Using temporal analysis of products and flux response technology to determine diffusion coefficients in catalytic monoliths

The importance of accurately measuring gas diffusivity in porous materials has led to a number of methods being developed. In this study the Temporal Analysis of Products (TAP) reactor and Flux Response Technology (FRT) have been used to examine the diffusivity in the washcoat supported on cordierite monoliths. Herein, the molecular diffusion of propane within four monoliths with differently prepared alumina/CeZrOx washcoats was investigated as a function of temperature. Moment-based analysis of the observed TAP responses led to the calculation of the apparent intermediate gas constant, Kp, that characterises adsorption into the mesoporous network and apparent time delay, tapp, that characterises residence time in the mesoporous network. Additionally, FRT has been successfully adapted as an extensive in situ perturbation technique in measuring intraphase diffusion coefficients in the washcoats of the same four monolith samples. The diffusion coefficients obtained by moment-based analysis of TAP responses are larger than the coefficients determined by zero length column (ZLC) analysis of flux response profiles with measured values of the same monolith samples between 20 and 100 °C ranging from 2–5×10^-9 m² s^-1 to 4–8×10^-10 m² s^-1, respectively. The TAP and FRT data, therefore, provide a range of the lower and upper limits of diffusivity, respectively. The reported activation energies and diffusivities clearly correlate with the difference in the washcoat structure of different monolith samples.

Alternative method for producing organic fertiliser from anaerobic digestion liquor and limestone powder:High Shear wet granulation

Generally, the solid and liquid fractions (digestate) from Anaerobic Digestion (AD) energy production are considered as waste. This has a negative impact on the sustainability of AD processes because of the financial outlay required to treat digestate before being discharged into municipal water treatment plants or natural water bodies. The main aim of this research was to investigate feasibility of producing an organic fertiliser using anaerobic digestate and limestone powders as the raw materials employing a high shear granulation process. Two-level factorial experimental design was used to determine the influence of granulation process variables on, the strength, resistance to attrition and yield of the granules. It was concluded from the study that it is technically feasible to produce organic fertiliser granules of acceptable strength and product yield. Increasing the liquid-to-solid ratio during granulation leads to increased granule strength and better product yield. Although the strength of the granules produced was lower than typical strength of commercial synthetic fertiliser granules (about 5 to 7. MPa), this could be improved by mixing the digestate with a polymeric binder or coating the particles post granulation. © 2012 Elsevier B.V.

Neuropsychological outcome at adolescence of very preterm birth and its relation to brain structure

Neuropsychological outcome at 14 to 15 years of age of a cohort of 75 participants (39 male, 36 female) born at <33 weeks' gestation was investigated. Research was conducted parallel to a recent MRI study by Stewart and colleagues which reported that 55% of this cohort had evidence of brain abnormality. One aim of the studs was to compare neuropsychological function in those very preterm children with and without MRI abnormality. Compared to a control sample of term adolescents, very preterm participants had impairment only on a measure of word production. On measures of attention, memory, perceptual skill, and visuomotor and executive function, the adolescents born very preterm performed in the normal range, whether or not they had evidence of MRI abnormality. Our findings are encouraging as the neuropsychological consequences of damage to the very preterm brain, still evident on MRI at 14 to 15 years of age, appear to be minor.

Failure of thick-skinned stiffener runout sections loaded in uniaxial compression

Recent efforts towards the development of the next generation of large civil and military transport aircraft within the European community have provided new impetus for investigating the potential use of composite material in the primary structure. One concern in this development is the vulnerability of co-cured stiffened structures to through-thickness stresses at the skin-stiffener interfaces particularly in stiffener runout regions. These regions are an inevitable consequence of the requirement to terminate stiffeners at cutouts, rib intersections or other structural features which interrupt the stiffener load path. In this respect, thickerskinned components are more vulnerable than thin-skinned ones. This work presents an experimental and numerical study of the failure of thick-sectioned stiffener runout specimens loaded in uniaxial compression. The experiments revealed that failure was initiated at the edge of the runout and propagated across the skin-stiffener interface. High frictional forces at the edge of the runout were also deduced from a fractographic analysis and it is postulated that these forces may enhance the fracture toughness of the specimens. Finite element analysis using an efficient thick-shell element and the Virtual Crack Closure Technique was able to qualitatively predict the crack growth characteristics for each specimen