Engineering model for intumescent coating behavior in a pilot‐scale gas‐fired furnace

In the event of a fire, intumescent fire protective coatings expand and form a thermally insulating char that protects the underlying substrate from heat and subsequent structural failure. The intumescence includes several rate phenomena, which have been investigated and quantified in the literature for several decades. However, various challenges still exist. The most important one concerns mathematical model validation under realistic exposure conditions and/or time scales. Another is the simplification of advanced models to overcome the often‐seen lack of a complete set of input and adjustable model parameters for a given coating, thereby providing models for industrial applications. In this work, these two challenges are addressed. Three experimental series, with an intumescent coating inside a 0.65 m³ gas‐fired furnace, heating up according to so‐called cellulosic fire conditions, were conducted and a very good repeatability was evident. The experiments were run for almost 3 h, reaching a final gas temperature of about 1100°C. Measurements include transient temperature developments inside the expanding char, at the steel substrate, and in the mineral wool insulation placed behind the substrate. A mathematical model, describing the intumescent coating behavior and temperatures in the furnace using a single overall reaction was developed and validated against experimental data. By including a decomposition front movement through the char, a good qualitative agreement was obtained. After further validation against experiments with other coating formulations, it has potential to become a practical engineering tool. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3947–3962, 2016     

Importance of a Conserved Lys/Arg Residue for Ligand/PDZ Domain Interactions as Examined by Protein Semisynthesis

PDZ domains are ubiquitous small protein domains that are mediators of numerous protein–protein interactions, and play a pivotal role in protein trafficking, synaptic transmission, and the assembly of signaling‐transduction complexes. In recent years, PDZ domains have emerged as novel and exciting drug targets for diseases (in the brain in particular), so understanding the molecular details of PDZ domain interactions is of fundamental importance. PDZ domains bind to a protein partner at either a C‐terminal peptide or internal peptide motifs. Here, we examined the importance of a conserved Lys/Arg residue in the ligand‐binding site of the second PDZ domain of PSD‐95, by employing a semisynthetic approach. We generated six semisynthetic PDZ domains comprising different proteogenic and nonproteogenic amino acids representing subtle changes of the conserved Lys/Arg residue. These were tested with four peptide interaction partners, representing the two different binding modes. The results highlight the role of a positively charged amino acid in the β1–β2 loop of PDZ domains, and show subtle differences for canonical and noncanonical interaction partners, thus providing additional insight into the mechanism of PDZ/ligand interaction.     

Room Sharing in Sydney: A Complex Mix of Affordability,Overcrowding and Profit Maximisation

The shared housing sector is a growing private rental submarket. Researchers have sought to analyse the drivers of this growth, the benefits of shared housing for tenants, landlords and wider urban systems, as well as risks for tenants and local planning systems. Yet, there is limited research exploring the diversity of the shared housing sector. In particular, analysis of room or space sharing with non-related adults is lacking. This paper explores the characteristics, geography and impact of room sharing across Sydney. By analysing online accommodation listings this paper provides insights for policymakers seeking to monitor and regulate shared room accommodation.     

The adjustable synergistic effects between acid–base coupling bifunctional ionic liquid extractants for rare earth separation

Two of the most widely used industrial extractants for rare earth elements (REEs), that is, di(2‐ethylhexyl)phosphoric acid (HDEHP) and 2‐ethyl(hexyl) phosphonic acid mono‐2‐ethylhexyl ester (HEH[EHP]) were developed into [DEHP]^? type acid–base coupling bifunctionalized ionic liquids (ABC‐BILs) and [EHEHP]^? type ABC‐BILs, respectively. The combinations of ABC‐BIL extractants revealed synergistic effects for REEs. Seven different combinations of ABC‐BILs and five kinds of REEs confirmed the novel synergistic extraction. Some synergy coefficients of the combined ABC‐BILs were bigger than those of mixed HDEHP and HEH[EHP] by two orders of magnitude. The first synergistic extraction produced by ionic liquid extractants in the field of solvent extraction was reported in this article. The novel synergistic extraction from combined ABC‐BILs extractants revealed highly efficient and environmentally friendly potential in both of academic research and industrial application for REEs separation. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3859–3868, 2014     

Kinetic Energy Approach to Dissolving Axisymmetric Multiphase Plumes

A phenomenological kinetic energy theory of buoyant axisymmetric multiphase plumes is constructed, with particular attention to the modeling of the dispersed phase. The dissolution is treated by means of the Ranz-Marshall equation involving a mass-transfer coefficient dependent on the plume properties. The model is compared with various experiments, yielding satisfactory agreement. A central ingredient in the model is the turbulent correlation parameter I, playing a role analogous to the conventional entrainment coefficient α. We use experimental data to suggest a relationship between I, the initial gas flux at the source, and the depth of the gas release.     

Physico-chemical characteristics of full scale sewage sludges with implications to dewatering

An investigation was carried out for a variety of different sewage sludges in order to establish correlations between sludge composition, structure and dewatering properties. Results indicated that the fraction of extracellular polymeric substances (EPS) in sludges was the most important parameter with respect to sludge structure. With high EPS contents, sludges had a lower shear sensitivity and lower degree of dispersion. This in turn lead to better filterability in terms of low resistance to filtration (SRF). The floc stabilising role of EPS components was not consistent with DLVO-theory, as the zeta-potential increased with increased EPS content due to increased EPS charge content. This indicates that polymer entanglement is a key factor to stable floc structure. This does not rule out the possible change in dispersion due to changed electrostatic repulsion for a given EPS content. While EPS had a good effect on floc stability and filterability, the cake dry matter content decreased with large EPS contents. This could be due to an osmotic pressure related to the polymer charge quantity, or it could be caused by water entrapment in the floc structures. A high degree of sludge dispersion increased the cake dry matter content in filtration. This mechanism is, however, impractical due to high SRF and not important to conditioned sludge. In practice, dewatering also includes sludge expression. Taking this into account, osmosis related to EPS charges is likely to be increasingly important (increasing the negative effect of EPS content on cake dry matter).