ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV. 相似文献
Anilinepropylsilica hybrid powder was synthesized by a sol-gel route in basic medium using HF as catalyst. The effect of the amount of HF catalyst on the morphologies and on organic content was studied. The xerogels were characterized using FTIR, SEM and N2 adsorption-desorption isotherms. The increase in the HF quantity results in an slight increase in organic content and changes in the particle size, surface area and pore structure. 相似文献
To elucidate structure-activity relationships for drugs that are able to poison or inhibit topoisomerase II, we investigated the thermodynamics and stereochemistry of the DNA binding of a number of anthracene derivatives bearing one or two 4, 5-dihydro-1H-imidazol-2-yl-hydrazone side chains (characteristic of bisantrene) at different positions of the planar aromatic system. An aza-bioisostere, which can be considered a bisantrene-amsacrine hybrid, was also tested. The affinity for nucleic acids in different sequence contexts was evaluated by spectroscopic techniques, using various experimental conditions. DNA-melting and DNase I footprinting experiments were also performed. The location and number of the otherwise identical side chains dramatically affected the affinity of the test compounds for the nucleic acid. In addition, the new compounds exhibited different DNA sequence preferences, depending on the locations of the dihydroimidazolyl-hydrazone groups, which indicates a major role for the side-chain position in generating specific contacts with the nucleic acid. Molecular modeling studies of the intercalative binding of the 1- or 9-substituted isomers to DNA fully supported the experimental data, because a substantially more favorable recognition of A-T steps, compared with G-C steps, was found for the 9-substituted derivative, whereas a much closer energy balance was found for the 1-substituted isomer. These results compare well with the alteration of base specificity found for the topoisomerase II-mediated DNA cleavage stimulated by the isomeric drugs. Therefore, DNA-binding specificity appears to represent an important determinant for the recognition of the topoisomerase-DNA cleavable complex by the drug, at least for poisons belonging to the amsacrine-bisantrene family. 相似文献
In order to effectively remove B from Si for its use in solar cells, a process involving B removal by solidification refining
of Si using a Si-Al melt with Ti addition was investigated. For clarifying the effect of Ti addition on B removal from the
Si-Al melt, TiB2 solubilities in Si-64.6 at. pct Al melt at 1173 K and Si-60.0 at. pct Al melt at 1273 K were determined by measuring the
equilibrium concentrations of B and Ti in the presence of TiB2 precipitates. The small solubilities of TiB2 in the Si-Al melt indicate the effective removal of B from the Si-Al melt by Ti addition. Further, solidification experiments
of Si-Al alloys containing B by Ti addition were performed, and the effect of Ti addition on the solidification refining of
Si with the Si-Al melt was successfully confirmed. 相似文献
Phase separation which occurs in parallel to the hydrolysis and gelation of alkoxysilane solution containing poly(sodium styrenesulfonate) (NaPSS) has been investigated. Depending on the reaction conditions, gel morphologies such as isolated pores, particle aggregates, and interconnected continuous pores from 0.1 to 100 μm long have been observed. Time-resolved light scattering of gelling solution suggested the occurrence of spinodal phase separation through the polymerization of silica and the subsequent freezing of the developing structure by sol-gel transition. The effects of reaction parameters on the periodic size are explained mainly in terms of their influence on the "chemical cooling" rate which is determined by the polymerizatica rate of silica and the solubility of NaPSS in the reacting solution. 相似文献
Summary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).
SEM photograph of silica particles prepared through capillary plate membrane. 相似文献
In this paper, we propose a new video conferencing system that presents correct gaze directions of a remote user by switching among images obtained from multiple cameras embedded in a screen according to a local user’s position. Our proposed method reproduces a situation like that in which the remote user is in the same space as the local user. The position of the remote user to be displayed on the screen is determined so that the positional relationship between the users is reproduced. The system selects one of the embedded cameras whose viewing direction towards the remote user is the closest to the local user’s viewing direction to the remote user’s image on the screen. As a result of quantitative evaluation, we confirmed that, in comparison with the case using a single camera, the accuracy of gaze estimation was improved by switching among the cameras according to the position of the local user.