The use of desorbing agents in electrodialytic remediation of harbour sediment

Electrodialytic removal of Cu, Zn, Pb and Cd from contaminated harbour sediment was made with the emphasis of testing the effectiveness of different desorbing agents: HCl, NaCl, citric acid, lactic acid, ammonium citrate and distilled water. Extraction experiments with the desorbing agents were made prior to the electrodialytic experiments. The extractions showed that HCl was most efficient for metal desorption, probably due to the low pH and complexation with chloride. The metals were not extracted by distilled water. However, in the electrodialytic experiments, the removal was high when using distilled water and the desorbing agents did generally not enhance the heavy metal removal compared to distilled water. The only exception was with lactic acid, where the Cu removal was 20% higher compared to the other desorbing agents. The removal was 48% Cu, 80% Zn, 96% Pb and 98% Cd, when using distilled water. Metal speciation with the different desorbing agents was simulated with the geochemical model Visual MINTEQ version 2.15. Variations in the Cl concentration were found to be of crucial importance since it influences the formation of metal chlorocomplexes, especially uncharged species. All the acidic desorbing agents were predicted to form mostly cationic species, which was in agreement with the removal direction in the electrodialytic remediation experiments.     

Wind loads on attached canopies and their effect on the pressure distribution over arch-roof industrial buildings

Arch-roof industrial buildings are very wind sensitive. The current aerodynamic coefficients in wind codes do not contemplate the possibility of existence of canopies attached to the buildings. This paper presents the results of an investigation on the influence exerted by canopies on the static wind actions on arch-roof industrial buildings. Six scale models of these arch-roof buildings were tested, with five types of canopies attached. Three of these canopies were instrumented and the static wind pressures were measured. The tests were done at the boundary layer wind tunnel of the Universidade Federal do Rio Grande do Sul. The results show that the aerodynamic coefficients for the roof are not affected by the canopies, in the case of axial incidence. However, the influence on the pressure distribution is noticeable for wind incidence perpendicular to the main axis of the arch roofs and for other incidences as well. This influence is discussed in the paper. The aerodynamic coefficients for the design of the arch-roofs, with and without the attached canopies are given. Aerodynamic coefficients for design of the canopies are also suggested. Furthermore, the paper discusses the relation between the magnitude of the canopy design forces and the canopy width, as well as the relation between the canopy height location and the height of the building wall. The results were compared with design recommendations from previous work of Jancauskas and Holmes (in: US National Conference on Wind Engineering, Proceedings, Texas Tech University, Lubbock, 1985) and Jancauskas and Eddleston (in: International Conference on Wind Engineering, Fotodruck J. Mainz, Aachen, 1987).     

The centralization index: A measure of local spatial segregation

Segregated areas may occur around an attractive park or a waste incinerator, but the magnitude and group membership of the people in closest proximity will likely be difierent. We therefore introduce a local segregation measure that can be applied to any location within a metropolitan area, and that can identify the group that is relatively more concentrated around that reference location. We further introduce an inference approach to identify the statistical significance of a particular segregation value. In an exploratory setting the index can be used to generate a map of hot spots, and seed the question: “why is this group significantly concentrated around that location?”     

ESMRMB 2017, 34th Annual Scientific Meeting,Barcelona, ES,October 19–October 21: Abstracts,Thursday

Objective

Current magnetic resonance imaging (MRI) axon diameter measurements rely on the pulsed gradient spin-echo sequence, which is unable to provide diffusion times short enough to measure small axon diameters. This study combines the AxCaliber axon diameter fitting method with data generated from Monte Carlo simulations of oscillating gradient spin-echo sequences (OGSE) to infer micron-sized axon diameters, in order to determine the feasibility of using MRI to infer smaller axon diameters in brain tissue.

Materials and methods

Monte Carlo computer simulation data were synthesized from tissue geometries of cylinders of different diameters using a range of gradient frequencies in the cosine OGSE sequence . Data were fitted to the AxCaliber method modified to allow the new pulse sequence. Intra- and extra-axonal water were studied separately and together.

Results

The simulations revealed the extra-axonal model to be problematic. Rather than change the model, we found that restricting the range of gradient frequencies such that the measured apparent diffusion coefficient was constant over that range resulted in more accurate fitted diameters. Thus a careful selection of frequency ranges is needed for the AxCaliber method to correctly model extra-axonal water, or adaptations to the method are needed. This restriction helped reduce the necessary gradient strengths for measurements that could be performed with parameters feasible for a Bruker BG6 gradient set. For these experiments, the simulations inferred diameters as small as 0.5 μm on square-packed and randomly packed cylinders. The accuracy of the inferred diameters was found to be dependent on the signal-to-noise ratio (SNR), with smaller diameters more affected by noise, although all diameter distributions were distinguishable from one another for all SNRs tested.

Conclusion

The results of this study indicate the feasibility of using MRI with OGSE on preclinical scanners to infer small axon diameters.

     

Knowledge formation and learning in the management of projects: A problem solving perspective

In contrast to traditional projects, which are assumed to be fully specified and then executed with little learning anticipated, complex projects cannot be fully specified at the outset and require continuous learning over their life cycles. Nevertheless, the key role of knowledge formation and learning in managing complex projects is under-developed for expanding project capability boundaries to include knowledge uncertainty and indeterminacy.     

The Effects of Annealing After Equal Channel Angular Extrusion (ECAE) on Mechanical and Magnetic Properties of 49Fe-49Co-2V Alloy

Metallurgical and Materials Transactions A - Equal channel angular extrusion (ECAE) of 49Fe-49Co-2V, also known as Hiperco® 50A or Permendur-2V, greatly improves the strength and ductility of...     

Substrate Stimulated Orientation for Pure Aluminum

Oriented materials are of great importance, but their formation is rarely described. Here, nine Al/Al₂O₃ systems were designed to identify the dominant factors. Electron back-scattered diffraction indicates that the new Al crystal(s) with one or multiple orientation(s) can be stimulated by one single-crystal Al₂O₃ substrates. Synchrotron radiation diffraction shows that the preferred orientation(s) is/are determined based on the initial stage of the liquid–solid transition. The nonpreferred orientation can be suppressed through competition.

     

OPTIMAL MAINTENANCE SCHEDULING FOR WATER DISTRIBUTION SYSTEMS

The scheduling of maintenance for water distribution systems is a complex task encompassing a wide range of alternatives. The methodology presented in this paper can consider the major piping alternatives of replacing and cleaning, and relining. It also considers the potential of pumping improvements while accounting for the costs of maintenance, failure and operations for a multiple-period planning horizon. To solve the problem a nonlinear optimization model is linked with a network simulation model. The application showed that the procedure can determine solutions in reasonable times.     

Effect of dietary and synthetic chelating agents on the intestinal absorption of lead

The effect of a number of dietary and synthetic chelating agents on the intestinal absorption of lead has been examined using the everted sac preparation and the tracer isotope ²⁰³Pb. All the agents examined increased lead transport into the serosal compartment. An explanation of the way in which these agents modify the model to describe lead transport is proposed.     

Forest fires in cork oak (Quercus suber L.) stands in Portugal

Fire and cork can be considered both the most serious problem and the most valuable resource of Portuguese forests. The existence of important areas of burned cork oak stands resulting from severe fire seasons in recent years is an environmental problem which deserves special attention. This paper makes a multidisciplinary survey of the problem of burned cork oak stands focusing on: the dimensions of the problem in Portugal, the remarkable resistance of cork oak to fire, the post‐fire management of cork oak stands, and the economic and ecological effects of fire in cork oak stands. Particular emphasis is given to knowledge gaps in this context.