[en] A new iterative method is proposed for solving the three-dimensional neutron diffusion equation. This method reduces the discretization error in the calculation of neutron leakage from a subregion. In addition, when only one fine-mesh point is located in each subregion, this method becomes the same as a fine-mesh finite-difference approximation method. Therefore, it is easy to compare the results of this method with those of a fine-mesh difference approximation. The computer code for this method can be used for calculating both the collapsed neutron flux and fine-mesh difference approximations. The conditions for the convergence of this iterative technique are introduced as a function of the neutron leakage. (auth)

[en] Vibronic level-to-level intensity distributions of the fluorescence emission from the ground (4⁰) and the first excited (4¹) vibrational levels of D₂CO and HDCO (A¹A₂) have been determined in the wavelength range 360 to 490 nm. From the intensity distribution data obtained at Boltzmann equilibrium under high buffer gas pressures of n-C₄H₁₀, the ratio of the radiative lifetimes for the two SVL's tau/sub R/(4¹)/tau/sub R/(4⁰), has been determined to be 0.82 +- 0.08 for D₂CO and 0.72 +- 0.15 for HDCO. The collision-induced 4¹ → 4⁰ vibrational relaxation by the parent molecule (X) proceeds with rate constants (k/sub 10.P/) of 9.4 X 10^-10 for D₂CO and 17 x 10^-10 cm³ molecule^-1s^-1 for HDCO, exceeding the gas kinetic rate by a factor of 3 and 5, respectively. 2 figures, 8 tables

[en] We measured the local temperature in an ion track utilizing fast exciton recombination in (C₃H₇NH₃)₂PbBr₄. We obtained the local temperatures of 1000-1500 K for 1.0 MeV H⁺, 2.0 MeV H⁺ and He⁺, and the local temperature was found to be an increasing function of the linear energy transfer. Furthermore, the measured local temperature increased with increasing ion dose, which is attributed to the diffusion of the phonons in an ion track

[en] The rise of the local temperature in an ion track was observed by utilizing fast exciton radiative recombination in the layered perovskite-type materials (C₃H₇NH₃)₂PbBr₄ and (C₄H₉NH₃)₂PbBr₄. In (C₃H₇NH₃)₂PbBr₄, the local temperature was an increasing function of the excitation density or linear energy transfer (LET). However, the same local temperature was obtained for different LETs in (C₄H₉NH₃)₂PbBr₄, which was attributed to local melting of the organic layers. Furthermore, the obtained value of the local 'melting point' was much higher than that in the bulk analog of the organic and inorganic layers, which indicates that nonequilibrium phonon dynamics plays a crucial role in the thermal spike process

[en] Purpose: Modulators of the DNA-unwinding enzyme, topoisomerase I (Topo I), inhibit DNA repair and have been reported to increase the lethal effects of X rays, which create breaks in DNA. CPT-11 is a derivative of camptothecin, a Topo I inhibitor, and is clinically available. In this study, we tested the in vitro combination effects of SN-38, an active form of CPT-11, and irradiation on several cell lines. Materials and Methods: Exponentially growing or confluent cultures of CHO cells were treated with SN-38 for 30 min. Cells were then irradiated. Thereafter, the cells were further incubated with the drug for 0 to 3 h. Exponentially growing other cell lines were exposed to 200 nM SN-38 for 30 min before, during, and 3 h after irradiation. The cell survival rate was determined using a conventional clonogenic assay. Results: SN-38 (200 nM to 4 μM) alone showed slight toxicity to CHO cells in the confluent culture after a 3.5-h incubation. When the cells were treated with the lower doses of SN-38 (50 to 800 nM) during the exponentially growing phase, the cell survival rates were much lower. In combination with irradiation, SN-38 showed only additive effects to irradiation when cells were treated in confluent cultures. However, higher combination effects of SN-38 and irradiation were observed in the cells treated in the exponentially growing phase. When cells were irradiated during the exponentially growing phase, a significant combination effect of 200 nM SN-38 and irradiation was also observed in some cell lines, but not in others. Conclusion: SN-38 and irradiation showed supraadditive effects in some cell lines, when treated in the exponentially growing phase, but not in other cell lines or when cells were treated in the confluent phase

[en] Pressure dependent values of SRL fluorescence quantum yields Phi/sub f/(J', K') in the 1--120 mTorr range are reported for 75 rotational levels (E/sup prime//sub rot/ = 37--1127 cm^-1) of S₁ H₂CO (4¹). High lying rotational levels tend to show an increase in Phi/sub f/ with increasing pressure of S₀ H₂CO, whereas low lying rotational levels tend to show a decrease. For some levels, collision-induced ΔJ' transitions occur 5--10 times faster than the gas kinetic collision rate but probably with a much slower rate for ΔK' transitions. A ΔK'-constrained, collision-induced rotational relaxation model involving mainly ΔJ' = +- 1 transitions is proposed to explain the observed pressure dependence of Phi/sub f/

[en] We have been developing a radioactive waste package made of high-strength and ultra low-permeability concrete (HSULPC) for geological disposal of TRU wastes, which is expected to be much more impervious to water than conventional concrete. In this study, basic data for the HSULPC regarding its the impervious character and the thermodynamics during cement hydration were obtained through water permeability measurements using cold isostatic pressing (CIP) and adiabatic concrete hydration experiments, respectively. Then, a prediction tool to find concrete package construction conditions to avoid thermal cracking was developed, which could deal with coupled calculations of cement hydration, heat transfer, stress, and cracking. The developed tool was applied to HSULPC hydration on a small-scale cylindrical model to examine whether there was any effect on cracking which depended on the ratio of concrete cylinder thickness to its inner diameter. The results were compared to experiments. For concrete with a compressive strength of 200MPa, the water permeability coefficient was 4 x 10¹⁹ m/s. Dependences of activation energy and frequency factor on degree of cement hydration had a sharp peaking due to the nucleation rate-determining step, and a gradual increase region due to the diffusion rate-determining step. From analyses of the small-scale cylindrical model, dependences of the maximum principal stress on the radius were obtained. When the ratio of the concrete thickness to the heater diameter was around 1, the risk of cracking was predicted to be minimized. These numerical predictions from the developed tool were verified by experiments

[en] A large number of rotational levels in the 4¹ (v₄' = 1) manifold of S₁ formaldehyde were excited in a multipath absorption/fluorescence cell using a pulsed dye laser. Fluorescence decay times (tau/sub f//sup D/) of D₂CO were measured for a number of rotational levels at 10.8 mTorr so that the apparatus could be calibrated for the measurement of fluorescence quantum yields (Phi/sub f//sup H/) of many rotational levels of H₂CO at varying pressures (1--120 mTorr). For 10.8 mTorr D₂CO, the average values of tau/sub f//sup D/ and Phi/sub f//sup D/ were 4.8 +- 0.3 μsec and 0.66 +- 0.07, respectively. The zero pressure values of Phi/sub f//sup H/ for H₂CO varied randomly from 0.0063 for J' = 13, K' = 7 (E/sub rot/ = 570.9 cm^-1) to 0.32 for J' = 2, K' = 2 (E/sub rot/ = 37.1 cm^-1), due to a random variation of the nonradiative decay rates. The J'-population averaged value of Phi/sub f//sup H/ in a given K' manifold < Phi/sub f//sup H/(J')>/sub K/' shows a trend to decrease with the increase in the K' quantum number for K' = 2--6, but becomes nearly constant for K' = 6--10. The (J', K')-population averaged value of Phi/sub f//sup H/ is < Phi/sub f//sup H/(J', K')> = 0.033 and the average value of radiative lifetimes is tau/sub r//sup H/ = 3.3 +- 1.2 μsec for the 4¹ level

[en] There were 384 (8877 square m) walls which covered with plant on 10 square km in the city of Tokyo, and the green wall rate in the city of Tokyo was 0.88%. Vines, for example Parthenocissus tricuspidata and Hedera helix, were widely used. The factor of thinking better of the landscape in urban area was one of the easily management of plants. The three wall greening systems, a wall covered with hanging climbers and two types of self-contained living wall, mitigated the thermal environment. However its degree can be depended on the greening method and the greenery occupancy rate of wall

[en] We report a new type of scintillator especially suitable for pulse-radiation detection. Thin films of organic/inorganic perovskite compound (n-C₆H₁₃NH₃)₂PbI₄, which is characterized by a multiple quantum well structure, were bombarded by 2.0 MeV protons, and their radiation-induced emission spectra were obtained. A single and sharp emission peak due to an exciton was observed at the wavelength of 524 nm. This emission was clearly detected even at room temperature, and its quantum efficiency was very high. The line shape of this emission did not change, retaining its sharpness, and no other emissions appeared throughout the irradiation. The optical response of (n-C₆H₁₃NH₃)₂PbI₄ is very fast. (n-C₆H₁₃NH₃)₂PbI₄ is a promising scintillator material, meeting requirements not satisfied by conventional scintillators