摘要
利用基质辅助激光解吸/电离飞行时间质谱(MALDI-TOF MS)检测食源性致病菌沙门氏菌属细菌。通过MALDI-TOF MS主成分分析及聚类分析等方法,对不同血清型、不同地区来源及不同宿主的74株沙门氏菌进行溯源研究。结果显示74株沙门氏菌中相同宿主或地区来源的菌株MALDI-TOF MS肽指纹图谱相似性较好,相同宿主或地区来源的沙门氏菌菌体蛋白表达更为相似。表明沙门氏菌分离宿主及地区来源可能影响沙门氏菌的菌体蛋白表达,MALDI-TOF MS可作为沙门氏菌检测和溯源分析的工具。
In order to investigate the feasibility of water toughening treatment of ZGMn13 （Hadfield） steel at lower temperature, microstructure of the steel water cooled from different heating temperatures was studied. The microstructure of the steel jominy end- quenched from 950 ℃ and 1050 ℃ by end water cooling at different distances from the quenched end was observed by mctallographic analysis method. The critical cooling rates of the Hadfield steel heated at 950 ℃ and 1050 ℃ for acquiring wholly austenite were obtained by theoretical analysis based on the experimental result. The results show that for Hadfield steel with 1.2 mass% C, the microstructure with full austenite can be got when the temperature reaches 950 ℃. The maximum distance from the quenched end for disappearance of the intergranular carbide in austenite matrix is 65 mm for the Hadfield steel heated at 950 ℃ in jominy end quench test, which is less than the value of 100 mm at 1050 ℃. Calculated by the heat transfer theory, the critical cooling rate for full austenite at 950 ℃ is 0.78 ℃/s, higher than the value of 0. 63 ℃/s at 1050 ℃. Accordingly, the critical cooling diameter of the part heated at 950 ℃ is about 170 mm for water toughening treatment of Hadfield steel. Therefore, when the diameter of Hadfield steel part with lower carbon content does not exceed 170 mm, the single-phase austenite can be obtained when the part is heated at 950 ℃ and water cooled.
出处
《食品科技》
CAS
北大核心
2013年第12期315-320,共6页
Food Science and Technology
基金
科技部质检公益性专项课题(201210043)
