Braided rivers play a significant role in replenishing groundwater, but our understanding of how these recharge rates fluctuate over time remains limited. Traditional techniques for gauging groundwater recharge are ineffective for studying complex braided river systems due to their insufficient spatiotemporal resolution. To address this gap, active-distributed temperature sensing (A-DTS) was used.
View Article and Find Full Text PDFVolcanic eruptions that occur without warning can be deadly in touristic and populated areas. Even with real-time geophysical monitoring, forecasting sudden eruptions is difficult, because their precursors are hard to recognize and can vary between volcanoes. Here, we describe a general seismic precursor signal for gas-driven eruptions, identified through correlation analysis of 18 well-recorded eruptions in New Zealand, Alaska, and Kamchatka.
View Article and Find Full Text PDFCurrent synthetic vascular grafts have poor patency rates in small diameter applications (<6 mm) due to intimal hyperplasia arising from a compliance mismatch between the graft and native vasculature. Enormous efforts have focused on improving biomechanical properties; however, polymeric grafts are often constrained by an inverse relationship between burst pressure and compliance. We have developed a new, semi-interpenetrating network (semi-IPN) approach to improve compliance without sacrificing burst pressure.
View Article and Find Full Text PDFJ Biomed Mater Res B Appl Biomater
February 2015
Coronary artery bypass grafting is one of the most commonly performed major surgeries in the United States. Autologous vessels such as the saphenous vein are the current gold standard for treatment; however, synthetic vascular prostheses made of expanded poly(tetrafluoroethylene) or poly(ethylene terephthalate) are used when autologous vessels are unavailable. These synthetic grafts have a high failure rate in small diameter (<4 mm) applications due to rapid reocclusion via intimal hyperplasia.
View Article and Find Full Text PDFJ Biomater Sci Polym Ed
November 2014
The rapid growth of regenerative medicine and drug delivery fields has generated a strong need for improved polymeric materials that degrade at a controlled rate into safe, non-cytotoxic by-products. Polyurethane thermoplastic elastomers offer several advantages over other polymeric materials including tunable mechanical properties, excellent fatigue strength, and versatile processing. The variable segmental chemistry in developing resorbable polyurethanes also enables fine control over the degradation profile as well as the mechanical properties.
View Article and Find Full Text PDFThe resistance to oxidation and environmental stress cracking of poly(carbonate urethanes) (PCUs) has generated significant interest as potential replacements of poly(ether urethanes) in medical devices. Several in vitro models have been developed to screen segmented polyurethanes for oxidative stability. High concentrations of reactive oxygen intermediates produced by combining hydrogen peroxide and dissolved cobalt ions has frequently been used to predict long-term oxidative degradation with short-term testing.
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