• Microbiology and Biotechnology Letters
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• v.9 no.3
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• pp.159-164
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• 1981

Reinforced Calcium-alginate gel entrappment method for enzyme immobilization is described with an example of penicillin amidase from Bacillus megaterium KFCC 10029, a partially constitutive mutant of B. megaterium ATCC 14945. Penicillin amidase recovered from the fermentation broth by adsorption on celite is mixed with alginate and gelatin solution, and cast into a pellet or noodle form by coagulation in calcium salt solution followed by crosslinking with glutaraldehyde. Optimum pH and temperature of the immobilized enzyme preparation were 8.0 and 6$0^{\circ}C$, respectively. Kinetic constants such as Km value and the inhibition constant of 6-APA and phenylacetic acid were 2.6 mM, 7.4 mM and 21.2 mM, respectively. The enzyme leakage from the adsorbent during operation was successfully prevented owing to the increase of physical strength of gel coat. The half lives in a column reactor were 6 and 30 days at the respective temperature of 4$0^{\circ}C$ and 3$0^{\circ}C$, which were the 6-8 fold increased values as compared with those of without entrappment. The results highly recommended the use of reinforced Calcium-alginate gel entrappment method for the enhancement of physical strength and the operational stability of alginate gel entrapped enzyme.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.67-74
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• 2017

PURPOSES : In this study, a three-dimensional nonlinear finite element analysis (FEA) model for airport concrete pavement was developed using the commercial program ABAQUS. Users can select an analysis method and set the range of input parameters to reflect actual conditions such as environmental loading. METHODS : The geometrical shape of the FEA model was chosen by considering the concrete pavement located in the third-stage construction site of Incheon International Airport. Incompatible eight-node elements were used for the FEA model. Laboratory test results for the concrete specimens fabricated at the construction site were used as material properties of the concrete slab. The material properties of the cement-treated base suggested by the Federal Aviation Administration(FAA) manual were used as those of the lean concrete subbase. In addition, preceding studies and pavement evaluation reports of Incheon International Airport were referred for the material properties of asphalt base and subgrade. The kinetic friction coefficient between the concrete slab and asphalt base acquired from a preceding study was used for the friction coefficient between the layers. A nonlinear temperature gradient according to slab depth was used as an input parameter of environmental loading, and a quasistatic method was used to analyze traffic loading. The average load transfer efficiency obtained from an Heavy falling Weight Deflectomete(HWD) test was converted to a spring constant between adjacent slabs to be used as an input parameter. The reliability of the FEA model developed in this study was verified by comparing its analysis results to those of the FEAFAA model. RESULTS : A series of analyses were performed for environmental loading, traffic loading, and combined loading by using both the model developed in this study and the FEAFAA model under the same conditions. The stresses of the concrete slab obtained by both analysis models were almost the same. An HWD test was simulated and analyzed using the FEA model developed in this study. As a result, the actual deflections at the center, mid-edge, and corner of the slab caused by the HWD loading were similar to those obtained by the analysis. CONCLUSIONS : The FEA model developed in this study was judged to be utilized sufficiently in the prediction of behavior of airport concrete pavement.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.76-82
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• 1986

A laboratory experiment was conducted to find out the denitrification rate upon the levels of nitrogen and source of organic matter in submerged sandy and sandy loam soil. The results obtained were sumarized as follows; 1. Evolution of nitrous oxide was increased at 1st and 10 days after incubation. And dinitrogen was increased at 1st and 30 days after incubation. Applications of green manure was enhanced the evolution of nitrous oxide ($N_2O$) and dinitrogen ($N_2$). 2. The cumulative denitrification rates at 50 days was high in Gyuam sandy loam soil (O-M: 1.52%) than that of Hamchang sandy soil (O-M: 3.81%). On the other hand, the cumulative emission of dinitrogen was high in Gyuam sandy loam soil while nitrous oxide was high in Hamchang sandy soil. The total mount of denitrification rate was high in order of green manure > rice straw > compost > control soil. 3. Increases of fertilizer nitrogen was enhanced the rate of emission of dinitrogen and nitrous oxide during the incubation time. 4. According to Michaelis-Menten kinetic equation, denitrification rates and reaction efficiency were remarkably increased by application of readily decomposable organic matter with in higher organic matter content of soil. 5. The negative relationship was observed between the evolution of dinitrogen and carbon ($CO_2+CH_4$) while the nitrous oxide with carbon was positive. 6. Under the this experiment conditions 1 mg of carbon was required for production of 4 mg N as $N_2O$ and 3 mg of N as $N_2$, respectively.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.205-217
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• 1993

In order to evalute the effects of radiation on mammalian neuronal system, we have examined the effect of gamma-ray radiation on the monoamine oxidase (MAO) activity in monoaminergic neurons. Following the whole body irradiation, MAO activity in the rat brain was measured as well as in the liver for the comparative studies between the neuronal and nonneuronal system. The effects of some radiation protectors and sensitizers were also examined in addition to the $O_2$ effect. The results can be summarized as follows. 1) The MAO activity of rat brain was minimally affected by the radiation dose up to 1,700 cGy Radiation dose above 2,500 cGy inhibited the brain MAO activity by no less than $l0\%.$ MAO-A form was found to be particularly sensitive to radiation. The liver MAO was somewhat inhibited (by about $5\%$) but hardly dependent on the dose of radiation. 2) The inhibitory effect on the brain was initiated immediately by the radiation dose of 2,500 cGy. On the contrary, for the liver, the inhibitory effect became apparent only 2 days after irradiation. 3) Two days after a dose of 2,500 cGy, Vmax and Km of the brain mitochondrial MAO decreased. For liver, Vmax decreased while Km increased, which indicates the kinetic patterns for the neuronal and nonneruronal systems are not affected similarly by radiation. 4) The effect of several known radiation protectors and sensitizers on MAO activity was tested ut no definite results were obtained. The level of -SH group increased in some degree upon radiation but not by the compounds. 5) MAO activity was not affected by $O_2$ concentration, while an elevated level of lipid peroxidase was found under the same condition. The results described here indicate that characteristics of MAO, one of the most important central nervous system enzymes, are liable to radiation, which is partially differentiated from the liver MAO. Also indicated are that the -SH groups are hardly related to the effect of radiation but the production of the lipid peroxide seems to be somewhat correlated to the effect of radiation.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.219-225
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• 1993

The evaluation of radiation-induced DNA double strand breaks (DSB) was made following irradiation of human lymphocytes, murine lymphocytes and EL-4 leukemia cells over a wide dose range of $^{60}Co\;{gamma}-rays.$ In lipopolysaccharide (LPS) or phytohemagglutinin (PHA)-stimulated murine lymphocytes, the slopes of the stand scission factor (SSF) revealed that lymphocytes with LPS increased DNA DSB formation by a factor of 1.432 (p<0.005). Furthermore, strand break production was relatively inefficient in the T lymphocytes compared to the B lymuhocytes. And EL-4 leukemia cells were found to form significantly more DNA DSB to a greater extent than normal lymphocytes (p<0.005). The in vitro studies of the intrinsic radiosensitivity between human lymphocytes and murine lymphocytes showed similar phasic kinetics. However, murine lymphocytes were lower in DNA DSB formation and higher in the relative radiation dose of 10 percent DNA strand breaks at 3.5 hours following ${gamma}-irradiation$ than human lymphocytes. Though it is difficult to interpret these results, these differences may be result from environmental and genetic factors. From our data, if complementary explanations for this difference will be proposed, the differences in the dose-effect relationship for the induction of DSB between humans and mice must be related to interspecies variations in the physiological condition of the peripheral blood in vitro and not to differences in the intrinsic radiation sensitivity of the lymphocytes. These results can be estimated on the basis of dose-effect correlation enabling the interpretation of clinical response and the radiobiological parameters of cytometrical assessment.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.118-122
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• 1995

Escherichia Coli ornithine transcarbamylase is the enzyme which catalyzes the L-citrulline biosynthesis from L-ornithine and carbamyl phosphate. To facilitate the purification of enzyme which will be used for many biochemical studies such as structure and function relationships and catalytic mechanisms, the cloning and expression of E. coli argI gene for ornithine transcarbamylase was conducted. argI was amplified from genomic DNA of E. coli strain of $DH5{\alpha}$, by polymerization chain reaction (PCR) method. The amplified argI gene was ligated to the prokaryotic expression vector pKK223-3 and used for transformation of E. coli TB2 which was deficient of ornithine transcarbamylase. The over-produced enzyme by the tnansformant was purified by ammonium sulfate fractionation, heat denaturation and affinity chromatography. The result of SDS denaturation gel electrophoresis for the purified enzyme showed a single band of about 38 kDa of ornithine transcarbamylase. Kinetic data for the expressed enzyme gave almost the s?????? values as those of the wild type enzyme. The $k_{cat}$, of the enzyme was $1.0{\times}10^5min^{-1}$, and $K_ms$ for ornithine and carbamyl phosphate were 0.35 mM and 0.06 mM, respectively.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.151-156
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• 1995

Single-drop splash/detachment studies and multiple-drop splash/detachment experiments were carried out to measure detachment by single and multiple drops. A raindrop tower 7.0 m in height was used to study soil splash by single drop raindrop impact over time on repacked soil samples in containers 76.2 mm in diameter. The waterdrop diameter and kinetic energy were 4.1 mm and $1.22{\times}10^{-3}$ J $drop^{-1}$, respectively. The samples consisted of five agricultural topsoils sieved to <2 mm, varying from sandy loam to clay loam in texture. The average weight of splashed soil particles after 75 drops did not show any significant difference between the five soils. The average weight of particles splashed by the first 15 drops showed that the sandy Pelham soil splashed to a greater degree than the others, and was therefore more detachable (p=0.05) than the other soils. The average weight of particles splashed by the last 15 drops also showed that the Pelham soil was the most detachable, with Cecil, Appling, Dyke, and Worsham soils being progressively less detachable. The effect of multiple drops on detachment was studied under a nozzle-type rainfall simulator at 74.9 mm $h^{-1}$ intensity for 85 min using the same soils as the single drop experiments. The total soil splash value for 85 min on Appling, Cecil, Dyke, Pelham, and Worsham soils were 6121, 6206, 4183, 5160, and 3247 g $m^{-2}$, respectively. There were no obvious relationships between soil loss measured from the different experiments.

• Economic and Environmental Geology
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• v.42 no.2
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• pp.95-105
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• 2009

Systematic studies are performed for arsenic adsorption on synthesized lepidocrocite. The synthesized lepidocrocite with high surface area of $94.8\;g/m^2$ has shown that the point of zero charge(PZC) is 6.57 determined by potentiometric titration, suggestive of high capacity of arsenic removal. Results show that arsenite[As(III)] uptake by synthesized lepidocrocite is greater than that of arsenate[As(V)] at pH $2{\sim}12$, indicating that the lepidocrocite has high affinity toward arsenite rather than arsenate. Adsorption of arsenate decreases with increasing pH from 2 to 12, whereas arsenite sorption increases until pH 8.0, and then decreases dramatically with increasing pH, suggesting that changes in surface charge of the lepidocrocite as a function of pH playa important role in aresinc uptake by the lepidocrocite. Upon kinetic experiments, our results demonstrate that both arsenite and arsenate sorption on the lepidocrocite increases rapidly for the first 4 h followed by little changes during the duration of the experiment, showing that adsorption plays a key role in aresenic uptake by the lepidocrocite. Our results also show that power function and elovich models are the best fit for the adsorption kinetics of arsenite and aesenate on the lepidocrocite.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1156-1163
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• 1996

This study is related to the investigation of the characteristics of quaternary ammonium salt catalyst on the addition reaction of carbon dioxide and glycidyl methacrylate(GMA) to form(2-oxo-1,3-dioxolane-4-yl)methacrylate(DOMA). Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed a higher catalytic activity. Mixed catalysts of NaI and 18-crown-6 showed a good yield of DOMA, but when they are used alone, they showed no catalytic activity. The DOMA monomer was obtained in low polar solvents, while poly(DOMA) could be directly synthesized in aprotic dipolar solvents. Kinetic studies carried out by measuring $CO_2$ pressure in a high pressure batch reactor showed that the reaction rate was first order to the concentration of GMA and $CO_2$ respectively. The rate constant(k) was 0.56L/mol hr and Henry's constant(H') of $CO_2$ in diglyme at $80^{\circ}C$ was $6.5{\times}10^{-4}mol/L{\cdot}kPa$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.2
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• pp.119-127
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• 1986

The rheological properties of mayonnaise were studied with cylindrindrical viscometer. It was observed that mayonnaise showed pseudoplastic behavior, yield stress and time dependent characteristics. In the initial period of shear time, the decay of viscosity of mayonnaise was followed by a second-order kinetic equation. The influence of temperature on viscosity could be described by Arrhenius equation. The apparent viscosity of mayonnaise markedly increased with an rise in the concentration of egg yolk; and the emulsion was most stable at the concentration of 12%. At the concentration of $65{\sim}75%$ oil, the apparent viscosity was increased; the maximum value was reached at 75% oil, and above 75% oil, the remarkable decreased was observed. The size of oil drops was decreased with an increase in oil concentration of 75% oil. The apparent viscosity of mayonnaise was increased with an rise in water contents, while being decreased with one in the concentration of vinegar.