Improved isotopic model based on N tracing and Rayleigh-type isotope fractionation for simulating differential sources of N O emissions in a clay grassland soil.

Rationale: Isotopic signatures of N O can help distinguish between two sources (fertiliser N or endogenous soil N) of N O emissions. The contribution of each source to N O emissions after N-application is difficult to determine. Here, isotopologue signatures of emitted N O are used in an improved isotopic model based on Rayleigh-type equations.

Isotope fractionation factors controlling isotopocule signatures of soil-emitted N₂O produced by denitrification processes of various rates.

Rationale: This study aimed (i) to determine the isotopic fractionation factors associated with N2O production and reduction during soil denitrification and (ii) to help specify the factors controlling the magnitude of the isotope effects. For the first time the isotope effects of denitrification were determined in an experiment under oxic atmosphere and using a novel approach where N2O production and reduction occurred simultaneously.

Methods: Soil incubations were performed under a He/O2 atmosphere and the denitrification product ratio [N2O/(N2 + N2O)] was determined by direct measurement of N2 and N2O fluxes.

Adsorption of surfactant-rich stickies onto mineral surfaces.

"Stickies" are tacky species, present in recycled paper and coated broke, derived from coating formulations, adhesives etc. They impact negatively on paper quality and cause web runnability problems by deposit build-up. To sustain recycling, stickies are controlled by adsorbing them onto minerals added to the recycled stock.

Use of a void network model to correlate porosity, mercury porosimetry, thin section, absolute permeability, and NMR relaxation time data for sandstone rocks.

The Pore-Cor void network model is used to construct stochastic realizations of the void structures of five sandstone samples of varying lithography. A close match was achieved to experimental porosity and mercury intrusion curves. The samples were resin impregnated and the fragments of voids revealed in thin sections photographed by backscatter electron microscopy at two magnifications.

Influence of anisotropy on the dynamic wetting and permeation of paper coatings.

A void network model, named Pore-Cor, has been used to study the permeation of an ink solvent into paper coating formulations coated onto a synthetic substrate. The network model generated anisotropic void networks of rectangular cross-sectional pores connected by elliptical cross-sectional throats. These structures had porosities and mercury intrusion properties which closely matched those of the experimental samples.

The Effects of Void Geometry and Contact Angle on the Absorption of Liquids into Porous Calcium Carbonate Structures.

The absorption (permeation) of alcohols into porous blocks of calcium carbonate has been studied experimentally and with a computer model. The experimental measurement was of change in apparent weight of a block with time after contact with liquid. The modeling used the previously developed 'Pore-Cor' model, based on unit cells of 1000 cubic pores connected by cylindrical throats.