• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.301-304
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• 1992

Ethanolic tetracarbonylhydridoferrate, $HFe(CO)_4^-$, combined with adipaldehyde is very efficient for the selective transformation of an amino group into a perhydroazepine ring. Phenylenediamines react with adipaldehyde in the presence of $HFe(CO)_4^-$at room temperature under the atmospheric pressure of carbon monoxide to give the corresponding perhydroazepines in moderate yields. In these reactions, the molar ratio of 1.0 : 1.0 : 1.0 of the ferrate-adipaldehyde-phenylenediamine system gave one perhydroazepine ring, and the case of 1.0 : 2.0 : 1.0 gave two perhydroazepine rings, selectively.

• Animal cells and systems
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• v.12 no.4
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• pp.305-311
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• 2008

Age and growth of the mudskipper, Scartelaos gigas were investigated using the second actinost bone of the pectoral girdle, based on an analysis of 560 individuals collected from the mud flats in south west Korea. Specimens were collected semimonthly from March to September of 2003. Actinost and ring radii of each ring group showed a direct one-to-one relationship, with ring radius increasing in tandem with actinost radius. Monthly change in the marginal indices showed that ring formation occurred between May and July(mainly June), being supported by the monthly change in the gonadosomatic(highest in June) and hepatosomatic(lowest in July) indices. Because the species has not been found since November, when air temperature was less than about $10^{\circ}C$, it is thought to enter to hibernation. Therefore, it was suggested that the two new actinost rings may appear a year: one during the spawning season(May-July) and another during hibernation(since November). Although the growth of S. gigas must be limited to short periods each year from March to April and from August to October, its growth rate was considerably fast. The von Bertalanffy growth parameters of S. gigas were $TL_{\infty}$=179.36 mm, K=0.78 $year^{-1}$, $t_0$=-0.7762, and age-length key were $TL_1$=134.3 mm, $TL_2$=158.6 mm, $TL_3$=169.1 mm, $TL_4$=175.0 mm.

• Elastomers and Composites
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• v.44 no.4
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• pp.436-441
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• 2009

Semi flexible polyesters containing aromatic rings and pentamethylene groups in the main chain were synthesized by direct polycondensation reaction. The structures of these polymers were investigated by $^1H$-NMR and FT-IR and the phase transition behavior was characterized with DSC, TGA and crossed polarizing microscope. Inherent viscosities ($\eta_{inh}$) of polymers measured in phenol/p-chlorophenol/1,1,2,2-tetrachloroethane were between 0.46 and 1.30 dL/g. As increasing the linearlity of rigid moieties in polyster, melting transition temperatures ($T_m$) increased and solubilities in organic solvents decreased. P-H, P-mH and P-4H of the polymers formed turbid melts that showed stir-opalescence and nematic phase at the broad anisotropic region, However, P-R, P-C and P-2B did not exhibit any textures related to the liquid crystallinity.

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1759-1764
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• 2002

Two crystal structures of dehydrated $Ag^+-andTl^+$-exchanged zeolite X$Ag_{27}Tl_{65-}X\;and\;Ag_{23}Tl_{69-}X$have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) $^{\circ}C(a=24.758(4)\AAa=24.947(4)$, ${\AA}respectively).$, Their structures were refined to the final error indices $R_1$=0.055 and $wR_2$=0.057 with 375 reflections, and $R_1$=0.057 and $wR_2$=0.057 with 235 reflections, respectively, for which I > $3\sigma(I).$ In the structure of $Ag_{27}Tl_{65-}X,\;27\;Ag^+$ ions were found at two crystallographic sites: 15$Ag^+$ ions at site I at the center of the hexagonal prism and the remaining 12$Ag^+$ ions at site II' in the sodalite cavity. Sixty-five $Tl^+$ ions were located at three crystallographic sites: 20$Tl^+$ ions at site II opposite single six-rings in the supercage, 18$Tl^+$ ions at site I' in the sodalite cavity opposite the D6Rs, and the remaining 27$Tl^+$ ions at site III' in the supercage. In the structure of $Ag_{23}Tl_{69-}X$, 23$Ag^+$ ions were found at two crystallographic sites: 15 at site I and 8 at site II'. Sixty-nine $Tl^+$ ions are found at four crystallographic sites: 24 at site II, 17 at stie I', and the remaining 28 at two III' sites with occupancies of 22 and 6.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.43-48
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• 1995

The crystal structure of P-toluenesulfonanilide, C13H13NO2S is monoclinic, space group P21/c, a=8.777(1)Å, b=9.784(2)Å, c=15.139(2)Å, β=99.00(1)°, Z=4, V=1284.0(6)Å3, Dc=1.28g/cm33, λ(Mo-Kα)=0.71069Å, μ=2.3cm-1, F(000)=520, Temperature : 293±3K, R=0.038 for 711 Fo<3.0σ unique observed reflection. The structure was determuned by direct method and refined by full-matrix least squares refinement. Two benzene rings have the dihedral angle of 68.4°. Moleculs are accumulated according to the c axis with two fold screw and contacted by van der Walls force.

• Korean Journal of Crystallography
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• v.9 no.1
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• pp.1-5
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• 1998

The complex[Cu(L)I2, 2H2O(1) (L:3,14-Dimethyl-2,6,13,17-tetraazatricyclo [14,4,01.18, 07.12]docosane) has been prepared and structurally characterized. The complex (1) crystallizes in the triclinic system, space group P1, a=8.400(1)Å, b=8.986(3) Å, c=9.156(1) Å, α=82.42(1)˚, β=73.61(1)˚ λ=81.04(2)˚, Z=1, R for 1926 observed reflections of [F0>40(F0)], measured at 288K, was 0.042. The tetracoordination around Cu atom of complex(1) is square plane and the average bond distance of Cu-N is 2.029 (11) Å. Both six-membered chelate rings adopts a chair conformation and the five-membered ring are gauche with the sec-NH centers having the RRSS configuration.

• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.46-50
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• 1991

Some nickel(II) complexes have been derived from the condensation of isonitrosobenzoylacetone and diamine(ethylenediamine and propylenediamine) in the presence of metal ion. It is suggested that an isonitroso group(=N-O) of the ligand coordinates to metal through nitrogen atom to form a five-membered ring while other =N-O coordinates to metal through oxygen atom to form a six-membered ring in Ni(IBN)$_2$-en ((IBA)$_2$-en = N,N'-propylenebis(isonitrosobenzoylacetone imino)). But both isonitroso groups of the ligand coordinate to metal through nitrogen atoms to form five-membered rings in Ni(IBA)$_2$-pn ((IBA)$_2$-pn = N,N'-propylenebis(isonitrosobenzoylacetone imino)).

• Bulletin of the Korean Chemical Society
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• v.5 no.4
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• pp.135-140
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• 1984

The reduction of vacuum-dehydrated $Na_xAg_{12-x}-A, 0 {\le} x {\le} 9.2$, and its reoxidation by O$_2$, have been studied by X-ray powder diffraction. Also, the structure of $Na_6Na_6-A$ treated with hydrogen at room temperature has been studied by single crystal methods in the cubic space group Pm3m at $24{\circ}C (a = 12.221(2) {\AA})$. The diffraction pattern of dehydrated Ag$_{12}$-A reduced by H$_2$ contains only the (111) and (200) reflections of silver metal, indicationg that the zeolite structure has been lost, but the zeolite's diffraction pattern and structural integrity can be fully restored by oxidation with O$_2$ at 100 or 200${\circ}C$. In contrast, the structures of $Na_xAg_{12-x}-A$, x = 4.5 and 9.2, were not destroyed by treatment with hydrogen. Dehydrated Na$_6Ag_6$-A treated with 50 Torr of hydrogen gas at 24${\circ}C$ for 30 minutes has $6\; Na^+\;and\;1.27\;Ag^+$ ions at 6-ring sites. These $Ag^+ ions are associated with 2.54 Ag${\circ}$ atoms to form 1.27 $Ag_3^+$ clusters per unit cell. Also found were 0.7 $Ag_3^{2+}$ clusters per unit cell near the 8-rings. The structure was refined to the final error indices R$_1$ = 0.134 and R$_2$ (weighted) = 0.147, using 168 independent reflections for which $I_0 >3{\sigma}(I_0)$.

• Elastomers and Composites
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• v.53 no.4
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• pp.213-219
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• 2018

The degradation mechanism and physical properties of an FKM O-ring were observed with thermal aging in this experiment. From X-ray photoelectron spectroscopy (XPS) analysis, we could observe carbon (285 eV), fluoro (688 eV), and oxygen (531 eV) peaks. Before thermal aging, the concentration of fluoro atoms was 51.23%, which decreased to 8.29% after thermal aging. The concentration of oxygen atoms increased from 3.16% to 20.39%. Under thermal aging, the FKM O-ring exhibited debonding of the fluoro-bond by oxidation. Analysis of the C1s, O1s, and F1s peaks revealed that the degradation reaction usually occurred at the C-F, C-F2, and C-F3 bonds, and generated a carboxyl group (-COOH) by oxidation. Due to the debonding reaction and decreasing mobility, the glass transition temperature of the FKM O-ring increased from $-15.91^{\circ}C$ to $-13.79^{\circ}C$. From the intermittent CSR test, the initial sealing force was 2,149.6 N, which decreased to 1,156.2 N after thermal aging. Thus, under thermal aging, the sealing force decreased to 46.2%, compared with its initial state. This phenomenon was caused by the debonding reaction and decreasing mobility of the FKM O-ring. The S-S curve exhibited a 50% increase in modulus, with break at a low strain and stress state. This was also attributed to the decreasing mobility due to thermal aging degradation.

• Bulletin of the Korean Chemical Society
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• v.6 no.4
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• pp.202-206
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• 1985

The crystal structure of The crystal structure of $Ag^+$-Exchanged Zeolite A, $Ag_{4.6}Na_{7.4}-A$, dehydrated, treated with $H_2$, and evacuated, all at $350^{\circ}C$, has been determined by single crystal x-ray diffraction methods in the cubic space group Pm3m at $24(1)^{\circ}C;$ a = $12.208(2)\AA.$ The structure was refined to the final error indices R1 = 0.088 and R2 (weighted) = 0.069 using 194 independent reflections for which II_0$ > $3{\sigma}(I_0)$. On threefold axes near the centers of 6-oxygen rings, $7.4 Na^+$ ions and $0.6 Ag^+$ ions are found. Two non-equivalent 8-ring $Ag^+$ ions are found off the 8-ring planes, each containing about $0.6 Ag^+$ ions. Three non-equivalent Ag atom positions are found in the large cavity, each containing about 0.6 Ag atoms. This crystallographic analysis may be interpreted to indicate that $0.6 (Ag_6)^{3+}$ clusters are present in each large cavity. This cluster may be viewed as a nearly linear trisilver molecule $(Ag_3)^0$ (bond lengths, 2.92 and 2.94 $\AA;$ angle, $153^{\circ})$ stabilized by the coordination of each atom to a Ag^+$ ion at 3.30, 3.33, and 3.43 $\AA$, respectively. In addition, one of the silver atoms approaches all of the 0(1) oxygens of a 4-ring at $2.76\AA.$ Altogether $7.4 Na^+$ ions, $1.8 Ag^+$ ions, and 1.8 Ag atoms are located per unit cell. The remaining $1.0 Ag^+$ ion has been reduced and has migrated out of the zeolite framework to form silver crystallites on the surface of the zeolite single crystal.