Young-Man Kim

Evaluation of natural crab shell as an adsorbent for preconcentrating airborne volatile organic compounds collected in a canister

Abstract A method has been developed for preconcentrating the volatile organic compounds (VOCs) in ambient air using a trap filled with natural crab shell powder without the need for extensive cryotrapping with liquid cryogens. Air samples collected in the canister were concentrated on the crab shell adsorbent trap without cryotrapping and then analysed using thermal desorption followed by capillary column (DB-5) gas chromatography with simultaneous ion trap mass detection. These analytical data on ambient air have been compared with those obtained by cryotrapping volatile compounds in glass beads followed by thermal desorption. The characteristics of natural crab shell as an adsorbent have been presented and its capacity for preconcentrating airborne VOCs has been tested by measuring breakthrough volume (l/g), detection limit (ppb, v/v) and reproducibility. The application of natural crab shell adsorbent trap for the analysis of ambient air samples collected in the canister has been proved to be useful.

Determination of free acetaldehyde in total blood for investigating the effect of aspartate on metabolism of alcohol in mice

To explore the effect of sodium L-aspartate monohydrate (aspartate) as a NAD+ regenerating agent for acetaldehyde in alcohol metabolism, a simple HPLC method has been developed for the measurement of free acetaldehyde in total mice blood digested with alcohol and aspartate. The blood samples were collected in EDTA Vacutainer tubes, and treated with 2,4-dinitrophenylhydrazine (DNP hydrazine) reagent in total blood. Acetaldehyde DNP hydrazone was extracted from total blood and analyzed by HPLC using an Ultrasphere ODS column. The compounds were separated using acetonitrile-water (50:50, v/v) as mobile phase and detected at 356 nm. The detection limit for acetaldehyde DNP hydrazone was 0.1 ppm. A blank determination was carried out for each analysis and subtracted from the results. The amount of acetaldehyde in blood has been determined as a function of time lapse after sole alcohol administration and aspartate ingestion followed by alcohol administration, respectively. This comparative analysis demonstrates that the ingestion of aspartate before the administration of alcohol dramatically decreases the aldehyde level in blood, and aspartate may be utilized as a prospective antagonist for acceleration of ethanol metabolism and prevention of acetaldehyde toxicity.

Solution conformation on bovine growth hormone releasing factor by 1H NMR and molecular modeling

The structure of bovine growth hormone releasing factor (bGHRF) consisting of 44 amino acids has been studied in CD and 1H nuclear magnetic resonance (NMR) spectroscopy in conjunction with molecular modeling. Since bGHRF does not have an ordered structure in water alone, a 30% 2,2,2‐trifluoroethanol (TFE) aqueous solvent was used to induce considerable α‐helical structures, which corresponds to a helical content of ∼62% as determined by circular dichroism (CD). The secondary structure was obtained from nuclear Overhauser enhancement and 3JHNα coupling constant in 30% TFE solution. Three‐dimensional structures consistent with NMR data were generated by using distance geometry calculation. A set of 267 interproton distances derived from nuclear Overhauser effect correlation spectroscopy (NOESY) experiments and coupling constants were used. From the initial random conformations, 50 distance geometry structures with minimal violations were selected for further refinement. The 14 best structures were obtained after simulated annealing calculation with energy minimization. The structure of bGHRF in 30% TFE solution was characterized by one α‐helix (residues 8–19), two poorly constrained helices (residues 23–27 and residues 31–34) and a β I(III)‐turn fragment (residues 20–23; φ i+1=−53.1°, Ψ i+1=−19.6°, φ i+2=−59.9°, Ψ i+2=−20.6°) connected by the segments of less defined structures in N‐terminal and Ω‐shaped flexible C‐terminal determined from NOESY cross peaks between helical segment (residues 14–18) and tail fragment (residues 42–44). The obtained structure will play an important role toward the understanding of the structural and functional role of the GHRF.

Rapid Annealing of Cu-In-Ga-Se Precursors by Electron Beam Irradiation Method.

Cu-In-Ga-Se precursors were prepared by RF- and DC-sputtering methods and then irradiated with an in-situ electron beam irradiation unit. Ternary (In,Ga)Se2 and binary CuSe targets were simultaneously used for preparation of precursors. The electron dose and irradiation time were kept constant at 300 seconds and 200 W of RF power, respectively, while intensities of accelerated electrons were varied from 2.5 to 4.5 keV. The thickness of all e-beam irradiated CuInGaSe2 (CIGS) films decreased from 1,250 nm to 470 nm. The crystalline properties of e-beam irradiated CIGS films were clearly shown on all samples and the highest intensity of (112) peak at 3.5 keV. The compositional ratio of Cu/(In + Ga) in the e-beam sample irradiated at 3.5 keV was coincident with that of the precursors. The degree of Ga content on the depth of the e-beam sample irradiated at 3.5 keV was uniformly distributed between the TCO/CdS layer and Mo back contact. Electron beam irradiation onto Cu-In-Ga-Se precursors as a rapid annealing method could be an excellent candidate for crystallization to the Cu(In,Ga)Se2 films.