• Computers and Concrete
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• 제11권6호
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• pp.587-602
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• 2013

In the current study, a method for concrete compressive strength prediction (based on cement strength class), incorporated in a software package developed by the authors for the estimation of concrete service life under harmful environments, is presented and validated. Prediction of concrete compressive strength, prior to real experimentation, can be a very useful tool for a first mix screening. Given the fact that lower limitations in strength have been set in standards, to attain a minimum of service life, a strength approach is a necessity. Furthermore, considering the number of theoretical attempts on strength predictions so far, it can be seen that although they lack widespread accepted validity, certain empirical expressions are still widely used. The method elaborated in this study, it offers a simple and accurate, compressive strength estimation, in very good agreement with experimental results. A modified version of the Feret's formula is used, since it contains only one adjustable parameter, predicted by knowing the cement strength class. The approach presented in this study can be applied on any cement type, including active additions (fly ash, silica fume) and age.

• Applied Biological Chemistry
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• 제33권4호
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• pp.315-318
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• 1990

분쇄되지 않은 미량의 원제를 수화제로 제제하는데는 미분상 다공성 증량제의 물리성을 이용한 흡착법이 유호하다. 밀리그램 단위의 농약 원제를 휘발성 유기용매에 용해시킨 후 계면활성제 혼합물이 흡착되어 있는 미분상의 합성실리카에 흡수시키고 건조하여 11종의 10% 수화제를 제제하였다. 원료 상태의 합성실리카와 시료수화제의 입도분포를 측정하여 평균 입경의 변화를 관찰하였다. 이들 수화제중 pencycuron과 vinclozolin을 제외한 9종의 시료는 2시간후에도 80%이상의 현수율을 나타냈다. 제제중 유효성분량을 $30{\sim}50%$로 증가시켜도 4종의 시료중 3종에서 현수율의 변화가 거의 없었다. 또한 이들 수화제 시료는 현수성과 거의 무관하게 생리활성이 기존제품과 대등하게 나타나서 수화제로서 그 기능이 우수한 것으로 인정되었다.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.778-782
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• 2003

In the course of screening anti-influenza agents from natural products, four neuraminidase inhibitors were isolated from the methanol extract of mushroom Microphorus affinis by purification using solvent partition, silica gel column chromatography, Sephadex LH-20, and semi-preparative HPLC. The chemical structures of these compounds were identified as ${\alpha}-lupeol$, methyl linoleate, methyl palmitate, and methyl oleate by means of spectral data including GC-MS, $^1H-,\;and\;^{13}C-NMR\;with\;IC_{50}$ values of 5.65, 7.07, 7.12, and $7.52\;\mu\textrm{M}$, respectively. They did not inhibit other glycosidases such as glucosidase, mannosidase, and galactosidase, indicating that they were relatively specific inhibitors of neuraminidase. The relationship between the fatty acid structure and inhibitory activity was investigated. The result showed that, in the case of an aliphatic linear hydrocarbon skeleton, at least one carboxyl (presumably any carbonyl) moiety and sixteen carbons were the necessary requirements for potent inhibition, whereas saturated, unsaturated, free, and ester forms did not have any significant effect on the activity.

• 한국미생물·생명공학회지
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• 제31권2호
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• pp.135-139
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• 2003

Melanin 생합성에 key enzyme인 tyrosinase 억제가 melanin색소 억제에 주된 요인으로 알려져 있지만, 생합성기작에는 여러 다른 요인들이 작용하기 때문에 일차적인 탐색 단계에서 tyrosinase 저해 활성뿐만 아니라 S. bikiniensis의 melanin생합성 억제 연구를 병행하여 천연물을 탐색하였다. 그 중 선택된 궁궁이 (Angelica poiymorpha MAXIM)에서 3가지 물질을 분리하였으며, 3가지 물질 모두가 100$\mu\textrm{g}$/$m\ell$ 이상 농도에서도 tyrosinase억제 활성이 나타나지 않는 반면, S. bikiniensis melanin 생합성 저해 효과를 보여 주었다. 동일 농도에서 S. bikinieffsis의 생장에는 영향을 미치지 않았다.

• 약학회지
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• 제51권6호
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• pp.430-434
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• 2007

The anti-inflammatory activity of fruit body of Phellinus pini was investigated by activity-guided fractionation. From the screening of each fraction for the inhibitory activity of NO production in lipopolysaccaride (LPS) activated RAW 264.7 cells, methanol extract and its hexane soluble fraction of Phellinus pini exhibited inhibition of NO production compared with LPS control without toxicity. The hexane soluble fraction showed dose-dependent inhibition of NO production. The active hexane fraction was repeatedly chromatographed over silica gel, ergosta-7,24(28)-dien-3-ol(1) and ergosterol peroxide (2) were isolated and identified. Ergosterol derivatives were inhibited NOS activation, $IC_{50}$ of them were $18.9{\pm}3.9{\mu}M$ (1) and $20.4{\pm}4.5{\mu}M$ (2).

• 한국미생물·생명공학회지
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• 제24권1호
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• pp.77-81
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• 1996

During the screening for the antifungal compounds against Phytophthora capsici causing phytophthora blight of red pepper, we isolated a strong active compound, bafilomycin $C_1$, produced by strain 3D3. The producing organism was identified as Streptomyces sp. based on taxonomic studies. The antifungal compound was purified from culture broth by HP-20 column chromatography, ethylacetate extraction, silica gel column chromatography and HPLC, and was identified as bafilomycin $C_1$ by color reaction, UV and $^{1}H$-NMR spectral data analysis. Bafilomycin $C_1$ showed strong antifungal activity against various phytopathogenic fungi.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.135-135
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• 1998

To find an antagonist of Pythium ultimum, the causal agent of damping-off, numerous actinomycete strains were screened for in vitro inhibiting mycelial growth of the target fungus and producing bioactive metabolites. A strain identified as Streptomyces sp. G60655 was isolated and used for further antagonistic efficacy. The degree of antagonism between the fungus and G60655 was affected by the medium used. Furthermore, the preinoculation of the antagonist was found to be necessary to exhibit the maximum efficacy of antagonsim against the fungus. From the culture broth, a bioactive metabolite was detected and purified by solvent extraction, silica gel chromatography and preparative HPLC. The FAB-MS spectrum of the active compound showed a molecular ion peak at m/z 1101 (M + H)$\^$+/, suggesting the molecular weight of 1100. The UV absorptions at 242 and 323 nm indicated the presence of aromatic functions. The structure of this compound was identified as echinomycin, a depsipeptide antibiotic by spectroscopic studies including various NMR measurements. Echinomycin was inactive against several soil born fungi, but inhibited the mycelial growth of P. ultimum and its related oomycetous fungi.

• Journal of Microbiology
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• 제45권3호
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• pp.262-267
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• 2007

During a screening program, an actinomycete strain isolated from the Egyptian soil was investigated for its potential to show antimicrobial activity. The identification of this isolate was performed according to spore morphology and cell wall chemo-type, which suggested that this strain is a streptomycete. Further cultural, physiological characteristics and the analysis of the nucleotide sequence of the 16S rRNA gene (1480 bp) of this isolate indicated that this strain is identical to Streptomyces violaceusniger (accession number EF063682) and then designated S. violaceusniger strain HAL64. In its culture supernatant, this organism could produce one major compound strongly inhibits the growth of Gram-positive but the inhibition of Gram-negative indicator bacteria was lower. The antibiotic was separated by silica gel column chromatography and then purified on a sephadex LH-20 column and finally the purity was checked by HPLC. The chemical structure of the purified compound was determined using spectroscopic analyses (molecular formula of $C_{33}H_{32}N_{2}O_{10}$ and molecular weight of 617.21) and found to be identical to the kosinostatin, a quinocycline antibiotic which is known to be produced by Micromonspora sp. TP-A0468 (Igarashi et al., 2002) and to quinocycline B isolated from Streptomyces aureofaciens (Celmer et al., 1958). Although the antibiotic is known, the newly isolated strain was able to produce the antibiotic as a major product providing an important biotechnological downstream advantage.

• 한국균학회지
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• 제26권1호통권84호
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• pp.78-85
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• 1998

전국 각지에서 채집한 사멸곤충에서 분리한 곤충 기생성 진균이 생산하는 살충성 생리활성물질을 탐색한 결과 곰팡이 분리주 CNAB-63 균주가 목화진딧물과 점박이응애 모두에 대해 다른 분리균주들보다 비교적 높은 살충효과를 보인 바, 본 균주가 생산하는 살충성분을 각종 chromatography로 분리 정제하였다. 정제된 활성물질 CNAB는 점박이응애에서 66.59%, 목화진딧물에서 52.96%의 살충효과를 보였으며, 그 외에도 온실가루이에 살충효과를 보였으나 배추좀나방에는 미미한 살충효과를 보였다. 한편 활성물질 CNAB는 $100\;{\mu}g/disk$ 농도에서 곰팡이, 효모, 세균류에 전혀 항균활성을 보이지 않았다.

• 생약학회지
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• 제24권4호
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• pp.299-303
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• 1993

The antioxidant activity of methanol extracts of plants and marine algae was tested by using 1,1-diphenyl-2-picrylhydrazyl(DPPH). Five plant extracts(Prunus davidiana, Eriobotrya japonica, Artemisia iwayomogi, Stirodella tolyrrhiza and Ulmus davidiana) and two algae (Ecklonia stolonifera and Symphycoladia latiuscula) were found to be the most effective in DPPH radical scavenging activity. The methanol extract obtained from the stems of Prunus davidiana was fractionated with several solvents. The ethylacetate soluble fraction exhibiting the strongest antioxidant activity was further purified by repeated silica gel and Sephadex LH-20 column chromatography. Antioxidant flavonoids and flavonoid glycosides were isolated and the most active ones was identified as (+)-catechin by MS, $^1H-NMR$ and $^{13}C-NMR$. Its antioxidant activity was higher than that oil vitamin C.