• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.41-48
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• 2007

Large colorless single crystals of sodium zeolite X, stoichiometry |Na80 |[Si112Al80O384]-FAU, with diameters up to 200 μm and Si/Al = 1.41 have been synthesized from gels with the composition of 2.40SiO2 : 2.00NaAlO2 : 7.52NaOH : 454H2O : 5.00TEA. One of these, a colorless octahedron about 200 μm in cross-section has been treated with aqueous 0.1 M KNO3 for the preparation of K+-exchanged zeolite X. The crystal structure of |K80|[Si112Al80O384]-FAU per unit cell, a = 24.838(4) A, dehydrated at 673 K and 1 × 10-6 Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd at 294 K. The structure was refined using all intensities to the final error indices (using only the 707 reflections for which Fo > 4σ (Fo)) R1 = 0.075 (based on F) and R2 = 0.236 (based on F2). About 80 K+ ions per unit cell are found at an unusually large number of crystallographically distinct positions, eight. Eleven K+ ions are at the centers of double 6-rings (D6Rs, site I; K-O = 2.492(6) A and O-K-O (octahedral) = 88.45(22)o and 91.55(22)o). Site-I' position (in the sodalite cavities opposite D6Rs) is occupied by five K+ ions per unit cell; these K+ ions are recessed 1.92 A into the sodalite cavities from their 3-oxygen planes (K-O = 2.820(19) A, and O-K-O = 78.6(6)o). Twety-three K+ ions are found at three nonequivalent site II (in the supercage) with occupancies of 5, 9, and 9 ions; these K+ ions are recessed 0.43 A, 0.75 A, and 1.55 A, respectively, into the supercage from the three oxygens to which it is bound (K-O = 2.36(13) A, 2.45(13) A, and 2.710(13) A, O-K-O = 116.5(20)o, 110.1(17)o, and 90.4(6)o, respectively). The remaining sixteen, thirteen, and twelve K+ ions occupy three sites III' near triple 4-rings in the supercage (K-O = 2.64(3) A, 2.94(3) A, 2.73(5) A, 2.96(6) A, 3.06(4) A, and 3.08(3) A).

• YAKHAK HOEJI
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• v.55 no.4
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• pp.319-323
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• 2011

Curcumin, of which a critical characteristic is the capacity of crossing the blood-brain barrier, has been reported to induce the expression of neuroprotective heme oxygenase (HO)-1. The aim of this study is to compare HO-1-inducing capacity and neuroprotective activity of curcumin, its demethoxy (demethoxycurcumin, DMC; bis-demethoxycurcumin, BDMC) and hydrogenated derivatives (tetrahydrocurcumin, THC) in mouse hippocampal HT22 cells. Curcumin attenuated glutamate-induced cell death through HO-1 expression. DMC lacking a methoxy group on one of the aromatic rings possessed slightly lower activity in HO-1 expression and neuroprotection than curcumin. Similarly, BDMC, which lacks two methoxy groups on both of the aromatic rings, showed less activity than curcumin. These findings suggest that the presence of methoxy groups on the aromatic ring is required to enhance neuroprotective HO-1 expression. The reduction of the diarylheptadienone chain of curcumin by hydrogen, as in THC, was accompanied by a complete loss of ability to induce HO-1 expression and neuroprotection, suggesting that the conjugated double bonds of the central seven-carbon chain of curcumin may be essential for its ability to induce neuroprotective HO-1 expression. Our findings may provide useful information for further development of neuroprotective HO-1 inducers.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.543-550
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• 2009

The single-crystal structure of largely ammonium-exchanged zeolite Y dehydrated at room temperature (293 K) and 1 ${\times}\;10^{-6}$ Torr. has been determined using synchrotron X-radiation in the cubic space group $Fd\overline{3}m\;(a=24.9639(2)\AA)$ at 294 K. The structure was refined to the final error index $R_1$ = 0.0429 with 926 reflections where $F_o>4\sigma(F_o)$; the composition (best integers) was identified as |$(NH_4)_{60}Na_{11}$|[$Si_{121}Al_{71}O_{384}$]-FAU. The 11 $Na^{+}$ ions per unit cell were found at three different crystallographic sites and 60 ${NH_4}^{+}$ ions were distributed over three sites. The 3 $Na^{+}$ ions were located at site I, the center of the hexagonal prism ($Na-O\;=\;2.842(5)\;\AA\;and\;O-Na-O\;=\;85.98(12)^{\circ}$). The 4 $Na^{+}$ and 22 ${NH_4}^{+}$ ions were found at site I' in the sodalite cavity opposite the double 6-rings, respectively ($Na-O\;=\;2.53(13)\;\AA,\;O-Na-O\;=\;99.9(7)^{\circ},\;N-O\;=\;2.762(11)\;\AA,\;and\;O-N-O =\;89.1(5)^{\circ}$). About 4 $Na^{+}$ ions occupied site II ($(Na-O\;=\;2.40(4)\;\AA\;and\;O-Na-O\;=\;108.9(3)^{\circ}$) and 29 ${NH_4}^{+}$ ions occupy site II ($N-O\;=\;2.824(9)\;\AA\;and\;O-N-O\;=\;87.3(3)^{\circ}$) opposite to the single 6-rings in the supercage. The remaining 9 ${NH_4}^{+}$ ions were distributed over site III' ($N-O\;=\;2.55(3),\;2.725(13)\;\AA\;and\;O-N-O\;=\;94.1(13),\;62.16(15),\;155.7(14)^{\circ}$).

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.1023-1029
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• 2001

The positions of Kr atoms encapsulated in the molecular-dimensioned cavities of fully dehydrated zeolite A of unit-cell composition Cs3Na8HSi12Al12O48 (Cs3-A) have been determined. Cs3-A was exposed to 1025 atm of krypton gas at 400 $^{\circ}C$ for four days, followed by cooling at pressure to encapsulate Kr atoms. The resulting crystal structure of Cs3-A(6Kr) (a = $12.247(2)\AA$, R1 = 0.078, and R2 = 0.085) has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at $21(1)^{\circ}C$ and 1 atm. In the crystal structure of Cs3-A(6Kr), six Kr atoms per unit cell are distributed over three crystallographically distinct positions: each unit cell contains one Kr atom at Kr(1) on a threefold axis in the sodalite unit, three at Kr(2) opposite four-rings in the large cavity, and two at Kr(3) on threefold axes in the large cavity. Relatively strong interactions of Kr atoms at Kr(1) and Kr(3) with Na+ ions of six-rings are observed: Na-Kr(1) = 3.6(1) $\AA$ and Na-Kr(3) = $3.08(5)\AA.$ In each sodalite unit, one Kr atom at Kr(1) was displaced $0.74\AA$ from the center of the sodalite unit toward a Na+ ion, where it can be polarized by the electrostatic field of the zeolite, avoiding the center of the sodalite unit which by symmetry has no electrostatic field. In each large cavity, five Kr atoms were found, forming a trigonal-bipyramid arrangement with three Kr(2) atoms at equatorial positions and two Kr(3) atoms at axial positions. With various reasonable distances and angles, the existence of Kr5 cluster was proposed (Kr(2)-Kr(3) = $4.78(6)\AA$ and Kr(2)-Kr(2) = $5.94(7)\AA$, Kr(2)-Kr(3)-Kr(2) = 76.9(3), Kr(3)-Kr(2)-Kr(3) = 88(1), and Kr(2)-Kr(2)-Kr(2) = $60^{\circ}).$ These arrangements of the encapsulated Kr atoms in the large cavity are stabilized by alternating dipoles induced on Kr(2) by four-ring oxygens and Kr(3) by six-ring Na+ ions, respectively.

• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.603-610
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• 1993

The crystal structure of dehydrated $Ag_{5.6}K_{6.4}-A$, zeolite A ion-exchanged with $K^+\;and\;Ag^+$ as indicated and dehydrated at 360$^{\circ}$C, has been determined by single-crystal X-ray diffraction techniques. Also determined were the structures of the products of the reactions of this zeolite with 0.1 Torr of Cs vapor at 250$^{\circ}$C for 48 h and 72 h, and with 0.1 Torr of Rb vapor at 250$^{\circ}$C for 24 h. The structures were solved and refined in the cubic space group Pm3m at 21(l)$^{\circ}$C (a= 12.255(l) ${\AA}$ , 12.367(l) ${\AA}$, 12.350(l) ${\AA}$, and 12.263(l) ${\AA}$, respectively). Dehydrated $Ag_{5.6}K_{6.4}$-A was refined to the final error indices $R_1= 0.044\;and\;R_2=0.037$ with 202 reflections for which I>3${\sigma}$(I). The crystal structures of the reaction products were refined to $R_1=0.087\;and\;R_2= 0.089$ with 157 reflections, $R_1=0.080\;and\;R_2= 0.087$ with 161 reflections, and $R_1= 0.071\;and\;R_2=0.061$ with 88 reflections, respectively. In the structure of $Ag_{5.6}K_{6.4}-A,\;K^+$ ions block all 8-oxygen rings, and one reduced Ag atom is found per sodalite cavity. Also, ca. 4.6 $Ag^+ ions\;and\;3.4 K^+ ions$ are found at 6-ring sites in the large cavity. The crystal structures of the reaction products show that all $K^+$ and $Ag^+$ ions have been reduced, and that all K^+$ atoms have left the zeolite. Cs or Rb species are found at three different crystallographic sites: 3.0 $Cs^+\;or\;3.0Rb^+$ ions per unit cell occupy 8-ring centers, ca. 8.0 $Cs^+ ions\;or\;5.7 Rb^+$ ions, are found on threefold axes opposite 6-rings deep in the large cavity, and ca. 2.5 $Cs^+\;or\;2.3 Rb^+ ions are found on threefold axes in the sodalite unit. Also, 1 $Rb^+$ ion lies opposite a 4-ring. Silver atoms, corresponding to 75% or 40% occupancy of hexasilver clusters stabilized by coordination to $Cs^+\;or\;Rb^+$ ions, are found at the centers of the large cavities. In the crystal structures of dehydrated Ag_{5.6}K_{6.4}-A$ reacted with Cs vapor, excess Cs atoms are absorbed and these form (locally) cationic clusters such as $(Cs_4)3^+\;and\;(Cs_6)4^+$.

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.631-637
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• 1996

The structures of fully dehydrated Ca2+- and Rb+-exchanged zeolite X, Ca31Rb30Si100Al92O384(Ca31Rb30-X; a=25.009(1) Å) and Ca28Rb36Si100Al92O384(Ca28Rb36-X; a=24.977(1) Å), have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd&bar{3} at 21(1) ℃. Their structures were refined to the final error indices R1=0.048 and R2=0.041 with 236 reflections for Ca31Rb30-X, and R1=0.052 and R2=0.043 with 313 reflections for Ca28Rb36-X; I>3σ(I). In both structures, Ca2+ and Rb+ ions are located at six different crystallographic sites. In dehydrated Ca31Rb30-X, sixteen Ca2+ ions fill site I, at the centers of the double 6-rings (Ca-O=2.43(1) Å and O-Ca-O=93.3(3)°). Another fifteen Ca2+ ions occupy site II (Ca-O=2.29(1) Å, O-Ca-O=119.5(5)°) and fifteen Rb+ ions occupy site II opposite single six-rings in the supercage; each is 1.60 Å from the plane of three oxygens (Rb-O=2.77(1) Å and O-Rb-O=91.1(4)°). About two Rb+ ions are found at site II', 1.99 Å into sodalite cavity from their three-oxygen plane (Rb-O=2.99(1) Å and O-Rb-O=82.8(4)°). The remaining thirteen Rb+ ions are statistically distributed over site III, a 48-fold equipoint in the supercages on twofold axes (Rb-O=3.05(1) Å and Rb-O=3.38(1) Å). In dehydrated Ca28Rb36-X, sixteen Ca2+ ions fill site I (Ca-O=2.41(1) Å and O-Ca-O=93.6(3)°) and twelve Ca2+ ions occupy site II (Ca-O=2.31(1) Å, O-Ca-O=119.7(4)°). Sixteen Rb+ ions occupy site II; each is 1.60 Å from the plane of three oxygens (Rb-O=2.81(1) Å and O-Rb-O=90.6(3)°) and four Rb+ ions occupy site II'; each is 1.88 Å into sodalite cavity from their three-oxygen plane (Rb-O=2.99(1) Å and O-Rb-O=83.8(2)°). The remaining sixteen Rb+ ions are found at III site in the supercage (Rb-O=2.97(1) Å and Rb-O=3.39(1) Å). It appears that Ca2+ ions prefer sites I and II in that order, and that Rb+ ions occupy the remaining sites. Rb+ ions are too large to be stable at site I, when they are competing with other smaller cations like Ca2+ ions.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.243-247
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• 1989

Two crystal structures of dehydrated $Ag^+\;and\;Ca^{2+}$ exchanged zeolite A, $Ag_2Ca_$5-A, reacting with 0.01 Torr of Cs vapor at $200^{\circ}C$ for 2 hours and 0.1 Torr of Cs vapor at $250^{\circ}C$ for 48 hours, respectively, have been determined by single crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at $21(1)^{\circ}C$. The stoichiometry of first crystal was $Ag_2Ca_5$-A (a = 12.294(1)${\AA}$), indicating that Cs vapor did not react with cations in zeolite A and that of second crystal was $Ag_2Cs_{10}$-A (a = 12.166(1)${\AA}$), indicating that all $Ca^{2+}$ ions were reduced by Cs vapor and replaced by $Cs^+$ ions. Full-matrix least-squares refinements of $Ag_2Ca_5-A\;and\;Ag_2Cs_{10}$-A has converged to the final error indices, $R_1\;=\;0.041\;and\;R_2$ = 0.048 with 227 reflections, and $R_1\;=\;0.117\;an\;n\;fdd\;R_2$ = 0.120 with 167 reflections, respectively, for which I > $3{\sigma}$(I). In the structure of $Ag_2Ca_5$-A, both $Ag^+$ ions and $Ca^{2+}$ ions lie on two crystal symmetrically independent threefold axis sites on the 6-rings; $2\;Ag^+$ ions are recessed 0.33 ${\;AA}$ from the (111) planes of three O(3) oxygens and 5 $Ca^{2+}$ ions lie on the nearly center of each 6-oxygen planes. In the structure of $Ag_2Cs_{10}-A,\;Cs^+$ ions lie on the 5 different crystallographic sites. 3 $Cs^+$ ions lie at the centers of the 8-rings at sites of D4h symmetry. 6 $Cs^+$ ions lie on the threefold axes of unit cell: $4\;Cs^+$ ions are found deep in the large cavity and 2 $Cs^+$ ions are found in the sodalite cavity. One $Cs^+$ ion is found in the large cavity near a 4-ring.

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.166-172
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• 2000

Growth of Ammodytes personatus was investigated based on the specimens collected in the costal waters of Shinsudo, Sacheon from March 20 to December 14, 1988. Age determination based on otolith. The rings in the otolith were used as the basis for age annulus. The time of ring formation was estimated to one time per year in May far 1st ring group and March for 2nd ring group. The spawning season peaked in December. It takes approximately 16 months for the first ring and 11 months for the second ring to form in the otolith. The opaque zone was formed and marked over summer at 1st ring group and spawning mark at 2nd ring group. The relationship between the total length(TL) and otolith radius(R), and body weight(BW) were represented respectively as follows: TL=29.17+182.9R, BW=$4.9{\times}10^{-8}TL^{3.9587}$. Von Bertalanffy growth model is $TL_t$ = 177.273 ($1_e^{-0.040(t+7.332)}$), Robertson growth model is $TL_t=\frac{150.275}{1+2.085e^{-0.099t}}$ and Gompertz growth model is $TL_t=157.551e^{-1.214exp(-0.069t)}$.

• Journal of Chest Surgery
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• v.34 no.7
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• pp.515-523
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• 2001

Background: More than 70% of morbidity and mortality of diabetes mellitus is due to macrovascular complications. These complications may be associated with defect of endothelium-dependent vascular relaxation. There have been suggestions that this defect might be due to direct toxicities of oxygen-free radical. So in this study ascorbic acid was used as a dietary supplement in streptozotocin induced diabetic rats to correct this defect. Material and Method: Sixty male Sprague-Dawley rats were used in this study. They were divided into control and experimental groups. Streptozotocin was injected to the 33 rats of experimental group and then divided into two the other receiving subgroups; one receiving ascorbic acid supplement(1 g/l in drinking water); and nosupplements. At 6, 9 and 12 weeks, abdominal aortic rings were obtained to make tissue preparations for evaluation of vascular smooth muscle contractility. Result: While control group showed good response to acetylcholine induced relaxation, diabetic group showed decreased relaxation regardless of ascorbic acid supplement at the experiments 6 weeks after streptozotocin treatment. This abnormal endothelium-dependent vascular relaxation was markedly reversed at 9 and 12 weeks into the diabetic group with ascorbic acid supplement. There were no differences in sodium nitroprusside induced relaxation responses between control and experimental groups; also, norepinephrine induced contractile responses did not show any remarkable effects. Conclusion: These results strongly suggest that the endothelial cells have defects in diabetic rats. Dietary supplement of ascorbic acid can reverse the defects of diabetic endothelial cells through its antioxidant effects and it may further protect against vascular disease in diabetic patients.

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.186-196
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• 1994

Three fully dehydrated partially $Ag^+$-exchanged zeolite A(Ag_4Na_8-A, Ag_6Na_6-A, and Ag_8Na_4-A) were treated at $250^{\circ}C$ with 0.1 torr Rb vapor at 4 h. Their structures were determined by singlecrystal X-ray diffraction methods in the cubic space group $Pm{\bar3}m$ (a = 12.264(4) $\AA$, a = 12.269(1) $\AA$, and a= 12.332(3) $\AA$, respectively) at $22(1)^{\circ}C$, and were refined to the final error indices, R(weighed), of 0.056 with 131 reflections, 0.068 with 108 reflections, and 0.070 with 94 reflections, respectively, for which I > $3\sigma(I).$ In these structures, Rb species are found at three different crystallographic sites; three $Rb^+$ ions per unit cell are located at 8-ring centers, ca. 6.0∼6.8 $Rb^+$ ions are found opposite 6-rings on threefold axes in the large cavity, and ca. 2.5 $Rb^+$ ions are found on three fold axes in the sodalite unit. Also, Ag species are found at two different crystallographic sites; ca. 0.6∼1.0 $Ag^+$ ion lies opposite 4-rings and about 1.8∼4.2 Ag atoms are located near the center of the large cavity. In these structures, the numbers of Ag atoms per unit cell are 1.8, 3.0, and 4.2, respectively, and these are likely to form hexasilver clusters at the centers of the large cavities. The $Rb^+$ ions, by blocking 8-rings, may have prevented silver atoms from migrating out of the structure. Each hexasilver cluster is stabilized by coordination to 6-ring, 8-ring $Rb^+$ ions, and also by coordination to a 4-ring $Ag^+$ ion.