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석면함유 슬레이트 지붕 물받이 퇴적물 중 석면 섬유 함유율
임지현,한솔민,김현석,신유민,박시은,허정윤,김민영,장봉기 순천향대학교 기초과학연구소 2022 순천향자연과학연구 논문집 Vol.28 No.1,2
This study attempted to determine the degree of asbestos release from the aging slate roof by comparing the asbestos content in the slate roof rain gutter with a colored steel plate (tin plate) over the slate roof. Four slate roof houses located in Haengmok-ri, Asan-si, Chungcheongnam-do, and one house constructed with a colored steel plate on the slate roof were selected to collect the sediment of the roof rain gutter. The asbestos fiber content was calculated by a point counting method using a polarization microscope after pretreatment with conversion treatment and hydrochloric acid treatment. The average asbestos content of the four slate roof rain gutter were 1.89%. However, asbestos was not detected in the Slate covering roof rain gutter, which were constructed on the slate roof. Asbestos fiber content was the highest at 2.89% in the slate roof rain gutter installed in 1976, followed by 2.44% in 1953. From the above results, it is necessary to minimize secondary damage as asbestos fibers released from slate roof houses to the surrounding atmosphere or leaked from slate roofs as rainwater may cause soil pollution and seriously affect residents' health. Although covering with colored steel plates (tin plates) has been shown to prevent the leakage of asbestos fibers to some extent, it is believed that a policy alternative to remove the slate roof as soon as possible is needed to solve the fundamental problem.
Plant Regeneration from Protoplast Isolated from Embryogenic Cells of Angelica gigas
Han-Sol Lee,So-Young Park,Jong-Eun Han,Jae-Heyuk Shin,Heyuk-Jun Kwon 한국원예학회 2021 한국원예학회 학술발표요지 Vol.2021 No.10
Protoplasts, cells lacking the polysaccharide wall, allow a technical complexity in cell-based study of plant. This study was carried out to investigate the effect of various factors on embryogenic cell-derived protoplast cultures to establish a reliable regeneration protocol in Angelica gigas. Firstly, the method of protoplast isolation was stablished by determination of enzyme solution. In next step, protoplast culture was conducted by investigation of the basal media, growth regulators, culture methods [liquid culture, sieving, thin-alginate layer (TAL) method]. Finally, micro-calli induced from protoplast cultures were transferred to hormone-free medium for the further development. High yield of the protoplast was successfully isolated from embryogenic cells, and those were classified into 4 groups according to their size. The highest frequency of cell division was achieved at 7 h of enzyme incubation treatment and the MS medium. The initial cell division was firstly observed in the Group 1(< 20 μm). As the culture period passed, the large groups gradually increased, and the small groups tend to decrease in number. The largest micro-calli were observed in 0.1 - 0.5 mg·L-1 2,4-D single treatments while the vigorous cell division was observed in the medium containing 1.0 mg·L<SUP>-1</SUP> 2,4-D, 0.5 mg·L<SUP>-1</SUP> kinetin. Among three culture method, the TAL showed the highest frequency of cell division compared to other methods. After somatic embryo induction and then shoot induction, the protoplast-derived embryos produced plantlets with high efficiency from TAL. Somatic embryos developed into well-rooted plants on hormone-free MS medium. In study, high frequency cell divisions were occurred from small in size, small vacuoles and cytoplasm-rich protoplasts, and these protoplasts were considered to embryonic stem cells. In future studies, we intend to analyze the differential gene expression to identify the protoplast types and molecular changes during protoplast recovery and development into plants.
Rewritable, Printable Conducting Liquid Metal Hydrogel
Park, Jung-Eun,Kang, Han Sol,Baek, Jonghyek,Park, Tae Hyun,Oh, Seunghee,Lee, Hyungsuk,Koo, Min,Park, Cheolmin American Chemical Society 2019 ACS NANO Vol.13 No.8
<P>The development of high-performance printable electrical circuits, particularly based on liquid metals, is fundamental for device interconnection in flexible electronics, motivating numerous attempts to develop a variety of alloys and their composites. Despite their great potential, rewritable and printable electronic circuits based on liquid metals are still manufactured on demand. In this study, we demonstrate liquid metal-based hydrogels suitable for rewritable, printable electrical circuits. Our liquid metal hydrogels are based on sedimentation-induced composites of eutectic gallium-indium (EGaIn) particles in poly(ethylene glycol) diacrylate (PEGDA). The EGaIn particles are vertically phase-segregated in the PEGDA. When a composite surface with high EGaIn content is gently scratched, the surface covering PEGDA is removed, followed by the rupture of the native oxide layers of the particles, and the exposed EGaIn becomes conductive. The subsequent water-driven swelling of PEGDA on the scratched surface completely erases the conductive circuit, causing the system to reset. Our friction-responsive liquid metal hydrogel exhibits writing-erasing endurance for 20 cycles, with a dramatic change in the electrical resistance from metal (∼1 Ω) to insulator (∼10<SUP>7</SUP> Ω). By employing surface friction pen printing, we demonstrate mechanically flexible, rewritable, printable electrical conductors suitable for displays.</P> [FIG OMISSION]</BR>
Han Sol Kim,Hongliang Li,Hye Won Kim,Sung Eun Shin,Mi Seon Seo,Jin Ryeol An,Kwon-Soo Ha,Eun-Taek Han,Seok-Ho Hong,Il-Whan Choi,Grace Choi,Dae-sung Lee,Won Sun Park 대한생리학회-대한약리학회 2017 The Korean Journal of Physiology & Pharmacology Vol.13 No.1
We investigated the inhibitory effect of escitalopram, a selective serotonin reuptake inhibitor (SSRI), on voltage-dependent K<sup>+</sup> (Kv) channels in freshly separated from rabbit coronary arterial smooth muscle cells. The application of escitalopram rapidly inhibited vascular Kv channels. Kv currents were progressively inhibited by an increase in the concentrations of escitalopram, suggesting that escitalopram inhibited vascular Kv currents in a concentration-dependent manner. The IC<sub>50</sub> value and Hill coefficient for escitalopram-induced inhibition of Kv channels were 9.54±1.33 µM and 0.75±0.10, respectively. Addition of escitalopram did not alter the steady-state activation and inactivation curves, suggesting that the voltage sensors of the channels were not affected. Pretreatment with inhibitors of Kv1.5 and/or Kv2.1 did not affect the inhibitory action of escitalopram on vascular Kv channels. From these results, we concluded that escitalopram decreased the vascular Kv current in a concentration-dependent manner, independent of serotonin reuptake inhibition.