• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.311-324
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• 2018

Herein,the Neodymium ion ($Nd^{3+}$) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

• Current Photovoltaic Research
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• 제10권1호
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• pp.16-22
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• 2022

The long-term stability of PSCs against visual and UV light, moisture, electrical bias and high temperature is an important issue for commercialization. In particular, since the operation temperature of solar cell can rise above 85℃, a study on thermal stability is required. In this study, the cause of thermal-induced degradation of PSCs was investigated using the SCAPS-1D simulation tool. First, PSCs of TiO₂/CH₃NH₃PbI₃/Spiro-OMeTAD/Au structure were exposed to a constant temperature of 85℃ to observe changes in conversion efficiency and quantum efficiency. Because the EQE reduction above 500 nm was remarkable, we simulated PSCs performance as a function of lifetime, doping density of perovskite and spiro-OMeTAD. Consequently, the main cause of thermal-induced degradation is considered to be the change in the perovskite doping concentration and lifetime due to ion migration of perovskite.

• 한국환경농학회지
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• 제6권2호
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• pp.73-76
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• 1987

들깨 수원(水原) 8호(號)(Perilla frutescens Suwon No. 8)에 $SO_2$를 접촉(接觸)시켰을 때 일어나는 광합성색소(光合成色素)의 변화(變化)에 대(對)한 $SO_2$농도(濃度), 접촉시간(接觸時間), 광,(光) 활성산소(活性酸素)와 무기(無機) $SO_3\;^{-2}$의 영향(影響)을 관찰분석(觀察分析)한 결과(結果)는 다음과 같다. 1. $SO_2$농도(濃度)가 높아지고 접촉시간(接觸時間)이 길어질수록 피해(被害)가 심해저 엽록소(葉綠素)의 파괴(破壞)도 많았다. 2. $SO_2$ gas접촉에 의하여 엽록소(葉綠素)a가 엽록소(葉綠素)b 보다 쉽게 분해(分解)되었으며 또한 carotinoid도 엽록소(葉綠素)b보다 쉽게 분해(分解)되는 것으로 추정된다. 3. 들깨의 $SO_2$에 의한 엽록소파괴(葉綠素破壞)는 $SO_2$에 의한 직접적(直接的)인 영향(影響)으로 파악되었고, 이 때에 광(光)이 필수적(必須的)으로 필요하며, 물이 광분해(光分解)로 생성(生成)되는 $O_2^-$가 $SO_2$와 함께 엽록소분해(葉綠素分解)에 중심적(中心的)인 역할을 하는 물질이었다.

• 공업화학
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• 제29권3호
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• pp.298-302
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• 2018

질소가 도핑된 이산화티타늄의 광촉매 특성을 알아보았다. 질소가 도핑된 이산화티타늄에 대하여 자외선 및 가시광선 분위기에서 메틸렌블루 광촉매 분해를 수행하였다. XPS 분석을 통해 제조한 $TiO_2$에서 질소(N)가 산소(O)와 치환되었음을 확인하였다. UV-Vis DRS 분석 결과 질소가 도핑된 무정형 $TiO_2$ 시료에서는 가시광선을 거의 흡수하지 않고 자외선을 흡수하는 반면 무정형/anatase 혼재 $TiO_2$ 시료의 경우 가시광선 흡수가 상당히 증가하였다. 질소가 도핑된 anatase $TiO_2$ 시료는 자외선 및 가시광선 조사에서 메틸렌블루 광분해 반응이 나타났다. 그러나 가시광선 조사에서 분해율은 자외선 조사의 분해율보다 낮았다. 무정형/anatase 혼재 $TiO_2$ 시료의 경우 자외선과 가시광선 조사에서 anatase $TiO_2$ 시료의 분해율보다 높았다. 이러한 결과는 anatase $TiO_2$ 시료에 비해 3배 정도 큰 무정형/anatase 혼재 $TiO_2$ 시료의 높은 표면적이 질소 도핑된 작은 anatase 입자와 관련이 있음을 보여준다.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2442-2451
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• 2018

Novel highly active visible-light photocatalysts in the form of zinc bismuth oxide ($ZnBi_2O_4$) and graphite hybrid composites were prepared by coupling via a co-precipitation method followed by calcination at $450^{\circ}C$. The asprepared $ZnBi_2O_4$-graphite hybrid composites were tested for the degradation of rhodamine B (RhB) solutions under visible-light irradiation. The existence of strong electronic coupling between the two components within the $ZnBi_2O_4$-graphite heterostructure suppressed the photogenerated recombination of electrons and holes to a remarkable extent. The prepared composite exhibited excellent photocatalytic activity, leading to more than 93% of RhB degradation at an initial concentration of $50mg{\cdot}L^{-1}$ with 1.0 g catalyst per liter in 150 min. The excellent visible-light photocatalytic mineralization of $ZnBi_2O_4-1.0graphite$ in comparison with pristine $ZnBi_2O_4$ could be attributed to synergetic effects, charge transfer between $ZnBi_2O_4$ and graphite, and the separation efficiency of the photogenerated electrons and holes. The photo-induced $h^+$ and the superoxide anion were the major active species responsible for the photodegradation process. The results demonstrate the feasibility of $ZnBi_2O_4-1.0graphite$ as a potential heterogeneous photocatalyst for environmental remediation.

• Molecules and Cells
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• 제21권2호
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• pp.218-223
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• 2006

The effect of poly(ADP-ribosyl)ation on the stability of p53 in SK-HEP1 cells treated with UV light was examined. Intracellular levels of p53 increased in cells treated with a low dose of UV light ($20J/m^2$), whereas they increased but then declined after a higher dose of UV ($100J/m^2$). Intracellular levels of p53 in the UV treated SK-HEP1 cells were dependent on the UV dose. Use of proteasome inhibitors revealed that p53 is degraded by proteasomal proteolysis after high doses of UV light. We present evidence that, at low doses, poly(ADP-ribose)polymerase (PARP) poly(ADP-ribosyl) ates p53 and protects it from proteasomal degradation before caspase-3 is activated, whereas at high doses the cells undergo UV induced apoptosis and PARP is cleaved by caspase-3 before it can protect p53 from degradation. Destabilization of p53 by cleavage of PARP may be important in cell fate decision favoring apoptosis.

• Journal of Ginseng Research
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• 제45권2호
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• pp.287-294
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• 2021

Background: Ginsenoside Rb1 (G-Rb1), one of the major active compounds in Panax ginseng, has already been shown to reduce inflammation in various diseases. Osteoarthritis (OA) has traditionally been considered a degenerative disease with degradation of joint articular cartilage. However, recent studies have shown the association of inflammation with OA. In the present study, we investigated whether Rb1 had an antiinflammatory effect on monoiodoacetate (MIA)-induced OA in ovariectomized rats as a model of postmenopausal arthritis. Methods: G-Rb1 at a dosage of 3 and 10 ㎍/kg body weight was administered every 3 days intraarticularly for a period of 4 weeks to observe antiarthritic effects. Diclofenac (10 mg/kg) served as a positive control. Results: The administration of Rb1 significantly ameliorated OA inflammatory symptoms and reduced serum levels of inflammatory cytokines. Furthermore, G-Rb1 administration considerably enhanced the expression of bone morphogenetic protein-2 and collagen 2A and reduced the levels of matrix metalloproteinase-13 genes, indicating a chondroprotective effect of G-Rb1. G-Rb1 also significantly reduced the expression of several inflammatory cytokines/chemokines (interferon gamma (IFN-γ), monocyte chemoattractant protein-1 (MCP-1)/CCL-2, interleukin [IL]-1β, and IL-6). Histological analysis demonstrated that G-Rb1 significantly attenuated the pathological changes in MIA-induced OA in ovariectomized rats. Safranin O and toluidine blue staining further demonstrated that G-Rb1 effectively prevented the degradation of cartilage and glycosaminoglycans, respectively. Conclusion: Overall, our results suggest that G-Rb1 exerts cartilage protective effect on MIA-induced ovariectomized OA rats, by inhibiting inflammatory mediators such as IL-6, IL-1β, MCP-1/CCL-2, cyclooxygenase-2 (COX-2), and prostaglandin E₂ (PGE2). These results shed a light on possible therapeutic application of G-Rb1 in OA.

• 한국환경농학회지
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• 제11권3호
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• pp.261-268
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• 1992

식물 세포의 미토콘드리아와 엽록체는 광 증감제로 작용할 가능성이 있는 여러 가지 색소들을 함유하고 있다. 이들 색소들은 대부분이 막에 결합되어있으며 청색광 영역에서 강한 흡수대를 가지므로 청색광하에서 노출된 이들 소기관에서는 활성산소가 발생되어 막의 구조적, 기능적 피해를 유발하는 요인이 된다. 활성산소의 광발생에 따른 막구조의 변화는 일차적으로 막지질 지방산성분의 산화적 파괴에 기인할 것이다. 본 연구에서는 식물이 고광도의 가시광선(특히 청색광선)하에서 일어나는 막지질 지방산의 산화적 파괴에 지방산 대신 상대적으로 둔감한 포화 지방산의 조성비를 높일 것이라고 가정하고, 이를 뒷받침할만한 실험결과를 얻었다. 즉, 광질이 서로 다른 가시광선 처리조건하에서 생장중인 식물 및 그 소기관들을 대상으로 막지질의 과산화, 지방산조성 및 불포화도, 막결합 단백질의 활성 등을 측정하고 이를 제시하였다.

• 제어로봇시스템학회논문지
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• 제16권6호
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• pp.586-591
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• 2010

VLC (Visible Light Communication) is a wireless communication method using light that is visible to the human eye. It has a major advantage that it causes no interference to RF-based devices. This makes wireless communication possible in RF hazardous areas such as nuclear facilities. In order to apply VLC communication in harsh environment of nuclear power plant, the high luminance LEDs, which are key components of the VLC communication, have been gamma-ray irradiated at the dose rate of 4kGy/h during 72 hours up to a total dose of 288 kGy. The radiation induced color-center was formed in the LED housing cap made of transparent plastic or acryl material. The beam degradations of high luminance LEDs by high dose-rate gammaray irradiation are analyzed using color CCD image processing technology.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.167-171
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• 2002

We have investigated the optical properties of Te-doped ZnSSe:Te epitaxial layers grown on (100) GaAs substrates by molecular beam epitaxy. The Te-doped ternary specimen shows strong blue or green emission (at 300k) which is assigned to Te$_{1}$ or Te$_{n}$( n$\geq$2) cluster bound exciton. Bright green and blue light-emitting diodes (LEDs) have been developed using ZnSSe:Te system as an active layer. The green LEDs exhibit a fairly long device lifetime (>2000 h) when operated at 3 A/cm$^{2}$ under CW condition at room temperature. It is confirmed that the Te-doping induced "crystal-hardening effect" plays a significant role in both efficient and strong suppression of the optical device degradation.gradation.