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Two independent projects are described in which drophammer techniques are used to investigate the dynamic increase factor (DIF) under both flexural and shear high-speed loading of a new ultra high performance fibre reinforced blast resistant concrete. The results from both studies correlate well. The results show that a DIF of the flexural tensile strength rising from 1.0 at 1 s -1 on a slope of 1/3 on a log (strain rate) versus log (DIF) plot can be used for design purposes. The results also show that no DIF should be used to increase the shear strength at high loading rates.

Several factors affecting the reactivity of fly ash (FA) as a precursor for geopolymer concrete have been investigated. These include physical and chemical properties of various FA sources, inclusion of ground granulated blast furnace slag (ggbs), chemical activator dosages and curing temperature. Alkali-activated FA was found to require elevated curing temperatures and high alkali concentrations. A mixture of sodium hydroxide and sodium silicate was used and this was shown to result in high strengths, as high as 70 MPa at 28 days. The presence of silicates in solution was found to be an important parameter affecting strength. Detailed physical and chemical characterisation was carried out on thirteen FA sources from the UK. The most important factor affecting the reactivity was found to be the particle size of FA. The loss on ignition (LOI) and the amorphous content are also important parameters that need to be considered for the selection of FA for use in geopolymer concrete. The partial replacement of FA with ggbs was found to be beneficial in not only avoiding the need for elevated curing temperatures but also in improving compressive strengths. Microstructural characterisation with scanning electron microscope (SEM) coupled with energy dispersive Xray spectroscopy (EDS) was performed on FA/ggbs pastes. The reaction product of FA and ggbs in these binary systems was calcium aluminium silicate hydrate gel (C-AS -H) with inclusion of Na in the structure.

Neonatal seizures have devastating consequences for brain development and are inadequately treated by available antiepileptics. In neonates, gamma-aminobutyric acid (GABA) is an excitatory neurotransmitter due to elevated levels of intraneuronal chloride achieved by robust activity of the Na(+)-K(+)-2Cl( -) cotransporter (NKCC1). This depolarizing action of GABA likely contributes to the lowered seizure threshold, increased seizure propensity, and poor efficacy of GABAergic anticonvulsants among infants. The diuretic bumetanide inhibits NKCC1 and silences seizure activity in rodent models of neonatal seizures, but its effect on seizures in human neonates is unknown. Continuous electroencephalography (EEG) monitoring was used to quantify the number, duration, and frequency of seizures 2 hours before and after the administration of bumetanide in a neonate with intractable multifocal seizures. Significant reductions in mean seizure duration and frequency were noted following treatment, with no associated clinical side effects or metabolic imbalances. These results suggest bumetanide may exert antiepileptic effects in human neonates.

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The systematic study of band-edge luminescence in pseudomorphic Si/Si1−xGex/Si double-heterostructure layers is reported for a wide composition range, 0.12<x<0.24, for the first time. An analytical expression for the exciton energy gap at 4.2 K valid for x<0.24 is derived from the no-phonon line energies: ESX(x) = 1.155−0.874x+0.376x2 eV. Addition of an expression for the exciton binding energy provides an approximation for the energy difference between the alloy valence band and the lowest conduction-band edge at low temperature. An exciton upshift of 16.9 meV due to quantum confinement is observed in a 6.3-nm Si0.83Ge0.17 alloy well. This is consistent with either type-I or type-II band alignment for which the conduction-band offset has a magnitude ‖ΔEc‖ ≤ 10 meV. The excitonic hole is closely confined in the alloy but the spectra suggest that the electron density in the silicon barriers is increased for the thin layer.