Durability of crosslinked polyethylene in human-contact applications: Stabilisation challenges

Highly crosslinked polyethylene polymers (XLPE) are used in many human-contact applications that require assurance on aspects of durability, longevity and safety. The work described in this paper focuses on applications in the medical field and in the construction industry. These are related to the use of XL-UHMWPE for articulating surfaces in orthopaedic implants particularly in total hip and knee replacements, and the use of XL-HDPE for potable water pipes. Safety, performance and durability of the end-use products are mandatory for their approval and use in such applications. However, it has long been recognised that the stabilisation of such highly crosslinked polymers by commercial antioxidants (AO) faces many challenges including the possible interference of the AOs with the crosslinking step, as well as the issues of safety associated with AO leaching and migration of into the human-environment. Here, the effect of AOs on the long-term oxidative stability of the end-use polymer artefacts in these applications is examined and compared with that obtained with some new alternative stabilisation systems. Results show that, in both applications, it was possible to achieve superior levels of retention of the AO in the polymer and long-term thermal stabilising (LTTS) performance (ageing) with minimum interference with the crosslinking process, thereby addressing issues of stabilisation, health and safety of polymers used in direct contact with the human environment

Less adhesiolysis and hernia repair during completion proctocolectomy after laparoscopic emergency colectomy for ulcerative colitis

The aim of this study was to determine whether the need for adhesiolysis during completion proctectomy (CP) with ileopouch anal anastomosis (IPAA) is influenced by the surgical approach of the initial emergency colectomy for ulcerative colitis and the hospital setting. One hundred consecutive patients who underwent CP with IPAA in our center between January 1999 and April 2010 were included. Emergency colectomy had been performed laparoscopically in 30 of 52 patients at the Academic Medical Center Amsterdam and in 6 of 48 patients at referring hospitals. Case files of these patients were retrospectively reviewed. Significantly more extensive adhesiolysis was performed after open compared to laparoscopic colectomy (47 vs. 6%, P <0.001). In univariate analysis, emergency colectomy at a referring hospital was also predictive for adhesiolysis (P = 0.003), but the open approach for the initial colectomy was the only independent predictive factor for the need for adhesiolysis (P <0.001) in a multivariable ordinal logistic regression analysis. Operating time of CP was significantly longer when limited [18 (95% CI = 0-36) min] or extensive [55 (35-75) min] adhesiolysis had to be performed. The interval to CP was longer after open colectomy and after colectomy performed at a referring hospital. Significantly more incisional hernia corrections during CP were performed after open emergency colectomy (14 vs. 0%, P = 0.024). Overall morbidity and postoperative hospital stay of CP were not related to the surgical approach or the hospital setting of the emergency colectomy. Laparoscopic as opposed to open emergency colectomy is associated with less adhesiolysis, fewer incisional hernias, and a shorter interval to completion proctectom

EON-ROSE and the Canadian Cordillera Array – Building Bridges to Span Earth System Science in Canada

EON-ROSE (Earth-System Observing Network - Réseau d’Observation du Système terrestrE) is a new initiative for a pan-Canadian research collaboration to holistically examine Earth systems from the ionosphere into the core. The Canadian Cordillera Array (CC Array) is the pilot phase, and will extend across the Cordillera from the Beaufort Sea to the U.S. border. The vision for EON-ROSE is to install a network of telemetered observatories to monitor solid Earth, environmental and atmospheric processes. EON-ROSE is an inclusive, combined effort of Canadian universities, federal, provincial and territorial government agencies, industry, and international collaborators. Brainstorming sessions and several workshops have been held since May 2016. The first station will be installed at Kluane Lake Research Station in southwestern Yukon during the summer of 2018. The purpose of this report is to provide a framework for continued discussion and development.RÉSUMÉEON-ROSE (Earth-System Observing Network - Réseau d’Observation du Système terrestrE) est une nouvelle initiative de collaboration de recherche pancanadienne visant à étudier de manière holistique les systèmes terrestres, depuis l’ionosphère jusqu’au noyau. Le Réseau canadien de la cordillère (CC Array) en est la phase pilote, laquelle couvrira toute la Cordillère, de la mer de Beaufort jusqu’à la frontière étasunienne. L’objectif d’EON-ROSE est d’installer un réseau d’observatoires télémétriques pour suivre en continu les processusterrestres, environnementaux et atmosphériques. EON-ROSE est un effort combiné et inclusif des universités canadiennes, des organismes gouvernementaux fédéraux, provinciaux et territoriaux, de l’industrie et de collaborateurs internationaux. Des séances de remue-méninges et plusieurs ateliers ont été tenus depuis mai 2016. La première station sera installée à la station de recherche du lac Kluane, dans le sud-ouest du Yukon, au cours de l’été 2018. Le but du présent rapport est de fournir un cadre de discussion et de développement continu

Photo-stabilization of biopolymers-based nanocomposites with UV-modified layered silicates

Eco-friendly in-situ stabilised biopolymer nanocomposites based on polyamide 11 (PA11) and polylactic acid (PLA) were prepared by melt mixing in the presence of a modified organo-montmorillonite clay containing a chemically-bound hindered amine UV-stabilising function, [(UV)OM-MMt]. Characterisation of the newly synthesised organo-modifier containing the reactive hindered amine (HAS) UV-stabilising function [(UV)OM] has confirmed a successful synthesis. The (UV)OM was then introduced into NaMMt through ion exchange reaction to prepare the UV stabiliser-bound organo-modified-MMt, [(UV)OM-MMt]. The in-situ stabilised PA11- and PLA- nanocomposites (PA11-(UV)OM-MMt and PLA-(UV)OM-MMt) were characterised and their photoxidative stabilities (under accelerated weathering conditions) were compared with their nanocomposite analogues containing either the organo-modified MMt (OM-MMt) alone (i.e. without UV-stabiliser) or the OM-MMT containing conventionally added commercial hindered amine HAS-UV-stabiliser (Cyasorb® UV-3853). It was found that both of the newly prepared in-situ stabilised PA11- and PLA- nanocomposites gave good clay dispersion and have demonstrated a much higher, especially in PLA-nanocomposites, photo-oxidative stability compared to the corresponding nanocomposites but in the absence, or the presence, of the conventionally added HAS-UV-stabiliser