• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.822-829
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• 2011

Evidence shows that probiotic bacteria can undergo substantial structural and morphological changes in response to environmental stresses, including antibiotics. Therefore, this study investigated the effects of penicillin G (0.015, 0.03, and 0.06 mg/l) on the morphology and adhesion of Lactobacillus acidophilus ATCC 4356, including the colony morphotype, biofilm production, hydrophobicity, $H_2_O2$ formation, S-layer structure, and slpA gene expression. Whereas only smooth colonies grew in the presence of penicillin, rough and smooth colony types were observed in the control group. L. acidophilus ATCC 4356 was found to be hydrophobic under normal conditions, yet its hydrophobicity decreased in the presence of the antibiotic. No biofilm was produced by the bacterium, despite testing a variety of different culture conditions; however, treatment with penicillin G (0.015-0.06 mg/l) significantly decreased its production of $H_2_O_2$ formation and altered the S-layer protein structure and slpA gene expression. The S-protein expression decreased with 0.015 mg/l penicillin G, yet increased with 0.03 and 0.06 mg/l penicillin G. In addition, the slpA gene expression decreased in the presence of 0.015 mg/l of the antibiotic. In conclusion, penicillin G was able to alter the S-layer protein production, slpA gene expression, and certain physicochemical properties of Lactobacillus acidophilus ATCC 4356.

• Environmental Engineering Research
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• 제22권1호
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• pp.61-74
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• 2017

This study investigated the effect of various cations ($Ca^{2+}$, $Mg^{2+}$, $Al^{3+}$, $Mn^{2+}$, $Zn^{2+}$) on the autoaggregation (AAg) and surface hydrophobicity (SHb) of three different bacteria (Brevibacillus panacihumi strain (ZB1), Lysinibacillus fusiformis strain (ZB2) and Enterococcus faecalis strain (ZL)) using a 2-level factorial design. The AAg ratio was measured from the changes in the absorbance of the media. Results show that ZB2 had maximum AAg for the three bacteria investigated. A microscopic clustering of cells was observed when $Ca^{2+}$ was added to ZB2. The AAg was in the range of 62%, 58% and 34% for ZB2, ZB1 and ZL, respectively and correlated to the SHb. The aggregation and SHb of the microbial cells increased with increasing ionic strength due to the repulsive steric or overlap forces between the polymer covered surfaces. $Ca^{2+}$ demonstrated a more significant effect on aggregation and SHb of microbial cells due to an attractive binding force.

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1120-1126
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• 2007

This study was performed to screen probiotic bifidobacteria for their ability to bind and neutralize lipopolysaccharides (LPS) from Escherichia coli and to verify the relationship between LPS-binding ability, cell surface hydrophobicity (CSH), and inhibition of LPS-induced interleukin-8 (IL-8) secretion by HT-29 cells of the various bifidobacterial strains. Ninety bifidobacteria isolates from human feces were assessed for their ability to bind fluorescein isothiocyanate (FITC)-labeled LPS from E. coli. Isolates showing 30-60% binding were designated LPS-high binding (LPS-H) and those with less than 15% binding were designated LPS-low binding (LPS-L). The CSH, autoaggregation (AA), and inhibition of LPS-induced IL-8 release from HT-29 cells of the LPS-H and LPS-L groups were evaluated. Five bifidobacteria strains showed high levels of LPS binding, CSH, AA, and inhibition of IL-8 release. However, statistically significant correlations between LPS binding, CSH, AA, and reduction of IL-8 release were not found. Although we could isolate bifidobacteria with high LPS-binding ability, CSH, AA, and inhibition of IL-8 release, each characteristic should be considered as strain dependent. Bifidobacteria with high LPS binding and inhibition of IL-8 release may be good agents for preventing inflammation by neutralizing Gram-negative endotoxins and improving intestinal health.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.886-889
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• 2001

Silicone rubber is being used for the housing material of outdoor high voltage insulators such as composite insulator, bushing, surge arrestor and cable terminator because of good tracking and erosion resistance, good hydrophobicity and recovery of hydrophobicity and chemical stability. But, the leakge current occurs on surface of the composite polymeric insulation materials when the insulator is used for a long time with severe contaminative condition and it can lead the contamination flashover. So the leakage current is important to estimate the condition of the silicone rubber surface. In this paper, aging characteristics of silicone rubber used for outdoor insulation have been hydrophobicity of silicone rubber in salt fog chamber with average leakage current monitoring for observing the transformation of surface degradation properties of silicone rubber with different ATH(alumina trihydrate, A1$_2$O$_3$$.$3H$_2$O) filler contents. The experimental results show that a higher peak leakage current and to raise a long time for tracking with increasing amount of ATH by the salt fog and heat recycle ageing.

• International Journal of Oral Biology
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• 제41권4호
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• pp.209-215
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• 2016

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.

• 한국식품조리과학회지
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• 제6권4호통권13호
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• pp.9-14
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• 1990

The emlsifying properties of small red bean protein isoates were evaluated through their emulsion capacity and stability of the resulting emulsions. The influence of pH, Sodium Chloride and heat treatment on the efficiency of small red bean protein isolates as emulsifying agents was studied. The surface hydrophobicity (So) of small red bean protein islates also examined. The results were obtained as follows; 1. The emusion capacity of small red bean protein isolates was high at pH 11, low at pH 3 and decreased by heat treament. With addition of NaCl, emulsion capacity decreased steadily and showed lowest value when 0.2M NaCl was added. 2. The emulsion stability at pH 4.5 and heat treatment over $60^{\circ}C$ decreased emulsion stability at pH 4.5. When NaCl was added, emulsion stability was generally increased. 3. The surface hydrophobicity of small red bean protein isolates showed the highest value at pH 3 and lowest at pH 11 and increased as the heating temperature increased When 0.2 M NaCl was added, surface hydrophobicity also increased at pH 4.5.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2302-2304
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• 1999

The application of polymeric insulators for outdoor use has been increasing as a new replacement of overhead line in abroad. In domestic case, it is actively going on the research of polymeric insulators. The Silicone rubber among polymeric insulators have a good electrical properties, due to surface hydrophobicity. This paper is concentrated on the recovery of surface hydrophobicity and the change of surface construction after electrical stress. The feature of silicone rubber, a good hydrophobicity, is demanded the improvement method as the estimation of the non-ceramic insulators like it.

• 폴리머
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• 제30권2호
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• pp.108-111
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• 2006

본 연구에서는 아크릴계 고분자의 소수성 차이에 따른 막 모폴로지 변화를 조사하였다. 막은poly(methyl methacrylate)(PMMA), poly(ethyl methacrylate)(PEMA), poly(butyl methacrylate)(PBMA), poly(isobutyl, methacrylate)(PIBMA) 및 이들의 블렌드를 사용하여 습식 상 역전 방법으로 제조하였다. 상대적으로 소수성이 적은 PMMA와 PEMA는channel-like 형태의 막 구조를, 소수성이 큰 PBMA와 PIBMA는 finger-like 형태의 막 구조를 보여주었다. 이러한 막 구조의 변화는 polymer-rich상의 고상화 과정에서 속도론적 차이가 있었기 때문이었다. 이성분 블렌드 막의 구조는 주 성분 고분자에 의해 결정되었다.

• 마이크로전자및패키징학회지
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• 제27권2호
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• pp.27-32
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• 2020

Robust and hydrophobic tetraethoxysilane (TEOS) based silica aerogel was synthesized by supercritical alcohol drying with surface modification using the phenyl based silica co-precursor (PTMS). The aerogels were synthesized by hydrolysis and polycondensation reaction in which TEOS and PTMS in methanol were reacted together in presence of oxalic acid and ammonium hydroxide as the catalysts. Supercritical alcohol dried PTMS/TEOS composite silica aerogel were examined for the hydrophobicity, chemical interaction, surface morphology, and textural characteristics. The hydrophobic silica-based aerogels were characterized by Fourier transform infrared spectroscopy to investigate the presence of functional groups and chemical bonds. The prepared silica demonstrates hydrophobicity (76°-149°), a high specific surface area (398 ㎡/g to 739 ㎡/g). The present investigation provides a simple approach to synthesize hydrophobic and thermally stable silica aerogels.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.495-496
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• 2008

This paper describes the influence of Ultra-violet irradiation on time to tracking resistance of epoxy insulating materials by use of the inclined plane test. And, the influence of surface degradation was evaluated through several method such as measurement of contact angle, surface roughness, using a scanning electron microscopy. As the 1000 hours of the surface degradation with UV-CON, the flashover time decreases at different rates depending on epoxy resin and silicone rubber specimen. As the duration of the surface degradation with UV-CON is prolonged, the contact angle of epoxy resin decreases at the rate of degradation time, while that of silicone rubber was not exchanged. It is assumed that this phenomenon is related to the decrease in hydrophobicity of the surface of the materials. Also, as to epoxy resin, the decrease of hydrophobicity due to surface degradation with UV-CON is greater than that resulting from surface degradation with WOM. The UV radiation produced chalking and crazing on the surface of the insulating materials specimen.