3,672 research outputs found
Polymeric micelles and the Dy-166/Ho-166 generator: A study of the loading mechanism of Dy/Dy-166 and Ho-166 into PCL-b-PEO polymeric micelles for imaging and cancer treatment
No full textA radioisotope used in radionuclide therapy is Holmium-166 (Ho-166). The treatment effectiveness of Ho-166 could be improved by the use of a so called in vivo Dysprosium-166(Dy-166)/Ho-166 generator. The application of this generator is hindered by an effect called internal conversion (IC). This affect can arise after the decay of Dy-166 to Ho-166, which can cause separation of Ho-166 from its carrier.Polymeric micelles might form a solution in the application of the Dy-166/Ho-166 generator in radionuclide therapy. The main goal of this thesis was to investigate and understand the loading mechanism of metallic species and polymeric micelles with a focus on the loading of Dy/Dy-166 and Ho-166. It was found that it was not effective to load metallic species (Dy/Dy-166) as free ions or as solid precipitates. Loading metallic species as aqueous hydroxides showed to be crucial for achieving a good loading and high stability. The second goal was to study if polymeric micelles were able to retain Ho-166 inside their core under the effects of internal conversion. No additional losses of Ho-166 were found when Dy/Dy-166 and Ho-166 were loaded into the micelles. It was concluded that the PCL-PEO micelles prevented the loss of Ho-166 under internal conversion effects.Applied Science
Preparation and Properties Investigation of Neutron Absorber Material Mo-Tb-Dy and Y-Tb-Dy Alloys
No full textControl rods with low worth absorber materials may provide a mechanical means of making relatively small adjustments in core reactivity. Mo-Tb-Dy and Y-Tb-Dy alloys were developed to obtain appropriate nuclear performance for low worth absorber material. The two alloys were prepared by powder metallurgy technology and vacuum melting technology individually. To clarify the effects of Mo and Y diluents, Tb-Dy was also prepared to be compared. The microstructures were analyzed by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). The experiment results showed that homogeneous microstructures were obtained. Out-pile properties, including mechanical properties, thermal conductivities, thermal expansion, corrosion resistance properties and ion irradiation properties were measured and analyzed. Y-Tb-Dy has similar properties with Tb-Dy. With temperature increasing, yield strengths of Tb-Dy and Y-Tb-Dy decreases largely while Mo-Tb-Dy decreases slightly. Thermal conductivities of Mo-Tb-Dy were four times more than Tb-Dy and Y-Tb-Dy. Mo element significantly increases thermal conductivity. Tb-Dy and Y-Tb-Dy showed severe corrosion and became powders in 280°C/10MPa de-ionized water while Mo-Tb-Dy had very slow corrosion rate. All three alloys were irradiated at 400∼700°C for 25 displacement per atom (dpa). No voids was observed for Tb-Dy and Y-Tb-Dy. Void diameter increases and its density decreases with temperature increasing for Mo-Tb-Dy. Maximum irradiation swelling rate with 0.5% was observed at 500°C. Irradiation swelling significantly decreased with increasing irradiation temperature.</jats:p
Thermal stability, magnetic and mechanical properties of Fe-Dy-B-Nb bulk metallic glasses with high glass-forming ability
No full textThe effects of Dy addition on the thermal stability, glass-forming ability (GFA), magnetic and mechanical properties of quaternary (Fe0.76-xDyxB0.24)(96)Nb-4 (x = 0-0.07) bulk metallic glasses (BMGs) were investigated. Increasing Dy content from x = 0 to 0.05 extended the supercooled liquid region up to 112 K, allowing the fabrication by copper mold casting of BMGs rods with 5.5 mm in diameter. The high GFA was found to be related to the structure of primary crystalline phase. For the x = 0.05 alloy, the competitive formation process of the complex Fe23B6 and Dy2Fe14B phases enabled to obtain the largest GFA value. Moreover, the Fe-Dy-B-Nb BMGs exhibited good soft-magnetic properties, i.e., high saturation magnetization of 1.18-0.56 T and low coercive force of 1.9-21.6 A/m. In addition, the glassy alloy rods also showed high compressive fracture strengths of 4400-4150 MPa and high Vickers hardness of 1110-1090 kg/mm(2). Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved
The development of NURBS curve interpolator controlling the surface roughness in direction of tool feeding for ball end milling
No full textIncomplete two-manifold mesh-based tool path generation
No full textThis paper presents a new paradigm for three-axis tool path generation based on an incomplete two-manifold mesh model; namely, an inexact polyhedron. When geometric data is transferred from one system to another system and tessellated for tool path generation, the model does not have any topological data between meshes and facets. In contrast to the existing polyhedral machining approach, the proposed method generates tool paths from an incomplete two-manifold mesh model. In order to generate gouge-free tool paths, cutter-location meshes (CL-meshes) are generated by offsetting boundary edges, boundary vertices, and facets. The CL-meshes are sliced by machining planes and the calculated intersections are sorted, trimmed, and linked. The grid method is used to reduce the computing time when range searching problems arise. The method is fully implemented and verified by machining an incomplete two-manifold mesh model
Crystallographic and magnetic properties of R3Fe29-xVxN4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy)
No full textA systematic investigation of crystallographic and magnetic properties of nitride R3Fe29-xVxN4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Nitrogenation leads to a relative volume expansion of about 6%. The lattice constants and unit cell volume decrease with increasing rare-earth atomic number from Nd to Dy, reflecting the lanthanide contraction. On average, the Curie temperature increases due to the nitrogenation to about 200 K compared with its parent compound. Generally speaking, nitrogenation also results in a remarkable improvement of the saturation magnetization and anisotropy fields at 4.2 K and room temperature for R3Fe29-xVxN4 compared with their parent compounds. The transition temperature indicates the spin reorientations of R3Fe29-xVxN4 for R = Nd and Sm are at around 375 and 370 K which are higher than that of R3Fe29-xVx, for R = Nd and Sm 145 and 140 K, respectively. The magnetohistory effects of R3Fe29-xVxN4 (R = Ce, Nd, and Sm) are observed in low fields of 0.04 T. After nitrogenation the easy magnetization direction of Sm3Fe26.7V2.3 is changed from an easy-cone structure to the b-axis. As a preliminary result, a maximum remanence B-r of 0.94 T, an intrinsic coercivity mu(0)H(C) of 0.75 T, and a maximum energy product (B H)(max) of 108.5 kJ m(-3) for the nitride magnet Sm3Fe26.7V2.3N4 are achieved by ball-milling at 293 K
CL surface deformation approach for a 5-axis tool path generation
No full textIn this paper, the 5-axis tool path that has been generated on the cutter contact (CC) surface is generated on the cutter location (CL) surface, and the CL surface deformation approach that inversely deforms the 3-axis tool path generated on the deformed CL surface to a 5-axis tool path is introduced. The CL point computation and interference check based on the CL surface is faster and more robust than that based on the CC surface. The proposed CL surface deformation approach can be used if the orientation of the cutter is predefined. By the CL surface deformation approach, the 5-axis tool path generation time can be reduced to that of a 3-axis, since the complexity of a CL surface deformation is linear and because the 3-axis tool path generation and gouge removal algorithms are used at the deformed CL surface
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