• The Journal of the Acoustical Society of Korea
• /
• 제25권1E호
• /
• pp.14-19
• /
• 2006

Ultrasonic absorption and velocity spectra in bovine serum albumin (BSA) aqueous solutions have been measured at $20^{\circ}C$ over the frequency range 0.2-3 MHz in the pH range 1.5-13.2. The high-Q ultrasonic resonator and pulse-echo overlap methods were used. At acid pH's, excess absorption over that of pH 7 was explained by double relaxation. The pH dependences of the relaxation frequency and maximum absorption per wavelength, showed that the relaxation at about 200 kHz was related to the expansion of molecules and that about 3 MHz resulted from the proton transfer reaction of carboxyl group. At alkaline pH's, the excess absorption was explained by double relaxation. The relaxation at about 300 kHz was associated with a helix-coil transition, and that about 3 MHz was attributed to the proton transfer reaction of phenolic group. The rate constants and volume changes associated with these processes were estimated.

• Natural Product Sciences
• /
• 제20권4호
• /
• pp.281-284
• /
• 2014

In this study, twenty-one oleanane-type triterpenoid saponins were isolated from a methanol extract of the roots of Pulsatilla koreana. Antagonistic activities were measured in these compounds by the aequorin based cellular functional assay system for the corticotropin releasing factor receptor (CRF1). Of them, compounds 7 - 10 showed the highest degree of CRF1 inhibition further at the concentration of $10{\mu}M$. Moreover, by the analysis based on the structure-activity relationship of isolated saponins, a sugar chain at C-3 and a carboxyl group at C-28, as well as a methyl group at C-23 seems to be key functional elements. To our knowledge, this is the first report on CRF1 inhibition of saponins from P. koreana.

• 한국염색가공학회지
• /
• 제7권1호
• /
• pp.72-79
• /
• 1995

The effect of copper sulfate/thiourea on the diffusion and the dye exhaustion of two dyes, C. I. Acid Orange 7 and C. I. Food Yellow 3 in nylon 6 fiber has been studied. The results obtained from the experimetal are as follows : 1) Copper sulfate reacted with thiourea at constant temperature and then generated the colorless trasparent coordination compound, and then combinated end group of carboxyl of nylon 6 fiber. 2) The coordination compound [$Cu_{2}$($TU_{6}$)] ($(SO_{4})_2$) is conducted at pH 5-6 in solution intensity and repulsed the sulfonic acid group of dyes, and therefore the diffusion of dyes is restraint. 3) Dye uptake and diffusion coefficient were decreased in the order of untreated > copper sulfate/thiourea-treated > tannin-treated.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.480.2-480.2
• /
• 2014

Electrochemical capacitors have been the most strong energy storage devices due to high power density and long cycle stability. Pristine carbon nanotubes are promising electrode materials for excellent electrical conductivity and high specific surface area in electrochemical capacitor. However, the practical application of pristine carbon nanotubes was limited by the aggregation into bundles due to van der Waals force. In this research, we explained how multi-walled carbon nanotubes (MWCNT) functionalized by carboxyl, sulfonic, and amine groups (CNT-COOH, CNT-SO3H, CNT-NH2) to improve the performances of MWCNT. Functionalized CNTs showed two- to four-fold increase in capacitance over that of pristine CNTs, while maintaining reasonable cyclic stability. But, the CNT-COOH showed the lowest rate capability of 57% compared to 84%, 86% of CNT-SO3H and CNT-NH2. As demonstrated by the spectroscopic analysis, This reseach showed how surface functional group of carbon nanotubes change capacitor performances.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
• /
• pp.156-157
• /
• 1998

Taurine is synthesized in the body or uptaken from dietary and is distributed in the various organs. It differs from other amino acids by virtue of the fact that a sulfonic acid group replaces the carboxyl group of what would be ${\beta}$-alanine. In order to function within the cell it must be transported into the cells by taurine transporter that is spanned 12 transmembrane domains. The human taurine transporter has long cytoplasmic carboxy and amino termini that may function as regulatory attachment sites for other proteins. Six potential protein kinase C(PKC) phosphorylation sites have been reported in human taurine transporter.

• 분석과학
• /
• 제8권4호
• /
• pp.655-661
• /
• 1995

The electrochemical reduction of coumarin derivatives in 0.1M TEAP acetonitrile solution was investigated by the direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The electrochemical reduction of 7-acetoxy-4-bromomethyl-coumarin(ABMC) was proceeded as an irreversible three steps(-0.58, -1.63 and -2.25 volts) of electrochemical transfer before chemical reaction. The solution color turned to yellow after the carboxyl group was reduced at 2nd step(-1.63 volts vs. Ag-AgCl) and the change in color was independant to the bromo group. Upon the basis of the results on the products analysis and the interpretaton of polarograms, a possible electrochemical reaction mechanism was suggested.

• Archives of Pharmacal Research
• /
• 제13권2호
• /
• pp.166-173
• /
• 1990

The structure of the anti-inflammatory agent, naproxen sodium was determined by single crystal X-ray diffraction analysis. Crystal of the compound, which was recrystallized from methanol solution, is nomoclinic, space group $P2_1$ with a = 21. 177(6), b = 5.785(2), c = 5.443(2) $\AA, \beta$ = 91.41(3)$\{\circ}$ and Z = 2. The calculated density is 1.346; the observed value is nements based on 1093 reflections ($F\geq3\sigma$(F)) gave the final R value of 0.043. There are of one water per one compound molecule in the crystal. The carboxyl group of the molecule is nearly perpendicular to the naphthalene ring. The molecules are arranged along with the screw axis, and stabilized by five 0...Na type interactions. The molecule retains nearly same dimensions and similar conformation compared to its parent compound, naproxen, except for the torsion angles around C(5)-C(11) bond.

• Journal of Pharmaceutical Investigation
• /
• 제30권2호
• /
• pp.73-83
• /
• 2000

Polyethylene glycol (PEG) is a water soluble, biocompatible, non-toxic polymer and PEGylation is a well established technique for the modification of therapeutic proteins and peptides. PEG-protein drugs have been extensively studies in relation to therapies for various diseases: cancer, inflammation and others. The covalent attachment of PEG to proteins and peptides prolonged plasma half-life, reduced antigenicity and immunogenicity, increased thermal and mechanical stability, and prevented degradation by enzymes. Several chemical groups for general and site specific conjugation have been exploited to activate PEG for amino group, carboxyl group, and cysteine groups. PEGylation of many proteins and peptides have been studied to enhance their properties for the potential uses. Also, the different positional isomers in several PEG-proteins have shown the difference in vivo stability and biological indicating that the site of PEG molecule attachment is one of the important factor to develop PEG-proteins as potential therapeutic agents.

• Macromolecular Research
• /
• 제17권8호
• /
• pp.585-590
• /
• 2009

The cure behaviors, dielectric characteristics and fracture toughness of diglycidylether of bisphenol-A (DGEBA)/poly(ethylene terephthalate) (PET) blend system were investigated. The degree of conversion for the DGEBA/PET blend system was measured using Fourier transform infrared (FTIR) spectroscopy. The cure kinetics were investigated by measuring the cure activation energies ($E_a$) with dynamic differential scanning calorimetry (DSC). The dielectric characteristic was examined by dielectric analysis (DEA). The mechanical properties were investigated by measuring the critical stress intensity factor ($K_{IC}$), critical strain energy release rate ($G_{IC}$), and impact strength test. As a result, DGEBAIPET was successfully blended. The Ea of the blend system was increased with increasing PET content to a maximum at 10 phr PET. The dielectric constant was decreased with increasing PET content. The mechanical properties of the blend system were also superior to those of the neat DGEBA. These results were attributed to the increased cross-linking density of the blend system, resulting from the interaction between the epoxy group of DGEBA and the carboxyl group of PET.

• 한국염색가공학회지
• /
• 제7권4호
• /
• pp.39-44
• /
• 1995

A study has been made about some correlations in the chemical cyclization of precursors, poly(ether-amide-amic acid)s by treating in solution a mixture of acetic anhydride and pyridine in the presence of 4,4-dimethyl formamide, with the poly(ether-amic acid)s being respectively reacted between trimellitic anhydride chloride and 3 kinds of diamines, i.e., 4,4'-bis(m-aminophenoxy) benzophenone, 2,2'-bis[4-(m-aminophenoxy) phenyl] propane and 4,4'-bis(m-aminophenoxy) diphenyl sulfone. The cyclization of imide ring in the poly(ether-amide-amic acid)s may be regarded as an intramolecular acylation of amide group by o-carboxyl group. As a result of this reseach, the effects on the conversion to poly(ether-amide-imide)s have been found by changing the ratio of cosolvents in the cyclization mixture.