Microstructure and tensile properties of carbon-epoxy laminates produced by automated fibre placement: Influence of a caul plate on the effects of gap and overlap embedded defects

Automated fibre placement (AFP) enables the trajectory of unidirectional composite tape to be optimized, but laying down complex shapes with this technology can result in the introduction of defects. The aim of this experimental study is to investigate the influence of gaps and overlaps on the microstructure and tensile properties of carbon-epoxy laminates. First, a comparison between a hand-layup and AFP layup, draped and cured under the same conditions, shows equivalent microstructures and tensile properties. This provides the reference values for the study. Then, gap and overlap embedded defects (more or less severe) are introduced during manufacturing, on two cross-ply layups [(0°/(90°)5/0°] and [(90°/0°)2/90°]. Autoclave cure without a caul plate results in local thickness variation and microstructural changes which depend on the defect type. This has a strong influence on mechanical performance. Use of a caul plate avoids these variations and in this case embedded defects hardly affect tensile properties.

Automatic Glaucoma Detection Based on Optic Disc Segmentation and Texture Feature Extraction

The use of digital image processing techniques is prominent in medical settings for the automatic diagnosis of diseases. Glaucoma is the second leading cause of blindness in the world and it has no cure. Currently, there are treatments to prevent vision loss, but the disease must be detected in the early stages. Thus, the objective of this work is to develop an automatic detection method of Glaucoma in retinal images. The methodology used in the study were: acquisition of image database, Optic Disc segmentation, texture feature extraction in different color models and classification of images in glaucomatous or not. We obtained results of 93% accuracy

Embolisation of Vertebral Artery Damaged Following Cervical Disc Removal

Introduction: The incidence of vertebral artery (VA) injury during cervical spine surgery is rare. Even though tamponade is effective in many cases, early consultation of an endovascular team is recommended if bleeding cannot be controlled. We report a case of emergent endovascular embolisation of left VA due to iatrogenic injury during anterior cervical disc removal and fusion. Case: A 47-year-old woman was admitted to our emergency department with serious arterial bleeding from the neck only hours after undergoing anterior cervical disc removal and fusion surgery. She was intubated and mechanically ventilated, however hemorrhage could not be successfully controlled by packing with surgical hemostatic agents. Cranial computed tomography, computed tomography of the cervical spine and CT angiography confirmed the suspected diagnosis of injury to the VA. Emergent endovascular embolisation successfully stopped the bleeding. Occlusion of the vessel was achieved by vascular plugging. The patient was discharged from our hospital 14 days after the intervention, receiving a revision surgery of the cervical spine on the day of embolisation. At the date of discharge she presented without any focal neurological deficit. Conclusion: Pre-operative radiographic imaging of the cervical spine should be used routinely to identify anatomic abnormalities of the vertebral arteries. Endovascular embolisation appears to be effective in treating acute iatrogenic dissection of the vertebral arteries.

Low back pain, intervertebral disc and occupational diseases

International audience

An epidemiological surveillance network of lumbar disc surgery to help prevention of and compensation for low back pain

International audience

Microstructure, vibrational and visible emission properties of low frequency ultrasound (42 kHz) assisted ZnO nanostructures

Size and shape tuneable ZnO nanostructures were prepared by a low frequency ultrasound (42 kHz) route using various organic solvents as the reaction media. The crystalline nature, lattice parameters and microstructural parameters such as microstrain, stress and energy density of the prepared ZnO nanostructures were revealed through X-ray diffraction (XRD) analysis. The organic solvents influenced the size and morphology of the ZnO nanostructures, and interesting morphological changes involving a spherical to triangular shaped transition were observed. The visible emission properties and lattice vibrational characteristics of the nanostructures were drastically modified by the changes in size and shape. Raman spectral measurements revealed the presence of multiphonon processes in the ZnO nanostructures. The intensity of the visible emission band was found to vary with the size and morphology of the structures. The strongest visible emission band corresponded to the structure with the largest surface/volume ratio and could be attributed to surface oxygen vacancies. The control over the size and morphology of ZnO nanostructures has been presented as a means of determining the intensity of the visible emission band