• Nano
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• 제13권10호
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• pp.1850124.1-1850124.12
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• 2018

$TiO_2$ films were deposited from oxygen/titanium tetraisopropoxide (TTIP) plasmas at low temperature by Helicon-PECVD at floating potential ($V_f$) or substrate self-bias of -50 V. The influence of titanium precursor partial pressure on the morphology, nanostructure and optical properties was investigated. Low titanium partial pressure ([TTIP] < 0.013 Pa) was applied by controlling the TTIP flow rate which is introduced by its own vapor pressure, whereas higher titanium partial pressure was formed through increasing the flow rate by using a carrier gas (CG). Then the precursor partial pressures [TTIP+CG] = 0:027 Pa and 0.093 Pa were obtained. At $V_f$, all the films exhibit a columnar structure, but the degree of inhomogeneity is decreased with the precursor partial pressure. Phase transformation from anatase ([TTIP] < 0.013 Pa) to amorphous ([TTIP+CG] = 0:093 Pa) has been evidenced since the $O^+_2$ ion to neutral flux ratio in the plasma was decreased and more carbon contained in the film. However, in the case of -50 V, the related growth rate for different precursor partial pressures is slightly (~15%) decreased. The columnar morphology at [TTIP] < 0.013 Pa has been changed into a granular structure, but still homogeneous columns are observed for [TTIP+CG] = 0:027 Pa and 0.093 Pa. Rutile phase has been generated at [TTIP] < 0:013 Pa. Ellipsometry measurements were performed on the films deposited at -50 V; results show that the precursor addition from low to high levels leads to a decrease in refractive index.

• Tuberculosis and Respiratory Diseases
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• 제41권5호
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• pp.475-483
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• 1994

연구배경 : N-acetylcysteine(ACE)은 임상에서는 객담용해제로 널리 쓰이고 있으나 시험관내 실험 또는 동물실험에서 ACE는 염증세포에서의 산소유리기를 감소시키고, 세포내 강력한 항산화기능을 갖고있는 glutathione(GSH)의 합성을 촉진한다고 알려졌다. 저자들은 만성폐쇄성폐질환 환자에게 통상 투여용량인 매일 600mg씩 1주일간 ACE를 투여했을때 말초혈액내 호중구의 superoxide 분비, chemotaxis 등의 기능에 변화가 오는지 또는 혈장의 GSH 농도가 증가되는지를 살펴보고 동시에 시험관내 실험으로 정상인의 호중구에 ACE를 가했을때 ACE의 농도에 따라 superoxide나 GSH의 양에 변화가 오는지를 관찰하였다. 방법 : ACE 투여 전, 후에 만성폐쇄성폐질환 환자의 말초혈액에서 호중구를 분리하여 PMA로 자극하거나 안했을때의 superoxide 분비를 분광광도계로, luminol-enhanced chemiluminescence를 luminometer로, 혈장의 GSH 농도를 분광광도계로 각각 측정하였다. 한편 정상인의 호중구를 분리하여 $10^{-2}-10^{-5}$ mole의 ACE와 혼합배양시의 superoxide, chemiluminescence 및 GSH를 각각 같은 방법으로 측정하였다. 결과 : ACE를 투여하기 전, 후의 말초혈액내 호중구의 superoxide 분비는 $1.97{\pm}1.75nM/1.4{\times}10^6\;cells/15min$, $2.75{\pm}2.14nM$이었고 PMA로 자극하였을때는 $67.52{\pm}13.41nM$, $67.99{\pm}13.54\;nM$로서 각각 유의한 차이가 없었다(p>0.05). 호중구의 chemiluminescence도 ACE 투여전, 후에 $2.64{\pm}2.29mV$, $2.91{\pm}3.58mV$이었고 PMA로 자극하였을때는 $40.76{\pm}30.09mV$, $37.33{\pm}30.03mV$로서 유의한 차이가 없었다(p>0.05). 호중구의 chemotaxis를 chemotactic index로 비교하였을때 ACE투여전, 후에 $55.71{\pm}16.34$, $59.68{\pm}11.57$이었고 혈장의 GSH는 $0.37{\pm}0.17nM/4{\times}10^5cells$, $0.39{\pm}0.18nM$로서 역시 유의한 차이가 없었다(p>0.05). 정상인의 호중구를 분리하여 $10^{-5}-10^{-2}$ mole의 ACE와 동시배양하며 PMA로 자극하였을때 superoxide는 ACE를 가하지 않은 대조군에서의 $56.54nM/1.4{\times}10^6\;cells/15min$에 비해 ACE의 $10^{-2}$ mole에서 37.0nM로서 유의하게 감소하였고 ACE의 농도에 따라 감소하는 양상을 보였다(r=-0.269, p<0.05). 호중구의 GSH 농도는 대조군의 $0.27nM/4{\times}10^5\;cells$에 비하여 ACE의 $10^{-3}$ mole에서 0.35nM, $10^{-2}$ mole 에서 1.15 nM로서 유의하게 증가하여 ACE의 농도에 따라 증가하였다(r=0.72, p<0.01). 결론 : ACE를 만성폐쇄성폐질환 환자에게 매일 600mg씩 1주일간 투여하였을때 말초혈액내 호중구의 superoxide 분비, chemotaxis에 영향을 주지 않았고 혈장의 glutathione 농도에도 변화가 없었다. 그러나 정상인의 호중구를 분리하여 ACE와 같이 배양한 실험에서 ACE는 농도에 비례하여 호중구의 superoxide 분비를 억제하였고 GSH를 증가시켰다. 이상으로 미루어 ACE는 염증세포에서의 superoxide 분비를 억제하고 GSH를 증가시킴으로서 oxidant-antioxidant 간의 불균형으로 야기되는 ARDS, 폐기종, 간질성폐질환등의 치료에 이용될수 있을것으로 생각되나 폐기종을 포함한 만성폐쇄성폐질환의 치료에 이용되기 위해서는 ACE의 혈중농도 또는 폐포세척액내의 농도를 충분히 증가시키는 방법이 강구되어야 할 것으로 사료된다.

• Journal of Nutrition and Health
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• 제36권6호
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• pp.570-576
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• 2003

스트레스에 의해서 생체는 에너지 대사를 증가시키며, 에너지 대사의 증가는 높은 반응성의 ROS를 생성한다. ROS는 높은 반응성으로 인해 지질, 단백질 등을 과산화시켜 원래의 활성을 잃게 한다. 이런 ROS에 대해서 높은 소거능을 지닌 vitamin I의 투여는 스트레스로 인한 생체내 산화적 손상을 억제할 수 있을 것으로 생각된다. 이런 효능을 확인하기 위하여 실험용 흰 쥐에게 4주간의 noise 및 고정화 스트레스를 가한 결과, 스트레스를 가함으로서 체중증가량을 감소시켰으며, 스트레스 지표 물질인 5-HIAA와 혈청내 유리 지방산의 증가 및 뇌조직의 산화적 손상이 증가되어 정상적으로 스트레스가 가해졌음을 확인할 수 있었다. 또한, vitamin E 투여군의 경우 혈청내에서의 vitamin E 농도가 유의적으로 증가하여 정상적인 vitamin E의 투여도 이루어졌음을 확인하였다. Vitamin E의 투여는 스트레스로 인한 체중 증가량의 감소를 억제하였으며, 또한 뇌조직의 단백질 및 지질의 산화적 손상을 억제하는 효능을 보였으며, SOD의 활성 또한 증가시키는 효능을 나타냈다. 따라서, vitamin E 투여는 스트레스로 인하여 발생하는 뇌조직의 산화적 손상을 억제함으로서 스트레스에 대한 방어 효능이 일부 있는 것으로 생각된다.

• 동의생리병리학회지
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• 제20권6호
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• pp.1485-1496
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• 2006

Various kinds of related parameters on hypertension such as anti-oxygen effect, ACE, weight of body, hwart and kidney, blood pressure, heartbeat rates, contents of aldosterone, catecholamine, change rates, of plasma constituents, uric acid, BUN, creatinine were determined to verify the effects on hypertension by Kamisamul-tang (KSMT). And the results are concluded as follows. KSMT did not show any cytotoxicity at the range of concentration (1-250 ${\mu}g/m{\ell}$) on the human fibroblast cell (hFCs). KSMT decreased the production of reactive oxygen species (ROS) and DPPH generation depending on the concentration. KSMT significantly inhibited angiotensin converting enzyme(ACE) activity depending on the concentration compared with control. KSMT maintained body weight of body, heat and kidney nearly normal group in hypertensive rat induced by DOCA-salt. KSMT significantly blood pressure and heart beat rate compared with control in hypertensive rat induced by DOCA-salt. KSMT significantly decreased aldosterone, dopamine, norepineph- rine, epinephrine compared with control in hypertensive rat induced by DOCA-salt. KSMT significantly decreased the level of potassium and cloride compared with control wheareas increased that of calcium significantly in hypertensive rat induced by DOCA-salt. KSMT significantly decreased the level of uric acid and BUN compared with control in hypertensive rat induced by DOCA-salt. It is verified experimentally tat Kamisamultang(KMST) which has been used broadly as a clinical therapeutics in oriental medicine is effective for anti-hypertension mechanism. And it could be applied to develope the reliable prescriptions for anti-hypertension in the future.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.442-442
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• 2008

Hydrogen was produced by water plasma excited in very high frequency inductively coupled tube reactor. Mass spectrometry was used to monitor gas phase species at various process conditions. Water dissociation rate depend on the process parameters such as ICP power, flow-rate and pressure. Water dissociation percent in ICP reactor decrease with increase of chamber pressure and $H_2O$ flow rate, while increase with increase of ICP power. In our experimental range, maximum water dissociation rate was 65.5% at the process conditions of 265 mTorr, 68 sccm, and 400 Watt. The effect of $CH_4$ addition to a water plasma on the hydrogen production has been studied in a VHF ICP reactor. With the addition of $CH_4$ gas, $H_2$ production increases to 12% until the $CH_4$ flow rate increases up to 15 sccm. But, with the flow rate of $CH_4$ more than 20 sccm, chamber wall was deposited with carbon film because of deficiency of oxygen in gas phase, hydrogen production rate decreased. The main roles of $CH_4$ gas are to reacts with O forming CO, CHO and $CO_2$ and releasing additional $H_2$ and furthermore to prevent reverse reaction for forming $H_2O$ from $H_2$ and $O_2$. But, $CH_4$ addition has negative effects such as cost increase and $CO_x$ emission, therefore process optimization is required.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.302-305
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• 1995

ITO(indium tin oxide) that is both conductive in electricity and transparent to the visible ray is called transparent conducting thin film. Nowaday, according to the development of flat panel display such as LCD(Liquid Crystal display, EL(electolumine- scence display), PDP(plasma display panel), ECD(electrocromic display), the higher quality in the low temperature process has been asked to reduce the production cost and to have a good uniformity on a large substrate. In this study, we prepared indium tin oxide(ITO) by a cylindrical DC magnetron sputtering with Indium-tin (9:1) alloy target instead of indium-tin oxide target. To reduce the defact in ITO, the effect on ITO by varing the magnetic field intensity and the applied voltage ares studied. the resistivity of the film deposited in oxygen partial pressure of 5% and substrate temperature of 140$^{\circ}C$. is 1.6${\times}$10$\^$-1/$\Omega$$.$cm with 85% optical transmission in viaible ray.

• 한국자동차공학회논문집
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• 제8권5호
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• pp.67-77
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• 2000

Investigated was the effect of propene(C3H6) on the NO-NO2 conversion in dry exhaust gases from lean burn engine using a pulsed corona discharge. A kinetic model was developed to characterize the plasma chemistry in simulated exhausts containing propene. The model uses ELENDIF program to solve Boltzmann equation for electron energy distribution function, and CHEMKIN-II program to solve stiff ODE(ordinary differential equation) problems for species concentrations. The corona discharge energy per pulse and the time-space averaged E/N were obtained by fitting the model to experimental data. The model calculation shows good agreement for NO and NO2 concentrations with the experimental data, and predicts the formation of byproducts such as CH2O, CH3HCO, CO AND CH3NO2 Propene enhances the NOx conversion enormously at lower energy density and the NOx conversion increases with the increase of initial propene and oxygen concentration, and temperature.

• Clinical and Experimental Reproductive Medicine
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• 제48권4호
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• pp.316-321
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• 2021

Objective: Amino acids can protect sperm structure in cryopreservation due to their antioxidant properties. Therefore, the present study aimed to investigate the protective effect of L-carnitine (LC) and N-acetyl cysteine (NAC) on motility parameters, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), DNA damage, and human sperm intracellular reactive oxygen species (ROS) during vitrification. Methods: Twenty normal human sperm samples were examined. Each sample was divided into six equal groups: LC (1 and 10 mM), NAC (5 and 10 mM), and cryopreserved and fresh control groups. Results: The groups treated with LC and NAC showed favorable findings in terms of motility parameters, DNA damage, and MMP. Significantly higher levels of intracellular ROS were observed in all cryopreserved groups than in the fresh group (p≤0.05). The presence of LC and NAC at both concentrations caused an increase in PMI, MMP, and progressive motility parameters, as well as a significant reduction in intracellular ROS compared to the control group (p≤0.05). The concentrations of the amino acids did not show any significant effect. Conclusion: LC and NAC are promising as potential additives in sperm cryopreservation.

• Clinical and Experimental Reproductive Medicine
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• 제49권2호
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• pp.110-116
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• 2022

Objective: Sperm vitrification leads to the production of reactive oxygen species (ROS) that can damage the functional parameters of sperm. The present study aimed to investigate the antioxidant effect of Nigella sativa extract on motility, plasma membrane function, mitochondrial membrane potential (MMP), DNA damage, and intracellular ROS production. Methods: A total of 20 sperm samples were used. Samples were divided into six experimental groups, including groups with aqueous extract from N. sativa seeds at concentrations of 1% to 6%, a cryopreserved control group, and a fresh control group. Results: Statistical analysis showed significantly higher total sperm motility at concentrations of 3% to 6% than in the vitrified semen control group. Additionally, progressive motility and all motion characteristics at all concentrations were significantly higher than in the vitrified semen control group. The presence of N. sativa seed extract also improved the quality of the sperm parameters assayed in all experimental groups (1%-6%; intracellular ROS production, DNA damage, MMP, and sperm membrane function) compared to the control group. Conclusion: Higher concentrations of N. sativa led to improvements in all sperm parameters and sperm quality. These findings indicate that N. sativa seed extract is effective for improving the quality of sperm after vitrification.

• 공업화학
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• 제27권1호
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• pp.92-100
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• 2016

플라즈마와 선택적 촉매환원법이 결합된 복합공정을 이용하여 저온에서의 질소산화물($NO_x$) 저감에 대해 조사하였다. 플라즈마와 촉매가 직접 상호작용을 할 수 있도록 촉매 충진층에서 플라즈마가 생성되도록 하였다. 반응온도, 촉매의 형태, 환원제인 n-헵테인의 농도, 산소함량, 수분함량 및 에너지밀도의 변화가 $NO_x$ 전환효율에 미치는 영향에 대해 살펴보았다. 반응온도 $250^{\circ}C$, 에너지밀도 $42J\;L^{-1}$ 조건에서, 복합공정의 $NO_x$ 전환효율은 선형의 Ag 촉매($Ag\;(nanowire)/{\gamma}-Al_2O_3$)와 구형의 Ag 촉매($Ag\;(sphere)/{\gamma}-Al_2O_3$)를 사용한 경우에 각각 83%와 69%로 나타났으며, 플라즈마를 결합하지 않았을 때는 같은 조건에서 선형의 Ag 촉매를 사용해도 약 30%의 낮은 $NO_x$ 전환효율을 보였다. 플라즈마에 의한 촉매의 성능 향상은 플라즈마의 산화작용에 의해 NO가 반응성이 우수한 $NO_2$로 전환되고, n-헵테인이 부분 산화되어 환원력이 우수한 중간생성물을 발생시켜 선택적 환원반응을 촉진시켰기 때문이다. 에너지밀도의 증가에 따라 $NO_x$ 전환효율이 증가하는 경향을 보였으며, n-헵테인의 농도를 증가시킬수록 $NO_x$ 전환효율이 높아졌으나 $C_1/NO_x$ 비가 5 이상이 되면 더 이상 $NO_x$ 전환효율이 증가되지는 않았다. 수분은 $NO_x$와 경쟁흡착 관계에 있으므로 $NO_x$ 전환효율에 큰 영향을 미치며, 수분함량이 높을 경우 $NO_x$ 전환효율이 감소하는 현상을 보였다. 산소농도가 3~15%로 증가할수록 $NO_2$ 및 부분 산화 탄화수소의 생성 촉진으로 $NO_x$ 전환효율이 향상되었으며, 특히 낮은 에너지 밀도에서 $NO_x$ 전환효율 차이가 큰 것으로 나타났다.