Microstructure and Mechanical Properties of MIG Welds between 6252 Armor Steel and Q550D HSLA Steel.

The microstructure and mechanical properties of the welded joints of 6252 armor steel and Q550D high-strength low-alloy (HSLA) steel welded by MIG welding were studied. ER70S-G and ER140S-G were used as fillers to obtain welded joints with good formation and no faults. The joint microstructure (OM) analysis showed that a large Widmanstätten structure was observed at the fusion line on the Q550D side, and the apparent grain sizes changed on the 6252 side. Cylindrical ferrite growth along the bainite grain boundary was observed in the ER70S-G filler weld zone, while the ER140S-G filler weld zone was occupied by lower bainite structures. The XRD phase analysis showed that more Fe-Ni-Cr compounds and less ferrite were formed in the ER140S-G filler weld. The hardness test showed that the hardness of the HAZ on the 6252 side was significantly higher than that of the BM and the WZ, and the welded joint obtained by the ER140S-G filler had a higher hardness. The tensile strength test showed that WZ (>772 MPa) had a higher strength than Q550D BM, and the tensile fracture (SEM) was primarily a ductile fracture. The impact test results showed that the welded joint had better impact resistance at room temperature, but the impact absorption energy of the weld and the heat-affected zone was strongly affected by changes in temperature, and brittle fracture occurred easily at low temperatures.

Estimated individual inhaled dose of fine particles and indicators of lung function: A pilot study among Chinese young adults.

Fine particle (PM2.5)-related lung damage has been reported in most studies regarding environmental or personal PM2.5 concentrations. To assess effects of personal PM2.5 exposures on lung function, we recruited 20 postgraduate students and estimated the individual doses of inhaled PM2.5 based on their microenvironmetal PM2.5 concentrations, time-activity patterns and refereed inhalation rates. During the period of seven consecutive days in each of the four seasons, we repeatedly measured the daily lung function parameters and airway inflammation makers such as fractional exhaled nitric oxide (FeNO) as well as systemic inflammation markers including interleukin-1ß on the final day. The high individual dose (median (IQR)) of inhaled PM2.5 was 957 (948) µg/day. We observed a maximum FeNO increase (9.1% (95%CI: 2.2-15.5)) at lag 0 day, a maximum decrease of maximum voluntary ventilation (11.8% (95% CI: 4.6-19.0)) at lag 5 day and a maximum interleukin-1ß increase (103% (95% CI: 47-159)) at lag 2 day for an interquartile range increase in the individual dose of inhaled PM2.5 during the four seasons. Short-term exposure to PM2.5 assessed by the individual dose of inhaled PM2.5 was associated with higher airway and systemic inflammation and reduced lung function. Further studies are needed to understand better underlying mechanisms of lung damage following acute exposure to PM2.5.

The effect of sleep duration and sleep quality on hypertension in middle-aged and older Chinese: the Dongfeng-Tongji Cohort Study.

OBJECTIVE: To examine the independent and combined associations of sleep duration and sleep quality with hypertension in a middle-aged and older Chinese population. METHODS: We included 21,912 individuals aged 62.2 years at baseline from September 2008 to June 2010, and they were followed until October 2013. Sleep duration was self-reported and sleep quality was evaluated with questions designed according to the Pittsburgh Sleep Quality Index. Hypertension was defined as blood pressure ≥140/90 mmHg, or self-reported physician diagnosis of hypertension, or self-reported current use of antihypertensive medication. RESULTS: In the cross-sectional analyses, the odds ratio of hypertension prevalence was significantly elevated (OR = 1.13, 95% CI = 1.03-1.24) in those who slept less than 7 h after adjusting for sex, age, body mass index, midday napping, cigarette smoking and sleep quality. It was particularly evident among males (OR = 1.19, 95% CI = 1.01-1.40) and individuals who were thin (OR = 2.00, 95% CI = 1.01-3.93) with full adjustment. The association was also found for sleep duration of 9∼<10 h after adjusting various covariates (OR = 1.14, 95% CI = 1.04-1.27). In addition, impaired sleep quality was only associated with hypertension in obese individuals (OR = 1.25, 95% CI = 1.02-1.50), not in other subgroups. However, no significant association was detected in any category of sleep duration or sleep quality in all models in the prospective analyses, and the results remained unchanged in the subgroup analyses of sex, age and body mass index. CONCLUSIONS: The results of this study provide limited support for association of sleep duration and sleep quality with hypertension in middle-aged and older Chinese. Further studies are needed to confirm the results.

Association of regular physical activity with total and cause-specific mortality among middle-aged and older Chinese: a prospective cohort study.

Association between physical activity and mortality has rarely been investigated among the Chinese population. Furthermore, the most appropriate amount of physical activity for longevity benefits remains unclear. We used data from the Dongfeng-Tongji cohort, including 24,606 middle-aged and older retired adults in 2008 and followed to 2013, to quantify linear and non-linear dose-response relationships between regular physical activity and mortality risks by Cox proportional hazards model. Compared with participants who did not engage in regular physical activity, those performing regular physical activity had significantly 46%, 56%, and 49% decreased risks of mortality from all causes, circulatory, and respiratory diseases, respectively. Each one-SD increase in regular physical activity was associated with 32% decrease of respiratory disease mortality. There were significant nonlinear dose-response associations between regular physical activity and mortality from all causes and circulatory diseases. Mortality risks decreased monotonically with increased regular physical activity amount, and appeared to reach a threshold at around 100 MET-hours/week. More mortality benefits were found among non-smokers than that among current and former smokers. Our results suggest that middle-aged and older Chinese adults can achieve mortality benefits from regular physical activity at the WHO recommended minimum, and the benefit threshold appears at approximately 100 MET hours/week.

Associations of Exhaled Carbon Monoxide and Fractional Exhaled Nitric Oxide with Metabolic Syndrome: A Cohort Study.

Exhaled carbon monoxide (eCO) and fractional exhaled nitric oxide (FeNO) could reflect underlying inflammatory and oxidative stresses, which play important roles in pathogenetic pathways of metabolic syndrome (MetS). However, epidemiologic evidence was limited. We conducted a study in Wuhan-Zhuhai (WHZH) cohort of 3649 community participants to investigate the association between eCO, FeNO and MetS in both cross-sectional and prospective ways. The results showed that higher eCO and FeNO were associated cross-sectionally with a higher prevalence of MetS. The multivariable-adjusted odds ratios for MetS at baseline were 1.22 (95% confidence interval [CI]: 1.11 to 1.35) associated with per log eCO and 1.14 (95% CI: 1.00 to 1.30) associated with per log FeNO. During a follow-up of 3 years, 358/2181 new developed MetS cases were identified. Compared with lowest quartile of eCO and FeNO, the multivariable-adjusted risk ratios (95% CI) for MetS were 1.48 (1.06 to 2.06) related to the highest quartile of eCO. These findings remained consistent across sex but not smoking status, eCO was only associated with MetS in non-smokers when stratified by smoking status. In conclusion, our study demonstrated that eCO and FeNO were independently and positively associated with the prevalence of MetS cross-sectionally, while only eCO was positively related with the incidence of MetS prospectively.

[Comparison of two methods for fiber count concentration determination].

OBJECTIVE: To compare the determination methods of fiber number concentration between China and WHO. METHODS: Individual fiber samplings were conducted at a RCF manufacturing enterprise for 40 types of work. Flow rate was set as 2 L/min and lasted 2 to 4 hours. We used acetone-triacetin to prepare samples. The rules of two methods were used to count fibers for each sample respectively. The differences between the results of two methods were compared using the sign-rank test, and the correlation between the two methods' counting results were evaluated by the Spearsman rank correlation analysis. RESULTS: The results of WHO counting rule were higher than those of Chinese counting rule for the same sample. The ratios of WHO method to Chinese method ranged from 1.88 to 3.70. Paired sign-rank test found the statistically significant differences of the results between the two methods (P<0.01). The rank correlation coefficient of the results by two rules counting ranged between 0.621 to 0.975, suggested positive correlation (P<0.01). The possible reasons of the difference between the two methods included the difference between the shapes of asbestos fiber and man-made mineral fiber, and counting rules of two methods. CONCLUSION: The results of WHO counting method is higher than those of Chinese counting method. High correlations between the results of the two methods were observed.