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[en] The radioactive decay of 99mTc has been measured using a HP Ge-spectrometer with active volume 69.4 cm3 and EG and G ORTEC model 7050 Data Acquisition and Analysis System. The energies and intensities of very weak 321.99keV and 232.01keV gamma rays were obtained. Energy levels of 99Ru were found with the energy value of 321.99keV (5/2+) and 89.98keV(3/2+). The beta branches to 99Ru ground, 89.98keV and 321.99KeV states were respectively determined with the intensities per decay of 1.0 x10-5, 2.6x10-5 and 0.7742x10-6. And also log ft-values of 9.32, 8.63, and 7.82 were respectively derived. The decay scheme of 99mTc were finally presented. Intensity ratios of 321.99keV, 232.01keV and 140.13 keV gammas were calculated through several corrections; I321.99 : I232.01 : I140.13 = 0.8087x10-6 : 0.6963x10-7 : 1. The total gamma emission following 99mTc beta decay results in a negligible effects to dosage calculations in the use of 99mTc for nuclear medicine. (Author)
[en] The research was performed to develop a CANDU-6 Core Monitoring System(CCMS) that enables operators to have efficient core management by monitoring core power distribution, burnup distribution, and the other important core variables and managing the past core history for Wolsong nuclear power plant unit 1. The CCMS uses Reactor Fueling Simulation Program(RFSP, developed by AECL) for continuous core calculation by integrating the algorithm and assumptions validated and uses the information taken from Digital Control Computer(DCC) for the purpose of producing basic input data. The CCMS has two modules; CCMS server program and CCMS client program. The CCMS server program performs automatic and continuous core calculation and manages overall output controlled by DataBase Management System. The CCMS client program enables users to monitor current and past core status in the predefined GUI(Graphic-User Interface) environment. For the purpose of verifying the effectiveness of CCMS, we compared field-test data with the data used for Wolsong unit 1 operation. In the verification the mean percent differences of both cases were the same(0.008%), which showed that the CCMS could monitor core behaviors well
[en] To assess the positional relationship between the maxillary sinus floor and the apex of the maxillary first molar using cone beam computed tomograph (CBCT). CBCTs from 127 subjects were analysed. A total of 134 maxillary first molars were classified according to their vertical and horizontal positional relationship to the maxillary sinus floor and measured according to the distance between the maxillary sinus floor and the maxillary first molar. Type III (The root projected laterally on the sinus cavity but its apex is outside the sinus boundaries) was dominated between 10 and 19 years and type I (The root apex was not in contact with the cortical borders of the sinus) was dominated (P<0.05) between 20 and 72 years on the vertical relationship between the maxillary sinus floor and the apex of the maxillary first molar. The maxillary sinus floor was located more at the apex (78.2%) than at the furcation (21.3%) for the palatal root. The distance from the root apex to the maxillary sinus floor confined to type I was increased according to the ages (P<0.05). Type M (The maxillary sinus floor was located between the buccal and the palatal root) was most common (72.4%) on the horizontal relationship between the maxillary sinus floor and the apex of the maxillary first molar. CBCT can provide highly qualified images for the maxillary sinus floor and the root apex of the maxillary first molar.
[en] 0.0622g RuCl3 powder was dissolved in 30mL DI water. ITO-glass was used as a working electrode, Pt as the counter electrode, and Ag/AgCl as a reference electrode. The precursor solution was not stirred during the deposition, and the temperature was maintained at 50 .deg. C. The deposited films were Irradiated by 1 MeV e-beam. Electron beam irradiation altered the oxidation state and increased crystallinity. Significant morphological changes were also observed with electron beam irradiation. Compared with control sample, which was not irradiated with electron beam, electron beam irradiated film showed much higher capacity. And the capacity was found to be strongly dependent on irradiation time. These enhanced electrochemical properties can be attributed to the higher surface area and facilitated charge transfer, resulting from increased surface roughness and defect sites
[en] We report on the use of a multichannel time scaling technique suitable for determining the half-life of long-lived intermediate states by means of correlation counting. Use of the method is demonstrated by studying the decay of an isomer of 75As at 304 keV excitation energy using a pressurized proportional counter and NaI(Tl) detection set-up. The measurement time was 9000 s. Eighteen values for electron capture detection efficiencies were obtained in the energy region 1.4-12 keV. We obtained eighteen sets of data for determining the fraction of correlation events, each set consisting of 52 counting distributions determined by scanning the clock-time of electron capture events with dwell times varying from 5 ms to 1500 ms. There are four sets acceptable for this work according to our criteria. The half-life of the 304 keV level was determined to be (17.62±0.23) ms and is compared with earlier results. (author)
[en] Purpose: A specially designed self-expandable covered metallic stent impregnated with the β-emitting radioisotope 166Ho (166Ho, energy: 1.85 and 1.76 MeV, T((1)/(2)): 26.8 h) was developed at our institute for the purpose of intraluminal palliative brachytherapy, as well as for treating malignant esophageal stricture and swallowing difficulty. The aim of this study was to evaluate the tissue response to brachytherapy and the safety of the radioactive metallic stent with regard to the normal canine esophagus before clinical application. Methods and Materials: 166Ho was impregnated into the polyurethane membrane (50 μ thickness) covering the outer surface of a self-expandable metallic stent (diameter, 18 mm; length, 40 mm). Stents with radioactivity 4.0-7.8 mCi (Group A, n=15), 1.0-1.8 mCi (Group B, n 5), and 0.5-0.7 mCi (Group C, n=5) were placed in the esophagi of 25 healthy beagle dogs, and the stents were tightly anchored surgically to prevent migration. The estimated radiation dose calculated by Monte Carlo simulation was 194-383 Gy in Group A, 48-90 Gy in Group B, and 23-32 Gy in Group C. The dogs were killed 8-12 weeks after insertion of the stents, and histologic examinations of the esophageal walls were performed. Results: In Group A, 3 of 15 dogs died of wound infection, so specimens were obtained from only 12 dogs; all 12 cases showed esophageal stricture with mucosal ulceration. Microscopically, severe fibrosis and degeneration of the muscular propria were found in 3 dogs, complete fibrosis of the entire esophageal wall was found in 7 dogs, and esophageal fibrosis with radiation damage within periesophageal soft tissue was found in 2 dogs. However, esophageal perforation did not develop, despite extremely high radiation doses. In Group B, glandular atrophy and submucosal fibrosis were found, but the muscular layer was intact. In Group C, no histologic change was found in 3 dogs, but submucosal inflammation and glandular atrophy with intact mucosa were found in 2 dogs. Conclusions: A radioactive, self-expandable covered metallic stent can be used as an alternative therapeutic modality for the palliative treatment of malignant esophageal stricture
[en] Esophageal cancer patients have a difficulty in the intake of meals through the blocked esophageal lumen, which is caused by an ingrowth of cancer cells and largely influences on the prognosis. It is reported that esophageal cancer has a very low survival rate due to the lack of nourishment and immunity as the result of this. In this study a new radioactive stent, which prevents tumor ingrowth and restenosis by additional radiation treatment, has been developed. Using 'HANARO, research reactor, the radioactive stent assembly (166Ho-SA) was prepared by covering the metallic stent with a radioactive sleeve by means of a post-irradiation and pre-irradiation methods. Scanning electron microscopy and autoradiography exhibited that the distribution of 165/166Ho (NO3) compounds in polyure-thane matrix was homogeneous. A geometrical model of the esophagus considering its structural properties, was developed for the computer simulation of energy deposition to the esophageal wall. The dose distributions of 166Ho-stent were calculated by means of the EGS4 code system. The sources are considered to be distributed uniformly on the surface in the form of a cylinder with a diameter of 20 mm and length of 40 mm. As an animal experiment, when radioactive stent developed in this study was inserted into the esophagus of a Mongrel dog, tissue destruction and widening of the esophageal lumen were observed. We have developed a new radioactive stent comprising of a radioactive tubular sleeve covering the metallic stent, which emits homogeneous radiation. If it is inserted into the blocked or narrowed lumen, it can lead to local destruction of the tumor due to irradiation effect with dilatation resulting from self-expansion of the metallic property. Accordingly, it is expected that restenosis esophageal lumen by the continuous ingrowth and infiltration of cancer after insertion of our radioactive stent will be decreased remarkably.=20
[en] The influence of electron beam irradiation on the electrochemical properties of electrodeposited RuO2 thin films was investigated using a 1 MeV electron beam. Crystallinity change before and after electron beam irradiation was investigated by X-ray diffraction, and the oxidation state of ruthenium was determined by X-ray photoelectron spectroscopy. Scanning electron microscopy was utilized to examine the morphology of the films. The results show that electron beam irradiation altered the oxidation state of ruthenium and increased crystallinity. Cyclic voltammetry was employed to evaluate the electrochemical properties of the synthesized RuO2 films in terms of their application as electrodes of electrochemical capacitors. RuO2 irradiated with 40 kGy showed 2.7 times higher capacitance (520 Fg-1) than the as-electrodeposited sample (190 Fg-1).
[en] We obtain the angular dependence of magnetophonon resonance (MPR) peaks from longitudinal magnetoconductivities of GaAs/AlAs semiconductor superlattices for longitudinal optical (LO) phonons in tilted magnetic field applied to the superlattice axis. The MPR peaks of both GaAs and AlAs LO phonon modes using the second derivative of the magnetoconductivities including a miniband width and a periodicity of the potential are shown. As the tilt angle of the applied magnetic fields is increased, the MPR peak positions are shifting to higher magnetic strength region whereas the peak amplitudes are decreasing to vanish at the same condition with experiments. Our results are in qualitative good agreement with the experimental results. We also get the resonance fields for the MPR peak numbers of the GaAs and AlAs LO phonon modes as a function of the tilt angles. Furthermore, we obtain the dispersion relations and the density of states (DOS) including a miniband width, a periodicity of the potential and tilt angles of the tilted magnetic fields to explain the appearance of plateau region between neighboring peak amplitudes. The plateau region can be explained by phenomena such as the shifts, the decreases, and the disappearances of the peak amplitudes of the magnetoconductivities and the second derivative of magnetoconductivities of GaAs/AlAs semiconductor superlattices for tilt angles of the applied magnetic fields