• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.261-268
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• 2014

Four clays (both natural and commercial types) mainly used in Korea were tested for removal efficiency of Microcystis spp. and ecotoxicity on Daphnia magna and Vibrio fischeri. Four clays (clay A~D) were composed of 91.9~100% of sand (0.02~0.2 mm in particle size). Clay D consisted of lager particles than other clays. Major elements of the four clays were $SiO_2$ (45.3~62.8%), $Al_2O_3$ (18.5~29.7%) and $Fe_2O_3$ (5.4~7.9%). They contained kaolinite (clay mineral), quartz, muscovite, and so on. Clay C and D contained montmorillonite, one of the clay minerals improving clay-cell aggregation. For clay A, B and C, removal efficiency of Microcystis spp. was over 60% at 2 g/L. It reached about 100% at over 5 g/L. For clay D, it was over 60% and 95~100% at 5 g/L and 20 g/L respectively. After adding clays, pH decreased. The greatest drop of pH appeared at clay C. Except for addition of 100 g/L clay C, ecotoxicity on D. magna and V. fischeri didn't appeared at all dose of clays.

• Journal of Powder Materials
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• v.22 no.6
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• pp.385-390
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• 2015

We report a synthesis of non-toxic InP nanocrystals using non-pyrolytic precursors instead of pyrolytic and unstable tris(trimethylsilyl)phosphine, a popular precursor for synthesis of InP nanocrystals. In this study, InP nanocrystals are successfully synthesized using hexaethyl phosphorous triamide (HPT) and the synthesized InP nanocrystals showed a broad and weak photoluminescence (PL) spectrum. As synthesized InP nanocrystals are subjected to further surface modification process to enhance their stability and photoluminescence. Surface modification of InP nanocrystals is done at $230^{\circ}C$ using 1-dodecanethiol, zinc acetate and fatty acid as sources of ZnS shell. After surface modification, the synthesized InP/ZnS nanocrystals show intense PL spectra centered at the emission wavelength 612 nm through 633 nm. The synthesized InP/ZnS core/shell structure is confirmed with X-ray diffraction (XRD) and Inductively Coupled Plasma - Atomic Emission Spectrometer (ICP-AES). After surface modification, InP/ZnS nanocrystals having narrow particle size distribution are observed by Field Emission Transmission Electron Microscope (FE-TEM). In contrast to uncapped InP nanocrystals, InP/ZnS nanocrystals treated with a newly developed surface modified procedure show highly enhanced PL spectra with quantum yield of 47%.

• Clean Technology
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• v.21 no.4
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• pp.235-240
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• 2015

In this study, vanadium dioxide was doped with titanium (0~0.5 at %) to improve thermochromic properties. The titanium doped vanadium dioxide (Ti-VO₂) particles were prepared via thermolysis process using vanadyl sulfate, ammonium bicarbonate and titianium chloride as precursors. The crystal structure, morphology, chemical bonding and thermochromic properties were investigated by using XRD, FE-SEM, XPS, DSC and UV-Vis-NIR spectroscopy. It was found that titanium was successfully doped into the crystal lattice of VO₂ and the obtained Ti-VO₂ particles have monoclinic structure. With increasing Ti concentration, the particle size and phase transition temperature of Ti-VO₂ particles decreased and NIR switching efficiency increased.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.720-725
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• 2011

Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/$Co_{3}O_{4}$ and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/$Co_{3}O_{4}$ catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

• Resources Recycling
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• v.9 no.3
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• pp.3-12
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• 2000

A Study on the cementation for the recovery of Cu, Ni and Co with Mn metallic powders in leaching solution from the manganese nodule that have removed Fe ions was studied. The results showed that the recovery efficiencies of metal ions with Mn powders increased when the temperature, pH and the concentration of chloride ions were increased in mixed solution. And the recovery efficiencies of Cu was 98% and not changed with the addition amounts of Mn powders but, in case of Co and Ni, the recovery efficiencies were increased with the addition amounts. The particle size of precipitate was about $5\mu\textrm{m}$. From the results of experiment we proposed the two-step cementation process for the recovery of Cu, Ni and Co with Mn powders.

• Journal of Environmental Science International
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• v.29 no.12
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• pp.1213-1222
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• 2020

In the current study, a Cu2O/TiO2 photoinduced nanocomposite materials prepared by ultrasonification method was evaluated the photocatalytic oxidation efficiency of volatile organic compounds (BTEX) under visible-light irradiation. The results of XRD confirmed the successful preparation of photoinduced nanocomposite materials. However, diffraction peaks belonging to TiO2 were not confirmed for the Cu2O/TiO2. The possible reason for the absence of Cu2O peak is their low content and small particle size. The result of uv-vis spectra exhibited that the fabricated Cu2O/TiO2 can be activated under visible light irradiation. The FE-SEM/EDS and TEM showed the formation of synthesized nanocomposites and componential analysis in the undoped TiO2 and Cu2O/TiO2. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with Cu2O/TiO2 were higher than undoped TiO2. According to light sources, the average oxidation efficiencies for BTEX by Cu2OT-0.5 were exhibited in the orer of 8 W day light > violet LEDs > white LEDs. However, the photocatalytic oxidation efficiencies normalized to supplied electric power were calculated to be in the following order of violet LEDs > white LEDs > 8 W day light, indicating that the LEDs could be a much more energy efficient light source for the photo-oxidation of gaseous BTEX using Cu2O/TiO2.

• Korean Journal of Metals and Materials
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• v.49 no.4
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• pp.348-354
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• 2011

Long-lasting brightness $Sr_{4}Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^{+}$ phosphor was synthesized by modified solid state reaction and its photoluminescence was investigated. $Sr(NO_3)_{2}$ and $Al(NO_3)_3{\cdot}9H_{2}O$ as starting materials, and $B_{2}O_{3}$ as a flux were mixed with $Eu_{2}O_{3}$ as an activator, $Dy_{2}O_{3}$ as a coactivator, and $AgNO_{3}$ as a charge compensator. The crystalline of target powder showed a single-phase $Sr_{4}Al_{14}O_{25}$ by the XRD characterization and the average particle size was about 20-30 ${\mu}m$ from the FE-SEM observation. $Ag^{+}$ ion doping effects (0-0.06 mol) on $Sr_{4}Al_{14}O_{25}:Eu^{2+},\;Dy^{3+},\;Ag^{+}$ phosphor were measured by photoluminescence spectrometer and luminescence meter. The of photoluminescence intensity of the $Sr_{3.64}Al_{14}O_{25}:Eu_{0.11},\;Dy_{0.22},\;Ag_{0.03}$ phosphor was higher than other compositions and afterglow brightness was 0.186 $cd/m^{2}$.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.39-49
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• 2022

Bottom ash generated from thermal power plants is mainly disposed in landfills, from which metals may be leached by infiltrating water. To evaluate the effect of metals in leachate on soil and groundwater, we characterized bottom ash generated from burning cokes, bituminous coal, the mixture of bituminous coal and wood pellets, and charcoal powder. The bottom ash of charcoal powder had a relatively large particle size, and its wood texture was well-preserved from SEM observation. The bottom ash of charcoal powder and wood pellets had relatively high K concentration from total element analysis. The eluates of the bottom ash samples had appreciable concentrations of Ca, Al, Fe, SO₄, and NO₃, but they were not a significant throughout the batch test. Therefore, it is considered that there is low possibility of soil and groundwater contamination due to leaching of metal ions and anions from these bottom ash in landfills. To estimate the trend of various trace elements, long-term monitoring and additional analysis need to be performed while considering the site conditions, because they readily adsorb on soil and aquifer substances.

• Analytical Science and Technology
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• v.19 no.1
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• pp.45-49
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• 2006

Drilled sediment core was acquired from Jinheung catchment which was located at Jeollabuk-do Jeongeup city. Elements concentration variation were studied by neutron activation analysis using sediment core by divided 1 cm depth interval. The concentration of major element such as Na, K were increased but Fe was decrease with depth. Minimum elements concentration and particle size were observed at 17 cm depth. This depth was considered 1969 year which was great dry year recorded from the rain fall data and the sedimentation rate was calculated $0.197g{\cdot}cm^{-2}{\cdot}year^{-1}$.

• Clinical and Experimental Vaccine Research
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• v.12 no.4
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• pp.304-312
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• 2023

Purpose: Due to the many problems with commercially available vaccines, the production of effective vaccines against brucellosis is a necessity. The aim of this study was to evaluate the immune responses caused by the chimeric protein consisting of trigger factor, Bp26, and Omp31 (TBO) along with aluminum hydroxide (AH/TBO) and selenium (Se/TBO) nanoparticles (NPs) as adjuvants in mouse model. Materials and Methods: Recombinant antigen expression was induced in Escherichia coli BL21 (DE3) bacteria using IPTG (isopropyl-d-1-thiogalactopyranoside). Purification and characterization of recombinant protein was conducted through NiFe₃O₄ NPs, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blot. NP characteristics, including morphology and particle size, were measured in vitro. The recombinant TBO was loaded on to AH and Se NPs and were administered subcutaneously. After mice immunization, measurement of antibody titter and protection assay was performed. Results: The average sizes of AH and Se NPs were about 60 nm and 150 nm, respectively. The enzyme-linked immunosorbent assay results showed that the serum of mice immunized by subcutaneous injection with both nanovaccines produced significant immunoglobulin G (IgG) responses against the chimeric antigen. The results of TBO-specific IgG isotype (IgG2a/IgG1) analysis showed that both AH and Se NPs induced a type to T-helper immune response. In addition, the results of the challenge with the pathogenic strain of Brucella melitensis 16M showed that vaccinated mice with AH/TBO NPs indicated a higher reduction of bacterial culture than immunized mice with Se/TBO NPs and TBO alone. Conclusion: The results showed that AH NPs carrying chimeric antigen can be a promising vaccine candidate against brucellosis by producing protective immunity.