Biogenic volatile organic compounds in the ambient air and plant emissions of a Tasmanian native forest, and the relationship between emission rates and essential oil content

The biogenic volatile organic compounds (VOCs) in the ambient air of the Hobart Air Shed and in the emissions from selected Tasmanian native trees and understorey shrubs were measured. The emission rates were then related to the plants' essential oils content, which had been extracted by hydro-distillation. The VOCs in the ambient air of native forests have not previously been studied in Australia. This study used multi-adsorbent cartridge adsorption/thermal desorption and Gas Chromatography-Mass Spectrometry. The type, quantity, source and variation of the VOCs were investigated. The concentration of VOCs in the atmosphere surrounding vegetation in the Hobart Air Shed was determined. In all, 129 compounds of eight classes were detected. Ofthese, 11 compounds were National Pollutant Inventory substances and 32 were considered biogenic; however, this estimate is conservative. The concentration of total VOCs in these ambient air measurements varied between 4.43 x 10- 10 g L- 1 and 3.04 x 10-9 g L-1 depending on the site sampled and meteorological conditions. The relative standard deviation ranged between 3.50/0 and 51.8% in the dual air samples. The emission rates of VOCs were determined for 14 plant species within the Hobart Air Shed, using an enclosure bottle technique. In all, 284 compounds of 10 classes were detected. Emission rates varied between 1.98 x 10-8 and 5.43 x 10-6 g g-l (wet weight) h-1 depending on the species sampled and prevailing conditions. The relative standard deviation was estimated to be 31.1 %. The VOC emission rate for the entire eucalypt forest in Tasmania was estimated as 8200 kg h-1 and for the Hobart Air Shed 59 kg h-1. The error could be as large as a factor of three. The essential oil compositions of the species examined were identified. Linear relationships between VOC oil concentration and emission rates were found in 10 of the 13 analyses

Does a novel X-ray imaging technology provide a substantial radiation dose reduction for patients in trans-catheter aortic valve implantation procedures?

Purpose: Modern interventional X-ray equipment employs image processing to permit reduction in radiation whilst retaining sufficient image quality. The aim of this study was to investigate whether our recently-installed system (AlluraClarity, Philips Healthcare) which contains advanced real-time image noise reduction algorithms and anatomy-specific X-ray optimization (beam filtering, grid switch, pulse width, spot size, detector and image processing engine), affected patient procedure dose and overall procedure duration in routine trans-catheter aortic valve implantation (TAVI) procedures. Methods: Patient dose for 42 TAVI patients from the AlluraClarity cardiac catheterisation lab and from a reference system (Axiom Artis, Siemens Healthcare) in the same cardiology department was recorded. Median values from the two X-ray systems were compared using the Wilcoxon statistical test. Results: Total patient procedure dose medians were 4016 and 7088 cGy cm2 from the AlluraClarity and reference systems respectively. AlluraClarity median patient doses were 3405 cGy cm2 and 783.5 cGy cm2 from fluoroscopy and digital image acquisition respectively. Reference median patient doses were 4928 cGy cm2 and 2511 cGy cm2 from fluoroscopy and digital image acquisition respectively. All differences in patient dose were significant at the 5% level. Median total fluoroscopy times [min:sec] were 19:57 and 20:20 for the AlluraClarity and reference systems respectively. Conclusion: The AlluraClarity cardiac catheterisation lab had 43% lower total patient procedure dose for TAVI patients than the reference lab; fluoroscopy and digital image acquisition doses were 31% and 69% lower respectively. In terms of total fluoroscopy time, there was no statistically significant difference between the two labs

The effects of pre-bond moisture on the fracture behaviour of adhesively-bonded composite joints

Accepted versio

A novel route to Pt-Bi2O3 composite thin films and their application in photo-reduction of water

A novel homoleptic bismuth(III) β-diketonate (dibenzoylmethane – dbm) complex [Bi(dbm)3]2 has been used as a precursor to thin films of crystalline β-Bi2O3, and hexachloroplatinic acid (H2PtCl6·6H2O) has been demonstrated as a suitable precursor for deposition of platinum nanoparticles, both deposited via aerosol-assisted chemical vapour deposition (AACVD). Thin films of Pt–Bi2O3 were co-deposited from a mixture of [Bi(dbm)3]2 and H2PtCl6·6H2O; the introduction of Pt particles into β-Bi2O3 causes hydrogen to be evolved during photolysis of water over the composite material, a property not found for Pt particles or β-Bi2O3 alone

A magnetically collimated jet from an evolved star

Planetary nebulae often have asymmetric shapes, which could arise due to collimated jets from evolved stars before evolution to the planetary nebula phase. The source of jet collimation in these stars is unknown. Magnetic fields are thought to collimate outflows that are observed in many other astrophysical sources, such as active galactic nuclei and proto-stars, although hitherto there are no direct observations of both the magnetic field direction and strength in any collimated jet. Theoretical models have shown that magnetic fields could also be the dominant source of collimation of jet in evolved stars. Here we report measurements of the polarization of water vapour masers that trace the precessing jet emanating from the asymptotic giant branch star W43A at 2.6 kpc from the Sun, which is undergoing rapid evolution into a planetary nebula. The masers occur in two clusters at opposing tips of the jets, ~1,000 AU from the star. We find direct evidence that the magnetic field is collimating the jet.Comment: Published in Nature 440 (March 2nd 2006). High-res figures can be found at http://www.jb.man.ac.uk/~wouter/papers/w43a/w43a.htm