Synchrotron X-ray Microtomography Research Articles

Characterization of fatigue crack growth behavior in LENS fabricated Ti-6Al-4V using high-energy synchrotron x-ray microtomography

Laser Engineered Net Shaping (LENS) is an additive manufacturing technique that belongs to the ASTM standardized directed energy deposition category. To date, very limited work has been conducted towards understanding the fatigue crack growth behavior of LENS fabricated materials, which hinders the widespread adoption of this technology for high-integrity structural applications. In this study, the propagation of a 20μm initial crack in LENS fabricated Ti-6Al-4V was captured in-situ, using high-energy synchrotron x-ray microtomography. Fatigue crack growth (FCG) data were then determined from 2D and 3D tomography reconstructions, as well as from fracture surface striation measurements using SEM. The generated data were compared to those obtained from conventional FCG tests that used compliance and direct current potential drop (DCPD) techniques to measure long and small crack growth. The observed agreement demonstrates that x-ray microtomography and fractographic analysis using SEM can be successfully combined to study the propagation behavior of fatigue cracks.

Synchrotron imaging of dentition provides insights into the biology of Hesperornis and Ichthyornis, the "last" toothed birds.

BackgroundThe dentitions of extinct organisms can provide pivotal information regarding their phylogenetic position, as well as paleobiology, diet, development, and growth. Extant birds are edentulous (toothless), but their closest relatives among stem birds, the Cretaceous Hesperornithiformes and Ichthyornithiformes, retained teeth. Despite their significant phylogenetic position immediately outside the avian crown group, the dentitions of these taxa have never been studied in detail. To obtain new insight into the biology of these ‘last’ toothed birds, we use cutting-edge visualisation techniques to describe their dentitions at unprecedented levels of detail, in particular propagation phase contrast x-ray synchrotron microtomography at high-resolution.ResultsAmong other characteristics of tooth shape, growth, attachment, implantation, replacement, and dental tissue microstructures, revealed by these analyses, we find that tooth morphology and ornamentation differ greatly between the Hesperornithiformes and Ichthyornithiformes. We also highlight the first Old World, and youngest record of the major Mesozoic clade Ichthyornithiformes. Both taxa exhibit extremely thin and simple enamel. The extension rate of Hesperornis tooth dentine appears relatively high compared to non-avian dinosaurs. Root attachment is found for the first time to be fully thecodont via gomphosis in both taxa, but in Hesperornis secondary evolution led to teeth implantation in a groove, at least locally without a periodontal ligament. Dental replacement is shown to be lingual via a resorption pit in the root, in both taxa.ConclusionsOur results allow comparison with other archosaurs and also mammals, with implications regarding dental character evolution across amniotes. Some dental features of the ‘last’ toothed birds can be interpreted as functional adaptations related to diet and mode of predation, while others appear to be products of their peculiar phylogenetic heritage. The autapomorphic Hesperornis groove might have favoured firmer root attachment. These observations highlight complexity in the evolutionary history of tooth reduction in the avian lineage and also clarify alleged avian dental characteristics in the frame of a long-standing debate on bird origins. Finally, new hypotheses emerge that will possibly be tested by further analyses of avian teeth, for instance regarding dental replacement rates, or simplification and thinning of enamel throughout the course of early avian evolution.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0753-6) contains supplementary material, which is available to authorized users.

Rotating tomography Paris–Edinburgh cell: a novel portable press for micro-tomographic 4-D imaging at extreme pressure/temperature/stress conditions

ABSTRACTThis paper presents details of instrumental development to extend synchrotron X-ray microtomography techniques to in situ studies under static compression (high pressure), shear stress or the both conditions at simultaneous high temperatures. To achieve this, a new rotating tomography Paris–Edinburgh cell has been developed. This ultra-compact portable device easily and successfully adapted to various multi-modal synchrotron experimental set-up at ESRF, SOLEIL and DIAMOND is explained in detail. An in-depth description of proof of concept first experiments performed on a high resolution imaging beamline is then given, which illustrate the efficiency of the set-up and the data quality that can be obtained.

Cecilanthus polymerus, a novel multiparted flower from the mid-Cretaceous Rocky Point locality, Maryland

A flower from the early Cenomanian of northeastern Maryland, Cecilanthus polymerus gen. et sp. nov., is described using SEM and synchrotron X-ray microtomography. The flower has >20 strap-shaped tepals, ca. 50 spatulate stamens with embedded adaxial pollen sacs and possibly H-valvate dehiscence, and ca. 100 more-or-less plicate carpels. Floral phyllotaxis is whorled, with >10 parts per whorl, but slightly irregular. Pollen and ovules are not preserved, but locule shape suggests that the carpels are uniovulate. Similar characters occur in extant Magnoliales and the basal ANITA grade, but never in combination. In an attempt to resolve these ambiguities, we performed morphological phylogenetic analyses, with the arrangement of extant taxa constrained to trees based primarily on molecular data. With anther dehiscence and ovule number treated as unknown, Cecilanthus has several most-parsimonious positions: nested in Nymphaeales, nested in Magnoliales, sister to Laurales, and sister to Chloranthaceae. However, scoring anther dehiscence as H-valvate and ovule number as = 1, increases support for a position in Magnoliales. Cecilanthus demonstrates that the early radiation of angiosperms produced floral morphotypes unlike those in any surviving taxa, and it illustrates the value of characters such as pollen morphology and seed anatomy for phylogenetic placement of floral mesofossils.

Fast synchrotron X-ray tomographic quantification of dendrite evolution during the solidification of Mg[sbnd]Sn alloys

The evolution of dendritic microstructures during the solidification of a Mg-15 wt%Sn alloy was investigated in situ via fast synchrotron X-ray microtomography. To enable these in situ observations a novel encapsulation method was developed and integrated into a fast, pink beam, imaging beamline at Diamond Light Source. The dendritic growth was quantified with time using: solid volume fraction, tip velocity, interface specific surface area, and surface curvature. The influence of cooling rate upon these quantities and primary phase nucleation was investigated. The primary dendrites grew with an 18-branch, 6-fold symmetry structure, accompanied by coarsening. The coarsening process was assessed by the specific surface area and was compared with the existing models. These results provide the first quantification of dendritic growth during the solidification of Mg alloys, confirming existing analytic models and providing experimental data to inform and validate more complex numeric models.

Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease

We describe the earliest evidence for neoplastic disease in the hominin lineage. This is reported from the type specimen of the extinct hominin Australopithecus sediba from Malapa, South Africa, dated to 1.98 million years ago. The affected individual was male and developmentally equivalent to a human child of 12 to 13 years of age. A penetrating lytic lesion affected the sixth thoracic vertebra. The lesion was macroscopically evaluated and internally imaged through phase-contrast X-ray synchrotron microtomography. A comprehensive differential diagnosis was undertaken based on gross- and micro-morphology of the lesion, leading to a probable diagnosis of osteoid osteoma. These neoplasms are solitary, benign, osteoid and bone-forming tumours, formed from well-vascularised connective tissue within which there is active production of osteoid and woven bone. Tumours of any kind are rare in archaeological populations, and are all but unknown in the hominin record, highlighting the importance of this discovery. The presence of this disease at Malapa predates the earliest evidence of malignant neoplasia in the hominin fossil record by perhaps 200 000 years.

Lidryopinae, new byrrhid subfamily from the Lower Cretaceous of France (Coleoptera, Byrrhidae)

The byrrhid subfamily Lidryopinae subfam. nov. is proposed for Lidryops occultus gen. et sp. nov. described from Lower Cretaceous “opaque” amber originated from Archingeay-Les Nouillers, Charente-Maritime, southwest France which was studied using propagation phase contrast X-ray synchrotron microtomography at the European Synchrotron Radiation Facility (Grenoble). This byrrhid subfamily differs from members of the closely related groups (Chelonariidae, Limnichidae, Dryopidae, Elmidae, Lutrochidae) in the set of characters including the moderately convex dorsum, the subpectinate antennae, the five-segmented tarsi with strongly lobed tarsomeres 1–4, subsecuriform ultimate maxillary and labial palpomeres. An assumption on probable lifestyle of Lidryops occultus gen. et sp. nov. is proposed on the basis of structural peculiarities. A short review of the byrrhid fossil record and its analysis are made.

Computational fluid dynamics of cerebral aneurysm coiling using high-resolution and high-energy synchrotron X-ray microtomography: comparison with the homogeneous porous medium approach

BackgroundComputational modeling of intracranial aneurysms provides insights into the influence of hemodynamics on aneurysm growth, rupture, and treatment outcome. Standard modeling of coiled aneurysms simplifies the complex geometry of the...

The apportionment of tooth size and its implications in Australopithecus sediba versus other Plio-pleistocene and recent African hominins.

Australopithecus sediba is characterized further by providing formerly unpublished and refined mesiodistal and buccolingual crown measurements in the MH1 and MH2 specimens. After size correction, these data were compared with those in other fossil and recent samples to facilitate additional insight into diachronic hominin affinities. Six comparative samples consist of fossil species: A. africanus, A. afarensis, Homo habilis, Paranthropus robustus, P. boisei, and H. erectus. Others comprise H. sapiens and Pan troglodytes. Re-estimates of "actual" dimensions in damaged A. sediba teeth were effected through repeated measurements by independent observers. X-ray synchrotron microtomography allowed measurement of crowns obscured by matrix and noneruption. Tooth size apportionment analysis, an established technique for intraspecific comparisons, was then applied at this interspecific level to assess phenetic affinities using both within- and among-group data. Comparison of these highly heritable dimensions identified a general trend for smaller posterior relative to larger anterior teeth (not including canines), contra Paranthropus, that allies A. sediba with other australopiths and Homo; however, specific reductions and/or shape variation in the species' canines, third premolars, and anterior molars relative to the other teeth mirror the patterning characteristic of Homo. Of all samples, including east African australopiths, A. sediba appears most like H. habilis, H. erectus and H. sapiens regarding how crown size is apportioned along the tooth rows. These findings parallel those in prior studies of dental and other skeletal data, including several that suggest A. sediba is a close relative of, if not ancestral to, Homo.

Importance of air bubbles in the core of coated pellets: Synchrotron X-ray microtomography allows for new insights

High-resolution X-ray microtomography was used to get deeper insight into the underlying mass transport mechanisms controlling drug release from coated pellets. Sugar starter cores were layered with propranolol HCl and subsequently coated with Kollicoat SR, plasticized with 10% TEC. Importantly, synchrotron X-ray computed microtomography (SR-μCT) allowed direct, non-invasive monitoring of crack formation in the film coatings upon exposure to the release medium. Propranolol HCl, as well as very small sugar particles from the pellets' core, were expulsed through these cracks into the surrounding bulk fluid. Interestingly, SR-μCT also revealed the existence of numerous tiny, air-filled pores (varying in size and shape) in the pellet cores before exposure to the release medium. Upon water penetration into the system, the contents of the pellet cores became semi-solid/liquid. Consequently, the air-pockets became mobile and fused together. They steadily increased in size (and decreased in number). Importantly, “big” air bubbles were often located in close vicinity of a crack within the film coating. Thus, they play a potentially crucial role for the control of drug release from coated pellets.

Three-dimensional α-Mg dendritic morphology and branching structure transition in Mg-Zn alloys

Three-dimensional dendritic morphology and branching structure of hexagonal close-packed α-Mg in magnesium-zinc alloys possessing different zinc concentrations were studied using synchrotron X-ray microtomography. Interestingly, dendrite growth patterns were observed to undergo a morphologic transition with increasing zinc addition. Dendrite arms in the basal plane of hexagonal close-packed α-Mg tend to split and deviate from the basal plane continuously and symmetrically as a function of zinc concentrations. A hyperbranched dendrite structure was also found with an interim zinc concentration. Several types of dendrite growth patterns with different morphologies and branching structure were proposed in order to reflect the evolution of α-Mg dendrites with various zinc contents.

3D synchrotron X-ray microtomography for paper structure characterization of z-structured paper by introducing micro nanofibrillated cellulose

3D synchrotron X-ray microtomography for paper structure characterization of z-structured paper by introducing micro nanofibrillated cellulose

3D synchrotron X-ray microtomography for paper structure characterization of z-structured paper by introducing micro nanofibrillated cellulose

3D synchrotron X-ray microtomography for paper structure characterization of z-structured paper by introducing micro nanofibrillated cellulose

The origin of novel features by changes in developmental mechanisms: ontogeny and three-dimensional microanatomy of polyodontode scales of two early osteichthyans.

Recent advances in synchrotron imaging allow us to study the three-dimensional (3D) histology of vertebrate fossils, including microfossils (e.g. teeth and scales) of early jawed vertebrates. These microfossils can often be scanned at submicron resolution (<1 µm) because of their small size. The resulting voxel (3D pixel) stacks can be processed into virtual thin sections revealing almost every internal detail of the samples, comparable to traditional thin sections. In addition, 3D models of the internal microanatomical structures, such as embedded odontodes and vasculature, can be assembled and examined in situ. Scales of two early osteichthyans, Psarolepis romeri from the Early Devonian of China and Andreolepis hedei from the Late Silurian of Sweden, were scanned using propagation phase-contrast synchrotron X-ray microtomography (PPC-SRµCT), and 3D models of internal canal systems and buried odontodes were created from the scans. Based on these new data, we review the evolutionary origin of cosmine and its associated pore-canal system, which has been long recognized as a synapomorphy of sarcopterygians. The first odontode that appeared during growth shows almost identical morphology in the two scales, but the second odontode of the Psarolepis scale shows a distinctive morphology with several pores on the surface. It is suggested that a shift from ridge-like odontode to pore-bearing odontode was the key step in the origin of cosmine, which was then elaborated further in more-derived sarcopterygians. We perform a detailed comparison between the two scales and propose a primary homology framework to generate microanatomical characters, which can be used in the phylogenetic analysis of early osteichthyans when more 3D data become available. Our results highlight the importance of 3D data for the study of histology and ontogeny of the dermal skeleton of early jawed vertebrates, especially scales of the polyodontode type. The traditional microvertebrate collection is not only useful for biostratigraphic studies, but also preserves invaluable biological information about the growth of vertebrate hard tissues. Today, we are only beginning to understand the biological meaning of the new 3D data. The increasing availability of such data will enable, and indeed require, a complete revision of traditional palaeohistological studies on early vertebrates.

3D synchrotron X-ray microtomography for paper structure characterization of z-structured paper by introducing micro nanofibrillated cellulose

A layer of Micro Nanofibrillated Cellulose (MNFC) was added during the formation of TMP paper to create a z-structured paper. A MNFC layer was added either on the top or in the middle of the thickness of a TMP sheet using a Dynamic Sheet Former. The MNFC layer basis weight was varied from 2 to 20 g.m-2 for a final paper basis weight of 60 g.m-2. 3D images of the paper structure were obtained by Synchrotron X-ray microtomography, showing that localized MNFC fibrils were retained in the paper structure. The small dimensions of CNF, particularly in width, and the presence of the calcium carbonate in the MNFC layer permit to clearly differentiate the TMP fibers from the MNFC fibrils. The porosity profiles for 100% TMP sheet and 100% MNFC film present a constant internal bulk porosity at about 75% and 38%, respectively. Porosity profiles of the z-structured paper display the presence of 2 or 3 different porosity zones in the internal bulk region. These results confirm the possibility to design papers with targeted porosity gradients in the z-direction without paper post treatment.

New species from Late Cretaceous New Jersey amber and stasis in subfamily Attageninae (Insecta: Coleoptera: Dermestidae)

AbstractA new fossil species of Dermestidae (Insecta: Coleoptera), preserved in Late Cretaceous (Turonian) amber from New Jersey, is described asAttagenus(Aethriostoma)turonianensisn. sp. The specimen is fossilized in translucent amber, but 3D imaging using propagation phase-contrast X-ray synchrotron microtomography allowed detailed classification and description. This species is the oldest representative of the subfamily Attageninae and the third fossil species described in the family from the entire Mesozoic. Dermestidae comprise beetle species that typically feed on carcasses, although some Recent species ofAttagenusLatreille, 1802 are known to feed on plant debris, which is highly abundant in amber deposit sediments. This new species is evidence for diversification in the family during the Early Cretaceous as well as long morphological conservation of diagnostic features of the genusAttagenusfrom the Late Cretaceous. Analyzing the taxa from Mesozoic ambers that show stasis, the small size of the specimens together with a specific ecology could explain the stability of these lineages.

Rupture of intermetallic networks and strain localization in cast AlSi12Ni alloy: 2D and 3D characterization

Damage development during tensile straining of a cast AlSi12Ni alloy has been characterized by in situ SEM imaging and synchrotron X-ray microtomography. Two main damage mechanisms consisting of intermetallic particle rupture and decohesion of Al-Si interfaces were revealed. Particle rupture takes place already from the beginning of the deformation, while decohesion of Al-Si interfaces is more characteristic at later stages. It is shown that damage evolution in the alloy is closely related to the underlying geometry of the intermetallic phase, its clustered structure playing a double role in controlling strain localization in the matrix as well as the rupture sequence of the intermetallic phase itself. The latter shows that small clusters break-off from the complex intermetallic network before large clusters, in good agreement with their load carrying capacity determined by the local volume fraction of the intermetallic phase. Finite element modeling of the alloy's tensile behavior evidences that deformation bands formed in the alloy with complex structure are similar to those developed in a model particle reinforced metal-matrix composite, where the particles correspond to the clustered regions of the intermetallic phase.

Heart fossilization is possible and informs the evolution of cardiac outflow tract in vertebrates.

Elucidating cardiac evolution has been frustrated by lack of fossils. One celebrated enigma in cardiac evolution involves the transition from a cardiac outflow tract dominated by a multi-valved conus arteriosus in basal actinopterygians, to an outflow tract commanded by the non-valved, elastic, bulbus arteriosus in higher actinopterygians. We demonstrate that cardiac preservation is possible in the extinct fish Rhacolepis buccalis from the Brazilian Cretaceous. Using X-ray synchrotron microtomography, we show that Rhacolepis fossils display hearts with a conus arteriosus containing at least five valve rows. This represents a transitional morphology between the primitive, multivalvar, conal condition and the derived, monovalvar, bulbar state of the outflow tract in modern actinopterygians. Our data rescue a long-lost cardiac phenotype (119-113 Ma) and suggest that outflow tract simplification in actinopterygians is compatible with a gradual, rather than a drastic saltation event. Overall, our results demonstrate the feasibility of studying cardiac evolution in fossils.

Influences of hydrogen on deformation and fracture behaviors of high Zn 7XXX aluminum alloys

Hydrogen degrades the mechanical properties of high strength 7XXX aluminum alloys in two ways: (i) degrades the mechanical properties by hydrogen embrittlement, and (ii) partitioned into micropores as molecular hydrogen and make contributions to ordinary ductile fracture. The multifaceted effects of hydrogen on the mechanical properties of high Zn content 7XXX aluminum alloys during deformation and fracture is studied by using synchrotron X-ray microtomography. Our results have revealed that the hydrogen susceptibility has increased with increasing the Zn amount. High concentration of hydrogen was induced by the EDM wire eroder. This high concentrated hydrogen induces quasi-cleavage fracture and restricts the growth of micropores during ductile deformation. The threshold concentration of hydrogen ahead of the crack tip for the nucleation of quasi-cleavage feature was estimated to be $$13~\hbox {cm}^{3}/100~\hbox {g Al}$$ .

Development of the synganglion and morphology of the adult nervous system in the mite Archegozetes longisetosus Aoki (Chelicerata, Actinotrichida, Oribatida).

Small arthropods show a highly condensed central nervous system, which is accompanied by the loss of the ancestral metameric organization. This results in the formation of one solid mass, a synganglion. Although numerous studies investigated the morphology of Archegozetes longisetosus, the organization of the nervous system is to date unknown. Using synchrotron X-ray microtomography, we investigated the organization of the nervous system in the adult stage and the development of the synganglion over all five free-living life stages (larva, proto-, deuto-, tritonymph and adult). The general morphology of the synganglion resembles that of other studied mites (in the classic sense) and ticks, being subdivided into a sub- and supraesophageal region, and consisting of cortex and neuropil. All nerves entering the walking legs except the first consist of two rami. This split is not based on a functional division into a motor and a sensory ramus, but both rami contain motor and sensory neurites. Within the synganglion, we found structures that resemble the ancestral metameric organization of the nervous system of arthropods. The development of the synganglion of A. longisetosus shows a more or less linear increase in volume, but cortex and neuropil grow at different rates over the five life stages. Between the second and third nymphal stage, the volume of the neuropil increases at a faster rate than the cortex.