• 접착 및 계면
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• 제3권3호
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• pp.7-14
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• 2002

Poly(ethylene-co-methylacrylate)(PEMA)를 KOH, 암모니아 수용액으로 가수분해, ammonolysis 시켜서 측기에 -COOK, $-CONH_2$, -COOH를 갖는 수분산 형태의 변성 폴리에틸렌(m-PE)을 제조하였다. Infrared spectroscopy, 원소 분석 및 atomic absorption 분석 등을 통하여 m-PE 측기의 종류 및 조성비를 조사하였으며 수분산액의 고형분 함량에 따른 점도 및 표면장력을 측정하였다. 제조된 수분산액은 측기의 조성에 따라 안정도, 투명도 등이 변화하였다. 측기 중에서 -COOK가 수분산에 가장 큰 영향을 주었으며 -COOK 조성비가 20 mol% 이상이 되어야 안정한 분산을 얻을 수 있었고 또한 -COOK 조성비가 높을수록 수분산액은 투명하였다. 동일 -COOK 조성비에서는 아마이드의 농도가 높을수록 탁도가 증가하여 친수성이 떨어짐을 알 수 있었다. 분산액의 고형분 함량에 따른 점도를 측정하면 -COOK 조성비가 클 경우 낮은 고형분 함량에서 급격한 점도 증가가 일어나 고분자 사슬사이의 얽힘이 쉽게 일어남을 알 수 있으며 표면장력은 -COOK 조성비가 클 경우 작은 값을 나타내었다.

• 대한화학회지
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• 제52권1호
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• pp.36-46
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• 2008

가진 1차 arylselenocarboxylic amide의 고리화는 여러가지 새로운 2,4-diaryl-1,3-selenazoles에 사용되었다. 염소, 브롬, 요오드를 사용한 2,4-diaryl-1,3-selenazoles의 할로겐화는 좋은 수율의 새로운 1,1-dihalo-2,4-diaryl-1,3-selenazoles를 준다. AIDS virus(HIV-1 and HIV-2)에 대하여 몇몇의 1,1-dihalo-2,4-diaryl-1,3-selenazoles의 항바이러스 활성도를 검사하였다. 그것들은 HIV-1에 대한 약간의 대생물활성을 보였다. 모든 화합물은 원소분석, 1H NMR 그리고 질량 분광분석 정보로 구조분석 하였다. 2-(3,4-dimethoxyphenyl)-4-(4-bromophenyl)-1,3-selenazole의 결정구조도 보였다.

• Bulletin of the Korean Chemical Society
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• 제23권6호
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• pp.824-829
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• 2002

New di-N-cyanomethylated tetraaza macrocycle 2.13-bis(cyanomethyl)-5.16-dimethyl-2,6,13,17-tetraazatricyclo[$16.4.0.0^7.12$]docosane $(L^2)$ has been prepared by the reaction of 3, 14-dimethyl-2,6,13,17-tetraazatricyclo $(L^1)$ with bromoacetonitrile. The square-planar complexes $[ML^2](ClO_4)_2(M=Ni(II)$ or Cu(II) can be prepared by the reaction of $L^2$ with the corresponding metal ion in acetonitrile. The cyanomethyl groups of $[ML^2](ClO_4)_2readily$ react with water to $yield[ML^3](ClO_4)_2$ containing pendant amide groups. The trans-octahedral complexes $[ML^4](ClO_4)_2$, in which two imidate ester groups are coordinated to the metal ion, can be also prepared by the reaction of $[ML^2](ClO_4)_2with$ methanol under mild conditions. The hydrolysis and alcoholysis reactions of $[ML^2](ClO_4)_2are$ promoted by the central metal ion, in spite of the fact that the cyanomethyl group is not involved in intramolecular coordination. The reactions are also promoted by a base such as triethylamine but are retarded by an $acid(HClO_4).Interestingly$, the imidate ester groups of $[ML^4]^2$ are unusually resistant to hydrolysis even in 0.1 M $HCIO_4$ or 0.1 M NaOH aqueous solution. Crystal structure of $[NiL^4](ClO_4)_2shows$ that the Ni-N (pendant imidate ester group) bond is rlatively strong; the Ni-N bond distance is shorter then the Ni-N(tertiary) distance and is similar to the Ni-N (secondary) distance.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2900-2904
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• 2013

We present the synthesis and characterization of DTPA-bis(histidylamide) (1a), DTPA-bis(aspartamide) (1b), and their gadolinium complexes of the type $[Gd(L)(H_2O)]$ (2a:L = 1a; 2b:L = 1b). Thermodynamic stabilities and $R_1$ relaxivities of 2a-b compare well with Omniscan$^{(R)}$, a well-known commercial, extracellular (ECF) MRI CA which adopts the DTPA-bis(amide) framework for the chelate: $R_1$ = 5.5 and 5.1 $mM^{-1}$ for 2a and 2b, respectively. Addition of the Cu(II) ion to a solution containing 2b triggers relaxivity enhancement to raise $R_1$ as high as 15.3 $mM^{-1}$, which corresponds to a 300% enhancement. Such an increase levels off at the concentration beyond two equiv. of Cu(II), suggesting the formation of a trimetallic ($Gd/Cu_2$) complex in situ. Such a relaxivity increase is almost negligible with Zn(II) and other endogenous ions such as Na(I), K(I), Mg(II), and Ca(II). In vivo MR images and the signal-to-noise ratio (SNR) obtained with an aqueous mixture of 2b and Cu(II) ion in an 1:2 ratio demonstrate the potentiality of 2 as a copper responsive MRI CA.

• Macromolecular Research
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• 제13권1호
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• pp.45-53
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• 2005

In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacryl­amide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylenebis­acrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g­PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-poly­methacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the Alg-g-PMAM or the H-Alg-g-PMAM was characterized by FTIR spectroscopy. The effects of the grafting variables (i.e., concentration of MBA, MAM, and APS) and the alkaline hydrolysis conditions (i.e., NaOH concentration, hydrolysis time, and temperature) were optimized systematically to achieve a hydrogel having the maximum swelling capacity. Measurements of the absorbency in various aqueous salt solutions indicated that the swelling capacity decreased upon increasing the ionic strength of the swelling medium. This behavior could be attributed to a charge screening effect for monovalent cations, as well as ionic cross-linking for multivalent cations. Because of the high swelling capacity in salt solutions, however, the hydrogels might be considered as anti-salt superabsorbents. The swelling behavior of the superabsorbing hydrogels was also measured in solutions having values of pH ranging from 1 to 13. Furthermore, the pH reversibility and on/off switching behavior, measured at pH 2.0 and 8.0, suggested that the synthesized hydrogels were excellent candidates for the controlled delivery of bioactive agents. Finally, we performed preliminary investigations of the swelling kinetics of the synthesized hydrogels at various particle sizes.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.75-75
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• 2003

We report here the results on N-acetyl-N'-dimethylamide of proline (Ac-Pro-NM $e_2$) calculated using the ab initio molecular orbital method with the self-consistent reaction field (SCRF) theory at the HF level with the 6-31+G(d) basis set to investigate the conformational preference of polyproline depending on the cis/trans peptide bonds and down/up puckerings along the backbone torsion angle $\square$ in the gas phase, chloroform, and water. In the gas phase, Ac-Pro-NM $e_2$ has seven local minima of tFd, tFu, cFd, cFu, cAu, tAu, and cAd conformations. In particular, polyproline conformations tFd, tFu, cFd, and cFu are found to be more stable than $\square$-helical conformations cAu, tAu, and cAd. In contrast, Ac-Pro-NHMe has seven local minima of tCd, tCu, cBd, cAu, tAu, cFd, and cFu conformations. Conformations tCd and tCu are found to be most stable, which is ascribed to the intramolecular hydrogen bond between C=O of acetyl group and $N^{~}$ H of N'-methyl amide group. The stability of the cFd conformation (i.e., the polyproline I structure) in chloroform is somewhat increased, relative to that in water, although tFd and tFu conformations (i.e., the polyproline II structure) are dominate both in chloroform and water. The population of backbone conformations feasible in chloroform and water is consistent with the experiments. This work is supported by a Korea Research Foundation Grant (KRF-2002-041-C00129).

• 한국식품영양과학회지
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• 제20권4호
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• pp.306-311
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• 1991

Streptozotocin(STZ)에 의해서 유도된 당뇨성 쥐에서 nicotinamide의 영향을 알아보기 위하여 혈중 당의농도, 지질함량 변동과 동맥경화 지표와의 상관관계를 관찰하였다. STZ 투여로서 혈중당의 농도가 증가되던 것이 nicotinamide의 전처리로 정상상태로 억제되었고 total lipid 및 triglyceride 함량에서도 STZ 투여로 증가되던 것이 nicotinamide 전처리로 억제되었으나 phospholipid 함량에는 별다른 영향이 없었다. 혈중 total cholesterol. VLDL, LDL-cholesterol 함량 및 동맥경화 지표는 STZ에 의해 증가되었으나 nicotinamide 전처리로 저지되었으며 HDL-cholesterol 함량에서는 STZ 투여에 의해 감소되던 것이 nicotinamide의 전처리로 회복되었다. 혈중 lipase의 활성은 STZ 투여로서 억제되던 것이 nicotinamide의 전처리로 회복되었다. s-ALT 및 s-AST의 활성은 STZ 투여군이나 nicotinamide 전처리 군에서나 별다른 영향이 없었다. 이상의 실험 결과에서 nicotinamide의 전처리는 STZ에 의하여 유도되는 당뇨병을 예방할 것이라는 사실은 다른 측면에서 뒷받침하는 것으로 본 연구에서는 당뇨성 고지혈증의 예방에 nicotinamide가 유용하게 응용될 수 있는 가능성을 제시하고 있다.

• 통합자연과학논문집
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• 제3권4호
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• pp.226-230
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• 2010

Calculation of partial charge is important in chemistry. However, because there are many methods developed, it is of considerable interest to know how to calculate and apply properly to address various chemical problems. For basis set, usually double zeta quality is acceptable, and double zeta polarization function would be enough for most cases. To describe electronic state more accurately, Many electron configurations would be necessary to describe highly strained or anionic species. The NPA population introduced new concept about amide bonds, i.e., the planar geometry of nitrogen atom may not come from resonance, but from the lowering of p-orbital energy by electronegative carbonyl carbon atom. The issues for hypervalent atomic charges was also addressed by various charge derivation scheme. When the charge schemes were applied to organolithium compounds, the ionic nature of boding was revealed. This comes from the fact that previous Mulliken partial atomic charges overemphasized the covalent character, wihout much justification. The other partial charge derivation schemes such as NPA(natural population analysis), IPP (Integrated Projected Population) showed that much more ionic picture. ESP potential derived charges are generally believed to be suitable to describe intermolecular interactions, therefore they are used for molecular dynamics simulations and CoMFA (comparative molecular field analysis). The charge derivation schemes using multipole polarization was mainly applied to reproduce experimental infrared spectroscopy. In some reports these schemes are also suitable for intermecular electrostatic interactions. Charges derived from electron density gradient have shown the some bonds are not straight, but actually bent. The proper choice of charge-calculation method along with suitable level of theory and basis set are briefly discussed.

• 대한치과마취과학회지
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• 제4권1호
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• pp.13-16
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• 2004

Background: Articaine, a new amide-type local anesthetic, was recently commercially available in Korea. The purpose of this study was to compare the anesthetic efficacy between articaine HCl and lidocaine HCl for the surgical extraction of bilateral mandibular impacted third molars. Patients and Methods: Forty young and healthy patients with bilateral impacted third molars were selected with permission. Randomly, one side of impacted third molar was operated under local anesthesia using 4% articaine and the other side under 2% lidocaine after 1 or 2 week recovery time. Intraoperative pain was evaluated via 0-10 cm visual analog scale (VAS) by both the patient and operator immediately after the operation. After 1 day and 7 days, the complications of local anesthesia were checked. Results: The pain VAS scores in articaine group, evaluated by both the patient and operator, were lower than those in lidocaine group, but they were not statistically significant (P = 0.44 and 0.54, respectively). The incidence of complications of local anesthesia between articaine and lidocaine was similar. Conclusion: In this study, articaine showed at least equal efficacy compared to lidocaine. The further dose-controlled study with more pharmacokinetic parameters will be needed.

• 자연과학논문집
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• 제7권
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• pp.47-51
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• 1995

입체 이성질체를 합성하는 방법으로 최근에 알려진 입체선택성 촉매를 이용한 유기반응을 연구 하기 위하여 비천연 아미노산인 인돌린-2- 카르본산으로 부터카르본산그룹의 환원,2차아민기의 보호화,메실화,아지도치환,환원에 의한 아민기로의 전환, 술폰화, 보호기제거등의 총 5단계의 합성과정을 거쳐 목적하는 술폰아미드를 합성하였다. 각 생성물은 관 크로마토그래피에 의하여 분리 정제후 핵자기공명스펙트럼($^1H,^13C $ NMR) 적외선 스펙트럼 등에 의하여 구조를 확인 하였다.