A modified permeameter for determination of unsaturated coefficient of permeability

The design details of a modified permeameter used for determining the unsaturated coefficient of permeability of tailings are presented in this Paper. This permeameter can accommodate a large tailings specimen, 200 × 200 × 400 mm high, and uses the Instantaneous Profile Method (IPM) to determine the variation of unsaturated coefficient of permeability with respect to soil suction using a single specimen. The soil-water characteristic curve data can also be simultaneously determined from the modified permeameter. The key design features in comparison to a conventional permeameter include the provision of adjustable sensors that move along with the tailings as it settles due to desaturation during the testing period. The advantages of using a modified permeameter in the determination of the coefficient of permeability of unsaturated tailings are also discussed in this paper. Tests were carried out by providing suction using hanging column technique in the suction range of 0–10 kPa. Such an apparatus can easily be modified to accommodate higher suction values.     

A class of inhomogeneous shear models for seismic analysis of landfills

An analytical/numerical procedure is developed to calculate the shear elasto-plastic earthquake response of hill-shaped landfills. Landfill response is evaluated on the basis of newly developed one-dimensional inhomogeneous shear beam models. In these models, the nonhomogeneity of landfill materials is taken into account by assuming a specific variation of stiffness properties along the depth. Closed-form analytical expressions are derived for natural frequencies, modal displacements, modal participation factors, absolute accelerations and maximum shear strains. Parametric results are presented in graphical and tabular form and conclusions are drawn. Within a numerical implementation framework of the above formulation, the landfill materials may be modeled by an elasto-plastic hysteretic model following the principles of flow or incremental plasticity. The entire numerical procedure may be executed on a personal computer and consequently qualifies as a versatile tool for conducting preliminary design calculations or parametric-type investigations. Using this newly developed procedure, the seismic response of the Fresh Kills landfill in New York City is investigated.     

Surface Boundary-Layer Characteristics Over a Tropical Inland Station: Seasonal Features

Some characteristic features of the atmospheric surfacelayer over an inland tropical station, Lucknow (27°N, 81°E)in India, are investigated for different seasons using micrometeorological data collected at the 10-m levelof an instrumented tower. Seasonal monsoonal variations in wind circulation (north-easterliesand south-westerlies) dominate the flow over this part of the region. This study utilizesthe wind, temperature and humidity data obtained for a period of one year from February 1996 to January 1997. The diurnal variation of mean parameterssuch as temperature, relative humidity, and wind speed are studied for different seasonsnamely pre-, south-west, post- and north-east monsoon periods. Turbulent statistics are computedusing the eddy correlation technique, and are studied under the framework of Monin–Obukhov similarity theory with results compared with otherexperimental studies reported in the literature. It is found that the turbulence statistics arenearly independent of season and the near-neutral values of the normalized standard deviations ofthe three wind components, temperature and specific humidityare found to be 1.00 ± 0.04 (vertical), 2.63 ± 0.36(longitudinal), 2.19 ± 0.06 (lateral), 6.56 ± 0.33and 6.45 ± 0.33 respectively.     

On the recurvature of tropical cyclones and the storm surge problem in Bangladesh

The disproportionality of the large frequency of occurrence of severe storm surges on the coast of Bangladesh is highlighted. The reasons for the recurvature of these storms towards the Bangladesh coast and the associated severe surges are discussed in this paper.Atmospheric Environment Service, Ice Center, Environment Canada, 373 Sussex Drive, Ottawa, Ontario, Canada K1A 0H3.     

Urban floods in Hyderabad,India, under present and future rainfall scenarios: a case study

Natural Hazards - This study assesses and evaluates the impacts of future extreme rainfall event(s) on conveyance capacity of urban Storm Water Network (SWN) of Hyderabad City, India, along with...     

3种蛋白源替代鱼粉对褐点石斑鱼幼鱼血液指标的影响

以全鱼粉饲料为对照(D1组),用豆粕替代10%、20%的鱼粉(D2、D3组),玉米蛋白粉替代10%的鱼粉(D4组),啤酒酵母替代10%的鱼粉(D5组),配制5组等氮等能饲料,研究不同蛋白源替代饲料中的鱼粉对褐点石斑鱼(Epinephelus fuscoguttatus)幼鱼血液生理生化指标的影响.结果发现:投喂56 d后,D5组终末体质量显著小于D1组和D2组(p<0.05),其他各组间差异不显著(p>0.05);D1组和D2组实验鱼体质量与D5组差异显著(p<0.05).D3组血红蛋白浓度、血栓细胞密度和平均血栓细胞体积显著低于D1组(p<0.05), D4组实验鱼嗜中性粒细胞密度和巨大不成熟细胞比例显著高于D1组(p<0.05).D3组实验鱼总蛋白含量显著低于D1、D4组(p<0.05),D3组球蛋白含量显著低于D1组(p<0.05),D3组白球蛋白比显著高于其他各组(p<0.05);D3组的血糖含量显著低于D1组(p<0.05),D2、D3、D5组的甘油三酯含量显著低于D1、D4组(p<0.05);D5组肌酐含量显著低于D1组(p<0.05).以上结果表明,酵母蛋白替代饲料中10%的鱼粉对实验鱼的生长和生理状态均产生不良影响,不适于作为褐点石斑鱼幼鱼饲料的鱼粉替代物;玉米蛋白粉和豆粕蛋白可以作为褐点石斑鱼幼鱼饲料中鱼粉的替代物,但替代比例玉米蛋白粉不宜超过10%,而豆粕蛋白的替代比例应小于20%.     

Coupled horizontal–vertical stability of bearings under dynamic loading

In this study, the coupled horizontal–vertical behavior of elastomeric bearings subjected to dynamic loading is studied in detail. Under extreme dynamic loading, elastomeric bearings exhibit unstable behavior and an instantaneous loss of horizontal stiffness that is recoverable. Building on an earlier study where the authors developed an analytical model for the horizontal behavior of bearings under dynamic loads, in this study, a new analytical model for the coupled horizontal–vertical behavior of the bearings is developed. The coupled behavior of the bearing is first studied for quasi‐static loading, and later, the behavior of the bearings under dynamic loading is studied. A clear distinction is made between different types of deformation the bearing undergoes in the vertical direction. Based on experimental results, it is observed that the behavior of the bearings under dynamic loading differs markedly from that observed under static loading. A new analytical model is proposed that can account for the coupled horizontal–vertical behavior of the bearings under dynamic loading. The proposed analytical model for predicting the post‐stability vertical behavior of the bearings is verified using experimental results. The model proposed is found to successfully predict the coupled horizontal–vertical behavior of elastomeric bearings. Copyright © 2015 John Wiley & Sons, Ltd.     

Kaolinite – alkali interaction and effects on basic properties

The influence of type and amount of clays present in soils on their properties is well understood. The clays exert their influence through large specific surface area and charges on them. Their effect is mostly exhibited through inter particle bonding and subsequent particle associations. The mineralogical influence of soils in water is well documented. However, the change in soil water system because of presence some of the contaminants can greatly influence the soil behaviour. Some of the changes are due to formation of new compounds due to interactions between the soil and pollutant. The paper reports the effect of interaction of kaolinite mineral with alkali on the index properties of soils from which the geotechnical behaviour can be understood. Detailed X-ray diffraction studies have shown that sodium aluminum silicate hydroxide hydrate (NASH) is formed by clay alkali reactions. The type and amount of formation of the compound is influenced by the concentration of alkali solution. While the compound formed is in smaller quantities with 1 N NaOH solution, significantly high quantity is formed with 4 N NaOH solution. Presence of alumina is shown to play a significant role. It was observed that the formation of sodium aluminum silicate hydroxide hydrate is reduced in the presence of alumina. Specific gravity of contaminated clay soil was reduced which confirms the formation of new compounds. Water adsorption and specific surface area of soil are also influenced due to soil alkali interaction. The changes in the free swell and index properties of soil in the presence of alkali have been explained by the changes in soil fabric and the formation of new compound.     

Development of a Label-Free Colorimetric Aptasensor with Rationally Utilized Aptamer for Rapid Detection of Okadaic Acid

Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis.In this study,a label-free col-orimetric aptasensor was constructed for visual and rapid detection of OA in shellfish.To exploit the binding capability of the anti-OA aptamer,the inherent molecular recognition mechanism of aptamer and OA was studied,based on molecular docking,fluorescent assay,and biolayer interferometry.Consistent results showed that the stem-loop near the 3’terminal of the aptamer exhibit dominate binding capacity.Based on the revealed recognition information,the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride(PDDA)for the development of the label-free colorimetric aptasensor,in which the 3’terminal was thoroughly exposed to OA.The aptasensor provided robust performance with a linear detection range of 100-1200 nmol L-1,a limit of detection of 41.30 nmol L-1,recovery rates of 91.6%-106.2%,as well as a high selectivity towards OA in shellfish samples.The whole detection process can be completed within 1 h.To our best knowledge,this is the first time that the anti-OA aptamer was thoroughly studied,and a label-free colorimetric aptasensor was rationally designed in this way.This study not only provides a rapid detection method for highly sensitive and specific detection of OA,but also serves as a reference for the design of efficient aptasensors in the future.