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Long N.Q.,Institute of Nuclear Science and Technology | Truong Y.,Dalat Nuclear Research Institute | Hien P.D.,Vietnam Atomic Energy Agency | Binh N.T.,Dalat Nuclear Research Institute | And 3 more authors.
Journal of Environmental Radioactivity | Year: 2012

Radionuclides from the reactor accident at the Fukushima Dai-ichi Nuclear Power Plant were observed in the surface air at stations in Hanoi, Dalat, and Ho Chi Minh City (HCMC) in Vietnam, about 4500 km southwest of Japan, during the period from March 27 to April 22, 2011. The maximum activity concentrations in the air measured at those three sites were 193, 33, and 37 μBq m -3 for 131I, 134Cs, and 137Cs, respectively. Peaks of radionuclide concentrations in the air corresponded to arrival of the air mass from Fukushima to Vietnam after traveling for 8 d over the Pacific Ocean. Cesium-134 was detected with the 134Cs/ 137Cs activity ratio of about 0.85 in line with observations made elsewhere. The 131I/ 137Cs activity ratio was observed to decrease exponentially with time as expected from radioactive decay. The ratio at Dalat, where is 1500 m high, was higher than those at Hanoi and HCMC in low lands, indicating the relative enrichment of the iodine in comparison to cesium at high altitudes. The time-integrated surface air concentrations of the Fukushima-derived radionuclides in the Southeast Asia showed exponential decrease with distance from Fukushima. © 2011 Elsevier Ltd.

PubMed | i Army Medical and Veterinary Research Center, ag Institute Chemii i Techniki Jadrowej, d NRF iThemba LABS, z Institute Investigaciones Biologicas Clements Estable and 34 more.
Type: Journal Article | Journal: International journal of radiation biology | Year: 2016

Two quality controlled inter-laboratory exercises were organized within the EU project Realizing the European Network of Biodosimetry (RENEB) to further optimize the dicentric chromosome assay (DCA) and to identify needs for training and harmonization activities within the RENEB network.The general study design included blood shipment, sample processing, analysis of chromosome aberrations and radiation dose assessment. After manual scoring of dicentric chromosomes in different cell numbers dose estimations and corresponding 95% confidence intervals were submitted by the participants.The shipment of blood samples to the partners in the European Community (EU) were performed successfully. Outside the EU unacceptable delays occurred. The results of the dose estimation demonstrate a very successful classification of the blood samples in medically relevant groups. In comparison to the 1st exercise the 2nd intercomparison showed an improvement in the accuracy of dose estimations especially for the high dose point.In case of a large-scale radiological incident, the pooling of ressources by networks can enhance the rapid classification of individuals in medically relevant treatment groups based on the DCA. The performance of the RENEB network as a whole has clearly benefited from harmonization processes and specific training activities for the network partners.

PubMed | Dalat Nuclear Research Institute, Nanyang Technological University and National University of Singapore
Type: | Journal: European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V | Year: 2016

The conventional bulk mixing method to prepare amorphous drug-polysaccharide nanoparticle complex (or drug nanoplex in short) has a major drawback in the lack of size control for the nanoplex produced, hence limiting its potential applications as a supersaturating drug delivery system for bioavailability enhancement of poorly soluble drugs. For this reason, we developed a continuous millifluidic synthesis platform of the drug nanoplex exhibiting high size tunability using curcumin (CUR) and chitosan (CHI) as the models for drug and polysaccharides, respectively. The nanoplex size tunability was achieved by controlling the residence time of the CUR and CHI solutions in the millifluidic reactor, where their slow diffusive mixing at the liquid-liquid interface resulted in a well-regulated nanoplex growth as a function of the residence time. The effects of the preparation pH, molecular weight of CHI, millifluidic tube diameter, and flowrate on the nanoplex size tunability were investigated from which the optimal preparation condition was determined. At the optimal condition, the CUR nanoplex was roughly 115nm in size with zeta potential of 15mV and 72% (w/w) CUR payload. The millifluidic synthesis also maintained the high CUR utilization rate (80%) exhibited by the bulk mixing method. Most importantly, the ability to produce significantly smaller nanoplex (sixfold smaller) via millifluidics led to the generation of higher (8.5 of CUR saturation solubility) and prolonged (8h) supersaturation level. These results bode well for the bioavailability enhancement potential of the drug nanoplex.

Tan V.H.,Agency for Radiation and Nuclear Safety | Son P.N.,Dalat Nuclear Research Institute
Journal of Physics: Conference Series | Year: 2016

The thermal neutron radiative capture cross section for186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations. © Published under licence by IOP Publishing Ltd.

Son P.N.,Dalat Nuclear Research Institute | Hai N.X.,Dalat Nuclear Research Institute
Journal of Physics: Conference Series | Year: 2016

Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of232Th were exactly calculated by the numerical method with using the DHP code. © Published under licence by IOP Publishing Ltd.

Nakamura T.,Kyushu University | Vo Doan H.D.,Dalat Nuclear Research Institute | Kotoh K.,Kyushu University
Energy Procedia | Year: 2013

We have considered a fuel cycle scheme for multi-recycling of plutonium recovered from spent UO2 fuels of LWRs. Plutonium is to be partially loaded into the next LWRs in the form of MOX fuels with UO2 fuels made by re-enrichment of uranium recovered from spent fuels of LWRs. We consider to recycle plutonium in combination with uranium multi-recycling system previously reported, which can provide uranium fuels for not only fully UO 2 fueled PWRs but also partially MOX fueled PWRs. The results of the process system analysis suggest that the proposed scheme makes it possible to recycle plutonium in succession. © 2013 The Authors.

Son P.N.,Dalat Nuclear Research Institute | Anh T.T.,Dalat Nuclear Research Institute | Vu C.D.,Dalat Nuclear Research Institute | Tan V.H.,Vietnam Atomic Energy Institute
Journal of the Korean Physical Society | Year: 2011

Thermal neutron capture cross-sections and resonance integrals for 69Ga and 71Ga were measured by the activation method. The experimental samples with and without a cylindrical Cd-shield case 1 mm in thickness were irradiated in the neutron field of the thermal column facility of Dalat research reactor. The induced activities in the samples were measured by using a high-resolution HPGe detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the 69Ga(n,γ)70Ga and 71Ga(n,γ)72Ga reactions have been obtained relative to the reference values of the 197Au(n,γ)198Au reaction with σ0 = 98.65 ± 0.09 barn and I0 = 1550 ± 28 barn. The necessary correction factors for thermal neutron and resonance neutron self-shielding effects were taken into account in the determinations. The present results are discussed and compared with the evaluated data from ENDF/BVII, JEFF 3.0 and JENDL 3.3.

Hieu T.Q.,Ho Chi Minh City University of Technology | Tuan N.N.,Dalat Nuclear Research Institute | Van Tan L.,Ho Chi Minh City Industrial University
Asian Journal of Chemistry | Year: 2011

The work describes a new 1:1 complex of o-ester tetra azophenyl calix[4]arene (TEAC) with Th(IV) at pH 4-5 has found. The FTIR, H NMR, Raman spectra of calix[4]arene and its Th(IV) complex had also checked. Based on complex formation, a new method has been developed to determine thorium in monazite sand. The sand samples are decomposed by mixed acid (conc. H2SO4 and HF) in platinum crucible, after cooling, the residue was dissolved in dilute HCl and thorium is separated together with the lanthanides in the form of oxalate from zirconium, iron and the phosphate ion. The oxalate precipitate is dissolved in concentration nitric acid. After that, Th(IV) will be formed complex with o-ester tetra azophenyl calix[4]arene in acetate buffer solution. The absorbance of complex solution was measured at 520 nm against water as blank.

PubMed | Dalat Nuclear Research Institute and Kyushu University
Type: | Journal: Carbohydrate polymers | Year: 2016

Sodium Carboxymethyl Cellulose (CMCNa)/Sodium Styrene Sulfonate (SSS) hydrogels with grafted and crosslinked polymeric networks were prepared by -radiation at atmosphere condition. The obtained hydrogels were characterized by gel fraction, swelling ratio, TGA and FTIR spectroscopy. The results showed the ratio of CMC and SSS 1:0 gave the highest gel fraction, compared with other ratios. The swelling capacity increased by increasing SSS content due to the presence of SO

PubMed | University of Science, Dalat Nuclear Research Institute and Ho Chi Minh City University of Natural Sciences
Type: | Journal: Radiation protection dosimetry | Year: 2016

Besides the most common methods of internal dose assessment from inhaled

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