|
Parametrically excited oscillation of stay cable and its control in cable-stayed bridges
SUN Bing-nan, WANG Zhi-gang, KO, J.M., NI, Y.Q.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(1): 13-20.
https://doi.org/10.1631/jzus.2003.0013
This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.
|
|
Surface plasmon resonance analysis to evaluate the importance of heparin sulfate groups\' binding with human aFGF and bFGF
WU Xiao-feng, XU Ya-xiang, SHEN Guo-xin, KAMEI Kaeko, TAKANO Ryo, HARA Saburo
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(1): 86-94.
https://doi.org/10.1631/jzus.2003.0086
Human acidic and basic fibroblast growth factors (aFGF and bFGF) are classic and well characterized members of the heparin-binding growth factor family. Heparin is generally thought to play an extremely important role in regulating aFGF and bFGF bioactivities through its strong binding with them. In order to unravel the mechanism of the interactions between heparin and FGFs, and evaluate the importance of heparin sulfate groups\' binding with FGFs, surface plasmon resonance analyses were performed using IAsys Cuvettes System. Heparin and its regioselectively desulfated derivatives were immobilized on the cuvettes. aFGF and bFGF solutions with different concentrations were pipetted into the cuvettes and the progress of the interaction was monitored in real-time by Windows-based software, yielding kinetic and equilibrium constants for these interactions. In addition, in order to reduce the delicate difference among the cuvettes, inhibition analyses of mixture of FGFs and immobilized native heparin by modified heparins were also done. The data from these two methods were similar, indicating that all sulfate groups at 2-O, 6-O and N- in heparin were required for the binding to aFGF; and that their contribution to the binding was in the order 2-O, N- and 6-O-sulfate group. In contrast, definite contribution of the 6-O-sulfate group to the binding with bFGF was most apparent, while the other two sulfate groups appeared to be necessary in the order 2-O and N-sulfate group. These methods established here can be used for analysing the effect of sulfate groups in heparin on the binding with other human FGF members or other heparin-binding proteins.
|
|
Quantitative assessment of the infection rate of the entomophthoraceous fungus, Zoophthora anhuiensis against the green peach aphid Myzus persicae
FENG Ming-guang, XU Qian
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(1): 95-100.
https://doi.org/10.1631/jzus.2003.0095
A two-step method was developed to quantitatively assess the infection rate of the entomophthoraceous fungus, Zoophthora anhuiensis (Li) Humber, on the green peach aphid, Myzus persicae (Sulzer). Firstly, a standard time-dose-mortality relationship, established by modeling data from bioassay 1 at varying conidial dosages (0.4-10.4 conidia/mm2) of Z. anhuiensis F97028, was used to yield an estimate of expected mortality probability at a given dosage. Secondly, bioassay 2 was conducted by simultaneously exposing six ≤4-day-old nymphal colonies to a shower of Z. anhuiensis conidia at each of four dosages (resulting from exposures of 0.3-8.0 min). Subsequently, the colonies were separately immersed in a 0.1% chlorothalonil solution for 0.5 min to disinfect all surviving conidia on the host integument from 1-12 h after exposure under temperature treatments of 15 and 20°C, respectively. The infection rate during a specific period from the end of the exposure to the immersion was then estimated as the ratio of the observed mortality over the expected mortality probability at a particular dosage. The results showed that the infection of M. persicae from Z. anhuiensis was highly rapid with little difference between aphid colonies maintained at 15 and 20°C before being immersed in the fungicidal solution after exposure. The first 6-hour period after exposure was most crucial to successful infection of the fungus with the infection rate greatly depending on conidial dosages. It took ≤1 h to infect>50% of the aphids at a dosage of >1.5 conida/mm2 and >90% at >50 conidia/mm2.
|
|
Responses of ABA and CTK to soil drought in leafless and leafy apple tree
LI Yan, PAN Hai-chun, LI De-quan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(1): 101-108.
https://doi.org/10.1631/jzus.2003.0101
The authors tested the contents of ABA (abscisic acid), ZR (zeatin riboside), DHZR (dihydrozeatin riboside) and iPA (isopentenyl adenosine) in leafless and leafy apple trees (Red Fuji/Malus micromalus Makino) during soil drought stress. ABA concentration in drought stressed leafless trees increased significantly compared to the controls. ABA both in roots and xylem rose steadily in the earlier drought stage, reaching a maximum of 1.46±0.35 nmol g-1FW and 117 nmol l-1 after the 8th day. Similar change patterns of ABA concentration was observed in the leafy trees during soil drought stress; ABA concentrations in roots and xylem sap increased and reached the maximum in the first three days; after 8th day, it decreased slightly, whereas leaf ABA concentration increased steadily in drought stressed plants throughout the duration of the experiment. Between drought stressed and control trees, no significant differences were observed in concentration of ZR and DHZR in both leafless and leafy trees; whereas iPA concentration of the drought stressed leafless and leafy plants decreased markedly in the later stage of drought. These results showed that endogenous ABA originated mainly from the roots in the earlier drought stage, and mainly from the leaves in the later drought stage. Total CTK showed no reduction in the earlier drought stage and decreased in the later drought stage.
|
|
Study on the effect of doxorubicin on expressions of genes encoding myocardial sarcoplasmic reticulum Ca2+ transport proteins and the effect of taurine on myocardial protection in rabbits
HUANG Xian-mei, ZHU Wei-hua, KANG Man-li
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2003, 4(1): 114-120.
https://doi.org/10.1631/jzus.2003.0114
To investigate the effect of doxorubicin (DOX) on gene expression of the myocardial sarcoplasmic reticulum (SR) Ca2+ transport proteins and the mechanism of taurine (Tau) protecting cardiac muscle cells, 9 rabbits were injected with DOX, 8 rabbits with DOX and Tau, and 9 rabbits with normal saline. Cardiac function, concentration of calcium in cardiomyocytes (Myo[Ca2+]i), activity of SR Ca2+-ATPase(SERCA2a), level of SERCA2a mRNA and Ca2+ released channels(RYR2)mRNA were detected. The left ventricle tissues were observed by electron microscopy. The results showed that cardiac index, left ventricular systolic pressure, activity of SR Ca2+-ATPase and level of SERCA2a mRNA decreased, while Myo[Ca2+]i increased in DOX-treated rabbits. DOX could not affect the level of RYR2 mRNA. Tau intervention could alleviate the increase of left ventricular diastolic pressure, Myo[Ca2+]i and the decrease of SERCA2a mRNA induced by doxorubicin. The results suggested that downregulation of SERCA2a gene expression was an important mechanism of DOX-induced cardiomyopathy and that Tau could partially improve the heart function by reducing calcium overload and alleviating downregulation of SERCA2a mRNA.
|
19 articles
|