• 제목/요약/키워드: acid environment

검색결과 2,538건 처리시간 0.038초

산성안개가 내후성강재의 녹형성 및 피로강도에 미치는 영향 (Effect of Acid Fog on Rust Formation and Fatigue Strength of Weathering Steel)

  • 김민건;구은회
    • 산업기술연구
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    • 제22권B호
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    • pp.13-20
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    • 2002
  • The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in uncoated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

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무도장 교량에 사용되는 내후성강재의 부식 및 피로거동에 미치는 산성안개의 영향 (Effect of Acid Fog on Rust Formation and Fatigue Behavior of Weathering Steel Used in Un-Coated Bridge)

  • 김민건
    • 대한기계학회논문집A
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    • 제32권1호
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    • pp.13-20
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    • 2008
  • The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

근적외선분광광도법을 이용한 참기름의 산가, 요오드가, 지방산정량법에 관한 연구 (Quantitative Analysis of Acid Value, Iodine Value and Fatty Acids Content in Sesame Oils by NIRS)

  • 김재관;이명진;김명길;김경아;박은미;김영숙;고환욱;손진석
    • 한국식품위생안전성학회지
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    • 제21권4호
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    • pp.204-212
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    • 2006
  • 근적외선 분광광도기을 이용하여 참기름의 Acid value, iodine value, palmitic acid, stearic acid, oleic acid, linoleic acid 및 linolenic acid를 비파괴적으로 신속하게 정량할 수 있는 가능성을 조사하였다. 시료의 스펙트럼측정은 투과방식을 이용하여 $400\sim2500nm$ 범위에서 측정하였다. MPLS를 이용하여 도출된 Acid value, Iodine value, palmitic acid, stearic acid, oleic acid, linoleic acid 및 linolenic acid의 검량선 상관도는 각각 0.9907, 0.9077, 0.9527, 0.9210, 0.9829, 0.9736, 0.9709이었고 검증했을때의 상관도는 각각 0.989, 0.944, 0.924, 0.717, 0.989, 0.967, 0.990이었으며 SEP는 0.058, 0.562, 0.194, 0.168, 0.221, 0.297, 0.072로 나타나 기존의 분석법을 대신하거나 예비시험법으로 활용할 수 있는 유용한 방법임이 입증되었다 본 연구에서 개발한 방법은 매우 간단하게 참기름의 품질평가 및 진위여부를 판단할 수 있어 다수의 시료를 검사해야 하는 기관과 실시간으로 품질관리를 필요로 하는 생산현장에서 예비시험법으로 활용함으로써 인력절감 및 실험환경 개선등의 효과를 얻을 수 있을 것으로 기대된다.

매생이(Capsosiphon fulvescens)의 이화학적 성분 (Physicochemical Composition of Seaweed Fulvescens (Capsosiphon fulvescens))

  • 양호철;정경모;강광성;송병준;임현철;나환식;문희;허남칠
    • 한국식품과학회지
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    • 제37권6호
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    • pp.912-917
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    • 2005
  • 전남 지방에서 생산되는 매생이를 채취하여 이화학적 성분을 조사하였다. 일반성분은 건물기준 탄수화물이 53.65%로 가장 많이 함유하고 있었고, 조단백질 31.76%, 회분 13.58%와 조 지방이 1.01%로 나타났다. 매생이에 주로 함유되어 있는 무기성분으로는 Na>Mg>Ca>K>P 순으로 나타났으며 Se도 검출되었다. 유리당은 총 5종의 유리당(fructose, glucose, sucrose, maltose, galactose)이 분석되었으며 유기산은 l-malic acid, citric acid, tartaric acid, D-malic acid 등 4종이 검출되었다. 매생이의 구성 아미노산은 전체적으로 고루 함유되어 있었고 그 중 glutamic acid, aspartic acid와 alanine이 전체의 36.2%를 차지하였다. 매생이에 함유된 주요 지방산으로는 palmitic acid, linolenoc acid, stearidonic acid 순이었으며 고도 불포화지방산이 전체의 58.37%를 차지하고 있었다.

느타리버섯 자실체의 부위 및 생육시기별 지방산 조성의 변화 (Changes of Fatty Acid Composition by Various Developmental Stage and Fruit Body Section in Pleurotus ostreatus)

  • 류영현;이숙희;조우식;윤재탁
    • 한국균학회지
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    • 제28권2호
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    • pp.109-111
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    • 2000
  • 느타리버섯(원형1호 느타리) 자실체의 부위별로 지방산 조성을 조사한 결과 linoleic acid는 갓부위에서 가장 높았고 대부위로 갈수록 낮아지는 경향이었고 stearic acid와 palmitic acid는 대부위로 갈수록 증가하는 경향이었다. 생육시기별 지방산조성은 oleic acid의 경우 버섯원기형성 후 $11{\sim}12$일 까지는 점차 증가하다가 이후부터는 감소하는 경향을 보였고 linoleic acid와 불포화지방산대비 포화지방산의 비율은 원기형성 후 $3{\sim}4$일까지는 증가하다가 그 후부터는 감소하는 경향을 나타내었다.

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Butyric Acid Fermentation of Sodium Hydroxide Pretreated Rice Straw with Undefined Mixed Culture

  • Ai, Binling;Li, Jianzheng;Chi, Xue;Meng, Jia;Liu, Chong;Shi, En
    • Journal of Microbiology and Biotechnology
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    • 제24권5호
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    • pp.629-638
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    • 2014
  • This study describes an alternative mixed culture fermentation technology to anaerobically convert lignocellulosic biomass into butyric acid, a valuable product with wide application, without supplementary cellulolytic enzymes. Rice straw was soaked in 1% NaOH solution to increase digestibility. Among the tested pretreatment conditions, soaking rice straw at $50^{\circ}C$ for 72 h removed ~66% of the lignin, but retained ~84% of the cellulose and ~71% of the hemicellulose. By using an undefined cellulose-degrading butyrate-producing microbial community as butyric acid producer in batch fermentation, about 6 g/l of butyric acid was produced from the pretreated rice straw, which accounted for ~76% of the total volatile fatty acids. In the repeated-batch operation, the butyric acid production declined batch by batch, which was most possibly caused by the shift of microbial community structure monitored by denaturing gradient gel electrophoresis. In this study, batch operation was observed to be more suitable for butyric acid production.

옥살산 기반의 비소오염토양 정화 연구 (Oxalic Acid-based Remediation of Arsenic-contaminated Soil)

  • 이명은;전은기;김종국;백기태
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제23권1호
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    • pp.85-91
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    • 2018
  • Arsenic (As) usually is bound to amorphous iron oxides in the soils, and it can be removed via dissolution of iron oxides. Inorganic acid and chelating agent are widely used to extract As in the soil washing. However, the overall performance is highly dependent on the state of As fractionation. In this study, oxalic acid and inorganic acids (HCl, $H_2SO_4$, and $H_3PO_4$) were applied to enhance the dissolution of iron oxides for remediation of As-contaminated soils. Oxalic acid was most effective to extract As from soils and removal of As was two times greater than other inorganic acids. Additionally, 75% of As bound to amorphous iron oxides was removed by 0.2 M oxalic acid. Arsenic removal by oxalic acid was directly proportional to the sum of labile fractions of As instead of the total concentration of As. Therefore, the oxalic acid could extract most As bound to amorphous iron oxides.

기계구조용강 SM55C의 부식피로강도에 미치는 산성안개 분위기의 영향 (Effects of Acid Fog Environment on the Corrosion Fatigue Strength of Structural Steel SM55C)

  • 김진학;김민건
    • 한국자동차공학회논문집
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    • 제8권5호
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    • pp.181-187
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    • 2000
  • Fatigue tests under acid fog environment were carried out to investigate the effect of acid fog on the corrosion fatigue strength of SM55C in comparison with distilled water. Main results obtained are as follows. The fatigue strength of SM55C under acid fog environment are remarkably decreased as compared with that of distilled water specimen. The corrosive effect of acid fog on fatigue strength are more serious under low stress amplitude level than under high stress amplitude level, and this leads to continuous reduction of fatigue strength. Under acid fog environment in early stage of crack growth. because the corrosive components dissolve the crack face offensively. the unstable fracture surface appears. But, the stable corrosion precipitation and products layer are formed on the fracture surface in accordance with the time pass.

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광주지역에서 유통되고 있는 참기름의 진위판별 및 안전성 조사 (A Survey on Adulteration and Safety of Sesame oil Circulated in Gwangju)

  • 양용식;김종필;서계원;조배식;강경리;김은선;박종태
    • 한국식품위생안전성학회지
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    • 제23권3호
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    • pp.212-217
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    • 2008
  • This survey was conducted to monitor the adulteration of sesame oil circulated in Gwangju, 2007. A total of 60 samples was tested by analysis of fatty acid composition. Of these samples, 22 were from large-scale manufacturer, 25 were from small-scale manufacturer and 13 from Bangagan. First of all, in goods manufactured by large-scale company, there are no sesame oils where linolenic acid($C_{18:3}$) exceed regulatory guidance(0.5%). 5 samples from small-scale manufacturer contained linolenic acid from 0.90% to 8.38%, which means that they have other cooking oil, such as com oil, soybean oil and rape seed oil. Among Bangagan goods, only one sample have 1.20% of linolenic acid. On the other hand erucic acid($C_{22:1}$) was not detected in 60 samples at all, which means that they were not adulterated with rape seed oil. And among 6 samples of exceeding 0.5% of linolenic acid and 12 samples from Bangagan, 13 of them had benzo(a)pyrene from $0.2{\mu}g/kg\;to\;0.7{\mu}g/kg$ and the other 5 samples did not.

P-hydroxybenzoic acid positively affect the Fusarium oxysporum to stimulate root rot in Panax notoginseng

  • Jing Zhao;Zhandi Wang;Rong Jiao;Qionglian Wan;Lianchun Wang;Liangxing Li;Yali Yang;Shahzad Munir
    • Journal of Ginseng Research
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    • 제48권2호
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    • pp.229-235
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    • 2024
  • Background: Plant health is directly related to the change in native microbial diversity and changes in soil health have been implicated as one of the main cause of root rot. However, scarce information is present regarding allelopathic relationship of Panax notoginseng root exudates and pathogenic fungi Fusarium oxysporum in a continuous cropping system. Methods: We analyzed P. notoginseng root exudate in the planting soil for three successive years to determine phenolic acid concentration using GC-MS and HPLC followed by effect on the microbial community assembly. Antioxidant enzymes were checked in the roots to confirm possible resistance in P. notoginseng. Results: Total 29 allelochemicals in the planting soil extract was found with highest concentration (10.54 %) of p-hydroxybenzoic acid. The HPLC showing a year-by-year decrease in p-hydroxybenzoic acid content in soil of different planting years, and an increase in population of F. oxysporum. Moreover, community analysis displayed negative correlation with 2.22 mmol. L-1 of p-hydroxybenzoic acid correspond to an 18.1 % population of F. oxysporum. Furthermore, in vitro plate assay indicates that medium dose of p-hydroxybenzoic acid (2.5-5 mmol. L-1) can stimulate the growth of F. oxysporum colonies and the production of macroconidia, as well as cell wall-degrading enzymes. We found that 2-3 mmol. L-1 of p-hydroxybenzoic acid significantly increased the population of F. oxysporum. Conclusion: In conclusion, our study suggested that p-hydroxybenzoic acid have negative effect on the root system and modified the rhizosphere microbiome so that the host plant became more susceptible to root rot disease.