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์ ๊ธฐ์ฉ๋งค ๋ฆฌ๊ทธ๋์ ๊ตฌ์กฐ์ ํน์ฑ์ด ๋ฆฌ๊ทธ๋ ธ-๋ฐ์ด์คํ๋ผ์คํฑ์ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ ๋ฏธ์น๋ ์ํฅ
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ) -- ์์ธ๋ํ๊ต ๋ํ์ : ๋์
์๋ช
๊ณผํ๋ํ ์ฐ๋ฆผ๊ณผํ๋ถ(ํ๊ฒฝ์ฌ๋ฃ๊ณผํ์ ๊ณต), 2021. 2. ์ต์ธ๊ท.In this study, the effect of the structural characteristics of ethanol organosolv lignin (EOL) on the thermal and mechanical properties of ligno-bioplastics was investigated. A response surface methodology (RSM) based on central composite design (CCD) was adopted to investigate the influence of the extraction conditions on the structural characteristics of EOL. Via the RSM, EOL with a low molecular weight, low polydispersity index (PDI), high phenolic hydroxyl content, and condensed structure was obtained under harsh extraction conditions. The correlation between the structural characteristics of EOL and the severity of the extraction conditions was confirmed by introducing the combined severity factor (CSF), and a clear correlation consistent with the RSM results was derived. In addition, the structural characteristics of the EOL derived under different extraction conditions influenced its thermal properties. The EOL with a low molecular weight, high phenolic hydroxyl group content, and condensed structure, exhibited high thermal stability while delaying the thermal decomposition with a high glass transition temperature (Tg). To predict the weight reduction rate of EOL at 300 ยฐC, the regression model (R2 = 0.837) was suggested. In accordance with the model, the lower the molecular weight of the EOL, the lower the rate of thermal degradation of EOL was expected. Meanwhile, the EOLโPLA thermo-bioplastics prepared using three types of EOL (EOL extracted under low-severity (LL), moderate-severity (ML), and high-severity (HL) conditions) exhibited improved thermal stability compared to neat PLA. According to the thermal properties of EOL, the EOLโPLA bioplastic formed with HL exhibited exceptional thermal stability. The bioplastics had different mechanical properties depending on the types of EOL. The tensile strength of the bioplastics tended to decrease as the content of lignin in the bioplastics increased. Conversely, the nominal strain at break of the bioplastics exhibited a different tendency depending on the types of EOL.
Oxypropylation of EOL was employed to improve the thermoplasticity and compatibility with PLA. Three types of EOL (LL, ML, and HL) with different structural characteristics were modified by propylene oxide (PO). During the oxypropylation, the degree of substitution (DS) and the degree of polymerization (DP) of the propyl side chain were affected by the distribution of the hydroxyl groups in the initial EOL structure. The HL with a high aromatic hydroxyl group content (4.31 mmol/g) exhibited a high DS (0.77), and the LL with a high aliphatic hydroxyl group content (2.94 mmol/g) exhibited a high DP (11.17). Moreover, the oxypropylation of EOL enhanced its thermoplasticity. In particular, a new Tg (from 55 to 60 ยฐC) and melting point were observed for the oxypropylated LL and ML. In addition, the compatibility of EOL with PLA was successfully improved by oxypropylation, which was supported by a slick and flat surface structure observed in the bioplastics with oxypropylated LL and ML. The increased compatibility of EOL with PLA induced an increase in the tensile strength of the oxypropylated EOLโPLA bioplastic to a similar level to that of the neat PLA, and the nominal strain was also increased to a higher level than that of the neat PLA. In addition, the Tg of the EOLโPLA bioplastic was increased compared to that of the neat PLA in a thermodynamic perspective, implying that the mechanical properties of the oxypropylated EOLโPLA bioplastic were improved at temperatures above the Tg of the neat PLA.
Thermosetting lignopolyurethanes with different thermal and mechanical properties depending on the types of EOL were prepared. The structural characteristics and properties of lignopolyurethane highly depended on the structural characteristics of oxypropylated EOL. The oxypropylated EOL with a high hydroxyl group content showed a high reaction rate. All of the lignopolyurethanes exhibited increased thermal stability at low temperatures compared to those of the corresponding oxypropylated EOLs, whereas at high temperatures, the thermal properties of lignopolyurethane depended on the thermal properties of the corresponding initial EOLs. In addition, the structural characteristics of the EOL had a significant effect on the mechanical properties of the lignopolyurethane film. The oxypropylated EOL with a high average hydroxyl content enabled to form a lignopolyurethane film with a high crosslink density due to its high reactivity. The lignopolyurethane film with a high crosslinking density exhibited competent tensile strength.
Consequently, the thermoplastic and thermosetting properties of EOL were imparted through chemical modification methods based on the correlation between the structural characteristics and properties of the EOL. The thermal and mechanical properties of the ligno-bioplastics were found to be significantly influenced not only by the chemical modification of EOL but also by the structural characteristics of lignin, the raw material.๋ณธ ์ฐ๊ตฌ์์๋ ์ ๊ธฐ์ฉ๋งค ๋ฆฌ๊ทธ๋์ ๊ตฌ์กฐ์ ํน์ฑ์ด ๋ฆฌ๊ทธ๋
ธ-๋ฐ์ด์คํ๋ผ์คํฑ์ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ ๋ฏธ์น๋ ์ํฅ์ ์กฐ์ฌํ์๋ค. ๋จผ์ ์ํ์ฌ ์ ๊ธฐ์ฉ๋งค ๋ฆฌ๊ทธ๋(EOL)์ ๊ตฌ์กฐ์ ํน์ฑ์ ๋ํ ์ถ์ถ ์กฐ๊ฑด์ ์ํฅ์ ๋ฐ์ํ๋ฉด๋ถ์๋ฒ(RSM)์ ์ด์ฉํ์ฌ ์กฐ์ฌํ์๋ค. ์ค์ ๋ RSM ๋ถ์ ๋ฒ์ ๋ด์์ ์ถ์ถ ์กฐ๊ฑด์ด ๊ฐํนํ ์๋ก ๋ฎ์ ๋ถ์๋, ๋ฎ์ ๋ค๋ถ์ฐ๋, ๋์ ๋ฐฉํฅ์กฑ ์์ฐ๊ธฐ ํจ๋ ๋ฐ ์ถํฉ๋ ๊ตฌ์กฐ๋ฅผ ๊ฐ์ง EOL์ด ์์ฐ๋๋ ๊ฒฝํฅ์ ๋ณด์๋ค. ์ด๋ฌํ ๊ฒฝํฅ์ ์ถ์ถ ์กฐ๊ฑด์ ๊ฐํน๋ ์ง์(CSF)๋ฅผ ๋์
ํ์ฌ EOL์ ๊ตฌ์กฐ์์ ๋ช
ํํ ์๊ด๊ด๊ณ๋ฅผ ๋์ถํจ์ผ๋ก์จ ํ์ธ๋์๋ค. ๋ํ ๋ค์ํ ์ถ์ถ ์กฐ๊ฑด์์ ํ์๋ EOL์ ๊ตฌ์กฐ์ ์ด์ ํน์ฑ ๊ฐ์ ์๊ด๊ด๊ณ๋ฅผ ํ๊ฐํ์๋ค. EOL์ ์ด์ ํน์ฑ์ ๋ถ์๋ ๋ฐ ๋ฐฉํฅ์กฑ ์์ฐ๊ธฐ ์ธ์์ ๋๋ ทํ ์๊ด ๊ด๊ณ๋ฅผ ๋ณด์๋ค. ๋ฎ์ ๋ถ์๋, ๋์ ๋ฐฉํฅ์กฑ ์์ฐ๊ธฐ ํจ๋ ๋ฐ ์ถํฉ๋ ๊ตฌ์กฐ๋ฅผ ๊ฐ๋ EOL์ ๋์ ์ ๋ฆฌ์ ์ด์จ๋(Tg), ๋ฎ์ ์ด๋ถํด ์์ ์จ๋ ๋ฐ ์ด๊ธฐ ๋ถํด ์๋๋ฅผ ๋ํ๋๋ค. EOL์ ๊ตฌ์กฐ์ ์ด์ ํน์ฑ ๊ฐ์ ์๊ด๊ด๊ณ ๊ฒฐ๊ณผ๋ฅผ ๋ฐํ์ผ๋ก EOL์ ์ค๋ ๊ฐ์์จ ์์ธก์ ์ํ ํ๊ท ๋ชจ๋ธ(R2 = 0.837)์ด ์ ์๋์์ผ๋ฉฐ, EOL์ ๋ถ์๋์ด ๋ฎ์์๋ก 300 ยฐC์์์ ์ด๋ถํด๊ฐ ๋๋ฆฌ๊ฒ ๋ฐ์ํ ๊ฒ์ผ๋ก ์์ธก๋์๋ค. ์ถ์ถ ์กฐ๊ฑด์ ๊ฐํน๋๊ฐ ์๋ก ๋ค๋ฅธ EOL(LL(#5, ๋ฎ์ ๊ฐํน๋ ์กฐ๊ฑด์์ ์ถ์ถ๋ EOL), ML(#16, ์ค๊ฐ์ ๊ฐํน๋ ์กฐ๊ฑด์์ ์ถ์ถ๋ EOL), HL(#4, ๋์ ๊ฐํน๋ ์กฐ๊ฑด์์ ์ถ์ถ๋ EOL))์ ์ฌ์ฉํ์ฌ ์ ์กฐ๋ EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ์ฌ์ฉ๋ EOL ์ข
๋ฅ์ ๋ฐ๋ผ ๋ค๋ฅธ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ ๋ํ๋๋ค. EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ์์ PLA์ ๋นํด ์ฐ์ํ ์ด์์ ์ฑ์ ๋ํ๋์ผ๋ฉฐ, HL๋ฅผ ์ฌ์ฉํ์ฌ ์ ์กฐํ EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ๋ค๋ฅธ ๋ฐ์ด์คํ๋ผ์คํฑ ๋ณด๋ค ๋์ ์ด๋ถํด ์์์ ๊ณผ ์ต๋ ๋ถํด ์จ๋๋ฅผ ๋ํ๋๋ค. EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ์ธ์ฅ ๊ฐ๋๋ ๋ฆฌ๊ทธ๋ ํจ๋์ด ์ฆ๊ฐํจ์ ๋ฐ๋ผ ๊ฐ์ํ๋ ๊ฒฝํฅ์ ๋ํ๋๋ค. ๋ฐ๋ฉด EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ๊ณต์นญ๋ณํ๋ฅ ์ EOL์ ๋ฐ๋ผ ๋ค๋ฅธ ๊ฒฝํฅ์ ๋ณด์๋ค.
ํํธ, EOL์ ์ด๊ฐ์์ฑ๊ณผ ๋ฐ์ด์คํด๋ฆฌ์ด์คํฐ์์ ์์ฉ์ฑ์ ๊ฐ์ ํ๊ธฐ ์ํด ์ฅ์ํ๋กํํ๋ฅผ ๋์
ํ์๋ค. ์ฅ์ํ๋กํํ๋ ๊ตฌ์กฐ์ ํน์ฑ์ด ๋ค๋ฅธ ์ธ ์ข
๋ฅ์ EOL(LL, ML ๋ฐ HL)์ ์ด์ฉํ์ฌ EOL์ ์์ฐ๊ธฐ์ ํ๋กํ๋ ์ฅ์ฌ์ด๋(PO)์ ๋ค์ํ ๋ชฐ๋น(1:1, 1:2 ๋ฐ 1:5)๋ก ์ค์ํ๋ค. ์ฅ์ํ๋กํํ ๊ณผ์ ์์ ์ด๊ธฐ EOL์ ์์ฐ๊ธฐ ๋ถํฌ๋ ํ๋กํ ์ธก์์ ์นํ๋์ ์คํฉ๋์ ํฌ๊ฒ ์ํฅ์ ๋ฏธ์ณค์ผ๋ฉฐ, ๋ฐฉํฅ์กฑ ์์ฐ๊ธฐ ํจ๋์ด ๋์ HL(4.31 mmol/g)์ ๋์ ์นํ๋(0.77)๋ฅผ ๋ณด์๊ณ , ์ง๋ฐฉ์กฑ ์์ฐ๊ธฐ ํจ๋์ด ๋์ LL(2.94 mmol/g)์ ๋์ ์คํฉ๋(11.17)๋ฅผ ๋ํ๋๋ค. ์ฅ์ํ๋กํํ๋ EOL์ ์ด๊ฐ์์ฑ์ ํฅ์์์ผฐ์ผ๋ฉฐ, ๊ตฌ์กฐ์ ํน์ฑ๊ณผ ์ด๊ธฐ EOL์ ๋ฐ๋ผ ์๋ก ๋ค๋ฅธ ์ด์ ํน์ฑ์ ๋ํ๋๋ค. ํนํ ์ฅ์ํ๋กํํ๋ LL๊ณผ ML์ 55-60 ยฐC ๋ฒ์์ ์๋ก์ด Tg๊ฐ ์์ฑ๋์์ผ๋ฉฐ, ์ฉ์ต์ ์ด ๊ด์ฐฐ๋์๋ค. ๋ํ ๊ฐ์ ๋ ์ด๊ฐ์์ฑ์ ๊ธฐ๋ฐ์ผ๋ก EOL๊ณผ PLA์ ์์ฉ์ฑ์ด ์ฅ์ํ๋กํํ์ ์ํด ํฅ์๋์๋ค. ์ฅ์ํ๋กํํ LL ๋ฐ ML์ ์ด์ฉํ ๋ฐ์ด์คํ๋ผ์คํฑ์์๋ ์ด๊ฐ์์ฑ ๋ฐ ์์ฉ์ฑ์ด ๊ฐ์ ๋์ด ์ด๊ธฐ EOL์ ์ด์ฉํ ๋ฐ์ด์คํ๋ผ์คํฑ์ ๋นํด ๋งค๋๋ฝ๊ณ ํํํ ํ๋ฉด ๊ตฌ์กฐ๊ฐ ๊ด์ฐฐ๋์๋ค. EOL์ ๊ฐ์ ๋ PLA์์ ์์ฉ์ฑ ๋ฐ ์ด๊ฐ์์ฑ์ ๋ฐ์ด์คํ๋ผ์คํฑ์ ์ธ์ฅ๊ฐ๋๋ฅผ PLA์ ์ ์ฌํ ์์ค์ผ๋ก ํฅ์์์ผฐ์ผ๋ฉฐ ๊ณต์นญ๋ณํ๋ฅ ์ PLA๋ณด๋ค ๋์ ์์ค์ผ๋ก ์ฆ๊ฐ์์ผฐ๋ค. ๋์ญํ์ ์ด๋ถ์ ๊ฒฐ๊ณผ, ์ฅ์ํ๋กํํ EOL์ ์ฒจ๊ฐ๋ PLA์ Tg๋ฅผ ํฅ์์์ผ ๋ฌผ๋ฆฌยทํํ์ ํน์ฑ์ ๊ฐ์ ํ์๋ค.
๋ํ ๊ตฌ์กฐ์ ํน์ฑ์ด ์๋ก ๋ค๋ฅธ ์ฅ์ํ๋กํํ ๋ฆฌ๊ทธ๋์ ์ด์ฉํ์ฌ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ด ๋ค๋ฅธ ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ์ ์กฐํ์๋ค. ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ์ฅ์ํ๋กํํ EOL๊ณผ ํฅ์ฌ๋ฉํธ๋ ๋์ด์์์๋ค์ดํธ(HDI)๋ฅผ ์ด์ฉํ์ฌ ํฉ์ฑํ์์ผ๋ฉฐ, ์ฅ์ํ๋กํํ EOL์ ๊ตฌ์กฐ์ ํน์ฑ์ ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ๋ฐ์์ฑ ๋ฐ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ ์ํฅ์ ๋ฏธ์ณค๋ค. ๊ตฌ์กฐ ๋ด ์์ฐ๊ธฐ ํจ๋์ด ๋์ ์ฅ์ํ๋กํํ EOL์ ๋์ ๋ฐ์ ์๋๋ฅผ ๋ํ๋๋ค. ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ์ด๊ธฐ ์ด์์ ์ฑ์ ๊ฐ๊ฐ์ ์์ํ๋ ์ฅ์ํ๋กํํ EOL์ ๋นํด ์ฆ๊ฐํ์์ผ๋ฉฐ 350 ยฐC ์ด์์ ๊ณ ์จ์์ ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ์ด์ ํน์ฑ์ ์ด๊ธฐ EOL์ ์ด์ ํน์ฑ์ ๋ฐ๋ผ ๋ค๋ฅด๊ฒ ๋ํ๋ฌ๋ค. ๋ํ, ์ฅ์ํ๋กํํ EOL์ ๊ตฌ์กฐ์ ํน์ฑ์ ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ ํ๋ฆ์ ๊ธฐ๊ณ์ ๋ฌผ์ฑ์ ํฐ ์ํฅ์ ๋ฏธ์ณค๋ค. ์์ฐ๊ธฐ ํจ๋์ด ๋์ ์ฅ์ํ๋กํํ EOL์ ๋์ ๋ฐ์์ฑ์ผ๋ก ์ธํด ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ์ ๊ฐ๊ต๋ฐ๋๋ฅผ ์ฆ๊ฐ์์ผ ๋์ ์ธ์ฅ๊ฐ๋๋ฅผ ์ผ๊ธฐํ๋ค.
๊ฒฐ๋ก ์ ์ผ๋ก EOL์ ๊ตฌ์กฐ์ ๋ฌผ์ฑ ๊ฐ์ ์๊ด๊ด๊ณ๋ฅผ ๋ฐํ์ผ๋ก ์ฅ์ํ๋กํํ๋ฅผ ํตํด EOL์ ์ด๊ฐ์์ฑ์ ๋ถ์ฌํ์ฌ EOL-PLA ๋ฐ์ด์คํ๋ผ์คํฑ์ ์ ์กฐํ์์ผ๋ฉฐ ์ฐ๋ ํ ํฉ์ฑ์ ํตํด ์ด๊ฒฝํ์ฑ์ ๋ถ์ฌํ์ฌ ๋ฆฌ๊ทธ๋
ธํด๋ฆฌ์ฐ๋ ํ ํ๋ฆ์ ์ ์กฐํ์๋ค. ์ด๋ ์ด๊ธฐ EOL์ ๊ตฌ์กฐ์ ํน์ฑ์ ๋ฆฌ๊ทธ๋
ธ-๋ฐ์ด์คํ๋ผ์คํฑ์ ์ด์ ยท๊ธฐ๊ณ์ ํน์ฑ์ ์ ์๋ฏธํ ์ํฅ์ ๋ฏธ์ณค๋ค.Chapter 1 1
Introduction 1
1. Background 2
1.1. Lignin as a bioplastic material 2
1.1.1. Bioplastics as alternatives to petroleum-based plastics 2
1.1.2. Drawbacks of thermoplastics (biopolyester) and thermosetting (biopolyurethane) bioplastics 6
1.1.3. Lignin as an additive or precursor of bioplastic materials and ligno-bioplastic 9
1.2. Bottlenecks of lignin utilization for bioplastics applications derived from its structure and thermal properties 12
1.2.1. Types of lignin based on the extraction processes and organosolv lignin 12
1.2.2. Diversity of the structural characteristics and thermal properties of lignin 16
1.2.3. Bottlenecks of lignin utilization in bioplastic production 20
1.3. Strategies for improving the commercial utilization of lignin in bioplastic production 21
1.3.1. Selective production of lignin with desirable structure 21
1.3.2. Compatibilization of lignin and thermoplastic resins by functionalization 23
1.3.3. Macromoleculization of lignin with bifunctional monomers 26
2. Objectives 27
3. Literature review 30
3.1. Investigation of the correlation between the structure and properties of lignin for its application in bioplastic production 30
3.1.1. Control of the lignin structure by adjusting the extraction conditions 30
3.1.2. Thermal properties of lignin based on its structure 33
3.2. Unmodified ligninโPLA bioplastics 36
3.2.1. Mechanical properties of ligninโPLA bioplastics 36
3.2.2. Thermal properties of ligninโPLA bioplastics 38
3.3. Chemical modification of lignin for ligninโPLA bioplastics 39
3.3.1. Lignin graft copolymer 39
3.3.2. Macromoleculization 43
โ
Chapter 2 46
Thermal and mechanical properties of EOLs and EOLโPLA bioplastics 46
1. Introduction 47
2. Materials and methods 50
2.1. Ethanol organosolv lignin (EOL) preparation 50
2.1.1. Raw materials 50
2.1.2. Conditions for EOL extraction 50
2.1.3. EOL extraction process 53
2.2. Structural characteristics of the EOL 54
2.2.1. Molecular weight 54
2.2.2. Hydroxyl group content 54
2.2.3. Intramolecular coupling structure of EOL 55
2.3. Thermal properties of EOL 57
2.3.1. Thermal decomposition characteristics of EOL 57
2.3.2. Glass transition temperature of EOL 57
2.3.3. Statistical analysis 57
2.4. EOLโPLA bioplastic 59
2.4.1. Preparation of EOLโPLA bioplastics 59
2.4.2. Thermal properties of EOLโPLA bioplastics 59
2.4.3. Mechanical properties of EOLโPLA bioplastics 59
3. Results and Discussion 60
3.1. Structural characteristics of EOL based on the extraction conditions 60
3.1.1. Molecular weight and PDI 61
3.1.2. Hydroxyl group content 68
3.1.3. Intramolecular coupling structure 75
3.1.4. Correlation between CSF of extraction condition and the structural characteristics of EOL 81
3.2. The thermal properties of EOL depending on its structural characteristics 84
3.2.1. Statistical analysis of the correlation between weight loss at 300 ยฐC and the structural characteristics of EOL 84
3.2.2. Thermal decomposition characteristics and glass transition temperature of three types of EOL 91
3.3. The properties of the EOLโPLA bioplastics depending on the structural characteristics of EOLs 94
3.3.1. Thermal properties of the EOLโPLA bioplastics depending on types of EOL 94
3.3.2. Mechanical properties of the EOLโPLA bioplastics depending on types of EOL 97
4. Summary 101
โ
Chapter 3 103
Chemical modification of EOL for improving thermoplasticity and compatibility in EOLโPLA bioplastics 103
1. Introduction 104
2. Materials and methods 107
2.1. EOL preparation 107
2.1.1. Raw materials 107
2.1.2. EOL extraction 107
2.1.2. Properties of EOL based on the extraction condition 110
2.2. Oxypropylated lignin preparation 112
2.2.1. Oxypropylation of three types of EOL 112
2.2.2. Properties of the oxypropylated EOLs in relation to their structural characteristics 113
2.3. Oxypropylated EOLโPLA bioplastics 116
2.3.1. Preparation of the EOLโPLA bioplastics 116
2.3.2. Morphologies of the EOLโPLA bioplastics 116
2.3.3. Properties of oxypropylated EOLโPLA bioplastics based on its structural characteristics 116
3. Results and Discussion 118
3.1. Structural characteristics of the oxypropylated EOL 118
3.1.1. Molecular weight of the oxypropylated EOLs 118
3.1.2. Hydroxyl group and modified methyl group content of the oxypropylated EOLs 123
3.1.3. DS and DP of the oxypropylated EOLs 131
3.2. Thermal properties of oxypropylated EOLs based on its structural characteristics 134
3.2.1. Thermal decomposition behavior of the oxypropylated EOL based on its structural characteristics 134
3.2.2. DSC analysis of the oxypropylated EOL based on its structural characteristics 138
3.3. The properties of the oxypropylated EOLโPLA bioplastic 143
3.3.1. Morphologies of the EOLโPLA bioplastics 143
3.3.2. Thermal properties of the oxypropylated EOLโPLA bioplastics 146
3.3.3. Mechanical properties of the oxypropylated EOLโPLA bioplastics 151
3.3.4. Thermodynamic properties of the oxypropylated EOLโPLA bioplastics 157
4. Summary 160
โ
Chapter 4 162
Preparation and characterization of lignopolyurethanes using different types of EOL 162
1. Introduction 163
2. Materials and methods 166
2.1. EOL and oxypropylated EOL preparation 166
2.1.1. Raw materials 166
2.1.2. Extraction of EOL 166
2.1.3. Oxypropylation of EOL 166
2.2. Lignopolyurethane preparation 169
2.2.1. Urethane synthesis for lignopolyurethane 169
2.2.2. Lignopolyurethane film preparation 169
2.3. Structural characteristics of lignopolyurethane 171
2.3.1. Elementary analysis of lignopolyurethane 171
2.3.2. FT-IR analysis of lignopolyurethane 171
2.4. The properties of lignopolyurethane 172
2.4.1. Thermal properties of lignopolyurethane 172
2.4.2. Mechanical properties of lignopolyurethane film 172
3. Results and Discussion 173
3.1. Structural characteristics of lignopolyurethane 173
3.1.1. Urethane synthesis for lignopolyurethane 173
3.1.2. FT-IR analysis of lignopolyurethane 178
3.2. Properties of lignopolyurethane 181
3.2.1. TGA of lignopolyurethane 181
3.2.2. DSC analysis of lignopolyurethane depending on its structural characteristics 184
3.3. Lignopolyurethane film 187
3.3.1. Crosslinking density of lignopolyurethane film 187
3.3.2. Mechanical properties of the lignopolyurethane film 189
4. Summary 194
โ
Chapter 5 196
Concluding remarks 196
References 202
์ด ๋ก 218Docto
Phylogenetic Positioning of a Strongyloides stercoralis Isolate Recovered from a Korean Patient and Comparison with Other Asian Isolates
Strongyloidiasis is caused by Strongyloides stercoralis and is one of the most neglected tropical diseases in tropical and subtropical regions. Although several strongyloidiasis cases have been reported in Korea, genetic analysis of Korean isolates is still incomplete. In this study, a parasite was isolated from a 61-year-old man diagnosed with strongyloidiasis during the treatment of lymphoma on his retroperitoneal lymph node. Diffuse symmetric wall thickening from the ascending to descending colon and a nematode-infected intestine was observed following microscopic examination. Genomic DNA was isolated from a patient tissue block, and S. stercoralis was identified by PCR and sequencing (18S rDNA). In order to determine phylogenetic location of a Korean isolate (named KS1), we analyzed cox1 gene (500-bp) and compared it with that from 47 previous S. stercoralis isolates (28 human isolates and 19 canid isolates) from Asian countries. Our results showed that phylogenetic tree could clearly be divided into 5 different groups according to hosts and regions. KS1 was most closely related with the Chinese isolates in terms of genetic distance.ope
Research on the Architectural Experiments and Alteration of Protestant Churches in Early Modern Seoul
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ฑด์ถํ๊ณผ, 2015. 2. ์ ๋ดํฌ.๋ณธ ์ฐ๊ตฌ๋ ๊ทผ๋ ์ด๊ธฐ ์์ธ์ ๊ฐ์ ๊ต ๊ตํ์ ๋์ฑ ๋ด ํ์ฐ ๊ณผ์ ๊ณผ ๊ฐ์ ๊ต ๊ตํ์ ๋ค์ํ ๊ฑด์ถ ์คํ ๋ฐ ๋ณํ๋ฅผ ๊ณ ์ฐฐํ๋ ๊ฒ์ ๋ชฉ์ ์ด ์๋ค. ์ด๋ฅผ ์ํด ๋ณธ ์ฐ๊ตฌ์์๋ 1884๋
๊ฐ์ ๊ต ์ ๊ต๊ฐ ์์๋ ์ด๋๋ก ๋์ฑ ๋ด์ ์ฅ๋ก๊ต, ๊ฐ๋ฆฌ๊ต ์์์ ๊ตํ๋ค์ด ํ์ฐ๋์ด ์
์งํ๋ ์์์ ์ฃผ๋ชฉํ์๋ค. ๋ํ 1897๋
์ ๋์ ์ผ๊ตํ๋ฅผ ์์์ผ๋ก ๊ฑด๋ฆฝ๋๊ฒ ๋ ๋ํ ์๋ฐฐ๋น๋ค์ ํ๋ฉด๊ณผ ๊ตฌ์กฐ์ ์์ด์์ ๊ฑด์ถ์ ์คํ๊ณผ ๊ทธ์ ๋ฐ๋ฅธ ์ํฅ๊ณผ ๋ณํ์ ๊ด๊ณ๋ฅผ ํ์ธํ์๋ค.
๊ทผ๋๊ธฐ ๊ตํ ๊ฑด์ถ์ ๋ํ ์ฐ๊ตฌ๋ ์ค๋ฌผ์ด ๋๋ถ๋ถ ํ์กดํ๊ณ ์๋ ์ฒ์ฃผ๊ต ์ฑ๋น์ ์ค์ฌ์ผ๋ก ์ฐ๊ตฌ๊ฐ ์งํ๋์ด ์๋ค. ๊ฐ์ ๊ต ๊ตํ ๊ฑด์ถ์ ๊ทผ๋๊ธฐ์ ์ฒ์ฃผ๊ต ์ฑ๋น๋งํผ์ด๋ ์ฌํ์ ์ผ๋ก๋ ๋ฌธํ์ ์ผ๋ก๋ ๊ฑด์ถ์ ์ผ๋ก ์์ธ์์ ํฐ ์ํฅ์ ๋ผ์ณค์์๋ ๋ถ๊ตฌํ๊ณ ์ ์ ๋ฐ ์ฌ๊ฑด์ถ ๋ฑ์ผ๋ก ์ธํ ์ค๋ฌผ ์ฌ๋ฃ ๋ฑ์ ๋ถ์กฑ์ผ๋ก ๊น์ด ์๋ ์ฐ๊ตฌ๊ฐ ์งํ๋์ง ๋ชปํ์๋ค.
ํ์ง๋ง ์ต๊ทผ์ ๊ทผ๋๊ธฐ ๊ฐ์ ๊ต ๊ตํ ๊ฑด์ถ์ ๋ํ ์๋ก์ด ์๋ฃ์ ๋ฐ๊ตด ๋ฐ ๊ฐ ๊ตํ์ ๊ตํ์ฌ ํธ์ฐฌ, ์ ๊ต์ฌ๋ค์ ์ผ๊ธฐ ๋ฐ ํธ์ง๋ฅ ๋ฑ์ ๋ฒ์ญ, ์ธ๊ตญ ์์นด์ด๋ธ ์๋ฃ์ ๋ํ ์ ๊ทผ์ ์ฉ์ด์ฑ ๋ฑ์ ํ์ฌ ๋ง์ ๊ตํ๋ค์ด ์ค์กดํ์ง ์์์๋ ๋ถ๊ตฌํ๊ณ ๋น์์ ๊ฐ์ ๊ต ๊ตํ์ ๋์์ ํน์ฑ ๋ฐ ๊ฑด์ถ์ ํน์ฑ ๋ฑ์ ์๋กญ๊ฒ ์ฌ์กฐ๋ช
ํ ์ ์๋ ๊ณ๊ธฐ๊ฐ ๋๋ค๊ณ ํ ์ ์๋ค.
๊ตํ ์
์ง ๋ฐ ํ์ฐ ๊ณผ์ ์ ์ฅ๋ก๊ตโ๊ฐ๋ฆฌ๊ต ์ ๋ ์ ๊ต๊ธฐ์ง ์๊ธฐ๋ฅผ ๊ฑฐ์น ํ์ ๋์ฑ ๋ด๋ก ํ์ฐํ๊ฒ ๋๋ค. ๋จผ์ ๊ตํ๋ ์ผ๋ฐ ๋์ค๊ณผ์ ์ ์ด์ด ์ฉ์ดํ ๊ณณ๊ณผ ๋ณ์ ๋ฐ ํ๊ต ์์ค์ด ์ธ์์ง ์ ์๋ ์์น์ ์๋ฆฌ ์ก๊ฒ ๋๋ค. ์ด๊ธฐ์ ์ธ์์ง ๊ตํ๋ค์ 4๋๋ฌธ๊ณผ ์์ฅ ์ฃผ๋ณ์ผ๋ก ์ธ์์ง์ ์ ์ ์๋ค. ๊ทธ ์ดํ์ ๊ตํ์ ํ์ฐ์ ์ ๊ต๋ถ ์ฌ์ด์ ๋งบ์ ์ ๊ต์ง ๋ถ๋ด ์ ์ฑ
๊ณผ 3๊ฐ ๊ฑฐ์ ๊ณํ์ ์ํด ๋์ฑ ๋ด ์ง์ญ์ ๊ฑฐ์ ์ ํ๋ณดํ๊ฒ ๋๋ค. ๋ง์ ์ ๊ต๋ถ ์์์ ๊ตํ๋ค์ด ์์ธ์ ์ธ์์ก์์๋ ์๋ก ๊ฒน์น์ง ์๊ณ ๊ณ ๋ฅด๊ฒ ๋ถํฌ๋ ์ ์์๋ ๊ฒ์ ์ ์์ ์ผ๋ก ๋ฐํจ๋์ง๋ ์์์ง๋ง, ์ ๊ต์ฌ๋ค ์ฌ์ด์์ ํ์ ํ ์ ๊ต์ง ๋ถ๋ด์ ์ฑ
์ ์ํฅ์ด๋ค. ๋ํ ๊ตํ ๋ด์ ์ ์๊ฐ ๊ฐ๋ฑ๊ณผ ์ง์ญ๊ฐ๋ฑ์ด ๊ตํ ํ์ฐ ๋ฐ ์
์ง์ ํ ์ถ์ ๋ด๋นํ๊ฒ ๋์๋ค. ์ด๋ ์ ๊ต์ง ๊ฐ์ฒ์ ์์ธ๋์๋ ๋ถ์ชฝ์ ์๋ฐ ๊ณ์ธต ๊ฑฐ์ฃผ ์ง์ญ์ ๊ตํ๊ฐ ์ธ์์ง๋๋ก ํ๋ ์ญํ ์ ํ์๋ค.
ํํธ, ๋ํ ์๋ฐฐ๋น์ด ๊ฑด์ถ๋๊ธฐ ์์ํ ์ดํ์ ๊ฐ์ ๊ต ๊ตํ์ ๊ฑด์ถ ์คํ์ ํ๋ฉด๊ณผ ๊ตฌ์กฐ๋ฅผ ํตํด ๋ค์ํ ์์์ผ๋ก ๋๋ฌ๋๊ฒ ๋๋ค. ํ๋ฉด์ ์์ด์๋ ๋ฏธ๊ตญ๊ตํ์ ์ค๊ณ ๋๋ฉด์ ์์ฉ๊ณผ ์ ์, ํ๊ตญ์ธ ๊ฑด์ถ๊ฐ์ ์ํ ์ผ๋์ ํ๋ฉด์ ์คํ, 2์ธต์ ๊ฐค๋ฌ๋ฆฌ ๊ณต๊ฐ์ ๊ณ ๋ คํ ์ฅ๋ฐฉํ์ ํ๋ฉด์ ๋์
์ผ๋ก ๋ํ๋๋ค. ๊ตฌ์กฐ์ ์ธก๋ฉด์ ์์ด์๋ ๊ฐ์ํ ๊ฐ์ ํธ๋ฌ์ค(sissor-bracing truss)๊ฐ ์ ๋์ ์ผ๊ตํ๋ฅผ ์ง๊ธฐ ์ํด ๋ณด๋ด์จ ๋๋ฉด์ ํตํด ๋์
๋ ๊ฒ์ผ๋ก ์ถ์ ๋๋ฉฐ, ๊ธฐ์ธ์ด์ง ์ฒ์ฅ์ ์ค์๋ถ๋ถ๋ง ํํํ ํน์ง์ ๋ณด์ธ๋ค. ์๋๊ณต ํธ๋ฌ์ค(king post roof truss)๋ ์๋๊ตํ์ ์ ์ฉ์ด ๋์๊ณ , ์ธ์ฅ๋ ฅ์ ๋ฐ๋ ๋๊ณต์ ๋ชฉ์ฌ๋ฅผ ๋์ ํ์ฌ ์ฒ ์ ๋ก ์ฌ์ฉํ ํน์ง์ ๋ณด์ธ๋ค. ์ด๋ ์๋๊ณต ํธ๋ฌ์ค๊ฐ ๊ฐ๋ ๊ฒฝ๊ฐ์ ํ๊ณ๋ฅผ ๊ทน๋ณตํ๊ธฐ ์ํ ์๋๋ก ์๊ฐ๋๋ค. ์๋๊ณต ํธ๋ฌ์ค(queen post roof truss)๋ ์น๋๊ตํ์ ์ ์ฉ์ด ๋์๋ค. ๊ทผ๋ ์๊ธฐ์ ์๋๊ณต ๋ฐฉ์์ ๋๋ฌธ ๊ฒฝ์ฐ์ด๋ค. ๋ํ ์๋๊ณต ํธ๋ฌ์ค์์ ์ผ๋ฐ์ ์ผ๋ก ์ฌ์ฉ๋๋ ํ์ฒ์ฅ ๊ตฌ์กฐ๋ฅผ ํํ ๊ฒ์ด ์๋๋ผ ์ฒ์ฅ ๋ณด์ ์ผ๋ถ๋ฅผ ์ด๋ํ์ฌ ์ฒ์ฅ์ด ์ํน ํ์ธ ๊ตฌ์กฐ๋ฌผ์ ์๋ํ์๋ค๋ ์ ์์ ์์๊ฐ ์๋ค๊ณ ํ๊ฒ ๋ค.
๋ง์ง๋ง์ผ๋ก ๊ทผ๋๊ธฐ ์์ธ์ ๊ตํ ๊ฑด์ถ์ ๋๋ฌ์ผ ์ฌ๋ฌ ์๋๋ค์ ๋ค๋ฅธ ์ง์ญ์ ๊ตํ ๋ฐ ํ๊ต ๊ฑด๋ฌผ์ ์ํฅ์ ์ฃผ์๊ณ , ์ดํ ์๊ธฐ์๋ ์ํฅ์ ์ฃผ๊ฒ ๋๋ค. ํ๋ฉด์ ์์ด์๋ ์ธ์ฒ์ ๋ด๋ฆฌ๊ตํ๊ฐ ์ ๋์ ์ผ๊ตํ์ ๋ง์ฐฌ๊ฐ์ง๋ก ๋ฏธ๊ตญ์ ํ๋ฉด์ ๋์
ํ์ฌ ๊ฑด์ถํ์๋ค. ํ์์ ๋จ์ฐํ ๊ตํ๋ ์ธํ, ๊ตฌ์กฐ, ํ๋ฉด ๋ฑ์์ ์๋๊ตํ์ ๋งค์ฐ ์ ์ฌํ ๊ฑด์ถ์ ํน์ฑ์ ๋ณด์ธ๋ค. ์ฅ๋ก๊ต์ ์ ๋ฐฉํ ํ๋ฉด์ ๋์๊ธฐ์ ๋ชฉํฌ์ ์๋๊ตํ์์ ๋์ผํ๊ฒ ๋ํ๋์ง๋ง, ์ดํ ์๊ธฐ์ ๊ฑด๋ฌผ์์๋ ์ ๋ฐฉํ๋ณด๋ค๋ ์ฅ๋ฐฉํ์ ํ๋ฉด์ผ๋ก ๊ท๊ฒฐ๋๋ ํน์ง์ ๋ณด์ธ๋ค. ๊ตฌ์กฐ์ ์ธก๋ฉด์ ์์ด์๋ ๊ฐ์ํ ๊ฐ์ ํธ๋ฌ์ค๊ฐ ์ ๋์ ์ผ๊ตํ์ ๋์
๋ ์ดํ๋ก ์๋๊ตํ ๋ฑ์ ๊ฐ๋ฆฌ๊ต ๊ตํ ๋ฐ ํ๊ต ๊ฑด๋ฌผ ๋ฑ์ ๊พธ์คํ๊ฒ ํ์ฉ๋์๊ณ , ๊ตํ๋ฅผ ๋ฐ์ด๋์ด ์ฅ๋ก๊ต์ ์ฑ๊ฒฐ๊ต์ ํ๊ต ๋ฐ ๊ตํ ๊ฑด๋ฌผ์์๋ ์ ์ฉ๋ ๊ฒ์ ํ์ธํ ์ ์๋ค.This studys purpose is to trace the location of early Protestant churches in Seoul during 1885-1910 and to reveal the spreading patterns of them. Furthermore, it aims for analyzing their architectural experiments and the alterations over the time period. Specifically, this study focuses on how Presbyterian churches and Methodist churches spread within Seoul city walls since the Protestant churches started missionary works in 1884. Starting with Chungdong First Methodist Church built in 1897, the changes in the floor patterns and roof structureof large chapels due to various architectural experiments and alterations were scrutinized.
The study of modern churches in Korea has mainly focused on existing Catholic churches so far. Even though the Protestant churches played a critical role in shaping modern Seouls cityscape in both social and cultural contexts as Catholic churches did, there has been a limited number of studies about them because of the lack in resources and existing buildings due to Korean war and continuous reconstructions.
However, as new resources for early modern Protestant churches have been collected recently and an easier access to archived materials of other countries and missionaries journals and letters was provided, a better environment for studying urban and architectural characteristics of Protestant churches at that time has been created.
Missionary works of Protestant churches began with the construction of Presbyterian and Methodist mission compounds in Jeong-dong where the foreign legations, including the U.S. legation, were located. However, since it was hard to be in contact with the general public at Jeong-dong, they eventually moved out to new areas in Seoul. First, churches settled in the area where they could easily contact with the general public and find enough space for hospital and school facilities. Churches of the early period were built around the four main gates of old Seoul and big markets. Second, according to the mission field apportionment policies and triangular foothold plans set by the central missionary, both Presbyterian and Methodist branches could procure regional footholds in Seoul boundary. Because of that mission field apportionment policies, they were evenly distributed within Seoul in spite of drastic growth. Furthermore, dividing Seoul into 3 or 4 sections and distributing each to the responsible missionaries had a huge impact on the spreading pattern. Lastly, both inner and outer struggles within the believers or among the local regions contributed to the location and spread of churches. This trend eventually led toward the church construction in the northen part of Seoul where was mainly the residential areas of gentry and therefore, previously excluded from the missionary works.
Meanwhile, as the large chapels were built, Protestant churches began to attempt various architectural experiments, trying different floor plans and roof truss structures. Main characteristics of floor plans include the application and adaptation of the floor plans of American churches, the experiment of basilican brick churches by Korean architects, and the introduction of square-shaped plans considering the use of second floor gallery. In terms of structures, Scissors-shaped bracing truss was introduced when Chungdong First Methodist church was built, and the central parts shape was flat while the sides were inclined. King post roof truss was applied for Andong Presbyterian church, in which the vertical member in charge of tension force was replaced by the iron one instead of wood. Grounds for this feature may be to overcome the limitations in the span length of king post roof truss. Queen post roof truss was used in Seungdong Presbyterian church, and it was a rare type in the early modern period. Seungdong Presbyterian churchs case is significant because some of beams were moved to the side to create a new type of ceiling structure while flat ceiling structure was commonly used for queen post roof truss originally.
Last, the architectural experiments and alterations of Protestant churches in early modern Seoul ultimately influenced the architecture of churches and schools in other regions, and these impacts have been continued afterwards. For the floor plans, Naeri Methodist church in Incheon and Chungdong First Methodist church both applied an American style plans. Namsanhyun Methodist church in Pyoung-yang is very similar to Sang-dong Methodist church in its appearance, structure, and plan. A square-shaped plan for Presbyterian churches appeared in Yangdong Presbyterian church, but the use of square-shaped plan declined as the rectangular plans were used. In the structural aspect, scissors-shaped bracing truss, which was first applied in Chungdong First methodist church, began to be widely used in school buildings and methodist churches, including Sangdong Methodist church. It is even found in the Presbyterian churches and the Holiness churches after all.โ
. ์ ๋ก 1
1.1 ์ฐ๊ตฌ์ ๋ฐฐ๊ฒฝ๊ณผ ๋ชฉ์ 1
1.2 ์ฐ๊ตฌ์ ๋์๊ณผ ๋ฐฉ๋ฒ 3
1.3 ์ ํ์ฐ๊ตฌ์ ๋ถ์ 5
โ
ก. ๊ฐ์ ๊ต ๊ตํ์ ์
์ง์ ํ์ฐ 11
2.1 ์ ๋ ์ ๊ต๊ธฐ์ง์ ์ค๋ฆฝ 11
2.2 ๊ตํ์ ์
์ง์ ํ์ฐ 19
2.2.1 ์ ๋ ์ ๊ต๊ธฐ์ง ์ธ๋ถ๋ก์ ์ง์ถ 19
2.2.2 ์ ๊ต์ง ๋ถ๋ด ์ ์ฑ
๊ณผ ์ง์ญ๋ณ ๋ถํฌ์ ํ์ฐ 26
2.2.3 ๊ตํ ๋ณ ๊ตํ ํ์ฐ 35
โ
ข. ์ด๊ธฐ ๊ฐ์ ๊ต ๊ตํ ๊ฑด์ถ์ ํน์ฑ 39
3.1 ๊ฐ์ ๊ต ๊ตํ ๊ฑด์ถ์ ํน์ฑ 40
3.1.1 ์ ์ ์ง๊ณผ ์ ์๋ค์ ์งํ์๋ก์์ ๊ตํ ๊ฑด์ถ 40
3.1.2 ๋ด๋ถ ๊ณต๊ฐ์ ํน์ฑ 45
3.2 ๋ํ ์๋ฐฐ๋น์ ๋ฑ์ฅ๊ณผ ํ์ฐ 51
3.2.1 ์ฒ์ฃผ๊ต ์ฑ๋น ๊ฑด์ถ์ ์ํฅ 54
3.2.2 ๊ต์ธ์ ์ฆ๊ฐ 56
3.2.2 ์๋ก์ด ํ๋ก๊ทธ๋จ์ ๋์
60
3.3 ๊ตํ์ ํน์ฑ์ ๋ฐ๋ฅธ ๊ฑด์ถ ํ๋์ ์ฐจ๋ณํ 63
3.2.1 ๊ฐ๋ฆฌ๊ต 63
3.2.2 ์ฅ๋ก๊ต 66
โ
ฃ. ๊ฐ์ ๊ต ๊ตํ์ ๊ฑด์ถ์ ์คํ๊ณผ ์ํฅ 71
4.1 ํ๋ฉด์์์ ์คํ 72
4.1.1 ๋ฏธ๊ตญ ์ค๊ณ ๋๋ฉด์ ํตํ ์ญ์ํ ํ๋ฉด์ ๋์
72
4.1.2 ํ๊ตญ์ธ ๊ฑด์ถ๊ฐ์ ์ํ ์ผ๋์ ํ๋ฉด์ ์คํ 81
4.1.3 ์ฅ๋ก๊ต ๊ตํ ๊ฑด์ถ์ ๋์
๋ ์ ๋ฐฉํ์ ํ๋ฉด 87
4.2 ์ง๋ถ ๊ตฌ์กฐ์์์ ์คํ 97
4.2.1 ๊ฐ์ํ ๊ฐ์ ํธ๋ฌ์ค ๊ตฌ์กฐ(scissor-bracing) 100
4.2.2 ์๋๊ณต ์ง๋ถ ํธ๋ฌ์ค ๊ตฌ์กฐ(king post roof truss) 105
4.2.3 ์๋๊ณต ์ง๋ถ ํธ๋ฌ์ค ๊ตฌ์กฐ(queen post roof truss) 111
4.2 ์คํ์ ์ํฅ๊ณผ ๊ตํ ๊ฑด์ถ์ ๋ณํ 115
4.2.1 ๋ค๋ฅธ ์ง์ญ์ผ๋ก์ ์ํฅ 115
4.2.2 ์ดํ ์๊ธฐ๋ก์ ์ํฅ 123
โ
ค. ๊ฒฐ๋ก 135Maste
Parasites and blood-meal hosts of the tsetse fly in Tanzania: a metagenomics study
Background: Tsetse flies can transmit various Trypanosoma spp. that cause trypanosomiasis in humans, wild animals, and domestic animals. Amplicon deep sequencing of the 12S ribosomal RNA (rRNA) gene can be used to detect mammalian tsetse hosts, and the 18S rRNA gene can be used to detect all associated eukaryotic pathogens, including Trypanosoma spp.
Methods: Tsetse flies were collected from the Serengeti National Park (n = 48), Maswa Game Reserve (n = 42), and Tarangire National Park (n = 49) in Tanzania in 2012-13. Amplicon deep sequencing targeting mammal-specific 12S rRNA and 18S rRNA genes was performed to screen the blood-feeding sources of tsetse flies and eukaryotic parasites in tsetse flies, respectively.
Results: 12S rRNA gene deep sequencing revealed that various mammals were blood-feeding sources of the tsetse flies, including humans, common warthogs, African buffalos, mice, giraffes, African elephants, waterbucks, and lions. Genes of humans were less frequently detected in Serengeti (P = 0.0024), whereas African buffaloes were detected more frequently as a blood-feeding source (P = 0.0010). 18S rRNA gene deep sequencing showed that six tsetse samples harbored the Trypanosoma gene, which was identified as Trypanosoma godfreyi and Trypanosoma simiae in subsequent ITS1 gene sequencing.
Conclusions: Through amplicon deep sequencing targeting the 12S rRNA and 18S rRNA genes, various mammalian animals were identified as blood-meal sources, and two Trypanosoma species were detected in tsetse flies collected from the Maswa Game Reserve, Serengeti National Park, and Tarangire National Park in Tanzania. This study illustrates the patterns of parasitism of tsetse fly, wild animals targeted by the fly, and Trypanosoma spp. carried by the fly in Tanzania. It may provide essential data for formulating better strategies to control African trypanosomes.ope
Ampicillin treated German cockroach extract leads to reduced inflammation in human lung cells and a mouse model of Asthma
Cockroaches can cause allergic sensitization in humans via contact with their feces or frass. Antibiotics can affect concentration of major allergen and total bacteria production in German cockroaches (Blattella germanica). This study examined the ability of antibiot-ic-treated German cockroaches to induce allergic airway inflammation and the effect of antibiotics on their lipopolysaccharide and Bla g1, 2, and 5 expression levels. Specifical-ly, we measured the ability of German cockroach extract (with or without prior antibiotic exposure) to induce allergic inflammation in human bronchial epithelial cells and a mouse model of asthma. Bacterial 16S rRNA and lipopolysaccharide levels were lower in ampi-cillin-treated cockroaches than in the control group. The Bla g1, Bla g2, and Bla g5 expression in ampicillin-treated cockroaches decreased at both the protein and RNA lev-els. In human bronchial epithelial cell lines BEAS-2B exposed to the ampicillin-treated extract, expression levels of interleukin-6 and interleukin-8 were lower than that in the control group. The total cell count and eosinophil count in bronchoalveolar lavage fluid was also lower in mice exposed to the ampicillin-treated extract than in those exposed to normal cockroach extract. Mouse lung histopathology showed reduced immune cell infiltration and mucus production in the ampicillin group. Our results showed that ampi-cillin treatment reduced the symbiont bacterial population and major allergen levels in German cockroaches, leading to reduced airway inflammation in mice. These results can facilitate the preparation of protein extracts for immunotherapy or diagnostics applications. ยฉ 2023 The Korean Society for Parasitology and Tropical Medicine.ope
Production of Dermatophagoides farinae Having Low Bacterial Content Using Ampicillin
Background: Symbiotic bacteria in house dust mites pose a risk of immunological side effects in the clinical use of immunotherapeutic agents. In this study, we investigated the duration for which the bacterial concentration in Dermatophagoides farinae could be kept low with antibiotic treatment, and whether the allergenic properties of the mite changed under ampicillin treatment.
Methods: D. farinae was cultivated in the presence of ampicillin powder in an autoclaved medium for 6 weeks. After subsequent subcultures without ampicillin, the mites were harvested, and the extract was prepared. The amounts of bacteria, lipopolysaccharides (LPS), and two major allergens (Der f 1 and Der f 2) were measured. Human bronchial epithelial cells and mice were treated with the D. farinae extract to assess the allergic airway inflammation.
Results: The number of bacteria and level of LPS were reduced by 150-fold and 33-fold, respectively, at least 18 weeks after ampicillin treatment. The concentration of Der f 1 and Der f 2 remained unchanged by ampicillin treatment. The secretion of interleukin (IL)-6 and IL-8 from the human airway epithelial cells decreased when treated with the extract of ampicillin-treated D. farinae compared with that of ampicillin-untreated D. farinae. A mouse asthma model was developed using ampicillin-treated D. farinae. We observed that the level of lung function, airway inflammation, and serum-specific immunoglobulin were not different for the mouse asthma model developed using ampicillin-treated D. farinae than the model developed using ampicillin-untreated D. farinae.
Conclusions: We showed that bacterial content in D. farinae was reduced by ampicillin treatment, which was sufficient to induce allergic sensitization and an immune response. This method will be used to develop more controlled allergy immunotherapeutic agents.
Copyright ยฉ 2023 Ju Yeong Kim et al.ope
Metabarcoding of bacteria and parasites in the gut of Apodemus agrarius
Background: The striped field mouse Apodemus agrarius is a wild rodent commonly found in fields in Korea. It is a known carrier of various pathogens. Amplicon-based next-generation sequencing (NGS) targeting the 16S ribosomal RNA (rRNA) gene is the most common technique used to analyze the bacterial microbiome. Although many bacterial microbiome analyses have been attempted using feces of wild animals, only a few studies have used NGS to screen for parasites. This study aimed to rapidly detect bacterial, fungal and parasitic pathogens in the guts of A. agrarius using NGS-based metabarcoding analysis.
Methods: We conducted 18S/16S rDNA-targeted high-throughput sequencing on cecal samples collected from A. agrarius (n = 48) trapped in May and October 2017. Taxa of protozoa, fungi, helminths and bacteria in the cecal content were then identified.
Results: Among the protozoa identified, the most prevalent was Tritrichomonas sp., found in all of the cecal samples, followed by Monocercomonas sp. (95.8% prevalence; in 46/48 samples) and Giardia sp. (75% prevalence; in 36/48 samples). For helminths, Heligmosomoides sp. was the most common, found in 85.4% (41/48) of samples, followed by Hymenolepis sp. (10.4%; 5/48) and Syphacia sp. (25%; 12/48). The 16S rRNA gene analysis showed that the microbial composition of the cecal samples changed by season (P = 0.005), with the linear discriminant analysis effect size showing that in the spring Escherichia coli and Lactobacillus murinus were more abundant and Helicobacter rodentium was less abundant. Helicobacter japonicus was more abundant and Prevotella_uc was less abundant in males. The microbial composition changed based on the Heligmosomoides sp. infection status (P = 0.019); specifically, Lactobacillus gasseri and Lactobacillus intestinalis were more abundant in the Heligmosomoides sp.-positive group than in the Heligmosomoides sp.-negative group.
Conclusions: This study demonstrated that bacterial abundance changed based on the season and specific parasitic infection status of the trapped mice. These results highlight the advantages of NGS technology in monitoring zoonotic disease reservoirs.ope
๊ทธ๋ ์ด๋ธ์ฆ ๋ณ ํ์๋ก๋ถํฐ ์ป์ ๊ฐ์์ ์กฐ์ง์์์ ์ฐํ์ง์ํฉ์ฑํจ์ ๋ฐํ ๋ฐ ์ง์ง ๊ณผ์ฐํ ํจ๊ณผ์ ๋ํ ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ(์์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :์ํ๊ณผ ์ธ๊ณผํ์ ๊ณต,2005.Maste
๊ณผํ๋ฌธํ์ฌ์ ์ถ์ง๊ณผ์ ์์์ ์ฐธ์ฌ ์ฃผ์ฒด๊ฐ ์ ์ฑ ๋คํธ์ํฌ ์ฐ๊ตฌ : ๋ํ๋ฏผ๊ตญ๊ณผํ์ถ์ ์ ์ค์ฌ์ผ๋ก
ํ์๋
ผ๋ฌธ(์์ฌ) --์์ธ๋ํ๊ต ๋ํ์ :ํ์ ํ๊ณผ(์ ์ฑ
ํ์ ๊ณต),2008. 8.Maste
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