Removal of filamentous algae by positively charged bubble flotation : a comparative study with spherical/ spherical-like shapes

Bui Thi Thuy 서울대학교 대학원 2014 국내석사

Abstract Removal of filamentous algae by positively charged bubble flotation: a comparative study with spherical/ spherical-like shapes Bui Thi Thuy Dept. of Civil and Environmental Engineering College of Engineering Seoul National University The objective of this study was to compare removals of filamentous algae with spherical/ spherical-like algae during charged bubble flotation process, optimize operation conditions for better removal of filamentous algae and observe the change of algal morphology to identify mechanisms underlying the efficiency of flotation with positively charged bubbles. Three selected shapes in this research are spherical (Microcystis sp.), oval (Chlamydomonas angulosa) and filamentous algae (Phormidium sp.), cultured in the laboratory under certain cultivated conditions. Physical properties of three differing algae were understood as morphology, size distribution and zeta potential in various pH. Under pH conditions of 4.5~7, all algae species showed negative charges; -10 mV for filamentous shape, ~ -20 mV for oval shape and ~ -40 mV for spherical shape. The size of these shapes ordered increasingly as spherical < oval < filamentous algae. Removal of differing algal shapes were conducted by the batch dissolved air flotation (BDAF) method with bubble generation from saturated pressure of 6 bars, in the presence of aluminium at 30% of bubble rate. Filamentous algae presented the greatest results (i.e. 86% for cell removal and ~93% for chlorophyll a reduction) when comparing to spherical/ spherical-like algae (i.e. ~75% for cell removal and ~80% for chlorophyll a reduction). For better filamentous algal removal, the optimum operational condition was also investigated. Bubbles were generated at two levels of saturated pressure (3 bars, 6 bars) and measured at different bubble concentrations (10%, 20%, and 30%), in the absence and presence of coagulants. Bubbles averaging 30 µm and 45 µm in size were observed at zeta potentials of -30 mV~+27 mV. We obtained optimal filamentous algal removal with positively charged bubble flotation at a 30% bubble rate at >16 mV and a bubble size of 30 µm, with removal of up to 85% and 93% of cells and chlorophyll a, respectively. Also, by positively charged bubble flotation, only filamentous cell changed its size arrangement and promoted spherically or ovally being to adopt with the stress environment. We also demonstrated the efficacy of using positively charged bubbles to remove filamentous cells and the importance of positively charged bubbles in the rarely reported interaction between bubbles and chain-like algae. Keywords: Bubble generation conditions, chain-like algae, filamentous algae removal, flotation, positively charged bubble, zeta potential Student number: 2012-23968

Rad51-associate protein 1 interacts with NS5A and regulates hepatitis C virus propagation : C형간염바이러스 NS5A 단백질과 결합하는 RAD51AP1 세포 단백질에 관한 연구

Nguyen Thuy Thuy Tram 한림대학교 대학원 2017 국내석사

Background: The life cycle of hepatitis C virus (HCV) is highly dependent on host cellular proteins for its propagation. In order to identify the cellular factors involved in HCV propagation, we performed protein microarray assay using the HCV NS5A protein as a probe. Of ~9,000 human cellular proteins immobilized in a microarray, approximately 90 cellular proteins were identified as NS5A interacting partners. Of these candidates, RAD51-associated protein 1 (RAD51AP1), which is a dsDNA, ssDNA and RNA binding protein is selected for further study. It is a member of the multiprotein complexes postulated to carry out homologous recombination and DNA repair in mammalian cells. RAD51AP1 synergizes with UAF1 to enhance RAD51-mediated homologous DNA pairing specifically by promoting the assembly of the synaptic complex, in which single-stranded DNA derived from the nucleolytic processing of a primary lesion is homologously aligned with a duplex molecule. RAD51AP1 knockdown cells tend to hypersensitizes to DNA-damaging agents and prone to chromatid breaks. Methods: By using microarray screening, we identified RAD51AP1 as one of 90 NS5A interacting partners. Results: We confirm that NS5A directly bounds to RAD51AP1 and further demonstrate that NS5A can enhance the protein level, but not RNA level of RAD51AP1 through ubiquitin-proteosome pathway. NS5A also disrupts the interaction between RAD51AP1 and UAF1, therefore impairs the trimeric complex of RAD51, RAD51AP1 and UAF1. Silencing of RAD51AP1 inhibits viral infection, whereas overexpression of RAD51AP1 increases HCV late step. Importantly, RAD51AP1 plays a role in the assembly step by acting as a bridge to transfer HCV RNA to NS5A. Conclusions: Our findings provide insights into the function of RAD51AP1 in the life cycle as well as the pathogenesis of HCV.

Flood risk assessment in Binh Thanh district : Ho Chi Minh city

Tran, Thuy Nhung 서울시립대학교 2017 국내석사

Flood events are occurring regularly in Ho Chi Minh City, in which Binh Thanh is one of the most seriously flooded districts. Due to the unpredictability of climate in recent years, extreme weather events have caused many flood hazards in the area. Meanwhile, the demand for urban development is leading to population growth and demand for land even in flood-prone areas. This study aims to assess the flood risk in Binh Thanh District through the analysis of vulnerability with multi-scale. The results indicate the impact of the vulnerability indicators on flood in Binh Thanh on the vulnerability map. These results will support governments as well as investors with the sustainable planning and mitigating the effects of flood. The research uses GIS application to build a spatial distribution map of vulnerability in Binh Thanh District with the database of satellite image data, census data, as well as experts’ interviews. Keywords: Flood, Climate change, Flood risk, Flood Vulnerability, Ho Chi Minh City, Binh Thanh District, GIS, Expert Interviews 정기적으로 홍수가 발생하는 호치민에서 홍수 피해가 가장 심한 지역은 빈탄이다. 최근 예측이 불가능한 기후와 극단적 날씨가 홍수 피해의 가장 큰 원인으로 파악된다. 하지만 도시 개발에 대한 수요가 인구 증가로 이어지고, 심지어 홍수 지역에서조차 토지 수요가 증가하고 있다. 이 연구의 목적은 다중 축척에 근거한 취약성 분석을 통해 빈탄 지구의 홍수 위험을 평가하는 것이다. 그 연구 결과는 취약성 지표가 빈탄의 홍수에 주는 영향을 보여줄 뿐 아니라, 지속가능한 계획 수립과 홍수 영향의 완화를 통해 정부 및 투자자에 도움을 줄 것으로 예측된다. 이 연구에서는 빈탄 지구의 취약성 공간분포지도를 만들기 위해, 위성 이미지 데이터, 인구 데이터, 전문가 인터뷰뿐 아니라 GIS도 사용하였다. 주요 용어: 홍수, 홍수 위험, 홍수 취약성, 기후 변화, 호치민 시, 빈탄 지구, GIS, 전문가 인터뷰

Vapor-phase polymerized thin films and seeding-polymerized nanofibers membranes of Poly(3,4-ethylenedioxythiophene) for optoelectronic applications

Truong, Thuy Le 성균관대학교 2007 국내석사

As with other conducting polymers, poly(3,4-ethylenedioxythiophene) is considered as a promising material for optoelectronic devices. In most of those optoelectronic applications as buffer or electrode layers, the surface and/or interface of PEDOT coating layer substantially influences mobility, quantum efficiency and stability of charge carriers as well as assembled devices. Previous studies show that the effect of dielectric surface on charge mobility is due to surface-induced morphology of polythiophene. In this sense, the vapor-phase polymerization (VPP) of PEDOT is a promising technology in various optoelectronic applications to provide a thin, uniform, and highly-conductive PEDOT coating. However, not only the conductivity enhancement but also the surface morphology of PEDOT VPP should be further explored to be adopted in optoelectronic device. In addition, the conductivity of the PEDOT coating in relation with surface smoothness and transparency should be identified to be used as thin film coating in optoelectronic devices. In this study, our overall goal is to produce well-characterised PEDOT film for optoelectronic applications by the formation of robustly nanostructured PEDOT coating. The surface morphology of PEDOT was investigated in the vapor-phase polymerization of the thiophene monomer on a flexible polyethyleneterphthalate (PET) substrate film. The PET surface was modified with ethylene diamine maintaining the surface roughness within 2 nm to create amine and amide groups for the enhanced hydrophilic interaction with Fe(III)-tosylate (Fe(OTs)3) and for the desirable hydrogen bonding with thiophene monomer as well as PEDOT. Polymerization rate was reduced by incorporating pyridine as a reaction retardant to control the surface roughness and conductivity of PEDOT thin films. The optimal conditions of pyridine and glycerol were found at a pyridine/Fe(OTs)3 molar ratio of 0.5 and a glycerol concentration of 4~5 wt%, respectively, providing the conductivity up to 500 S/cm and the surface roughness < 2 nm.

Studies on tryptophan dependent and independent secretion mechanisms of tryptophanyl-tRNA synthetase: Pathophysiological implications for innate immune responses

NGUYEN THUY THUY TRAM 가천대학교 대학원 2023 국내박사

While cytoplasmic tryptophanyl-tRNA synthetase (WARS1) ligates tryptophan (Trp) to its cognate tRNAs for protein synthesis, it also acts as an innate immune activator in extracellular space. However, its secretion mechanism remains elusive. Here, we report that in response to stimuli WARS1 can be secreted via two distinct pathways: via Trp-dependent secretion of naked protein and via Trp-independent plasma membrane-derived vesicles (PMVs). In the direct pathway, Trp binding to WARS1 induces a “closed” conformation, generating a hydrophobic surface and basic pocket. The Trp-bound WARS1 then binds stable phosphatidylinositol (4,5)-biphosphate and inner plasma membrane leaflet, passing across the membrane. In the PMV-mediated secretion, WARS1 recruits calpain 2, which is activated by calcium. WARS1 released from PMVs induces inflammatory responses in vivo. These results shed a light into the WARS1’s secretion mechanisms and improve our understanding how WARS1 is involved in the control of local and systemic inflammation upon infection.

Irisin attenuates hepatic stellate cell activation and liver fibrosis in bile duct ligation mice model and improves mitochondrial dysfunction

Lai Thuy Linh 강원대학교 대학원 2024 국내석사

Background: Liver fibrosis is a common outcome of chronic liver disease and is primarily driven by hepatic stellate cell (HSC) activation. Irisin, a myokine released during physical exercise, is beneficial for metabolic disorders and mitochondrial dysfunction. This study aimed to discover the effects of irisin on liver fibrosis in HSCs, a bile duct ligation (BDL) mouse model, and the associated mitochondrial dysfunction. Methods: In vitro experiments utilized LX-2 cells, a human HSC line, stimulated with transforming growth factor beta 1 (TGF-β1) which is a major regulator of HSC fibrosis, with or without irisin. Mitochondrial function was assessed using mitochondrial fission markers, transmission electron microscopy, mitochondrial membrane potential, and adenosine triphosphate production. In vivo, liver fibrosis was induced in mice via BDL, followed by daily intraperitoneal injections of irisin (100 µg/kg/day) for 10 days. Results: In vitro, irisin mitigated HSC activation and reduced reactive oxygen species associated with the TGF-β1/Smad signaling pathway. Irisin restored TGF-β1-induced increases in fission markers (Fis1, p-DRP1) and reversed the decreased expression of TFAM and Sirt3. Additionally, irisin restored mitochondrial membrane potential and adenosine triphosphate production lowered by TGF-β1 treatment. In vivo, irisin ameliorated the elevated liver-to-body weight ratio induced by BDL and alleviated liver fibrosis, as evidenced by Masson’s trichrome staining. Irisin also improved mitochondrial dysfunction induced by BDL surgery. Conclusion: Irisin effectively attenuated HSC activation, ameliorated liver fibrosis in BDL mice, and improved associated mitochondrial dysfunction. These findings highlight the therapeutic potential of irisin for the treatment of liver fibrosis. Keywords: liver fibrosis, irisin, hepatic stellate cells, mitochondrial dysfunction, TGF-β1

Development and Evaluation of the Cultural Competence Course for Vietnamese Nursing Students

Ho Thi Thuy Trang 인제대학교 일반대학원 2020 국내석사

ABSTRACT Development and Evaluation of the Cultural Competence Course for Vietnamese Nursing Students Ho Thi Thuy Trang (Advisor: Prof. Jina Oh, R.N, Ph.D.) Department of Nursing Graduate School, Inje University This study was supported by the Global Korea Scholarship (GKS) of the National Institute for International Education under the Ministry of Education, Korea (grant number KGSP-GRA-2016-683). Background: Cultural competence is crucial competence for both health care providers and student to promote health outcome and quality of care. The purposes of study were develop and evaluate the effectiveness of cultural competence intervention on the level of cultural competency on Vietnamese nursing students in a Bachelor of Science in nursing program Methods: The cultural competence program was developed and evaluated based on five phase of ADDIE model. The participants were encouraged cultural competence in context of knowledge, attitude and skill through diverse teaching methods. The instructional materials were contributed from movie and documentary, presentation, and service learning. Evaluation tools included self-evaluation and focus group interview. A pretest- posttest, one control and two experimental groups, and quasi experimental design were used with 60 nursing students who participated in the program. Results: The findings indicated that significant group by time interactions in total cultural competence score (F=66.73, p<.001) was found. Participant’s perception about effect of training expressed three categories “journey toward cultural competence”, “satisfaction of cultural nursing competence course”, and “suggestion for improvement”. Besides, no statistically significant differences between stand-alone cultural course, and cultural course with service learning were revealed. “Obtaining culture’s perspective through real experience”; and “expanding understanding of cultural competence through service learning” were immersed from participants having service learning. Conclusions: This study found that cultural competence course was developed systematically to adopt student’s educational need; and had effective on student’s cultural competence. It also provides evidence on the effects of cultural competence course in theoretical and practice aspects should be considered in the future. Furthermore, cultural competence issue should expand and incorporate nursing curricula.

Moment infinitely divisible weighted shifts

Trinh Thi Thuy Hong 忠南大學校 大學院 2025 국내박사

Operator theory, an essential branch of functional analysis, examines linear and nonlinear mappings between topological or normed vector spaces. The thesis aims to present certain results regarding moment infinitely divisible weighted shifts on complex Hilbert spaces. We first study the foundational aspects of operator theory specific to complex Hilbert spaces. Next, we focus on the moment infinitely divisible weighted shift operator class. There are some results related to this class operator presented in this thesis. Also, some new results will be proved in detail. Each chapter is intended to be selfcontained with full details. Some definitions could be repeated to be easy to follow and avoid confusion. The text also contains many examples describing the concepts and results thoroughly.

이온성 액체의 생분해성과 생태 독성효과

Pham Thi Phuong Thuy 전북대학교 대학원 2007 국내석사

이온성 액체는 휘발성 유기용매를 대체할 수 있는 청정용매로, 여러 공정에 이용할 수 있는 액체상태의 소금이다. 이온성 액체는 구조를 변화시키거나 양이온과 음이온의 구성을 바꿈으로써 산업공정의 사용에 적합하도록 화학적, 물리학적 특성을 변화 시킬 수 있다. 이렇게 합성된 이온성 액체가 지속 가능한 화학물질이 되기 위해서는 이온성 액체의 생물학적 행동에 대한 평가가 반드시 수행되어야 한다. 그러므로 본 연구자는 전세계적으로 데이터가 미흡한 이온성 액체의 생태독성과 생 분해성에 대한 조사를 실시 하였다. 음이온으로 bromide 결합하고 각각 알킬 체인의 길이가 3, 4, 6, 8개인 양이온 1-alkyl-3-methylimidazolium, 1-alkyl-3-methylpyridinium, 1-alkyl-1-methylpyrrolidinium의 독성을 측정하기 위하여 미세 녹조류 (Pseudokirchneriella subcapitata)를 선정하였다. 독성 측정방법으로는 OECD [Organization for Economic Cooperation and Development] 와 EPA [Environmental Protection Agency]에서 참조된 성장반응 실험이 실시 되었으며, 조류의 광합성 특성을 기초로 고안된 독성 측정장치를 통해 이루어졌다. 실험결과 두 가지 실험 방법에서 양이온의 종류에 관계없이 알킬 체인의 길이가 증가할수록 독성이 증가되는 것을 확인할 수 있었다. 양이온의 종류에 따른 독성 평가 경우, imidazolium과 pyridinium이 pyrrolidinium보다 독성이 더 강하게 측정되어서 실험된 이온성 액체 중 pyrrolidinium이 가장 친환경적 화학구조를 가진 것으로 판단할 수 있었다. 폐수나 하수 처리공정에서 이온성 액체의 처리 가능성과 분해과정을 확인하기 위하여 생 분해성 실험을 실시하였다. 활성오니는 전주시 하수처리장에서 채취하였으며 2 달간의 시간 동안 이온성 액체의 생 분해성 과정을 HPLC와 LC-MS로 측정하였다. 실험결과 dialkylimidazolium과 dialkylpyridinium 염은 각기 다른 알킬 체인 부분의 산화 과정을 통해 생 분해 된 것을 확인 할 수 있었다. Imidazolium염의 경우 1-(1-hydroxybutyl)-3-methylimidazolium, 1-(3-hydroxybutyl)-3-methylimidazolium, 1-butyl-3-hydroxymethyl imidazolium, 1-methyl-3-(3-oxobutyl)imidazolium, methylimidazole, butylimidazole의 중간체를 관찰할 수 있었으며, pyridinium의 경우 1-hydroxybutyl-3-methylpyridinium, 1-(2-hydroxybutal)-3-methylpyridinium, 1-(2-hydroxyethyl)-3-methylpyridinium and methylpyridine의 중간체를 확인할 수 있었다.

Essays on behavioral finance

Truong, Thuy Thi Thu 영남대학교 대학원 2021 국내박사

This thesis comprises three essays that discuss specific applications of behavioral finance to asset pricing. Motivated by the inconclusive debates on anomalies caused by the psychological biases of irrational investors in the literature, the first essay examines the existence of prevalent anomalies in the Korean stock market during a recent sample period and provides behavioral explanations for these anomalies. Methodologically, this essay examines whether hedge returns on long-short portfolios are significant and whether there are significant changes in market returns over time. The findings show that investment, profitability, lottery-related anomalies, and turn-of-month anomaly exist in the Korean stock market. The second essay investigates whether investor optimism and high personal funding liquidity around the beginning of the month can amplify investors' preference for lottery-like stocks by examining the pricing of lottery-like stocks around the beginning of the month (i.e., at the turn of the month). Prior studies at a monthly frequency have shown that lottery-like stocks tend to have low returns in the following month, known as the lottery anomaly. However, my daily frequency study finds out a cyclicality of the lottery anomaly within a month. Specifically, a long-short portfolio earns positive returns over a few days at the beginning of each month. However, the profit is entirely subdued by negative returns over the rest of the month, resulting in the monthly negative return of the lottery anomaly in the monthly frequency literature. Moreover, I demonstrate that investor demand for lottery-like stocks is magnified abnormally and stronger than for other stocks at the turn of the month, explaining the outperformance of lottery-like stocks. The third essay investigates the change in gambling preference of irrational investors under different conditions. Specifically, this essay examines the pricing of lottery-like stocks under different stock market conditions, housing market conditions, or macroeconomic conditions in South Korea. The findings show that the underperformance of lottery-like stocks is more significant when the market is up, more stable, and when the unemployment rate is lower. 이 논문은 투자자들의 비합리적 행태가 자산 가격 결정에 미치는 영향을 실증적으로 분석한다. 본 논문은 크게 세 챕터의 소논문으로 구성된다. 첫째, 기존문헌에서 다루어진 행태재무학적 이례현상을 횡단면적 이상현상과 시계열적 이상현상으로 분류하고, 이러한 이상현상이 최근 표본 기간 동안 한국 주식 시장에서 어떠했는지 분석한다. 매수-매도 포트폴리오를 구성하여 초과 수익률의 유의성을 검토한 결과 국내 주식 시장은 투자(investment), 수익성(profitability), 복권주(lottery-like stock) 이상현상 및 월바뀜(turn-of-month) 이상현상이 존재함을 밝힌다. 두 번째 소논문에서는 횡단면적 이상현상과 시계열적 이상현상의 교차효과에 대해 가설을 세우고 검토한다. 구체적으로, 월바뀜 시기의 개인투자자 감정 변화 및 자금조달 유동성 변화로 인해, 복권주 선호 성향이 이 시기에 보다 강화되어 복권주 과대평가가 일어 날수 있다는 가설을 세우고 검증한다. 월(monthly) 빈도 자료를 이용한 기존 연구에서는 복권성향 측정변수를 이용해 구성한 매수-매도 포트폴리오가 평균적으로 음의 월수익률을 거둔다고 보고한다. 반면, 본 연구에서는 일(daily) 빈도 자료를 이용하여 월초 거래일과 나머지 기간의 거래일을 나누어 살펴볼 때, 월초에는 양의 수익률을 나머지 거래일에는 큰 음의 수익률을 거두는 사실을 발견한다. 즉, 복권주는 월초 몇 거래일 동안 고평가되어 양의 수익률을 거두지만 나머지 기간동안 크게 하락하여 월 수익률은 기존문헌에서 보고한 바와 같이 음의 수익률을 거두게 된다. 또한, 개인투자자들의 복권주 거래량을 분석하면, 복권주에 대한 개인 투자자의 비정상 순매수량이 월초에 크게 확대됨을 알수 있다. 이는 월초 거래일동안의 복권주 고평가 현상이 월 바뀜 기간 동안 개인투자자의 복권주 편향 확대에 기인함을 보여준다. 세 번째 소논문은 다양한 거시 경제 지표 변화에 따라 개인 투자자의 복권주 선호도의 변화 및 복권주 수익률 이상현상의 변화를 분석한다. 보다 구체적으로는 주식 시장 수익률 및 변동성 변화, 주택 가격 지표 및 가처분 소득 변화, 고용률 변화에 따라 개인투자자들의 복권주 선호성향 변화 및 복권주 수익률 이상현상의 변화를 살펴본다. 결과에 따르면 복권주의 저조한 성과는 시장이 상승하고 변동성이 작고 실업률이 낮을 때 더 크다. 즉 이러한 기간동안 개인투자자의 복권주 선호도가 높아지고 고평가되어 미래 수익률이 낮아짐을 의미한다.