In this work, we have investigated the effect of martensite/bainite dual phase content on the mechanical properties of EA4T high-speed axle steel. For evaluation and control of the strength, ductility, and toughness of steel, the microstructure of lath martensite (LM) and granular bainite (GB) was clarified through an optical microscope (OM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Besides, the tensile fracture morphology was studied by scanning electron microscopy (SEM). For this purpose, this study conducted a quantitative analysis of the LM and GB fractions using the Pro Imaging software-2018 of OM. The remarkable effect of the LM/GB structure on mechanical properties is discussed. The results have shown that by increasing the volume fraction of the GB structure, the LM structure is refined and its microhardness and strength are improved. Meanwhile, the micro strength of LM follows the Hall–Petch relationship with the lath martensite packet size. Subsequently, the mechanical property prediction model of EA4T steel based on the LM/GB content was established by regression analysis of all experiment dates. When the LM fraction in the steel is about 40–70%, a superior combination of strength, ductility, and toughness can be obtained in EA4T steel.
The residue of 17β-estradiol (E 2) in milk could potentially lead to the occurrence of various reproductive diseases; therefore, a rapid and sensitive method for monitoring E 2 residues in milk was highly necessary. In this study, we produced new polyclonal and monoclonal antibodies using E 2-3-O-carboxymethyl ether as a hapten and developed an indirect competitive enzyme-linked immunosorbent assay (icELISA) for the detection of E 2 in milk. The results showed that the sensitivity of polyclonal antibody was higher than that of monoclonal antibody, providing a half maximum inhibition concentration (IC 50) against E 2 of 0.17 ng/mL, high cross-reactivity (CR) to E 2 benzoate (150%) and oestriol (18.02%), and negligible CR with other oestrogen compounds. Under optimized conditions, the developed icELISA based on the polyclonal antibody had a limit of detection values of 0.093 μg/L, which was enough sensitive to detect E 2 in milk. In spiked samples (0.5, 1, and 2 μg/L), the recoveries ranged from 83.12% to 94.58% with coefficients of variation <12.8%. These results indicated that the icELISA method we developed was suitable for screening of E 2 residue in milk.
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