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The ANSTO isotope cycling system
No full textA number of electronic systems are used on the ANTARES accelerator at ANSTO to implement its fast cycling accelerator mass spectrometry (AMS) capability. The fast cycling system was originally installed and commissioned in 1993 and has recently been updated. This paper describes the more significant of the electronic systems, such as the controller ("sequencer"), the high-voltage power supply ("bouncer"), the fast electrostatic beam chopper, and those used for measurement of the pulsed ion beam current. The sequencer, a programmable 15-bit digital pulse generator, generates the timing and sequencing of the control signals for bouncing voltage selection, beam chopping, Faraday cup current measurement, and rare isotope event measurement. The new sequencer is implemented using a National Instruments FPGA (field programmable gate array) card, programmed using LabVIEW 2010. This device has the benefits of host CPU-independent operation, simple interfacing (PCI), a small footprint, off-the-shelf availability at modest cost, and ease of functionality upgrade. The sequencer provides 15 synchronous digital signals, whose "on" and "off" transitions can be independently specified, in both number and time, with a time resolution of between 0.5 and 128 μs, and with the total duration between repetitions adjustable between 65.5 ms and 8.4 s per cycle. It is hosted by a generic PC because of the low-cost and ubiquity of these. The stand-alone FPGA-based approach ensures that the sequencer determinism is unaffected by processes executing in the host CPU. © 2013 Arizona Board of Regents on behalf of the University of Arizon
Evaluating irradiation dose for sterility induction and quality control of mass-produced fruit fly cactrocera tryoni (Diptera: Tephritidae)
No full textThe sterile insect technique has been routinely used to eradicate fruit fly Bactrocera tryoni (Froggatt) incursions. This study considers whether fly quality in a mass-rearing facility can be improved by reducing irradiation doses, without sacrificing reproductive sterility. Pupae were exposed to one of five target irradiation dose ranges: 0, 40–45, 50–55, 60–65, and 70–75 Gy. Pupae were then assessed using routine quality control measures: flight ability, sex ratio, longevity under nutritional stress, emergence, and reproductive sterility. Irradiation did not have a significant effect on flight ability or sex ratio tests. Longevity under nutritional stress was significantly increased at 70–75 Gy, but no other doses differed from 0 Gy. Emergence was slightly reduced in the 50–55, 60–65, and 70–75 Gy treatments, but 40–45 Gy treatments did not differ from 0 Gy, though confounding temporal factors complicate interpretation. Reproductive sterility remained acceptable (>99.5%) for all doses— 40–45 Gy (99.78%), 50–55 Gy (100%), 60–65 Gy (100%), and 70–75 Gy (99.99%). We recommend that B. tryoni used in sterile insect technique releases be irradiated at a target dose of 50–55 Gy, providing improved quality and undiminished sterility in comparison with the current 70–75 Gy standard while also providing a substantial buffer against risk of under dosing. © 2014, Oxford University Pres
Protein-ligand and membrane-ligand interactions in pharmacology: the case of the translocator protein (TSPO)
No full textThe targets of many small molecule drugs are membrane proteins, and traditionally the focus of pharmacology is on the interaction between such receptors and their small molecule drug ligands. However, the lipid membranes of cells and organelles are increasingly appreciated as diverse and dynamic structures that also specifically interact with small molecule drugs and peptides, causing profound changes in the properties of these membranes, and modulating the function of the membrane and the proteins within it. Drug-membrane interactions are likely to have a role in both the therapeutic and toxic activity of a variety of compounds, and their role in the overall pharmacological effect of a drug needs to be understood more clearly. This is the case for the 18 kDa translocator protein (TSPO) and its ligands, where functions that were established based on pharmacological studies are being called into question. Re-examining the putative functions of the TSPO and the effects of its ligands reveals a need to consider in more detail the interplay between protein-ligand and membrane-ligand interactions, and the modulatory relationship between TSPO and the lipid membrane. © 2015 Elsevier Ltd
Vortex-glass phase transition and enhanced flux pinning in C4+-irradiated BaFe1.9Ni0.1As2 superconducting single crystals
No full textWe report the effects of C4+-irradiation on the superconducting properties of BaFe1.9Ni0.1As2 single crystal. The BaFe1.9Ni0.1As2 single crystal before and after C4+-irradiation was characterized by magnetic, magneto-transport and magneto-optical techniques over a wide range of magnetic fields (0–13 T) and temperatures (2–200 K). We demonstrate that the C4+-irradiation significantly enhances the in-field critical current density (by a factor of up to 1.5 at 5 K) and induces enhanced flux jumping at 2 K, with only a small degradation (by 0.5 K) of the critical temperature, Tc. The vortex phase diagram describing the evolution of the vortex-glass transition temperature with magnetic field and the upper critical field has been resolved for the C4+-irradiated sample. For temperatures below Tc, the resistivity curves and the pinning potential were found to show good scaling, using a modified model for vortex-liquid resistivity. The vortex state is three dimensional at temperatures lower than a characteristic temperature. Good agreement between the thermally activated flux flow model, which is usually employed to account for the resistivity in the vortex-liquid region, and the modified vortex-liquid model, has been observed.
© 2013 IOP Publishin
The influence of crystal structure on ion-irradiation tolerance in the Sm(x)Yb(2-x)TiO5 series
No full textThis ion-irradiation study covers the four major crystal structure types in the Ln2TiO5 series (Ln = lanthanide), namely orthorhombic Pnma, hexagonal P63/mmc, cubic (pyrochlore-like) Fd-3m and cubic (fluorite-like) Fm-3m. This is the first systematic examination of the complete Ln2TiO5 crystal system and the first reported examination of the hexagonal structure. A series of samples, based on the stoichiometry Sm(x)Yb(2-x)TiO5 (where x = 2, 1.4, 1, 0.6, and 0) have been irradiated using 1 MeV Kr2+ ions and characterised in-situ using a transmission electron microscope. Two quantities are used to define ion-irradiation tolerance: critical dose of amorphisation (Dc), which is the irradiating ion dose required for a crystalline to amorphous transition, and the critical temperature (Tc), above which the sample cannot be rendered amorphous by ion irradiation. The structure type plus elements of bonding are correlated to ion-irradiation tolerance. The cubic phases, Yb2TiO5 and Sm0.6Yb1.4TiO5, were found to be the most radiation tolerant, with Tc values of 479 and 697 K respectively. The improved radiation tolerance with a change in symmetry to cubic is consistent with previous studies of similar compounds. © 2016 Elsevier B.V
3d transition metal complexes with a julolidine–quinoline based ligand: structures, spectroscopy and optical properties
No full textA Schiff base type ligand with the combination of the julolidine and the quinoline groups has been reported as a potential chemosensor in detecting the cobalt(II) ion among other heavy and transition metal ions in solution. However, no crystal structure of such a ligand with any metal ions has been reported. In this work, its complexation with 3d transition metal ions (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) has been investigated with five new complexes being synthesised, and spectroscopically and structurally characterised. [Mn2L2(CH3OH)2(CH3COO)2]•CH3OH (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} shows a dinuclear structure with two Mn : L : acetate (1 : 1 : 1) units bridged by two methanol molecules. [CoL2(NO3)]•CH3OH•H2O (2) and [NiL2]•H2O (3) exhibit mononuclear structures with a Co : L or Ni : L ratio of 1 : 2. [CuL(CH3COO)]•1/3CH3OH (4) demonstrates a mononuclear structure and the Cu ion has a square planar coordination polyhedron with a L ligand and a highly non-symmetrical acetate anion. [Zn2L2(CH3COO)2]•CH3OH (5) has two types of dinuclear units, both with two ZnL units bridged by two acetate anions but in three different bridging coordination modes. Their vibrational modes, absorption and photoluminescence properties have also been investigated. © 2016 the Partner Organisation
Lightning-induced shock lamellae in quartz
No full textUsing transmission electron microscopy we show that planar deformation lamellae occur within quartz in the substrate of a rock fulgurite, i.e., a lightning-derived glass. These lamellae exist only in a narrow zone adjacent to the quartz/fulgurite boundary and are comparable to planar deformation features (“shock lamellae”) caused by hypervelocity impacts of extra-terrestrial objects. Our observations strongly suggest that the lamellae described here have been formed as a result of the fulgurite-producing lightning strike. This event must have generated a transient pressure pulse, whose magnitude, however, is uncertain at this stage. © 2015 GeoScience Worl
Influence of Particle Mass and Flow Rate on Plasma Polymerized Allylamine Coated Quartz Particles for Humic Acid Removal
No full textPlasma polymerized allylamine films were deposited onto quartz particles for the removal of humic acid, a common water contaminant. Allylamine flow rates of 6.6 and 11.5 standard cubic centrimetres per minute (sccm) were used and the mass of particles varied from 50 to 500 g. At an allylamine flow rate of 6.6 sccm, the atomic concentration of carbon and nitrogen decreased with increasing mass of particles. The isoelectric point and number of positively charged amine groups increased as the allylamine flow rate was increased and/or the mass of particles coated was decreased. Greater humic acid removal was achieved by increasing the allylamine flow rate and/or decreasing the mass of particles coated, which will have important implications for its use in water. © 2014 John Wiley and Sons Inc
What approach to brain partial volume correction is best for PET/MRI?
No full textMany partial volume correction approaches make use of anatomical information, readily available in PET/MRI systems but it is not clear what approach is best. Seven novel approaches to partial volume correction were evaluated, including several post-reconstruction methods and several reconstruction methods that incorporate anatomical information. These were compared with an MRI-independent approach (reblurred van Cittert ) and uncorrected data. Monte Carlo PET data were generated for activity distributions representing both 18F FDG and amyloid tracer uptake. Post-reconstruction methods provided the best recovery with ideal segmentation but were particularly sensitive to mis-registration. Alternative approaches performed better in maintaining lesion contrast (unseen in MRI) with good noise control. These were also relatively insensitive to mis-registration errors. The choice of method will depend on the specific application and reliability of segmentation and registration algorithms. (c) 2012 Elsevier Science B.V
Mechanical properties and adhesion characteristics of hybrid sol–gel thin films
No full textThe hardness and Young's modulus of organic–inorganic hybrid coatings, synthesised using sol–gel technology, deposited on silicon and copper were determined using indentations at low forces with a spherical tipped indenter and found to depend strongly on the size of the organic substituent. The indentation creep response of the coating systems was compared based on fast loading rates and for different times at maximum load. The adhesion characteristics of the coatings on copper were examined to ascertain the influence of the organic substituents on the film cracking behaviour and debond tendencies. For this purpose, coated tensile test specimens were strained uniaxially in a universal testing machine while the surface was examined using an optical microscope. The mechanical response was analysed from the multiple cracking patterns observed and the extent of film delamination from the underlying substrate. The results indicate that the interfacial adhesion and film toughness are dramatically affected by the nature of the organic substituent. © 2004 Elsevier B.