Development of an Evaluation Methodology for Fuel Discharge in Core Disruptive Accidents of Sodium-Cooled Fast Reactors

The purpose of the present study is to develop a methodology to evaluate fuel discharge through the CRGT （control-rod guide tube） during CDAs （core-disruptive accidents） of SFRs （sodium-cooled fast reactors）, since fuel discharge will decrease the core reactivity and CRGTs have a potential to provide an effective discharge path. Fuel discharge contains multi-component fluid dynamics with phase changes, and, in the present study, the SFR safety analysis code SIMMER （Sn, implicit, multifield, multicomponent, Eulerian recriticality） was utilized as a technical basis. First, dominant phenomena affecting fuel discharge through the CRGT are identified based on parametric calculations by the SIMMER code. Next, validations on the code models closely relating to these phenomena were carried out based on experimental data. It was shown that the SIMMER code with some model modifications could reproduce the experimental results appropriately. Through the present study, the evaluation methodology for the molten-fuel discharge through the CRGT was successfully developed.     

Flow induced acoustic resonance in in-line tube banks

In the present paper the attention is focused on the relation between vortex shedding phenomena andacoustic resonance which occurred in the two-dimensional model of boiler.There were tube bankswith in-line arrangement for small tube pitch ratio.We measured the sound pressure level,the phasedelay of acoustic pressures,the spectrum of velocity fluctuation and the gap velocity.As a result, wefound two peak frequencies of sound pressure level with different Strouhal numbers S_t,mainly about0.26 and 0.52.The noise of S_t=0.26 was the resonance of transverse mode and S_t=0.52 waslongitudinal mode.The vortex shedding of S_t=0.15 was generated inside the tube banks withoutacoustic resonance. As gap velocity increased, we observed that the peak level of spectrum was weakand broad-banded. The onset velocity of the acoustic resonance of longitudinal mode was lower thanthat of transverse mode.     

Optimal placement of heat generating components at various levels of electronics packaging

A multidisciplinary placement optimization methodology for heat generating electronics components is demonstrated at various levels of electronics packaging design. The proposed methodology is capable of handling a large number of conflicting multidisciplinary design requirements and complex trade-offs including thermal, mechanical, electrical, electromagnetic, cost among others, which are optimized simultaneously using a genetic algorithm. An effective thermal performance prediction methodology is developed to shorten the calculation time while retaining sufficient accuracy. For simpler thermal problems, a superposition method is used to predict the temperature distribution caused by arbitrarily placed multiple heat sources. For more complex problems (e.g. variable local heat transfer coefficient) artificial neural networks (ANNs) and the superposition method are combined for more efficient prediction of surface (case) and junction temperatures. The proposed methodology is designed to handle existing complex design trade-offs at the crucial early design stage. Capabilities of the present methodology are demonstrated by applying it to several standard benchmarks at the enclosure (PCB) and chip (logic block) levels.     

A method for multidirectional TEM observation of a specific site at atomic resolution

A new technique has been developed for the three-dimensional structure characterisation of a specific site at atomic resolution. In this technique, a focused ion beam (FIB) system is used to extract a specimen from a desired site as well as to fabricate the electron transparent specimen. A specimen holder with a specimen stage rotation mechanism has also been developed for use with both an FIB system and a high-resolution transmission electron microscope (TEM). The specimen holder allows both the FIB milling of a specimen and its observation in TEM without remounting the specimen from the specimen holder. A specimen for the three-dimensional TEM observation is extracted using the FIB micro-sampling technique and shaped into a pillar to mount on a tip of a needle stub enabling a multidirectional observation. The technique was applied to the multidirectional observation of the crystal structure of an Si single crystal at atomic resolution. The crystal lattice fringes of the two Si(111) planes with distances of 0.31 nm as well as the lattice fringes of the Si(200) with distances of 0.19 nm were clearly observed.     

Detection and quantification of on-chip phosphorylated peptides by surface plasmon resonance imaging techniques using a phosphate capture molecule

We describe herein a detection and quantification system for on-chip phosphorylation of peptides by surface plasmon resonance (SPR) imaging techniques using a newly synthesized phosphate capture molecule (i.e., biotinylated zinc(II) complex). The biotinylated compound is a dinuclear zinc(II) complex that is suitable for accessing phosphate anions as a bridging ligand on the two zinc(II) ions. The compound was exposed on the peptide array and detected with streptavidin (SA) via a biotin-SA interaction by SPR imaging. In the conventional method using antibody, both anti-phosphoserine and anti-phosphotyrosine antibodies were required for phosphoserine and phosphotyrosine detection, respectively. Detection of the phosphate group by the zinc(II) complex, however, was independent of the phosphorylated amino acid residues. The calibration curve for the phosphorylation ratios was established with a calibration chip, on which phosphoserine-containing peptide probes were immobilized. The peptide probes, which were phosphorylated on the surface by protein kinase A, were detected and quantified by SPR imaging using the zinc(II) complex, SA, and anti-SA antibody. The reaction rate and the kinetics of on-chip phosphorylation were also evaluated with the peptide array. The phosphorylation ratio was saturated at approximately 20% in 2 h in this study.     

TWO REACTION PATH KINETICS IN CO OXIDATION ON ZINC OXIDE

The mode of transient response curves in CO oxidation on ZnO is drastically changed to a false start, an overshoot or an instantaneous mode, depending on the concentration region of CO. These characteristic modes and the anomalous steady state rate data which show maximum and minimum are consistently explained by the two reaction pathways model.     

Strain Softening and Hardening during Superplastic-Like Flow in a Fine-Grained MgAl2O4 Spinel Polycrystal

Superplastic-like flow in a fine-grained MgAl₂O₄ polycrystal exhibits strain softening and hardening, which cannot be ascribed to cavity damage and grain growth during deformation, respectively. The softening and hardening can be related to a change in the internal stress, which depends on a decrease and an increase in the density of the intragranular dislocations, respectively, whose motion contributes to the relaxation of stress concentrations exerted through the predominant deformation mechanism of grain-boundary sliding. In these two regions, the rate of deformation is controlled by the continuous recovery of the dislocations limited by lattice diffusion of the oxygen ions.     

Chemical reactions in foods II

Chemical reactions in foods II     

Computer-assisted automated synthesis. III. Synthesis of substituted N-(carboxyalkyl) amino-acid tert-butyl ester derivatives

A versatile automated synthesis apparatus, equipped with a chemical artificial intelligence, was developed to prepare and isolate a wide variety of compounds. The apparatus was to the synthesis of substituted N-(carboxyalkyl)amino-acids. The apparatus [1,2] is composed of units for performing various tasks,for example reagent supply, reaction, purification and separation, each linked to a control system. All synthetic processes, including washing and drying of the apparatus after each synthetic run, were automatically performed from the mixing of the reactants to the isolation of the products as powders or crystals. The reaction of an amino-acid tertbutyl ester acetic acid salt with a 2-keto acid sodium salt produces an unstable intermediate, Schiff base, which is reduced with sodum cyanoborohydride to give a substituted N-(carboxyalkyl)aminoacid tert-butyl ester sodium salt. The equilibrium and the consecutive reactions were controlled by adding sodium cyanoborohydride using the artificial intelligence software, which contained novel kinetic equations [3] and substituent effects [4].Substitued N-(carboxyalkyl)amino-acid tert-butyl esters, 90 derivatives, were automatically synthesized using the computerassisted automated synthesis apparatus. The syntheses were performed unattended 24 hours a day, except for supplying the raw materials, reagents and solvents. The apparatus is extremely valuable for synthesizing many derivatives of a particular compound. The configurations of the products were determined by circular dichroism measurements.