• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.116-121
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• 1993

A single crystla of zeolite $Na_{78}Rb_{28}-X$ (approximate composition) was prepared by exposing $Na_{92}-X$ at $350^{\circ}C$ to 0.1 Torr of rubidium vapor, and its structure was determined by single-crystal x-ray diffraction methods in the cubic space group, Fd3, ${\alpha}=25.045(4){\AA}$. The structure was refined to the final error indices $R_1=0.082$ and $R_2=0.084$ with 353 for which I>$3{\sigma}(I)$. Only about 28 of the 92 $Na^+$ ions per unit cell were reduced and only about 14 of the 28 $Na^0$ atoms produced were retained within the zeolite. A $Na_5{^{4+}}$ cluster is present within each sodalite cavity. It is a centered tetrahedron (like $CH_4$) with bond $length=2.80(2){\AA}$ and angle tetrahedral by symmetry, and shows the full symmetry of its site. $T_d$, at the center of the sodalite cavity. Each of the four terminal atoms of the $Na_5{^{4+}}$ cluster bond to three framework oxygens at $2.36(2){\AA}$. At the centers of some double 6-rings are sodium atoms which bridge linearly between $Na_5{^{4+}}$ clusters to form agglomerations such as short zig-zag chains $Na_5{^{4+}}$ clusters. Delocalized electrons, located primarily on the sodiums at centers of the sodalite and (likely) double-six-ring cavities, contribute to the stability of the clusters.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.630-635
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• 1991

The crystal structure of a bromine sorption complex of dehydrated fully $Ca^{2+}$-exchanged zeolite A (a = 12.211(2) ${\AA}$) has been determined by single-crystal X-ray diffraction techniques in the cubic space group, Pm3m at $21(1)^{\circ}C$. The crystal was prepared by dehydration at $360^{\circ}C$ and 2 ${\times}$ $10^{-6}$ Torr for 2 days, followed by exposure to about 180 Torr of bromine vapor at $24^{\circ}C$ for 30 min. In the resulting structure, six $Ca^{2+}$ ions are located on two different threefold axes associated with 6-ring oxygens. A total of six dibromine molecules are sorbed per unit cell. Each $Br_2$ molecule approaches a framework oxide ion axially, with O-Br = 3.12(7) ${\AA}$, Br-Br = 2.64(9) ${\AA}$ and O-Br-Br = $178(2)^{\circ}$, indicating a charge-transfer interaction. Full-matrix least-squares refinement converged to a conventional R index of 0.104 using the 103 independent reflections for which I > 3${\sigma}$ (I).

• Animal Bioscience
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• v.35 no.2
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• pp.260-271
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• 2022

Objective: We aimed to investigate the effect of the differing amino acid (AA) release dynamics of two protein sources on the growth performance, nitrogen deposition, plasma biochemical parameters, and muscle synthesis and degradation of piglets when included in their diets at normal and low concentrations. Methods: Forty-eight piglets (Duroc×Landrace×Large White) with initial body weight of 7.45±0.58 kg were assigned to six groups and fed one of 6 diets. The 6 dietary treatments were arranged by 3×2 factorial with 3 protein sources and 2 dietary protein levels. They are NCAS (a normal protein content with casein), NBlend (a normal protein content with blend of casein and corn gluten meal), NCGM (a normal protein content with corn gluten meal), LCAS (a low protein content with casein), LBlend (a low protein content with blend of casein and corn gluten meal), LCGM (a low protein content with corn gluten meal). The release dynamics of AA in these diets were determined by in vitro digestion. The digestibility, utilization and biological value of nitrogen in piglets were determined by micro Kjeldahl method. Plasma insulin was measured by enzyme-linked immunosorbent assay kits. The protein expression of mediators of muscle synthesis and degradation was determined by western blotting. Results: Although the consumption of a low-protein diet supplemented with crystalline AA was associated with greater nitrogen digestion and utilization (p<0.05), the final body weight, growth performance, nitrogen deposition, and phosphorylation of ribosomal protein S6 kinase 1 and eIF4E binding protein 1 in the muscle of pigs in the low-protein diet-fed groups were lower than those of the normal-protein diet-fed groups (p<0.05) because of the absence of non-essential AA. Because of the more balanced release of AA, the casein (CAS) and Blend-fed groups showed superior growth performance, final body weight and nitrogen deposition, and lower expression of muscle ring finger 1 and muscle atrophy F-box than the CGM-fed groups (p<0.05). Conclusion: We conclude that the balanced release of AA from CAS containing diets and mixed diets could reduce muscle degradation, favor nitrogen retention, % intake and improve growth performance in pigs consuming either a normal- or low-protein diet.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.9
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• pp.423-430
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• 2002

The fabrication and experimentation of multi-channel electrodes which enable detecting and recording of multi-site neuronal signals have been investigated. A multi-channel electrode array was fabricated by depositing 2000${\AA}$ thick Au layer on the 1000${\AA}$ thick Ti adhesion layer on a glass wafer. The metal paths were patterned by wet etching and passivated by depositing a PECVD silicon nitride insulation layer to prevent signals from intermixing or cross-talking. After placing a thin slice of rat cerebellar granule cell in the culture ring located in central portion of the multi-channel electrode plate, a neuronal signal from an electrode which is in contact with the cerebellar granule cell has been detected. It was found that the electrode impedance ranges 200㏀∼1㏁ and the impedance is not changed by cleaning with nitric acid. Also, the impedance is inversely proportion to the exposed electrode area and the cross-talk is negligible when the electrode spacing is bigger than 600$\mu\textrm{m}$. The amplitude and frequency of the measured action potential were 38㎷ and 2㎑, which are typical values. From the experimental results, the fabricated multi-channel electrode array proved to be suitable for multi-site neuronal signal detection for the analysis of a complicated cell network.

• Archives of Pharmacal Research
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• v.3 no.1
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• pp.37-49
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• 1980

Chlorpropamide, $C_{10}H_{13}N_{2}O_{3}SCI$, forms orthofombic crystals of space group $P_{2}_{ 1}2_{1}2_{1}$ with a 9.066 $\pm$ 0.004, b = 5.218 $\pm$ 0.003, c = 26, 604 $\pm$, 0.008 $\AA$, and four molecules per cell. Three dimensional photographic data were collected with Mo-K$\alpha$ radiation. The structure was determined using Patterson, Fourier and Difference syntheses methods and refined by the block-diagonal least-squares methods with anisotropic thermal parameters for all nonhydrogen atoms and isotropic thermal parameters for all hydrogen atomes. The final R value was 0.10 for the 1823 observed independent reflections. The dihedral angle between the planes through the benzene ring and the urea goup is 99$^{\circ}$. The conformational angle formed by the projection of the S-C(1) with that of N(1)-C(7) when the projection is taken along the S-N(1) bond is 76$^{\circ}$. The molecule appears to form with neighbouring molecules two hydrogen bonds, N(1)..H...O(3) and N(2)-H...0(2) of lengths 2.774 and 2.954$\AA$ respectively related by screw diads parallel to the a axis. Adjacent molecules parallel to b and c axis are bound together by van der Wasls forces.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.143-148
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• 1991

In the unhydrated and hydrated states, conformational free energies of L-ascorbic acid anion (AAA) were computed with an empirical potential function and the hydration shell model (a program CONBIO). The conformational energy was minimized from possible starting conformations expressed with five torsion angles of the molecule. The conformational entropy of each low energy conformation in both states was computed using a harmonic approximation. As found in L-ascorbic acid (AA), intramolecular hydrogen bonds (HBs) are proved to be of significant importance in stabilizing the overall conformations of AAA in both states, and give the folded conformations, which are quite different from those in crystal. There are competitions between HBs and hydration around O3 atom of the lactone ring and hydroxyls of the acyclic side chain. Especially, the whole conformation of AAA is strongly dependent on the water-accessibility of O3 atom. Though there is a significant effect of the hydration on conformational surface, the lowest energy conformation of the unhydrated AAA is conserved. The different patterns of HBs and hydration result in the conformations of AAA in both states being different from those of AA. It can be drawn by several feasible conformations obtained in the hydrated state that there exists an ensemble of several conformations in aqueous solution.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.258-262
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• 1993

Two single crystals of fully dehydrated $Rb^+$ -exchanged zeolite A have been prepared by the reduction of all $Ca^{2+}$ ions in dehydrated $Ca_6$-A by rubidium vapor. Their structures were determined by single crystal X-ray diffraction methods in the cubic space group Pm3m (a=12.160(2) $^{\AA}$ and 12.166(2) $^{\AA}$) at 22(1)$^{\circ}$C. In these structures, 12.4(2) to 13.3(2) Rb species are found per unit cell, more than 12 Rb$^+$ ions needed to balance the anionic charge of the zeolite framework, indicating that the sorption $Rb^0$ has occurred. In each structure, three $Rb^+$ ions per unit cell are located at the centers of the 8-rings. Six to eight $Rb^+$ ions are found opposite the 6-rings on threefold axes, and three $Rb^+$ ions are found in a sodalite unit. About 0.5 $Rb^+$ ion lies opposite a 4-ring. The structural analysis indicates the presence of a triangular rubidium cluster in the sodalite cavities. The triangular rubidium clusters may be stabilized by the coordination to two and/or three rubidium ions in the large cavity. Therefore, this cluster may be viewed as $(Rb_5)^{4+}$ and/or $(Rb_6)^{4+}$.

• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.303-308
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• 1988

Four crystal structures of dehydrated Ag(I) and Tl(I) exchanged zeolite A, $Ag_{12-x}Tl_x$-A, x = 2, 3, 4, and 5, have been determined by single-crystal x-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at $21(1)^{\circ}C$. All crystals were ion exchanged in flowing streams of mixed $AgNO_3\;and\;TlNO_3$ aqueous solution, followed by dehydration at $350^{\circ}C$ and $2{\times}10^{-6}$ Torr for 2 days. In all of these structures, one-sixth of the sodalite units contain octahedral hexasilver clusters at their centers and eight $Ag^+$ ions are found on threefold axes, each nearly at the center of a 6-oxygen ring. The hexasilver cluster is stabilized by coordination to eight $Ag^+$ ions. The Ag-Ag distance in the cluster, ca. 2.92 ${\AA}$, is near the 2.89 ${\AA}$ bond length in silver metal. The remaining five-sixths of the sodalite units are empty of silver species. The first three $Tl^+$ ions per unit cell preferentially associate with 8-oxygen rings, and additional $Tl^+$ ions, if present, are found on threefold axes in the large cavity.

• Bulletin of the Korean Chemical Society
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• v.21 no.1
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• pp.75-80
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• 2000

The positions of Xe atoms encapsulated in the molecular-dimensioned cavities of fully dehydrated Na-A have been determined. Na-A was exposed to 1050atm of xenon gas at 400 $^{\circ}C$ for seven days, followed by cooling at pressure to encapsulate Xe atoms. The resulting crystal structure of Na-A(7Xe) (a = 12.249(1) $\AA$, $R_1$ = 0.065, and $R_2$ = 0.066) were 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 Na-A(7Xe), seven Xe atoms per unit cell are distributed over four crystallographically distinct positions: one Xe atom at Xe(1) lies at the center of the sodalite unit, two Xe atoms at Xe(4) are found opposite four-rings in the large cavity, and four Xe atoms, two at Xe(2) and others at Xe(3), respectively, occupy positions opposite and between eight- and six-rings in the large cavity. Relatively strong interactions of Xe atoms at Xe(2) and Xe(3) with $Na^+$ ions of four-, eight-, and six-rings are observed:Na(1)-Xe(2) = 3.09(6), Na(2)-Xe(3) = 3.11(2), and Na(3)-Xe(2) = 3.37(8) $\AA$. In each sodalite unit, one Xe atom is located at its center. In each large cavity, six Xe atoms are found, forming a distorted octahedral arrangement with four Xe atoms, at equatorial positions (each two at Xe(2) and Xe(3)) and the other two at axial positions (at Xe(4)). With various reasonable distances and angles, the existence of $(Xe)_6$ cluster is proposed (Xe(2)-Xe(3) = 4.78(6) and 4.94(7), Xe(2)-Xe(4) = 4.71(6) and 5.06(6), Xe(3)-Xe(4) = 4.11(3) and 5.32(4) $\AA$, Xe(2)-Xe(3)-Xe(2) = 93(1), Xe(3)-Xe(2)-Xe(3) = 87(1), Xe(2)-Xe(4)-Xe(2) = 91(4), Xe(2)-Xe(4)-Xe(3) = 55(2), 59(1), 61(1), and 68(1), and Xe(3)-Xe(4)-Xe(3) = 89($^{\circ}1$)). These arrangements of the encapsulated Xe atoms in the large cavity are stabilized by alternating dipoles induced on Xe(2), Xe(3), and Xe(4) by eight- and six-ring $Na^+$ ions as well as four-ring oxygens, respectively.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.30-36
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• 2001

The crystal structures of fully dehydrated $Pd^{2+}$ - and $TI^{+}$ -exchanged zeolite X, $Pd_{18}TI_{56}Si_{100}Al_{92}O_{384}(Pd_{18}TI_{50-}X$, a = $24.935(4)\AA$ and $Pd_{21}TI_{50}Si_{100}Al_{92}O_{384}(Pd_{21}TI_{50-}X$ a = $24.914(4)\AA)$, have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at $21(1)^{\circ}C.$ The crystals were prepared using an exchange solution that had a $Pd(NH_3)_4Cl_2\;:TINO_3$ mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05M for 4 days. After dehydration at $360^{\circ}C$ and 2 ${\times}$$10^{-6}$ Torr in flowing oxygen for 2 days, the crystals were evacuated at $21(1)^{\circ}C$ for 2 hours. They were refined to the final error indices $R_1$ = 0.045 and $R_2$ = 0.038 with 344 reflections for $Pd_{18}Tl_{56-}X$, and $R_1$ = 0.043 and $R_2$ = 0.045 with 280 reflections for $Pd_{21}Tl_{50-}X$; I > $3\sigma(I).$ In the structure of dehydrated $Pd_{18}Tl_{56-}X$, eighteen $Pd^{2+}$ ions and fourteen $TI^{+}$ ions are located at site I'. About twenty-seven $TI^{+}$ ions occupy site II recessed $1.74\AA$ into a supercage from the plane of three oxygens. The remaining fifteen $TI^{+}$ ions are distributed over two non-equivalent III' sites, with occupancies of 11 and 4, respectively. In the structure of $Pd_{21}Tl_{50-}X$, twenty $Pd^{2+}$ and ten $TI^{+}$ ions occupy site I', and one $Pd^{2+}$ ion is at site I. About twenty-three $TI^{+}$ ions occupy site II, and the remaining seventeen $TI^{+}$ ions are distributed over two different III' sites. $Pd^{2+}$ ions show a limit of exchange (ca. 39% and 46%), though their concentration of exchange was much higher than that of $TI^{+}$ ions. $Pd^{2+}$ ions tend to occupy site I', where they fit the double six-ring plane as nearly ideal trigonal planar. $TI^{+}$ ions fill the remaining I' sites, then occupy site II and two different III' sites. The two crystal structures show that approximately two and one-half I' sites per sodalite cage may be occupied by $Pd^{2+}$ ions. The remaining I' sites are occupied by $TI^{+}$ ions with Tl-O bond distance that is shorter than the sum of their ionic radii. The electrostatic repulsion between two large $TI^{+}$ ions and between $TI^{+}$ and $Pd^{2+}$ ions in the same $\beta-cage$ pushes each other to the charged six-ring planes. It causes the Tl-O bond to have some covalent character. However, $TI^{+}$ ions at site II form ionic bonds with three oxygens because the super-cage has the available space to obtain the reliable ionic bonds.