DGIST 전자도서관

비침습 샘플 DNA 분석으로 유추한 영월 한반도습지 내 멧돼지(Sus scrofa)의 생태 연구

2020.0환경영향평가, v.29, no.3, pp.230 - 238

본 연구는 비침습 샘플인 털을 이용하여 영월 한반도습지 내 서식하는 멧돼지(Sus scrofa)의 유전분석을 통하여 그들의 서식 생태를 유추하였다. 털 시료는 2018년 11월부터 2019년 5월까지 한반도습지(2.772km2) 내에서 비빔목 및 헤어트랩을 이용하여 수집하였다. 털 시료로부터 DNA를 추출하여 개체의 종과 성을 PCR을 통해 파악하였으며 6개의 마이크로새틀라이트 마커를 이용하여 개체 구분과 개체 간 유전적 근연관계를 유추하였다. 수집된 털 시료 중 총 16개의 털이 멧돼지의 시료였으며, 이는 암컷 7마리, 수컷 3마리의 10개체로부터 수집된 것임이 판명되었다. 이 10개체의 유전적 관계를 추정해 본 결과, 이들이 만들어내는 45쌍 중에 9쌍의 개체가 친족관계일 가능성이 높게 나타났다. 개체 쌍의 친족관계와 털 시료가 채집된 위치를 함께 고려하여 본 결과, 한반도습지 일대에서 서식하는 멧돼지는 암컷과 그 자손으로써 모계 가족단위로 생활하는 것으로 추정되며, 이는 기존에 알려진 멧돼지의 습성과도 일치하는 결과이다. 그러나 본 연구에 사용된 샘플과 마이크로새틀라이트 마커의 수가 제한적이므로 향후 추가적인 분석이 필요하다.

A Short Review on Interface Engineering of Perovskite Solar Cells: A Self-Assembled Monolayer and Its Roles

2020-02Solar Rrl, v.4, no.2, pp.1900251

Perovskite solar cells (PSCs) are considered as potential candidates for next-generation energy harvesting due to their advantages. A classic PSC has two charge transport layers (CTLs) above and below a perovskite layer, and these CTLs largely influence charge extraction and transport. Thus, an interface inevitably forms between the CTL and perovskite layer, and if the CTL and perovskite do not form a compact contact, these interfaces can become a nonradiative recombination center, which can degrade device efficiency and stability. Accordingly, interface engineering is considered an effective way to alleviate this issue. Herein, an overview of interface engineering methods on PSCs is provided, particularly with regard to types of self-assembled monolayers and their roles in device energy level alignment and passivation effects. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fully-automatic deep learning-based analysis for determination of the invasiveness of breast cancer cells in an acoustic trap

2020-06Biomedical Optics Express, v.11, no.6, pp.2976 - 2995

A single-beam acoustic trapping technique has been shown to be very useful for determining the invasiveness of suspended breast cancer cells in an acoustic trap with a manual calcium analysis method. However, for the rapid translation of the technology into the clinic, the development of an efficient/accurate analytical method is needed. We, therefore, develop a fully-automatic deep learning-based calcium image analysis algorithm for determining the invasiveness of suspended breast cancer cells using a single-beam acoustic trapping system. The algorithm allows to segment cells, find trapped cells, and quantify their calcium changes over time. For better segmentation of calcium fluorescent cells even with vague boundaries, a novel deep learning architecture with multi-scale/multi-channel convolution operations (MM-Net) is devised and constructed by a target inversion training method. The MM-Net outperforms other deep learning models in the cell segmentation. Also, a detection/quantification algorithm is developed and implemented to automatically determine the invasiveness of a trapped cell. For the evaluation of the algorithm, it is applied to quantify the invasiveness of breast cancer cells. The results show that the algorithm offers similar performance to the manual calcium analysis method for determining the invasiveness of cancer cells, suggesting that it may serve as a novel tool to automatically determine the invasiveness of cancer cells with high-efficiency. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

Detection of antibiotic-resistant Escherichia coli from the feces of the Oriental magpie nestlings

2020-06한국조류학회지, v.27, no.1, pp.3 - 9

Appearance of drug-resistant bacteria is one of the most important issues worldwide that greatly impact both humans and wildlife. Previous studies proved that wild birds inhabiting in urban areas can be exposed to antibiotic-resistant bacteria, whose resistance might be derived from the antibiotics widely used in the medical facilities and farming areas. In these environments, wild birds can be a spreading vector for the resistance genes among the environmental bacteria. The Oriental magpie (Pica serica) is one of the wildlife species well known for high adaptability to urban habitats. Therefore, one can predict that the Oriental magpie is a potential carrier of the antibiotic-resistant microbes. In this study, we conducted disk susceptibility test and PCRs for antibiotic resistance genes and detected Escherichia coli carrying resistance to three antibiotic agents from the feces of 10 hatchlings and fledglings of the Oriental magpie living in the campus of Seoul National University (SNU). In addition, some individuals showed multi drug resistance. Our results show that nestlings and fledglings of the Oriental magpie are exposed to Escherichia coli harboring resistance to one or more antibiotic agents. In order to understand the origin and the transfer mechanisms of these microbes, more thorough investigation on the exposure of wildlife species living in a range of urban-rural gradients to the antibiotic resistant microbes should be conducted.

Improving the ionic conductivity of Li1-xAlxGe2-x(PO4)(3) solid electrolyte for all-solid-state batteries using microstructural modifiers

2020-10Ceramics International, v.46, no.14, pp.23200 - 23207

Although lithium-ion batteries are recognized as the most suitable power source for electric vehicles, they continue to pose a severe safety issue mainly arising from the use of flammable electrolytes. To improve safety, various types of solid electrolytes are explored as potential alternatives due to their non-flammability, high stability, and a wide electrochemical window. In particular, Li1+xAlxGe2-x(PO4)3 (LAGP) has many strengths such as a high total Li+ conductivity and low sensitivity against Li metal anode. Despite these benefits, practical use of LAGP is hindered by a significant loss of total Li+ conductivity due to large grain boundary resistance and interfacial resistance. As an effective way to increase the total Li+ conductivity of LAGP, we propose microstructural engineering with the structural modifiers (B2O3 and Bi2O3) with different functionalities. During synthesis, B2O3 facilitates the grain growth of LAGP, thereby reducing the number of grain boundaries. At the same time, Bi2O3 promotes the densification of LAGP with the advancement of its structural integrity. As a result of synergetic effect, the total Li+ conductivity of LAGP can be effectively improved at room temperature. Furthermore, we demonstrate positive effects of the tailored microstructure of LAGP on the electrochemical performance of all-solid-state batteries. © 2020 Elsevier Ltd and Techna Group S.r.l.

Efficient degradation of antibiotics in different water matrices through the photocatalysis of inverse opal K-g-C3N4: Insights into mechanism and assessment of antibacterial activity

2020-11Chemical Engineering Journal, v.400, pp.125902

The efficient degradation of fluoroquinolone antibiotics and the reduction of their antimicrobial activity were achieved in different water matrices through the photocatalysis of inverse opal potassium-doped carbon nitride (IO K-CN). The IO K-CN photocatalyst with optimum doping ratio of potassium performed much better than bulk carbon nitride and pure inverse opal carbon nitride for removing fluoroquinolone antibiotics, such as levofloxacin (LVX) and norfloxacin (NOR). The remarkably narrowed band gap resulting from potassium doping and the unique properties of the inverse opal construction jointly contributed to enhancing the activity of the photocatalyst. A possible mechanism and degradation pathway for LVX was proposed on the basis of a series of characterizations including electron spin resonance (ESR) experiments, and liquid chromatography-mass spectrometry (LC-MS) analysis. Meanwhile, the byproducts during the LVX photocatalytic degradation were shown to have much lower sterilization effect, implying that the toxicity and the potential risk of LVX were excellently reduced. The potential application for the treatment of antibiotic-containing wastewater was indicated by the excellent treatment efficiency and favorable durability of this photocatalyst. © 2020 Elsevier B.V.

Boosting the Performance of Solid Oxide Electrolysis CellsviaIncorporation of Gd(3+)and Nd(3+)Double-doped Ceria

2020-12Fuel Cells, v.20, no.6, pp.712 - 717

The solid oxide electrolysis cell (SOEC) and its developement are in an increasing focus, because of its high efficiency and eco-friendliness in storing energy by converting electrical energy into hydrogen. Recently, research has been conducted to decrease the operation temperature of SOECs below 750 degrees C to overcome high system costs and rapid degradation rate at high operation temperatures. Although La0.6Sr0.4Co0.2Fe0.8O3-delta(LSCF) is a promising oxygen electrode for SOEC, when the operating temperature is reduced, the reaction kinetics of the LSCF oxygen electrode is significantly decreased due to high activation energy of the oxygen ion transport. To address this issue, we developed a composite oxygen electrode of LSCF combined with Gd and Nd double doped ceria (GNDC). Due to excellent oxygen ion transport nature of GNDC, the SOEC with the LSCF-GNDC oxygen electrode yielded impressive current density of similar to 1,174 mA cm(-2)at 1.3 V at 750 degrees C along with excellent stability. These results demonstrated that the novel LSCF-GNDC composite is promising as an efficient and durable oxygen electrode for SOEC applications.

Nucleophilic reactivity of a mononuclear cobalt(iii)-bis(tert-butylperoxo) complex

2020-08Chemical Communications, v.56, no.66, pp.9449 - 9452

A mononuclear cobalt(III)-bis(tert-butylperoxo) adduct (Co-III-((OOBu)-Bu-t)(2)) bearing a tetraazamacrocyclic ligand was synthesized and characterized using various physicochemical methods, such as X-ray, UV-vis, ESI-MS, EPR, and NMR analyses. The crystal structure of the Co-III-((OOBu)-Bu-t)(2)complex clearly showed that two (OOBu)-Bu-t ligands bound to the equatorial position of the cobalt(iii) center. Kinetic studies and product analyses indicate that the Co-III-((OOBu)-Bu-t)(2)intermediate exhibits nucleophilic oxidative reactivity toward external organic substrates.

Mechanistic insight into hydroxamate transfer reaction mimicking the inhibition of zinc-containing enzymes

2020-09Chemical Science, v.11, no.33, pp.9017 - 9021

A hydroxamate transfer reaction between metal complexes has been investigated by a combination of experimental and theoretical studies. A hydroxamate-bound cobalt(ii) complex bearing a tetradentate macrocyclic ligand, [Co-II(TBDAP)(CH3C(-NHO)O)](+)(1), is prepared by the reduction of a hydroximatocobalt(iii) complex with a biological reductant. Alternatively,1is accessibleviaa synthetic route for the reaction between the cobalt(ii) complex and acetohydroxamic acid in the presence of a base.1was isolated and characterized by various physicochemical methods, including UV-vis, IR, ESI-MS, and X-ray crystallography. The hydroxamate transfer reactivity of1was examined with a zinc complex, which was followed by UV-vis and ESI-MS. Kinetic and activation parameter data suggest that the hydroxamate transfer reaction occursviaa bimolecular mechanism, which is also supported by DFT calculations. Moreover,1is able to inhibit the activity against a zinc enzyme,i.e., matrix metalloproteinase-9. Our overall investigations of the hydroxamate transfer using the synthetic model system provide considerable insight into the final step involved in the inhibition of zinc-containing enzymes.

There is No test-retest reliability of brain activation induced by robotic passive hand movement: A functional NIRS study

2020-10Brain and Behavior, v.10, no.10, pp.e01788

Introduction: The basic paradigm of rehabilitation is based on the brain plasticity, and for promoting it, test–retest reliability (TRR) of brain activation in which certain area of the brain is repeatedly activated is required. In this study, we investigated whether the robotic passive movement has the TRR of brain activation. While active training has been shown to have TRR, but there still have been arguments over the TRR by passive movement. Methods: In order to test TRR, 10 repetitive sessions and various intervals (1 day, 3 days, 7 days, 23 days, 15 min, and 6 hr) were applied to five subjects, which had the same statistical power as applying two sessions to 50 subjects. In each session, three robot speeds (0.25, 0.5, and 0.75 Hz) were applied to provide passive movement using the robot. The fNIRS signal (oxy-Hb) generated in the primary sensorimotor area (SM1) was measured on a total of 29 channels. At this time, we used activation maps and intraclass correlation coefficient (ICC) values to examine the TRR and the effect of robot speeds and intervals on TRR. Results: As a result, activation maps showed prominent variation regardless of robot speeds and interval, and the ICC value (=0.002) showed no TRR of brain activation for robotic passive movement. Conclusion: The brain activation induced by the robotic passive movement alone has very poor TRR, suggesting that further enhancement is required to strengthen the TRR by complementing active user engagements. © 2020 The Authors. Brain and Behavior published by Wiley Periodicals LLC.

The (α, β)-Precise Estimates of MTBF and MTTR: Definition, Calculation, and Observation Time

ACCEPTIEEE Transactions on Automation Science and Engineering

The mean time between failures (MTBF) and mean time to repair (MTTR) of manufacturing equipment (e.g., machines) are used in every quantitative method for production systems performance analysis, continuous improvement, and design. Unfortunately, the literature offers no methods for evaluating the smallest number of up- and downtime measurements necessary and sufficient to calculate reliable estimates of these equipment characteristics. This article is intended to provide such a method. The approach is based on introducing the notion of (α, β)-precise estimates, where α characterizes the estimate's accuracy and β its probability. Using this notion, this article evaluates the critical number, n* (α,β), of up- and downtime measurements necessary and sufficient to calculate (α, β)-precise estimates of MTBF and MTTR. In addition, this article derives a probabilistic upper bound of the observation time required to collect n* (α,β) measurements. IEEE

이공계 대학생의 사회적 책임감 함양을 위한 ENACT 모형의 개발과 교육적 함의

2020-11공학교육연구, v.23, no.6, pp.3 - 16

This study aims to introduce the ENACT model, which is a systematic teaching-learning model for cultivating social responsibility of science and engineering college students, and to discuss its educational implications. For the development of the ENACT model, we conducted extensive literature reviews on RRI, STEM education, and science and technology studies (STS). In addition, we examined exemplary overseas education programs emphasizing social responsibility of scientists/engineers and citizens. The ENACT model consists of five steps; 1) Engage in SSIs, 2) Navigate SSIs, 3) Anticipate consequences, 4) Conduct scientific and engineering practice, and 5) Take action. This model links Socioscientific Issues (SSI) education with engineering education, dividing the major elements of social responsibility education for scientists and engineers into the dimensions of epistemology and praxis, and reflected them in the model. This effort enables science and engineering college students to pursue more responsible and sustainable development by carrying out the responsible problem-solving process based on an understanding of the nature of science and technology. We plan to implement ENACT model based programs for science and engineering college students and to examine the effects.