No abstract

Halobacterium salinarum is an extremely halophilic archaea, which is able to live in highly saline environments. In a recent study, several halophilic archaea were found to have the ability to biodegrade organic hydrocarbon pollutants, but protein information regarding hydrocarbon degradation and tolerance in halophilic archaea has been relatively rare. In this study, the protein expression profile of H. salinarum cultured under different diesel concentrations (0, 2 and 4%) was investigated by two-dimensional gel electrophoresis. Proteins which increased their expression levels in diesel media were identified using matrix-assisted laser desorption/ionization-time of flight and electrospray ionization-tandem mass spectrometry analysis. Among these, a protein spot (named D3UPCA) which was up-regulated about nine-fold and found to have COG3388, an uncharacterized protein conserved in archaea, was selected in order to further characterize its functions. The D3UPCA coding gene (named d3upca) was cloned and expressed in Escherichia coli, and purified by the glutathione-S-transferase-fusion method. The function of the protein was estimated using various bioinformatics tools and was predicted to be related to the regulation of transcription and/or translation of genes needed to tolerate stresses associated within the presence of diesel oil.

Recently, potholes have drawn attention as a major pavement distress. In Korea and other countries, slaked lime is used to improve the moisture resistance of asphalt mixtures in order to prevent road damages by moisture. The present study was conducted to evaluate the moisture resistance of asphalt mixtures containing air-cooled slag having a chemical composition similar to that of slaked lime. To evaluate the moisture resistance of asphalt mixtures containing air-cooled slag, a moisture resistance test that is applied in Korea and other countries was performed. The evaluation of the moisture resistance of asphalt mixtures containing air-cooled slag showed that the coverage ratio measured by the dynamic immersion test was about 80%, which was similar to that of the asphalt mixtures containing slaked lime. In the case of the indirect tensile strength test, the TSR value tends to increase with increasing the air-cooled slag content of the specimens. But the indirect tensile strength was slightly lower in the specimen containing 3% air-cooled slag. The Hamburg wheel tracking test showed that the moisture resistance of the specimens produced in a laboratory and in a plant was good but that of the specimen containing 3% air-cooled slag was slightly lower. The laboratory experiment performed in the present study showed that the moisture resistance was improved by the addition of air-cooled slag, which has a similar composition with slaked lime, to asphalt mixtures. However, when the entire filler of the asphalt mixture was replaced by air-cooled slag, the strength was slightly decreased, indicating that an appropriate amount of air-cooled slag should be added. The applicability of air-cooled slag to asphalt pavement material may need to be studied through a microstructure analysis and a long-term pavement performance test to investigate the mechanism more accurately.

No abstract

No abstract