Radionuclides in low- and intermediate-level radioactive wastes from the decommissioning process of nuclear power plants were generally immobilized by cementation methods. Ethylenediaminetetraacetic acid (EDTA), which is extensively used as a decontamination agent, can affect the behaviors of radionuclides immobilized in cement waste forms. In this study, the effects of EDTA contained in simulated radioactive decommissioning wastes on the leaching characteristics of immobilized Co and Cs and the microstructure evolution of cement waste form. Co leaching was accelerated by the formation of Co–EDTA complexes with high mobility and solubility. Cs leaching was hindered by the ion competition with other metal–EDTA complexes for releasing from the cement waste form. Cs leaching was also retarded by carbonated layer at edge of the cement waste form, which process is facilitated by the presence of EDTA. Finally, the effects of EDTA on the leaching characteristics of immobilized Cs and Co and the microstructure evolution of the cement waste form should be considered to ensure the safety of disposal for lowand intermediate-level radioactive wastes.

Sulfur and nitrogen co-doped carbon dots (NSCDs) were quickly synthesized by the microwave-assisted method from triammonium citrate and thiourea. NSCDs showed a quantum yield of 11.5% with excitation and emission bands at 355 and 432 nm, respectively. Also, a fluorescence quenching was observed in the presence of Pb(II) ions, and the as-synthesized CDs were used as a sensitive probe for detecting Pb(II) in water and food samples. The results showed the optimal conditions for Pb(II) determination were CDs concentration of 0.02 mg mL− 1 at pH 6.0–7.0 and an incubation time of 20 min. The relative fluorescence intensity of NSCDs was proportional to Pb(II) concentrations in the range of 0.029–2.40 and 2.40–14.4 μmol L− 1 with a correlation coefficient (R2) of 0.998 and 0.955, respectively, and a detection limit of 9.2 × 10– 3 μmol L− 1. Responses were highly repeatable, with a standard deviation below 3.5%. The suggested method demonstrates the potential of a green, fast, and low-cost approach for Pb(II) determination in water, tea, and rice samples with satisfying results.

Enhancing the capacitive deionization performance requires the inner structure expansion of porous activated carbon to facilitate the charge storage and electrolyte penetration. This work aimed to modify the porosity of coconut-shell activated carbon (AC) through CO2 activation at high temperature. The electrochemical performance of CO2- activated AC electrodes was evaluated by cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy, which exhibited that AC-800 had the superior performance with the highest capacitance of 112 F/g at the rate of 0.1 A/g and could operate for up to 4000 cycles. Furthermore, in the capacitive deionization, AC-800 showed salt removal of 9.15 mg/g with a high absorption rate of 2.8 mg/g min and Ni(II) removal of 5.32 mg/g with a rate close to 1 mg/g.min. The results promote the potential application of CO2- activated AC for desalination as well as Ni-removal through capacitance deionization (CDI) technology.

Numerous low-and intermediate level radioactive wastes were generated from the decommissioning processes of nuclear power plants. Radionuclides such as Co and Cs contained in decommissioning wastes should be immobilized to prevent the release of radionuclides from the wastes due to its harmful impacts on ecosystem by high radioactivity and long half-life. Ethylenediaminetetraacetic acid (EDTA) used as decontamination agent can be contained in cement waste during decommissioning process of nuclear power plants. In addition, EDTA can be stably and strongly bound with radionuclides, resulting in the acceleration of the nuclide release from solidified cement matrix. Here, we investigated the effects of EDTA on leaching behaviors of Co and Cs immobilized in the cement specimen. The leaching tests were performed according to the ANS 16.1 “Measurement of the leachability of solidified low-level radioactive wastes by a short-term test procedure”. From the results, an increase in the EDTA content in the cement specimen led to an increase in Co leaching, whereas a decrease in Cs leaching. Leaching of Cs was dominantly controlled by diffusion from the pore space of the cement specimen to the solution. The effective diffusion coefficient and leachability index of nuclide were determined using the diffusion-release models of ANS 16.1. The results of present study can be used in the safety assessment for disposal of the radioactive waste generated by decommissioning of nuclear power plants.

In this study we aimed to examine the co-doping effects of 1/6mol% Co3O4 and 1/4mol% Cr2O3 (Co:Cr=1:1)on the reaction, microstructure, and electrical properties, such as the bulk defects and the grain boundary properties, of ZnO-Bi2O3-Sb2O3 (ZBS; Sb/Bi=0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Co,Cr-doped ZBS, ZBS(CoCr)varistors were controlled using the Sb/Bi ratio. Pyrochlore (Zn2Bi3Sb3O14), α-spinel (Zn7Sb2O12), and δ-Bi2O3 were formed inall systems. Pyrochlore was decomposed and promoted densification at lower temperature on heating in Sb/Bi=1.0 by Cr ratherthan Co. A more homogeneous microstructure was obtained in all systems affected by α-spinel. In ZBS(CoCr), the varistorcharacteristics were improved (non-linear coefficient, α=20~63), and seemed to form Zni..(0.20eV) and Vo.(0.33eV) asdominant defects. From impedance and modulus spectroscopy, the grain boundaries were found to be composed of anelectrically single barrier (0.94~1.1eV) that is, however, somewhat sensitive to ambient oxygen with temperature. The phasedevelopment, densification, and microstructure were controlled by Cr rather than by Co but the electrical and grain boundaryproperties were controlled by Co rather than by Cr.

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb (II) removal. This procedure is based on using powdered activated carbon, which was prepared from walnut shells that were generated as plant wastes and modified with potassium carbonate and phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb (II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich adsorption models. The kinetic study of Pb (II) on activated carbon from walnut shells was performed based on pseudo- first order and pseudo- second order equations. The data indicate that the adsorption kinetics follow the pseudo- second order rate. The procedure was successfully applied for Pb (II) removal from aqueous solutions.

Most heavy metals are well-known toxic and carcinogenic agents and when discharged into wastewater represent a serious threat to the human population and the fauna and flora of the receiving water bodies. The present study aims to develop a procedure for Pb(II) removal. The study was based on using powdered activated carbon, which was prepared from walnut shells generated as plant wastes and modified with potassium carbonate or phosphoric acid as chemical agents. The main parameters, such as effect of pH, effect of sorbent dosage, Pb(II) concentrations, and various contact times influence the sorption process. The experimental results were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich adsorption models. The kinetic study of Pb(II) on activated carbon from walnut shells was performed based on pseudo-first order and pseudo-second order equations. The data indicate that the adsorption kinetics follow the pseudo-second order rate. The procedure was successfully applied for Pb(II) removal from aqueous solutions.

The molecular cloud associated with the H II region S301 has been mapped in the J = 1-0 transitions of 12CO and 13CO using the 13.7 m radio telescope of Taeduk Radio Astronomy Observatory. The cloud is elongated along the north-south direction with two strong emission components facing the H II region. Its total mass is 8.7 × 10 3 M⊙. We find a velocity gradient of the molecular gas near the interface with the optical H II region, which may be a signature of interaction between the molecular cloud and the H II region. Spectra of CO, CS, and HCO+ exhibit line splitting even in the densest part of the cloud and suggests the clumpy structure. The radio continuum maps show that the ionzed gas is distributed with some asymmetry and the eastern part of the H II region is obscured by the molecular cloud. We propose that the S301 H II region is at the late stage of the champagne phase, but the second generation of stars has not yet been formed in the postshock layer.

Interaction of dietary Magnesium, Calcium and Polyunsaturated fatty acid(vegetable oils)on 3-Hydroxy-3-Methylglutaryl Co-A reductase activity was studied for a period of 30 days using isocalories and isonitrogenous as a basal diet . The subject rabbits were divided into 18 feeding groups. The results are summarized as follows: 1. The ratio of α1-lipoprotein par lipalbumin is 0.34 for control group, 0.38 the highest group fed 0.1 Mg(II) 10ml plus perilla oil and basal diet, the lowest 0.25 group fed 0.1M Mg(II) 5ml plus sesame oil and basal diet. 2. The ratio ratio of α2-lipoprotein per lipalbumin is 0.64 for control group. 0.95 as the highest for the group fed 0.1M Ca(II) 15ml plus sesame oil and basal diet, 0.1M Ca(II) 5ml plus perilla oil and basal diet. 3. The ratio of β-lipoprotein per lipalbumin is 0.71 for control group, the highest 0.81 for the groups fed 0.1M Mg(II) 10ml plus sesame oil and basal diet, the lowest 0.37 for the group fed 0.1M Mg(II) 15ml plus soybean oil and basal diet. 4. In serum triglyceride, control group was 129.5mg%, the highest 155.4mg% for the group fed 0.1M Ca(II) 5ml plus sesame oil and basal diet, the lowest 85.7mg% for the group fed 0.1M Mg(II) 10ml plus soybean oil and basal diet. 5. In serum cholesterol, control group was 96.7mg%, the highest 152.5mg% for the group fed 0.1M Ca(II) 10ml plus sesame oil and basal diet, the lowest 80.5mg% for the group fed 0.1M Mg(II) 15ml plus soybean oil and basal diet. 6. In case of HMG-CoA reductase activity, control group was 0.95, the highest 0.98 for the group fed 0.1M Ca(II) plus soybean oil and basal diet. 7. Interaction between metal(II) ions and polyunsaturated fatty acid(vegetable oil) are soybean oil〉sesame oil〉perilla oil, for Mg(II). soybean oil〉perilla oil〉sesame oil, for Ca(II). Therefore, it is invetigated that the interaction between metal ion and polyunsaturated fatty acid is the higher, the cholesterol level is the lower, and HMG-CoA reductase activity is increased.

니켈 라테라이트광 황산침출액에 함유된 니켈과 코발트를 마그네슘으로부터 분리하는 것은 유가금속의 회수측면에서 중요하다. 세 금속간의 분리성을 조사하기 위해 니켈과 코발트 및 마그네슘이 단독으로 존재하는 황산용액과 혼합용액에서 Diphonix 수지에 의한 흡착거동을 조사하였다. 금속 농도는 100 ppm으로 고정시키고 황산용액의 pH를 5에서 7사이로 변화시켰다. 상온에서 Diphonix에 의한 세 금속이온의 흡착거동은 Langmuir 등온곡선과 잘 일치하였으며, 각 금속의 최대흡착량을 구했다. 세 금속이 혼합된 합성용액에서 Diphonix 농도에 따른 세 금속이온의 흡착거동은 동일하였으며 Diphonix 수지로 니켈과 코발트를 마그네슘으로부터 분리하는 것은 어렵다.