화석연료 사용에 의한 환경문제의 해결을 위한 방법의 하나로 수소에너지에 대한 연구가 활발히 진행되고 있다. 물을 분해에 의한 수소 제조는 전기분해, 광화학적, 열화학적, 생물학적 방법 등이 있다. 물의 전기분해 기술은 전기를 이용하여 수소를 물로부터 직접 제조하는 방법으로 지구오염물질인 이산화탄소의 배출이 없는 것이 특징이다. 특히, 물의 전기분해 방법 중에서 알칼리 수전해는 오래전부터 알려진 수소제조 방법으로 전해액으로 ∼30 wt%의 KOH수용액 또는 ∼20 wt%의 NaOH수용액을 사용하며, 셀은 수산화이온 (OH-) 만을 선택적으로 통과시키는 격막, 수소와 산소를 발생시키는 전극으로 구성된다. 최근에는 양.음이온교환막의 발 전과 더불어 전해효율이 60% 이상에 이를 만큼 분리막의 중요성이 부각되고 있다.

최근 기능성과 친환경 화장품에 대한 관심이 증가하고 있으며, 이에 따라 안전하면서 효능이 우수한 식물 추출물을 활용한 소재 개발이 이루어지고 있는 실정이다. 따라서 본 연구에서도 주로 건강 기능성 소재로써 다양한 효능이 있는 것으로 알려진 그라비올라 추출물이 기능성 화장품 소재로써의 가 능성을 확인하고자 하였다. 그라비올라 추출물의 항산화 활성을 확인하고자 총 폴리페놀과 총 플라보노 이드 함량, DPPH radical 소거 활성을 측정하였고, HDF 세포에서의 세포 독성을 확인한 후 적정 농도 에서 HDF 세포에 과산화수소(H2O2)를 처리하여 산화적 스트레스에 대한 ROS 활성 억제 효과와 세포 보호 효과를 측정하였다. 본 실험 결과, 그라비올라 추출물은 항산화 지표가 되는 총 폴리페놀과 플라보 노이드의 100g당 26.6 mg(CA)/100g, 14.3 mg(CA)/100g의 높은 함량을 확인하였으며, 높은 radical 소 거 활성을 확인하였다. HDF 세포에 대한 세포 생존율을 측정한 결과, 모든 농도에서 유의한 세포 독성 이 나타나지 않았으며, 추후 100 μg/mL 농도에서 실험하였다. H2O2로 유도된 HDF 세포에 ROS 활성 억제를 측정한 결과, 농도 의존적인 ROS 활성 억제 효과를 확인하였고, H2O2를 4 시간, 24 시간, 48 시간 동안 처리 후 그라비올라 추출물의 세포 보호 효과를 측정한 결과, 25 μg/mL 농도에서 24시간까 지 89.92%의 높은 세포 보호 효과를 확인하였다. 이와 같은 결과를 통하여 그라비올라 추출물은 항산 화 활성이 우수하고, HDF 세포에 대한 독성이 거의 없으며, H2O2에 의해 발생하는 활성산소에 대한 효과적인 활성 억제 효과와 세포 보호 효과가 우수한 것으로 확인됨에 따라 항산화 및 세포 보호 효과 를 가진 다양한 기능성 소재로서의 가능성을 확인하였다.

With the matters of climate change, energy security and resource depletion, a growing pressure exists to search for replacements for fossil fuels. Among various sustainable energy sources, hydrogen is thought of as a clean energy, and thus efficient hydrogen storage is a major issue. In order to realize efficient and safe hydrogen storage, various porous materials are being explored as solid-states materials for hydrogen storage. For those purposes, it is a prerequisite to characterize a material’s textural properties to evaluate its hydrogen storage performance. In general, the textural properties of porous materials are analyzed by the Brunauer-Emmett-Teller (BET) measurement using nitrogen gas as a probe molecule. However, nitrogen BET analysis is sometimes not suitable for materials possessing small pores and surfaces with high curvatures like MOFs because the nitrogen molecule may sometimes be too large to reach the entire porous framework, resulting in an erroneous value. Hence, a smaller probe molecule for BET measurements (such as hydrogen) may be required. In this study, we describe a cost-effective novel cryostat for BET measurement that can reach temperatures below the liquefaction of hydrogen gas. Temperature and cold volume of the cryostat are corrected, and all measurements are validated using a commercial device. In this way, direct observation of the hydrogen adsorption properties is possible, which can translate directly into the determination of textural properties.

In this study, two Fe-30Mn-0.2C-(1.5Al) high-manganese steels with different surface conditions were hydrogencharged under high temperature and pressure; then, tensile testing was performed at room temperature in air. The yield strength of the 30Mn-0.2C specimen increased with decreasing surface roughness(achieved via polishing), but that of the 30Mn-0.2C- 1.5Al specimen was hardly affected by the surface conditions. On the other hand, the tendency of hydrogen embrittlement of the two high-manganese steels was not sensitive to hydrogen charging or surface conditions from the standpoints of elongation and fracture behavior. Based on the EBSD analysis results, the small decrease in elongation of the charged specimens for the Fe-30Mn-0.2C-(1.5Al) high-manganese steels was attributed to the enhanced dislocation pile-up around grain boundaries, caused by hydrogen

The aim of this study is to consider the effect hydrogen on dezincification behavior of Cu-Zn alloys. The investigations include microstructural observations with scanning electron microscope and chemical composition analysis with energy dispersive spectrometer. The dezincification layer was found to occur in high pressure hydrogen atmosphere, not in air atmosphere. In addition, the layers penetrated into the inner side along the grain boundaries in the case of hydrogen condition. The shape of the dezincification layers was porous because of Zn dissolution from the α or β phase. In the case of stress corrosion cracks formed in the Cu-Zn microstructure, the dezincification phenomenon with porous voids was also accompanied by grain boundary cracking.

Isosteric heat of hydrogen adsorption is one of the most important parameters required to describe solid-state hydrogen storage systems. Typically, it is calculated from adsorption isotherms measured at 77K (liquid N2) and 87K (liquid Ar). This simple calculation, however, results in a high degree of uncertainty due to the small temperature range. Therefore, the original Sievert type setup is upgraded using a heating and cooling device to regulate the wide sample temperature. This upgraded setup allows a wide temperature range for isotherms (77K ~ 117K) providing a minimized uncertainty (error) of measurement for adsorption enthalpy calculation and yielding reliable results. To this end, we measure the isosteric heats of hydrogen adsorption of two prototypical samples: activated carbon and metal-organic frameworks (e.g. MIL-53), and compared the small temperature range (77~87K) to the wide one (77K ~ 117K).

Understanding effects of thermal pollution and acidification has long been a concern of aquatic ecologists, but it remains largely unknown in Korea. This study was performed to elucidate the effects of thermal wastewater effluent (TWE) and acid rain on water quality and attached algae in a small mountain stream, the Buso Stream, a tributary located in the Hantan River basin. A total of five study sites were selected in the upstream area including the inflowing point of hot-spring wastewater (HSW), one upstream site (BSU), and three sites below thermal effluent merged into the stream (1 m, 10 m and 300 m for BSD1, BSD2, and BSD3, respectively). Field surveys and laboratory analyses were carried out every month from December 2015 to September 2016. Water temperature ranged 1.7~28.8°C with a mean of 15.0°C among all sites. Due to the effect of thermal effluent, water temperature at HSW site was sustained at high level during the study period from 17.5°C (January) to 28.8°C (September) with a mean of 24.2±3.7°C, which was significantly higher than other sites. Thermal wastewater effluent also brought in high concentration of nutrients (N, P). The effect of TWE was particularly apparent during dry season and low temperature period (December~March). Temperature effect of TWE did not last toward downstream, while nutrient effect seemed to maintain in longer distance. pH ranged 5.1~8.4 with a mean of 6.9 among all sites during the study period. The pH decrease was attributed to seasonal acid rain and snow fall, and their effects was identified by acidophilic diatoms dominated mainly by Eunotia pectinalis and Tabellaria flocculosa during March and August. These findings indicated that water quality and periphyton assemblages in the upstream region of Buso Stream were affected by thermal pollution, eutrophication, and acidification, and their confounding effects were seasonally variable.

A black nickel oxide powder, one of the commercial nickel oxide ores, was reduced by hydrogen gas in a batchtype fluidized-bed reactor in a temperature range of 350 to 500 oC and in a residence time range of 5 to 120 min. The hydrogen reduction behavior of the black nickel oxide was found to be somewhat different from that of green nickel oxide ore. For the black nickel oxide, the maximum temperature (below which nickel oxide particles can be reduced without any agglomeration) was significantly lower than that observed for the green nickel oxide. In addition, the best curve fittings of the Avrami model were obtained at higher values of the overall rate constant “k” and at lower values of the exponent “m”, compared to those values for the green nickel oxide. It may be inferred from these results that the hydrogen reduction rate of the black nickel oxide is faster than that of the green nickel oxide in the early stages, but the situation reverses in the later stages. For the black nickel oxide ore, in spite of the low temperature sintering, it was possible to achieve a high degree fluidized-bed reduction at lower temperatures and at lower gas consumption rates than was possible for the green nickel oxide. In this regard, the use of black nickel oxide is expected to yield a benefit if its ore price is sufficiently lower than that of the green nickel oxide.

The purpose of this study was to evaluate the protective effect of PineXol® on H2O2-induced cell death in SK-N-MC cells, and in early stage focal ischemia rodent model. SK-N-MC cells were pre-treated with 200 μM H2O2 or various concentrations of PineXol® (10, 30, and 50 pg/mL) for 24 h, and then exposed to H2O2 for 3 h. Cell death was assessed by the CCK-8 assay, reactive oxygen species (ROS) assay, and lactate and dehydrogenase (LDH) release assay. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) expressions were also analyzed by western blotting. Focal ischemia rodent model was used as the in vivo model, and different concentrations of PineXol® (1, 10, and 100 mg/kg) were administered. One week after administration, reduction of infarct volume was analyzed by TTC staining. Cell viability of H2O2-treated SK-N-MC cells significantly increased by pre-treatment of PineXol® (p<0.05). PineXol® pre-treatment also induced significant decrease of ROS and LDH expressions. However, PineXol® did not affect the infarct volume. These results suggest that PineXol® has significant neuroprotective effect in vitro, but statistical significance was not confirmed in the in vivo focal ischemia mo

실리콘 폼은 고성능 가스켓, 열 차폐, 진동 마운트 및 Enter 키 패드로 많은 산업 분야에서 난연성 소재로서 매우 유용하다. 실리콘 발포체는 실온에서 백금 촉매 및 무기필러 존재하에서 비닐기를 함유한 폴리실록산 (V-silicone) 및 수산기를 함유한 폴리실록산 (OH-silicone)과 하이드라이드를 함유 한 폴리실록산 (H-silicone)의 수소와의 수소축합반응의해 가교와 발포를 동시에 일으켜 제조하였다. 이 러한 방법은 종래의 발포와 경화를 각각 실시한 공정보다 매우 편리한 방법이다. 이 실험에 사용 된 기 능성 실리콘수지들은 1.0 meq/g의 vinyl기를 가진 점도 20 Pa-s의 V-silicone과 0.4 meq/g의 수산기를 가진 점도 50 Pa-s의 OH-silicone 및 7.5 meq/g의 하이드라이드기를 함유한 점도 0.06 Pa.s.의 H-silicone으로 구성되어 있다. 본 연구에서는 실리콘의 종류 및 함량, 촉매, 충전제 등의 변화에 따른 실리콘수지 발포체의 구조 및 기계적 특성에 미치는 영향을 연구하였다.백금 촉매는 실리콘 수지에 대하여 0.5 wt%이면 충분하였다. 낮은 점도의 OH-silicone의 첨가는 초 기 발포 속도를 높이며 발포체 밀도는 감소시키지만, 낮은 점도의 V-silicone의 첨가는, 인장 강도뿐만 아니라 신율도 감소시킨다. SF-3 조건에서 얻은 실리콘수지 발포체의 밀도, 인장강도 및 신율을 각각 0.58 g/cm3, 3.51 kgf/cm2 및 176 %를 얻을 수 있었다. 본 발포 시스템에서의 알루미나 충전재 역시 실리콘수지 발포체의 기계적 특성을 향상시키는 중요한 역할을 하였다.

We report on the fabrication and characterization of a novel Cu2O/CuO heterojunction structure with CuO nanorods embedded in Cu2O thin film as an efficient photocathode for photoelectrochemical (PEC) solar water splitting. A CuO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method; then, a Cu2O thin film was electrodeposited onto the CuO nanorod array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated Cu2O/CuO heterojunction photocathode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/CuO photocathode was found to exhibit negligible dark current and high photocurrent density, e.g. −1.05 mA/cm2 at −0.6 V vs. Hg/HgCl2 in 1 mM Na2SO4 electrolyte, revealing the effective operation of the oxide heterostructure. The photocurrent conversion efficiency of the Cu2O/CuO photocathode was estimated to be 1.27% at −0.6 V vs. Hg/HgCl2. Moreover, the PEC current density versus time (J-T) profile measured at −0.5 V vs. Hg/HgCl2 on the Cu2O/CuO photocathode indicated a 3-fold increase in the photocurrent density compared to that of a simple Cu2O thin film photocathode. The improved PEC performance was attributed to a certain synergistic effect of the bilayer heterostructure on the light absorption and electron-hole recombination processes.

Membrane based water and wastewater treatment becomes more and more popular; however, membrane fouling is still a critical obstacle for its extensive use. Most of the membranes being used are polymeric and have limitations in physical, chemical, and thermal stability, even though various novel materials were introduced. In this study, metal membranes were fabricated to solve those weak points of polymeric membranes. We evaluated the physical properties of a metal membrane, such as pore size distribution, surface morphology, and water flux, and finally used the membrane for electrochemical oxidation of municipal wastewater with simultaneous hydrogen fuel generation. The metal membrane removed 50-70% of the feed organic matter by electrochemical oxidation; 10-30 % removal by electrochemical oxidation plus 40% by membrane rejection.

Hydrogen sulfide (H2S) emitted from various sources is a major odorous compound, and non-thermal plasma (NP) has emerged as a promising technique to eliminate H2S. This study was conducted to investigate lab-scale and pilot-scale NP reactors using corona discharge for the removal of H2S, and the effects of relative humidity, applied electrical power on reactor performance and ozone generation were determined. A gas stream containing H2S was injected to the lab-scale NP reactor, and the changes in H2S and ozone concentration were monitored. In the pilotscale NP experiment, the inlet concentration and flow rate were modified to determine the effect of relative humidity and applied power on the NP performance. In the lab-scale NP experiments, H2S removal was found to be the 1st-order reaction in the presence of ozone. On the other hand, when plasma reaction and ozone generation were initiated after H2S was introduced, the H2S oxidation followed the 0th-order kinetics. The ratio of indirect oxidation by ozone to the overall H2S removal was evaluated using two different experimental findings, indicating that approximately 70% of the overall H2S elimination was accounted for by the indirect oxidation. The pilotscale NP experiments showed that H2S introduced to the reactor was completely removed at low flow rates, and approximately 90% of H2S was eliminated at the gas flow rate of 15 m3/min. Furthermore, the elimination capacity of the pilot-scale NP was 3.4 g/m3·min for the removal of H2S at various inlet concentrations. Finally, the experimental results obtained from both the lab-scale and the pilot-scale reactor operations indicated that the H2S mass removal was proportional to the applied electrical power, and average H2S masses removed per unit electrical power were calculated to be 358 and 348 mg-H2S/kW in the lab-scale and the pilot-scale reactors, respectively. To optimize energy efficiency and prevent the generation of excessive ozone, an appropriate operating time of the NP reactor must be determined.

The hydrogen embrittlement of two austenitic high-manganese steels was investigated using tensile testing under high-pressure gaseous hydrogen. The test results were compared with those of different kinds of austenitic alloys containing Ni, Mn, and N in terms of stress and ductility. It was found that the ultimate tensile stress and ductility were more remarkably decreased under high-pressure gaseous hydrogen than under high-pressure gaseous argon, unlike the yield stress. In the specimens tested under high-pressure gaseous hydrogen, transgranular fractures were usually observed together with intergranular cracking near the fracture surface, whereas in those samples tested under high-pressure gaseous argon, ductile fractures mostly occurred. The austenitic high-manganese steels showed a relatively lower resistance to hydrogen embrittlement than did those with larger amounts of Ni because the formation of deformation twins or microbands in austenitic highmanganese steels probably promoted planar slip, which is associated with localized deformation due to gaseous hydrogen.