• 전기화학회지
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• 제8권2호
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• pp.82-87
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• 2005

고전압 용 양극산화물 $LiNi_{0.5}Mn_{1.5}O_4$는 고온에서 합성 시, 입자 내에 산소결함에 의한 불순물상을 만들게 된다. 불순물상은 불완전한 스피넬 구조를 형성하며 리튬이온의 삽입$\cdot$탈리를 방해하여 전극의 성능을 감소시킨다. 본 연구에서는 고온 열처리 시 생성되는 이러한 불순물상의 거동을 파악하기 위해 크롬을 치환한 $LiNi_{0.5-x}Mn_{1.5}Cr_xO_4(0{\leq}x{\leq}0.05)$를 졸$\cdot$겔법을 이용하여 합성하여 고온 열분석을 실시하였다. 열분석 결과 크롬이 치환되지 않은 양극활물질은 산소결함에 의한 $2\%$의 무게 감소를 보였으나, 크롬이 치환된 경우 무게 감소분이 줄어들어 불순물 생성이 억제됨을 알 수 있었다. XRD 분석에서도 크롬이 치환된 경우 불순물 상이 억제됨을 나타내었으며 불순물상의 감소로 인해 크롬을 첨가한 양극활물질 $LiNi_{0.5-x}Mn_{1.5}Cr_xO_4$를 사용한 경우 충·방전 실험 시 가역 용량과 싸이클 안정성이 향상됨을 볼 수 있었다.

• 한국분말재료학회지
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• 제13권6호
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• pp.401-407
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• 2006

Effects of oxygen deficiency on the room temperature ferromagnetism in Fe-doped reduced $TiO_2$ have been investigated by comparing the air-annealed $Ti_{0.97}Fe_{0.03}O_2$ compound with secondly post-annealed one in vacuum ambience. The air-annealed sample showed a paramagnetic behavior at room temperature. However, when the sample was further annealed in vacuum, a strongly enhanced ferromagnetic behavior was observed at same temperature. $M{\"{o}}ssbauer$ spectra of air-annealed sample at 295K showed a single doublet of $Fe^{3+}$, suggesting that the Fe ions are paramagnetic. On the other hand, the absorption spectra after vacuum-annealing exhibited two doublets, in which one is the same component with air-annealed sample and the other is new doublet corresponding to $Fe^{2+}$ state. This result suggests that the occurrence of ferromagnetism in reduced sample may be interpreted as the contribution of unquenched orbital moment of $Fe^{2+}$ ions.

• 한국안광학회지
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• 제8권2호
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• pp.1-11
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• 2003

확산에 관한 Fick 법칙 및 연속법칙을 사용하여 액체(눈물)-콘택트 렌즈-눈물 층을 통하여 각막으로 유입되는 산소 flux 및 각막 표면의 산소 분압을 계산할 수 있는 일련(一連)의 방정식을 세우고 이들 식에 의거하여 피팅에 따른 눈물 층의 두께, 콘택트 렌즈의 Dk 및 두께 변화가 각막에 유입되는 산소 flux에 어떠한 영향을 미치는가를 예측하였다. 본 모델을 사용하여 적절한 피팅 조건에 부합하고 또한 각막 표면의 산소 분압이 보장되는 콘택트 렌즈의 Dk 및 두께를 결정할 수 있다. 대단히 높은 Dk값을 지닌 콘택트 렌즈라도 너무 flat 또는 tight하게 피팅된 경우 콘택트 렌즈의 주변부와 각막 사이 눈물 층의 간격이 커짐으로 인하여 각막 주변부에 도달하는 산소 flux 및 각막 주변부 표면의 산소 분압이 급격히 감소하게 될 수 있다.

• 한국잡초학회지
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• 제17권4호
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• pp.431-438
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• 1997

유해(有害)한 활성산소종(活性酸素種)들을 생성하는 환경 stress에 대한 식물의 적응과정(適應過程)을 파악하기 위한 일환으로서, 호박을 식물재료로 공시하고 Mg이 결핍(缺乏)된 영양액(營養液)에서 재배하여 산화적(酸化的) stress 조건을 부여하였을 때, 나타나는 과산화(過酸化)의 피해정도와 항산화효소(抗酸化酵素)들의 활성변동(活性變動)을 조사하였다. 충분한 양의 Mg이 공급된 영양액에서 재배된 호박의 잎에서는 Mg, 엽록소(葉綠素), 단백질(蛋白質) 함량(含量) 및 항산화효소(抗酸化酵素)들의 활성(活性)이 다소 증가 되었거나 거의 일정하게 유지되었다. 그러나 Mg이 결핍(缺乏)된 영양액(營養液)에서 재배된 호박의 잎에서는 Mg, 엽록소(葉綠素), 단백질(蛋白質) 함량(含量)은 현저히 감소된 반면, 항산화효소(抗酸化酵素)인 AP, GR 및 SOD의 활성(活性)이 크게 증가되었다. 본 연구에서 얻어진 결과들은 식물에서 Mg의 결핍(缺乏)으로 이하여 해로운 활성산소종(活性酸素種)이 생성되며 동시에 이들 활성산소종(活性酸素種)의 유해(有害)한 작용을 소거(消去)하기 위한 항산화효소(抗酸化酵素)의 활성(活性)도 유도(誘導)되는 것을 시사한다.

• 마이크로전자및패키징학회지
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• 제19권2호
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• pp.73-78
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• 2012

The chemical, electrical, and optical properties of ZnO and Al-doped ZnO films after high temperature annealing were studied. The resistivity increased significantly after annealing at $600^{\circ}C$ under $10^{-10}$ Torr atmosphere. The mechanism of the resistivity change was explored using photoemission spectroscopy and photoluminescence spectrometer. The results indicated that the amount of oxygen deficient region O-Zn bonds decreased and oxygen vacancy was decreased after the high temperature vacuum annealing. The increase in the resistivity of ZnO and Al-doped ZnO films was resulted from the decrease in carrier concentration due to a decrease in the amount of oxygen deficiency.

• Bulletin of the Korean Chemical Society
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• 제12권1호
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• pp.17-22
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• 1991

Fourier transform infrared spectroscopy has been applied to the characterization of titania supported molybdena. The equilibrium adsorption method seemed to produce molybdena species homogeneously dispersed on the support. Even under an oxidizing environment, molybdena species appeared to be able to possess coordinatively unsaturated $Mo^{5+}$ ions owing to the natures of TiO$_2$, i.e. oxygen deficiency and permeability toward oxygen diffusion. At the initial stage of reduction, the terminal double bond oxygen ( Mo=O ) seemed to be removed, generating presumably $Mo^{4+}$. The carbonyl bands at 2198 and 2190 $cm^{-1}$ observed after CO exposure were attributed to the $Mo^{5+}{\cdots}CO\;and\;Mo^{4+}\;{\cdots}CO$ complexes, respectively, while the band pair at 2136 and 2076 $cm^{-1}$ to $Mo^{4+}(CO)_2$.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.403-406
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• 2012

Effect of thickness on ZnO properties including the compositional ratio and crystallinity has been systematically investigated using a variety of characterization tools of x-ray diffraction, field emission scanning electron microscopy, x-ray fluorescence and x-ray photoelectron spectroscopy. Interestingly, it was observed that ZnO films below 80 nm in thickness were in oxygen deficiency, while the oxygen ratio was increased in the films above the thickness, although the compositional ratio of ZnO film was not linearly varied with increasing film thickness. Also, ZnO crystallinity, which is characterized by (002) diffraction pattern, was clearly improved with increasing film thickness. The properties of ZnO film with different sputtering time and the nature of direct current reactive sputtering process were discussed in terms of compositional ratio, especially oxygen ratio in ZnO film.

• 한국세라믹학회지
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• 제47권2호
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• pp.99-105
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• 2010

The electrical transport properties of mayenite ($Ca_{12}Al_{14}O_{33}$ or $12CaO{\cdot}7Al_2O_3$; mostly abbreviated as $C_{12}A_7$) can be controlled in a wide range by varying the oxygen deficiency: At high temperatures mayenite becomes either an oxygen solid electrolyte, a mixed ionic/electronic conductor or an inorganic electride with metal-like properties upon chemical reduction (removing oxygen). The underlying defect chemistry can be understood on the basis of a relatively simple model-despite the complex cage structure: A point defect model based on the assumption that the framework $[Ca_{12}Al_{14}O_{32}]^{2+}$ acts as a pseudo-donor describes well the high temperature transport properties. It accounts for the observed conductivity plateau at higher oxygen activities and also describes the experimentally observed oxygen activity dependence of the electronic conductivity with -1/4 slope at temperatures between 800 and $1000^{\circ}C$. Doping effects in mayenite are still not well explored, and we review briefly the existing data on doping by different elements. Hydration of mayenite plays a crucial role, as Mayenite is hygroscopic, which may be a major obstacle for technical applications.

• 한국해양학회지
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• 제22권4호
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• pp.246-256
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• 1987

鎭海灣一帶 海域에서 夏季 底層 溶存酸素표의 缺乏현상과 底棲生物量과의 關 係를 밝히기 위하여 1983年 9月 底棲生物의 生態學的 調査를 실시하였다. 일반적으 로 底層의 溶存酸素量이 낮은 地域에서는 底棲生物量과 個體數가 현저히 감소하였 다. 底層의 溶存酸素量이 2.0$m\ell$/$\ell$이하 그리고 酸素飽和度 40% 이하인 貧酸素 海域 이 전체 調査海域 497km$^{2}$의 54%를 차지하는 266km$^{2}$에 걸쳐 광범위하 게 발달하고 있음이 밝혀졌으며, 특히 馬山灣, 行岩灣, 古縣域灣, 加助島 西側의 元 門灣, 鎭海灣 中央部등이 영향을 받는 것으로 나타났다.

• IMMUNE NETWORK
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• 제11권3호
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• pp.169-174
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• 2011

Background: NADPH oxidase (NOX) modulates cell proliferation, differentiation and immune response through generation of reactive oxygen species. Particularly, NOX2 is recently reported to be important for regulating Treg cell differentiation of CD4+ T cells. Methods: We employed ovalbumin-induced airway inflammation in wild-type and NOX2-deficient mice and analyzed tissue histopathology and cytokine profiles. Results: We investigated whether NOX2-deficiency affects T cell-mediated airway inflammation. Ovalbumin injection which activates T cell-mediated allergic response increased airway inflammation in wild-type mice, as evidenced by increased immune cell infiltration, allergic cytokine expression, and goblet cell hyperplasia in the lung. Interestingly, NOX2 knockout (KO) mice were more susceptible to allergen-induced lung inflammation compared to wild-type mice. Immune cells including neutrophils, lymphocytes, macrophages, and eosinophils were drastically infiltrated into the lung of NOX2 KO mice and mucus secretion was substantially increased in deficiency of NOX2. Furthermore, inflammatory allergic cytokines and eotaxin were significantly elevated in NOX2 KO mice, in accordance with enhanced generation of inflammatory cytokines interleukin-17 and interferon-${\gamma}$ by CD4+ T cells. Conclusion: These results indicate that NOX2 deficiency favorably produces inflammatory cytokines by T cells and thus increases the susceptibility to severe airway inflammation.