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For demanding applications high steel cleanliness and strictly controlled inclusions are required. Primary inclusions are formed during steel treatments in the ladle. Most of these are removed to the ladle slag or on the lining. However, the rest of the inclusions still remain through the successive process stages, and additionally new inclusions are formed during casting and solidification due to decreasing thermodynamic solubility of oxygen in the steel at lower temperatures, reactions with surrounding slag, refractory materials and eventual contact with air. Inclusions formation and transformation are simulated by thermodynamic calculations in the steel/inclusions/slag system taking into account the solidification phenomena. In this paper inclusions in Si/Mn‐deoxidised steel and Al‐deoxidised Ca‐treated steels are contributed. Calculations are compared with experimental results from steel plants. 相似文献
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冶炼用钙灰在存放期间,由于暴露在空气中,钙灰堆表面钙灰与空气接触,吸收空气中的水分消化从而影响钙灰的质量。简要分析钙灰中CaO含量降低原因。 相似文献
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《The IES Journal Part A: Civil & Structural Engineering》2013,6(2):154-162
Investigated herein is the effect of temperature on heat development in cement pastes and concretes with and without silica fume cured at relatively high temperatures often encountered in tropical environment. With an initial temperature of 30°C, adiabatic temperature rise of the concrete with 8% silica fume as cement replacement was similar to that of the control Portland cement concrete up to about 18 h. After 24 h, however, the temperature of the silica fume concrete was lower than that of the control concrete. Since the concrete with 8% silica fume had a higher 28-day compressive strength (72.5 MPa) than the control concrete without silica fume (59.2 MPa), the concrete with silica fume is likely to have a lower temperature rise as compared with the control concrete of equivalent 28-day strength by reducing cementitious materials content with the same water content. The extent of heat evolution in the silica fume pastes was generally greater at lower temperatures of 20–50°C, but less at 65°C than in the control paste. At the relatively high curing temperatures, the degree of cement hydration in the paste with silica fume was lower than that in the control cement paste at early ages. However, the pozzolanic reaction started even before 24 h after water was added. 相似文献
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Trave G.; Cregut D.; Lionne C.; Quignard J.-F.; Chiche L.; Widada J.; Liautard J.-P. 《Protein engineering, design & selection : PEDS》1994,7(5):689-696
All the functions of annexins in vitro as well as in vivo aremediated and probably regulated by calcium. We have used recombinantannexin I, synthesized by Escherichia coli, and we have performedsite-directed mutagenesis. We have mutated the endonexin foldof domain 2 that binds calcium. Mutations were performed inthis domain of the molecule because it perfectly matches thecalcium binding consensus sequence. The two glycines of thisfold were mutated into glutamic acid. The helix content andthe stability of the mutants are identical to those of the wild-type,suggesting that the mutations did not drastically affect thestructure of the protein. The two mutants showed modified calciumbinding affinities. However, the calcium binding affinity ofthe G131E mutant was far more altered than that of the G129Emutant. Furthermore, other biochemical properties of these mutantswere modified to different extents. The binding to phospholipidwas not seriously affected, whereas the selfassociation waslost by the G131E mutant. In the same way, liposome aggregationis conserved, but modified, while the calcium affinity measuredby equilibrium dialysis is dramatically altered. 相似文献