• The Plant Pathology Journal
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• v.23 no.4
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• pp.272-280
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• 2007

Isolates of Cucumber mosaic virus (CMV) collected in Korea, were compared with their pathological features in tobacco and zucchini squash. Full-length cDNA clone of RNA3 was generated by using long-distance RT-PCR. Transcript RNA3 from the cDNA clone was inoculated onto host plants with transcripts RNA1 and RNA2 of Fny strain, generating RNA3-pseudorecombinant CMV. Timing and severity of systemic symptom was not significantly different among the pseudorecombinant CMVs in tobacco, compared with strains Fny-CMV and Pf-CMV. However, the pseudorecombinant CMVs induced two different systemic symptoms (mosaic vs. chlorotic spot) in zucchini squash. Based on symptom induction, the pseudorecombinant CMVs were categorized into two classes. The severity and timing of symptoms were correlated with viral RNA accumulations in systemic leaves of zucchini squash, suggesting that different kinetics of virus movement associated with CMV proteins are crucial for systemic infection and symptom development in zucchini squash. The analysis of movement proteins (MP) of CMV strains showed high sequence homology, but the differences of several amino acids were found in the C-terminal region between Class-I-CMV and Class-II-CMV. The analysis of coat proteins (CP) showed that the CMV isolates tested belonged to CMV subgroup I and the viruses shared overall 87-99% sequence identity in their genomes. Phylogenetic analysis of MP and CP suggested that biological properties of Korean CMV isolates have relationships associated with host species.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1287-1291
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• 2009

The genes of cyanide hydratase(CHT), a kind of nitrilases whichhydrolyze cyanide to formamide were extracted from N. crassa and A. nidulans, the two fungal strains. The recombinant forms of the CHT originated from N. crassa and A. nidulans were prepared with N-terminal hexahistidine purificationtags or no tags, and expressed in E. coli. The enzymes were purified using immobilized metal affinity chromatography. They were compared according to their pH activity profiles, and kinetic parameters. The N. crassa CHT has the wider pH range of activity above 50% and three-fold higher turnover rate (6.6 ${\times}$ $10^8$ $min^{-1}$) than the A. nidulans, meanwhile the CHT of A. nidulans has the higher $K_m$ value. Expression of CHT in both N. crassa and A. nidulans were induced by the presence of KCN, regardless of any presence of nitrogen sources. Max. 82% of KCN was degraded in 60 min for biological degradation tests.

• Environmental Engineering Research
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• v.22 no.2
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• pp.203-209
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• 2017

Innovations in the biofiltration process can provide effective solutions to overcome crucial water pollution problems. The elimination of pollutants is a result of the combined effects of biological oxidation, adsorption and filtration processes. This research aims to evaluate the performance of quartz sand biofiltration for removing total suspended solids, turbidity, color, organic matter, and ammonium from polluted river water and develop an empirical model for designing quartz sand biofilters for the treatment of polluted river water. Experiments were conducted using two biofilter units filled with quartz sand as filter media. A set of experiments were performed to evaluate the effect of hydraulic retention time on biofilter performance in removing water contaminants. The kinetics of organic matter removal were also determined to describe the performance of the biofilter. The results show that biofiltration can significantly remove river water pollutants. Removal efficiency depends on the applied hydraulic retention time. At a hydraulic retention time of two hours, removal efficiencies of total organics, ammonium and total suspended solids were up to 78%, 82%, and 91%, respectively. A model for designing quartz sand biofiltration has been developed from the experimental data.

• Geotechnical Engineering
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• v.14 no.1
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• pp.5-14
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• 1998

In refuse landfill, long-term settlement is considerably dependent upon the biological decomposition of refuse which is distinguished from typical soil behavior. Two equations are combined in order to model long-term settlement behavior of refuse landfill caused by mechanical secondary compression and secondary compression caused by the decomposition of biolegradable refuse. It is suggested that mechanical secondary compression is linear with respcet to the logarithm of time. In order to estimate the settlement that occurs due. to the decomposition of biodegradable refuse, a mathematical model is used which theoretically conoiders the decomposition process related to the solubilization stage of biodegradable refuse solid. This model is based on hydrolysis process and expressed as first order kinetics. The proposed model is applied to Lysimeter compression data of an old refuse. This paper intends to propose the simplest mathematical model which effectively represents settlement caused by the solubilization stage of biodegradable refuse solid on decomposition process.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.560-565
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• 1997

The physicochemical properties of melatonin (MT) in propylene glycol (PG) and 2-hydroxypropyl-.betha.-cyclodextrin $(2-HP{\beta}CD)$ vehicles were characterized. MT was endothermally decomposed as determined by differential scanning calorimetry (DSC). Melting point and heat of fusion obtained were $116.9{\pm}0.24^{\circ}C $.and $7249{\pm}217 cal/mol$., respectively. MT as received from a manufacture was very pure, at least 99.9%. The solubility of MT in PG solution increased slowly until reaching 40% PG and then steeply increased. Solubility of MT increased linearly as concentration of $2-HP{\beta}CD$ without PG INCREASED$(R^2=0.993)$. MT solubility in the mixtures of pg and $2-HP{\beta}CD$ also increased linearly but was less than the sum of its solubility in $2-HP{\beta}CD$ and PG individually. The MT solubility was low in water, simulated gastric or intestinal fluid but the highest in the mixture of PG(40v/v%) and $2-HP{\beta}CD$ (30w/v%) although efficiency of MT solubilization in $2-HP{\beta}CD$ decreased as the concentration of PG increased. MT was degraded in a fashion of the first order kinetics $(r^2>0.90)$. MT was unstable in strong acidic solution (HCl-NaCl buffer, pH 1.4) but relatively stable in other pH values of 4-10 at $70^{\circ}C$. In HCl-NaCl buffer, MT in 10% PG was more quickly degraded and then slowed dpwm at a higher concentration. However, the degradation rate constant of MT in 2-HP.betha.CD was not changed significantly when compared to the water. The current studies can be applied to the dosage formulations for the purpose of enhancing percutaneous absorption or bioavailability of MT.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.57-67
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• 2022

The curing characteristics of naphthalene type epoxy resin systems according to the change of curing agent were investigated to develop a new next-generation EMC(Epoxy Molding Compound) with excellent warpage characteristics, low thermal expansion, and excellent fluidity for WLP(Wafer Level Package). As epoxy resins, DGEBA, which are representative bisphenol type epoxy resins, NE-16, which are the base resins of naphthalene type epoxy resins, and NET-OH, NET-MA, and NET-Epoxy resins newly synthesized based on NE-16 were used. As a curing agent, DDM (Diamino Diphenyl Methane) and CBN resin with naphthalene moiety were used. The curing reaction characteristics of these epoxy resin systems with curing agents were analyzed through thermal analysis experiments. In terms of curing reaction mechanism, DGEBA and NET-OH resin systems follow the nth curing reaction mechanism, and NE-16, NET-MA and NET-Epoxy resin systems follow the autocatalytic curing reaction mechanism in the case of epoxy resin systems using DDM as curing agent. On the other hand, it was found that all of them showed the nth curing reaction mechanism in the case of epoxy resin systems using CBN as the curing agent. Comparing the curing reaction rate, the epoxy resin systems using CBN as the curing agent showed a faster curing reaction rate than them with DDM as a hardener in the case of DGEBA and NET-OH epoxy resin systems following the same nth curing reaction mechanism, and the epoxy resin systems with a different curing mechanism using CBN as a curing agent showed a faster curing reaction rate than DDM hardener systems except for the NE-16 epoxy resin system. These reasons were comparatively explained using the reaction rate parameters obtained through thermal analysis experiments. Based on these results, low thermal expansion, warpage reduction, and curing reaction rate in the epoxy resin systems can be improved by using CBN curing agent with a naphthalene moiety.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.117-128
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• 2022

In this study, we have examined pyrethroid actions on sodium channels in the pest insect Heliothis virescens. The synthetic pyrethroid permethrin increased steady-state sodium current in H. virescens central neurons and prolonged tail currents (I_Na-tail) due to extreme slowing of sodium channel deactivation. Prolongation of I_Na-tail was evident at permethrin concentrations as low as 60 nM, which modified ~1.7% of sodium channels and 10 μM permethrin modified about 30% of channels. The average time constant (τ₁) of tail current decay was ~335 ms for permethrin-modified channels. These modified channels activated at more negative potentials and showed slower activation kinetics, and failed to inactivate. Permethrin modification of sodium channels was dramatically potentiated by the α scorpion toxin LqhαIT, showing positive cooperativity between two binding sites. The amplitude of the tail current induced by 0.3 μM permethrin was enhanced ~8-fold by LqhαIT (200 pM). Positive cooperativity was also observed between permethrin and the insect-specific scorpion toxin AaIT as 10 nM permethrin potentiated the shift of voltage dependence caused by AaIT (~2-fold).

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.318-325
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• 2023

The detection of antibiotics in treated wastewater is a global concern as it enters water bodies and causes the development of antibiotic resistance genes in humans and marine life. The study specifically aims to explore the potential of ferrate (VI) in eliminating tetracycline (TCL). The degradation of TCL is optimized with parametric studies, viz., the effect of pH and concentration, which provide insights into TCL elimination. The increase in pH (from 7.0 to 10.0) favors the percentage removal of TCL; however, the increase in TCL concentrations from 0.02 to 0.3 mmol/L caused a decrease in percentage TCL removal from 97.4 to 29.1%, respectively, at pH 10.0. The time-dependent elimination of TCL using ferrate (VI) followed pseudosecond-order rate kinetics, and an apparent rate constant (kapp) was found at 1978.8 L² /mol² /min. Coexisting ions, i.e., NaNO₃, Na₂HPO₄, NaCl, and oxalic acid, negligibly affect the oxidation of TCL by ferrate (VI). However, EDTA and glycine significantly inhibited the elimination of TCL using ferrate (VI). The mineralization of TCL using ferrate (VI) was favored at higher pH, and it increased from 18.57 to 32.52% when the solution pH increased from pH 7.0 to 10.0. Additionally, the real water samples containing a relatively high level of inorganic carbon spiked with TCL revealed that ferrate (VI) performance in the removal of TCL was unaffected, which further inferred the potential of ferrate (VI) in real implications.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.181-190
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• 2024

Here, we develop a centrifugal microfluidic reactor with simple, fast, and high-throughput manner for the generation of magnetic Janus micro-adsorbents (MAs). By using the multi-micronozzle consisting of two separate aligned needles and centrifugal tubes, we have synthesized highly monodispersed Prussian blue- and magnetic nanoparticle-laden micro-adsorbents (PB-MNP-MAs). The enhanced cesium (Cs⁺) adsorption was demonstrated by conducting the adsorption isotherm and kinetics experiment which can be contributed to the porous nature of the Ca-alginate networks with a high surface area of embedded PB nanoparticles, resulting to perform rapid adsorption activity within 10 min. After Cs⁺ adsorption process, the as-synthesized PB-MNP-MAs were successfully harvested by introducing the external magnetic fields. Therefore, we believe that our findings can be provided new direction towards the development of advanced functional adsorbents in biological and environmental fields.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.4
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• pp.323-333
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• 2024

Polychlorinated biphenyls (PCBs) were once used throughout various industries; however, because of their persistence in the environment, exposure remains a global threat to the environment and human health. The Kv1.3 and Kv1.5 channels have been implicated in the immunotoxicity and cardiotoxicity of PCBs, respectively. We determined whether 3,3',4,4'-tetrachlorobiphenyl (PCB77), a dioxin-like PCB, alters human Kv1.3 and Kv1.5 currents using the Xenopus oocyte expression system. Exposure to 10 nM PCB77 for 15 min enhanced the Kv1.3 current by approximately 30.6%, whereas PCB77 did not affect the Kv1.5 current at concentrations up to 10 nM. This increase in the Kv1.3 current was associated with slower activation and inactivation kinetics as well as right-shifting of the steady-state activation curve. Pretreatment with PCB77 significantly suppressed tumor necrosis factor-α and interleukin-10 production in lipopolysaccharide-stimulated Raw264.7 macrophages. Overall, these data suggest that acute exposure to trace concentrations of PCB77 impairs immune function, possibly by enhancing Kv1.3 currents.