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Duk-Young Jung

Publications and source records attributed to Duk-Young Jung.

9 recordsLinked to original sources
PubMed2006

Close-packed hemispherical microlens array from two-dimensional ordered polymeric microspheres.

This paper describes a facile, reproducible soft-lithography-based method for fabricating hexagonally close-packed microlens arrays by templating the surface of a colloidal monolayer, which is formed by spin-casting monodisperse polystyrene microspheres. The relief structure of colloidal monolayers has successfully generated PDMS elastomers with hexagonal arrays of hemispherical air voids. Closely packed hemispherical microlens arrays were imprinted on ultraviolet-curable photopolymers which are bound on glass substrates. Atomic force microscopy measurements showed that each spherical hole of the PDMS molds is 103 nm deep and the replicated microlens is 95 nm in height with narrow size distribution and good reproducibility. Without a multistep engineering process, this method might provide a reliable route to fabricate embossed thin layers ranging from nanometer to micrometers by controlling the size of polymer microspheres over a centimeter scale area.

Journal Article↗
PubMed2006

Treatment of open tibial shaft fractures using tightly fitted interlocking nailing.

Between 2000 and 2003 we treated 23 patients who sustained open tibial shaft fractures with tightly fitted interlocking intramedullary nailing. There were three grade I, eight grade II, nine grade IIIa, and three grade IIIb open fractures. Nail diameters were decided on using preoperative and intraoperative radiographs. Nails were introduced after gentle passage with a 7- to 8-mm hand reamer. Union was obtained in all cases. Nine (37.5%) fractures, however, required additional procedures before union. Three of them gained union through exchange nailing, bone graft, and bone transport, respectively. The remaining six underwent dynamisation. Two of them required an additional exchange nailing for non-union; thereafter one healed and the other gained union through an additional bone graft. Deep infection occurred in one case. Screw breakage occurred in one case only. Tightly fitted nailing produced a significantly lower incidence of locking screw breakage. However, even with this advantage, this technical modification has failed to show clinical advantage in terms of higher healing rate or lower rate of secondary procedures.

Adolescent↗
PubMed2005

Two-dimensional carboxylate bridged network of europium(III)-transition metal(II) glutarate compounds.

Four new heterometallic glutarate coordination polymers, [Eu2M(H2O)4][O2C(CH2)3CO2]4.2H2O (M = Mn (1), Fe (2), Co (3) and Ni (4)) have been obtained under hydrothermal synthesis. The single-crystal X-ray diffraction analyses showed that they have two-dimensional frameworks based on the linear polyhedral chains consisting of two nine-coordinated Eu(III)O9 and a six-coordinated M(II)O6. These 1-D MO6-Eu2O16 chains are cross-linked by glutarate ligands as an interchain pillared architecture, whose conformations vary depending upon the transition metals. The magnetic behavior of the compounds show a weak antiferromagnetic interaction, in which shielding of the 4f electrons by the outer shell electrons effectively precludes significant coupling interactions between the Eu-4f electrons and transition metal (M)-3d electrons.

Carboxylic Acids↗
PubMed2004

Hybrid external fixation of distal tibial fractures: new strategy to place pins and wires without penetrating the anterior compartment.

INTRODUCTION: Impalement of the anterior compartment musculature remains a problem in the hybrid external fixation of distal tibial fractures. The purposes of this study were to develop a tensioned wire configuration which does not violate the anterior compartment and to analyze the biomechanical implications of new wire configuration. MATERIALS AND METHODS: Thirty-seven adult volunteers without known pathology around either tibia were recruited. Axial computed tomography of the distal tibia was performed at 5-mm slices from the plafond to the upper margin of the syndesmosis. The wire convergence angle was measured at the 1-, 2-, and 2.5-cm levels using the following landmarks: tibialis anterior tendon (TA), tibialis posterior tendon (TP), peroneus brevis tendon (PB), anterolateral border of the lateral malleolus (LM). Two straight lines were drawn by connecting TA and PB and connecting TP and LM. The wire convergence angle was defined as an acute angle between these two lines. Then the orientation of the bisector axis of the wires was measured. As a second part of this study, a validated three-dimensional hybrid external fixator model was developed using finite elements modeling to analyze the stiffness of the frames constructed according to the measured wire convergence angle and orientation. Five simulated configurations were tested. The stiffness of each frame was analyzed under four load conditions: torsion, axial compression, side bending, and anteroposterior bending. RESULTS: The mean convergence angle was 30 degrees irrespective of the level. The bisector axis was oriented towards the anterolateral direction about 20 degrees from the coronal plane. The stiffness of the frame constructed with a wire convergence angle of 30 degrees and an anterolateral wire orientation of 20 degrees was 20-30% less than that of the frame constructed with 60 degrees wires oriented in a coronal plane. The addition of an anteromedial half-pin increased the stiffness significantly. CONCLUSIONS: Two tensioned wires may be placed without violating the anterior compartment by using the above four clinically identifiable landmarks. Addition of a half-pin on the anteromedial surface of the distal articular fragment makes the frame markedly stiffer than is possible using the standard wire configuration.

Adult↗
PubMed2004

Crystal structure and spectroscopic study of novel two- and three-dimensional photoluminescent Eu(III)-adipate compounds.

Two new photoluminescent compounds with the formulas of [Eu(2)(adipate)(3)(H(2)O)].H(2)O (1) and [Eu(2)(adipate)(3)(4H(2)O)] (2) were synthesized by using Eu(III) chloride and adipic acid under hydrothermal reaction conditions in aqueous solution. Compound 1, a 3-D layered framework, possesses infinite Eu-O-Eu polyhedral chains and self-assembled adipate ligands between Eu-O layers. Compound 2 has dimeric Eu(2)O(16) units interconnected by adipate ligand, resulting in 2-D open frameworks with a cavity among the ligands. Crystal data 1: monoclinic space group C2/c, with a = 14.2486(12) A, b = 8.2733(7) A, c = 39.298(2) A, beta = 99.530(6) degrees, and Z = 8. 2: monoclinic space group P2(1)/c, with a = 11.661(4) A, b = 14.011(3) A, c = 9.013(4) A, beta = 110.87(3) degrees, and Z = 2. The ligand conformations of two Eu(III)-adipate (1 and 2) compounds present anti/anti/anti, gauche/anti/gauche, and intermediate forms. Both compounds 1 and 2 showed strong red luminescence upon excitation, and their luminescence decay involves the multiphonon relaxation mechanism.

Journal Article↗
PubMed2002

A coordination polymer of cobalt(II)-glutarate: two-dimensional interlocking structure by dicarboxylate ligands with two different conformations.

A novel Co-glutarate, Co[O(2)C(CH(2))(3)CO(2)] (1), was synthesized as single crystals by the hydrothermal reaction of CoCl(2) with glutaric acid in the presence of KOH and characterized by single-crystal X-ray diffraction analysis, TGA, IR, UV-vis reflectance spectrometry, and SQUID measurements. The dark purple Co-glutarate crystallizes in the monoclinic system in the space group P2/c, with a = 14.002(3) A, b = 4.8064(10) A, c = 9.274(3) A, beta = 90.5(2)degrees, and Z = 4. The Co(2+) centers are tetrahedrally coordinated to four oxygen atoms from the dicarboxylate ligands. The anhydrous-pillared three-dimensional structure consists of infinite Co-CO(2)-Co inorganic layers, which are stacked by the coordinated glutarate alkyl chain along the a-axis. There are two different conformations for glutarate ligands, i.e., the gauche- and the anti-forms. These ligands reside between the inorganic layers alternatively to separate each layer by 7.01 A (gauche) and 6.99 A (anti). Magnetic measurement reveals that the predominant magnetic interactions are antiferromagnetic below 14 K.

Journal Article↗
PubMed2002

Quantitative analyses of shape-selective intercalation of isomeric mixtures of muconates into [LiAl2(OH)6]Cl.yH2O layered double hydroxide.

Quantitative investigation of the shape selectivity for the competitive intercalation reaction of isomeric mixtures in the interlayer of LDH was achieved by analyzing the solid phases synthesized by the reaction of [LiAl(2)(OH)(6)]Cl.yH(2)O with various compositional mixtures of (E,E)- and (Z,Z)-muconates. The apparent partition constant K' for the anion-exchange reaction between (E,E)- and (Z,Z)-muconates was quite dependent on the mole fraction of muconates in solution. The only single phase saturated with [LiAl(2)(OH)(6)](2)[(E,E)-C(6)H(4)O(4)].zH(2)O could be obtained in the range of the initial mole fraction of (E,E)-muconate larger than 0.6 in the starting solution, while mixed phases intercalated with (E,E)- and (Z,Z)-muconates could be obtained at lower mole fractions of (E,E)-muconate. The shape selectivity for the competitive reaction of two muconates on the [LiAl(2)(OH)(6)](+) lattice could be ascribed to thermodynamic processes, and the conditions under which that pure (E,E)-muconate was efficiently separated from isomeric mixtures of two muconates were successfully evaluated.

Journal Article↗