Toxic Chemical and their Neutralising Agents in Porous Media

The UK Government Decontamination Service advises central Govern- ment on the national capability for the decontamination of buildings, infrastructure, transport and open environment, and be a source of expertise in the event of a chemical, biological, radiological and nuclear (CBRN) incident or major release of HazMat materials. The study group constructed mathematical models to describe the depth to which a toxic chemical may seep into an initially dry porous substrate, and of the neutralisation process between a decontaminant and the imbibed chemical. The group recognised that capillary suction was the dominant process by which the contaminant spreads in the porous substrate. Therefore, in the first instance the absorption of the contaminant was modelled using Darcy’s law. At the next level of complication a diffuse interface model based on Richards’ equation was employed. The results of the two models were found to agree at early times, while at later times we found that the diffuse interface model predicted the more realistic scenario in which the contaminant has seeped deeper into the substrate even in the absence of further contaminant being supplied at the surface. The decontamination process was modelled in two cases; first, where the product of the decontamination reaction was water soluble, and the second where the reaction product formed soluble in the contaminant phase and of similar density. These simple models helped explain some of the key physics involved in the process, and how the decontamination process might be optimised. We found that decontamination was most effective in the first of these two cases. The group then sought to incorporate hydrodynamic effects into the reaction model. In the long wavelength limit, the governing equations reduced to a one-dimensional Stefan model similar to the one considered earlier. More detailed approximations and numerical simulations of this model were beyond the scope of this study group, but provide an entry point for future research in this area

Multiscale modeling of a rectifying bipolar nanopore : comparing Poisson-Nernst-Planck to Monte Carlo

In the framework of a multiscale modeling approach, we present a systematic study of a bipolar rectifying nanopore using a continuum and a particle simulation method. The common ground in the two methods is the application of the Nernst-Planck (NP) equation to compute ion transport in the framework of the implicit-water electrolyte model. The difference is that the Poisson-Boltzmann theory is used in the Poisson-Nernst-Planck (PNP) approach, while the Local Equilibrium Monte Carlo (LEMC) method is used in the particle simulation approach (NP+LEMC) to relate the concentration profile to the electrochemical potential profile. Since we consider a bipolar pore which is short and narrow, we perform simulations using two-dimensional PNP. In addition, results of a non-linear version of PNP that takes crowding of ions into account are shown. We observe that the mean field approximation applied in PNP is appropriate to reproduce the basic behavior of the bipolar nanopore (e.g., rectification) for varying parameters of the system (voltage, surface charge, electrolyte concentration, and pore radius). We present current data that characterize the nanopore’s behavior as a device, as well as concentration, electrical potential, and electrochemical potential profiles

The study of physicochemical properties of stabilizing plates removed from the body after treatment of pectus excavatum

This paper presents the results of a physicochemical surface study and clinical observation of a new generation of plates for the treatment of pectus excavatum. Analysis of the data allowed us to investigate the effect of implant design and condition of their surface on the results of treatment of pectus excavatum. In the study, we performed an analysis of clinical data, obtained after a suitable period of treatment with the use of implants, as well as a study of physicochemical properties of stabilizing plates after their removal from the body. Surface roughness, the surface wettability and corrosion resistance were measured, and the results were compared with clinical observations. When removing the plates we found only slight inflammatory-periosteal reactions around the wire fixing transverse stabilizing plates to the ribs and locking the base plate correcting the distortion. The corrective plates did not shift or rotate during the entire treatment period, giving an optimal, oval and natural shape of the chest. The obtained values of the parameters investigated indicate that the reduction in resistance to pitting corrosion occurred in the areas where laser marking was made to identify the plate. The remaining plates, in spite of mechanical damage of the surface, were characterized by good corrosion resistance, a fact which is confirmed by the results of clinical evaluation

Definition of optimal supply chains for reuse of building components derived from C&DW in the EU

Construction and demolition waste (C&DW) is one of the largest waste streams in the EU. A large proportion of C&DW has the potential to be reused or recycled within the construction sector thus contribution to saving natural resources and energy. The Directive 2008/98/EC on Waste, states that by 2020 the material recovery of non-hazardous C&DW shall be increased to a minimum of 70% by weight. To reach this aim, innovative reuse and recycling strategies are needed. In this context, a study was conducted within the IRCOW-project related to reuse. Reuse is defined in directive 2008/98/EC article 3 §13 as any operation by which products or components that are not waste are used again for the same purpose for which they were conceived. The study about C&D materials’ (C&DM1) reuse was conducted using interviews and workshop sessions with stakeholders involved in the construction and waste management process (including designers, construction companies, demolition enterprises, waste management companies, reuse agents and authorities), and included six European countries; Sweden, Germany, Belgium, Poland, Italy and Spain. The following main results have been achieved: Description of current reuse practices in the participating countries. Identification of critical reuse barriers and opportunities. Formulation of optimal scenarios to promote reuse in EU. Proposal of key development needs to facilitate reuse activities in EU. Outline of policy recommendations to promote reuse in EU The innovation of the study lies in the involvement of all actors related to the reuse supply chain, thoughout the methodology applied. The perception of the current situation, concerns and requests of the different stakeholders led to the definition of the the optimal scenarios, considering all agents’ points of view and focusing on the synergies.In this context, a study was conducted within the IRCOW-project related to reuse. Reuse is defined in directive 2008/98/EC article 3 §13 as any operation by which products or components that are not waste are used again for the same purpose for which they were conceived