The neutronics and burnup analyses of an accelerator-based transmutation system with tungsten target and TRU-nitride fuel were performed with a newly developed code system named ATRAS (Accelerator-based Transmutation Reactor Analysis System). The ATRAS code is an integrated code system which can perform the hadronic cascade process above 20 MeV and neutron transport and core burnup process below 20 MeV with the spallation neutron source.
The specifications of the transmutation system are investigated. The core consists of the central spallation target region and the surrounding TRU-mononitride fuel region. The core is driven by protons at an energy of 1.0 GeV. This system was also proposed as a benchmark problem in the “OECD NEA/NSC Benchmark on Physics aspects of Different Transmutation Concepts”.
According to the calculation results by the ATRAS code, higher power density and transmutation rate were achieved with nitride fuel, and the neutron spectrum was slightly harder than that of the metallic fuel system. The burnup calculation for thermal power 800 MW was also performed with the ATRAS code. It is shown that about 300 kg of TRU are transmuted annually. 相似文献
Neuroprotective effects of ifenprodil, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, against glutamate cytotoxicity were examined in cultured rat cortical neurons. The viability of the cultures was markedly reduced by a 10-min exposure to glutamate followed by incubation with glutamate-free medium for 60 min. Ifenprodil and its derivative SL 82.0715 dose-dependently prevented cell death induced by glutamate. The NMDA antagonists MK-801 and 3-[(+/-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid also prevented glutamate cytotoxicity with a potency similar to that of ifenprodil. Ifenprodil as well as MK-801 prevented NMDA-induced cytotoxicity, but did not affect kainate-induced cytotoxicity. Glutamate cytotoxicity was inhibited by removing extracellular Ca++ during and immediately after glutamate exposure. Ifenprodil and MK-801 reduced NMDA-induced Ca++ influx measured with rhod-2. Either spermidine, a polyamine modulatory site agonist, or glycine, a strychnine-insensitive glycine site agonist, potentiated NMDA- and glutamate-induced cytotoxicity. The protective effects of ifenprodil against NMDA- and glutamate-induced cytotoxicity were significantly reduced by spermidine, but not by glycine. These findings indicate that ifenprodil protects cortical neurons against glutamate cytotoxicity by selective antagonism of the polyamine modulatory site of the NMDA receptor complex. 相似文献
Hepatitis delta virus (HDV) RNA ribozyme system which consists of three RNA oligomer strands (substrate 8-mer; enzyme 16-mer plus 35-mer, Fig. 1) was designed. Effects of Mg2+ concentration on the pseudo first-order rate constant (kobs) of RNA cleavage reaction and on conformation of ribozyme complex were examined. The secondary structure of the complex was also analyzed by limited digestion with ribonucleases. The kobs and CD data were analyzed by curve-fitting analysis using equations derived for two-Mg2+ and three-Mg2+ ion binding models. The result revealed that a three-Mg2+ binding model can explain the Mg(2+)-concentration-dependent changes of both conformation and activity of the HDV ribozyme. 相似文献
Comparison of acquired mutations in the p53 tumor suppressor gene can illuminate factors contributing to carcinogenesis among cancer cohorts. Japan has an ethnically homogeneous population with a low incidence of breast cancer. Previously we reported an unusual frequency, allelic status, and clustering of mutations in breast cancers from the northern part of the main Japanese island. To extend these findings, exons 2-11 and adjacent intronic sequences were analysed in tumors of women from northern (Hokkaido) and southern (Tokushima) Japan. The frequency of breast cancers with p53 gene mutations in the Hokkaido group is the highest reported (81%) while that in Tokushima (28%) is similar to most other populations. Thirteen of the 19 mutations (68.4%) in the Hokkaido cohort were heterozygous, an unusually high frequency for p53 mutations in any tumor type. There were three missense mutations at codon 175, a known hotspot for alterations in the p53 gene, and three missense mutations at codon 179, a rare site for p53 changes. In addition, the patterns of p53 gene mutation differed between the two Japanese cohorts (P=0.04). The multiple differences in acquired p53 mutations suggest unsuspected biological differences among breast cancers in northern and southern Japan. In addition, the high frequency of p53 mutations in breast cancers from Hokkaido predicted a poorer prognosis for this population which was confirmed on examination of mortality data. 相似文献
Japan Atomic Energy Research Institute (JAERI) performs Research and Development (R&D) for accelerator-driven systems (ADS) for transmutation of long-lived nuclides. To study the basic characteristics of ADS, Transmutation Experimental Facility is proposed within the framework of the J-PARC project. The facility consists of two buildings, Transmutation Physics Experimental Facility to research the neutronics and the controllability of ADS and ADS Target Test Facility for material irradiation and partial mockup of beam window. A comprehensive R&D program for future ADS plant is also underway in three technical fields, 1) accelerator, 2) lead-bismuth target/coolant and 3) subcritical core. 相似文献
To find a promising molecular method for meat traceability, three methods of single nucleotide polymorphism (SNP) detection: RFLP-PCR analysis, high-resolution melting (HRM) analysis, and TaqMan probe analysis, have been compared in terms of accuracy, ease of use, throughput capability, and cost. We genotyped ten pork DNA samples across three SNPs. The results showed that the HRM genotyping method was the most accurate and easiest to use with the lowest cost, while TaqMan probe analysis provided similar results, but its cost was much higher. 相似文献
Strong suppression of the effects caused by the internal electric field in ZnO/ZnMgO quantum wells following ion-implantation and rapid thermal annealing, is revealed by photoluminescence, time-resolved photoluminescence, and band structure calculations. The implantation and annealing induces Zn/Mg intermixing, resulting in graded quantum well interfaces. This reduces the quantum-confined Stark shift and increases electron-hole wavefunction overlap, which significantly reduces the exciton lifetime and increases the oscillator strength. 相似文献
Two-dimensional graphene offers interesting electronic, thermal, and mechanical properties that are currently being explored
for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of nano-graphene
oxide (NGO), i.e., single-layer graphene oxide sheets down to a few nanometers in lateral width. We develop functionalization
chemistry in order to impart solubility and compatibility of NGO in biological environments. We obtain size separated pegylated
NGO sheets that are soluble in buffers and serum without agglomeration. The NGO sheets are found to be photoluminescent in
the visible and infrared regions. The intrinsic photoluminescence (PL) of NGO is used for live cell imaging in the near-infrared
(NIR) with little background. We found that simple physisorption via π-stacking can be used for loading doxorubicin, a widely
used cancer drug onto NGO functionalized with antibody for selective killing of cancer cells in vitro. Owing to its small
size, intrinsic optical properties, large specific surface area, low cost, and useful non-covalent interactions with aromatic
drug molecules, NGO is a promising new material for biological and medical applications.
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This article is published with open access at Springerlink.com 相似文献