• Nano
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• v.13 no.11
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• pp.1850129.1-1850129.10
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• 2018

To improve the high charge carrier recombination rate and low visible light absorption of {001} facets exposed $TiO_2$ [$TiO_2(001)$] nanosheets, few-layered $MoS_2$ nanoparticles were loaded on the surfaces of $TiO_2(001)$ nanosheets by a simple photodeposition method. The photocatalytic activities towards Rhodamine B (RhB) were investigated. The results showed that the $MoS_2-TiO_2(001)$ nanocomposites exhibited much enhanced photocatalytic activities compared with the pure $TiO_2(001)$ nanosheets. At an optimal Mo/Ti molar ratio of 25%, the $MoS_2-TiO_2(001)$ nanocomposites displayed the highest photocatalytic activity, which took only 30 min to degrade 50 mL of RhB (50 mg/L). The active species in the degradation reaction were determined to be $h^+$ and $^{\bullet}OH$ according to the free radical trapping experiments. The reduced charge carrier recombination rate, enhanced visible light utilization and increased surface areas contributed to the enhanced photocatalytic performances of the 25% $MoS_2-TiO_2(001)$ nanocomposites.

• KSBB Journal
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• v.25 no.2
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• pp.155-166
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• 2010

Studies on the production of cell-wall bound innerpolysaccharides (IPS) (soluble ${\beta}$-D-glucan) have been performed by use of suspended myelial cultures of Inonotus obliquus. This product has promising potentials as an effective antidiabetic as well as an immunostimulating agents. As a first step to enhanced production of IPS, Intensive strain improvement programs were carried out by obtaining a large amounts of protoplasts for the isolation of single cell colonies. Rapid and large screening of high-yielding producers was possible because about fivefold higher amount of protoplasts ($2.3{\times}10^6$ protoplasts/mL) could be recovered with relatively high regeneration rates of $10^{-2}{\sim}10^{-3}$ by applying a modified filtration method, as compared to the previously used trapping method. A basic protocol necessary for UV-mutation of the protoplasts was also developed, resulting in several overproducing variants with good fermentation properties. Since the amount of IPS extracted from the mycelial cell walls of I. obliquus turned out to be almost constant per g DCW, increase in cell mass was considered the most important factor for the enhancement in IPS production. Therefore, attempts were made to screen mutant cells showing rapid mycelial growth rate in the final suspended cultures. Notably, the mutant strains showing an active cellgrowth in the preceding solid growth cultures were observed to produce higher amount of IPS in the suspended fermentations as well. A striking mutant, OBLQ756-15-5 strain, obtained from the survivors of a harsh UV-treated condition (97% death rate) was found to stably produce as high cell mass as 22 g DCW/L in the final fermentations. Currently, this strain is being tested for development of a scaled-up fermentation process for mass production of IPS.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.131-137
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• 2013

The thin insulator films for organic memory device were made by the plasma polymerization method using the styrene monomer which was not the wet process but the dry process. For the formation of stable plasma, we make an effort for controlling the monomer with bubbler and circulator system. The thickness of plasma polymerized styrene insulator layer was 430 nm, the thickness of the Au memory layer was 7 nm thickness of plasma polymerized styrene tunneling layer was 30, 60 nm, the thickness of pentacene active layer was 40 nm, the thickness of source and drain electrodes were 50 nm. The I-V characteristics of fabricated memory device got the hysteresis voltage of 45 V at 40/-40 V double sweep measuring conditions. If it compared with the results of previous paper which was the organic memory with the plasma polymerized MMA insulation thin film, this result was greater than 18 V, the improving ratio is 60%. From the paper, styrene indicated a good charge trapping characteristics better than MMA. In the future, we expect to make the organic memory device with plasma polymerized styrene as the memory thin film.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.211-219
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• 2009

Local and seasonal populations of the oriental fruit moth, Grapholita molesta, were monitored with sex pheromone trapping and RAPD (random amplified polymorphic DNA) molecular marker to analyze their movement in apple orchards. To detect their movements among farms, pheromone traps were placed at regions between apple farms ('outside-farms') as well as within-farms ('inside-farms'). Four seasonal adult peaks were evident in apple-cultivating fields from April to October in both trappings of inside- or outside-farms. After overwintering generation, populations of inside-farms were significantly reduced with frequent insecticide applications, compared to populations of outside-farms. Within apple farms, G. molesta tended to be unevenly distributed because of significant sublocal preference. Active movements of local and seasonal populations of G. molesta were supported by gene flow analysis using RAPD marker. Monitoring data using sex pheromone and seasonal reduction in initial genetic differentiation detected in the overwintering populations suggest that there must be significant movement of G. molesta among different orchards in apple-cultivating areas.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.383-392
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• 2020

In this paper, AgCl/Ag₃PO₄/diatomite photocatalyst is successfully synthesized by microemulsion method and anion in situ substitution method. X-ray diffraction (XRD), photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) are used to study the structural and physicochemical characteristics of the AgCl/Ag₃PO₄/diatomite composite. Using rhodamine B (RhB) as a simulated pollutant, the photocatalytic activity and stability of the AgCl/Ag₃PO₄/diatomite composite under visible light are evaluated. In the AgCl/Ag₃PO₄/diatomite visible light system, RhB is nearly 100 % degraded within 15 minutes. And, after five cycles of operation, the photocatalytic activity of AgCl/Ag₃PO₄/diatomite remains at 95 % of the original level, much higher than that of pure Ag₃PO₄ (40 %). In addition, the mechanism of enhanced catalytic performance is discussed. The high photocatalytic performance of AgCl/Ag₃PO₄/diatomite composites can be attributed to the synergistic effect of Ag₃PO₄, diatomite and AgCl nanoparticles. Free radical trapping experiments are used to show that holes and oxygen are the main active species. This material can quickly react with dye molecules adsorbed on the surface of diatomite to degrade RhB dye to CO₂ and H₂O. Even more remarkably, AgCl/Ag₃PO₄/diatomite can maintain above 95 % photo-degradation activity after five cycles.

• Journal of Adhesion and Interface
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• v.22 no.3
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• pp.91-97
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• 2021

By introducing an organic interlayer on the Parylene C dielectric surface, the electrical device performances and the operating stabilities of organic field-effect transistors (OFETs) were improved. To achieve this goal, hexamethyldisilazane (HMDS) and octadecyltrichlorosilane (ODTS), as the organic interlayer materials, were used to control the surface energy of the Parylene C dielectrics. For the bare case used with the pristine Parylene C dielectrics, the field-effect mobility (μ_FET) and threshold voltage (V_th) of dinaphtho[2,3-b:2',3'-f ]thieno[3,2-b]- thiophene (DNTT) FET devices were measured at 0.12 cm²V^-1s^-1 and - 5.23 V, respectively. On the other hand, the OFET devices with HMDS- and ODTS-modified cases showed the improved μ_FET values of 0.32 and 0.34 cm²V^-1s^-1, respectively. More important point is that the μ_FET and V_th of the DNTT FET device with the ODTS-modified Parylene C dielectric presented the smallest changes during a repeated measurement of 1000 times, implying that it has the most stable operating stability. The results could be meaned that the organic interlayer, especially ODTS, effectively covers the Parylene C dielectric surface with alkyl chains and reduces the charge trapping at the interface region between active layer and dielectric, thereby improving the electrical operating stability.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.203-210
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• 2002

In order to elucidate the growth mechanism of sulfide chimney formed as a result of seafloor hydrothermal mineralization, we carried out the mineralogical and fluid inclusion studies on the inactive, sulfide- and silica-rich chimney which has been recovered from a hydrothermal field in the Cleft segment of the Juan de Fuca Ridge. According to previous studies, many active and inactive vents are present in the Cleft segment. The sulfide- and silica-rich chimney is composed of amorphous silica, pyrite, sphalerite and wurtzite with minor amounts of chalcopyrite and marcasite. The interior part of the chimney is highly porous and represents a flow channel. Open spaces within chimneys are typically coated with colloform layers of amorphous silica. The FeS content of Zn-sulfides varies widely from 13.9 to 34.3 mole% with Fe-rich core and Fe-poor rims. This variation possibly reflects the change of physicochemical characteristics of hydrothermal fluids. Chemical and mineralogical compositions of the each growth zone are also varied, possibly due to a thermal gradient. Based on the microthermometric measurements of liquid-rich, two-phase inclusions in amorphous silica that was precipitated in the late stage of mineralization, minimum trapping temperatures are estimated to be about 1140 to 145$^{\circ}$C with the salinities between 3.2 and 4.8 wt.% NaCI equiv. Although the actual fluid temperatures of the vent are not available, this study suggests that the lowtemperature conditions were predominant during the mineralization in the hydrothermal field at Cleft segment. Comparing with the previously reported chimney types, the morphology, colloform texture, bulk chemistry, and a characteristic mineral assemblage (pyrite + marcasite + wurtzite + amorphous silica) of this chimney indicate that the chimney have been formed from a relatively low-temperature (<250$^{\circ}$C) hydrothermal fluid that was changed by sluggish fluid flow and conductive cooling.