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Significance Axons, the brain’s communication cables, have been described as cylinders since their discovery in 1860. Their structure is linked to how fast they conduct signals and is thus indicative of brain health and function. Here, we demonstrate an interplay between the micromorphology of axons and other extra-axonal structures, showing that axons are noncylindrical and exhibit environment-dependent diameter and trajectory variations. The nonspecificity in diameter, and thus conduction velocity, challenges the current knowledge of how axons communicate signals. Diffusion magnetic resonance imaging can be used to measure axon diameter in the living brain in order to explore the brain network and detect potential biomarkers of disease, but we show here that the observed complex morphologies of axons bias these measurements., Axonal conduction velocity, which ensures efficient function of the brain network, is related to axon diameter. Noninvasive, in vivo axon diameter estimates can be made with diffusion magnetic resonance imaging, but the technique requires three-dimensional (3D) validation. Here, high-resolution, 3D synchrotron X-ray nano-holotomography images of white matter samples from the corpus callosum of a monkey brain reveal that blood vessels, cells, and vacuoles affect axonal diameter and trajectory. Within single axons, we find that the variation in diameter and conduction velocity correlates with the mean diameter, contesting the value of precise diameter determination in larger axons. These complex 3D axon morphologies drive previously reported 2D trends in axon diameter and g-ratio. Furthermore, we find that these morphologies bias the estimates of axon diameter with diffusion magnetic resonance imaging and, ultimately, impact the investigation and formulation of the axon structure–function relationship.

World journal of gastroenterology 28(29), 3994 - 4006 (2022). doi:10.3748/wjg.v28.i29.3994, BACKGROUNDThe enteric nervous system (ENS) is situated along the entire gastrointestinal tract and is divided into myenteric and submucosal plexuses in the small and large intestines. The ENS consists of neurons, glial cells, and nerves assembled into ganglia, surrounded by telocytes, interstitial cells of Cajal, and connective tissue. Owing to the complex spatial organization of several interconnections with nerve fascicles, the ENS is difficult to examine in conventional histological sections of 3-5 μm.AIMTo examine human ileum full-thickness biopsies using X-ray phase-contrast nanotomography without prior staining to visualize the ENS.METHODSSix patients were diagnosed with gastrointestinal dysmotility and neuropathy based on routine clinical and histopathological examinations. As controls, full-thickness biopsies were collected from healthy resection ileal regions after hemicolectomy for right colon malignancy. From the paraffin blocks, 4-µm thick sections were prepared and stained with hematoxylin and eosin for localization of the myenteric ganglia under a light microscope. A 1-mm punch biopsy (up to 1 cm in length) centered on the myenteric plexus was taken and placed into a Kapton® tube for mounting in the subsequent investigation. X-ray phase-contrast tomography was performed using two custom-designed laboratory setups with micrometer resolution for overview scanning. Subsequently, selected regions of interest were scanned at a synchrotron-based end-station, and high-resolution slices were reported. In total, more than 6000 virtual slices were analyzed from nine samples.RESULTSIn the overview scans, the general architecture and quality of the samples were studied, and the myenteric plexus was localized. High-resolution scans revealed details, including the ganglia, interganglional nerve fascicles, and surrounding tissue. The ganglia were irregular in shape and contained neurons and glial cells. Spindle-shaped cells with very thin cellular projections could be observed on the surface of the ganglia, which appeared to build a network. In the patients, there were no alterations in the general architecture of the myenteric ganglia. Nevertheless, several pathological changes were observed, including vacuolar degeneration, autophagic activity, the appearance of sequestosomes, chromatolysis, and apoptosis. Furthermore, possible expulsion of pyknotic neurons and defects in the covering cellular network could be observed in serial slices. These changes partly corresponded to previous light microscopy findings.CONCLUSIONThe analysis of serial virtual slices could provide new information that cannot be obtained by classical light microscopy. The advantages, disadvantages, and future possibilities of this method are also discussed., Published by WJG Press, Beijing

Background: Enteric neuropathy is described in most patients with gastrointestinal dysmotility and may be found together with reduced intraepidermal nerve fiber density (IENFD). The aim of this pilot study was to assess whether three-dimensional (3d) imaging of skin biopsies could be used to examine various tissue components in patients with gastrointestinal dysmotility. Material and methods: Four dysmotility patients of different etiology and two healthy volunteers were included. From each subject, two 3-mm punch skin biopsies were stained with antibodies against protein gene product 9.5 or evaluated as a whole with two X-ray phase-contrast computed tomography (CT) setups, a laboratory µCT setup and a dedicated synchrotron radiation nanoCT end-station. Results: Two patients had reduced IENFD, and two normal IENFD, compared with controls. µCT and X-ray phase-contrast holographic nanotomography scanned whole tissue specimens, with optional high-resolution scans revealing delicate structures, without differentiation of various fibers and cells. Irregular architecture of dermal fibers was observed in the patient with Ehlers-Danlos syndrome and the patient with idiopathic dysmotility showed an abundance of mesenchymal ground substance. Conclusions: 3d phase-contrast tomographic imaging may be useful to illustrate traits of connective tissue dysfunction in various organs and to demonstrate whether disorganized dermal fibers could explain organ dysfunction. (Less)

This study aimed to explore the value of synchrotron-based phase-contrast microcomputed tomography (micro-CT) in pulmonary vascular pathobiology. The microanatomy of the lung is complex with intricate branching patterns. Tissue sections are therefore difficult to interpret. Recruited intrapulmonary bronchopulmonary anastomoses (IBAs) have been described in several forms of pulmonary hypertension, including alveolar capillary dysplasia with misaligned pulmonary veins (ACD/MPV). Here, we examine paraffin-embedded tissue using this nondestructive method for high-resolution three-dimensional imaging. Blocks of healthy and ACD/MPV lung tissue were used. Pulmonary and bronchial arteries in the ACD/MPV block had been preinjected with dye. One section per block was stained, and areas of interest were marked to allow precise beam-alignment during image acquisition at the X02DA TOMCAT beamline (Swiss Light Source). A ×4 magnifying objective coupled to a 20-µm thick scintillating material and a sCMOS detector yielded the best trade-off between spatial resolution and field-of-view. A phase retrieval algorithm was applied and virtual tomographic slices and video clips of the imaged volumes were produced. Dye injections generated a distinct attenuation difference between vessels and surrounding tissue, facilitating segmentation and three-dimensional rendering. Histology and immunohistochemistry post-imaging offered complementary information. IBAs were confirmed in ACD/MPV, and the MPVs were positioned like bronchial veins/venules. We demonstrate the advantages of using synchrotron-based phase-contrast micro-CT for three-dimensional characterization of pulmonary microvascular anatomy in paraffin-embedded tissue. Vascular dye injections add additional value. We confirm intrapulmonary shunting in ACD/MPV and provide support for the hypothesis that MPVs are dilated bronchial veins/venules.

X-ray fluorescence microscopy performed at nanofocusing synchrotron beamlines produces quantitative elemental distribution maps at unprecedented resolution (down to a few tens of nanometres), at the expense of relatively long measuring times and high absorbed doses. In this work, a method was implemented in which fast low-dose in-line holography was used to produce quantitative electron density maps at the mesoscale prior to nanoscale X-ray fluorescence acquisition. These maps ensure more efficient fluorescence scans and the reduction of the total absorbed dose, often relevant for radiation-sensitive (e.g. biological) samples. This multimodal microscopy approach was demonstrated on human sural nerve tissue. The two imaging modes provide complementary information at a comparable resolution, ultimately limited by the focal spot size. The experimental setup presented allows the user to swap between them in a flexible and reproducible fashion, as well as to easily adapt the scanning parameters during an experiment to fine-tune resolution and field of view.

In this paper, super-resolution imaging is described and evaluated for x-ray tomography and is compared with standard tomography and upscaling during reconstruction. Blurring is minimized due to the negligible point spread of photon counting detectors and an electromagnetically movable micro-focus x-ray spot. Scans are acquired in high and low magnification geometry, where the latter is used to minimize penumbral blurring from the x-ray source. Sharpness and level of detail can be significantly increased in reconstructed slices to the point where the source size becomes the limiting factor. The achieved resolution of the different methods is quantified and compared using biological samples via the edge spread function, modulation transfer function, and Fourier ring correlation.

In pulmonary arterial hypertension, plexiform lesions are associated with severe arterial obstruction and right ventricular failure. Exploring their structure and position is crucial for understanding the interplay between hemodynamics and vascular remodeling. The aim of this research was to use synchrotron-based phase-contrast micro-CT to study the three-dimensional structure of plexiform lesions. Archived paraffin-embedded tissue samples from 14 patients with pulmonary arterial hypertension (13 idiopathic, 1 with known BMPR2-mutation) were imaged. Clinical data showed high-median PVR (12.5 WU) and mPAP (68 mmHg). Vascular lesions with more than 1 lumen were defined as plexiform. Prior radiopaque dye injection in some samples facilitated 3-D rendering. Four distinct types of plexiform lesions were identified: 1) localized within or derived from monopodial branches (supernumerary arteries), often with a connection to the vasa vasorum; 2) localized between pulmonary arteries and larger airways as a tortuous transformation of intrapulmonary bronchopulmonary anastomoses; 3) as spherical structures at unexpected abrupt ends of distal pulmonary arteries; and 4) as occluded pulmonary arteries with recanalization. By appearance and localization, types 1–2 potentially relieve pressure via the bronchial circulation, as pulmonary arteries in these patients were almost invariably occluded distally. In addition, types 1–3 were often surrounded by dilated thin-walled vessels, often connected to pulmonary veins, peribronchial vessels, or the vasa vasorum. Collaterals, bypassing completely occluded pulmonary arteries, were also observed to originate within plexiform lesions. In conclusion, synchrotron-based imaging revealed significant plexiform lesion heterogeneity, resulting in a novel classification. The four types likely have different effects on hemodynamics and disease progression.

First results of in-line holography and holotomography from the NanoMAX beamline at MAX IV are presented., Coherent X-ray imaging techniques, such as in-line holography, exploit the high brilliance provided by diffraction-limited storage rings to perform imaging sensitive to the electron density through contrast due to the phase shift, rather than conventional attenuation contrast. Thus, coherent X-ray imaging techniques enable high-sensitivity and low-dose imaging, especially for low-atomic-number (Z) chemical elements and materials with similar attenuation contrast. Here, the first implementation of in-line holography at the NanoMAX beamline is presented, which benefits from the exceptional focusing capabilities and the high brilliance provided by MAX IV, the first operational diffraction-limited storage ring up to approximately 300 eV. It is demonstrated that in-line holography at NanoMAX can provide 2D diffraction-limited images, where the achievable resolution is only limited by the 70 nm focal spot at 13 keV X-ray energy. Also, the 3D capabilities of this instrument are demonstrated by performing holotomography on a chalk sample at a mesoscale resolution of around 155 nm. It is foreseen that in-line holography will broaden the spectra of capabilities of MAX IV by providing fast 2D and 3D electron density images from mesoscale down to nanoscale resolution.

Acta biomaterialia 136, 582 - 591 (2021). doi:10.1016/j.actbio.2021.09.047, Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is controversial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (��CT) and neutron ��CT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation., Published by Elsevier, [Amsterdam]

A deeper knowledge of the architecture of the peripheral nerve with three-dimensional (3D) imaging of the nerve tissue at the sub-cellular scale may contribute to unravel the pathophysiology of neuropathy. Here we demonstrate the feasibility of X-ray phase contrast holographic nanotomography to enable 3D imaging of nerves at high resolution, while covering a relatively large tissue volume. We show various subcomponents of human peripheral nerves in biopsies from patients with type 1 and 2 diabetes and in a healthy subject. Together with well-organized, parallel myelinated nerve fibres we show regenerative clusters with twisted nerve fibres, a sprouted axon from a node of Ranvier and other specific details. A novel 3D construction (with movie created) of a node of Ranvier with end segment of a degenerated axon and sprout of a regenerated one is captured. Many of these architectural elements are not described in the literature. Thus, X-ray phase contrast holographic nanotomography enables identifying specific morphological structures in 3D in peripheral nerve biopsies from a healthy subject and from patients with type 1 and 2 diabetes. Funding Agencies|EU InterReg project MAX4ESSFUN [KU-008]; Swedish Research CouncilSwedish Research Council [E0605401, E0605402]; Lund University

Objectives: Light microscopical analysis in two dimensions, combined with immunohistochemistry, is presently the gold standard to describe the enteric nervous system (ENS). Our aim was to assess the usefulness of three-dimensional (3D) imaging by X-ray phase-contrast tomography in evaluating the ENS of the human bowel. Material and methods: Myenteric ganglia were identified in full-thickness biopsies of the ileum and colon by hematoxylin & eosin staining. A1-mm biopsy punch was taken from the paraffin blocks and placed into a Kapton® tube for subsequent tomographic investigation. The samples were scanned, without further preparation, using phase-contrast tomography at two different scales: overview scans (performed with laboratory setups), which allowed localization of the nervous tissue (∼1µm effective voxel size); and high-resolution scans (performed with a synchrotron endstation), which imaged localized regions of 320x320x320 µm3 (176 nm effective voxel size). Results: The contrast allowed us to follow the shape and the size changes of the ganglia, as well as to study their cellular components together with the cells and cellular projections of the periganglional space. Furthermore, it was possible to show the 3D network of the myenteric plexus and to quantify its volume within the samples. Conclusions: Phase-contrast X-ray tomography can be applied for volume analyses of the human ENS and to study tissue components in unstained paraffin-embedded tissue biopsies. This technique could potentially be used to study disease mechanisms, and to compare healthy and diseased tissues in clinical research.

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Whether hydroxyapatite (HA) orientation in fossilised bone samples can be non-destructively retrieved and used to determine the arrangement of the bone matrix and the location of muscle attachments (entheses), is a question of high relevance to palaeontology, as it facilitates a detailed understanding of the (micro-)anatomy of extinct species with no damage to the precious fossil specimens. Here, we report studies of two fossil bone samples, specifically the tibia of a 300-million-year-old tetrapod, Discosauriscus austriacus, and the humerus of a 370-million-year-old lobe-finned fish, Eusthenopteron foordi, using XRD-CT – a combination of X-ray diffraction (XRD) and computed tomography (CT). Reconstructed 3D images showing the spatial mineral distributions and the local orientation of HA were obtained. For Discosauriscus austriacus, details of the muscle attachments could be discerned. For Eusthenopteron foordi, the gross details of the preferred orientation of HA were deduced using three tomographic datasets obtained with orthogonally oriented rotation axes. For both samples, the HA in the bone matrix exhibited preferred orientation, with the unit cell c-axis of the HA crystallites tending to be parallel with the bone surface. In summary, we have demonstrated that XRD-CT combined with an intuitive reconstruction procedure is becoming a powerful tool for studying palaeontological samples.

Osteoporosis, a prevalent metabolic bone disorder, predisposes individuals to increased susceptibility to fractures. It is also, somewhat controversially, thought to delay or impair the regenerative response. Using high-resolution Fourier-transform infrared spectroscopy and small/wide-angle X-ray scattering we sought to answer the following questions: Does the molecular composition and the nano-structure in the newly regenerated bone differ between healthy and osteoporotic environments? And how do pharmacological treatments, such as bone morphogenetic protein 7 (BMP-7) alone or synergistically combined with zoledronate (ZA), alter callus composition and nano-structure in such environments? Cumulatively, on the basis of compositional and nano-structural characterizations of newly formed bone in an open-osteotomy rat model, the healing response in untreated healthy and ovariectomy-induced osteoporotic environments was fundamentally the same. However, the BMP-7 induced osteogenic response resulted in greater heterogeneity in the nano-structural crystal dimensions and this effect was more pronounced with osteoporosis. ZA mitigated the effects of the upregulated catabolism induced by both BMP-7 and an osteoporotic bone environment. The findings contribute to our understanding of how the repair processes in healthy and osteoporotic bone differ in both untreated and treated contexts and the data presented represents the most comprehensive study of fracture healing at the nanoscale undertaken to date.

Botulinum-toxin A (BoNT/A) is used for a wide range of conditions. Intramuscular administration of BoNT/A inhibits the release of acetylcholine at the neuromuscular junction from presynaptic motor neurons causing muscle-paralysis. The aim of the present study was to investigate the effect of high dose intramuscular BoNT/A injections (6 UI = 60 pg) on muscle tissue. The gait pattern of the rats was significantly affected 3 weeks after BoNT/A injection. The ankle joint rotated externally, the rats became flat footed, and the stride length decreased after BoNT/A injection. Additionally, there was clear evidence of microstructural changes on the tissue level by as evidenced by 3D imaging of the muscles by Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM). Both the fibrillar and the non-fibrillar tissues were affected. The volume fraction of fibrillary tissue was reduced significantly and the non-fibrillar tissue increased. This was accompanied by a loss of the linear structure of the muscle tissue. Furthermore, gene expression analysis showed a significant upregulation of COL1A1, MMP-2, TGF-b1, IL-6, MHCIIA and MHCIIx in the BoNT/A injected leg, while MHVIIB was significantly downregulated. In conclusion: The present study reveals that high dose intramuscular BoNT/A injections cause microstructural damage of the muscle tissue, which contributes to impaired gait.

Open Data Science Mesh (CS3MESH4EOSC) is a newly funded project to create a new generation, interoperable federation of data and higher-level services to enable friction-free collaboration between European researchers. This new EU-funded project brings together 12 partners from the CS3 community (Cloud Synchronization and Sharing Services). The consortium partners include CERN, Danish Technical University (DK), SURFSARA (NL), Poznan Supercomputing Centre (PL), CESNET (CZ), AARNET (AUS), SWITCH (CH), University of Munster (DE), Ailleron SA (PL), Cubbit (IT), Joint Research Centre (BE) and Fundacion ESADE (ES). CERN acts as project coordinator. The consortium already operates services and storage-centric infrastructure for around 300 thousand scientists and researchers across the globe. The project will integrate these local existing sites and services into a seamless mesh infrastructure which is fully interconnected with the EOSC-Hub, as proposed in the European Commission's Implementation Roadmap for EOSC. The project will provide a framework for applications in several major areas: Data Science Environments, Open Data Systems, Collaborative Documents, On-demand Large Dataset Transfers and Cross-domain Data Sharing. The collaboration between the users will be enabled by a simple sharing mechanism: a user will select a file or folder to share with other users at other sites. Such shared links will be established and removed dynamically by the users from a streamline web interface of their local storage systems. The mesh will automatically and contextually enable different research workflow actions based on type of content shared in the folder. One of the excellence areas of CS3 services is access to content from all types of devices: web, desktop applications and mobile devices. The project augments this capability to access content stored on remote sites and will *in practice* introduce FAIR principles in European Science. The project with leverage on technologies developed and integrated in the research community, such as ScienceBox (CERNBox, SWAN, EOS), EGI-CheckIn, File Transfer Service (FTS), ARGO, EduGAIN and others. The project will also involve commercial cloud providers, integrating their software and services

Here we report a method for increased resolution of single exposure three modality x-ray images using super-resolution. The three x-ray image modalities are absorption-, differential phase-contrast-, and dark-field-images. To create super-resolution, a non-mechanically movable micro-focus x-ray source is used. A series of almost identical x-ray projection images is obtained while the point source is translated in a two-dimensional grid pattern. The three image modalities are extracted from fourier space using spatial harmonic analysis, also known as the single-shot method. Using super-resolution on the low-resolution series of the three modalities separately results in high-resolution images for the modalities. This approach allows to compensate for the inherent loss in resolution caused by the single-shot method without increasing the need for stability or algorithms accounting for possible motion.

In this paper we demonstrate a method for novelty detection of foreign objects in food products using grating-based multimodal X-ray imaging. With this imaging technique three modalities are available with pixel correspondence, enhancing organic materials such as wood chips, insects and soft plastics not detectable by conventional X-ray absorption radiography. We conduct experiments, where several food products are imaged with common foreign objects typically found in the food processing industry. To evaluate the benefit from using this multi-contrast X-ray technique over conventional X-ray absorption imaging, a novelty detection scheme based on well known image- and statistical analysis techniques is proposed. The results show that the presented method gives superior recognition results and highlights the advantage of grating-based imaging.

The macro- and micro-features of bone can be assessed by using imaging methods. However, nano- and molecular features require more detailed characterization, such as use of e.g., vibrational spectroscopy and X-ray scattering. Nano- and molecular features also affect the mechanical competence of bone tissue. The aim of the present study was to reveal the effects of mineralization and its alterations on the mineral crystal scale, by investigating the spatial variation of molecular composition and mineral crystal structure across the cross-section of femur diaphyses in young rats, and healthy and osteoporotic mature rats (N=5). Fourier transform infrared spectroscopy and scanning small- and wide-angle X-ray scattering (SAXS/WAXS) techniques with high spatial resolution were used at identical locations over the whole cross-section. This allowed quantification of point-by-point information about the spatial distribution of mineral crystal volume. All measured parameters (crystal dimensions, degree of orientation and predominant orientation) varied across the cortex. Specifically, the crystal dimensions were lower in the central cortex than in the endosteal and periosteal regions. Mineral crystal orientation followed the cortical circumference in the periosteal and endosteal regions, but was less well-oriented in the central regions. Central cortex is formed rapidly during development through endochondral ossification. Since rats possess no osteonal remodeling, this bone remains (until old age). Significant linear correlations were observed between the dimensional and organizational parameters, e.g., between crystal length and degree of orientation (R2=0.83, p

Scanned-energy mode photoelectron diffraction (PhD) and ab initio density functional theory calculations have been employed to investigate the adsorption geometry of benzoate ([C6H5COO]−) on rutile-TiO2(110)(1 × 1). PhD data indicate that the benzoate moiety binds to the surface through both of its oxygen atoms to two adjacent fivefold surface titanium atoms in an essentially upright geometry. Moreover, its phenyl (C6H5−) and carboxylate ([−COO]−) groups are determined to be coplanar, being aligned along the [001] azimuth. This experimental result is consistent with the benzoate geometry emerging from DFT calculations conducted for laterally rather well-separated adsorbates. At shorter interadsorbate distances, the theoretical modeling predicts a more tilted and twisted adsorption geometry, where the phenyl and carboxylate groups are no longer coplanar; i.e., interadsorbate interactions influence the configuration of adsorbed benzoate.

The purpose of this study was to perform an initial investigation of the possibility to determine breast cancer growth rate with (14)C bomb-pulse dating. Tissues from 11 breast cancers, diagnosed in 1983, were retrieved from a regional biobank. The estimated average age of the majority of the samples overlapped the year of collection (1983) within 3σ Thus, this first study of tumour tissue has not yet demonstrated that (14)C bomb-pulse dating can obtain information on the growth of breast cancer. However, with further refinement, involving extraction of cell types and components, there is a possibility that fundamental knowledge of tumour biology might still be gained by the bomb-pulse technique. Additionally, δ (13)C and δ (15)N analyses were performed to obtain dietary and metabolic information, and to serve as a base for improvement of the age determination.

Visually guided flight control in the rainforest is arguably one of the most complex insect behaviors: illumination varies dramatically depending on location [1], and the densely cluttered environment blocks out most of the sky [2]. What visual information do insects sample for flight control in this habitat? To begin answering this question, we determined the visual fields of the ocelli-thought to play a role in attitude stabilization of some flying insects [3-5]-of an orchid bee, Euglossa imperialis. High-resolution 3D models of the ocellar system from X-ray microtomography were used for optical ray tracing simulations. Surprisingly, these showed that each ocellus possesses two distinct visual fields-a focused monocular visual field suitable for detecting features elevated above the horizon and therefore assisting with flight stabilization [3-5] and, unlike other ocelli investigated to date [4, 6, 7], a large trinocular fronto-dorsal visual field shared by all ocelli. Histological analyses show that photoreceptors have similar orientations within each ocellus and are likely to be sensitive to polarized light, as in some other hymenopterans [7, 8]. We also found that the average receptor orientation is offset between the ocelli, each having different axes of polarization sensitivity relative to the head. Unlike the eyes of any other insect described to date, this ocellar system meets the requirements of a true polarization analyzer [9, 10]. The ocelli of E. imperialis could provide sensitive compass information for navigation in the rainforest and, additionally, provide cues for visual discrimination or flight control.

When used in combination with raster scanning, small-angle X-ray scattering (SAXS) has proven to be a valuable imaging technique of the nanoscale, for example of bone, teeth and brain matter. Although two-dimensional projection imaging has been used to characterize various materials successfully, its three-dimensional extension, SAXS computed tomography, poses substantial challenges, which have yet to be overcome. Previous work using SAXS computed tomography was unable to preserve oriented SAXS signals during reconstruction. Here we present a solution to this problem and obtain a complete SAXS computed tomography, which preserves oriented scattering information. By introducing virtual tomography axes, we take advantage of the two-dimensional SAXS information recorded on an area detector and use it to reconstruct the full three-dimensional scattering distribution in reciprocal space for each voxel of the three-dimensional object in real space. The presented method could be of interest for a combined six-dimensional real and reciprocal space characterization of mesoscopic materials with hierarchically structured features with length scales ranging from a few nanometres to a few millimetres--for example, biomaterials such as bone or teeth, or functional materials such as fuel-cell or battery components.

We present a new method for detecting fractures in solid materials below the resolution given by the detector pixel size by using grating-based X-ray interferometry. The technique is particularly useful for detecting sub-pixel cracks in large samples where the size of the sample is preventing high-resolution μCT studies of the entire sample. The X-ray grating interferometer produces three distinct modality signals: absorption, phase and dark field. The method utilizes the unique scattering features of the dark-field signal. We have used tomograms reconstructed from each of the three signals to detect cracks in a model sample consisting of stearin.

We show how radiological images of both single and multi material samples can be simulated using the Monte Carlo simulation tool McXtrace and how these images can be used to make a three dimensional reconstruction. Good numerical agreement between the X-ray attenuation coefficient in experimental and simulated data can be obtained, which allows us to use simulated projections in the linearisation procedure for single material samples and in that way reduce beam hardening artefacts. The simulations can be used to predict beam hardening artefacts in multi material samples with complex geometry, illustrated with an example. Linearisation requires knowledge about the X-ray transmission at varying sample thickness, but in some cases homogeneous calibration phantoms are hard to manufacture, which affects the accuracy of the calibration. Using simulated data overcomes the manufacturing problems and in that way improves the calibration. (C) 2014 Elsevier B.V. All rights reserved. (Less)

Extracting microanatomical information beyond the image resolution of MRI would provide valuable tools for diagnostics and neuroscientific research. A number of mathematical models already suggest microstructural interpretations of diffusion MRI (dMRI) data. Examples of such microstructural features could be cell bodies and neurites, e.g. the axon's diameter or their orientational distribution for global connectivity analysis using tractography, and have previously only been possible to access through conventional histology of post mortem tissue or invasive biopsies. The prospect of gaining the same knowledge non-invasively from the whole living human brain could push the frontiers for the diagnosis of neurological and psychiatric diseases. It could also provide a general understanding of the development and natural variability in the healthy brain across a population. However, due to a limited image resolution, most of the dMRI measures are indirect estimations and may depend on the whole chain from experimental parameter settings to model assumptions and implementation. Here, we review current literature in this field and highlight the integrative work across anatomical length scales that is needed to validate and trust a new dMRI method. We encourage interdisciplinary collaborations and data sharing in regards to applying and developing new validation techniques to improve the specificity of future dMRI methods.

Dark-field imaging is a scattering-based X-ray imaging method that can be performed with laboratory X-ray tubes. The possibility to obtain information about unresolvable structures has already seen a lot of interest for both medical and material science applications. Unlike conventional X-ray attenuation, orientation dependent changes of the dark-field signal can be used to reveal microscopic structural orientation. To date, reconstruction of the three-dimensional dark-field signal requires dedicated, highly complex algorithms and specialized acquisition hardware. This severely hinders the possible application of orientation-dependent dark-field tomography. In this paper, we show that it is possible to perform this kind of dark-field tomography with common Talbot-Lau interferometer setups by reducing the reconstruction to several smaller independent problems. This allows for the reconstruction to be performed with commercially available software and our findings will therefore help pave the way for a straightforward implementation of orientation-dependent dark-field tomography.

Developments in X-Ray Tomography XI : [Proceedings] - SPIE, 2017. - ISBN 9781510612396 - doi:10.1117/12.2275121 Developments in X-Ray Tomography XI, San Diego, United States, 6 Aug 2017 - 10 Aug 2017; Proceedings of SPIE 10391, 103910 (2017). doi:10.1117/12.2275121, Permanent implants made of titanium or its alloys are the gold standard in many orthopedic and traumatological applications due to their good biocompatibility and mechanical properties. However, a second surgical intervention is required for this kind of implants as they have to be removed in the case of children that are still growing or on patient’s demand. Therefore, magnesium-based implants are considered for medical applications as they are degraded under physiological conditions. The major challenge is tailoring the degradation in a manner that is suitable for a biological environment and such that stabilization of the bone is provided for a controlled period. In order to understand failure mechanisms of magnesium-based implants in orthopedic applications and, further, to better understand the osseointegration, screw implants in bone are studied under mechanical load by means of a push-out device installed at the imaging beamline P05 of PETRA III at DESY. Conventional absorption contrast microtomography and phasecontrast techniques are applied in order to monitor the bone-to-implant interface under increasing load conditions. In this proof-of-concept study, first results from an in situ push-out experiment are presented., Published by SPIE, Bellingham, Wash.

The implementation of hybrid fluorescence molecular tomography (FMT) and X-ray computed tomography (CT) has been shown to be a necessary development, not only for combining anatomical with functional and molecular contrast, but also for generating optical images of high accuracy. FMT affords highly sensitive 3-D imaging of fluorescence bio-distribution, but in stand-alone form it offers images of low resolution. It was shown that FMT accuracy significantly improves by considering anatomical priors from CT. Conversely, CT generally suffers from low soft tissue contrast. Therefore utilization of CT data as prior information in FMT inversion is challenging when different internal organs are not clearly differentiated. Instead, we combined herein FMT with emerging X-ray phase-contrast CT (PCCT). PCCT relies on phase shift differences in tissue to achieve soft tissue contrast superior to conventional CT. We demonstrate for the first time FMT-PCCT imaging of different animal models, where FMT and PCCT scans were performed in vivo and ex vivo, respectively. The results show that FMT-PCCT expands the potential of FMT in imaging lesions with otherwise low or no CT contrast, while retaining the cost benefits of CT and simplicity of hybrid device realizations. The results point to the most accurate FMT performance to date.