14 research outputs found
Finite elements based approaches for the modelling of radial crack formation upon Vickers indentation in silicon nitride ceramics
© 2019 By having superior properties silicon nitride ceramics can be considered as the state-of-the-art material in the bearing industry. Vickers indentation of this material is typically accompanied by formation of cracks visible on surface. Two Finite Elements models are developed in the current work: the first model is based on fracture mechanics and the second on cleavage stress criterion. Plastic behavior of silicon nitride is included in the modeling, and since little is known on the plasticity of this material, the Drucker-Prager model (used for non-metallic materials)along with the classical J2-plasticity are explored. The results of the fracture mechanics based model correlate well with experimental results in terms of surface crack length. The numerical results in terms of the morphology of the indented zone (including cracks and plastic zone)are provided by the stress criterion based model, and these results correlate well too, with the experimental data
ZO-1 Stabilizes the Tight Junction Solute Barrier through Coupling to the Perijunctional Cytoskeleton
ZO-1 binds numerous transmembrane and cytoplasmic proteins and is required for assembly of both adherens and tight junctions, but its role in defining barrier properties of an established tight junction is unknown. We depleted ZO-1 in MDCK cells using siRNA methods and observed specific defects in the barrier for large solutes, even though flux through the small claudin pores was unaffected. This permeability increase was accompanied by morphological alterations and reorganization of apical actin and myosin. The permeability defect, and to a lesser extent morphological changes, could be rescued by reexpression of either full-length ZO-1 or an N-terminal construct containing the PDZ, SH3, and GUK domains. ZO-2 knockdown did not replicate either the permeability or morphological phenotypes seen in the ZO-1 knockdown, suggesting that ZO-1 and -2 are not functionally redundant for these functions. Wild-type and knockdown MDCK cells had differing physiological and morphological responses to pharmacologic interventions targeting myosin activity. Use of the ROCK inhibitor Y27632 or myosin inhibitor blebbistatin increased TER in wild-type cells, whereas ZO-1 knockdown monolayers were either unaffected or changed in the opposite direction; paracellular flux and myosin localization were also differentially affected. These studies are the first direct evidence that ZO-1 limits solute permeability in established tight junctions, perhaps by forming a stabilizing link between the barrier and perijunctional actomyosin
Microdiffraction analysis of structure of silumin’s high-velocity cellular crystallization
Epithelial myosin light chain kinase expression and activity are upregulated in inflammatory bowel disease
Strength estimation of silicon nitride ceramics using a round-notched specimen subjected to shearing-tool indentation
Extracorporeal Membrane Oxygenation Causes Loss of Intestinal Epithelial Barrier in the Newborn Piglet
Endoscopic complications avoidance and management
The frequency of endoscopic complications is likely to rise owing to the increased number of indications for therapeutic procedures and also to the increased complexity of endoscopic techniques. Informed patient consent should be obtained as part of the procedure. Prevention of endoscopic adverse events is based on knowledge of the relevant risk factors and their mechanisms of occurrence. Thus, suitable training of future gastroenterologists and endoscopists is required for these complex procedures. When facing a complication, appropriate management is generally provided by an early diagnosis followed by prompt therapeutic care tailored to the situation. The most common complications of diagnostic and therapeutic upper gastrointestinal endoscopy, retrograde cholangiopancreatography, small bowel endoscopy and colonoscopy are reviewed here. Different modalities of medical, endoscopic or surgical management are also considered. © 2012 Macmillan Publishers Limited. All rights reserved.SCOPUS: re.jinfo:eu-repo/semantics/publishe