In this study, nitrogen ions were implanted into STS 316L austenitic stainless steel by plasma immersion ion implantation (PIII) to improve the corrosion resistance. The implantation of nitrogen ions was performed with bias voltages of −5, −10, −15, and −20 kV. The implantation time was 240 min and the implantation temperature was kept at room temperature. With nitrogen implantation, the corrosion resistance of 316 L improved in comparison with that of the bare steel. The effects of nitrogen ion implantation on the electrochemical corrosion behavior of the specimen were investigated by the potentiodynamic polarization test, which was conducted in a 0.5 M H2SO4 solution at 70 oC. The phase evolution and texture caused by the nitrogen ion implantation were analyzed by an X-ray diffractometer. It was demonstrated that the samples implanted at lower bias voltages, i.e., 5 kV and 10 kV, showed an expanded austenite phase, γN, and strong (111) texture morphology. Those samples exhibited a better corrosion resistance.

To fabricate porous SiC-Si composites for heating element applications, both SiC powders and Si powders were mixed and sintered together. The properties of the sintered SiC-Si body were investigated as a function of SiC particle size and/or Si particle contents from 10 wt% to 40 wt%, respectively. Porous SiC-Si composites were fabricated by Si bonded reaction at a sintering temperature of 1650 oC for 80 min. The microstructure and phase analysis of SiC-Si composites that depend on Si particle contents were characterized using scanning electron microscope and X-ray diffraction. The electrical resistivity of SiC-Si composites was also evaluated using a 4-point probe resistivity method. The electrical resistivity of the sintered SiC-Si body sharply decreased as the amount of Si addition increased. We found that the electrical resistivity of porous SiC-Si composites is closely related to the amount of Si added and at least 20 wt% Si are needed in order to apply the SiCSi composites to the heating element.

Background : Gentinae Macrophyllae Radix is one of the traditional medicines originated from the roots of multiple plants, Gentiana macrophylla Pall., Gentiana straminea Maxim., Gentiana crassicaulis Duthie ex Burkill and Gentiana dahurica Fisch., in Gentianaceae. Multi-origin traditional medicine usually has adulteration problem based on the morphological similarity and/or misunderstanding the species. Therefore, accurate and reliable identification criteria to ensure drug safety and quality is necessary. Methods and Results : We collected four original species of Gentinae Macrophyllae Radix from plantations and markets in China and Korea. DNA barcoding with four barcoding markers (Internal Transcribed Spacer (ITS), rbcL, trnL intron, trnL-F intergenic sapcer) was performed. Intra-specific variation was observed in ITS nucleotide sequence however, successfully distinct four original species based on the nucleotide discrepancy while trnL intron has no difference. trnL-F intergenic spacer has two transitions(T→C and A→G) sites only in G. crassicaulis and rbcL shows one transition(C→T) site in G. dahurica and G. macrophylla. Phylogenetic relationship analysis of the Gentinae Macrophyllae Radix revealed two major clades – clade I including three groups, G. macrophylla, G. straminea and G. dahurica, and clade II including G. crassicaulis. This aspects was shown more clear with multi-region combined analysis. Conclusion : DNA barcoding will be accurate and powerful criteria for the analysis the origin of Gentinae Macrophyllae Radix. However, single region analysis might be deficient such as trnL intron, rbcL and trnL-F intergenic spacer results in this research. Multi-region combined analysis based on the multiregional DNA barcode markers will be overcome the disadvantage and also increase the precision.