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마늘과 계란에서의 염소산염, 과염소산염 분석법 확립 및 검증
안희연 ( Hui-yeon Ahn ),이정훈 ( Jung-hoon Lee ),송민호 ( Min-ho Song ),유지우 ( Ji-woo Yu ),박건우 ( Geon-woo Park ),신지원 ( Ji-won Shin ),이지호 ( Ji-ho Lee ),금영수 ( Young-soo Keum ) 한국환경농학회 2023 한국환경농학회 학술대회집 Vol.2023 No.0
This study aims to assess the safety of chlorates and perchlorates in food. With the increasing consumption of chlorine-based disinfectants, investigations on the contamination of chlorates and perchlorates have become inevitable. Monitoring of chlorate and perchlorate levels, which can be generated during the production and manufacturing processes of food, was conducted to evaluate potential hazards. Continuous monitoring of chlorates and perchlorates is being carried out in other countries, but it is still limited in domestic settings. Therefore, standardization of detection methods for chlorates and perchlorates is necessary, along with the establishment of an integrated monitoring system throughout the production, distribution process, and consumption stages. In order to develop analytical methods for chlorates and perchlorates, two representative samples (garlic, eggs) were selected. LC-MS/MS was used with the Quppe (Quick Polar Pesticides) method to analyze Chlorate and Perchlorate which are polar substances. Among them, the instrumental conditions and extraction methods were established for garlic and eggs, and recovery tests were conducted at levels of 0.01 mg/kg and 0.1 mg/kg. Garlic is a food that is both a representative vegetable for roots and tuber vegetables and a detected food in EFSA (European Food Safe Authority) Chlorate monitoring. Eggs, on the other hand, are representative foods for the protein group as well as for semi-solid foods. To remove the proteins in galic and eggs, additional centrifugation step was employed. Finally, analytical method for the determination of chlorate and perchlorate was established and validated in representative samples of garlic and eggs.
Chung Joon-hui,Yeon Jehyeong,Seong Hoon Je,An Si-Hyun,Kim Da-Yeon,Yoon Younggun,Weon Hang-Yeon,Kim Jeong Jun,Ahn Jae-Hyung 한국미생물·생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.12
Plastic pollution has been recognized as a serious environmental problem, and microbial degradation of plastics is a potential, environmentally friendly solution to this. Here, we analyzed and compared microbial communities on waste plastic films (WPFs) buried for long periods at four landfill sites with those in nearby soils to identify microbes with the potential to degrade plastics. Fourier-transform infrared spectroscopy spectra of these WPFs showed that most were polyethylene and had signs of oxidation, such as carbon-carbon double bonds, carbon-oxygen single bonds, or hydrogen-oxygen single bonds, but the presence of carbonyl groups was rare. The species richness and diversity of the bacterial and fungal communities on the films were generally lower than those in nearby soils. Principal coordinate analysis of the bacterial and fungal communities showed that their overall structures were determined by their geographical locations; however, the microbial communities on the films were generally different from those in the soils. For the pulled data from the four landfill sites, the relative abundances of Bradyrhizobiaceae, Pseudarthrobacter, Myxococcales, Sphingomonas, and Spartobacteria were higher on films than in soils at the bacterial genus level. At the species level, operational taxonomic units classified as Bradyrhizobiaceae and Pseudarthrobacter in bacteria and Mortierella in fungi were enriched on the films. PICRUSt analysis showed that the predicted functions related to amino acid and carbohydrate metabolism and xenobiotic degradation were more abundant on films than in soils. These results suggest that specific microbial groups were enriched on the WPFs and may be involved in plastic degradation.
Hui-Dong Qian,Jung Tae Lim,Yang Yang,Jong-Woo Kim,Tian Hong Zhou,Su Yeon Ahn,Hankuk-Jeon,Kyung Mox Cho,Jihoon Park,Chul-Jin Choi 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
Rare-earth intermetallic compounds of R(Fe,M)12 (R = rare earth elements, M = transition metals) with ThMn12 structure have been known to be promising permanent magnetic materials since the 1980s. Recently, increasing rare earth price has pushed the industry to seek ways to reduce the R-content in the hard magnetic materials. In case, strong magnets with the ThMn12 type of structure received much attention. However, during the several tens of years, the research about ThMn12 magnetic materials was not made a breakthrough. As a turning point of the ThMn12-type Fe-rich compounds research, ThMn12-type Sm(Fe1-xCox)12 compound films with a saturation magnetization of 1.78 T, an anisotropy field of 12 T, and a Curie temperature of 586 °C, all of which are superior to those for Nd₂Fe14B, were successfully produced. However, it still has difficulty in stabilizing the unstable ThMn12 phase in magnetic powders and bulks. In previous research, the ThMn12 structure is also unstable and partial Fe atoms must be substituted with phase stabilizing element(s), such as Ti, V, Cr, Mn, Mo, W, Al, and Si, which results in magnetization reduction. So, decreasing magnetization or coercivity with the non-magnetic elements substitution is a new challenge for the ThMn12-type Sm(Fe1-xCox)12 compound research. Therefore, we have developed a new fabrication method to produce a high-density Sm(Fe0.8Co0.2)11Ti bulk with high purity and magnetic properties and investigated Si substitution or doping effects on this work"s magnetic and physical properties. The purity of the hard magnetic ThMn12 phase in the bulk magnet reached higher than 97 wt.%. The remanent magnetization and maximum energy product of the prepared Sm(Fe0.8Co0.2)11Ti bulk reached high values of 96.0 emu/g and 12.22 MGOe, respectively. The phase transformation behavior from amorphous to ThMn12 phase during heat treatment was systematically investigated by transmission electron microscopy. The magnetic properties and grain sizes of Sm(Fe0.8Co0.2)11Ti bulk magnets with different annealing times were shown in Fig. 1 (a). To investigate the effect of substituted elements in the ThMn12-type Fe-rich compounds and compare with the Ti substitution, Si was selected to dop into the ThMn12-type Fe-rich compounds. Sm(Fe0.8Co0.2)10Si₂ and Sm(Fe0.8Co0.2)11Ti+Six (x = 0, 0.5, and 1) ribbons were produced using a melt spinning method. The magnetic properties of the Sm(Fe0.8Co0.2)10Si₂ ribbons with different melt spinning speeds and the Sm(Fe0.8Co0.2)11Ti+Six ribbons with melt spinning speed of 39 m/s are shown in Fig. 1 (b). The maximum coercivity of the Sm(Fe0.8Co0.2)10Si₂ and Sm(Fe0.8Co0.2)11Ti+Six ribbons reached 1745 and 3140 Oe, respectively. The details of the fabrication procedure, microstructure, and magnetic properties of as mentioned compounds will be discussed. 〈그림 본문참조〉