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- ArticleChakraborty M, Kundu S, Bhattacharjee A.RSC Adv. 2023 Nov 30;13(50):34972-34986.Thermal decomposition of a mixture of ferrocene carboxaldehyde and oxalic acid dihydrate in O2 atmosphere produced rod-like hematite nanomaterial. The decomposition reaction was complex as evident from the overlapped multistep reaction steps in the non-isothermal thermogravimetry (TG) profiles obtained in the 300-700 K range. A peak deconvolution method was applied to separate the overlapped reaction steps. The multistep TG profiles were successfully deconvoluted, which showed that the decomposition occurs in six individual steps. However, it was found that only the last three reaction steps were responsible for the production of hematite. To estimate the activation energy values for these thermal reactions, six model-free integral isoconversional methods were used. The activation energy value significantly depends on the extent of conversion in each step; however, the nature of its dependence significantly different for each step. The most probable stepwise reaction mechanism functions for the solid-state reactions were obtained using the master plot method. The reaction mechanism was found to be different for different steps. Utilizing the activation energy and reaction mechanism function, the reaction rates of decomposition for each step were determined. To substantiate the validity of the assumed kinetic models, the experimental conversion curves were compared with the constructed ones, and the agreement was quite reasonable. The conversion-dependent thermodynamic parameters were obtained utilising the estimated kinetic parameters. Role of the co-precursor in the thermal reaction of the precursor was plausibly revealed. The present study describes how the use of a co-precursor significantly enhances the thermal decomposition of the precursor, how hematite nanomaterials can be synthesized from a co-precursor driven solid state reaction at low temperatures, and how the kinetic calculations facilitate the understanding of the solid-state reaction process. This study proposes the use of a suitable combination of precursor and co-precursor for solid-state thermal synthesis of iron-based nanoparticles using organo-iron compounds as precursor and also illustrates the effective application of the thermal analysis technique to understand the decomposition reaction.
- ArticleZhang X, Ren XY, Hong X, Gao XY.RSC Adv. 2019 Oct 28;9(60):34972-34985.The properties and friction behavior of ZCuPb20Sn5 modified with P were investigated. With the P addition and content increase, the second phase appeared and gradually increased in amount. Also, the microstructure of ZCuPb20Sn5 was refined and evenly distributed. The addition of P had a beneficial effect on the microstructure and properties of ZCuPb20Sn5. As the P content increased, the hardness and tensile strength of ZCuPb20Sn5 increased, but the elongation, the friction coefficient and the wear rate decreased. The wear mechanism of ZCuPb20Sn5 was mainly adhesive wear, and a small amount of debris was produced. As the P content increased, the anti-wear resistance of ZCuPb20Sn5 deteriorated.
- ArticleJiao X, Sun W, Zhang Y, Liu X, Zhang Q, Wang Q, Zhang S, Zhao ZK.RSC Adv. 2018 Oct 10;8(61):34967-34972.The yeast Saccharomyces cerevisiae serves as a promising host for the production of a wide range of chemical compounds and fuels. Currently, simultaneous expression of several genes could be achieved via the use of 2A viral peptides, yet detailed characterizations to assess the discrepancy of different orders of genes linked by 2A peptides are rarely sufficient. In this study, we investigated the effects of the order of genes linked by porcine teschovirus-1 2A (P2A) peptide on the metabolic pathway in S. cerevisiae. A heterologous carotenoid biosynthetic system involving nine kinds of polycistronic expression of codon-optimized carotenogenic genes GGPPS, CARB and CARRP from Blakeslea trispora was introduced into S. cerevisiae. The order of genes in the polycistronic segment was exchanged; β-carotene production by engineered yeasts was significantly different. The highest β-carotene yield was achieved in transformants carrying the plasmid, with CARB as the first gene in the polycistronic construct regardless of the location of GGPPS, CARRP. In addition, we found that β-carotene production was coupled with the growth in engineered strain with the highest β-carotene content during the shake flask fermentation and fed-batch fermentation. A novel microbial heterologous carotenoid production system was established by optimizing the order of genes linked by P2A peptide sequences in a polycistronic expression construct. The observation of the importance of the order in a polycistronic construct may be used to increase yields in other P2A peptide-containing expression systems.