Edge Illumination X-Ray Phase Contrast Imaging and Ultrasonic Attenuation for Porosity Quantification in Composite Structures

Carbon fiber reinforced composites are widely used in the aerospace industry, due to their low weight and high strength. Porosity often occurs during the manufacturing of composite structures, which can compromise the structural integrity of the part and affect its mechanical properties. In the aerospace industry a typical requirement for structural components is for the porosity content to be kept below 2%. Non-destructive evaluation (NDE) techniques are used to estimate the porosity content in composite components, the most common being ultrasonic attenuation and X-ray computed tomography (CT). Planar Edge Illumination X-ray Phase Contrast Imaging (EI XPCI) was used to quantify the porosity content in woven carbon fiber reinforced composite plates with porosity ranging between 0.7% and 10.7%. A new metric was introduced, the standard deviation of the differential phase (STDVDP) signal, which represents the variation of inhomogeneity in the plates for features of a scale equal to or above the system resolution (here 12µm). The SDTVDP was found to have a very high correlation with porosity content estimated from matrix digestion and ultrasonic attenuation, hence providing a promising new methodology to quantify porosity in composite plates

Thyrotropin receptor blocking antibodies

Autoantibodies (Ab) against the thyroid-stimulating hormone receptor (TSHR) are frequently found in autoimmune thyroid disease (AITD). Autoantibodies to the TSHR (anti-TSHR-Ab) may mimic or block the action of TSH or be functionally neutral. Measurement of anti-TSHR-Ab can be done either via competitive-binding immunoassays or with functional cell-based bioassays. Antibody-binding assays do not assess anti-TSHR-Ab functionality, but rather measure the concentration of total anti-TSHR binding activity. In contrast, functional cell-based bioassays indicate whether anti-TSHR-Ab have stimulatory or blocking activity. Historically bioassays for anti-TSHR-Ab were research tools and were used to study the pathophysiology of Graves\u27 disease and Hashimoto\u27s thyroiditis. In the past, bioassays for anti-TSHR-Abs were laborious and time-consuming and varied widely in performance from laboratory to laboratory. Recent advances in the development of cell-based assays, including the application of molecular engineering, have led to significant improvements that have enabled bioassays to be employed routinely in clinical laboratories. The prevalence and functional significance of TSHR blocking autoantibodies (TBAb) in autoimmune hypothyroidism has been less well investigated compared to TSHR stimulating Ab. There is an increasing body of data, however, that demonstrate the clinical utility and relevance of TBAb, and thus the importance of TBAb bioassays, in the diagnosis and management of patients with AITD. In the present review, we summarize the different methods used to measure TBAb, and discuss their prevalence and clinical relevance

A multi-layer edge-on single photon counting silicon microstrip detector for innovative techniques in diagnostic radiology

A three-layer detector prototype, obtained by stacking three edge-on single photon counting silicon microstrip detectors, has been developed and widely tested. This was done in the framework of the Synchrotron Radiation for Medical Physics/Frontier Radiology (SYRMEP/FRONTRAD) collaboration activities, whose aim is to improve the quality of mammographic examinations operating both on the source and on the detector side. The active surface of the device has been fully characterized making use of an edge-scanning technique and of a well-collimated laminar synchrotron radiation beam. The obtained data (interlayer distances, channel correspondence, etc.) have then been used to combine information coming from each detector layer, without causing any loss in spatial and contrast resolution of the device. Contrast and spatial resolution have also been separately evaluated for each detector layer. Moreover, imaging techniques (phase contrast, refraction, and scatter imaging), resulting in an increased visibility of low absorbing details, have been implemented, and their effectiveness has been tested on a biological sample. Finally, the possibility of simultaneously acquiring different kind of images with the different detector layers is discussed. This would result in maximizing the information extracted from the sample, while at the same time the high absorption efficiency of the detector device would allow a low dose delivery

Composite impact damage detection and characterization using ultrasound and X-ray NDE techniques

Combining low weight and high strength, carbon fiber reinforced composites are widely used in the aerospace industry, including for primary aircraft structures. Barely visible impact damage can compromise the structural integrity and potentially lead to failures. Edge Illumination (EI) X-ray Phase Contrast imaging (XPCi) is a novel X-ray imaging technique that uses the phase effects induced by damage to create improved contrast. For a small cross-ply composite specimen with impact damage, damage detection was compared to ultrasonic immersion C-scans. Different defect types could be located and identified, verified from the conventional ultrasonic NDE measurement

Post-Acquisition Mask Misalignment Correction for Edge Illumination X-ray Phase Contrast Imaging

Edge illumination x-ray phase contrast imaging uses a set of apertured masks to translate phase effects into variation of detected intensity. While the system is relatively robust against misalignment, mask movement during acquisition can lead to gradient artifacts. A method has been developed to correct the images by quantifying the misalignment post-acquisition and implementing correction maps to remove the gradient artifact. Images of a woven carbon fiber composite plate containing porosity were used as examples to demonstrate the image correction process. The gradient formed during image acquisition was removed without affecting the image quality, and results were subsequently used for quantification of porosity, indicating that the gradient correction did not affect the quantitative content of the images

Composite porosity characterization using X-ray edge illumination phase contrast and ultrasonic techniques

Owing to their combination of low weight and high strength, carbon fiber reinforced composites are widely used in the aerospace industry, including for primary aircraft structures. Porosity introduced by the manufacturing process can compromise structural performance and integrity, with a maximum porosity content of 2% considered acceptable for many aerospace applications. The main nondestructive evaluation (NDE) techniques used in industry are ultrasonic imaging and X-ray computed tomography, however both techniques have limitations. Edge Illumination X-ray Phase Contrast Imaging (EI XPCi) is a novel technique that exploits the phase effects induced by damage and porosity on the X-ray beam to create improved contrast. EI XPCi is a differential (i.e., sensitive to the first derivative of the phase), multi-modal phase method that uses a set of coded aperture masks to acquire and retrieve the absorption, refraction, and ultra-small-angle scattering signals, the latter arising from sub-pixel sample features. For carbon fiber-reinforced woven composite specimens with varying levels of porosity, porosity quantification obtained through various signals produced by EI XPCi was compared to ultrasonic immersion absorption C-scans and matrix digestion. The standard deviation of the differential phase is introduced as a novel signal for the quantification of porosity in composite plates, with good correlation to ultrasonic attenuation

Reliable material characterisation at low x-ray energy through the phase-attenuation duality

We present a comparison of between two polychromatic X-ray imaging techniques used to characterise materials: dual energy (DE) attenuation and phase-attenuation (PA), the latter being implemented via a scanning-based Edge Illumination system. The system-independent method to extract electron density and effective atomic number developed by S.G. Azevedo et al IEEE Transactions on nuclear science, Vol. 63, 341 (2016) - SIRZ - is employed for the analysis of planar images, with the same methodology being used for both approaches. We show PA to be more reliable at low energy X-ray spectra (40 kVp), where conventional DE breaks down due to insufficient separation of the energies used in measurements, and to produce results comparable with “standard” DE implemented at high energy (120 kVp), therefore offering a valuable alternative in applications where the use of high x-ray energy is impractical

The Varicella-Zoster virus origin-binding protein can substitute for the herpes simplex virus origin-binding protein in a transient origin-dependent DNA replication assay in insect cells

AbstractWe isolated two recombinant baculoviruses each of which expresses a varicella-zoster virus (VZV) homolog of one ofthe seven herpes simplex virus type 1 (HSV-1) genes required for DNA replication. We performed transient origin-dependent DNA replication assays in insect cells in which we substituted a baculovirus which expresses a VZV protein for a baculovirus which expresses its HSV homolog. VZV gene 51 protein was found to be able to support origin-dependent DNA synthesis when it was substituted for UL9, the HSV-1 origin-binding protein (01313). This occurred whether an HSV-1 or a VZV origin-containing plasmid was used in the assay. These results suggest that VZV gene 51 protein is able to interact with the HSV replication machinery, and in light of the extensive structural divergence of these proteins, it suggests that initiation of VZV and HSV-1 DNA synthesis may involve a limited number of interactions between the OBP and other replication factors. Substitution of infected-cell protein 8 (ICP8), the major single-stranded DNA-binding protein of HSV-1, with VZV gene 29 protein, however, did not result in amplification of plasmids containing either an HSV-1 or a VZV origin. In the absence of ICP8, addition of both VZV gene 51 protein and gene 29 protein was also negative for origin-dependent replication whether or not UL9 was present. Although demonstration that our baculovirus-expressed VZV gene 29 protein is functional for DNA replication will await development of a VZV replication system, our results suggest that VZV gene 29 protein is unable to interact functionally with one or more of the HSV replication proteins. This approach should contribute to efforts to define the interactions among the alphaherpesvirus DNA replication proteins