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- 저자 : Peihua Ma (검색결과 2 건)
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Ma Haiyan,Xie Chen,Zheng Shunlin,Li Peihua,Cheema Hafsa Nazir,Gong Jing,Xiang Zhuqing,Liu Juanjuan,Qin Jiahao 한국미생물학회 2022 The journal of microbiology Vol.60 No.2
Intensive potato continuous cropping (IPCC) results in low potato yields compared with non-intensive potato continuous cropping (PCC) and potato-maize rotation (PMRC). However, it is still unclear whether the degree of potato continuous cropping obstacle is related to the soil environment formed by the previous crop. To investigate the effect of planting potatoes and planting maize after harvesting the spring potatoes on soil chemical properties and soil microbial community structure, an experiment was carried out in the same origin soil environment over a period of seven years: (a) PCC, i.e., spring planting; (b) IPCC, i.e., autumn and spring planting (IPCC); (c) PMRC, i.e., spring potatoes and summer maize (PMRC), and (d) fallow (CK). We confirmed that the potato yield under PMRC was significantly higher than that under PCC and IPCC. Under IPCC, soil total phosphorus content was significantly higher than other treatments, whereas ammonium nitrogen content was the lowest. Compared with PCC and IPCC, PMRC had a higher ammonium nitrogen content and lower total phosphorus content. The significantly different fungal taxa in IPCC (Glomerellales, Plectosphaerella, Thelebolales) may threaten the health of the plant and positive correlated with soil total phosphorus, while other microbial taxa in PMRC (Bacillales, Polythrincium, Helotiales) can mainly promotes plant nitrogen uptake and protects plants against diseases. The PMRC-promoting taxa were positively correlated with the ammonium nitrogen content and negative correlated with soil total phosphorus content. In summary, the cropping systems might have affected potato yields by changed soil microorganism community structures – especially fungal community structures – and by the chemical properties of the soils that also depends on microbes.
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Lingling Ren,Huimin Gu,Wei Wang,Shuai Wang,Chengde Li,Zhenbiao Wang,Yuchun Zhai,Peihua Ma 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.1
Despite showing considerable potential, wire arc additive manufacturing (WAAM) has been limited to producing Al–Mgalloys. As the addition of Sc can improve the mechanical properties of Al–Mg alloys, in this study, Al–Mg–Sc alloy depositswith different Sc contents were prepared by a WAAM process. The porosity, microstructure, and mechanical properties ofthe deposits were studied. At Sc contents less than 0.15%, Sc was completely dissolved in the Al matrix without grain refinement,and the mechanical properties were slightly improved. At a Sc content of 0.3%, the primary Al3Scphase precipitatedout of the as-deposited body, resulting in an abrupt change in the microstructure, significant grain refinement, significantlyincreased tensile strength and yield strength, with a tensile strength, yield strength, and elongation of 372 MPa, 270 MPa,and 22.5%, respectively. Following heat treatment at 350 °C for 1 h, the grain boundaries were refined and the secondaryAl3Scphase was precipitated. Furthermore, the tensile strength and yield strength were significantly increased to 415 MPaand 279 MPa, respectively, and elongation decreased to 18.5%. At a Sc content of 0.45%, due to the aggregated precipitatedphase, the coarsened grain boundaries and the limited solid solution amount of Sc in the α(Al) matrix (~ 0.25%), themechanical properties were not further improved compared with the deposit with Sc content of 0.3%. Thus, based on economicconsiderations, the optimal Sc content was 0.3%. Owing to their enhanced mechanical properties, WAAM-producedAl–Mg–Sc alloys are expected to have a wide range of applications in aviation, aerospace.
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