X-ray Micro-computed Tomography Scanning Research Articles

Sensitivity of planktic foraminiferal test bulk density to ocean acidification

The anthropogenic CO2 accumulating in the ocean is lowering seawater carbonate ion concentration and may reduce calcification rates of marine calcareous organisms. Several proxies based on test weights of planktic foraminifera have been used to evaluate the impact of ocean acidification on these organisms. Unfortunately, because of the absence of a method to evaluate the bulk density of a test, the impact of seawater carbonate chemistry on test calcification is still not fully understood. In this study, we measured bulk densities of living Globigerina bulloides (planktic foraminifera) tests with an X-ray micro-computed tomography (XMCT) scanner and compared them with ambient seawater characteristics. Results demonstrated that test bulk densities were controlled by ambient seawater carbonate ion concentrations and that changes of test bulk densities were accompanied by changes in micron to submicron scale porosity of internal ultrastructure. These results suggest that alteration of the bulk density of foraminiferal tests due to acidification of ambient seawater can be directly observed by XMCT scanning. A useful metric of calcification intensity would therefore be physical measurements of test densities with XMCT.

Adaptive Diversification of the Lateral Line System during Cichlid Fish Radiation

SummaryThe mechanosensory lateral line system is used by fishes to sense hydrodynamic stimuli in their environment. It provides information about flow regimes, proximity to substrate, and the presence and identity of prey and predators and represents a means of receiving communication signals from other fish. Thus we may expect lateral line system structures to be under strong divergent selection during adaptive radiation. Here, we used X-ray micro-computed tomography scans to quantify variation in cranial lateral line canal morphology within the adaptive radiation of Lake Malawi cichlids. We report that cranial lateral line canal morphology is strongly correlated with diet and other aspects of craniofacial morphology, including the shape of oral jaws. These results indicate an adaptive role for the lateral line system in prey detection and suggest that diversification of this system has taken an important role in the spectacular evolution of Lake Malawi's cichlid fish diversity.

Comprehensive study of the interactions between the critical dimensionless numbers associated with multiphase flow in 3D porous media

Multiphase flow in porous media is of great interest in many engineering applications, such as geologic carbon sequestration, enhanced oil recovery, and groundwater contamination and remediation. In order to advance the fundamental understanding of multiphase flow in complex three-dimensional (3D) porous media, the interactions between the critical dimensionless numbers, including the contact angle, viscosity ratio, and capillary (Ca) number, were investigated using X-ray micro-computed tomography (micro-CT) scanning and lattice Boltzmann (LB) modeling. In this study, the 3D pore structure information was extracted from micro-CT images and then used as interior boundary conditions of flow modeling in a pore-scale LB simulator to simulate multiphase flow within the pore space. A Berea sandstone sample was scanned and then two-phase flow LB simulations were performed based on the micro-CT images. The LB-simulated water/CO2 distributions agreed well with the micro-CT scanned images. Simulation results showed that a decreasing contact angle causes a decrease in wetting-fluid relative permeability and an increase in non-wetting fluid relative permeability. A rising Ca number increases both wetting and non-wetting fluid relative permeabilities. An increasing viscosity ratio (the ratio of non-wetting fluid viscosity to wetting fluid viscosity) facilitates the increase of non-wetting fluid relative permeability and mitigates the reduction of wetting fluid relative permeability, when the contact angle decreases continuously. The primary novel finding of this study is that the viscosity ratio affects the rate of change of the relative permeability curves for both phases when the contact angle changes continuously. To the best of our knowledge, it is the first time that comprehensive interactions between these dimensionless numbers are demonstrated in a sandstone sample based on real 3D structures. We also investigated the role of the changes of flow direction and sample location on relative permeability curves. Simulation results showed that the change in non-wetting fluid relative permeability was larger when the flow direction was switched from vertical to horizontal, which indicated that there was stronger anisotropy in larger pore networks that were primarily occupied by the non-wetting fluid.

Mechanical anisotropy of coal with considerations of realistic microstructures and external loading directions

This paper investigates the anisotropy of coal under uniaxial compression conditions using both experimental and numerical methods. Primary wave (P-wave) velocity measurements, X-ray micro-computed tomography (CT) scanning, and uniaxial compression tests were conducted to assess the anisotropic characteristics of selected coal samples. Based on the experimental results, comprehensive analyses were carried out to study the influences of different contributing factors on the anisotropic properties of coal. A three-dimensional (3D) finite difference model was then built to further investigate the effects of failure initiation, stress redistribution and the presence of microstructures on the anisotropy of coal. The experimental and numerical results of uniaxial compression tests indicate that the coal strength anisotropy is affected by the directional distribution of the microstructures. Bedding planes directly control the uniaxial compressive strength of coal, and face cleats have a greater influence on the mechanical properties than butter cleats. The presence of mineral inclusions increases the heterogeneity of coal because of the significant differences in strength and deformation in the mineral inclusion zones. The mechanical and seismic anisotropies are both directly related to the directional distribution of the microstructures, which is demonstrated by the variations in the anisotropic strength and P-wave velocity of the coal. The correlations between the uniaxial compressive strength (UCS) and P-wave velocity are different when the coals are loaded in different directions, and an exponential correlation was suitable for defining this relationship.

Functional whole wheat breads: Compelling internal architecture

In this study, X-ray micro-computed tomography scanning coupled with image analysis was used to investigate the influence of bread formulation on micro-structural characteristics of bread particularly its crumb. Results for standard whole wheat flour bread (WWB) and two functional breads formulated by partial replacement of whole wheat flour by 10% (FGF10) and 20% (FGF20) cryo-ground fermented green gram flour showed a significant variation in their micro-structural properties. For example, the total volume of bread crumb and total surface area of pores were nearly reduced by 34% in FGF10 and 71% in FGF20 samples compared to WWB. Further, height of loaf along with crumb properties: porosity, total number of pores, interconnectivity index, diameter of open pore, and volume of open pore followed the order WWB > FGF10 > FGF20. These variations have resulted in 11.85–16.75% reduction in specific loaf volume of functional breads compared to WWB. Conversely, crumb properties such as wall thickness, volume fraction of solid phase, percentage of closed pore, diameter of closed pore, and volume of closed pore showed reverse trend resulting in rise in crumb hardness of functional breads by 22.57–37.21% compared to WWB. Three-dimensional images of breads also supported the quantitative results.

Virtual micromorphology: The application of micro-CT scanning for the identification of termite mounds in archaeological sediments

X-ray micro-computed tomography (micro-CT) scans were conducted on impregnated sediment blocks from the early Holocene rockshelter site of Lapa do Santo, East-Central Brazil. The analysis was designed to investigate the presence of termite mound fragments in the archaeological sediments and test the value of complementary techniques in micromorphological studies. Soil feeding termites have been common in the tropical soils of Central Brazil since the Paleogene/Neogene and exist in high concentrations in the surroundings of Lapa do Santo. The micro-CT scans revealed a distinctive spongy microstructure inside some of the clay aggregates in the sediments that are not visible in thin section, matching the spongy microstructure inside termite mound fragments. The microstructure consists of a mix of clay and organic material (feces, saliva and other body fluids) produced by termites to cement the mounds' matrix. The cements are undistinguishable from the matrix under the microscope, but clearly visible in the micro-CT scans given the low attenuation coefficient of organo-mineral matter. The termite mound fragments appear dispersed within the ashy matrix (made of intact and reworked combustion features), suggesting their possible use in earth ovens. The combination of combustion features and reworked earth ovens attests to the complex input of anthropogenic sediments in the formation of Lapa do Santo. This study demonstrates that micro-CT can potentially disclose materials not visible in thin section and can be utilized as a complementary technique to micromorphology.

Phylogeny of the Eocene Aphalarinae (Hemiptera: Psylloidea) from Baltic amber, with description of a new species using X-ray micro-computed tomography scanning, and a new genus synonymy

A new Eocene species of Psylloidea is described from Baltic amber. Eogyropsylla pankowskii Ashe-Jepson & Ouvrard sp. nov., along with E. magna and E. parva, is micro- computed tomography (CT) scanned to produce three-dimensional reconstructions, facilitating the detailed description of its morphology, and updated descriptions of other members of Eogyropsylla. The thoracic structures are described in detail. Eogyropsylla pankowskii may be the first fossil psyllid found excreting honeydew. With the addition of this species, a phylogeny of Eogyropsylla is constructed using a discrete character matrix of morphological characters. These characters have been collected from the micro-CT scans, from direct observation, and from published literature for all known members of the genus. Parascenia weitschati Klimaszewski, 1997 appears wrongly classified in a separate genus based on male genitalia characters only, and we conclude that Parascenia Klimaszewski, 1997 is a junior synonym of Eogyropsylla Klimaszewski, 1993. Eogyropsylla now contains eight species, with Eogyropsylla weitschati comb. nov. being the only known male of the genus. The assignment of Eogyropsylla to Aphalarinae is confirmed. This genus branches basally in the aphalarine cladogram, as sister group to Colposcenia. The early evolution and Laurasian origin of the oldest known modern Psylloidea is discussed. This study demonstrates that micro-CT techniques are an invaluable tool for palaeontology and entomology.http://zoobank.org/urn:lsid:zoobank.org:pub:DAF44D3D-4C64-41E3-B525-E9E158302CC9

Modeling the Air Pressure Increase Within a Powder Bed During Compression—A Step Toward Understanding Tablet Defects

The cause of tablet defects, such as cracking, bubbling, and capping, during compression is currently not fully understood. Prior experimental work suggests that an increase in internal air pressure on powder compression can directly contribute to the formation of cracks within a tablet. The present study examines the air pressure increase on compression in a fully two-dimensional axisymmetric tablet geometry while being coupled to a plasticity model describing the evolution of tablet relative density on consolidation. It is shown numerically that increasing compression speed results in a large air pressure increase on the order of 1-1.5 MPa which approaches the diametrical tensile strength of tablets. In addition, it is shown experimentally through X-ray microcomputed tomography scans of tablets made at various dwell times that increasing dwell times equivalent to that on a tablet press has no effect on the degree of cracking within the tablet. Only when dwell times reach a time scale of 10 to 100 s does the air pressure diminish to a point at which cracking is eliminated. The reduction in air pressure during these extended dwells is captured by the current model. The experimental and numerical work presented here couples for the first time an air pressure model and plasticity model on compression. In addition, it provides a foundation for understanding how realistic tableting aspects such as precompression and tablet size impact the air pressure increase on consolidation.

Palaeopermeability anisotropy and geometrical properties of sealed-microfractures from micro-CT analyses: An open-source implementation

Fault zone permeability and the real 3D-spatial distribution of the fault-related fracture networks are critical in the assessment of fault zones behavior for fluids. The study of the real 3D-spatial distribution of the microfracture network, using X-ray micro-computed tomography, is a crucial factor to unravel the real structural permeability conditions of a fault-zone. Despite the availability of several commercial software for rock properties estimation from X-ray micro-computed tomography scanning, their high cost and lack of programmability encourage the use of open-source data treatment.This work presents the implementation of a methodology flow for the quantification of both structural and geometrical parameters (fractures density, fractures aperture, fractures porosity, and fractures surface area), and the modeling of palaeopermeability of fault-related fractured samples, with focus in the proper spatial orientation of both the sample and the results. This is performed with an easy to follow step-by-step implementation, by a combination of open-source software, newly implemented codes, and numerical methods. This approach keeps track of the sample’s spatial orientation from the physical to the virtual world, thus assessing any fault-related palaeopermeability anisotropy.

Methods to measure contact angles in scCO2-brine-sandstone systems

Numerous methods are used to measure contact angles (θ) in multiphase systems. The wettability and θ are primary controls on CO2 residual trapping during Geologic Carbon Storage (GCS) and determining these values within rock pores is paramount to increasing storage efficiency. One traditional experimental approach is the sessile drop method which involves θ measurements on a single image of droplets. More recent developments utilize X-ray micro-computed tomography (CT) scans which provide the resolutions necessary to image in situ θ of fluids at representative conditions; however, experimental micro-CT data is limited and varied. To further examine θ distributions in supercritical-CO2-brine-sandstone systems, a combination of manual and automated θ measurement methods were utilized to measure θ using both sessile drop and micro-CT images of two sandstone cores. The purpose of this work was threefold: (1) compare two current and two new θ measuring methods using micro-CT images of scCO2-brine-sandstone systems; (2) determine how traditional experimental method (sessile drop) θ results compare to in situ θ results (micro-CT); and (3) determine if the Matlab Contact Angle Algorithm (MCAA) from Klise et al. (2016) can be used to measure θ scCO2-brine-sandstone systems.One of the two new methods utilizing open-source software resulted in comparable average θ and θ ranges to the primary manual measuring method (Andrew et al., 2014b) reported in literature that requires commercial software to complete. An additional new method involves immersive interaction with micro-CT image volumes that no other software currently provides. Both processes are found to be promising for future work. θ measured using micro-CT images at in situ conditions result in a broader θ distribution than those measured using sessile drop images. These findings suggest some pores are intermediate-wet in an in situ sandstone system and factors other than interfacial tension influence trapping. Lastly, MCAA θ results consistently produced broader θ distributions and higher average θ than the manual θ measurements. This is a result of some automated measurements incorrectly identifying directional quantities leading to skewed results. MCAA is still promising for future work with careful attention to data interpretation.

Parametric Reconstruction of Glass Fiber-reinforced Polymer Composites from X-ray Projection Data\u2014A Simulation Study

We present a new approach to estimate geometry parameters of glass fibers in glass fiber-reinforced polymers from simulated X-ray micro-computed tomography scans. Traditionally, these parameters are estimated using a multi-step procedure including image reconstruction, pre-processing, segmentation and analysis of features of interest. Each step in this chain introduces errors that propagate through the pipeline and impair the accuracy of the estimated parameters. In the approach presented in this paper, we reconstruct volumes from a low number of projection angles using an iterative reconstruction technique and then estimate position, direction and length of the contained fibers incorporating a priori knowledge about their shape, modeled as a geometric representation, which is then optimized. Using simulation experiments, we show that our method can estimate those representations even in presence of noisy data and only very few projection angles available.

An evaluation of a double-tailed deformity in a coral-reef surgeonfish Acanthurus nigrofuscus (Acanthuridae) using micro-computed tomography.

X-ray micro-computed tomography scans were used to examine the caudal-fin structure of an unusual double-tailed deformity in an adult brown surgeonfish Acanthurus nigrofuscus from the Great Barrier Reef. In both this case and in a similar double-tailed deformity in a juvenile Tomini surgeonfish Ctenochaetus tominiensis from the Philippines, the caudal fin was duplicated along the dorsoventral axis. Detailed examination of the A. nigrofuscus specimen revealed that the deformity was associated with duplication and reflection of the hypural plates and the posterior vertebrae, yet the fish survived to adulthood, indicating that the effects of duplication on survival may be limited.

Investigation of particle fracture during fatigue of aluminum 2024

A significant portion of the mechanical energy that enters into a material subjected to fatigue is expended to nucleate local, early-state damage which is distinct from later observed catastrophic type damage frequently targeted in fatigue investigations. Therefore, identification of early signs of fatigue damage combined with means to monitor its evolution is crucial for understanding the influence of material microstructure on the development of progressive pre-failure sites that can ultimately lead to conditions that favor the development of fatigue damage. In this context, in situ scanning electron microscope (SEM) testing combined with microstructure-sensitive nondestructive evaluation (NDE) is leveraged, in this article, to allow the direct observation of fatigue damage incubation in a precipitate-hardened aluminum alloy, Al 2024-T3. To validate surface observations of such early signs of damage, X-ray Micro-Computed Tomography (μ-CT) scans were made to investigate the relation between particle size and chemical balance with local grain structure and crystallography. In addition, an effort was made to explore the effect of specimen geometry and loading schemes on the occurrence of particle fracture activity as well its evolution throughout the early stages of the specimen life. Furthermore, a machine learning approach was developed in an attempt to post-process the available NDE data and relate it to particle fracture activity.

A functional evaluation of feeding in the surgeonfish Ctenochaetus striatus: the role of soft tissues.

Ctenochaetus striatus is one of the most abundant surgeonfishes on Indo-Pacific coral reefs, yet the functional role and feeding ecology of this species remain unclear. This species is reported to possess a rigid structure in its palate that is used for scraping, but some authors have reported that this element is comprised of soft tissue. To resolve the nature and role of this structure in the feeding ecology of C. striatus we examined evidence from anatomical observations, scanning electron microscopy, histology, X-ray micro-computed tomography scanning, high-speed video and field observations. We found that C. striatus from the Great Barrier Reef possess a retention plate (RP) on their palates immediately posterior to the premaxillary teeth which is soft, covered in a thin veneer of keratin with a papillate surface. This RP appears to be used during feeding, but does not appear to be responsible for the removal of material, which is achieved primarily by a fast closure of the lower jaw. We infer that the RP acts primarily as a ‘dustpan’, in a ‘dustpan and brush’ feeding mechanism, to facilitate the collection of particulate material from algal turfs.

Processing of Al-Sc aluminum alloy using SLM technology

The proposed paper deals with the experimental determination of process parameters reaching densities >99 % for Scandium modified aluminum alloy (Scalmalloy®) processed by SLM 280HL. The alloy achieves significantly higher yield strength and higher elongation than the AlSi10Mg aluminum alloy figcommonly used. Potential of this alloy is for lightweight applications in space, aerospace, and automotive industries, where is a need of the best possible stiffness to weight ratio. Experiments were provided with different values of laser power and laser scanning speed. Layer thickness and other parameters stayed unchanged. The X-ray micro-computed tomography (μCT) scanning of the tensile specimen was used in order to obtain qualitative and quantitative information about the porosity.

Establishing an Animal Model of Secondary Osteoporosis by Using a Gonadotropin-releasing Hormone Agonist

Introduction: Orchidectomy is currently the preferred method to induce bone loss in preclinical male osteoporosis model. Gonadotropin-releasing hormone (GnRH) agonists used in prostate cancer treatment can induce testosterone deficiency but its effects on bone in preclinical male osteoporosis model are less studied.Objective: This study aimed to evaluate the skeletal effect of buserelin (a GnRH agonist) in male rats and compare it with orchidectomy.Methods: Forty-six three-month-old male Sprague-Dawley rats were divided into three experimental arms. The baseline arm (n=6) was sacrificed at the onset of the study. In the buserelin arm, the rats received a daily subcutaneous injection of either normal saline (n=8), buserelin acetate at 25 µg/kg (n=8) or 75 µg/kg (n=8). In the orchidectomy arm, the rats were either sham-operated (n=8) or orchidectomized (n=8). All groups underwent in-vivo X-ray micro-computed tomography scanning at the left proximal tibia every month. Blood was collected at the beginning and the end of the study for testosterone level evaluation. The rats were euthanized after the three-month treatment. The femurs were harvested for biomechanical strength and bone calcium determination.Results: The results showed that buserelin at both doses caused a significant decline in testosterone level and deterioration in bone microstructure (p<0.05), but did not affect bone calcium content (p>0.05). Buserelin at 25 µg/kg decreased displacement and strain of the femur significantly (p<0.05). Similar changes were observed in the orchidectomized group compared to the sham-operated group but without any significant changes in biomechanical strength (p>0.05).Conclusion: Buserelin can induce testosterone deficiency and the associated deterioration of bone microarchitecture similar to orchidectomy in three months. However, it may require a longer time to show significant effects on bone strength and mineral content.

Discrete element modeling of crushable sands considering realistic particle shape effect

This study proposed a novel approach for generating crushable agglomerates with realistic particle shapes in discrete element modeling (DEM). The morphologies of sand particles were obtained by X-ray micro-computed tomography scanning and image processing. Based on the particle surface reconstructed by spherical harmonic analysis, the crushable agglomerates with realistic particle shapes can be generated in DEM simulations. The results of single particle crushing tests showed that particle shapes significantly influence the fracture patterns and crushing strengths of sand particles. Furthermore, two one-dimensional compression tests were conducted to investigate the particle shape effect on micro- and macro-mechanical behaviors of crushable sands.

Deformation mechanisms of idealised cermets under multi-axial loading

The response of idealised cermets comprising approximately 60% by volume steel spheres in a Sn/Pb solder matrix is investigated under a range of axisymmetric compressive stress states. Digital volume correlation (DVC) anal`ysis of X-ray micro-computed tomography scans (μ-CT), and the measured macroscopic stress-strain curves of the specimens revealed two deformation mechanisms. At low triaxialities the deformation is granular in nature, with dilation occurring within shear bands. Under higher imposed hydrostatic pressures, the deformation mechanism transitions to a more homogeneous incompressible mode. However, DVC analyses revealed that under all triaxialities there are regions with local dilatory and compaction responses, with the magnitude of dilation and the number of zones wherein dilation occurs decreasing with increasing triaxiality. Two numerical models are presented in order to clarify these mechanisms: (i) a periodic unit cell model comprising nearly rigid spherical particles in a porous metal matrix and (ii) a discrete element model comprising a large random aggregate of spheres connected by non-linear normal and tangential “springs”. The periodic unit cell model captured the measured stress-strain response with reasonable accuracy but under-predicted the observed dilation at the lower triaxialities, because the kinematic constraints imposed by the skeleton of rigid particles were not accurately accounted for in this model. By contrast, the discrete element model captured the kinematics and predicted both the overall levels of dilation and the simultaneous presence of both local compaction and dilatory regions with the specimens. However, the levels of dilation in this model are dependent on the assumed contact law between the spheres. Moreover, since the matrix is not explicitly included in the analysis, this model cannot be used to predict the stress-strain responses. These analyses have revealed that the complete constitutive response of cermets depends both on the kinematic constraints imposed by the particle aggregate skeleton, and the constraints imposed by the metal matrix filling the interstitial spaces in that skeleton.

Industrial Applications of Selected JFS Articles

Industrial Applications of Selected <i>JFS</i> Articles

Comparison of Microwave and Conventional Frying on Quality Attributes and Fat Content of Potatoes.

A comparative analysis of quality attributes (moisture, fat, color, and relaxation modulus) of French fries was performed between conventional and microwave frying. Experiments were performed in triplicate for both frying operations at temperatures of 177, 185, and 193 °C for frying times of 60, 90, and 120 s. The real-time pressure and temperature profiles at above conditions indicated that during microwave frying, gage pressure had greater magnitudes that lasted longer, and the temperature increased to boiling point of water faster in comparison to conventional frying. Lower magnitude of negative pressure during microwave frying is expected to have caused lower fat content in fries obtained using this method (0.08 g/g solids less at 185 °C and 0.07 g/g solids less at 193 °C) than conventional frying. The lightness parameter (L* ) decreased to a lesser extent in microwave frying than in conventional frying. The stress relaxation function of the French fries were significantly different between the 2 frying operations. Consumer test confirmed that reduced fat uptake during microwave frying did not compromise with desirable quality attributes of French fries. X-ray micro-computed tomography scanning provided complementary understanding about differences in microstructural properties of fries made using microwave and conventional frying.