• Asian-Australasian Journal of Animal Sciences
• /
• 제7권3호
• /
• pp.397-400
• /
• 1994

The effect of xylazine administration on plasma cortisol, prolactin, glucose and packed cell volume (PCV) responses to immobilization and heat stress was investigated. Immobilization of rats for 2 hours by ligation of the fore and hind legs strongly caused approximately two-fold increase in plasma cortisol and prolactin levels. Plasma glucose and PCV were not significantly changed. Pretreatment of immobilized rats with xylazine (20 mg/kg body weight i.m.) resulted in approximately 20% reduction in both plasma cortisol and prolactin concentrations. A marked hyperglycemia and increase in the PCV value was observed. On the other hand, rats exposed to acute heat stress ($40^{\circ}C$, and 60% relative humidity) for 2 hours, also developed two fold increase in both plasma cortisol and prolactin concentrations and the pretreatment with xylazine caused a 20% reduction in the levels of both hormones. Plasma glucose level was not significantly changed in heat stressed rats but it was markedly increased after pretreatment with xylazine. PCV was significantly incrcased under heat stress and pretreatment with xylazine induced a pronounced elevation in this value. It was suggested that stimulation of cortisol and prolactin secretion in response to immobilization or heat stress can be partially reduced by an alpha 2-adrenergic agonist.

• Archives of Metallurgy and Materials
• /
• 제64권3호
• /
• pp.841-844
• /
• 2019

Poppet valves made from high-frequency heat-treated SUH3 steel have insufficient durability, and scratches appear on the valve face in prolonged use. It is necessary to develop surface treatment technology with excellent durability to prevent the deterioration of engine performance. Therefore, a surface treatment technology with higher abrasion resistance than existing processes was developed by direct metal deposition to the face where the cylinder and valve are closed. In this study, heat pretreatment and deposition tests were performed on three materials to find suitable powders. In the performance evaluation, the hardness, friction coefficient, and wear rate were measured. Direct metal deposition using Inconel 738 and Stellite 6 powders without heat pretreatment were experimentally verified to have excellent durability.

• 공업화학
• /
• 제21권1호
• /
• pp.24-28
• /
• 2010

이산화탄소의 광물고정화는 자연계의 풍화 작용을 모사한 것으로 매우 안정한 반응이지만 반응 속도가 매우 느리다. 이러한 반응 속도 증가를 위하여 광물의 전처리가 필요하다. 본 연구에서는 이산화탄소 광물고정화 속도 증가를 위한 두 가지의 전처리 방법을 소개하고 고정화 효율 증가를 확인하였다. 열적전처리는 $630^{\circ}C$에서 행해지는데, 이는 이산화탄소가 고정화되는 것을 방해하는 사문석 분자 내의 -OH기의 제거한다. FT-IR 피크를 통해 -OH기가 제거되는 것을 확인할 수 있다. 화학적전처리는 사문석 내의 주요 광물고정화 성분인 마그네슘 성분을 $75^{\circ}C$의 추출 온도에서 황산을 이용하여 추출해내는 것이다. 황산의 수소이온이 사문석 내의 결합을 약화시켜 마그네슘이 추출되도록 한다. 이는 ICP-AES와 XRF를 통하여 추출량을 확인하였다. 전처리가 끝난 사문석을 이용하여 이산화탄소 광물고정화 반응을 진행시 열적전처리의 경우 43%의 이산화탄소 고정화 효율을 나타내는데, 전처리를 하지 않았을 때 27%의 효율에 비하여 증가하였음을 확인하였다. 하지만 이 경우 많은 에너지가 소비된다는 단점이 있다. 화학적 전처리의 경우 열적전처리에 비해 45 atm, $25^{\circ}C$라는 비교적 온화한 조건에서 진행되는데, 이산화탄소 고정화 효율도 전처리 전인 24%에서 42%까지 상승하는 것을 확인할 수 있다.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2002년도 봄 학술발표대회 발표논문집
• /
• pp.471-474
• /
• 2002

SA treatment significantly increased thermotolerance In cucumber seedlings. Pretreatment of seeds with $CaCl_2$ solution enhanced the SA- induced thermotolerance. On the contrary, pretreatment with the $Ca^{2+}$ chelator EGTA lowered this SA-induced thermotolerance. In addition, pretreatment with $Ca^{2+}$ channel blocker verapamil also weakened the SA-induced thermotolerance. However, the calmodulin antagonist chlorpromazine(CPZ) had little effect on the SA-induced thermotolerance. Measurement of activity of the antioxidant enzyme APX and the level of lipid peroxidation (in term of MDA) indicated that heat stress induced an oxidative stress in cucumber seedlings. SA treatment induced higher activities of APX and a lower level of lipid peroxidation. $Ca^{2+}$ pretreatment further enhanced the SA-induced increase in APX activity and lowered the heat stress-induced lipid peroxidation, but EGTA pretreatment had a contrary effect. These results suggest that $Ca^{2+}$ and calmodulin may be involved In the acquisition of the SA-induced thermotolerance; antioxidant enzyme system take part in the final generation of the SA-induced thermotolerance.

• Journal of the Korean Wood Science and Technology
• /
• 제40권5호
• /
• pp.343-351
• /
• 2012

A large diameter roundwood is an important element of Korean traditional buildings, Hanok, and is hard to be dried without surface cracks. Four different pretreatments, such as pre-cracking, oil heating, kerfing-oil heating and PEG impregnation, were investigated for reducing the surface cracks of large-diameter roundwood specimens during heat treatment. The roundwood specimens of pre-cracking, oil heating and kerfing-oil heating showed surface cracks during pretreatment, but that of PEG impregnation did not. It was confirmed that kerfing reduced the total crack width. Among the four pretreatments and control only the PEG impregnation roundwood specimen had no crack on both outer and inner surfaces after heat treatment. The PEG impregnation specimen shrank only 1.6% in the tangential direction while the pre-cracking did 8.0%.

• 한국미생물·생명공학회지
• /
• 제22권2호
• /
• pp.222-225
• /
• 1994

Three kinds of pretreatment methods were used for selectivel isolation of soil actinomy cetes. One hundred and six strains were isolated on Bennet's agar and 114 strains were on humic acid-vitamin agar from 5 domestic soil samples. All of these isolates were identified to the genus level based on morphological and physiological characheristics. Among three methods, dry heat was most effective to isolate many different strains including rare actinomycetes. On genus, Bennet's agar was effective for selective isolation of Nocardia but bumic acid-vitamin agar for another rare actinomycetes.

• Journal of Periodontal and Implant Science
• /
• 제42권3호
• /
• pp.95-104
• /
• 2012

Purpose: The purpose of this study was to determine whether increasing the Ti6Al4V surface oxide negative charge through heat ($600^{\circ}C$) or radiofrequency plasma glow discharge (RFGD) pretreatment, with or without a subsequent coating with fibronectin, stimulated osteoblast gene marker expression in the MC3T3 osteoprogenitor cell line. Methods: Quantitative real-time polymerase chain reaction was used to measure changes over time in the mRNA levels for osteoblast gene markers, including alkaline phosphatase, bone sialoprotein, collagen type I (${\alpha}1$), osteocalcin, osteopontin and parathyroid hormone-related peptide (PTH-rP), and the osteoblast precursor genes Runx2 and osterix. Results: Osteoprogenitors began to differentiate earlier on disks that were pretreated with heat or RFGD. The pretreatments increased gene marker expression in the absence of a fibronectin coating. However, pretreatments increased osteoblast gene expression for fibronectin-coated disks more than uncoated disks, suggesting a surface oxide-mediated specific enhancement of fibronectin's bioactivity. Heat pretreatment had greater effects on the mRNA expression of genes for PTH-rP, alkaline phosphatase and osteocalcin while RFGD pretreatment had greater effects on osteopontin and bone sialoprotein gene expression. Conclusions: The results suggest that heat and RFGD pretreatments of the Ti6Al4V surface oxide stimulated osteoblast differentiation through an enhancement of (a) coated fibronectin's bioactivity and (b) the bioactivities of other serum or matrix proteins. The quantitative differences in the effects of the two pretreatments on osteoblast gene marker expression may have arisen from the unique physico-chemical characteristics of each resultant oxide surface. Therefore, engineering the Ti6Al4V surface oxide to become more negatively charged can be used to accelerate osteoblast differentiation through fibronectin-dependent and independent mechanisms.

• Animal Bioscience
• /
• 제34권6호
• /
• pp.1006-1013
• /
• 2021

Objective: Cells have increased susceptibility to activation of apoptosis when suffering heat stress (HS). An effective supplementation strategy to mimic heat-induced apoptosis of bovine mammary epithelial cells (MECs) is necessary to maintain optimal milk production. This study aimed to investigate possible protective effects of the anti-apoptotic activity of 5-aminolevulinic acid (5-ALA) against HS-induced damage of bovine MECs. Methods: Bovine MECs were pretreated with or without 5-ALA at concentrations of 10, 100, and 500 µM for 24 h followed by HS (42.5℃ for 24 h and 48 h). Cell viability was measured with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Real-time quantitative polymerase chain reaction and Western blotting were used to explore the regulation of genes associated with apoptosis, oxidative stress, and endoplasmic reticulum (ER) stress genes. Results: We found that 5-ALA induces cytoprotection via inhibition of apoptosis markers after HS-induced damage. Pretreatment of bovine MECs with 5-ALA resulted in dramatic upregulation of mRNA for nuclear factor erythroid-derived 2-like factor 2, heme oxygenase-1, and NAD(P)H quinone oxidoreductase 1, all of which are antioxidant stress genes. Moreover, 5-ALA pretreatment significantly suppressed HS-induced ER stress-associated markers, glucose-regulated protein 78, and C/EBP homologous protein expression levels. Conclusion: 5-ALA can ameliorate the ER stress in heat stressed bovine MEC via enhancing the expression of antioxidant gene.

• 유기물자원화
• /
• 제18권1호
• /
• pp.81-88
• /
• 2010

음식폐기물의 혐기성 발효시 열적 전처리의 최적 조건을 도출하기 위하여 수소 발생 특성을 평가하였다. 음식폐기물의 열적 전처리의 경우 용해성 화학적 산소요구량(SCOD)과 탄수화물 함량을 증가시켜 수소 수율을 향상시키는 것으로 나타났다. 실험결과 SCOD와 탄수화물을 기준으로 한 최대 가용화 효율은 각각 55.1%와 223.6%로 나타났다. 반응시간에 따라 전처리 효과는 증가하는 경향을 보였으나 20분간 1시간 비교시 약 7%의 차이를 보여 20분 이상의 반응시간의 증가는 크지 않은 것으로 나타났다.

• Tuberculosis and Respiratory Diseases
• /
• 제44권6호
• /
• pp.1343-1352
• /
• 1997

연구배경 : 패혈증이나 이에 합병된 급성호흡곤란증후군 환자들은 고열을 동반하는 경우가 많다. 발열은 조직의 대사를 항진시키므로 조직내 산소공급에 제한이 초래되는 패혈증 환자들에서 발열이 동반되는 경우 열을 동반하지 않는 경우보다 중요기관의 산소공급이 상대적으로 저하될 가능성이 있다. 반면, 발열상태는 조직내 열충격단백질 (heat shock protein, HSP)의 생성을 유도하여 패혈증에 의한 비가역적인 손상으로부터 세포들을 보호함으로써 생체의 방어기전에 유려하게 작용할 수도 있어 패혈중 이에 합병된 급성 폐손상 환자들의 발열에 대한 임상적 의미는 아직 규명되어 있지않았다. 본 연구는 열을 전처치 하였거나 하지 않은 Sprague-Dawley rat의 기도에 TNF를 주입한 후 TNF에 의해 유도되는 급성 폐손상의 정도를 비교함으로써 열이 급성 폐손상에 미치는 효과를 관찰하고자 하였다. 대상 및 방법 : 급성 폐손상의 지표로는 백서의 우측폐내 $I^{125}$의 분당 측정량 대비 1mL의 혈중내 $I^{125}$의 분당 측정량의 비율로 정의한 단백누출지표와 백혈구의 조직내 침윤정도를 반영하는 myeloperoxidase(MPO)의 활성도를 측정하였다. 결과는 평균(${\pm}$ 표준오차)로 표기하였다. 결 과 : 백서의 기도에 생리식염수를 주입한 백서들은 열을 전처치 하였거나 하지 않은 경우 두 군사이의 단백 누출 지표는 각각 0.099(${\pm}0.024$) 및 0.123(${\pm}0.005$)로서 차이가 없었으며 MPO도 4.58(${\pm}0.79\;U/gm$) 및 7.32(${\pm}0.97\;U/gm$)로서 열을 전처치 할 경우 다소 감소되는 경향(P=0.064)를 보였으나 차이가 없었다. 백서의 기도에 TNF-$\alpha$을 주입한 치료군에서 열 전처치한 백서군은 단백누출지표 0.137(${\pm}0.012$) 및 MPO 7.01(${\pm}0.89\;U/gm$)로서 열 전처치 않은 백서군 단백누출지표 0.186(${\pm}0.015$) 및 MPO 14.11(${\pm}1.08\;U/gm$)에 비해 낮았으며(각 P<0.05) 정상군과는 차이가 없었다. MPO 활성도가 단백 증가되었다(r=0.564, P<0.005). 열 전처치 하지 않은 백서에 비해 열 전처치한 백서의 폐 조직내 HSP 72 단백질의 발현은 열 충격 후 18시간 및 23시간 뒤에도 증가되어 나타났다. 결 론 : 백서에 열을 전처치 할 경우 TNF-$\alpha$로 유도되는 급성 폐손상이 경감되므로 발열이 백서의 방어기전에 유리하게 작용한 것으로 사료되었다.