• Title/Summary/Keyword: Acid Resistance

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Reliability of the Impregnated Boron Compounds, Citric Acid- and Heat-Treated Samama (Anthocephalus macrophyllus) Wood against the Fungal and Termite Attacks

  • Trisna PRIADI;Guruh Sukarno PUTRA;Tekat Dwi CAHYONO
    • Journal of the Korean Wood Science and Technology
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    • v.51 no.1
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    • pp.49-57
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    • 2023
  • This research aimed to evaluate the durability of Samama (Anthocephalus macrophyllus) wood treated with boron preservatives, citric acid (CA), and heating against termites. Wood samples were impregnated firstly with 5% boron solutions, such as boric acid, borax and boric acid + borax combination at 1:1 (w/w). The second impregnation used 5% CA. The impregnations were conducted in a pressure tank at 7 kg/cm2 for 4 hours. After impregnation, the samples were heat treated at 80℃ or 160℃. All the treated and control samples were exposed to decay fungi, drywood termites and subterranean termites based on SNI 7207:2014 standard. The results showed that boron preservatives reduced fungal attacks on Samama wood. The combination treatment of boric acid, CA and heat treatment at 160℃ was also effective to increase the resistance of Samama wood against white- and brown rot fungi, and drywood termites. Heat treatment consistently improved the resistance of Samama wood from decay fungi.

Dielectric breakdown of anodic oxide films formed on AA6061 in 20% H2O4and 8% H2SO4+ 3% C2H2O4 solutions (20% 황산 및 8% 황산 + 3% 옥살산에서 AA6061 합금 표면에 형성된 아노다이징 피막의 내전압 특성)

  • Cheolgi Park;Jaehwak Jang;Yunsuk Hyun;Sungmo Moon
    • Journal of Surface Science and Engineering
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    • v.57 no.1
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    • pp.8-13
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    • 2024
  • Anodizing of Al6061 alloy was conducted in two different electrolytes of 20% sulfuric acid and 8% sulfuric acid + 3 % oxalic acid solutions at a constant current or decreasing current density conditions, and its dielectric breakdown voltage was measured. The surface morphology of anodic oxide films was observed by TEM and thermal treatment was carried out at 400 ℃ for 2 h to evaluate the resistance of the anodic oxide films to crack initiation. The anodic oxide film formed in 8% sulfuric acid + 3 % oxalic acid solution showed higher dielectric breakdown voltage and better resistance to crack initiation at 400 ℃ than that formed in 20% sulfuric acid solution. The dielectric breakdown voltage increased 6 ~12% by applying decreasing current density comparing with a constant current density.

Sanitizing Agent Effect and Antibiotic Resistance of Salmonella spp. Isolated from Raw Chicken Carcasses in Food Service (집단급식용 생계육에서 분리된 Salmonella의 항생체 내성과 위생 처리제의 영향)

  • Kang, Ji-Hyun;Lee, Young-Duck;Jung, Ki-Chang;Park, Jong-Hyun
    • Korean Journal of Food Science and Technology
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    • v.33 no.5
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    • pp.582-588
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    • 2001
  • To control the growth of Salmonella on raw chicken supplied in food service, they were isolated and analysed for their physiological characteristics. Total viable microbe counts under the skin of the chicken amounted to 10% of numbers on their skin. Fifty one of Salmonella were isolated and identified from 75 chicken carcass samples. About 70% of the isolates showed resistance to more than four antibiotics, which indicated very high resistance among the strains ever reported in Korea. Lactic acid and trisodium phosphate(TSP) as sanitizing agent were applied to the Salmonella spp. isolates by agar diffusion method. The resistance by isolates to those sanitizing agents was compared with type strains of S. typhimurium ATCC 14028, S. typhimurium ATCC 12023, S. heidelberg and S. enteritidis. The isolates showed similar or less resistance to the type strains as for the lactic acid. However, as for trisodium phosphate known recently as a good sanitizer, 50% of the isolates showed more resistant compared with the type strains. Also, the treatment time and regeneration medium affected significantly the resistance of the isolates, which indicates that more careful test might be needed for TSP's practical application to raw chicken. Therefore, From the results, it is suggested that antibiotic treatment during breeding broiler and contamination after slaughtering should be minimized along with careful use of sanitizing agent in order to ensure more safe raw chicken supply.

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Resistance to Pine Gall-midge and Phenolic Acid Content in Pine Needles (소나무류의 솔잎혹파리에 대한 저항성과 침엽내(內) Phenolic Acid의 농도)

  • Eom, Tae-Jin;Son, Doo-Sik;Lee, Sang-Woo;Seo, Jae-Durk
    • Journal of the Korean Wood Science and Technology
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    • v.26 no.3
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    • pp.33-40
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    • 1998
  • The phenolic acids in needles of five pine species such as Pinus densiflora, P. thunbergii. P. virginiana. P. rigida. and P. koraiensis were analyzed seasionally (March, June, September and December) in order to investigate the resistant factors against pine gall-midge(Thecodiplosis japonensis Uchida et Inouye). The interrelation of resistance to pine gall-midge and the content of phenolic acids in pine needles was investigated in the artificial hybride pine species. The contents of salicylic acid in susceptible species (P. densiflora and P. thunbergii) to pine gall-midge which watered with salicylic acid solution in a pot was determined. The results can be concluded as follows, 1. There was a little change in total phenolic constituents of resistant and susceptible pines seasonally. The each content of benzoic acid, salicylic acid and p-hydroxybenzoic acid in June was the highest through four seasons. 2. In June, resistant species showed higher content of salicylic acid than susceptible species, while the content of gallic acid was the highest in December. 3. Among the 21 artificial hybrids(P. densiflora ${\times}$ P. virginiana. P. thunbergii ${\times}$ P. virginiana), the hybrides of the higher salicylic acid content showed the lower rate of pine gall formation. 4. Pine gall formation of the susceptible species which were watered with salicylic acid solution remarkably decreased.

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Complete Nucleotide Sequence of Small Multidrug Resistance Plasmid pKH4 (Small Multidrug Resistance(smr) 플라스미드 pKH4의 염기서열 결정)

  • 고창학;문경호
    • YAKHAK HOEJI
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    • v.43 no.6
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    • pp.789-792
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    • 1999
  • The complete nucleotide sequence of pKH4, a small multidrug resistance (smr) plasmid isolated from multidrug resistant Staphylococcus aureus SA5, was determined. Sequence analysis has revealed that pKH4 has two open reading frames for Rep and Smr proteins. The comparison of the amino acid sequence of Smr protein of pKH4 with those of other Smr proteins of various Staphylococcus showed that Smr protein of pKH4 is a new member of the SMR family.

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Acid Corrosion Resistance and Durability of Alkali-Activated Fly Ash Cement-Concrete (알칼리활성 플라이 애쉬 시멘트-콘크리트의 산저항성 및 내구성)

  • Kang, Hwa-Young;Park, Sang-Sook;Han, Sang-Ho
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.1
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    • pp.61-68
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    • 2008
  • A new cementitious material has been developed, called alkali-activated fly ash cement(AAFC), which is used to produce AAFC-concrete for construction. The effect of acid attack, sodium chloride solution, carbonation, freeze-thaw cycling, and SEM, XRD analysis of the AAFC-concrete prepared using alkali-activated fly ash cement and OPC-concrete were experimentally investigated. It was found that the acid resistance of AAFC-concrete(35 MPa) prepared from alkali-activated fly ash at 85$^{\circ}C$ for 24 hrs is far better than OPC-concrete(35 MPa). Also, the AAFC-concrete(35 MPa) had a similar resistance of OPC-concrete(35 MPa) to attack, such as sodium chloride solution, carbonation and freeze-thaw cycling.

Effect of Anodizing Current Density on Anti-Corrosion Characteristics for Al2O3 Oxide Film (Al2O3 산화 피막의 내식성에 미치는 양극산화 전류밀도의 영향)

  • Lee, Seung-Jun;Jang, Seok-Gi;Kim, Seong-Jong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.153-153
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    • 2016
  • Aluminum alloys have poor corrosion resistance compared to the pure aluminum due to the additive elements. Thus, anodizing technology artificially generating thick oxide films are widely applied nowadays in order to improve corrosion resistance. Anodizing is one of the surface modification techniques, which is commercially applicable to a large surface at a low price. However, most studies up to now have focused on its commercialization with hardly any research on the assessment and improvement of the physical characteristics of the anodized films. Therefore, this study aims to select the optimum temperature of sulfuric electrolyte to perform excellent corrosion resistance in the harsh marine environment through electrochemical experiment in the sea water upon generating porous films by variating the temperatures of sulfuric electrolyte. To fabricate uniform porous film of 5083 aluminum alloy, we conducted electro-polishing under the 25 V at $5^{\circ}C$ condition for three minutes using mixed solution of ethanol (95 %) and perchloric (70 %) acid with volume ratio of 4:1. Afterward, the first step surface modification was performed using sulfuric acid as an electrolyte where the electrolyte concentration was maintained at 10 vol.% by using a jacketed beaker. For anode, 5083 aluminum alloy with thickness of 5 mm and size of $2cm{\times}2cm$ was used, while platinum electrode was used for cathode. The distance between the two was maintained at 3 cm. Afterward, the irregular oxide film that was created in the first step surface modification was removed. For the second step surface modification process (identical to the step 1), etching was performed using mixture of chromic acid (1.8 wt.%) and phosphoric acid (6 wt.%) at $60^{\circ}C$ temperature for 30 minutes. Anodic polarization test was performed at scan rate of 2 mV/s up to +3.0 V vs open circuit potential in natural seawater. Surface morphology was compared using 3D analysis microscope to observe the damage behavior. As a result, the case of surface modification presented a significantly lower corrosion current density than that without modification, indicating excellent corrosion resistance.

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Strength and sulfuric acid resistance properties of cement mortar containing copper slag (동 제련 슬래그를 사용한 시멘트 모르타르의 강도 및 황산저항 특성)

  • Hong, Chang Woo;Lee, Jung-Il;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.3
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    • pp.101-108
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    • 2016
  • Each year, more than seven hundred thousand tons of copper slag are generated in Korea as a byproduct during the production of copper. Due to the large amount of copper slag produced, there has been increased interest in the use of copper slag as a construction material. To evaluate the potential of copper slag as a construction material, laboratory evaluations were conducted in this study, and three particle shapes and replacement rates of river sand were selected as experimental variables. Strength, air-void characteristics, and sulfuric acid resistance were the three properties evaluated to assess whether copper slag can be used as a construction material. Test results indicate that the gradation of copper slag has an effect on strength, and the maximum strength was achieved when 60 % of river sand was replaced with copper slag. In addition, when compared with ordinary Portland cement mortar, replacing river sand with copper slag reduced air void size and increased sulfuric acid resistance.

Improvement of Oxidation-resistance of Graphite by Phosphate (인산 에스테르에 의한 탄소재료의 내산화 증진 효과)

  • 김경자;조광연;박윤창;김태관;정윤중;임연수
    • Journal of the Korean Ceramic Society
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    • v.36 no.5
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    • pp.555-563
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    • 1999
  • Impregnation of phosphorous additiers into graphite bulk was studied with the goal of enhancing the effectiveness of oxidationprotection. In addition graphite acid washing was carried out prior to the impregnation further to improve oxidation resistance. Observation of the oxidation rate for raw graphite(Raw) impregnated graphite with tri-butyl phsophate on raw block(RP) and impregnated graphite on acid-treated graphite(AP) in air are reported. The phsophorus residue adsorbed on the graphite surface at active sites was determined by FTIR, XRS, TGA techniques. AP with tri-butyl phosphate was found to result in both 30% reduction in oxidation rate at 1000$^{\circ}C$ compared to Raw and increase of 120$^{\circ}C$ in oxidation temperature From the samples of oxidation rate of each specimen in Arrhenius plot it can be said that the present oxidation resistance origninates from the change of chemical reaction modesw neigther by acid-washing treatment nor phsophate impregnation

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Electrochemical Properties of Core-Shell Polyolefin Nonwoven Fabric Modified with Sulfonic Acid Group (술폰산기를 갖은 코아-쉘형 폴리올레핀 부직포의 전기화학적 성질)

  • Choi, Seong-Ho;Zhang, Yu-Ping;Shon, Sang-Ho;Lee, Kwang-Pill
    • Analytical Science and Technology
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    • v.17 no.1
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    • pp.60-68
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    • 2004
  • The core-shell polyolefin nonwovon fabric (PNF), wherein the PNF comprises at least about 60% of polyethylene having a melting temperature at ${\sim}132^{\circ}C$ and no more than about 40% of second polypropylene having a lower melting temperature at ${\sim}162^{\circ}C$. The sulfonic acid group for battery separators were prepared by radiation-induced grafting of styrene onto PNF and by the subsequent sulfonation of polystyrene graft chains. The sulfonated PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The electrochemical properties such as electrolyte retension, electrical resistance, and transport number of the $K^+ions$ were evaluated after sulfonation. It was found that the electrolyte retension increased, whereas the electrical resistance decreased with increasing sulfonic acid content. The transport number of $K^+$ in PNF with sulfonic acid of 0.22 ~ 3.60 mmol/g was to be 0.90 ~ 0.93.