High Surface Area Oxidation – Development of an Improved Open Cup ARC Vessel and Validation

PresentationEasily oxidized, low volatility organic liquids absorbed/dispersed on inorganic solid materials such as insulation, absorbents, and molecular sieves can result in spontaneous ignition incidents. This is due to increased rates of oxidation of the organic when it is spread out over the very high surface area inherent in these types of solid materials. Similarly, high surface area organic solids that are either self-reactive or oxidizable may self-heat when accumulated in a pile of sufficient size, resulting in thermal runaways, gas generation, and/or fire. Understanding and quantifying this behavior is critical to identifying hazards and developing appropriate mitigative measures. Previously, an Open Cup Accelerating Rate Calorimeter technique was developed at Dow using an open, stainless steel container, purged with air heated to testing temperatures to maintain adiabaticity. This method has been used for many years to understand the reaction kinetics of “auto-oxidation” reactions and high surface area runaway reactions. While the method has been shown to be reliable and able to accurately predict large scale hazards, the exposure of the gaseous decomposition and oxidation products of the reactions is destructive to the ARC calorimeter. The open-cup system vents directly into the ARC, resulting in accelerated corrosion or potentially exposing the internals to fire. A new ARC container design has been developed that has been demonstrated to produce comparable results and removes the concerns associated with damaging the equipment. The new design of the Open Cup ARC test cell, validation, and discussion of the data application will be included in this article

Local and regional ecological morphology of dung beetle assemblages across four biogeographic regions

Aim Niche partitioning within species assemblages is thought to influence species packing and/or total niche space occupied. The evolution of dung beetles (Scarabaeinae) is likely to have been strongly influenced by inter-specific competition, leading to niche partitioning. We consider whether local-scale processes leave a signature in regional patterns of functional diversity in dung beetle assemblages, and investigate the correlation between total exploited ecomorphological space and density of species packing with increased species richness. We test whether ecomorphological space occupied by local assemblages reflects that of their regional species pool, and the extent to which ecomorphological space is convergent or divergent within functional groups across regional pools. Location Neotropics, Africa, Australia and Madagascar. Methods Dung beetle assemblages were collected in a standardized manner from four biogeographic regions. Ecomorphological similarity among the assemblages was assessed by multivariate analysis of 19 linear measurements for 300 species and three functional nesting types (roller, tunneller or dweller), firstly on a local level within the Neotropics and Afrotropics, and then between the regional species pools. Results Key body measurements, in particular the hind tibia, separated rollers and tunnellers into largely non-overlapping entities along the first three axes of the shape analysis. Three Neotropical assemblages, which vary widely in species numbers, each harboured a similar amount of morphometric variation, resulting in increasingly dense species packing with greater species richness. Similar findings were obtained in two South African assemblages. Assemblages in the four biogeographic regions showed largely similar distributions of ecomorphological variation, including the separation of rollers and tunnellers, despite their distant phylogenetic relationships. Ecomorphological similarity among regions was particularly high in tunnellers, whilst the rollers exhibited greater regional differentiation. Main conclusions Local assemblages evidently represent the full diversity of functional groups available in the regional pool, even in species-poor assemblages. There is a strong trend towards convergence in morphology separating tunnellers and rollers in phylogenetically independent lineages. The ecomorphological similarity of regional assemblages suggests that morphological convergence is the result of common selective forces active within the assemblages themselves. This lends support to the widely hypothesized effect of inter-specific interactions and niche partitioning in determining assemblage composition and lineage evolution in the Scarabaeinae. © 2011 Blackwell Publishing Ltd

A systematic search for warm molecular gas in AGN and star forming galaxies at z=2 with MIRI

Feedback from Active Galactic Nuclei (AGN) have become the cornerstones of cosmological hydrodynamical simulations and they are believed to regulate the star formation in their host galaxies. A promising way to gauge the impact of AGN on the interstellar medium is by tracing their molecular gas content, as the gas experiences an immediate impact of the radiation, jets or outflows from the AGN, compared to star formation. Recent ALMA observations targeting CO emission in mass-matched sample of AGN and non-AGN host galaxies at high redshift have suggested that AGN display lower cold molecular gas content compared to their non-AGN counterparts. One of the hypothesis to explain this difference is the molecular gas in AGN host galaxies could be present in the warm molecular gas phase, traced using rest-frame near-infrared ro-vibrational transitions. This proposal aims to trace warm molecular gas via rest-frame H2 2.12 um transition in a mass-matched sample of AGN and non-AGN host galaxies at z~2.2 using MIRI/MRS. The selected sample is complemented by ground-based ionised gas and cold molecular gas observations. We will test if AGN host galaxies show a systematic difference in their warm molecular gas content compared to the non-AGN galaxies. We will also compute the total gas mass (ionised+molecular) in these galaxies which will provide a key input to current models of AGN feedback...