Adelaide Microscopy publications

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Microfibril-associated glycoprotein-1 (MAGP-1) is specifically located on the beads of the beaded-filament structure for fibrillin-containing microfibrils as visualized by the rotary shadowing technique
(Histochemical Society, 1996) Henderson, M.; Polewski, R.; Fanning, J.; Gibson, M.
This study used immunoelectron microscopic techniques to define the ultrastructural location of MAGP-1 on the fibrillin-containing microfibrils of the ocular zonule. A specific anti-MAGP-1 monoclonal antibody (MAb), 11B, was produced that did not crossreact with fibrillin-1 or other microfibrillar proteins. MAb 11B was shown by immunofluorescence to localize intensely to zonular tissue. Postembedding immunoelectron microscopy showed that MAGP-1 was associated with microfibrils throughout the zonule, with the exception of a narrow band of microfibrils at the junction with the lens capsule. With preembedding labeling, the anti-MAGP-1 MAb was found to localize in a crossbanding pattern, at intervals of about 50 nm, to microfibrils throughout the zonule and along bundles of microfibrils in surrounding vitreous tissue. Rotary shadowing of isolated microfibrils showed a "beads on a string" morphology with a periodicity of about 50 nm. With immunogold labeling, the anti-MAGP-1 antibody specifically localized on the beads in a symmetrical manner. Occasionally two gold partides were attached to the same bead, suggesting that multiple MAGP-1 molecules were present in the structure. The results indicate that MAGP-1 is intimately and regularly associated with the bead regions of fibrillin-containing microfibrils. The findings are consistent with a major structural role for MAGP-1 in microfibril biology.
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Cell death in LMA-affected wheat aleurone layers
(Royal Australian Chemical Institute, 2003) Mrva, K.; Blesing, M.; Mares, D.; Cereals 2003 (53rd : 2003 : Glenelg, South Australia); Black, C.; Panozzo, J.
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Effects of chemical functional groups on the polymer adsorption behavior onto titania pigment particles
(Academic Press Inc Elsevier Science, 2004) Farrokhpay, Saeed; Morris, G.; Fornasiero, Daniel; Self, Peter Geoffrey; Adelaide Microscopy
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Breeding system in a population of Trigonella balansae (Leguminosae)
(Oxford Univ Press, 2004) Nair, R.; Dundas, I.; Blesing, M.; Verlin, D.; Waterhouse, L.; Dowling, K.
Background and Aims Although some taxonomic studies in the genus Trigonella have been conducted, there has been no concerted effort to study the breeding system. This paper examines the floral structure and pollination system in a population of T. balansae, an annual pasture legume. Methods Floral morphology, hand and vector pollination, stigma receptivity, pollen tube growth, using scanning electron and fluorescence microscopy, were conducted. Key Results Measurements of floral structure from before to after anthesis indicates an inability for T. balansae to self-pollinate and a requirement for an external vector to effectively transfer pollen from the anthers onto the stigmas of this species. Seed set can be obtained by hand or honeybee manipulation of T. balansae flowers. Conclusions Trigonella balansae is a self-compatible species, but which requires vectors such as honeybees to bring about pollination.
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The origin of the color of pearls in iridescence from nano-composite structures of the nacre
(Mineralogical Soc Amer, 2004) Snow, M.; Pring, A.; Self, P.; Losic, D.; Shapter, J.
The origin of the variety of body colors exhibited by South Sea Pearls is in part due to a newly recognized structure of the nacre, the edge-band structure, which gives rise to interference colors characteristic of its width. With the pearl oyster, Pinctada maxima, the colors include a range of silver tones, creams, yellows, and gold in various degrees of color saturation. We establish here that the primary body color of P. maxima pearls arises from the interference of light within the binding regions of the aragonite tiles. The tile faces terminate in a fissured nano-composite structure containing organic matrix within the margin of the aragonite tiles. This edge-band structure gives rise to an optical film formed of organic matrix in aragonite. The TEM images show that the edge-band structure width increases progressively from 74(4) nm in a silver pearl, to 80(4) nm in a cream pearl, and to 90(4) nm in a gold pearl. These colors are the first-order Newton's colors, which, when mixed with the specular reflection of the nacre and modified by any pigmentation present, give rise to the body color of pearls. The non-metallic whiter pearls more commonly seen can be accounted for by disorder of this structure leading to unsaturation of the color.
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Influence of polymer functional group architecture on titania pigment dispersion
(Elsevier Science BV, 2005) Farrokhpay, Saeed; Morris, G.; Fornasiero, Daniel; Self, Peter Geoffrey; Adelaide Microscopy
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Titania pigment particles dispersion in water-based paint films
(FEDERATION SOC COATINGS TECHNOLOGY, 2006) Farrokhpay, Saeed; Morris, Gayle E.; Fornasiero, Daniel; Self, Peter A. F.; Adelaide Microscopy
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Density changes around phosphorus granules and fluid bands in a calcareous soil
(Soil Sci Soc Amer, 2006) Hettiarachchi, G.; Lombi, E.; McLaughlin, M.; Chittleborough, D.; Self, P.
We employed x-ray computed microtomography (X-ray CT) to observe differences in moisture around fertilizer P granules (monoammonium phosphate, MAP) versus injection zones of fluid P fertilizer (technical grade monoammonium phosphate, TG MAP) in a calcareous soil over time. X-ray CT allows nondestructive visualization of small columns containing soils and fertilizers. We were able to visualize the increase in density around the highly hygroscopic fertilizer granule over time. It appeared that both water flow toward the granule and precipitation of P could be responsible for the development of about 1 mm thick high density zone immediately adjacent to the granule. The mass flow of water toward the granule may have slowed or restricted the diffusion of fertilizer P from the granule, thus increasing the chances for P fixation through precipitation reactions. Also, the granule became less dense with time indicating the progress of granule dissolution. In contrast, injection of fluid fertilizer (TG-MAP) in soil did not result in moisture changes over time as evidenced by a lack of X-ray CT detectable density differences in the soil column. These data support previous findings that, when P is supplied in granular form, P diffusion and isotopic lability in calcareous soils are reduced compared with equivalent liquid fertilizer formulations, probably due to precipitation reactions induced by osmotically induced flow of soil moisture into the fertilizer granule.
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Plant CLE peptides from two distinct functional classes synergistically induce division of vascular cells
(Natl Acad Sciences, 2008) Whitford, R.; Fernandez, A.; De Groodt, R.; Ortega, E.; Hilson, P.
The Clavata3 (CLV3)/endosperm surrounding region (CLE) signaling peptides are encoded in large plant gene families. CLV3 and the other A-type CLE peptides promote cell differentiation in root and shoot apical meristems, whereas the B-type peptides (CLE41–CLE44) do not. Instead, CLE41 inhibits the differentiation of Zinnia elegans tracheary elements. To test whether CLE genes might code for antagonistic or synergistic functions, peptides from both types were combined through overexpression within or application onto Arabidopsis thaliana seedlings. The CLE41 peptide (CLE41p) promoted proliferation of vascular cells, although delaying differentiation into phloem and xylem cell lineages. Application of CLE41p or overexpression of CLE41 did not suppress the terminal differentiation of the root and shoot apices triggered by A-type CLE peptides. However, in combination, A-type peptides enhanced all of the phenotypes associated with CLE41 gain-of-function, leading to massive proliferation of vascular cells. This proliferation relied on auxin signaling because it was enhanced by exogenous application of a synthetic auxin, decreased by an auxin polar transport inhibitor, and abolished by a mutation in the Monopteros auxin response factor. These findings highlight that vascular patterning is a process controlled in time and space by different CLE peptides in conjunction with hormonal signaling.
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Gun shot residue analysis and distinguishing the formation of GSR from environmental particles
(Springer-Verlag, 2009) Sarvas, I.; Kobus, H.; Green, L.; Kotula, P.; Wuhrer, R.; Adelaide Microscopy
Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009
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Evaluation of high power ultrasound porous cleaning efficacy in American oak wine barrels using X-ray tomography
(Elsevier BV, 2011) Porter, G.; Lewis, A.; Barnes, M.; Williams, R.
This study presents a novel cleaning application which investigates the ability of high power ultrasound (HPU) to remove crystalline potassium hydrogen tartrate sediment from the porous structure of American oak wine barrels. Tartrate deposits within stave samples were imaged by X-ray tomography. Volumetric reconstruction software enabled tartrate volumes to be quantified after successive treatments at varied solvent temperatures by re-imaging samples and modelling obtained tomographic projections. The removal of microscopic tartrate crystals from stave surfaces by HPU was also investigated. It was demonstrated that HPU can significantly remove tartrate deposits from the first two millimetres of oak surfaces however such ability at depth 2-8 mm was not reproducible. An average of 89% total tartrate volume was removed from the surface layer in the first treatment but was further increased to 98% by increasing solvent temperature and irradiation time. A highly significant removal of stave surface tartrate crystals with this cleaning technique was also demonstrated at temperatures studied. Industrial Relevance: Fouling of the interior surface and porous membranes of wine barrels is a significant problem encountered by every wine maker. This problem occurs in white and red wine production by precipitated tartrate crystallisation which forms a robust scale inhibiting oak compound extraction by wine, additionally harbouring spoilage microorganisms and contaminants. Tartrate scale is typically removed by spray techniques, but often with less than optimal results. Ultrasonic cleaning is a well established practice in many industries; this industrial scaled study demonstrates a high power ultrasonic (4 kW/20 kHz) application in the effective and efficient removal of tartrate sediment from the surface of staves, and to a depth of two millimetres, with a relatively short treatment time (12 min) at mild temperatures (40-60 °C). Such outcomes are expected to benefit the wine industry, consumers and environment by increased barrel functionality and less frequent replacement, an improvement in oak compound extraction rate and concentration in wine, increased product quality, as well as the minimisation of cleaning water consumption and excessive use of preservatives. © 2011 Elsevier Ltd. All rights reserved.
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Inclusion-localised crystal-plasticity, dynamic porosity, and fast-diffusion pathway generation in zircon
(Pergamon-Elsevier Science Ltd, 2012) Timms, N.; Reddy, S.; John, D.; Green, L.; Muhling, J.; Adelaide Microscopy
A population of oscillatory zoned, igneous zircon grains in a Javanese andesite contains fluid and mineral inclusions (up to 10μm across) trapped during zircon growth. Orientation contrast imaging and orientation mapping by electron backscatter diffraction reveal that crystal-plastic deformation overprints growth zoning and has localized around 1-10μm pores and inclusions. Cumulative crystallographic misorientation of up to 25° around pores and inclusions in zircon is predominantly accommodated by low-angle (<5°) orientation boundaries, with few free dislocations in subgrain interiors. Low-angle boundaries are curved, with multiple orientation segments at the sub-micrometer scale. Misorientation axes associated with the most common boundaries align with the zircon c-axis and are consistent with dislocation creep dominated by <100>(010) slip. A distinctly different population of sub-micron pores is present along subgrain boundaries and their triple junctions. These are interpreted to have formed as a geometric consequence of dislocation interaction during crystal-plasticity. Dislocation creep microstructures are spatially related to differences in cathodoluminescence spectra that indicate variations in the abundance of CL-active rare earth elements. The extent of the modification suggests deformation-related fast-pathway diffusion distances that are over five orders of magnitude greater than expected for volume diffusion. This enhanced diffusion is interpreted to represent a combination of fast-diffusion pathways associated with creep cavitation, dislocations and along low-angle boundaries. These new data indicate that ductile deformation localised around inclusions can provide fast pathways for geochemical exchange. These pathways may provide links to the zircon grain boundary, thus negating the widely held assumption that inclusions in fracture-free zircon are geochemically armoured once they are physically enclosed. © 2011.
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Effect of nanostructuring and Al alloying on friction and wear behaviour of thermal sprayed WC-Co coatings
(Elsevier, 2012) Basak, A.; Celis, J.; Vardavoulias, M.; Matteazzi, P.
Abstract not available
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Taphonomy of very ancient microfossils from the similar to 3400 Ma Strelley Pool Formation and similar to 1900 Ma Gunflint Formation: new insights using a focused ion beam
(Elsevier Science BV, 2012) Wacey, D.; Menon, S.; Green, L.; Gerstmann, D.; Kong, C.; Mcloughlin, N.; Saunders, M.; Brasier, M.; Adelaide Microscopy
Focused ion beam (FIB) milling permits the accurate extraction of ultrathin (c. 100. nm) cross sectional lamellae from microfossils found in geological thin sections. Subsequent TEM analysis of these lamellae can provide unique insights into the ultrastructure, chemistry and taphonomy of Precambrian microfossils at the micrometer to nanometer scale. Combining serial FIB milling with SEM imaging extends this capability to three dimensional (3D) tomographic reconstruction and visualization of Precambrian microfossils, revealing information not available in light microscopy.Here we apply these techniques to two iconic silicified microfossil assemblages, from the ∼3400. Ma Strelley Pool Formation of Western Australia and the ∼1900. Ma Gunflint Formation of Canada. All the examined microfossils have carbonaceous walls surrounded by pure silica. Impregnation of microfossil walls by nano-grains of silica is common, together with variable degrees of wall displacement and replacement by silica. All microfossils are rigidly preserved in 3D and show little or no folding or compression. However, there are also notable differences in taphonomic preservation. Our examples of the spheroidal Gunflint microfossil Huroniospora showed the highest fidelity of preservation with a continuous carbonaceous wall fossilized by spheroidal nano-silica grains that resemble those found on bacterial surfaces in modern silicifying hot-spring environments. The nucleation of these silica nano-spheres on the microfossil walls has induced an artificial 'saw-tooth-like' ridged wall texture that may subsequently hinder species-level identification. The Strelley Pool microfossils in comparison show a lower fidelity of preservation with small parts of the microfossil walls completely replaced by silica, plus extensive recrystallization of spheroidal silica nano-grains to angular micro-quartz. Our examples of the sheath-like filamentous Gunflint microfossil Siphonophycus showed the lowest fidelity of preservation with many gaps in the carbonaceous walls and significant redistribution of carbon by recrystallizing silica grains. A model is presented to explain these observations.Criteria for distinguishing highly probable microfossils from non-cellular carbonaceous microstructures (e.g., botryoids and grain coatings) using FIB-based imaging are put forward for the first time here, using examples drawn from the Strelley Pool Formation and comparisons with younger Gunflint material.The combined in situ techniques of FIB-TEM and FIB-SEM nano-tomography potentially provide a wealth of new nano-scale information regarding the biogenicity, antiquity and taphonomy of Precambrian microfossils. However, the destructive nature of both techniques makes their application to unique palaeontological specimens problematical. © 2012 Elsevier B.V.
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Repairing a critical-sized bone defect with highly porous modified and unmodified baghdadite scaffolds
(Elsevier BV, 2012) Roohani-Esfahani, S.; Dunstan, C.; Davies, B.; Pearce, S.; Williams, R.; Zreiqat, H.; Adelaide Microscopy
This is the first reported study to prepare highly porous baghdadite (Ca₃ZrSi₂O₉) scaffolds with and without surface modification and investigate their ability to repair critical-sized bone defects in a rabbit radius under normal load. The modification was carried out to improve the mechanical properties of the baghdadite scaffolds (particularly to address their brittleness) by coating their surfaces with a thin layer (∼400 nm) of polycaprolactone (PCL)/bioactive glass nanoparticles (nBGs). The β-tricalcium phosphate/hydroxyapatite (TCP/HA) scaffolds with and without modification were used as the control groups. All of the tested scaffolds had an open and interconnected porous structure with a porosity of ∼85% and average pore size of 500 μm. The scaffolds (six per scaffold type and size of 4 mm × 4 mm × 15 mm) were implanted (press-fit) into the rabbit radial segmental defects for 12 weeks. Micro-computed tomography and histological evaluations were used to determine bone ingrowth, bone quality, and implant integration after 12 weeks of healing. Extensive new bone formation with complete bridging of the radial defect was evident with the baghdadite scaffolds (modified/unmodified) at the periphery and in close proximity to the ceramics within the pores, in contrast to TCP/HA scaffolds (modified/unmodified), where bone tended to grow between the ulna adjacent to the implant edge. Although the modification of the baghdadite scaffolds significantly improved their mechanical properties, it did not show any significant effect on in vivo bone formation. Our findings suggest that baghdadite scaffolds with and without modification can serve as a potential material to repair critical sized bone defects.
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The use of hydroponics in abiotic stress tolerance research
(InTech, 2012) Shavrukov, Y.; Genc, Y.; Hayes, J.; Asao, T.
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Off-line feed rate scheduling based on a mechanistic cutting force on discrete segments during end milling
(Trans Tech Publications, 2013) Islam, M.; Pramanik, A.; Basak, A.; Kim, Y.H.; Yarlagadda, P.
This paper describes the development of an off-line feed rate scheduling technique based on a mechanistic cutting force model. The proposed technique was developed for an end milling operation. The surface area of the workpiece was divided into a number of segments, and the resultant cutting force at each discrete segment was determined using One Path Analysis software. The calculated resultant cutting force was applied to the feed rate scheduling. Experimental results clearly showed that the implementation of feed rate scheduling reduces machining time considerably and that as the number of segments increases, the effectiveness of the feed rate scheduling increases.
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Unique microstructural design of ceramic scaffolds for bone regeneration under load
(Elsevier BV, 2013) Roohani-Esfahani, S.; Dunstan, C.; Li, J.; Lu, Z.; Davies, B.; Pearce, S.; Field, J.; Williams, R.; Zreiqat, H.
During the past two decades, research on ceramic scaffolds for bone regeneration has progressed rapidly; however, currently available porous scaffolds remain unsuitable for load-bearing applications. The key to success is to apply microstructural design strategies to develop ceramic scaffolds with mechanical properties approaching those of bone. Here we report on the development of a unique microstructurally designed ceramic scaffold, strontium-hardystonite-gahnite (Sr-HT-gahnite), with 85% porosity, 500μm pore size, a competitive compressive strength of 4.1±0.3MPa and a compressive modulus of 170±20MPa. The in vitro biocompatibility of the scaffolds was studied using primary human bone-derived cells. The ability of Sr-HT-gahnite scaffolds to repair critical-sized bone defects was also investigated in a rabbit radius under normal load, with β-tricalcium phosphate/hydroxyapatite scaffolds used in the control group. Studies with primary human osteoblast cultures confirmed the bioactivity of these scaffolds, and regeneration of rabbit radial critical defects demonstrated that this material induces new bone defect bridging, with clear evidence of regeneration of original radial architecture and bone marrow environment.
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Machining and tool wear mechanisms during machining titanium alloys
(Trans Tech Publications, 2013) Pramanik, A.; Islam, M.; Basak, A.; Littlefair, G.
This paper investigates the machining mechanism of titanium alloys and analyses those understandings systematically to give a solid understanding with latest developments on machining of titanium alloys. The chip formation mechanism and wear of different cutting tools have been analyzed thoroughly based on the available literature. It is found that the deformation mechanism during machining of titanium alloys is complex and it takes place through several processes. Abrasion, attrition, diffusion–dissolution, thermal crack and plastic deformation are main tool wear mechanisms.
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Quantitative prediction of phase transformations in silicon during nanoindentation
(Taylor & Francis, 2013) Zhang, L.; Basak, A.
This paper establishes the first quantitative relationship between the phases transformed in silicon and the shape characteristics of nanoindentation curves. Based on an integrated analysis using TEM and unit cell properties of phases, the volumes of the phases emerged in a nanoindentation are formulated as a function of pop-out size and depth of nanoindentation impression. This simple formula enables a fast, accurate and quantitative prediction of the phases in a nanoindentation cycle, which has been impossible before.

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