THM analysis of a large‐scale heating test incorporating material fabric changes

Engineered barriers are basic elements in the design of repositories for the isolation of high‐level radioactive waste. This paper presents the thermo‐hydro‐mechanical (THM) analysis of a clay barrier subjected to heating and hydration. The study focuses on an ongoing large‐scale heating test, at almost full scale, which is being carried out at the CIEMAT laboratory under well‐controlled boundary conditions. The test is intensely instrumented and it has provided the opportunity to study in detail the evolution of the main THM variables over a long period of time. Comprehensive laboratory tests carried out in the context of the FEBEX and NF‐PRO projects have allowed the identification of the model parameters to describe the THM behaviour of the compacted expansive clay. A conventional THM approach that assumes the swelling clay as a single porosity medium has been initially adopted to analyse the evolution of the test. The model was able to predict correctly the global THM behaviour of the clay barrier in the short term (i.e. for times shorter than three years), but some model limitations were detected concerning the prediction of the long‐term hydration rate. An additional analysis of the test has been carried out using a double structure model to describe the actual behaviour of expansive clays. The double structure model explicitly considers the two dominant pore levels that actually exist in the FEBEX bentonite and it is able to account for the evolution of the material fabric. The simulation of the experiment using this enhanced model provides a more satisfactory reproduction of the long‐term experimental results. It also contributes to a better understanding of the observed test behaviour and it provides a physically based explanation for the very slow hydration of the barrier. Copyright © 2011 John Wiley & Sons, Ltd.     

Esterase activities and lipid peroxidation levels in offshore commercial species of the NW Mediterranean Sea

There is a lack of information on monitoring neurotoxicity in offshore commercial species. To help fill this gap, we sampled hake (Merluccius merluccius) and Norway lobster (Nephrops norvegicus) in fishing grounds off the coast of l’Ametlla de Mar (NW Mediterranean) in June 2005 at a depth of 100 m and 400 m. Additionally, at 400 m depth, two other fish species, Micromesistius poutassou and Phycis blennoides were included. Neurotoxicity markers such as Colinesterases (ChEs), namely acethyl- (AChE), butyryl- (BChE), propionyl- (PrChE) and carboxilesterase (CbE) were measured in muscle. Lipid peroxidation (LP), a marker of oxidative damage, was also included. The results are discussed in relation to the animal’s sex, size and fishing depth. A comparison of esterases and LP levels between muscle and liver of hake and between muscle and hepatopancreas of Norway Lobster was made.

AChE was dominant in muscle and CbE in hepatopancreas. No differences between fish species were seen for AChE. However, N. norvegicus, presented lower levels of ChEs and LP. A size-dependence in ChEs was seen for M. merluccius, with larger animals showing significantly lower activities (p < 0.05). Sex-dependence was seen in N. norvegicus for most esterases, except AChE, with males displaying higher activities (p < 0.05). A sampling-depth effect was also seen in the crustacea, with animals from 100 m generally presenting lower esterase activities and higher LP levels.     

A Hubble Space Telescope/NICMOS view of the prototypical giant Hii region NGC604 in M33

We present the first high-spatial-resolution near-infrared (NIR) imaging of NGC604, obtained with the NICMOS camera onboard the Hubble Space Telescope (HST). These NICMOS broad-band images reveal new NIR point sources, clusters, and diffuse structures. We find an excellent spatial correlation between the 8.4 GHz radio continuum and the 2.2 μm nebular emission. Moreover, massive young stellar object candidates appear aligned with these radio peaks, reinforcing the idea that those areas are star-forming regions. Three different scaled OB associations are recognized in the NICMOS images. The brightest NIR sources in our images have properties that suggest that they are red supergiant stars, of which one was previously known. This preliminary analysis of the NICMOS images shows the complexity of the stellar content of the NGC604 nebula.     

Stochastic evaluation of the impact of sewer inlets’ hydraulic capacity on urban pluvial flooding

Sewer inlet structures are vital components of urban drainage systems and their operational conditions can largely affect the overall performance of the system. However, their hydraulic behaviour and the way in which it is affected by clogging is often overlooked in urban drainage models, thus leading to misrepresentation of system performance and, in particular, of flooding occurrence. In the present paper, a novel methodology is proposed to stochastically model stormwater urban drainage systems, taking the impact of sewer inlet operational conditions (e.g. clogging due to debris accumulation) on urban pluvial flooding into account. The proposed methodology comprises three main steps: (i) identification of sewer inlets most prone to clogging based upon a spatial analysis of their proximity to trees and evaluation of sewer inlet locations; (ii) Monte Carlo simulation of the capacity of inlets prone to clogging and subsequent simulation of flooding for each sewer inlet capacity scenario, and (iii) delineation of stochastic flood hazard maps. The proposed methodology was demonstrated using as case study design storms as well as two real storm events observed in the city of Coimbra (Portugal), which reportedly led to flooding in different areas of the catchment. The results show that sewer inlet capacity can indeed have a large impact on the occurrence of urban pluvial flooding and that it is essential to account for variations in sewer inlet capacity in urban drainage models. Overall, the stochastic methodology proposed in this study constitutes a useful tool for dealing with uncertainties in sewer inlet operational conditions and, as compared to more traditional deterministic approaches, it allows a more comprehensive assessment of urban pluvial flood hazard, which in turn enables better-informed flood risk assessment and management decisions.     

西班牙南部Subbetic中带Río Fardes剖面Turonian-Coniacian大洋红层

Río Fardes剖面位于西班牙南部Granada东北,构造上属于深水环境的Subbetic中带。该剖面主要由白垩纪Fardes组第Ⅱ段和第Ⅲ段(半)远洋沉积构成,并出现浊流沉积和混杂沉积。本次研究在Fardes组浊流层序内首次发现两段红色沉积。钙质超微化石表明红层的时间从Turonian早期(UC7 带)到Coniacian中期—晚期界线(UC10/?UC11带)。红层由mm级红色泥岩夹灰色、杂色、偶尔黑色泥岩和钙质泥岩组成。沉积学研究表明新发现的Turonian Coniacian远洋红色泥岩沉积形成于CCD面之下深水盆地环境,浊流和碎屑流沉积强烈地影响着(半)远洋环境的背景泥岩相,并成为红色沉积结束的原因。     

Light requirements of the seagrass,Zostera muelleri,determined by observations at the maximum depth limit in a temperate estuary,New Zealand

The Kaipara Harbour in New Zealand is one of the largest estuarine systems in the world, containing significant areas of subtidal seagrass habitat (Zostera muelleri). Light availability at the maximum depth limit for Z. muelleri was measured at 2.10 (0.19 SEM) and 4.91 (0.53 SEM) mol photons m^?2 d^?1 during the winter and summer monitoring periods, respectively. The primary drivers of benthic light availability were found to be surface light availability, the timing of the low tide and water clarity. Core sampling analysis suggested that biomass of seagrass growing at the maximum depth limit was low, indicative of light limitation. The results of this study suggest that the subtidal distribution of seagrass in the Kaipara Harbour is light-limited and that reductions in water clarity due to changes in land use are likely to result in significant reductions in the extent and productivity of subtidal seagrass habitat.     

Nonlinear convection in an imposed horizontal magnetic field

Abstract

Nonlinear two-dimensional magnetoconvection, with a Boussinesq fluid driven across the field-lines, is taken as a model for giant-cell convection in the sun and late-type stars. A series of numerical experiments shows the sensitivity of the horizontal scale of convection to the applied field and to the Rayleigh number R. Overstable oscillations occur in cells as broad as they are deep, but increasing R leads to steady motions of much greater wavelength. Purely geometrical effects can cause oscillation: this work implies that strong horizontal field will in general lead to time-dependent convection.     

Concentration of Ciprofloxacin in Brazilian Hospital Effluent and Preliminary Risk Assessment: A Case Study

This study was carried out to evaluate the occurrence of the fluoroquinolone antimicrobial agent ciprofloxacin (CIP) in the effluent of the Hospital of the Federal University of Santa Maria (HUSM). Measured environmental concentrations (MECs) of CIP in the hospital wastewater, both before (P1) and after (P2) cesspit/filter system treatment (CFTS), were determined by means of solid phase extraction and reversed‐phase liquid chromatography with fluorescence detection (LC‐FLD) and reversed‐phase liquid chromatography with mass spectrometric detection (LC‐MS/MS). The MECs (n = 7 daily composed samples) were 19 to 155 μg L^–1 (average: 54 ± 21 μg L^–1) and 32 to 99 μg L^–1 (average: 65 ± 45 μg L^–1) in P1 and P2, respectively. No relevant removal was observed from P1 to P2. In a worst case scenario, the final effluent was regarded as MECs of surface water. These MECs were generally 5 to 20,000‐fold higher than what was previously known. If the present data is drawn on to form a model of the situation in developing countries, the picture provides a first rough indication that the environmental risk associated with the use and emission of pharmaceuticals into the environment in developing countries might be higher than in developed countries.