• Radiation Oncology Journal
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• v.4 no.1
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• pp.1-13
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• 1986

In order to clarify the effect of radiation on the mouse jejunal crypt cells by combined administration of administration and radiation and also to evaluate the enhancing effect of adriamycin, the authors performed this study by delivering single irradiation of 1,000 to 1,600 rad to the whole abdomen of mice by cobalt-60 teletherapy unit. In combination with adriyamycin treatment groups, the drug was administered as single dose of 10 mg/kg either 2 hours before or 4 hours after graded single dose,900 to 1,400 rad, of irradiation. The authors studied the quantitative changes of intestinal crypt cells by microcolony survival assay technique and the morphological changes of small intestinal villi by scanning electron microscope in mice following to combined therapy with adriamycin and irradiation, The average number of jejunal crypts per circumference was $130{\pm}16$ in control group. The mean lethal dose(Do) of each irradiation alone and combined therapy groups 2 hours before and 4 hours after irradiation, were 160, 170, and 170 rad in cell survival curves, respectively. The dose effect factor(DEF) of adriamycin in each groups of pre-irradiation and post-irradiation were 1.19 and 1.26, respectively. The conical shaped villi were noted on 1,200 rad in irradiation alone group and 1,000 rad in combined groups. For the proper clinical application we must be careful of the radiation injury to small bowel when the anticancer chemotherapy and radiation therapy to the abdomen and pelvic area are used as combined therapeutic modality.

• Korean Journal of Veterinary Research
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• v.13 no.1
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• pp.85-102
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• 1973

In the event a population of animals is exposed to ionizing radiation, proper disposition of animals will minimize loss to the farmer and protect the public from unwholesome meat and dairy products. Clinical response is an important factor in considering salvage of animals for food following exposure to ionizing radiation whether the dose is lethal or not. It is the purpose of this report to present the discussions of blood picture and growth of y ung growing rabbits exposed to cobalt-60 gamma-irradiation. The experimental animals were Hyrnalayan rabbits of 65 days old. The body weight for all animals of the time of irradiation was approximately 450g. The 96 rabbits used in the experiment were allotted t groups of eight. Rabbits in one group served as controls and the others were exposed to single doses of 100, 200, 300, 400, 500, 600 and 700 Roentgens (R). The exposure does rate averaged 15 R per minute. Central blood was obtained by heart puncture. Erythrocyte and leukocyte enumerations and, determinations of hemoglobin in blood and hematocrit value were made in the usual manner. Erythrocyte counts, concentrations of hemoglobin in blood, and hematocrit readings dropped to the lowest value between 1 and 4 weeks postirradiation, returning towards the control values. But recovery was not complete at the time of the last determination on 6 weeks postirradiation. There was a progressive decrease with increasing radiation does in the above values. Mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were not affected by the irradiation. After irradiation of each does the numbers of total leukocyte and the absolute numbers of various types of white cell began to decrease rapidly, and reached a minimum after 2 weeks, returning towards normal levels. But recovery was not complete at the time of the last determination on 6 weeks postirradiation. The reductions in total leukocyte and differential counts as the radiation does increases were apparent. Relative neutrophilia was observed in each irradiated group because of more expense of lymphocytes after irradiation. Growth rate of the rabbits was not affected by 100 R of whloe-body irradiation, while rabbits irradiated with 200, 300, 400 and 500 R showed marked depression of growth rate. As the radiation does increases, a depression of growth rate was apparent. The rabbits exposed to 600 and 700 R ceased from growing and recovery was not recognized during the experimental period.

• Resources Recycling
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• v.25 no.1
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• pp.60-67
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• 2016

A scale-up test with a continuous solvent extraction and electro-winning system was carried out to separate and recover copper from a synthetic sulfuric acid solution (Cu 10.5 g/L, Co 2.0 g/L, Ni 15.0 g/L, Fe 0.2 g/L). The solution was introduced into mixer-settlers with four stages of extraction and two stages of stripping for continuous countercurrent solvent extraction to separate copper from nickel and cobalt. The loading was carried out using 40% LIX 84-I(v/v) as extractant with a phase ratio of A : O = 1 : 1. Meanwhile, the stripping was undertaken at a phase ratio of A : O = 1 : 1.5 using depleted electrolyte containing 35.0 g/L Cu and 180 g/L $H_2SO_4$ as stripping solution. The extraction and stripping efficiencies were found to be 96.7% and 91.0%, respectively. The copper composition of the stripped solution (pregnant electrolyte) was 50.0 g/L Cu with impurities of 25 ppm nickel, 5 ppm cobalt and 3 ppm iron. In the electro-winning process, copper metal of 99.833 purity was yielded with current efficiency of 98.9% and current density of $1.50A/dm^2$.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.365-370
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• 2019

In this study, effects of the ultrasonic irradiation during the reaction process were investigated for the enantioselective kinetic resolution (EKR) reaction of racemic epoxides in the presence of chiral cobalt salen catalysts, as compared to that of using the conventional mechanical stirring. In order to compare catalytic activities, the chiral cobalt salen complexes having $AlCl_3-$, $BF_3-$ and nitrobenzenesulfonic acid (NBSA) were synthesized and used as catalysts, and then three kinds of the racemic epoxides such as ephichlorohydrine (ECH), epoxy phenoxypropane (EPP) and propylene oxide (PO) were used as reactants. In addition, EKR reactions have been performed using the water and methanol as nucleophiles, respectively. The unique contribution of ultrasonic irradiation as a powerful mixing medium was evaluated in this study to improve the kinetics in comparison to the conventional mechanical agitation during EKR reactions. The reaction time to obtain the highest 99 ee% became shorten more than that of above 60%, when the ultrasonic irradiation was used. This result may be interpreted by the cavitation effect of ultrasound in the solution, generating a powerful shear force for the very violent mixing.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.113-119
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• 1989

In recent years there has been a growing interest in total body, hemibody, total lymphoid irradiation. For refractory leukemia or lymphoma patients, various techniques and dose regimens were introduced, including high dose total body irradiation for destruction of leukemic or bone marrow cells and immunosuppression prior to bone marrow transplantation, and low dose total body irradiation for treatment of lymphocytic leukemia or lymphomas. Accurate provision for specified dose and the desired homogeneity are essential before clinical total body irradiation. Purposes of this paper are to discuss calibrating Cobalt Unit in 3m distance using Rando Phantom, to compare calculated dose, calibrated dose, and compensating filters for homogeneous dose distribution in the head and neck, the lung, and the pelvis. Results were following. 1. Measured dose on the lung was 6% higher than on the abdomen. Measured dose on the head (10%) and neck (18%) were higher than the abdomen because of thinness. Pelvic dose was measured 12% less than the abdomen. Those data suggest that compensating filter was essential. 2. Measured dose according to distance was 3% less than calculated dose which suggest that all doses in clinical use should be compared with calculated dose for minimizing error.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.335-341
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• 2017

Cyclotron is a device that accelerates positrons or neutrons, and is used as a facility for making radioactive drugs having short half-lives. Such radioactive drugs are used for positron emission tomography (PET), which is a medical apparatus. In order to make radioactive drugs from a cyclotron, a nuclear reaction must occur between accelerated positrons and a target. After the reaction, unncessary neutrons are produced. In the present study, radioactivation generated from the collisions between the concrete shielding wall and the positrons and neutrons produced from the cyclotron is investigated. We tracked radioactivated radioactive isotopes by conducting experiments using FLUKA, a type of Monte Carlo simulation. The properties of the concrete shielding wall were comparatively analyzed using materials containing impurities at ppm level and materials that do not contain impurities. The generated radioactivated nuclear species were comparatively analyzed based on the exposure dose affecting human body as a criterion, through RESRAD-Build. The results of experiments showed that the material containing impurities produced a total of 14 radioactive isotopes, and $^{60}Co$(72.50%), $^{134}Cs$(16.75%), $^{54}Mn$(5.60%), $^{152}Eu$(4.08%), $^{154}Eu$(1.07%) accounted for 99.9% of the total dose according to the analysis having the exposure dose affecting human body as criterion. The $^{60}Co$ nuclear species showed the greatest risk of radiation exposure. The material that did not contain impurities produced a total of five nuclear species. Among the five nuclear species, 54Mn accounted for 99.9% of the exposure dose. There is a possibility that Cobalt can be generated by inducive nuclear reaction of positrons through the radioactivation process of $^{56}Fe$ instead of impurities. However, there was no radioactivation because only few positrons reached the concrete wall. The results of comparative analysis on exposure dose with respect to the presence of impurities indicated that the presence of impurities caused approximately 98% higher exposure dose. From this result, the main cause of radioactivation was identified as the small ppm-level amount of impurities.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.9-16
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• 2005

This study was carried out to investigate the characteristics of extracellular cellulase and xylanase from 4 selected different species, such as enzyme activity and stability by pH, temperature and metal ions, for application into enzymatic deinking system. The optimal temperature and pH for enzyme activity of Bacillus pumilus I, B. subtilis I, B. pumilus II and B. subtilis II were mainly $40{\sim}60^{\circ}C$ and pH $6.0{\sim}7.0$, respectively. Certain metal ions, calcium and cobalt, elevated enzyme activity, even though there were different results of enzyme activities based on various metal ions in 4 different species. With these results we suggest that enzymatic deinking system should be proceed at $50^{\circ}C$ with neutral pH condition.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.953-959
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• 2001

Homogeneous spherical W-Co salt powders were made by spray drying of aqueous solution of ammonium $metatungstate(NH_4)_6(H_2W_{12}O_{40}){\cdot}4H_2O,\; AMT)$ and cobalt nitrate $hexahydrate(Co(NO_3)_2{\cdot}6H_2O)$. The thermal decomposition process of spray dried W-Co salt powders was studied by TG, XRD, SEM, TEM and FT-IR. Spray dried W-Co salt powders were calcined for 1 hour in the temperature from$ 350^{\circ}C$ to $800^{\circ}C$ in atmosphere of air. At the temperatures over $600^{\circ}C$, spherical $CoWO_4/WO_3$ composite oxide powders were obtained. The primary particle size of W/Co composite oxide powders increased with increasing thermal decomposition temperature due to the particle growth. The observed crystallite size by TEM was in the range of 60nm and that of $CoWO_4$ calculated by Scherrer's formula at $800^{\circ}C$ was smaller than 55nm. The crystallite site was identified by XRD and TEM.

• Journal of Powder Materials
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• v.10 no.2
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• pp.108-117
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• 2003

WC and dense WC-10 vol%Co materials with grain size of~1${\mu}m$ were synthesized by high-frequency induction heated combustion synthesis (HFIHCS) method in one step from elemental powders of W, C and Co within several minutes. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. In the absence of cobalt additive, WC can be formed, but its relative density was low (about 73%) under simultaneous application of a 60 MPa pressure and the induced current. However, in the presence of 10 vol.%Co, the relative density increased to 99% under the same experimental condition. The percentages of the total shrinkage occurring before and during the synthesis reaction of WC-10 vol.%Co were 5% and 51%, respectively. The fracture toughness and hardness values of WC-10 vol.%Co were 10 MPa . m$^{1/2}$ and 1840 kg/$mm^2$, respectively.

• The Journal of the Korean Society for Microbiology
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• v.6 no.1
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• pp.15-20
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• 1971

A vaccine was prepared by $10^6$ r cobalt-60 irradiation of lyophilized virulent Brucella melitensis and tested in mice for immunogenic activity against a lethal challenge dose of the homologous strain. The vaccine(GIV) produced a high degree of immunity in mice, and comparative studies demonstrated it to be superior to vaccines prepared by heat or by chemical(ether, formalin, or phenol) treatment. Living vaccines, Brucella abortus. strain 19 and an R-form of Brucella melitensis were lethal for mice in larger doses. A comparison of seven adjuvant mixtures for use with the GIV showed no statistically significant difference, but. Freund's complete adjuvant and a mixture of aluminum-potassium sulfate and pectin appeared to enhance the activity of the GIV.