Effect of MWCNT addition on the thermal and rheological properties of polymethyl methacrylate bone cement

Multi-walled carbon nanotube (MWCNT)/polymethyl methacrylate (PMMA) composites with loadings ranging from 0.1 to 1.0 wt.% were prepared for use as bone cement. Unfunctionalised, carboxyl and amine functionalised MWCNT were used. Thermal properties were characterised in accordance with the International Standard for acrylic cements, ISO 5833:2002. The rate of reaction exotherm generated and thermal necrosis index (TNI) values were calculated. Polymerisation kinetics were characterised using parallel plate rheology and the exotherm during polymerisation was reduced by ˜4–34%, as a consequence of the MWCNT thermal conductivity. The rate of reaction was significantly altered, such that the setting times of the cements were extended (˜3–24%). Consequently, significant decreases in TNI values (ranging from 3% to 99%) were recorded, which could reduce the exothermic temperatures experienced in vivo and therefore prevent the likelihood of polymerising PMMA cement causing thermally-induced bone tissue necrosis. Thermal data was supported by the rheological characterisation results. Onset of polymerisation for PMMA cement exhibited a strong linear increase as a function of MWCNT loading, however, polymer gelation was not affected to the same degree. It is proposed that the chemically functionalised MWCNT altered PMMA bone cement polymerisation kinetics, reducing the rate of polymerisation, and hence, the reaction exotherm.

Guidelines for the measurement of BCR-ABL1 transcripts in chronic myeloid leukaemia

Molecular testing for the BCR-ABL1 fusion gene by real time quantitative polymerase chain reaction (RT-qPCR) is the most sensitive routine approach for monitoring the response to therapy of patients with chronic myeloid leukaemia. In the context of tyrosine kinase inhibitor (TKI) therapy, the technique is most appropriate for patients who have achieved complete cytogenetic remission and can be used to define specific therapeutic milestones. To achieve this effectively, standardization of the laboratory procedures and the interpretation of results are essential. We present here consensus best practice guidelines for RT-qPCR testing, data interpretation and reporting that have been drawn up and agreed by a consortium of 21 testing laboratories in the United Kingdom and Ireland in accordance with the procedures of the UK Clinical Molecular Genetics Society.

Preservation methods alter stable isotope values in gelatinous zooplankton: implications for interpreting trophic ecology

Jellyfish are increasingly topical within studies of marine food webs. Stable isotope analysis represents a valuable technique to unravel the complex trophic role of these long-overlooked species. In other taxa, sample preservation has been shown to alter the isotopic values of species under consideration, potentially leading to misinterpretation of trophic ecology. To identify potential preservation effects in jellyfish, we collected Aurelia aurita from Strangford Lough (54(o)22'44.73aEuro(3)N, 5(o)32'53.44aEuro(3)W) during May 2009 and processed them using three different methods prior to isotopic analysis (unpreserved, frozen and preserved in ethanol). A distinct preservation effect was found on delta N-15 values: furthermore, preservation also influenced the positive allometric relationship between individual size and delta N-15 values. Conversely, delta C-13 values remained consistent between the three preservation methods, conflicting with previous findings for other invertebrate, fish and mammalian species. These findings have implications for incorporation of jellyfish into marine food webs and remote sampling regimes where preservation of samples is unavoidable.

Diastereoselective assembly of pentanuclear circular helicates

Reaction of a ligand which contains two N-donor and O-donor tridentate domains separated by a 1,3-phenylene spacer unit with Zn2+ ions results in a pentanuclear circular helicate [Zn5(L)5]10+ and this structure persists in both the solid and solution state. The formation of this high nuclearity species is governed by unfavourable steric interactions between the phenyl units which destabilize the simple linear helicate. Incorporation of enantiopure units within the ligand strand controls the diastereoselectivity with up to 80% d.e.

No Evidence that Extended Tracts of Homozygosity are Associated with Alzheimer’s Disease.

We sought to investigate the contribution of extended runs of homozygosity in a genome-wide association dataset of 1,955 Alzheimer's disease cases and 955 elderly screened controls genotyped for 529,205 autosomal single nucleotide polymorphisms. Tracts of homozygosity may mark regions inherited from a common ancestor and could reflect disease loci if observed more frequently in cases than controls. We found no excess of homozygous tracts in Alzheimer's disease cases compared to controls and no individual run of homozygosity showed association to Alzheimer's disease.

Fatigue and biocompatibility properties of a poly(methyl methacrylate) bone cement with multi-walled carbon nanotubes

Composites of multi-walled carbon nanotubes (MWCNT) of varied functionality (unfunctionalised and carboxyl and amine functionalised) with polymethyl methacrylate (PMMA) were prepared for use as a bone cement. The MWCNT loadings ranged from 0.1 to 1.0 wt.%. The fatigue properties of these MWCNT–PMMA bone cements were characterised at MWCNT loading levels of 0.1 and 0.25 wt.% with the type and wt.% loading of MWCNT used having a strong influence on the number of cycles to failure. The morphology and degree of dispersion of the MWCNT in the PMMA matrix at different length scales were examined using field emission scanning electron microscopy. Improvements in the fatigue properties were attributed to the MWCNT arresting/retarding crack propagation through the cement through a bridging effect and hindering crack propagation. MWCNT agglomerates were evident within the cement microstructure and the degree of agglomeration was dependent on the level of loading and functionality of the MWCNT. The biocompatibility of the MWCNT–PMMA cements at MWCNT loading levels upto 1.0 wt.% was determined by means of established biological cell culture assays using MG-63 cells. Cell attachment after 4 h was determined using the crystal violet staining assay. Cell viability was determined over 7 days in vitro using the standard colorimetric MTT assay. Confocal scanning laser microscopy and SEM analysis was also used to assess cell morphology on the various substrates.

The Veil of Kyoto and the politics of greenhouse gas mitigation in Australia

This paper investigates how the Kyoto Protocol has framed political discourse and policy development of greenhouse gas mitigation in Australia. We argue that ‘Kyoto’ has created a veil over the climate issue in Australia in a number of ways. Firstly, its symbolic power has distracted attention from actual environmental outcomes while its accounting rules obscure the real level of carbon emissions and structural trends at the nation-state level. Secondly, a public policy tendency to commit to far off emission targets as a compromise to implementing legislation in the short term has also emerged on the back of Kyoto-style targets. Thirdly, Kyoto’s international flexibility mechanisms can lead to the diversion of mitigation investment away from the nation-state implementing carbon legislation. A final concern of the Kyoto approach is how it has shifted focus away from Australia as the world’s largest coal exporter towards China, its primary customer. While we recognise the crucial role aspirational targets and timetables play in capturing the imagination and coordinating action across nations, our central theme is that ‘Kyoto’ has overshadowed the implementation of other policies in Australia. Understanding how ‘Kyoto’ has framed debate and policy is thus crucial to promoting environmentally effective mitigation measures as nation-states move forward from COP15 in Copenhagen to forge a post-Kyoto international agreement. Recent elections in 2009 in Japan and America and developments at COP15 suggest positive scope for international action on climate change. However, the lesson from the 2007 election and subsequent events in Australia is a caution against elevating the symbolism of ‘Kyoto-style’ targets and timetables above the need for implementation of mitigation policies at the nation-state level

Late Pleistocene history of turbidite sedimentation in a submarine canyon off the northern Great Barrier Reef, Australia

Cores from slopes east of the Great Barrier Reef (GBR) challenge traditional models for sedimentation on tropical mixed siliciclastic-carbonate margins. However, satisfactory explanations of sediment accumulation on this archetypal margin that include both hemipelagic and turbidite sedimentation remain elusive, as submarine canyons and their role in delivering coarse-grained turbidite deposits, are poorly understood. Towards addressing this problem we investigated the shelf and canyon system bordering the northern Ribbon Reefs and reconstructed the history of turbidite deposition since the Late Pleistocene. High-resolution bathymetric and seismic data show a large paleo-channel system that crosses the shelf before connecting with the canyons via the inter-reef passages between the Ribbon Reefs. High-resolution bathymetry of the canyon axis reveals a complex and active system of channels, sand waves, and local submarine landslides. Multi-proxy examination of three cores from down the axis of the canyon system reveals 18 turbidites and debrites, interlayered with hemipelagic muds, that are derived from a mix of shallow and deep sources. Twenty radiocarbon ages indicate that siliciclastic-dominated and mixed turbidites only occur prior to 31 ka during Marine Isotope Stage (MIS) 3, while carbonate-dominated turbidites are well established by 11 ka in MIS1 until as recently as 1.2 ka. The apparent lack of siliciclastic-dominated turbidites and presence of only a few carbonate-dominated turbidites during the MIS2 lowstand are not consistent with generic models of margin sedimentation but might also reflect a gap in the turbidite record. These data suggest that turbidite sedimentation in the Ribbon Reef canyons, probably reflects the complex relationship between the prolonged period (> 25 ka) of MIS3 millennial sea level changes and local factors such as the shelf, inter-reef passage depth, canyon morphology and different sediment sources. On this basis we predict that the spatial and temporal patterns of turbidite sedimentation could vary considerably along the length of the GBR margin.