• BMB Reports
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• 제29권1호
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• pp.38-44
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• 1996

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method, which is being used for amplifying DNA. Not only does Taq DNA polymerase have high commercial value commercial value for the polymerase chain reaction application, but it is also important in studying DNA replication, because it is apparently an homologue to E. coli DNA polymerase I, which has long been used for DNA replication study (Lawyer et ai., 1993). The crystal structure determination of Taq DNA polymerase was initiated. An X-ray diffraction pattern breaks down a crystal structure into discrete sine waves in a Fourier series. The original shape of a crystal object in terms of electron density may be represented as the sum of those sine waves with varying amplitudes and phases in three dimensions. The molecular replacement method was initially employed to provide phase information for the structure of Taq DNA polymerase. The rotation search using the program MERLOT resulted in a solution peak with 5.4 r.m.s. PC-refinement of the X-PLOR program verified the result and also optimized the orientation angles. Next, the translation search using the X-PLOR program resulted in a unique solution peak with 7.35 r.m.s. In addition, the translation search indicated $P3_121$ to be the true space group out of two possible ones. The phase information from the molecular replacement was useful in the MIR phasing experiment.

• 대한화학회지
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• 제24권4호
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• pp.280-287
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• 1980

發癌物質과 DNA 鹽基雙間의 分子錯物形成에서 可能性있는 配置(orientation)를 決定하였다. 아데닌-티민 염기쌍에서는 티민쪽에서, 구아닌-시토신 염기쌍에서는 구아닌쪽에서 分子錯物을 形成한다.

• Bulletin of the Korean Chemical Society
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• 제23권11호
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• pp.1595-1603
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• 2002

In this paper we have presented the results of diffusion behavior of model systems for eight liquid n-alkanes ($C_{12}$-$C_{44}$) in a canonical (NVT) ensemble at several temperatures using molecular dynamics simulations. For these n-alkanes of small chain length n, the chains are clearly <$R_{ee}^2$>/6<$R_g^2$>>1 and non-Gaussian. This result implies that the liquid n-alkanes over the whole temperatures considered are far away from the Rouse regime, though the ratio becomes close to the unity as n increases. Calculated self-diffusion constants $D_{self}$ are comparable with experimental results and the Arrhenius plot of self-diffusion constants versus inverse temperature shows a different temperature dependence of diffusion on the chain length. The global rotational motion of n-alkanes is examined by characterizing the orientation relaxation of the end-to-end vector and it is found that the ratio ${\tau}1/{\tau}2$ is less than 3, the value expected for a isotropically diffusive rotational process. The friction constants ${\xi}$of the whole molecules of n-alkanes are calculated directly from the force auto-correlation (FAC) functions and compared with the monomeric friction constants ${\xi}_D$ extracted from $D_{self}$. Both the friction constants give a correct qualitative trends: decrease with increasing temperature and increase with increasing chain length. The friction constant calculated from the FAC's decreases very slowly with increasing temperature, while the monomeric friction constant varies rapidly with temperature. By considering the orientation relaxation of local vectors and diffusion of each site, it is found that rotational and translational diffusions of the ends are faster than those of the center.

• 폴리머
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• 제26권4호
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• pp.431-438
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• 2002

편광 푸리에 변환 적외선 분광법을 이용하여 액정 디스플레이의 배향막으로 널리 사용되는 폴리이미드 필름의 편광 자외선 조사에 따른 액정의 배향성과 열적 안정성을 연구하였다. 편광자외선이 조사된 폴리이미드의 경우, 조사된 편광자외선의 극성 방향에 평행한 폴리이미드 분자들의 우선적인 광분해 반응으로 인하여 편광자외선 조사 후 남아 있는 폴리이미드 분자들은 조사된 편광자외선 극성 방향과 수직 배향을 나타내었다. 하지만 러빙 처리된 폴리이미드 필름은 러빙 방향과 평행하게 폴리이미드 분자들의 재배향이 유도됨을 확인하였다. 또한 편광자외선이 조사된 폴리이미드 배향막이 편광자외선 조사를 통한 폴리이미드 분자들의 단편화 반응 때문에 러빙 처리된 폴리이미드 배향막 보다는 열적 안정성이 저하됨을 확인하였다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.333-333
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• 2006

We synthesized two novel polynorbornene derivatives, chiral poly(norbornene acid methyl ester) (C-PNME) and racemic poly(norbornene acid n-butyl ester) (R-PNME), which are potential low dielectric constant materials for applications in advanced microelectronic and display devices. Thin films of these polymers deposited on substrates were investigated by structural analyses using synchrotron grazing incidence X-ray scattering, specular reflectivity and ellipsometry. These analyses provided important information on the structure, electron density gradient across film thickness, chain orientation, refractive index and thermal expansion of the polymers in substrate-supported thin films. The structural characteristics and properties of the thin films were first dependent on the polymer chain' tacticity and further influenced by film thickness and thermal annealing.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2723-2725
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• 2014

Recently we have reported a novel class of anion receptors which are based on 2n-crown-n topology. Trioxane derivatives are capable of anion sensing through pure aliphatic C-H hydrogen bonding. In this work, we highlight another interesting property, i.e., they can also recognize cations as normal crown ethers (3n-crown-n topology). Since the same functional moiety can recognize anions and cations, these coronands are predicted to be amphi-ionophores. However, we could not detect cations even in the gas phase. Considering trioxane is analogous to [$1_6$]starand, this was rather counter-intuitive. The calculation results show that these coronands can detect alkali metals with very low affinity. The low affinity toward cations should be responsible for this failure of experimental detection. With careful theoretical study, we found that this low affinity toward cations could be explained by the unfavorable charge-dipolar moiety orientations as proposed by Cui et al. As in the case of [$1_6$]starand, this is an example that underscores the importance of charge-dipolar moiety orientation in supramolecular interactions.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.311-311
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• 2006

The morphology of Poly(styrene-b-methylmethacrylate) (P(S-b-MMA)) block copolymer thin films deposited on silicon wafers was controlled by treating the substrates with Self-Assembled Monolayers (SAM) of phenylsilanes with different alkyl chain lengths. It was found that the treatment with SAM strongly modified the substrates properties, especillay the surface energy, as compared with bare silicon oxide. By futher adjusting the molecular weight of P(S-b-MMA), a variety of morphologies could be generated, including a perpendicular orientation of lamellea of PS and PMMA, which is required for industrial applications.

• Nuclear Engineering and Technology
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• 제6권3호
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• pp.155-159
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• 1974

메틸 및 에틸 시아노 아세테이트의 각종 회전체에 대하여 확장 Huckel 분자 궤도법 계산을 실시하였다. 결과로 C≡N 기는 cis 배치가 안정하고 $CH_3$기는 trans 배치가 안정함을 알았다. 또 안정화 에너지의 대부분은 정전기적인 일자간의 인력에 기인되는 것임을 밝혔다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 정기총회 및 동계학술연구발표회
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• pp.203-203
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• 2009

We report on the epitaxial growth of tetragonal $DO_{22}$-type Mn3Ga films on GaSb (001) using molecular beam epitaxy and the related structural and magnetic properties. The as-studied $Mn_3Ga$ film was found to exhibit relatively small coercivity around 400 Oe, which differs greatly from the hard magnetic properties of $Mn_3Ga$ bulk specimen or films that are normally reported. This difference was probably attributed to the effects of the GaSb (001) substrate that forced the $Mn_3Ga$ film to be two-dimensionlly stabilized in the (114) orientation and thus led to the modified intrinsic properties of $Mn_3Ga$ films. The growth orientation of the Mn3Ga (114)//GaSb (001) also caused the easy magnetocrystalline direction located in the film plane due to the dominant shape anisotropy in the thin films.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.420-422
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• 1995

PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.