Enhanced phytoextraction of uranium and selected heavy metals by Indian mustard and ryegrass using biodegradable soil amendments

The applicability of biodegradable amendments in phytoremediation to increase the uptake of uranium (U), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn) by Indian mustard (Brassica juncea) and ryegrass (Lolium perenne) was tested in a greenhouse experiment. Plants were cultivated during one month on two soils with naturally or industrially increased contaminant levels of U. Treatments with citric acid, NH₄-citrate/citric acid, oxalic acid, S,S-ethylenediamine disuccinic acid (EDDS) or nitrilotriacetic acid (NTA) at a rate of 5 mmol kg^− 1 dry soil caused increases in soil solution concentrations that were up to 18 times higher for U and up to 1570 times higher for other heavy metals, compared to the controls. Shoot concentrations increased to a much smaller extent. With EDDS, 19-, 34-, and 37-fold increases were achieved in shoots of Indian mustard for U, Pb and Cu, respectively. The increases in plant uptake of Cd, Cr and Zn were limited to a factor of four at most. Ryegrass generally extracted less U and metals than Indian mustard. Despite a marked increase of U and metal concentrations in shoots after addition of amendments, the estimated time required to obtain an acceptable reduction in soil contaminant concentrations was impractically long. Only for Cu and Zn in one of the studied soils, could the Flemish standards for clean soil theoretically be attained in less than 100 years.     

A simple procedure for ground response curve of circular tunnel in elastic-strain softening rock masses

This paper presents a simple procedure for the ground response curve of a circular tunnel excavated in elastic-strain softening rock mass compatible with a linear Mohr–Coulomb or a nonlinear Hoek–Brown yield criterion. The numerical stepwise procedure proposed by Brown et al. [Brown, E.T., Bray, J.W., Ladanyi, B., Hoek, E., (1983). Ground response curves for rock tunnels. J. Geotech. Eng. ASCE 109, 15–39] is modified by including the effects of elastic strain increments and variable dilatancy within the plastic region. The accuracy and practical application of the proposed procedure are shown through some examples. Four different combinations of dilatancy angle and softening parameter are considered to investigate the effects of elastic strain increments and variable dilatancy within the plastic region. The effects of variable dilatancy and peak dilatancy angle on the ground response curve are investigated for tunnels in poor-to-good-quality rock masses. The results show the importance of correctly estimating peak dilatancy angle in elastic-perfectly plastic and elastic-strain softening Hoek–Brown media.     

Bayesian data analysis to quantify the uncertainty of intact rock strength

One of the main difficulties in the geotechnical design process lies in dealing with uncertainty. Uncertainty is associated with natural variation of properties, and the imprecision and unpredictability caused by insufficient information on parameters or models. Probabilistic methods are normally used to quantify uncertainty. However, the frequentist approach commonly used for this purpose has some drawbacks.First, it lacks a formal framework for incorporating knowledge not represented by data. Second, it has limitations in providing a proper measure of the confidence of parameters inferred from data. The Bayesian approach offers a better framework for treating uncertainty in geotechnical design. The advantages of the Bayesian approach for uncertainty quantification are highlighted in this paper with the Bayesian regression analysis of laboratory test data to infer the intact rock strength parameters σ_(ci) and m_i used in the Hoek-Brown strength criterion. Two case examples are used to illustrate different aspects of the Bayesian methodology and to contrast the approach with a frequentist approach represented by the nonlinear least squares(NLLS) method. The paper discusses the use of a Student's t-distribution versus a normal distribution to handle outliers, the consideration of absolute versus relative residuals, and the comparison of quality of fitting results based on standard errors and Bayes factors. Uncertainty quantification with confidence and prediction intervals of the frequentist approach is compared with that based on scatter plots and bands of fitted envelopes of the Bayesian approach. Finally, the Bayesian method is extended to consider two improvements of the fitting analysis. The first is the case in which the Hoek-Brown parameter, a, is treated as a variable to improve the fitting in the triaxial region. The second is the incorporation of the uncertainty in the estimation of the direct tensile strength from Brazilian test results within the overall evaluation of the intact rock strength.     

Blockarchitecture

Curation or selection offers up probably the greatest challenge for the contemporary architect. With the onslaught of information, the emphasis is now on what an architect chooses to respond to rather than what is available to him or her in terms of sources. Iain Borden discusses how Block Architecture's responsive position enables the firm to react with immediacy to its urban surroundings, while also resulting in highly attuned ‘architectures of suggestion and momentary thinking’. Copyright © 2005 John Wiley & Sons, Ltd.     

Metabolism and Morphology

Architecture is on the cusp of systemic change, driven by the dynamics of climate and economy, of new technologies and new means of production. There is a growing interest in the dynamics of fluidity, in networks and in the new topologies of surfaces and soft boundaries. This is part of a general cultural response to the contemporary reconfiguration of the concept of ‘nature’ within the discourse of architecture; a change from metaphor to model, from ‘nature’ as a source of formal inspiration to ‘nature’ as a mine of interrelated dynamic processes that are available for analysis and digital simulation. Michael Weinstock presents an account of the dynamics of natural metabolisms, and suggests an agenda for the development of metabolic morphologies of buildings and cities. Copyright © 2008 John Wiley & Sons, Ltd.     

Engineering geological mapping of heterogeneous rock masses in the Northern Apennines: an example from the Parma Valley (Italy)

Most of the geological formations in the Northern Apennines are made up of flysch and tectonic mélanges. A general characterization of the most common rock masses cropping out in the Val Parma is presented in this paper, using the Marinos–Hoek classification based on the Hoek–Brown criterion. Three groups were identified: heterogeneous rock masses essentially controlled by single discontinuities with strengths much lower than the main rock mass (HH); truly heterogeneous rock masses with approximately equal alternations of hard and weak horizons which fail through the weaker materials (TH) and a rock mass in which the majority of the material is weak, tending to soil-like behaviour (WH). A general engineering geological map of the study area is presented, highlighting the spatial distribution of the three different groups.     

Revisiting rock classification to estimate rock mass properties

This paper presents the results of ongoing research carried out by the author exploring methods to provide a more robust estimate of rock mass properties specifically for use in tunnel design. Data from various large-scale rock mass failures are introduced, including coal pillars. The damage-initiation,spalling-limit approach is compared to the coal pillar database. New comparisons of estimating the geological strength index(GSI) and relationships to estimate the Hoeke Brown failure criterion parameters, mb, s and a, are presented.     

Severe jaw enlargement associated with uremic hyperparathyroidism

Marked enlargement of the jaws is a rare complication of renal osteodystrophy. This report describes a localized enlargement of the mandible due to a brown tumor in a patient undergoing chronic hemodialysis. Literature on jaw involvement in secondary hyperparathyroidism is reviewed.     

Polarization and coherence in the Hanbury Brown–Twiss effect

We study the correlation of intensity fluctuations in random electromagnetic beams, the so-called Hanbury Brown–Twiss effect (HBT). We show that not just the state of coherence of the source, but also its state of polarization has a strong influence on the far-zone correlations. Different types of sources are found to have different upper bounds for the normalized HBT coefficient.