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Shape-memory materials hold great potential to impart medical devices with functionalities useful during implantation, locomotion, drug delivery, and removal. However, their clinical translation is limited by a lack of non-invasive and precise methods to trigger and control the shape recovery, especially for devices implanted in deep tissues. In this study, the application of image-guided high-intensity focused ultrasound (HIFU) heating is tested. Magnetic resonance-guided HIFU triggered shape-recovery of a device made of polyurethane urea while monitoring its temperature by magnetic resonance thermometry. Deformation of the polyurethane urea in a live canine bladder (5 cm deep) is achieved with 8 seconds of ultrasound-guided HIFU with millimeter resolution energy focus. Tissue sections show no hyperthermic tissue injury. A conceptual application in ureteral stent shape-recovery reduces removal resistance. In conclusion, image-guided HIFU demonstrates deep energy penetration, safety and speed.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10847440 | PMC |
http://dx.doi.org/10.1038/s41467-024-45437-2 | DOI Listing |
Materials (Basel)
August 2025
Department of Mechanics and Applied Computer Science, Faculty of Mechanical Engineering, Bialystok University of Technology, 45C Wiejska St, 15-351 Bialystok, Poland.
Novel polyester-polyurethane polymeric materials were formulated by combining a natural aliphatic polyester, poly(3-hydroxybutyrate) (P3HB), with a synthetic aliphatic polyurethane via melt blending. The resulting fully biodegradable compositions were functionally modified through the incorporation of urea, with the aim of enabling post-consumer utilization of the material residues as nitrogen-rich fertilizers. The fabrication process was systematically established and optimized, focusing on homogeneous blending and processability.
View Article and Find Full Text PDFACS Omega
August 2025
Institute of Plant Nutrition, Resources and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China.
Polymer coated fertilizers (PCFs) play a crucial role in the sustainable development of precision agriculture. However, conventional petroleum-based coating materials for PCFs are non-degradable and depend on non-renewable resources. Thus, biobased coatings, particularly those derived from vegetable oils, are promising alternatives.
View Article and Find Full Text PDFJACS Au
July 2025
Centre For Membrane Separations, Adsorption, Catalysis and Spectroscopy for Sustainable Solutions (cMACS), Celestijnenlaan 200F, Post box 2454, 3001 Leuven, Belgium.
Polyurethane ranks as one of the most significant plastics globally in terms of production volume and economic value, serving a crucial role in modern society. Due to complexities in the chemical recycling of polyurethane, replacement rates in recycled materials tend to be low, and the recovery of the isocyanate-derived aromatic compounds is often neglected. While many recycling efforts try to address these shortcomings, they primarily focus on TDI-based flexible foams, as recycling rigid PU foams is more challenging.
View Article and Find Full Text PDFPolymers (Basel)
June 2025
Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, LV-1006 Riga, Latvia.
This study explores how production technology influences spray-applied rigid polyurethane (PUR) foam insulation's cryogenic performance. In cryogenic applications such as liquid gas storage, insulation must minimise heat transfer and resist moisture ingress under severe thermal gradients. Experimental aluminium vessels were insulated with PUR foam of varying thicknesses and surface conditions-rough, machined smooth, and with a urea-based protective coating-and then tested using dynamic boil-off of liquid nitrogen (LN).
View Article and Find Full Text PDFSmall
August 2025
College of Chemistry, Liaoning University, 66 Chongshan Middle Road, Huanggu District, Shenyang, Liaoning, 110036, P. R. China.
There has long been a trade-off between mechanical strength and toughness in polyurethane (PU) elastomers. This limitation arises from stress concentration and inefficient energy dissipation within the rigid domains. Therefore, a gradient hydrogen bonding topology strategy is proposed that constructs hierarchical crosslinked networks incorporating both strong (urea-based) and weak (ester-based) hydrogen bonds.
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