The biological effect of radiofrequency (RF) fields remains controversial. We address this issue by examining whether RF fields can cause changes in gene expression. We used the pulsed RF fields at a frequency of 2.45 GHz that is commonly used in telecommunication to expose cultured human HL-60 cells. We used the serial analysis of gene expression (SAGE) method to measure the RF effect on gene expression at the genome level. We observed that 221 genes altered their expression after a 2-h exposure. The number of affected genes increased to 759 after a 6-h exposure. Functional classification of the affected genes reveals that apoptosis-related genes were among the upregulated ones and the cell cycle genes among the downregulated ones. We observed no significant increase in the expression of heat shock genes. These results indicate that the RF fields at 2.45 GHz can alter gene expression in cultured human cells through non-thermal mechanism.

A Mathematical model has been developed to analyze the transient three-dimensional and three-phase flow in an argon gas bottom stirring ladle with one and two off-centered porous plugs. Multiphase Volume of Fluid (VOF) method is used to simulate the behaviors of slag layer. Numerical simulation was conducted to clarify the transient phenomena of gas injection into the molten steel. When argon gas is injected into molten steel in a ladle, the gas rising passage is formed near the plug, and then bubbles are created in the molten steel. The rising gas bubbles impinge on the slag intermittently and break the slag layer to create the slag eye. Simultaneously, the wave at the slag-steel interface was formed and the wave frequency increases with the increase of argon gas flow rate for one off-centered plug case. The modeling simulations show that the diameter of slag eye changes from 0.43 to 0.81 m when the flow rate of argon gas varies from 100 to 300 NL/min for a 220 ton ladle. The relationship between non-dimensional areas of slag eye and the modified Froude number is in good agreement with the experimental data reported in literature. At the same total gas flow rate of 300 NL/min, the two-plugs generate two eyes with the diameters of around 0.6 m. Since the significant deformation of slag layer occurs during gas stirring operation, the thickness of slag becomes thin near the slag eye and thick near the ladle wall, respectively. The downward flow velocity of steel at the slag eye periphery may be affected significantly by flow rate of Ar gas. Therefore, when the downward flow velocity would be larger, the more emulsification of slag could be expected.KEY WORDS: ladle metallurgy; slag layer behavior; three-phase flow; mathematical model.

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During recent years, there has been great interest in exploring the potential for high-rate natural gas (NG) injection in North American blast furnaces (BFs) due to the fuel’s relatively low cost, operational advantages, and reduced carbon footprint. However, it is well documented that increasing NG injection rates results in declining raceway flame temperatures (a quenching effect on the furnace, so to speak), with the end result of a functional limit on the maximum injection rate that can be used while maintaining stable operation. Computational fluid dynamics (CFD) models of the BF raceway and shaft regions developed by Purdue University Northwest’s (PNW) Center for Innovation through Visualization and Simulation (CIVS) have been applied to simulate multi-phase reacting flow in industry blast furnaces with the aim of exploring the use of pre-heated NG as a method of widening the BF operating window. Simulations predicted that pre-heated NG injection could increase the flow of sensible heat into the BF and promote complete gas combustion through increased injection velocity and improved turbulent mixing. Modeling also indicated that the quenching effects of a 15% increase in NG injection rate could be countered by a 300K NG pre-heat. This scenario maintained furnace raceway flame temperatures and top gas temperatures at levels similar to those observed in baseline (stable) operation, while reducing coke rate by 6.3%.

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