An Experimental and Numerical Study of the Low‐Pressure Grouting of Granular Soils by Diluted Chemical Solutions

The use of silicate solutions for the low‐pressure grouting of granular soils is one of the techniques applicable in geotechnical engineering to reduce the “natural” hydraulic conductivity of granular deposits. This provision was suggested as a possible mean to limit the leakage of water within some underground structures located in the urban area of Milan and caused by the increase of the water table level. These structures, in fact, were built during the 1970s, and in the early 1980s, without a proper waterproofing because of the low level of the water table at that time. An experimental and numerical study is presented here to evaluate the effectiveness of grouting treatments in reducing the hydraulic conductivity of granular soils. First, the experimental part of the study is summarized, which aims at providing an insight into the variation of the hydraulic conductivity of a granular soil during the grouting process. Then, the numerical modeling of this process is discussed and the main features of a two‐ and three‐dimensional finite element program, developed for the purposes of this study, are outlined. Finally, on the basis of a series of numerical analyses, some conclusions are drawn on the effectiveness of the proposed provision.     

Mass spectrometry in the diagnosis of thyroid disease and in the study of thyroid hormone metabolism

The importance of thyroid hormones in the regulation of development, growth, and energy metabolism is well known. Over the last decades, mass spectrometry has been extensively used to investigate thyroid hormone metabolism and to discover and characterize new molecules involved in thyroid hormones production, such as thyrotropin-releasing hormone. In the earlier period, the quantification methods, usually based on gas chromatography–mass spectrometry, were complicated and time consuming. They were mainly focused on basic research, and were not suitable for clinical diagnostics on a routine basis. The development of the modern mass spectrometers, mainly coupled to liquid chromatography, enabled simpler sample preparation procedures, and the accurate quantification of thyroid hormones, of their precursors, and of their metabolites in biological fluids, tissues, and cells became feasible. Nowadays, molecules of physiological and pathological interest can be assayed also for diagnostic purposes on a routine basis, and mass spectrometry is slowly entering the clinical laboratory. This review takes stock of the advancements in the field of thyroid metabolism that were carried out with mass spectrometry, with special focus on the use of this technique for the quantification of molecules involved in thyroid diseases.     

Development of smooth finishes in electrostatic fluidized bed (EFB) coating process of high-performance thermoplastic powders (PPA 571 H)

This paper deals with the analysis of the evolution of the surface morphology of metal substrates coated with high-performance thermoplastic powders, namely PPA 571 H, by using electrostatic fluidized bed (EFB) process. Attention has been particularly focused on the relationship between baking time and temperature of EFB coated substrates and the morphological characteristics of the resulting polymeric films.

First, thermal behaviour of PPA 571 H polymeric powders was characterized by using standard calorimetric techniques. Accordingly, PPA 571 H melting kinetic was experimentally deduced. Based upon experimental findings, predictive analytical model was also developed and employed to trace ‘iso-conversion’ curves out.

Second, metal substrates, made from low carbon steel (AISI 1040), were EFB coated and baked at several baking time and temperatures. Combined analyses of scanning electron and confocal microscopes were led to measure the evolution of the films surface morphology under different baking conditions. Accordingly, a relationship between film morphologies and melting degree was sought. Consistent trends of roughness parameters versus baking parameters were found, with smoother finishes of the polymeric films being achieved for higher degrees of melting, that is, for higher baking temperature and time. Full maps and related analytical models of the finishing levels according to baking parameters were also built up, hence providing first useful indications to powder coaters on how to best deal with their settings.     

On the antimony-stabilized cubic structure of potassium/ammonium salts of 12-molybdophosphoric acid and its catalytic performance in the oxidehydrogenation of ethane

Potassium/ammonium salts of 12-molybdophosphoric acid were modified by the addition of an Sb⁵⁺ salt. The addition of antimony led to a remarkable increase in the thermal structural stability of the compounds obtained. The incipient destruction of the Keggin unit in the mixed potassium/ammonium salt of 12-molybdophosphoric acid was shifted from 400–420°C to 500°C. The potassium salt modified by the addition of one Sb⁵⁺ atom per KU decomposed at temperatures higher than 600°C. This property allowed the samples to be used as catalysts for high temperature, gas-phase oxidation reactions, such as the oxidehydrogenation of ethane. The compounds did not undergo structural decomposition at temperatures as high as 540°C under reaction conditions, but were poorly active and selective in ethylene formation. Therefore, antimony-stabilized compounds were further modified by the addition of transition metal ions in order to improve the catalytic performance. The addition of small amounts of iron, chromium and cerium ions led to an improvement of the catalytic performance; the compound was apparently monophasic, and characterized by the cubic crystalline structure typical of the salts of 12-molybdophosphoric acid.On leave from the Institute of Chemical Physics, Academy of Sciences, Russia.     

Soil sealing footprint as an indicator of dispersed urban growth: a multivariate statistics approach

The present study introduces a set of indicators derived from high-resolution land-use maps with the aim to illustrate the spatial distribution, intensity, and diversity of sealed soils in a Mediterranean region (Rome, Italy) shifting from a mono-centric spatial organization toward a dispersed urban agglomeration. A multivariate approach provides a comprehensive assessment of Rome ‘sealing footprint’, classifying local districts according to different imperviousness profiles. Results illustrate the rearrangement of the land-use structure determined by suburbanization with higher soil consumption and lower land-use efficiency. The approach is considered a promising tool to inform policies for a spatially balanced and land-saving urban development.     

Toxicity removal efficiency of decentralised sequencing batch reactor and ultra-filtration membrane bioreactors

As a consequence of the Water Framework Directive and Marine Strategy Framework Directive, there is now more focus on discharges from wastewater treatment plants both to transitional and marine-coastal waters. The constraint to encourage sustainable water policy to prevent water deterioration and reduce or stop discharges has entailed new requirements for existing wastewater treatment plants in the form of advanced wastewater treatment technologies as further suggested by the Integrated Pollution and Prevention Control Bureau. A whole toolbox of physico-chemical and ecotoxicological parameters to investigate commercial and mixed domestic and industrial discharges was considered to check the efficiency of an Activated-Sludge Sequencing Batch Reactor (AS-SBR) and two Ultra-Filtration Membrane Biological Reactors (UF-MBRs) on a small scale decentralised basis. All discharges were conveyed into Venice lagoon (Italy), one of the widest impacted Mediterranean transitional environment. The UF-MBRs were able to provide good quality effluents potentially suitable for non-potable reuse, as well as reducing specific inorganic micro-pollutants concentration (e.g. metals). Conversely, the AS-SBR showed unpredictable and discontinuous removal abilities.     

Moving Out of Home Ownership in Later Life: The Influence of the Family and Housing Careers

Home ownership is often regarded as the preferred housing tenure; however, situations in parallel life-course careers might make moving to a rental home necessary or attractive to home owners. Retrospective data from the SHARELIFE survey were used to study the short- and long-term impact of situations and disruptions in the family and housing careers on leaving home ownership at middle (45–64) and older ages (65–80) in Denmark, Sweden and the Netherlands. We found that directly after separation and widowhood, the likelihood of leaving home ownership was the greatest. However, more than 10 years after separation and widowhood, individuals were still significantly more likely to leave ownership than those in their first marriage. Furthermore, late first childbirth and early first-time home ownership were associated with lower chances of leaving home ownership. We conclude that situations and changes in family and housing careers have both a short-term and a long-term impact on the likelihood of moving out of home ownership.     

Dynamics of alternative modes of RNA replication for positive-sense RNA viruses

We propose and study nonlinear mathematical models describing the intracellular time dynamics of viral RNA accumulation for positive-sense single-stranded RNA viruses. Our models consider different replication modes ranging between two extremes represented by the geometric replication (GR) and the linear stamping machine replication (SMR). We first analyse a model that quantitatively reproduced experimental data for the accumulation dynamics of both polarities of turnip mosaic potyvirus RNAs. We identify a non-degenerate transcritical bifurcation governing the extinction of both strands depending on three key parameters: the mode of replication (α), the replication rate (r) and the degradation rate (δ) of viral strands. Our results indicate that the bifurcation associated with α generically takes place when the replication mode is closer to the SMR, thus suggesting that GR may provide viral strands with an increased robustness against degradation. This transcritical bifurcation, which is responsible for the switching from an active to an absorbing regime, suggests a smooth (i.e. second-order), absorbing-state phase transition. Finally, we also analyse a simplified model that only incorporates asymmetry in replication tied to differential replication modes.