We report on the glass-forming abilities of the homologous series 1,2-diphenylcyclo-butene, pentene, hexene and heptene-a series that retains the cis-phenyl configuration characteristic of the well-studied glass former, o-terphenyl. We find that the glass-forming ability shows a sharp maximum for the six-membered ring and demonstrate that this trend in glass-forming ability is a consequence of a maximum, for the 1,2-diphenylcyclohexene, of the reduced glass transition temperature T(g)/T(m). Since the nonmonotonic trend in T(g)/T(m) is entirely due to variations in T(m), we conclude that the design target for maximizing the glass-forming ability across an homologous series should focus on the crystal stability and the factors that determine it.

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<p>Coastal waters are typically productive aquatic ecosystems and play an important role in the global greenhouse gas (GHG) budget. However, the uncertainty in the estimation of GHG emission from estuaries remains large due to significant variability in GHG concentrations in time and space. This study aimed to provide a more accurate estimation of GHG emissions from sub-tropical estuaries by validating and analyzing results from a 3D hydrodynamic-biogeochemical model used to capture the temporal and spatial dynamics of the major GHG (CO<sub>2</sub> CH<sub>4</sub>, and N<sub>2</sub>O). The model was applied to the Brisbane, Maroochy, and Noosa Estuary in Queensland, Australia, representing systems under high, median, and low human impacts, and was validated with datasets from long-term monitoring stations and field campaigns along the freshwater-marine continuum. Distinct spatial heterogeneity of GHG distribution was found with the upstream acting as a hotspot for emission to the atmosphere, despite this area occupying a relatively small portion of the rivers. Seasonal variations of <em>p</em>CO<sub>2</sub> at the surface were driven mostly by the changes in water temperature and DIC concentrations, while strong diurnal variation was also found, driven by the changes related to tidal forcing. All GHG showed distinct signatures in the three rivers, related to trophic statues and hydrology. The model allowed us to approximate the fraction of incoming carbon and nitrogen that was lost to the atmosphere as GHG emissions, which is a step towards improving regional and national GHG budgets. A link of the biogeochemical model to a parameter optimization software PEST is being used to assist in uncertainty analysis from the model outputs.</p>

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Sediment diagenesis models have been developed over the past few decades using various algorithms and notation for similar processes. Organic matter oxidation in particular has been parameterised in a number of different ways. The reactions involved are the sequence of decreasing energy-yield oxidation pathways (aerobic mineralisation, denitrification, Mn(IV) reduction, Fe(III) reduction, SO 4 2reduction and methanogenesis). In this paper we examine the differences between three common approaches that have emerged in the literature and quantify whether the differences have a significant effect on organic matter oxidation rates. Firstly, the equations of three approaches were expressed using a common notation, highlighting the similarities and differences between the rate expressions. All approaches have an oxidation rate that is the product of the rate constant k OM , organic matter concentration OM, a limitation term Θ Ox , and an inhibition term Θ In. The Θ Ox and Θ In of Approach 1 apply Monod kinetics. The Θ Ox and Θ In of Approach 2 apply Blackman kinetics, which has previously been described as not significantly different to a Monod formulation. Approach 3 uses Monod terms while mixing the limitation and inhibition functions differently to Approach 1. While Approaches 1 and 2 usually use six oxidation pathways, Approach 3 uses three pathways, combining manganese, iron and sulfate reduction and methanogenesis into one anoxic pathway. Methanogenesis in Approach 1 is a product of the previous five inhibition terms, whereas in Approach 2 it is the difference between the total rate and the sum of the five higher-energy rates. The algorithms of the three approaches were compared with a simple calculation of organic matter oxidation on a homogenous unit of sediment over 3 years, in marine and freshwater conditions. The differences between the approaches were illustrated in terms of the points in time when the oxidants are exhausted. In all three approaches, O 2 was exhausted within 1.7 to 1.8 days. The NO 3 was exhausted after 1.7 to 1.8 days in Approaches 2 and 3, but after 2.8 days in Approach 1. In Approach 1 Mn(IV) was exhausted at day 798 and Fe(III) at day 857, whereas these components were not exhausted in Approach 2 in the three year simulation, and not simulated in Approach 3. In the freshwater experiment, SO 4 2was depleted by days 425 and 215, respectively. While the time to depletion differed considerably, it is of note that both approaches allowed depletion of SO 4 2prior to the more thermodynamically favourable oxidants. Approaches 1 and 3 allow for more overlap of the rates of different oxidation pathways whereas Approach 2 only allows for overlap when the oxidant concentration is below its limiting concentration. This represents a different conceptualisation of the microbial processes in the sediment with bacteria either partially or completely inhibited. Implications of this include that at the time when the corresponding reduction pathway began in Approach 2, in Approach 1 25% of NO 3-, 17% of Fe...