Publications by authors named "Youn-Joong Kim"

Exosomes are extracellular nanovesicles secreted by cells that efficiently deliver therapeutic cargo for cancer treatment. However, because exosomes are present in low quantities and have limited target specificity, internal and external stress stimulation has been studied to increase exosome efficiency. Inspired by these studies, the uptake efficiency of cobalt chloride-induced hypoxic cancer cell-secreted exosomes was evaluated.

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(1) Background: The purpose of this study was to evaluate the 3-dimensional bony changes of the mandibular condyle in temporomandibular joints-osteoarthritis (TMJ-OA) patients treated with stabilization splint (SS) therapy using shape correspondence analysis. (2) Methods: A total of 27 adult patients (2 men and 25 women) with a mean age of 24.6 ± 3.

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The aim of this study was to assess the changes in individual condyles from 5 to 8 years in patients with temporomandibular joint (TMJ) osteoarthritis using 3-dimensional cone beam computed tomography (3D CBCT) reconstruction and superimposition. To assess the longitudinal TMJ changes, CBCT was performed at initial (T) and final (T) timepoints that were at least 5 years apart and at a middle (T) timepoint. To improve the accuracy, we used a novel superimposition method that designated areas of coronoid process and mandibular body.

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Synthesis of a two-dimensional (2D) highly crystalline composite, P(Py:BPDSA:Py)-GO, from the growth of a close-packed polymer crystal, P(Py:BPDSA:Py), on graphene oxide (GO) sheets via in situ polymerization of two-monomer-connected precursors (TMCPs, Py:BPDSA:Py), in which two pyrrole (Py) molecules are linked through a connector (4,4'-biphenyldisulfonic acid) (BPDSA), is reported. When the TMCP is polymerized on GO, it leads to an exceptionally ordered structure determined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) studies. X-ray crystallography of the composite shows crystalline peaks with d spacings in the [100] direction.

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We have applied correlative microscopy to identify the key constituents of a dorsal rib fossil from Koreanosaurus boseongensis and its hosting mudstone discovered at the rich fossil site in Boseong, South Korea, to investigate the factors that likely contributed to diagenesis and the preservation of fossil bone. Calcite and illite were the commonly occurring phases in the rib bone, hosting mudstone, and the boundary region in-between. The boundary region may have contributed to bone preservation once it fully formed by acting as a protective shell.

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Osteohistological researches on dinosaurs are well documented, but descriptions of direct correlations between the bone microstructure and corresponding nanostructure are currently lacking. By applying correlative microscopy, we aimed to verify that well-preserved osteohistological features correlate with pristine fossil bone nanostructures from the femoral bones of Koreanosaurus boseongensis. The quality of nanostructural preservation was evaluated based on the preferred orientation level of apatite crystals obtained from selected area electron diffraction (SAED) patterns and by measuring the "arcs" from the {100} and {002} diffraction rings.

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The design of crystalline polymers is intellectually stimulating and synthetically challenging, especially when the polymerization of any monomer occurs in a linear dimension. Such linear growth often leads to entropically driven chain entanglements and thus is detrimental to attempts to realize the full potential of conjugated molecular structures. Here we report the polymerization of two-monomer-connected precursors (TMCPs) in which two pyrrole units are linked through a connector, yielding highly crystalline polymers.

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Immobilisation of heavy metals in geopolymers has attracted attention as a potential means of treating toxic wastes. Lead is known to be effectively immobilised in a geopolymer matrix, but detailed explanation for the mechanisms involved and the specific chemical form of lead are not fully understood. To reveal the effect of the activator types on the immobilisation of lead in geopolymers, 0.

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This article describes the case of a 41-year-old woman who presented with the complaint of crepitation sound and mild pain in the left temporomandibular joint area. Panoramic radiographs taken to rule out degenerative or arthritic changes in the joints demonstrated a radiopaque mass within the left condyle. Cone beam computed tomography scans revealed an ectopic tooth located centrally within the left condyle.

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Vacuolar-type H(+)-ATPase (V-ATPase) is a multi-subunit proton pump. The proton pump is essential for the regulation of pH in various eukaryotic cellular processes. Among the 14 subunits that constitute V-ATPase, d subunit mediates coupling between cytosolic and membrane domains.

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Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3-hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs.

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Polyamidoamine (PAMAM) is one of the widely employed non-viral vectors in gene therapy research, and shows excellent biocompatibility and relatively low cytotoxicity. However, it has poor transfection efficiency compared with that of polyethylenimine (PEI, 25 kDa). To enhance the gene expression efficiency, we introduced the RRRK peptide from mouse fibroblast growth factor 3 (FGF3) to PAMAM, which is a known nuclear localization signal (NLS).

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On the basis of Pauling's first rule for ionic bonding, the coordination number of cations with oxygen anions can be determined by comparison of their relative ionic size ratio. In contrast to simple oxides, various site occupancies by multicomponent cations with similar sizes usually occur in complex oxides, resulting in distinct physical properties. Through an unprecedented combination of in situ high-temperature high-resolution electron microscopy, crystallographic image processing, geometric phase analysis, and neutron powder diffraction, we directly demonstrate that while the initial crystallites after nucleation during crystallization have a very high degree of ordering, significant local cation disordering is induced by rapid crystal growth in Li-intercalation metal-phosphate nanocrystals.

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The reaction between atactic poly(2-vinylpyridine) and 1,4-dibromobutane leads to formation of long-range 3D molecular ordering in polymer chains mainly because the side group (pyridine) of the polymer chain changes to a syndotactic configuration. This may enable the production of functional molecular devices that operate on a 3D atomic scale.

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Single-crystalline rock-salt PbS nanowires (NWs) were synthesized using three different routes; the solvothermal, chemical vapor transport, and gas-phase substitution reaction of pregrown CdS NWs. They were uniformly grown with the [100] or [110], [112] direction in a controlled manner. In the solvothermal growth, the oriented attachment of the octylamine (OA) ligands enables the NWs to be produced with a controlled morphology and growth direction.

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We performed structure analysis of Si single crystal and CaMoO(4) inorganic crystal by energy-filtered precession electron diffraction (PED). Structure analysis was performed using conventional selected area electron diffraction, PED and energy-filtered PED (EF-PED). The EF-PED method proved to be advantageous in determining the crystal structures and accurate cell parameters of inorganic crystals due to resolution enhancement by sharpening the peak shapes and reducing inelastic scattering.

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This work presents variation of oxidative catalytic activities of methanol and formic acid on Pt nanoparticles of various sizes and a comparison to the results observed on Pt(111), Pt(100), and polycrystalline Pt. The Pt nanoparticles dispersed on platelet carbon nanofiber are cuboctahedral particles, whose sizes span from 5.6 to 1.

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The phase transition phenomena of Ge2Sb2Te5 chalcogenides were investigated by in situ dynamic high-resolution transmission electron microscopy (HR-TEM) and electron energy loss spectroscopy (EELS). A 300kV field emission TEM and a 1250kV high voltage TEM were employed for the in situ heating experiments from 20 to 500 degrees C for undoped and 3wt% nitrogen-doped Ge2Sb2Te5 thin films deposited by DC sputtering. Crystallization of amorphous Ge2Sb2Te5 to its cubic structure phase started at 130 degrees C and then rapid crystal growth developed from cubic to hexagonal phase in the range of 130-350 degrees C; finally, the hexagonal crystals started to melt at 500 degrees C.

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Threadlike structures on the surfaces of mammalian internal organs were recently observed, and they can be the anatomical basis of the meridian-like network of internal organs as detected by the Bi-Digital O-Ring test imaging method. Morphological and histological studies were performed to reveal their novel features by using confocal and electron microscopy, and there is evidence that reveals that they have a ductal structure in which some liquid flows. They form a part of the network of acupuncture meridians that is thought to be a circulatory system distributed throughout an animal body.

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Electron detection characteristics such as modulation transfer function (MTF), detection quantum efficiency (DQE), dynamic range, linearity, average gain, and uniformity of a high-voltage multiscan CCD (HV-MSC, 1K x 1K pixels) camera were evaluated. This camera was used as a major recording medium in a high-voltage electron microscope (HVEM) installed at the Korea Basic Science Institute (KBSI). In spite of the high energy of the incident electrons, the overall properties of the HV-MSC camera were comparable to other CCD cameras for a low-voltage electron microscope (LVEM).

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Electron beam irradiation can change the bulk structure of a specimen permanently. The crystallizations of amorphous phases in the 900 degrees C-heated kaolinite by electron beam irradiation and natural kaolinite by in situ heating are observed in a 1250 keV HVEM in this study. Crystalline silicon was formed in both cases.

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There have been several reports on novel threadlike structures (NTSs) on the surfaces of the internal organs of rats and rabbits since their first observation by Bonghan Kim in 1963. To confirm this novel circulatory function, it is necessary to observe the flow of liquid through the NTS as well as the structurally corroborating channels in the NTS. In this article, we report on the measurement of the flow speed of Alcian blue solution in the NTSs on the organ surfaces of rabbits, and we present electron microscopic images depicting the cribrous cross-section with channels.

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We introduce a simple preparation method for ultrathin carbon support films that is especially useful for high-resolution electron microscopy (HREM) of nanoparticles. Oxidized iron nanoparticles were used as a test sample in a demonstration of this method. The film qualities are discussed on the basis of electron-energy-loss spectroscopy (EELS) and image analysis techniques such as thickness maps and histograms.

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