Migration of minor actinides and lanthanides in fast reactor metallic fuel

Minor actinides (MA) and lanthanides (LA) migration to the cladding in fast reactor metallic fuel is a concern because of their reaction with the cladding material. MA and LA migration test results are analyzed and reactions with the cladding are characterized. Remedies for reducing MA and LA migration and reaction with cladding are reviewed. A possible method is proposed that includes the addition of a compound forming element such as indium or thallium in fuel. These elements preferentially form stable compounds with MA and LA and should therefore reduce migration of MA and LA. As an intrinsic solution to the issue, the feasibility of the use of U-Pu-Mo alloy as fuel is studied. Unlike U-Pu-Zr, U-Pu-Mo consists of a single phase at typical fuel operation temperatures, and should have negligible fuel constituent redistribution and reduce MA and LA migration.     

Production of Residue-Free Nanoparticles by Atomization of Aqueous Solutions

It has been difficult to produce physically and chemically pure nanoparticles from a particle solution in deionized (DI) water by atomization due to residue from impurities in the DI water. In this study, we show that further purification of DI water by reverse osmosis (RO) membrane filtration under high pressure (900 psi) substantially reduces solvent impurities when submicrometer and nanosized particles are atomized. Comparison of size distributions among several types of DI water showed that the production of residual particles significantly decreased by a factor of ～11 (by number) after the RO filtration of regular DI water from commercially available DI water. Mixing states of aerosolized particles produced from particle solutions were examined by using the hygroscopicity tandem differential mobility analyzer technique and transmission electron microscopy/energy dispersive spectroscopy. We found that residual particles were externally mixed with particles of interest during the aerosolization and drying process and that impurities in DI water can beadded onto the target particles (i.e., internally mixed). By removing impurities in DI water by the RO filtration, the effect of impurities for the production of clean nanoparticles was significantly reduced, suggesting that the atomization method can still be a promising tool to produce pure nanoparticles in a simple and inexpensive way.

Copyright 2012 American Association for Aerosol Research     

Local stiffness control for reducing vehicle interior noise by using FRF-based synthesis method

This paper explores the feasibility of estimating the interior noise of a vehicle compartment when the attachment stiffness (i.e., the local stiffness of the mounting point at which operational force is applied) is altered. In order to change the local stiffness of the vehicle body, it was assumed that the local stiffness could be changed by attaching some additional systems to the vehicle body. The frequency response function (FRF)-based synthesis method is used herein to estimate the change in the local stiffness of the modified vehicle body. In addition, the change in the noise transfer function (NTF) can also be estimated using this method. Since the operational force transmitted from the source excitation to the body attachment is required to predict the interior noise of the vehicle body in the operational condition, a transfer path analysis (TPA) technique was performed. Various vehicles and additional systems were utilized to estimate the dynamic properties of the modified vehicle body. Results indicated that the synthesis technique is an appropriate method to estimate the change in the local stiffness and NTF of the modified vehicle body. The results also show that the interior noise of the body can be estimated accurately by using the synthesis technique and TPA procedure when the vehicle body is locally modified.     

A high‐luminous‐efficacy PDP having multi‐anodes for reduction of ionic effect (MARI)

Abstract— We propose a PDP having a new structure and driving scheme. An auxiliary electrode was inserted between X and Y electrodes. Driving and discharge stability was determined using a test panel. A 42‐in. SD (852 × 480) panel and a 42‐in. HD (1366 × 768) panel were also made having this new structure, and we verified the increase in luminous efficacy and the reduction of ionic losses. We achieved a luminous efficacy of 2.35 lm/W in an SD panel and 1.97 lm/W in a HD panel. Finally, we investigated the characteristics and merits of the new structure.     

Storage of multiple holograms of equal diffraction efficiency in a phase-code multiplexing system

Computer simulations of 8-, 32-, and 128-bit phase-code multiplexing systems are presented, and exposure schedules are obtained numerically for equal diffraction efficiency. An analytic prediction of the exposure schedule is derived as a double exponential function that can be applied to the three different systems for variation of diffraction efficiency of less than +/- 13.5%. Eight holograms were experimentally recorded in a BaTiO3 crystal according to our exposure schedule and also to conventional schedules, which had originally been derived for an angle-multiplexing system. It is shown that the experimental data agree well with the computer simulations.     

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MCORE: a context-sensitive recommendation system for the mobile Web

Abstract: Recommendation systems for the mobile Web have focused on endorsing particular types of content to users. Today, mobile service providers have a more direct recommendation channel, namely the short messaging service. Therefore, mobile service providers should consider both the timing and context of recommendation messages (push messages) that are sent to users. Mobile service providers can learn context-specific user preferences by analysing mobile Web use logs and user responses to push messages. In this paper, we present a context-sensitive recommendation system that can be used to select the optimal context in which to send recommendation messages. We call this system the mobile context recommender system (MCORE). We compared user responses to push messages delivered in and out of suitable contexts as determined by MCORE. The precision of push messages delivered within a suitable context was higher than that of messages delivered outside of one.     

Chemical analysis of fuel crud obtained from Korean nuclear power plants

Crud samples were obtained from two different kinds of used fuels in PWRs. The constituent elements were analysed according to the shapes of crud particles by SEM and EPMA. The principal elements of octahedral crystal particles were identified as Ni and Fe, where the ratio (Fe/Ni) was approximately 2. The major element of the observed needle-like structures was determined to be Ni. In addition, Zr composed the main element of particles shaped like broken fragments sized at 10-50 μm in diameter. The round particles less than 20 μm in diameter were identified as Si-containing compounds. We also found the Zn element in a series of fuel crud samples obtained from a plant. Zn was mainly detected in the hard crud, inner layer of crud, but not on the surface of crud. It was observed that there is an inverse relationship between the Ni and Zn contents in the hard crud.     

Novel Bacterial Production of Two Different Bioactive Forms of Human Stem-Cell Factor

Human stem-cell factor (hSCF) stimulates the survival, proliferation, and differentiation of hematopoietic cells by binding to the c-Kit receptor. Various applications of hSCF require the efficient and reliable production of hSCF. hSCF exists in three forms: as two membrane-spanning proteins hSCF248 and hSCF229 and truncated soluble N-terminal protein hSCF164. hSCF164 is known to be insoluble when expressed in Escherichia coli cytoplasm, requiring a complex refolding procedure. The activity of hSCF248 has never been studied. Here, we investigated novel production methods for recombinant hSCF164 and hSCF248 without the refolding process. To increase the solubility of hSCF164, maltose-binding protein (MBP) and protein disulfide isomerase b’a’ domain (PDIb’a’) tags were attached to the N-terminus of hSCF164. These fusion proteins were overexpressed in soluble form in the Origami 2(DE3) E. coli strain. These solubilization effects were enhanced at a low temperature. His-hSCF248, the poly-His tagged form of hSCF248, was expressed in a highly soluble form without a solubilization tag protein, which was unexpected because His-hSCF248 contains a transmembrane domain. hSCF164 was purified using affinity and ion-exchange chromatography, and His-hSCF248 was purified by ion-exchange and gel filtration chromatography. The purified proteins stimulated the proliferation of TF-1 cells. Interestingly, the EC₅₀ value of His-hSCF248 was 1 pg/mL, 100-fold lower than 9 ng/mL hSCF164. Additionally, His-hSCF248 decreased the doubling time, increased the proportion of S and G2/M stages in the cell cycle, and increased the c-Myc expression at a 1000-fold lower concentration than hSCF164. In conclusion, His-hSCF248 was expressed in a soluble form in E. coli and had stronger activity than hSCF164. The molecular chaperone, MBP, enabled the soluble overexpression of hSCF164.