• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4611-4619
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• 2024

This study focuses on the development of a curated separation system aimed at separating thorium ions as part of a recovery plan for managing the thorium radionuclide in the rare earth element (REE) processing industry. As a step towards advancing technology readiness, the separation system employs the electrosorption technique, which involves the migration and storage of thorium ions in the electrical double layers on the porous surface of a carbon-based electrode. Using a prototype electrosorption cell operated at an applied voltage of 1.0 V, the system successfully achieved a thorium ion recovery rate of 84.5 ± 0.29 %, with an impressive electrosorption capacity of 105.26 mg-Th/1 g-carbon. Notably, despite the presence of higher concentrations of REE as competing ions, greater selectivity towards thorium was observed which likely attributable to its larger ionic radius, higher electron affinity, and greater distribution coefficient. These findings highlight the efficacy of the curated separation system and its potential to balance between REE economic significance as well as a protection to the environment.

• Journal of Mushroom
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• v.20 no.1
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• pp.22-28
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• 2022

In order to provide basic data for preparing management standards and to verify the safety of the Chinese oak mushroom-derived moisturizing medium-which is synthesized and imported in large quantities-the presence of 321 residual pesticides, 7 heavy metals, and 3 radioactive materials was analyzed in the moisturizer samples. Examination of residual pesticides in seven moisturizing medium samples prepared using the Chinese oak mushroom and three domestic sawdust samples used for mushroom culture revealed the presence of cypermethrin and iprodione in three moisturizer samples, but the contents of these pesticides were below the standard limits. Zn was detected in ten samples, Cu was detected in nine samples, and Ni was detected in four samples, but their contents were below the standard limits. Pb, Cd, Cr, and Hg were not detected in any sample. No radioactive materials were detected in the samples. In addition, fruiting bodies of the oak mushroom were observed in each medium. Examination did not reveal the presence of any residual pesticides or harmful compounds. In this study, the use of the moisturizing medium prepared using the Chinese oak mushroom was found to be safe. As residual pesticides, heavy metals, and radioactivity-even in trace amounts-remain concentrated in the human body, continuous verification of the safety of hazardous substances and pollutants during the systematic cultivation and management of these mushrooms is required.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.174-184
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• 2015

In the present study, the metabolism of [$^{14}C$]butachlor was investigated in rice plant according to the OECD test guideline No. 501. [$^{14}C$]Butachlor was treated as granule to paddy water by application of 1.5 kg ingredient (a.i.)/ha at the 3~4 leave stage of rice plant. At 85 days after treatment (DAT), samples of panicle, foliage, and roots were taken for radioactivity analysis. Upon harvest at 126 DAT, rice plants were separated into brown rice, husk, straw, and root parts. Amounts of total radioactivity absorbed by rice plant ranged from 8.6 to 9.8% of applied radioactivity (AR). Total radioactive residues (TRRs) of rice plant at 126 DAT was the highest as 4.0421 mg/kg (7.3% AR) in the straw followed by 1.4595 mg/kg (2.4% AR) in the root, 0.7257 mg/kg (0.1% AR) in the husk. The lowest level recording 0.1020 mg/kg (0.1% AR) was found in brown rice. Each part was extracted with various solvents and solvent/water mixtures. Greater than 70% of TRRs was readily extractable from foliage, panicle, husk and straw. Only 34.0% of the brown rice and 43% of root based on TRRs were extractable showing that the residues were completely assimilated in the plant tissue. The level of non-extractable radioactivity was ranged from 26.2 to 66.0% of TRRs. From this study, five tentative major metabolites (M1, M2, M3, M4 and M5) were observed in rice extracts. Among the metabolites, 2,6-diethylaniline assigned as M4 was identified in rice plant by comparing to retention time of reference standard. Un-metabolized butachlor was not detected in any fractions. In soil extracts, N-(butoxymethyl)-N-(2,6-diethyl phenyl)acetamide, 2,6-diethylaniline, M2, M3 and M5 were observed. And the concentration of butachlor was low level (ca. 0.03 mg/kg).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.55-61
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• 2013

The recovery of Zr from Zircaloy-4 (Zry-4) cladding hulls using a chlorination method was demonstrated for complete conversion of Zr into $ZrCl_4$. A chlorination reaction was performed by reacting Zry-4 hulls for 8 h under a 70 cc/min $Cl_2$ + 70 cc/min Ar flow at $380^{\circ}C$. The initial weight of the reactant (51.7 g) decreased to 0.49 g after 8 h of operation, which is only 0.95wt% of the initial weight. The weight of the total reaction products was 121.7 g with a high Zr purity of 99.80wt%. Fe and Sn were identified as major (0.18wt%) and minor (0.02wt%) impurities of the reaction products, respectively. It was also shown that Zr exhibited a high recovery ratio of 96.95wt% with a relatively small experimental loss of 2.34wt%. Observation of the reaction residues revealed that the chlorination reaction was dominant along the longitudinal direction, and surface oxide layers remained as reaction residues. The high purity and recovery ratio of Zr proposed the feasibility of the chlorination technique as an effective hull waste treatment method.

• BMB Reports
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• v.38 no.1
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• pp.58-64
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• 2005

Myo-inositol monophosphate phosphatase (IMPP) is a key enzyme in the phosphoinositide cell-signaling system. This study found that incubating the IMPP from a porcine brain with pyridoxal-5'-phosphate (PLP) resulted in a time-dependent enzymatic inactivation. Spectral evidence showed that the inactivation proceeds via the formation of a Schiff's base with the amino groups of the enzyme. After the sodium borohydride reduction of the inactivated enzyme, it was observed that 1.8 mol phosphopyridoxyl residues per mole of the enzyme dimer were incorporated. The substrate, myo-inositol-1-phosphate, protected the enzyme against inactivation by PLP. After tryptic digestion of the enzyme modified with PLP, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. Amino acid sequencing of the peptide identified a portion of the PLP-binding site as being the region containing the sequence L-Q-V-S-Q-Q-E-D-I-T-X, where X indicates that phenylthiohydantoin amino acid could not be assigned. However, the result of amino acid composition of the peptide indicated that the missing residue could be designated as a phosphopyridoxyl lysine. This suggests that the catalytic function of IMPP is modulated by the binding of PLP to a specific lysyl residue at or near its substrate-binding site of the protein.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.26-29
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• 2011

Purpose: The general test method of the Korean Pharmacopeia specifies the test method on the clauses of quality control after manufacturing. According to KFDA Guidance for Medicines, standards of residual solvents regulates the maximum permissible dose of acetonitrile as 400 ppm, ethanol as 5,000 ppm, and acetic acid as 5,000 ppm. This study aims at identifying the type of resiual solvents in the final [F-18]FDG vial of an automatic synthesizer and measure its residual quantity. Materials and Methods: The center carried out residual solvents test of [F-18]FDG injection using Agilent Technologies 7890A with a Flame Ionization Detector. The column of Agilent Technologies 7890A used in measuring of residual solvents was CP WAX column ($30m{\times}0.53mm{\times}1.0{\mu}m$) and analysis condition was split mode 1:1 at the initial temperature $70^{\circ}C$ which was increased $20^{\circ}C/minute$ after two minutes and maintained at the final $140^{\circ}C$ for two minutes. The analysis method was as following: Firstly, ethanol-acetonitrile-acetic acid mixture was classified into four types of concentration (250-25-250 ppm, 1,000-100-1,000 ppm, 3,000-300-3,000 ppm, and 6,000-600-6,000 ppm), and $1.0{\mu}L$ of each type of concentration was injected into gas chromatography followed by an analysis of its peak domain. Then, a calibration-curve by the external standard method was drawn based on the analysis result. Results: While ethanol and acetonitrile were detected in TRACERlab MX, FASTlab had additional acetic acid. The residual quantity of the ethanol-acetonitrile-acetic acid mixture evaluated using the calibration-curve was average 72 ppm ethanol, 54 ppm acetonitrile, and 1030 ppm acetic acid for FASTlab, whereas average 439 ppm ethanol and 79 ppm acetonitrile for TRACERlab MX. This indicated that both of them were within the maximum permissible dose. Conclusion: Solvent residues in the [F-18]FDG injection were all within maximum permissible doses and proper to be used to examine a patient. The result indicated that types and quantities of solvent resides of radioactive pharmaceuticals vary depending on the automatic synthesizer.