Search

• First application of WBE in Eastern China to assess the community-wide antimicrobials usage. • Spatiotemporal trends in concentrations, daily loads and population-normalised daily loads were measured. • Paired parent and metabolite analysis were included. • Contribution of environmental AMR from antibiotic manufacturing was recognised. Wastewater-based epidemiology (WBE) has potential to identify the epidemiological links between people, animals, and the environment, as part of antimicrobial resistance (AMR) surveillance. In this study, we investigated six wastewater treatment plants (WWTPs) serving six communities located in two regions in Eastern China: Site A in Zhejiang and site B in Jiangsu province to assess the public use of antimicrobial agents (AA). Fifty antimicrobials and 24 of their metabolites were quantified using ultraperformance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS). Spatiotemporal trends were established for measured concentrations, daily loads, and population-normalised daily loads. Daily AA mass loads varied between 1.6 g/day and 324.6 g/day reflecting the WWTP scales, with macrolides and β-lactams showing the highest overall environmental burden at 223.7 g/day and 173.7 g/day, respectively. Emissions of antibiotic residues from manufacturing have been observed, with the peak daily load 12-fold higher than the overall load from a community serving a population of over 600,000. Community exposure levels of 225.2 ± 156.2 mg/day/1000 inhabitant and 351.9 ± 133.5 mg/day/1000 inhabitant were recorded in site A and B, respectively. Paired parent-metabolites analysis identified a large proportion (64–78%) of un-metabolised metronidazole and clindamycin at site B, indicating improper disposal of unused drugs either in the community or in livestock production. Consumption levels, calculated via WBE, suggested relatively low antimicrobial usage in Eastern China compared to other areas in China. This first application of WBE in Eastern China to assess the community-wide exposure to AAs has potential to inform regional antimicrobial stewardship. [Display omitted] [ABSTRACT FROM AUTHOR]

Objectives To compare the differences in antibiotic use between COPD and non-COPD residents, and to explore the effect of COPD on antibiotic use. Methods Participants aged 40 years old or over from the Songjiang Adult Cohort were included. Information on prescription and baseline survey was collected based on the health information system. A logit-negative binomial Hurdle model was used to explore correlations between COPD and percentage of antibiotic use and average rate of antibiotic prescribing of different types of antibiotic. Multinomial logistic regression was used to assess the association between COPD and antimicrobial combination therapy and routes of administration. Results A total of 34576 individuals were included and 1594 (4.6%) were COPD patients. During the 6 years' follow-up, the percentage of antibiotic use for COPD patients was 98.4%, which was 7.88 (95%CI: 5.24–11.85) times of that for non-COPD patients after adjusting for potential confounders. The prescribing rate was 3220 prescriptions (95%CI: 3063.6–3385.2) per 1000 person-years for COPD patients, which was 1.96 (95%CI: 1.87–2.06) times of that for non-COPD patients. Other beta-lactam antibacterials, Macrolides, lincosamides and streptogramins, and quinolone antibacterials were the most commonly used types of antibiotic. Except for aminoglycoside antibacterials, both percentage of antibiotic use and rate of antibiotic prescription were increased in COPD patients. COPD patients were more likely to be prescribed a maximum of two antibiotics (OR=1.34, 95%CI: 1.20–1.50); and were more likely to use antibiotics intravenously (OR=2.77, 95%CI: 2.47–3.11). Conclusion COPD patients were more likely to have increased antibiotic use in a large-scale population-based adult cohort, suggesting COPD patients are a high-priority group for the management of antibiotic use in communities. [ABSTRACT FROM AUTHOR]

• Antibiotics have been found in tap water and well water in rural Eastern China. • The dominant contaminations in drinking-water samples were macrolides and sulfonamides. • Drinking-water may be an important exposure source to antibiotics, inducing potential health risks. • Ingestion route, compared with dermal contact, may be the primary mode of exposure to antibiotic residues in drinking-water. Trace levels of antibiotics were frequently found in drinking-water, leading a growing concern that drinking-water is an important exposure source to antibiotics in humans. In this study, we investigated antibiotics in tap water and well water in two rural residential areas in Eastern China to assess the related human health exposure risks in drinking-water. Twenty-seven antibiotics were analyzed using ultra performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS). The average daily dose (ADD) and the health risk quotient (HRQ) for exposure to antibiotics in humans were evaluated using 10000 times of Monte Carlo simulations. Ten antibiotics were detected in drinking-water samples, with the maximum concentrations of antibiotic mixture of 8.29 ng/L in tap water and 2.95 ng/L in well water, respectively. Macrolides and sulfonamides were the predominant contaminants and showed the seasonality. Azithromycin had the highest detection frequencies (79.71-100%), followed by roxithromycin (25.71-100%) and erythromycin (21.43-86.96%). The estimated ADD and HRQ for human exposure to antibiotic mixture through drinking-water was less than 0.01 μg/kg/day and 0.01, respectively, which varied over sites, water types, seasons and sex. Ingestion route was more important than dermal contact route (10−6 to 10−4 μg/kg/day magnitude vs. 10−11 to 10−8 μg/kg/day magnitude). Macrolides also contributed mainly to health exposure risks to antibiotics through drinking-water, whose HRQ accounted for 46% to 67% of the total HRQs. Although the individual antibiotic and their combined effects contributed to acceptable health risks for human, the long-term exposure patterns to low-dose antibiotics in drinking-water should not be ignored. [ABSTRACT FROM AUTHOR]

In this study, the influence of Er addition on the microstructure, type transformation of second phases, and corrosion resistance of an Al–Zn–Mg–Cu alloy were explored. The results revealed that the added Er element could significantly refine the alloy grains and change the second-phase composition at the grain boundary of the alloy. In the as-cast state, the Er element significantly enhanced the corrosion resistance of the alloy due to its refining effect on the grains and second phases at the grain boundary. The addition of the alloying element Er to the investigated alloy changed the type of corrosion attack on the alloy's surface. In the presence of Er, the dominant type of corrosion attack is pitting corrosion, while the alloy without Er is prone to intergranular corrosion attack. After a solution treatment, the Al8Cu4Er phase was formed, in which the interaction with the Cu element and the competitive growth relation to the Al3Er phase were the key factors influencing the corrosion resistance of the alloy. The anodic corrosion mechanism of the Al8Cu4Er and Al3Er phases evidently lowered the alloy corrosion rate, and the depth of the corrosion pit declined from 197 μm to 155 μm; however, further improvement of corrosion resistance was restricted by the morphology and size of the Al8Cu4Er phase after its formation and growth; therefore, adjusting the matching design of the Cu and Er elements can allow Er to improve the corrosion resistance of the Al–Zn–Mg–Cu aluminum alloy to the greatest extent. [ABSTRACT FROM AUTHOR]

In order to assess Al–Zn–Mg–Cu alloys as potential high temperature structural materials, the hardness, tensile properties and fracture behaviors of 7085 Al alloy were investigated at various temperatures from room temperature to 175 °C. High-resolution transmission electron microscopy was used to investigate the evolutions of precipitates at different temperatures, particularly on the relationship between microstructural evolution and tensile strength. The results reveal that both the microstructure and mechanical properties of the alloy are quite sensitive to the environmental temperature. As the temperature increases, the hardness and strength decrease while the elongation and reduction of area increase. As tensile testing temperature rises, the strain hardening exponent (n) decreases due to the thermal softening effect. The fracture mode of the alloy transforms from mixture of intergranular and transgranular fracture to completely transgranular dimples when tensile testing temperature reaches 150 °C. The precipitate sequence during high temperature tests is coincident with that of aging. With the increase of tensile testing temperature, the mean precipitate radius grows larger, and the distribution of grain boundary precipitates transforms from continuous to discontinuous. Image 1 • Tensile tests of 7085 Al alloy was investigated from room temperature to 175 °C. • As temperature rose, strain hardening exponent decreased due to thermal softening. • Fracture mode of the material changed when tensile temperature reached 150 °C. • η′ transformed to η precipitates continuously during high temperature tests. • The average precipitate size increased with the increase of tensile temperature. [ABSTRACT FROM AUTHOR]

Long-term thermal stability plays an important role in practical applications of Al-Zn-Mg-Cu alloys. In the present work, thermal stability of the T7452-treated 7085 Al alloy was assessed at temperatures of 100, 125, 150 and 175 °C for 100, 500 and 1000 h, through hardness, electrical conductivity and tensile tests after thermal exposure. The nanoscale precipitates under different thermal exposure conditions were also qualitatively studied by transmission electron microscopy (TEM). The results show that thermal stability of the alloy is more sensitive to thermal exposure temperature than to exposure time. The hardness increases first and then decreases with the increase of exposure temperature while it decreases gradually as exposure time prolongs. However, the variation of electrical conductivity is opposite. The tensile strength, yield strength and hardness after 100 °C/100 h thermal exposure increased by 2.4%, 6.7% and 9.2% than those of the alloy without thermal exposure, respectively. The precipitate sequence during thermal exposure is coincident with that of aging. In addition, as thermal exposure deepens, the average radius of precipitates increases while the volume fraction decreases. Meanwhile, the grain boundary precipitates coarsen and transform from continuous to discrete. The influence of precipitates on properties of the alloy is discussed quantitatively. • Thermal stability of 7085 alloy was conducted under different temperatures for different durations. • Correlations between hardness and electrical conductivity of the 7085 alloy during thermal exposure were investigated. • Thermal exposure temperature played more significant effect on strength and electrical conductivity than the exposure time. • The average precipitate size increased while the volume fraction decreased as thermal exposure deepened. • The increments of yield strength before and after thermal exposure were calculated. [ABSTRACT FROM AUTHOR]

As a new generation of Al-Zn-Mg-Cu alloy, 7085 aluminum alloy is a promising structural material in the field of aerospace industry. However, research on its thermal stability is still lacking. In the present work, thermal exposure was carried out on the T7452-treated 7085 aluminum alloy under different temperatures (100 °C, 125 °C, 150 °C and 175 °C) for 500 h. Variations of tensile properties and hardness were exhibited. The microstructure, nano-scale precipitates and fracture characteristics of the alloy were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that with the increase of exposure temperature, the strength and hardness increase first and then decrease while the elongation and the reduction of area increase continuously as compared to those of the non-thermal exposed alloy. The transformation from η′ phase to η phase during thermal exposure occurs continuously during thermal exposure. In addition, as the exposure temperature increases, the average dimensions of precipitates and the average spacing of neighbor precipitates become larger. The influence of precipitates on mechanical properties of the alloy is discussed. [ABSTRACT FROM AUTHOR]