CNT-grafted glass fibers as a smart tool for epoxy cure monitoring, UV-sensing and thermal energy harvesting in model composites

A 'hierarchical' reinforcement of glass fibers (GFs) chemically grafted with multiwall carbon nanotubes (MWCNTs) has been utilized for epoxy cure monitoring, UV-sensing, and thermal energy harvesting in model composites. MWCNTs were covalently attached to the surface of glass fiber yarns (GF-yarns) in a dip-coating deposition process. Hereafter, the hybrid yarns are denoted as GF-CNT. Scanning electron microscopy (SEM) demonstrated a highly uniform CNT-layer covering the fiber surfaces. In turn, GF-CNT reached a maximum conductivity of 2060 S m-1, being of the same order of magnitude as the CNT-only bucky paper film. A GF-CNT in a uni-directional arrangement within a dog-bone shaped mould was employed for epoxy cure monitoring, recording the resistance changes during the curing process. In addition, three yarns connected in parallel highlighted the potential for detecting the resin position upon filling a mould. GF-CNT embedded in epoxy has been proposed also as an integrated non-invasive composite UV-sensor, allowing polymer matrix health monitoring. Besides, the semi-conductive nature of MWCNTs offered the opportunity of thermoelectric energy harvesting by the GF-CNT and its model composite when exposed to a temperature gradient. This work reports some new insights into and potential of fiber/CNT multi-scale reinforcements giving rise to multi-functional structural composites. © 2016 The Royal Society of Chemistry

Gender does not influence angiogenesis and arteriogenesis in a rabbit model of chronic hind limb ischemia

Objective: Estrogen administration promotes angiogenesis and perfusion in oophorectomized rabbits with chronic limb ischemia. In the present study we tested whether gender affects angiogenesis and arteriogenesis in a rabbit model of chronic hind limb ischemia. Methods. and results: Ischemia was induced in one hind limb of five oophorectomized (Ooph), seven non-oophorectomized (NonOoph) female and eight male New Zealand White rabbits by excision of the femoral artery. Ten days after the induction of ischemia (day 0) and at days 15 and 30 systolic calf blood pressure was measured in the ischemic and non-ischemic hind limbs. Revascularization in the ischemic limb was expressed as ischemic/normal limb blood pressure, capillary/muscle fiber density, and non-capillary, non-lymphatic vessels/muscle fiber density after examination of light microscopic sections taken from the abductor muscle of the ischemic limb at the time of death (day 30). Ischemic/normal blood pressure at day 30 in males was 0.62 +/- 0.22, in NonOoph 0.64 +/- 0.09 (P=ns vs. males) and in Ooph 0.39 +/- 0.05 (P < 0.05 vs. males and NonOoph), (F= 4.69, P= 0.02). Ischemic capillary/muscle fiber in males was 0.96 ± 0.09, in NonOoph 0.95 ± 0.06 (P = ns vs. males) and in Ooph 0.83 ± 0.09 (P < 0.05 vs. males and NonOoph), (F= 5.93, P= 0.01). Ischemic non-capillary, non-lymphatic vessels/muscle fiber density in males was 0.11 +/- 0.02, in NonOoph 0.12 +/- 0.03 (P= ns vs. males) and in Ooph 0.08 +/-0.02 (P < 0.05 vs. NonOoph), (F= 5.05, P= 0.02). Conclusion: Gender does not influence angiogenesis and arteriogenesis in the rabbit model of chronic hind limb ischemia. However, estrogen deficiency induced by oophorectomy negatively affects angiogenesis and arteriogenesis. © 2003 Elsevier Ireland Ltd. All rights reserved