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Investigating the seeding mechanism of precision seeders is of great significance for improving the quality of cotton sowing operations. This paper designs a rotary type-hole cotton precision mulching dibbler. The main factors influencing the entry of cotton seeds into the seed wheel holes during the seeding process are then theoretically analyzed. Following this, an accurate discrete element model of coated cotton seeds is established and combined with a discrete element method (DEM) and multi-body dynamics (MBD)-coupled simulation model of the seed drill for seed picking and planting. Simulation experiments on the seeding performance of the precision dibbler were performed to study the influence of the seed wheel structure and motion parameters on the picking and planting performance under different speeds. The optimal parameter combination for the seed wheel is obtained through optimization experiments, and a precision dibbler is manufactured for bench testing. The bench test results are consistent with the simulation test results. At the precision dibbler rotation speed of 16 r/min, the qualified index reaches a maximum value of 93.28%, the skip sowing index increases with the precision dibbler rotation speed, and the re-sowing index decreases as the speed increases. These optimization results significantly improved seeding precision and efficiency and are of great significance for the reliability and effectiveness of cotton sowing operations. [ABSTRACT FROM AUTHOR]

Secreted phospholipase A2s (sPLA2s) are a group of enzymes with 6–8 disulfide bonds that participate in numerous physiological processes by catalyzing the hydrolysis of phospholipids at the sn-2 position. Due to their high content of disulfide bonds and hydrolytic activity toward cell membranes, obtaining the protein of sPLA2s in the soluble and active form is challenging, which hampers their functional study. In this study, one member of recombinant human sPLA2s, tag-free group IIE (GIIE), was expressed in Pichia pastoris. The protein GIIE was purified from the crude culture supernatant by a two-step chromatography procedure, a combination of cation exchange and size-exclusion chromatography. In the shake flask fermentation, Protein of GIIE with higher purity was successfully obtained, using basal salts medium (BSM) instead of YPD medium. In the large-scale fermentation, each liter of BSM produced a final yield of 1.2 mg pure protein GIIE. This protocol will facilitate further research of GIIE and provide references for the production of other sPLA2 members. [ABSTRACT FROM AUTHOR]