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Synthesis and Characterization of CdS Nanocrystals in a Novel Phosphate Glass
Donghwan Kim,Chawon Hwang,Donggun Gwoo,Taehee Kim,Youngseok Kim,Namjin Kim,류봉기 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.4
Zinc-borophosphate glasses doped with various concentrations (≤ 5 wt. %) of cadmium sulfide (CdS) were synthesized. Nanocrystals of CdS were developed in the glass matrices at different concentrations, with emphasis on the quantum confinement effect. The effects of CdS content on the optical and various other properties were investigated. The optical characterization of the glasses was carried out using UV-Visible spectrophotometry. There was a red shift in the optical cut-off with increasing CdS content in the glass. The band gap of the CdS nanocrystals doped in the glass matrix ranged from 3.5 eV to 4.2 eV. The structural characterization,which was carried out using X-ray diffraction, shows the CdS to have hexagonal crystal structure. The average size and shape of the nanocrystals doped in the glass matrix were determined using transmission electron microscopy (TEM). The particle sizes of the doped CdS crystals were in the range of 3 nm to 6 nm for 2 wt. % CdS, and 15 nm to 20 nm for 5 wt. % CdS.
Effect of Titanium on Structure of Sodium Borophosphate Glasses
Donghwan Kim,Chawon Hwang,Donggun Gwoo,Taehee Kim,Namjin Kim,류봉기 대한금속·재료학회 2011 ELECTRONIC MATERIALS LETTERS Vol.7 No.4
Glasses in the system 30P₂O_5-30B₂O₃-40Na₂O-xTiO₂ (0 ≤ x ≤ 25 mol %) have been prepared by the meltquenching technique. Increasing the TiO₂ content of the glass structure results in a decrease in the molar volume and an increase in the glass transition/softening temperatures. Structural changes were studied by Raman spectroscopy, and 11 B and 31P solid-state NMR. The observed changes in the spectra and the properties of the studied glasses can be ascribed to several reasons, such as the addition of TiO₂ that results in the formation of distorted Ti octahedral linked to pyrophosphate unit through P–O–Ti bonds. In these glass series,the overall glass network was enhanced by TiO₂ addition, although a depolymerization in the original P–O–P network occurred.
Effects of Substitution of K2O for Na2O on the Bioactivity of CaO-Na2O-SiO2-P2O5 Glasses
Taehee Kim,Chawon Hwang,Donggun Gwoo,Hoyyul Park,류봉기 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.5
The compositional dependences of bioactivity, thermal properties, atomic structure, and surface morphology have been investigated in the CaO-Na2O-SiO2-P2O5 system; this system is known as a bioglass. 45S5 Bioglass®is known to be a general and highly bioactive material. However, the bioactivity of this glassy material is expected to be improved by modifying the alkali-metal composition. Thermal properties, density, and molar volume were measured to investigate the structural packing. FT-IR spectra and X-ray diffraction were used to confirm the structures of these glasses. The morphology was examined using field emission electron microscopy,and the formation of a Ca-P layer was studied using an energy-dispersive system. This study shows that the tendency to form a calcium phosphate layer is increased with the substitution of K2O for Na2O.
Min, Sun-Hong,Cho, Ilsung,Park, Chawon,Jung, Wongyun,Hwang, Won Taek,Kim, Minho,Lee, Kyo Chul,Lee, Yong Jin,Lim, Sang Moo,Hong, Bong Hwan 대한방사성의약품학회 2019 Journal of radiopharmaceuticals and molecular prob Vol.5 No.2
Radiopharmaceuticals include therapeutic radiopharmaceuticals and diagnostic radiopharmaceuticals. Therapeutic radiopharmaceuticals are administered to the body and ingested at specific organs to detect radiation emitted from the site and to construct an image to diagnose the disease. Diagnostic radiopharmaceuticals are used to treat diseases by killing cells with radiation emitted from radiopharmaceuticals, such as cancer cells, vascular endothelial cells, arthritis, and Alzheimer's disease. The application possibilities of terahertz imaging technology for the combination of radiopharmaceuticals and molecular imaging medicine are discussed and experimental methods are presented. Terahertz imaging is expected to be a powerful technique because of the effective piercing feasibility, which enables to perform safe and high resolutive imaging. To investigate the response of cell to the terahertz wave, both the pulsed and CW THz wave systems are employed. THz imaging of a rat's paraffin-embedded epithelial cell with tumor is studied in advance.
Sun-Hong Min,Bong Hwan Hong,Ilsung Cho,Chawon Park,Wongyun Jung,Won Taek Hwang,Minho Kim,Kyo Chul Lee,Yong Jin Lee,Sang Moo Lim 대한방사성의약품학회 2019 Journal of radiopharmaceuticals and molecular prob Vol.5 No.2
Radiopharmaceuticals include therapeutic radiopharmaceuticals and diagnostic radiopharmaceuticals. Therapeutic radiopharmaceuticals are administered to the body and ingested at specific organs to detect radiationemitted from the site and to construct an image to diagnose the disease. Diagnostic radiopharmaceuticals areused to treat diseases by killing cells with radiation emitted from radiopharmaceuticals, such as cancer cells,vascular endothelial cells, arthritis, and Alzheimer's disease. The application possibilities of terahertz imagingtechnology for the combination of radiopharmaceuticals and molecular imaging medicine are discussed andexperimental methods are presented. Terahertz imaging is expected to be a powerful technique because ofthe effective piercing feasibility, which enables to perform safe and high resolutive imaging. To investigate theresponse of cell to the terahertz wave, both the pulsed and CW THz wave systems are employed. THz imagingof a rat’s paraffin-embedded epithelial cell with tumor is studied in advance.
Kim, Minho,Hong, Bong Hwan,Cho, Ilsung,Park, Chawon,Min, Sun-Hong,Hwang, Won Taek,Lee, Wonho,Kim, Kyeong Min Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.2
Boron-neutron capture therapy (BNCT) is a cancer treatment method that exploits the high neutron reactivity of boron. Monitoring the prompt gamma rays (PGs) produced during neutron irradiation is essential for ensuring the accuracy and safety of BNCT. We investigate the imaging of PGs produced by the boron-neutron capture reaction through Monte Carlo simulations of a gamma camera with a SrI<sub>2</sub> scintillator and parallel-hole collimator. GAGG scintillator is also used for a comparison. The simulations allow the shapes of the energy spectra, which exhibit a peak at 478 keV, to be determined along with the PG images from a boron-water phantom. It is found that increasing the size of the water phantom results in a greater number of image counts and lower contrast. Additionally, a higher septal penetration ratio results in poorer image quality, and a SrI<sub>2</sub> scintillator results in higher image contrast. Thus, we can simulate the BNCT process and obtain an energy spectrum with a reasonable shape, as well as suitable PG images. Both GAGG and SrI<sub>2</sub> crystals are suitable for PG imaging during BNCT. However, for higher imaging quality, SrI<sub>2</sub> and a collimator with a lower septal penetration ratio should be utilized.