Microstructure and elemental distribution of americium-containing uranium plutonium mixed oxide fuel under a short-term irradiation test in a fast reactor

In order to investigate the effect of americium addition in MOX fuel on the irradiation behavior, the ‘Am-1’ program is being conducted in the experimental fast reactor Joyo. The Am-1 program consists of two short-term irradiation tests of 10 min and 24 h irradiations and a steady-state irradiation test. The short-term irradiation tests were successfully completed and the post irradiation examinations (PIEs) are in progress. This paper reports on the results of PIEs for Am-containing MOX fuel irradiated for 10 min. MOX fuel pellets containing 3% or 5% Am were fabricated in a shielded air-tight hot cell using a remote handling technique. The oxygen to metal ratio (O/M) of these fuel pellets was 1.98. They were irradiated at peak linear heating rate of about 43 kW m⁻¹. Focus was being placed on migration behavior of Am during the irradiation. The ceramography results showed that structural changes such as lenticular pores and a central void occurred early, within the brief 10 min of irradiation. The results of electron probe microanalysis revealed that the concentration of Am increased in the vicinity of the central void.     

A 10 ns 54×54 b parallel structured full array multiplierwith 0.5 μm CMOS technology

A 54 b×54 b multiplier fabricated in a double-metal 0.5 μm CMOS technology is described. The 54 b×54 b full array is adopted to complete multiplication within one latency. A 10 ns multiplication time is achieved by optimizing both the propagation time of the part consisting of 4-2 compressors and the propagation time of the final adder part. The n-channel pass-transistor circuit and the p-channel load circuit are used at the critical blocks to improve the multiplication speed. This multiplier is intended to be applied to double-precision floating-point data processing based on the IEEE standard up to clock range of 100 MHz     

Structure determination of tubular crystals of membrane proteins. III. Solvent flattening

Solvent flattening is considered to be a principal means for improving the data quality in X-ray crystallography. It could be equally effective for tubular crystals of membrane proteins imaged by electron microscopy because of the large empty space inside the tubes. However, tubular crystals are difficult objects for solvent flattening due to lack of electron diffraction amplitudes. Therefore, solvent flattening was used to align images more accurately and to improve the completeness of the data by reducing contributions of noise in the solvent (+ lipid) region. The methods developed were tested with the tubular crystals of Ca2+-ATPase embedded in amorphous ice. The improvement of the data quality was remarkable when solvent flattening was applied to many individual images before averaging. In this way, noises contaminated in the protein region by contrast transfer function were removed effectively. Solvent flattening was far more powerful than simple averaging described in Part II of this series (K. Yonekura, C. Toyoshima, Ultramicroscopy 84 (2000) 15).     

p57Kip2 regulates actin dynamics by binding and translocating LIM-kinase 1 to the nucleus

p57Kip2 is the only cyclin-dependent kinase (Cdk) inhibitor shown to be essential for mouse embryogenesis. The fact suggests that p57 has a specific role that cannot be compensated by other Cdk inhibitors. LIM-kinase 1 (LIMK-1) is a downstream effector of the Rho family of GTPases that phosphorylates and inactivates an actin depolymerization factor, cofilin, to induce the formation of actin fiber. Here we demonstrate that p57 regulates actin dynamics by binding and translocating LIMK-1 from the cytoplasm into the nucleus, which in turn results in a reorganization of actin fiber. The central region of p57, a unique feature among the Cdk inhibitors, and the N-terminal region of LIMK-1, which contains the LIM domains were essential for the interaction. Expression of p57, but not p27Kip1 or a p57 mutant, with a deletion in the central region was shown to induce marked reorganization of actin filament and a translocation of LIMK-1. Our findings indicate p57 may act as a key regulator in embryogenesis by bearing two distinct functions, the regulation of cell cycle through binding to Cdks and the regulation of actin dynamics through binding to LIMK-1, both of which should be important in developmental procedure.     

Packing-property of pharmaceutical powders. VI. Relationship between compacting progress and measurements variation of apparent density in course of packing of pharmaceutical powders (author''s transl)]

In this study we investigated the relationship between binding of anti-tumor antibodies by polyoma-virus-induced SEYF- a tumor cells and the expression of immune-complex receptors on these cells. It was shown that in vivo propagated cells became progressively coated with IgG. The increase in the IgG coating of SEYF-a cells, occurring during the second week of propagation, was directly correlated with an increase in the coating of cells with potentially cytotoxic anti-tumor antibodies. The activity of these antibodies was demonstrated by cell lysis following addition of exogenous complement. Cell populations propagated in vivo for longer periods (3 weeks or more) became less sensitive to exogenous complement although their IgG coating remained high, and although higher titers of anti-tumor antibodies could be eluted from them. This indicated that antibodies coating young tumor cell populations have the capacity to activate complement whereas those coating older tumor cell populations are incapable of complement activation. Previous findings that SEYF-a cell populations are able to bind unrelated immune complexes were confirmed in the present study. We also found that the capacity of these populations to bind such unrelated complexes decreased with propagation time in vivo. The involvement of anti-tumor antibodies in this phenomenon was indicated by the finding that such antibodies inhibited binding of unrelated immune complexes by young cells but not by old cells. Furthermore, treatments causing dissociation of Ig from the cell surface restored, to some extent, the capacity of anti-tumor antibodies to inhibit immune complex binding by old SEYF-a populations.     

Separation of Am(III) from Eu(III) by extraction based on in situ extractant formation of dithiocarbamate derivatives

A new solvent-extraction technique based on in situ formation of dithiocarbamate derivatives in order to separate Am(III) from Eu(III) was carried out. In this technique, the extractant is formed during the extraction course by the reaction between the organic materials, which are needed to synthesize the extractant. The synthesis of extractant in in situ extractant-formation method was carried out as follows. Di-substituted amine, such as dioctylamine (DOA), dibenzylamine (DBzA) and so on, and carbon disulfide (CS₂) were mixed in organic solvents, such as nitrobenzene, to produce dioctylammonium dioctyldithiocarbamate (DOA⁺·DODTC⁻), dibenzylammonium dibenzyldithiocarbamate (DBzA⁺·DODTC⁻), or so on. These organic solutions are also the organic phase in the solvent extraction, whereas the aqueous phase is 1.00 mol/dm³ (H, Na)NO₃ solution. The elements of Am(III) and Eu(III) were extracted into organic phase from different hydrogen ion concentrations of aqueous phase. The SF of Am(III)/Eu(III) is 3.2 × 10⁴ at pH_eq = 6.25 in DOA–CS₂/nitrobenzene system. This separation technique of Am(III) from Eu(III) by extraction based on in situ extractant formation has the following advantages. (a) It is unnecessary to take the chemical stability of extractant into account for storage purpose, and (b) Am(III) can be completely separated from Eu(III) by a single extraction procedure.     

Differences in Hollow Volumes in Cooked Rice Grains with Various Amylose Contents as Determined by NMR Micro Imaging

The presence of hollows in cooked rice grains found before in the cultivar Koshihikari was confirmed for 4 more cultivars with various amylose contents. The size, shape, and total volume of hollows differed between cultivars. Hollow volumes increased with grain volume and length before 100 °C was reached, but subsequently decreased during prolonged boiling. The previously proposed mechanism, describing sealing by gelatinized starch of cracks formed during soaking, seemed accurate for all 5 cultivars. Based on the hypothetical model of their formation, a relationship between amylose content and hollow formation was assumed. However, no correlation existed between final hollow volume and shape on 1 side and individual parameters such as flour gelatinization and amylose content on the other side.     

Thermal conductivity of BaPuO3 at temperatures from 300 to 1500 K

Polycrystalline specimens of barium plutonate, BaPuO₃, have been prepared by mixing the appropriate amounts of PuO₂ and BaCO₃ followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. The Debye temperature of BaPuO₃ was determined from the sound velocity and lattice parameter measurements. The elastic moduli were also determined from the longitudinal and shear sound velocity. The thermal conductivity of BaPuO₃ was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by a laser flash method in vacuum. The thermal conductivity of BaPuO₃ was roughly independent of the temperature and was almost the same magnitude as that of BaUO₃. This was markedly lower than the conductivities of other perovskite type oxides and was about one-tenth that of UO₂ around room temperature. The temperature dependence of the thermal conductivity of BaPuO₃ was found to be quite similar to that of BaUO₃.