[en] Results of researches and tests of the flammability control system FCS conducted in Japan with the aim of using passive autocatalytic recombinators making possible reduction of expenditures on equipment and service, improvement of reliability of the rector are performed. Quantity of catalytic FCS for the reactor safety at BWR NPP is determined. Improvements in reliability of the rector because of absence of dynamic systems as well as absence of problems with the location of recombinators were demonstrated by tests of catalytic FCS

[en] The object of this study is to acquire data on radiation damage of organic insulator films at low temperature. The specimens used were thin films of polyphenylene sulfide (PPS), polyarylether etherketone (PEEK), polyethylene terephthalate (PET), and polypyromellitimide (PPMI, Kapton H). Experiments were mainly done with PPS, since at the present there is little information on the cryogenic properties and radiation effects for this material. Irradiation of the films was performed at 20 K in the lowtemperature irradiation facility of the Kyoto University Reactor and the mechanical properties of the films were measured at 77 K. In tensile tests of PPS films, both the unirradiated and irradiated specimens showed a gradual increase in strength beyond the elastic limit at all test temperatures. The tensile strength and the ultimate elongation of PPS films were almost independent of irradiation dose up to 8 MGy at 20 K. For comparison, similar mechanical tests were carried out with irradiated films of PEEK, PET, and PPMI. As far as the present experiments are concerned the radiation tolerance of PPS films has been proved to be on the same level as that of PEEK and PPMI films

[en] This paper reports how the T-method for eddy current analysis, developed by the authors, has several advantages over conventional methods. Mesh division of space is not needed, because current vector potential, T, could be defined only in an analysis region with a proper boundary condition and the Coulomb gage to get a unique solution. Magnetic field generated outside a conductor by induced current can be simply given by normal components of T on a surface of the conductor. This procedure indicates the possibility of crack shape recognition due to possible use of the normal components on the surface of a cracked body. In the present study numerical experiments are tried to verify the possibility of focusing on accuracy of the numerical solutions

[en] A transverse bunching method is presented for an electron beam using a deflecting mode in a non-axisymmetric RF cavity. The method's principle is based on an interaction between synchrotron and betatron oscillations. A damping of the betatron oscillation leads to a reduction of beam size at the expense of growth in energy spread. The damping time can be controlled by varying the amplitude of the deflecting mode or by detuning of the deflecting mode frequency from an acceleration frequency. (author)

[en] Two commercially available reinforced composites intended for use as insulating materials for fusion magnets were subjected to gamma and neutron radiation at room and cryogenic temperatures. The fracture modes were analyzed in flexural and tensile tests. The fracture modes varied from tensile to shear fracture with increasing radiation doses because irradiation markedly decreased the laminar shear strength. The effects of dose and temperature on interlaminar shear strength were determined for cobalt 60 irradiation at the ISIR laboratory and for neutron irradiation at the Kyoto University Reactor. The materials, Lamiverre-A and Hoxan, two glass-cloth-reinforced epoxy laminates, were assessed after irradiation by scanning electron microscopy and fractography

[en] The radiation effects of some organic insulator films have been studied at low temperature. The specimens used were thin films of polyethylene terephtalate (PET), polyphenylene sulfide (PPS), polyether etherketone (PEEK), and polypyromellitimide (PPMI, Kapton H). Reactor irradiations were performed at 20 K and tensile properties of the irradiated films were measured at 77 K. In the irradiated PET, the tensile strength remarkably decreased with an increase in the absorbed dose above 2 MGy and the ultimate elongation gradually reduced with increasing dose. On the other hand, no essential changes in mechanical properties were observed for both PPS and PEEK films after irradiation up to 8 MGY at 20 K. As far as the present experiments are concerned, the radiation tolerances of PPS and PEEK films have been proved to be of the same level as that of PPMI film. (orig.)

[en] Purpose: To test the in vitro efficacy of the chemotherapeutic alkylating agent prodrug 4-ipomeanol (4-IM) combined with ionizing radiation (IR) in cells transduced with an adenoviral vector carrying a chimeric fusion protein of rabbit cytochrome CYP4B1 and enhanced green fluorescent protein (EGFP) under the control of the radiation-inducible EGR1 promoter. Materials and Methods: Cassette effect was tested by comparing survival fractions determined by low-input MTT assay for HEK293 cells stably transfected with the prodrug-activating fusion protein CYP4B1-EGFP under the control of the EGR1 promoter with that of control HEK293 cells stably transfected with EGFP alone, 8 days after treatment with 4-IM and IR. Radiosensitization by activated 4-IM was tested by comparing survival fractions from clonogenic assays of 9L cells transfected with the CYP4B1-EGFP cassette or EGFP alone, both under a constitutive CMV promoter, after 24 hours of 4-IM exposure. The EGR-4B1-EGFP cassette was inserted into the E1A region of an adenoviral vector, and efficacy compared to adenoviral vector carrying CMV-EGFP (MOI 100), was tested in U87-MG cells using MTT assay 3 days after treatment with 4-IM and IR. In each case, cells were irradiated at doses of 0, 2, and 4 Gy on day 1, following 4-IM treatment at concentrations of 0, 2.5 and 5.0 μg/ml. Results: MTT assays demonstrated a decrease in the relative survival fractions (survival with 4-IM/survival without 4-IM) of EGR1-CYP4B1-EGFP transfected cells with increasing radiation dosage, but not of the control cells: 88%, 57%, 39% at 0, 2 and 4 Gy for the EGR1-CYP4B1-EGFP cells, and 96%, 87%, 96% at 0, 2 and 4 Gy for the control cells (2.5 μg/ml 4-IM). Clonogenic assays for radiosensitization demonstrated that survival fractions decreased with increasing radiation doses and 4-IM concentrations (for the CYP4B1 bearing cells), but no significant differences in D0 were seen with 4-IM. Of relevance, a similar lack of sensitization was seen in the same model using rat cytochrome P450 2B1 (CYP2B1) to activate cyclophosphamide, but a pronounced effect was seen when this combination was used in a replication competent HSV-1 vector (rRp450). 4-IM (5.0 μg/ml) reduced the relative survival of cells treated with adenovirus carrying EGR-4B1-EGFP to 66±11% with the addition of 2 Gy IR and to 57±- 10% with 4 Gy IR. No effect was seen in cells treated with adenovirus carrying CMV-EGFP. Conclusion: IR potentiates the cytotoxic activity of the EGR1/CYP4B1/4-IM transgene system. Cytochrome P450 activated alkylating agent prodrugs do not appear to themselves sensitize cells to radiation in the models tested, but significant augmentation of IR efficacy can be obtained when these are incorporated into appropriate transgene and vector systems. There may be additional variability between agents and cell lines, as has been reported for temozolomide. We are proceeding to test these gene therapy vectors in murine models

[en] The long-term stability and maintenance of endosseous implants with anodized–hydrothermally treated commercially pure titanium surfaces and a nanotopographic structure (SA-treated c.p.Ti) depend on the barrier function provided by the interface between the transmucosal portion of the implant surface and the peri-implant epithelium. This study investigated the effects of extracellular and intracellular gene expression in adherent gingival epithelial cells cultured for 1–7 days on SA-treated c.p.Ti implant surfaces compared to anodic oxide (AO) c.p.Ti and c.p.Ti disks. Scanning electron microscopy (SEM) showed filopodium-like extensions bound closely to the nanotopographic structure of SA-treated c.p.Ti at day 7 of culture. Gene expressions of focal adhesion kinase, integrin-α6β4, and laminin-5 (α3, β3, γ2) were significantly higher on SA-treated c.p.Ti than on c.p.Ti or AO c.p.Ti after 7 days (P < 0.05). Our results confirmed that gingival epithelial cells adhere to SA-treated c.p.Ti as the transmucosal portion of an implant, and that this interaction markedly improves expression of focal adhesion molecules and enhances the epithelial cell phenotype. The cellular gene expression responses driving extracellular and intracellular molecular interactions thus play an important role in maintenance at the interface between SA-treated c.p.Ti implant surfaces and the gingival epithelial cells. - Highlights: • SA-treated Ti provides a nanotopographic structure for clinical oral implants. • This could regulate integrin-mediated epithelial cell adhesion and gene expression. • FAK mRNA was significantly higher on SA-treated Ti. • Integrin-α6β4 and laminin-5 mRNA were significantly higher on SA-treated Ti. • Extracellular/intracellular molecular interactions play a key role on SA-treated Ti

[en] Radiation effects on glass-fiber reinforced epoxy composites at cryogenic temperatures has been studied by measuring the changes in interlaminar shear strength of the specimens. The scanning electron microscope observation has also been performed on fracture surface of the specimens. At 8.5 MGy of absorbed dose, only 10 % decrease of the strength was observed in the case of gamma irradiation, whereas over 80 % decrease of the strength was found on the reactor irradiated specimen. The difference of degradation behavior between gamma and reactor irradiations is attributed to the additional absorbed dose in the latter from the nuclear reaction due to boron-10 contained in the glass fibers by capture of thermal neutrons. (author)

[en] The intestinal absorption of Serratia protease (TSP) was studied in vivo with adult rats and dogs. After intraduodenal administration of TSP, the TSP levels in the blood and lymph were determined periodically by radioimmunoassay. The maximum concentration of TSP was observed within 1 h after administration in both the blood and lymph; it was higher in the latter. An apparent saturation phenomenon was observed in the absorption of TSP