• 환경위생공학
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• 제23권2호
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• pp.1-18
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• 2008

The tetrachloroethylene (PCE) dehalogenase of Clostridium bifermentans DPH-1 (a halorespiring organism) was purified, cloned, and sequenced. This enzyme is a homodimer with a molecular mass of ca. 70 kDa and exhibits dehalogenation of dichloroethylene isomers along with PCE and trichloroethylene (TCE). Broad range of substrate specificity for chlorinated aliphatic compounds (PCE, TCE, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloropropene, and 1,1,2-trichloroethane) for this enzyme was also observed. A mixture of propyl iodide and titanium citrate caused a light-reversible inhibition of enzymatic activity suggesting the involvement of a corrinoid cofactor. A partial sequence (81 bp) of the encoding gene for PCE dehalogenase was amplified and sequenced with degenerateprimers designed from the N-terminal sequence (27 amino acid residues). Southern analysis of C. bifermentans genomic DNA using the polymerase chain reaction product as a probe revealed restriction fragment bands. A 5.0 kb ClaI fragment, harboring the relevant gene (designated pceC) was cloned (pDEHAL5) and the complete nucleotide sequence of pceC was determined. The gene showed homology mainly with microbial membrane proteins and no homology with any known dehalogenase, suggesting a distinct PCE dehalogenase. So, C. bifermentans could play some important role in the initial breakdown of PCE and other chlorinated aliphatic compounds in sites contaminated with mixtures of halogenated substances.

• 한국유기농업학회지
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• 제19권spc호
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• pp.161-164
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• 2011

Nitrogen fixation by legumes can be valuable sources for organic farming. This study was to investigate the effect of different legume mixtures on nitrogen fixation and transfer to grasses on spring paddy field. Three different mixtures were used (rye+hairy vetch, Italian ryegrass+crimson clover, oat+pea) in a randomized complete block design with three replications and sowed in pots with different sowing rate (5:5 rye:hairy vetch,7:3=Italian:crimson, 6:4=oat:pea) on early March. $(^{15}NH_4)SO_4$ solution at. 99.8 atom%$^{15}N$ was applied to the each pot at the rate of 2kg N $ha^{-1}$ on $16^{th}$ April. Forage were harvested at ground level in heading stage and separated into legume and grass. Total N content and $^{15}N$ value were determined using a continuous flow stable isotope ratio mass spectrometry. DM yield of rye+vetch, Italian+crimson and oat+pea were 6,607, 3,213 and 4,312kg/ha, respectively. Proportion of N from fixation was 0.73(rye+vetch), 0.42(Italian+crimson) and 0.93(oat+pea). The percentages of N transfer from legume to grass were from 61% to 24% in different method by treatments and -35% to 21% in isotope dilution method.

• Membrane and Water Treatment
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• 제10권3호
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• pp.201-206
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• 2019

In this study, we performed an electrowinning process for effective removal of metals (Cu and Ni) in solution and their recovery as solid forms. A complete removal of Cu and Ni (1,000 mg/L) was observed during four times recycling test, indicating that our electrowinning system can ensure the efficient metal removal with high stability and durability. In addition, we investigated effect of operation parameters (i.e., concentration of boric acid only for Ni, variation of pH, concentration of electrolyte ($H_2SO_4$), and cell voltage) on the efficiency of metal removal (Cu and Ni) during the electrowinning. The addition of boric acid significantly enhanced removal efficiency of Ni as the concentration of boric acid increased up to 10 g/L. Compared to negligible pH effect (pH 1, 2, and 4) on the Cu removal, we observed the increase in removal efficiency of Ni as the pH increased from 1 to 4. The electrolyte concentration did not significantly influence the removal of Cu and Ni in this study. We also obtained great removal rates of Cu and Ni at 2.5 V and 4.0 V, which were much faster than those at lower voltages. Finally, almost 99% of each Cu and Ni (1,000 mg/L) was selectively removed from the mixture of metals by adjusting pH and addition of boric acid after the completion of Cu removal. The findings in this study can provide a fundamental knowledge about effect of important parameters on the efficiency of metal recovery during the electrowinning.

• 대한금속재료학회지
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• 제49권1호
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• pp.52-57
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• 2011

Nickel ferrite ($NiFe_2O_4$) powder was prepared through the ceramic route by calcination of a stoichiometric mixture of nickel oxide (NiO) and iron oxide ($Fe_2O_3$). The pressed pellets of $NiFe_2O_4$ were isothermally reduced in pure hydrogen at 800, 900, 1000 and $1100^{\circ}C$. Based on thermogravimetric analysis, the reduction behavior and the kinetic reaction mechanisms of the synthesized ferrite were studied. The initial ferrite powder and various reduction products were characterized by XRD, SEM, reflected light microscope and VSM to reveal the effect of hydrogen reduction on the composition, microstructure, magnetic properties and reaction kinetics of the produced Fe-Ni alloy. Complete reduction of the $NiFe_2O_4$ was achieved with synthesis of homogeneous nanocrystalline Fe-Ni alloys. Arrhenius equation with the approved mathematical formulations for a gas-solid reaction was applied for calculating the activation energy ($E_a$) values and detecting the controlling reaction mechanism.

• Journal of the Korean Wood Science and Technology
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• 제50권5호
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• pp.315-324
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• 2022

The termicidal activity and chemical components of wood vinegar from two sources of biomass, nipah fruit shells (NFS) and a mixture of shells and fiber (MSF), were evaluated against Coptotermes curvignathus. A no-choice test was carried out to evaluate their termicidal activity using filter paper samples treated with 2.5%, 5.0%, 7.5%, 10.0%, and 12.5% NFS or MSF vinegar. Both wood vinegars exhibited antitermitic activity against C. curvignathus. The results show that increased concentrations of NFS and MSF vinegar significantly increased termite mortality. In particular, the NFS vinegar caused complete mortality and the lowest filter paper mass losses at 2.18% when treated with 12.5% wood vinegar. The most abundant chemical compounds of NFS vinegar were cyclopropanecarbonyl chloride, 2,5-dichlorophenol, 2-propanone, acetic acid, propanoic acid, benzenesulfonic acid, 3,7-dimethyl-6-octenal, and trans-geraniol. Meanwhile, the main compounds in the MSF vinegar were 1,2-ethanediol, formic acid, acetic acid, ethanoic acid, 2-furancarboxaldehyde, phenol, 2-methoxy phenol, and 4-methyl phenol.

• Geomechanics and Engineering
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• 제33권2호
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• pp.155-165
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• 2023

Hurricane Katrina swept New Orleans, Louisiana, USA, in 2005, causing more than 1,000 fatalities and severe damage to the flood protection system. Recovery activities are complete, however, clarifying failure mechanisms and devising resilient and cost-effective retrofitting techniques for the flood protection system are still of utmost importance to enhance the general structural integrity of water retaining structures. This study presents extensive centrifuge test results to find various failure mechanisms and effective retrofitting techniques for a levee system. The result confirmed the rotational failure and translational failure mechanisms for the London Ave. Canal levee and 17^th St. Canal levee, respectively. In addition, it found that the floodwalls with fresh waterstop in their joints perform better than those with old/weathered waterstop by decreasing pore water pressure build-up in the levee. Structural caps placed on the top of the joints between I-walls could also prevent local failure by spreading the load to surrounding walls. At the same time, the self-sealing bentonite-sand mixture installed along the riverside of floodwalls could mitigate the failure of floodwalls by blocking the infiltration of seepage water into the gap formed between levee soils and floodwalls.

• 농업과학연구
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• 제49권4호
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• pp.857-869
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• 2022

Eggs are considered an excellent complete food because they contain many major energy sources, including protein. Eggs are one of the most widely consumed foods worldwide, and egg consumption is steadily increasing. Eggs are generally classified according to their quality and weight. Various characteristics of eggs must be considered for the design and effective utilization of equipment used for the transport, processing, packaging, and storage of eggs. In this study, egg surface area, volume, density, etc. were measured according to the grade of the egg. The values of several geometrical properties that were measured tended to increase with increasing egg grade. The smallest grade eggs had the lowest shell thickness and density. The electrical conductivity of the eggshell and its contents was measured with a self-made electrode and equipment. The egg shell showed properties similar to insulators, and as the thickness increased, the electrical conductivity tended to increase. The electrical conductivity of the egg yolk showed almost constant values under all conditions. The electrical conductivity of the egg white and mixture was particularly low at 0.1 kHz. Fouling and electrode corrosion occurred in a low frequency region due to the egg white. In this study, various geometric and electrical characteristics of eggs were measured, and based on this, factors that could serve as new indicators for egg processed production were analyzed and investigated.

• Journal of Animal Science and Technology
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• 제48권3호
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• pp.375-382
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• 2006

본 시험에 사용된 생약제제는 지황, 천궁, 감초, 오미자, 차전차, 산약, 둥글레, 당귀 및 황백 등 24가지의 생약을 적절히 배합한 혼합생약제제(고뿔??)로서 육성돈 사료에 첨가 급여시 생산성, 혈액 내 면역관련 혈액학적 지표, 분내 휘발성 지방산 및 암모니아태 질소 함량에 미치는 영향을 규명하고자 실시하였다. 시험동물은 3원 교잡종(Landrace×Yorkshire×Duroc) 육성돈 80두를 공시하였으며 시험개시시의 체중은 16.35±0.05kg 이었고 1) NC (negative control; antibiotics-free diet), 2) PC (positive control; NC diet added 0.16% antibiotic), 3) NCK0.2 (NC diet added 0.2% herbal product(koppuul??)), 4) PCK0.1 (PC diet added 0.1% herbal product (koppuul??))로 4개 처리를 하여 처리당 5반복 반복당 4두씩 임의 배치하여 42일간 실시하였다. 총 사양시험 기간 동안 일당증체량에서는 PCK0.1구와 PC구가 NC구와 비교하여 유의적으로 높게 나타났고(P<0.05) 사료효율에서는 PC구가 NC구와 비교하여 유의적으로 높았다(P<0.05). 혈액 내 백혈구수와 IgG 함량의 변화는 PC, NCK0.2와 PCK0.1구가 NC구와 비교하여 유의적으로 높은 경향을 보였다(P<0.05). Lymphocyte의 경우 PCK0.1구에서 증가량이 유의적으로 가장 높았으며 대조구가 가장 낮게 나타났다(P<0.05). 분내 암모니아태 질소 함량을 보면 NCK0.2구가 항생제를 첨가한 PC구와 대조구에 비해 유의하게 낮은 결과를 보였다(P<0.05). 건물과 질소 소화율에서는 항생제를 0.16% 첨가한 PC구에서 높은 경향을 보였으나 전 처리구에서 유의적인 차이를 보이지 않았다. 결과적으로 육성돈 사료 내 생약제 또는 항생제 첨가시 일당증체량, 혈액 내 백혈구수와 IgG 함량을 증가시키고 분내 암모니아태 질소 함량을 감소시키는 것으로 사료된다.

• Journal of Animal Science and Technology
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• 제44권2호
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• pp.221-232
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• 2002

시험은 사료내 필수아미노산 결핍이 rat의 사료섭취량과 혈액 및 뇌내 전이상엽피질(PPC)의 유리아미노산 농도 변화에 미치는 영향을 조사하여 뇌내 섭식조절 메카니즘을 구명하고자 하였다. 시험에 이용된 모든 사료의 질소원은 순수 아미노산 혼합물을 이용하였으며, 질소수준은 15%로 하였다. 사료는 하루 6시간 동안 섭취하도록 훈련을 시켰으며(17:00-21:00, meal feeding method), 사료섭취량과 증체량은 사료급여 7일째부터 매시간 측정하였다. 실험 1에서 사료섭취량과 증체량을 사료급여 후 매시간 측정하였으며, 혈액 및 PPC의 아미노산 농도는 사료급여 11일째의 0, 1, 2, 3, 6시간 후에 관찰하였다. 실험 2에서는 complete diet에서 11일째에 lysine 결핍사료로 교체하여 사료섭취량, 증체량 및 혈액 및 PPC의 아미노산 농도는 실험 1과 동일하게 측정하였다. 실험 1에서 complete diet 급여에 따른 사료섭취량은 7일째부터 일일섭취량(15g/day)을 충족하였다. 또한 11일째의 혈액 및 뇌의 유리 아미노산 농도는 사료급여 한시간 후에 증가하였으나, 그 후에는 일정한 수준을 유지하였다. 반면, 실험 2에서는 complete diet에서 lysine 결핍사료로 교체함에 따른 사료섭취량은 급격하게 감소하였고(P$<$0.05), 혈액 및 PPC의 유리 lysine 농도는 lysine 결핍사료 급여 2시간 후에 유의적(p$<$0.05)으로 감소하였으며, 누적 사료섭취량은 사료급여 4시간째 유의적으로 감소하였다(p$<$0.05). 따라서 이상의 결과로 보아 아미노산 결핍사료 섭취에 따른 혈액과 PPC의 해당 아미노산의 농도 감소는 사료섭취량의 감소에 비하여 빠르게 반응하였고, 이러한 결과로 미루어 사료중 아미노산 결핍에 반응하는 부위의 일부분으로 뇌내 PPC가 직접적인 관여를 한다고 판단된다.

• 한국양식학회지
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• 제20권1호
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• pp.19-25
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• 2007

참다랑어(Thunnus orientalis)의 배합사료 개발을 위해 전갱이(Trachrus japonicus) 근육 합성 엑기스(SE)를 사용하여 omission test를 통해 섭이촉진물질을 검색하였다. 인공종묘 생산된 참다랑어 치어(평균체중 $9.0{\pm}0.91\;g$: 실험 1, 2, 3; $1.6{\pm}0.23\;g$: 실험 4)를 사용하여 전갱이 근육 100 g 상당 함량의 각각의 섭이촉진 물질을 카제인 기초 사료에 첨가하여 총 4회의 사육실험을 실시하였다. 실험 1에서 인공합성엑기스(SE)와 SE로부터 아미노산 관련 화합물(SE-A), 핵산관련물질(SE-N) 그리고 유기염기화합물(SE-O)을 각각 제외한 시험액을 제조하여 천연 전갱이 근육 엑기스(NE)와 비교한 결과, SE-A와 SE-N구는 SE보다 낮은 섭이활성을 보였으나, SE-O구는 SE와 유사한 섭이활성을 보였다. 실험 2에서는 IMP가 섭이 촉진에 가장 많은 영향을 미치는 것이 인정되었으며, 실험 3에서는 L-alanine, L-glutamic acid, L-histidine, L-lysine, taurine 그리고 IMP의 혼합물이 SE와 섭이활성의 차이를 보이지 않았다. 실험 4에서는 L-histidine, L-glutamine 그리고 IMP 혼합물이 가장 높은 섭이활성을 보였으며, 그 다음으로는 SE, L-lysine, L-alanine and IMP 혼합물, L-histidine, L-glutamic acid, L-lysine and L-alanine과 IMP의 혼합물이 높은 섭이활성을 보였다. 본 연구결과 참다랑어 치어의 유효 섭이촉진물질은 L-histidine, L-glutamic acid 그리고 IMP로 판단되었다.