• 한국세라믹학회지
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• 제56권3호
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• pp.284-290
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• 2019

Ternary MoS₂/graphene (G)-TiO₂ photocatalysts were prepared by a simple hydrothermal method. The morphology, phase structure, band gap, and catalytic properties of the prepared samples were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-vis spectrophotometry, and Brunauer-Emmett-Teller surface area measurement. The H₂ production efficiency of the prepared catalysts was tested in methanol-water mixture under visible light. MoS₂/G-TiO₂ exhibited the highest activity for photocatalytic H₂ production. For 5 wt.% and 1 wt.% MoS₂ and graphene (5MT-1G), the production rate of H₂ was as high as 1989 µmol^-1h^-1. The catalyst 5MT-1G showed H₂ production activity that was ~ 11.3, 5.6, and 4.1 times higher than those of pure TiO₂, 1GT, and 5MT, respectively. The unique structure and morphology of the MoS₂/G-TiO₂ photocatalyst contributed to its improved hydrogen production efficiency under visible light.

• Animal Bioscience
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• 제35권10호
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• pp.1616-1627
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• 2022

Objective: This work was conducted to investigate the effects of oxidative stress on meat quality, mitochondrial function, calcium metabolism and ferroptosis of broilers. Methods: In this study, a total of 144 one-day-old male Ross 308 chicks were divided into 3 groups (control group, saline group, and hydrogen peroxide [H₂O₂] group) with 6 replicates of 8 broilers each. The study lasted for 42 d. The broilers in the saline and H₂O₂ groups were intraperitoneally injected with 0.75% saline and 10.0% H₂O₂ on the 16th and 37th day of the experimental period respectively, the injection volumes were 1.0 mL/kg of broiler body weight. On the 42nd day of the experimental period, two chicks were randomly selected from each cage, a total of thirty-six chicks were stunned by electric shock and slaughtered to collect breast muscle samples. Results: The H₂O₂ exposure reduced pH value, increased drip loss and shear force of breast meat (p<0.05), impaired the ultrastructure and function of mitochondria. The H₂O₂ exposure damaged the antioxidant system in mitochondria, excessive reactive oxygen species carbonylation modified calcium channels on mitochondria, which impaired the activities of key enzymes on calcium channel, resulted in the increased calcium concentration in cytoplasm and mitochondria (p<0.05). In addition, the H₂O₂ exposure increased the iron content and lipid peroxidation (p<0.05), which induced ferroptosis. Conclusion: Oxidative stress could impair meat quality by causing mitochondrial dysfunction, resulting in calcium metabolism disorder and ferroptosis.

• Journal of Plant Biotechnology
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• 제48권4호
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• pp.278-288
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• 2021

The development of bioenergy through biomass has gained importance due to the increasing rates of fossil fuel depletion. Biomass is important to increase the productivity of bioethanol, and production of biomass with high biomass productivity, low lignin content, and high cellulose content is also important in this regard. Inorganic salts are important in the cultivation of biomass crops for the production of biomass with desirable characteristics. In this study, the roles of various inorganic salts in biomass and bioethanol production were investigated using an in vitro tobacco culture system. The inorganic salts evaluated in this study showed dramatic effects on tobacco plant growth. For example, H₂PO₄ substantially improved plant growth and the root/shoot (R/S) ratio. The chemical compositions of tobacco plants grown in media after removal of various inorganic salts also showed significant differences; for example, lignin content was high after Mg²⁺ removal treatment and low after K⁺ treatment and H₂PO₄ removal treatment. On the other hand, NO₃^- and H₂PO₄ treatments yielded the highest cellulose content, while enzymatic hydrolysis yielded the highest glucose concentration ratio 24 h after NH₄⁺ removal treatment. The ethanol productivity after H₂PO₄ removal treatment was 3.95% (w/v) 24 h after fermentation and 3.75% (w/v) after 36 h. These results can be used as the basis for producing high-quality biomass for future bioethanol production.

• 공업화학
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• 제34권3호
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• pp.327-329
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• 2023

본 연구에서는 Clostridium ljungdahlii 배양에서 유기질소공급물인 tryptone과 sodium tungstate의 배양액 내 농도가 균주 성장과 아세트산, 에탄올 생산에 대한 영향을 확인하기 위한 실험을 수행하였다. 대조군 실험의 배지 조건(0 g/L tryptone)보다 tryptone 2.5 g/L를 투입한 경우 균주 성장이 144.6% 증가하였고, 에탄올 및 아세트산 생산은 각각 8.6%와 36.7% 향상되었다. 대조군 실험에 사용된 배지의 조건(0.01 µM Na₂WO₄·2H₂O)보다 100배인 1 µM Na₂WO₄·2H₂O를 사용한 실험군에서, 균주 성장과 C2 대사산물의 총생산량에는 큰 차이가 없지만, 에탄올 생산 증가하고 아세트산 생산은 감소하여 에탄올/아세트산 생산비가 0.56로 대조군의 0.24에서 크게 증가하였다.

• 생명과학회지
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• 제25권6호
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• pp.673-679
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• 2015

본 연구에서는 재비늘버섯(Pholiota highlandensis)의 리그닌 분해 활성을 확인하고, laccase 생산을 위한 최적 배양 조건을 조사하였다. 재비늘버섯 균사체로부터 laccase를 생산하기 위한 배지조건을 조사한 결과, 다양한 합성 배지 중에서 Coriolus versicolor 배지(2% dextrose, 0.4% peptone, 0.6% yeast extract, 0.046% KH₂PO₄, 0.1% K₂HPO₄, 0.05% MgSO₄·7H₂O)가 가장 높은 laccase 활성을 나타내었다. Laccase생산에 대한 배양 조건을 최적화하기 위하여 Coriolus versicolor 배지의 조성 중에서 탄소원, 질소원, 인산원, 무기염에 대한 영향을 조사하였다. 탄소원, 질소원, 인산원, 무기염은 각각 2% fructose, 0.4% peptone 및 0.6% yeast extract, 0.05% NaH₂PO₄, 0.05% MgSO₄·7H₂O의 경우에 가장 높은 효소활성을 나타내었다. 본 균주는 몇 가지 방향족 화합물에 의해 laccase 생산이 유도되었고, guaiacol을 첨가할 경우 25℃에서 11일 동안 배양하였을 때 효소의 활성이 최대치(114.1 U/ml)에 도달하였다. 또한 본 균주의 laccase 생산을 위한 최적 pH와 온도는 각각 8.0과 35℃를 나타내었다. 최적 조건에서 배양된 균사체 배양 상등액을 Native-PAGE로 전기영동한 후 ABTS를 기질로 사용하여 활성염색을 수행한 결과, 약 90 kDa 부근에서 laccase 활성을 가지는 1개의 밴드를 확인하였다.

• 자원리싸이클링
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• 제30권6호
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• pp.12-18
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• 2021

수성가스 전환 반응은 가스화로 생성된 합성 가스에 수소 생산 증가와 H₂/CO 비율 제어를 위해 수증기를 첨가하는 가스화 후속 공정이다. 본 연구에서는 RPF(Refuse plastic fuel) 가스화 시스템의 합성가스를 대상으로 수성가스 전환 반응을 연구하였다. 수성가스 전환 반응은 촉매를 이용하여 high temperature shift(HTS) 와 low temperature shift(LTS) 반응에 대하여 lab scale 관형 반응기를 이용하여 반응 온도, steam/carbon ratio, 유량의 변화가 H₂ 생성과 CO 전환율에 미치는 영향을 조사하였다. 운전 온도는 HTS 시스템이 250-400℃, LTS 시스템이 190-220℃이며 steam/carbon ratio는 1.5-3.5로 변화시켰다. 반응 모의 가스의 농도는 RPF 합성가스의 농도를 기준으로 CO, 40vol%, H₂, 25vol%, CO₂, 25vol%이다. 반응 온도와 steam/carbon ratio가 증가함에 따라 CO 전환율 및 H₂ 생성량이 증가하고, 유량이 증가하면 촉매층의 체류시간 단축으로 CO 전환율과 H₂ 생성량이 감소하였다.

• 한국태양에너지학회 논문집
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• 제33권2호
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• pp.93-100
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• 2013

Two-step thermochemical cycle using ferrite-oxide($Fe_2O_4$) device was investigated. The $H_2O$(g) was converted into $H_2$ in the first experiment which was performed using a dish type solar thermal system. However the experiment was lasted only for 2 cycles because the metal oxide device was sintered and broken down. Another problem was that the reaction was taken place mainly on a side of the metal oxide device. The m-$ZrO_2$, which was widely known as a material preventing sintering, was applied on the metal oxide device. The ferrite loading rate and the thickness of the metal oxide device were increased from 10.67wt% to 20wt% and from 10mm to 15mm, respectively. The chemical reactor having two inlets was designed in order to supply the reactants uniformly to the metal oxide device. The second-experiment was lasted for 5 cycles, which was for 6 hours. The total amount of the $H_2$ production was 861.30ml. And cerium oxide($CeO_2$) device was used for increasing $H_2$ production rate. $CeO_2$ device had low thermal resistance, however, more $H_2$ production rate than $Fe_2O_4$ device.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.308-310
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• 2022

Ultrawide bandgap gallium oxide (Ga₂O₃) semiconductors are known to have excellent photocatalytic properties due to their high redox potential. In this study, CO₂ reduction is demonstrated using nanostructured Ga₂O₃ photocatalyst under ultraviolet (254 nm) light source conditions. After the CO₂ reduction, C₂H₄ remained as a by-product in this work. Nanostructured Ga₂O₃ photocatalyst also showed an excellent endurance characteristic. Photogenerated electron-hole pairs boosted the CO₂ reduction to C₂H₄ via nanostructured Ga₂O₃ photocatalyst, which is attributed to the ultrawide and almost direct bandgap characteristics of the gallium oxide semiconductor. The findings in this work could expedite the realization of CO₂ reduction and a simultaneous C₂H₄ production using a low cost and high performance photocatalyst.

• Animal Bioscience
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• 제37권2_spc호
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• pp.323-336
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• 2024

Molecular hydrogen (H₂) and formate (HCOO^-) are metabolic end products of many primary fermenters in the rumen ecosystem. Both play a vital role in fermentation where they are electron sinks for individual microbes in an anaerobic environment that lacks external electron acceptors. If H₂ and/or formate accumulate within the rumen, the ability of primary fermenters to regenerate electron carriers may be inhibited and microbial metabolism and growth disrupted. Consequently, H₂- and/or formate-consuming microbes such as methanogens and possibly homoacetogens play a key role in maintaining the metabolic efficiency of primary fermenters. There is increasing interest in identifying approaches to manipulate the rumen ecosystem for the benefit of the host and the environment. As H₂ and formate are important mediators of interspecies interactions, an understanding of their production and utilization could be a significant starting point for the development of successful interventions aimed at redirecting electron flow and reducing methane emissions. We conclude by discussing in brief ruminant methane mitigation approaches as a model to help understand the fate of H₂ and formate in the rumen ecosystem.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.140-145
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• 2024

High temperature co-electrolysis of H₂O-CO₂ mixtures using solid oxide cells has attracted attention as promising CO₂ utilization technology for production of syngas (H₂/CO), feedstock for E-fuel synthesis. For direct supply to E-fuel production such as hydrocarbon and methanol, the outlet gas ratio (H₂/CO/CO₂) of co-electrolysis should be controlled. In this work, current voltage characteristic test and product gas analysis were carried out under various reaction conditions which could attain proper syngas ratio.