• Membrane Journal
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• v.27 no.3
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• pp.232-239
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• 2017

In this study, the regeneration investigation for waste reverse osmosis membrane filters which were discarded after use for the household water purifiers has been carried out. Sodium hydroxide, sodium bisulfate, and ethylenediamine tetra acetic acid(EDTA). as the chemical cleaning agents were used. And they were in-situ cleaned with the micro-bubble generator as well. The best result was obtained when both 0.1% EDTA and micro-bubbles were used for 30 min cleaning. Thus, when the performance of the brand new RO membrane and restorated RO membrane were compared, the flux, 19.9%, the recovery ratio 45% were enhanced while the salt rejection was reduced for NaCl 100 mg/L solution, in other words, it has been recovered to the original brand new RO membrane filter. Also the removal of pollutants on membrane surface was confirmed in a naked eye through the scanning electron microscopy. Finally, this research has provided the possibility of the re-use of the waste RO membrane filters of household water purifier which were reclaimed or incinerated after use.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.289-299
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• 2005

Annealing experiments on albite powders, thin sections, and TEM specimens have been performed utilizing an optical microscope heating stage. Sample orientations were determined by optical microscope and XRD, and then confirmed by TEM diffraction patterns. Partial melting of samples occurred at $1030^{\circ}C$-l2 hr for powder, but at $1060^{\circ}C$-12 hr for TEM specimen. It is difficult to get TEM images of albite microstructures above this temperature due to thickening and the amorphous phase of the melted part. Correlative studies between optical microscopy and TEM indicated that the $1050^{\circ}C$-12 hr annealing in ambient condition was most adequate to observe tweed microstructures in albite through TEM. In situ TEM heating experiments for direct observation of tweed microstructures in albite may require annealing at slightly higher temperatures than $1050^{\circ}C$ considering the high vacuum condition inside TEM.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.280-290
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• 1999

The microstructures of a Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.6}Ca_2Cu_3O_{9+{\delta}}$/Ag tape (tape I ) with J$_c$ of 17,600 A/cm$^2$ at 77 K and 0 T and three Tl$_{0.8}Pb_{0.2}Bi_{0.2}Sr_{1.8}Ba_{0.2}Ca_{2.2}Cu_3O_{9+{\delta}}$/Ag tapes with J$_c$'s of 9,300 (tape II), 16,700 (tape III) and 25,200 A/cm$^2$ (tape IV)prepared using the powder-in-tube method and an in-situ reaction method, were investigated using scanning electron microscopy and high-resolution transmission electron microscopy, and compared each other. ln the tape preparation, an intermediate rolling process was incorporated during final heat-treatment for the last tape, but not for the rest of the tapes. The microstructural analysis revealed clear differences in grain-texturing, crystallographic defects and impurity phases, depending on the chemical composition of the tape. Tendency of directional grain-alignment increased in an order of tapes I, II III and IV. In tape IV, T1-1223 grains are textured, at least in local regions. In crystallographic defects, while stacking faults were prevalent in the former composition, dislocations and voids were frequently observed in the latter. Also impurity phases were appeared to be more abundant in the former than in the latter. The relationship between 1,and the microstructure in the tapes was attempted to explain in a term of grain-linking.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.4
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• pp.255-265
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• 1997

Precipitation and strengthening mechanisms in squeeze cast Mg-8.5wt%Li-4.5wt%Al have been investigated by differential scanning calorimetry(DSC), scanning electron microscopy(SEM), in-situ and ex-situ X-ray diffraction analysis and hardness measurement. Special emphasis was placed on the investigation of the precipitation behavior by the DSC technique. Microstructural and calorimetric analysis showed that ${\theta}$ and ${\delta}$ precipitates in the b.c.c. ${\beta}$ phase matrix, forming two exothermic peaks at the temperature ranges of $130^{\circ}C{\sim}180^{\circ}C$ and $236^{\circ}C{\sim}280^{\circ}C$. ${\theta}$ and ${\delta}$ dissolve into the matrix forming an endothermic peak at the temperature range of $280^{\circ}C{\sim}352^{\circ}C$. The as-cast microstructure consists of ${\alpha}$, ${\beta}$ and ${\delta}$. Peak strength was obtained after aging for 1 hour at $50^{\circ}C$. The aging time required for the peak strength decreased as the aging temperature increases. The hardness decrease during overaging was due to the coarsening of ${\theta}$ precipitates. Microhardness measurement showed that variation of the hardness of ${\beta}$ matrix was more pronounced than that of the ${\alpha}$ phase, indicating that the ${\beta}$ phase is more responsible for the strengthening of the Mg-8.5wt%Li-4.5wt%Al alloy.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.281-287
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• 2009

Pd was deposited on magnesium-oxide-covered magnesium ribon substrate by metal thermal evaporation method in high vacuum. The electronic and chemical properties of Pd samples with different coverages were studied using in-situ X-ray Photoelctron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (SEM). For relatively lower amounts of Pd deposited(< 1nm), separate Pd particles could be observed, whereas at higher Pd coverages, Pd thin films caused by agglomeration of Pd nanoparticles was found. The metal support interaction with Pd-support was observed. The Pd atoms on the metal oxide/metal interface were partially negative charged by charge transfer.

• Polymer(Korea)
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• v.31 no.6
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• pp.518-525
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• 2007

The thermomechanical properties and morphologies of nanocomposite fibers of poly(ethylene terephthalate)(PET) incorporating thermally stable organoclays are compared. Dodecyltriphenyl-phosphonium-mica($C_{12}PPh-Mica$) and 1-hexadecane benzimidazole-mica ($C_{16}BIMD-Mica$) were used as reinforcing fillers in the fabrication of PET hybrid fibers. Dispersions of organoclays with PET were studied by using the in-situ polymerization method at various organoclay contents to produce nano-scale composites. The thermo-mechanical properties and morphologies of the PET hybrid fibers were determined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (XRD), electron microscopy (SEM and TEM), and a universal tensile machine (UTM). Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nano-scale, although some clay particles are agglomerated. We also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the PET nanocomposite fibers. Even polymers with low organoclay content (<5 wt%) were found to exhibit much higher thermo-mechanical values than pure PET fibers.

• Imaging Science in Dentistry
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• v.31 no.4
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• pp.227-233
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• 2001

Purpose: The purpose of this study was to investigate the apoptosis induction in tissues constituting the craniofacial region of growing rat by irradiation. Materials and Methods: The submandibular gland, brain, articular cartilage of condylar head, and calvarium were extracted from 20-day-old rats irradiated 10 Gy. Apoptosis of each tissue was examined by DNA fragmentation and estimated quantitatively using apoptotic index on TUNEL assay. Apoptotic index of each tissue was calculated by the equation for apoptotic cells/total cells × 1,000 on the images of confocal laser scanning microscopy. Apoptotic index was analyzed statistically according to the time lapse after irradiation on the tissues. Results : In the submandibular gland, apoptotic index was significantly increased from 6 hours after irradiation showing the highest value at 12 hours and decreased to the control level at 3 days after irradiation. In the brain, apoptotic index was abruptly reached to the maximum value at 6 hours after irradiation and decreased to the control level at 4 days after irradiation. Articular cartilage and calvarium showed no or little apoptotic signals. The results obtained by the apoptotic index accorded with that of DNA fragmentation. Conclusion : Radiation was closely related with the apoptosis of submandibular gland and brain but, not related with the apoptosis of the articular cartilage of condylar head and calvarium. The changes induced by radiation of the hard tissues would not be explained by apoptosis.

• Journal of Aquaculture
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• v.15 no.1
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• pp.7-13
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• 2002

Since 1993, the White Spot Syndrome Virus (WSSV) disease occurred in China among cultured shrimps resulting in mass mortality. Epizootiological surveys undertaken during the outbreak period of 1993-1994 indicated that all stages of Penaeus chinensis, P. japonicus and P. monodon were infected. Consequent to the transport of contaminated shrimp seedlings and seawater, the disease spread all over the farms of China. The disease was more rapidly transmitted at temperatures above $25^{\circ}C$. Challenge experiments showed the causative agent was highly virulent. White spots appeared on the carapace of both span-taneous and experimentally infected shrimps. Moribund shrimps contained turbid hemolymph, hypertrophied Iymphoid organ and a necrotic mid-gut gland. Electron microscopy showed the presence of viral particles in the gills, stomach, lymphoid organ, and epidermal tissue of the infected shrimp. The visions were slightly ovoid with an envelope and averaged 350 $\times$ 150 nm; nucleocapsids measured 375 $\times$ 157 nm. With discontinuous sucrose gradient of 35, 50 and 60% (w/v), the virus was separated from hemolymph of the infected shrimp. The estimated molecular weight of genomic DNA was 237 Kb with EcoR I, 247 Kb with Hind III and 241kb with Pst I. A total of 9 hybridoma colones secreting monoclonal antibodies (MAbs) were produced from mouse myeloma and spleen cells immunized with WSSV. The immunofluorescence assay of gill tissue showed that the MAbs reacted with diseased but not with healthy shrimp. The MAbs belonged to IgGl, IgG2b subclass and IgM class, all with kappa light Immune-electron-microscopy with colloidal gold marker showed the presence of 5 MAbs epitopes on the envelope and one on the capsid of the virus. Baculoviral mid-gut gland necrosis showed the specificity of the MAbs produced. For diagnosis 5 different methods were selected. Using Kimura primers for PCR, or MAbs for immunoblot, ELISA or FAT method, in situ hybridization was carried out to show the gene. All these methods detected WSSV in the organ samples of the diseased shrimp but not in healthy one.

• Applied Microscopy
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• v.20 no.2
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• pp.57-70
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• 1990

Characterization and electron microscopic visualization of the plasmid and the gene expression of Escherichia coli were carried out. Transcriptional units of active structural genes were observed after lysis of Escherichia coli cells. The ribosomes attached to the E. coli genome on mRNA molecule as polyribosomes. From this gradient of polyribosome length, we estimated location of mRNA synthesis initiation site. In this experiment, a granule is ofen present which may correspond to a RNA polymerase at the promoter site. pOX1, pOX7, pOX7A, $pOX7{\Delta}1$, pSTP36, pSTP21, pBR322, and pJH12 were visualized by way of electron microscope, and their estimated sizes were determined to be $5.70{\pm}0.08{\mu}m,\;2.15{\pm}0.10{\mu}m,\;2.14{\pm}0.12{\mu}m,\;7.39{\pm}0.08{\mu}m,\;4.03{\pm}0.04{\mu}m,\;1.50{\pm}0.03{\mu}m\;and\;1.25{\pm}0.09{\mu}m$ respectively. One micrometer of measured length corresponded to about 3.0 Kb. Mica-press adsorption method that allows selectivs visualization of the plasmid DNA released in situ from the bacterial cell is rapid and useful for visualization of plasmids. The released plasmid DNA was adsorbed preferently on mica in a divalent cation-free solution. Miller chromatin-spreading method was useful to observe the plasmid and transcripts. BAC method and cytochrome C monolayer were useful to observe the plasmid DNA. Our ability to visualize ultrastructural aspects of the expression of E. coli has given us a unique tool with which to study the regulation the level of an individual gene.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.156-161
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• 2020

In this study, hierarchical mesoporous CuO spheres, ZnO flowers, and heterojunction CuO/ZnO nanostructures were fabricated via a facile hydrothermal method. The as-prepared materials were characterized in detail using various analytical methods such as powder X-ray diffraction, micro Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy. The obtained results are consistent with each other. The H₂S-sensing characteristics of the sensors fabricated based on the CuO spheres, ZnO flowers, and CuO/ZnO heterojunction were investigated at different temperatures and gas concentrations. The sensor based on ZnO flowers showed a maximum response of ~141 at 225 ℃. The sensor based on CuO spheres exhibited a maximum response of 218 at 175 ℃, whereas the sensor based on the CuO/ZnO nano-heterostructure composite showed a maximum response of 344 at 150 ℃. The detection limit (DL) of the sensor based on the CuO/ZnO heterojunction was ~120 ppb at 150 ℃. The CuO/ZnO sensor showed the maximum response to H₂S compared with other interfering gases such as ethanol, methanol, and CO, indicating its high selectivity.