• Elastomers and Composites
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• v.49 no.1
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• pp.59-65
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• 2014

In this study, in order to complete curing reaction of the molding compound comprising an epoxy/anhydride at $71^{\circ}C$ for 40 hours, metal coordination complexes such as cobalt (II) acetylacetonate, potassium acetylacetonate, iron (III) acetylacetonate and chromium (III) octoate as a catalyst were applied to the epoxy/anhydride compounds respectively. The weight ratio of an epoxy part/an anhydride part was adjusted to improve the mechanical properties of the molding compound. According to the experimental results, an epoxy/anhydride compound containing chromium (III) octoate showed a high conversion at $71^{\circ}C$ for 40 hours as well as a proper processability at room temperature among the several metal coordination complexes. For the mechanical properties of the cured epoxy/anhydride compound, the compounds containing weight ratio from 0.9/1 to 0.5/1 of the epoxy part/anhydride part with chromium (III) octoate showed the high flexural strength, and higher compressive strength was shown with increasing of the hardener part.

• Journal of the Korean Chemical Society
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• v.38 no.5
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• pp.339-344
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• 1994

The crystal structure of a methanol sorption complex of dehydrated partially Co(II)-exchanged zeolite A, $Co_4Na_4-A{\cdot}6.5CH_3OH$ (a = 12.169(1) $\AA)$, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm$\bar3$m at $21(1)^{\circ}C. $Co_4Na_4$-A was dehydrated at $360^{\circ}C\;and\;2{\times}10^{-6}$ torr for 2 days, followed by exposure to about 104 torr of methanol vapor at $22(1)^{\circ}C$ for 1 hr. The structure was refined to final error indices, $R_1$ = 0.061 and $R_2$ = 0.060 with 147 reflections, for which I > $3\sigma(I).$ In this structure, four $Co^{2+}$ ions and 1.5 $Na^+$ ions per unit cell lie at 6-ring positions: the $Na^+$ ions are recessed 0.44 $\AA$ into the sodalite unit and the Co(II) ions extend ca. 0.55 $\AA$ into the large cavity. 2.5 $Na^+$ ions lie in an 8-oxygen ring plane. The 6.5 methanol molecules are sorbed per unit cell. The 6.5 methanol oxygens, all in the large cavity, associate with the 4 $Co^{2+}$ ions and 2.5 $Na^+$ ions.

• Korean Journal of Microbiology
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• v.5 no.2
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• pp.69-78
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• 1967

Kim, Jong Hyup, (Div. of Biology, Atomic Energy Research Institute.) Studies on the Cellular Metabolism in Microorganisms as influenced by Gamma-irradiation(II). On respiration rate and dehydrogenase activity of yeast cells irradiated by gamma ray from cobalt-60. 1. Oxygen uptake rate of the gamma irraiated yeast cells had been measured with Warburg's manometer, and the $O_{2}$-uptake was compared with those of normal cells. The rate of endogetious respiration increases in its $O_2$-uptake at 150, 000 rentgen dose, and at higher rentoen doses it was decreased. Exogenous respiration begin to decrease in its O_2$-uptake at 5, 000r. doses of irradiation, further decrease with increasing of doses unproportionally. 2. It appears that plasma-membrane and nuclear membrane of yeast cells have changed and denatured by gamma-irradiation, as exogenous respiration of glucose had been decreased at a dose of 200, 000r's irradiation. 3. The activity of glucose, alcoholic, lactic, succinic and glutamic deliydrogenase (G.D.H., A.D.H., L.D.H., S.D.11., and GL.D.H.) in the gamma irradaited cells had been assayed by T.T.C.(Triphenyl tetrazolium chloride) method and spectrophotometry, the obtained results were compared with those of normal cells. 4. At a dose of and 10, 000 rentgens' irradiation of gamma ray, the activty of each debydrogenase (G.D.H., A.D.H., L.D.H., ) shows a sharp and highest peak in optical absorbalicy, but each abtivity of S.D.H and Gl.D.H shows its' maximum peak at a dose of 30, 000r. 5. The curve of each dehydrogenase activity was found to be rhythmical according to dose-rate of gamma irradiation. 6. Comparing with activity of debydrogenase each other, the maximum peak in optical absorbency can be arranged according to order as follows; glucose > alcoholoic > lactic > glutamic > succinic, this order is identical to the order of breakdown utility in respiration of normal yeast cells. 7. The activity of dehydrogenase experimented exhibit a resistance against gamma irradiation at lethal dose of cells, and the activity of dehydrogenase are found to be much resistant than those of respiratory system. We may assume that the membrane substrate of mitochondria or cytoplasm had been destructed by gamma-irradiation much more than that of dehydronase system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.33-40
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• 2006

The characteristics of the aluminum waste melting and the distribution of the radioactive nuclides have been investigated for the estimation on the volume reduction and the decontamination of the aluminum wastes from the decommissioning of the TRIGA MARK it and III research reactors at the Korea Atomic Energy Research Institute(KAERI). The aluminum wastes were melted with the use of the fluxes such as flux $A:NaCl-KCl-Na_3AlF_6$, flux B:NaCl-NaF-KF, flux $C:CaF_2$, and flux $D:LiF-KCl-BaCl_2$ in the DC graphite arc furnace. For the assessment of the distribution of the radioactive nuclides during the melting of the aluminum, the aluminum materials were contaminated by the surrogate nuclides such as cobalt(Co), cesium(Cs) and strontium(Sr). The fluidity of aluminum melt was increased with the addition of the fluxes, which has slight difference according to the type of fluxes. The formation of the slag during the aluminum melting added the flux type C and D was larger than that with the flux A and B. The rate of the slag formation linearly increased with increasing the flux concentration. The results of the XRD analysis showed that the surrogate nuclide was transferred to the slag, which can be easily separated from the melt and then they combined with aluminum oxide to form a more stable compound. The distribution ratio of cobalt in ingot to that in slag was more than 40% at all types of fluxes. Since vapor pressures of cesium and strontium were higher than those that of the host metals at the melting temperature, their removal efficiency from the ingot phase to the slag and the dust phase was by up to 98%.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.606-612
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• 2018

The enzyme xylose isomerase (E.C. 5.3.1.5, XI) is responsible for the conversion of an aldose to ketose, especially xylose to xylulose. Owing to the ability of XI to isomerize glucose to fructose, this enzyme is used in the food industry to prepare high-fructose corn syrup. Therefore, we studied the characteristics of XI from Anoxybacillus kamchatkensis G10, a thermophilic bacterium. First, the gene coding for XI (xylA) was inserted into the pET-21a(+) expression vector and the construct was transformed into the Escherichia coli competent cell BL21 (DE3). The expression of recombinant XI was induced in the absence of isopropyl-thio-${\beta}$-galactopyranoside and purified using Ni-NTA affinity chromatography. The optimum temperature of recombinant XI was $80^{\circ}C$ and measurement of the heat stability indicated that 55% of residual activity was maintained after 2 h incubation at $60^{\circ}C$. The optimum pH was found to be 7.5 in sodium phosphate buffer. Magnesium, manganese, and cobalt ions were found to increase the enzyme activity; manganese was the most effective. Additionally, recombinant XI was resistant to the presence of $Ca^{2+}$ and $Zn^{2+}$ ions. The kinetic properties, $K_m$ and $V_{max}$, were calculated as 81.44 mM and $2.237{\mu}mol/min/mg$, respectively. Through redundancy analysis, XI of A. kamchatkensis G10 was classified into a family containing type II XIs produced by the genera Geobacillus, Bacillus, and Thermotoga. These results suggested that the thermostable nature of XI of A. kamchatkensis G10 may be advantageous in industrial applications and food processing.

• Radiation Oncology Journal
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• v.8 no.2
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• pp.231-239
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• 1990

From May 1979 through December 1981 a total of 524 patients with carcinoma of the uterine cervix were treated by radiation therapy with curative intent. Among the 524 patients, 350 were treated with a high-dose-rate (HDR), remote-controlled, afterloading intracavitary irradiation (ICR) system using a cobalt source (Ralstron), and 168 patients received a low-dose-rate (LDR) ICR using a radium source. External beam irradiation with a total dose of 40-50 Gy to the whole pelvis followed by intracavitary irradiation with a total dose of 30-39 Gy in 10-13 fractions to point A was the treatment protocol. ICR was given three times a week with a dose of 3 Gy per fraction. Five-year actuarial survival rates in the HDR-ICR group were $77.6{\%}$ in stage IB (N=20), $68.2{\%}$ in stage II (N=182), and $50.9{\%}$ in stage III (N=148). In LDR-ICR group, 5-year survival rates were $87.5{\%}$ in stage IB (N=22), $66.3{\%}$ in stage II (N=91), and $55.4{\%}$ in stage III (N=52). Survival rates showed a statistically significant difference by stage, but there was no significant difference between the two ICR groups. Late bowel complications after radiotherapy were noted in $3.7{\%}$ of the HDR-ICR group and $8.4{\%}$ of the LDR-ICR group. There was no severe complication requiring surgical management. The incidence of bladder complications was $1.4{\%}$ in the HDR-ICR group and $2.4{\%}$ in the LDR-ICR group. The application of HDR-ICR was technically simple and easily performed on an outpatient basis without anesthesia, and the patients tolerated it very well. Radiation exposure to personnel was virtually nil in contrast to that of LDR-ICR. Within a given period of time, more patients can be treated with HDR-ICR because of the short treatment time. Therefore, the HDR-ICR system is highly recommended for a cancer center, particularly one with a large number of patients to be treated. In order to achieve an improved outcome, however, the optimum dose-fractionation schedule of HDR-ICR and optimum combination of intracavitary irradiation with external beam irradiation should be determined through an extensive protocol.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.213-225
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• 1989

An analysis has been made of two hundred seven patients who were treated at the department of Radiation Oncology of Korea University Hospital for lung cancer from January 1981 through December 1986. There were 137 patients of nonsmall cell carcinoma (137/207, 66%), 26 patients of small cell carcinoma (26/207, 12.5%) and 44 patients of unproven histology. By aims of treatment, there were 104 patients (104/207, 50%) treated for cure, 89 patients (89/207, 42.9%) for palliation and 14 patients treated postoperatively. In 22 out of 207 patients, chemotherapy was done with radiotherapy, 12 of which were patients with small cell carcinoma. Stage II patients were 49 (49/207, 23.6%), stage III patients were 157 (157/207, 75.8%) and one patient had an occult cancer The tumor was initial Iy measured by CAT scan and chest X-rays in the 165 (165/207, 79.7%) patients, among which 117 patients had tumor diameter more than 5cm and 48 patients less than 5cm. Radiation therapy was given with Cobalt 60 teletherapy unit and the treatment volume encompassed primary tumor and the mediastinum. For curative aim, daily tumor dose of 180 cGy was given up to the range of 5,400~6,120cGy/30~34F/6~7 week period and for palliative aim, daily tumor dose of 300 cGy was given up to the range of 3,600~4,500 cGy/12~15F/2~3 week period. Postoperatively, mediastinum was treated for total dose of 5,040 cGy/28F/5.5 week period. 123 patients (123/207, 59%) were followed up after completion of radiotherapy for 14 months to 7 years. Local tumor response to the irradiation was measured by chest X-ray taken at one month follow up and was evaluated for response rate, if they were regressed more than 50% or less than 50% of the initial tumor size. The treatment results were as follows; 1. The median survival time was 8.5 months and survival rates for 1 year, 2 year and 5 year was 25%, 3.5% and 1% of nonsmall cell lung ca of 74 evaluable patients. 2. More than 50% of local tumor response rate was obtained in about half of overall cases; 90.5% for small cell ca, 50% for squamous cell ca, 25% for adenoca and 57% for large cell ca. 3. Response rate more than 50% was seen in the 50% of the patient group with tumor diameter more than 5cm and in the 55% of those with tumor diameter less than 5cm. 4. By total raidation dose given, patient group which was given 5,400~6,120 cGy equivalent dose or higher showed tumor response rate more than 50% in 53% of the patients, whereas the group with dose less than 5,400cGy equivalent, in 25% of the patients. 5. Survival rate for 6 month, 1 year and 2 year was compared between the group of local tumor response rate more than 50% vs. group with response rate less than 50%; 74% vs. 43%, 33% vs, 23%, 10% vs. 1%, respectively. 6. Local failure was seen in 21%(44/207) of the patients, which occured mostly within 15 months after completion of radiation therapy. Distant metastases were seen in 49.7%(103/207) of the patients, of which 43 cases were found before initiation of radiotherapy. The most common metastatic sites were bone and brain. In this sutdy, 1 year,2 year and S year survival rates were somewhat poor compared to the other studies. It mainly seems to be due to the poor general status of the patients and the far-advanced stage of the disease. In nonsmall cell cancer patients who had limited local disease and had small primary tumor size, we observed better local response. In addition, dose higher than 6,000 cGy group showed better tumor control than lower dose group. Survival rate was better for the local control group. For imporvement of local control of the lung cancer and hence, the survival of the patients with lung cancer, proper radical radiotherapy with high dose for localized disease is needed. New modality of treatment such as high LET beam in radiation therapy or drugs for the advanced disease as well as early diagnosis is also needed.