• Title/Summary/Keyword: in-group bonds

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Dielectric Characteristics through 2D-correlation Analysis of SiOCH Thin Film deposited by BTMSM/O2 High Flow Rates (BTMSM/O2 고유량으로 증착된 SiOCH 박막의 2차원 상관관계 분석을 통한 유전특성 연구)

  • Kim, Min-Seok;Hwang, Chang-Su;Kim, Hong-Bae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.6
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    • pp.544-551
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    • 2008
  • We have studied the dielectric characteristics of low-k interlayer dielectric materials fabricated by PECVD for various precursor's flow rates. BTMSM precursor was introduced with the flow rates from 42 sccm to 60 sccm by 2 sccm step in the constant flow rate of 60 sccm $O_2$. The absorption intensities of Si-O-$CH_x$ bonding group and Si-$CH_x$ bonding group changed synchronously for the variation of precursor flow rate, but the intensity of Si-O-Si(C) responded asynchronously with the $CH_x$ combined bonds. The heat treatment reduced the FTIR absorption intensity of Si-O-$CH_x$ bonding group and Si-$CH_x$ bonding group but increased the intensity of Si-O-Si(C). The nanopore and free space formed by the increasement of caged link mode and cross link mode of Si-O-Si(C) group implied the origin of low-k SiOCH films.

Rhodium-Catalyzed Reductive Decyanation of Nitriles Using Hydrosilane as a Reducing Agent: Scope, Mechanism and Synthetic Application

  • Tobisu, Mamoru;Nakamura, Ryo;Kita, Yusuke;Chatani, Naoto
    • Bulletin of the Korean Chemical Society
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    • v.31 no.3
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    • pp.582-587
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    • 2010
  • A rhodium-catalyzed reductive cleavage reaction of carbon-cyano bonds is developed using hydrosilane as a mild reducing agent. A wide range of nitriles, including aryl, benzyl, and $\beta$-hydrogen containing alkyl cyanides are applicable to this decyanation reaction. The method is also applicable to organic synthesis, in which benzyl cyanide is used as a benzyl anion equivalent and a cyano group functions as a removable ortho-directing group.

The Crystal and Molecular Structure of Phlorizin Dihydrate

  • Shin, Whan-Chul
    • Bulletin of the Korean Chemical Society
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    • v.6 no.1
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    • pp.7-11
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    • 1985
  • The crystal structure of phlorizin, a ${\beta}$ -D-glucopyranoside of a flavonoid dihydrochalcone phloretin, has been determined by single crystal diffraction methods using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with Cu $K{\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 4.9094 (2), b = 19.109 (1), c = 23.275 (4) $\AA$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.047 for the 1697 observed reflections. The dihydrochalcone moiety is flat and fully extended. The glucose ring has the $^4C_1$ chair conformation and the conformation of the primary alcohol group is gauche-gauche. The crystal packing is dominated by an extensive hydrogen bonding pattern. There are one strong and two weak intramolecular hydrogen bonds in the phlorizin molecule.

THE PROTEIN COMPOSITION OF GINGIVAL CREVICULAR FLUID SAMPLED FROM NORMAL SUBJECTS AND PATIENTS WITH PERIODONTAL DISEASE (정상치은열구액과 치주질환시 치은열구액의 단백질 조성비교에 관한 연구)

  • Kim, Soo-Ah;Lee, Jin-Young;Kim, Hyong-Seop
    • Journal of Periodontal and Implant Science
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    • v.23 no.3
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    • pp.391-398
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    • 1993
  • Gingival crevicular fluid (GCF) is a promising source for markers of destructive periodontal disease activity. This study was undertaken to evaluate the protein composition of GCF in varying stages of the gingival inflammatory response. GCF sampled from 26 people with clinically healthy gingiva and 18 people with periodontitis were examined via sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS/PAGE). The result were as follows. 1. Total amount of GCF protein of diseased group significantly different from that of normal group. But difference in protein concentration was not that significant. 2. In analyzing GCF with SDS/PAGE, it was suggested that albumin is used as indicator plasma protein leakage because of heavily staining bond of albumin in patients with periodontal disease. 3. In diseased group, overall bonds of protein and bands of high molecular weight protein were heavily stained. It was proved useful information on high molecular plasma protein leakage with increasing vascular permeability due to inflammation.

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Effects of Cu Addition on Microstructural and Mechanical Properties of Mo-Cu-N Coatings (Cu 첨가가 Mo-Cu-N 코팅의 미세구조와 기계적 특성에 미치는 영향)

  • Kim, Soobyn;Yoon, Hae-Won;Lee, Han-Chan;Moon, KyoungIl;Hong, Hyun Seon
    • Journal of Surface Science and Engineering
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    • v.52 no.4
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    • pp.227-232
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    • 2019
  • Mo-N based coatings have been studied for enhancing mechanical characteristics of thin films. In the case of Mo-X-N coatings, the microstructure and mechanical properties can be affected by the addition of the third element. In this work, Mo-Cu-N coatings were successfully fabricated with varying the Cu content from 4.5 at% to 31 at% by the co-sputtering method. Thus, properties of the coatings were analyzed by EDS, SEM, XRD, AFM, nano indentation and scratch test techniques. From observed results, MoxN bonds were made in a nitrogen atmosphere and Cu elements were present at grain boundaries. In addition, coatings with the Cu content above 14 at% had a Cu3N peak in the XRD results. Thus, it is suggested that the formation of Cu3N phase affected the microstructure and mechanical properties of Mo-Cu-N coatings. Mechanical properties of Mo-Cu-N coatings were found to be relatively better at Cu content of about 12 at%.

Characterization of the UV Oxidation of Raw Natural Rubber Thin Film Using Image and FT-IR Analysis

  • Kim, Ik-Sik;Lee, Bok-Won;Sohn, Kyung-Suk;Yoon, Joohoe;Lee, Jung-Hun
    • Elastomers and Composites
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    • v.51 no.1
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    • pp.1-9
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    • 2016
  • Characterization of the UV oxidation for raw natural rubber (NR) was investigated in controlled conditions through image and FT-IR analysis. The UV oxidation was performed on a thin film of natural rubber coated on a KBr window at 254 nm and room temperature to exclude the thermal oxidation. Before or after exposure to UV light, image of the NR thin film was observed at a right or tilted angle. FT-IR absorption spectra were measured in transmission mode with the UV irradiation time. The UV oxidation of NR was examined by the changes of absorption peaks at 3425, 1717, 1084, 1477, 1377, and $833cm^{-1}$ which were assigned to hydroxyl group (-OH), carbonyl group (-C=O), carbon-oxygen bond (-C-O), methylene group $(-CH_2-)$, methyl group $(-CH_3)$, and cis-methine group $(cis-CCH_3=CH-)$, respectively. During the initial exposure period, the results indicated that the appearance of carbonyl group was directly related to the reduction of cis-methine group containing carbon-carbon double bond (-C=C-). Most of aldehydes or ketones from carbon-carbon double bonds were formed very fast by chain scission. A lot of long wide cracks with one orientation at regular intervals which resulted in consecutive chain scission were observed by image analysis. During all exposure periods, on the other hand, it was considered that the continuous increment of hydroxyl and carbonyl group was closely related to the decrement of methylene and methyl group in the allylic position. Therefore, two possible mechanisms for the UV oxidation of NR were suggested.

A Mechanistic Study on the Nucleophilic Addition Reactions of Benzylamines to the Activated Olefins

  • Oh, Hyuck-Keun
    • Bulletin of the Korean Chemical Society
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    • v.29 no.6
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    • pp.1195-1198
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    • 2008
  • Kinetic studies of the additions of benzylamines to a noncyclic dicarbonyl group activated olefin, methyl $\alpha$-acetyl-$\beta$ -phenylacrylates (MAP), in acetonitrile at 30.0 ${^{\circ}C}$ are reported. The rates are lower than those for the cyclic dicarbonyl group activated olefins. The addition occurs in a single step with concurrent formation of the $C_\alpha$ -N and $C_\beta$ -H bonds through a four-center hydrogen bonded transition state. The kinetic isotope effects ($k_H/k_D$ > 1.0) measured with deuterated benzylamines ($XC_6H_4CH_2ND_2$) increase with a stronger electron acceptor substituent ($\delta\sigma$ X > 0) which is the same trend as those found for other dicarbonyl group activated series (1-4). The sign and magnitude of the cross-interaction constant, ρXY, is comparable to those for the normal bond formation processes in the $S_N2$ and addition reactions. The relatively low ${\Delta}H^\neq$ and large negative ${\Delta}S^\neq$ values are also consistent with the mechanism proposed.

The Solvent-Independent Structure of Piroxicam (피록시캄의 용매 비의존 결정구조)

  • Kim, Bong-Hee;Suh, Il-Hwan;Jhee, Ok-In;Suh, Jong-Myung;Suh, Jung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.18 no.4
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    • pp.209-215
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    • 1988
  • The three-dimensional structures of piroxicam crystallized from two different solvents, toluene and toluene/hexane mixture respectively, are proved identical: $C_{15}H_{13}N_3O_4S,\;M\;=\;331.35$, monoclinic, a = 7.128(1), b = 15.146(2), c = 13.956(2) ${\AA},\;{\beta}=\;97.33(1)^{\circ},\;V\;=\;1494.37{\AA}^{3},\;Dx\;=\;1.472\;g/cm^{3},\;Z\;=\;4,\;space\;group\;P2_{1}/c,\;Mo\;K{\alpha}(\lambda=\;0.71073\;{\AA})$, F(000) = 688, T = 295 K, R = 0.0611 for 1993 unique observed reflections. The thiazine ring exhibits a half chair conformation. An amide group is involved in an intramolecular hydrogen bond to the hydroxy group, O(17)-H(17)${\cdots}O(15){\AA}$. The molecule is planar within 2 ${\AA}$ with the interplanar angle $127.9(4)^{\circ}$ between pyridine and benzene rings. A molecular chain parallel to [011] is formed by two intermolecular hydrogen bonds N(16)-H(6)${\cdots}O(11)$ and C(6)-H(6)${\cdots}O(11)$, and the molecular chains are held together by van der Waals forces.

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Preparation of Graphene/Waterborne Polyurethane Nanocomposite through in-situ Polymerization (In-situ 중합을 통한 그래핀/수분산 폴리우레탄 나노 복합체 제조)

  • Cha, Ji-Jung;Yim, Jin-Heong
    • Polymer(Korea)
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    • v.37 no.4
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    • pp.507-512
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    • 2013
  • A graphene/waterborne polyurethane (WPU) nano composite was prepared by in-situ polymerization of PU and graphene having isocyanate (iGO) group in order to improve physicochemical/electrical characteristics. The properties of the graphene/WPU nanocomposite can effectively be enhanced as compared pristine WPU; up to 57% of tensile strength and $10^2$ fold of electrical conductivity with introduction of 2 wt% graphene. In addition, mechanical/electrical properties of the graphene/WPU nanocompsite were higher than those of graphene/WPU composite prepared by a simple physical blend method. It might attribute to homogeneous dispersion of iGO in the WPU matrix via covalent bonds and hydrogen bonds between WPU and iGO from the results of morphological analysis by scanning electron microscopy (SEM).

Molecular Theory of Plastic Deformation (I). Theory (소성변형의 분자론 (제1보). 이론)

  • Kim Chang Hong;Ree Taikyue
    • Journal of the Korean Chemical Society
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    • v.21 no.5
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    • pp.330-338
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    • 1977
  • In order to elucidate the plastic deformation of solids, the following assumptions were made: (1) the plastic deformation of solids is classified into two main types, the one which is caused by dislocation movement and the other caused by grain boundary movement, each movement being restricted on a different shear surface, (2) the dislocation movement is expressed by a mechanical model of a parallel connection of various kinds of Maxwell dislocation flow units whereas the grain boundary movement is also expressed by a parallel connection of various kinds of Maxwell grain boundary flow units; the parallel connection in each type of movements indicates that all the flow units on each shear surface flow with the same shear rate, (3) the latter model for grain boundary movement is connected in series to the former for dislocation movement, this means physically that the applied stress distributes homogeneously in the flow system while the total strain rate distributes heterogeneously on the two types of shear planes (dislocation or grain boundary shear plane), (4) the movement of dislocation flow units and grain boundary units becomes possible when the atoms or molecules near the obstacles, which hinder the movement of flow units, diffuse away from the obstacles.Using the above assumptions in conjunction with the theory of rate processes, generalized equations of shear stress and shear rate for plastic deformation were derived. In this paper, four cases important in practice were considered.ted N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.

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