• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1183-1186
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• 2011

The unique Br signature was utilized for C-terminal amino acid sequencing of model peptides. C-terminal carboxyl group was selectively derivatized in peptides, containing side chain carboxyl group, using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) and Br was introduced using 4-bromophenylhydrazine hydrochloride (BPH) in a one pot reaction. Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) tandem mass spectra were obtained carrying the Br signature in the y-series ions. The Br signature facilitated C-terminal sequencing and discrimination of C-terminal carboxyl groups in the free acid and amide forms.

• Textile Coloration and Finishing
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• v.10 no.2
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• pp.8-17
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• 1998

In this study we have examined electroless chemical plating on the plasma grafted poly [ethylene terephathalate］(PET) fabric in order to improve the interfacial adhesion between metal and fiber. The vapour phase of acrylic acid introduced on the PET surface and the graft polymerization was carried out by using cold plasma, resulting in the grafting yield of 0.8-1.3 wt％. The carboxyl group of the plasma grafted was identified by FT-IR-ATR spectra. The Interfacial adhesion was related to the carboxyl group. After electroless chemical plating of nickel, it showed that the more the carboxyl, the better the interfacial adhesion. Comparing to the untreated, the plasma grafted fabric showed fairly good interfacial adhesion(5B grade, ASTM D3359) . The shielding effect of electromagnetic wave showed 95dB. The shielding effect depends on the fabric structure, the surface structure, and the cross sectional shape of fibers. The dense fabric structure, the etched surface like a microcrater, and the trigonal cross sectional shape were prefered.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.182-182
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• 1994

Angiotensin converting enzyme (ACE)을 비가역적으로 불활성화시킴으로써 오랫동안 작용할 수 있는 고혈압치료제로서의 ACE억제제를 개발하기 위하여pseudomechanism-based inhibition이라는 새로운 억제기전을 가질 것으로 추정되는 아래 그림과 같은 기본 분자구조를 갖는 epoxide 유도체들을 합성하여 in vitro에서 ACE활성 억제효과를, HPLC법을 이용하여 측정하였다. 그 결과 합성되어진 epoxide 유도체들은, epoxide group대신에 sulfhydryl 또는 carboxyl group으로 치환되어져 있는 기존의 ACE 억제제들보다도 효능이 현저히 저하됨으로써, ACE의 $Zn^{2+}$ binding site와는 배위결합력이 미약하다는 것을 의미하여 준다. 또한 유도체들의 phenylring에 chloride, hydroxyl, nitro group과 같은 polar group 의 도입으로 말미암아 ACE 억제효과가 저하됨으로써 이 부위에서의 hydrophobic interaction이 ACE를 억제하는데 중요하다는 것을 시사해 주며 이외에도 이미 알려진 바와같이 carbonyl carbon과 인접한 carbon atom에 methyl group의 도입이 억제효과에 중요한 역활을 하였다. 따라서 향후에는 ACE의 $Zn^{2+}$ binding site와 강력한 배위결합을 하는 carboxyl group을 도입하고 epoxide의 위치를 변경시키며 또한 hydrophobic interaction하는 부위의 구조를 변화시켜 보다 효능이 우수한 새로운 기전의 ACE억제제를 개발해 나가고자 한다.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1821-1826
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• 2014

The adsorption characteristics of the methylene blue (MB) were studied using three activated carbons such as ACA and ACB with similar specific surface area (1,185 and $1,105m^2/g$), and ACC with relatively high specific surface area ($1,760m^2/g$). The surface chemical properties of these activated carbons were investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that ACA had more functional groups (with phenol, carbonyl, and carboxyl etc.) than ACB (with carbonyl and carboxyl) and ACC (with carboxyl). The isotherm data were fitted well by Langmuir isotherm model. The adsorption capacities of ACA, ACB, and ACC for MB were 454.7 mg/g, 337.7 mg/g, and 414.0 mg/g, respectively. As phenol and carboxyl content of the surface on activated carbon increased, MB adsorption capacity was increased. Although ACA had a smaller specific surface area than ACC, the content of phenol and carboxyl group was abundant, so MB adsorption capacity was found to be higher than ACC.

• Macromolecular Research
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• v.13 no.3
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• pp.236-242
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• 2005

Three dithioester-derived carboxyl acid functionalized RAFT(reversible addition-fragmentation chain transfer) agents, viz. acetic acid dithiobenzoate, butanoic acid dithiobenzoate and 4-toluic acid dithiobenzoate, were used in the RAFT bulk polymerization of styrene, in order to study the effects of the R-group structure on the living nature of the polymerization. By conducting the polymerization with various concentrations of the RAFT agents and at different temperatures, it was found that the R-group structure of the RAFT agents plays an important role in the RAFT polymerization; the bulky structure and radical stabilizing property of the R-group enhances the living nature of the polymerization and allows the polymerization characteristics to be well controlled.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.231-244
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• 2020

As a way of finding value-added materials from waste medium density fiberboard (MDF), this study characterized cellulose nanocrystals (CNCs) isolated by ammonium persulfate (APS) oxidation using recycled MDF fibers. Chemical composition of the recycled MDF fibers was done to quantify α-cellulose, hemicellulose, lignin, nitrogen, ash and extractives. The APS oxidation was performed at 60 ℃ for 16 h, followed by ultrasonication, which resulted in a CNC yield of 11%. Transmission electron microscope images showed that rod-like CNCs had an average length and diameter of 167±47 nm and 8.24±2.28 nm, respectively, which gave an aspect ratio of about 20. The conductometric titration of aqueous CNCs suspension resulted in a carboxyl content of 0.24 mmol/g and the degree of oxidation was 0.04. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy clearly showed the presence of carboxyl group on the CNCs prepared by the APS oxidation. The change of pH of the aqueous CNC suspension from 4 to 7 converted the carboxyl group to sodium carboxylate group. These results showed that the APS oxidation was facile and CNCs had a one-step preparation method, and thus suggested an optimization of the oxidation condition in future.

• Journal of Adhesion and Interface
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• v.2 no.1
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• pp.18-22
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• 2001

Surface morphology of [poly(vinylidene fluoride)/poly(methyl methacrylate)] (PVDF/PMMA) was investigated on the basis of atomic force microscopy and differential scanning calorimeter measurements. The surface of (PMMA/PVDF) and (H14-PMMA/PVDF) blend films was fully composed with PVDF crystals. Although the difference of surface free energy between PMMA and PVDF is increased with increasing carboxyl group content in PMMA, however, in the case of (H24-PMMA/PVDF) blend film surface, the existence of aggregated H-PMMA was observed. It was found that the degree of surface enrichment of the blend is more affected by the magnitude of intermolecular interaction than the surface free energy difference, Besides, the introduction of carboxyl group for miscible (PVDF/PMMA) blend decreased the miscibility in the blend.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.335-342
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• 2021

Studies on the side effects of contrast agents are being discussed based on various cases, but studies analyzing the chemical structure of the underlying contrast agents are difficult to understand as the manufacturers have not disclosed them. Therefore, in this study, the chemical structure of the contrast medium was analyzed using ¹H-NMR spectrometer for Omnipaque contrast medium prepared from Iohexol, which is a nonionic iodide contrast medium, Xenetix contrast medium from Iobitridol, and Iomeron contrast medium from Iomeprol. As a result, it was found that the Omnipaque contrast medium of Iohexol had 6 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. It was found that the Xenetix contrast medium of the iobitridol formulation had 6 carboxyl groups, 3 carbonyl groups, 2 amine groups, and 4 cyano groups. It was found that the Iomeron contrast agent of the Iomeprol formulation had 5 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. As shown in this study, the chemical structure of the non-ionic monomer contrast agent increases its affinity with water by binding a number of hydroxyl groups (OH) to the carboxyl group. It is necessary to accurately identify each of these factors and analyze the physical and chemical changes of the contrast medium according to various environmental factors.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.246-253
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• 1998

Heavy metal-tolerant microorganisms, such as Pseudomonas putida, P. aeruginosa, P. chlororaphis and P. stutzeri which possessed the ability to accumulate cadmium, lead, zinc and copper, respectively, were isolated from industrial wastewaters and mine wastewaters polluted with various heavy metals. The binding sites of heavy metal in the cells were investigated by chemical modification of functional groups the cell walls. To determine the binding sites of heavy metal in the cells, electrochemical charge of amine and carboxyl groups in the cell walls of heavy metal-tolerant microorganisms were chemically modified. Chemical modifications of amine groups did not affect the heavy metal uptake as compared to native cell walls. In contrast, modifications of carboxyl groups drastically decreased heavy metal uptake as compared to native cell walls, and electron microscopy confirmed that the form and structure of the heavy metal uptake were different from those of native cell walls. The results suggested that the carboxyl groups were the major sites of heavy metal uptake in the heavy metal-tolerant microorganism cell.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3217-3220
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• 2010

The electronic structures and bonding configuration of histidine on Ge(100) have been investigated with various sample treatments using core-level photoemission spectroscopy (CLPES). Interpretation of the Ge 3d, C 1s, N 1s, and O 1s core level spectra being included in these systems revealed that both the imino nitrogen in the imidazole ring and the carboxyl group in the glycine moiety concurrently participate in the adsorption of histidine on a Ge(100) surface at 380 K. Moreover, we could clearly confirm that the imino nitrogen with a free lone pair in the imidazole group adsorbs on Ge(100) more strongly than the carboxyl group in the glycine moiety by examining systems annealed at various temperatures.