Spray deposition for plastic electronics

Spray deposition is a promising technique for the solution processing of plastic electronic devices due to its potential for high-speed, large-scale device fabrication using low capital cost equipment. Most recent reports of spray-deposited electronic devices have used ultrasonic systems for film deposition to minimise surface roughness, but such systems suffer from low materials throughput, and are consequently ill-suited to industrial manufacturing. Gas-driven spray-heads enable higher throughput materials delivery but can result in an unacceptably rough film due to the large, broadly distributed droplet sizes that are often generated and the hard-impact nature of the deposition process. This thesis describes a new automated gas-driven spray coater for the controlled deposition of a broad variety of solution processed electronic materials. It is specifically suited to the deposition of polymer films such as poly(3-hexylthiophene) (P3HT), overcoming many of the usual disadvantages of conventional gas-driven spray coaters. Key features of the system include: a novel, high performance 3D-printed spray-head for the generation of ultrafine sprays; full three-dimensional position and velocity control of the spray head; integrated temperature control; and independent control of solution and gas flow rates. To determine the optimum solution composition for spray-deposition of P3HT films, the aggregation and gelation dynamics of various P3HT/o-xylene solutions were first investigated by static light scattering. On the basis of these measurements, we conclude that dilute solutions (with polymer concentration <5 mg/ml) of low (<20 kg/mol ) molecular weight polymer containing a small amount of a secondary solvent. are optimal for avoiding gelation and clogging of the spay-head. For higher weight material, heating of the solution is necessary to avoid gelation. The thesis also describes the development of an optical profiling technique for the characterisation of polymer films, which provides a fast method for quantitatively characterising the uniformity of large-area, thin polymer films. Using this technique, we were able to confirm that the spray-deposition system yields high quality, thin semiconducting polymer films, allowing for the controlled fabrication of active layers in organic photovoltaic devices from non-chlorinated solvents. The influence of solution composition and deposition variables such as gas pressure, solvent composition and substrate temperature were investigated, and optimised conditions for the deposition of high quality (device-grade) thin P3HT films were thereby identified. A maximum device efficiency of 4.0 % was achieved for the spray-deposited bulk heterojunction P3HT:fullerene films processed from xylene. The results indicate that, providing the active layer is continuous, high device efficiency may be achieved even with relatively rough films, spray-coated from non-chlorinated processing solvents.Open Acces

Hepatitis C Virus in Saliva

To investigate the prevalence of hepatitis C virus in saliva, the saliva of a group of haemophiliacs and blood donors, who were previously shown to be anti HCV positive by second generation immunoassay and a recombinant immunoblot, was examined using reverse transcription and the polymerase chain reaction. Both studies indicated that HCV was present in the saliva of a proportion (47.6% and 34% respectively) of each study group. With a view to utilizing the polymerase chain reaction on saliva as a routine diagnostic tool for the detection of HCV, a revised protocol was sought, from the numerous procedures available, to reduce the sophisticated technique to a reproducible, reliable method. All aspects of the entire protocol from beginning to end were considered. HCV RNA extraction was assessed using two commercially available kits, in addition to the more traditional lysis with a chaotrophic agent followed by organic extraction and ethanol precipitation. Two procedures involving separate reverse transcription and the polymerase chain reaction were compared with a combined one step reverse transcription and polymerase chain reaction, to establish a protocol ensuring maximum amplification while reducing the possibility of false positive results. Finally, a sensitive and specific method was sought that would enable accurate detection of the desired product in a non-laborious manner. The appropriateness of the polymerase chain reaction performed on saliva samples as an alternative to blood was evaluated among a group of HCV infected blood donors enrolled in a trial of interferon. Observation and treatment patients were monitored using biochemical and virological markers. Blood and saliva were collected in parallel and tested for HCV RNA. Results indicated that saliva was not a suitable alternative to blood for determining response to treatment. In every study, both whole saliva and oral fluid collected in commercially available devices were obtained. HCV RNA could be detected in both specimen types but often not in parallel. These discrepancies may have resulted from deficiencies in the sample handling protocols. It is likely that specimen processing and storage conditions may influence the stability of HCV RNA. This was evaluated by studying saliva samples collected from known HCV seropositive intravenous drug users, which had been subjected to a number of handling and storage conditions. No single method was shown to be appropriate for both saliva and oral fluid. The evaluation of paired serum and saliva samples for HCV RNA indicated that some individuals had HCV RNA present in saliva but not in blood. DNA sequencing was employed to confirm the presence of HCV RNA in saliva and to genotype the isolates amplified. The presence of different subtypes and even genotypes in the mouth and serum was observed. The source of HCV within the mouth and the potential risk of transmission through saliva are discussed

Non-pharmacological, non-surgical interventions for urinary incontinence in older persons : A systematic review of systematic reviews. The SENATOR project ONTOP series

This work was supported by the European Union Seventh Framework program (FP7/2007–2013) under grant agreement n° 305930Peer reviewedPostprin