• Title/Summary/Keyword: Disc diffusion test

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A study on Adhesion and Wear Resistance of Vanadium Carbide Coating on Die Steels by Immersing in Molten Borax Bath (용융 붕사욕 침지법에 의해 금형용 강에 형성된 VC coating층의 밀착성과 내마모성에 관한 연구)

  • Lee, B.K.;Nam, T.W.
    • Journal of the Korean Society for Heat Treatment
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    • v.13 no.2
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    • pp.71-84
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    • 2000
  • A study on adhesion and wear resistance of VC(vanadium carbide) coating on die steels, STD11 and STD61, has been carried out. The VC coating on the die steels was made by immersing them in molten borax bath, a kind of TRD(thermo-reactive deposition and diffusion). Adhesion strength and wear resistance were investigated using scratch test, indentation test and plate-disc test(Ogoshi type) respectively. The influence of sliding distance on the amount of wear has been determined and dominant wear mechanisms has been characterized using optical microscopy, scanning electron microscopy and EDS spectroscopy. The critical adhesion strength($L_c$) between VC coating layer and substrate(STD11) was increased to 60N($L_c$) in the scratch test. In the case of STD61, the strength increased to 24N. The wear resistance of VC coated die steels was excellent because the diffusion layer formed just below the coating layer. The dominant wear mechanism was identified as adhesive wear for VC coating die steels which were worn by combination of cracking and plucking of VC fragments and disc.

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Antimicrobial Activity of Methyl Gallate isolated from the Leaves of Glochidion superbum Against Hospital Isolates of Methicillin Resistant Staphylococcus aureus

  • Ahmed, Mohammed Dahiru;Taher, Muhammad;Maimusa, Alhaji Hamusu;Rezali, Mohamad Fazlin;Mahmud, Mohammed Imad Al-deen Mustafa
    • Natural Product Sciences
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    • v.23 no.1
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    • pp.5-8
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    • 2017
  • An antimicrobial compound has been isolated from the leaves of Glochidion superbum. The compound was determined as methyl 3, 4, 5-trihydroxybenzoate (methyl gallate), based on ultraviolet (UV), infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS) analysis. The isolated compound exhibited potent antimicrobial activity against three clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) by qualitative agar disc diffusion method and quantitative broth dilution method. Agar disc diffusion was done in a dose-dependent manner for each bacterial isolate at disc potencies of 25, 50, 100, and $150{\mu}g/disc$. The zones of inhibition were on average equal to 12.27, 14.20, 15.43, and 24.17 mm respectively. The inhibition zones were compared with that of vancomycin disc at $30{\mu}g$ as a reference standard. The MIC and MBC values were $50{\mu}g/ml$ and $100{\mu}g/ml$ respectively. The results of anti MRSA activity were analyzed using one-way ANOVA with Turkey's HSD and Duncan test. In conclusion, methyl gallate which was isolated from G. superbum showed the inhibition activity against methicillin resistant S. aureus.

The trend of antimicrobial resistance of Escherichia coli isolated from healthy volunteers of community and chicken butchers in Incheon (일반인 및 닭도축장 근무자에서 분리한 대장균의 항생제 내성 양상)

  • Hwang, Kyoung-Wha;Kim, Hye-Young;Lee, Mi-Yeon;Koh, Yeon-Ja
    • Korean Journal of Veterinary Service
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    • v.30 no.1
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    • pp.103-113
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    • 2007
  • We monitored antibiotic resistance of Escherichia coli isolates from healthy volunteers of community and chicken butchers from February to July in 2006. From disc diffusion test on 473 E coli isolates from healthy volunteers of the community, the resistance rates of tetracycline, ampicillin, and ticarcillin were 44.8%, 40.8%, and 37.4%, respectively. In the disc diffusion test on 18 E coli isolates from chicken butchers, the resistance rates of tetracycline, nalidixic, streptomycin, and ampicillin were 94.4%, 61.1%, 55.6%, and 50.0%, respectively.

Antimicrobial Activity against Food Hazardous Microorganisms and Antimutagenicity against Salmonella serotype Typhimurium TA100 of an Ethanol Extract from Sanguisorba officinalis L. (지유 에탄올 추출물의 식품 위해성 세균에 대한 항균 활성 및 Salmonella serotype Typhimurium TA100에 대한 항돌연변이 활성 효과)

  • Kim, Se-Ryoung;Won, Ji-Hye;Kim, Mee-Ra
    • Korean journal of food and cookery science
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    • v.27 no.4
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    • pp.17-26
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    • 2011
  • This study was performed to analyze the antibacterial activity against food hazardous microorganisms and antimutagenic effects of Sanguisorba officinalis L. ethanol extracts on Salmonella Typhimurium TA100. The antibacterial activity was evaluated by paper disc diffusion assay, minimum inhibition concentration (MIC), and optical density of the culture with the ethanol extract for 24 hr. Antibacterial activity was tested with seven microorganisms including Escherichia coli, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. The paper disc diffusion assay showed distinct clear inhibition zones around the discs treated with the extract for five microorganisms, except Escherichia coli and Escherichia coli O157:H7. MIC values were 0.625-2.5 mg/mL for these five strains that showed clear zones. The time-kill assay was consistent with the results from the paper disc diffusion assay and MIC test. Additionally, antimutagenicity of the extract was determined using the Ames test. The ethanol extract at 5 mg/plate inhibited 72.42% and 89.85% of mutagenicity induced by 4-nitroquinoline 1-oxide and sodium azide, respectively. These results demonstrate that the ethanol extract from S. officinalis L. has remarkable antibacterial activity and antimutagenicity.

Screening of the Antibacterial Effects by Ethanol Extracts from Natural Plant in Jeju against Propionibacterium acnes (Propionibacterium acnes에 대한 제주 자생식물 에탄올 추출물의 항균효과 검색)

  • Ko, Mi-Ok;Kang, Hee-Joo;Hwang, Joon-Ho;Yang, Kyong-Wol
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.44 no.1
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    • pp.59-66
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    • 2018
  • Propionibacterium acnes, a major pathogens bacterium of acne, is one of the microflora associated with the inflammation. In this study, the antibacterial effects of 70% ethanol extracts from the 61 natural plants in Jeju against P. acnes were investigated using the disc diffusion method. The 45 natural plant extracts showed antibacterial effects and the 16 natural plants extracts didn't show antibacterial effects. The Phyllanthus urinaria L. (stem and leaves) extract showed thr highest antimicrobial activity with $18.96{\pm}0.69mm$ clear zone of the growth of P. acnes, followed by Angelica gigas Nakai (roots), Gynostemma pentaphyllum (Thunb.) Makino, Angelica gigas Nakai (stem and leaves), Isodon inflexus (Thunb.) Kudo, camellia sinensis L. (flowers), Rosmarinus officinalis, etc. These results suggest that the natural plant in Jeju can be used as functional cosmetic biomaterials or antimicrobial agents against P. acnes.

A Study on the Automobile Clutch Disc Spline Hub with High Toughness by Powder Metallurgy (분말 야금에 의한 고인성 자동차 Clutch Disc Spline Hub 개발에 관한 연구)

  • 허만대;장경복;강성수
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.2
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    • pp.28-34
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    • 1998
  • Powder metallurgy processes are able to form Net-Shape products and have been widely used in the production of automobile parts to improve its productivity. However, because of pores in powder products, the toughness of powder products are generally poor. Therefore, forged products are used in parts which suffer severe fatigue loads. In this paper, the choice of powder materials and production processes such as mixing, compaction, sintering, heat treatment to produce automobile spline hub are studied. Three type of materials are selected and processed and its microstructure and properties are investigated by tensile test, compression ring test, and impact test. Materials and processing methods are selected from the results. Finally, experimental spline hubs are manufactured by selected processes from selected powders and proved by torsional durability test.

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Screening of some Bangladeshi medicinal plants for in vitro antibacterial activity

  • Uddin, Shaikh Jamal;Rouf, Razina;Shilpi, Jamil Ahmed;Alamgir, Mohammad;Nahar, Lutfun;Sarker, Satyajit Dey
    • Advances in Traditional Medicine
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    • v.8 no.3
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    • pp.316-321
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    • 2008
  • A total of 33 extracts representing 26 plant species belonging to 24 families were collected from different regions of Bangladesh, and screened for their in vitro antibacterial activity against several pathogenic Gram-positive and Gram-negative bacterial strains using the conventional disc diffusion method. The most potent activity was exhibited by the extracts of Aegiceras corniculatum, Alocasia fornicata, Ceriops decandra, Cuscuta reflexa, Lasia spinosa, Lantana camara, Pandanus foetidus and Xylocarpus granatum. The extracts of Abtilon indicum, Derris trifoliata, Dendrophthoe falcat, Ruellia tuberosa and X. moluccensis did not show any antibacterial properties at test concentrations.

A Study on the Antimicrobial Effect of Ginkgo biloba Leaves Extracts according to Concentrations of Ethanol for staphylococcus aureus (포도상구균에 대만 에탄올 농도별 은행잎 추출물의 항균효과에 관한 연구)

  • Lee, In-Hwa;Shim, Youn;Choi, Seung-Hyun;Park, Ju-Young;Han, Sung-Woo;Song, Jn-Young;Yoon, Suk-Jin
    • KSBB Journal
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    • v.21 no.4
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    • pp.312-316
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    • 2006
  • A optimal condition for the Ginkgo biloba extraction in ethanol and water binary solvent system has been proposed based on concentration of bilobalide and ginkgolide known as having a antimicrobial components in the range 5% to 70% ethanol in water at $80^{\circ}C$. Concentration of bilobalide as a single component of Ginkgo biloba leaves extract is the highest at the 60% ethanol and ginkgolide A and B is highest at 50% ethanol. Antimicrobial effect of Ginkgo biloba leaves extracts on the S. aureus was also examined by disc diffusion test and optical density test. In case of the disc diffusion test, the clean zone diameter was increased from 0.95 cm to 1.70 cm as ethanol concentration increased from 5 to 70%. However, over the 40% of ethanol concentration the antimicrobial effect was almost flat. Based on these results, we propose that the 40% of ethanol and 60% water solvent is most desirable for Ginkgo biloba extract considering vapor pressure problem in concentrating process after extraction. We introduced SEM and TEM to figure out the morphological change on the surface and inside body of S. aureus when Ginkgo biloba leaves extract was treated. After mixed with Ginkgo biloba leaves extract blast like blebs appeared on the surface of S. aureus cells and cell wall was not observed. From the these results, it seems that the Ginkgo biloba leaves extract including bilobalide and ginkgolide A, B prevent cell wall synthesis.

Antimicrobial Activity of Extracted by Supercritical Fluid from Origanum vulgare, Cinnamomum cassia, Chamaecyparis obtusa and Scutellariae baicalensis (오레가노, 육계, 편백 및 황금의 초임계 유체 추출물의 항균 활성)

  • Kim, Woo-Jin;Cho, Jun-Young;Choi, Chang-Suk;Yoon, Gee-Sun;Lee, Won-Kyu;Ryu, Yeon-Woo
    • KSBB Journal
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    • v.23 no.2
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    • pp.147-152
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    • 2008
  • The variety of functional plants has an attention for new natural food preservation and natural antiseptic development. The extracts from functional plants with various methods (ethanol extraction, hot water extraction and supercritical fluid extraction) tested antimicrobial activity against 10 strains including the pathogenic and food poisoning bacteria, the yeast and fungi. The antimicrobial activities of supercritical fluid extracts were shown higher than ethanol extract and hot water extract when tested with disc-diffusion method and minimum inhibitory concentration (MIC). Antimicrobial activity of supercritical fluid extract was two times higher than ethanol extract in Cinnaonomum cassia. In addition, the supercritical fluid extractions of Chamaecyparis obtuas and the C. cassia showed the higher yield than Origanum vulgare and Scutellariae baicalensis. The supercritical fluid extract of C. cassia showed an antimicrobial activity against all strains tested. The supercritical fluid extract of S. baicalensis showed strong antimicrobial activity on Listeria monocytogenes. Supercritical fluid extraction of O. vulgare and C. obtuas showed strong antimicrobial activity on Salmonella typhimuriium. In MIC test, C. obtuas was shown the best natural material for the preparation of natural antimicrobial agent by supercritical fluid extraction. In conclusion, these results suggest that supercritical fluid extraction technique was effective to obtain functional ingredient with higher antimicrobial activity in the development of new antimicrobial reagent from natural materials.