• KSBB Journal
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• 제13권5호
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• pp.599-605
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• 1998

Soybean peroxidase was extracted from soybean hulls and purified by ammonium sulfate precipitations (25% and 75% saturation), pl fractionation, and anionic exchange and gel filtration chromatographies (DEAE-Sephadex A-50 and Superose 12). Modlecular weight and pl value were estimated to be ca. 45 kD and 4.2, respectively. Purified soybean peroxidase had an RZ value of 0.43. Compared with horseradish peroxidase, it showed superior thermal and pH stability. Assuming the first-order kinetics, the thermal deactivation rate constant of soybean peroxidase at 80$^{\circ}C$ was about 8 times lower than that of horseradish peroxidase. Deactivation energy was calculated to be 69.3 kcal/mol. Soybean peroxidase showed about 10% higher H2O2 degradation capacity than horseradish peroxidase. Exploiting these advantages, the soybean peroxidase purified from the domestic soybean hull is expected to replace horseradish peroxidase in various applications.

• 한국조명전기설비학회지:조명전기설비
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• 제11권1호
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• pp.24-33
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• 1997

본 논문에서는 주상변압기 절연유의 가속열화반응을 수행하였다. 유중가스를 air bubbling법으로 추출하여 가스크로마토그라프로 성분을 분석하였으며 가스농도는 각 가스의 추출율을 감안하여 보정하였다. 절연재료의 열화는 열분해반응과 산화반응에 의하여 진행되었으며 두종류의 반응은 모두 0차반응의 특성을 보였고 탄화수소류, $CO+CO_2$ 및 수소가스의 생성속도식을 얻었다. 유중가스 분석과 UV-Visible 분광광도법에 의하여 변압기내의 철심과 동코일이 열화과정에서 촉매역활을 함에 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.161-167
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• 2024

Despite the important role of manganese (Mn) in cobalt-free, Ni-rich cathode materials, existing reports on the effects of Mn as a substitute for cobalt are not consistent. In this work, we analyzed the performance of cathodes comprised of Li(Ni_1-xMn_x)O₂ (LNMO). Both beneficial and detrimental results occurred as a result of the Mn substitution. We found that a complex interplay of effects (Li/Ni mixing driven by magnetic frustration, grain growth suppression, and retarded lithium insertion/extraction kinetics) influenced the performance and was intimately related to calcination temperature. This indicates the importance of establishing an optimal reaction temperature for the development of high-performance LNMO.

• Asian-Australasian Journal of Animal Sciences
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• 제26권8호
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• pp.1102-1110
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• 2013

Following the extraction of oil for biodiesel production, oilseed press cakes are high in fat. As the dietary supplementation of fat is currently considered the most promising strategy of consistently depressing methanogenesis, it follows that oilseed press cakes may have a similar potential for $CH_4$ abatement. As such, this study aimed to characterise the nutritive value of several oilseed press cakes, glycerine and soybean meal (SBM) and to examine their effects on in vitro ruminal fermentation, digestion kinetics and $CH_4$ production. Moringa press oil seeds exhibited the greatest in sacco effective degradability (ED) of DM and CP (p<0.05). In vitro gas production (ml/g digested DM) was not affected (p = 0.70) by supplement at 48 h of incubation. In vitro DMD was increased with the supplementation of glycerine and SBM at all levels of inclusion. Moringa oilseed press cakes produced the lowest $CH_4$ (mg/g digested DM) at 6 and 12 h of incubation (p<0.05). The findings suggest that moringa oilseed press cake at 400 g/kg DM has the greatest potential of the oilseed press cakes examined in this study, to reduce $CH_4$ production, without adversely affecting nutrient degradability.

• 분석과학
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• 제37권1호
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• pp.63-78
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• 2024

The continuous increasing of the global demand of copper and nickel metals raises the interest in developing alternative technologies to produce them from copper sulfide ore. Also, in line with Egypt's vision 2030 for achieving the sustainable socioeconomic development which aims at developing alternative and eco-friendly technologies for processing the Egyptian ores to produce these strategic products instead of its importing. These metals enhance the advanced electrical and electronic industries. The current work aims at investigating the recovery of copper and nickel from Abu Swayeil copper ore using pug leaching technique by sulfuric acid. The factors affecting the pug leaching process including the sulfuric acid concentration, leaching time and temperature have been investigated. The copper ore sample was characterized chemically using X-ray fluorescence (XRF) and scanning electron microscope (SEM-EDX). A response surface methodology develops a quadratic model that expects the nickel and copper leaching effectiveness as a function of three controlling factors involved in the procedure of leaching was also investigated. The obtained results showed that the maximum dissolution efficiency of Ni and Cu are 99.06 % and 95.30%, respectively which was obtained at the following conditions: 15 % H₂SO₄ acid concentration for 6 hr. at 250 ℃. The dissolution kinetics of nickel and copper that were examined according to heterogeneous model, indicated that the dissolution rates were controlled by surface chemical process during the pug leaching. The activation energy of copper and nickel dissolution were 26.79 kJ.mol^-1 and 38.078 kJ.mol^-1 respectively; and the surface chemical was proposed as the leaching rate-controlling step.

• 자원리싸이클링
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• 제22권1호
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• pp.64-71
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• 2013

지구온난화 원인으로 지목되고 있는 $CO_2$가스를 저감시키기 위한 방안 중의 하나로 칼슘이나 마그네슘 등을 함유하는 천연규산염 광물의 탄산염화가 제안되고 있다. 전기로제강슬래그는 칼슘, 마그네슘 등 을 주성분으로 하는 규산염들로 구성되고 있어, 이 슬래그를 천연규산염 광물 대신에 탄산염화의 대상원료로 사용하면 $CO_2$가스저감은 물론 탄산칼슘과 같은 산업원료를 제조, 활용할 수 있는 가능성이 있다. 전기로제강슬래그 탄산염화에 의한 탄산칼슘 제조공정은 칼슘성분의 분리단계와 분리된 칼슘성분의 탄산염화단계로 구성된다. 슬래그 중의 칼슘성분 분리를 위한 초산침출 연구결과는 이미 보고되어 있으며 분리된 침출용액 중의 칼슘이온의 탄산염화는 고압의 $CO_2$가스 하에서도 반응속도가 매우 느린 것으로 예측되고 있다. 본 연구에서는 보다 효율적인 침출 및 탄산염화 공정의 개발을 위하여 염산수용액 침출에 의한 칼슘성분 분리에 관한 실험을 수행하였으며 그 침출결과를 초산침출 실험결과와 비교, 분석하였다. 용액 중의 $Ca^{2+}$의 $CO_2$가스에 의한 탄산염화 반응에 대한 열역학적 자료를 통하여 용액의 pH에 따른 $Ca^{2+}$과 $CaCO_3$의 phase boundary를 고찰하였다. 슬래그 중의 칼슘성분 분리를 위해서는 염산이 초산에 비하여 더욱 효율적인 침출용매이며, 염산을 침출용매로 사용 시는 침출용액 중의 미반응산의 회수 및 재순환이 유리할 것으로 기대된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권1호
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• pp.104-111
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• 2004

비소로 오염된 토양에 대해 토양세척기법을 적용하기 위한 최적의 운전조건을 도출하고자 실험을 수행하였다. 대상시료는 강원도 N광산의 광미와 경상북도 K광산 하류의 밭 토양과 하천퇴적 토양을 선정하였다. 연속추출법 실험 결과, 비소의 총함량은 21,028$\pm$190(광미), 443$\pm$7(밭 토양), 37$\pm$3(하천퇴적 토양)mg/kg으로 존재하였으며, 결합력이 약하고 쉽게 용출 가능한 비소의 농도는 최초 4단계 연속추출에 의한 총량으로 2,284$\pm$100[광미(10.9%)], 151$\pm$5[밭 토양(34.0%)], 15$\pm$3[하천퇴적 토양(39.5%)]mg/kg으로 나타났다. 수산화나트륨을 이용한 시간에 따른 용출 실험 결과, 3가지 토양 모두 적용농도(50, 100 mM)에서 6시간 이후부터 90%이상의 비소 용출 효율을 보였으며, 세척제의 최적농도는 모든 경우에 대해 200 mM이었고 진탕비는 각각 1:10(광미)과 1:5(밭 토양, 하천퇴적 토양)가 최적 조건이었다. 수산화나트륨에 의한 연속 토양세척 실험 결과, 하천퇴적 토양과 밭 토양은 연속 토양세척에 의해 세척된 토양 내의 잔존 비소 농도가 감소함을 알 수 있었으나, 광미의 경우는 거의 큰 변화가 없었다.

• KSBB Journal
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• 제32권2호
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• pp.117-123
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• 2017

Maple tree is a useful medical plant for obtaining bioactive materials such as pharmaceutics, cosmetics, food additive, etc., and there are 16 species of native maple trees in Korea. In this study, we evaluated the antioxidant activity of sap and crude extracts of Acer mono Max, a representative maple species. The crude extracts were obtained by solvent extraction (water, ethanol, and ethyl acetate) from its branches (bark and xylem). The phenolic contents and radical scavenging capacities of the extracts and the sap were evaluated in terms of half maximal effective concentration ($EC_{50}$) and kinetics by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The ethanol extracts showed the highest extraction yield, phenolic contents and antioxidant activity, and bark extracts showed better antioxidant activity than xylem extracts. The antioxidant activity of the sap was very low, but the $EC_{50}$ of ethanol and ethyl acetate extracts ranged from 68 to $79{\mu}g/mL$, similar to that ($60{\mu}g/mL$) of the control, butylated hydroxytoluene (BHT). The DPPH radical scavenging rate ($220{\sim}760{\mu}M/min$) and the second-order reaction rate constant ($6.48{\sim}7.04L/g{\cdot}min$) of these extracts were better than those of BHT ($55{\sim}370{\mu}M/min$ and $3.60L/g{\cdot}min$). These results suggest that A. mono Max. is one of the useful bioresources for obtaining antioxidant biologically active substances, and it is possible to obtain physiologically active substances from by-product of its pruning while minimizing the effect on the growth of the tree.

• 한국환경과학회지
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• 제23권6호
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• pp.1157-1163
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• 2014

The solid phase extractant (PVC-D2EHPA bead) was prepared by immobilizing di-2-ethylhexyl-phosphoric acid (D2EHPA) with polyvinyl chloride (PVC). The prepared PVC-D2EHPA beads were characterized by using fourier transform infrared spectrometer (FTIR) and scanning electron microscopy (SEM). The removal experiments of Cu(II) by PVC-D2EHPA beads conducted batchwise. The removal kinetics of Cu(II) was found to follow the pseudo-second-order model. The equilibrium data fitted well with Langmuir isotherm model and the maximum removal capacity was 2.6 mg/g at $20^{\circ}C$. The optimum pH region was in the range of 3.5 to 6. and the standard free energy (${\Delta}G^{\circ}$) was between -4.67~-4.98 kJ/mol, indicating the spontaneous nature of Cu(II) removal by PVC-D2EHPA beads.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.9-12
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• 2002

Diffusive transport of volatile organic compounds(VOCs) and their degradation by bacteria in unsaturated soils are couple by poorly understood mass transfer kinetics at the gas/water interface. Determination of the fate of VOCs in unsaturated soil is necessary to evaluate the feasibility of natural attenuation as a VOC remediation strategy. The objective of this study was to develop a mechanistically based mathematical model that would consider the interdependence of VOC transport, microbial activity, and sorptive interaction in a moist, unsaturated soil. Because the focus of the model was on description of natural attenuation, the advective VOC transport that is induced in engineered remediation processes such as vapor extraction was not considered. The utility of the model was assessed through its ability to describe experimental observations form diffusion experiments using toluene as a representative VOC in well-defined soil columns that contained a toluene degrading bacterium, Pseudomonas Putida, as the sole active microbial species. The coefficient for gas-liquid mass-transfer, K$\sub$LA/, was found to be a key parameter controlling the ability of bacteria to degrade VOCs. This finding indicates that soil size and geometry are likely to be important parameters in assessing the possible success of natural attenuation of VOCs in contaminated unsaturated soils.