible patients(76.0%male;87.8%aged≥25 years)were included,of which 117(6.8%)had PDR.The highest rates of PDR were 12.2%in Liangshan Prefecture of Sichuan and 9.3 and 8.9%in Dehong and Lincang Prefecture of Yunnan.A multivariate logistic regression analysis revealed that PDR was significantly higher among intravenous drug users(adjusted Odds Ratio(aOR)=2.64,95%CI:1.57–4.44)and individuals from Liangshan,Dehong,and Lincang(aOR=2.04,95%CI:1.26–3.30).In total,754 sequences were used to generate 164 transmission networks.Five transmission networks had two or three sequences containing the same mutations,two networks contained subjects from Liangshan,and one network contained subjects from Dehong.Conclusions:Overall,the PDR prevalence was moderate,with a particularly high prevalence in areas with severe HIV epidemics.These results indicate the importance of continuous PDR monitoring in patients initiating antiretroviral therapy.