Three-dimensional Characterization Research Articles

Three-dimensional visualization of dentine occlusion based on FIB-SEM tomography

The occlusion of dentinal tubules has become a rapid and effective method for treating dentin hypersensitivity. Accurate evaluation of dentin occlusion is critical to illustrate the efficacy of oral care products and to optimize dental therapy in the clinics, which is limited by the conventional two-dimensional (2-D) characterization methods. Here, we demonstrate the visualization of the dentin occlusion via three-dimensional (3-D) characterization using a focused ion beam-scanning electron microscopy (FIB-SEM) tomography. Using the “Slice and View” approach, the material used for occluding dentin tubules is imaged with a very high-resolution voxel (10 nm × 10 nm × 20 nm) from 2-D SEM images and then reconstructed into a 3-D volume, which presents the mode of action of toothpaste for treating dentin hypersensitivity. Meanwhile, quantitative analysis of the depth of occlusion is successfully obtained. This work validates the feasibility of FIB-SEM tomography in the analysis of dentin occlusion within the complicated networks of dentine tubules at the nanoscale, and provides a novel approach to facilitate the research and development of oral care products.

Three-dimensional characterization of karstic dissolution zones, fracture networks, and lithostratigraphic interfaces using GPR cubes, core logs, and petrophysics: Implications for thief zones development in carbonate reservoirs

Fractures and karstic dissolution features have been recognized to significantly affect subsurface fluid flow on a range of scales in carbonate rocks. However, due to the information gap between seismic and borehole scales, characterizing these features is a real challenge. We present a three-dimensional multidisciplinary approach to identify the main factors controlling the formation of connected rock volumes composed by permeable karstic dissolution zones. We investigate two outcrops in the Jandaíra Formation, which is an intensely fractured and karstified carbonate platform in the Potiguar Basin, Brazil. Two GPR cubes are jointly interpreted with cored boreholes, borehole images, petrophysical profiles, and thin sections. We verified that attenuated zones of GPR signal are related to secondary carbonate changes caused by fracturing and/or diagenetic alterations, leading to the development of relatively high secondary permeability. At least three types of attenuation/karstic zones might occur: fractured or broken zones affected by fracture enlargement due to dissolution, zones submitted to intense diagenetic alterations, and void spaces as a final end-member of these two processes. Fractures are preferential routes to fluid flow, thus contributing to increase dissolution processes, particularly in layers having relatively high values of primary matrix porosity and permeability. On the other hand, relevant diagenetic alterations might occur in layers that contain high concentration of stylolites. As a result of interconnecting dissolved stylolites, zones of relatively high secondary permeability can be created regardless of the primary values of matrix porosity and permeability. Geobodies of connected volumes of karstic zones often present tabular shapes and are delimited by subvertical fractures and subhorizontal lithostratigraphic interfaces. In the reservoir scale, these tabular geobodies might compose highly connected permeable volumes of altered carbonate rocks that constitute thief zones or super-K layers.

Microstructural characterisation and analysis of coarse aggregates in asphalt drill cores

The research presented in this paper is focused on the three-dimensional characterisation of coarse aggregates ( mm) within real asphalt structures. It is based on three-dimensional images acquired by micro X-ray Computed Tomography (μXRCT). A method to segment the aggregates from the other asphalt mixture components and each other, using these images is presented in detail. Subsequently, they are converted into basic data on the aggregate size, form, structure and orientation of every individual aggregate. On this database, fundamental and generally used parameters are calculated to characterise the aggregate properties. Finally, the parameters are evaluated regarding the aggregate form, angularity, location within the drill core and alignment of its main dimension. The results show that the segmentation method delivers quite precise results about the aggregates. The analysis of those basic parameters points out that the aggregates' positioning is evenly distributed but the orientation behaviour inside the structure is dependent on their shape characteristics.

Three-dimensional characterization and quantitative research of Malan loess microstructure under seismic loading

The deformation and failure of loess in areas of high seismic intensity are closely related to the dynamic vulnerability, which is primarily controlled by the loess microstructure. This study performed a series of dynamic triaxial tests and microstructure tests on intact loess to track and quantitatively characterize the evolution of the three-dimensional microstructure during deformation. The microstructural observations were performed using micro-CT on the samples after varying vibration times. The microstructure parameters (including pore radius, elongation, orientation, coordination number, pore throat area, and channel length) were obtained using a reconstructed pore network model. The results of this study demonstrated that the loess seismic subsidence originated from both compositional and microstructural characteristics. The intact loess had a loose structure with high porosity and limited cementation. Upon cyclic loading, cementation and contact breakdown led to the failure of the loess structure, followed by particle rearrangement. With increasing vibration times, the spaced and inter-aggregate pores became intra-aggregate pores, the pore throat size tended to decrease while the pore number tended to increase, the connectivity tended to weaken, and the shape tended to be long and flat. Pores >28 μm mainly provided spatial conditions for collapse deformation under seismic load. In addition, under the ultimate loading, large-volume cracks occurred inside the sample. The findings of this study provide further insights into loess seismic subsidence from the perspective of three-dimensional microstructures and a research basis for analyzing the stability of loess in relation to construction projects by combining finite and discrete elements.

Atomic layer deposition enables multi-modal three-dimensional electron microscopy of isoporous membranes.

Block copolymers (BCPs) are promising materials for water purification. They enable the fabrication of integral asymmetric isoporous membranes with high permeability and good selectivity. Commonly, the characterization of such hierarchical structures is performed by conventional electron microscopy (EM) means, namely scanning and transmission electron microscopy (SEM and TEM, respectively). However, due to the inherent lack of contrast between BCP domains, external contrast agents are required to achieve informative, high-resolution imaging. In addition, such EM techniques are typically limited to a certain cross-section or surface morphology only. In this paper, we harness the selective growth of AlOx in the pore-forming domains of BCPs to create an internal and stable contrast difference between the blocks. This in turn allowed us to perform advanced three-dimensional characterization of the membranes with focused ion beam (FIB)-SEM and TEM tomography, providing an understanding of the 3D structure and properties such as 3D geometry of the pores, 3D tortuosity, and 3D permeability. This 3D characterization also provides better correlations between the membrane structure and its performance. Such knowledge can allow better design and fine-tuning of BCP membranes and other membranes for their applications.

Deformation behavior of cell walls in an additively manufactured hybrid metallic foam

A hybrid Al-Al3Ni metallic foam was synthesized in-situ via directed energy deposition (DED) of Ni-coated Al 6061 powder, without the need for a foaming agent. Three-dimensional characterization via X-ray computed tomography shows that the foam contains approximately 61.5 % porosity and a high volume fraction of the Al3Ni phase (∼60 vol. %) within the cell walls. This microstructure is notably distinct from the eutectic structure that is typically observed in conventionally processed Al-Ni alloys. To investigate the mechanical properties and deformation mechanisms of the Al-Al3Ni cell walls, in-situ micro-pillar compression was performed, and the results reveal a notable yield strength of 560 MPa and a compressive strain that exceeds 30 %. These properties are attributable to the presence of a high volume fraction of Al3Ni particles, in combination with the characteristics of the Al/Al3Ni interfaces. To provide insight into the deformation mechanisms in the cell walls we used in-situ mechanical testing, transmission electron microscopy and precession electron diffraction characterization, together with molecular dynamics simulations. Our results reveal two distinct mechanisms: uniform dislocation-based deformation of the Al alloy phase and localized deformation within the slip bands in the Al3Ni phase. The results further highlight the importance of the Al/Al3Ni interfaces in mechanical strengthening and the transfer of plastic deformation from the Al phase to the Al3Ni phase. At high mechanical loads, cracks form due to the large stress concentration at the slip bands and slip band intersections in the Al3Ni, giving rise to intragranular fracture of Al3Ni and finally interfacial debonding and cracking.

Resolving the Subsurface Structure and Elastic Modulus of Layered Films via Contact Resonance Atomic Force Microscopy.

Since its discovery, atomic force microscopy (AFM) has become widely used for surface characterization, evolving from a tool for probing surface topography to a versatile method for characterizing mechanical, electrical, chemical, magnetic, and electro-optical properties of surfaces at the nanoscale. Developments of several AFM-based techniques have enabled even subsurface imaging, which is routinely being carried out at the qualitative level of feature detection for localized subsurface inhomogeneities. We surmise, however, that a quantitative three-dimensional (3D) subsurface characterization can emerge from the AFM mechanical response of flat buried interfaces, and present here a methodology for determining the depth of a film and its mechanical properties. Using load-dependent contact resonance atomic force microscopy (CR-AFM) and accurate modeling of the contact between the AFM tip and a layered sample, we determine the relationship between the measured resonance frequency of the AFM probe and the contact stiffness. Our subsequent statistical analysis reveals an intrinsic and sample-specific interdependence between the depth and modulus sensitivities of CR-AFM. This interdependence prevents the simultaneous accurate determination of both depth and modulus from measurements on a single-layered sample. If the elastic moduli of the sample components are predetermined from separate investigations of bulk samples (or otherwise known), then this methodology accurately yields the location of the interface between the layers of the sample; as such, it can serve as a nondestructive and robust technique for probing layer thickness, subsurface features, and elastic properties of materials used in semiconductor electronics, additive manufacturing, or biomaterials.

A Novel Technique for Producing Three-Dimensional Data Using Serial Sectioning and Semi-Automatic Image Classification.

The three-dimensional characterization of internal features, via metrics such as orientation, porosity, and connectivity, is important to a wide variety of scientific questions. Many spatial and morphological metrics only can be measured accurately through direct in situ three-dimensional observations of large (i.e., big enough to be statistically representative) volumes. For samples that lack material contrast between phases, serial grinding and imaging—which relies solely on color and textural characteristics to differentiate features—is a viable option for extracting such information. Here, we present the Grinding, Imaging, Reconstruction Instrument (GIRI), which automatically serially grinds and photographs centimeter-scale samples at micron resolution. Although the technique is destructive, GIRI produces an archival digital image stack. This digital image stack is run through a supervised machine-learning-based image processing technique that quickly and accurately segments data into predefined classes. These classified data then can be loaded into three-dimensional visualization software for measurement. We share three case studies to illustrate how GIRI can address questions with a significant morphological component for which two-dimensional or small-volume three-dimensional measurements are inadequate. The analyzed metrics include: the morphologies of objects and pores in a granular material, the bulk mineralogy of polyminerallic solids, and measurements of the internal angles and symmetry of crystals.

Abstract 13506: Three-Dimensional Transoesophageal Echocardiography Characterization of Left Atrial Appendage Dimensions in Patients With Spontaneous Cardioversion of Atrial Fibrillation

Introduction: Few studies have described the clinical profile and natural history of patients with spontaneous cardioversion (SpCV) in atrial fibrillation (AF). Hypothesis: We hypothesized that patients with SpCV have a distinct morphological pattern in AF. Methods: We prospectively evaluated 262 patients hospitalized for AF using two-dimensional (2D) transthoracic (TTE) and three-dimensional (3D) transoesophageal echocardiography (TEE). 3D parameters were off-line analysed using Tomtec software (4D Cardio-View, Philips). Patients were divided into two groups according to the cardiac rhythm within 24 hours after admission: spontaneous cardioversion (SpCV group, 59 patients) and non-spontaneous cardioversion (noSpCV group, 203 patients). Results: Mean age of the population was 66±12 years and 166 (63%) patients were male. SpCV group had in comparison with noSpCV group lower CRP levels (respectively 3.3(3-5.5) versus 4(3-10) mg/L, p=0.0394), lower BNP levels (151(67-200) versus 269(129-424) pg/mL, p<0.001) and lower HBA1c levels (5.5(5.3-5.7) versus 5.9(5.6-6.3) %, p<0.0001). Using 2D TTE, SpCV group had in comparison with noSpCV group lower indexed left atrial end-systolic volume, lower indexed right atrial end-systolic volume, lower E velocity, and higher left ventricle ejection fraction (Table 1). Based on 2D and 3D TEE, SpCv group had in comparison with noSpCV group higher LAA emptying flow velocity and higher LAA filling flow velocity, lower 3D end-systolic and end-diastolic LAA volumes (both non-indexed and indexed) and lower 3D LAA ostium in comparison with noSpCV group (Table 1). Conclusions: Although SpCv of AF is a frequent situation incompletely studied, clinical and echocardiographic characteristics could be described. Further investigations are needed to determine the impact of such abnormalities on the prognosis in the SpCV group.

Synaptic pruning through glial synapse engulfment upon motor learning.

Synaptic pruning is a fundamental process of neuronal circuit refinement in learning and memory. Accumulating evidence suggests that glia participates in sculpting the neuronal circuits through synapse engulfment. However, whether glial involvement in synaptic pruning has a role in memory formation remains elusive. Using newly developed phagocytosis reporter mice and three-dimensional ultrastructural characterization, we found that synaptic engulfment by cerebellar Bergmann glia (BG) frequently occurred upon cerebellum-dependent motor learning in mice. We observed increases in pre- and postsynaptic nibbling by BG along with a reduction in spine volume after learning. Pharmacological blockade of engulfment with Annexin V inhibited both the spine volume reduction and overnight improvement of motor adaptation. These results indicate that BG contribute to the refinement of the mature cerebellar cortical circuit through synaptic engulfment during motor learning.

Local Three-Dimensional Characterization of Nonlinear Grain Boundary Length within Bulk ZnO Using Nanorobot in SEM

Aiming at the problems of lack of data on the nonlinear morphology to divide uneven grain boundary in bulk ceramics, a unique approach of nanorobot-based characterization of three-dimensional nonlinear structure length can be creatively proposed under scanning electron microscope to quantify the actual morphology of local micro-area grain boundary in bulk ZnO. Contour shapes of the targeted grain boundaries in plane X-Y can be imaged using SEM. Z-directional relative height differences at different positions can be sequentially probed by nanorobot. Experiments demonstrate that it is effective to characterize three-dimensional length structures of nonlinear grain boundaries in bulk materials. By quantifying Z-directional relative height differences, it can be verified to show that irregular characteristics exist in three-dimensional grain boundary length, which can extend the depth effect on nonlinear bulk conductance. Furthermore, this method can also obtain nonlinear quantitative topographies to divide grain boundaries to uneven structure in the analysis of bulk polycrystalline materials.

Three-dimensional characterization of developing and adult ocular vasculature in mice using in toto clearing

The ocular vasculature is critically involved in many blinding diseases and is also a popular research model for the exploration of developmental and pathological angiogenesis. The development of ocular vessels is a complex, finely orchestrated sequence of events, involving spatial and temporal coordination of hyaloid, choroidal and retinal networks. Comprehensive studies of the tridimensional dynamics of microvascular remodeling are limited by the fact that preserving the spatial disposition of ocular vascular networks is cumbersome using classical histological procedures. Here, we demonstrate that light-sheet fluorescence microscopy (LFSM) of cleared mouse eyes followed by extensive virtual dissection offers a solution to this problem. To the best of our knowledge, this is the first 3D quantification of the evolution of the hyaloid vasculature and of post-occlusive venous remodeling together with the characterization of spatial distribution of various cell populations in ocular compartments, including the vitreous. These techniques will prove interesting to obtain other insights in scientific questions addressing organ-wide cell interactions.

Fine-Scale Three-Dimensional Characterization of a Reservoir Comprising Braided River Sand Bodies with a Complex Stacking Pattern in a Cratonic Basin

Abstract The complex stacking pattern of braided river sand bodies in the cratonic basins results in a multilevel and multistage spatial distribution of reservoir units, which increases the difficulty of characterizing the spatial distribution pattern of reservoir parameters. Therefore, when characterizing the spatial regularity of this type of reservoir, it is necessary to consider the stacking pattern of the sand bodies to select the constraints. In this paper, the He 8 section of the Sulige 120 area in the Ordos Basin, China, is taken as an example. First, based on analysis of the development scale and genetic type of sand bodies in the area, four sand body stacking patterns and plan-view distribution patterns are identified. Second, a study on how to improve the accuracy of braided river sand body models is carried out, and a sand body model is established. Finally, a three-dimensional model of reservoir properties is established by using the sequential Gaussian simulation method under the constraint of the phase control model. The model results show that the three-dimensional model of the sand bodies established by the multipoint geostatistical method has better connectivity and is more suitable for constructing sand body models under complex sand body stacking conditions. The training images established by the target body method can clearly identify the boundary of the main channel of the braided river and solve the discontinuity of the sand body distribution. The reservoir model established under the constraint of the sand body model can effectively simulate the nonhomogeneity in the reservoir parameters, which can play a crucial role in accurately predicting the porosity and permeability distribution patterns of reservoirs with complex sand body stacking pattern. The present study provides a new idea for characterizing complexly stacked sand body reservoirs in a cratonic basin.

Towards three-dimensional characterization of hypervelocity impact events using ultrahigh-speed digital holography

This experimental study reports the development and use of high-speed and ultrahigh-speed digital holography (DH) systems to perform three-dimensional (3D) characterization of particle-fields created from the impact of a supersonic projectile with a target plate. Different target materials including clay and gypsum were tested producing a cloud of ejecta particles from the impact zone. While the megahertz-rate ultrahigh-speed DH instrument version was used for measurements in early (0-250 µs) time-scale processes, the 100 kilohertz-rate high-speed version was employed to interrogate extended (250 µs-1 s) durations following impact. By capturing holograms and performing wavefront reconstruction at different depths, holography allows scanning through the 3D space plane-by-plane at given moment in time, allowing the user to focus on different objects to determine their shape and precise 3D location. We automate this particle detection procedure in sequential holograms by using a minimum intensity focusing criterion and obtain their locations in three-dimensional space with respect to time. Further, we track particles over these durations to determine their trajectories along with instantaneous and mean velocities. Based on the optical configuration and field-of-view employed both instruments were able characterize the ejecta clouds for particle size distributions ranging 1 µm-1 mm. The results presented clearly demonstrate the applicability of digital holography for 3D characterization of ejecta and debris clouds arising from the impact of supersonic and hypersonic projectile with different material targets.

Fused x-ray and fast neutron CT reconstruction for imaging large and dense objects

Megavolt x-ray computed tomography (CT) is a powerful tool for three-dimensional characterization. However, its utility is limited for large objects composed of high-atomic number (Z) materials, where x rays fail to penetrate. Information from fast neutron CT (FNCT) can complement x-ray CT reconstructions since fast neutrons can more readily penetrate high-Z objects. Here, we demonstrate a method for combining FNCT and x-ray CT data to create a single reconstruction, more accurate than could be achieved with either x rays or fast neutrons alone. The algorithm was tested on an exemplar comprising multiple concentric, nested cylinders of different materials. Simulated and empirical x-ray CT data were acquired for the exemplar using a 9 MV bremsstrahlung spectrum. Additional simulated and empirical FNCT data were acquired using an accelerator based fast neutron source. The FNCT data were used to synthesize x-ray CT data and augment the x-ray CT data missing due to lack of penetration. This approach mitigates artifacts that would otherwise negatively affect the accuracy and resolution of a single-modality reconstructed volume.

Three-dimensional mechanical characterization of murine skeletal muscle using quantitative micro-elastography.

Skeletal muscle function is governed by both the mechanical and structural properties of its constituent tissues, which are both modified by disease. Characterizing the mechanical properties of skeletal muscle tissue at an intermediate scale, i.e., between that of cells and organs, can provide insight into diseases such as muscular dystrophies. In this study, we use quantitative micro-elastography (QME) to characterize the micro-scale elasticity of ex vivo murine skeletal muscle in three-dimensions in whole muscles. To address the challenge of achieving high QME image quality with samples featuring uneven surfaces and geometry, we encapsulate the muscles in transparent hydrogels with flat surfaces. Using this method, we study aging and disease in quadriceps tissue by comparing normal wild-type (C57BL/6J) mice with dysferlin-deficient BLAJ mice, a model for the muscular dystrophy dysferlinopathy, at 3, 10, and 24 months of age (sample size of three per group). We observe a 77% decrease in elasticity at 24 months in dysferlin-deficient quadriceps compared to wild-type quadriceps.

Three-dimensional Characterisation of Microstructures in Low-carbon Lath Martensite

Three-dimensional Characterisation of Microstructures in Low-carbon Lath Martensite

Radiographic Study Evaluating Perforator Vessels in the Ischiorectal Fossa for Safe Elevation of Island Flaps.

Background:Perforator flaps based on the ischiorectal fossa (IRF) (ie, internal pudendal artery perforator flaps) are useful for perineal reconstruction. The three-dimensional characterization of perforator arteries in the IRF remains unclear, as the IRF contains thick adipose tissue as well as organs, such as the rectum, vagina, and urethra. This study aimed to evaluate perforators in the IRF to guide the safe elevation of skin flaps designed based on the IRF.Methods:IRF vessels were examined in 200 bilateral computed tomography angiography scans performed in 100 patients. We examined branching patterns arising from the internal iliac artery and the origins of the skin perforators in the IRF.Results:The branching patterns of the internal iliac artery were divided into three groups: perforators derived exclusively from the internal pudendal artery (78%), perforators derived from the internal pudendal artery and the inferior gluteal artery (18%), and perforators derived exclusively from the inferior gluteal artery (4%). The average number of perforators in the IRF was 1.5 ± 0.7. The number of perforators was significantly higher in women than in men. The perforator arteries were found exclusively around the medial and dorsal sides of the ischial tuberosity.Conclusions:We found that perforators in the IRF were stable. All cases had more than one skin perforator, which was mainly derived from the internal pudendal artery. Although perforators cannot be identified during flap elevation because the fatty tissue in the IRF is very thick, physicians must focus on preserving the perforator-containing fatty tissue around the ischial tuberosity.

Three-dimensional microstructural characterization of FBR MOX fuel and the contribution of microstructural features to the thermal conductivity of the fuel

Combination of microstructural characterization, property measurements, and phase field modeling is used to investigate fast breeder reactor (FBR) mixed oxide (MOX) fuel irradiated to burnup of 13.7% fissions per initial metal atom (FIMA). The fuel was characterized at different radial locations, which revealed that grey phase can be present in the central region if it nucleates on five metal precipitates (FMPs). In addition, in the mid-radial region FMPs do not diffuse out of the region once formed and the size of Pd–Te precipitates is dictated by the porosity present in the region. Thermal conductivity measurements (TCM) were conducted as a function of radial location and the microstructure of the fuel was correlated with the observed trend. Reconstructions of the 3D solid and gaseous fission product structures in different regions of the fuel were used to simulate the effective thermal conductivity (ETC) of the respective regions and determine which microstructural feature has the strongest impact on thermal conductivity. Based on conducted assessment, FMPs and Pd-Te precipitates improve local conductivity of central and mid-radial regions even in the presence of grey phase, but defects are primary contributor to the degradation of thermal conductivity on the periphery of the fuel.

A Primary-Auxiliary Coupled Neural Network for Three-Dimensional Holographic Particle Field Characterization

Particle field measurement is an important topic in many industrial branches. However, there are always complex imaging scenes in the engineering experiments, resulting in severe imaging artifact, noise, and blur, such as the optical holography. In this article, we propose a primary-auxiliary coupled neural network (PANet) for 3-D holographic particle field characterization, which can obtain a comprehensive particle measurement, including the identification, focus determination, segmentation, and size estimation. PANet is constituted by two subnets that are arranged in a coupled architecture, i.e., a Primary-Net (PNet) and an AuxiliaryNet (ANet). As the main frame, PNet is designed to accomplish the detection of most particles, while ANet aims to detect the tiny particles that PNet cannot identify. We exploit an alternative training method to realize their functional differentiation and complementation. PANet is evaluated on two kinds of holographic particle field data, i.e., high-energy laser shock aluminum target and droplet breakup in high Mach shock wave. By means of semisupervised learning and a specific loss function, the effect of deficient particle labeling can be alleviated. Experimental results demonstrate that PANet can achieve excellent performance in particle field characterization, especially for those with a wide size span and complex image background.