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Magnetization reduction roasting is an important method for the utilization of oolitic magnetite. In this study, the magnetization reduction behavior and kinetics of oolitic hematite in gas-based roasting were systematically investigated by X-ray photoelectron spectroscopy (XPS). The results revealed that under optimal roasting conditions of 650 °C, a roasting time of 60 min, and a CO concentration of 30%, the magnetization reduction rate of the roasted product reached 44.34%. Furthermore, the weak magnetic separation concentrate presented a TFe of 58.09% and a concentrate iron recovery of 94.3%. The results of the XPS spectrum indicated that the peak area ratio (Fe2+/Fe3+) gradually increased with an increase in roasting temperature, roasting time, and CO concentration, while over-reduction occurred when the roasting temperature exceeded 750 °C. The investigation of magnetization roasting kinetics for varying particle sizes demonstrated that the magnetization reduction process is controlled by chemical reaction, with a corresponding activation energy range of 42.96 kJ/mol to 63.29 kJ/mol, indicating the particle size has little effect on the magnetization reduction of oolitic hematite. [ABSTRACT FROM AUTHOR]

Edible bird's nest (EBN) has been proven to exhibit whitening activity. In spite of this, the relationship between the digestive products of EBN and the whitening activity is still unclear. Hence, the B16-F10 cell model was used in this study to study the whitening activity of simulated EBN digestion products in vitro. The simulated digestive juices showed significant inhibition of tyrosinase (TYR) (P < 0.05), and the release rate of free sialic acid was 21.87% in EBN digestive juices. After simulated gastrointestinal digestion, the relative contents of <1 kDa components, 1–3 kDa components, and >3 kDa components were 42.63%, 15.05%, and 42.32%, respectively. EBN digestive products were further fractionated, and the fraction of <1 kDa (EPP-1) exhibited the highest tyrosinase inhibitory activity with 83.12% and its peptides content was 92.44%. The EPP-1 significantly inhibited tyrosinase activity and decreased melanin content (P > 0.05) by regulating the cAMP/MITF/TRP-1/TRP-2 tyrosinase signaling pathways in the B16-F10 cell experiment. Based on these findings, our data suggest that the digestive products of EBN may potentially be fit for developing a new generation of natural whitening health products. [ABSTRACT FROM AUTHOR]

In order to promote the high value-added utilization of high calcium fly ash, the geopolymer with excellent mechanical properties was prepared using fly ash as main raw material by water glass alkali excitation. Then, hydrogen peroxide was introduced as foaming agent, sodium dodecyl sulfate (SDS) was used as foaming stabilizer and the foaming process was optimized to prepare porous foaming geopolymer. The pore size distribution of foaming section was analyzed by Image-Pro Plus image software and the microstructure of foaming geopolymer was characterized by XRD, FTIR and SEM-EDS. The results show that under the conditions of liquid-solid ratio of 0. 50, alkali equivalent of 10% (mass fraction), water glass modulus of 1. 50, H2O2 content of 3% (mass fraction), SDS content of 0. 3% (mass fraction) and foaming at 80 °C for 4 h, the 28 d compressive strength of specimen after standard curing is 1. 78 MPa, and the apparent density is 631 kg/m³. Foaming geopolymer has small pore size and uniform distribution, resulting in low density. The polymerization product is a small amount of C-S-H gel and a large amount of N(C)-A-S-H gel produced by the synergistic reaction of calcium, aluminum and sodium, which ensures the mechanical strength of foaming geopolymer. [ABSTRACT FROM AUTHOR]

Sintering accounts for about 50% of the total NOx emissions of the iron and steel industry. NOx emissions from the sintering process can be simulated using the emissions from coke combustion. However, the generation and emission law for NOx burning in the sintering process of pulverized coal is still not clear. The formation characteristics of NOx during coal combustion catalyzed by iron ore fines and several iron-containing pure minerals were studied in this paper. The results showed that iron ore fines can improve the NOx emission rate and increase the total NOx emissions during coal combustion. The type and composition of the iron ore fines have an important impact on the generation and emission of NOx in the process of coal combustion. The peak concentration and emissions of NOx in coal combustion flue gas with limonite, hematite or specularite added increased significantly. The peak value for the NOx concentration in the coal combustion flue gas with magnetite or siderite added increased, but the emissions decreased. Therefore, the generation of NOx in the sintering process can to a certain extent be controlled by adjusting the type of iron-containing raw materials and the distribution of the iron-containing raw materials and coal. [ABSTRACT FROM AUTHOR]