Synchrotron X-ray Phase Contrast Research Articles

Quantitative Structural and Compositional Elucidation of Real-World Pharmaceutical Tablet Using Large Field-of-View, Correlative Microscopy-Tomography Techniques and AI-Enabled Image Analysis.

The purpose of this study is to present a correlative microscopy-tomography approach in conjunction with machine learning-based image segmentation techniques, with the goal of enabling quantitative structural and compositional elucidation of real-world pharmaceutical tablets. Specifically, the approach involves three sequential steps: 1) user-oriented tablet constituent identification and characterization using correlative mosaic field-of-view SEM and energy dispersive X-ray spectroscopy techniques, 2) phase contrast synchrotron X-ray micro-computed tomography (SyncCT) characterization of a large, representative volume of the tablet, and 3) constituent segmentation and quantification of the imaging data through user-guided, iterative supervised machine learning and deep learning. This approach was implemented on a real-world tablet containing 15% API and multiple common excipients. A representative volumetric tablet image was obtained using SyncCT at a 0.36-µm resolution, from which constituent particles and pores were fully segmented and quantified. As validation, the derived tablet formulation composition and porosity agreed with the experimental values, despite the micrometer-scale particle and pore sizes. The approach also revealed the formation of ordered mixture inside the tablet. Notably, the image-derived size distributions of both the agglomerated microcrystalline cellulose and its primary particulate units matched the laser diffraction-based measurements of the as-is material. Key pore attributes including the pore size distribution, spatial anisotropy, and pore interconnectivity were also qualified. Overall, this study demonstrated that the correlative microscopy-tomography approach, by leveraging phase contrast SyncCT and AI-based image analysis, can deliver new, practically-useful structural and compositional information and facilitate more efficient formulation and process development of tablets.

In situ characterisation of dynamic fracture in Al2O3 using ultra-fast X-ray phase contrast radioscopy: effects of porosity and crack speed

The dynamic fracture properties of porous ceramics were studied using single bunch synchrotron X-ray phase contrast imaging. The modified brazilian geometry was used to initiate and propagate a pure mode I crack. The specimen was compressed using the Split Hopkinson bars at strain rates of the order of 102 s-1. Main cracks were isolated for four different grades of Al2O3, one dense alumina, and three porous grades with 20% to 60% porosity. The maximum measured crack velocities for three grades is of the order of 0.6cR and 0.4cR for the most porous. The fracture energy was estimated using a FE numerical simulation to quantify the influence of inertial effects induced by crack propagation. The results show that these inertial effects are far from negligible (up to 80% of the stored energy) and that the dynamic correction factors known from the literature tend to overestimate the fracture energy. The values obtained vary from 22 J/m2 for the densest to 5 J/m2 for the most porous.

Fabrication and X-ray microtomography of sandwich-structured PEEK implants for skull defect repair

Bone defects pose a significant risk to human health. Medical polyetheretherketone (PEEK) is an excellent implant material for bone defect repair, but it faces the challenge of bone osteoconduction and osseointegration. Osteoconduction describes the process by which bone grows on the surface of the implant, while osseointegration is the stable anchoring of the implant achieved by direct contact between the bone and the implant. Bone defects repair depends on the implant’s three-dimensional spatial structure, including pore size, porosity, and interconnections to a great extent. However, it is challenging to fabricate the porous structures to meet specific requirements and to characterize them without causing damage. In this study, we designed and fabricated sandwich-like PEEK implants mimicking the three-layer structures of the skull, whose defects imposes a significant burden on young adulthood and paediatric populations, and performed in-line phase-contrast synchrotron X-ray microtomography to non-destructively investigate the internal porous microstructures. The sandwich-like three-layer microstructure, comprising a dense layer, a loose layer and a dense layer in succession, exhibits structural similarity to that in a natural skull. This work demonstrated the fabrication of the sandwich-like PEEK implant that could potentially enhance osteoconduction and osseointegration. Furthermore, the interior structures and residual porogen sodium chloride particles were observed within the PEEK implant, which cannot be realized by other microscopic methods without destroying the sample. It highlights the advantages and potential of using synchrotron X-ray microtomography to analyze the structure of biomedical materials. This study provides theoretical guidance for the further design and fabrication of PEEK bone repair materials and will advance the clinical application of innovative bioactive bone repair materials.

The osteohistology of Orthosuchus stormbergi using synchrotron radiation microcomputed tomography.

Orthosuchus stormbergi was a small-bodied crocodyliform, representative of a diverse assemblage of Early Jurassic, early branching crocodylomorph taxa from the upper Elliot Formation of South Africa. The life history of these early branching taxa remains poorly understood, with only sparse investigations into their osteohistology, yet species like Orthosuchus have potential to inform about the macroevolution of growth strategies on the stem leading to crown crocodilians. In order to elucidate the growth patterns of Orthosuchus, we used propagation phase contrast X-ray synchrotron micro-computed tomography to virtually image the osteohistology of the postcrania of two specimens, including multiple elements from the type (SAM-PK-K409), and the femur of a referred specimen (BP/1/4242). In total, we scanned nine mid-diaphyseal sections of the humerus, radius, ulna, radiale, femur, tibia, fibula, and a rib. We then compared our results to osteohistological sections of crocodylomorph taxa from the published literature. Our results show that the most predominant bone tissue type in Orthosuchus is lamellar, with a few patches of woven and parallel-fibred bone. The type specimen contains four to five lines of arrested growth and the hindlimb elements present outer circumferential lamellae, whereas the referred specimen contains six to seven. Both specimens grew at similar rates, reaching adult skeletal body size at year four or five. The sectioned bones, most notably the radius and ulna, are comparatively thick walled and compact. Our virtual osteohistological sections are one of the first for an early branching crocodyliform, and the broad sample of skeletal elements makes Orthosuchus a key anchor point for understanding the plesiomorphic life history traits of the clade.

In vivo imaging of nickel-rich laticifers: A breakthrough in metal hyperaccumulation

The discovery of the nickel-rich latex of the New Caledonian endemic tree Pycnandra acuminata introduced the term ‘hyperaccumulator’ and gave rise to a new field of research. This then instigated a global quest for these unusual hyperaccumulator plants, even while the underlying mechanisms of nickel acquisition, transport, and internal elemental distribution remained unknown for this original laticifer-bearing hyperaccumulator plant. Here we reveal for the first time the distribution of nickel-filled laticifers in the different plant organs of P. acuminata. The pressurised nickel laticifers were imaged multimodally with a combination of synchrotron X-ray fluorescence (XRF) microscopy, microtomography (XRF-μCT) and synchrotron X-ray phase contrast imaging microtomography (PCI-μCT). These advanced synchrotron methodologies allowed for complimentary non-invasive reconstructions of an in-situ model of the laticiferous system in this species. The data shows the distribution of the nickel-rich laticifers within whole plant tissues from roots to apical tip, thus suggesting nickel trafficking in the laticifer network. The extraordinary concentration of nickel within P. acuminata laticifers functions as an effective natural tracer for XRF-μCT and PCI-μCT to probe the structure and organization of these cells, thereby permitting insights into the development and physiological functioning of this unique duct system.

A promising eco-sustainable wound dressing based on cellulose extracted from Spartium junceum L. and impregnated with Glycyrrhiza glabra L extract: Design, production and biological properties

Glycyrrhiza glabra extract is widely known for its antioxidant and anti-inflammatory properties and can improve the wound healing process. The aim of this work was to shorten the time of the healing process by using an eco-sustainable wound dressing based on Spanish broom flexible cellulosic fabric by impregnation with G. glabra extract-loaded ethosomes. Chemical analysis of G. glabra extract was performed by LC-DAD-MS/MS and its encapsulation into ethosomes was obtained using the ethanol injection method. Lipid vesicles were characterized in terms of size, polydispersity index, entrapment efficiency, zeta potential, and stability. In vitro release studies, biocompatibility, and scratch test on 3T3 fibroblasts were performed. Moreover, the structure of Spanish broom dressing and its ability to absorb wound exudate was characterized by Synchrotron X-ray phase contrast microtomography (SR-PCmicroCT). Ethosomes showed a good entrapment efficiency, nanometric size, good stability over time and a slow release of polyphenols compared to the free extract, and were not cytotoxic. Lastly, the results revealed that Spanish broom wound dressing loaded with G. glabra ethosomes is able to accelerate wound closure by reducing wound healing time. To sum up, Spanish broom wound dressing could be a potential new green tool for biomedical applications.

Progressive Weakening of Granite by Piezoelectric Excitation of Quartz with Alternating Current

A promising solution to reduce energy usage and mitigate the wear of drilling and comminution tools during mining operations involves inducing vibrations within the piezoelectric phases dispersed in the structure of rocks using alternating current (AC). This paper presents experimental evidence of AC-induced weakening of Kuru granite, manifested as improvements in rock drillability and reductions of strength. Sievers’ J-miniature drill tests were used to assess surface drillability. The impact of AC treatment on the quasi-static strength of granite was assessed via three-point bending and indirect tension Brazilian disk tests. The influence of AC treatment on the dynamic tensile strength of the rock was determined using split Hopkinson bar tests, with the fragmentation process captured using in situ ultra-fast synchrotron X-ray phase contrast imaging. The quasi-static tests revealed no reduction in rock strength after the AC treatment. In contrast, reductions of 25% in hardness and 18% in dynamic tensile strength were observed. Fragmentation patterns differed between treated and non-treated rocks, with treated specimens exhibiting reduced macrocrack formation during loading.

Characterization of spring and durum wheat using non-destructive synchrotron phase contrast X-ray microtomography during storage

Post-harvest losses during cereal grain storage are a big concern in both developing and developed countries, where spring and durum wheat are staple food grains. Varieties under these classes behave differently under storage, which affects their end storage life. High resolution imaging data of dry as well as spoiled seed are not available for any class of wheat; therefore, an attempt was made to generate 3D data for better understanding of seed structure and changes due to spoilage. Six wheat varieties (3 varieties for each class of wheat) were stored for 5 week at 17% moisture content (wb) before scanning. Seeds were also stored in a freezer (-18 °C) for further scanning to determine if any changes occur in the structure of seeds due to freezing. Spring varieties of wheat performed better than durum varieties and freezing did not affect seed structure. Data could also help plant breeders to develop varieties that do not easily spoil, adjust grain processing techniques, and develop post-harvest recommendations for other wheat varieties.

Micro- and nanostructure specific X-ray tomography reveals less matrix formation and altered collagen organization following reduced loading during Achilles tendon healing

Recovery of the collagen structure following Achilles tendon rupture is poor, resulting in a high risk for re-ruptures. The loading environment during healing affects the mechanical properties of the tendon, but the relation between loading regime and healing outcome remains unclear. This is partially due to our limited understanding regarding the effects of loading on the micro- and nanostructure of the healing tissue. We addressed this through a combination of synchrotron phase-contrast X-ray microtomography and small-angle X-ray scattering tensor tomography (SASTT) to visualize the 3D organization of microscale fibers and nanoscale fibrils, respectively. The effect of in vivo loading on these structures was characterized in early healing of rat Achilles tendons by comparing full activity with immobilization. Unloading resulted in structural changes that can explain the reported impaired mechanical performance. In particular, unloading led to slower tissue regeneration and maturation, with less and more disorganized collagen, as well as an increased presence of adipose tissue. This study provides the first application of SASTT on soft musculoskeletal tissues and clearly demonstrates its potential to investigate a variety of other collagenous tissues. Statement of significanceCurrently our understanding of the mechanobiological effects on the recovery of the structural hierarchical organization of injured Achilles tendons is limited. We provide insight into how loading affects the healing process by using a cutting-edge approach to for the first time characterize the 3D micro- and nanostructure of the regenerating collagen. We uncovered that, during early healing, unloading results in a delayed and more disorganized regeneration of both fibers (microscale) and fibrils (nanoscale), as well as increased presence of adipose tissue. The results set the ground for the development of further specialized protocols for tendon recovery.

Study of Microstructural, Nutritional, and Biochemical Changes in Hulled and Hulless Barley during Storage Using X-ray and Infrared Techniques.

Four varieties of barley (Esma, AC Metacalf, Tradition, and AB Cattlelac), representing four Canadian barley classes, were stored at 17% moisture content (mc) for 8 week. Stored barely was characterized using synchrotron X-ray phase contrast microcomputed tomography, synchrotron X-ray fluorescence imaging, and mid-infrared spectroscopy at the Canadian Light Source, Saskatoon. The deterioration was observed in all the selected varieties of barley at the end of 8 week of storage. Changes due to spoilage over time were observed in the grain microstructure and its nutrient distribution and composition. This study underscores the critical importance of the initial condition of barley grain microstructure in determining its storage life, particularly under unfavorable conditions. The hulled barley varieties showed more deterioration in microstructure than the hulless varieties of barley, where a direct correlation between microstructural changes and alterations in nutritional content was found. All selected barley classes showed changes in the distribution of nutrients (Ca, Fe, K, Mn, Cu, and Zn), but the two-row AC Metcalf variety exhibited more substantial variations in their nutrient distribution (Zn and Mn) than the other three varieties during storage. The two-row class barley varieties showed more changes in biochemical components (protein, lipids, and carbohydrates) than the six-row class varieties.

Understanding the hot isostatic pressing effectiveness of laser powder bed fusion Ti-6Al-4V by in-situ X-ray imaging and diffraction experiments

In the present study, in-situ observation of Hot Isostatic Pressure (HIP) procedure of laser powder bed fusion manufactured Ti-6Al-4V parts was performed to quantitatively estimate the densification rate of the material and the influence of the defect initial size and shape on such rate. The observations were performed in-situ using the Ultrafast Tomography Paris-Edinburgh Cell and the combination of fast phase-contrast synchrotron X-ray tomography and energy dispersive diffraction. With this strategy, we could quantify how the effectiveness of HIP depends on the characteristics of a defect. Smaller defects showed a higher densification rate, while the defect shape did not have significant effect on such rate.

In situ damage characterization of CFRP under compression using high-speed optical, infrared and synchrotron X-ray phase-contrast imaging

The strain rate dependency and failure modes of carbon fiber reinforced plastic (CFRP) laminate were investigated under out-of-plane compressive loading. Simultaneous high-speed optical and infrared imaging were used to measure full-field deformation and temperature in the dynamically loaded specimens. The damage initiation and propagation inside the CFRP laminates at high strain rates were characterized using in-situ ultra-fast synchrotron X-ray phase contrast imaging (XPCI). The visually observed damage onset occurs at the strain value of 4.2 ± 0.6% as a transverse shear fracture at the free edge of specimens. The local temperature increases significantly to 185 °C due to damage initiation at high strain rates, while at low strain rates the temperature rise occurs after the final shear band forms. The XPCI and post-failure analysis provide an integrated perspective on the formation of a diagonal shear crack and disintegration of the specimen into two pieces with the fracture of plies in the in-plane transverse direction. Scanning electron microscopic (SEM) study was integrated with XPCI results to append the time scale for the post-mortem failure pattern as well as the length scale for microcracks and filament-level failure.

Exploiting synchrotron X-ray tomography for a novel insight into flax-fibre defects ultrastructure

Flax fibres are valuable reinforcements for tomorrow’s composites. However, defects called kink-bands, which mainly appear on fibres during the extraction and transformation phases, might affect their mechanical properties. Defects induced pores within the kink-band are investigated in this work. They were morphologically explored using synchrotron phase-contrast X-ray microtomography, a technique that displays a sharp 3D representation of the pores. The study highlights the link between kink-bands and secondary cell wall ultrastructure. Pores are organised concentrically around the lumen, and their low thickness suggest that they are located at the interface between cellulose layers within S2 (G) layer. Moreover, the pores inclination with reference to the lumen axis follows the typical microfibrillar angle changes observed in the literature in the kink-band region. The volumes of the pores were measured, and a local increase in porosity was revealed in zones where defects are most severe along the fibre.

Heterotopic mineral deposits in intact rat Achilles tendons are characterized by a unique fiber-like structure

Heterotopic mineralization entails pathological mineral formation inside soft tissues. In human tendons mineralization is often associated with tendinopathies, tendon weakness and pain. In Achilles tendons, mineralization is considered to occur through heterotopic ossification (HO) primarily in response to tendon pathologies. However, refined details regarding HO deposition and microstructure are unknown. In this study, we characterize HO in intact rat Achilles tendons through high-resolution phase contrast enhanced synchrotron X-ray tomography. Furthermore, we test the potential of studying local tissue injury by needling intact Achilles tendons and the relation between tissue microdamage and HO. The results show that HO occurs in all intact Achilles tendons at 16 weeks of age. HO deposits are characterized by an elongated ellipsoidal shape and by a fiber-like internal structure which suggests that some collagen fibers have mineralized. The data indicates that deposition along fibers initiates in the pericellular area, and propagates into the intercellular area. Within HO deposits cells are larger and more rounded compared to tenocytes between unmineralized fibers, which are fewer and elongated. The results also indicate that multiple HO deposits may merge into bigger structures with time by accession along unmineralized fibers. Furthermore, the presence of unmineralized regions within the deposits may indicate that HOs are not only growing, but mineral resorption may also occur. Additionally, phase contrast synchrotron X-ray tomography allowed to distinguish microdamage at the fiber level in response to needling. The needle injury protocol could in the future enable to elucidate the relation between local inflammation, microdamage, and HO deposition.

New paradigm in graft rejection detection in heart transplantation recipients: diagnostic utility of synchrotron X-ray phase contrast imaging (GRAFT-XPCI) - a multi-centric, prospective, observational study protocol

New paradigm in graft rejection detection in heart transplantation recipients: diagnostic utility of synchrotron X-ray phase contrast imaging (GRAFT-XPCI) - a multi-centric, prospective, observational study protocol

Exploring the three-dimensional vasculature of dermal hard tissues in thyestiid osteostracans using synchrotron radiation microtomography

ABSTRACT Osteostracans are stem-gnathostomes with bony tissues that represent an important link between living jawed and jawless vertebrates, the latter of which lack skeletal hard tissues. In this study, a number of skeletal microremains from a diverse group of osteostracans called thyestiids have been investigated using propagation phase-contrast X-ray synchrotron microtomography. This enabled detailed reconstructions of their three-dimensional vasculature. The dermal skeleton of thyestiids is divided into three layers that vary in proportion between taxa, similar to gnathostomes and other osteostracans. The basal layer is confirmed as an acellular bony tissue composed of fiber bundles that contains narrow, vertical canals and/or large cavities. Bundles bend around smaller canals but form jagged edges around larger cavities, which suggests delayed mineralization. The presumed vascular mesh canals of the deep middle layer are radially arranged in some taxa, but more irregular or even tree-like in others, suggesting a relation to how the elements developed and grew. A number of mesh canals ascend toward the superficial layer where they supply the subepidermal vascular plexus, or create pore fields that open to the surface in some taxa. These ascending mesh canals most likely expanded and formed a network of canals underneath more extensive pore fields. Aestiaspis viitaensis has a simple upper canal system above these fields, while Tremataspis mammillata and Tr. milleri scales have a polygonal network of upper mesh canals above extensive perforated septa. These systems are most likely homologous, but their relation to intra- and inter-areal canals described in other osteostracans remains ambiguous.

Local TGF-beta sequestration by fibrillin-1 regulates vascular wall homeostasis in the thoracic aorta

Abstract Background Aortic dissection and rupture is the main cause of early cardiovascular mortality in patients with Marfan syndrome (MFS). MFS is caused by a defect in fibrillin-1, a building block of microfibrils in the extracellular matrix which binds transforming growth factor beta (TGF-beta) via interaction with latent TGF-beta binding proteins (LTBPs). Multiple mouse models, both pharmaceutically induced and genetically manipulated, have been used to investigate the pathophysiology and biomechanical aspects of thoracic aortic aneurysms and dissections. However, the role of TGF-beta in MFS has been controversial, with earlier studies suggesting that excess release of TGF-beta due to decreased interaction with dysfunctional fibrillin-1 leads to aortic dilation and vascular damage, while other studies have shown an important protective effect of TGF-beta. Studying dedicated mouse models for MFS, with defects interfering with TGF-beta binding and -function may help resolve these discrepancies. Purpose This study aimed to reveal insights in the role of TGF-beta signaling in aneurysm formation and dissection in MFS. Methods Mice lacking the fibrillin-1 binding site for LTBPs (Fbn1H1Δ/+ and Fbn1H1Δ/H1Δ), mice with a truncated fibrillin-1 (Fbn1GT-8/+), and mice with a combination of both alleles (Fbn1GT-8/ H1Δ) were subjected to in vivo cardiac ultrasound analysis. Ex vivo phase-contrast synchrotron X-ray imaging was performed at the Paul Scherrer Institute to visualize the elastic lamellae architecture in the vascular wall of the entire excised thoracic aorta in a subset of mice from each group. Results Fbn1GT-8/+, Fbn1 H1Δ/+ and Fbn1H1Δ/H1Δ mice had a normal life span, but Fbn1GT-8/ H1Δ mice showed increased mortality due to aortic rupture starting at 4–5 months of age. The aortic root was dilated both in Fbn1GT-8/+ and Fbn1GT-8/ H1Δ mice at 6 months of age, but not in Fbn1H1D/+ or Fbn1H1Δ/H1Δ mice. Synchrotron images showed significant elastic lamellae fragmentation in the thoracic aortic wall of Fbn1GT-8/+ mice, and to a larger extent in Fbn1GT-8/ H1Δ mice. Surprisingly, localized elastin fragmentation was also found in the ascending thoracic aorta of Fbn1 H1Δ/+ and Fbn1H1Δ/H1Δ mice, despite a lack of aortic aneurysm formation. Moreover, Fbn1H1Δ/H1Δ mice displayed more severe aortic wall damage. The localized microdissections found in these mouse models were characterized by a severe alteration of the elastic fiber organization, cellular influx and increased collagen deposition, as confirmed by histological analysis. Conclusions Our data suggest that loss of LTBP binding to fibrillin-1 leads to the development of localized microdissections in the aorta in the absence of aortic aneurysm, and exacerbates the aortic wall morphology abnormalities in mice with truncated fibrillin-1. We therefore hypothesize that local TGF-beta sequestration is required to maintain aortic homeostasis. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Foundation for Cardiac Surgery (“VZW Fonds voor Hartchirurgie”), grant No. 489644Baillet-Latour Grant for Medical Research

Kembawacela yajuwayeyi n. sp., a new cistecephalid species (Dicynodontia: Emydopoidea) from the Upper Permian of Malawi

Cistecephalidae are a relatively basal clade of dicynodonts, well-nested within emydopoids, and known to have multiple adaptations to a fossorial lifestyle. In recent years cistecephalid taxonomic diversity has been progressively increasing and important insights into the osteology, soft-tissue anatomy, and paleobiology of the clade have improved considerably. Here we describe a new species of the cistecephalid Kembawacela from the Chiweta Beds (northern Malawi, Wuchiapingian), a poorly sampled area of Karoo sediments. Due to the minute dimensions and delicate nature of specimen DMMM-PK-16-1, we utilized propagation phase-contrast synchrotron X-ray micro-computed tomography, revealing conspicuous contrast between rock matrix and bone and allowing reconstruction of its cranial osteology in great detail. DMMM-PK-16-1 is here recognized as a new species based on the morphology of the crista oesophagea of the pterygoid, which has an acute posterior process separate from its contralateral. Despite the affinities with Kembawacela kitchingi there are various distinguishable features absent in the taxon (e.g., posterior border of the pterygoids is smoothly concave, rather than interdigitating with the basipostsphenoid). The erection of a new species in this region seems to support the growing evidence for species-level diversity in East African Karoo basins when contrasted to the Main South African Karoo basin. Furthermore, the anatomical resolution obtained allowed us to reconstruct the osseous labyrinth, the paths for several nerve branches, arteries and veins for the first time in cistecephalids, and we develop new hypotheses for their paths and nomenclature for dicynodonts. We found remarkable resemblance in the brain endocast of DMMM-PK-16-1 and another cistecephalid, Kawingasaurus, which is distinct from other dicynodonts in which it is known.

Tailoring the Microstructure of Lamellar Ti3C2Tx MXene Aerogel by Compressive Straining.

Aerogels are attracting increasing interest due to their functional properties, such as lightweight and high porosity, which make them promising materials for energy storage and advanced composites. Compressive deformation allows the nano- and microstructure of lamellar freeze-cast aerogels to be tailored toward the aforementioned applications, where a 3D nanostructure of closely spaced, aligned sheets is desired. Quantitatively characterizing their microstructural evolution during compression is needed to allow optimization of manufacturing, understand in-service structural changes, and determine how aerogel structure relates to functional properties. Herein we have developed methods to quantitatively analyze lamellar aerogel domains, sheet spacing, and sheet orientation in 3D and to track their evolution as a function of increasing compression through synchrotron phase contrast X-ray microcomputed tomography (μCT). The as-cast domains are predominantly aligned with the freezing direction with random orientation in the orthogonal plane. Generally the sheets rotate toward flat and their spacing narrows progressively with increasing compression with negligible lateral strain (zero Poisson’s ratio). This is with the exception of sheets close to parallel with the loading direction (Z), which maintain their orientation and sheet spacing until ∼60% compression, beyond which they exhibit buckling. These data suggest that a single-domain, fully aligned as-cast aerogel is not necessary to produce a post-compression aligned lamellar structure and indicate how the spacing can be tailored as a function of compressive strain. The analysis methods presented herein are applicable to optimizing freeze-casting process and quantifying lamellar microdomain structures generally.

Dental cementum virtual histology of Neanderthal teeth from Krapina (Croatia, 130-120 kyr): an informed estimate of age, sex and adult stressors.

The evolution of modern human reproductive scheduling is an aspect of our life history that remains vastly uncomprehended. The present work aims to address this gap by validating a non-destructive cutting-edge methodology to infer adult life-history events on modern teeth with known life history and then applying it to fossil specimens. We use phase-contrast synchrotron X-ray microtomography to visualize the dental cementum of 21 specimens: nine contemporary humans; 10 Neanderthals from Krapina (Croatia, 130-120 kyr); one Neolithic Homo sapiens from Ajmana (Serbia); and one Mesolithic H. sapiens from Vlasac (Serbia). We were able to correctly detect and time (root mean square error = 2.1 years; R2 = 0.98) all reproductive (menarche, parturition, menopause) and other physiologically impactful events in the modern sample. Nonetheless, we could not distinguish between the causes of the events detected. For the fossil specimens, we estimated age at death and age at occurrence of biologically significant events. Finally, we performed an exploratory analysis regarding possible sexual dimorphism in dental cementum microstructure, which allowed us to correctly infer the sex of the Neolithic specimen, for which the true value was known via DNA analysis.