• Journal of the Korean Wood Science and Technology
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• 제52권1호
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• pp.31-46
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• 2024

Subterranean termite attacks on cajuput (Melaleuca cajuputi) seedling roots were widespread in several of Java's Perum Perhutani Forest Management Units. This attack was suspected to be related to the chemical components of the cajunput seedling roots. This study was conducted to determine the bioactivity of cajuput seedling root extract as an attractant for the subterranean termite Coptotermes curvignathus Holmgren (Isoptera: Rhinotermitidae). The extraction process was performed according to ASTM D1108-96, and the extract was characterized using gas chromatography-mass spectrometry (GC-MS). Bioactivity testing of the extracts was carried out using attractiveness and no-choice feeding bioassays. The results showed that the average root extraction yield from cajunput seedlings was 4.94%. The attractiveness of the extract solutions at concentrations of 0.50%, 0.75%, and 1.00% were 45.33%, 62.00%, and 74.67%, respectively. The mortality rate of C. curvignathus termites ranged from 9.63% to 24.44%. Cajuput seedling root extract's lethal concentration 50 was 2.45% (non-toxic). GC-MS analysis showed that the extract contained linoleic acid, which has the potential to attract insects.

• Corrosion Science and Technology
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• 제23권1호
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• pp.20-32
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• 2024

Metal corrosion in acidic environments is a major issue in various industrial applications. This study evaluates the 4-piperonylideneaminoantipyrine (PPDAA) corrosion inhibition efficiency for mild steel in a hydrochloric acid (HCl) solution. The weight loss method was used to determine the corrosion inhibition efficiency at different concentrations and immersion time periods. Results revealed that the highest inhibition efficiency (94.3%) was achieved at 5 mM concentration after 5 hours of immersion time. To inspect the surface morphology of the inhibitor film on the mild steel surface, scanning electron microscopy (SEM) was used before and after immersion in 1.0 M HCl. Density functional theory (DFT) calculations were performed to investigate the molecular structure and electronic properties of the inhibitor molecule to understand the corrosion inhibition mechanism. Theoretical results showed that the inhibitor molecule can adsorb onto the mild steel surface through its nitrogen and oxygen atoms, forming a protective layer that prevents HCl corrosive attack. These findings highlight the potential of PPDAA as an effective corrosion inhibitor for mild steel in HCl solution. Moreover, combining experimental and theoretical approaches provides insights into the mechanism of corrosion inhibition, which is essential for developing effective strategies to prevent metal corrosion in acidic environments.

• Food Science and Biotechnology
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• 제14권3호
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• pp.399-404
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• 2005

The aim of this study was to investigate the in vitro antioxidant profiles of genistein and other isoflavonoids. The reactivity of genistein towards stable radical and reactive oxygen species including ${\bullet}\;ABTS^+$, ${\bullet}{O_2}^-$, $H_2O_2$ and HOCl has been investigated, and the effects were compared with other isoflavonoids and antioxidants. All the tested isoflavonoids showed remarkable ${\bullet}\;ABTS^+$ scavenging activity and genistein was more potent than BHT and ascorbic acid. Genistein was more effective in scavenging hypochlorous acid than superoxide and hydrogen peroxide. At $10\;{\mu}M$ concentrations of genistein and genistin showed about 90% inhibitory effect on HOCl, while BHT and ascorbic acid showed lower than 50% inhibitory effect. Moreover, genistein could inhibit plasmid DNA cleavage, protein degradation and cell death from HOCl attack, while daidzein, BHT and ascorbic acid could not protect them effectively. These results suggest that genistein is a more potent radical scavenger than other isoflavonoids, and it can remarkably reduce cellular damage induced by HOCl.

• 대한지역사회영양학회지
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• 제13권3호
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• pp.334-345
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• 2008

The purpose of this study was to compare nutrient intakes and blood lipids according to the obesity index of middle aged men. Subjects were assigned to one of the following groups based on percentage of body fat (%Fat),; normal weight (10-20% fat), overweight (20-25% fat) and obesity (over 25% fat). Nutrient intakes were evaluated based on questionnaires and 24 hour recall method and blood lipids were analyzed by blood analyzer. The results were as follows: 1) Nutrient intakes were that carbohydrate intake rate in obesity group was lower than normal group and lipids intake rate in obesity group was higher than normal group. The intake of riboflavin and folic acid were differ normal and obesity group (p < 0.05), and normal group ingested under recommended intake. 2) Total-cholesterol, LDL-cholesterol and blood pressure in obesity group were higher than normal group but the differences were not significant. The attack rate of coronary heart disease and blood glucose in obesity group is higher than normal group (p < 0.05). 3) The correlation of anthropometric measurements, blood lipid, blood glucose and blood pressure had significant results. Soft lean mass was associated BMI (p < 0.01), TC (p < 0.05), HDL (p < 0.05), LDL (p < 0.05) and SBP (p < 0.05). TG was associated TC (p < 0.05), HDL (p < 0.01), VLDL (p < 0.001) and Risk (p < 0.01). TC was associated LDL (p < 0.01) and Risk (p < 0.01). Blood glucose was associated TC (p < 0.05), LDL (p < 0.05), SBP (p < 0.05) and DBP (p < 0.05). These results suggest that reduction of body weight for the attack risk of obesity group in coronary heart disease.

• 한국건축시공학회지
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• 제14권4호
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• pp.359-368
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• 2014

Photocatalytic cement has been receiving attention due to its high oxidation power that reduces nitrogen oxide, thus contributing to a clean atmospheric environment. However, there has not yet been a thorough investigation on the effect of photocatalytic reactions on the durability of cementitious material, the parent material. In this study, photocatalytic cement samples were exposed to nitric oxide gas and UV along with cycles of wetting and drying to simulate environmental conditions. The surface of samples was characterized mechanically, chemically, and visually during the cycling. The results indicate that that the photocatalytic efficiency decreased with continued NO oxidation. The pits found from SEM indicated that chemical deterioration, such as acid attack or leaching, did occur. However, this was not confirmed by X-ray diffraction. The hardness was not affected, probably due to the formation of CSH as evidenced by the XRD pattern. In conclusion, it was found that photocatalysis could alter cementitious materials both chemically and mechanically, which could further affect long-term durability.

• 한국염색가공학회지
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• 제1권1호
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• pp.26-34
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• 1989

The selective chemical degradation or etching of PET based on an organic amine attack on the ester group. The techniques involves the chemical removal of loss ordered amorphous regions or crystalline regions, which are essentially unaffected by the degradative etchant. Thus, most of previous studies have limited to consideration which has been given to structural changes taking place. Therefore, this study was carried out to investigate surface characterization, dyeing properties of PET film hydrazinolyzed with hydrazine hydrate in methanol. PET film was treated with 30% hydrazine hydrate in methanol at $30^\circ{C}$ for various time intervals. The total surface tension of treated PET increased, the dispersion force decreased and the hydrogen bonding force increased. The equilibrium dye adsorption, dyeing rate and apparent diffusion coefficient of acid dyes increased, and the apparent activation energies of diffusion decreased.

• 대한토목학회논문집
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• 제12권2호
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• pp.55-66
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• 1992

인공해수 및 5종류의 약품용액에 시멘트풀, 모르터 및 콘크리트 공시체를 침지하여 강도 및 중량 변화를 측정하고 X-ray, SEM 및 EDS로서 반응생성물과 미세구조를 분석 고찰하였다. 연구결과 황산 및 황산염용액에서는 ${SO_4}^{2-}$ 이온의 침투로 인한 ettringite와 석고의 생성이 열화의 원인이 되었다. 염화물용액에서는 $Cl^-$ 이온의 침투가 콘크리트를 열화시키는 중요한 요인이 되었음을 알 수 있었다.

• 한국대기환경학회지
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• 제29권1호
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• pp.64-73
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• 2013

Because some particulate matter emission sources may inherently produce soluble species, or some soluble species may be produced during atmospheric transport, it is important to understand the origin of a particles's solubility when water-soluble tracers are used in source apportionment studies. Laboratory experiments were performed on three types of soils (Mongolia grassland, Mongolia desert, and Korean rural soils), to study the impact of acidification by nitric acid vapor on the solubility of metals in the soils. To achieve this goal, concentrations of water-soluble metals (Na, Mg, Al, K, Ca, Mn, and Fe) in the soils measured before and after acidification. Contributions of concentrations of water-soluble metal species before and after acidification attack to their total concentrations varied little with soil type. Concentrations of water-soluble Mg, Al, K, Ca, Mn, and Fe from the soils after interaction with nitric acid vapor increased, with significant increases in soluble Ca and Mn for all soil types suggesting soil acidification enhances the amount of leachable metal species in soil dust. There was little increase in water-soluble Na and K after acidification for each soil type. This experiment demonstrates that quantities of water-soluble metal species in particulate matter are produced under high gaseous nitric acid conditions.

• The Plant Pathology Journal
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• 제19권2호
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• pp.85-91
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• 2003

Pre-treatment with DL-3-aminobutyric acid (BABA) in the cucumber plants caused the decrease of disease severity after inoculation with anthracnose pathogen Colletotrichum orbiculare. In this study, ultrastructures of the vascular bundle and the infection structures in the leaves of BABA-treated as well as untreated cucumber plants were observed after inoculation with the anthracnose pathogen by electron microscopy. The ultrastructures of vascular bundle in the leaves of BABA-treated plants were similar to those of the untreated plants except plasmodesmata. In the BABA-treated plants, the plasmodesmata were more numerous than in the untreated plants, suggesting that the BABA treatment may cause the active transfer of metabolites through the vascular bundle. In the leaves of untreated plants, the fungal hyphae were spread widely in the plant tissues at 5 days after pathogen inoculation. Most cellular organelles in the hyphae were intact, indicating a compatible interaction between the plant and the parasite. In contrast, in the leaves of BABA pre-treated plants the growth of most hyphae was restricted to the epidermal cell layer at 5 days after inoculation. Most hyphae cytoplasm and nucleoplasm was electron dense or the intracellular organelles were degenerated. The cell walls of some plant cells became thick at the site adjacent to the intercellular hyphae, indicating a mechanical defense reaction of the plant cells against the fungal attack. Furthermore, hypersensitive reaction (HR) of the epidermal cells was often observed, in which the intracellular hyphae were degenerated. Based on these results it is suggested that BABA causes the enhancement of defense mechanisms in the cucumber plants such as cell wall apposition or HR against the invasion of C. orbiculare.

• 한국농공학회논문집
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• 제54권5호
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• pp.25-34
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• 2012

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to cement mortar by forming expansive hydration products due to the reaction between cement hydration products and acid and sulfate ions. In this study, the effect of fly ash and blast furnace slag on the bond performances of structural synthetic fiber in latex modified cement mortar under sulfate environments. Fly ash and blast furnace slag contents ranging from 0 % to 20 % are used in the mix proportions. The latex modified cement mortar specimens were immersed in fresh water, 8 % sodium sulfate ($Na_2SO_4$) solutions for 28 and 50 days, respectively. Pullout tests are conducted to measure the bond performance of structural synthetic fiber from latex modified cement mortar after sulfate environments exposure. Test results are found that the incorporation of fly ash and blast furnace slag can effectively enhance the PVA fiber-latex modified cement mortar interfacial bond properties (bond behavior, bond strength and interface toughness) after sulfate environments exposure. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results under sulfate environments.