X-ray Microtomography Methods Research Articles

Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

Bamboo plants are an essential component of tropical ecosystems, yet their vulnerability to climate extremes, such as drought, is poorly understood due to limited knowledge of their hydraulic properties. Cephalostachyum pergracile, a commonly used tropical bamboo species, exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019, but the underlying mechanisms remain unclear. This study investigated the leaf and stem hydraulic traits related to drought responses, including leaf-stem embolism resistance (P50leaf; P50stem) estimated using optical and X-ray microtomography methods, leaf pressure–volume and water-releasing curves. Additionally, we investigated the seasonal water potentials, native embolism level (PLC) and xylem water source using stable isotope. We found that C. pergracile exhibited strong resistance to embolism, showing low P50leaf, P50stem, and turgor loss point, despite its rapid leaf water loss. Interestingly, its leaves displayed greater resistance to embolism than its stem, suggesting a lack of effective hydraulic vulnerability segmentation (HVS) to protect the stem from excessive xylem tension. During the dry season, approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer. Consequently, significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87 ± 2.33% in the wet season to 12.87 ± 4.09% in the dry season were observed. In summary, this study demonstrated that the rapid leaf water loss, high reliance on surface water, and a lack of effective HVS in C. pergracile accelerated water depletion and increased xylem embolism even in the typical dry season, which may explain its high mortality rate during extreme drought events in 2019.

Water refilling along vessels at initial stage of willow cuttage revealed by move contrast CT

Cuttage is a widely used technique for plant propagation, whose success relies on the refilling for water transport recovery. However, requirements for refilling characterization studies, including large penetration depth, fast temporal resolution and high spatial resolution, cannot be reached simultaneously via conventional imaging techniques. So far, the dynamic process of water refilling along the vessels at the initial stage of cuttage, as well as its characteristics, remains unclear. Hereby, we developed a move contrast X-ray microtomography method which achieves 3D dynamic non-destructive imaging of water refilling at the initial stage of willow branch cuttage, without the aid of any contrast agent. Experimental results indicate three primary refilling modalities in vessels: 1) the osmosis type, mainly manifested by the osmosis of tissue through the vessel wall into the cavity; 2) the linear type, revealed as the tissue permeates to a certain extent where the liquid column in the vessels is completely formed; and 3) an osmosis-linear mixed type refilling as an intermediate state. Further analysis also exhibits a “temporal-spatial relay” mode of refilling between adjacent vessels. Since the vessel length is quite limited, the cavitation and the relay refilling mode of vessels can be an important way to achieve long-distance water transport.

Characterization of Systemic Disease Development and Paw Inflammation in a Susceptible Mouse Model of Mayaro Virus Infection and Validation Using X-ray Synchrotron Microtomography.

Mayaro virus (MAYV) is an emerging arthropod-borne virus endemic in Latin America and the causative agent of arthritogenic febrile disease. Mayaro fever is poorly understood; thus, we established an in vivo model of infection in susceptible type-I interferon receptor-deficient mice (IFNAR-/-) to characterize the disease. MAYV inoculations in the hind paws of IFNAR-/- mice result in visible paw inflammation, evolve into a disseminated infection and involve the activation of immune responses and inflammation. The histological analysis of inflamed paws indicated edema at the dermis and between muscle fibers and ligaments. Paw edema affected multiple tissues and was associated with MAYV replication, the local production of CXCL1 and the recruitment of granulocytes and mononuclear leukocytes to muscle. We developed a semi-automated X-ray microtomography method to visualize both soft tissue and bone, allowing for the quantification of MAYV-induced paw edema in 3D with a voxel size of 69 µm3. The results confirmed early edema onset and spreading through multiple tissues in inoculated paws. In conclusion, we detailed features of MAYV-induced systemic disease and the manifestation of paw edema in a mouse model extensively used to study infection with alphaviruses. The participation of lymphocytes and neutrophils and expression of CXCL1 are key features in both systemic and local manifestations of MAYV disease.

An assessment of mineral concentration of dental enamel neighbouring hypothetical orthodontic brackets using X-ray microtomography

ObjectivesDifferences in the mineral concentration (MC) level of dental enamel may represent a precursor of white spot lesions adjacent to fixed orthodontic brackets. The aim of the current in vitro study was to compare the MC level central, occlusal and cervical to orthodontic attachments. Methods and MaterialsA total of 16 enamel blocks were obtained from sound human premolar samples extracted for orthodontic reasons. The buccal portion of the dental enamel blocks was divided into central, occlusal, and cervical regions and then imaged and measured to calculate the level of MC using quantitative X-ray microtomography methods (XMT) at each site. ResultsThere was a substantial variation in the mineral concentration with the lowest level being detected in the cervical region when compared with other regions. The MC of the gingival zone was significantly lower than that of the middle zone (P<0.05) and was insignificantly lower than that of the occlusal zone. ConclusionWithin the limitations of the current study, it can be concluded that the cervical region of the permanent enamel had the lowest mineral concentration using XMT. The cervical region may therefore be more vulnerable to the development of white spot lesions (WSLs) adjacent to a fixed orthodontic appliance during orthodontic treatment. Clinical significanceUsing X-ray microtomography lower mineral concentration in the cervical region of the enamel was observed. This may make these areas particularly susceptible to demineralisation during fixed appliance-based orthodontic treatment and may influence the bond strength of fixed orthodontic attachments.

In Situ Visualization of Li-Whisker with Grating-Interferometry-Based Tricontrast X-ray Microtomography

The lithium-ion battery has demonstrated tremendous economic and social impacts. Upon battery operation under different conditions, lithium changes its chemical state and physical formation, leading to undesired side reactions, e.g., lithium dendrite growth that degrades the cell performance and causes safety concerns. In situ detection and visualization of lithium metal in functional batteries could offer insights with both scientific and industrial significance but remain a frontier challenge. Here, we demonstrate in situ three-dimensional imaging of lithium whisker using a grating-interferometry-based tricontrast X-ray microtomography method. Our approach explicitly reveals the micromorphology of the electrochemically developed porous lithium whisker with micrometer-level spatial resolution while offering sensitivity to the nanoporosity that is smaller than the nominal resolution limit. Our result reveals valuable structural information on the lithium whisker that is otherwise inaccessible. This method is also readily applicable to a broad range of battery research, including all-solid-state batteries.

Air-water interfacial areas relevant for transport of per and poly-fluoroalkyl substances

Per and polyfluoroalkyl substances (PFAS) present in the soil pose a long-term threat to groundwater. Robust characterization and modeling of PFAS retention and transport in unsaturated systems requires an accurate determination of the magnitude of air-water interfacial area (AWIA). Multiple methods are available for measuring or estimating air-water interfacial area, including x-ray microtomography (XMT), various aqueous and gas-phase interfacial tracer-test (ITT) methods, and thermodynamic-based estimation methods. AWIAs determined with the different methods can vary significantly. Therefore, it is critical to determine which measurement methods are relevant for application to PFAS retention and transport. This is achieved by employing AWIAs determined with different methods to simulate the results of miscible-displacement experiments reported in the literature for the transport of perfluorooctanoic acid (PFOA) in an unsaturated quartz sand. Measured PFOA breakthrough curves were successfully predicted using AWIA values measured by aqueous ITT methods. Conversely, AWIAs measured with the XMT method and estimated with the thermodynamic method under-predicted the magnitude of retardation and could not successfully simulate the measured transport data. These results indicate that the ITT method appears to provide the most appropriate AWIA values for robust characterization and modeling of PFAS transport in unsaturated systems. The long-term impact of employing different AWIA values on PFOA leaching in the vadose zone was simulated for a representative AFFF application scenario. The predicted timeframes for PFOA migration to groundwater varied from 3 to 6 to 20 years depending on which AWIA was used in the simulation. These relatively large differences would result in significantly different risk-assessment outcomes. These results illustrate that it is critical to employ the AWIA that is most representative of PFAS retention for accurate predictions of PFAS leaching in the vadose zone.

Water desorption characteristics of saturated lightweight fine aggregate in ultra-high performance concrete

In this study, the water desorption behavior of saturated lightweight fine aggregate (LWA) in ultra-high performance concrete (UHPC) was systemmically investigated using isothermal calorimetry, relative humidity (RH), mercury intrusion porosimetry, X-ray microtomography methods, etc. The LWA with high porosity and coarse pore structure exhibited high absorption and easy desorption at high RH. The results indicate that a large amount of water in LWA was released before setting, resulting in an increase of water to binder ratio, which had an adverse effect on the performance. However, the water absorbed in LWA released fast after 6 h, inducing an internal curing effect. Mechanism on a "four-stage desorption" driven by capillary pressure and RH gradient was proposed. The water desorption that is beneficial for the internal curing is calculated. The results indicated that the internal curing efficiency could be enhanced by increasing LWA content and reducing its pore size.

Структурные и спектральные особенности композитов на основе белковых сред с одностенными углеродными нанотрубоками

Исследованы структурные особенности нанокомпозитов, полученных при лазерном облучении водно-белковых сред с одностенными углеродными нанотрубками (ОУНТ), электродуговым (ОУНТI) и газофазным методами (ОУНТII). С помощью спектроскопии комбинационного рассеяния нанокомпозитов определен нековалентный характер взаимодействия нанотрубок с молекулами белков. Белковая составляющая в нанокомпозитах подверглась необратимой денатурации и может выступать в качестве связующего биосовместимого материала, который является источником аминокислот для биологических тканей при имплантации нанокомпозитов в организм. Образцы, изготовленные из ОУНТI, с меньшим диаметром и длиной имели наиболее однородную структуру. При увеличении концентрации от 0.01 до 0.1 % происходило увеличение среднего размерамикропор от 45 до 85 мкм и пористости образца в общем с 46 до 58 %. При этом доля открытых пор для двух типов концентраций ОУНТI составила 2 % от общего объема композита. 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Determination of sintering stress and bulk viscosity from sinter-forging and X-ray microtomography methods: a Review

Abstract Sintering stress and bulk viscosity for viscous sintering of glass were determined by two methods; sinter-forging and X-ray microtomography methods. Calcium aluminosilicate (CAS) glass with the diameter of 2.7 µm was chosen in sinter-forging experiment, while soda-lime glass with the diameter of 160 μm was observed by X-ray microtomography. Sintering stress of CAS glass and soda-lime glass was normalized by surface energy and the initial particle size. The normalized sintering stress of CAS glass determined by sinter-forging method was in fair agreement with values estimated from the X-ray microtomography data of soda-lime glass, despite the differences in particle shape and chemical composition. Bulk viscosity were also normalized by glass viscosity, and the normalized bulk viscosity obtained by sinter-forging method agreed fairly well with that estimated by X-ray microtomography method.

Comparison between sinter forging and X-ray microtomography methods for determining sintering stress and bulk viscosity

The macroscopic sintering parameters, sintering stress, bulk viscosity, and shear viscosity, were measured by the discontinuous sinter forging experiment for viscous sintering of calcium aluminosilicate (CAS) glass. The calculated results were compared with experimental values from the microstructural evolution during viscous sintering of spherical soda lime glass particles by X-ray microtomography. The sintering stress of CAS glass normalized by surface energy and the initial particle size was in good agreement with values estimated from the microtomography data of soda lime glass, despite the differences in particle shape and chemical composition. The bulk viscosity obtained by discontinuous sinter forging agreed fairly well with that estimated by X-ray microtomography observation, when they were normalized by glass viscosity.

Microtomographic analysis of pore space in a virgin soddy-podzolic soil

The method of X-ray microtomography was applied to study pore space of a virgin soddy-podzolic soil at the natural soil water content. The morphometric parameters of the pores of more than 100 μm in diameter were determined in the vertically oriented undisturbed soil monoliths (d = 3 cm, h = 3–4 cm) from the genetic horizons of the most differentiated part of the soil profile (the AY, AEL, EL, BEL, BT1, and BТ2 horizons). A tendency for the horizontal orientation of these pores was found in all the horizons, except for the humus (AY) horizon. Isolated vesicular pores of different sizes were abundant in the eluvial part of the profile. Numerous recent and relict phytogenic channels were found in the intraped mass of the BT2 horizon. Differently directed interfaces of structural units in the soil horizons were visualized. Cluster analysis was applied to estimate differences between the genetic horizons with respect to their textures, aggregate sizes, and shapes of pores as seen in vertical two-dimensional X-ray images.

Application of X-ray microtomography to quality assessment of fibre cement boards

In this paper a method of X-ray microtomography (micro-CT) was employed for a direct insight into a microstructure of fibre cement boards of different quality. Four specimens were subjects of examination. Two parameters were determined to characterize the level of compaction of fibres in concrete matrix: mean-square displacement of migrating virtual particles after 500,000 of time steps and a diffusive tortuosity. The results of the investigation had revealed that fibre cement boards differing in density produce different images after processing with micro-CT method. The effect of microstructure tightening due to saturation using dying agent was also detectable.

Microstructural characteristics of wellbore cement and formation rocks under sequestration conditions

Abstract One of the most important aspects of the interaction between well-bore cement and the formation rock are the porosimetric parameters of both materials. Porosity and pore-size distribution affect the behaviour of the porous solid material, including the fluid movement and flow. In order to analyse the porosity of rock and cement material in the presented investigation the following procedures were applied: mercury intrusion porosimetry (MIP), gas adsorption technique and X-ray microtomography (XMT). The investigation proved the usefulness of XMT method, which enables the microstructural characterisation of the composed (cement–rock) samples during the subsequent stages of the experiment. Imaging the cement degradation in the rock–cement contact zone is possible, thanks to the differentiated densities of the altered zones, resulting from the rock or cement dissolution, and new phases precipitation. Five rock samples of different lithology (quartzitic sandstone, eolian sandstone, shale, limestone and anhydrite) were selected for the examination. The prepared samples composed of well bore cement and rock were exposed to CO2-saturated brine, under static conditions. Basing on the shape of the gas adsorption isotherms the classification of the materials (cement and rocks) was performed. In the case of the rocks classified as macroporous, because of the porosity characteristics close to those of cement, the CO2 saturated brine flow is uniform in both materials (cement and rock), and the dissolution and precipitation processes are less intense. The obtained results seem to be very useful for predicting the integrity of wellbore, in case of different caprock and reservoir rock.

Microcrack Analysis of Carbon Fiber Reinforced Plastic by Using X-ray Micro-Tomography Method

Microcrack Analysis of Carbon Fiber Reinforced Plastic by Using X-ray Micro-Tomography Method

Study of helium bubble evolution in highly neutron-irradiated beryllium by using x-ray micro-tomography and metallography methods

Beryllium will be used as a plasma-facing material and a neutron multiplier in fusion reactors. The processes of helium accumulation in fusion and fission reactors are similar. Therefore, it is possible to extrapolate the data obtained on beryllium irradiated in a fission reactor to a fusion one. Fragments of the beryllium matrix of the BR2 reactor irradiated at 323 K up to a fast neutron fluence of 4.67×1022 cm−2 (E>1 MeV) and helium accumulation of about 22 500 appm with additional annealing at 1123 and 1273 K for 0.5, 1. 5 and 10 h were used for the investigation of helium porosity by optical metallography and x-ray micro-tomography methods. The possibility of using the XRT method for investigations of helium porosity evolution in irradiated and annealed beryllium was demonstrated. The non-uniformity of helium bubble formation in the material leads to a non-homogeneous swelling observed on the cross-section of the beryllium samples. The reason for high swelling in the bulk of the beryllium sample could be the formation of large stable helium bubbles, which are not mobile and not mutually connected.

Direct Prediction of Structure and Permeability of Flocculated Structures and Sediments Using 3D Tomographic Imaging

3D visualizations of the microstructure of flocculated particulates and sediments using optical confocal laser microscopy and high resolution X-ray microtomography methods are described. Data obtained from in situ measurements should enable direct computation of the properties of solids assembly (shape, size, contact area) and their permeability to fluids. A specific application relating to the formation of silica aggregates is described from which the behaviour of sediments containing these materials can be predicted on the basis of a bench-top test and the use of a Lattice Boltzmann simulation. It is proposed that the method can potentially be used to predict trends such as the filtration behaviour of porous structures under different states of compression. This offers a significant benefit in assisting the formulation design of flocculated materials pertinent to a number of industrial sectors wishing to design optimal filtration or relevant operations.

Distribution Characteristics of Constituent Particles in Thick Plate of 2024 AI-T351 / Verteilungscharakteristika von Einschlüssen in 2024 AI-T351 Grobblech

Constituent particles and precipitations in 2024 Al-T351 were analysed in order to investigate their spatial distribution characteristics using various methods that are optical microscopy (OM), scanning electron microscopy (SEM) and synchrotron-radiation based X-ray microtomography (XTM). The OM method provides quantitative or half-quantitative results of the size, distance and shape of the particles. The SEM method produces graded information on the particles and precipitations with wider magnification scales. XTM method provides a clear view of the spatial distribution of the coarse particles and particle clusters. It was found that the particle clusters form interfaces, which separate the material into disk-like matrix domains. The interfaces are expected to have a low mechanical strength, which promotes damage and fracture in the material.

Microstructure-dependent densification of polar firn derived from X-ray microtomography

AbstractThe densification of dry polar snow and firn results in a continuous increase of density with depth accompanied by significant density fluctuations within seasonal layers. Density measurements of high spatial resolution reveal a persistent minimum of density fluctuations in the vicinity of the snow–firn transition (0.55–0.65 g cm-3) in firn-core records. In this study we give an explanation for the fluctuation minimum by applying a new method of X-ray microtomography to obtain three-dimensional (3-D) structural data of a Greenland firn core. At 13 different depths between 10 and 78 m a set of 16 samples of 40 cm total length for each depth interval was measured. A reconstructed firn segment of 40 cm covers 1–2 years of snow accumulation. Using digital image analysis techniques, different structural parameters are estimated including 3-D pore and particle sizes and specific surface areas. It is shown that the densification rates of snow and firn layers consisting of coarse particles are much higher than those consisting of fine particles within the same depth interval. This causes a density crossing of fine- and coarse-grained layers with a minimum of density variations at the crossover point. This crossing-over implies that formerly dense layers in the seasonal density signal are not of the same origin as dense layers in the deeper part of the firn column and that the seasonal density signal will totally change shape with depth. It is speculated that in coarse- and fine-grained firn the dominant mechanism of densification acts over different regimes of density.

Submicrometer-resolution three-dimensional imaging with hard x-ray imaging microtomography

An x-ray microtomography method combined with hard x-ray imaging microscopy was developed that has a potential spatial resolution of the order of 10–100 nm. The system consists of a high-brilliance undulator source of SPring-8, a beam diffuser plate to reduce the coherence of the illumination, a high-precision rotating sample stage, a Fresnel zone plate objective, and a high-resolution x-ray imaging detector. The three-dimensional images of several samples were observed and successfully reconstructed with a pitch pattern of 0.6 μm.