• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2771-2775
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• 2010

We present a rapid biogenic method for the production of nanoscale gold particles using pear extract. The formation and stability of pear-derived gold nanoparticles (Pear-AuNPs) were monitored by ultraviolet-visible spectroscopy. Their morphology, elemental composition and crystalline phase were determined by transmission electron microscopy, energy-dispersive X-ray spectroscopy and selected area electron diffraction. The average core size of crystalline Pear-AuNPs was in the range of $10{\pm}5\;nm$ and the observed morphology was spherical. The X-ray photoelectron spectrum showed a strong peak for the pure 'Au' phase. The circular dichroism spectrum indicated the natural capping ability of the pear extract, which generated peptide-gold nanoparticles. These nanoparticles were stable in aqueous solution for two months. A cell viability assay of Pear-AuNPs showed biocompatibility with human embryonic kidney 293 cells. Accordingly, this eco-friendly process for the bio-mimetic production of Pear-AuNPs is nontoxic in nature; consequently, it will find potential application in nano-biotechnology.

• Journal of Periodontal and Implant Science
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• 제23권3호
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• pp.507-516
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• 1993

The Chlorhexidine(CHX) has been a widely used adjunt in periodontal therapy due to its bactericidal effect. In spite of the effects of CHX exhibits cytotoxic to human cells and delays granulation tissue formation. Therefore, understanding the effects of CHX on fibroblast attachment and cell growth will provide the rationale for its use during healing phase of periodontal surgery. This study was undertaken to examine the effects of standardized CHX-pretreated dentin slices and direct CHX exposure on human gingival fibroblasts. The results were as follow : 1. In experiment 1, there was a significant reduction in the number of fibroblast attachment in 0.12, 1%-pretreated groups relative to the control, 0.05%-pretreated groups(P<0.05). 2. In experiment 1, the control, 0.05%-pretreated groups showed considerable attachment and typical fibroblastic morphology, but 0.12, 1%-pretreated groups showed irregular, round-up (unattached) fibroblastic morphology. 3. In experiment 2, it appeared that all experimental groups exhibits significant inhibition of cell growth when compared with the control group.

• Journal of Plant Biology
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• 제37권1호
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• pp.53-67
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• 1994

대표적인 규소축적 식물 중에 하나인 벼(Orzy sativa)의 규소체를 기관별로 광학현미경과 주사전자현미경 하에서 조사하였다. 또한 규소체의 명칭에 대하여 가능한 기원조직에 근거하여 정리하였다. 벼의 조사된 주요 기관 7개 부위, 즉 엽신, 엽초, 줄기, 뿌리, 포영, 호영, 그리고 내영에서 특징적인 규소체가 확인되었다. 각 기관에 형성된 규소체 중 특히 장세포 기원의 규소체, 단세포 기원의 규소체 그리고 표피부속체 기원의 규소체 등은 기관별로 그 형태가 다양하게 나타났다. 또한 엽신에서는 벼의 다른 기관에서 형성되는 대부분의 규소체가 형성되는 것으로 밝혀졌다.

• Journal of Microbiology and Biotechnology
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• 제26권6호
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• pp.1011-1017
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• 2016

The antimicrobial effects of methanol and ethanol extracts of Inula britannica against several Helicobacter pylori strains (26695, J99, and SS1) were evaluated in vitro, to determine their applicability as functional foods. In the paper disc diffusion method, the antimicrobial effects of the I. britannica extracts against the H. pylori strains were apparent. Viable cell counting also showed that the extracts at 100 μg/ml concentration dramatically decreased the viability of the H. pylori strains. In particular, the methanol and ethanol extracts at a concentration of 100 μg/ml reduced the H. pylori SS1 cell number to 2.46 log CFU/ml and 1.08 log CFU/ml, respectively. In the presence of 100 μg/ml extracts, the urease production of H. pylori SS1 was decreased to more than 30%, whereas that of H. pylori J99 and H. pylori 26695 was decreased to about 20%, relative to the controls. The extracts inhibited the attachment of the H. pylori strains to human gastric AGS cells as well as caused the detachment of already attached H. pylori cells. In addition, the H. pylori morphology was changed to a coccoidal shape in the presence of the extracts. In conclusion, the I. britannica extracts were effective against H. pylori strains in vitro, irrespective of genotype status, and could therefore be used as novel functional foods.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.183-186
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• 2006

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si AR layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layer were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The surface morphology of porous Si layers were investigated using SEM. The formation of a porous Si layer about $0.1{\mu}m$ thick on the textured silicon wafer result in an effective reflectance coefficient $R_{eff}$ lower than 5% in the wavelength region from 400 to 1000nm. Such a surface modification allows improving the Si solar cell characteristics.

• 한국화재소방학회논문지
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• 제20권4호
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• pp.110-115
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• 2006

폴리우레탄에 인계 화합물을 첨가하여 폴리우레탄폼을 제조하였으며, 인계 화합물이 제조된 폴리우레탄폼의 기계적 물성과 난연성에 미치는 영향에 대하여 고찰하였다. 폴리우레탄과 인계 난연제인 Tri(chloroisopropyl) phosphate(TCPP), Triethyl phosphate(TEP), Trimethyl phosphate(TMP) 각각을 약 $90^{\circ}C$에서 혼합시켜 혼합물로부터 제조된 경질 폴리우레탄폼에 대한 여러 실험을 통하여 기계적 물성뿐만 아니라 난연 효과도 상당히 향상됨을 확인하였다. Cone calorimeter를 이용하여 열방출율(heat release rate, HRR)을 측정하여 난연 첨가제의 함량에 따른 재료별 난연 특성을 평가하였다. 그리고 Scanning Electron Microscope(SEM)을 사용하여 난연제를 첨가하여 만든 폴리우레탄폼의 morphology를 관찰한 결과 순수한 폼과 마찬가지로 매우 균일한 형태의 cell 분포를 가짐을 확인하였다.

• 한국미생물·생명공학회지
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• 제17권3호
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• pp.231-235
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• 1989

부착성 동물세포인 recombinant human embryonic kidney cell line 293을 5% FBS가 함유된 DME/F12(3:1) mixture 배지에서 배양할 경우 static culture에서와는 달리 미립담체 배양에서는 낮은 부착효율과 spreading의 저해현상이 관찰되었다. Cell line 293의 미립담체 배양에 있어서 배지내의 serum은 세포의 미립담체에 대한 부착속도(attach-ment rate)를 감소시킬 분만 아니라 세포의 증식을 저해한다는 사실을 확인하였다. 이러한 경우, conditioned microcarrier를 이용함으로써 미립담체로부터 세포의 탈착을 어느 정도 막을 수 있었다. 특히 autocrine growth factor를 생성하는 hepatoma cell line인 HpG 2 cell을 배양하여 얻은 conditioned medium을 serum-free medium에 첨가하여 사용함으로써 세포의 정상적인 성장 분만 아니라 growth-stimulation을 유도할 수 있었다.

• Macromolecular Research
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• 제16권5호
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• pp.404-410
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• 2008

In order to obtain 'value added products' from polypropylene (PP)/waste ground rubber tire powder (WGRT) composites, PP/WGRT microcellular foams were prepared via supercritical carbon dioxide. The effects of blend composition and processing condition on the cell size, cell density and relative density of PP/WGRT micro-cellular composites were studied. The results indicated that the microcellular structure was dependent on blend composition and processing condition. An increased content of waste ground rubber tire powder (WGRT) and maleic anhydride-grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) reduced the cell size, and raised the cell density and relative density, whereas a higher saturation pressure increased the cell size, and reduced the cell density and relative density. With increasing saturation temperature, the cell size increased and the relative density decreased, whereas the cell density initially increased and then decreased.

• 대한예방한의학회지
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• 제13권2호
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• pp.39-50
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• 2009

Objectives : In order to evaluate the cytotoxicity of 3,4,5-trihydroxybenzoic acid and related compounds on the growth of normal cell lines and human oral epithelioid cell line, cell viability, cell adhesion ability, and morphological changes of cells were examined. Methods : We measured the cytotoxicity of 3,4,5-trihydroxybenzoic acid and related compounds with 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyltetrazolium bromide-[MTT), and 2,3-bis-[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium -5-caboxanilide-[XTT) methods. Results : The cytotoxicity of 3,4,5-trihydroxybenzoic acid($IC_{50}$, $2,552.40\;{\mu}M$) was low according to the toxic criteria. Cytotoxic effect of 3,4,5-trihydroxybenzoic acid and related compounds against $IC_{50}$ value in cell morphology increased in a concentration-dependent manner. In light microscopy, $100\;{\mu}M$ 3,4,5-trihydroxy-benzoic acid showed th highest cytotoxic activity. Conclusions : These results suggest that 3,4,5-trihydroxybenzoic acid may have a potential anticancer activity.

• Applied Microscopy
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• 제12권1호
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• pp.23-32
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• 1982

Caulubacter is distinctive in the morphology and replication and ubiquitous in the biosphere, especially in every type of aquatic environment. In water and waste-water treatment processes, chlorine and chlorine compounds have been used as a main disinfectant throughout the world. Therefore, Caulobacter in the waters should be affected by chlorination of the waters. The objective of this study is to determine the effects of the disinfectants on Caulobacter cells and on the developmental processes of the cells. The Caulobacter swarmer cells were disinfected by chlorine at pH 7.0 minutes of the reaction with 2.0 mg/l of infected at pH 10.0. The swarmer cells treated with 2.0 or 4.0 mg/l of chlorine for 15 minutes lost their flagella and were observed by electron microscopy to be damaged on their cell surfaces, discharging some cellular materials. When the chlorinated swarmers and untreated control samples were recultivated in fresh PYE broth medium, the control swarmers multiplicated exponentially after one-hour lag phase, whereas the chlorinated swarmers extended the lag phase to about four hours. During the extended lag phase, the cells were proved by electron microscopy to be grown and be in predivisional step, but no swarmer cell was found. When the stalked cells were chlorinated, almost all the cells were observed to have their stalks broken and some cellular materials discharged. In those samples recultivated, many cells differentiated to possess an abnormally elongated stalk with several crossbands on it. This suggests that the chlorine-shocked Caulobacter cells can develope to abnormal morphology in water environments which they can survive and regrow in.