Rheological evaluation of pretreated cladding removal waste

Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid

Non-invasive tracking of injected bone marrow mononuclear cells to injury and implanted biomaterials

Biomaterial scaffolds enhancing the engraftment of transplanted bone-marrow mononuclear cells (BM-MNC) have enormous potential for tissue regeneration applications. However, development of appropriate materials is challenging given the precise microenvironments required to support BM-MNC engraftment and function. In this study, we have developed a non-invasive, real-time tracking model of injected BM-MNC engraftment to wounds and implanted biomaterial scaffolds. BM-MNCs, encoded with firefly luciferase and enhanced GFP reporter genes, were tail vein injected into subcutaneously wounded mice. Luciferase-dependent cell bioluminescence curves revealed our injected BM-MNCs homed to and engrafted within subcutaneous wound sites over the course of 21days. Further immunohistochemical characterization showed that these engrafted cells drove functional changes by increasing the number of immune cells present at early time points and remodelling cell phenotypes at later time points. Using this model, we subcutaneously implanted electrospun polycaprolactone (PCL) and PCL/Collagen scaffolds, to determine differences in exogenous BM-MNC response to these materials. Following BM-MNC injection, immunohistochemical analysis revealed a high exogenous BM-MNC density around the periphery of PCL scaffolds consistent with a classical foreign body response. In contrast, transplanted BM-MNCs engrafted throughout PCL/Collagen scaffolds indicating an improved biological response. Importantly, these differences were closely correlated with the real-time bioluminescence curves, with PCL/Collagen scaffolds exhibiting a∼2-fold increase in maximum bioluminescence compared with PCL scaffolds. Collectively, these results demonstrate a new longitudinal cell tracking model that can non-invasively determine transplanted BM-MNC homing and engraftment to biomaterials, providing a valuable tool to inform the design scaffolds that help augment current BM-MNC tissue engineering strategies.Tracking the dynamic behaviour of transplanted bone-marrow mononuclear cells (BM-MNCs) is a long-standing research goal. Conventional methods involving contrast and tracer agents interfere with cellular function while also yielding false signals. The use of bioluminescence addresses these shortcomings while allowing for real-time non-invasive tracking in vivo. Given the failures of transplanted BM-MNCs to engraft into injured tissue, biomaterial scaffolds capable of attracting and enhancing BM-MNC engraftment at sites of injury are highly sought in numerous tissue engineering applications. To this end, the results from this study demonstrate a new longitudinal tracking model that can non-invasively determine exogenous BM-MNC homing and engraftment to biomaterials, providing a valuable tool to inform the design of scaffolds with implications for countless tissue engineering applications.Richard P.Tan, Bob S.L.Lee, Alex H.P.Chan, Sui Ching G.Yuen, Juichien Hung, Steven G.Wise, Martin K.C.N