Microwave Absorption of λ/4 Wave Absorbers Using High Permeability Magnetic Composites in Quasi-microwave Frequency Band

Yeo-Chun Yun,Kyung-Sub Lee,Sang-Woo Kim,Sung-Soo Kim 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

For the aim of thin electromagnetic wave absorbers used in quasi-microwave frequency band, this study proposes the high-permeability magnetic composite sheets of quarter wavelength thickness (λ/4 spacer) coated with resistive film of 377 Ω/sq (impedance transformer). For the λ/4 spacer, flexible magnetic composite sheets of Fe??Si9.5Al5.5flake particles aligned in rubber matrix are prepared by conventional magnetic composite fabrication technique. Due to high permeability and high permittivity of the composite sheets, λ/4 thickness can be reduced as low as 0.5 ㎜ in 2 ㎓. The microwave absorbance (determined at 2 ㎓) of the magnetic composite sheets are found to be -4.6 ㏈ (65% power absorption) at a λ/4 thickness of 0.5 ㎜. By coating the conductive paste (graphite and carbon black dispersed in polymer resin matrix) on the λ/4 spacer (thickness = 0.5㎜), the microwave absorbance is greatly improved. When the sheet resistance of coated films is close to 377 Ω/sq, the reflection loss is reduced to -11 ㏈ (90% power absorption). This is attributed to the wave impedance matching led by the resistive film of free-space impedance combined with a λ/4 thickness of high-permeability magnetic spacer. It is, therefore, proposed that the resistive film/magnetic composite structure with controlled electrical properties and thickness can be useful as thin microwave absorbers used in quasi-microwave frequency band.

Adsorption characteristics of NH₄-N by biochar derived from pine needles

Yun-Gu Kang,Jun-Young Lee,Jin-Hyuk Chun,Jae-Han Lee,Yeo-Uk Yun,Taek-Keun Oh 충남대학교 농업과학연구소 2021 Korean Journal of Agricultural Science Vol.48 No.3

Evaluation of the Biochars pH on NH₃ Volatilization

Yun-Gu Kang(강윤구),Jin-Hyuk Chun(천진혁),Jae-Han Lee(이재한),Yeo-Uk Yun(윤여욱),Gi-Bum Yi(이기범),Taek-Keun Oh(오택근) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11

Nitrogen (N) is one of the most vital nutrient elements in plant growth. The plant quality and quantity varies depending on the amount of N. However, owing to the moderately low N use efficiencies by the growing crops, a considerably large percentage of it about 10 - 20% is volatilized to the atmosphere as form of NH₃ and N₂O. The volatilized NH₃ reacts with various oxides (NO<SUB>x</SUB>, SO<SUB>x</SUB>) to generate secondary particulate matter (PM2.5). Therefore, this study aimed to assess if biochars pH can impact its capacity of lessening NH3 emitted from the fertilized agricultural fields. Biochar was applied with 1% (w w<SUP>-1</SUP>) while N in form of urea was applied at three different rates of 160, 320, and 640 kg ha<SUP>-1</SUP>. NH₃ was collected using a dynamic chamber method and analyzed following the indophenol blue method after extraction with 2 M KCl solution. Based on the results indicate that the daily NH₃ emissions peaked within 4 - 7 days after fertilizations and decreased sharply afterwards. biochar amendments greatly reduced NH₃ emissions in all the treatments. The greatest reduction of 25% in relation to the control came from the neutral biochar (pH 6.7) applied to the soil fertilized with the 320 kg N ha<SUP>-1</SUP> and is thus, the most effective way of reducing NH3 volatilizations.

Ginsenoside fractions regulate the action of monocytes and their differentiation into dendritic cells

Yeo Jin Lee,Young Min Son,Min Jeong Gu,Ki-Duk Song,Sung-Moo Park,Hyo Jin Song,Jae Sung Kang,Jong Soo Woo,Jee Hyung Jung,Deok-Chun Yang,Seung Hyun Han,Cheol-Heui Yun 고려인삼학회 2015 Journal of Ginseng Research Vol.39 No.1

Background: Panax ginseng (i.e., ginseng) root is extensively used in traditional oriental medicine. It is a modern pharmaceutical reagent for preventing various human diseases such as cancer. Ginsenosidesd-the major active components of ginsengdexhibit immunomodulatory effects. However, the mechanism and function underlying such effects are not fully elucidated, especially in human monocytes and dendritic cells (DCs). Methods: We investigated the immunomodulatory effect of ginsenosides from Panax ginseng root on CD14⁺ monocytes purified from human adult peripheral blood mononuclear cells (PBMCs) and on their differentiation into DCs that affect CD4⁺ T cell activity. Results: After treatment with ginsenoside fractions, monocyte levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 increased through phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK), but not p38 mitogen-activated protein kinase (MAPK). After treatment with ginsenoside fractions, TNF-α production and phosphorylation of ERK1/2 and JNK decreased in lipopolysaccharide (LPS)-sensitized monocytes.We confirmed that DCs derived from CD14⁺ monocytes in the presence of ginsenoside fractions (Gin-DCs) contained decreased levels of the costimulatory molecules CD80 and CD86. The expression of these costimulatory molecules decreased in LPS-treated DCs exposed to ginsenoside fractions, compared to their expression in LPS-treated DCs in the absence of ginsenoside fractions. Furthermore, LPS-treated Gin-DCs could not induce proliferation and interferon gamma (IFN-γ) production by CD4⁺ T cells with the coculture of Gin-DCs with CD4⁺ T cells. Conclusion: These results suggest that ginsenoside fractions from the ginseng root suppress cytokine production and maturation of LPS-treated DCs and downregulate CD4⁺ T cells.

Ginsenoside fractions regulate the action of monocytes and their differentiation into dendritic cells

Yeo Jin Lee,Young Min Son,Min Jeong Gu,Ki-Duk Song,Sung-Moo Park,Hyo Jin Song,Jae Sung Kang,Jong Soo Woo,Jee Hyung Jung,Deok-Chun Yang,Seung Hyun Han,Cheol-Heui Yun 고려인삼학회 2015 Journal of Ginseng Research Vol.39 No.3

Background: Panax ginseng (i.e., ginseng) root is extensively used in traditional oriental medicine. It is a modern pharmaceutical reagent for preventing various human diseases such as cancer. Ginsenosidesdthe major active components of ginsengdexhibit immunomodulatory effects. However, the mechanism and function underlying such effects are not fully elucidated, especially in human monocytes and dendritic cells (DCs). Methods: We investigated the immunomodulatory effect of ginsenosides from Panax ginseng root on CD14⁺ monocytes purified from human adult peripheral blood mononuclear cells (PBMCs) and on their differentiation into DCs that affect CD4⁺ T cell activity. Results: After treatment with ginsenoside fractions, monocyte levels of tumor necrosis factor (TNF)-a, interleukin (IL)-6, and IL-10 increased through phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK), but not p38 mitogen-activated protein kinase (MAPK). After treatment with ginsenoside fractions, TNF-α production and phosphorylation of ERK1/2 and JNK decreased in lipopolysaccharide (LPS)-sensitized monocytes.We confirmed that DCs derived from CD14⁺ monocytes in the presence of ginsenoside fractions (Gin-DCs) contained decreased levels of the costimulatory molecules CD80 and CD86. The expression of these costimulatory molecules decreased in LPS-treated DCs exposed to ginsenoside fractions, compared to their expression in LPS-treated DCs in the absence of ginsenoside fractions. Furthermore, LPS-treated Gin-DCs could not induce proliferation and interferon gamma (IFN-γ) production by CD4⁺ T cells with the coculture of Gin-DCs with CD4⁺ T cells. Conclusion: These results suggest that ginsenoside fractions from the ginseng root suppress cytokine production and maturation of LPS-treated DCs and downregulate CD4⁺ T cells.

Ginsenoside fractions regulate the action of monocytes and their differentiation into dendritic cells

Lee, Yeo Jin,Son, Young Min,Gu, Min Jeong,Song, Ki-Duk,Park, Sung-Moo,Song, Hyo Jin,Kang, Jae Sung,Woo, Jong Soo,Jung, Jee Hyung,Yang, Deok-Chun,Han, Seung Hyun,Yun, Cheol-Heui The Korean Society of Ginseng 2015 Journal of Ginseng Research Vol.39 No.1

Background: Panax ginseng (i.e., ginseng) root is extensively used in traditional oriental medicine. It is a modern pharmaceutical reagent for preventing various human diseases such as cancer. Ginsenosidesd-the major active components of ginsengd-exhibit immunomodulatory effects. However, the mechanism and function underlying such effects are not fully elucidated, especially in human monocytes and dendritic cells (DCs). Methods: We investigated the immunomodulatory effect of ginsenosides from Panax ginseng root on $CD14^+$ monocytes purified from human adult peripheral blood mononuclear cells (PBMCs) and on their differentiation into DCs that affect $CD4^+$ T cell activity. Results: After treatment with ginsenoside fractions, monocyte levels of tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-6, and IL-10 increased through phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK), but not p38 mitogen-activated protein kinase (MAPK). After treatment with ginsenoside fractions, TNF-${\alpha}$ production and phosphorylation of ERK1/2 and JNK decreased in lipopolysaccharide (LPS)-sensitized monocytes.We confirmed that DCs derived from $CD14^+$ monocytes in the presence of ginsenoside fractions (Gin-DCs) contained decreased levels of the costimulatory molecules CD80 and CD86. The expression of these costimulatory molecules decreased in LPS-treated DCs exposed to ginsenoside fractions, compared to their expression in LPS-treated DCs in the absence of ginsenoside fractions. Furthermore, LPS-treated Gin-DCs could not induce proliferation and interferon gamma (IFN-${\gamma}$) production by $CD4^+$ T cells with the coculture of Gin-DCs with $CD4^+$ T cells. Conclusion: These results suggest that ginsenoside fractions from the ginseng root suppress cytokine production and maturation of LPS-treated DCs and downregulate $CD4^+$ T cells.

pncA Mutations in the Specimens from Extrapulmonary Tuberculosis

( Jae Chun Lee ),( Yeo Jun Yun ),( Cheah Yoke Kqueen ),( Jong Hoo Lee ),( Hee Youn Kim ),( Young Ree Kim ),( Yoon Hoh Kook ),( Keun Hwa Lee ) 대한결핵 및 호흡기학회 2012 Tuberculosis and Respiratory Diseases Vol.72 No.6

Background: Pyrazinamide (PZA) is an effective antitubercular drug that becomes toxic to Mycobacterium tuberculosis when converted to pyrazinoic acid by pyrazinamidase (PZase), encoded by mycobacterial pncA. A strong association was noted between the loss of PZase activity and PZA resistance. The causative organisms in extrapulmonary tuberculosis are rarely cultured and isolated. To detect pncA mutations in specimens from extrapulmonary tuberculosis as confirmative diagnosis of mycobacterial infection and alternative susceptibility test to PZA. Methods: Specimens were collected from clinically proven extrapulmonary tuberculosis. pncA was sequenced and compared with wild-type pncA. Results: pncA from 30 specimens from 23 donors were successfully amplified (56.6% in specimens, 59% in donors). Six mutations in pncA were detected (20.0% in amplified specimens, 26.1% in specimen donors) at nucleotide positions of 169, 248 and 419. The mutation at position 169 results in substitution of aspartic acid for histidine, possible allelic variation of M. bovis that have intrinsic PZA resistance. The mutation at position 248 changes proline into arginine and that at position 419, arginine into histidine. Conclusion: DNA-based diagnosis using pncA may be simultaneously useful for the early diagnosis of mycobacterial infection and the rapid susceptibility to PZA in extrapulmonary tuberculosis. A potential implication of pncA allelic variation at 169 might be suggested as a rapid diagnostic test for M. bovis infection or Bacille Calmette-Guerin BCG) reactivation.

Nitrooleate Mediates Nitric Oxide Synthase Activation in Endothelial Cells

Shin, Eunju,Yeo, Eunju,Lim, Jihye,Chang, Yun Hee,Park, Haeryun,Shim, Eugene,Chung, Haeyon,Hwang, Hye Jin,Chun, Jiyeon,Hwang, Jinah Wiley (John WileySons) 2014 Lipids Vol.49 No.5

<P>Nitrated lipids such as nitrooleate (OLA-NO2) can act as endogenous peroxisome proliferator-activated receptor gamma (PPARγ) ligands to exert vascular protective effects. However, the molecular mechanisms regarding nitric oxide (NO) production and its regulation are not fully defined in the vasculature. Here, we show that OLA-NO2 increased endothelial NO release by modulating activation of endothelial nitric oxide synthase (eNOS) in endothelial cells. Treatment with OLA-NO2 (3?μM) increased NO release in a time-dependent manner. OLA-NO2 decreased protein expression of eNOS and caveolin-1 (Cav-1) but increased heat shock protein 90 (Hsp90) expression. Immunoprecipitation analysis confirmed that OLA-NO2 replaced eNOS/Cav-1 with eNOS/Hsp90 interaction, resulting in increasing eNOS activity. OLA-NO2 also induced eNOS phosphorylation at Ser633 and Ser1177 and eNOS dephosphorylation at Ser113 and Thr495. In addition, OLA-NO2 induced phosphorylation of Akt and extracellular signal-regulated protein kinase (ERK1/2), which might contribute to eNOS activation. Collectively, these results substantiate a new functional role for nitrated fatty acid, demonstrating that OLA-NO2 exerts vascular protective effects by increasing NO bioavailability through eNOS phosphorylation/dephosphorylation and interaction with associated proteins such as Hsp90 and Cav-1.</P>

Anti-oxidative and Photo-protective Effects of Coumarins Isolated from Fraxinus chinensis

Lee, Bum-Chun,Lee, So-Yong,Lee, Hwa-Jeong,Sim, Gwan-Sub,Kim, Jin-Hui,Kim, Jin-Hwa,Cho, Young-Ho,Lee, Dong-Hwan,Pyo, Hyeong-Bae,Choe, Tae-Boo,Moon, Dong-Cheul,Yun, Yeo-Pyo,Hong, Jin-Tae 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.10

Free radicals and reactive oxygen species (ROS), which are generated by UV irradiation, may cause serious injury to skin cell membranes, DNA and functional proteins. In addition, these agents stimulate the expressions of matrix metalloproteinases (MMPs), which can degrade most components of the extracellular matrix (ECM), including collagen. In order to develop new anti-photoaging agents, five major components from the extract of Fraxinus chinensis extract (FCE) were identified. Two of the major components of FCE were found to be esculin (11.2%) and esculetin (1.9%). FCE ($IC_{50}:\;50.0{\mu}g/mL$ 1, 1-diphenyl-2-picrylhydrazyl (DPPH); $19.8{\mu}g/mL$, superoxide anion radical) and esculetin ($IC_{50}:\;2.1{\mu}g/mL$ DPPH; $0.6{\mu}g/mL$, superoxide anion radical) showed strong antioxidative activities. Of the compounds tested, esculetin showed the strongest scavenging activity against DPPH radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. The intracellular ROS scavenging activity showed that oxidation of 5-(6-)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate ($CM-H_2DCFDA$) was effectively inhibited by esculetin, with potent free radical scavenging activity was also shown in UVB-irradiated human dermal fibroblasts (HDFs). Moreover, treatment of UVA-irradiated HDFs with esculetin resulted in dose-dependent decreases in the expression levels of MMP-1 mRNA and protein. From these results, FCE and one of its components, esculetin, were predicted to be potentially useful as ingredients in cosmetics for protecting against photoaging.

Adrenal Medullary Hyperplasia with Coexisting Adrenal Cortical Adenoma

Jung Whan Chun,M.D.,Seong Woo Hong,M.D.,Yun Kyung Kang,M.D.<SUP>1<.SUP>,Woo Yong Lee,M.D.,Yeo Gu Jang,M.D. and Byungmo Lee,M.D. 대한갑상선-내분비외과학회 2011 The Koreran journal of Endocrine Surgery Vol.11 No.3

Adrenal medullary hyperplasia is an increase in the mass of the adrenal medullary cells. We report a case of a 38-year-old man presenting with pheochromocytoma-like symptoms who was preoperatively misdiagnosed with pheochromocytoma. Hypertension was associated with an intracranial hemorrhage evident in a brain computed tomography scan, in which no obvious pituitary gland enlargement was detected. An abdominopelvic CT revealed a solitary tumor in the right adrenal gland with no obvious enlargement of the contralateral adrenal gland or sympathetic chains. Lab results showed increased levels of urinary metanephrines. Based on clinical data, the patient underwent a laparoscopic right adrenalectomy bases on a diagnosis of pheochromocytoma. The patient was finally diagnosed with adrenal medullary hyperplasia with coexisting ipsilateral non-functioning adrenal cortical adenoma. Postoperatively, blood pressure and lab results were maintained in the normal range and the patient was symptomatically free during the follow-up period. (Korean J Endocrine Surg 2011;11: 182-185)