• 한국자기공명학회논문지
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• 제19권3호
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• pp.137-142
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• 2015

NMR-based structural studies on membrane proteins are appreciated quite challenging due to various reasons, generally including the narrow dispersion of NMR spectra, the severe peak broadening, and the lack of long range NOEs. In spite of the poor biophysical properties, structural studies on membrane proteins have got to go on, considering their functional importance in biological systems. In this review, we provide a simple overview of the techniques generally used in structural studies of membrane proteins by solution NMR, with experimental examples of a helical membrane protein, caveolin 3. Detergent screening is usually employed as the first step and the selection of appropriate detergent is the most important for successful approach to membrane proteins. Various tools can then be applied as specialized NMR techniques in solution that include sample deteuration, amino-acid selective isotope labeling, residual dipolar coupling, and paramagnetic relaxation enhancement.

• 한국식품영양학회지
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• 제12권2호
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• pp.191-191
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• 1999

A Purge & Trap Concentrator was used to analyze various volatile organic compounds(VOCs) in wat-er. The object of this study was to observe the purge efficiency of 40 VOCs in water according to the change of parameters (purge time drypurge time sample temperature) and to determine the optimum condition for VOCs using the purge & Trap concentrator interfaced with a narrow capillary connected to a gas chromatography/mass spectrometry. The optimum condition of purge and trap is as follows: purge time at 11min drypurge time at 5min sample temperature at 6$0^{\circ}C$ at constant purge flow (40mol/min) constant desorption flow(20ml/min) desorption temperature(2$25^{\circ}C$) and desorption time (1min) At this analytical condition the detection limits of VOCs was in the range of 0.1~0.5$\mu$g/ml and the purge efficiency of each compound was over 70%.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.225-231
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• 2005

This paper presents a design method for the structural-acoustic coupled radiator that can emit sound in the desired direction. A coupled system that has a finite space and a semi-infinite space separated by two flexible walls and an opening is considered. An objective function is selected to maximize radiation power on a main axis and minimize a side lobe level. To get initial values, prediction of a pressure distribution on field points and radiation pattern of the structural-acoustic coupling system is shown at a coupled-resonant frequency. Three different optimization methods are adapted to design the coupled radiator. Pressure and intensity distribution of the designed radiator is presented.

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.481-487
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• 2002

A selective enzyme-linked immunosorbent assay (ELISA) for the insecticide chlorpyrifos was developed. Four haptens for chlorpyrifos were synthesized and two of them were used as immunogens after coupling to keyhole limpet hemocyanin by two differe nt approaches. Rabbits were immunized with either of them and the sera were screened against 4 haptens coupled to ovalbumin (OVA). Using the sera of highest specificity, an antigencoated ELISA was developed, which shows an I50 of 160 ppb with a detection limit of 10 ppb. An antibody-coated ELISA was also developed, which shows an $I_{50}$ of 20 ppb with a detection limit of 0.1 ppb. The antibodies showed negligible cross-reactivity with other organophosphorus pesticides except for insecticides chlorpyrifos-methyl and bromophos-ethyl, which makes these assays suitable for the selective detection of chlorpyrifos.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2989-2992
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• 2009

An efficient synthetic route of novel 2′(${\alpha}$)-C-fluoro-2′(${\beta}$)-C-methyl carbocyclic nucleoside analogues is described. The key fluorinated intermediate 7 was prepared from the epoxide intermediate 5 via selective ring-opening of epoxide. Coupling of 7 with nucleosidic bases under the Mitsunobu reactions followed by deprotection afforded the target carbocyclic nucleoside analogues. The synthesized compounds were evaluated as inhibitors of the hepatitis C virus (HCV) in Huh-7 cell line in vitro.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2626-2630
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• 2009

2'($\beta$)-Hydroxymethylated adenosine is a potent and selective inhibitor of hepatitis C virus (HCV) replication. It targets the RNA-dependent RNA polymerase of HCV, NS5B. Synthesis and antiviral evaluation of carbocyclic versions are described. The cyclopentene intermediate ($9\beta$) was successfully synthesized through sequential Johnson-Claisen orthoester rearrangement and ring-closing metathesis (RCM). Coupling of bases via a Pd(0) catalyst, selective dihydroxylation, and desilylation yielded the target nucleoside analogues. The compounds 17 and 18 were assayed for their ability to inhibit HCV RNA replication in a subgenomic replicon Huh7 cell line and showed moderate antiviral activity with toxicity up to 20.0 and 24.7 ${\mu}g/mL$, respectively.

• 한국통신학회논문지
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• 제22권6호
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• 방사선산업학회지
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• 제10권4호
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• pp.181-187
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• 2016

Selective ${\beta}_1$-agonist and antagonists are used for the treatment of cardiac diseases including congestive heart failure, angina pectoris and arrhythmia. Selective ${\beta}_1$-antagonists including nebivolol have high binding affinity on ${\beta}_1$-adrenergic receptor, not ${\beta}_2$-receptor mainly expressed in smooth muscle. Nebivolol is one of most selective ${\beta}_1$-blockers in clinically used ${\beta}_1$-blockers including atenolol and bisoprolol. We tried to develop clinically useful cardiac PET tracers using a selective ${\beta}_1$-blocker. Nebivolol is $C_2$-symmetric and has two chromane moiety with a secondary amino alcohol and aromatic fluorine. We adopted the general synthetic strategy using epoxide ring opening reaction. Unlike formal synthesis of nebivolol, we prepared two chromane building blocks with fluorine and iodine which was transformed to diaryliodonium salt for labelling of $^{18}F$. Two epoxide building blocks were readily prepared from commercially available chromene carboxylic acids (1, 8). Then, the amino alcohol building block (15) was prepared by ammonolysis of epoxide (14) followed by coupling reaction with the other building block, epoxide (7). Diaryliodonium salt, a precursor for $^{18}F$-aromatic substitution, was synthesized in moderate yield which was readily subjected to $^{18}F$-aromatic substitution to give $^{18}F$-labelled nebivolol.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2143-2146
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• 2010

A selective synthetic method of the 2,5-biaryltriazolones has been developed via copper-catalyzed N-arylation reaction. Aryltriazolones, which were readily prepared from commercially available compounds, were N-arylated to 2,5-biaryltriazolones with high regioselectivity. This approach allows for access to a variety of 2,5-biaryl-1,2,4-trizol-3-ones in a simple and practical manner.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3382-3384
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• 2010

A new synthetic route to ($\pm$)-aspidospermidine was devised, starting from the cycloadduct of 3-ethyl-5-bromo-2-pyrone with vinyl sulfide through a tandem conjugate addition-alkylation sequence. The requisite 3-ethyl-5-bromo-2-pyrone was prepared via the C3-selective Pd-catalyzed coupling reaction with $Et_3Al$-dimethylaminoethanol complex.