Dissolution Behavior of Mg from Magnesia-Chromite Refractory into Al-killed Molten Steel

Magnesia-chromite refractory materials are widely employed in steel production, and are considered a potential MgO source for the generation of MgO·Al₂O₃ spinel inclusions in steel melts. In this study, a square magnesia-chromite refractory rod was immersed into molten steel of various compositions held in an Al₂O₃ crucibles. As the immersion time was extended, Mg and Cr gradually dissolved from the magnesia-chromite refractory, and the Mg and Cr contents of the steel melts increased. However, it was found that the inclusions in the steel melts remained as almost pure Al₂O₃ because the Mg content of the steel melts was low, approximately 1 ppm. On the surface of the magnesia-chromite refractory, an MgO·Al₂O₃ spinel layer with a variable composition was formed, and the thickness of the MgO·Al₂O₃ spinel layer increased with the immersion time and the Al content of the steel melts. At the rod interface, the formed layer consisted of MgO-saturated MgO·Al₂O₃ spinel. The MgO content decreased along the thickness direction of the layer, and at the steel melts interface, the formed layer consisted of Al₂O₃-saturated MgO·Al₂O₃ spinel. Therefore, the low content of Mg in steel melts and the unchanged inclusions were because of the equilibrium between Al₂O₃-saturated MgO·Al₂O₃ layer and Al₂O₃. In addition, the effects of the Al and Cr contents of the steel melts on the dissolution of Mg from the magnesia-chromite refractory are insignificant.     

Hetero- and homo-epitaxial growth of 3C-SiC for MOS-FETs

Planar defects, like anti-phase boundaries (APBs) and stacking faults (SFs), are reduced by growing 3C-SiC on undulant-Si whose entire surface is covered with countered slopes oriented in the [1 1 0] and directions. During the initial 3C-SiC growth, APBs are eliminated on each slope of an undulation. Then, one kind of SF self-vanishes. However, another kind of SF remains on the 3C-SiC surface, although its density is gradually reduced with increasing SiC thickness by combining with a counter-SF. The leakage current of a pn diode fabricated homo-epitaxially on 3C-SiC is roughly proportional to the SF density before homo-epitaxial growth. The viability of 3C-SiC grown on undulant-Si for semiconductor devices is discussed by reviewing recent reports on various MOS-FETs using it as the substrate. The key issue in the fabrication of a MOS-FET as a power-switching device operated at high-voltage is to reduce the leakage-current at the pn junction, thereby eliminating SFs.     

Amorphous nanosilicas induce consumptive coagulopathy after systemic exposure

We previously reported that well-dispersed amorphous nanosilicas with particle size 70 nm (nSP70) penetrate skin and produce systemic exposure after topical application. These findings underscore the need to examine biological effects after systemic exposure to nanosilicas. The present study was designed to examine the biological effects. BALB/c mice were intravenously injected with amorphous nanosilicas of sizes 70, 100, 300, 1000 nm and then assessed for survival, blood biochemistry, and coagulation. As a result, injection of nSP70 caused fatal toxicity, liver damage, and platelet depletion, suggesting that nSP70 caused consumptive coagulopathy. Additionally, nSP70 exerts procoagulant activity in vitro associated with an increase in specific surface area, which increases as diameter reduces. In contrast, nSP70-mediated procoagulant activity was absent in factor XII-deficient plasma. Collectively, we revealed that interaction between nSP70 and intrinsic coagulation factors such as factor XII, were deeply related to nSP70-induced harmful effects. In other words, it is suggested that if interaction between nSP70 and coagulation factors can be suppressed, nSP70-induced harmful effects may be avoided. These results would provide useful information for ensuring the safety of nanomaterials (NMs) and open new frontiers in biological fields by the use of NMs.     

Mathematical Modeling and Exergy Analysis of Blast Furnace Operation With Natural Gas Injection

Blast furnace operation with natural gas (NG) injection is one of the effective measures to save energy, reduce CO₂ emission, and decrease environmental load for iron and steel industry. Numerical simulations on blast furnace operation with NG injection through tuyeres are performed in this paper by raceway mathematical model, multi‐fluid blast furnace model, and exergy analytical model. With increasing NG injection volume, the simulation results are shown as follows: (1) the theoretical flame temperature and bosh gas volume can be constant by decreasing blast volume and increasing oxygen enrichment. (2) The utilization rate of CO enhances while that of H₂ decreases. The proportion of H₂ in indirect reduction tends to be increased, which accelerates the reduction of burdens. The pressure drop shows that the permeability of blast furnace gets better. The blast furnace productivity is increased from 2.07 to 3.08 t · m^?3 · day^?1. The silicon content in hot metal is decreased from 0.26% to 0.05%. When BF operation with 125.4 kg · tHM^?1 NG injection, coke rate and carbon emission rate are decreased by 27.2% and 32.2%, respectively. (3) The thermodynamic perfection degree is increased from 88.40% to 90.50%, the exergy efficiency is decreased from 51.94% to 49.02% and the chemical exergy of top gas is increased from 4.69 to 6.22 GJ · tHM^?1. It is important to strengthen the recycling of top gas.     

Synergistic effect of D-glucose and epidermal growth factor display on dynamic behaviors of human epithelial cells

We investigated the synergistic effect of D-glucose and epidermal growth factor (EGF) display on the dynamic cellular behaviors of morphology and migration in a culture of human epithelial cells. The time-lapse observation revealed that the cells on the D-glucose/EGF-displayed substrate were endowed with enhanced migration, accompanied with periodic changes in morphology between round and stretched shapes. Immunofluorescence staining of phosphotyrosine PY20 and vinculin was conducted to determine the intracellular localization of phosphorylated tyrosine expression and focal contact formation, respectively. On the substrate displaying D-glucose and EGF, the cells exhibited increases in the levels of the expression of phosphorylated tyrosine and the formation of focal contacts not only at the cellular periphery but also in the cell body. These findings supported the consideration that the displayed D-glucose causes the cells to be in close contact with the surface via grasping glucose transporters on the cytoplasmic membrane.     

Ionization probability of secondary ions sputtered from Si(1 1 1) and Ge(1 1 1) surfaces

We have measured the energy distributions of the secondary ions sputtered from the Si(1 1 1) and Ge(1 1 1) surfaces and investigated the ionization probabilities of sputtered Si⁺ and Ge⁺ ions for clarifying their ionization mechanisms. The observed ionization probabilities depend on the velocity of Si⁺ and Ge⁺ ions. This velocity dependence can be successfully analyzed by a theoretical expression, which was proposed originally for the metal surfaces. This implies that the ionization mechanism of Si⁺ and Ge⁺ ions is the same as ions sputtered from the metal surface, i.e., the resonant electron transfer in the high velocity regime and the thermal excitation process in the low velocity regime. The difference in the ionization probability between Si⁺ and Ge⁺ ions is well explained by the difference in the band gap energy.     

Serial Changes of Serum Growth Factor Levels and Liver Regeneration after Partial Hepatectomy in Healthy Humans

This study aimed to investigate the associations of the serial changes of serum levels of various growth factors with liver regeneration after hepatectomy in healthy liver donors. Sixteen healthy liver donors who underwent conventional liver resection were included. Serum levels of various growth factors before hepatectomy and on postoperative day (POD) 1, 3, 5 and 7 were measured. Liver volume data calculated by multi-detector computed tomography using workstation. The ratio of remnant liver volume on POD 0 to liver volume before the operation was 51% ± 20%. The ratio of liver volume on POD 14 to liver volume on POD 0 were inversely correlated with remnant liver volume on POD 0 (r = −0.91). The ratio of liver volume on POD 14 to liver volume on POD 0 were significantly correlated with serum hepatocyte growth factor (HGF) levels on POD 1 (r = 0.54), serum leptin levels on POD 1 (r = 0.54), and serum macrophage colony-stimulating factor (M-CSF) levels on POD 5 (r = 0.76) and POD 7 (r = 0.80). These results suggest that early-phase elevation of serum levels of HGF, leptin and M-CSF may be associated with the acceleration of liver regeneration after hepatectomy in humans.     

Production of Hydrogen Storage Alloy of Mg2NiH4 by Hydriding Combustion Synthesis in Laboratory Scale

A laboratory scale production method for hydrogen storage alloy of Mg₂NiH₄ by hydriding combustion synthesis was investigated. In this study, cylinders of magnesium and nickel mixture powder, compressed at different pressures, and a powder mixture of metals, without the compressive treatment, were used as a raw material. The products were examined by X-ray diffraction (XRD) and scanning-electron microscopy (SEM). The XRD results indicated that pure Mg₂NiH₄ was simply obtained not only from the compressed cylinders, but also from the powder. There was no significant effect of the compressive pressure of the cylinder on the composition of the final products. However, SEM observations showed that the compressed sample and the powder are clearly different, in spite of the same product composition. The results also revealed a possibility of new production system of Mg₂NiH₄ using hydriding combustion synthesis, with many benefits of simple pretreatment, including: simple equipment, short operating time, high-quality product, and energy savings.     

Development of virtual and real-field construction management systems in innovative, intelligent field factory

In this study, we proposed a concept of virtual and real-field construction management systems (VR-Coms), which is integrated with virtual construction simulation, planning, scheduling, and performance management systems to evaluate productivity and safety in virtual simulated and real-field constructions. And, we built up a computational environment to develop the VR-Coms. The VR-Coms offer supporting modules for learning and discovering solutions with objective to manage construction at right speed with improved humanware and constructability. The configuration of VR-Coms is described. This paper also shows an application of agent theory to construction management.     

PVC、EPR和CSM材料辐照后热氧化降解的反应动力学分析

采用气相色谱定量测量了聚氯乙烯(PVC)、乙丙橡胶(EPR)和氯磺化聚乙烯(CSM)等线缆绝缘材料经辐照后在不同温度下热老化过程中的O2消耗量.对实验数据进行了反应动力学分析,发现线缆绝缘材料的热氧化降解反应为一级反应.同时获得了不同温度下的反应常数,并与根据Arrhenius 方程计算的理论结果进行了比较.