Alexander Peter Kao

Exposure to X-ray radiation for an extended amount of time can cause damage to the bone tissue and therefore affect its mechanical properties. Specifically, high-resolution X-ray Computed Tomography (XCT), in both synchrotron and lab-based systems, has been employed extensively for evaluating bone micro-to-nano architecture. However, to date, it is...

Ectopic calcification (EC) of myofibers is a pathological feature of muscle damage in Duchenne muscular dystrophy (DMD). Mineralisation of muscle tissue occurs concomitantly with macrophage infiltration, suggesting a link between ectopic mineral deposition and inflammation. One potential link is the P2X7 purinoceptor, a key trigger of inflammation,...

The biomaterial with the highest known tensile strength is a unique composite of chitin and goethite (α-FeO(OH)) present in teeth from the Common Limpet (Patella vulgata). A biomimetic based on limpet tooth, with corresponding high-performance mechanical properties is highly desirable. Here we report on the replication of limpet tooth developmental...

Digital volume correlation (DVC) in combination with high-resolution micro-computed tomography (microCT) imaging and in situ mechanical testing is gaining popularity for quantifying 3D full-field strains in bone and biomaterials. However, traditional in situ time-lapsed (i.e., interrupted) mechanical testing cannot fully capture the dynamic strain...

Additive Manufacturing (AM) often produces complex engineered structures by precisely distributing materials in a layer-by-layer fashion. Multimaterial AM is a particularly flexible technique able to combine a range of hard and soft materials to produce designed composites. Critically, the design of AM multimaterial structures requires the developm...

Azhdarchid pterosaurs, the largest flying vertebrates, remain poorly understood, with fundamental aspects of their palaeobiology unknown. X-ray computed tomography reveals a complex internal micro-architecture for three-dimensionally preserved, hyper-elongate cervical vertebrae of the Cretaceous azhdarchid pterosaur, Alanqa sp. Incorporation of the...

Plant fibres and especially flax can be distinguished from most synthetic fibres by their intricate shape and intrinsic porosity called lumen, which is usually assumed to be tubular. However, the real shape appears more complex and thus might induce stress concentrations influencing the fibre performance. This study proposes a novel representation...

Magnesium (Mg) and its alloys are very promising degradable, osteoconductive and osteopromotive materials to be used as regenerative treatment for critical-sized bone defects. Under load-bearing conditions, Mg alloys must display sufficient morphological and mechanical resemblance to the native bone they are meant to replace to provide adequate sup...

The overall mechanical behaviour of cortical bone is strongly dependant on its microstructure. X-ray computed tomography (XCT) has been widely used to identify the microstructural morphology of cortical tissue (i.e. pore network, Haversian and Volkmann's canals). However, the connection between microstructure and mechanics of cortical bone during p...

Background Coat protein complex 1 (COPI) is integral in the sorting and retrograde trafficking of proteins and lipids from the Golgi apparatus to the endoplasmic reticulum (ER). In recent years, coat proteins have been implicated in human diseases known collectively as “coatopathies”. Methods Whole exome or genome sequencing of two families with a...

Vitreous enamel steels (VES) are a class of metal-ceramic composite materials realised with a low carbon steel basement coated by an enamel layer. During the firing phase to adhere the enamel to the metal, several gas bubbles remain entrapped inside the enamel volume modifying its internal structure. In this work high-resolution X-ray computed tomo...

As a composite material, the mechanical properties of bone are highly dependent on its hierarchical organisation, thus, macroscopic mechanical properties are dictated by local phenomena, such as micro-damage resulting from repetitive cyclic loading of daily activities. Such microdamage is associated with plastic deformation and appears as a gradual...

The pterosaurs were the first vertebrates to evolve powered flight and they staged a major radiation in the Cretaceous. Cretaceous pterosaurs occupied many of the niches occupied today by birds, including aerial insect hawkers, piscivores, and filter feeders. The diversity of this radiation remains poorly known due to the uneven stratigraphic and g...

Fibres are present in many biological tissues and their geometric properties can be a useful indication of their role. Hence, imaging of nano-fibre volumes is useful for a number of different biomedical applications. It is possible to image nano-fibres with a variety of imaging modalities such as 2D Scanning Electron Microscopy (SEM) or 3D X-ray Co...

The mechanical behavior of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X‐ray Computed Tomography (XCT) has been extensively used to assess the progr...

A deeper understanding of the cartilage-bone mechanics is fundamental to unravel onset and progression of osteoarthritis, enabling better diagnosis and treatment. The aim of this study is therefore to explore the capability of X-ray computed (XCT) phase-contrast imaging in a lab-based system to enable digital volume correlation (DVC) measurements o...

A new pterosaur, Afrotapejara zouhri gen. et sp. is described on the basis of a partial rostral fragment from the Cretaceous Kem Kem beds of Takmout, near Erfoud in southern Morocco. The taxon is distinguished from all other Tapejaridae on the possession of a dorsal expansion of the rostral margin a short distance from the rostral tip. Tapejarid fe...

Deficient bone vasculature is a key component in pathological conditions ranging from developmental skeletal abnormalities to impaired bone repair. Vascularisation is dependent upon vascular endothelial growth factor (VEGF), which drives both angiogenesis and osteogenesis. The aim of this study was to examine the efficacy of blood vessel and bone f...

MMA-based cements are the most used bone cements in vertebroplasty and total hip arthroplasty. However, they present several drawbacks, including susceptibility to bacterial infection, monomer leakage toxicity, and high polymerization temperature, which can all lead to damage to the surrounding tissues and their failure. In the present study, silve...

Isolated cervical vertebrae from the mid Cretaceous Kem Kem beds of south east Morocco are referred to the theropod dinosaur clade Abelisauroidea, and represent the first axial remains from this deposit referred to this group. An isolated axis is referred to Abelisauroidea on account of the invaginated spinopostzygapophyseal lamina; the extremely l...

The regeneration of injured tendons and ligaments is challenging since the scaffolds needs proper mechanical properties and a biomimetic morphology. In particular, the morphological arrangement of scaffolds is a key point to drive the cells growth to properly regenerate the collagen extracellular matrix. Electrospinning is a promising technique to...

Reconstructions of ruptured tendons and ligaments currently have dissatisfactory failure rate. Failures are mainly due to the mechanical mismatch of commercial implants with respect to the host tissue. In fact, it is crucial to replicate the morphology (hierarchical in nature) and mechanical response (highly-nonlinear) of natural tendons and ligame...

Lesions of tendons and ligaments account for over 40% of the musculoskeletal lesions. Surgical techniques and materials for repair and regeneration are currently not satisfactory. The high rate of post-operative complications and failures mainly relates to the technical difficulties in replicating the complex multiscale hierarchical structure and t...

Surgical treatment of tendon lesions still yields unsatisfactory clinical outcomes. The use of bioresorbable scaffolds represents a way forward to improve tissue repair. Scaffolds for tendon reconstruction should have a structure mimicking that of the natural tendon, while providing adequate mechanical strength and stiffness. In this paper, electro...

Digital volume correlation (DVC), combined with in situ synchrotron microcomputed tomography (SR-microCT) mechanics, allows for 3D full-field strain measurement in bone at the tissue level. However, long exposures to SR radiation are known to induce bone damage, and reliable experimental protocols able to preserve tissue properties are still lackin...

Teeth are complex biological structures consisting primarily of enamel and dentin. The mechanical loading of teeth due to the action of brushing provides a complex interaction between applied forces and the biological structure, resulting in volume loss of dental tissue. The volume loss as a resulting of using an ex situ brushing of teeth was measu...

en Fibrous nanomaterials such as electrospun materials have many uses ranging from tissue engineering to biosensors. High‐resolution imaging is an important component in the characterization of these materials. Important parameters required to predict and study the properties of fibre rich materials include diameter and orientation distribution as...

en Repair of ligaments and tendons requires scaffolds mimicking the spatial organisation of collagen in the natural tissue. Electrospinning is a promising technique to produce nanofibres of both resorbable and biostable polymers with desired structural and morphological features. The aim of this study was to perform high‐resolution x‐ray tomography...

Tissue biomechanics regulate a wide range of cellular functions, but the influences on epidermal homeostasis and repair remain unclear. Here, we examined the role of extracellular matrix stiffness on human keratinocyte behavior using elastomeric substrates with defined mechanical properties. Increased matrix stiffness beyond normal physiologic leve...

Cortical bone is an example of a mineralized tissue containing a compositional distribution of hard and soft phases in 3-dimensional space for mechanical function. X-ray computed tomography (XCT) is able to describe this compositional and morphological complexity but methods to provide a physical output with comparable mechanical function is lackin...

Type VI collagen is a non-fibrillar collagen expressed in many connective tissues and implicated in extracellular matrix (ECM) organisation. We hypothesized that type VI collagen regulates matrix assembly and cell function within the dermis of the skin. In the present study we examined the expression pattern of type VI collagen in normal and wounde...