Formation of a mineral layer during coke dissolution into liquid iron and its influence on the kinetics of coke dissolution rate

The formation and development of the mineral layer that forms between coke and liquid iron during carbon dissolution has been characterised. Coke particles (-2mm, +0.5mm) were added to the top surface of an iron 2 mass% C melt at representative ironmaking temperatures, for periods of time between 2 minutes and 120 minutes, before being quenched. The quenched samples were then sectioned and the solidified coke-melt interfacial region analysed in the SEM. Analysis showed that a mineral layer was present at the interface at all experimental temperatures (1450-1550oC) from 2 minutes and persisted beyond 120 minutes. The mineral layer was found to be composed of calcium aluminate phases, with the proportions of these phases dictating its morphology. Further, changes observed in the rate of carbon dissolution from the coke were related to the composition and morphology of the mineral layer. The effect of this mineral layer on the rate of carbon dissolution has been interpreted as a change in the reaction control mechanism

The effect of sulfur concentration in liquid iron on mineral layer formation during coke dissolution

The effects of sulfur concentration in liquid iron on mineral layer development between coke and iron as coke dissolves in a 2 mass % carbon-iron liquid have been investigated at 1500°C. Initial sulfur in iron concentrations used ranged from 0.006 to 0.049 mass %. Key findings include that the two stage dissolution behavior exhibited in the carbon transfer from coke to iron as reported in a previous study by the authors, at low initial sulfur in iron contents, was also apparent at the higher values used in this study. This two stage behavior was attributed to a change in the mineral layer density, as a result of changes in mineral morphology at the interface. In addition to confirming the two stage behavior of the carbon transfer kinetics at the higher sulfur concentration in iron levels, it was also found that after a period of time a solid calcium sulfide layer formed on the mineral layer. The sulfide layer formed after approximately 40 minutes and the proportion of sulfide in the mineral layer increased with increased experimental time and initial sulfur concentration in iron. It was usually found at the iron side of the mineral layer and associated with calcium enriched calcium aluminates. Thermodynamic analysis of this layer confirmed that the sulfide is stabilized as the mineral layer is enriched by calcium

Progranulin mediates immune evasion of pancreatic ductal adenocarcinoma through regulation of MHCI expression

Immune evasion is indispensable for cancer initiation and progression, although its underlying mechanisms in pancreatic ductal adenocarcinoma (PDAC) are not fully known. Here, we characterize the function of tumor-derived PGRN in promoting immune evasion in primary PDAC. Tumor- but not macrophage-derived PGRN is associated with poor overall survival in PDAC. Multiplex immunohistochemistry shows low MHC class I (MHCI) expression and lack of CD8(+) T cell infiltration in PGRN-high tumors. Inhibition of PGRN abrogates autophagy-dependent MHCI degradation and restores MHCI expression on PDAC cells. Antibody-based blockade of PGRN in a PDAC mouse model remarkably decelerates tumor initiation and progression. Notably, tumors expressing LCMV-gp33 as a model antigen are sensitized to gp33-TCR transgenic T cell-mediated cytotoxicity upon PGRN blockade. Overall, our study shows a crucial function of tumor-derived PGRN in regulating immunogenicity of primary PDAC