• Title/Summary/Keyword: environmental stress response

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Response Analysis of Nearby Structures to Excavation-Induced Advancing Ground Movements (지반굴착 유발 진행성 지반변위에 의한 인접구조물의 거동분석)

  • Son, Moorak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.4C
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    • pp.153-162
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    • 2009
  • This paper investigates the effects of excavation-induced ground movements on nearby structures, considering soil-structure interactions of different soil and structural characteristics. The response of four and two-story block structures, which are subjected to excavation-induced advancing ground movements, are investigated in different soil conditions using numerical analysis. The structures for numerical analysis are modelled to have cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The response of four and two-story block structures are investigated with advancing ground movement phases and compared with the response of structures which are subjected to excavation-induced total ground movement. The response of structures is compared among others in terms of the magnitude and shape of deformations and cracks in structures for different structure and ground conditions. The results of the comparison provide a background for better understandings for controlling and minimizing building damage on nearby structures due to excavation-induced ground movements.

Changes of Vascular Contraction and Relaxation of Rat aorta under Arsenic Stress (비소 스트레스에 의한 흰쥐 대동맥의 수축과 이완반응의 변화양상)

  • 권윤정;박태규;성유진;김인겸;김중영
    • Journal of Life Science
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    • v.13 no.5
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    • pp.634-641
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    • 2003
  • In order to examine whether arsenic, one of environmental stress, contribute to augumentation and relaxation of rat aorta, this study was performed in vivo and in vitro, using intacted or denuded rats aorta ring preparation, respectively. The carotid arterial pressure was recorded on an ink-writing physiograph(Grass Co. 79E) connected to strain gauge. The contractile response of vascular ring with or without endothelium preparation isolated from rat were determined in organ bath and was recorded on physiograph connected to isometric transducer. Vasopressin-,and phenylephrine- induced increase in arterial pressure significantly enhanced in arsenic-treated rats; increase of 19.1%, and 46.6%, respectively. Vascular contractile response was measured in vitro preparations exposed to 0, 0.5, 1, 2 and 4 mM of arsenic for 1, 3, 5 and 8 hours. The dose-vascular responses of phenylephrine augmented by increasing dose of arsenic in the strips exposed to arsenic for 8 hours, and did not augmented for 1, 3, 5 hours. The phenomenon was not affected by strips denuded endothelium. And the response of relaxation of rat aorta induced by nitroprusside was not influenced by arsenic stress, but acetylcholine was a little increased. compared to that of control. There were no significant difference in relaxation between control and arsenic treated rings with endothelium or denuded. All of the results, phenyleprine-induced vascular contraction was significantly enhanced in 4 mM arsenic-treated rat aortic rings compared with control, whether endothelium was present or denuded at 8 hours after arsenic treatment. It may be a mechanism by which long-term arsenic stresses play a role in development of hypertension.

Growth Response and Changes of Nitrate and Sucrose Content in Tomato under Salt Stress Condition (염스트레스에 의한 토마토 생장반응과 식물체내 Nitrate 및 Sucrose 변화)

  • Lee, Ju-Young;Jang, Byoung-Choon;Lee, Su-Yeon;Park, Jae-Hong;Choi, Geun-Hyoung;Kim, Sam-Cwaun;Kim, Tae-Wan
    • Korean Journal of Soil Science and Fertilizer
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    • v.41 no.3
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    • pp.164-169
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    • 2008
  • This experiment was carried out to find the growth response and changes of nitrate and soluble sugar content in tomato leaves with salt stress. Tomato (Solanum lycopericum) seedlings were grown under different electrical conductivity (EC) levels adjusted with $CaCl_2$ as 1, 2, and $6dS\;m^{-1}$. The growth response and contents of nitrate and soluble sugar in tomato plants were examined at 7 and 14 days after salt treatment. Leaf area and dry weight ratio of shoot to root of tomato plants were decreased as EC level increased. Photosynthetic rate of leaves was reduced under high EC level due to the stomatal closure and the reduction of transpiration rate. The soluble sugar and starch content were lower in the tomato leaves grown under high EC level. Total nitrogen and nitrate contents were decreased in high EC level, whereas the ammonium content was increased. High-salt stress induced the accumulation of salt crystal in mesophyll cells of tomato leaf.

Verification of Numerical Analysis Technique of Dynamic Response of Seabed Induced by the Interaction between Seabed and Wave (파랑-지반 상호작용에 의한 해저지반의 동적응답 수치해석법 검증)

  • Kang, Gi-Chun;Kim, Sung-Woung;Kim, Tae-Hyung;Kim, Do-Sam;Kim, Jae-Hong
    • Journal of the Korean Geotechnical Society
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    • v.31 no.1
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    • pp.5-14
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    • 2015
  • Seabed may undergo large excess pore water pressure in the case of long duration of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. Thus, it is necessary to develop a numerical technique which can precisely evaluate the dynamic response of seabed due to wave action. In this study, a new numerical technique named mixed model (2D NIT & FLIP models) was proposed. The dynamic wave pressure and water flow velocity acting on the boundary between seabed and the wave field was estimated using 2D-NIT model. This result was used as input data in FLIP program for investigation of dynamic response of seabed. To secure the reliability of the mixed model, the numerical analysis results of the mixed model were compared with Yamamoto's solution and Chang's experiment results. The comparison results indicated that there were some differences between them, but the general trend of the effective stress increment and the excess pore water pressure along the depth of seabed was similar to each other. Thus, this study clearly supports the plausibility of the numerical analysis of the mixed model.

The Mechanism of Stomatal Closing by $H_2O_2$ in Epidermal Strips of Commelina communis L. (닭의장풀의 분리표피에서 $H_2O_2$에 의한 기공 닫힘기작)

  • 이준상;전방욱
    • Journal of Environmental Science International
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    • v.6 no.2
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    • pp.125-131
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    • 1997
  • The mechanism of stomatal closing in response to $O_2$ was indirectly investigated by using $H_2O_2$ which is the intermediate product of $O_2$ metabolites. Stomata in epidermal strips close in response to $H_2O_2$. The effect of $H_2O_2$ on stomatal closing was dependent on the concentration of $H_2O_2$. 10 ppm $H_2O_2$ showed a clear effect on stomatal closing and 1000 ppm $H_2O_2$ induced complete stomatal closing after the treatment of 3 hours. Stomatal closing by $H_2O_2$ in intact leaf was also observed by measuring the diffusion resistance with porometer. It was found that the stomatal closing by $H_2O_2$ was not mediated by $Ca^{2+}$, and that was a different result observed in stomatal closing by water stress. Reversely, $Ca^{2+}$ showed a great inhibition on stomatal closing. The leakage of K+ in epidermal strips was doubled in response to $H_2O_2$ when it was campared to the control. 10 ppm $H_2O_2$ decreased photosynthetic activity. Fv/Fm representing the activity of Photosystem II was reduced about 4 % in 10 ppm $H_2O_2$ and 8 % in 100 ppm $H_2O_2$ In the treatment of 1.5 hour. However, stomatal closing by 10 ppm $H_2O_2$ was reduced about 56 %. According1y, it can be suggested that stomatal closing by $H_2O_2$ is related with the decrease of photosynthetic activity, but it was chiefly induced by the change of the membrane permeability. Key words Commelina communis, stomatal closing, $H_2O_2$, $Ca^{2+}$, photosynthesis.

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Dynamic Response Analysis of Pipe Subjected to Underwater Explosion (수중폭발로 인한 파이프의 동적 응답해석)

  • Kim, Seongbeom;Lee, Kyungjae;Jung, Dongho;Park, Taehyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.1
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    • pp.9-16
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    • 2014
  • In recent years, the structural shock response to UNDEX (UNDerwater EXplosion) has been studied as much, or more, through numerical simulations than through testing for several reasons. Very high costs and sensitive environmental concerns have kept destructive underwater explosion testing to a minimum. Increase of simulation capabilities and sophisticated simulation tools has made numerical simulations more efficient analysis methods as well as more reliable testing aids. In this study, the main issue is the fluid-structure interaction. Here, appropriate relations between the acoustic pressure on the fluid surface and displacements on the structure surface are formed internally. The analysis was carried out using ABAQUS/Explicit and the results have been visualized in ABAQUS CAE. The shock loading history, acoustic pressure, stress of stand-off point, the velocity and strain energy time histories were presented.

Prediction of Tunnel Response by Spatially Variable Ground Motion (공간적으로 변이하는 지진파에 대한 터널의 응답 예측)

  • Kim, Intai;Han, Jungwoo;Yun, Seung;Park, Duhee
    • Journal of the Korean GEO-environmental Society
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    • v.9 no.4
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    • pp.53-61
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    • 2008
  • Various components including wave scattering, wave passage, and site amplification effects cause the ground motion to vary spatially. The spatially varying ground motion can significantly influence the dynamic response of longitudinal structures such as bridges and tunnels. While its effect on bridges has been extensively studied, there is a lack of study on its effect on underground tunnels. This paper develops a new procedure for simulating the tunnel response under spatially varying ground motion. The procedure utilizes the longitudinal displacement profile, which is developed from spatially variable ground motion time histories. The longitudinal displacement profile is used to perform a series of pseudo-static three dimensional finite element analyses. Results of the analyses show that the spatially variable ground motion cause longitudinal bending of the tunnel and can induce substantial axial stress on the tunnel lining. The effect can be significant at boundaries at which the material properties of the ground change in the longitudinal direction.

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Comparative physiological and proteomic analysis of leaf in response to cadmium stress in sorghum

  • Roy, Swapan Kumar;Cho, Seong-Woo;Kwon, Soo Jeong;Kamal, Abu Hena Mostafa;Kim, Sang-Woo;Lee, Moon-Soon;Chung, Keun-Yook;Woo, Sun-Hee
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2017.06a
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    • pp.124-124
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    • 2017
  • Cadmium (Cd) is of particular concern because of its widespread occurrence and high toxicity and may cause serious morpho-physiological and molecular abnormalities in in plants. The present study was performed to explore Cd-induced morpho-physiological alterations and their potentiality associated mechanisms in Sorghum bicolor leaves at the protein level. Ten-day-old sorghum seedlings were exposed to different concentrations (0, 100, and $150{\mu}M$) of $CdCl_2$, and different morpho-physiological responses were recorded. The effects of Cd exposure on protein expression patterns in S. bicolor were investigated using two-dimensional gel electrophoresis (2-DE) in samples derived from the leaves of both control and Cd-treated seedlings. The observed morphological changes revealed that the plants treated with Cd displayed dramatically altered shoot lengths, fresh weights, and relative water content. In addition, the concentration of Cd was markedly increased by treatment with Cd, and the amount of Cd taken up by the shoots was significantly and directly correlated with the applied level of Cd. Using the 2-DE method, a total of 33 differentially expressed protein spots were analyzed using MALDI-TOF/TOF MS. Of these, treatment with Cd resulted in significant increases in 15 proteins and decreases in 18 proteins. Significant changes were absorbed in the levels of proteins known to be involved in carbohydrate metabolism, transcriptional regulation, translation and stress responses. Proteomic results revealed that Cd stress had an inhibitory effect on carbon fixation, ATP production and the regulation of protein synthesis. In addition, the up-regulation of glutathione S-transferase and cytochrome P450 may play a significant role in Cd-related toxicity and stress responses. Our study provides insights into the integrated molecular mechanisms involved in response to Cd and the effects of Cd on the growth and physiological characteristics of sorghum seedlings. The upregulation of these stress-related genes may be candidates for further research and use in genetic manipulation of sorghum tolerance to Cd stress.

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The fucose containing polymer (FCP) rich fraction of Ascophyllum nodosum (L.) Le Jol. protects Caenorhabditis elegans against Pseudomonas aeruginosa by triggering innate immune signaling pathways and suppression of pathogen virulence factors

  • Kandasamy, Saveetha;Khan, Wajahatullah;Kulshreshtha, Garima;Evans, Franklin;Critchley, Alan T.;Fitton, J.H.;Stringer, Damien N.;Gardiner, Vicki-Anne;Prithiviraj, Balakrishnan
    • ALGAE
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    • v.30 no.2
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    • pp.147-161
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    • 2015
  • Brown algal extracts have long been used as feed supplements to promote health of farm animals. Here, we show new molecular insights in to the mechanism of action of a fucose containing polymer (FCP) rich fraction from the brown seaweed Ascophyllum nodosum using the Caenorhabditis elegans-Pseudomonas aeruginosa PA14 infection model. FCP enhanced survival of C. elegans against pathogen stress, correlated with up-regulation of key immune response genes such as: lipases, lysozyme (lys-1), saponin-like protein (spp-1), thaumatin-like protein (tlp-1), matridin SK domain protein (msk-1), antibacterial protein (abf-1), and lectin family protein (lfp). Further, FCP caused down regulation of P. aeruginosa quorum sensing genes: (lasI, lasR, rhlI, and rhlR), secreted virulence factors (lipase, proteases, and elastases) and toxic metabolites (pyocyanin, hydrogen cyanide, and siderophore). Biofilm formation and motility of pathogenic bacteria were also greatly attenuated when the culture media were treated with FCP. Interestingly, FCP failed to mitigate the pathogen stress in skn-1, daf-2, and pmk-1 mutants of C. elegans. This indicated that, FCP treatment acted on the regulation of fundamental innate immune pathways, which are conserved across the majority of organisms including humans. This study suggests the possible use of FCP, a seaweed component, as a functional food source for healthy living.

Chlorophyll Fluorescence and Antioxidative Enzyme Activity of Crinum Leaves Exposed to Natural Environmental Stress in Winter (겨울철 자연환경에 노출된 문주란 잎의 엽록소형광과 항산화효소 활성에 관한 연구)

  • 오순자;고석찬
    • Korean Journal of Environmental Biology
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    • v.22 no.1
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    • pp.233-241
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    • 2004
  • Chlorophyll fluorescence and antioxidative enzyme activity were investigated from leaves of Crinum asiaticum var. japonicum under the natural condition in winter, in order to monitor plant response and physiological states such as vitality, productivity and so on. In the O-J-I-P transients, the fluorescence intensity of J, I, P-step decreased remarkably depending on temperature drop in winter. The photochemical efficiencies of PSII, Fv/Fm, were significantly low in late winter with decrease of Fm. These results indicate that Crinum plants were affected by seasonal drop of temperature. The catalase activity significantly decreased depending on temperature drop in winter. However, the activity of superoxide dismutase ascorbate peroxidase and peroxidase slightly increased in winter while some isoenzymes appeared in winter. These results, with the remarkable decrease of Ev/Fm in winter, represent that Crinum plants were exposed to oxidative stress and subsequently damaged leading to cell death.