Tailoring gas sensing properties of multi-walled carbon nanotubes by in situ modification with Si,P, and N

A simple method for the synthesis of multi-walled carbon nanotubes (MWCNTs) containing Si, P–N and N is reported, and their gas sensing properties were investigated. The MWCNTs were synthesised by the thermal decomposition of aerosols containing mixtures of ferrocene/triphenylsilane, ferrocene/triphenylphosphine/benzylamine, and ferrocene/benzylamine/toluene. Electron microscopy studies revealed that the addition of Si, P, and N alters the structure of CNTs dramatically. Gas sensing experiments were carried out using Si, P–N, N-containing MWCNTs, and were compared with pure MWCNTs synthesised at similar experimental conditions. These experiments showed that the gas sensitivity and selectivity of CNT-based sensors can be indeed tailored without any post-processing of the raw nanotubes. The efficient in situ tailoring of nanotube properties and functionality are important for nanotubes to become viable materials at the industrial scale where low cost processes are required.     

A Comparative Evaluation of Short-Term Streamflow Forecasting Using Time Series Analysis and Rainfall-Runoff Models in eWater Source

Over the past few decades, many numerical streamflow prediction techniques using observed time series (TS) have been developed and widely used in water resources planning and management. Recent advances in quantitative rainfall forecasting by numerical weather prediction (NWP) models have made it possible to produce improved streamflow forecasts using continuous rainfall-runoff (RR) models. In the absence of a suitable integrated system of NWP, RR and river system models, river operators in Australia mostly use spreadsheet-based tools to forecast streamflow using gauged records. The eWater Cooperative Research Centre of Australia has recently developed a new generation software package called eWater Source, which allows a seamless integration of continuous RR and river system models for operational and planning purposes. This paper presents the outcomes of a study that was carried out using Source for a comparative evaluation of streamflow forecasting by several well-known TS based linear techniques and RR models in two selected sub-basins in the upper Murray river system of the Murray-Darling Basin in Australia. The results were compared with the actual forecasts made by the Murray River operators and the observed data. The results show that while streamflow forecasts by the river operators were reasonably accurate up to day 3 and traditional TS based approaches were reasonably accurate up to 2?days. Well calibrated RR models can provide better forecasts for longer periods when using high quality quantitative precipitation forecasts. The river operators tended to underestimate large magnitude flows.     

Fault detection and characterisation in Pressurised Water Reactors using real-time simulations

The use of real-time plant simulators running in parallel with a nuclear plant to predict the control system behaviour and highlighting unexpected plant behaviour is presented. The study is performed on a 910 MW Generation II Framatome Pressurised Water Reactor model and simulator. By simulating the plant behaviour in real-time whilst comparing it with the real-time transient the plant is following, a complete second set of expected control operations and simulated plant measurements is generated. This enables the calculation of the unknown set of variables introduced into the plant as a fault condition. The benefit of such a system is that plant faults that are too small to detect (especially during transients when the plant operating point is moving around) can be identified as unexpected or faulty plant behaviour. The behaviour of the control system is also continually predicted so the effect of the control system compensating for fault symptoms (which in most cases hides the fault condition) is used to characterise the fault as a control variable acting on the plant. The approach is illustrated by simulating a specific fault, small enough to go undetected for an extended period of time, during a typical transient. This is continually compared with a plant simulation, simulating the same transient without the fault. Using the described methodology, the fault is detected and characterised long before the plant safety is jeopardised or the fault is detected by the conventional protection system.     

Polymeric display of immunogenic epitopes from herpes simplex virus and transmissible gastroenteritis virus surface proteins on an enteroadherent fimbria

Polydnaviruses are the only known group of mutualistic viruses. They are required for successful parasitization in many braconid and ichneumonid parasitoids. The intimacy of this mutualistic association is indicated by the integration and vertical transmission of polydnaviruses in wasp genomes and by their asymptomatic, developmentally regulated replication. The evolution of this mutualism raises several interesting issues that require a better understanding of the viral genome and viral replication. To develop probes for virus replication and morphogenesis, we have begun to characterize several viral structural proteins. A 699 bp cDNA encoding the p12 viral structural protein was cloned and sequenced. The p12 gene localizes to viral segment Y and encodes a predicted protein of 92 amino acids that does not encode a signal peptide and is unrelated to known peptide or nucleic acid sequences. The p12 mRNA is detected at the onset of virus replication. mRNA titers increase with increasing rates of virus replication. Polyclonal antisera raised against histidine-tagged p12 protein expressed in bacteria reacted specifically with the p12 polypeptide in Western blots of CsPDV virions. The p12 polypeptide was not detected in non-replicative wasp or lepidopteran tissues by Western blot analyses but was readily detected in protein extracts of wasp ovaries. The data indicate that the p12 gene is a viral gene encoding a virion protein and provides a specific probe for virus replication that will be useful for studying the evolution of this group of mutualistic viruses.     

18F]fluoroethoxy-benzovesamicol, a PET radiotracer for the vesicular acetylcholine transporter and cholinergic synapses

CACO-2 BBE was used to determine the response of a gastrointestinal epithelium to tumor necrosis factor-alpha (TNF). Incubation of CACO-2 BBE with TNF did not produce any effect on transepithelial resistance (TER) within the first 6 hr but resulted in a 40-50% reduction in TER and a 30% decrease in 1SC (short circuit current) relative to time-matched control at 24 hr. The decrease in TER was sustained up to 1 week following treatment with TNF and was not associated with a significant increase in the transepithelial flux of [14C]-D-mannitol or the penetration of ruthenium red into the lateral intercellular space. Dilution potential and transepithelial 22Na+ flux studies demonstrated that TNF-treatment of CACO-2 BBE cell sheets increased the paracellular permeability of the epithelium to Na+ and Cl-. The increased transepithelial permeability did not associate with an increase in the incidence of apoptosis. However, there was a TNF-dependent increase in [3H]-thymidine labeling that was not accompanied by a change in DNA content of the cell sheet. The increase in transepithelial permeability was concluded to be across the tight junction because: (i) 1 mM apical amiloride reduced the basolateral to apical flux of 22Na+, and (ii) dilution potential studies revealed a bidirectionally increased permeability to both Na+ and Cl-. These data suggest that the increase in transepithelial permeability across TNF-treated CACO-2 BBE cell sheets arises from an alteration in the charge selectivity of the paracellular conductive pathway that is not accompanied by a change in its size selectivity.