• Advances in nano research
• /
• v.4 no.4
• /
• pp.281-294
• /
• 2016

The advantages of nano-scale materials (size 1-99 nm in at least in one dimension) could be realized with their potential applications in diversified avenues. Herein, we report for the first time on the successful synthesis of homogeneous epoxy coatings containing phytogenic silver nanoparticles (Ag) on PVC and glass substrates by room-temperature curing of fully mixed epoxy slurry diluted by acetone. Alstonia scholaris bark extract was used to reduce and stabilize the silver ions. The surface morphology and mechanical properties of these coatings were characterized using the techniques like, UV-Vis (UV-Visible) spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FT-IR), Epifluorescence microscopy and scanning electron microscopy (SEM). The effect of incorporating Ag nanoparticles on the biofilm (scale) resistant epoxy-coated PVC was investigated by total viable counts ($CFU/cm^2$) from epoxy coating from (Initial) $1^{st}$ day to $25^{th}$ days. The phytogenic Ag nanoparticles were found to be significantly improving the microstructure of the coating matrix and thus enhanced the anti-biofilm performance of the epoxy coating. In addition, the antimicrobial mechanism of Ag nanoparticles played an important role in improving the anti-biofilm performance of these epoxy coatings.

• Corrosion Science and Technology
• /
• v.17 no.6
• /
• pp.257-264
• /
• 2018

Anti-graffiti coatings have become more important. These layers must guarantee excellent corrosion protection properties, and graffiti must be easily removable, without reducing protection and aesthetic properties. In this study, anti-graffiti and corrosion behavior of two anti-graffiti polyurethane powder coatings were studied. These layers were deposited on aluminum substrate, with two different surface finishes, smooth, and wrinkled. The action of four different removers are investigated. Graffiti were drawn on coatings by means of red acrylic spray paint. Methyl-ethyl-ketone (MEK) and a "commercial" remover were the most effective solvents, in terms of graffiti removal capability, producing limited change in aesthetical surface aspect for smooth finishing. The wrinkled surface was less resistant. Corrosion protection properties, after removal action and contact with the remover, were evaluate by electrochemical impedance spectroscopy. After approximately 5 hours, coatings were no longer protective due to formation of defects. To simulate the weathering effect, UV-B cyclic test (4 hours of UV exposure followed by 4 hours of saturated humidity at $50^{\circ}C$) were performed for 2000 hours. Gloss and color changes were measured, and electrochemical impedance spectroscopy measurements were performed after aging and graffiti removal.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.2
• /
• pp.226-236
• /
• 2020

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21^st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 ㎍/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 ㎍/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 ㎍ of AgNPs/ml, the pigment production was reduced by about 15-100%, respectively.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.2
• /
• pp.154-159
• /
• 2000

This study was carried out to elucidate the symptom of leaf injury to ozone and to determine varietal difference to ozone injury in rice and soybean plant. Ozone was produced by electrostatic discharge in oxygen and was monitored by UV absorption ozone analyzer. The rice leaves were spotted red and rolling leaf edge, discolored to reddish brown or yellowish white in response to ozone, and the leaves that were severely stressed were withered from the tip of leaf. The soybean ones were also discolored to lemon yellow, yellow or dark brown. The leaf injury in both rice and soybean was clearly appeared at the reverse side of leaf and in lower leaves. Milyang 23 and Nonganbyeo among rice cultivars tested were resistant to ozone, but Chucheongbyeo was resistant to it. The ratio of leaf injury was increased and chlorophyll content was decreased as the extension of ozone exposure from 2 to 8 hours in rice. Keunolkong and Danyeopkong among soybean cultivars tested showed resistant reaction to ozone, but Kwangankong and Muhankong were susceptible to it. It was observed that the soybean plants grown for 45 days after seeding were severely damaged by ozone than those of other growth stages.

• Microbiology and Biotechnology Letters
• /
• v.13 no.2
• /
• pp.163-167
• /
• 1985

To investigate the condition for the protoplast fusion of Streptococcus lactis, streptomycin(200 $\mu\textrm{g}$/$m\ell$) resistant and rifampicin (200$\mu\textrm{g}$/$m\ell$) resistant mutants were isolated. By using these markers, protoplast fusion was carried out in the presence of CaCl$_2$ and polyethylene glycol. The optimal conditions for the protoplast fusion were obtained by treatment of protoplasts with 150 mM CaCl$_2$ (final concentration; 25 mM) and 40％ (w/v) PEG 4, 000 for 2 min. At the optimal conditions, the fusion frequency was 6.26$\times$10$^{-5}$ . On the other hand, genetic recombination between the antibiotic resistant mutants by mating was not observed.

• Microbiology and Biotechnology Letters
• /
• v.7 no.3
• /
• pp.165-173
• /
• 1979

Recovery component for cell division in UV-irradiated E. coli B was detected with use of the cell extract of E. coli B/r which is a resistant mutant of E. coli B against UV-irradiation. The active substance was non-dialyzable and increased the activity by adding B-NAD remarkably. One more factor for increasing or promoting the restoration recognized was magnesium. Magnesium was effective to stabilze the substance in procedure of isolation. Two active substances were obtained from sucrose gradient centrifugation. One of them was recovred from the botton area and the other from top area just below below surface. the former was not stabilized by magnesium, while the latter stabilized the activity by it remarkably. The former which did not require magnesium was insensitive to protease and the latter which required magnesium was sensitive to it. Both were insensitive to RNase and DNase. Recovery ratio was doubled by using nitrogen gas than aeration in purification process. DNA-ligase less mutant was revealed same activity on it's recovery ratio with the parent strain of E. coli K-12. The active substance stimulating the filament cell may exist as a complex which is inactivated easily in the dissociated state ana requrie B-NAD or magnesium.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.1
• /
• pp.111-114
• /
• 2000

Streptomyces are widespread in nature and play a very important role in the biosynthesis as well as biodegradation of natural and unnatural aromatic compounds. Both qualitatively and quantitatively through TLC and UV spectrophotometric assays, it was observed that the thermophilic soil bacteria S. setonii (ATCC 39116), which can utilize a benzoate as a sole carbon and energy source in a minimal liquid culture, was not very sensitive to the benzoate concentation and to the culture conditions such as the pH and temperature. The in vitro conversion of a catechol to a cis, cis-muconic acid by a crude S. setonii lysate implies that the aromatic ring cleavage by S. setonii is initiated by a thermostable catechol-1,2-dioxygenase, the key enzyme in the ortho-cleavage pathway of aromatic compound biodegradation. Unlike non-degrading S. lividans, S.setonii was also highly resistant to other similar hazardous aromatic compounds, exhibiting almost no adverse effect on its growth in a complex liquid culture.

• Korean Journal of Microbiology
• /
• v.25 no.2
• /
• pp.117-121
• /
• 1987

The ozone-induced reactivation factor for ozonated or UV-irradiated T3 phage was determined in defferent bacterial strains of Escherichia coli B resistant of sensitive to ozone. Our results suggest that ozone is a weak, if any at all, inducer of the Weigle reactivation, one of the SOS functions. This is in agreement with other studies which have suggested that thes agent is probably a weak inducer of the SOS functions.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1995.04a
• /
• pp.68-68
• /
• 1995

청주 근처 토양에서 분리한 에너지 대사 저해제인 2,4-dinitrophenol (DNP)에 내성을 보이는 Streptomyces CM 001 균주가 생산하는 항진균성 물질(CUA)을 순수하게 분리 정제하고 화학분석을 통한 구조의 규명, 항진균활성 연구 및 유전적 변이원성(mutagenicity)등을 살펴보았다. CM 001 균주를 베네트 배지와 같이 영양성이 좋은 배지에서 배양시 항진균 활성이 동반 생성되는 색소와 비례적으로 증가했다. 배양 상등액 속의 항진균성 물질들을 염산처리, 유기용매처리 후 Amberlite XAD-4 column chromatography, silica gel adsorption-Sephadex LH-20 chromatography 과정을 통해 색소가 제거된 부분 정제 백색분말로 얻었다 이로부터 Prep. HPLC과정을 통하여 8종의 화합물을 각기 분리하였는데 이 화합물들은 동일한 UV spectrum과 216, 260nm에서 최대 흡수파장을 보였다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2008.07a
• /
• pp.265-266
• /
• 2008

The environmental and mechanical reliability of planar lightwave circuit (PLC)-type optical splitter modules is investigated with references [1, 3]. The module is composed of Y-branching silica-based waveguides on Si connected to optical fiber with UV-curable adhesives and is packaged in a metal case which is filled with humidity-resistant resin. High optical performance such as low loss, low reflection, and thermal stability are obtained through the use of this fiber connection technique. Ten reliability tests including long-term environmental and mechanical and ALT test were carried out for more then ten $1{\times}32$ channel PLC splitter modules.