• 제목/요약/키워드: Transient effects

검색결과 1,113건 처리시간 0.029초

인삼성분(人蔘成分)의 혈압강하기전(血壓降下機轉)에 관한 연구(硏究) (Studies on Hypotensive Mechanism of Ginseng Components)

  • 김낙두;김인철
    • 생약학회지
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    • 제9권1호
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    • pp.41-47
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    • 1978
  • Total saponins and ether extracts of red and white ginseng were obtained and their effects on blood pressure in cat and their histamine liberating activities in rabbits were measured. 1) Ether extract of red ginseng showed a transient hypotensive effect and subsequently showed a remarkable and persistent hypotensive effect, whereas other three fractions, such as saponin fractions of red and white ginseng and ether extract of white ginseng showed only a initial transient hypotensive effects. 2) Histamine levels liberated into blood after administration of each fractions measured by the bioassay with guinea pig ileum. Ether extract of red ginseng immediately increased histamine contents in plasma but the histamine levels decreased to normal level within 10min in spite of decreased blood pressure was sustained. Although white ginseng saponin lowered blood pressure immediately when it is administered, histamine release was observed after 10min. The results suggest that hypotensive effects of ginseng seems to have no correlation with the histamine liberating activity. Ginseng appears to show hypotensive effect via some other mechanisms.

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모터의 연성을 고려한 로터리 압축기의 과도진동 해석 (Transient Vibration Analysis of a Rotary Compressor Considering the Coupled Effects of Motor)

  • 정의봉;김정훈;안세진;황선웅
    • 한국소음진동공학회논문집
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    • 제12권11호
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    • pp.847-855
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    • 2002
  • A rotary compressors are used most widely In air-conditioning systems. Noise and vibration of a rotary compressor is an important problems during turning on and off as well as during operating. To estimate the vibration occurring during turning on and off, vibration analysis of a motor-compressor coupled system is required. In this paper, through modeling the motor and solving the forces from the equations of motion of the moving parts, the analysis of vibration of the compressor taking into consideration of the effects of motor and moving parts was performed. The accelerations of accumulator during turning on. turning off and operation are simulated. And simulated accelerations are compared with those of experimental data.

유동방향의 열전도가 전열면의 성능에 미치는 영향 (Effects of longitudinal conduction on the performance of heat transfer surfaces)

  • 박병규;홍택;박상희
    • 설비공학논문집
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    • 제11권5호
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    • pp.561-569
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    • 1999
  • The effects of longitudinal heat conduction on the performance of heat transfer surfaces are investigated by using a single-blow method. In the transient testing method for determining the heat transfer characteristics, exponential inlet temperature variations are made by using screen-mesh heater with small time constant and low frontal velocities of the test section, and the experimentally determined inlet temperature profile is used as the inlet fluid temperature condition. The effects of longitudinal heat conduction are negligible only if $\gamma^\act<0.05\;and \;N_{tu}\le3$ and should be considered if $N_{tu}\le3$ The test results ate compared with the existing theoretical and experimental data and the validity of this technique is confirmed by the good agreement.

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Igniter and Thickness Effects on Upward Flame Spread

  • J.Q. Quintiere;Lee, C.H.
    • 한국화재소방학회:학술대회논문집
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    • 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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    • pp.154-161
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    • 1997
  • Several studies have developed upward flame spread models which use somewhat different features. However, the models have not considered the transient effects of the igniter and the burning rate. Thus, the objective of this study is to examine a generalized upward flame spread model which includes these effects. We shall compare the results with results from simpler models used in the past in order to examine the importance of the simplifying assumptions. We compare these results using PMMA, and we also include experimental results for comparison. The results of the comparison indicate that flame velocity depends on the thermal properties of a material, the specific model for flame length and transient burning rate, as well as other variables including the heat flux by igniter and flame itself. The results from the generalized upward flame spread model can provide a prediction of flame velocity, flame and pyrolysis height, burnout time and position, and rate of energy output as a function of time.

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과중량을 이용한 워밍업 점프가 사후 점프 수행에 미치는 영향 (Effect of Loaded Warm-up Jumps on the Following Performance of Vertical Jump)

  • 김현균;김영관;조행난
    • 한국운동역학회지
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    • 제25권2호
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    • pp.167-174
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    • 2015
  • Purpose : The purpose of this study was to investigate the effects of loaded vertical jumps on the following vertical jumps and to find how long the transient effect of warm-ups would continue. Methods : Twelve healthy college male students, majoring in physical education, participated in this study voluntarily. They performed three sets of unloaded jumps (pre-jump, 5% post jump, and 10% post jump) and two sets of loaded jumps (5% and 10% loaded jumps) according to the counter-balanced order. At each set, three trials of maximal vertical jumps were performed by a 30 second interval between trials and a 3 minute break after warm-up jumps. Force platform and motion capturing system were used to record motions and ground reaction force. Results : Only 5% post-warm-up jumps ($48.29{\pm}2.06cm$) showed significant increase in the jump height compared with pre-warm-up jumps ($47.35{\pm}2.21cm$). The transient effects of loaded warm-ups disappeared 4 minutes after loaded jumps. Conclusion : Conclusively, a decent amount of loading (around 5% extra of body weight) during sport specific warm-ups would give a positive, transient effect on the performance of the vertical jump.

Neuroprotective Effects of Hydroxyfullerene in Rats Subjected to Global Cerebral Ischemia

  • Kim, Young-Ock;Kim, Hak-Jae;Kim, Su-Kang;Yoon, Bum-Chul
    • Molecular & Cellular Toxicology
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    • 제4권3호
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    • pp.218-223
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    • 2008
  • Oxidative stress is believed to contribute to the neuronal damage induced by cerebral ischemia/reperfusion injury. The present study was undertaken to evaluate the possible antioxidant neuroprotective effect of hydroxyfullerene (a radical absorbing cage molecule) against neuronal death in hippocampal CA1 neurons following transient global cerebral ischemia in the rat. Transient global cerebral ischemia was induced in male Wistar rats by four vessel- occlusion (4VO) for 10 min. Lipid peroxidation in brain tissues was determined by measuring the concentrations of thiobarbituric acid-reactive substances (TBARS). Furthermore, the apoptotic effects of ${H_2}{O_2}$ on PC12 cells were also investigated. Cell viabilities were measured using MTT [3-(4,5-dimethylthiazolyl-2)-2,-5-diphenyltetrazolium bromide] assays. Hydroxyfullerene, when administered to rats at 0.3-3 mg/kg i.p. at 0 and 90 minutes after 4-VO was found to significantly reduce CA1 neuron death by 72.4% on hippocampal CA1 neurons. Our findings suggest that hydroxyfullerene protects neurons from transient global cerebral injury in the rat hippocampus by reducing oxidative stress and lipid peroxidation levels, which contribute to apoptotic cell death.

Fucoidan Extract from Laminaria religiosa Suppresses Ischemia-induced Apoptosis and Cell Proliferation in the Hippocampus of Gerbils

  • Lee, Jong-Jin;Song, Yun-Kyung;Lim, Hyung-Ho
    • 대한한의학회지
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    • 제27권4호
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    • pp.105-115
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    • 2006
  • Fucoidan has been shown to exhibit a host of biological activities, including anti-coagulant, anti-thrombotic, anti-tumourigenic, anti-inflammatory, anti-viral, anti-complementary and neuroprotective effects. In the present study, we attempted to determine the effects of Fucoidan on both apoptosis and cell proliferation in the hippocampal CA1 region and the dentate gyrus of gerbils after the induction of transient global ischemia. This experiment involved the use of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay as well as immunohistochemisty for caspase-3 and 5-bromo-2'-deoxyuridine (BrdU). The monosaccharide composition of the purified Fucoidan which had been extracted from Laminaria religiosa was utilized in this study. The present study clearly induces that apoptotic cell death and cell proliferation in the gerbil's hippocampal regions increased significantly following the induction of transient global ischemia and the results of this study also indicate that Fucoidan exerted a suppressive effect on this observed ischemia-induced increase in apoptosis within the CA1 and dentate gyrus, and also suppressed cell proliferation in the dentate gyrus.

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Geometrically non-linear transient C° finite element analysis of composite and sandwich plates with a refined theory

  • Kommineni, J.R.;Kant, T.
    • Structural Engineering and Mechanics
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    • 제1권1호
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    • pp.87-102
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    • 1993
  • A $C^{\circ}$ continuous finite element formulation of a higher order displacement theory is presented for predicting linear and geometrically non-linear in the sense of von Karman transient responses of composite and sandwich plates. The displacement model accounts for non-linear cubic variation of tangential displacement components through the thickness of the laminate and the theory requires no shear correction coefficients. In the time domain, the explicit central difference integrator is used in conjunction with the special mass matrix diagonalization scheme which conserves the total mass of the element and included effects due to rotary inertia terms. The parametric effects of the time step, finite element mesh, lamination scheme and orthotropy on the linear and geometrically non-linear responses are investigated. Numerical results for central transverse deflection, stresses and stress resultants are presented for square/rectangular composite and sandwich plates under various boundary conditions and loadings and these are compared with the results from other sources. Some new results are also tabulated for future reference.

Mitochondrial Porin Isoform AtVDAC1 Regulates the Competence of Arabidopsis thaliana to Agrobacterium-Mediated Genetic Transformation

  • Kwon, Tackmin
    • Molecules and Cells
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    • 제39권9호
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    • pp.705-713
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    • 2016
  • The efficiency of Agrobacterium-mediated transformation in plants depends on the virulence of Agrobacterium strains, the plant tissue culture conditions, and the susceptibility of host plants. Understanding the molecular interactions between Agrobacterium and host plant cells is crucial when manipulating the susceptibility of recalcitrant crop plants and protecting orchard trees from crown gall disease. It was discovered that Arabidopsis voltage-dependent anion channel 1 (atvdac1) mutant has drastic effects on Agrobacterium-mediated tumorigenesis and growth developmental phenotypes, and that these effects are dependent on a Ws-0 genetic background. Genetic complementation of Arabidopsis vdac1 mutants and yeast porin1-deficient strain with members of the AtVDAC gene family revealed that AtVDAC1 is required for Agrobacterium-mediated transformation, and there is weak functional redundancy between AtVDAC1 and AtVDAC3, which is independent of porin activity. Furthermore, atvdac1 mutants were deficient in transient and stable transformation by Agrobacterium, suggesting that AtVDAC1 is involved in the early stages of Agrobacterium infection prior to transferred-DNA (T-DNA) integration. Transgenic plants overexpressing AtVDAC1 not only complemented the phenotypes of the atvdac1 mutant, but also showed high efficiency of transient T-DNA gene expression; however, the efficiency of stable transformation was not affected. Moreover, the effect of phytohormone treatment on competence to Agrobacterium was compromised in atvdac1 mutants. These data indicate that AtVDAC1 regulates the competence of Arabidopsis to Agrobacterium infection.