Seung Mook Jo

Korea Institute of Science and Technology, Sŏul, Seoul, South Korea

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Publications (34)93.52 Total impact

  • H. J. Chung · D. W. Lee · S. M. Jo · D. Y. Kim · W. S. Lee
    MRS Online Proceeding Library 01/2011; 837. DOI:10.1557/PROC-837-N3.15
  • S. H. Park · B. C. Kim · S. M. Jo · D. Y. Kim · W. S. Lee
    MRS Online Proceeding Library 01/2011; 837. DOI:10.1557/PROC-837-N3.14
  • S. W. Choi · Y.-Z. Fu · Y. R. Ahn · S. M. Jo · A. Manthiram
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    ABSTRACT: Composite membranes consisting of polyvinylidene fluoride (PVdF) and Nafion have been prepared by impregnating various amounts of Nafion (0.3–0.5g) into the pores of electrospun PVdF (5cm×5cm) and characterized by scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and proton conductivity measurements. The characterization data suggest that the unique three-dimensional network structure of the electrospun PVdF membrane with fully interconnected fibers is maintained in the composite membranes, offering adequate mechanical properties. Although the composite membranes exhibit lower proton conductivity than Nafion 115, the composite membrane with 0.4g Nafion exhibits better performance than Nafion 115 in direct methanol fuel cell (DMFC) due to smaller thickness and suppressed methanol crossover from the anode to the cathode through the membrane. With the composite membranes, the cell performance increases on going from 0.3 to 0.4g Nafion and then decreases on going to 0.5g Nafion due to the changes in proton conductivity.
    Journal of Power Sources 05/2008; 180(1):167-171. DOI:10.1016/j.jpowsour.2008.02.042 · 6.22 Impact Factor
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    ABSTRACT: Zinc enriched (ZEN) neurons and terminals are abundant in the rodent spinal cord. Zinc ions have been suggested to modulate the excitability of primary afferent fibers believed to be important in nociceptive transmission. To test the hypothesis that vesicular zinc concentration is related to neuropathic pain we applied Chung's rodent pain model on BALB/c mice, and traced zinc transporter 3 (ZnT3) proteins and zinc ions with immunohistochemistry and autometallography (AMG), respectively. Under anesthesia the left fifth lumbar spinal nerve was ligated in male mice in order to produced neuropathic pain. The animals were then sacrificed 5 days later. The ZnT3 immunoreactivity was found to have decreased significantly in dorsal horn of fourth, fifth, and sixth lumbar segments. In parallel with the depressed ZnT3 immunoreactivity the amount of vesicular zinc decreased perceptibly in superficial gray matters of especially layer I-IV of the same segments. The transection-induced reduction of vesicular zinc in ZEN terminals of the dorsal horn was synchronic to reduced pain threshold, as measured by von Frey method. In a separate study, we observed intensive zinc selenite precipitation in somata of the smaller spinal ganglion cell, but 5 days after spinal nerve transection zinc precipitation was also found in the lager ganglion cells. The present results indicate that zinc may be involved in pain mechanism in the spinal ganglion level. These results support the hypothesis that vesicular zinc might have a modulatory role for neuropathic pain. Thus, increased pain sensitivity might be related to reduce vesicular zinc level in the dorsal spinal gray matter.
    BioMetals 05/2008; 21(2):151-8. DOI:10.1007/s10534-007-9103-x · 2.69 Impact Factor
  • G. S. Chung · S. M. Jo · B. C. Kim
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    ABSTRACT: A solution of a polyimide (PI, Matrimid® 5218) in dimethylacetamide was electrospun, and carbonization of the electrospun nonwoven fabrics produced carbon nanofiber fabrics. The effects of iron(III) acetylacetonate (AAI) on carbonization and the resulting morphology were also investigated. The carbonization behavior of the nonwoven fabrics was examined by X-ray diffraction and Raman spectroscopy. AAI promoted carbonization of the nonwoven fabrics and increased the carbon yield. Addition of 3 wt % AAI increased the crystal dimension of electrospun PI nanofibers from 1.06 to 4.18 nm and decreased the integrated intensity ratio from 3.37 to 1.83 when heat treated at 1200°C. Scanning electron microscopy images of the carbonized nonwoven fabrics showed that AAI remained as particles within the fibers after carbonization. In addition, transmission electron microscopy observations revealed that turbostratic-oriented graphite layers were observed around the particles even at 1200°C, which have been reported only on carbonization of rigid-chain solvent insoluble PI materials under tension. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97:165–170, 2005
    Journal of Applied Polymer Science 07/2005; 97(1):165 - 170. DOI:10.1002/app.21742 · 1.64 Impact Factor
  • S.H. Park · S.M. Jo · D.Y. Kim · W.S. Lee · B.C. Kim
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    ABSTRACT: To investigate the effects of introducing the iron compound on the carbonization behavior polyacrylonitile (PAN)-based electrospun nanofibers were carbonized with or without iron(III) acetylacetonate (AAI) over the temperature range of 900–1500 °C in nitrogen atmosphere. The morphological characteristics of the carbon nanofibers were investigated using X-ray diffractometer (XRD), Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The electrical conductivity of the carbon nanofiber web was measured by four-point probe method. The iron catalyst had a profound effect on the crystal structure of the carbonized nanofiber. In the presence of AAI the nanofibers carbonized at 1300 °C developed graphite structure, which could be obtained at the temperature higher than 2000 °C in the absence of the catalyst. The in-plane size of the graphite crystals (La) was measured to be about 6.5 nm by Raman spectroscopy and the (0 0 2) spacing by XRD was 0.341 nm.
    Synthetic Metals 05/2005; 150(3):265-270. DOI:10.1016/j.synthmet.2005.02.010 · 2.22 Impact Factor
  • Sang Won Suh · Seung Mook Jo · Zsolt Vajda · Gorm Danscher
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    ABSTRACT: The effects of adrenalectomy (ADX) on the vesicular zinc content of zinc-enriched (ZEN) terminals in mouse hippocampus were investigated at light microscopic levels using zinc transporter-3 immunohistochemistry (ZnT3IHC) and zinc selenium autometallography (ZnSeAMG). ZnT3 resides in the synaptic vesicle membranes of ZEN neurons and is believed to move zinc ions into the vesicles. ZnT3IHC staining closely corresponds to the ZnSeAMG staining, but in the present study we present evidence of a delayed decrease of ZEN zinc, as compared to downregulation of the ZnT3 protein following ADX. Twenty-four hours after adrenalectomy the level of ZnT3IHC was visibly reduced while the ZnSeAMG staining intensity seemed unchanged. After 10 and 30 days, however, downregulation of ZnT3 was paralleled by a distinct reduction in ZnSeAMG staining. The total protein concentration of ZnT3 was reduced by about 53%, and the total zinc concentration in the hippocampus of the same mice was reduced by 43-64%, 30 days after the adrenalectomy. The present results support previous results suggesting that ZnT3 is responsible for transport of zinc ions into a pool of synaptic vesicles in ZEN terminals.
    Neuroscience Letters 05/2005; 377(3):164-9. DOI:10.1016/j.neulet.2004.11.096 · 2.06 Impact Factor
  • J. R. Kim · S. W. Choi · S. M. Jo · W. S. Lee · B. C. Kim
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    ABSTRACT: Microporous fibrous membranes were prepared from poly(vinylidenefluoride-co-hexafluoropropylene) P(VdF-HFP) solutions in an acetone/N,N-dimethylacetamide mixture using the electrospinning method. Varying the P(VdF-HFP) polymer concentration in electrospinning can easily control the pore size and the porosity of the electrospun fibrous membranes (ES-FMs). The usefulness of the ES-FMs as a matrix of polymer electrolyte for a lithium-ion polymer battery with high performance was evaluated. Electrospun fibrous polymer electrolyte membranes (ES-FPEMs) showed excellent electrochemical properties of ionic conductivity, higher than 1 x 10(-3) S/cm at room temperature, and the electrochemical stability window, up to 4.5 V vs. Li+/Li. At a C/2 rate, the prototype cell using the ES-FPEM showed a good charge/discharge property, with little capacity fade under constant current and constant voltage conditions at 20 and 60degreesC.
    Journal of The Electrochemical Society 01/2005; 152(2). DOI:10.1149/1.1839531 · 2.86 Impact Factor
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    S. W. Choi · J. R. Kim · S. M. Jo · W. S. Lee · YR Kim
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    ABSTRACT: Microporous fibrous polymer electrolytes were prepared by immersing electrospun poly(acrylonitrile) (PAN)-based fibrous membranes into lithium salt-based electrolytes. They showed high ionic conductivities of up to 1.0 x 10(-3) S/cm at 20 degrees C, and sufficient electrochemical stabilities of up to 4.5 V. Their ion conduction depended on the physicochemical properties of the lithium salt-based electrolytes trapped in pores, as well as on the interactions among the Li+ ion, the carbonate, and the PAN. From the Fourier transform-Raman data, lithium ion transport was mainly achieved by the lithium salt-based electrolytes in pores via the interaction between the Li+ ion and the C=O group of carbonate molecules, and was also affected by the PAN through the interaction between the Li+ ion and the C&3bond; N groups of PAN. Their electrochemical stabilities were enhanced by the swelling of the electrospun PAN nanofibers because of the dipolar interaction between the C; N groups of PAN and the C=O groups of carbonate in the lithium salt-based electrolytes. Prototype cells using electrospun PAN-based fibrous polymer electrolytes thus showed different cyclic performances, according to the composition of the lithium salt-based electrolytes. The prototype cell with 1 M LiPF6-ethylene carbonate/ dimethyl carbonate (1/1) showed the highest discharge capacity and the most stable cyclic performance among them. (c) 2005 The Electrochemical Society.
    Journal of The Electrochemical Society 01/2005; 152(5). DOI:10.1149/1.1887166 · 2.86 Impact Factor
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    ABSTRACT: We examined the presence of Zn-transporters (ZnT1, ZnT3, ZnT4, and ZnT6) proteins and zinc ions in rat choroid epithelium with immunohistochemistry and zinc selenide autometallography (ZnSe(AMG)). The four ZnT proteins were all expressed in the choroid epithelial cells. ZnT3 immunostaining was found in vesicle membranes in the apical part of the cells, associated to the microvillus membrane. Correspondingly, the ZnSe(AMG) technique revealed zinc ions in small vesicles, in microvilli, and multivesicular bodies in the epithelial cells. Traceable zinc ions were also found in lysosome-like organelles of fenestrated endothelial cells, but here no corresponding ZnT3 immunostaining was seen. The observations suggests that the choroid plexus is instrumental to regulation of the level of zinc ions in the cerebrospinal fluid.
    Neuroreport 09/2004; 15(11):1801-4. DOI:10.1097/01.wnr.0000132918.05366.81 · 1.64 Impact Factor
  • Article: P36-1
    Structure 01/2004; 36:2. · 6.79 Impact Factor
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    S.W. Choi · S.M. Jo · W.S. Lee · YR Kim
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    ABSTRACT: The electrospun nanofibrous membrane had high porosity, large surface area, fully interconnected pore structure, and sufficient mechanical strength. As such, a nanofibrous polymer electrolyte using this membrane showed excellent physical and electrochemical properties. Hence, the electrospun nanofibrous membrane is considered to be a good microporous polymer matrix of polymer electrolytes for high-performance lithium polymer batteries.
    Advanced Materials 12/2003; 15(23):2027 - 2032. DOI:10.1002/adma.200304617 · 17.49 Impact Factor
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    ABSTRACT: We report, for the first time, the light microscopical and ultrastructural appearance of ZnT3-immunoreactivities in the ependymal cells of the central canal of the mouse spinal cord. Light microscopy revealed the presence of ZnT3-immunoreactive (Ir) ependymal cells in 1 microm thick epon sections stained by the ABC method. The ZnT3-Ir cells were observed at all levels of the spinal cord, but were a little more numerous in lumbosacral segments than in cervicothoracic segments. The ZnT3-Ir cells had large, ovoid nuclei with abundant cytoplasm, and protruded into the lumen of the central canal. Our ultrastructural findings suggest that the ZnT3-Ir ependymal cells possess secretory activity directed towards the central canal. We propose that they may play a role in the trans-ependymal mechanism responsible for zinc homeostasis between cerebrospinal fluid and the central area of the gray matter.
    Neuroscience Letters 06/2003; 342(1-2):81-4. DOI:10.1016/S0304-3940(03)00253-2 · 2.06 Impact Factor
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    Seung Mook Jo · Yong Kuk Kim · Zhanyou Wang · Gorm Danscher
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    ABSTRACT: Zinc ions seem to be important to several neurological functions and have been connected to the pathophysiology of epilepsy, neuronal cell death after seizure or stroke, and Alzheimer's disease. Both epilepsy and Alzheimer's disease are clinical conditions believed to involve the olfactory bulb. The mammalian olfactory bulb is densely innervated by zinc-enriched (ZEN) neurons, and the distribution of the ZEN terminals in the mouse olfactory bulb has previously been described. The aim of this study was to describe the origins of ZEN terminals projecting into the main olfactory bulb of the rat. Selective labeling of ZEN terminals was accomplished by intracerebral infusion of sodium selenide, whereby zinc selenium clusters are created in the ZEN terminals. Some of these clusters move by retrograde axonal transport to the somata where they can be silver-enhanced by autometallography (AMG). After infusion of sodium selenide into the main olfactory bulb, retrogradely labeled ZEN somata were found (1) ipsilaterally in all anterior olfactory nuclei, taenia tecta, piriform cortex and lateral entorhinal cortex, and (2) contralaterally in anterior olfactory nuclei except the external division. The ipsilateral anterior olfactory nucleus had the densest population of ZEN somata, and it was found that these somata originated mainly from pyramidal neurons in layers II and III of each area. The olfactory-related centrifugal afferents to the main olfactory bulb are discussed.
    Brain Research 12/2002; 956(2):230-5. DOI:10.1016/S0006-8993(02)03544-8 · 2.83 Impact Factor
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    ABSTRACT: In the present study, we showed for the first time the presence of inhibitory zinc-enriched neuron terminals in the mouse cerebellar cortex by means of double-immunohistochemistry for zinc transporter 3 (ZnT3) and glutamate decarboxylase (GAD). The co-localization of ZnT3 and GAD in the cerebellar cortex was analyzed by confocal microscopy. Strong, punctuate ZnT3-immunoreactivity (Ir) was predominantly distributed in the granule cell layer, while GAD-Ir was seen throughout the cerebellar cortical layers. All of the ZnT3-immunoreactive structures were also immunopositive to GAD, but not vice versa. Based on size and position, these double-labeled elements were axonal terminals of the Golgi and basket cells, in the granule cell and molecular layers, respectively. Observations by electron microscopy revealed that ZnT3-immunoreactive terminals showed typical characteristics of the inhibitory synapses like the following: (1) presynaptic terminals containing flat vesicles; and (2) symmetrical synaptic contacts with dendritic elements. The present results indicate that a zinc-containing GABAergic system exists in the mouse cerebellar cortex.
    Neuroscience Letters 04/2002; 321(1-2):37-40. DOI:10.1016/S0304-3940(01)02560-5 · 2.06 Impact Factor
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    ABSTRACT: This article describes the physical properties of lyocell fibers spun from an isotropic cellulose spinning dope in N-methyl morpholine N-oxide (NMMO) monohydrate (IPS lyocell fibers). Wide angle x-ray diffraction (wAxD) experiments on the crimped fibers exhibit little difference in the crystal structure of IPS and Tencel lyocell fibers: both fibers reveal a cellulose II structure. However, the IPS lyocell fibers have a lower tensile modulus than Tencel by about 12.5%, although they have a similar tensile strength. Wetting and subsequent drying shift the loss tangent values higher, which is more remarkable for the IPS lyocell fibers dried under tension. Further, the IPS lyocell fibers dried under tension have a sharper α-transition peak than the fibers dried without tension. The IPS lyocell fibers exhibit excellent wet tensile strength: 90% of tensile strength is retained after wetting twice in distilled water. In addition, the IPS lyocell fibers show good chemical stability to acids and alkalis, except for an extremely strong alkali—pH 14. Mercerization of the IPS lyocell fibers in the buffer solution of pH 14 notably decreases the tensile modulus but increases elongation.
    Textile Research Journal 04/2002; 72(4):335-340. DOI:10.1177/004051750207200410 · 1.33 Impact Factor
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    ABSTRACT: It is well established that GABA degradation may play a key role in epileptogenesis. However, whether or not the expression of GABA-transaminase (GABA-T), which catalyzes GABA degradation and participates in the neuronal metabolism via GABA shunt, changes chronologically after on-set of seizure remains to be clarified. To identify the change of GABA-T expression in seizure, GABA-T expression in the gerbil hippocampus, associated with different sequelae of spontaneous seizures, was investigated. The distribution pattern of GABA-T immunoreactive neurons in the hippocampus between the seizure-resistant and pre-seizure group of seizure sensitive gerbils was similar. Interestingly, at 30 min postictal, the enhancement of GABA-T immunoreactivity in the perikarya was apparently observed. This contrasted with the decline in GABA-T immunoreactivity in the granular and pyramidal layer. At 12-24 h postictal, GABA-T immunoreactivity in the hilar neurons had declined significantly. However, the GABA-T immunoreactivity in the granular layer increased. These findings suggest that in the gerbil, the alteration in GABA-T expressions may play an important role in the self-recovery mechanism from seizure attack via both GABA degradation and regulation of neuronal metabolism.
    Neurochemistry International 07/2001; 38(7):609-14. DOI:10.1016/S0197-0186(01)00002-X · 2.65 Impact Factor
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    ABSTRACT: The zinc selenide autometallographic (ZnSeAMG) technique for tracing the retrograde axonal transport of zinc ions in zinc-enriched (ZEN) neurons was used to map the distribution of ZEN neuronal somata in rat spinal cord. After a local injection of sodium selenide into the dorsal or ventral horn, ZnSeAMG-labeled ZEN neurons appeared in Rexed’s laminae V, VII and X while laminae I and II were void. A few scattered ZEN somata were observed in the remaining laminae. The labeled neurons differed in shape and size, and the relatively high level of labeled somata around the injection site suggests that many ZEN neurons have relatively short axons or boutons en passage close to the neuronal origin. Ultrastructurally, the retrogradely transported zinc selenide clusters were found in the lysosomes of ZEN somata and proximal dendrites. Electron microscopic studies also revealed two different kinds of ZEN terminals: (1) terminals with flat synaptic vesicles making symmetric synaptic contacts; and (2) terminals with round vesicles making asymmetric synaptic contacts. The present study suggests the existence of propriospinal systems of ZEN neurons comprising both segmental and intersegmental ZEN connections and having either inhibitory or excitatory ZEN terminals. The ZEN neurons seem to form a vast network of terminals located primarily in the gray matter, but also contacting dendrites radiating into the white matter. Important functions of this rather massive system of ZEN terminals can not be deduced from our present knowledge, but the systems appear to be involved in both motor and sensory functions.
    Brain Research 06/2001; 900(1-900):80-87. DOI:10.1016/S0006-8993(01)02261-2 · 2.83 Impact Factor
  • T C Kang · J C Lee · K Y Choi · S K Park · Y G Jeong · S M Jo · M H Won
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    ABSTRACT: The distribution of serotonin immunoreactivity in the main olfactory bulb (MOB) of the Mongolian gerbil (Meriones unguiculatus) was examined by immunohistochemistry. Seven distinct layers of the Mongolian gerbil MOB-stained with cresyl violet were identified. Serotonin-immunoreactive (IR) cell bodies were not found in the MOB. The serotonin-IR nerve fibres had a specific laminar distribution and morphology in the gerbil MOB. Serotonin-IR nerve fibres were observed in the glomerular, external plexiform and granule cell layers of the MOB. These serotonin-IR nerve fibres showed varicosities that were larger than the thickness of the axon. The highest density of serotonin-IR nerve fibres was in glomeruli of the glomerular layer. The average fibre density in the glomerular layer was more than three to four times the density in the infraglomerular layers. Glomerular serotonin-IR fibres were much more intensively stained than infraglomerular serotonin-IR fibres. This result suggests that serotonin-IR nerve fibres of Mongolian gerbil MOB are extrinsic and may act to modulate the olfactory transmission.
    Anantomia Histologia Embryologia 05/2001; 30(2):117-20. DOI:10.1046/j.1439-0264.2001.00314.x · 0.74 Impact Factor
  • Sang Won Suh · Seung Mook Jo · Zsolt Vajda · Gorm Danscher
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    ABSTRACT: Chelatable zinc ions from synaptic vesicles have been suggested to be involved in neuronal death caused by stroke, epilepsy and head trauma. Elevated glucocorticoid concentration exacerbates such neuron loss, while low levels protect. We have tested the notion that the neuroprotective effect of prior glucocorticoid reduction is mediated by a reduction of zinc ions contained in zinc-enriched (ZEN) synaptic vesicles. The level of vesicular zinc ions was evaluated by toluene sulfonamide quinoline (TSQ) fluorometry and zinc autometallography (ZnSAMG) 10 and 30 days, respectively, after adrenalectomy. The hippocampus showed significant vesicular zinc ion depletion following adrenalectomy. After the kainate injection, adrenalectomized rats showed proconvulsive seizure behavior, i.e. shortened latency to seizure onset time and increased seizure score. Additionally they showed decreased hippocampal CA3 neuronal death as compared to control animals. The present data suggest that zinc ions released from damaged ZEN terminals are involved in seizure-induced neuronal death.
    Brain Research 04/2001; 895(1-2-895):25-32. DOI:10.1016/S0006-8993(01)01996-5 · 2.83 Impact Factor

Publication Stats

808 Citations
93.52 Total Impact Points


  • 2005–2008
    • Korea Institute of Science and Technology
      • Electronic Materials Research Center
      Sŏul, Seoul, South Korea
  • 2000–2005
    • Aarhus University
      • Institute of Anatomy
      Aarhus, Central Jutland, Denmark
  • 2004
    • University of California, Davis
      Davis, California, United States
  • 1997–2003
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2002
    • Hanyang University
      • Division of Chemical Engineering and Bioengineering
      Sŏul, Seoul, South Korea