Synchrotron Radiation X-ray Microtomography Research Articles

Mongolitria: A new Early Cretaceous three-valved seed from Northeast Asia.

Fossil seeds recovered from the Early Cretaceous of Mongolia and Inner Mongolia, China, are described and assigned to Mongolitria gen. nov., a new genus of gymnosperm seed. Abundant lignitized seeds along with compression specimens isolated from the matrix were studied using a combination of scanning electron microscopy, anatomical sectioning, light microscopy, synchrotron radiation X-ray microtomography, and cuticle preparations. A single permineralized seed was examined by light microscopy of cellulose acetate peels and X-ray microtomography. Two species are recognized, Mongolitria friisae sp. nov. and Mongolitria exesum sp. nov. Both seeds are orthotropous with a short apical micropyle and a small, basal, circular attachment scar. The thick sclerenchymatous integument has a consistently three-parted organization and about 20 conspicuous longitudinal ribs on the surface. Mongolitria exesum differs from M. friisae primarily in its much larger size and thicker seed coat, which also preserves clear evidence of insect damage. Mongolitria is similar to other fossil seeds that have been assigned to Cycadales, but displays a unique combination of characters not found in any living or extinct cycadaceous plant, leaving its higher-level systematic affinities uncertain. Germination apparently involved splitting of the integument into three valves. Mongolitria was prominent among the plant parts accumulating in peat swamps in eastern Asia during the Early Cretaceous.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection.

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Rotating bending fatigue mechanisms of L-PBF manufactured Ti-6Al-4V alloys using in situ X-ray tomography

Lightweight titanium alloys are being increasingly used in high value structures, but in-depth knowledge of the rotating bending fatigue (RBF) mechanism remains insufficient, particularly for additively manufactured components. In response, an in situ RBF test rig was developed for the first time, using time-lapse synchrotron radiation X-ray microtomography (SR-μCT) to identify the failure behavior of laser powder bed fused Ti-6Al-4V alloys. The RBF damage evolution was characterized by combining the non-destructive SR-μCT with post-mortem scanning electron microscopy, and electron backscatter diffraction. Compared with RBF life data and fatigue long crack growth from standard specimens, in situ RBF tests proved to be reliable, in revealing the fatigue mechanism. However, fatigue short cracks in the representative mini RBF testing campaign were found to initiate from microstructural features of outer surfaces, instead of gas pores or lack of fusion defects. It is demonstrated that neither the standard nor the improved Kitagawa-Takahashi diagrams are unable to correlate the fatigue strength to manufacturing defects. The equivalent defect should include the effect of surface microstructural defects, in addition to internal defects, when studying additively manufactured alloys.

Fe2O3 for stable K-ion storage: mechanism insight into dimensional construction from stress distribution and micro-tomography.

Fe2O3 is considered a potential electrode material owing to its high theoretical capacity, low cost, and non-toxic characteristics. However, the significant volume expansion and structural degradation during charging and discharging hinder its application in potassium ion batteries. The electrochemical properties of the electrode material are primarily influenced by the diffusion efficiency of ions and the mechanics of the object. From the construction of a one dimensional structure, a three-dimensional flower-like Fe2O3 with a high specific surface and low-dimensional spherical Fe2O3 were prepared. Considering the convenience and visualization of the research, micron-scale Fe2O3 was prepared, although the larger particle size will lose part of the capacity. Notably, compared with the spherical structure, the specific capacity of the flower structure was increased by about 100%. The von Mises stress distribution on the two structures was simulated by the finite element method, revealing the mechanism of electrode failure induced by volume expansion and confirming the vital role of the multidimensional system in relieving stress concentration and improving electrochemical performance. Furthermore, synchrotron radiation soft X-ray absorption spectrum and X-ray micro-tomography revealed the phase transformation process and reaction mechanism of Fe2O3 in potassium ion batteries. The dimensional structure construction strategy reported here can provide theoretical support for modifying transition metal oxides.

Development of the Pectoral Lobed Fin in the Australian Lungfish Neoceratodus forsteri

The evolutionary transition from paired fins to limbs involved the establishment of a set of limb muscles as an evolutionary novelty. In parallel, there was a change in the topography of the spinal nerves innervating appendicular muscles, so that distinct plexuses were formed at the bases of limbs. However, the key developmental changes that brought about this evolutionary novelty have remained elusive due to a lack of data on the development of lobed fins in sarcopterygian fishes. Here, we observed the development of the pectoral fin in the Australian lungfish Neoceratodus forsteri (Sarcopterygii) through synchrotron radiation X-ray microtomography. Neoceratodus forsteri is a key taxon for understanding the fin-to-limb transition due to its close phylogenetic relationships to tetrapods and well-developed lobed fins. At the onset of the fin bud in N. forsteri, there is no mesenchyme at the junction between the axial body wall and the fin bud, which corresponds to the embryonic position of the brachial plexus formed in the mesenchyme in tetrapods. Later, concurrent with the cartilage formation in the fin skeleton, the fin adductor and abductor muscles become differentiated within the surface ectoderm of the fin bud. Subsequently, the girdle muscle, which is homologous to the tetrapod serratus muscle, newly develops at the junction between the axial body wall and the fin. Our study suggests that the acquisition of embryonic mesenchyme at the junction between the axial body wall and the appendicular bud opened the door to the formation of the brachial plexus and the specialization of individual muscles in the lineage that gave rise to tetrapods.

The spatiotemporal spread of cervical spinal cord contusion injury pathology revealed by 3D in-line phase contrast synchrotron X-ray microtomography

Extensive structural changes occur within the spinal cord following traumatic injury. Acute tissue debris and necrotic tissue are broken down, proliferating local glia and infiltrating leukocytes remodel tissue biochemical and biophysical properties, and a chronic cavity surrounded by a scar forms at the injury epicentre. Serial-section 2D histology has traditionally assessed these features in experimental models of spinal cord injury (SCI) to measure the extent of tissue pathology and evaluate efficacy of novel therapies. However, this 2D snapshot approach overlooks slice intervening features, with accurate representation of tissue compromised by mechanical processing artefacts. 3D imaging avoids these caveats and allows full exploration of the injured tissue volume to characterise whole tissue pathology. Amongst 3D imaging modalities, Synchrotron Radiation X-ray microtomography (SRμCT) is advantageous for its speed, ability to cover large tissue volumes at high resolution, and need for minimal sample processing. Here we demonstrate how extended lengths of formalin-fixed, paraffin-embedded (FFPE) rat spinal cord can be completely imaged by SRμCT with micron resolution. Label-free contrast derived from X-ray phase interactions with low-density soft tissues, reveals spinal cord white matter, gray matter, tissue damage and vasculature, with tissue still viable for targeted 2D-histology after 3D imaging. We used SRμCT to quantify tissue pathology after a midline, cervical level (C6), 225 kDyne contusion injury over acute-to-chronic (24 h to 5 weeks) post injury time points. Quantification revealed acute tissue swelling prior to chronic atrophy across the whole imaged region (spanning 2 spinal segments above and below injury), along with rostro-caudal asymmetries in white and gray matter volume loss. 3D volumes revealed satellite damage in tissue far removed from the epicentre, and extensive rostro-caudal spread of damage through the base of the dorsal columns at 24 h post injury. This damage overlapped regions of vasogenic oedema, confirmed with subsequent histology. Tissue damage at later time points in border regions was most prominent in the dorsal columns, where it overlapped sites of damaged venous vasculature. Elaborating rostro-caudal and spatiotemporal asymmetries in reduced traumatic injury models centred on these regions may inform future treatments that seek to limit the spread of tissue pathology to these ‘at-risk’ regions.

Dynamic structure model of polyelectrolyte complex based controlled-release matrix tablets visualized by synchrotron radiation micro-computed tomography.

Hydrophilic matrix tablets are the most commonly used dosage forms to fabricate oral controlled-release systems. It is highly desirable to design delivery system with novel mechanism to achieve sustained drug release through a simplified preparation process. The chitosan-anionic polymers based matrix tablets is assumed to produce self-assembly in the gastrointestinal tract, then transferring into film-coated tablets from original matrix type. But its dynamic behavior during dissolution process and the on-going internal microstructural changes during drug release were still in the dark. In this study, by using synchrotron radiation X-ray micro-tomography (SR-μCT) with phase contrast imaging, the micro-structure characteristics of chitosan-λ-carrageenan (CS-λ-CG) matrix based tablets during the dissolution were successfully elucidated for the first time. The qualitative and quantitative analyses of intensity distribution distinguished a hydrated CS-λ-CG layer from a solid core. Visualization based on 3D models provided quantitative details on the micro-structural characteristics of hydration dynamics. After CS-λ-CG matrix tablets were immersed in simulated gastric fluid (SGF) pH1.2 medium for 0.5-2.0h, the hydrated layer transformed into a gel layer and a solid swollen layer. The erosion front, swelling front, and solvent penetration front were also defined from the distinguishable micro-structures. More importantly, once the matrix tablet was transferred from SGF to the simulated intestinal fluid (SIF) pH6.8 medium, a new layer with the enhanced strength and compactness in comparison to common gels was formed on the surface of tablets. The temporal and spatial variation of 3D models further provided direct evidence for this cross-linking behavior, the new layer was composed of CS-λ-CG polyelectrolyte complexes (PEC) which subsequently dominated release mechanisms. In summary, the phase contrast SR-μCT technique was utilized to investigate the hydration dynamics of CS-λ-CG matrix tablets which was supposed to provide a novel drug release mechanism. Based on the structure feature obtained from the high contrast image, different hydration region was distinguished and the cross-linked film was identified and visualized directly for the first time.

Internal crack characteristics in very-high-cycle fatigue of a gradient structured titanium alloy

Gradient structure (GS) is commonly designed and processed in engineering materials to improve mechanical properties especially fatigue performance by taking advantage of the strengthened surface. However, whether the very-high-cycle fatigue (VHCF) property can be improved by GS is questioning due to the different crack initiation mechanisms between low-, high-cycle and VHCF. In this paper, GS of a Ti-6Al-4V alloy is generated by pre-torsion and characterized by electron backscatter diffraction. Then the VHCF behavior of the GS specimen is studied. The fractography and synchrotron radiation X-ray microtomography presented detailed characteristics of the internal crack initiation region in VHCF of the titanium alloy with GS. The results indicated that, in contrast to the low- and high-cycle regimes, the VHCF strength is reduced for the specimens with GS. Thus, the GS induced by pre-torsion cannot enhance the VHCF strength of the titanium alloy. This implies that VHCF test (property) is an important consideration for the microstructural designed materials. The graphical abstract is available in Supplementary information.

Multi-Analytical Approach for Asbestos Minerals and Their Non-Asbestiform Analogues: Inferences from Host Rock Textural Constraints

Asbestos is a hazardous mineral, as well as a common and well-known issue worldwide. However, amphiboles equal in composition but not in morphology, as well as the fibrous antigorite and lizardite, are not classified as asbestos even if more common than other forms of the mineral. Still, their potential hazardous properties requires further exploration. The proposed multi-instrumental approach focuses on the influence of textural constraints on the subsequent origin of asbestiform products in massive rock. This aspect has a significant effect on diagnostic policies addressing environmental monitoring and the clinical perspective. Concerning minerals that are chemically and geometrically (length > 5 μm, width < 3 μm and length:diameter > 3:1) but not morphologically analogous to regulated asbestos, the debate about their potential hazardous properties is open and ongoing. Therefore, a selection of various lithotypes featuring the challenging identification of fibrous phases with critical counting dimensions was investigated; this selection consisted of two serpentinites, one metabasalt and one pyroxenite. The analytical protocol included optical microscopy (OM), scanning and transmission electron microscopy combined with energy dispersive spectrometry (SEM/EDS; TEM/EDS), micro-Raman spectroscopy and synchrotron radiation X-ray microtomography (SR X-ray μCT). The latter is an original non-destructive approach that allows the observation of the fiber arrangement in a three-dimensional space, avoiding morphological influence as a result of comminution.

Characterization of Zn-Substituted Carbonated Apatite Implanted in Rat Tibia by Synchrotron Radiation X-Ray Microtomography and 3D Image Analysis.

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HIFU induced particles redistribution in polymer matrix via synchrotron radiation X-ray microtomography

High-intensity Focused Ultrasound (HIFU) was used to stimulate the embedded copper sulfate (CuSO4) particles to release from the crosslinked poly (methyl methacrylate-co-butyl acrylate) copolymer solid matrix. In order to better understand the ultrasound release mechanism for drug/polymer delivery systems, the synchrotron radiation X-ray computed microtomography (SR-CT) was used to non-destructively investigate the structure of drug/polymer delivery systems after different HIFU treatment time. For the first time, we clearly demonstrate that ultrasonic waves can overcome the constraints of the polymer chain and drive the filler to move from the strong region to the weak region in the solid polymer matrix, thus resulting in a change in distribution of the filler in solid polymers. This result also demonstrates that SR-CT is a powerful technique which can be used to quantitatively study the 3D structure of fillers/polymers composite as it can take a broader and overall view than the conventional localized two-dimensional analysis method such as SEM, TEM.

New insights into Mesozoic cycad evolution: an exploration of anatomically preserved Cycadaceae seeds from the Jurassic Oxford Clay biota

Most knowledge concerning Mesozoic Era floras has come from compression fossils. This has been augmented in the last 20 years by rarer permineralized material showing cellular preservation. Here, we describe a new genus of anatomically preserved gymnosperm seed from the Callovian–Oxfordian (Jurassic) Oxford Clay Formation (UK), using a combination of traditional sectioning and synchrotron radiation X-ray micro-tomography (SRXMT). Oxfordiana motturii gen. et sp. nov. is large and bilaterally symmetrical. It has prominent external ribs, and has a three-layered integument comprising: a narrow outer layer of thick walled cells; a thick middle parenchymatous layer; and innermost a thin fleshy layer. The integument has a longitudinal interior groove and micropyle, enveloping a nucellus with a small pollen chamber. The large size, bilateral symmetry and integumentary groove demonstrate an affinity for the new species within the cycads. Moreover, the internal groove in extant taxa is an autapomorphy of the genus Cycas, where it facilitates seed germination. Based upon the unique seed germination mechanism shared with living species of the Cycadaceae, we conclude that O. motturii is a member of the stem-group lineage leading to Cycas after the Jurassic divergence of the Cycadaceae from other extant cycads. SRXMT—for the first time successfully applied to fossils already prepared as slides—reveals the distribution of different mineral phases within the fossil, and allows us to evaluate the taphonomy of Oxfordiana. An early pyrite phase replicates the external surfaces of individual cells, a later carbonate component infilling void spaces. The resulting taphonomic model suggests that the relatively small size of the fossils was key to their exceptional preservation, concentrating sulfate-reducing bacteria in a locally closed microenvironment and thus facilitating soft-tissue permineralization.

The imaging of failure in structural materials by synchrotron radiation X-ray microtomography

The initiation and propagation of short cracks are critical to the detailed understanding of the failure mechanisms of engineering materials and structures. Therefore, for a safety critical component, it is beneficial to be able to follow the progress of cracks in loaded structures and real environments ideally at sub-micron spatial resolution and/or sub-second time resolution. Here we review the great progress that has been made in the application of synchrotron radiation X-ray computed microtomography (SR-μCT) to the study of internal damage accumulation and evolution in structural materials including cast irons and steel, nickel superalloys, lightweight titanium and aluminum alloys as well as metallic, ceramic and polymer composite materials together with additatively manufactured or three-dimensional (3D) printed metallic materials. SR-μCT is shedding light on the complex interactions of cracks with intrinsic porosity, precipitates and intermetallic inclusions and grain structure, as well as macroscopic features such as holes and joints. Furthermore it is enabling qualitative and quantitative relations between the microstructural features and engineering performance to be established and validated under realistic service loading and environmental conditions. Here we introduce the basic 3D and time-lapse (4D) tomographic methods and discuss their strengths and limitations across a range of the applications, as well as identify opportunities for the future.

Regenerative properties of collagenated porcine bone grafts in human maxilla: demonstrative study of the kinetics by synchrotron radiation microtomography and light microscopy.

Recently, it has been reported that heterologous biomaterials, where the collagen matrix is preserved, seem to facilitate blood clotting and the subsequent invasion of repairing and regenerative cells. This study aimed at evaluating the healing of human extraction sockets grafted with a collagenated cortico-cancellous porcine bone (mp3®, OsteoBiol®, Tecnoss®, Giaveno, Italy) by synchrotron radiation X-ray microtomography (microCT) and histology in order to have a 3D quantitative characterization over time. Ridge preservation with porcine bone and collagen membrane was performed on 21 patients using a flapless approach and a secondary soft tissue closure. At the time of implant placement, six bone samples were harvested, two in the 3-month group, two in the 6-month group, one in the 12-month group post-surgery, and one spontaneously healed control, and evaluated by microCT and histology. MicroCT revealed that in the grafted sites there were a greater number of trabeculae, although they appeared thinner than in the control sites; these trabeculae homogenously filled the defects, suggesting an improved strength of the socket. Histology showed that over time, the amount of biomaterial decreased and the newly formed bone increased, while less dense bone with wider marrow spaces was detected in the control sample, supporting synchrotron findings. The morphometric data converge to indicate the suitability of porcine bone for the preservation of post-extraction sockets. The use of mp3 is encouraged to preserve and heal sockets.

Meroblastic cleavage identifies some Ediacaran Doushantuo (China) embryo-like fossils as metazoans

Ediacaran Doushantuo (Formation) embryo-like fossils (EDEFs, ca. 600 Ma) from South China display cellular and sub-cellular structures and provide a unique window on the early evolution of multicellular eukaryotes. But there have been widely disparate interpretations of these fossils. Here we report new fossil embryo-like forms from the Doushantuo phosphorite that exhibit a meroblastic cleavage pattern. Our results from high-resolution propagation phase contrast–synchrotron radiation X-ray microtomography (PPC-SRµCT) demonstrate that these fossils preserve features directly comparable to those of modern meroblastic animal embryos that utilize discoidal cleavage. Given that discoidal-type meroblastic cleavage occurs only in metazoans, the phylogenetic positions of these fossils probably fall into the animal branch of the holozoan tree. Meroblastic as well as holoblastic cleavage forms were thus present by ca. 600 Ma, substantiating the conclusion derived from molecular clock estimates that a variety of metazoan lineages had evolved by the mid-Ediacaran after the termination of the Marinoan glaciation, if not earlier.

Tensile failure observations in sintered steel foam struts revealed by sub-micron contrast-enhanced microtomography

Powder metallurgical open-cell steel foams made of hollow struts are of great interest for impact resistance. Here we report experimental results of high-resolution characterisation of single struts, extracted from a commercially available steel foam. Synchrotron radiation X-ray microtomography reveals that the hollow struts are made of triplets of lens shaped rods, connected to each other along the long axis, appearing triangular in cross-sections. The struts have a non-uniform geometry and they include macro and micropores as well as high-density inclusion powder particles, poorly fused with the matrix. Micro-tensile testing showed that tensile failure is accompanied by longitudinal unzipping due to shear along the thinner material found near the hollow corners. Included, higher-density powder particles deflect crack propagation along the interface with the matrix, where much porosity is observed. Results of finite element simulations well match our mechanical tests, revealing plastic deformation due to bending and significant shear stresses arising between neighbouring rods within the same strut. The failure behaviour and the mechanical response of sintered struts in steel foams produced using non-uniformly coated polyurethane templates is the result of an interplay between the triplet geometry, sub-micron pores, precipitates and high-density inclusions.

In situ 3D topographic and shape analysis by synchrotron radiation X-ray microtomography for crystal form identification in polymorphic mixtures.

Polymorphism denotes the existence of more than one crystal structure of a substance, and great practical and theoretical interest for the chemical and pharmaceutical industries. In many cases, it is challenging to produce a pure crystal form and establish a sensitive detection method for the identification of crystal form in a mixture of polymorphs. In this study, an accurate and sensitive method based on synchrotron radiation X-ray computed microtomography (SR-μCT) was devised to identify the polymorphs of clopidogrel bisulphate (CLP). After 3D reconstruction, crystal particles were extracted and dozens of structural parameters were calculated. Whilst, the particle shapes of the two crystal forms were all irregular, the surface of CLP II was found to be rougher than CLP I. In order to classify the crystal form based on the quantitative morphological property of particles, Volume Bias Percentage based on Surface Smoothing (VBP) was defined and a new method based on VBP was successfully developed, with a total matching rate of 99.91% for 4544 particles and a lowest detectable limit of 1%. More important for the mixtures in solid pharmaceutical formulations, the interference of excipients can be avoided, a feature cannot achieved by other available analytical methods.

Microstructural investigation using synchrotron radiation X-ray microtomography reveals taste-masking mechanism of acetaminophen microspheres

The structure of solid drug delivery systems has considerable influence on drug release behaviors from particles and granules and also impacts other properties relevant to release characteristics such as taste. In this study, lipid-based microspheres of acetaminophen were prepared to mask the undesirable taste of drug and therefore to identify the optimal formulation for drug release. Synchrotron radiation X-ray computed microtomography (SR-μCT) was used to investigate the fine structural architectures of microspheres non-destructively at different sampling times during drug release test, which were simultaneously determined to quantitatively correlate the structural data with drug release behaviors. The results demonstrated that the polymeric formulation component, namely, cationic polymethacrylate (Eudragit E100), was the key factor to mask the bitter taste of acetaminophen by inhibiting immediate drug release thereby reducing the interaction intensity of the bitter material with the oral cavity taste buds. The structure and morphology of the microspheres were found to be influenced by the shape and particle size of the drug, which was also an important factor for taste-masking performance. The quantitative analysis generated detailed structural information which was correlated well with drug release behaviors. Thus, SR-μCT has been proved as a powerful tool to investigate the fine microstructure of particles and provides a new approach in the design of particles for taste masking.

Quantification of bone regeneration by virtual slices using non-destructive synchrotron X-ray microtomography

This study demonstrates a non-destructive histomorphometric analysis technique that uses virtual tissue slices obtained with synchrotron radiation X-ray microtomography (SR-μCT), and compared the results to those obtained using conventional hematoxylin-eosin (H&E) photomicrography of regenerated bone in rat calvarial defects grafted with deproteinized bovine bone substitute (Bio-Oss®). Calvarial defects (diameter, 4 mm) were created in 8 adult male Spraque-Dawley rats and filled with Bio-Oss®. The percentage of newly formed bone (NB%) was evaluated histomorphometrically using SR-μCT images and photomicrographs (H&E) 3 weeks postoperatively. Osteoconductive new bone formation was observed in the calvarial central defect. Histomorphometric analysis revealed no NB% differences between the SR-μCT and photomicrograph (H&E) groups at 3 weeks (p=0.959). The mean new bone area fractions were 17.62% and 17.95% in the analysis using SR-μCT virtual slices and conventional H&E-stained slices, respectively. Therefore, Bio-Oss® bone regeneration can be quantified non-destructively using SR-μCT at an accuracy comparable to that obtained using conventional photomicrography.

Mechanical Simulation of the Localized Deformation in the Aluminum Foams: A Three-dimensional (3D) Structure Based Study

Metal-foam materials have been used increasingly in industry for their low-density, high-toughness and high impact resistance properties. Understanding the macro-scale mechanical properties of these materials is essential to evaluate their actual performance and thus to optimize the structures and properties accordingly. Synchrotron radiation X-ray microtomographytechnique is a promising method to study 3D structures at small length scales, which provides high spatial resolution and allows the researchers to observe the change of structures/features in situ without destroying the original objects. In this work, the real 3D structure of closed-cell aluminum foam was obtained by using synchrotron radiation X-ray microtomography. The reconstructed 3D model of the foam was further utilized as input for the subsequent mechanical study to investigate the localized deformation behaviors and evolution process of the foam under longitudinal quasi-static uniaxial compressive loading. By analyzing the simulated results, it is demonstrated that the deformation bands always initiate and propagate along the cell walls which are finally folded upon loading. And the large spherical cells are more susceptible to yielding, as well as to the stress concentration than the cells with other shapes. This finding is consistent with the experimental results.