Kyungsun Song

A new method for the identification and quantification of magnetite-maghemite mixture using conventional X-ray diffraction technique.

The electrical explosion of Fe wire in air produced nanoparticles containing the binary mixture of magnetite (Fe(3)O(4)) and maghemite (γ-Fe(2)O(3)). The phase identification of magnetite and maghemite by the conventional X-ray diffraction method is not a simple matter because both have the same cubic structure and their lattice parameters are almost identical. Here, we propose a convenient method to assess the presence of magnetite-maghemite mixture and to further quantify its phase composition using the conventional peak deconvolution technique. A careful step scan around the high-angle peaks as (511) and (440) revealed the clear doublets indicative of the mixture phases. The quantitative analysis of the mixture phase was carried out by constructing a calibration curve using the pure magnetite and maghemite powders commercially available. The correlation coefficients, R(2), for magnetite-maghemite mixture was 0.9941. According to the method, the iron oxide nanoparticles prepared by the wire explosion in this study was calculated to contain 55.8 wt.% maghemite and 44.2 wt.% magnetite. We believe that the proposed method would be a convenient tool for the study of the magnetite-maghemite mixture which otherwise requires highly sophisticated equipments and techniques.

Quantitative levels of fibrin(ogen) related materials in cerebrospinal fluid in patients with bacterial meningitis and other conditions

Summary We assumed that fibrin deposits and subsequent lysis within cerebrospinal fluid may occur in the various inflammatory disorders involving meninges. Therefore, we measured fibrin(ogen) related materials in cerebrospinal fluid of 118 patients with 21 bacterial meningitis, 22 aseptic meningitis, 75 non-meningitis associated with infectious febrile conditions and other neurologic conditions. Fibrin(ogen) related materials were quantitated as immunological components (D and E) of fibrin(ogen), which react with anti-D and anti-E using automated latex photometric immunoassay. When compared to aseptic meningitis group (mean; D=7.3, E=1.4ng/ml), the levels of D and E fibrin(ogen) related materials in cerebrospinal fluid were increased to highly significant levels in the bacterial meningitis group including tuberculous meningitis (mean; D=36.4, E=6.4ng/ml) (p

A study of activity ratios of uranium isotope in the groundwater using liquid scintillation counter

An analytical method was developed for the measurement of uranium isotope in ground water using the liquid scintillation counting technique. A LKB Wallac Quantulus 1220 liquid scintillation counter (LSC) equipped with pulse shape analyzer (PSA) and a solvent extraction method were used for the measurement of uranium isotope in ground water samples. The effect of solution volume on the extraction efficiency was evaluated for 100 to 1000 mL solutions using a NIST standard reference material (NIST SRM 4321C). The effect of groundwater pH on the extraction efficiency was also investigated for pH ranging from 0.5 to 10. It was found that the extraction efficiency had a strong dependence on pH showing a maximum at pH 2. In contrast, the effect of groundwater volume on the extraction efficiency was negligible in the range investigated. According to the method, the extraction efficiency of uranium isotopes was near 96% and the lower detection limit for uranium was 0.018 Bq/L with the counting time of 300 min. The result of this study was also verified by the conventional ICP-MS measurement. It is demonstrated that the suggested method is valuable to the determination of the optimum extraction and measurement conditions for uranium in ground water. The method was successfully applied to the ground water at four locations near the Daejeon province. It was found that the uranium content and the isotopic ratio of at the locations ranged 0.59~6.69 Bq/L and 0.72~1.40, respectively.