nano-CT Imaging Research Articles

The Impact of Temperature and the Duration of Freezing on a Hydrogel Used for a 3D-Bioprinted In Vitro Skin Model.

Skin bioprinting has the potential to revolutionize treatment approaches for injuries and surgical procedures, while also providing a valuable platform for assessing and screening cosmetic and pharmaceutical products. This technology offers key advantages, including flexibility and reproducibility, which enable the creation of complex, multilayered scaffolds that closely mimic the intricate microenvironment of native skin tissue. The development of an ideal hydrogel is critical for the successful bioprinting of these scaffolds with incorporated cells. In this study, we used a hydrogel formulation developed in our laboratory to fabricate a 3D-bioprinted skin model. The hydrogel composition was carefully selected based on its high compatibility with human skin cells, incorporating alginate, methyl cellulose, and nanofibrillated cellulose. One of the critical challenges in this process, particularly for its commercialization and large-scale production, is ensuring consistency with minimal batch-to-batch variations. To address this, we explored methods with which to preserve the physicochemical properties of the hydrogels, with a focus on freezing techniques. We validated the pre-frozen hydrogels' printability, rheology, and mechanical and surface properties. Our results revealed that extended freezing times significantly reduced the viscosity of the formulations due to ice crystal formation, leading to a redistribution of the polymer chains. This reduction in viscosity resulted in a more challenging extrusion and increased macro- and microporosity of the hydrogels, as confirmed by nanoCT imaging. The increased porosity led to greater water uptake, swelling, compromised scaffold integrity, and altered degradation kinetics. The insights gained from this study lay a solid foundation for advancing the development of an in vitro skin model with promising applications in preclinical and clinical research.

Quantitative Three-Dimensional Imaging Analysis of HfO2 Nanoparticles in Single Cells via Deep Learning Aided X-ray Nano-Computed Tomography.

It is crucial for understanding mechanisms of drug action to quantify the three-dimensional (3D) drug distribution within a single cell at nanoscale resolution. Yet it remains a great challenge due to limited lateral resolution, detection sensitivities, and reconstruction problems. The preferable method is using X-ray nano-computed tomography (Nano-CT) to observe and analyze drug distribution within cells, but it is time-consuming, requiring specialized expertise, and often subjective, particularly with ultrasmall metal nanoparticles (NPs). Furthermore, the accuracy of batch data analysis through conventional processing methods remains uncertain. In this study, we used radioenhancer ultrasmall HfO2 nanoparticles as a model to develop a modular and automated deep learning aided Nano-CT method for the localization quantitative analysis of ultrasmall metal NPs uptake in cancer cells. We have established an ultrasmall objects segmentation method for 3D Nano-CT images in single cells, which can highly sensitively analyze minute NPs and even ultrasmall NPs in single cells. We also constructed a localization quantitative analysis method, which may accurately segment the intracellularly bioavailable particles from those of the extracellular space and intracellular components and NPs. The high bioavailability of HfO2 NPs in tumor cells from deeper penetration in tumor tissue and higher tumor intracellular uptake provide mechanistic insight into HfO2 NPs as advanced radioenhancers in the combination of quantitative subcellular image analysis with the therapeutic effects of NPs on 3D tumor spheroids and breast cancer. Our findings unveil the substantial uptake rate and subcellular quantification of HfO2 NPs by the human breast cancer cell line (MCF-7). This revelation explicates the notable efficacy and safety profile of HfO2 NPs in tumor treatment. These findings demonstrate that this 3D imaging technique promoted by the deep learning algorithm has the potential to provide localization quantitative information about the 3D distributions of specific molecules at the nanoscale level. This study provides an approach for exploring the subcellular quantitative analysis of NPs in single cells, offering a valuable quantitative imaging tool for minute amounts or ultrasmall NPs.

Experimental Study and Mechanism Analysis of Paraffin/Sisal Composite Phase Change Energy Storage Fiber Prepared by Vacuum Adsorption Method.

Sisal fiber exhibits a fibrous and porous structure with significant surface roughness, making it highly suitable for storing phase change materials (PCMs). Its intricate morphology further aids in mitigating the risk of PCM leakage. This research successfully employs vacuum adsorption to encapsulate paraffin within sisal fiber, yielding a potentially cost-effective, durable, and environmentally friendly phase change energy storage medium. A systematic investigation was carried out to evaluate the effects of sisal-to-paraffin mass ratio, fiber length, vacuum level, and negative pressure duration on the loading rate of paraffin. The experimental results demonstrate that a paraffin loading rate of 8 wt% can be achieved by subjecting a 3 mm sisal fiber to vacuum adsorption with 16 wt% paraffin for 1 h at -0.1 MPa. Through the utilization of nano-CT imaging enhancement technology, along with petrographic microscopy, this study elucidates the mechanism underlying paraffin storage within sisal fiber during vacuum adsorption. The observations reveal that a substantial portion of paraffin is primarily stored within the pores of the fiber, while a smaller quantity is firmly adsorbed onto its surface, thus yielding a durable phase change energy storage medium. The research findings contribute to both the theoretical foundations and the available practical guidance for the fabrication and implementation of paraffin/sisal fiber composite phase change energy storage mediums.

Associations Among Hip Structure, Bone Mineral Density, and Strength Vary With External Bone Size in White Women.

Bone mineral density (BMD) is heavily relied upon to reflect structural changes affecting hip strength and fracture risk. Strong correlations between BMD and strength are needed to provide confidence that structural changes are reflected in BMD and, in turn, strength. This study investigated how variation in bone structure gives rise to variation in BMD and strength and tested whether these associations differ with external bone size. Cadaveric proximal femurs (n= 30, White women, 36-89+ years) were imaged using nanocomputed tomography (nano-CT) and loaded in a sideways fall configuration to assess bone strength and brittleness. Bone voxels within the nano-CT images were projected onto a plane to create pseudo dual-energy X-ray absorptiometry (pseudo-DXA) images consistent with a clinical DXA scan. A validation study using 19 samples confirmed pseudo-DXA measures correlated significantly with those measured from a commercially available DXA system, including bone mineral content (BMC) (R 2 = 0.95), area (R 2 = 0.58), and BMD (R 2 = 0.92). BMD-strength associations were conducted using multivariate linear regression analyses with the samples divided into narrow and wide groups by pseudo-DXA area. Nearly 80% of the variation in strength was explained by age, body weight, and pseudo-DXA BMD for the narrow subgroup. Including additional structural or density distribution information in regression models only modestly improved the correlations. In contrast, age, body weight, and pseudo-DXA BMD explained only half of the variation in strength for the wide subgroup. Including bone density distribution or structural details did not improve the correlations, but including post-yield deflection (PYD), a measure of bone material brittleness, did increase the coefficient of determination to more than 70% for the wide subgroup. This outcome suggested material level effects play an important role in the strength of wide femoral necks. Thus, the associations among structure, BMD, and strength differed with external bone size, providing evidence that structure-function relationships may be improved by judiciously sorting study cohorts into subgroups. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

How does nano-focus computed tomography impact the quantification of debris within the root canal system?

The aim of this study was to compare the quantification of hard-tissue debris by using micro-computed tomography (micro-CT) and nano-focus computed tomography (nano-CT) after root canal instrumentation. Ten mandibular molars containing an isthmus in the mesial root were scanned in a SkyScan 1172 micro-CT device with a voxel size of 12.8 µm and in a NanoTom nano-CT device with 5.5 µm. The mesial root canals were irrigated with 5 mL of saline solution at the orifice level, instrumented with Reciproc R25 files and a second scanning was performed by micro-CT and nano-CT devices for post-instrumentation images. DataViewer software was used for registering the pre- and post-operative micro-CT and nano-CT images. The root canal and the debris were segmented for quantitative analysis of the volume of the canal and volume of debris using CTAn software. Statistical analysis was performed using the T test for comparison between volume of the canal after instrumentation and volume of debris in both image modalities. The level of significance was set at p < 0.05. Nano-CT images showed higher values of debris when compared with micro-CT (p < 0.05) after root canal instrumentation. No difference was observed between the volume of the root canal after instrumentation in the two imaging methods used (p > 0.05). Nano-CT technology can be recommended as a more precise method for quantitative analysis of hard-tissue debris. Moreover, in Endodontic research it is a promising method, as it is capable of providing higher spatial and contrast resolution, faster scanning and higher image quality.

Deep Learning-Based BoVW–CRNN Model for Lung Tumor Detection in Nano-Segmented CT Images

One of the most common oncologies analyzed among people worldwide is lung malignancy. Early detection of lung malignancy helps find a suitable treatment for saving human lives. Due to its high resolution, greater transparency, and low noise and distortions, Computed Tomography (CT) images are most commonly used for processing. In this context, this research work mainly focused on the multifaceted nature of lung cancer diagnosis, a quintessential, fascinating, and risky subject of oncology. The input used here has been nano-image, enhanced with a Gabor filter and modified color-based histogram equalization. Then, the image of lung cancer was segmented by using the Guaranteed Convergence Particle Swarm Optimization (GCPSO) algorithm. A graphical user interface nano-measuring tool was designed to classify the tumor region. The Bag of Visual Words (BoVW) and a Convolutional Recurrent Neural Network (CRNN) were employed for image classification and feature extraction processes. In terms of findings, we achieved the average precision of 96.5%, accuracy of 99.35%, sensitivity of 97%, specificity of 99% and F1 score of 95.5%. With the proposed solution, the overall time required for the segmentation of images was much smaller than the existing solutions. It is also remarkable that biocompatible-based nanotechnology was developed to distinguish the malignancy region on a nanometer scale and has to be evaluated automatically. That novel method succeeds in producing a proficient, robust, and precise segmentation of lesions in nano-CT images.

The Development of the Chimaeroid Pelvic Skeleton and the Evolution of Chondrichthyan Pelvic Fins.

Pelvic girdles, fins and claspers are evolutionary novelties first recorded in jawed vertebrates. Over the course of the evolution of chondrichthyans (cartilaginous fish) two trends in the morphology of the pelvic skeleton have been suggested to have occurred. These evolutionary shifts involved both an enlargement of the metapterygium (basipterygium) and a transition of fin radial articulation from the pelvic girdle to the metapterygium. To determine how these changes in morphology have occurred it is essential to understand the development of extant taxa as this can indicate potential developmental mechanisms that may have been responsible for these changes. The study of the morphology of the appendicular skeleton across development in chondrichthyans is almost entirely restricted to the historical literature with little contemporary research. Here, we have examined the morphology and development of the pelvic skeleton of a holocephalan chondrichthyan, the elephant shark (Callorhinchus milii), through a combination of dissections, histology, and nanoCT imaging and redescribed the pelvic skeleton of Cladoselache kepleri (NHMUK PV P 9269), a stem holocephalan. To put our findings in their evolutionary context we compare them with the fossil record of chondrichthyans and the literature on pelvic development in elasmobranchs from the late 19th century. Our findings demonstrate that the pelvic skeleton of C. milii initially forms as a single mesenchymal condensation, consisting of the pelvic girdle and a series of fin rays, which fuse to form the basipterygium. The girdle and fin skeleton subsequently segment into distinct components whilst chondrifying. This confirms descriptions of the early pelvic development in Scyliorhinid sharks from the historical literature and suggests that chimaeras and elasmobranchs share common developmental patterns in their pelvic anatomy. Alterations in the location and degree of radial fusion during early development may be the mechanism responsible for changes in pelvic fin morphology over the course of the evolution of both elasmobranchs and holocephalans, which appears to be an example of parallel evolution.

Triple-Phase Pore Network for Oxygen and Proton Transport Model in the Cathode Catalyst Layer of Proton Exchange Membrane Fuel Cells

Improvement in the mass transport overpotentials of the oxygen reduction reaction provides a pathway for reducing the high cost associated to platinum group metal loading as well as enhancing the lifetime of electrodes in proton exchange membrane fuel cells (PEMFCs). State-of-the-art PEMFCs typically have Pt loadings of the order of 0.3 mgPtcm-2, which is the main part of the estimated stack cost of $55/kW. Understanding transport phenomena at triple phase boundaries that consist of a (solid) electrocatalyst, ionomer, and (gas-phase) oxygen, where the electrochemical reactions occur has gained importance to improve electrocatalyst accessibility. Mathematical models that address transport of electrons, protons, and oxygen in the cathode is critical for an effective catalyst layer design. Modeling of this multiphysics phenomena is further complicated due to multiscale effects. Pore network model (PNM) is a promising technique to tackle these challenges because of its capability of resolving porous networks locally in greater detail. Moreover, improvements in microscopic imaging techniques (e.g., SEM, TEM, and nano CT) enable the generation of realistic pore networks of the catalyst layers that can be directly integrated into PNM. Most modeling studies to date focus on single networks for oxygen transport in the open pore space, or transport of oxygen and water. A pore network that describes oxygen, proton, and electron transport simultaneously remains uncharted. Here, we construct a triple-phase pore network model using nano CT images of heterogeneous porous catalyst layers. Binary images of solid-open pore space and ionomer-catalyst support are generated, which are then overlapped to create ternary images. Pores and throats are then fit to theseimages to create pore-networks that describe open-pores for oxygen and water transport, ionomer pores for proton transport, and a solid network for electron transport. A schematic of the approach is shown in Figure 1.The study offers a new method that constructs a triple pore network for a porous material in which two levels of open space porosity (micro and macro) exist in connection with solid and ionomer networks. Therefore, arealistic pore network is obtained to be further modeled through the approach presented. Figure 1

Vascular Supply to the Proximal Plantar Plate of Lesser Toe Metatarsophalangeal Joint is Primarily Supplied by the Attachment to the Metatarsal: A Nano-CT Microvasculature Study

Category: Lesser Toes Introduction/Purpose: Lesser toe metatarsophalangeal (MTP) instability is implicated in common forefoot pain and deformities. The plantar plate is a major stabilizing structure of the MTP joint with instability frequently occurring after a tear or attenuation of this structure. Previous studies have demonstrated that the blood supply to the proximal plantar plate comes from both the metatarsal and the plantar fascia. Commonly, a McGlamry elevator is used to strip the plantar plate from the plantar surface of the metatarsal to improve exposure of the MTP joint. The vascular consequence of stripping the plantar plate from the metatarsal is not yet well understood. The purpose of this study is to quantify the relative contribution of blood supply to the proximal plantar plate from the metatarsal and plantar fascia. Methods: Twelve fresh-frozen human adult cadaver lower extremity specimens were utilized for this study, resulting in 35 lesser MTP joints that were studied. All specimens were between the ages of 18 and 65 years and had no history of diabetes, peripheral vascular disease, or connective tissue disorders. Specimens with a history of trauma to the foot or ankle, prior foot or ankle surgery, or evidence of clinical deformity of less toes upon inspection were excluded. The specimens were prepared as described previously in Finney et al. The anterior and posterior tibial arteries were perfused with a barium solution and counterstained with phosphomolybdic acid. The second through fourth MTP joints of 12 feet were imaged with nano-computed tomography (nano- CT) at 14-micron resolution. Reconstructed 3D and 2D CT images were utilized for analysis of the volume of vasculature along the metatarsal pedicle and plantar fascia of the proximal plantar plate. Results: Based on nano-CT imaging, the plantar plate specimen demonstrated microvascular infiltration at the proximal attachments of the metatarsal neck, interosseous muscles, periosteum, and plantar fascia (Figure 1). An average of 63.5% of the vascular supply to the proximal portion of the plantar plate entered from the metatarsal pedicle in 35 lesser toe specimens analyzed. The remaining 36.5% of the vascular supply entered from the plantar fascia. The second toes, third toes, and fourth toes had an average of 64.7%, 59.0%, and 67.1% of vasculature supply from the metatarsal pedicle, respectively. The average volume of vasculature from the metatarsal pedicle to the proximal plantar plate was 0.38 mm3, while the average volume of vasculature from the plantar fascia to the proximal plantar plate was 0.19 mm3. Conclusion: The vascular supply of the proximal plantar plate is supplied from both the metatarsal pedicle and plantar fascia. Using the McGlamry elevator for exposure of the MTP joint disrupts the dominant tributary for proximal plantar plate perfusion.

Influence of working length and anatomical complexities on the apical root canal filling: a nano-CT study.

The present study aimed to compare the filled volume by gutta-percha and sealer in the apical region of the main canal and ramifications, after instrumentation at two different working lengths using nano-computed tomography (nano-CT). Twenty-two premolars with apical ramifications were selected after micro-computed tomography evaluation and were randomly divided into groups for further endodontic instrumentation at two different working lengths: G1 - Root canals shaped 1 mm short of the apical foramen (n=11), and G2 - Root canals shaped at the apical foramen (n=11). After completing root treatment, nano-CT images were acquired, and the filled volume by gutta-percha and sealer in the main canal apical 0-4 mm and 0-1 mm ranges, and apical ramifications were objectively measured by an operator specialized in both radiology and endodontics, blinded for both groups. The Mann-Whitney test was applied to compare both groups regarding the filling of the main canal apical ranges and apical ramifications with a significance level of 5% (α ≤ 0.05). It was observed that root canals shaped at the apical foramen had a larger volume of the main canal filled than root canals shaped 1 mm short of the apical foramen, at both apical ranges (0-4 and 0-1 mm) (p<0.05). Regarding the filling of the apical ramifications, there was no significant difference between groups (p>0.05). In conclusion, the root canals shaped at apical foramen exhibited increased filling volume of the main canal in the apical region. However, neither of both working lengths influenced filling of the apical ramifications.

Effect of process variables on in vitro characteristics of clindamycin phosphate loaded PLGA nanoparticles in dental bone regeneration and 3D characterization studies using nano-CT

Bone tissue surrounding the teeth may be lost due to traumatic, pathological, or physiological reasons, which can result in tooth loss. Therefore, studies in the field of dental surgery have focused on preventing bone loss around the teeth as well as bone regeneration. In the present work, clindamycin phosphate loaded polymeric nanoparticles were developed as a local drug delivery system to promote alveolar bone regeneration. The effects of PVA concentration, drug/polymer ratio, inner phase content, polymer type, and pH of the external water phase on the characterization of nanoparticles were investigated by determining the encapsulation efficiency, particle size and size distribution, surface morphology, 3D structure, drug release, and release kinetics of formulations. Encapsulation efficiency was highly dependent on PVA concentration and pH of the external water phase. The mean particle size decreased with the decrease in molecular weight of PLGA. Although using clindamycin phosphate, a water soluble drug, sustained release was achieved for up to 3 months for all formulations. This study revealed that nano-CT visualization is critical in explaining the effects of process parameters on the characterization of nanoparticles. With the 3D images obtained through nano-CT, the internal and external structural properties of the nanoparticles were obtained both visually and quantitatively. The findings of nano-CT imaging that simultaneously determine the 3D structure, size, volume and porosity of nanoparticles were promising for further studies unlike SEM. The differences of internal structural properties between the nanoparticles prepared using PCL and PLGA, which could not be distinguished using SEM images, were revealed through nano-CT imagery. Thus, thanks to the 2D and 3D images obtained by nano-CT, it was determined that densely capsular nanoparticles were formed using PCL, and nanoparticles in a matrix structure were formed with PLGA. In addition, the use of nano-CT scanning was particularly effective in interpreting the dissolution rate. Imaging the internal structures of the nanoparticles gave interpretable results in the formulation choices made in this study.

Dual U-Net based feature map algorithm for automatic projection alignment of synchrotron nano-CT

Synchrotron radiation-based nano-CT is a non-destructive imaging technique used to study the internal structure of matter. The efficient and automatic correction of errors in nano-CT imaging has proven challenging. Accordingly, different projection alignment techniques have been employed to address these issues. However, these techniques have their limitations. Herein, we propose a novel error correction model, a U-Net, that combines an experimentally informed mathematical model, optimized deep learning algorithm, and efficient projection matching model. The results show that the generation of feature maps based on our model is effective for improving the quality of 3D reconstructions while remaining highly robust. We further propose an optimized feature map generation method, a dual U-Net. Applying it yields an almost negligible alignment error rate for low random error-shift nano-CT data and a stable decrease in errors of one order of magnitude for high random error-shift nano-CT data. This study demonstrates the feasibility of the proposed feature map replacement projection alignment method, which may prove crucial to maximizing the efficiency and generalization of automatic projection alignment tasks.

Nano Tomography of High Voltage Induced First Cycle Cracking in NMC811

Lithium nickel-manganese-cobalt (NMC) oxide-based Li-ion batteries have emerged as the most promising successor to LiCoO2 chemistry and could potentially facilitate ubiquitous adoption of Li-ion in mobile and transport systems. High specific capacities, high-rate capability, and long-term cycling abilities are driving much research into these cathode materials, forcing a greater nickel content with each iteration. NMC811’s high specific capacity makes it highly attractive for battery suppliers and users; however, it suffers significant capacity fade via several degradation modes, one being crack formation within secondary particles. The fresh surface exposed by cracking has been linked with parasitic reactions that evolve oxygen and potentially initiate the formation of inactive crystal structures. [1]X-ray computed tomography (CT) has been utilised extensively to image the morphology of battery particles and with the advancement of lab-based tomography systems, resolution on the nano scale is readily available.[2] Whilst in-situ studies are becoming the standard experimental operation for appraising the dynamic nature of these materials, in-situ cells are complicated for use in lab-based instruments due to their low flux, low energy and reduced working space. Thus, nano tomography rarely provides information that deconvolutes chemo-mechanical cracking from manufacturing defects and calendaring. However, in this work we have developed a unique technique to follow the progression of cracking at the nanometre scale by sequential correlated imaging of a micro-sized tab cut from the electrode.[3,4] This method allows for images of the pristine material to be acquired ex-situ before electrochemical testing, and then sequential imaging of the same region of interest in subsequent scans. Here, nano-CT imaging of the same region of the electrode while fully-lithiated and charged to 4.5 V unveils the propagation of cracks as a function of voltage, and their relaxation phenomena upon discharge.[1] Li, Tianyu, Xiao-Zi Yuan, Lei Zhang, Datong Song, Kaiyuan Shi, and Christina Bock. "Degradation mechanisms and mitigation strategies of nickel-rich NMC-based lithium-ion batteries." Electrochemical Energy Reviews 3, no. 1 (2020): 43-80.[2] Heenan, Thomas MM, Chun Tan, Jennifer Hack, Dan JL Brett, and Paul R. Shearing. "Developments in X-ray tomography characterization for electrochemical devices." Materials Today 31 (2019): 69-85[3] Tan, C., S. Daemi, T. Heenan, F. Iacoviello, A. S. Leach, L. Rasha, R. Jervis, D. J. L. Brett, and P. R. Shearing. "Rapid preparation of geometrically optimal battery electrode samples for nano scale X-ray characterisation." Journal of The Electrochemical Society 167, no. 6 (2020): 060512.[4] Tan, Chun, Andrew S. Leach, Thomas MM Heenan, Huw Parks, Rhodri Jervis, Johanna Nelson Weker, Daniel JL Brett, and Paul R. Shearing. "Nanoscale state-of-charge heterogeneities within polycrystalline nickel-rich layered oxide cathode materials." Cell Reports Physical Science (2021): 100647. Figure 1

Characterization of electrically stressed power device metallization using nano-CT imaging

Power devices for automotive products are exposed to higher temperatures, currents, and voltages than common semiconductors. These devices are subject to large variations in the nominal power supply voltage. Power-Temperature Cycling (PTC) is an important reliability stress for power semiconductor devices, which addresses these specific load scenarios. It is known that PTC fails especially occur in the metallization of these power devices. Recent nano-CT imaging methods provide high-resolution 3D measurements on the relevant size scale suitable to spatially analyze these faults in detail. In this work, we demonstrate the suitability of the investigation method based on the study of various via-chain test structures previously stressed in the PTC and visually show the various defects that occurred in the process.

Evaluation of imaging setups for quantitative phase contrast nanoCT of mineralized biomaterials.

X-ray nano-tomography with phase contrast (nanoCT) using synchrotron radiation is a powerful tool to non-destructively investigate 3D material properties at the nanoscale. In large bone lesions, such as severe bone fractures, bone cancer or other diseases, bone grafts substituting the lost bone might be necessary. Such grafts can be of biological origin or be composed of a synthetic bone substitute. The long-term functioning of artificial bone substitutes depends on many factors. Synchrotron nanoCT imaging has great potential to contribute to further the understanding of integration of implants into bone tissue by imaging the spatial interaction between bone tissue and implant, and by accessing the interface between implant material and bone tissue. With this aim, a methodology for evaluating the image quality is presented for in-line phase contrast nanoCT images of bone scaffold samples. A PMMA-embedded tricalcium phosphate scaffold was used with both a closed and an open porosity structure and bone ingrowths as a representative system of three known materials. Parameters such as spatial resolution and signal-to-noise ratio were extracted and used to explore and quantitatively compare the effects of implementation choices in the imaging setup, such as camera technology and imaging energy, on the resulting image quality. Increasing the X-ray energy from 17.5 keV to 29.6 keV leads to a notable improvement in image quality regardless of the camera technology used, with the two tested camera setups performing at a comparable level when the recorded intensity was kept constant.

Optimization of composite bone scaffolds prepared by a new modified foam replica technique

This study aimed to demonstrate the application of the recently developed modified polyurethane (PU) foam replica technique in the fabrication of the hydroxyapatite (HA)/alumina (Al2O3) composite bone scaffolds with different volume fraction quantities of the alumina. Furthermore, the optimum values of porosity and volume fraction of the alumina were obtained in order to achieve an ideal scaffold suitable for repairing the damaged cancellous bone tissues existent in different anatomical locations of the body. Introducing a specific ageing process, samples with excellent properties suitable for bone fracture healing were produced in this study. 20 different groups of the scaffolds, each one comprising 20 samples, which included specimens with different porosities and compositions, were synthesized and characterized regarding morphology, composition, porosity, and mechanical properties. The field emission scanning electron microscopy (FESEM) and nano-computed tomography (nano-CT) images of the samples demonstrated that the scaffolds with high value of porosity and interconnectivity between the pores were achieved via the proposed scheme. According to the findings, although the overall trend of the variation in the viscosity of different HA/Al2O3 slurry compositions during the ageing process were the same, their ageing time was different. Besides, depending on the volume fraction of the alumina and the porosity of the foams used in synthesis of the samples, the values of the porosity and the compressive strength of the scaffolds were varied from 55.72% to 84.76% and 1.67–7.13 MPa, respectively, which are good for bone tissue engineering applications. Moreover, the results obtained from the optimization process revealed that the scaffolds with the respective values of the porosity and the alumina volume fraction of 84.76% and 0% for lumbar spine, 62.83% and 6.57% for proximal tibia, 56.16% and 9.33% for proximal femoral, and 55.72% and 9.8% for femur are the best choices for healing the corresponding injured spongy bone tissues.

Artificial neural network approach for multiphase segmentation of battery electrode nano-CT images

The segmentation of tomographic images of the battery electrode is a crucial processing step, which will have an additional impact on the results of material characterization and electrochemical simulation. However, manually labeling X-ray CT images (XCT) is time-consuming, and these XCT images are generally difficult to segment with histographical methods. We propose a deep learning approach with an asymmetrical depth encode-decoder convolutional neural network (CNN) for real-world battery material datasets. This network achieves high accuracy while requiring small amounts of labeled data and predicts a volume of billions voxel within few minutes. While applying supervised machine learning for segmenting real-world data, the ground truth is often absent. The results of segmentation are usually qualitatively justified by visual judgement. We try to unravel this fuzzy definition of segmentation quality by identifying the uncertainty due to the human bias diluted in the training data. Further CNN trainings using synthetic data show quantitative impact of such uncertainty on the determination of material’s properties. Nano-XCT datasets of various battery materials have been successfully segmented by training this neural network from scratch. We will also show that applying the transfer learning, which consists of reusing a well-trained network, can improve the accuracy of a similar dataset.

A comparative study of the permeability enhancement in coal and clay-rich shale by hydraulic fracturing using nano-CT and SEM image analysis

The low permeability of unconventional reservoirs is a key petrophysical parameter that restricts the seepage and migration of methane in micro-channels. Coal and shale have a high content of clay minerals, and swelling clay minerals lead to permeability reduction due to their unique water sensitivity and swelling mechanism, which is an important factor affecting the production efficiency of methane in reservoirs. This work begins with visual two-dimensional (2D) and three-dimensional (3D) characterization of the pore-fracture network in coal and clay-rich shale and emphasizes the root cause of the different changes in coal and clay-rich shale permeability by hydraulic fracturing. The results showed the increase of pore and throat radius of coal by hydraulic fracturing is significantly higher than that of clay-rich shale, indicating that high vitrinite and low clay content contribute to brittle deformation, while high clay and low vitrinite content account for ductile deformation. Hydraulic fracturing can form more effective micro-channels and increase shale permeability by nearly two orders of magnitude. The permeability enhancement of clay-rich shale is apparently better than that of coal by hydraulic fracturing. After fracturing, the average loss ratio of permeability of clay-rich shales is 35.2%, which is much higher than the average loss ratios measured on coal (11.1%), suggesting that the abundant water provided by hydraulic fracturing leads to the absorption and swelling of clay minerals in shale. Swelling clay minerals cause persistent adsorption and filling of H2O molecules between layers, forming colloidal suspensions in the micro-channels, further blocking the migration pathway of methane molecules in clay-rich shale.

Mapping the elemental and crystalline phase distribution in Cu2+ doped 45S5 bioactive glass upon crystallization

Nano-CT and TEM imaging characterisation of Cu-doped 45S5 glass-ceramics. The grain size and content of Cu-riched glassy phase, which affect bioactive and mechanical responses, can be tuned by heat treatment.

Foliar Uptake of the Potencially Toxic Elements in Garlic Chive Leaves

Contamination of vegetables due to the foliar uptake of atmospheric toxic elements could pose severe health risks. However, the uptake mechanisms of potencially toxic elements (PTEs) from the atmosphere and translocation by plant leaves remain unclear. In this study, carboxylic acid-functionalized water-soluble CdSe/ZnS quantum dot nanoparticles (QD NPs) were used as an experimental particle model of PTEs in the edible plant garlic chive (Allium tuberosum). A droplet of QD NP suspension was deposited to simulate the conditions of raindrops containing metal particles falling on a plant leaf. The 3D spatial distribution of QD NPs in plant leaves was measured using three complementary imaging techniques: synchrotron X-ray microcomputed tomography (micro-CT), nano-CT, and two-photon microscopy (TPM). The TPM and micro-CT results revealed that QD NPs deposited on garlic chive leaves penetrated the plant leaves. Nano-CT images showed that QD NPs are absorbed into mesophyll cells and phloem vessels. The results of TEM and TPM imaging demonstrated that QD NPs penetrate through the leaves and translocate in the direction of the stem. The use of these emerging imaging techniques improved the ability to detect and visualize NPs in a plant leaf. These observations also provide mechanistic insights into foliar metal uptake and their translocation and accumulation.