• Title/Summary/Keyword: Contact potential

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Optimal Condition of Microporous Membrane for Bone Marrow Stromal Cell Allotransplantation to Stimulate Wound Healing in Vitro (창상치유목적의 골수기질세포 동종이식을 위한 고분자막의 조건)

  • Lee, Eun-Sang;Kim, Myeong-Joo;Han, Seung-Kyu;Hong, Sung-Taek;Kim, Woo-Kyung
    • Archives of Plastic Surgery
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    • v.37 no.5
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    • pp.509-518
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    • 2010
  • Purpose: Major drawbacks of conventional bone marrow stromal cells (BSCs) transplantation method are mainly caused by direct transplanted cell to host cell interactions. We hypothesized that separation of the transplanted cells by a microporous membrane might inhibit most of the potential adverse effects and induce superior effect. The purpose of the study is to determine the optimal condition of the microporous membrane. Methods: First, BSCs were placed in polyethylene terephthalate (PET) transwell inserts with 3, 8, or $12{\mu}m$ pore size, and cultured in 24 well culture plates. After 5 days, bottoms of the plates were observed for presence of attached BSCs in monolayer and cell numbers were evaluated. Second, BSCs were placed PET, polycarbonate (PCT), and mixed cellulose esters (MCE) transwell inserts with 3 and $8{\mu}m$ pore size, and cultured in 24 well culture plates. After 3 days, the supernatants of the media left in culture plate were analyzed for collagen, vascular endothelial growth factor (VEGF), platelet derived growth factor BB (PDGF-BB), and basic fibroblast growth factor (bFGF). Third, BSCs were placed in 15% and 70% of the PET membrane with $3{\mu}m$ pore size. All the experimental conditions and methods were same as the second study. Results: The optimal pore sizes to prevent BSC leakage were $3{\mu}m$ and $8{\mu}m$. The amounts of type I collagen and three growth factors tested did not show significant differences among PET, PCT, and MCE groups. However, the collagen, VEGF, and bFGF levels were much higher in the high (70%) density group than in the low (15%) density group. Conclusion: This study revealed that the optimal pore size of membrane to prevent direct BSC to recipient cell contact is in between $3{\mu}m$ and $8{\mu}m$. Membrane materials and pore sizes do not influence the collagen and growth factor passage through the membrane. The most striking factor for collagen and growth factor transport is pore density of the membrane.

The Characteristics of $V_H$ Gene Family Expression in Early B Cells (어린 B세포가 갖는 $V_H$유전자 발현의 특성)

  • JEONG Hyun Do;HUH Min-Do
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.28 no.1
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    • pp.114-122
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    • 1995
  • Defining the mechanisms of B cell diversification which establish the immune repertoire is fundamental to understand how the immune response is regulated. In this report, B cell differentiation and diversification focused on the regulation of immunoglobulin $V_H$ gene expression during ontogeny were analyzed by in situ hybridization technique. Fetal liver B cells in .different gestational days from 16d to 20d showed the predominant expression of $V_H7183$ and $V_HQ52$ without transition of repertoire during the observed gestation days. The two subsets of fetal liver B cells separated according to different differentiation stages based on the presence of tell surface immunoglobulin also did not indicate apparent difference in expressed $V_H$ gene family profiles. B cells in fetal spleen as an another hematopoietic lymphoid tissue in fetus also expressed similar $V_H$ gene repertoire to that in fetal liver B cells. This distinct pattern of $V_H$ gene expression in fetal B cells from that of adult B cells were not changed even after four weeks contact with adult bone marrow microenvironment supplied by the established adult bone marrow stromal cell layers. Thus, the restricted $V_H$ gene repertoire of B cells in fetus which is distinct from that in adult appears to be associated more with the genetic potential of fetal B cell progenitors and less with environmental influences or differentiation stages or compartmentalization.

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Potential Element Retention by Weathered Pulverised Fuel Ash : I. Batch Leaching Experiments (풍화 석탄연소 고형폐기물(Pulverised Fuel Ash)의 중금속 제거가능성 : I. 뱃치 용출실험)

  • Lee, Sanghoon
    • Economic and Environmental Geology
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    • v.28 no.3
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    • pp.251-257
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    • 1995
  • Three PEA (Pulverised Fuel Ash) samples, which were fresh, 17 and some 40 years weathered, were collected from two major British power plants. Batch leaching tests with these samples using distilled water and simulated industrial leachate showed higher amounts of element liberation from fresh ash, including Ca, Na, K, S (as $SO^{2-}_4$, $Cr_{total}$, Cu, Li Ni, Mo and CI and this seems to indicate their surface association and easier dissolution when contact with water. On the contrary Mg, Al, Ba, Si, V, As and Se do not show such readily leachable concentrations and these elements might be more associated with glass fraction in PFA particle rather than surface. Although element concentrations in the weathered ash are much lower than those in the initial leachate from the fresh ash, elements are still detected as resonable concentrations, with rather constant levels and this seems to demonstrate the element release from unstable glass phase of PFA particle. Fe, Ca, $Cr_{total}$, Cu, Ni, Zn and Hg were removed from the synthetic leachate by PFA and this is also confirmed by gain in solid PFA. The order of element retention is Meaford weathered ash > Drax weathered ash > Drax fresh ash in decreasing order and this conforms with the degree of weathering. Namely, the more wethered, the more wethered, the more effective in metal retention from the synthetic leachate.

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A Study for In-process Monitoring in Press die (프레스금형 형내 모니터링에 대한 연구)

  • Yun, Jae-Woong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.692-696
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    • 2017
  • The shape of press components is becoming increasingly complex due to customer demands, process shortening and cost savings. In addition, the stability of the pressing process frequently varies during mass production due to the influence of many factors. In order to ensure the process stability, it is necessary to establish a process in which reproducibility is realized in tolerance, which is sufficient for advance study of shape, material, press, mold and lubrication. However, unforeseen changes in process parameters cause disruptions in production line shutdowns and production planning. In this paper, we introduce a method to monitor a real time process by applying a sensor to a press mold. A non-contact type sensor for measuring the flow of a sheet material and an example of an experiment using the optical sensor which is highly applicable to mass production are presented. An optical sensor was installed in a cylindrical drawing mold to test its potential application while changing the material, blank holder force, and drawing ratio. We also quantitatively determined that the flow of other sheet materials was quantified locally using a square drawing die and that the measured value was always smaller than the drawing depth due to the material elongation. Finally, we propose a field that can be used by attaching the sensor to the press mold. We hope that the consequent cost reduction will contribute to increasing global mold competitiveness.

Loss of Metalworking Fluids Collected on PVC Filter Due to Contact with Clean Air and Desiccation (PVC필터에 채취된 절삭유의 손실에 관한 연구)

  • Park, Dong-Uk;Ha, Kwon-Chul
    • Analytical Science and Technology
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    • v.14 no.5
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    • pp.451-457
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    • 2001
  • Because liquids with high molecular weight such as mineral oil have low vapor pressure at room temperature, it is generally thought to be difficult to lose them to evaporation. However, when they are dispersed into air in small droplets during application in machining processes, their surface area becomes considerably higher. To determine the potential for metalworking fluids (MWF) filter losses, MWF mist was generated and collected on polyvinyl chloride (PVC) filters in test chamber. After collected MWF was exposed to clean air during designated period (range 10~240 minutes) and the filters were desiccated, losses were evaluated. As duration of clean air passing through PVC filter increased, loss of MWF gradually increased. MWF lost after 10 minutes ranged form 12.4 % to 21.8 % of the original loading mass, on average 53.3 % of the total loss. These results indicate that significant mass of MWF collected on PVC filters can be lost at the beginning of air sampling. Loss of MWF collected on PVC filter also occurred during desiccation without active airflow. In multiple regression to identify which factors influence the loss of MWF collected on PVC filter, both duration of air passing through PVC filter and MWF age (fresh vs. used) were significant predictor (p=0.0001). Therefore, workers' exposure to MWF measured method 0500, may underestimate true concentration. Further study is needed to develop a new method to quantify the workers' exposure to airborne MWF mist accurately.

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Fluoride and nitrate removal in the decentralized water treatment plants by electroadsorption using carbon nano-tube electrodes (소규모 급수 시설의 불소 및 질산성질소 이온 제거를 위한 탄소나노튜브 전극을 활용한 전기흡착 연구)

  • Han, Song-Hee;Chang, In-Soung;Chae, Ki-Woong;Joung, Seun-Young;Lee, Cheol-Ku
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.6
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    • pp.2904-2912
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    • 2011
  • Water qualities in the decentralized water treatment plants do not frequently satisfy the water standard limit, in particular, fluoride and nitrate are notorious for the poor removal. In this study, an electro-adsorption equipped with carbon nonotube (CNT) electrodes were carried out to effectively remove the nitrate and fluoride in the decentralized water treatment plants. Two types of CNT electrodes, coating and sintering electrodes were applied. Coating electrodes were made based on different kinds of binder and sintering electrodes were made based on different sintering temperature. Removal of fluoride and nitrate when the coated electrodes with organic binder were used for electro-adsorption were 46 and 99.9% respectively, which were better performances than the coated electrodes with inorganic binder were used. On the other hand, removal of fluoride and nitrate when the electrodes sintered at higher temperature ($1,000^{\circ}C$) were 77 and 87% respectively, which were better performances than the electrodes sintered at lower temperature ($850^{\circ}C$). As a consequences, the electro-adsorption equipped with a CNT electrodes could be an potential alternative process for the removal of fluoride and nitrate in a decentralized water treatment plants if proper current density and contact time were applied.

Effect of Organic Solvent-Modification on the Electrical Characteristics of the PCBM Thin-Film Transistors on Plastic substrate (플라스틱 기판상에 제작된 PCBM 박막 트랜지스터의 전기적 특성에 대한 유기 용매 최적화의 효과에 대한 연구)

  • Hyung, Gun-Woo;Lee, Ho-Won;Koo, Ja-Ryong;Lee, Seok-Jae;Kim, Young-Kwan
    • Journal of the Korean Applied Science and Technology
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    • v.29 no.2
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    • pp.199-204
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    • 2012
  • Organic thin-film transistors (OTFTs) have received considerable attention because their potential applications for nano-scale thin-film structures have been widely researched for large-scale integration industries, such as semiconductors and displays. However, research in developing n-type materials and devices has been relatively shortage than developing p-type materials. Therefore, we report on the fabrication of top-contact [6,6]-phenyl-C61-butyricacidmethylester (PCBM) TFTs by using three different solvent, o-dichlorobenzene, toluene and chloroform. An appropriate choice of solvent shows that the electrical characteristics of PCBM TFTs can be improved. Moreover, our PCBM TFTs with the cross-linked Poly(4-vinylphenol) dielectric layer exhibits the most pronounced improvements in terms of the field-effect mobility (${\sim}0.034cm^2/Vs$) and the on/off current ratio (${\sim}1.3{\times}10^5$) for our results. From these results, it can be concluded that solvent-modification of an organic semiconductor in PCBM TFTs is useful and can be extended to further investigations on the PCBM TFTs having polymeric gate dielectrics. It is expected that process optimizations using solution-processing of organic semiconductor materials will allow the development of the n-type organic TFTs for low-cost electronics and various electronic applications.

Oral Administration of β-Glucan and Lactobacillus plantarum Alleviates Atopic Dermatitis-Like Symptoms

  • Kim, In Sung;Lee, Seung Ho;Kwon, Young Min;Adhikari, Bishnu;Kim, Jeong A;Yu, Da Yoon;Kim, Gwang Il;Lim, Jong Min;Kim, Sung Hak;Lee, Sang Suk;Moon, Yang Soo;Choi, In Soon;Cho, Kwang Keun
    • Journal of Microbiology and Biotechnology
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    • v.29 no.11
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    • pp.1693-1706
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    • 2019
  • Atopic dermatitis (AD) is a chronic inflammatory skin disease of mainly infants and children. Currently, the development of safe and effective treatments for AD is urgently required. The present study was conducted to investigate the immunomodulatory effects of yeast-extracted β-1,3/1,6-glucan and/or Lactobacillus plantarum (L. plantarum) LM1004 against AD-like symptoms. To purpose, β-1,3/1,6-glucan and/or L. plantarum LM1004 were orally administered to AD-induced animal models of rat (histamine-induced vasodilation) and mouse (pruritus and contact dermatitis) exhibiting different symptoms of AD. We then investigated the treatment effects on AD-like symptoms, gene expression of immune-related factors, and gut microbiomes. Oral administration of β-1,3/1,6-glucan (0.01 g/kg initial body weight) and/or 2 × 1012 cells/g L. plantarum LM1004 (0.01 g/kg initial body weight) to AD-induced animal models showed significantly reduced vasodilation in the rat model, and pruritus, edema, and serum histamine in the mouse models (p < 0.05). Interestingly, β-1,3/1,6-glucan and/or L. plantarum LM1004 significantly decreased the mRNA levels of Th2 and Th17 cell transcription factors, while the transcription factors of Th1 and Treg cells, galactin-9, filaggrin increased, which are indicative of enhanced immunomodulation (p < 0.05). Moreover, in rats with no AD induction, the same treatments significantly increased the relative abundance of phylum Bacteroidetes and the genus Bacteroides. Furthermore, bacterial taxa associated with butyrate production such as, Lachnospiraceae and Ruminococcaceae at family, and Roseburia at genus level were increased in the treated groups. These findings suggest that the dietary supplementation of β-1,3/1,6-glucan and/or L. plantarum LM1004 has a great potential for treatment of AD as well as obesity in humans through mechanisms that might involve modulation of host immune systems and gut microbiota.

Underwriting Method of Worksite Marketing Product (Worksite Marketing 상품과 언더라이팅 기법)

  • Kim, Cheong-Nyun;Chung, Sung-Wan
    • The Journal of the Korean life insurance medical association
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    • v.24
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    • pp.97-117
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    • 2005
  • Internally Korean insurance market is that whole life products' growth are becoming slowdown that's why new insurance products have appeared on the market in consideration of consumer's needs recently. Externally domestic insurance market competitions has drifted from insurance industry to whole financial industry since bankasurance started. Life insurance companies should open up a new market to survive from severe competitions. Worksite marketing can be an alternative. An insurer make arrangements with an employer about an insurance terms which an insurer offers in Worksite marketing. Then eligible individuals enroll in the plans at their own discretion and pay 100 percent of the premium for coverage through payroll deductions. An employer doesn't need to pay extra money for additional benefit but can raise employee's loyalty and satisfaction of company through worksite marketing. An employee can be covered at discounted premium rate and less strict underwriting guidelines to an insurer compared to individual insurance. In developed countries specially U.S insurance market, Worksite marketing is getting very popular and growing rapidly due to the advantages. Worksite marketing has both individual insurance characters and group insurance characters. Individual insurance characters are that employees enroll in the plans at their own discretion and pay 100 percent of the premium for coverage. Group insurance characters are that actively at work and participation etc. An insurer have to reflect these two characters on Worksite marketing when an insurance company work out a plan for developing products and underwriting guidelines. When an insurer devise worksite products, one should consider participation level which means percentage of eligible employees participating. Participation is related to anti-selection. As we know underwriting is essential for every kind of insurance, especially underwriting plays major role in worksite marketing. We can see that in the below. Firstly, it has a function in calculation of premium rate. When calculate premium rate for worksite products underwriters have to estimate expected participation level and risk factors. So underwriters and acturies keep in close contact with each other. Secondly, underwriting methods are important. When an insurer underwrite worksite products, there are three kinds of underwriting methods. These are Simplified issue underwriting, Full underwriting and Guaranteed issue underwriting. Simplified issue underwriting typically requires no medical examination, but usually requires supplying satisfactory answers to one or several health and/or lifestyle questions. Full underwriting requires a complete medical history questionnaire that may further require an exam. Guaranteed issue underwriting means that coverage is issued without the employee having to provide evidence of insurability. When insurer set the GI limit are usually based on the type of industry, number of eligible employees, the average amount of coverage and participation level. In addition to insurer should have a clear definition of eligible employee on the insurance provision and application form. It will minimize possibility of trouble claims and anti-selection. An insurer also establish preexisting condition exclusion and special guidelines for late entrants. When an insurer introduce Worksite marketing to Korean insurance market, an insurer has to examine market research to analyze potential market and strategy of sales most of all. Also an insurer should review real situation of the U.S, England and Japanese market etc. There are a lot of new technologies about worksite marketing process that an insurer should learn. When an insurer consider many things which we explained it can be a real alternative.

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Pb(II) Removal from Aqueous Solutions Using Pinewood and Oakwood (소나무와 참나무를 이용한 Pb(II) 제거)

  • Um, Byung-Hwan;Jo, Sung-Wook;Park, Seong-Jik
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.4
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    • pp.450-459
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    • 2014
  • Crushed pinewood and oakwood were studied as an adsorbent for Pb(II) removal from aqueous solution. Batch adsorption experiments were carried out to describe the effects of contact time, initial Pb(II) concentration, pH, competing cations, and adsorbent dosage on the Pb(II) adsorption process. Kinetic studies revealed that the Pb(II) adsorption process for pinewood and oakwood followed both pseudo first and pseudo second order model. The Fruendlich model best described equilibrium adsorption data with correlation coefficients ($R^2$) of 0.956 and 0.950 for pinewood and oakwood. The maximum adsorption capacity of Pb(II) onto pinewood and oakwood was found to be 16.853 and 27.989 mg/g, respectively. The Pb(II) adsorption onto both pinewood and oakwood was increased as pH increased in the pH range 3-9. The presence of cations such as $Na^+$, $Ca^{2+}$, and $Al^{3+}$ decreased Pb(II) adsorption. The Pb(II) removal was greater in seawater than deionized water, resulting from the presence of $CO{_3}^{2-}$ and $OH^-$ ions in seawater. This study showed that pinewood and oakwood have a potential application in the remediation of Pb(II) contaminated water.