Effect of Fine Steel Slag Powder on the Early Hydration Process of Portland Cement

Hydration heat evolution, non-evaporative water, setting time and SEM tests were peorormed to investigate the effect of fine steel slag powder on the hydration process of Portland cement and its mechanism. The results show that the effect of fine steel slag powder on the hydration process of Portland cement is closely related to its chemical composition, mineral phases, fineness, etc. Fine steel slag powder retards the hydration of portland cement at early age. The major reason for this phenomenon is the relative high content of MgO , MnO2, P2O5 in steel slag, and MgO solid solved in C3 S contained in steel slag.

Early planetary processes and light elements in iron-dominated cores

This paper discusses the latest research on the accretion and differentiation of terrestrial planets and multidisciplinary constraints on light elements in irondominated metallic cores.The classic four-stage model of terrestrial planet formation advocates slow and local accretion.Meanwhile,the pebble accretion model suggests fast accretion for planets,while the Grand Tack model provides heterogeneous accretion mechanisms.Terrestrial planets and small interstellar bodies may have experienced at least some degree of partial melting due to the three primary energy sources(i.e.,the decay of short-lived radioactive nuclides,the kinetic energy delivered by impacts,and the conversion of gravitational potential energy).Together with metal-silicate separation mechanisms,the magma ocean theory depicts the pattern of core formation in terrestrial planets.Several hypotheses have been proposed to explain the concentration of siderophile elements in the mantle,including the single-stage,continuous,and multistage core formation models,and the lateveneer model.Some light elements have been postulated in the core to account for Earth’s outer core density deficit.A plethora of constraints on the species and concentration of light elements have been put forward from the perspectives of cosmochemical and geochemical fingerprints,geophysical observations,mineral physics,numerical modeling,and theoretical prediction.Si and O may be the two leading candidates for Earth’s outer core light elements;however,it still remains an open question.S is another potential light element in Earth’s core,most likely with less than 2 wt%.Other light elements including H and C,may not exceed1 wt%in the core.Moreover,the accretion and differentiation history would provide some clues to light elements in other terrestrial planetary cores.In principle,a larger heliocentric distance corresponds to accretion from more oxidized materials,leading to a higher S concentration in the Martian core.On the contrary,Mercury is close to the Sun and has accreted from more reduced materials,resulting in more Si in the core.

Analysis of stable components for extended-range (10-30 days) weather forecast:A case study of continuous overcast-rainy process in early 2009 over the mid-lower reaches of the Yangtze River

A continuous overcast-rainy weather(CORW) process occurred over the mid-lower reaches of the Yangtze River(MLRYR) in China from February 14 to March 9 in 2009,with a large stretch and long duration that was rarely seen in historical records.Using the empirical orthogonal function(EOF),we analyzed the geopotential height anomaly field of the NCEP-DOE Reanalysis II in the same period,and defined the stable components of extended-range(10-30 days) weather forecast(ERWF).Furthermore,we defined anomalous and climatic stable components based on the variation characteristics of the variance contribution ratio of EOF components.The climatic stable components were able to explain the impact of climatically averaged information on the ERWF,and the anomalous stable components revealed the abnormal characteristics of the continuous overcast-rainy days.Our results show that the stable components,especially the anomalous stable components,can maintain the stability for a longer time(more than 10 days) and manifest as monthly scale low-frequency variation and ultra-long-wave activities.They also behave as ultra-long waves of planetary scale with a stable and vertically coherent structure,reflect the variation of general circulation in mid-high latitudes,display the cycle of the zonal circulation and the movement and adjustment of the ultra-long waves,and are closely linked to the surface CORW process.