Regulatory characteristics of the vibrio vulnificus global regulators, CRP, RpoS, and Fur, essential for its survival and pathogenesis

이현중 韓國外國語大學校 大學院 2008 국내박사

In pathogenic bacterium, the ability to acquire iron, which is mainly regulated by the ferric uptake regulator (Fur), is essential to maintain growth as well as its virulence. In Vibrio vulnificus, a human pathogen causing gastroenteritis and septicemia, fur gene expression is positively regulated by Fur when the iron concentration is limited (Lee et al., 2003. J. Bacteriol. 185:5891-5896). Footprinting analysis revealed that an upstream region of the fur gene was protected by Fur protein from DNase I under iron-depleted conditions. The protected region, from -142 to -106 relative to the transcription start site of the fur gene, contains distinct AT-rich repeats. Mutagenesis of this repeated sequence resulted in abolishment of binding by Fur. To confirm the role of this cis-acting element in Fur-mediated control of its own gene in vivo, fur expression was monitored in V. vulnificus strains using a transcriptional fusion containing the mutagenized Fur-binding site (furmt::luxAB). Expression of furmt::luxAB showed that it was not regulated by Fur and was not influenced by iron concentration. Therefore, this study demonstrates that V. vulnificus Fur acts as a positive regulator under iron-limited conditions by direct interaction with the fur upstream region. Bacterial ability to acquire iron is essential to maintain its growth as well as to elicit its virulence, which is regulated by a transcriptional regulator, ferric uptake regulator (Fur). In the previous report (H.?J. Lee et al. 2007 J Bacteriol 189:2629), fur gene expression in Vibrio vulnificus was shown to be activated by a direct binding of iron-free Fur to the upstream region of the fur gene, which includes two direct repeats of 5'-AAATTGT-3'. These finding led us to question if this novel Fur-binding site is unique in autoregulation of fur expression, or it is widely distributed in V. vulnificus genome. Thus, in this study, the V. vulnificus-DNA microarray was utilized to define the Fur-regulon. Total 188 orfs were differentially expressed in ?fur; expression of 38 orfs were significantly reduced in ?fur, and expression of 150 orfs were significantly increased in ?fur. Then, the upstream regions of those orfs were subjected to in silico analysis for the presence of the direct repeats of 5'-AAATTGT-3? or the presence of the classical Fur-box (5?-GATAATGATAATCATTATC-3?). To verify the role of this novel Fur-binding site sequence, 8 genes were chosen for further study. The primer extension assays were performed to identify the promoter regions of the selected genes. Then, transcription fusions including the putative regulatory region for each gene were constructed. Fusion assays showed that expression of each fusion was consistent with the expression patterns determined by DNA microarray experiments. In addition, the putative novel Fur-binding sites were mutagenized and then used for construction of transcriptional fusions. Expression of the mutagenized fusions containing Fur-activated genes were no longer regulated by Fur or an iron chelator, 2, 2'-dipyridyl. However, the fusions containing Fur-repressive genes were not affected by mutation of the sequences homologous the direct repeats of AAATTGT. Instead, these Fur-repressive genes includes the classical Fur-binding sites in their promoter regions. Therefore, the direct repeats of 5'-AAATTGT-3' appears to be the consensus Fur-binding site which is involved in activation by an iron-free Fur. In the natural environment, microorganisms are often challenged by exposure to various forms of physical stress, including oxidative stresses, osmotic shock, temperature shock, and iron or nutrient starvation. Under these conditions, bacteria turn on expression of certain genes that allow them to cope with the given stresses. One of the effective mechanisms for bacteria to bring about such a major switch in gene expression is a selective utilization of alternative sigma subunits that alter the specificity of core RNA polymerase to promoters of target genes or operons (Ishihama, 2000). RpoS (?S) that is a subunit of RNA polymerase complex, is involved in gene expression for responses to general stress and the stationary phase, and is highly conserved in bacteria belonging to the ?-subdivision of Proteobacteria. Recent studies demonstrated that expression of rpoS- and ?S-dependent genes are not only induced at the stationary phase but also induced during the exponential phase for responses to diverse stresses (Hengge-Aronis, 1996; Hengge-Aronis et al., 1993; Lee et al., 1995; Loewen and Hengge-Aronis, 1994; Muffler et al., 1997; Muffler et al., 1996). Although ?S protein levels are low during the exponential phase, relatively high levels of rpoS mRNA are present and do not seem to change in response to several stresses that actually result in strongly elevated levels of ?S protein. Therefore, extensive investigation into the mechanism of translational control of rpoS and proteolysis of ?S has been conducted. There are also several studies that have investigated transcriptional regulation of the rpoS gene. Interestingly, the ferric uptake regulator, Fur, appears to be part of the RpoS regulon (Lee et al., 2003). The Fur protein is a 17-kDa polypeptide that acts as a transcriptional regulator of iron-regulated promoters by Fe2+-dependent DNA binding activity (Bagg and Neilands, 1987). Fur appears to be an abundant protein, which acts as a multimer through protein-protein interactions. The Fur protein can perform multiple functions including regulation, activation, and repression according to iron availability. In some Gram-negative bacteria, the Fur repressor is known to be involved in autoregulation in response to iron (Delany et al., 2002; Delany et al., 2003; Sala et al., 2003). Vibrio vulnificus, a septicemia-causing pathogenic bacterium, has been found to acquire resistance against various stresses and to elicit expression of virulence factors via a rpoS gene product. In this study, we investigated the transcriptional characteristics of this global regulator. Two distinct transcriptional initiation sites for the rpoS gene, the proximal promoter (Pp) and the distal promoter (Pd), were defined by Northern blot and primer extension experiments. The luxAB-transcriptional fusions containing various lengths of the rpoS upstream region indicated that Pd is a major promoter for the rpoS expression. Western blot analysis showed that RpoS amounts were inversely correlated with the intracellular levels of 3',5'-cyclic monophosphate (cAMP). The expressions from both Pd and Pp were increased in the cya or the crp mutants. An exogenous addition of cAMP to the cya mutant resulted in repressed expression of rpoS. In addition, rpoS expression was significantly lowered in the cpdA mutant in which the level of cAMP was elevated due to a deficiency in 3',5'-cAMP phosphodiesterase. cAMP-CRP complex was shown to bind to two rpoS promoters by electrophoretic mobility shift assays. The alteration of the putative CRP-binding site on each rpoS promoter, via a site-directed mutagenesis, abolished the binding of cAMP-CRP as well as the regulation by cAMP-CRP. Therefore, this study clearly shows a relationship between the intracellular cAMP level and the degree of rpoS expression, and further demonstrates, for the first time, the direct binding of cAMP-CRP complex to rpoS upstream regions, which results in repression of rpoS gene expression.

(The) effect of visual and aural input enhancement for Korean high school EFL learners

Lee, Jung Hyun Sungkyunkwan University 2013 국내석사

Anti-cancer mechanisms of the biologically active substances from Orostachys japonicus in human colon cancer cells

Lee, Hyun-Ji 인제대학교 대학원 2023 국내박사

Among the causes of death in Korea, deaths due to cancer are increasing day by day. Although chemotherapy is usually used for the treatment of cancers, chemotherapy has serious side effects that cause toxicity even to normal cells. Therefore, in recent years, studies to find new substances that exhibit specific anti-cancer activity with fewer side effects from natural products have been actively conducted. Flavonoids are polyphenolic compounds derived from plants, and various physiologically active effects of them such as anti-oxidant, anti-thrombotic, anti-inflammatory, anti-diabetic, anti-cancer, and neuroprotective effects are known. Orostachys japonicus is a herbaceous plant of the Crassulaceae family and has been used for anti-inflammation, hemostasis, and detoxification since old times, and its efficacy in various cancers has recently been known. In this study, OJE, an ethyl acetate (EtOAc) fraction of O. japonicus, was used to systematically identify the mechanism of anti-cancer activity in HT-29 human colon cancer cells. Thus, by treating HT-29 cells with kaempferol, quercetin, astragalin, afzelin, quercitrin, and isoquercitrin, which are presumed to be physiologically active substances derived from OJE, this study focused on exploring the effects of substances fron OJE alone or in combination on proliferation, apoptosis, cell cycle arrest, invasion, and metastasis of cancer cells. As a result of performing MTS assay by treating HT-29 cells with various substances presumed to be physiologically active substances derived from OJE alone or in combination, it was confirmed that the proliferation of HT-29 cells was effectively inhibited in a concentration and time-dependent manner. In addition, in order to visually confirm the anti-cancer activity of substanses from OJE on HT-29 cells, DAPI nuclear staining, detection of cell membrane structural changes by Annexin V-FITC, and DNA content measurement by PI staining were carried out. It was confirmed that OJE significantly inhibited cell proliferation in a concentration-dependent manner and induced apoptosis. As a result of direct visual observation of apoptotic bodies through DAPI nuclear staining, chromatin condensation and cell blebbing were confirmed in the kaempferol, quercetin, and OJE-treated groups compared to the control group. As a result of Annexin V-FITC/PI staining, cell viability decreased and apoptosis was induced in a concentration-dependent manner in OJE-treated groups compared to the control group. Bcl-2 is a protein that functions to safeguard cells against diverse apoptotic triggers by inhibiting the release of cytochrome c from mitochondria, and a reduction in this protein level enhances the progression of apoptosis. In addition, caspase-3 is the final executioner caspase that performs apoptosis, caspase-9 is activated by endogenous factors such as intrinsic stress, and caspase-8 is activated by extrinsic signals, caspase-12 is activated by endoplasmic reticulum stress, and all of them induce apoptosis by finally activating caspase-3. As a result of confirming the expression quantity of apoptosis-related proteins by western blotting, the expression levels of bcl-2, procaspase-3, procaspase-8, procaspase-9, and procaspase-12 decreased in a concentration-dependent manner, while the expression levels of bax, cleaved caspase-3, and cleaved caspase-9 increased in a concentration-dependent manner. In addition to apoptosis, another indicator of anti-cancer activity is cell cycle arrest. After treating HT-29 cells with OJE at different concentrations, the expression levels of proteins regulating cell cycle arrest was confirmed using western blotting. The expression of CDK2, CDK4, cyclin A2, and cyclin D1, which are proteins related to G1/S phase, decreased in a concentration-dependent manner. After treating HT-29 cells with OJE at concentration, anti-metastatic activity was examined using western blotting and wound healing assay. As a result, the expression levels of integrin β1, ZO-1, claudin-1, and mmp-9 decreased in a concentration-dependent manner, and the migration of cancer cells was also inhibited in a concentration-dependent manner. After treating HT-29 cells with OJE at different concentrations, the activation of ERK, JNK, and p38, which promote apoptosis and cell cycle arrest in the upstream signal transduction pathway through phosphorylation increased in a concentration-dependent manner. After treating HT-29 cells with OJE at different concentrations, lamin A and C, which constitute the nuclear membrane, and PARP, which perform DNA repair, all in the downstream pathway decreased in a concentration-dependent manner. Therefore, since OJE shows clear anti-cancer activity in the HT-29 colon cancer cells, it is highly likely that it can be used as anti-cancer products to help treat patients suffering from various cancers. 한국인의 사망원인 중 암으로 인한 사망이 나날이 늘어나고 있다. 현재 암의 치료에는 보통 화학요법이 사용되고 있지만, 화학요법은 정상 세포에도 독성을 일으키는 부작용이 심각하다. 그리하여 최근에는 부작용이 적으면서 특이적인 항암 활성을 나타내는 신물질을 천연물에서 찾으려는 연구가 활발히 진행되고 있다. 플라보노이드는 식물에서 유래된 폴리페놀 계열의 화합물로, 항산화, 항혈전, 항염증, 항당뇨, 항암, 신경 보호와 같은 다양한 생리 활성 효과가 알려져 있다. 와송(瓦松, Orostachys japonicus)은 돌나무과의 초본 식물로 예로부터 염증, 지혈, 소종, 해독 등에 사용되어 왔고, 최근 각종 암에도 그 효능이 알려지고 있다. 본 연구에서는 O. japonicus의 ethyl acetate (EtOAc) 분획물인 OJE를 사용하여 HT-29 인체 대장암 세포에서의 항암 활성 기작을 체계적으로 규명하였다. 즉, OJE와 와송 유래 생리 활성 물질로 추정되는 kaempferol, quercetin, astragalin, afzelin, quercitrin 및 isoquercitrin을 HT-29 세포에 처리하여 암세포의 증식, 세포사멸, 세포 주기 정지, 침윤과 전이에 대한 효과를 집중적으로 탐구하였다. HT-29 세포에 OJE와 와송 유래 생리 활성 물질로 추정되는 여러 가지 물질을 단독 또는 혼합 처리하여 MTS assay를 수행한 결과, 농도 및 시간 의존적으로 HT-29 세포의 증식을 효과적으로 억제하는 것을 확인할 수 있었다. 또한, OJE의 HT-29 세포에 대한 항암 활성을 가시적으로 확인하기 위하여, DAPI 핵 염색, Annexin V-FITC에 의한 세포막 구조 변화의 검출, PI 염색에 의한 DNA 함유량 측정을 확인한 결과, OJE가 농도 의존적으로 세포 증식을 유의하게 억제하며, 세포사멸을 유발함을 확인할 수 있었다. DAPI 핵 염색을 통해 직접 육안 관찰을 수행한 결과, 대조군에 비해 kaempferol, quercetin 및 OJE 처리군에서 핵 내의 염색질 응축과 세포질 팽창 등을 확인할 수 있었다. Annexin V-FITC/PI 염색 결과, OJE처리군에서 대조군과 비교하여 세포 생존율은 감소하고, 세포사멸이 농도 의존적으로 증가하였다. Bcl-2는 미토콘드리아 내 cytochrome c의 방출을 억제시켜 다양한 세포사멸 자극으로부터 세포를 보호하는 역할을 수행하는 단백질로서 이 단백질의 감소는 세포사멸을 가속화시킨다. 또한, caspase-3은 세포사멸을 수행하는 최종 caspase이며, caspase-9는 세포 내 스트레스 등의 내재적 요인에 의해 활성화되고, caspase-8은 외인적 신호를 매개로 활성화되며, caspase-12는 소포체 스트레스에 의하여 활성화되는데 이들은 모두 caspase-3을 최종적으로 활성화시켜 세포사멸을 유도한다. 세포사멸 관련 단백질의 발현 정도를 western blotting으로 확인한 결과, bcl-2, procaspase-3, procaspase-8, procaspase-9, procaspase-12 단백질의 발현은 농도 의존적으로 감소하였으며, bax, cleaved caspase-3, cleaved caspase-9 단백질의 발현은 농도 의존적으로 증가하였다. 세포사멸 이외에 항암 활성의 또 다른 지표가 되는 것이 세포 주기 정지이다. HT-29 세포에 OJE를 농도별로 처리한 후, 세포 주기 정지를 조절하는 단백질들을 western blotting을 이용하여 발현 정도를 확인한 결과, G1/S기와 관계된 단백질인 CDK2, CDK4, cyclin A2 및 cyclin D1의 발현이 농도 의존적으로 감소하였다. HT-29 세포에 OJE를 농도별로 처리한 후, 항전이 활성을 western blotting과 wound healing assay를 이용하여 살펴본 결과 integrin β1, ZO-1, claudin-1 및 mmp-9의 발현이 농도 의존적으로 감소하였으며, 암세포의 이동도 농도 의존적으로 억제되었다. HT-29 세포에 OJE를 농도별로 처리한 후, 신호전달의 상위 경로를 확인한 결과 세포사멸과 세포 주기 정지를 촉진하는 ERK, JNK 및 p38의 인산화에 의한 활성화가 농도 의존적으로 증가하였다. OJE를 농도별로 처리한 후, 신호전달의 하위 경로를 확인한 결과 핵막을 구성하는 lamin A와 C 및 DNA 수선을 수행하는 PARP가 모두 농도 의존적으로 감소하였다. 따라서 OJE는 HT-29 대장암 세포주에서 분명한 항암 활성을 보이므로, 다양한 암종으로부터 고통 받는 환자를 치료하는 데 도움을 주는 항암 소재로 활용될 수 있는 가능성이 매우 높다고 사료된다.

Inhibitory effect of plant essential oils on Malassezia furfur and Malassezia pachydermatis causing various disease in human hair scalp

Lee, Jeong Hyun Kwangju Women's University 2011 국내석사

Experimental Investigation of Thermal Dispersion under Forced Groundwater Flow through Lab-Scale Tests to Design an Optimal GWHP system

Lee, Bo-Hyun 서울대학교 대학원 2016 국내석사

Due to the direct use of groundwater as a heat source/sink, the efficiency of GWHP system depends on hydrological and thermal properties of the aquifer in a complex manner. Although a few studies have been conducted to identify key factors affecting the performance of the system, most of them did not focus on thermal properties but flow conditions and well arrangement. However, thermal dispersion was recently recognized for its significance in the high flow field which can be commonly induced by GWHP systems. Therefore, it is needed to further research on how thermal dispersion affects the heat transport in GWHP systems. In this research, a laboratory device simulating the heat transport in saturated porous medium was designed to investigate thermal dispersion behavior under forced groundwater flow conditions. The main goal of this study is to compare the thermal dispersion coefficient in forced flow environments with that in natural flow environments through lab-scale heat tracer tests and further simulations using two different heat sources: (a) a resistor and (b) water injection. The longitudinal/transverse thermal dispersion coefficients under natural flow condition were derived from the tests with a resistor. A linear dependency of the coefficients on flow velocity was examined in this study probably due to the flow conditions being limited to conduction-dominated flow environment (Pet < 1). Thermal dispersion coefficients computed from numerical simulations using the model validated with water-injection tests showed higher values because of the disturbance in flow velocity field. The increase of thermal dispersion coefficients compared to the natural flow condition (without-injection) became larger in the lower regional flow velocity with the higher injection rate. This implicate that the influence of thermal dispersion in navigating thermal plume movement can be significant in the forced flow field, especially when the groundwater flow is slow and the operated injection rate is high. Therefore, it is important to give careful consideration to the adoption of thermal dispersion value when assessing the heat transport with water injection. Otherwise, the oversight of thermal dispersion term may cause a critical error in predicting thermal plume movement in forced flow fields.

Chemical constituents of armoracia rusticana and rosa multiflora and their neuroprotective activities

Lee, Taehyun Sungkyunkwan university 2021 국내박사

As a part of our ongoing search for bioactive constituents from Korean medicinal plants, the roots of A. rusticana and the twigs of R. multiflora were investigated. The investigation resulted in the isolation and characterization of 39 compounds from the roots of A. rusticana and 28 compounds from the twigs of R. multiflora. The structures of the isolated compounds were elucidated through spectroscopic analysis, including NMR (1H and 13C NMR, 1H-1H COSY, HSQC, HMBC, and NOESY), spectrometric analysis (LC-MS and HRESIMS), and chemical methods. Moreover, the configurational assignment was conducted using experimental and calculated ECD and LC-MS analysis. The isolated compounds from the roots of A. rusticana were identified as 2-allyl-8-hydroxy-3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazole-1-one (A-1), 2-allyl-8-hydroxytetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (A-2), 8-hydroxy-2-phenylethyl-3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazole-1-one (A-3), 8-hydroxy-2-phenylethyltetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (A-4), horsethiohydantoin (A-5), (S)-2-phenylethyltetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (A-6), horseradiurea (A-7), (S)-(-)-spirobrassinin (A-8), phenethyl cyanide (A-9), N-(2-phenylethyl)urea (A-10), horseramide A (A-11), 4-(methylsulfinyl)butanenitrile (A-12), 6-(methylsulfinyl)hexanenitrile (A-13), 7-(methylsulfinyl)heptanenitrile (A-14), 8-(methylsulfinyl)octanenitrile (A-15), 9-(methylsulfinyl)nonanenitrile (A-16), 10-(methylsulfinyl)decanenitrile (A-17), 9-(methylsulfinyl)nonanoic acid (A-18), 8-(methylsulfonyl)octanenitrile (A-19), 9-(methylsulfonyl)nonanenitrile (A-20), kaempferol (A-21), kaempferol 3-O-β-D-glucopyranoside (A-22), kaempferol 3-O-β-D-galactopyranoside (A-23), kaempferol 3-O-α-D-arabinopyranoside (A-24), kaempferol 3-O-β-D-xylopyranoside (A-25), horseradiside A-C (A-26 ~ A-28), kaempferol 3-O-β-D-xylopyranoside-7-β-D-glucopyranoside (A-29), kaempferol 3-O-β-D-xylopyranosyl-(1′′′→2′′)-β-D-glucopyranoside (A-30), kaempferol 3-O-β-D-xylopyranosyl-(1′′′→2′′)-β-D-galactopyranoside (A-31), kaempferol 3-O-β-D-apiofuranosyl-(1′′′→2′′)-β-D-glucopyranoside (A-32), nicotiflorin (A-33), kaempferol 3-O-β-D-glucopyranoside-4′-β-D-glucopyranoside (A-34), (7S,8R)-3′-demethyl-dehydrodiconiferyl alcohol-3′-O-β-D-glucopyranoside (A-35), horseradiside D (A-36), lariciresinol-4′-O-β-D-glucoside (A-37), lariciresinol-4-O-β-D-glucoside (A-38), and (+)-lariciresinol-4,4′-O-bis-β-D-glucopyranoside (A-39). Consequently, compounds A-1 ~ A-7, A-11, A-26 ~ A-28, and A-36 were confirmed as new compounds. Furthermore, the structures of the isolated compounds from the twigs of R. multiflora were identified as jillenidin A-C (R-1 ~ R-3), procyanidin B6 (R-4), procyanidin B5 (R-5), rosaside A (R-8), catechin (R-9), (+)-catechin 7-O-β-D-glucopyranoside (R-10), (+)-catechin 5-O-β-D-glucopyranoside (R-11), (+)-catechin 4′-O-β-D-glucopyranoside (R-12), rosaside B (R-13), citrusin A (R-14), 4-[(1R,2S)-1,3-dihydroxy-2-[4-[(1E)-3-hydroxy-1-propen-1-yl]-2-methoxyphenoxy]propyl]-2-methoxyphenyl β-D-glucopyranoside (R-15), rosaside C (R-16), methyl 3,4-dihydroxy-5-[[6-O-(3,4,5-trihydroxybenzoyl)-β-D-glucopyranosyl]oxy]benzoate (R-17), methyl gallate 3-O-β-D-glucopyranoside (R-18), rosaside D (R-19), 2,4,6-trimethoxyphenyl β-D-glucopyranoside (R-20), leonuriside A (R-21), betulin (R-22), lupeol (R-23), pomolic acid (R-24), corosolic acid (R-25), maslinic acid (R-26), arjunolic acid (R-27), and hederagenin (R-28). All of the isolated compounds were evaluated for their potential neurotrophic activity through induction of nerve growth factor (NGF) in C6 glioma cell lines and their anti-neuroinflammatory activity based on the measurement of inhibition levels of nitric oxide (NO) production in lipopolysaccharide (LPS)-activated microglia BV-2 cells. Compounds A-1b, A-2a, and A-7 were mainly exhibited potent neurotrophic activities (stimulation levels: 153.59 ± 5.44, 141.99 ± 5.21, and 157.06 ± 2.23%, respectively) and compounds A-21 ~ A-25, A-27, A-31, A-32, and A-35 were showed powerful NGF secretion with the stimulation levels of 167.08 ± 3.53, 143.56 ± 1.94, 154.01 ± 7.84, 159.45 ± 1.41, 153.36 ± 17.30, 129.09 ± 13.73, 176.96 ± 2.58, 174.48 ± 2.10, and 170.03 ± 0.64%, respectively. Furthermore, compound A-7 exhibited potent NO inhibition effect with an IC50 value of 19.83 μM. Besides, R-8, R-13, and R-21 exhibited moderate anti-neuroinflammatory activities with IC50 values of 51.52, 50.58, and 44.32 μM, respectively. 국내 자생하는 천연식물로부터 새로운 퇴행성 신경질환 치료제의 개발을 위한 노력의 일환으로 수종의 국내 자생 식물을 채취하여 신경보호 prescreening 방법을 사용하여 Nerve Growth Factor (NGF, 신경성장인자) 분비유도활성과 Nitric Oxide (NO, 신경염증 유발인자) 생성억제활성을 평가하였다. 그 결과 Armoracia rusticana (겨자무)의 뿌리와 Rosa multiflora (찔레나무)의 가지에서 유의한 활성이 확인되었고, 두 식물들로부터 신경영양인자 분비유도 및 신경염증 억제활성에 대한 성분 연구를 수행하였다. 먼저, A. rusticana (겨자무) 뿌리의 신경보호 성분 연구를 수행하였다. 그 결과 80% 메틸알콜 추출물로부터 얻어진 분획물 중 클로로포름 분획에서 6종의 새로운 thiohydantoin 성분과 5종의 새로운 hydantoin 성분, 1종의 새로운 hydantoinurea 성분, 그리고 1종의 새로운 methyl sulfinyl derivative 성분을 포함한 총 20종의 물질이 분리되었다. 이와함께 에틸아세테이트 및 n-부틸알콜 분획에서 3종의 새로운 kaempferol 배당체성분과 1종의 새로운 lignin 배당체를 포함한 11종의 성분이 분리되었다. 분리된 39 종의 성분들은 그들의 이화학적 성상 및 기기분석결과를 통해 그 구조를 2-allyl-8-hydroxy-3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazole-1-one (A-1), 2-allyl-8-hydroxytetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (A-2), 8-hydroxy-2-phenylethyl-3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazole-1-one (A-3), 8-hydroxy2-phenylethyltetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (A4), horsethiohydantoin (A-5), (S)-2-phenylethyltetrahydro-1Hpyrrolo[1,2-c]imidazole-1,3(2H)-dione (A-6), horseradiurea (A-7), (S)-(-)-spirobrassinin (A-8), phenethyl cyanide (A-9), N-(2-phenylethyl)urea (A-10), horseramide A (A-11), 4-(methylsulfinyl)butanenitrile (A-12), 6-(methylsulfinyl)hexanenitrile (A13), 7-(methylsulfinyl)heptanenitrile (A-14), 8-(methylsulfinyl)octanenitrile (A-15), 9-(methylsulfinyl)nonanenitrile (A-16), 10-(methylsulfinyl)decanenitrile (A-17), 9-(methylsulfinyl)nonanoic acid (A18), 8-(methylsulfonyl)octanenitrile (A-19), 9-(methylsulfonyl)nonanenitrile (A-20), kaempferol (A-21), kaempferol 3-Oβ-D-glucopyranoside (A-22), kaempferol 3-O-β-D-galactopyranoside (A-23), kaempferol 3-O-α-D-arabinopyranoside (A-24), kaempferol 3-O-β-D-xylopyranoside (A-25), horseradiside A-C (A-26 ~ A-28),kaempferol 3-O-β-D-xylopyranoside-7-β-D-glucopyranoside (A-29),kaempferol 3-O-β-D-xylopyranosyl-(1′′′→2′′)-β-D-glucopyranoside (A-30), kaempferol 3-O-β-D-xylopyranosyl-(1′′′→2′′)-β-Dgalactopyranoside (A-31), kaempferol 3-O-β-D-apiofuranosyl-(1′′′→2′′)-β-D-glucopyranoside (A-32), nicotiflorin (A-33), kaempferol 3-O-β-Dglucopyranoside-4′-β-D-glucopyranoside (A-34), (7S,8R)-3′-demethyldehydrodiconiferyl alcohol-3′-O-β-D-glucopyranoside (A-35),horseradiside D (A-36), lariciresinol-4′-O-β-D-glucoside (A-37),lariciresinol-4-O-β-D-glucoside (A-38), 그리고 (+)-lariciresinol-4,4′-O-bis-β-D-glucopyranoside (A-39)로 구조규명 하였고, 위 성분들에 대한 신 경영양인자 분비활성과 신경염증인자 분비억제 활성을 평가하였다. 그 결과 화합물 A-1b, A-2a, 그리고 A-7에서 매우 강한 NGF 분비유도활성이 확인되었다. (stimulation levels: 153.59 ± 5.44, 141.99 ± 5.21, 그리고 157.06 ±2.23%). 이와함께 화합물 A-21 ~ A-25, A-27, A-31, A-32, 그리고 A-35에서 매우 강한 NGF 분비유도활성이 확인되었다 (stimulation levels: 129.09 ± 13.73- 176.96 ± 2.58%). 흥미롭게도, 화합물 A-7에서는 매우 강한 NO생성 억제활성 또한 확인할 수 있었다 (IC50 19.83 μM). 다음으로, R. multiflora (찔레나무)의 가지에 대한 신경보호 성분 연구를 수행하였다. 그 결과, 80% 메틸알콜 추출물로부터 얻어진 분획물 중 에틸아세테이트, n부틸알콜, 그리고 클로로포름 분획에서 5종의 새로운 biflavonoid 성분들과 1종의 새로운 flavanol 배당체, 1종의 새로운 lignin 배당체, 그리고 2종의 새로운 phenolic 배당체를 포함한 총 28종의 물질이 분리되었다. 분리된 28 종의 성분들은 그들의 이화학적 성상 및 기기분석결과를 통해 그 구조를 jillenidin A-C (R-1~ R-3), procyanidin B6 (R-4), procyanidin B5 (R-5), rosaside A (R-8), catechin (R-9), (+)-catechin 7-O-β-D-glucopyranoside (R-10), (+)-catechin 5-O-β-D-glucopyranoside (R-11), (+)-catechin 4′-O-β-Dglucopyranoside (R-12), rosaside B (R-13), citrusin A (R-14), 4-[(1R,2S)-1,3-dihydroxy-2-[4-[(1E)-3-hydroxy-1-propen-1-yl]-2-methoxyphenoxy]propyl]-2-methoxyphenyl β-D-glucopyranoside (R-15),rosaside C (R-16), methyl 3,4-dihydroxy-5-[[6-O-(3,4,5-trihydroxybenzoyl)-β-D-glucopyranosyl]oxy]benzoate (R-17), methylgallate 3-O-β-D-glucopyranoside (R-18), rosaside D (R-19), 2,4,6-trimethoxyphenyl β-D-glucopyranoside (R-20), leonuriside A (R-21), betulin (R-22), lupeol (R-23), pomolic acid (R-24), corosolic acid (R-25), maslinic acid (R-26), arjunolic acid (R-27), 그리고 hederagenin (R-28)로 구조규명 하였고, 위 성분들에 대한 신경영양인자 분비활성과 신경염증인자 분비억제활성을 평가하였다. 그 결과 화합물 R-8, R-13, 그리고 R-21에서 NO생성 억제를 통한 약하지만 유의한 항신경염증활성이 관찰되었다 (51.52, 50.58, 그리고 44.32 μM). 이상의 연구를 통하여 A. rusticana (겨자무)의 뿌리와 R. multiflora (찔레나무)의 가지로부터 총 26 종의 새로운 화합물 (6종의 thiohydantoin, 5종의 hydantoin, 1종의 hydantoinurea, 1종의 methyl sulfinyl derivative, 4종의 flavonoid 배당체, 2종의 lignan 배당체, 5종의 biflavonoid, 1종의 flavanol 배당체, 1종의 lignin 배당체 그리고 2종의 phenolic 배당체 성분)을 포함한 총 67종의 성분을 분리하여 그 구조를 규명하였다. 구조규명을 완려한 후에는 신경영양인자 (NGF) 분비유도활성과 신경염증인자 (NO) 생성억제활성을 평가하였다. 분리된 물질 중 16 종의 물질에서 유의성 있는 신경영양인자 (NGF) 분비유도활성 또는 신경염증인자 (NO) 생성억제활성을 확인하였고, 특히 화합물 A-7 (horseradiurea)는 신경영양인자(NGF) 분비유도활성과 신경염증인자 (NO) 생성억제활성 모두에서 매우 강한 활성을 나타내었다. 두 신경보활성평가의 결과는, 화합물 A-7이 향후 신경보호활성의 약물을 개발함에 있어 매우 유망한 후보물질로의 가능성을 나타낸것으로 판단된다.

Boosting efficiency and stability of low-intensity indoor organic photovoltaics via morphological modification using two compatible non-fullerene acceptors

Lee, Junghyun Sungkyunkwan University 2022 국내석사

Morphological modification in non-fullerene blends is demonstrated to boost the efficiency and stability of indoor organic photovoltaics (OPVs). Here, we devised a strategy to improve morphology in photoactive layer and minimize charge recombination loss by using two compatible non-fullerene acceptors of IT-4F and ITIC-Th. Notably, under low-intensity indoor conditions, suppression of trap-assisted recombination through morphological modification contributes to enhancing OPV performance. The optimal ternary OPV achieves a power conversion efficiency of 30.11% under a 500 lux light emitting diode with superior morphological durability at the thermal treatment. We also developed a smart module for real-time temperature measurement and control by utilizing an indoor OPV module with ternary blend system. This study demonstrates the effect of morphology on OPV performance under low light conditions and proposes an ideal morphology for non-fullerene OPVs with enhanced performance for indoor applications. 비풀러렌 블랜드의 형태학적 변형은 실내 유기 태양 전지 발전의 효율과 안정성을 높이는 것으로 입증되었습니다. 여기서, 우리는 호환성이 우수한 두 비풀러렌 수용체인 IT-4F 와 ITIC-Th를 사용하여 광 활성층의 형태를 개선하고 전하 재결합 손실을 최소화하는 전략을 고안하였습니다. 특히, 저강도 실내 조건에서 형태학적 변형을 통한 trap-assisted 재결합 억제는 유기 태양 전지의 성능을 향상시킵니다. 최적의 터너리 시스템의 유기 태양 전지는 500 lux 실내 광 조건에서 30.11 %의 전력 변환 효율을 달성하였으며, 동시에 열적 조건에서의 형태학적 내구성을 함께 보였습니다. 또한 터너리 시스템을 갖춘 실내 OPV 모듈을 활용하여 실시간 온도 측정 및 제어를 위한 스마트 모듈을 개발했습니다. 이 연구는 저조도 실내 광 조건에서 향상된 성능을 가진 비풀러렌 유기 태양 전지에 대한 이상적인 형태를 제안합니다.

(A) 20 MS/s 12-bit charge sharing type SAR ADC for RF beamforming

Lee, Junghyun Sungkyunkwan University 2022 국내석사

This thesis presents a charge sharing analog to digital converter(ADC) with high speed and high resolution to be used for the wide bandwidth of 20 to 160 MHz for RF beamforming transceivers, which regard to be important at the semiconductor markets. SAR ADC, which is a structure of ADCs, has not only high resolution of 10 to 12 bits and tens of mega samplings per a second, but also low power consumption. However, the settling time of SAR ADCs with tens of MS/s has to be lower than 0.5 LSB. Moreover, the comparator operates in a short time to compare the difference between the input voltages of comparator. To solve the difficulty of the fast operation, this work purposes a 20 MS/s 12-bit charge sharing SAR ADC with 8 channels. Charge sharing DAC was designed with a large unit capacitor for the low capacitor thermal noise and low threshold voltage devices for the low on resistance. The proposed ADC was designed by 13 0nm CMOS process, which had the size of 1600 μm by 505 μm. For the input frequency of 5 MHz at the process of TT and 27 °C, the designed ADC has the ENOB of 10.64-bit and the SNDR of 65.82 dB with the current consumption of 8.172 mA for 8-channel. 본 논문에서는 반도체 시장에서 중요하게 여겨지는 RF Beamforming Transceiver의 20~160 MHz 채널 대역폭을 처리하기 위한 고속 동작 속도와 고해상도를 가진 전하 공유(Charge Sharing) 아날로그/디지털 변환기 구조를 제안한다. 아날로그/디지털 변환기 구조 중 SAR 구조는 10~12 bit의 해상도와 수십 MS/s의 속도를 가지며, 낮은 소비전력을 갖는다. 그러나 수십 MS/s로 동작하기 위해, ADC의 Settling time은 0.5 LSB 내로 만족해야 하며, 비교기 입력의 차이를 짧은 시간 내에 비교 동작을 완료해야 한다. 빠른 동작을 해결하기 위해, 본 논문에서는 8 채널에 대한 Charge Sharing SAR 구조의 아날로그/디지털 변환기를 통해 20 MS/s의 동작 속도와 12 bit 해상도를 목표로 한다. Charge Sharing DAC은 커패시터의 낮은 열잡음을 위한 큰 단위 커패시터와 낮은 온저항을 위한 Low Threshold Voltage 소자를 사용하여 설계하였다. 제안하는 아날로그/디지털 변환기는 130 nm CMOS 공정으로 설계하였으며, 8채널에 대한 면적은 1600 μm x 505 μm이다. 5 MHz의 입력 신호에 대한 ENOB 성능은 10.64 bits, SNDR 성능은 65.82 dB 이고, 8채널에 대한 소비 전류는 8.172 mA 이다.

Analysis of user-generated visual content that leads to brand identity cocreation : case of customer engagement from brand space

이강현 Graduate School, Yonsei University 2021 국내박사

Enhanced random access scheme with timing advance adjustment for massive machine type communications

Lee, Byunghyun Graduate School, Yonsei University 2019 국내석사

최근 5세대 통신 기술의 표준화가 진행됨에 따라, 대규모 기기간 통신 환경에서 일어나는 랜덤 액세스 채널 과부하 문제가 대두되고 있다. 본 논문에서는 대규모 기기간 통신환경에서 일어나는 랜덤 액세스 채널 과부하 문제를 해결하기 위 향상된 랜덤 액세스 기법을 제시한다. 먼저 프리앰블 전송에서 타이밍 어드밴스 조절을 통해 프리앰블 자원의 수를 효과적으로 증가 시킬 수 있는 프리앰블 확장 기법을 제안한다. 또한, 타이밍 어드밴스 조절이 프리앰블 검출 성능에 미치는 영향을 조사하기 위하여 매틀랩 기반의 링크 레벨 시뮬레이션을 실시한다. 다음으로, 추가 적인 하향링크 제어 채널 자원의 사용 없이 더욱 많은 랜덤 액세스 응답 메시지를 보내기 위한 경량 랜덤 액세스 응답 메시지 구조를 제안한다. 이에 더하여, 랜덤 액세스 응답 메시지를 받지 못하여 프리앰블을 재전송 하는 단말을 줄이기 위한 자원 할당 대기 기법을 제안한다. 우리는 제안 랜덤 액세스 기법의 성능을 측정하기 위하여 다중 랜덤 액세스 채널 슬롯에서의 분석 모델을 제안한다. 마지막으로, 네트워크 시뮬레이터를 통한 시스템 레벨 시뮬레이션을 실시하여 제안된 분석 모델을 검증한다. In this thesis, we propose a Random Access (RA) scheme to alleviate the Random Access CHannel (RACH) overload problem in the massive Machine Type Communication (mMTC) environment. We then propose a TA-based Preamble Resource Expansion (TAPRE) scheme which effectively increases preamble resources to decrease the preamble collision probability.We demonstrate a link level simulation for the preamble detection at the Next Generation EnodeB (gNB) to evaluate the feasibility of TAPRE. Furthermore, we also propose a light Random Access Response (RAR) message structure to reduce the size of RAR payload. Then, we propose a Resource Allocation Wait (RAW) scheme which efficiently reduce the number of MTCDs that perform back-off due to the failure of RAR reception. Our analysis shows that the performance of the proposed RA scheme is superior to the RA scheme in NR. We validate our analysis with the system level simulation based on NS-3. Simulation results show that the average number of successful MTCDs with their RA procedures is significantly increased compared to that of NR. Moreover, average access delay, preamble collision probability, RAR reception probability and average number of preamble transmissions are also reduced with our proposed RA scheme.