Centre for Microscopy and Microanalysis Publications - UQ eSpace

中国东部部分地区新生代岩石圈地幔的成因: 主量和微量元素制约

2012-01-19T00:00:00Z

珊瑚礁区碳循环研究进展

2012-01-20T00:00:00Z

Abrupt increase in east Indonesian rainfall from flooding of the Sunda Shelf ∼9500 years ago

2013-04-10T13:40:12Z

We present a precisely dated, multi-proxy stalagmite record from Liang Luar Cave, Flores (southeast Indonesia) that reveals a rapid increase in Indonesian monsoon rainfall at ∼9.5 ka. A "ramp-fitting" method for detecting statistically significant inflections in a time-series was applied to the stalagmite δ 18O, Mg/Ca, and Sr/Ca profiles to quantify the precise timing and magnitude of an abrupt increase in monsoon strength over a period of ∼350 years. Previously published lake-level records from the monsoon-affected Australian interior show a sudden intensification of the Australian monsoon at ∼14 ka. However, our records indicate that monsoon intensification in Flores occured ∼4-5 kyr later. The timing of the monsoon shift in Flores is synchronous with the rapid expansion of rainforest in northeast Australia and regional freshening of the southern Makassar Strait which, under present-day conditions, is sensitive to monsoon variability. The freshening of southern Makassar was coeval with an abrupt ∼1.5 °C cooling in the upper thermocline of the Timor Sea ∼9.5 ka, indicative of reduced surface heat transport by the Indonesian Throughflow (ITF) when the Java Sea opened during postglacial sea-level rise. This suggests that the abrupt increase in monsoon rainfall on Flores was not due to a change in the ITF - because a decrease in rainfall would be expected to accompany cooler local sea surface temperatures (SSTs) - but rather by the sudden increase in ocean surface area and/or temperature in the monsoon source region as the Sunda Shelf flooded during deglaciation. We propose that it was the abrupt intensification of the monsoon through the late deglaciation that maintained the subsequent structure of the ITF following the flooding of the Sunda Shelf at ∼9.5 ka.

A comparison of anterior adhesive areas and secretions in Troglocephalus rhinobatidis and Neoheterocotyle rhinobatidis (Monogenea : Monocotylidae) from the gills of the shovelnose ray, Rhinobatos typus (Rhinobatidae)

2007-08-14T00:00:00Z

This study continues the collection of data on the anterior adhesive areas and secretions of monopisthocotylean monogenean (flatworm) parasites and begins an investigation of their phylogenetic usefulness. Here, two species of parasitic worms from an elasmobranch, Troglocephalus rhinobatidis (Monocotylidae: Dasybatotreminae) and Neoheterocotyle rhinobatidis (Monocotylidae: Heterocotylinae), are compared and contrasted. It has been suggested in recent literature that these two taxa are more closely related than is currently recognised. Our data support this view. Both species have multiple apertures on the ventral anterior margin through which adhesive is secreted. Two types of secretion exit from multiple adjacent duct endings terminating in each aperture: rod-shaped (S1) and spherical-shaped (S2) bodies. S1 bodies of both species show nano-banding of similar size and are membrane bound. Ultrastructure of the glands, ducts, duct endings and secreted adhesive is similar for both species, but aperture shape differs. Away from the adhesive areas, tegumental inclusions are found to differ between the two species and another, apparently non-adhesive, secretion is found in N. rhinobatidis.

A comparison of critical-point drying and hexamethyldisilazane (HMDS) preparation methods for scanning electron microscopy of insects and platyhelminths

2008-06-06T00:00:00Z

A comparison of the anterior adhesive system in the oncomiracidium and adult of the monogenean parasite Merizocotyle icopae (Monocotylidae)

2007-08-15T00:00:00Z

The anterior adhesive system of the oncomiracidium and adult of Merizocotyle icopae (Monogenea: Monocotylidae) were compared. The oncomiracidium has one ventrally placed aperture on either side of the head near the anterior extremity. In the adult, there are three ventrally placed apertures on either side of the head region. Both systems have three types of electron-dense secretory bodies opening into each aperture. A rod-shaped secretion (S1) and a small electron dense ovoid secretion (S2) are common to larvae and adults. The third secretion type differs: in adults, it is a large, spherical (S3) type but in larvae, it is an ovoid (S4) body. S4 bodies do occur in adults, but appear to be secreted as a general body secretion. An additional anteromedian secretion (S5) is also present in the oncomiracidium, but is not secreted into the anterior apertures. Homology and function of secretions are discussed.

A convenient sample preparation protocol for scanning electron microscope examination of xylem-occluding bacterial biofilm on cut flowers and foliage

2012-07-09T09:49:20Z

Microbes and their exopolysaccharides (EPS) can block xylem vessels, thereby increasing the hydraulic resistance and decreasing the vase life of cut flowers and foliage. Scanning electron microscopy (SEM) provides a powerful tool for investigation of bacteria-induced xylem occlusion. However, conventional preparation protocols for SEM involving chemicals can cause loss of hydrated EPS material, and thereby damage the bacterial biofilms during dehydration. A modified chemical fixation protocol involving pre-fixation with 75. mM lysine plus 2.5% glutaraldehyde followed by the normal fixation in 3% glutaraldehyde was, therefore, tested for improved preservation of bacterial biofilm at the stem-ends of cut . Acacia holosericea foliage stems. Stem-end segments with different stages of bacterial growth were obtained from stems stood into water. The lysine-based protocol was compared with four other processing protocols of critical point drying (CPD) without fixation (control), freeze-drying (FD), conventional chemical fixation followed by drying with hexamethyldisilazane (HMDS), and conventional chemical fixation with CPD. The non-fixed control, FD and the glutaraldehyde fixation with HMDS drying gave poor preservation of hydrated material, including bacterial EPS. Conventional glutaraldehyde fixation followed by CPD was superior to these three methods in terms of better preserving the EPS. However, this fourth method gave condensation of biofilms during dehydration. In contrast, the modified lysine-based protocol resulted in superior preservation of EPS and biofilm structure. Thus, this fifth method was the most appropriate for examination of bacterial stem-end blockage in cut ornamentals.

Actin- and dynamin-dependent maturation of bulk endocytosis restores neurotransmission following synaptic depletion

2012-07-11T11:42:01Z

α-Actinin-3 deficiency results in reduced glycogen phosphorylase activity and altered calcium handling in skeletal muscle

2010-04-04T00:05:08Z

A design on nano-hetero strucutre in Dy doped CeO2 solid electrolytes using a combined process of spart plasma sintering and conventional sintering

2007-08-23T00:00:00Z

Adhesion of microbes using 3-aminopropyl triethoxy silane and specimen stabilisation techniques for analytical transmission electron microscopy

2007-08-13T00:00:00Z

A variety of adhesive support-films were tested for their ability to adhere various biological specimens for transmission electron microscopy. Support films primed with 3-amino-propyl triethoxy silane (APTES), poly-L-lysine, carbon and ultraviolet-B (UV-B)-irradiated carbon were tested for their ability to adhere a variety of biological specimens including axenic cultures of Bacillus subtilis and Escherichia coli and wild-type magnetotactic bacteria. The effects of UV-B irradiation on the support film in the presence of air and electrostatic charge on primer deposition were tested and the stability of adhered specimens on various surfaces was also compared. APTES-primed UV-B-irradiated Pioloform(TM) was consistently the best adhesive, especially for large cells, and when adhered specimens were UV-B irradiated they became remarkably stable under an electron beam. This assisted the acquisition of in situ phase-contrast lattice images from a variety of biominerals in magnetotactic bacteria, in particular metastable greigite magnetosomes. Washing tests indicated that specimens adhering to APTES-primed UV-B-irradiated Pioloform(TM) were covalently coupled. The electron beam stability was hypothesised to be the result of mechanical strengthening of the specimen and support film and the reduced electrical resistance in the specimen and support film due to their polymerization and covalent coupling.

Adhesive secretions in the platyhelminthes

Whittington, I. D. og Cribb, B. W. — 2007-08-14T00:00:00Z

A Dual Layer Hair Array of the Brown Lacewing: Repelling Water at Different Length Scales

2011-09-05T16:32:56Z

Advanced transmission electron microscopy characterization of semiconductor quantum structures

2007-08-14T00:00:00Z

Aedes aegypti: Sensilla trichodea and stimulus-conducting structures

Muir, Lynda E. og Cribb, Bronwen W. — 2011-03-10T00:00:00Z

Much of the morphology of the olfactory sensilla on the antennae of the mosquito Aedesaegypti (L.) has been described, however little is known about the fate of odour molecules once they have been adsorbed onto the surfaces of sensilla. A stimulus-conducting system of pores, pore kettles, and pore tubules has been described for the sensillatrichodea (olfactory hairs) of several insects but not mosquitoes. Scanning electron microscopy was used to identify the s. trichodea of Ae. aegypti and to attempt visualization of their pore openings. Chemical fixation, cryopreparation, freeze drying, and negative staining, with high resolution transmission electron microscopy (TEM), were used to locate putative stimulus-conductingstructures associated with the pores. TEM sections using Dalton's fixative or freeze drying showed pores and pore tubules, whereas pore tubules were poorly preserved in cryoprepared sections. The putative stimulus-conductingstructures were clearly demonstrated by negative staining of whole sensilla which was quick and easy. The current hypothesis of olfactory stimulus conduction is extended to include Ae. aegypti.

A focused review on nanoscratching-induced deformation of monocrystalline silicon

Wu, Yueqin og Huang, Han og Zou, Jin — 2013-01-25T07:39:16Z

This focused review includes two parts. In the first part, the previous studies on the deformations of monocrystalline Si induced by nanoscratching were summarised. In the second part, our recent studies on the scratching-induced deformation of Si were systematically presented. The studies have demonstrated that lateral force in nanoscratching plays a key role in the amorphization and phase transformation of Si under mechanical loading. The deformation route of Si appears to be different from those reported from the nanoindentation studies.

Age and biostratigraphic significance of the Punung Rainforest Fauna, East Java, Indonesia, and implications for Pongo and Homo

2009-09-03T09:52:04Z

The Punung Fauna is a key component in the biostratigraphic sequence of Java. It represents the most significant faunal turnover on the island in the last 1.5 million years, when Stegodon and other archaic mammal species characteristic of earlier Faunal stages were replaced by a fully modern fauna that included rainforest-dependent species such as Pongo pygmaeus (orangutan). Here, we report the first numerical ages for the Punung Fauna obtained by luminescence and uranium-series dating of the fossil-bearing deposits and associated flowstones. The Punung Fauna contained in the dated breccia is of early Last Interglacial age (between 128 ± 15 and 118 ± 3 ka). This result has implications for the age of the preceding Ngandong Fauna, including Homo erectus remains found in the Ngandong Terrace, and for the timing of Homo sapiens arrival in Southeast Asia, in view of claims for a modern human tooth associated with the Punung breccia.

Age frequency distribution and revised stable isotope curves for New Zealand speleothems: Palaeoclimatic implications

2011-03-08T00:00:00Z

Age hardening of a sintered Al-Cu-Mg-Si-(Sn) alloy

Kent, D. og Schaffer, G. B. og Drennan, J. — 2007-08-15T00:00:00Z

The age hardening response of a sintered Al-3.8 wt% Cu-1.0 wt% Mg-0.70 wt% Si alloy with and without 0.1 wt% Sn was investigated. The sequence of precipitation was characterised using transmission electron microscopy. The ageing response of the sintered Al-Cu-Mg-Si-(Sn) alloy is similar to that of cognate wrought 2xxx series alloys. Peak hardness was associated with a fine, uniform dispersion of lath shaped precipitates, believed to be either the betaor Q phase, oriented along < 010 >. directions and theta' plates lying on {001}(alpha). planes. Natural ageing also resulted in comparable behaviour to that observed in wrought alloys. Porosity in the powder metallurgy alloys did not significantly affect the kinetics of precipitation during artificial ageing. Trace levels of tin, used to aid sintering, slightly reduced the hardening response of the alloy. However, this was compensated for by significant improvements in density and hardness. (c) 2005 Elsevier B.V. All rights reserved.

A high-precision record of mid-late Holocene sea-level events from emergent coral pavements in the Houtman Abrolhos Islands, southwest Australia

Collins, LB og Zhao, JX og Freeman, H — 2007-08-15T00:00:00Z

Early work on sea-levels in southwest Australia claimed to recognise a Holocene sea-level highstand which was not seen in better known sea-level records elsewhere at the time. More recent work has confirmed that a mid-Holocene highstand Occurred about 6 kyr ago. As new data on oscillating sea-levels from the region have recently been published, a high continuity, precisely dated and accurately surveyed record was obtained from emergent coral pavements in the leeward Houtman Abrolhos Islands (Serventy Island), a tectonically stable region from where good-quality Holocene sea-level data have been previously obtained from corals. From the mid-Holocene highstand ca. 7 U/Th kyr ago, sea-level declined linearly during the remainder of the Holocene as the carbonate platform prograded leewards. Hydro-isostatic controls are probably significant in the record. (c) 2005 Elsevier Ltd and INQUA. All rights reserved.

A late Pleistocene predator-accumulated avifauna from Kids Cave, West Coast, South Island, New Zealand

Worthy, Trevor H. og Zhao, J. X. — 2007-08-15T00:00:00Z

A fossil deposit excavated from the floor of Kids Cave, West Coast, South Island, New Zealand, is interpreted as having been primarily accumulated by New Zealand falcon Falco novaeseelandiae, with some contribution by Haast's eagle Harpagornis moorei. The fauna is rich: 3699 bones represented 41 bird species, two frog species, unspecified geckoes and skinks, and one bat species. Fossil deposition was mainly within the Last Glacial Maximum from about 22,000 cal yr bp to about 15,000 cal yr bp, with a marked change in sediment characteristics at the onset of the LGM's coldest period. Chronological control is given by three Uranium-series dates for a speleothem and radiocarbon AMS dating of four avian eggshell samples and one bone. The fauna is the first extensive predator accumulation of LGM age described from the West Coast of the South Island, and it indicates a palaeoenvironment of a mosaic of shrublands with forest patches. The onset of the coldest part of the LGM (Aurora 3 glacial advance, 19,500 - 19,000 cal yrs bp) saw marked climate cooling/drying affecting the site, but the avifauna indicates that although open-country taxa became more common in this period, some forest persisted nearby throughout the remainder of the LGM.

Alloying, elemental enrichment, and interdiffusion during the growth of Ge(Si)/Si(001) quantum dots

2007-10-17T00:00:00Z

Ge(Si)/Si(001) quantum dots produced by gas-source molecular beam epitaxy at 575 degreesC were investigated using energy-filtering transmission electron microscopy and x-ray energy dispersive spectrometry. Results show a nonuniform composition distribution in the quantum dots with the highest Ge content at the dot center. The average Ge content in the quantum dots is much higher than in the wetting layer. The quantum dot/substrate interface has been moved to the substrate side. A growth mechanism of the quantum dots is discussed based on the composition distribution and interfacial structures.

Alpha-cellulose δ13C variation in mangrove tree rings correlates well with annual sea level trend between 1982 and 1999

2007-08-15T00:00:00Z

A pilot study of tree rings in a modern mangrove tree (Rhizophora apiculata) from Leizhou Peninsula, northern South China Sea shows that ( 1) the tree-rings are annual; ( 2) the ring widths decrease; and ( 3) their alpha-cellulose delta(13)C values increase from 1982 to 1999 AD, consistent with the trends of annual sea level, salinity and sea surface temperatures in the same period. We propose that such changes were caused by increasingly longer duration of waterlogging in response to sea-level rise. If this is the case, alpha-cellulose delta(13)C in mangrove tree rings can be used as a potential indicator of past sea level fluctuations.

AlSb/GaAs（001）失配位错的高分辨电子显微学研究. High-resolution electron microscopy of misfit dislocations in AlSb/GaAs(001) system

2011-02-04T00:00:00Z

Alternative mechanism for misfit dislocation generation during high-temperature Ge(Si)/Si(001) island growth

2007-10-17T00:00:00Z

The misfit dislocations in [001] Ge(Si)/Si islands grown at 700 degreesC were investigated using transmission electron microscopy. 30degrees partial misfit dislocations are found both in the island/substrate interface and near the island surface. Since the 30degrees partial leads the movement of the 60degrees dissociated misfit dislocation in a (001) compressively strained system such as (001) GeSi/Si, a generation mechanism of misfit dislocations through partial misfit dislocations half loops is proposed. (C) 2002 American Institute of Physics.

Aluminum induced in situ crystallization of amorphous SiC

2009-09-04T10:28:49Z

Amorphous iron oxide decorated 3D heterostructured electrode for highly efficient oxygen reduction

2011-10-16T00:19:40Z

Amorphous SiOx nanowires catalyzed by metallic Ge for optoelectronic applications

2011-03-20T00:00:00Z

Amorphous SiOx nanowires, with diameters of ∼20nm and lengths of tens of m, were grown from self-organized GeSi quantum dots or GeSi alloy epilayers on Si substrates. The morphologies and yield of these amorphous nanowires depend strongly upon the synthesis temperature. Comparative experiments indicate that the present SiOx nanowires are induced by metallic Ge as catalysts via the solid liquid solid growth mechanism. Two broad peaks centered at 410nm and 570nm were observed in photoluminescence spectrum, indicating that such SiOx nanowires have the potential applications in white light-emitting diodes, full-colour display, full-colour indicator and light sources.

Amorphous structures induced in monocrystalline silicon by mechanical loading

2007-08-15T00:00:00Z

Different amorphous structures have been induced in monocrystalline silicon by high pressure in indentation and polishing. Through the use of high-resolution transmission electron microscopy and nanodiffraction, it was found that the structures of amorphous silicon formed at slow and fast loading/unloading rates are dissimilar and inherit the nearest-neighbor distance of the crystal in which they are formed. The results are in good agreement with recent theoretical predictions. (C) 2004 American Institute of Physics.

Amphipols: Polymeric surfactants for membrane biology research

2009-01-08T10:29:09Z

Membrane proteins classically are handled in aqueous solutions as complexes with detergents. The dissociating character of detergents, combined with the need to maintain an excess of them, frequently results in more or less rapid inactivation of the protein under study. Over the past few years, we have endeavored to develop a novel family of surfactants, dubbed amphipols (APs). APs are amphiphilic polymers that bind to the transmembrane surface of the protein in a noncovalent but, in the absence of a competing surfactant, quasi-irreversible manner. Membrane proteins complexed by APs are in their native state, stable, and they remain water-soluble in the absence of detergent or free APs. An update is presented of the current knowledge about these compounds and their demonstrated or putative uses in membrane biology.

Analytical electron microscopy of proton exchange membrane fuel cells

2007-08-23T20:26:49Z

Microtome sections of proton exchange membrane cells produce a wide range of information ranging from macroscopic distribution of components through specimens in which the detailed distribution of catalyst particles can be observed. Using modern data management practices it is possible to combine information at different scales and correlate processing and performance data. Analytical electron microscopy reveals the compositional variations across used cells at the electrolyte/electrode interface. In particular analytical techniques indicate that sulphur concentrations are likely to diminish at the interface Nafion/anode interface. © 2006 Elsevier B.V. All rights reserved.

A nanometre-scale non-periodic structural variation in high temperature superconducting ceramics and the implications for properties

Barry, J. C. og Alarco, J. A. — 2007-08-14T00:00:00Z

Non-periodic structural variation has been found in the high T-c cuprates, YBa2Cu3O7-x and Hg0.67Pb0.33Ba2Ca2Cu3O8+delta, by image analysis of high resolution transmission electron microscope (HRTEM) images. We use two methods for analysis of the HRTEM images. The first method is a means for measuring the bending of lattice fringes at twin planes. The second method is a low-pass filter technique which enhances information contained by diffuse-scattered electrons and reveals what appears to be an interference effect between domains of differing lattice parameter in the top and bottom of the thin foil. We believe that these methods of image analysis could be usefully applied to the many thousands of HRTEM images that have been collected by other workers in the high temperature superconductor field. This work provides direct structural evidence for phase separation in high T-c cuprates, and gives support to recent stripes models that have been proposed to explain various angle resolved photoelectron spectroscopy and nuclear magnetic resonance data. We believe that the structural variation is a response to an opening of an electronic solubility gap where holes are not uniformly distributed in the material but are confined to metallic stripes. Optimum doping may occur as a consequence of the diffuse boundaries between stripes which arise from spinodal decomposition. Theoretical ideas about the high T-c cuprates which treat the cuprates as homogeneous may need to be modified in order to take account of this type of structural variation.

Anatase TiO2 crystal facet growth: Mechanistic role of hydrofluoric acid and photoelectrocatalytic activity

2011-09-04T00:00:00Z

An efficient approach to characterize pseudo-merohedral twins by precession electron diffraction: Application to the LaGaO3 perovskite

2010-03-24T00:00:00Z

An electron microscopic study of nickel sulfide inclusions in toughened glass

Barry, J. C. og Ford, S. — 2007-08-14T00:00:00Z

It has been known since the early sixties that nickel sulfide inclusions cause spontaneous fracture of toughened (thermally tempered) glass, but despite the considerable amount of work done on this problem in the last four decades, failures still occur in the field with regularity. In this study we have classified (by viewing through a 60x optical microscope) inclusions into two groups, which are classic and atypical nickel sulfides. The classics look like the nickel sulfide inclusions found at the initiation-of-fracture of windows that have broken spontaneously. We have compared the structure and composition of the atypical inclusions with the structure and composition of the classics. All of the classic and atypical nickel sulfide inclusions studied in this work were found to have a composition in the range of Ni52S48 to Ni48S52. Inclusions on the nickel rich side of stoichiometric NiS were found to be two-phase assemblies, and inclusions on the sulphur rich side of NiS were single phase. It had been proposed that the atypicals were passive, and of a different composition to the classics. However, we found that the difference between passive and dangerous nickel sulfide inclusions was not a difference in composition but rather a difference in the type of material in the internal pore space. The passive's had carbon char in their internal pore space, whereas the pore space of dangerous inclusions contained Na2O. The presence of Na2O and carbon char with the inclusions indicates that the formation of the inclusions results from a reaction of a nickel-rich phase with sodium sulphate and carbon. (C) 2001 Kluwer Academic Publishers.

A new cathode for solid oxide fuel cells capable of in situ electrochemical regeneration

2011-11-06T01:32:38Z

A new genus of the Gyliauchenidae Goto et Matsudaira, 1918 (Digenea) from Naso tuberosus (Percomorpha, Acanthuridae) on the Great Barrier Reef, Queensland, Australia

2008-06-10T00:00:00Z

A new genus and species, Affecauda annulata, belonging to the Gyliauchenidae Goto et Matsudaira, 1918 was found in the intestine of Naso tuberosus from Heron and Lizard Islands on the Great Barrier Reef, Queensland, Australia. This is the first record of a gyliauchenid from a species of Naso. We have placed Affecauda annulata within the Gyliauchenidae based on the structure of its digestive tract and terminal genitalia. The unusual and distinctive shape of the hindbody, which is elongate and curled, and the location of the excretory vesicle and papilla, which is distinctly anterior to the ventral sucker, distinguish this genus from other genera within the Gyliauchenidae.

An integrated zircon geochronological and geochemical investigation into the Miocene plutonic evolution of the Cyclades, Aegean Sea, Greece: part 2-geochemistry

2012-12-16T00:13:14Z

Zircons from 14 compositionally variable granitic rocks were examined in detail using CL image-guided micro-analysis to unravel the complex magmatic history above the southward retreating Hellenic subduction zone system in the Aegean Sea. Previously published U-Pb ages document an episodic crystallisation history from 17 to 11 Ma, with peraluminous (S-type) granitic rocks systematically older than closely associated metaluminous (I-type) granitic rocks. Zircon O- and Hf isotopic data, combined with trace element compositions, are highly variable within and between individual samples, indicative of open-system behaviour involving mantle-derived melts and evolved supracrustal sources. Pronounced compositional and thermal fluctuations highlight the role of magma mixing and mingling, in accord with field observations, and incremental emplacement of distinct melt batches coupled with variable degrees of crustal assimilation. In the course of partial fusion, more fertile supracrustal sources dominated in the earlier stages of Aegean Miocene magmatism, consistent with systematically older crystallisation ages of peraluminous granitic rocks. Differences between zircon saturation and crystallisation temperatures (deduced from zircon Ti concentrations), along with multimodal crystallisation age spectra for individual plutons, highlight the complex and highly variable physico-compositional and thermal evolution of silicic magma systems. The transfer of heat and juvenile melts from the mantle varied probably in response to episodic rollback of the subducting lithospheric slab, as suggested by punctuated crystallisation age spectra within and among individual granitic plutons.

An investigation of the microstructure/electrical conductivity relationship in In2O3-substituted LSGM

2007-08-14T00:00:00Z

The effect of controlled In3+ substitution on to the B-site in the perovskite oxygen ion conductor La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) has been examined with a view to exploring the influence on oxygen ion conductivity. In combination with the electrical conductivity study, detailed microstructural analysis was used to verify the location of the substituting cation and to determine the nature of secondary phase formation. The indium species clearly substituted for Ga3+ on the B-site of the lattice and the electrical conductivity showed a gradual decrease as the In+3 content increased. The interpretation of this data was complicated by the formation of the secondary phases LaInO3 and LaSrGaO4. (C) 2001 Elsevier Science Ltd. All rights reserved.

Annealing effects on the microstructure of Ge/Si(001) quantum dots

2007-10-17T00:00:00Z

Ge/Si(001) multilayer islands produced by gas-source molecular-beam epitaxy at 575 degreesC were investigated using energy-filtering transmission electron microscopy. Results show, for as-grown samples, not only a continuous enlargement of island size in upper layers but also a continuous increase of Ge concentration within islands in upper layers. As a result of the increasing island size and Ge concentration within the islands, the island density in upper layers decreases. For samples annealed at 900 degreesC for 5 min, the aspect ratio of buried islands increases significantly, and the average Ge concentration within islands of different layers becomes uniform. (C) 2001 American Institute of Physics.

Annealing of ion implanted gallium nitride

2007-08-13T00:00:00Z

In this paper, we examine Si and Te ion implant damage removal in GaN as a function of implantation dose, and implantation and annealing temperature. Transmission electron microscopy shows that amorphous layers, which can result from high-dose implantation, recrystallize between 800 and 1100 °C to very defective polycrystalline material. Lower-dose implants (down to 5 × 1013 cm – 2), which are not amorphous but defective after implantation, also anneal poorly up to 1100 °C, leaving a coarse network of extended defects. Despite such disorder, a high fraction of Te is found to be substitutional in GaN both following implantation and after annealing. Furthermore, although elevated-temperature implants result in less disorder after implantation, this damage is also impossible to anneal out completely by 1100 °C. The implications of this study are that considerably higher annealing temperatures will be needed to remove damage for optimum electrical properties. ©1998 American Institute of Physics.

Anodic-oxide-induced interdiffusion in GaAs/AlGaAs quantum wells

2007-08-13T00:00:00Z

Enhancement of interdiffusion in GaAs/AlGaAs quantum wells due to anodic oxides was studied. Photoluminescence, transmission electron microscopy, and quantum well modeling were used to understand the effects of intermixing on the quantum well shape. Residual water in the oxide was found to increase the intermixing, though it was not the prime cause for intermixing. Injection of defects such as group III vacancies or interstitials was considered to be a driving force for the intermixing. Different current densities used in the experimental range to create anodic oxides had little effect on the intermixing. ©1998 American Institute of Physics.

Anomalies in skull bones of the Australian lungfish, Neoceratodus Forsteri, compared with aberrations in fossil Dipnoan skulls

Kemp, A. R. — 2008-06-10T00:00:00Z

Abnormalities that appear during the development of the dermal, chondral and visceral cranium of the Australian lungfish, Neoceratodus forsteri, are common and many of these anomalies are reflected in the skulls of fossil lungfish. In addition to asymmetry of individual bones, elements may be missing altogether, or may have fused with one or more adjacent bones. Bones may be divided, with the separate bones having the outline of a normal bone. Elements may be malformed, and sometimes additional elements are present alongside a normal structure. Ossicles of the infraorbital, mandibular and preopercular series vary both in shape and in number. Aberrations may be genetic or teratogenic in origin, or may result from inappropriate osteogenic stimuli from the sensory lines that appear before the bones. The incidence of abnormalities is low in the Recent lungfish, Neoceratodus forsteri, and anomalies appear early in development and persist throughout life. Fossil dipnoans appear to have a high incidence of similar aberrations. Abnormalities have implications for taxonomic determinations, and phylogenetic analyses that rely on precise patterns of fusion and loss in the skull roofing bones of dipnoans should be treated with caution. Similar constraints apply to attempts to relate the skull roofing bones of dipnoans to those of other vertebrates.

Anomalies in the developing neural and visceral head skeleton of the Australian lungfish, Neoceratodus forsteri

Kemp, A — 2007-08-14T00:00:00Z

Several anomalies occur in the developing neural and visceral head skeleton of young specimens of Neoceratodus forsteri that have been reared under laboratory conditions. These include anomalies of the basicranium and its derivatives, aberrations of the anterior mandible and hyoid apparatus, and abnormalities in the articulation of the jaws and the elements that produce them. Apart from the occasional absence of the basihyal, and failure of the quadrate processes to form, the anomalies are not deficiencies. Most involve malformations of parts of the neurocranium and visceral skeleton, inappropriate articulations or fusions between elements, disunity in structures that are normally fused and the appearance of supernumerary elements. The incidence of chondral anomalies, generally higher than aberrations that occur in the dermal skeleton in juvenile lungfish, ranges from 1-10% in laboratory reared individuals that have not been subjected to experimental interference. The anomalies differ from those found in many amphibian populations, in the field and in the laboratory, because they involve the cranium, and not the limbs, and the lungfish have not been exposed to the factors that cause anomalies in the amphibians. It is unlikely that the existence of those anomalies, if it is reflected in the wild population, places a selective pressure on the lungfish, because, in a normal season, less than 1% of the total number of eggs produced survive to be recruited into the adult population.

A novel group of allenic hydrocarbons from five Australian (Melolonthine) beetles

2007-08-14T00:00:00Z

Allenic hydrocarbons, previously unknown as a molecular class from insects, are represented by CH3(CH2)(n)-CH=. =CH-(CH2)(7)CH3 (n = 11-15, 17, 19) in several Australian melolonthine scarab beetles and with demonstrated (R)-chirality when n = 11 and 13.

A novel method for the production of aluminium nitride

2007-08-15T00:00:00Z

A method has been developed to produce thick (> 400 mu m) AlN surface layers oil aluminium plates at 540 degrees C, under nitrogen at atmospheric pressure. A critical element of the process is the use of Mg powder placed in close proximity to the Al plate surface. The Mg reduces/disrupts the natural, protective oxide film on the Al surface. The nitride layers form through two distinct modes, one growing outward from the Al plate surface and the other growing into the Al. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A novel switch region regulated H-ras membrane orientation and signal output

2009-04-07T10:19:40Z

The plasma membrane nanoscale distribution of H-ras is regulated by guanine nucleotide binding. To explore the structural basis of H-ras membrane organization, we combined molecular dynamic simulations and medium-throughput FRET measurements on live cells.

A Novel synthesis strategy leading to the formation of stable transition-metal-oxide mesostructures

Zhao, X. og Drennan, J. og Lu, M.G. — 2007-08-14T00:00:00Z

An overview of the 2002-2004 excavations of Ming Dynasty imperial kilns in Jingdezhen

Li, Baoping — 2011-07-14T00:00:00Z

Seven page English essay: An overview of the 2002-2004 excavations of Ming dynasty imperial kilns in Jingdezhen by Quan Kuishan, edited and abridged translation into English by Baoping Li.

Anterior adhesive areas and adjacent secretions in the parasitic flatworms Decacotyle lymmae and D. tetrakordyle (Monogenea: Monocotylidae) from the gills of stingrays

Cribb, B. W. og Whittington, I. D. — 2007-08-15T00:00:00Z

The monogeneans Decacotyle lymmae and D. tetrakordyle (Monocotylidae: Decacotylinae), from gills of the dasyatid stingrays Taeniura lymma and Pastinachus sephen, respectively, have a single aperture for adhesive secretion on each side of the anterior ventrolateral region. Rod-shaped bodies (S1) and electron-dense spherical secretion (S2) exit through specialised ducts opening adjacent to one another within these apertures. The S1 bodies are 230 +/- 11 nm wide and greater than or equal to4 mum long in D. lymmae and 240 +/- 9 nm wide and greater than or equal to3.3 mum long in D. tetrakordyle. The S2 bodies have a diameter of 88 +/- 7 nm in D. lymmae and 65 +/- 6 nm in D. tetrakordyle. The apertures are unusual in being extremely small (internal diameter, 3-5 mum). Each aperture has a slit-like surface opening as small as 160 nm wide, surrounded by muscle fibres indicating that they may be opened and closed. The aperture is also surrounded and underlain by muscle fibres that may aid in secretion from, or even eversion of, the tissue within the aperture. Sensilla/cilia are also found within the apertures. Additional secretions from anteromedian and anterolateral glands (body glands), each containing granular secretions, occur in profusion and exit anteriorly and posteriorly to the position of the apertures, through duct openings in the general body tegument. These granular secretions do not appear to be associated with anterior adhesion. Both species show similarities in aperture, underlying tissue, sense organ, and secretion detail, in accordance with findings from other monogenean genera, and which supports the importance of such data for phylogenetic studies.