• Journal of Life Science
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• v.20 no.1
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• pp.77-81
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• 2010

We separated the bacteria showing protease activity from Reticulitermes speratus which is known as the only termite species in Korea. Then, we collected the best activated strain and studied the optimal culture condition for producing the enzyme. According to the results of observing morphological and physiological characteristics, and the type of 16S rRNA of the strain, it was identified as Serratia marcescens and named S. marcescens strain TM-3215. This strain showed the best activity under conditions of 0.8% (w/v) starch, 0.4% (w/v) peptone, 0.08% (w/v) $MgSO_4{\cdot}7H_2O$, $30^{\circ}C$ and pH 8.0. After being cultivated under optimal conditions for 9 hr, the strain produced 19.8 U/ml of enzyme, an amount 1.8 times greater than the control.

• Journal of Radiation Protection and Research
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• v.29 no.4
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• pp.263-268
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• 2004

Using the Monte Carlo simulation, a study on the lion-proportionality of the prototype phoswich detector with $2'{\times}2'$ CSI(Tl) and plastic scintillator, which was made by KAERI, has been carried. The defector response functions (DRFs) calculated by simulations were compared with the experimental measurement on the $^{137}Cs\;and\;^{60}Co$. To precisely simulate the DRF for the phoswich, the CSI(Tl) non-proportionality was calculated using the electron response and the simplified electron cascade sequence for treating the photoelectric absorption event. The resulting DRFs of $^{137}Cs\;and\;^{60}Co$ sources obtained by simulations were compared with experiments for verification. For $^{137}Cs$, gamma-ray responses simulated by MCNP5 are generally good agreement with the measured ones. But the DRF of $^{60}Co$ does not match well with the results of experiment in the energy region below second peak due to the coincidence effect of two gamma-rays (1.17 MeV and 1.33 MeV). Through the analysis of the non-proportionality of CsI(Tl) in the prototype phoswich, the improved DRFs considering non-proportionality were produced and the simulation results were verified using the experimental measurements. However, to more precisely reproduce the DRF for the phoswich, further studies in relation to the electron channeling effect and the Doppler broadening effect of a scintillator are still needed as well as considering that effect of the transfer contribution.

• Journal of Radiation Protection and Research
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• v.29 no.4
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• pp.251-256
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• 2004

CsI(Tl), $CdWO_4(CWO),\;Bi_4Ge_3O_{12}(BGO)\;and\;Gd_2SiO_5:Ce(GSO)$ scintillators were studied to manufacture a phoswich detector. The maximum wavelengths of the CsI(Tl), CWO, BGO and GSO scintillators are 550 nm, 475 nm, 490 nm and 440 nm for the radioluminescence, and the absolute light outputs of the CsI(Tl), CWO, BGO and GSO scintillators are 54890 phonon/MeV, 17762 phonon/MeV, 8322 phonon/MeV and 8932 phonon/MeV with a neutral filter, and the decay time of the CsI(Tl), CWO, BGO and GSO scintillators is $1.3{\mu}s,\;8.17{\mu}s$, 213 ns and 37 ns by a single photon method. The phoswich detector which was manufactured with plastic and CsI(Tl) scintillators could separate the ${\beta}$ particle and ${\gamma}$ ray. The phoswich detector could also measure the pulse height spectra of the ${\beta}$ particle and ${\gamma}$ ray by a PSD method.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.200-208
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• 2011

The neutron fluence measurement and evaluation technology is very important for material irradiation test. The most essential technology in this study is the neutron irradiation evaluation method using a fluence monitor. The fluence monitors were fabricated with metal wires of the purity ${\geq}$ 99.9%, whose dimensions were 0.1mm diameter, about 3 mm length, and around 150-200 ${\mu}g$ mass range. Three wire samples (Fe, Ni, Ti) were prepared for one irradiation aluminum capsule. Five capsules were irradiated in the OR5 hole of the HANARO reactor at 30 MW power for about 25 days. After irradiation tests, radiation activities were measured with the high purity germanium (HPGe) detector. The reaction rates were calculated by using the measured radiation activity data, and then neutron fluence were obtained from the reaction rates and the weighted neutron cross section with calculated neutron spectrum at the fluence monitor position.

• Journal of Aquaculture
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• v.11 no.4
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• pp.495-503
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• 1998

The present study investigated the effects of Bisroot, that contains live bacteria (Bacillus polyfermenticus, Bacillus mesentericus, Streptococcus faecalis, & Bifidobacterium breve) and digestive enzymes (protease, lipase), on the growth, body composition and immune response of Nile tilapia fingerlings. One percent of the Bisroot was added to the experimenta feed. All exprimental fish were fed for 60 days. The weigh gains among the experimental fish were not significntly different (P>0.05). Hematocrit value, hemoglobin, total protein, glucose, GOT, and GPT were unaffected by Bisroot treatment. However, it was observed that glucose, GOT, and GPT value in the fish that were fed Bisroot, were lower than the control. The complement activity ($CH_50$) tended to be significantly increased by Bisroot treatment, but not lysozyme activity. Phagocytosis and respiratory burst activities of macrophages in the head kidney were enhanced by Bisroot. Therefore, the Bisroot diet enhances the cellular immune activities were enhanced by Bisroot. Therefore, the Bisroot diet enhances the cellular immune activities of non-specific immune responses. When fish were challenged with a virulent strain of Edwardsiella tarda, the Bisroot treated fish were more resistant than the control. The present results suggest that the introduction of Bisroot into the diet of Nile tilapia could increase their resistance against bacterial infection, reduce fish mortality, and offers economic benefits.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.578-584
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• 2003

Polychlorinated biphenyls (PCBs) known as environmental contaminants in soil were analyzed by the soil pollution standard process test and the static supercritical $CO_2$ extraction mode. It was shown that the percent average recoveries of PCBs by the soil pollution standard process test were ranged in 25-35% and the corresponding standard deviations were above 10%. In contrast, the percent average recoveries of PCBs by the static supercritical $CO_2$ extraction mode were 2-2.5 times higher and standard deviations were within 7%. These results indicate that static supercritical $CO_2$ extraction mode may be a useful alternative to sample pretreatment certified by the soil pollution standard process test. The increasing supercritical $CO_2$ pressure from 1130 psi to 1996 psi at $40^{\circ}C$ enhanced the recovery of all PCB congeners from soil. However, at same Tc and Pc, the equilibrium time (5 versus 60 minutes) had no effect on the recovery of each PCB congener. Finally, similar PCB recoveries were obtained under the same extraction condition, regardless of the molecular weight and structure (coplanar versus non-coplanar) of PCB congeners.

• Polymer(Korea)
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• v.33 no.3
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• pp.224-229
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• 2009

The dielectric properties of semi-IPN poly(phenylene oxide)(PPO) blend/$BaTiO_3$(BT) composites are investigated. The composites are fabricated via melt-mixing of crosslinker and peroxide in precursor PPO composite obtained by precipitating the suspension consisted of PPO, BT and toluene into methylethyl ketone, poor solvent of PPO. The permittivity of the precursor PPO composites shows higher value than that of integral-blended PPO composites by extruder and coincides with the theoretical value calculated by logarithmic rule of mixture. The blend of PPO and cross-linked triallyl isocyanurate is most effective for lowering the permittivity and loss tangent owing to the suppression of the orientation polarization of matrix. In contrast, 4,4'-(1,3-phenylene diisopropylidene) bisaniline, which has amine unit in its structure, increases the permittivity as well as loss tangent of the composite, but it has the ability to densify the matrix resin and the interfacial adhesion between the matrix and filler to improves flexural strength and modulus.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.184-191
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• 2008

Entomopathogenic bacteria (Xenorhabdus nematophila, X. sp. and Photorhabdus temperata subsp. temperata) isolated from entomopathogenic nematodes express potent insecticidal activity in insect hemocoel. They are also known to suppress insect immune mediation by inhibiting phospholipase $A_2$, leading to host immunosuppression. This study analyzed effects of their cultured broths on inhibiting insect immunosuppression. For this, we removed all bacterial cells using $0.2\;{\mu}m$ pore sized membrane from the bacteria-cultured broth. All three sterilized cultured media, in dose-dependent manners, significantly inhibited hemocyte-spreading behavior of 5th instar larvae of Spodoptera exigua. However, they showed differential inhibitory activities among different bacterial species, in which X. nematophila showed the most potent inhibitory activity. This immunosuppressive effect was applied to increase the pathogenicity of Bacillus thuringiensis (Bt). All three bacterial cultured broths including bacterial cells significantly potentiated Bt pathogenicity against young S. exigua larvae when each of them was orally administered in a mixture of low dose of Bt. Finally, we tested the effect of oral administration of the cultured media containing the immunosuppressive compound(s) secreted by the bacteria. The membrane-sterilized cultured broths were mixed with the low dose of Bt and then orally administered to the young S. exigua. Only the cultured medium of X. nematophila showed increase of Bt pathogenicity. These results indicated that the; cultured media of the three bacteria possessed immunosuppressive factor(s), which may act to potentiate Bt toxicity to young S. exigua larvae.

• Korean journal of applied entomology
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• v.53 no.1
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• pp.15-26
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• 2014

The black soldier fly, Hermetia illucens, larvae may depend on indigenous bacteria in the intestine to feed and digest diverse food sources. To prove this hypothesis, we isolated and identified the intestinal bacteria of the black soldier fly for their digestive and antimicrobial abilities. The last instar larvae had long digestive tracts, which were about seven times longer than its body length. An individual of H. illucens larvae possessed a total of $5.0{\pm}10^6$ bacteria in the whole intestine, of which more than 98% bacteria were located in the hindgut. Three different bacterial isolates cultured on nutrient agar (NA) medium were detected in the intestine and identified as Morganella morganii, Providencia rettgeri and Bacillus halodurans by Biolog microbial identification system. Analysis of 16S rDNA sequences of the intestinal bacteria detected the additional bacteria of Proteus mirabilis, Providencia alcalifaciens, and Providencia sp. These intestinal bacteria cultured on NA medium exhibited high resistance to 4 antibiotics and inhibited growth of other microbes which are mainly plant pathogens. Also, these bacteria exhibited catalytic activities to degrade cellulose, lipid, proteins, and carbohydrates. These results suggest that H. illucens larvae possess intestinal bacteria that may play crucial roles in their digestive physiology.

• Korean journal of applied entomology
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• v.53 no.1
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• pp.73-80
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• 2014

Postharvest insect pest control is necessary for agricultural industry including domestic consumer markets and exporting products to meet quarantine issue. Especially, the organic or environmentally friendly agricultural products do not fit to the traditional chemical postharvest treatments mostly using methyl bromide. As an alternative, a physical treatment called CATTS (controlled atmosphere and temperature treatment) has been developed to control various insect and mite pests on apple and several stone fruits. This study was designed to determine the CATTS conditions to control the oriental fruit moth, Grapholita molesta, which is restricted in exporting the infested apples. To apply CATTS on this insect pest, the most heat-tolerant stage was determined. Among the immature stages locating on the fruits, the fifth instar larvae were the most tolerant to $44^{\circ}C$ for 20 min. The ramping rate (the time to increase chamber temperature from $25^{\circ}C$ to $46^{\circ}C$) was positively correlated with the CATTS efficiency under 15% $CO_2$ and 1% $O_2$. After the ramping step, the duration of CATTS was positively correlated with CATTS efficiency. In addition, the CATTS efficiency was highly dependent on the fruit internal temperature at $44^{\circ}C$. From all these parameters, we developed a standard protocol yielding 100% control efficiency of CATTS against apples infested by 4,378 larvae including 2,104 fifth instar individuals.