Fiber production from inorganic industrial solid wastes is an effective waste management strategy. Because of cost considerations, most enterprises generally use local solid wastes as raw materials to produce fibers. In this study, we explored the feasibility of producing fibers using fly ash and magnesium slag. The results show that the melting temperature of the blends composed of fly ash, magnesium slag, and a small amount of calcined dolomite first decreased and then increased with an increase in acidity coefficient (Mk) from 1.0 to 2.4. The samples could form a eutectic system in the Mk range of 1.4–1.8, and therefore have a relatively low melting temperature in this Mk range. Fly ash could react with magnesium slag and calcined dolomite to form akermanite, gehlenite-magnesium, and anorthite at temperatures close to the melting temperature; therefore, these crystalline phases were the main reaction products formed in the samples with Mk values lower than 1.80. Anorthite reacted further with some Na-containing and Si-containing spieces to produce labradorite. Thus, the content of anorthite and labradorite rapidly increased and they became the major crystal phases in the blend samples with Mk values greater than 1.80. MAS-NMR spectroscopic analysis revealed that the network structure of the melts depended on the ratio of bridging oxygen to non-bridging oxygen; a high ratio of bridging oxygen to non-bridging oxygen could lead to the formation of a dense network structure in the melt. The blends of fly ash and magnesium slag can be used to produce wool fibers and continuous fibers. In addition, the suitable temperature ranges for the production of both types of fibers were determined. The drawing temperature for continuous fiber production depended on the degree of polymerization and structure of the melt. 相似文献
Fe-based bulk metallic glasses (BMGs) with high boron content have potential application as a coating material used in the framework for storing spent nuclear fuels to support their safe long-term disposal. The high glass forming ability (GFA) and large supercooled liquid region are therefore required for such Fe-based BMGs in either the glassy powder fabrication or the subsequent coating spraying. In order to meet these requirements, the influence of Nb content on the GFA of Fe57Cr10Zr8B18Mo7−xNbx (x=1–5, at.%) alloys was investigated, as Nb has positive roles in GFA and thermal stability of BMGs. The results indicate that a fully amorphous phase in the as-cast samples with 3 mm in diameter is obtained for both the Fe57Cr10Zr8B18Mo5Nb2 and Fe57Cr10Zr8B18Mo4Nb3 alloys. The corresponding supercooled liquid regions of the two BMGs are 78 K and 71 K, respectively. The mechanism for improving their GFA was analyzed based on the principle of metal solidification, the parameters for glass formation and thermal properties of the alloys. The compression strength and Vicker’s hardness of the two BMGs are 1,950 MPa and 1,310 HV, 2,062 MPa and 1,180 HV, respectively. The developed BMGs with high B content, good GFA, and very high hardness can be used as coating materials to the framework for spent nuclear fuels.
Indoleamine-2,3-dioxygenase 1 (IDO1) is a heme-containing enzyme that catalyzes the rate-limiting step in the kynurenine pathway of tryptophan (TRP) metabolism. As it is an inflammation-induced immunoregulatory enzyme, pharmacological inhibition of IDO1 activity is currently being pursued as a potential therapeutic tool for the treatment of cancer and other disease states. As such, a detailed understanding of the mechanism of action of IDO1 inhibitors with various mechanisms of inhibition is of great interest. Comparison of an apo-form-binding IDO1 inhibitor (GSK5628) to the heme-coordinating compound, epacadostat (Incyte), allows us to explore the details of the apo-binding inhibition of IDO1. Herein, we demonstrate that GSK5628 inhibits IDO1 by competing with heme for binding to a heme-free conformation of the enzyme (apo-IDO1), whereas epacadostat coordinates its binding with the iron atom of the IDO1 heme cofactor. Comparison of these two compounds in cellular systems reveals a long-lasting inhibitory effect of GSK5628, previously undescribed for other known IDO1 inhibitors. Detailed characterization of this apo-binding mechanism for IDO1 inhibition might help design superior inhibitors or could confer a unique competitive advantage over other IDO1 inhibitors vis-à-vis specificity and pharmacokinetic parameters. 相似文献