• 식물조직배양학회지
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• 제27권4호
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• pp.339-343
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• 2000

When plants are exposed to subfreezing temperatures ice crystals are forming within extracelluar space in leaves. The growth of ice crystal is closely related to the degree of freezing injury. It was shown that an antifreeze protein binds to an ice nucleator through hydrogen bonds to prevent growth of ice crystal and also reduces freezing damage. The antifreeze proteins in plants are similar to PR proteins but only the PR proteins induced upon cold acclimation were shown to have dual functions in antifreezing as well as antifungal activities. Three of the genes encoded for CLP, GLP, and TLP were isolated from barley and Kentucky bluegrass based on amino acid sequence revealed after purification and low temperature-inducibility as shown in analysis of the protein. The deduced amino acid of the genes cloned showed a signal for secretion into extracellular space where the antifreezing activity sup-posed to work. The western analysis using the antisera raised against the antifreeze proteins showed a positive correlation between the amount of the protein and the level of freeze tolerance among different cultivars of barely. Besides it was revealed that TLP is responsible for a freeze tolerance induced by a treatment of trinexapac ethyl in Kentucky bluegrass. Analysis of an overwintering wild rice, Oryza rufipogon also showed that an acquisition of freeze tolerance relied on accumulation of the protein similar to CLP. The more direct evidence for the role of CLP in freeze tolerance was made with the analysis of the transgenic tobacco showing extracellular accumulation of CLP and enhanced freeze tolerance measured by amount of ion leakage and rate of photosynthetic electron transport upon freezing. These antifreeze proteins genes will be good candidates for transformation into crops such as lettuce and strawberry to develop into the new crops capable of freeze-storage and such as rose and grape to enhance a freeze tolerance for a safe survival during winter.

• 멤브레인
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• 제26권6호
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• pp.432-448
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• 2016

최근 이온 교환 고분자 전해질 막을 활용한 고효율 에너지 전환 및 저장 장치에 대한 연구가 활발히 이루어지고 있다. 고분자 전해질 연료전지, 레독스 흐름전지 및 역전기투석 등 다양한 에너지 시스템에서 에너지 효율 향상을 위해 이온교환 전해질 막의 양/음이온의 선택적 수송 거동이 중요시되고 있다. 본 총설은 각각의 고효율 전해질 전지 시스템에 따라 요구되는 다양한 이온 교환막의 선택적 양/음이온 투과 거동의 한계점을 고찰하고, 한계를 극복하기 위한 다양한 구조의 고분자 이온 교환 복합막의 장점 및 단점을 정리하였다. 고분자 가교법 및 다공성 지지체 복합막 이외에 다양한 구조의 신규다공성 무기 나노입자를 유-무기 이온교환 복합막에 도입하는 시도가 이루어지고 있는 동시에, 이온 선택도 향상을 위한 다양한 형태의 표면 개질 방법이 개발되고 있으며, 이를 통해 이온 교환 복합막의 선택적 양/음이온 거동의 한계를 극복하는 전략을 제시하고 있다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.467-470
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• 2006

For a mobile application such as cellular phone, micro fuel cells should be extremely compact and thin. RHFC can be an alternative solution because RHFC gives higher power density than DMFC and does not need ahydrogen storage vessel In this paper, RHFC using methanol fuel is made as a novel planar design without a PROX. Both reformer and cell are made closely in a same plate to share the heater of reformer with the cell. The PBI membrane is used in the cell. The reason is that high temperature of reformer can cause a performance drop when perfluorosulfonic acid membrane such as Nafion is used such a high temperature operation also guarantees the higher CO tolerance to MEA catalyst. The cell is designed as an air-breathing type which the cathode of the cell is opened to the air. The commercial Cu/ZnO/Al2O3 steam reformer catalyst is packed in reformer channel. The active area of MEA is $11.9cm^2$ and the peak power density was $27.5mW/cm^2$.

• Advances in Energy Research
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• 제4권2호
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• pp.177-187
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• 2016

Ammonia borane $NH_3BH_3$ solubilized in organic solvent is a potential liquid-state chemical hydrogen storage material. In this study, metal acetylacetonates like $Fe(O_2C_5H_7)_3$, $Co(O_2C_5H_7)_2$, $Ni(O_2C_5H_7)_2$, $Pd(O_2C_5H_7)_2$, $Pt(O_2C_5H_7)_2$ and $Ru(O_2C_5H_7)_3$ are considered for assisting dehydrocoupling of ammonia borane in diglyme (0.135 M) at $50^{\circ}C$. The molar ratio between ammonia borane and metal acetylacetonate is fixed at 100. A protocol for the separation of the soluble and insoluble fractions present in the slurry is proposed; it consists in using acetonitrile to make the precipitation of metal-based compounds easier and to solubilize boron-based intermediates/products. The nature of the metal does not affect the dehydrocoupling mechanisms, the $^{11}B\{^1H\}$ NMR spectra showing the formation of the same reaction intermediates. The aforementioned metal acetylacetonates do mainly have effect on the kinetics of dehydrocoupling. Dehydrocoupling takes place heterogeneously and dehydrogenation of ammonia borane in these conditions leads to the formation of polyborazylene via intermediates like e.g., B-(cyclodiborazanyl) amine-borane and borazine. Our main results are reported and discussed herein.

• Advances in Energy Research
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• 제1권1호
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• pp.1-12
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• 2013

In this work, we present the catalytic dehydrogenation of hydrazine borane $N_2H_4BH_3$ (HB) using supported nickel catalysts at $50^{\circ}C$. In the presence of monometallic nickel catalysts, the dehydrogenation of HB is a one-step reaction consisting of the hydrolysis of the $BH_3$ group only. The challenge is to activate nickel to make it reactive towards the $N_2H_4$ moiety of HB. A set of 52 catalysts were prepared by using 2 supports ($Al_2O_3$ and $TiO_2$), 5 nickel precursors and 3 preparation methods. For the first time, we show that the supported nickel catalysts are able to dehydrogenate the $NH_3$ moiety of HB. In our experimental conditions, the best results were obtained with 20 wt% Ni-$Al_2O_3$ and 20 wt% Ni-$TiO_2$, with ca. 190 mL $H_2+N_2$ generated over a total theoretical volume of 283 mL, suggesting $H_2$ selectivity of 37 and 32%, respectively. Both catalysts were then characterized by EDX, XPS, and XRD. Our achievement is the first step forward and opens new perspectives for developing catalysts for the total dehydrogenation of HB.

• 한국결정성장학회지
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• 제6권2호
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• pp.213-219
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• 1996

$300^{\circ}C$ 이상의 고온에서 동작하는 전통적인 $SnO_{2}$ 또는 ZnO와 같은 전통적인 세라믹 가스 센서보다 훨씬 낮은 온도에서 동작이 가능한 $Pt/MoO_{3}$ 가스 센서를 pellet 형으로 제작하였다. $Pt/MoO_{3}$ 가스 센서의 하고 온도(calcination temperature)에 따른 표면구조의 변화와 결정구조의 변화가 투과전자현미경(transmission electron microscopy)과 X-선 회절시험에 의하여 조사되었다. 투과전자현미경 사진으로부터 하소 온도가 증가할수록 시편에서 $PtCl_{x}$에서 Cl의 양이 줄어드는 것과 Pt위에 $MoO_{3}$의 얇은 막(overlayer)이 형성되어 있다는 것을 보여준다. 가스 흡착 시험 결과 표면구조의 변화에 따라서 시편의 수소 저장 능력이 변화함을 보여주었다. $50^{\circ}C$와 $150^{\circ}C$에서 수소가스 감지도를 측정한 결과 매우 우수한 결과를 보여 주었다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.267-273
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• 2012

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber-the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam-was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• 공업화학
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• 제3권1호
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• pp.1-6
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• 1992

메탄올은 저급(低級) 탄소원(炭素源)의 활용(活用)이란 측면(側面)에서, 에너지 저장(貯藏) 운송(運送)이란 관점(觀點)에서 점점 관심(關心)을 끌고 있다. 특히 저급탄소원(低級炭素源)으로부터의 메탄올 합성기술(合成技術)은 이미 상업화(商業化)되어 있는 기술(技術)이기 때문에 더욱 현실적(現實的)인 기술(技術)로 대두되고 있다. 메탄올은 발전(發電), 도시(都市)가스, 화학원료(化學原料) 및 운송연료(運送燃料)로 저급(低級) 탄소원(炭素源)을 활용(活用)할 경우(境遇), 상호(相互) 연계(連繫)하는 매개체(媒介體)로 사용(使用)할 수 있으므로 이를 국익(國益) 차원(次元)에서 C1화학(化學) 기술(技術)을 통한 연계방안(連繫方案)을 기술(技術)하려고 시도하였다. 특히 이산화탄소(二酸化炭素)를 자연계(自然界)에서처럼 일종(一種)의 수소저장(水素貯藏) 수단(手段)으로 메탄올 합성(合成)에 이용(利用)함으로 지구온난화(地球溫暖化) 같은 환경문제(環境問題)를 줄이는 방안(方案)으로 제시(提示)했다.

• Korea-Australia Rheology Journal
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• 제14권3호
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• pp.129-138
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• 2002

A cationic surfactant, cetyltrimethylammonium $\rho$-toluenesufonate (CTA$\rho$TS), forms long threadlike micelles in aqueous solution. The threadlike micelles make concentrated entanglement networks, so that the solution shows pronounced viscoelastic behavior as concentrated polymer systems do. However, a mechanism for a process responsible for the longest relaxation time of the threadlike micellar system is different from that of semi-dilute to concentrated polymer systems. The threadlike micellar system exhibits unique viscoelasticity described by a Maxwell model. The longest relaxation time of the threadlike micellar system is not a function of the concentration of CTA$\rho$TS, but changes with that of $\rho$-toluenesufonate ($\rho$$TS^{-}$) ions in the bulk aqueous phase supplied by adding sodium $\rho$-toluenesulfonate (NapTS). The rates of molecular motions in the threadlike micelles are not influenced by the concentration of $\rho$$TS^{-}$ anions, therefore, molecular motions in the threadlike micelles (micro-dynamics) are independent of the longest relaxation mechanism (macro-dynamics). A nonionic surfactant, oleyldimethylamineoxide (ODAO), forms long threadlike micelles in aqueous solution without any additives. The aqueous threadlike micellar system of ODAO also shows Maxwell type viscoelastic behavior. However, the relaxation mechanism for the longest relaxation process in the system should be different from that in the threadlike micellar systems of CTA$\rho$TS, since the system of ODAO does not contain additive anions. Because increase in the average degree of protonation of head groups of ODAO molecules in micelles due to adding hydrogen bromide causes the relaxation time remarkably longer, changes in micro-structure and micro-dynamics in the threadlike micelle are closely related to macro-dynamics in contrast with the threadlike micellar system of CTA$\rho$TS.

• 한국식품영양과학회지
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• 제22권5호
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• pp.570-575
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• 1993

양조간장 분말을 Sephadex 겔 여과 크로마토그래피법으로 분획한 후, 가장 갈색도가 높은 melanoidin 관련 물질의 획분인 melanoidin related products(MRPs)을 모아 동결 건조시킨 다음, 이의 free redical scavenger 기능, 항산화 효력상승제의 기능과 금속 킬레이터로서의 기능, 리폭시게나아제 활성 저해능, 그리고 저장안전성 등에 대한 항산화 특성을 고찰한 결과 다음과 같다. MRPs는 첨가농도(혹은 갈색도)의 증가에 따라 과산화물의 생성을 저해하였으며, 그 항산화력은 ${\alpha}-토코페롤$ 보다는 낮았다. 그리고 free redical scavenger로서의 능력을 가지고 있어 리놀레산 혼합물의 산호를 지연 시켰으며, 염화제일철에 의하여 촉매된 산화반응에서 synergistic antioxidative effect를 나타내었다. 또한 양조간장 MRPs는 리폭시게나아제 활성을 저해하여 conjugated dienoic acid 생성량을 감소시켰다. 한편, 이 MRPs는 저장 안전성이 상당히 있어, $50^{\circ}C$에서 15일간 저장되어 있어도 항산화 효과의 상실이 거의 없음이 관찰되었다.