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P. Dharmaiah, H.-S. Kim, K.-H. Lee and S.-J. Hong

Abstract

In this study, single phase polycrystalline Zn4Sb3 as well as 11 at.% Zn-rich Zn4Sb3 alloy having ε-Zn4Sb3 (majority phase) and Zn (minority phase) phases bulk samples produced by gas-atomization and subsequently consolidated by spark plasma sintering (SPS) process. The crystal structures were analyzed by X-ray diffraction (XRD) and cross-sectional microstructure were observed by the scanning electron microscopy (SEM). The internal grain microstructure of 11at.% Zn-rich Zn4Sb3 powders shows lamellar structure. Relative density, Vickers hardness and crack lengths were measured to investigate the effect of sintering temperature of Zn4Sb3 samples which are sintered at 653, 673 and 693 K. Relative density of the single phase bulk Zn4Sb3 sample reached to 99.2% of its theoretical density. The micro Vickers hardness of three different sintering temperatures were found around 2.17 – 2.236 GPa.

Open access

D.-J. Kim, K.M. Kim, J.H. Shin, Y.M. Cheong, E.H. Lee, G.G. Lee, S.W. Kim, H.P. Kim, M.J. Choi, Y.S. Lim and S.S. Hwang

Abstract

Fast water flow facilitates ferrous ion transport leading to flow accelerated corrosion (FAC) of carbon steel and the possibility of a large accident through a failure of a secondary pipe in a nuclear power plant. Ion transport is directly linked to oxide properties such as the thickness, chemical composition and porosity. This work deals with a precise observation of the cross section of the corroded specimen focusing on an oxide passivity and its thickness using SEM (scanning electron microscope) and TEM (transmission electron microscope) as well as an apparent weight loss and a surface observation for the specimens corroded using a rotating cylindrical electrode autoclave system in pure water of pH 7 at 150°C having dissolved oxygen below 1 ppb within a flow rate range of 0 to 10 m/s. The Cr content in steel was changed from 0.02 to 2.4 wt%. Increasing the Cr content in the alloy, the FAC rate and oxide thickness decreased. The oxide porosity tends to decrease with the Cr content and immersion time owing to the development of Cr containing oxide. The oxidation behavior is not changed with the immersion time.

Open access

Y.-P. Hong, H.-Y. Kwon, K.-S. Kim, K.-N. Hong and Y.-Y. Kim

Abstract

Level and distribution of genetic diversity in 8 populations of Japanese red pine in Korea were estimated using I-SSR variants. A total of 80 I-SSR variants were observed in the analyzed 150 individuals, which revealed DNA fingerprints-like individual specific amplicon profiles for all of them. Relatively higher level of genetic diversity within populations was observed in 8 populations of Japanese red pine (mean of 0.450) than in other tree species. From the results of AMOVA, majority of genetic diversity was allocated within populations (93.42%) resulting in a moderate degree of population differentiation (ΦST= 0.066). The observed distribution pattern of I-SSR variants among 8 populations was coincided with the typical patterns for the long-lived woody species. Genetic relationships among the populations, reconstructed by UPGMA and Neighbor- Joining methods, revealed 2 genetic groups. The populations of Gangwon-Uljin and Chungnam-Taean turned out to be the most closely related despite a distant location between them. The overall genetic relationships among the 8 populations, reconstructed by both methods, were not coincided with geographic distances. The discrepancy between genetic relationships and geographical distribution among the populations suggests that the analyzed populations might have undergone random changes in genetic composition due to some kinds of disturbances. Results obtained in this study suggests that more careful approach should be made in preparing strategy for gene conservation of Japanese red pine in Korea. More information on countrywide molecular population genetic status of Japanese red pine will be helpful to prepare more reasonable strategy for gene conservation of the species in the country.

Open access

H.P. Kim, M.J. Choi, S.W. Kim, D.J. Kim, Y.S. Lim and S.S. Hwang

Abstract

Effects of grain boundary morphologies on stress corrosion cracking (SCC) of Alloy 600 have been studied in 40% NaOH at 315°C using C-ring specimens. The configuration of the grain boundary and the intergranular carbide density were controlled by heat treatment. SCC tests were performed at +150 mV above the corrosion potential. The specimen with a serrated grain boundary showed higher SCC resistance than that with a straight grain boundary. This appears to be caused by the fact that the specimen with the serrated grain boundary has longer SCC path. SCC resistance also increased with intergranular carbide density probably due to enhanced relaxation of stress at intergranular carbide.

Open access

Y.-P. Hong, H.-Y. Kwon and I.-S. Kim

Abstract

To monitor the level and distribution pattern of genetic diversity in countrywide populations of Japanese red pines in Korea, 80 I-SSR variants were analyzed from 192 individuals in 11 populations. The previously reported data, obtained from the 8 populations of this species, were incorporated into the estimation of the population genetic statistics. Relatively higher level of genetic diversity was observed in 19 populations of Japanese red pines (mean of 0.453) than those in other tree species. From the results of AMOVA, majority of genetic diversity (92%) was allocated within populations, which brought about the moderate degree of population differentiation (ϕST= 0.08). Two genetic groups were observed from the dendrogram reconstructed by UPGMA. Overall correlation between genetic relationships and geographic affinity was inconsistent among the 19 populations. Some probable genetic disturbances, induced by either human interference or the natural process of regeneration for the species after devastation, might be responsible for the discrepancy between genetic relationships and geographical distribution of the populations. These results suggested that simple geographic or ecological grouping might not represent the genetic zone of the Korean populations of Japanese red pines, and that more careful approach should be made for designating in situ gene conservation of this species in Korea.

Open access

S.M. Shin, D.J. Shin, G.J. Jung, Y.H. Kim and J.P. Wang

Abstract

This study was focused on recycling process newly proposed to recover electrodic powder enriched in nickel (Ni) and rare earth elements (La and Ce) from spent nickel-metal hydride batteries (NiMH). In addition, this new process was designed to prevent explosion of batteries during thermal treatment under inert atmosphere. Spent nickel metal hydride batteries were heated over range of 300°C to 600°C for 2 hours and each component was completely separated inside reactor after experiment. Electrodic powder was successfully recovered from bulk components containing several pieces of metals through sieving operation. The electrodic powder obtained was examined by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) and image of the powder was taken by scanning electron microscopy (SEM). It was finally found that nickel and rare earth elements were mainly recovered to about 45 wt.% and 12 wt.% in electrodic powder, respectively.

Open access

Louise Hjort Nielsen, Sarah van Mastrigt, Randy K. Otto, Katharina Seewald, Corine de Ruiter, Martin Rettenberger, Kim A. Reeves, Maria Fransisca Rebocho, Thierry H. Pham, Robyn Mei Yee Ho, Martin Grann, Verónica Godoy-Cervera, Jorge O. Folino, Michael Doyle, Sarah L. Desmarais, Carolina Condemarin, Karin Arbach-Lucioni and Jay P. Singh

Abstract

With a quadrupling of forensic psychiatric patients in Denmark over the past 20 years, focus on violence risk assessment practices across the country has increased. However, information is lacking regarding Danish risk assessment practice across professional disciplines and clinical settings; little is known about how violence risk assessments are conducted, which instruments are used for what purposes, and how mental health professionals rate their utility and costs. As part of a global survey exploring the application of violence risk assessment across 44 countries, the current study investigated Danish practice across several professional disciplines and settings in which forensic and high-risk mental health patients are assessed and treated. In total, 125 mental health professionals across the country completed the survey. The five instruments that respondents reported most commonly using for risk assessment, risk management planning and risk monitoring were Broset, HCR-20, the START, the PCL-R, and the PCL:SV. Whereas the HCR-20 was rated highest in usefulness for risk assessment, the START was rated most useful for risk management and risk monitoring. No significant differences in utility were observed across professional groups. Unstructured clinical judgments were reported to be faster but more expensive to conduct than using a risk assessment instrument. Implications for clinical practice are discussed.