The rate of hydrogen evolution, r(H 2), due to the photocatalysed reforming of methanol, MeOH, is studied as a function of Pt loading on P25 TiO 2 both in the aqueous (at room temperature) and gas phase (at 100 o C). A similar study, using Pd on P25, has been reported earlier [M. Bowker et al. J. Catalysis, 2003, 217, 427-433] and a perimeter-based Metal-Support Interface (MSI) kinetic model used to interpret the results. Here a new kinetic model is introduced which appears to provide a better fit to all the r(H 2) vs wt% metal data sets, in which the rate of reaction is proportional to an extended area around each metal island, rather than its perimeter. A simple theoretical rationale is provided for this expanding photocatalytic area and overlap (EPAO) kinetic model in which each metal island forms an electric field with the surrounding TiO 2 so as to act as a sink for electrons photogenerated in the surrounding TiO 2 film, thereby allowing it to effect the reduction of water, leaving the remaining photogenerated holes to oxidise the methanol adsorbed on the TiO 2. Some support for this very simple kinetic and theoretical model is provided by the results of a brief study of the oxidation of soot deposited on and around a Pt 'dot' on a sol-gel TiO 2 film, in that, upon irradiation of this system a zone of activity is visibly revealed by the gradual disappearance of the soot around the Pt 'dot', the radius of which appears to be proportional to the radius of the metal 'dot'.

A number of different M/TiO 2 photocatalysts, where M (the co-catalyst) = Pt, Pd, Au and Ag, are used to drive the steam reforming of methanol (MeOH) in a gas phase continuous flow reactor operated at 100 o C. The rate of H 2 production is: Pt > Pd > Au > Ag >> no metal. The photonic efficiency of Pt/TiO 2 photocatalyst is ca. 120% which suggests some of the hydrogen derives from a current-doubling reaction mechanism. The Pt/TiO 2 photocatalyst drives the steam reforming of MeOH, which generates H 2 and CO 2 , with an apparent selectivity of 100% over a wide UV irradiance range (i.e. 1-9.5 mW cm-2 at 365 nm). In contrast, in the dark, the decomposition of MeOH, which generates H 2 and CO, dominates with a selectivity of ca. 79%. In contrast to Pt, the Pd/TiO 2 photocatalyst is non-selective to either MeOH reforming or its decomposition, so that CO 2 and CO are generated with equal rates. The Au and Ag photocatalysts are less active than either the Pt or Pd co-catalysts and exhibit a variation in selectivity with UV irradiance which is intermediate between that of Pt and Pd. The possible use of photocatalysis as a means to generate H 2 from alcohol-based biofuels is briefly discussed.

Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD), the third enzyme of the mitochondrial beta-oxidation pathway, carries out the dehydrogenation of 3-hydroxyacyl-CoA compounds of 12-18 carbon length. To date only nine cases of LCHAD deficiency have been documented. We report a further patient who as a neonate developed non-specific gastrointestinal symptoms and at 5 months of age cardiomyopathy, recurrent hypoketotic hypoglycaemia and gross alterations of plasma carnitine fractions. Dietary management with medium chain triglycerides led rapidly to clinical improvement. There was a close correlation between the clinical condition, plasma carnitine fractions and cardiac function. At 2 years of age she is developing normally.

Clearly discernible rings of high photocatalytic activity, i.e. rings of activation, RoAs, are formed around Pt macro-sized (radius: ro  1 mm radius) Pt islands, i.e. Pt 'dots', deposited on TiO2 films, which have been covered with a visible pollutant, such as soot, or a dye, such as acid orange 7, AO7. The features of the RoA region appear very similar for soot or dye-covered films. Thus, the radius of the RoA region, ra, appears to depend weakly, if at all, on ro, and is typically 0.60-0.68 mm > ro. The rate of photocatalytic removal of the surface pollutant inside the RoA is uniform and significantly greater, i.e. ca. 3.2 -5 x's, than that outside the RoA region. RoA region formation is observed for: (i) Pt dots which have been photodeposited or created through thermal reduction, (ii) Pt dots on sol-gel and commercial (paints and tiles) TiO2 films and (iii) Pd dots, but less clearly for Au dots. A simple mechanistic rationale for RoA region formation is presented and the potential importance of this feature, with regard to improving the performance of commercial photocatalytic films, is discussed briefly.

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The preparation and testing of a colour-based prototype indicator for high-pressure processing (HPP) are described. The indicator is a layered structure comprising a pressed disc of a mixture of silica gel, which has been previously loaded with a set wt% of acidified water, and polytetrafluoroethylene, PTFE, powders, a water-permeable barrier layer, and a Congo-Red-based pH indicator layer, all vacuum-sealed in a water impermeable plastic film. The value of the wt% is calculated from the ratio of the mass of acidified water added to the mass of originally dry silica gel. The high pressures associated with HPP drive the release of the acidified water from the silica gel and its subsequent transport through the water-permeable barrier layer to the pH indicator, thereby producing a striking red-to-blue colour change. The response of the HPP indicator can be tuned to different HPP conditions by varying the wt% of acidified water used to load the silica gel powder. Indicators, with 61, 63, and 65 wt% acidified water loaded silica gel, are prepared and found to require, respectively, the application of at least, 600, 400, and 300 MPa pressure for 3 min to effect a change colour. To our knowledge, this is the first reported example of a prototype HPP indicator that can be tuned to respond to the very different pressure and time conditions used in HPP to sterilise such very different products as milk, apple and orange juice, and aloe vera gel.

Abstract3D printing is known as a fast, inexpensive, reproducible method for producing prototypes but is also fast becoming recognised as a scalable, advanced manufacture process. Two types of lab-scale, 3D printed plastic, fixed-film, flow-through photocatalytic reactors are described, both of which are sinusoidal in shape, and only differ in that one has no baffles, reactor A, whereas the other has, reactor B. Both reactors are lined with a P25 TiO2/polylactic acid (PLA) coating, which, after UVA pre-conditioning, is used to photocatalyse the bleaching of circulating aqueous solutions of either methylene blue, MB, or phenol, PhOH, repeatably, without any obvious loss of activity. The rate of the photocatalysed bleaching of MB exhibited by reactor B shows a much lower dependence upon flow rate than reactor A, due to the greater lateral mixing of the laminar flow streams produced by the baffles. The photonic efficiencies of reactor A for the photocatalysed bleaching of MB and PhOH were determined to be 0.025% and 0.052%, respectively, and the photocatalytic space-time yields (PSTY) to be 0.98 × 10−4 and 1.49 × 10−4 m3 of reaction solution.m−3 reactor volume.day−1.kW−1, respectively. This is the first example of an all plastic, 3D printed photocatalytic reactor and demonstrates the advantages of 3D printing for prototyping. Given the 3D printing is a scalable process, possible potential areas of application are discussed briefly. Graphical abstract