• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.106-109
• /
• 2012

Purpose : The KOTRON-13 cyclotron was developed and installed in regional cyclotron centers to produce short-lifetime medical radioisotopes. However, this cyclotron has limited capacity to produce $^{11}C$ so far. In present study, we developed an effective $^{11}C$ target system combining with fluorine-18 target and applied to the production of various $^{11}C$ radiopharmaceuticals. Materials and Methods : To develop the optimal $^{11}C$ target system and effective its cooling system, we designed the $^{11}C$ target system by Stopping and Range of Ions in Matter (SRIM) simulation program and considered the cavity pressure during irradiation at target grid. In this investigation, we modified target materials, cavity shapes and the position of cooling system in $^{11}C$ target and then evaluated $[^{11}C]CO_2$ production at different beam currents, thickness of the target foil, oxygen content of nitrogen gas and target gas loading pressure. Also, we evaluate the production of several $^{11}C$ radiopharmaceuticals such as [$^{11}C$]PIB, [$^{11}C$]DASB, and [$^{11}C$]Clozapine. Results : $[^{11}C]CO_2$ was produced about 74 GBq for 30min irradiation at 60 ${\mu}A$ of beam current as following conditions: thickness of the target foil: 19 nm HAVAR, oxygen content of nitrogen: under 50 ppb, target gas loading pressure: 24 bar. Additionally, the cooling system was stable to produce $[^{11}C]CO_2$ at high beam current. The radiochemical yields of [$^{11}C$]PIB, [$^{11}C$]DASB, and [$^{11}C$]Clozapine showed about 26-38% with over 127 GBq/umol of specific activity. Conclusion : The carbon-11 target system in the KOTRON-13 cyclotron was successfully developed and showed stable production of $[^{11}C]CO_2$. These results showed that our $^{11}C$ target system will be compatible with other commercial system for the routine $^{11}C$ radiopharmaceuticals production in the KOTRON-13 cyclotron.

• Bulletin of the Korean Chemical Society
• /
• v.11 no.6
• /
• pp.531-534
• /
• 1990

The reaction of $Os_3(CO)_{10}(NCMe)_2$ with a tungsten alkylidyne $Cp(CO)_2W{\equiv}CTol(Cp={\eta}^5-C_5H_5,\;Tol=p-C_6H_4Me)$ produces the compound, $CpWOs_3(CO)_{11}({\mu}_3-CTol)$(1). The structure of compound 1 can be viewed as one in which the metalla-alkyne, $Cp(CO)_2W{\equiv}CTol$, is ${\mu}_3-{\eta}^2-{\bot}$ (perpendicular) bound to an $Os_3(CO)_9$ fragment. Variable-temperature $^{13}C$ NMR spectra of 1 show no evidence for the analogous rotation of the metalla-alkyne molecule as shown alkyne rotation in $Os_3(CO)_9(C_2Tol_2)$ compound. This lack of the metalla-alkyne fluxionality supports the apparent saturated nature of compound 1.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.308-311
• /
• 1999

The varistor characteristics of $ZnO-Pr_6O_11-CoO-Er_2O_3$-based ceramics were investigated. $ZnO-Pr_6O_11-CoO-Er_2O_3$-based ceramics were sintered at $1300^{\circ}C$ and $1350^{\circ}C$in the addition range 0.0~2.0mol% $Er_2O_3$, respectively. $ZnO-Pr_6O_11-CoO-Er_2O_3$-based ceramics, which are added with 0.5mol% $Er_2O_3$ at $1300^{\circ}C$ and l.Omol% $Er_2O_3$ at $1350^{\circ}C$ sintering temperature, exhibited the bestexcellent varistor characteristics, namely, the nonlinear exponent was better 52.78 at $1300^{\circ}C$ thanat 13$1350^{\circ}C$ and the leakage current was better 6.57$\mu\textrm$A at $1350^{\circ}C$ than at $1300^{\circ}C$. Consequently, it is estimated that $ZnO-Pr_6O_11-CoO-Er_2O_3$-based ceramics, which $Er_2O_3$ is added in the range 0.5~l.Omol% will begin to be used as a predominant basic composition of $PR_6O_11$-based ZnO varistors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.179-184
• /
• 2000

The I-V characteristics of $ZnO-Pr_6O_{11}-CoO-Dy_2O_3$ based varistors were investigated in the $Pr_6O_{11}/CoO$ composition ratio range of 0.5/0.5 to 1.0/1.0 and sintering temperature range of 1300 to $1350^{\circ}C$ as the basic study to develop the advanced $Pr_6O_{11}$-based ZnO varistors. All varistors except for $Pr_6O_{11}$/CoO = 0.5/1.0 exhibited the best I-V characteristics at $1350^{\circ}C$. However, the varistors with $Pr_6O_{11}$/CoO= 0.5/1.0 exhibited the best I-V characteristics at $1350^{\circ}C$. The varistors with $Pr_6O_{11}$/CoO= 0.5/1.0 of all varistors exhibited the best I-V characteristics, which the nonlinear exponent is 36.9 and the leakage current is 7.6 ${\mu}A$ Therefore, it was estimated that ZnO-$Pr_6O_{11}-CoO-Dy_2O_3$ ceramics with $Pr_6O_{11}$/CoO= 0.5/1.0 will be usefully used as varistor materials in the future.

• Korean Journal of Food Science and Technology
• /
• v.29 no.6
• /
• pp.1119-1124
• /
• 1997

This study was carried out for improvement and correction of the traditional pressure variation method (PVM) in the respiration rate measurements of fresh fruits and vegetables using a microcomputer system and a differential pressure sensor. Water vapor pressure in the container was calculated by equations for psychrometric calculations. At the beginning of experimental period water vapor pressure in the container was increased and maintained constantly in the most experimental period, but was decreased dramatically after $CO_2$ scrubbing. The percentages of water vapor pressure on total differential pressure were $33{\sim}46%$ at $1^{\circ}C$, $23{\sim}45%$ at $11^{circ}C$ and $35{\sim}53%$ at $21^{\circ}C$. The differences between the respiration rates determined by gas chromatography and corrected pressure variation method (CPVM) were $0.2{\sim}0.3\;mgCO_2kg^{-1}h^{-1}$ at $1^{\circ}C$, $0.2{\sim}2.9\;mgCO_2kg^{-1}h^{-1}$ at $11^{\circ}C$ and 1.0{\sim}9.0\;mgCO_2kg^{-1}h^{-1}$ at $21^{circ}C$, while those between gas chromatography and normal pressure variation method (PVM) were $0.8{\sim}1.2\;mgCO_2kg^{-1}h^{-1}$ at $1^{\circ}C$, $3.9{\sim}11.0\;mgCO_2kg^{-1}h^{-1}$ at $11^{\circ}C$ and $8.0{\sim}32.0\;mgCO_2kg^{-1}h^{-1}$ at $21^{circ}C$, respectively. The differences of the respiration rates with CPVM were smaller than those with PVM. CPVM, therefore, were more exact and convenient method than PVM in the measurement of respiration rate of fresh produce.

• Journal of Astronomy and Space Sciences
• /
• v.19 no.1
• /
• pp.7-18
• /
• 2002

Interstellar cabon monoxide and its isotopes were observed with the 13.7m radio telescope of the Daeduk Radio Astronomy Observatory toward Orion Molecular Cloud-1 (OMC-1). We derive the excitation temperature, optical depth, column density, and isotopic abundance ratios from the observed lines of $^{12}CO,^{13}CO,\;and\;C^{18}O$ inside of the region of $11'{\times}11'$. The optical depths of $^{13}CO$ were obtained to be 0.1~0.4, while those of $C^{18}O$ to be 0.01~0.03. The isotopic ratios $^{12}C/^{13}C$ were also estimated to be 2~60. We could not find the radial isotopic ratio $^{12}C/^{13}C$ gradient in the OMC-1.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.1
• /
• pp.39-45
• /
• 2003

The varistor properties of ZnO-Pr$_{6}$O$_{11}$-CoO-based ceramics doped with Sm$_2$O$_3$were investigated in the addition range of 0.0~2.0 mol% Sm$_2$O$_3$at sintering temperature of 130$0^{\circ}C$ and 135$0^{\circ}C$. As Sm$_2$O$_3$ content is increased, the breakdown voltage was increased in the range of 348.9~521.8 V/mm for ceramics sintered at 130$0^{\circ}C$ and 8.5~381.3 V/mm for ceramics sintered at 135$0^{\circ}C$. On the whole, the increase of sintering temperature led to the low nonlinearity regardless of Sm$_2$O$_3$content. ZnO-Pr$_{6}$O$_{11}$-CoO-based ceramics doped with 1.0 mol% at each sintering temperature exhibited the most superior varistor properties, with the nonlinear exponent of 42.1 at 130$0^{\circ}C$, 36.8 at 135$0^{\circ}C$ and the leakage current of 9.2 $\mu$A at 130$0^{\circ}C$, 11.7 $\mu$A at 135$0^{\circ}C$.EX>.EX>.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.22 no.2
• /
• pp.74-78
• /
• 2018

Purpose $[^{11}C]$acetate has been proved useful in detecting the myocardial oxygen metabolism and various malignancies including prostate cancer, hepatocellular carcinoma, renal cell carcinoma and brain tumors. The purpose of study was to improve the radiosynthesis yield of $[^{11}C]$acetate on a automated radiosynthesis module. Materials and Methods $[^{11}C]$acetate was prepared by carboxylation of grignard reagent, methylmagnesium chloride, with $[^{11}C]$$CO_2$ gas, followed by hydrolysis with 1 mM acetic acid and purification using solid phase extraction cartridges. The effect of the reaction temperature ($0^{\circ}C$, $10^{\circ}C$, $-55^{\circ}C$) and cyclotron beam time (10 min, 15 min, 20 min, 25 min) on the radiosynthesis yield were investigated in the $[^{11}C]$acetate labeling reaction. Results The maximum radiosynthesis yield was obtained at $-10^{\circ}C$ of reaction temperature. The radioactivities of $[^{11}C]$acetate acquired at $-10^{\circ}C$ reaction temperature was 2.4 times higher than those of $[^{11}C]$acetate acquired at $-55^{\circ}C$. Radiosynthesis yield of $[^{11}C]$acetate increased with increasing cyclotron beam time. Conclusion This study shows that radiosynthesis yield of $[^{11}C]$acetate highly dependent on reaction temperature. The best radiosynthesis yield was obtained in reaction of grignard reagent with $[^{11}C]$$CO_2$ at $-10^{\circ}C$. This radiolabeling conditions will be ideal for routine clinical application.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.4
• /
• pp.934-940
• /
• 2010

The reduction of [$Os_3(CO)_{11}P(OMe)_3$] and subsequent ionic coupling of the reduced species with $[Ru({\eta}^5-C_5H_5)(CH_3CN)_3]^+$ resulted in the formation of [$Os_3(CO)_{11}P(OMe)_3(Ru({\eta}^5-C_5H_5))_2$] which can be converted to spiked tetrahedral cluster, [$HOs_3(CO)_{11}P(OMe)_3Ru_2({\eta}^5-C_5H_5)(C_5H_4)$] via the intramolecular hydrogen transfer. Due to the unavailability of a suitable single crystal, the PW91/SDD and LDA/SDD density functional methods were used to predict possible structures and the available spectroscopic information (IR, NMR) of [$Os_3(CO)_{11}P(OMe)_3(Ru({\eta}^5-C_5H_5))_2$]. The most probable geometry found by constrained search is the isomer (a2) in which the phosphite, $P(OMe)_3$, occupies an axial position on one of the two osmium atoms that is edge bridged by the $Ru(CO)_2({\eta}^5-C_5H_5)$ unit. By using the most probably geometry, the predicted infrared frequencies and $^1H$, $^{13}C$ and $^{31}P$ NMR chemical shifts of the compound are in the same range as the experimental values. For this type of complex, the LDA/SDD method is appropriate for IR predictions whereas the OPBE/IGLO-II method is appropriate for NMR predictions. The activation energy and reaction energy of the intramolecular hydrogen transfer coupled with the structural change of the transition metal framework were estimated at the PW91/SDD level to be 110.32 and -0.14 kcal/mol respectively.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1692-1695
• /
• 1999

The nonohmic characteristics of ZnO-$Pr_6O_{11}$-CoO-based ceramic varistor doped with $Dy_2O_3$ in the range $0.0\sim2.0mol%$ sintered at $1300^{\circ}C$ and $1350^{\circ}C$ were investigated. 98.5 ZnO-$0.5Pr_6O_{11}$-1.0CoO varistor sintered at $130^{\circ}C$ exhibited higher nonlinear coefficient of 36 than the established Pr-based varistor. The four-component-system varistor such as 96.5 ZnO-$0.5Pr_6O_{11}$-1.0CoO-$2.0Dy_2O_3$ exhibited very highly nonohmic characteristics, which has nonlinear coefficient of 53.9. 98.5ZnO-$0.5Pr_6O_{11}$-1.0CoO varistor sintered at $1350^{\circ}C$, in contrast with that of $1300^{\circ}C$, exhibited approximately ohmic characteristics but nonlinear coefficient of varistor doped with 0.5mol% $Dy_2O_3$ showed higher nonlinear coefficient of probably 35. Consequently, it can be confirmed that $Dy_2O_3$ acted as additive of improvement on nonlinear coefficient. It is estimated that $Dy_2O_3$ will be used as additive of improvement on nonlinear coefficient to develop a goof ZnO varistor.