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Chen C.-H.,National Health Research Institute | Lin F.-S.,National Health Research Institute | Liao W.-N.,National Health Research Institute | Liang S.L.,National Health Research Institute | And 15 more authors.
Analytical Chemistry

This study aims to establish a 198Au-radiotracer technique for in vivo tracing, rapid quantification, and ex vivo visualization of PEGylated gold nanoparticles (GNPs) in animals, organs and tissue dissections. The advantages of GNPs lie in its superior optical property, biocompatibility and versatile conjugation chemistry, which are promising to develop diagnostic probes and drug delivery systems. 198Au is used as a radiotracer because it simultaneously emits beta and gamma radiations with proper energy and half-life; therefore, 198Au can be used for bioanalytical purposes. The 198Au-tagged radioactive gold nanoparticles (198Au-GNPs) were prepared simply by irradiating the GNPs in a nuclear reactor through the 197Au(n,γ)198Au reaction and subsequently the 198Au-GNPs were subjected to surface modification with polyethylene glycol to form PEGylated 198Au-GNPs. The 198Au-GNPs retained physicochemical properties that were the same as those of GNP before neutron irradiation. Pharmacokinetic and biodisposition studies were performed by intravenously injecting three types of 198Au-GNPs with or without PEGylation into mice; the γ radiation in blood specimens and dissected organs was then measured. The 198Au-radiotracer technique enables rapid quantification freed from tedious sample preparation and shows more than 95% recovery of injected GNPs. Clinical gamma scintigraphy was proved feasible to explore spatial- and temporal-resolved biodisposition of 198Au-GNPs in living animals. Moreover, autoradiography, which recorded beta particles from 198Au, enabled visualizing the heterogeneous biodisposition of 198Au-GNPs in different microenvironments and tissues. In this study, the 198Au-radiotracer technique facilitated creating a trimodality analytical platform for tracing, quantifying and imaging GNPs in animals. © 2014 American Chemical Society. Source

Jan B.Y.-L.,Chien Hsin University of Science and Technology | Tsai S.-C.,Nuclear Science and Technology Development Center | Li Y.-Y.,National Tsing Hua University
Journal of Radioanalytical and Nuclear Chemistry

Sorption and diffusion are important processes for the transport of radionuclides through geomedia from a radioactive disposal facility. In this study, batch tests and through-diffusion experiments were performed to investigate the sorption and diffusion of Se(IV) in crushed granite. Different column lengths of 2, 4 and 8, were employed in the through-diffusion experiments to study the effect of the column length on the apparent diffusion coefficients. Synthetic groundwater (GW) and synthetic seawater (SW) were the liquid phases in these experiments. A two-site kinetic linear model and the Freundlich isotherm were applied to match the sorption/desorption batch data quite closely for both of GW and SW conditions. The retardation factors (R f ) were estimated by comparing the breakthrough curve of Se(IV) with that of HTO. Experimental results indicated that whether in GM or SW solution, the column lengths did not significantly affected D a or R f of Se in crushed granite. © 2014 Akadémiai Kiadó. Source

Lee P.-Y.,National Tsing Hua University | Liu Y.-H.,Nuclear Science and Technology Development Center | Jiang S.-H.,National Tsing Hua University
Applied Radiation and Isotopes

High energy proton beam (>8MeV) is favorable for producing neutrons with high yield. However, the produced neutrons are of high energies. These high energy neutrons can cause severe fast neutron contamination and degrade the BNCT treatment quality if they are not appropriately moderated. Hence, this study aims to briefly discuss the issue, from the viewpoint of fast neutron contamination control, whether high energy proton beam is ideal for AB-BNCT or not. In this study, D2O, PbF4, CaF2, and Fluental™ were used standalone as moderator materials to slow down 1-, 6-, and 10-MeV parallelly incident neutrons. From the calculated results, we concluded that neutrons produced by high energy proton beam could not be easily moderated by a single moderator to an acceptable contamination level and still with reasonable epithermal neutron beam intensity. Hence, much more complicated and sophisticated designs of beam shaping assembly have to be developed when using high energy proton beams. © 2014 Elsevier Ltd. Source

Liu H.C.,ESS Building | Lee M.,ESS Building | Liang T.K.S.,Nuclear Science and Technology Development Center
International Conference on Nuclear Engineering, Proceedings, ICONE

In the Westinghouse design of Advanced Pressurized Water Reactor (AP-1000), a special design named In-Vessel Retention (IVR) is adopted to enhance the heat removal capability through outer wall of reactor vessel during a severe core melt accident. In the present study, RELAP5-3D system thermalhydraulic code is used to simulate the natural convection flow within the water channel of IVR. The results of simulation are substituted into SULTAN, and SBLB Critical Heat Flux correlations developed specifically for this purpose to access the margin of IVR design of AP1000. In the model, the cylindrical part of flow channel of IVR is represented by three-dimensional cylindrical components ?r, ⊙,z?of RELAP5-3D code. The semi-spherical shell of the flow channel is modeled by several inter-connected threedimensional cylindrical components. Each component has different radius. The results demonstrated that the critical heat flux ratio is lowest at the upper equator of the vessel. It has also been predicted that the heat removal capacity of AP1000 IVR is limited between 33 and 48.2 MW, which correspond between 0.35 and 1.08 hours after shutdown. The results demonstrated that IVR of AP1000 can terminate the progression of severe accidents if the attacks of vessel lower head starts about 70 minutes after the initiation of the accident. Copyright © 2012 by ASME. Source

Liu Y.-H.,Nuclear Science and Technology Development Center | Lee P.,National Tsing Hua University | Lin Y.-C.,National Tsing Hua University | Chou F.-I.,Nuclear Science and Technology Development Center | And 4 more authors.
Applied Radiation and Isotopes

Dose estimation of animal experiments affects many subsequent derived quantities, such as RBE and CBE values. It is important to ensure the trustiness of calculated dose of the irradiated animals. However, the dose estimation was normally calculated using simplified geometries and tissue compositions, which led to rough results. This paper introduces the use of treatment planning systems NCTplan and Xplan for the dose estimation. A mouse was taken as an example and it was brought to hospital for micro-PET/CT scan. It was found that the critical organ doses of an irradiated mouse calculated by simplified model were unreliable in comparison to Xplan voxel model. The difference could reach the extent of several tenths percent. It is recommended that a treatment planning system should be introduced to future animal experiments to upgrade the data quality. © 2014 Elsevier Ltd. Source

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