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Native starches and their phosphates with various molecular structures was introduced as the depressant to realize the flotation of quartz from hematite in this study. The present starch phosphates (WSP, NSP, GSP) were modified by the reaction between phosphate and three different corn starches (WS, NS, G50). The synthesis and characterization of starch phosphates found that starch with high amylopectin content was easily modified into starch phosphates. Microflotation tests showed that starch phosphates exhibited stronger depressing abilities of hematite flotation than native starches. Zeta potential measurement showed that both starches and starch phosphates could positively shift the zeta potential of hematite, while starch phosphates had more effects than starches. XPS and MDS indicated that the chemisorption occurred between Fe of hematite surface and C O groups of starch-based depressants. In addition, starch phosphates could adsorb onto the hematite surface through P O groups. MDS also presented that the adsorption strength of starch phosphate was mainly determined by the type and number of generating chelating rings, and the molecular structure of starch significantly affected the formation of chelate rings. The proposed adsorption model insights will significantly promote the development of starch-based depressants for iron ore flotation and other mineral processing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects women of reproductive age. Resistant starch can be fermented by gut microbes then produce short-chain fatty acids (SCFAs). It was reported SCFAs might play a key role in gut microbiota-dependent therapy of PCOS. However, the effects of resistant starch on PCOS symptoms have not yet been investigated. Here, maize starch was acylated with specific SCFAs. Our results indicated that acylated starch can release acetate, propionate, and butyrate into the caecum and colon. Treatment with butylated starch (BS) alleviated abnormal ovarian morphology, metabolic disorders, and sex hormone imbalance in letrozole-treated rats, whereas treatment with acetylated starch and propylated starch did not exhibit such effects. Furthermore, BS stimulated the secretion of peptide tyrosine-tyrosine into the serum by activating a G protein-coupled receptor, GPR41, which further affected disease phenotypes. In addition, compared with caecal microbiota, faecal microbiota was more affected by BS. Butyrate-producing microbes were enriched in faeces after BS treatment and may have helped further to relieve PCOS symptoms. [Display omitted] [ABSTRACT FROM AUTHOR]