• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.977-980
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• 2011

A new analytical method for measurement of 3,4-dihydroxyphenylalanine (DOPA) in human urine was developed. DOPA from an aqueous solution was converted into an ethoxycarbonyl (EOC) derivative. A tertbutyldimethylsilyl (TBDMS) reaction under anhydrous conditions was then attempted for analysis by gas chromatography-mass spectrometry in selected ion monitoring mode. A new mass spectral data on DOPA as a tri-EOC/mono-TBDMS derivative was built. This method showed good linearity (r ${\geq}$ 0.999), precision (% relative standard deviation = 3.1-9.2), and accuracy (% relative error = -7.2-8.8), with a detection limit of 0.05 ng/mL. This selective and accurate method of DOPA analysis will be useful for biochemical monitoring of various neurological disorders including Parkinson's disease in biological fluids.

• Molecules and Cells
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• v.46 no.3
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• pp.187-189
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• 2023

• Mass Spectrometry Letters
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• v.9 no.3
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• pp.81-85
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• 2018

In this study, the chemical composition of bacterial melanin isolated from the Streptomyces glaucescens strain was elucidated by ultra-high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Ultra-high-resolution mass profiles of the microbial melanin product were acquired using a 15 Tesla FT-ICR mass spectrometer in positive and negative ion modes via electrospray ionization to obtain more complete descriptions of the molecular compositions of melanin-derived organic constituents. A mass resolving power of 500,000 (at m/z 400) was achieved for all spectra while collecting 400 scans per sample with a 4 M transient. The results of this analysis revealed that the melanin pigment isolated from S. glaucescens predominantly exhibits CHON and CHO species, which belong to the proteins class of compounds, with the mean C/O and C/N ratios of 4.3 and 13.1, thus suggesting that the melanin could be eumelanin. This analytical approach could be utilized to investigate the molecular compositions of a variety of natural or synthetic melanins. The compositional features of melanins are important for understanding their formation mechanisms and physico-chemical properties.

• Publications of The Korean Astronomical Society
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• v.9 no.1
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• pp.55-68
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• 1994

We have reviewed three different techniques to estimate molecular cloud mass, and discussed the uncertainties involved. We found that determination of the most important parameter, the $^{13}CO$ abundance, is not very sensitive to the real LTE conditions, and that any possible error in deriving LTE column density may not introduce an error in the total gas column density, as far as the visual extinction is established for the object cloud. The virial technique always endows the largest mass estimate as there are several uncertainties, even if the cloud is in virial equilibrium. The strong indicator of the cloud perturbation is the centroid velocity dispersion. The mass using CO luminosity is based on the empirical law, but weakly dependent on the virial assumption, thus it still gives a larger mass estimate. The mass discrepancy is likely to be inevitable, and a factor of two or three difference between mass estimates could easily be attributed to the uncertainties mentioned above. The LTE mass estimate may be the most reliable one if we use the relation visual extinction and $^{13}CO$ column density of the object cloud, and the intercept is included.

• Journal of Oral Medicine and Pain
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• v.24 no.3
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• pp.261-267
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• 1999

The present investigation was carried out to identify salivary components of mucosal pellicle and to explore the difference of mucosal pellicle components according to the location of oral mucosa. By using antisera and immunoblotting, high-(MG1) and low-(MG2) molecular-mass salivary mucins, amylase, IgA, proline-rich proteins(PRPs) were detected in mucosal pellicle in vivo. In addition, the data indicated that mucins, IgA and proline-rich proteins could be cleaved into lower-molecular-mass products, whereas the IgA, proline-rich proteins could also be cross-linked into higher-molecular-mass complexes. Mucosal pellicles from buccal, labial and palatal mucosa showed similar pattern in immunoblotting experiments using anti-MG2 and anti-PRPs antisera. The data from this study suggest that during mucosal pellicle formation multiple components of saliva adsorb to oral mucosal epithelial cell surfaces, and selected components can be proteolytically cleaved into smaller fragments and/or cross-linked into higher-molecular products.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.34-42
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• 1999

The present investigation has focused up on the study of the adsorption of three different molecular mass fractions of a polyDiMethylDiAllylAmmoniumChloride (DMDAAC) (8750(LM\ulcorner), 48000(MM\ulcorner) and 1200000(HM\ulcorner)) on bleached chemical fibres. Both kinetics of adsorption and equilibrium adsorption measurements have been conducted and each adsorption has been measured by polyelectrolyte titration. The results show that the LM\ulcorner polymer can reach all of the charges in the fibre wall whereas the MM\ulcorner and HM\ulcorner can only reach the external surfaces of the fibres. It is also shown that the kinetics of adsorption of the LMw polymer is not at all affected by the presence of a saturated layer of HMw polymer on the surface of the fibres. Finally, the results from the investigation show that it is possible to have full coverage of the external surface of the fibres by a high molecular mass polymer and a full coverage of the internal surface of the fibres with a low molecular mass polymer. This is true if the high molecular masspolymer is added first followed by addition of the low molecular masspolymer.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.76.3-76.3
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• 2019

We present the results from our comparisons of HCN and HCO+ (J=4-3) with HI and $H_2$ gas in NGC 6946, a sample from a mapping study of the dense molecular gas in the strongest star-forming galaxies (MALATANG). The MALATANG is one of the JCMT legacy surveys on the nearest 23 IR-brightest galaxies beyond the Local Group, which aims to study the relations of dense molecular gas with more general cool gas such as atomic and molecular hydrogen gas, and star formation properties in active galaxies. In this work, we particularly focus on the comparisons between the JCMT HCN/HCO+ (J=4-3) data and the THINGS HI/the NRO CO (J=1-0) data. We probe the dense molecular gas mass as a function of HI and $H_2$ mass in different locations in the central ${\sim}1.5kpc^2$ region. We discuss how the excess/deficit of $HI/H_2$ or total cool gas ($HI+H_2$) mass controls the presence and/or the fraction of dense molecular gas.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.536-545
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• 2024

Radioactive iodine is a representative fission product to be quantified for the safety assessment of nuclear facilities. In integral severe accident analysis codes, the iodine behavior is usually described by a multi-physical model of iodine chemistry in aqueous phase under radiation field and mass transfer through gas-liquid interface. The focus of studies on iodine source term evaluations using the combination approach is usually put on the chemical aspect, but each contribution to the iodine amount released to the environment has not been decomposed so far. In this study, we attempted the decomposition by revising the two-film theory of molecular-iodine mass transfer. The model involves an effective overall mass transfer coefficient to consider the iodine chemistry. The decomposition was performed by regarding the coefficient as a product of two functions of pH and the overall mass transfer coefficient for molecular iodine. The procedure was applied to the EPICUR experiment and suppression chamber in BWR.

• KSBB Journal
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• v.19 no.5
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• pp.394-398
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• 2004

A derivatization method in mass spectrometry for small molecular analysis was developed to solve the problems of volatility of many analytes, difficult ionization of analytes, and undiscriminating isobaric analytes. This derivatization method, oximation of $\alpha$-ketoacid, in the transaminase reaction leads to change of mass difference between amine reactants and ketoacid products. In addition, regardless of the kinds of ketoacid, the linear relationship between the peak intensity and its concentration (from 1 mM to 10 mM) shows that quantitative analysis of the conversion of the reaction can be executed by the analysis of peak intensity of the corresponding oximated ketoacids. Furthermore, this method can be used for identifying transaminase as well as determining its substrate specificity

• Journal of fish pathology
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• v.28 no.3
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• pp.133-143
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• 2015

The antigenic proteins of Lymphocystis disease virus (LCDV) from tumors of olive flounder, Paralichthys olivaceus, are described following characterization by mass spectrometry. In SDS-PAGE, predominant protein bands were observed at 114, 88, 70, 54, 52, 47, 42 and 24 kDa. Western blot analysis showed that antisera reacted strongly at molecular weights of 114, 67 and 54 kDa, and reacted weakly at molecular weights of 74, 70, 36, 24 and 22 kDa. In the identification of LCDV antigenic proteins by matrix-assisted laser desorption ionization (MALDI) TOF mass spectrometry, 10 of 14 excised bands consisted mostly of proteins with amino acid sequences that matched LCDV-C (lymphocystis disease virus isolate China) ORFs. Strong antigens with molecular weights of 114, 67 and 54 kDa were identified as LDVICp236 (chromosome segregation ATPase), LDVICp033 (membrane bound metallopeptidase) and LDVICp157 (hypothetical protein), respectively. Minor antigens with molecular weights of 70, 36, 24 and 22 kDa proteins were identified as LDVICp160 (acetyl-coA hydrolase), LDVICp213 (hypothetical protein), LDVICp039 (hypothetical protein) and LDVICp213 (hypothetical protein). However, the major capsid protein (LDVICp043) did not react with the polyclonal antibody.