Search

This paper studies the buckling problem of nanowires (NWs) and carbon nanotubes (CNTs) freely standing on a substrate and subjected to distributed axial loads. NWs and CNTs are modeled as elastic nanocolumns and due to their high Young's modulus, the substrate is reasonably considered as an elastic foundation. The junction between the nanocolumn and substrate is described by a rotational spring. A new approach is suggested to solve the stability of axially-loaded nanocolumns with a rotational spring junction. An approximation expression for the critical load with high accuracy is derived in closed form. The results are confirmed for a rectangular Ag NW by FEM. Numerical results of the critical length of NWs and CNTs under their own weight are presented in graphs and tables. Obtained results indicate that the critical length is sensitive to small Young's modulus of the elastic substrate and becomes insensitive for enough large Young's modulus of the elastic substrate. When the rotational spring stiffness is sufficiently large, the case reduces to a free-standing NW on a rigid foundation.

Background Cancer-induced bone pain remains a clinical challenge due to the poor understanding of the mechanisms. Recent study revealed extracellular adenosine triphosphate (ATP) and P2X receptors may be implicated in nociceptive signalling under cancer pain state. Therefore, here we investigated the potential role of P2X3 receptor in a rat model of bone cancer pain. Methods Walker 256 tumour cells were inoculated into the left tibia of Wistar rats. The model was verified by X-ray imaging, pathology and behaviour examinations. The expression of P2X3 receptors in dorsal root ganglia (DRG) was examined. Functional significance of altered P2X3 receptors was investigated by measuring influx upon α,β-meATP stimulation in acutely dissociated DRG neurons. Moreover, A-317491, an antagonist of P2X3 receptors, was administrated intrathecally or locally to evaluate its analgesia effect in the cancer pain animals. Results The P2X3 receptor was up-regulated for about 50% in DRG neurons in rats with bone cancer at both protein and mRNA levels and correlated with the pain behaviour in bone cancer rats. A 51.9% increase of α,β-me ATP (10 μM, for 4 s) evoked transient response currents and a higher percentage of neurons responsive to the application of α,β-me ATP was detected in bone cancer rats. Intrathecal or local injection of A-317491 significantly attenuated pain behaviour induced by bone cancer. Conclusions These results suggest that the P2X3 receptor is functionally up-regulated in DRG in cancer rats. P2X3 receptor is a promising target for therapeutic intervention in cancer patients for pain management.