• Journal of Plant Biotechnology
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• 제37권4호
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• pp.529-538
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• 2010

Proline accumulates in plants under environmental stresses including saline stress and alkaline stress. Here, we investigated the responses to two different stresses, saline stress (200 mM NaCl) and alkaline stress (100 mM $Na_2CO_3$) in two Leymus chinensis (Trin.) genotypes, LcWT07 and LcJS0107, and effects of exogenous proline on the activities of antioxidant enzymes. Both saline stress and alkaline stress significantly induced the accumulation of proline in leaves of the two genotypes after 96 h, and alkaline stress caused a transient and significant increase in LcJS0107 plants at 6 h. A reduction in the activities of catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11), but not in the activity of superoxide dismutase (SOD, EC 1.15.1.1), was detected in plants exposed to saline and alkaline stresses. Remarkable decrease in relative water contents (RWC) was found in 144 h stressed plants. However, lipid peroxidation estimated by malonyldialdehyde (MDA) content in leaves remained relatively stable. With the addition of exogenous proline, it did not cause changes of proline levels in two genotypes, but combined with saline or alkaline stress, the exogenous application of proline significantly induced proline accumulation after even short treatment periods. Combined with salt stress, the exogenous application also increased the activities of CAT and APX. These results indicated that exogenous proline not only increases proline levels in vivo as a osmotic adjustment under stress, but mitigates the detrimental effects of saline and alkaline stresses by increasing the activities of antioxidant enzymes.

• 대한치과교정학회지
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• 제24권1호
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• pp.105-114
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process of bone formation and bone resolution. To find out the changes occuring in the cell itself, mechanical stress was applied to the cell populations involved in the bone metabolism. Bone tissue cell populations were isolated from fetal rat calvaria and divided into OC and OB groups. Following results were obtained from measuring the changes in acid & alkaline phosphatease activity, cyclic AMP and $PGE_2$ production in time lapse after the application of mechanical stress. 1. In case of the marker enzyme of specific bone tissue cell, acid phosphatase activity was high in OC group and alkaline phosphatase activity was high in OB group. 2. After the mechanical stress was applied, acid phosphatase activity was decreased in both OC and OB groups and alkaline phosphatase activity was increase in OB group. 3. When the mechanical stress was applied for 15, 30 and 60 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased. 4. When the mechanical stress was applied for 20 and 40 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased.

• 한국초지조사료학회지
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• 제41권3호
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• pp.210-216
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• 2021

Pollution of agricultural soil by alkaline salts, such as Na₂CO₃, is a critical and long-lasting problem in cultivable land. The aim of the study was to examine the putative role of citric acid (CA) in alleviating Na₂CO₃-stress in alfalfa. In this study, Na₂CO₃ significantly induced leaf chlorosis, inhibited plant growth and photosynthesis related parameters, increased hydrogen peroxide (H₂O₂) and reduced major antioxidant enzymes (SOD, CAD, APX) in alfalfa. However, the presence of CA these negative effects of Na₂CO₃-stress largely recovered. Interestingly, expression of antioxidant and ion transporter genes (Fe-SOD, CAT, APX, DHAR and NHX1) involved in Reactive oxygen species (ROS) homeostasis and oxidative stress tolerance in alfalfa. These findings suggest that CA-mediated Na₂CO₃ stress alleviation is an ecofriendly approach that would be useful to local farmer for alfalfa and other forage crop cultivation in alkaline soils.

• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.43-48
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• 2011

탄소 기지상에 니켈도금을 하여 다공성 MCFC의 전극으로 사용하기 위하여 탄소 기지위에 산성용액과 염기성용액을 이용하여 무전해 니켈도금을 하였다. 알칼리 용액에서의 도금속도가 산성용액에서의 도금속도보다 빨랐으며 두가지 용액에서 pH가 증가함에 따라 도금속도가 증가하였다. 산성용액에서의 잔류응력은 압축응력을 보였으며 알칼리용액에서는 높은 인장응력을 보였으며 높은 잔류응력으로 인하여 pH 11 이상에서는 표면균열이 발생하였다. Thiourea를 첨가하였을 경우 0.5 ppm까지의 저농도에서 도금속도가 증가하다가 이후 감소하였으며 1.5 ppm 이상에서 두가지 용액에서 모두 도금이 더 이상 진행되지 않았다. Succine 산을 첨가한 경우 5 g/L까지 속도가 증가하다가 감소하여 일정한 값을 유지하였다.

• 대한치과교정학회지
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• 제26권3호
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• pp.291-299
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• 1996

교정력은 치아이동과 악골성장을 조절하는 기계적 자극이며, 이러한 기계적 자극에 골세포가 반응하므로써 치조골과 악골의 개조가 일어난다. 이러한 기계적 자극은 크게 압축력과 인장력으로 대별된다. 따라서 본 연구는 인장력 및 압축력의 서로다른 기계적자극이 세포활성에 미치는 차이를 알아보기 위하여 조골세포주 MC3T3-E1 세포를 24well 배양접시에 well당 $2{\times}10^4$개의 세포를 넣어 배양한 후, 밀생상태가 되었을때 Diaphragm pump을 사용하여, $25g/cm^2$ 및 $300g/cm^2$의 압축력과 $-25g/cm^2$ 및 $-300g/cm^2$의 인장력을 지속적으로 가하였다. 배양한 후 각각 4일, 6일, 10일, 14일, 18일, 20일째에 ALP활성을 측정한 결과 같은 크기의 압력에서는 인장력에 비해 압축력을 가한 경우에서 ALP활성도가 증가되었으나, 세포는 기계적 자극의 양상 즉 압축력과 인장력을 구별하여 다르게 반응을 하지는 않는 것 같았다. 인장력과 압축력 모두에서 ALP활성도는 시간이 지남에 따라 대조군 수준으로 돌아왔다. 이는 기계적 자극은 세포의 증식과 분화가 왕성한 시기에 세포활성도에 더 크게 영향을 미치는 것으로 생각되며, 압축력과 인장력에 관계없이 기계적 자극의 양이 클수록 ALP활성도의 최고치 도달시간이 지연되어, 기계적 자극의 세기는 세포 활성도에 영향을 미칠 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1122-1126
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• 2009

The exogenously added cadaverine is effective in protecting Vibrio vulnificus from methyl viologen (MV)-induced superoxide stress at pH 8.5. Such a protective effect by cadaverine was not observed at pH 7.5. Consistently, the accumulated level of intracellular cadaverine at pH 8.5 is approximately four times as much as that of the control cell at pH 7.5. Cadaverine accumulation is not affected by MV. The protection of V. vulnificus by cadaverine from superoxide stress was abolished when cadB coding for the lysine-cadaverine antiporter was interrupted. However, the cadaverine-mediated protection was complemented with cadB DNA. Therefore, CadB of V. vulnificus not only acts as a lysine-cadaverine antiporter at acid pH to neutralize the external medium, but also mediates cadaverine uptake at alkaline pH to result in cell protection from superoxide stress.

• 약학회지
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• 제39권5호
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• pp.548-553
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• 1995

Effects of restraint stress and its modulations by ursodeoxycholic acid(UDCA) were evaluated on some biochemical and biophysical parameters in rats. Restraint stress induced elevations in blood alkaline phosphatase (ALP). cholesterol (CHOL), aspartate transaminase (GOT), alanine transaminase (GPT), lactate dehydrogenase (LDH) levels. It was also caused adrenal hypertrophy, decrease in weight of spleen and contents of ascorbic acid in stressed rats. As a results, stress indicators such as spleen, ascorbic acid, GOT, GPT, LDH were fastly changed after imposing stress, but those such as ALP, CHOL, adrenal were induced relatively later. UDCA was tested if it has an inhibitory effect against 18-hr restraint induced stress. UDCA lowered ALP, CHOL, LDH level and also effectively elevated the ascorbic acid contents in 25 mg/kg dosage of UDCA. In organ weights. the restraint stress induced increases in spleen and adrenal were attenuated by UDCA in 50 mg/kg dosage. However. stress-induced GOT and GPT levels were unaffected by UDCA.

• Nuclear Engineering and Technology
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• 제45권1호
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• pp.67-72
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• 2013

Stress corrosion cracking (SCC) behaviors of Alloy 690 were studied in lead-containing aqueous alkaline solutions using the slow strain rate tension (SSRT) tests in 0.1M and 2.5M NaOH with and without PbO at $315^{\circ}C$. The side and fracture surfaces of the alloy were then examined using scanning electron microscopy after the SSRT test. Microstructure and composition of the surface oxide layer were analyzed by using a field emission transmission electron microscopy, equipped with an energy dispersive X-ray spectroscopy. Even though Alloy 690 was almost immune to SCC in 0.1M NaOH solution, irrespective of PbO addition, the SCC resistance of Alloy 690 decreased in a 2.5M NaOH solution and further decreased by the addition of PbO. Based on thermodynamic stability and solubility of oxide, high Cr of 30wt% in the Alloy 690 is favorable to SCC in mild alkaline and acidic solutions whereas the SCC resistance of high Cr Alloy 690 is weakened drastically in the strong alkaline solution where the oxide is not stable any longer and solubility is too high to form a passive oxide locally.

• Membrane and Water Treatment
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• 제7권5호
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• pp.417-431
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• 2016

Poly(vinylidene fluoride) (PVDF) powder was treated with aqueous sodium hydroxide to obtain partially defluorinated fluoropolymers with expected properties such as improving hydrophilicity and fouling resistance. Raman spectrum and FT-IR results confirmed the existence of conjugated carbon double bonds after alkaline treatment. As the concentration increased, the degree of defluorination increased. The morphology and structure of membranes were examined. The permeation performance was investigated. The results showed that membrane's hydrophilicity increased with increase of the percentage of alkaline treated PVDF powder. Moreover, in terms of the water contact angle, it decreased from $92^{\circ}$ to a minimum of $68^{\circ}$; while water up take increased from 128 to 138%. Fluxof pure water and the cleaning efficiency increased with the increase of alkaline treated PVDF powder. The fouling potential also decreased with the increase of the percentage of alkaline treated PVDF powder. The reason that makes blending PVDF show different characteristics because of partial defluorination, which led the formation of conjugated C = C bonds and the inclusion of oxygen functionalities. The polyene structure followed by hydroxide attack to yield hydroxyl and carbonyl groups. Therefore, the hydrophilicity of blending membrane was improved. The SEM and porosity measurements showed that no obvious variations of the pore dimensions and structures for blend membranes were observed. Mechanical tests suggest that the high content of the alkaline treated PVDF result in membranes with less tolerance of tensile stress and higher brittleness. TGA results exhibited that the blend of alkaline treated PVDF did not change membrane thermal stability.

• Corrosion Science and Technology
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• 제17권3호
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• pp.116-122
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• 2018

The secondary coolant of a nuclear power plant has small amounts of various impurities (S, Pb, and Cl, etc.) introduced during the initial construction, maintenance, and normal operation. While the concentration of impurities in the feed water is very low, the flow of the cooling water is restricted, so impurities can accumulate on the Top of Tubesheet (TTS). This environment is chemically very complicated and has a very wide range of pH from acidic to alkaline. In this study, the characteristics of the oxide and the mechanism of stress corrosion cracking (SCC) are investigated for Alloy 690 TT in alkaline solution containing Pb, Cl, and S. Reverse U-bend (RUB) specimens were used to evaluate the SCC resistance. The test solution comprises 3m NaCl + 500ppm Pb + 0.31m $Na_2SO_4$ + 0.45m NaOH. Experimental results show that Alloy 690 TT of the crevice environment containing Pb, S, and Cl has significant cracks, indicating that Alloy 690 is vulnerable to stress corrosion cracking under this environment.