RESUMO
The high-temperature superplastic deformation behavior of rolled Mg-8Al-2Sn (AT82) and Mg-8Al-1Sn-1Zn (ATZ811) alloys were investigated in this study. During tensile deformation at 573 K, no obvious grain growth occurred in both alloys, because of the high-volume fraction of second phases located at grain boundaries. Meanwhile, texture weakening was observed, suggesting that grain boundary sliding (GBS) is the dominant superplastic deformation mechanism, which agreed well with the strain rate sensitivity (m) and the activation energy (Q) calculations. The microstructural evolution during tensile deformation manifested that there were more and larger cavities in AT82 than ATZ811 during high-temperature tensile deformation. Therefore, superior superplasticity was found in the ATZ811 alloy that presented a tensile elongation of ~510% under a strain rate of 10-3 s-1 at 573 K, in contrast to the relatively inferior elongation of ~380% for the AT82 alloy. Meanwhile, good tensile properties at ambient temperature were also obtained in ATZ811 alloy, showing the ultimate tensile strength (UTS) of ~355 MPa, yield strength (YS) of ~250 MPa and elongation of ~18%. Excellent mechanical performance at both ambient and elevated temperatures can be realized by using economical elements and conventional rolling process, which is desirable for the industrial application of Mg alloy sheets.
RESUMO
Objective To investigate the effects and cost of four formulations of niclosamide ethanolamine salt in Oncomela-nia hupensis snail control in the field in marshland and lake regions,so as to provide the evidence for drawing up the plan of mol-luscicide using in schistosomiasis endemic areas. Methods One drainage channel and one channel without water in the same area with snails in Jiangling County,Jingzhou City were selected as the research fields. The drainage channel was divided into 9 sections,except one section as a blank control group where the natural death rate of snails was observed only,and the remaining 8 sections were taken as the observation groups,where different dosages of 4％niclosamide ethanolamine salt powder,5％ni-closamide ethanolamine salt granules,25％ niclosamide ethanolamine salt suspending agent,26％ metaldehyde and ni-closamide ethanolamine salt suspending agent,and 50％niclosamide ethanolamine salt wettable powder were used re-spectively. The channel without water were divided into 4 sections,except one section as a blank control group,the oth-er 3 segments were taken as the observation groups,where 4％niclosamide ethanolamine salt powder,5％niclosamide ethanolamine salt granules,and 50％ niclosamide ethanolamine salt wettable powder were used respectively. Before and after spraying molluscicide for 7 days and 15 days,the system sampling method was used to observe the effects of snail control. Meanwhile,the unit cost method was used to calculate the costs of the different mulluscicide formulations abovementioned in unit area(1 m2). Results In the field at the drainage channel,the snail mortality rates of the groups spraying 4％niclosamide ethanolamine salt powder(50 g/m2),5％niclosamide ethanolamine salt granules(40 g/m2),25％ niclosamide ethanolamine suspending agent,26％ metaldehyde and niclosamide ethanolamine salt sus-pending agent,and 50％niclosamide ethanolamine salt wettable powder(2 g/m2 and 4 g/m2)for 7 days were 79.52％-97.87％,while the rates after spraying for 15 days were 71.00％-96.30％,and compared with those before spraying, the differences were statistically significant(all P<0.01). For the groups spraying with 2 g/m2 or 4 g/m2 suspending agent as well as wettable powder for 7 days,the snail mortality rates were significantly different(both P<0.05). In the field at the channel without water,the snail mortality rates of the 3 observation groups after spraying molluscicide for 7 days were 97.14％-100％,while for 15 days were 94.32％-100％,and compared with the rates before spraying,all the differences were statistically significant(all P<0.01). The unit costs per 1 m2 of the molluscicide abovementioned were ranged from 0.280 Yuan to 0.416 Yuan. Conclusions In marshland area inside embankment,the molluscicide formulations of the powder and granule are suitable for the environments without water or with instability water level , while the molluscicide formulations of the suspended agents and wettable powder are suitable for the water environment. Though the unit cost of powder is the lowest,the molluscicide in this formulation flies away seriously.
