• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.547-556
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• 2011

Two computational methods for determining equilibrium states for the Mark-IV electrorefiner (ER) have been assessed to improve the current computational electrorefiner model developed at University of Idaho. Both methods were validated against measured data to better understand their effects on the calculation of the equilibrium compositions in the ER. In addition, a sensitivity study was performed on the effect of specific unknown activity coefficients-including sodium in molten cadmium, zirconium in molten cadmium, and sodium chloride in molten LiCl-KCl. Both computational methods produced identical results, which stayed within the 95% confidence interval of the experimental data. Furthermore, sensitivity to unavailable activity coefficients was found to be low (a change in concentration of less than 3 ppm).

• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1259-1265
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• 2021

In the present study, a large-area hybrid gamma imaging system was designed by adopting coded aperture imaging on the basis of a large-area Compton camera to achieve high imaging performance throughout a broad energy range (100-2000 keV). The system consisting of a tungsten coded aperture mask and monolithic NaI(Tl) scintillation detectors was designed through a series of Geant4 Monte Carlo radiation transport simulations, in consideration of both imaging sensitivity and imaging resolution. Then, the performance of the system was predicted by Geant4 Monte Carlo simulations for point sources under various conditions. Our simulation results show that the system provides very high imaging sensitivity (i.e., low values for minimum detectable activity, MDA), thus allowing for imaging of low-activity sources at distances impossible with coded aperture imaging or Compton imaging alone. In addition, the imaging resolution of the system was found to be high (i.e., around 6°) over the broad energy range of 59.5-1330 keV.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2107-2111
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• 2023

The aim of the study is the activity concentration measurements of organic and inorganic ¹⁴C in the discharges of JSC "Institute of Nuclear Materials" (INM). In INM the research water-water reactor "IVV-2M" is operating. Collecting of ¹⁴C species was performed using a ¹⁴C sampler with a chromium oxide and platinum catalysts at different temperatures: 400, 550 and 700 ℃. The measurements of ¹⁴C activity were performed using a liquid scintillation counter. The share of organic ¹⁴C in emissions ranged from 0.30 to 0.84 and depends on the temperature of the catalyst, core structure and reactor operating mode.

• Molecules and Cells
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• v.46 no.6
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• pp.374-386
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• 2023

Thermal stress induces dynamic changes in nuclear proteins and relevant physiology as a part of the heat shock response (HSR). However, how the nuclear HSR is fine-tuned for cellular homeostasis remains elusive. Here, we show that mitochondrial activity plays an important role in nuclear proteostasis and genome stability through two distinct HSR pathways. Mitochondrial ribosomal protein (MRP) depletion enhanced the nucleolar granule formation of HSP70 and ubiquitin during HSR while facilitating the recovery of damaged nuclear proteins and impaired nucleocytoplasmic transport. Treatment of the mitochondrial proton gradient uncoupler masked MRP-depletion effects, implicating oxidative phosphorylation in these nuclear HSRs. On the other hand, MRP depletion and a reactive oxygen species (ROS) scavenger non-additively decreased mitochondrial ROS generation during HSR, thereby protecting the nuclear genome from DNA damage. These results suggest that suboptimal mitochondrial activity sustains nuclear homeostasis under cellular stress, providing plausible evidence for optimal endosymbiotic evolution via mitochondria-to-nuclear communication.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.3
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• pp.176-180
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• 2008

Department of Nuclear Medicine in Seoul National University Hospital (SNUH) had developed $^{18}F$-Flumazenil as Benzodiazepine receptor imaging agent for PET diagnosis of Epilepsy. But production Activity of $^{18}F$-Flumazenil is decreased owing to this method has difficult synthesis procedures and pretty long synthesis time. In this study, we can modify synthesizing method to have more simple procedure and less spend time and help to increase production Activity. Old method: Radioactivity was produced by cyclotron was captured by QMA cartridge that was activated. Captured radioactivity was eluted into the reaction vial by using kryptofix solution and delivered. After evaporation of eluent, the azeotrophic drying step repeated two times. tosylflumazenil in anhydrous Acetonitrile was added to a reaction vial while bubbling. The reaction mixture was evaporated until the mixture volume was 0.5 mL. Reaction vial washed with 20 % Acetonitrile and that solution went into the reaction vial. The reaction mixture was loaded to the HPLC loop by hand and purified $^{18}F$-Flumazenil by HPLC column. New method: We used $TBAHCO_3$ solution as a eluent. After the eluent was evaporated, tosylflumazenil in anhydrous acetonitrile was added to a reaction vial and the reaction mixture was bubbled for 15 minutes. It was evaporated until the mixture volume became 0.5 mL. It was loaded to the HPLC loop. In old method, $^{18}F$-Flumazenil was synthesized via 6 steps synthesis procedures in 105 minutes with 30~35% synthesizing yield (non-decay correction) and specific activity was about $0.5{\sim}2{\times}10^5$ Ci/mole. In new method, It had 3 steps synthesis procedures in 53 minutes with 40~45% synthesizing yield and specific activity was about $3{\sim}8{\times}10^5$ Ci/mole. This method leads to improve of minimizing synthesis time, increasing synthesis yield and specific activity. While we can load reaction mixture to the HPLC loop, we can expose high radiation field thanks to used by hand.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1007-1008
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• 2004

• Journal of Powder Materials
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• v.12 no.1
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• pp.51-55
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• 2005

$Cu_2O$ nano cubes with high catalase activity were synthesized by reduction of freshly prepared Cu in distilled water at $40^{\circC}$ and their catalase activities of $H_2O_2$ were studied. Transmission electron microscopy (TEM) observation showed that most of these nanocubes were uniform in size, with the average edge length of 30 nm. Selected area electron diffraction of TEM revealed that the nanocube consisted of single crystalline $Cu_2O$, but it changed to CuO phase. The catalase activity depends on the amount of both cuprite phase and surface area.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.3
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• pp.249-255
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• 2007

While respiratory burst enhances neutrophil glucose utilization, many neutrophil functions are critically influenced by extracellular matrix interaction and phosphoinositide-3-OH kinase (PI3K) signaling. We thus evaluated the role of RGD integrin occupancy and PI3K inhibition on respiratory burst and [18F]FDG uptake of stimulated neutrophils. Human neutrophils were stimulated by 100 ng/mL phorbol-myristate-acetate (PMA), and respiratory burst was measured by cumulative luminescence with lucigenin. [18F]FDG uptake and total hexokinase activity was measured 20 min after PMA stimulation in the presence or absence of soluble RGD peptides (200 g/mL) and/or the PI3K inhibitor wortmannin (200 nM). PMA induced a 71.70.9 fold increase in neutrophil oxygen intermediate generation. [18F]FDG uptake was increased to $194.6{\pm} 3.7%$ and hexokinase activity to $145.0{\pm}2.0%$ of basal levels (both p<0.0005). RGD peptides attenuated respiratory burst activation to $35.6{\pm}0.2%$ (p<0.005), but did not inhibit stimulated [18F]FDG uptake or hexokinase activity. In contrast, without affecting respiratory burst activation, wortmannin inhibited PMA stimulated [18F]FDG uptake to $66.9{\pm}1.6%$ and hexokinase activity to $81.0{\pm}4.2%$ (both P<0.0005), demonstrating its dependence on PI3K activity. Neither RGD nor wortmannin reversed the other's inhibitory effect on stimulated [18F]FDG uptake and hexokinase activity or respiratory burst, which suggests the involvement of distinct signaling pathways. Neutrophil [18F]FDG uptake is enhanced by PMA through a mechanism that requires PI3K activity but is independent of integrin receptor occupancy or respiratory burst activation.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.12-27
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• 2004

Pretreatment process consisted of submerged hollow-fiber microfiltration(HMF) membrane and spiral-wound nanofiltration(SNF) membrane has been developed by NETEC, KHNP for the purpose of improving the impurities of liquid radioactive waste before entering Selective Ion Exchange System(SIES). The lab-scale combined system was installed at Kori NPP #2 nuclear power plant and demonstration tests using actual liquid radioactive waste were carried out to verify the performance of the combined system. The submerged HMF membrane was adopted for removal of suspended solid in liquid radioactive waste and the SNF membrane was used for removal of particulate radioisotope such as, Ag-l10m and oily waste because ion exchange resin can not remove particulate radioisotopes. The liquid waste in Waste Holdup Tank (WHT) was processed with HMF and SNF membrane, and SIES. The initial SS concentration and total activity of actual waste were 38,000ppb and $1.534{\times}10_{-3}{\mu}Ci/cc$, respectively. The SS concentration and total activity of permeate were 30ppb and lower than LLD(Lower Limit of Detection), respectively.

• Reproductive and Developmental Biology
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• v.33 no.4
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• pp.223-228
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• 2009

We attempted to control the maturation promoting factor (MPF) activity and investigated the subsequent reprogramming of bovine somatic cell nuclear transfer (SCNT) embryos. Serum-starved adult skin fibroblasts were fused to enucleated oocytes treated with 2.5 mM caffeine or $150\;{\mu}M$ roscovitine. The MPF activity, nuclear remodeling patterns, chromosome constitutions and development of SCNT embryos were evaluated. Methylated DNA of embryos was detected at various developmental stages. The MPF activity was increased by caffeine treatment or reduced by roscovitine treatment (p<0.05). Blastocyst development was higher in the caffeine-treated groups (27.6%) than that of the roscovitine-treated group (8.3%, p<0.05). There was no difference in the apoptotic cell index among the three groups. However, the mean cell number of blastocysts was increased in the caffeine-treated group (p<0.05). Higher methylation levels were observed in the Day 3 embryos of the roscovitine-treated group (50.8%), whereas lower methylation levels were noted at Day 5 in the caffeine-treated group (12.5%, p<0.05). These results reveal that the increase in MPF activity via a caffeine-treatment creates a more suitable condition for nuclear reprogramming after SCNT.