The effect of toxic sulfide exposure on oxygen consumption and oxidation products in Urechis unicinctus (Echiura: Urechidae)

To investigate sulfide detoxification in Urechis unicinctus,oxygen consumption rate and sulfide detoxification productswere analyzed during sulfide exposure under controlled laboratory conditions.The results showed that oxygen consumption rateswere elevated significantly during 3 h sulfide exposure compared to the control(P0.05).The concentration of sulfite in body walland hindgut of experimental worms increased significantly(P0.05)when exposed to 50μmolL-1sulfide,reached a maximum at24 h and then decreased.Similar result was observed in worms exposed to 150μmolL-1sulfide except that sulfite concentrationreached a maximum at 12 h.Contents of thiosulfate in body wall and hindgut of U.unicinctus exposed to sulfide were also significantly higher than that of the control without sulfide exposure.In conclusion,during short-time sulfide exposure U.unicinctus mayraise oxygen consumption to detoxify toxic sulfide into sulfite and thiosulfate.Sulfide detoxification was restrained when the expo-sure time was prolonged or sulfide concentration was increased,which was indicated by decrease of sulfite,the intermediate productof sulfide detoxification.     

Determination of Ca,K, Mg and Fe in four fish species by FAAS

A method for determining calcium(Ca),potassium(K),magnesium(Mg) and iron(Fe) in four fish species was optimized and validated.It included microwave mineralization of the samples and subsequent quantification by flame atomic absorption spectroscopy(FAAS) with Zeeman-effect background correction.Using HNO3(65%) and H2O2(33%) as extraction solutions,the optimal conditions of extraction were established as follows:0.5 g of sample mass;microwave time program of 300 W/5 min and 600 W/5 min.The method was free of matrix interferences.The linear correlation coefficients were ≥0.9991,the recovery percentage of analytes was from 99.31% to 103.70% and the RSD(relative standard deviation) was lower than 2.06%.The detection limits obtained were 32.3,43.2,14.0 and 68.6 ng mL-1 for Ca,K,Mg and Fe in FAAS respectively.It is shown that the method is rapid,simple,sensitive and accurate.The method was applied to the studies of digestibility and measurement of these nutrients in samples of fish collected from Norway,Japan and China.     

Initiation and development of water film by seepage

When water seeps upwards through a saturated soil layer,the soil layer may become instability and water films occur and develop.Water film serves as a natural sliding surface because of its very small friction.Accordingly,debris flow may happen.To investigate this phenomenon,a pseudothree-phase media is presented first.Then discontinuity method is used to analyze the expansion velocity of water film.Finally,perturbation method is used to analyze the case that a water flow is forced to seep upwards through the soil layer while the movement of the skeleton may be neglected relative to that of water.The theoretical evolutions of pore pressure gradient,effective stress,water velocity,the porosity and the eroded fine grains are obtained.It can be seen clearly that with the erosion and redeposited of fine grains,permeability at some positions in the soil layer becomes smaller and smaller and,the pore pressure gradient becomes bigger and bigger,while the effective stress becomes smaller and smaller.When the effective stress equals zero,e.f.liquefaction,the water film occurs.It is shown also that once a water film occurs,it will be expanded in a speed of U(t)(1-ε).     

Characteristic rainfall for warning of debris flows

A characteristic rainfall is introduced to overcome the difficulties encountered in determining a critical rainfall value for triggering debris flow.The characteristic value is defined as the rainfall at which debris-flow occurrence probability shows a rapid increase,and can be used as a warning rainfall threshold for debris flows.Investigation of recorded debris flows and 24-hour rainfall data at Jiangjia basin,Yunnan Province,in southwestern China,demonstrates the existence of such a characteristic rainfa...     

牡丹江地震台实时在线设备全程监视系统的设计

"十五"期间,牡丹江地震台新增形变、火山测震台网等观测项目,观测数据通过多次中转传回牡丹江地震台.自2007年投入运行以来,多次出现数据断记问题,为减少断记,地震台站优化了观测系统,安装了实时监控软件,系统改进后,断记时间减少.     

Ground motion attenuation of M_s8.0 Wenchuan earthquake

The great MS8.0 Wenchuan earthquake has been the most destructive earthquake since 1949 in China. The earthquake occurred no more than half a year after the establishment of the National Strong Motion Observation Network System (NSMONS) of China; what is more, the epicenter was located in the area with dense strong motion observation stations so that a large number of strong motion records of the main shock were obtained. In this paper, 501 strong motion records from 167 observation stations are utilized to...     

利用SBAS-DInSAR技术提取腾冲火山区形变时间序列

基于6景JERS-1 L波段SAR影像,利用小基线集-合成孔径雷达干涉测量技术,通过线性形变相位、非线性形变相位、大气延迟相位以及地形残差相位的分离,提取了腾冲火山地区1995—1997年间地表形变时间序列（雷达视线向）,与2003—2004年的GPS观测结果对比表明,SBAS-DInSAR技术提取地壳形变的精度可达亚厘米级。时间序列形变显示胆札-高田断裂两侧形变差异性显著,可能与其下方存在的地壳岩浆囊的活动有关。打鹰山地区地表形变揭示其下方可能存在隐伏断裂。     

水温传感器放置深度研究现状

通过调研井孔水温传感器放置情况及水温观测现状和效果,剖析了在井水温度观测中存在的问题,尤其是水温传感器放置条件(深度)对观测效果的影响问题,就水温传感器的最佳放置条件,综述近年相关研究进展,包括水温微动态特征的影响因素和成因机制的研究。     

Shaking table test and numerical simulation of a 1/2‐scale self‐centering reinforced concrete frame

Self‐centering reinforced concrete frames are developed as an alternative of traditional seismic force‐resisting systems with better seismic performance and re‐centering capability. This paper presents an experimental and computational study on the seismic performance of self‐centering reinforced concrete frames. A 1/2‐scale model of a two‐story self‐centering reinforced concrete frame model was designed and tested on the shaking table in State Key Laboratory of Disaster Reduction in Civil Engineering at Tongji University to evaluate the seismic behavior of the structure. A structural analysis model, including detailed modeling of beam–column joints, column–base joints, and prestressed tendons, was constructed in the nonlinear dynamic modeling software OpenSEES. Agreements between test results and numerical solutions indicate that the designed reinforced concrete frame has satisfactory seismic performance and self‐centering capacity subjected to earthquakes; the self‐centering structures can undergo large rocking with minor residual displacement after the earthquake excitations; the proposed analysis procedure can be applied in simulating the seismic performance of self‐centering reinforced concrete frames. To achieve a more comprehensive evaluation on the performance of self‐centering structures, research on energy dissipation devices in the system is expected. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental analysis on the impact force of viscous debris flow

A miniaturized flume experiment was carried out to measure impact forces of viscous debris flow. The flow depth (7.2–11.2 cm), velocity (2.4–5.2 m/s) and impact force were recorded during the experiment. The impact process of debris flow can be divided into three phases by analyzing the variation of impact signals and flow regime. The three phases are the sudden strong impact of the debris flow head, continuous dynamic pressure of the body and slight static pressure of the tail. The variation of impact process is consistent with the change in the flow regime. The head has strong–rapid impact pressure, which is shown as a turbulent‐type flow; the body approximates to steady laminar flow. Accordingly, the process of debris flows hitting structures was simplified to a triangle shape, ignoring the pressure of the tail. In order to study the distribution of the debris flow impact force at different depths and variation of the impact process over time, the impact signals of slurry and coarse particles were separated from the original signals using wavelet analysis. The slurry's dynamic pressure signal appears to be a smooth curve, and the peak pressure is 12–34 kPa when the debris flow head hits the sensors, which is about 1.54 ± 0.36 times the continuous dynamic pressure of the debris flow body. The limit of application of the empirical parameter α in the hydraulic formula was also noted. We introduced the power function relationship of α and the Froude number of debris flows, and proposed a universal model for calculating dynamic pressure. The impact pressure of large particles has the characteristic of randomness. The mean frequency of large particles impacting the sensor is 210 ± 50–287 ± 29 times per second, and it is 336 ± 114–490 ± 69 times per second for the debris flow head, which is greater than that in the debris flow body. Peak impact pressure of particles at different flow depths is 40–160 kPa, which is 3.2 ± 1.5 times the impact pressure of the slurry at the bottom of the flow, 3.1 ± 0.9 times the flow in the middle, and 3.3 ± 0.9 times the flow at the surface. The differences in impact frequency indicate that most of the large particles concentrate in the debris flow head, and the number of particles in the debris flow head increases with height. This research supports the study of solid–liquid two phase flow mechanisms, and helps engineering design and risk assessment in debris flow prone areas. Copyright © 2015 John Wiley & Sons, Ltd.