Effect of Na diffusion from glass substrate on the microstructural and photocatalytic properties of post-annealed TiO2 films synthesised by reactive sputtering

Amorphous columnar TiO₂ films were synthesised by reactive sputtering on cold soda–lime glass substrates (TiO₂/glass films). The films were subsequently heated in order to crystallise the photoactive anatase phase. The surface chemical composition assessment demonstrates the occurrence of metallic Na, the amount of which increases with the annealing temperature. The evolution of the structural, microstructural and photocatalytic properties of the films with the annealing temperature was investigated and compared to that of TiO₂ films deposited in same conditions, but on glass pre-coated with a SiN_x diffusion barrier (TiO₂/SiN_x/glass films). Once crystallised, both series of TiO₂ films exhibit [001] preferential orientation corresponding to the columnar growth. Grain coalescence associated to a modification of the grain shape is only observed in TiO₂/glass films for annealing temperatures higher than 450 °C, whereas neither microstructural nor structural change is observed in TiO₂/SiN_x/glass films. The Na-contaminated TiO₂ films exhibit different photocatalytic behaviour with the annealing temperature compared to the Na-free TiO₂ films. A discussion is finally based on these differences.     

Chiral organic thin films: How far pulsed laser deposition can conserve chirality

We have investigated the pulsed laser deposition (PLD) technique to grow isotropic thin films based on bridged binaphthyls. We have focused on the conservation of the chiroptical properties during the deposition process. Chiral high purity liquid chromatography reveals that all the molecules are damaged at the same laser power threshold, but that below this threshold, neither bridged binaphthyl nor binaphthol undergo racemization. In situ circular dichroism spectra, as well as optical rotation (OR) measurements, confirm these findings. Isotropic 2 μm thick films with OR of 20°/mm at 546 nm were deposited. Furthermore, an estimation of the thermal load reveals that, due to its instantaneous nature, PLD does not induce thermal degradation. Only photochemical processes are involved in both racemization and degradation.     

Adiponectin and atherosclerosis risk factors in African hemodialysis patients: a population at low risk for atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (CVD) is the major cause of morbidity and mortality in hemodialysis (HD) patients. Adiponectin (ADPN), a recently discovered collagen-like protein, is secreted exclusively by adipocytes. It has anti-atherogenic properties and reduced serum ADPN levels have been shown to be predictive of cardiovascular events. In this study, we determined the atherosclerotic risk and the significance of ADPN levels in our HD patients and also examined its relationship to other traditional CVD risk factors. A cross-sectional study of 84 patients on maintenance HD (58 Blacks and 26 non-Blacks) and 63 healthy controls matched for age, sex and race (35 Blacks and 28 non-Blacks) was undertaken. Serum ADPN levels and other risk factors, including blood pressure, serum lipid, and C-reactive protein, were studied in HD patients and were compared with the controls. Carotid artery intima-media thickness and plaque occurrence was measured by B-mode ultrasonography while echocardiography was done according to American Society of Echocardiography guidelines. Serum ADPN levels were higher in the HD group compared with the control subjects (22.19 ± 0.98 mg/mL vs. 9.93 ± 0.68 mg/mL; P < 0.001). Higher ADPN levels in HD patients were associated with lower triglyceride levels. ADPN correlated positively (r = 0.49, P < 0.0001) with left ventricular mass index (LVMI) in the total study population. ADPN levels were raised in HD patients and correlated with LVMI, possibly because of the confounding effect of low glomerular filtration rate. ADPN levels were inversely related to risk factors for atherosclerosis and may provide possible targets for therapeutic interventions.     

Influence of fatty acid additives on the tribological performance of sunflower oil

Vegetable oils are potential substitutes for petroleum‐based lubricants because they are environmentally friendly, renewable, less toxic and readily biodegradable. The addition of free fatty acids has been shown to increase the lubrication performance of vegetable oils at elevated temperatures. The purpose of this study was to evaluate the relationship between the length of the carbon chain in the fatty acid and its effectiveness as an additive for a range of elevated temperatures. Stearic, arachidic and behenic fatty acid additives were added to commercial sunflower oil. All fatty acid additives were shown to be effective in lowering the wear rate and coefficient of friction in ball‐on‐disc tribological tests. The overall carbon chain length was not observed to have a consistent influence on the effectiveness of the additive. All additives were less effective at temperatures above 100°C. Copyright © 2010 John Wiley & Sons, Ltd.     

Modelling the dynamic response of a solid oxide steam electrolyser to transient inputs during renewable hydrogen production

Hydrogen is regarded as a leading candidate for alternative future fuels. Solid oxide electrolyser cells (SOEC) may provide a cost-effective and green route to hydrogen production especially when coupled to a source of renewable electrical energy. Developing an understanding of the response of the SOEC stack to transient events that may occur during its operation with intermittent electricity input is essential before the realisation of this technology. In this paper, a one-dimensional (1D) dynamic model of a planar SOEC stack has been employed to study the dynamic behaviour of such an SOEC and the prospect for stack temperature control through variation of the air flow rate. Step changes in the average current density from 1.0 to 0.75, 0.5 and 0.2 A/cm² have been imposed on the stacks, replicating the situation in which changes in the supply of input electrical energy are experienced, or the sudden switch-off of the stack. Such simulations have been performed both for open-loop and closed-loop cases. The stack temperature and cell voltage are decreased by step changes in the average current density. Without temperature control via variation of the air flow rate, a sudden fall of the temperature and the cell potential occurs during all the step changes in average current density. The temperature excursions between the initial and final steady states are observed to be reduced by the manipulation of the air flow rate. Provided that the change in the average current density does not result in a transition from exothermic to endothermic operation of the SOEC, the use of the air flow rate to maintain a constant steady-state temperature is found to be successful.     

Human collagen II peptide 256-271 preferentially binds to HLA-DR molecules associated with susceptibility to rheumatoid arthritis

The history and evolution of devices designed to achieve urinary continence are reviewed. Passive and active (including volume and pressure regulated) devices are described in detail. Meta-analysis of the published studies revealed that continence improved in 88% of patients and total continence was achieved in 73%. Global revision rate was 32%. Urethral erosion occurred in approximately 12%, infection in 4.5% and mechanical complications in 14% of cases. The complications relating to the AMS artificial urinary sphincter are analyzed. The majority of patients (> 85%) required only one revision. 22% of complications were due to mechanical malfunction. Infection comprised 12.9% of complications. The patterns of total revisions followed a double exponential decay curve: 50% of revisions were performed within 8 months and 90% within 3 years of implantation. Complications were still reported several years postimplantation. This review analyzes the problems relating to the application of pressure and the presence of foreign material around the urethra and exemplifies the requirement for long-term specialist follow-up of these patients.     

Automatic tool state identification in a metal turning operation using MLP neural networks and multivariate process parameters

This paper describes results of the application of feed-forward Multi-Layer Perceptron (MLP) neural networks for cutting tool state identification in a metal turning operation. Test cuts were conducted using P25 carbide inserts with and without wear (i.e. nominally sharp) on EN24 alloy steel. The acquired data were used to train, cross-validate and test the generalisation capabilities of two MLP configurations. Both networks had exactly the same input and output nodes but differing number of nodes in a single middle layer. Training was achieved via back-propagation of error enhanced by the addition of a momentum term and adaptive learning rate. Different error goal targets during training of the MLP were used, and the validation results of the model investigation analysed and presented. Obtained results for successful classification of the tool state with respect to only two classes (worn or sharp) were between 83 and 96%.     

Comparing spectral and invasive estimates of baroreflex gain

One of the new methods to evaluate the sensitivity of the baroreceptor-heart rate (HR) reflex involves the use of power spectral analysis to calculate the transfer function between blood pressure and HR. We assess the applicability and reproducibility of the baroreflex gain estimated by this method with traditional invasive techniques that induce ramp changes in mean arterial pressure (MAP) in conscious rabbits. Renal sympathetic nerve activity recordings are used to identify the mid-frequency band, and we also identify coherent fluctuations of MAP and HR with a 1.8 s phase delay, consistent with a baroreflex relationship and therefore appropriate to estimate the cross spectral transfer function     

Places to stay on the move: Software architectures for mobile user interfaces

Architectural design has an important effect on usability, most notably on temporal properties. This paper investigates software architecture options for mobile user interfaces, in particular those for collaborative systems. One of the new features of mobile systems, as compared with fixed networks, is the connection point to the physical network, the point of presence (PoP), which forms an additional location for code and data. This allows architectures that bring computation closer to the users, hence reducing feedback and feedthrough delays. A consequence of using PoPs is that code and data have to be mobile within the network, leading to potential security problems.