Articles de revues : « X-Ray Micro-CT (Micro-Tomography) »

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Ishii, Keizo. « Micron X-ray computed tomography based on micro-particle-induced X-ray emission ». International Journal of PIXE 25, n^o 03n04 (janvier 2015) : 187–215. http://dx.doi.org/10.1142/s0129083515500175.

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Particle-induced X-ray emission (PIXE) is a phenomenon of atomic inner shell ionization and characteristic X-ray emission due to ion-atomic collisions. The intensity of continuous X-rays in the PIXE energy spectrum is much lower than that of characteristic X-rays. Therefore, PIXE can be used as a semi-monochromatic X-ray source. Furthermore, PIXE produced by a heavily charged particle beam with a diameter of several micrometers (micro-PIXE) can be used as a monochromatic X-ray point source for Xray computed tomography (CT) to investigate internal structures of objects <1 mm. We developed micron X-ray CT based on micro-PIXE with a spatial resolution of about 4 μm. Because the photoelectric effect cross-section is proportional to the fifth power of the atomic number, the distributions of small amounts of heavy elements can be investigated using this CT technique, and the element can be identified using its absorption edge. We applied this CT to observe the internal structure of hair, a head of an ant, and Drosophila. We were able to identify the medulla configuration and cortex of the hair, and the mandibular glands, pharynx, and brain in the ant head. We confirmed a high Mn concentration in the mandibular glands. We used a contrast agent to visualize the internal organs of Drosophila. Furthermore, we applied this CT to research clay particles contaminated by the Fukushima Dai-ichi nuclear accident and confirmed that cesium atoms were distributed on the surfaces of clay particles.

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Batranin, Andrey, Denis Ivashkov et Sergei Stuchebrov. « Performance Evaluation of Micro-CT Scanners as Visualization Systems ». Advanced Materials Research 1084 (janvier 2015) : 694–97. http://dx.doi.org/10.4028/www.scientific.net/amr.1084.694.

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High-resolution X-ray tomography, also known as micro-computed tomography (micro-CT) or microtomography, is a versatile evaluation technique, which extends application in various fields including material science. Micro-CT is a suitable method for quantitative and dimensional materials characterization. Needless to say, the accuracy of the method and applied equipments – micro-CT scanners – should be assessed to obtain reliable, solid results. In this paper, the performance of a micro-CT scanner as a visualization system is discussed. Quantitative parameters of image quality and visualization systems as well as methods to obtain their numerical values are briefly described. The results of experiments carried out on in-house made micro-CT scanner TOLMI-150-10 developed in Tomsk Polytechnic University are presented.

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Obenaus, André, et Anna Smith. « Radiation dose in rodent tissues during micro-CT imaging ». Journal of X-Ray Science and Technology : Clinical Applications of Diagnosis and Therapeutics 12, n^o 4 (janvier 2004) : 241–49. http://dx.doi.org/10.3233/xst-2004-00116.

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The use of non-invasive imaging modalities, including micro X-ray computed tomography (micro-CT), is starting to be used extensively to investigate normal and pathological states in a variety of animal models. This increased use of in vivo imaging requires a better understanding of the radiation dose delivered during routine imaging. Our laboratory is equipped with a micro X-ray computer tomography unit (MicroCAT II®, ImTek Inc., Knoxville, TN) with a 60 kVp X-ray source and a reconstruction volume resolution as low as 15 microns that is used for proton radiation therapy treatment planning. In order to determine the X-ray radiation dose delivered to skin and internal organs by our micro-CT we implanted new, calibrated Harshaw TLD-100 Lithium Fluoride thermo-luminescent detectors (TLDs), into five C57BL/6 male mice and ten Sprague-Dawley male rats. Implants were made into the brain, heart, right lung, liver, stomach, cecum, bladder, dorsal thoracal skin and ventral abdominal skin in each animal. Animals were each scanned once using 50 kVp at 800 μA with 360 projections per scan with each projection lasting 400 msec. Using the TLD readings, the radiation dose from each body location was measured with the dorsal thoracal skin receiving the highest average dose (4.5 cGy, mouse; 2.8 cGy, rat) and other internal organs receiving significantly lower average doses. Therefore, knowing the radiation doses delivered during routine imaging, care can be taken to avoid significant and potentially lethal doses of radiation.

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Jones, Julian R., Georgina E. Milroy, Ruth Cameron, William Bonfield et Larry L. Hench. « Using X-Ray Micro-CT Imaging to Monitor Dissolution of Macroporous Bioactive Glass Scaffolds ». Key Engineering Materials 284-286 (avril 2005) : 493–96. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.493.

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Bioactive glass scaffolds with interconnected macroporous networks have been developed by foaming sol-gel derived bioactive glass of the 70S30C (70 mol% SiO2, 30 mol% CaO) composition. The effect of sintering temperature on the dissolution of the scaffolds in simulated body fluid (SBF) was investigated in 3D using x-ray micro-computer tomography (micro CT) and inductive coupled plasma (ICP) analysis. Micro-CT is non-destructive and allows observation of specific parts of the scaffold at various stages of degradation. However, data analysis is complex at present. Percentage porosity data obtained by micro-CT was compared to physical data and pore size distributions obtained from mercury intrusion porosimetry were compared to the interconnected pore diameters observed from the micro CT images.

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Dimonie, Doina, Ionut-Cristian Radu, George Vlasceanu, Catalin Zaharia, Nicoleta Dragomir, Ovidiu Dima et Sorina Iftimie. « Estimating the 3D Printing Defects by Micro-Computed Tomography ». Proceedings 57, n^o 1 (18 novembre 2020) : 97. http://dx.doi.org/10.3390/proceedings2020057097.

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Litzlbauer, Horst Detlef, Christoph Neuhaeuser, Alexander Moell, Susanne Greschus, Andreas Breithecker, Folker Ernst Franke, Wolfgang Kummer et Wigbert Stephan Rau. « Three-dimensional imaging and morphometric analysis of alveolar tissue from microfocal X-ray-computed tomography ». American Journal of Physiology-Lung Cellular and Molecular Physiology 291, n^o 3 (septembre 2006) : L535—L545. http://dx.doi.org/10.1152/ajplung.00088.2005.

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We evaluated microfocal X-ray-computed tomography (micro-CT) as a method to visualize lung architecture two and three dimensionally and to obtain morphometric data. Inflated porcine lungs were fixed by formaldehyde ventilation. Tissue samples (8-mm diameter, 10-mm height) were stained with osmium tetroxide, and 400 projection images (1,024 × 1,024 pixel) were obtained. Continuous isometric micro-CT scans (voxel size 9 μm) were acquired to reconstruct two- and three-dimensional images. Tissue samples were sectioned (8-μm thickness) for histological analysis. Alveolar surface density and mean linear intercept were assessed by stereology-based morphometry in micro-CT scans and corresponding histological sections. Furthermore, stereology-based morphometry was compared with morphometric semi-automated micro-CT analysis within the same micro-CT scan. Agreement of methods was assessed by regression and Bland-Altman analysis. Comparing histology with micro-CT, alveolar surface densities (35.4 ± 2.4 vs. 33.4 ± 1.9/mm, P < 0.05) showed a correlation ( r = 0.72; P = 0.018) with an agreement of 2 ± 1.6/mm; the mean linear intercept (135.7 ± 14.5 vs. 135.8 ± 15 μm) correlated well ( r = 0.97; P < 0.0001) with an agreement of −0.1 ± 3.4 μm. Semi-automated micro-CT analysis resulted in smaller alveolar surface densities (33.4 ± 1.9 vs. 30.5 ± 1/mm; P < 0.01) with a correlation ( r = 0.70; P = 0.023) and agreement of 2.9 ± 1.4/mm. Non-destructive micro-CT scanning offers the advantage to visualize the spatial tissue architecture of small lung samples two and three dimensionally.

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Zou, Shuo, Serena Best et William Bonfield. « Segementation of X-Ray Microtomography Data of Porous Scaffold ». Key Engineering Materials 330-332 (février 2007) : 911–14. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.911.

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Computerized X-ray micro tomography (micro CT) is a powerful technique for studying the structure and properties of porous scaffold. A variety of sample parameters can be studied using a single micro CT scan [1]. In general a segmented data set is a required for most quantitative analysis. However, segmentation of CT data can be difficult due to the artifacts in micro CT images such as blurred interfaces due to the machine contrast transfer function and the partial volume effect. Therefore the segmentation can be biased and prone to errors. Many methods have been developed to improve segmentation, however the interface problem has not been solved perfectly [2]. Porous scaffolds suffer from these effects because of their high surface to volume ratio and hence large interface. In this paper we discuss the interface problem in detail and demonstrate the effect of voxel size on the histograms of CT images of porous scaffold as well as a thresholding method based on 2 dimensional histogram is also presented. The potential of this method in more complicated scenarios such as 3-phase system is currently being investigated [3].

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Barburski, Marcin, Ilya Straumit et Stepan V. Lomov. « Internal Structure of the Sheared Textile Composite Reinforcement : Analysis Using X-Ray Tomography ». Key Engineering Materials 651-653 (juillet 2015) : 325–30. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.325.

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X-ray micro computed tomography (Micro-CT) is a non-destructive technique that can provide information on the internal structure of materials. The purpose of micro-CT is to assess the presence of defects as well as characterizing internal structures and potential damage present in the produced part. Simple shear is an interesting deformation mechanism for woven fabric draping. The internal structure change of the carbon fibre twill fabric after shear deformation is chosen as a subject of this paper. Parameters of the mesoscopic internal structure of the woven fabric like cross section, shape, area, and middle line coordinates can be obtained from micro-CT images through image processing procedures. Details of the image data processing for sheared fabric cross sections are discussed. This paper illustrates the possibilities of micro-focus computer tomography in materials research, namely for defining geometrical properties of textile. Image processing is also used for the recognition of fibre direction in the yarns. Described methodology can be applied for determining structure of a fabric, and the results can be used for further micromechanical modelling. Identification of the fibres orientation is important for estimation of the mechanical properties of composites and can be achieved with image processing techniques.

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Heyn, René, Abraham Rozendaal, Anton Du Plessis et Carene Mouton. « Characterization of Coloured Gemstones by X-ray Micro Computed Tomography ». Minerals 11, n^o 2 (8 février 2021) : 178. http://dx.doi.org/10.3390/min11020178.

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The monetary value of gemstones is based on five variables: rarity, cut, weight, color and clarity. The latter refers to internal impurities and defects. Fashion may also dictate demand and price. To enhance some of these features and value, gemstones are treated. Disclosure or nondisclosure thereof has been controversial and affected consumer confidence. Most of these treatments are difficult to detect with the naked eye and accurately quantify with traditional optical and analytical methods. X-ray micro computed tomography (micro-CT or μCT) is proposed as a relatively low cost, physically non-destructive and complementary method to detect and quantify clarity enhancement and also to provide a unique 3D fingerprint of each gemstone. A collection of 14 cut colored gemstones was selected. Micro-CT scans allowed fracture detection, their distribution and calculation of filler volume as well as 3D mapping of inclusions, surface and internal imperfections and artificially induced modifications. As a result the method allows the construction of a digital twin. X-ray exposure could however induce unwanted color changes. This effect was minimized or eliminated by optimizing dosage and exposure time.

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Rashidi, Armin, Tina Olfatbakhsh, Bryn Crawford et Abbas S. Milani. « A Review of Current Challenges and Case Study toward Optimizing Micro-Computed X-Ray Tomography of Carbon Fabric Composites ». Materials 13, n^o 16 (14 août 2020) : 3606. http://dx.doi.org/10.3390/ma13163606.

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X-ray computed tomography provides qualitative and quantitative structural and compositional information for a broad range of materials. Yet, its contribution to the field of advanced composites such as carbon fiber reinforced polymers is still limited by factors such as low imaging contrast, due to scarce X-ray attenuation features. This article, through a review of the state of the art, followed by an example case study on Micro-computed tomography (CT) analysis of low X-ray absorptive dry and prepreg carbon woven fabric composites, aims to highlight and address some challenges as well as best practices on performing scans that can capture key features of the material. In the case study, utilizing an Xradia Micro-CT-400, important aspects such as obtaining sufficient contrast, an examination of thin samples, sample size/resolution issues, and image-based modeling are discussed. The outcome of an optimized workflow in Micro-CT of composite fabrics can assist in further research efforts such as the generation of surface or volume meshes for the numerical modeling of underlying deformation mechanisms during their manufacturing processes.

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Mayo, Sheridan C., Andrew M. Tulloh, Adrian Trinchi et Sam Y. S. Yang. « Data-Constrained Microstructure Characterization with Multispectrum X-Ray Micro-CT ». Microscopy and Microanalysis 18, n^o 3 (3 mai 2012) : 524–30. http://dx.doi.org/10.1017/s1431927612000323.

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AbstractConventional X-ray microcomputed tomography (micro-CT) is not usually sufficient to determine microscopic compositional distributions as it is limited to measuring the X-ray attenuation of the sample, which for a given dataset can be similar for materials of different composition. In contrast, the present work enables three-dimensional compositional analysis with a data-constrained microstructure (DCM) modeling methodology, which uses two or more CT datasets acquired with different X-ray spectra and incorporates them as model constraints. For providing input data for DCM, we have also developed a method of micro-CT data collection that enables two datasets with different X-ray spectra to be acquired in parallel. Such data are used together with the DCM methodology to predict the distributions of corrosion inhibitor and filler in a polymer matrix. The DCM-predicted compositional microstructures have a reasonable agreement with energy dispersive X-ray images taken on the sample surface.

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Yang, Sam, Da Chao Gao, Tim Muster, Andrew Tulloh, Scott Furman, Sheridan Mayo et Adrian Trinchi. « Microstructure of a Paint Primer - a Data-Constrained Modeling Analysis ». Materials Science Forum 654-656 (juin 2010) : 1686–89. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1686.

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Metallic aerospace components are commonly painted with a primer to improve their corrosion resistance. The primer contains a polymer matrix with embedded corrosion inhibitor and filler particles. Its performance is determined by the microscopic distributions of the particles. Various techniques have been used to quantify such distributions, including X-ray micro-computed tomography (CT). However, its success is sometimes limited by factors such as different particles having similar X-ray CT absorption properties and their size being smaller than the resolution of micro-CT. In this paper, we have performed two X-ray CT measurements on a paint primer sample consisting of SrCrO4 corrosion inhibitor particles and UV-absorbing TiO2 filler particles. Fe and Ti targets were used as X-ray sources with different spectral distributions. The measured CT data sets were used as constraints for a data-constrained microstructure modeling (DCM) prediction of the sample’s microscopic structures. DCM model predictions were compared with experimental elemental surface maps and showed reasonable degree of agreement, suggesting X-ray micro-CT combined with DCM modeling would be a powerful technique for detailing the dynamics of chromate-inhibited primers and other multiphase systems where the components are sensitive to incident X-ray energy.

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Begot, Laurent, Filip Slavkovic, Myriam Oger, Clement Pichot, Halima Morin, Adnane Boualem, Anne-Laure Favier et Abdelhafid Bendahmane. « Precision Phenotyping of Nectar-Related Traits Using X-ray Micro Computed Tomography ». Cells 11, n^o 21 (31 octobre 2022) : 3452. http://dx.doi.org/10.3390/cells11213452.

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Flower morphologies shape the accessibility to nectar and pollen, two major traits that determine plant–pollinator interactions and reproductive success. Melon is an economically important crop whose reproduction is completely pollinator-dependent and, as such, is a valuable model for studying crop-ecological functions. High-resolution imaging techniques, such as micro-computed tomography (micro-CT), have recently become popular for phenotyping in plant science. Here, we implemented micro-CT to study floral morphology and honey bees in the context of nectar-related traits without a sample preparation to improve the phenotyping precision and quality. We generated high-quality 3D models of melon male and female flowers and compared the geometric measures. Micro-CT allowed for a relatively easy and rapid generation of 3D volumetric data on nectar, nectary, flower, and honey bee body sizes. A comparative analysis of male and female flowers showed a strong positive correlation between the nectar gland volume and the volume of the secreted nectar. We modeled the nectar level inside the flower and reconstructed a 3D model of the accessibility by honey bees. By combining data on flower morphology, the honey bee size and nectar volume, this protocol can be used to assess the flower accessibility to pollinators in a high resolution, and can readily carry out genotypes comparative analysis to identify nectar-pollination-related traits.

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Zhou, La-Zhen, Wen-Jing Xia, Qian-Qian Xu, Zan Chen, Fang-Zuo Li, Zhi-Guo Liu et Tian-Xi Sun. « Micro cone-beam CT scanner based on X-ray polycapillary optics ». Acta Physica Sinica 71, n^o 9 (2022) : 090701. http://dx.doi.org/10.7498/aps.71.20212195.

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In-vivo small animal imaging system is an important part of disease research and new drug development. It is essential for living small animal imaging system to be able to provide the anatomical structure, molecular and functional information. The X-ray micro cone-beam computed tomography (micro-CBCT) can perform longitudinal study with a resolution of tens-to-hundreds of microns in a short imaging time at a relatively low cost. Furthermore, it is easy to combine with other modalities to provide abundant information about small animals. A key challenge to the micro-CBCT scanner is that its spatial and contrast resolution determined primarily by the X-ray focal spot size, the detector element size, and the system geometry. Aiming to improve the spatial resolution, contrast resolution, and imaging uniformity of the micro-CBCT system, we use the X-ray polycapillary optics for adjusting the X-ray source. A micro-CBCT based on X-ray polycapillary optics with a large field of view is constructed for the small animal imaging study. The micro-CBCT system is composed of microfocus X-ray tube with an attached polycapillary focusing X-ray lens, amorphous silicon-based flat panel detector, rotation stage, and controlling PC. The Feldkamp-Daivs-Kress (FDK) algorithm is adopted to reconstruct the image. The system performances are evaluated. The magnification of this micro-CBCT system is 1.97. The results show that the spatial resolution of the system at 10% modulation transfer function (MTF) is 9.1 lp/mm, which is 1.35 times higher than that in the case of no optics. The image uniformity deterioration caused by hardening effect is effectively alleviated by filtrating the low energy X-rays with the X-ray polycapillary optics and the contrast enhancement is more than twice. The anesthetic rats are imaged with this micro-CBCT system in vivo and the practicability of the system in small animal imaging research is verified.

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Zhou, La-Zhen, Wen-Jing Xia, Qian-Qian Xu, Zan Chen, Fang-Zuo Li, Zhi-Guo Liu et Tian-Xi Sun. « Micro cone-beam CT scanner based on X-ray polycapillary optics ». Acta Physica Sinica 71, n^o 9 (2022) : 090701. http://dx.doi.org/10.7498/aps.71.20212195.

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In-vivo small animal imaging system is an important part of disease research and new drug development. It is essential for living small animal imaging system to be able to provide the anatomical structure, molecular and functional information. The X-ray micro cone-beam computed tomography (micro-CBCT) can perform longitudinal study with a resolution of tens-to-hundreds of microns in a short imaging time at a relatively low cost. Furthermore, it is easy to combine with other modalities to provide abundant information about small animals. A key challenge to the micro-CBCT scanner is that its spatial and contrast resolution determined primarily by the X-ray focal spot size, the detector element size, and the system geometry. Aiming to improve the spatial resolution, contrast resolution, and imaging uniformity of the micro-CBCT system, we use the X-ray polycapillary optics for adjusting the X-ray source. A micro-CBCT based on X-ray polycapillary optics with a large field of view is constructed for the small animal imaging study. The micro-CBCT system is composed of microfocus X-ray tube with an attached polycapillary focusing X-ray lens, amorphous silicon-based flat panel detector, rotation stage, and controlling PC. The Feldkamp-Daivs-Kress (FDK) algorithm is adopted to reconstruct the image. The system performances are evaluated. The magnification of this micro-CBCT system is 1.97. The results show that the spatial resolution of the system at 10% modulation transfer function (MTF) is 9.1 lp/mm, which is 1.35 times higher than that in the case of no optics. The image uniformity deterioration caused by hardening effect is effectively alleviated by filtrating the low energy X-rays with the X-ray polycapillary optics and the contrast enhancement is more than twice. The anesthetic rats are imaged with this micro-CBCT system in vivo and the practicability of the system in small animal imaging research is verified.

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Zhou, La-Zhen, Wen-Jing Xia, Qian-Qian Xu, Zan Chen, Fang-Zuo Li, Zhi-Guo Liu et Tian-Xi Sun. « Micro cone-beam CT scanner based on X-ray polycapillary optics ». Acta Physica Sinica 71, n^o 9 (2022) : 090701. http://dx.doi.org/10.7498/aps.71.20212195.

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In-vivo small animal imaging system is an important part of disease research and new drug development. It is essential for living small animal imaging system to be able to provide the anatomical structure, molecular and functional information. The X-ray micro cone-beam computed tomography (micro-CBCT) can perform longitudinal study with a resolution of tens-to-hundreds of microns in a short imaging time at a relatively low cost. Furthermore, it is easy to combine with other modalities to provide abundant information about small animals. A key challenge to the micro-CBCT scanner is that its spatial and contrast resolution determined primarily by the X-ray focal spot size, the detector element size, and the system geometry. Aiming to improve the spatial resolution, contrast resolution, and imaging uniformity of the micro-CBCT system, we use the X-ray polycapillary optics for adjusting the X-ray source. A micro-CBCT based on X-ray polycapillary optics with a large field of view is constructed for the small animal imaging study. The micro-CBCT system is composed of microfocus X-ray tube with an attached polycapillary focusing X-ray lens, amorphous silicon-based flat panel detector, rotation stage, and controlling PC. The Feldkamp-Daivs-Kress (FDK) algorithm is adopted to reconstruct the image. The system performances are evaluated. The magnification of this micro-CBCT system is 1.97. The results show that the spatial resolution of the system at 10% modulation transfer function (MTF) is 9.1 lp/mm, which is 1.35 times higher than that in the case of no optics. The image uniformity deterioration caused by hardening effect is effectively alleviated by filtrating the low energy X-rays with the X-ray polycapillary optics and the contrast enhancement is more than twice. The anesthetic rats are imaged with this micro-CBCT system in vivo and the practicability of the system in small animal imaging research is verified.

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Szewczykowski, Piotr. « Applying micro-computed tomography for porosity analysis of polypropylene modified with microspheres ». MATEC Web of Conferences 332 (2021) : 01017. http://dx.doi.org/10.1051/matecconf/202133201017.

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Porosity of polypropylene samples was investigated by applying X-ray micro-computed tomography (micro-CT), which is getting more and more popular as a non-destructive method. Microspheres were applied as a blowing agent at three concentrations: 3%, 6% and 9% by weight. Tensile testing specimens were obtained by injection molding technology and its central, measuring part were examined by micro – CT. Results were compared to porosity calculated based on difference in porous and solid material density. Pore size distribution curves were discussed as well.

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Bharkhada, Deepak, Hengyong Yu, Hong Liu, Robert Plemmons et Ge Wang. « Line-Source Based X-Ray Tomography ». International Journal of Biomedical Imaging 2009 (2009) : 1–8. http://dx.doi.org/10.1155/2009/534516.

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Current computed tomography (CT) scanners, including micro-CT scanners, utilize a point x-ray source. As we target higher and higher spatial resolutions, the reduced x-ray focal spot size limits the temporal and contrast resolutions achievable. To overcome this limitation, in this paper we propose to use a line-shaped x-ray source so that many more photons can be generated, given a data acquisition interval. In reference to the simultaneous algebraic reconstruction technique (SART) algorithm for image reconstruction from projection data generated by an x-ray point source, here we develop a generalized SART algorithm for image reconstruction from projection data generated by an x-ray line source. Our numerical simulation results demonstrate the feasibility of our novel line-source based x-ray CT approach and the proposed generalized SART algorithm.

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Meftah, Redouane, Jeroen Van Stappen, Sylvain Berger, Gary Jacqus, Jean-Yves Laluet, Paul-Henri Guering, Luc Van Hoorebeke et Veerle Cnudde. « X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam ». Materials 12, n^o 12 (17 juin 2019) : 1944. http://dx.doi.org/10.3390/ma12121944.

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Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore network is often not investigated and is, thus, poorly known. Since this network controls different physical properties, such as the sound absorption, it is crucial to understand its overall structure. In this manuscript, we show how to reveal the pore network of EPS foams through the combination of high resolution X-ray tomography (micro-CT) and saturation techniques. The foams were saturated with CsCl-brine, which acts as a contrasting agent in X-ray micro-CT imaging. This allowed us to separate the beads, making up the foam, from the pore network. Based on the 3D micro-CT results, we were able to assess a representative elementary volume for the polystyrene, which allows for calculating the acoustical parameters from the Johnson–Champoux–Allard (JCA) model, the pore and bead size distribution. The 3D data was also used as input to simulate sound absorption curves. The parametric study showed that an increase in the bead size influenced the sound absorption of the material. We showed that, by doubling the diameter of beads, the absorption coefficient was doubled in certain ranges of frequency.

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Yoneyama, Akio, Satoshi Takeya, Thet Thet Lwin, Daiko Takamatsu, Rika Baba, Kumiko Konishi, Ryusei Fujita et al. « Advanced X-ray imaging at beamline 07 of the SAGA Light Source ». Journal of Synchrotron Radiation 28, n^o 6 (21 octobre 2021) : 1966–77. http://dx.doi.org/10.1107/s1600577521009553.

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The SAGA Light Source provides X-ray imaging resources based on high-intensity synchrotron radiation (SR) emitted from the superconducting wiggler at beamline 07 (BL07). By combining quasi-monochromatic SR obtained by the newly installed water-cooled metal filter and monochromatic SR selected by a Ge double-crystal monochromator (DCM) with high-resolution lens-coupled X-ray imagers, fast and low-dose micro-computed tomography (CT), fast phase-contrast CT using grating-based X-ray interferometry, and 2D micro-X-ray absorption fine structure analysis can be performed. In addition, by combining monochromatic SR obtained by a Si DCM with large-area fiber-coupled X-ray imagers, high-sensitivity phase-contrast CT using crystal-based X-ray interferometry can be performed. Low-temperature CT can be performed using the newly installed cryogenic system, and time-resolved analysis of the crystallinity of semiconductor devices in operation can be performed using a time-resolved topography system. The details of each instrument and imaging method, together with exemplary measurements, are presented.

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El-Gizawy, Ahmed Sherif, Xuewei Ma, Ferris Pfeiffer, James D. Schiffbauer et Tara Selly. « Characterization of Microarchitectures, Stiffness and Strength of Human Trabecular Bone Using Micro-Computed Tomography (Micro-CT) Scans ». BioMed 3, n^o 1 (19 janvier 2023) : 89–100. http://dx.doi.org/10.3390/biomed3010007.

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The present work presents evaluation and experimental verification of the use of X-ray computed tomographic microscopy (micro-CT) for accurate characterization of geometry, microarchitecture, and stiffness properties of bones. These properties are crucial for designing and building optimized implants for joint and dental reconstruction applications. High-resolution micro-CT scans would provide more detailed and accurate information about the microarchitecture and density distribution across patient bones. Nevertheless, micro-CT applications on live patients require invasive procedures involving small bone biopsy specimens. Alternatively, micro-CT could be used on samples collected from selected cadavers of different age, gender, and race groups to establish a database that could be used for providing useful microarchitecture information. The micro-CT scans of investigated bone samples reveal that the trabecular bone is anisotropic and heterogeneous. The results also showed considerable degree of parametric variability and uncertainty on microarchitecture and stiffness properties of patient’s trabecular bone.

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Chen, Meiling, Zhuchao Xu, Hui Li, Jialin Zhang, Dengcheng Feng, Zhichao Lou, Changhua Fang, Yanjun Li et Wenkai Zhu. « Characterization of bamboo extrinsic toughening mechanism in bending by X-ray micro-computed tomography(micro-CT) ». Industrial Crops and Products 208 (février 2024) : 117882. http://dx.doi.org/10.1016/j.indcrop.2023.117882.

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Wang, Yi, Lech Muszynski et John Simonsen. « Gold as an X-ray CT scanning contrast agent : Effect on the mechanical properties of wood plastic composites ». Holzforschung 61, n^o 6 (1 novembre 2007) : 723–30. http://dx.doi.org/10.1515/hf.2007.117.

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Abstract Wood plastic composites (WPCs) are typically composed of wood particles, thermoplastic polymers and small amounts of additives. Further improvement of WPC technology requires a better understanding of their mechanical performance and durability on the micro level. X-ray computed tomography (CT) and advanced imaging techniques can provide visualization and support characterization of the internal structure, deformation and damage accumulation in WPCs under loading and various environmental exposures. However, both wood and thermoplastics are weakly attenuating materials for X-ray and good contrast between these two components is difficult to obtain. In the present study, chemically inert gold nano-particles and micro-particles were investigated as contrast agents to improve X-ray CT scanning contrast between wood and thermoplastics. The effect of adding 1% (by wt.) gold nano- and micro-particles on the tensile properties of wood/high-density polyethylene composites was addressed. Samples with and without surfactant were tested in tension and scanned on a custom desktop X-ray CT system. It was found that the addition of gold particles did not impair the WPC tensile properties. However, some of the tensile properties were significantly affected if the surfactant was included. Gold micro-particles were shown to disperse well without surfactant and significantly improve the X-ray CT scanning contrast between wood and polymer, while gold nano-particles (without surfactant) did not disperse well and do not contribute to contrast improvement.

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Dall’Ava, Lorenzo, Harry Hothi, Johann Henckel, Anna Di Laura, Sean Bergiers, Paul Shearing et Alister Hart. « Dimensional analysis of 3D-printed acetabular cups for hip arthroplasty using X-ray microcomputed tomography ». Rapid Prototyping Journal 26, n^o 3 (2 janvier 2020) : 567–76. http://dx.doi.org/10.1108/rpj-06-2019-0175.

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Purpose Three-dimensional (3D) printing is increasingly used to produce orthopaedic components for hip arthroplasty, such as acetabular cups, which show complex lattice porous structures and shapes. However, limitations on the quality of the final implants are present; thus, investigations are needed to ensure adequate quality and patients safety. X-ray microcomputed tomography (micro-CT) has been recognised to be the most suitable method to evaluate the complexity of 3D-printed parts. The purpose of this study was to assess the reliability of a micro-CT analysis method comparing it with reference systems, such as coordinate measuring machine and electron microscopy. Design/methodology/approach 3D-printed acetabular components for hip arthroplasty (n = 2) were investigated. Dimensions related to the dense and porous regions of the samples were measured. The micro-CT scanning parameters (voltage – kV, current – µA) were optimised selecting six combinations of beam voltage and current. Findings Micro-CT showed good correlation and agreement with both coordinate measuring machine and scanning electron microscopy when optimal scanning parameters were selected (130 kV – 100 µA to 180 kV – 80 µA). Mean discrepancies of 50 µm (± 300) and 20 µm (± 60) were found between the techniques for dense and porous dimensions. Investigation method such as micro-CT imaging may help to better understand the impact of 3D printing manufacturing technology on the properties of orthopaedic implants. Originality/value The optimisation of the scanning parameters and the validation of this method with reference techniques may guide further analysis of similar orthopaedic components.

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Eberspächer-Schweda, Matthias C., Kira Schmitt, Stephan Handschuh, Andrea Fuchs-Baumgartinger et Alexander M. Reiter. « Diagnostic Yield of Micro-Computed Tomography (micro-CT) Versus Histopathology of a Canine Oral Fibrosarcoma ». Journal of Veterinary Dentistry 37, n^o 1 (mars 2020) : 14–21. http://dx.doi.org/10.1177/0898756420926519.

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Micro-computed tomography (micro-CT) imaging currently gains increased interest in human as well as veterinary medicine. The ability to image 3-dimensional (3D) biopsy specimens nondestructively down to 1 µm spatial resolution makes it a promising tool for microscopic tissue evaluation in addition to histopathology. Visualizing tumor margins and calculating tumor load on 3D reconstructions may also enhance oncological therapies. The objective of this study was to describe the workflow from tumor resection to histopathological diagnosis, using both routine hematoxylin-eosin (HE)-stained sections and micro-CT tomograms on a stage II oral fibrosarcoma in a 7-year-old Hovawart dog. The maxillectomy specimen was fixed with formalin and stained with an X-ray dense soft tissue contrast agent. Micro-CT imaging was done using an ex vivo specimen micro-CT device. Tumor margins could not be exactly determined on micro-CT tomograms due to limited image resolution and contrast. Histopathology was performed after washing out the contrast agent. It showed neoplastic cells infiltrating the surrounding tissue further than assumed from micro-CT images. A total tumor volume of 10.3 cm3 could be calculated based on correlating micro-CT tomograms with HE-stained sections. This correlative approach may be of particular interest for oncological therapy. More than that, micro-CT imaging technology supported histopathology by means of 3D orientation and selection of slices to be cut on determining tumor margins. In this clinical case report, micro-CT imaging did not provide unambiguous clinical evidence for oncological decision-making, but it showed potential to support histopathology and calculate tumor volume for further clinical use.

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Parapar, Julio, Carlos Caramelo, María Candás, Xela Cunha-Veira et Juan Moreira. « An integrative approach to the anatomy of Syllis gracilis Grube, 1840 (Annelida) using micro-computed X-ray tomography ». PeerJ 7 (8 juillet 2019) : e7251. http://dx.doi.org/10.7717/peerj.7251.

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Background The overall anatomy of the genus Syllis (Annelida: Syllidae) has been largely studied; however, an integrative approach considering different anatomical techniques has never been considered. Here, we use micro-computed X-ray tomography (micro-CT) to examine the internal anatomy of Syllis gracilis Grube, 1840, along with other widely available techniques. Methods We studied the anatomy of the marine annelid S. gracilis through an integrative approach, including micro-CT along with stereo and light compound microscopy (STM, LCM), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and histological sectioning (HIS). In this manner, we evaluated the applicability of micro-CT for the examination of annelid anatomy by testing whether the images obtained make it possible to visualize the main body structures, in comparison with other current techniques, of the various elements of its internal anatomy. Results Overall external and internal body elements are clearly shown by the integrative use of all techniques, thus overcoming the limitations of each when studied separately.Any given method shows disparate results, depending on the body part considered. For instance, micro-CT provided good images of the external anatomy, including relevant characters such as the shape, length and number of articles of dorsal parapodial cirri. However, it is especially useful for the examination of internal anatomy, thus allowing for 3D visualization of the natural spatial arrangement of the different organs. The features best visualized are those of higher tissue density (i.e., body musculature, anterior parts of the digestive tract), particularly in 3D images of unstained specimens, whereas less electrodense tissues (i.e., the peritoneal lining of septa and nervous system) are less clearly visualized. The use of iodine stain with micro-CT has shown advantages against non-staining for the adequate observation of delicate elements of low density, such as the segmental organs, the connective between the ganglia, the ventral nerve cord and segmental nerves. Discussion Main external anatomical elements of S. gracilis are well shown with micro-CT, but images show lesser optical resolution and contrast when compared to micrographs provided by SEM and CLSM, especially for fine structural features of chaetae. Comparison of micro-CT and HIS images revealed the utility and reliability of the former to show the presence, shape and spatial disposition of most internal body organs; the resolution of micro-CT images at a cellular level is, however, much lower than that of HIS, which makes both techniques complementary.

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Orellana, F., A. Grassi, P. Wahl, K. Nuss, A. Neels, S. Zaffagnini et A. Parrilli. « 3D QUANTITATIVE CHARACTERIZATION OF THE HUMAN MENISCAL VASCULAR NETWORK USING X-RAY MICRO-COMPUTED TOMOGRAPHY ». Orthopaedic Proceedings 106-B, SUPP_2 (2 janvier 2024) : 6. http://dx.doi.org/10.1302/1358-992x.2024.2.006.

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A comprehensive understanding of the self-repair abilities of menisci and their overall function in the knee joint requires three-dimensional information. However, previous investigations of the meniscal blood supply have been limited to two-dimensional imaging methods, which fail to accurately capture tissue complexity. In this study, micro-CT was used to analyse the 3D microvascular structure of the meniscus, providing a detailed visualization and precise quantification of the vascular network.A contrast agent (μAngiofil®) was injected directly into the femoral artery of cadaver legs to provide the proper contrast enhancement. First, the entire knee joint was analysed with micro-CT, then to increase the applicable resolution the lateral and medial menisci were excised and investigated with a maximum resolution of up to 4 μm. The resulting micro-CT datasets were analysed both qualitatively and quantitatively. Key parameters of the vascular network, such as vascular volume fraction, vessel radius, vessel length density, and tortuosity, were separately determined for the lateral and medial meniscus, and their four circumferential zones defined by Cooper.In accordance with previous literature, the quantitative micro-CT data confirm a decrease in vascular volume fraction along the meniscal zones. The highest concentration of blood vessels was measured in the meniscocapsular region 0, which is characterized by vascular segments with a significantly larger average radius. Furthermore, the highest vessel length density observed in zone 0 suggests a more rapid delivery of oxygen and nutrients compared to other regions. Vascular tortuosity was detected in all circumferential regions, indicating the occurrence of vascular remodelling in all tissue areas.In conclusion, micro-CT is a non-invasive imaging technique that allows for the visualization of the internal structure of an object in three dimensions. These advanced 3D vascular analyses have the potential to establish new surgical approaches that rely on the healing potential of specific areas of the meniscus.Acknowledgements: The authors acknowledge R. Hlushchuk, S. Halm, and O. Khoma from the University of Bern for their help with contrast agent perfusions.

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Zabler, Simon, Katja Schladitz, Kilian Dremel, Jonas Graetz et Dascha Dobrovolskij. « Region-of-Interest X-Ray Tomography for the Non-Destructive Characterization of Local Fiber Orientation in Large Fiber Composite Parts ». Key Engineering Materials 809 (juin 2019) : 587–93. http://dx.doi.org/10.4028/www.scientific.net/kem.809.587.

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To detect and characterize materials defects in fiber composites as well as for evaluatingthe three-dimensional local fiber orientation in the latter, X-ray micro-CT is the preferred methodof choice. When micro computed tomography is applied to inspect large components, the method isreferred to as region-of-interest computed tomography. Parts can be as large as 10 cm wide and 1 mlong, while the measurement volume of micro computed tomography is a cylinder of only 4 − 5 mmdiameter (typical wall thickness of fiber composite parts). In this report, the potentials and limits ofregion-of-interest computed tomography are discussed with regard to spatial resolution and precisionwhen evaluating defects and local fiber orientation in squeeze cast components. The micro computedtomography scanner metRIC at Fraunhofer‘s Development Center X-ray Technology EZRT deliversregion-of-interest computed tomography up to a spatial resolution of 2 μm/voxel, which is sufficientfor determining the orientation of natural or synthetic fibers, wood, carbon and glass. The mean localfiber orientation is estimated on an isotropic structuring element of approximately 0.1 mm length bymeans of volume image analysis (MAVI software package by Fraunhofer ITWM). Knowing the exactlocal fiber orientation is critical for estimating anisotropic thermal conductivity and materials strength.

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Gomes Junior, Francisco Guilhien, Silvio Moure Cícero, Carlos Manoel Pedro Vaz et Paulo Renato Orlandi Lasso. « X-ray microtomography in comparison to radiographic analysis of mechanically damaged maize seeds and its effect on seed germination ». Acta Scientiarum. Agronomy 41, n^o 1 (13 mars 2019) : 42608. http://dx.doi.org/10.4025/actasciagron.v41i1.42608.

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Among the most relevant aspects of seed production, mechanical damage may affect seed germination and reduce health and vigor. This study introduces a noninvasive high-resolution imaging procedure for evaluating the mechanical damage to maize seeds and the effects on seed germination. Seeds with different levels of mechanical damage were evaluated using a benchtop micro-computed tomography system (micro-CT) and digital X-ray equipment. The two-dimensional transaxial, coronal and sagittal micro-CT sections were used to inspect the seed anatomy and the mechanical injuries in the internal seed tissue. Germination tests were performed using paper towel rolls (25°C for 7 days) in which the seedling length was evaluated on a daily basis, and the seedling dry biomass was measured at the seventh germination day. The micro-CT cross-sectional images allowed an efficient spatial characterization of the mechanical damage inside the seeds. On average, mechanically damaged seeds produced seedlings with a length 24% shorter and a dry biomass 65% less than that of the undamaged seeds. We concluded that the micro-CT technique provides an efficient means to inspect mechanically damaged maize seeds and allows for a reliable association with germination response.

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Bultreys, T., S. Van Offenwert, W. Goethals, M. N. Boone, J. Aelterman et V. Cnudde. « X-ray tomographic micro-particle velocimetry in porous media ». Physics of Fluids 34, n^o 4 (avril 2022) : 042008. http://dx.doi.org/10.1063/5.0088000.

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Fluid flow through intricate confining geometries often exhibits complex behaviors, certainly in porous materials, e.g., in groundwater flows or the operation of filtration devices and porous catalysts. However, it has remained extremely challenging to measure 3D flow fields in such micrometer-scale geometries. Here, we introduce a new 3D velocimetry approach for optically opaque porous materials, based on time-resolved x-ray micro-computed tomography (CT). We imaged the movement of x-ray tracing micro-particles in creeping flows through the pores of a sandpack and a porous filter, using laboratory-based CT at frame rates of tens of seconds and voxel sizes of 12 μm. For both experiments, fully three-dimensional velocity fields were determined based on thousands of individual particle trajectories, showing a good match to computational fluid dynamics simulations. Error analysis was performed by investigating a realistic simulation of the experiments. The method has the potential to measure complex, unsteady 3D flows in porous media and other intricate microscopic geometries. This could cause a breakthrough in the study of fluid dynamics in a range of scientific and industrial application fields.

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Hu, Yibing, Ryan T. Armstrong, Igor Shikhov, Tzong T. Hung, Brendan Lee et Peyman Mostaghimi. « Unsteady-State Coreflooding Monitored by Positron Emission Tomography and X-ray Computed Tomography ». SPE Journal 25, n^o 01 (15 juillet 2019) : 242–52. http://dx.doi.org/10.2118/195701-pa.

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Summary The forced-imbibition displacement process—a complex function of multiple physical properties of rock, fluids, and flow conditions—is of vital importance. For this paper we used imaging techniques to detect the process in three dimensions with high temporal resolution. Positron emission tomography (PET) is a powerful tool for imaging fluid transport in porous media because it has high temporal resolution and is not affected by complex lithology and pore structures. In this study, we conducted a detailed experimental and numerical analysis to prove how PET can be used with microcomputed tomography (micro-CT) to complement the imaging of water displacement in the porous space of sandstone. To characterize the rock properties, a dry sample was imaged with a high-resolution micro-CT scanner. The image was reconstructed and segmented into two phases (solid and void) to calculate the porosity/permeability relationship on cubic subsets. The Navier-Stokes equation was solved for permeability calculation. The porosity/permeability relationship was used as the input to simulate the forced imbibition process on an upscaled micro-CT image using the Matlab Reservoir Simulation Toolbox (MRST) (Lie et al. 2011; Krogstad et al. 2015; Lie 2016; Bao et al. 2017). The result was the evolution of invading-fluid saturation in every upscaled voxel. In the following step, water tracer labeled with fluorodeoxyglucose (18F-FDG) was injected into the dry sample and a series of PET images was acquired to detect fluid pathways. Fluid-front topology and a propagation procedure were captured. We integrated saturation data across the core cross section for both data sets (direct PET-based and MRST-simulated on upscaled tomograms) to reduce the complexity of the analysis. Comparison of the resulting 1D saturation profiles demonstrated the capability of PET imaging to monitor and understand dynamic flow processes in reservoir rocks.

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Tsai, Kevin Wen-Kai, Ho-Shiang Chueh et Jyh-Cheng Chen. « DEVELOPMENT OF PHANTOM FOR PERFORMANCE EVALUATION OF MICRO-CT ». Biomedical Engineering : Applications, Basis and Communications 20, n^o 03 (juin 2008) : 177–84. http://dx.doi.org/10.4015/s1016237208000763.

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Micro-X-ray computed tomography (micro-CT) has several characters such as non-invasive, high spatial resolution, high signal-to-noise ratio, providing three-dimensional volume information. Because micro-CT was utilized in many kinds of research field such as preclinical biomedical study, designing a performance phantom and developing analytic methods to objectively evaluate the performance of micro-CT are very important. In this study, the performance phantom and the analytic methods were developed for performance evaluation of micro-CT. The performance parameters extracted from different CT images including noise, linearity, spatial resolution, and hardware alignment were defined in the American Association of Physicists in Medicine (AAPM) Report No. 1 and the American Society for Testing and Materials (ASTM) E1695-95. Standard deviation, Pearson's correlation coefficient, edge response function, and visualization method were utilized to evaluate noise, linearity, spatial resolution, and hardware alignment, respectively. A digital uniform disk image was utilized to evaluate the accuracy of spatial resolution evaluation method. The physical phantom study was performed to evaluate a home-made micro-CT and a commercial micro-CT (Skyscan 1076). According to these results, the performance phantom and the analytic methods developed in this study have demonstrated their capability to evaluate performance of any micro-CT.

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Cho, Hongdong, Hongsu Bae, Chanho Park, Hyeong Min Park, Seo-Eun Oh, Sang-Yeop Chung et Beomjoo Yang. « Mechanical and Microscopic Characteristics of Polyurethane-Based Pervious Pavement Composites ». Materials 14, n^o 16 (4 août 2021) : 4365. http://dx.doi.org/10.3390/ma14164365.

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Conventional pervious pavement materials (PPM) that consist of cement and aggregate materials are known for poor durability due to their brittle behavior. Thus, to enhance the durability, we fabricated polymeric PPMs from durable and abundant polyurethane (PU) and undertook mechanical and microscopic characterizations. PU-based PPM samples with varying aggregate sizes were produced and examined to test their compressive strength and water permeability. Furthermore, X-ray micro-computed tomography (micro-CT) was implemented to analyze the samples’ pore and tortuosity characteristics. Through the micro-CT analysis, the morphological characteristics of PPM’s internal structures were identified and quantitively analyzed the correlations between the pore size distribution, connectivity, and tortuosity within the samples. Finally, the microstructures derived from micro-CT were generated as a finite element model and also numerically determined the stress distribution generated inside.

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Waku, Yoshiharu, et Hideyuki Yasuda. « High Temperature Characteristics of Unidirectionally Solidified Eutectic Ceramic Composites and some Potential Applications ». Materials Science Forum 638-642 (janvier 2010) : 997–1002. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.997.

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We have recently developed ceramic eutectics, which are named Melt Growth Composites (MGCs). The binary MGCs (Al2O3/YAG and Al2O3/GAP binary systems) have a novel microstructure, in which continuous networks of single-crystal Al2O3 phases and single-crystal oxide compounds (YAG or GAP) interpenetrate without grain boundaries. To characterize the entangled structure of the typical MGCs, the X-ray computerized tomography (micro X-ray CT) was performed at a synchrotron radiation facility Spring8. The micro X-ray CT showed that the Al2O3 and the GAP are entangled with each other. Therefore, the MGCs have excellent high-temperature strength characteristics, creep resistance, superior oxidation resistance and thermal stability in the air atmosphere at very high temperatures. To achieve higher thermal efficiency for gas turbine systems, MGC bowed stacking nozzle vanes have been fabricated on an experimental basis.

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Arana Peña, L. M., S. Donato, D. Bonazza, L. Brombal, F. Martellani, F. Arfelli, G. Tromba et R. Longo. « Multiscale X-ray phase-contrast tomography : From breast CT to micro-CT for virtual histology ». Physica Medica 112 (août 2023) : 102640. http://dx.doi.org/10.1016/j.ejmp.2023.102640.

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Wingham, James Robert, Robert Turner, Joanna Shepherd et Candice Majewski. « Micro-CT for analysis of laser sintered micro-composites ». Rapid Prototyping Journal 26, n^o 4 (2 janvier 2020) : 649–57. http://dx.doi.org/10.1108/rpj-08-2019-0211.

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Purpose X-Ray-computed micro-tomography (micro-CT) is relatively well established in additive manufacturing as a method to determine the porosity and geometry of printed parts and, in some cases, the presence of inclusions or contamination. This paper aims to demonstrate that micro-CT can also be used to quantitatively analyse the homogeneity of micro-composite parts, in this case created using laser sintering (LS). Design/methodology/approach LS specimens were manufactured in polyamide 12 with and without incorporation of a silver phosphate glass additive in different sizes. The specimens were scanned using micro-CT to characterise both their porosity and the homogeneity of dispersion of the additive throughout the volume. Findings This work showed that it was possible to use micro-CT to determine information related to both porosity and additive dispersion from the same scan. Analysis of the pores revealed the overall porosity of the printed parts, with linear elastic fracture mechanics used to identify any pores likely to lead to premature failure of the parts. Analysis of the additive was found to be possible above a certain size of particle, with the size distribution used to identify any agglomeration of the silver phosphate glass. The particle positions were also used to determine the complete spatial randomness of the additive as a quantitative measure of the dispersion. Practical implications This shows that micro-CT is an effective method of identifying both porosity and additive agglomeration within printed parts, meaning it can be used for quality control of micro-composites and to validate the homogeneity of the polymer/additive mixture prior to printing. Originality/value This is believed to be the first instance of micro-CT being used to identify and analyse the distribution of an additive within a laser sintered part.

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Martinson, Mercedes, Nazanin Samadi, George Belev, Bassey Bassey, Rob Lewis, Gurpreet Aulakh et Dean Chapman. « Development of a bent Laue beam-expanding double-crystal monochromator for biomedical X-ray imaging ». Journal of Synchrotron Radiation 21, n^o 3 (13 mars 2014) : 479–83. http://dx.doi.org/10.1107/s1600577514003014.

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The Biomedical Imaging and Therapy (BMIT) beamline at the Canadian Light Source has produced some excellent biological imaging data. However, the disadvantage of a small vertical beam limits its usability in some applications. Micro-computed tomography (micro-CT) imaging requires multiple scans to produce a full projection, and certain dynamic imaging experiments are not possible. A larger vertical beam is desirable. It was cost-prohibitive to build a longer beamline that would have produced a large vertical beam. Instead, it was proposed to develop a beam expander that would create a beam appearing to originate at a source much farther away. This was accomplished using a bent Laue double-crystal monochromator in a non-dispersive divergent geometry. The design and implementation of this beam expander is presented along with results from the micro-CT and dynamic imaging tests conducted with this beam. Flux (photons per unit area per unit time) has been measured and found to be comparable with the existing flat Bragg double-crystal monochromator in use at BMIT. This increase in overall photon count is due to the enhanced bandwidth of the bent Laue configuration. Whilst the expanded beam quality is suitable for dynamic imaging and micro-CT, further work is required to improve its phase and coherence properties.

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Langheinrich, A. C., C. Stolle, M. Kampschulte, D. Lommel, W. S. Rau et B. Bassaly. « Diagnostic value of ex-vivo three-dimensional micro-computed tomography imaging of primary nonhematopoietic human bone tumors : osteosarcoma versus chondrosarcoma ». Acta Radiologica 49, n^o 8 (octobre 2008) : 940–48. http://dx.doi.org/10.1080/02841850802247673.

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Background: Osteosarcoma and chondrosarcoma are the most common nonhematopoietic primary malignancies of bone. However, unusual radiographic appearances can lead to delay in diagnosis and confusion with benign diseases. Purpose: To evaluate the feasibility of micro-computed tomography (CT) for the analysis of primary, nonhematopoietic human bone tumors ex vivo. Material and Methods: Samples from 12 human bone specimens (osteosarcoma, n=6; chondrosarcoma, n=6) obtained for diagnostic purposes were scanned using industrial X-ray film without amplifier foil and scanned with micro-CT (7- and 12-µm-cubic voxels). Trabecular bone CT “density” and tumor matrix CT “density” were determined, and results were compared with those obtained from a detailed conventional histopathologic analysis of corresponding cross-sections. The significance of differences in grayscale measurements was tested with analysis of variance. Results: Micro-CT provided quantitative information on bone morphology equivalent to histopathological analysis. We established grayscale measurements by which tumor matrices of chondrosarcoma and osteosarcoma could be radiographically categorized following histological classifications ( P<0.001). Conclusion: Micro-CT is feasible for the analysis and differentiation of human osteosarcoma and chondrosarcoma.

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Liu, Huabo, Fanjing Meng et Shaozhen Hua. « 4D Mapping of the Fracture Evolution in a Printed Gypsum-Like Core by Using X-Ray CT Scanning ». Advances in Civil Engineering 2021 (17 avril 2021) : 1–12. http://dx.doi.org/10.1155/2021/8820828.

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The paper presents the use of micro-X-ray computed tomography (CT) system and associated automatic loading device in visualizing and analyzing the propagation of penny-shaped flaw in gypsum-like 3D printing specimen. During the loading process, a micro-X-ray computed tomography (CT) system was used to scan the specimen with a resolution of 30 × 30 μm2. The volumetric images of specimen were reconstructed based on two-dimensional images. Thus, the propagation of penny-shaped flaw in gypsum-like 3D printing specimen in spatial was observed. The device can record the evolution of the internal penny-shaped flaw by X-ray CT scanning and the evolution of the surface crack by digital radiography at the same time. Fractal analysis was employed to quantify the cracking process. Two- and three-dimensional box-counting methods were applied to analyze slice images and volumetric images, respectively. Comparison between fractal dimensions calculated from two- and three-dimensional box-counting method was carried out. The results show that the fractal dimension increases with the propagation of cracks. Moreover, the common approach to obtain the 3D fractal dimension of a self-similar fractal object by adding one to its corresponding 2D fractal dimension is found to be inappropriate.

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Yu, Hengyong, Guohua Cao, Laurel Burk, Yueh Lee, Jianping Lu, Pete Santago, Otto Zhou et Ge Wang. « Compressive sampling based interior reconstruction for dynamic carbon nanotube micro-CT ». Journal of X-Ray Science and Technology : Clinical Applications of Diagnosis and Therapeutics 17, n^o 4 (janvier 2009) : 295–303. http://dx.doi.org/10.3233/xst-2009-023000230.

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In the computed tomography (CT) field, one recent invention is the so-called carbon nanotube (CNT) based field emission x-ray technology. On the other hand, compressive sampling (CS) based interior tomography is a new innovation. Combining the strengths of these two novel subjects, we apply the interior tomography technique to local mouse cardiac imaging using respiration and cardiac gating with a CNT based micro-CT scanner. The major features of our method are: (1) it does not need exact prior knowledge inside an ROI; and (2) two orthogonal scout projections are employed to regularize the reconstruction. Both numerical simulations and in vivo mouse studies are performed to demonstrate the feasibility of our methodology.

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Popova, Elena, Sergey Tkachev, Igor Reshetov, Peter Timashev et Ilya Ulasov. « Imaging Hallmarks of Sarcoma Progression Via X-ray Computed Tomography : Beholding the Flower of Evil ». Cancers 14, n^o 20 (19 octobre 2022) : 5112. http://dx.doi.org/10.3390/cancers14205112.

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Sarcomas are a leading cause of cancer death in individuals younger than 20 years of age and represent the largest group of rare solid tumors. To date, more than 100 morphological subtypes of sarcomas have been described, among which epidemiology, clinical features, management, and prognosis differ significantly. Delays and errors in the diagnosis of sarcomas limit the number of effective therapeutic modalities and catastrophically worsen the prognosis. Therefore, the development of an algorithm for the early accurate diagnosis of sarcomas seems to be as important as the development of novel therapeutic advances. This literature review aims to summarize the results of recent investigations regarding the imaging of sarcoma progression based on the use of X-ray computed tomography (CT) in preclinical studies and in current clinical practice through the lens of cancer hallmarks. We attempted to summarize the main CT imaging features of soft-tissue and bone sarcomas. We noted the development of new molecular markers with high specificity to antibodies and chemokines, which are expressed in particular sarcoma subtypes to reach tumor type-specific imaging. We demonstrate the possibility of the use of X-ray computed microtomography (micro-CT) for non-destructive 3D visualization of solid tumors by increasing the visibility of soft tissues with X-ray scattering agents. Based on the results of recent studies, we hypothesize that micro-CT enables the visualization of neovascularization and stroma formation in sarcomas at high-resolution in vivo and ex vivo, including the novel techniques of whole-block and whole-tissue imaging. Finding correlations between CT, PET/CT, and micro-CT imaging features, the results of the histopathological specimen examination and clinical outcomes may significantly increase the accuracy of soft-tissue and bone tumor diagnostics, which leads to the initiation of appropriate histotype-specific management in a timely manner and, consequently, to improved outcomes.

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Tian, Linan, Long Liu, Bo Ma, Fahmi Zaïri, Ning Ding, Weimin Guo, Na Xu, Huixia Xu et Ming Zhang. « Evaluation of maximum non-metallic inclusion sizes in steel by statistics of extreme values method based on Micro-CT imaging ». Metallurgical Research & ; Technology 119, n^o 2 (2022) : 202. http://dx.doi.org/10.1051/metal/2022016.

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Non-metallic inclusions have become a matter of concern for several properties of steel. The effective evaluation of inclusions in steel would provide critical information to evaluate the steel quality. In this study, an evaluation method based on X-ray Micro-Computed Tomography (Micro-CT) experiments was proposed. First, Micro-CT experiments were carried out to characterize the inclusions. Then, the characterizations of the inclusions were collected based on the 2D slices and their 3D features. The extreme values were evaluated by statistics of extreme values method with these data. The evaluation results were compared with those obtained by international standard ASTM E2283-08. The results demonstrated that the evaluation method based on inclusion sizes collected from 3D inclusion information provided a stable result. It means that the extreme value evaluation method with the 3D data based on Micro-CT was an effective method.

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Zheng, Yihao, Yancheng Wang, Roland K. Chen, Sagar Deshpande, Noah S. Nelson, Steven R. Buchman et Albert J. Shih. « Tissue transformation mold design and stereolithography fabrication ». Rapid Prototyping Journal 23, n^o 1 (16 janvier 2017) : 162–68. http://dx.doi.org/10.1108/rpj-10-2015-0133.

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Purpose To obtain a vascularized autologous bone graft by in-vivo tissue transformation, a biocompatible tissue transformation mold (TTM) is needed. An ideal TTM is of high geometric accuracy and X-ray radiolucent for monitoring the bone tissue formation. The purpose of this study is to present the TTM design and fabrication process, using 3D reconstruction, stereolithography (SLA) and silicone molding. Design/methodology/approach The rat mandible, the targeted bone graft, was scanned by micro-computed tomography (CT). From the micro-CT images, the 3D mandible model was identified and used as the cavity geometry to design the TTM. The TTM was fabricated by molding the biocompatible and radiolucent silicone in the SLA molds. This TTM was implanted in a rat for in vivo tests on its biocompatibility and X-ray radiolucency. Findings SLA can fabricate the TTM with a cavity shape that accurately replicates that of the rat mandible. The bone formation inside of the silicone TTM can be observed by X-ray. The TTM is feasible for in vivo tissue transformation for vascularized bone reconstruction. Research limitations/implications Research of the dimensional and geometrical accuracy of the TTM cavity is required in the future study of this process. Practical implications The TTM fabricated in this presented approach has been used for in-vivo tissue transformation. This technique can be implemented for bone reconstruction. Originality/value The precision fabrication of the TTMs for in-vivo tissue transformation into autogenous vascularized bone grafts with complex structures was achieved by using SLA, micro-CT and silicone molding.

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Yousuf, M. A., et M. Asaduzzaman. « An Efficient Ring Artifact Reduction Method Based on Projection Data for Micro-CT Images ». Journal of Scientific Research 2, n^o 1 (25 décembre 2009) : 37–45. http://dx.doi.org/10.3329/jsr.v2i1.2645.

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Ring artifacts are very troublesome in a flat-panel based micro computed tomography (micro-CT) since they might severely degrade visibility of the micro-CT images. Unlike ring artifacts in other types of micro-CTs such as image-intensifier based micro-CT, ring artifacts in a flat-panel detector based micro-CT are hardly removable since the sensitivity of the pixel elements in a flat-panel detector is less uniform than in other types of x-ray detectors. The dependence of the ring artifacts on many imaging conditions, such as tube voltage, detector integration time and phantom size, was first investigated. Based on the observation that the ring artifacts are not imaging-condition-invariant in a flat-panel detector based micro-CT, an efficient ring artifact correction method has been developed based on post-processing. In the filtered sinogram, the ring artifact positions are identified and then the defective lines are corrected in the original projection data before the filtered back-projection. Experimental results on capacitor phantom, contrast phantom and bone images verify the efficacy of the proposed method. Keywords: Micro-CT; Ring artifact correction; Flat-panel detector; Filtered back-projection; Small animal imaging. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.2645 J. Sci. Res. 2 (1), 37-45 (2010)

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Satoh, Takahiro. « Development of particle induced X-ray emission-computed tomography in Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency ». International Journal of PIXE 25, n^o 03n04 (janvier 2015) : 147–52. http://dx.doi.org/10.1142/s0129083515500151.

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A new micro-particle induced X-ray emission-computed tomography (PIXE-CT) system was developed at Takasaki Ion Accelerators for Advanced Radiation Application in Japan Atomic Energy Agency. In this system, scanning transmission ion microscopy-CT was performed as well as PIXE-CT for three-dimensional (3D) measurement of major elements' distributions, which are required for corrections of X-ray yields due to energy losses of projectiles and absorption of X-rays. Moreover, maximum likelihood expectation maximization algorithm has been introduced to image reconstruction because higher spatial resolution can be obtained even with less X-ray yields. Consequently, 3D distribution of trace elements in a minute biological cell less than 100 μm has been successfully obtained.

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Watanabe, Toshiki, Akihisa Takeuchi, Masayuki Uesugi, Tomoki Uchiyama, Takahiko Asaoka, Yoichiro Tsuji, Hideto Imai, Yoshiharu Sakurai et Yoshiharu Uchimoto. « High Resolution Observation of Liquid Water in Polymer Electrolyte Fuel Cell Using X-Ray Nano Computed Tomography ». ECS Meeting Abstracts MA2022-02, n^o 39 (9 octobre 2022) : 1388. http://dx.doi.org/10.1149/ma2022-02391388mtgabs.

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Polymer electrolyte fuel cells (PEFCs) are attracting attention as energy device of low environmental impact because of their high generation efficiency and their emitting only water. The gas supplied to the PEFC is humidified, and water is produced at the cathode catalytic layer by the electrochemical reaction between oxygen and protons. The gas diffusion layer (GDL) and micro porous layer (MPL) in PEFC plays an important role in the transport of oxygen and water. When liquid water accumulates in the GDL, the supply of oxygen to the cathode is inhibited, resulting in poor generation performance. In order to maintain the performance of PEFCs, it is important to manage the water in the cell. Attempts have been made to visualize the liquid water in GDLs and MPLs for better GDL and MPL design; X-ray micro computed tomography (micro-CT) is one powerful tool for this. Visualization of liquid water in GDLs and MPLs using micro-CT has so far revealed the behavior of the produced water[1,2]. However, in previous studies, it has been difficult to visualize liquid water in the catalyst layer, which is the reaction field where the water is produced. This is because the spatial resolution of micro-CT is larger than a µm, which is insufficient for analyzing liquid water in the catalytic layer. X-ray CT measurements with a resolution of at least 150 nm are needed to measure the distribution of liquid water in the cross section of the catalyst layer. In this study, a measurement system to reveal the distribution of liquid water in the catalyst layer was developed using a 150 nm-spatial-resolution X-ray CT with a synchrotron radiation x-ray microscope called X-ray nano-CT. A GDL specimen prepared cut to a disk shape with 1 mm diameter. The GDL specimen mounted on a copper stage with high thermal conductivity connected Peltier element module. The micro-CT and nano-CT measurements were carried out in BL20XU beamline at SPring-8, Japan. An X-ray beam energy was 30 keV with a double crystal monochromator. The nano-CT measurements were performed using Zernike phase contrast with voxel size of 38.4 nm. We measured the micro-CT and nano-CT of the dry condition of the GDL specimen. Then, the GDL specimen injected liquid water was scanned. Injection of liquid water into the GDL specimen is not easy because of water-repellent of GDLs. Helium gas saturated water vapor at 40 °C was sprayed to the GDL at 30 ml/min, then the GDL cooled to 10 °C using a Peltier element module and the vapor was condensed inside of the GDL. The measurement setup is shown in Figure 1. This water injection in GDL method was based on the method reported by Kato et al [2]. Figure 2 shows the optical system of the nano-CT used in this study. The optical system of this nano-CT provides a condenser zone plate for sample illumination, a Fresnel zone plate for enlarged image, and phase ring for Zernike phase contrast. These optics allow CT with a high spatial resolution of 150 nm to be measured even for materials with low X-ray absorption. A three-dimensional structure of GDL was revealed by CT measurements in each scale order. The distribution of liquid water in GDL were visualized with nanoscale spatial resolution (Figure 3). We have successfully visualized the three-dimension distribution of liquid water in the GDL with nm order scale using nano-CT. The newly established nano-CT with a spatial resolution of 150 nm order is extremely useful for elucidating liquid-water behavior in PEFCs containing catalyst layers, which was not clear before. Acknowledgements This work is based on results obtained from a NEDO FC-Platform project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). This study was partially supported by the Synchrotron radiation experiments performed at BL20XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal numbers 2021A2009, 2021B1015). References: 1) U. U. Ince, H. Markötter, N. Ge, M. Klages, J. Haußmann, M. Göbel, J. Scholta, A. Bazylak, I. Manke, Int. J. Hydrog. Energy, 45, 12161–12169 (2020) 2) S. Kato, S. Yamaguchi, W. Yoshimune, Y. Matsuoka, A. Kato, Y. Nagai, T. Suzuki, Electrochem. Commun., 111, 106644 (2020) Figure 1

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Othman, Faisal, Yamin Wang et Furqan Le-Hussain. « The Effect of Fines Migration During CO2 Injection Using Pore-Scale Characterization ». SPE Journal 24, n^o 06 (15 juillet 2019) : 2804–21. http://dx.doi.org/10.2118/192076-pa.

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Summary Recent laboratory studies have shown that fines migration induces a decrease in rock permeability during CO2 injection. This study uses X–ray microcomputed tomography (micro–CT), nitrogen permeability, and Itrax X–ray fluorescence (Itrax–XRF) scanning to investigate the mechanism of fines migration during CO2 injection. We perform CO2–flooding experiments on two Berea core samples. The cores are characterized using nitrogen permeability, micro–CT, scanning electron microscopy with energy–dispersive X–ray spectroscopy (SEM–EDS), and Itrax–XRF scanning. The cores are flooded with fresh water, then CO2–saturated water, and finally water–saturated supercritical CO2 (scCO2). To calculate permeability, the pressure difference across the core samples is monitored during these fluid injections. The produced–water samples are analyzed using inductively coupled plasma–optical emission spectrometry (ICP–OES). After the flooding experiments, nitrogen permeability, micro–CT, SEM–EDS, and XRF scanning are repeated to characterize pore–scale damage. Micro–CT image–based computations are run to estimate permeability decrease along the core–sample length after injection. Results show the dissolution of dolomite and other high–density minerals. Mineral dissolution dislodges fines particles, which migrate during water-saturated–scCO2 injection. During CO2–saturated–water injection, the permeability of Berea 1 and Berea 2 increase by 29 and 13%, respectively. After water–saturated–scCO2 injection, the permeability of Berea 1 and Berea 2 decrease by 60%. The permeability damage of the sample can be explained by fines migration and subsequent blockage. SEM–EDS images also show instances of pore blockage.

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Geier, Benedikt, Janina Oetjen, Bernhard Ruthensteiner, Maxim Polikarpov, Harald R. Gruber-Vodicka et Manuel Liebeke. « Connecting structure and function from organisms to molecules in small-animal symbioses through chemo-histo-tomography ». Proceedings of the National Academy of Sciences 118, n^o 27 (28 juin 2021) : e2023773118. http://dx.doi.org/10.1073/pnas.2023773118.

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Our understanding of metabolic interactions between small symbiotic animals and bacteria or parasitic eukaryotes that reside within their bodies is extremely limited. This gap in knowledge originates from a methodological challenge, namely to connect histological changes in host tissues induced by beneficial and parasitic (micro)organisms to the underlying metabolites. We addressed this challenge and developed chemo-histo-tomography (CHEMHIST), a culture-independent approach to connect anatomic structure and metabolic function in millimeter-sized symbiotic animals. CHEMHIST combines chemical imaging of metabolites based on mass spectrometry imaging (MSI) and microanatomy-based micro-computed X-ray tomography (micro-CT) on the same animal. Both high-resolution MSI and micro-CT allowed us to correlate the distribution of metabolites to the same animal’s three-dimensional (3D) histology down to submicrometer resolutions. Our protocol is compatible with tissue-specific DNA sequencing and fluorescence in situ hybridization for the taxonomic identification and localization of the associated micro(organisms). Building CHEMHIST upon in situ imaging, we sampled an earthworm from its natural habitat and created an interactive 3D model of its physical and chemical interactions with bacteria and parasitic nematodes in its tissues. Combining MSI and micro-CT, we present a methodological groundwork for connecting metabolic and anatomic phenotypes of small symbiotic animals that often represent keystone species for ecosystem functioning.

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Kytýř, Daniel, Tomáš Fíla, Petr Koudelka, Ivana Kumpová, Michal Vopálenský, Leona Vavro et Martin Vavro. « INSTRUMENTATION OF FOUR-POINT BENDING TEST DURING 4D COMPUTED TOMOGRAPHY ». Acta Polytechnica CTU Proceedings 18 (23 octobre 2018) : 20. http://dx.doi.org/10.14311/app.2018.18.0020.

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High-resolution time-lapse micro-focus X-ray computed tomography is an effective method for investigation of deformation processes on volumetric basis including fracture propagation characteristics of non-homogeneous materials subjected to mechanical loading. This experimental method requires implementation of specifically designed loading devices to X-ray imaging setups. In case of bending tests, our background research showed that no commercial solution allowing for reliable investigation of so called fracture process zone in quasi-brittle materials is currently available. Thus, this paper is focused on description of recently developed in-situ four-point bending loading device and its instrumentation for testing of quasi-brittle materials. Proof of concept together with the pilot experiments were successfully performed in a CT scanner TORATOM. Based on results of the pilot experiments, we demonstrate that crack development and propagation in a quasi-brittle material can be successfully observed in 3D using high resolution 4D micro-CT under loading.

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Lee, Dongyun, et Jisun Shin. « Generalized Pulp Stones of Primary Dentition in a Patient with Molar-Incisor Malformation : A Case Report ». JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY 47, n^o 3 (31 août 2020) : 337–43. http://dx.doi.org/10.5933/jkapd.2020.47.3.337.

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Molar-incisor malformation (MIM) is a new type of root anomaly reported recently. The characteristics of MIM are dysplastic root formations, constriction of pulp chambers and presence of calcified matrices at the level of cementoenamel junction in permanent first molars and primary second molars. In some cases, permanent maxillary incisors are also affected.The permanent first molars of the patient in this case report were affected with MIM. Generalized pulp stones were observed in overall primary dentition. Micro-computed tomography (micro-CT) imaging and scanning electron microscope-energy dispersive X-ray spectrometer analysis were performed on the extracted mandibular first molar and maxillary primary second molar of the patient. Micro-CT images revealed the discontinuity of enamel directly connected to an accessory canal of the root.

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