Chalk River Laboratories

About: Chalk River Laboratories is a based out in . It is known for research contribution in the topics: Neutron diffraction & Neutron scattering. The organization has 2297 authors who have published 2700 publications receiving 73287 citations.

Adipogenic Mesenchymal Stromal Cells from Bone Marrow and Their Hematopoietic Supportive Role: Towards Understanding the Permissive Marrow Microenvironment in Acute Myeloid Leukemia.

Abstract: The role of bone marrow-derived mesenchymal stem/stromal cells (MSCs) in creating a permissive microenvironment that supports the emergence and progression of acute myeloid leukemia (AML) is not well established. We investigated the extent to which adipogenic differentiation in normal MSCs alters hematopoietic supportive capacity and we undertook an in-depth comparative study of human bone marrow MSCs derived from newly diagnosed AML patients and healthy donors, including an assessment of adipogenic differentiation capacity. MSCs from healthy controls with partial induction of adipogenic differentiation, in comparison to MSCs undergoing partial osteogenic differentiation, expressed increased levels of hematopoietic factors and induced greater proliferation, decreased quiescence and reduced in vitro hematopoietic colony forming capacity of CD34+ hematopoietic stem and progenitor cells (HSPCs). Moreover, we observed that AML-derived MSCs had markedly increased adipogenic potential and delayed osteogenic differentiation, while maintaining normal morphology and viability. AML-derived MSCs, however, possessed reduced proliferative capacity and decreased frequency of subendothelial quiescent MSCs compared to controls. Our results support the notion of a bone marrow microenvironment characterized by increased propensity toward adipogenesis in AML, which may negatively impact normal hematopoiesis. Larger confirmatory studies are needed to understand the impact of various clinical factors. Novel leukemia treatments aimed at normalizing bone marrow niches may enhance the competitive advantage of normal hematopoietic progenitors over leukemia cells.

Solidification Analysis of an Al-19 Pct Si Alloy Using In-Situ Neutron Diffraction

Abstract: In-situ neutron diffraction and thermal analysis techniques were used simultaneously to evaluate the kinetics of the nonequilibrium solidification process of an Al-19 pct Si binary alloy. Feasibility studies concerning the application of neutron diffraction for advanced solidification analysis were undertaken to explore its potential for high resolution phase analysis coupled with fraction solid/liquid analysis of phase constituents. Neutron diffraction patterns were collected in a stepwise mode during solidification between 983 K and 793 K (710 °C and 520 °C). The variation of intensity of the diffraction peaks was analyzed and compared to the results of conventional cooling curve analysis. Neutron diffraction was capable of detecting nucleation of the Si phase (primary and eutectic), as well as the Al phase during Al-Si eutectic nucleation. Moreover, neutron diffraction indicated the possibility of detecting the presence of Si peaks at near liquidus temperature and premature nucleation of α-Al prior to Al-Si eutectic temperature. The solid and liquid volume fractions were determined based on the change of intensity of neutron diffraction peaks over the solidification interval. Overall, the volume fraction determined was in good agreement with the results of the cooling curve thermal analysis, as well as calculations using the FactSage software. The potential of neutron diffraction for high resolution melt analysis required for advanced studies of grain refining, eutectic modification, etc. was illustrated. This study will help us better understand the solidification mechanism of Al-Si alloys used for various casting component applications.

Characterization of protein resistant, grafted methacrylate polymer layers bearing oligo(ethylene glycol) and phosphorylcholine side chains by neutron reflectometry.

Abstract: Neutron reflectometry was used to investigate the structures of end-tethered protein resistant polymer layers based on poly(oligo(ethylene glycol) methyl ether methacrylate) [poly(OEGMA)] and poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)]. Layers having different graft densities were studied in both the dry and wet states. A stretched parabolic model was used to fit the neutron data, resulting in a one-dimensional scattering length density profile of the polymer volume fraction normal to the film. Measured in D2O, the cutoff thicknesses of OEGMA and MPC layers at high graft density (0.39 chains/nm2 for OEGMA and 0.30 chains/nm2 for MPC) and a chain length of 200 repeat units were 450 and 470 A, respectively, close to their contour length of 500 A, suggesting that the grafts become highly hydrated when exposed to water. It was also found that at similar graft density and chain length, the volume fraction profiles of poly(OEGMA) and poly(MPC) layers are similar, in line with the authors’ previous results showing that these surfaces have similar protein resistance [W. Feng et al., BioInterphases 1, 50 (2006)]. The possible correlation of protein resistance to water content as indicated by the average number of water molecules per ethylene oxide (Nw,EO) or phosphorylcholine (Nw,PC) moiety was investigated. Nw,EO and Nw,PC, estimated from the volume fraction data, increased with decreasing graft density, and when compared to the reported number of water molecules in the hydration layers of EO and PC residues, led to the conclusion that water content slightly greater than the water of hydration resulted in protein resistant surfaces, whereas water content either less than or greatly in excess of the water of hydration resulted in layers of reduced protein resistance.