• Journal of the Korean Chemical Society
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• v.39 no.7
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• pp.493-500
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• 1995

The geometry optimization of oxazole, relevant to the binding of lexitropsin that contains this ring to the base pair (G-C sequence) of minor groove of DNA, is performed with the aid of MM+ and ab initio (Hartree-Fock) calculations. The proton affinity and electronic structure are calculated at the 6-31G and $6-31G^{\ast}$ level for the optimized geometry. The proton affinities are also studied for various substituted oxazoles with the electron-donating and -withdrawing groups to estimate the substituent effect on the proton affinities of oxazoles. It is shown that the electron-donating substituents increase the proton affinity of oxazole, while the electron-withdrawing substituents decrease it. This result can be explained with atomic charge and electron density at oxygen of substituted oxazoles.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.115-119
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• 2015

${\beta}$-cyclodextrin has an ability to protect compounds from oxidative reaction by collecting them within its ring-like structure. So, In harsh condition ($40^{\circ}C$), marker compound, quercetin, was dramatically reduced in Hovenia dulcis fruit extract containing dextrin at 4 and 8 week compared to 0 week, but not that containing ${\beta}$-cyclodextrin. To evaluate the effects of dextrin and ${\beta}$-cyclodextrin on protective effect of H.dulcis fruit extract against alcohol-induced liver damage, The mice were orally injected alcohol, H. dulcis fruit extract/dextrin (HD) and H. dulcis fruit extract/${\beta}$-cyclodextrin (HCD), respectively, for 7 days. The mice orally administrated with alcohol significantly enhanced the serum concentration of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the activity of lactate dehydrogenase (LDH) in serum compared to the control group. HD and HCD significantly decreased the levels of serum ALT and AST and serum LDH activities compared to alcohol group. And also alcohol group significantly increased the level of total cholesterol compared to the control group, but HD and HCD significantly reduced it compared to the alcohol group. However, the levels of TG in blood were not significantly changed in all groups. The activities of alcohol dehydrogenase (ADH) were significantly increased in HD and HCD group although those of aldehyde dehydrogenase showed an increasing tendency. This data suggested that HD and HCD were able to induce alcohol degradation in the liver tissues. All together, the results showed that HCD demonstrated their ability to protect liver from alcohol-induced damage on equal terms with HD.

• Analytical Science and Technology
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• v.28 no.5
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• pp.347-352
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• 2015

Chemical properties such as heat of formation and density of methylnitroimidazole derivatives were predicted and analyzed by using density functional theory (DFT). Successive addition of energetic nitro groups into an imidazole ring increases both the heat of formation and the density. Using the chemical property values computed by DFT, explosive performance was analyzed with the Cheetah program, and compared with those of TNT, RDX, and HMX, which are currently used widely in military systems. When both C-J pressure and detonation velocity were used as explosive performance, methyldinitroimidazole derivatives show better performance than TNT, while methyltrinitroimidzole is almost close to RDX. Since methylnitroimidazole derivatives have a good merit, i.e. low melting point for melt loading, they are forecasted to be used widely in various military and civilian application.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.59.2-59.2
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• 2019

Event Horizon Telescope (EHT) aims to resolve the innermost region to the super massive black hole (SMBH) with its extremely high angular resolution (~20-25 uas) and enhanced sensitivity (down to 1-10 mJy) in concert with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm wavelength. This has a great importance as the first observational probe of the black hole shadow which has been theoretically predicted as a ring-like emission affected by the general relativistic effect under a strong gravitational field of SMBH. During the 2017 April 5-11, four nights of EHT observing campaign were carried out towards its primary targets, M87 and $SgrA{\ast}$. To robustly ensure the data processing, independent pipelines for various radio data calibration softwares (e.g., AIPS, HOPS, CASA) have been developed and cross-compared each other. The EHT has also been developing newer interferometric imaging techniques (e.g., eht-imaging-library, SMILI, dynamical imaging), as well as using an established method (CLEAN). With these, the EHT has designed various strategies which will be adopted for convincing imaging results. In this talk, I review how the robustness of EHT data processing and imaging will be validated so that the results can be ensured against well known uncertainties or biases in the interferometric data calibration and imaging.

• Analytical Science and Technology
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• v.35 no.4
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• pp.153-160
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• 2022

A green spectrophotometric method for the determination of cyanide has been proposed using, a green reagent, aqueous extract of blue butterfly pea. The test tube was filled with anthocyanin rich extract (pH 6) and cyanide solution. The reaction was kept constant for 10 minutes at room temperature. The reaction mixture changed color from blue to green as the amount of CN-ions increased. The 620 nm peak intensity increased with CN concentration. Therefore, this wavelength was used for all cyanide analyses. The cyanide calibration curve had a linear range of 0.25-1.00, 1.00-4.00, and 4.00-10.00 mg/L, with a satisfactory correlation coefficient of 0.99 and a LOD of 0.57 mg/L. The recovery ranged from 8.33 to 76.94 percent, indicating that this method is inaccurate at low cyanide concentrations. The intra-day and intermediate precision relative deviations were 0.391-0.871 % and 1.112-1.583 %. An H-bond forms between the C-4 group of the B-carbonyl ring and the HCN molecule according to the B3LYP/TZVP calculation. The method is convenient for cyanide concentrations above the LOQ of 1.09 mg/L, cost-effective, and capable of reducing toxic solvents with acceptable precision. The method could also be used to detect total cyanide in biological, environmental, and industrial waste samples.

• Analytical Science and Technology
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• v.21 no.3
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• pp.167-173
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• 2008

In order to solve the reproduction problem of PCB, we carried out poly chlorinated biphenyl (PCB) removal at low temperature (< $220^{\circ}C$), which could not take place reproduction of PCB by over 90% on catalyst. We coated catalyst to commercial bag filter for simultaneous removal of PCB and particle. It was found that PCB could be not reproducible due to it's decomposition of benzene ring. The coating method of spray type was more useful than that of precipitation one. PCB removal conversion was highest on the Pt-Co catalyzed bag filter. The data of this study can be well used in order to remove PCB and particle simultaneously for incinerator process by substituting commercial bag filter to catalyzed bag filter.

• Analytical Science and Technology
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• v.25 no.3
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• pp.197-206
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• 2012

Ambers are composed of polymer molecules which contain aromatic moieties such as benzene, naphthalene, phenanthrene and anthracene. They emit fluorescence when irradiated with ultraviolet light, which was used for confirming an amber. The fluorescence of amber, however, tends to decrease as the surface of amber is weathered with light, heat, oxygen for a long time. In this study, the reliability of confirming amber with its fluorescence by measuring the changes of fluorescence after artificial aging. Aging factors were UV light (${\lambda}$=340 nm), oxygen with heat (100%, $90^{\circ}C$) and heat ($90^{\circ}C$) and aging time was for 5, 15, 30 and 60 days, respectively. In the excitation and emission spectra of amber, the intensity decreased and the maximal wavelength was shifted to longer wavelength with artificial aging time. Especially, there was a drastic decrease in the intensity of spectra to 1.7% of initial value after 60 days aging under oxygen with heat. Only in Colombian amber there showed an increase of fluorescence intensity for a certain aging time, which could be explained by the production of aromatic ring in the presence of light and heat. Conclusively, the fluorescence can be lessened by the natural weathering with light, heat and oxygen and it is not accurate to recognize amber just with UV irradiation method.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1946-1952
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• 2005

New group 15 organometallic compounds, M$(phenanthrenyl)_3$ (M = P (1), Sb (2), Bi (3)) have been prepared from the reactions of 9-phenanthrenyllithium with $MCl_3$. A reaction of 9-(diphenylphosphino)phenanthrene with 2,6-diisopropylphenyl azide led to the formation of (phenanthrenyl)${(Ph)}_2P$=N-(2,6-$^iPr_2C_6H_3$) (4). The crystal structures of 2 and 4 have been determined by single-crystal X-ray diffractions, both of which crystallize with two independent molecules in the asymmetric unit. Compound 2 shows a trigonal pyramidal geometry around the Sb atom with three phenanthrenyl groups being located in a screw-like fashion with an approximately $C_3$ symmetry. A significant amount of CH- -$\pi$ interaction exists between two independent molecules of 4. The phosphorus center possesses a distorted tetrahedral environment with P-N bond lengths of 1.557(3)$\AA$ (P(1) N) and 1.532(3)$\AA$ (P(2)-N), respectively, which are short enough to support a double bond character. One of the most intriguing structural features of 4 is an unusually diminished bond angle of C-N-P, attributable to the hydrogen bonding of N(1)-H(5A) [ca. 2.49$\AA$ between two adjacent molecules in crystal packing. The compounds 1-3 show purple emission both in solution and as films at room temperature with emission maxima ($\lambda_{max}$) at 349, 366, and 386 nm, respectively, attributable to the ligand centered $\pi$ $\rightarrow$ $\pi^\ast$ transition in phenanthrene contributed by the lone pair electrons of the Gp 15 elements. Yet the nature of luminescence observed with 4 differs in that it originates from $\pi$ (diisopropylbenzene)-$\pi^\ast$ (phenanthrene) transitions with the $\rho\pi$contribution from the nitrogen atom. The emission maximum of 4 is red-shifted ranging 350-450 nm due to the internal charge transfer from the phenanthrenyl ring to the N-arylamine group as deduced from the ab initio calculations.

• Analytical Science and Technology
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• v.24 no.3
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• pp.183-192
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• 2011

This study was done for the determination and excretion profile of superdrol and its metabolites in human urine using both liquid chromatography with electrospray ionization mass spectrometry and gas chromatography with mass spectrometry after trimethylsilylation. Superdrol and its two metabolites were detected in human urine after administration of superdrol to healthy volunteers. The intra-day recovery ranged 89.7-113.2%, accuracy ranged 91.8-113.8% and reproducibility ranged 0.2-6.8% and inter-day recovery ranged 89.3-104.1%, accuracy ranged 95.2-103.0%, reproducibility ranged 0.7-7.8%. We found that superdrol M1 was a hydration at C-3 and superdrol M2 was a hydroxylation at D-ring. Superdrol and two metabolites were excreted as their glucuronided fractions. The glucuro-/sulfa-conjugated ratio of superdrol, superdrol M1 and superdrol M2 were 0.02, 0.02, 0.01, respectively. The excretion studies showed that superdrol and two metabolites were reached 4.3 h after oral administration and superdrol and superdrol M1 were detected until 48 h in human urine.

• Analytical Science and Technology
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• v.21 no.6
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• pp.510-517
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• 2008

This study has been described the metabolism and excretion in a healthy male urine collected for 26hrs after oral administration of diclofenac. To detect conjugated metabolites of diclofenac, urine sample was acid-hydrolyzed under the conditions of 6M-HCl at over $110^{\circ}C$ for 1hr. During the acidic hydrolysis process, diclofenac and its metabolites were converted into their corresponding lactam-ring through dehydration reaction. As results of chemical conversion by means of hydrolysis, the structures of diclofenac and its metabolites were also changed acidic to basic forms. However, lactam-ring was degraded by hydroxyl ion at basic condition. Thus, the extraction rate of dehydrated diclofenac and its metabolites was not favored at basic condition. For the determination of trace amounts of diclofenac and its metabolites in urine, trimethylsilylation (TMS) with MSTFA was applied and followed by analysis with gas chromatograph-mass spectrometer. In this study, four metabolites that are formed by the hydroxylation of parent drug were mainly detected. Each metabolite was tentatively identified by both interpretation of mass spectra and comparison with previously reported results. In addition, time profile of urinary excretion rate for parent drugs and metabolites was studied. Finally, the metabolic pathway of diclofenac was suggested on the basis of the elucidation of its metabolites and excretion profiles.