Search

The nuclear field shift (NFS) is an isotope shift in atomic energy levels caused by a combination of differences in nuclear size and shape and electron densities at the nucleus. The effect of NFS in isotope fractionation was theoretically established by Bigeleisen in 1996 [Bigeleisen J. (1996) J. Am. Chem. Soc. 118:3676–3680] and has been analytically measured in laboratory chemical exchange reactions. More recently, some isotopic variations of heavy elements (Hg, Tl, U) measured in natural systems as well as isotopic anomalies measured for lower-mass elements in meteorites have been attributed to the NFS effect. These isotopic variations open up new and exciting fields of investigations in Earth sciences. In this paper, we review the different natural systems in which NFS has been proposed to be the origin of isotopic variations.

In order to examine easily synthetic conditions of uranyl molybdate, UO 2 MoO 4 , used for the reprocessing process study of spent nuclear oxide fuels in alkaline molybdate melts, the uranium molybdate compounds were produced from U 3 O 8 powder and anhydrous MoO 3 reagent. The results of having investigated them in solid state by using X-ray diffractometry and Raman spectrometry, it was confirmed that UO 2 MoO 4 could be synthesized by heating mixed powder of U 3 O 8 and MoO 3 with stoichiometric mole ratio at 770 °C for 4 h under air atmosphere. Moreover, adding this UO 2 MoO 4 into Li 2 MoO 4 Na 2 MoO 4 eutectic melt, most of the dissolved uranium species in the melt were observed as hexa–valent uranyl ions by absorption spectrophotometry.

Coarse-grained (CG) and ultrafine-grained (UFG) pure aluminum samples fabricated by equal channel angular pressing (ECAP) were cyclically deformed at 77K under constant plastic strain amplitude. Monotonic tensile tests were performed at 300 and 77K soon after the fatigue tests. In spite of the increase in the tensile strength of fatigued CG Al, tensile ductility decreased remarkably in comparison to that of as-annealed CG Al. On the other hand, the ultimate tensile strength (UTS) and tensile ductility of UFG Al were much higher at 77K than those at 300K. Furthermore, UFG Al at 77K maintained high UTS and high tensile ductility even after fatigue tests. Microstructural observation has revealed that dislocation wall structure formed in fatigued CG Al persists after the monotonic tensile tests. However, dislocation wall structure formed in fatigued UFG Al disappeared during early stages of monotonic tensile tests at both 300 and 77K. These results indicate that the dislocation wall structure in UFG Al is unstable against succeeding monotonic tensile deformation. [doi:10.2320/matertrans.M2012280]

The patient was a 58-year-old man with advanced gastric cancer with multiple liver metastases. He received TXL/TS-1 therapy during February 2009, but treatment was stopped immediately when he developed anorexia, diarrhea, and numbness in his fingers. Therefore, only TS-1 was administered. Following treatment initiation, tumor marker levels promptly dropped. The gastric lesion disappeared and, to date, only a slight scar remains since April 2010. Similarly, liver metastases have not been detected since August 2011. There has been no lesion progression for 6 years since the start of the chemotherapy.

We describe a technique of S isotope analysis in sulfate form with the first separation stage involving anion-exchange and the second stage of mass-spectrometric analysis by MC-ICP-MS using standard-sample-standard bracketing. Ammonium in 1 : 1 stoichiometric proportion with sulfate was used to improve transmission and stability and to avoid cone and membrane clogging by condensable species. The working resolution of similar to 9000 allowed the main interferences, notably (SH)-S-32 on S-33, to be resolved. The matrix effect caused by phosphorus present in biological samples is negligible for S/P ratios \textgreater= 10: our chemical protocol allows S/P \textgreater= 150 to be routinely achieved. Replicate measurements of S standard solutions give values of isotopic abundances within errors of accepted values and demonstrate a reproducibility of +/- 0.10 parts per thousand for delta S-34 and +/- 0.15 parts per thousand for delta S-33 (2s). The technique is adequate for quantities as small as 10 nanomoles. We investigated the delta S-34 of 110 samples of cancer patients and 10 samples of rheumatoid arthritis patients. We avoided the use of blood collection tubes with sulfate-containing heparin. Sulfur in serum is transported by albumin and fibrinogen. Most serum and plasma delta S-34 values fall within a narrow interval of similar to 1 parts per thousand around a mean delta S-34(VCDT) of similar to 6.0 parts per thousand. The delta S-34 values of total blood, serum, and plasma are very similar. Despite the short turnover time of albumin and fibrinogen, S is surprisingly well regulated. Subtle variations of 0.2-0.3 parts per thousand around the mean value can be assigned to sex and age, with sulfur in male and adult samples tending to be heavier than in their female and juvenile counterparts. This narrow range of variations across the spectrum of a large number of individuals not selected for controlled dietary habits seems paradoxical. In general, breast and prostate cancer and rheumatoid arthritis have very little effect on the average serum delta S-34, but increase the scatter of values. We confirm that the serum of patients affected by liver cancer and other pathologies is depleted of albumin-born sulfur. While sulfur in the serum of patients with non-malignant liver pathologies tends to be isotopically light, the serum delta S-34 of medicated hepatocellular carcinoma patients tends to be at the high end of control values.

For the purpose of determining a surface deposition density on soil for radio-cesiums, a CdZnTe (CZT) semiconductor detector whose crystal has dimensions of 1 cm cubic was applied to the in situ environmental radioactivity measurement in deeply contaminated areas in Fukushima region. Even in high–dose rate areas where pulse height spectra weren’t able to be properly obtained by the conventional high-purity Ge (Hp-Ge) semiconductor detector, proper pulse height spectra were obtained by the CZT detector with certain accuracy. Results of deposition density on soil for 134Cs and 137Cs derived from net peak areas by the CZT detector seemed consistent, comparing with those measured by the Japanese government. Air kerma rates were estimated by the same pulse height spectra for determining surface deposition density on soil for radio-cesiums. Estimated results showed almost the same values as obtained by the NaI(Tl) scintillation survey meter. The results indicate that the CZT detector can be applied to rapid and simple in situ gamma ray radioactivity measurement in higher–dose rate areas whose dose rates exceed several tenth μSv h−1. The study also strongly supports that the CZT detector is one promising candidate for the detector to be used for checking the effect of decontamination works and for long-term monitoring in heavily contaminated areas.

For the assessment of Fukushima Daiichi Nuclear Power Plant accident, the applicability of the thermal ionization mass spectrometry (TIMS), which is a type of mass spectrometry, was studied. For the study of the recovery/analysis method of cesium and strontium, at first, the radioactive cesium and strontium were generated by the irradiation of natural uranium at KUR. After this study, the applicability of this method to the environmental samples obtained in Fukushima prefecture was verified.

The isotopic ratios of radioactive cesium derived from the Fukushima accident were determined by γ-spectrometry and thermal ionization mass spectrometry (TIMS). In order to ascertain the initial ratios at the time of the accident, environmental samples collected during 2011 were used for the analysis. Soil, litter, and seaweed were incinerated, and the cesium contained therein was adsorbed into ammonium phosphomolybdate powder. The cesium in the seawater was adsorbed into AMP-PAN resin (Eichrom Technologies, LLC); its recovery ratio was almost one without the carrier being added. Incinerated samples and the AMP-PAN resin were then measured by γ-spectrometry. The cesium solution recovered from adsorbers was subjected to TIMS measurements. The isotopic ratios of 134Cs/137Cs and 135Cs/137Cs were found to be independent of the type of sample in question, as well as the sampling location; the ratios were 0.07 and 0.36 (decay correction: 11 March 2011), respectively, which differ from the results of atmospheric nuclear tests (i.e., 0 and 2.7, respectively). This difference in the ratio of 135Cs/137Cs will contribute to estimations of the origin of radioactive contamination in the future.

Accumulative roll bonding (ARB) was applied to three FCC metals, such as Al, Cu and Ni. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were made to evaluate dislocation density ? of the ARB processed FCC metals. The values of ? of ARB processed Cu and Ni increased rapidly after the first ARB cycle, and then, tend to saturate after the following cycles. The evaluated values of ? of both ARB 8-cycled Cu and Ni using DSC were around 2?1015 m?2. Whereas, those using XRD were around 5?1014m?2 (for Cu) and 3?1014m?2 (for Ni). Although the ? values depend on the measurement methods, the trends that DSC values are about an order of magnitude higher than XRD values seem to be common. In the case of Al, dislocation density evaluated using XRD increased to about 1?1013m?2 at the first ARB cycle, and then gradually decreased to about 1?1012m?2 with increasing number of ARB cycles.

This review examines recent applications of stable copper, zinc and sulfur isotopes to medical cases and notably cancer. The distribution of the natural stable isotopes of a particular element among coexisting molecular species varies as a function of the bond strength, the ionic charge, and the coordination, and it also changes with kinetics. Ab initio calculations show that compounds in which a metal binds to oxygen- (sulfate, phosphate, lactate) and nitrogen-bearing moieties (histidine) favor heavy isotopes, whereas bonds with sulfur (cysteine, methionine) favor light isotopes. Oxidized cations (e.g., Cu(II)) and low coordination numbers are expected to favor heavy isotopes relative to their reduced counterparts (Cu(I)) and high coordination numbers. Here we discuss the first observations of Cu, Zn, and S isotopic variations, three elements closely related along multiple biological pathways, with emphasis on serum samples of healthy volunteers and of cancer patients. It was found that heavy isotopes of Zn and to an even greater extent Cu are enriched in erythrocytes relative to serum, while the difference is small for sulfur. Isotopic variations related to age and sex are relatively small. The 65Cu/63Cu ratio in the serum of patients with colon, breast, and liver cancer is conspicuously low relative to healthy subjects. The characteristic time over which Cu isotopes may change with disease progression (a few weeks) is consistent with both the turnover time of the element and albumin half-life. A parallel effect on sulfur isotopes is detected in a few un-medicated patients. Copper in liver tumor tissue is isotopically heavy. In contrast, Zn in breast cancer tumors is isotopically lighter than in healthy breast tissue. 66Zn/64Zn is very similar in the serum of cancer patients and in controls. Possible reasons for Cu isotope variations may be related to the cytosolic storage of Cu lactate (Warburg effect), release of intracellular copper from cysteine clusters (metallothionein), or the hepatocellular and biosynthetic dysfunction of the liver. We suggest that Cu isotope metallomics will help evaluate the homeostasis of this element during patient treatment, notably by chelates and blockers of Cu trafficking, and understand the many biochemical pathways in which this element is essential.

Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (Tl-203 and Tl-205) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ion-exchange chemistry, the isotope ratio of Tl-205/Tl-203 in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation > 1 aEuro degrees was found. Electronic structures of possible Tl species (hydrated Tl+, Tl3+, and Tl chlorides) were calculated by ab initio methods, and the isotope fractionation factor was theoretically obtained. The isotope fractionation via intramolecular vibrations was calculated to be much smaller than the experimental result. The isotope fractionation via isotopic change in nuclear volume, named the nuclear field shift effect, was calculated to be > 1 aEuro degrees in Tl(I)-Tl(III) redox systems and/or ligand exchange systems of Tl(III). The nuclear field shift effect was found to be the major origin of Tl isotope fractionation.

As an analytical application for pyrochemical reprocessing using molten salts, quantitative analysis of uranium and lanthanides by UV/Vis/NIR absorption spectrophotometry was performed. Electronic absorption spectra of LiCl–KCl eutectic at 773 K including trivalent uranium and eight rare earth elements (Y, La, Ce, Pr, Nd, Sm, Eu, and Gd as fission product elements) were measured in the wavenumber region of 4,500–33,000 cm−1. The composition of the solutes was simulated for a reductive extraction condition in a pyroreprocessing process for spent nuclear fuels, that is, about 2 wt% U and 0.1–2 wt% rare earth elements. Since U(III) possesses strong absorption bands due to f–d transitions, an optical quartz cell with short light path length of 1 mm was adopted in the analysis. The quantitative analysis of trivalent U, Nd, Pr, and Sm was possible with their f–f transition intensities in the NIR region. The analytical results agree with the prepared concentrations within 2σ experimental uncertainties.

The neutron neutron-capture cross cross-sections of 244Cm and 246Cm were measured by the time-of-flight method in the energy range of 1–300 300 eV with an array of large germanium detectors in the Accurate Neutron-Nucleus Reaction measurement InstrumentANNRI at Material and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research ComplexJ-PARC/MLF. The 244Cm resonances at around 7.7 and 16.8 8 eV and the 246Cm resonances at around 4.3 and 15.3 3 eV were observed in the capture reactions for the first time. The uncertainties of the obtained cross cross-sections are 5.8% at the top of the first resonance of 244Cm and 6.6% at that of 246Cm. The rResonance analyses were performed for low-energy ones using the code SAMMY. The prompt γ-ray spectra of 244Cm and 246Cm were also obtained. Eight and five new prompt γ-ray emissions were observed in the 244Cm(n, γ) and 246Cm(n, γ) reactions, respectively.

The coordination circumstances and redox reactions of UO2 2+ in the aqueous solution concentrated by calcium chloride, such as CaCl2·6H2O (6.9 M CaCl2), were studied by Raman spectroscopy and electrochemical methods. The frequency of the O=U=O symmetrical stretching vibration suggested that the complex formation of UO2 2+ with Cl− leads to the weakening of U=O bond. In the electrochemical measurements, two-step cathodic currents were observed at −0.090 and −0.4 V (vs. Ag|AgCl) corresponding to the reduction of UO2 2+ to UO2 + and that of UO2 + to UO2, respectively. It was found that UO2 + formed at first cathodic current was disproportionated to form UO2 2+ and UO2. The UO2 was identified by X-ray diffraction analysis. Electrolytic deposition of UO2 was observed in 6.9–4.7 M CaCl2 and in 14 M LiCl. When small amount of proton, i.e., 0.005 M was coexisted in 6.9 M CaCl2, UO2 2+ was reduced to form U4+ instead of UO2.

The thermodynamic stability of Ln(III) (Ln: La, Ce, Pr, Tb, and Er) and U(III) complexes in LiCl–KCl system at 923 K was studied by electrochemical techniques. The Gibbs free energy change of the Ln3+/Ln0 and U3+/U0 redox reactions, Δ G 3 / 0 ∘ ′ , was investigated under various mole fraction of KCl, χK = 0–0.65. In general, Δ G 3 / 0 ∘ ′ increased linearly with the decrease of χK due to the distortion of octahedral symmetry of LnCl 6 3 - and UCl 6 3 - , but a few exceptions were found for lighter Ln elements, e.g., La and Ce, at smaller χK of 0–0.2. The discrepancy suggests an increase of the number of Cl− ions around La3+ and Ce3+.

AC u­3.0mass%Co alloy was heat-treated by a method named “short-cut aging”. Incoherent fcc Co precipitates of about 200nm in size formed in an fcc Cu matrix were observed with conventional and ultra-high-voltage transmission electron microscopes. Although the Co precipitates had shapes similar to a regular octahedron composed of {111} of the Cu matrix, small deviations from the regular octahedron were

It is known that pure metals having ultrafine grains (UFGs) exhibit softening and grain coarsening at temperatures about one third of the melting temperatures. When such low-temperature annealing (LTA) of UFG copper is conducted under uniaxial tensile stress, the retardation of the softening is found to occur compared with that without stress. Observations of the microstructure and texture analysis indicate that the softening and the grain coarsening are attributed to recrystallization, and the presence of uniaxial tensile stress during LTA retards recrystallization. High voltage transmission electron microscopy revealed that the dislocation density of UFG copper annealed under uniaxial tensile stress is lower than that after LTA without stress. The retardation of recrystallization is associated with the reduction of the dislocation density of unrecrystallized UFG copper induced by dynamic recovery. [doi:10.2320/matertrans.MD201117]

We proposed a quantum-circuit analog of dynamical Casimir effect by using a superconducting quantum circuit. The proposed system can be regarded as a time-dependent harmonic oscillator, resulting in squeezing of a quantum flux trapped in the system. Here we develop our theory taking into account finite temperatures, in order to contact with experiments like circuit-QED. We present numerical results of occupation probability distributions produced by non-stationary boundary effect at various temperatures.

I investigated presence of taking medicine and a taking medicine continuation rate to evaluate how to use the regional post-referral treatment plan about the osteoporosis treatment for the secondary hip fractures prevention. I evaluated the present conditions of the regional post-referral treatment plan that I considered from acute care hospital points of view. The osteoporosis treatment that continued and expanse of the osteoporosis liaison service are necessary to quit the chain of the osteoporotic fracture. It is necessary to improve a taking medicine continuation rate.

In order to monitor stability of doses from the four components such as thermal, epi-thermal, fast neutron and gamma-ray during BNCT irradiation, we are developing a multiionization-chamber system. This system is consisted of four kinds of ionization chamber, which have specific sensitivity for each component, respectively. Since a suitable structure for each chamber depends on the energy spectrum of the irradiation field, the optimization study of the chamber structures for the epi-thermal neutron beam of cyclotron-based epi-thermal neutron source (C-BENS) was performed by using a Monte Carlo simulation code “PHITS” and suitable chamber-structures were determined.

Isotope fractionation of Zn between aqueous sulfide, chloride, and carbonate species (Zn2+, Zn(HS)2, Zn ( HS ) 3 - , Zn ( HS ) 4 2 - , ZnS(HS)−, ZnCl+, ZnCl2, ZnHCO 3 + , and ZnCO3) was investigated using ab initio methods. Only little fractionation is found between the sulfide species, whereas carbonates are up to 1‰ heavier than the parent solution. At pH > 3 and under atmospheric-like CO2 pressures, isotope fractionation of Zn sulfides precipitated from sulfidic solutions is affected by aqueous sulfide species and the δ66Zn of sulfides reflect these in the parent solutions. Under high P CO 2 conditions, carbonate species become abundant. In high P CO 2 conditions of hydrothermal solutions, Zn precipitated as sulfides is isotopically nearly unfractionated with respect to a low-pH parent fluid. In contrast, negative δ66Zn down to at least −0.6‰ can be expected in sulfides precipitated from solutions with pH > 9. Zinc isotopes in sulfides and rocks therefore represent a potential indicator of mid to high pH in ancient hydrothermal fluids.

Palladium complexation in concentrated nitric acid solutions was studied by UV/Vis absorption spectrophotometry. The ionic strength of the solutions was fixed to I = 1, 3, or 5 mol dm−3 (M) by mixing of HNO3 and HClO4. The major palladium species were found to be Pd2+, PdNO3 +, and Pd(NO3)2. The formation constant of PdNO3 + was determined to be β 1 = 1.32 (I = 1 M), 1.49 (I = 3 M), or 1.47 (I = 5 M), while that of Pd(NO3)2 to be β 2 = 0.45 (I = 3 M) or 0.14 (I = 5 M).

Lithium orthosilicate and lithium aluminate are the candidates of the breeder material of the tritium-breeding blanket. To enhance the rate of tritium release from these breeder materials, 0.2 wt.% of palladium was impregnated into the breeder materials by the incipient wet impregnation method. The lithium orthosilicate and the lithium aluminate pebbles with or without Pd were irradiated in the Kyoto university research reactor, and out-of-pile annealing experiments were performed. When the breeder materials were deposited with a catalytic additive, such as Pd the ratio of the tritium discharged in the molecular form of tritium (HT) increased. It was also found that the amount of the tritium discharged from the lithium orthosilicate pebbles with a catalytic additive at the low temperatures is greater compared with lithium aluminate.

The coordination of U4+ and Th4+ in concentrated CaCl2 solutions is studied by U and Th L III edge extended X-ray absorption fine structure (EXAFS) spectroscopy. With the decrease of concentration of CaCl2 from 6.9 to 4 M, the Cl− ion coordination number N Cl in the U4+ coordination sphere decreases from 3.4 to 1.3, while the hydration number N O increases from 4.5 to 6.7. The combined coordination number N O+NCl of U4+ in concentrated Cl− solution (8.0), is lower than that in 1.5 M perchloric acid aqueous solution (9.0). For Th4+, the decrease of concentration from 6.9 to 4 M CaCl2, the coordination number N Cl in the Th4+ coordination sphere decreased slightly from 1.9 to 1.5, while coordination number N O increased from 7.6 to 8.8. The N O+NCl of Th4+ in concentrated Cl− solution (9.0), is similar to that in 1.5 M perchloric acid. The bond distance of U–Cl (2.67 Å), is shorter than that of Th–Cl (2.76 Å), because of low coordination number N O to U4+. By adding HCl into the system, the U4+ and Th4+ coordination sphere is unchanged. The coordination structures of U4+ and Th4+ in concentrated LiCl is also discussed.

Absorption spectra of uranium species dissolved in molten lithium molybdate–sodium molybdate eutectic of 0.51Li2MoO4–0.49Na2MoO4 mixture at 550 ºC were measured by UV/Vis/NIR spectrophotometry, and their redox reactions were investigated by cyclic voltammetry. We found that the major ions of uranium species dissolved in the melt were uranyl penta-valent. After purging dry oxygen gas into the melt, penta-valent species were oxidized to the uranyl hexa-valent. In the cyclic voltammetry of the melt without uranium species, it was confirmed that the lithium-sodium molybdenum oxide compounds were deposited on the working electrode at the negative potential and the lithium molybdenum oxide compounds were deposited on the counter electrode at positive potential. When UO2 was dissolved into the melt, the reductive reaction of the uranium species was observed at the reductive potential of the pure melt. This suggests that the uranium species dissolved in the melts could be recovered as mixed uranium-molybdenum oxides by electrolysis.

The thermodynamic stability of Nd(III) complexes was studied by electrochemical techniques for molten binary mixtures composed of LiCl and an alkali earth chloride, CaCl 2 , SrCl 2 , or BaCl 2 at 923 K. The Gibbs free energy change of formation of Nd(III) in the melts was determined. The obtained values showed a good correlation with the polarizing power of solvent cations. The Nd(III) complex was more stable in the melts with low polarizing power. The electronic absorption spectrum of the hypersensitive f – f transition of Nd 3+ was investigated to obtain information about the structural change of the NdCl 6 3 - complex. The estimated oscillator strength of the 4 G 5/2 , 2 G 7/2 ← 4 I 9/2 transition and the degree of the energy splitting in electronic energy levels showed different trends upon the polarizing power for each of added alkali earth chloride. This indicates that the coordination environments further from second neighbors could have significant impact on the electronic energy levels of Nd(III) in the mixtures including alkali earth cations.

Annihilation behaviors of irradiation defect and, correlation of these behaviors with deuterium trapping and desorption in gamma-ray irradiated Li2TiO3, which is one of the candidates for tritium b...

The redox reactions and coordination circumstances of uranium trivalent ions in molten LiCl–CsCl mixtures were investigated by cyclic voltammetry and spectrophotometry. The formal redox potential, E °′(U 3+ |U), in LiCl–CsCl mixtures with the CsCl mole fraction of 0.2 was more positive than that in LiCl melt. The CsCl system showed the most negative E °′(U 3+ |U). The electronic absorption spectra of U 3+ in LiCl–CsCl mixtures showed that the intensities of absorption peaks decreased with the increase of CsCl mole fraction. The oscillator strength of the hypersensitive f – f transition, f , decreased with the increase of CsCl mole fraction.

Distribution behavior of Ce(III), Am(III), and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO3)2·RH2O or molten calcium chloride hydrate CaCl2·RH2O was studied radiochemically. In Ca(NO3)2·RH2O systems, maximum separation factors of Ce and Cm to Am were observed to be 12 (Ce/Am) and 1.7 (Cm/Am). The distribution ratios of these elements increased with the decrease of water activity in the hydrates, and the extractabilities at the water deficient region was less sensitive compared to those at the water abundant region. This trend was similar to the coordination circumstance change observed in electronic absorption spectra of Nd(III) in the hydrates.

The thermodynamic stability of Nd(III) complex in various molten alkali chlorides at 923 K was studied by electrochemical analysis. The standard Gibbs free energy change of the Nd3+ formation, Δ G 3 / 0 ∘ , decreased by adding MCl (M = Na, K, Rb, or Cs) into LiCl. The Nd(III) complex was more stable in an alkali chloride mixture with larger averaged cationic radius. This means that the stability is controlled by the polarizing power of solvent cations. The electronic absorption spectrum of the hypersensitive f–f transition of Nd3+ was investigated to know the change in its coordination environments. The oscillator strength of the 4G5/2, 2G7/2 ← 4I9/2 transition and the degree of the energy splitting in electronic energy levels were estimated. The results suggested that the octahedral symmetry of the NdCl63− complex was more distorted in the melt with higher LiCl content, and the distortion was depressed by decreasing the polarizing power of solvent cations. The local structure around Nd3+ was significantly correlated with the thermodynamic stability of the Nd(III) complex in molten alkali chlorides.

The redox behavior of Eu2+ and Eu3+ in the LiCl–KCl eutectic at 773 K was investigated. Since the equilibrium potential of the melt is very close to the redox potential of the Eu3+|Eu2+ couple, the Eu2+ and Eu3+ species coexist. Quantitative analysis of Eu2+ and Eu3+ was performed by spectrophotometry and by potentiometry. Under the coexistence of Eu2+ and Eu3+, potentiometric titration of Eu ion using a yttria-stabilized zirconia membrane electrode (YSZME) was performed by changing the concentration of O2−. The formation of the europium oxychloride, EuOCl, was confirmed by X-ray diffraction analysis, whiles no precipitation of the oxides, EuO and Eu2O3, was found. The equivalent point of the EuOCl formation (x = [O2−]added/[Eu]total) was shifted to a smaller value from the theoretical value (x = 1) due to the coexisting Eu2+. The contribution of the coexisting Eu2+ to the formation of EuOCl was estimated by using [Eu2+]/[Eu3+] as determined by potentiometry and this was subtracted from the titration data. The solubility product of EuOCl was determined to be pks(EuOCl) = 7.81 ± 0.10.

Using a single crystal of a Cu–6 mass% Ag alloy aged at 723 K for various times, nano-sized Ag precipitates in a Cu matrix were observed by conventional and ultra high-voltage transmission electron microscopes. The nano-sized Ag precipitates with a radius of about 5 nm had a nearly spherical shape. The shape change from the nearly spherical shape to the {111} octahedral shape occurred with increasing the size of the Ag precipitates to 11 nm. Elastic states of the Ag precipitates were evaluated by observing moire fringes formed between the Ag precipitates and the Cu matrix. The origin of the shape change of the nano-sized Ag precipitates was discussed by considering the sum of elastic strain energy and interfacial energy.

Effects of Si addition on mechanical properties of severely deformed copper by accumulative roll-bonding (ARB) have been investigated. Tensile tests and strain-rate jump tests have been carried out at room temperature. For annealed coarse-grained polycrystals, the difference in yield stress σ 0.2 between pure copper and a Cu–1.64at.%Si alloy was only about 15 MPa while the difference became 170 MPa after the ARB process by six cycles. The strain-rate sensitivity m of pure copper increased with increasing the number N of the ARB cycles for N ≥ 5. However, the increase in m becomes less significant for Cu–Si alloys. These findings have been discussed in terms of thermally activated dislocation processes.

目的・方法:POSSUMは1991年にイギリスで開発されたが（以下，original POSSUM），術後合併症の過剰予測で日本の実情に合わないとされ，2007年にHiroshima-POSSUM（以下，H-POSSUM）が開発された．島根県の多施設消化器手術データベースに集積された1,246例（2002年から2010年）の前半622症例からロジスティク回帰分析にてShimane-POSSUM（以下，S-POSSUM）を導き，後半624症例における有用性を観察された発生率の予測されたそれに対する比（以下，O/E比）の比較とROC解析を用いて，original POSSUM，H-POSSUMと比較した．結果:術後合併症率ではO/E比はoriginal POSSUM 0.52，H-POSSUM 0.70，S-POSSUM 0.86であり，手術直接死亡率でも各々0.09，0.25，0.46と，S-POSSUMが最も1に近かった．ROC解析では，術後合併症率ではAUCは各々0.666，0.672，0.672，手術直接死亡率では，0.817，0.829，0.836と3者同等であった．結論:当地域の消化器手術の合併症予測にはS-POSSUMが最も有用であった．

Nickel plays a central role as an enzyme co-factor in the metabolism of methanogenic Archaea. Methanogens can fractionate Ni isotopes during assimilation, opening the possibility of using the stable isotopic composition of Ni as a biomarker. However, other sources of Ni isotopic variations need to be evaluated before one can establish Ni isotopes as an unambiguous tracer of methanogenesis in the rock record. Equilibrium exchange of Ni between the different species present in the ocean is a potential source of isotopic fractionation. Through controlled laboratory experiments and theoretical calculations, we quantify equilibrium Ni isotope fractionation between different species relevant to the modern and ancient ocean: Ni(H2O)62+, Ni(H2O)182+, NiOH(H2O)5+, Ni(OH)2(H2O)4, NiCl(H2O)5+, cis-NiCl2(H2O)4, trans-NiCl2(H2O)4, NiHS(H2O)5+, Ni(HS)2(H2O)4, NiSO4(H2O)4, NiHCO3(H2O)4+, NiCO3(H2O)4, and organic ligands (crown ether and oxalic acid). The magnitude of ligand-controlled Ni isotopic fractionation, approximately 1.25‰/amu (2.5‰ for the 60Ni/58Ni ratio), is similar to that previously measured in cultures of methanogenic Archaea.

Ultrafine-grained (UFG) Al of 99.98∼99.99% purity was fabricated by equal channel angular pressing. Fully reversed tension-compression low-cycle fatigue tests were carried out under plastic strain control at various temperatures between 83 K and 300 K. At 300 K, UFG Al showed rapid cyclic softening. As test temperature decreased, cyclic softening became less significant and at 83 K, UFG Al showed cyclic hardening till saturation. Formation of shear bands and development of dislocation structure were the characteristic features of fatigued specimens. As test temperature decreased, the area fraction of shear bands on specimen surface decreased and at 83 K, shear bands could not be observed. In addition, local grain coarsening occurred except at 83 K. Formation of dislocation cell and wall structures became more frequent at lower temperatures and well-developed dislocation walls were formed in grains as small as 1.5 μm in size at 83 K.

Measurement of Neutron Capture Cross Section Ratios of Cm Resonances Using NNRI Shinji GOKO a , Atsushi KIMURA a , Hideo HARADA a , Masumi OSHIMA a , Masayuki OHTA a , Kazuyoshi FURUTAKA a , Tadahiro KIN a , Fumito KITATANI a , Mitsuo KOIZUMI a , Shoji NAKAMURA a , Yosuke TOH a , Masayuki IGASHIRA b , Tatsuya KATABUCHI b , Motoharu MIZUMOTO c , Yoshiaki KIYANAGI c , Koichi KINO c , Michihiro FURUSAKA c , Fujio HIRAGA c , Takashi KAMIYAMA d , Jun-ichi HORI d , Toshiyuki FUJJI d , Satoshi FUKUTANI d & Koichi TAKAMIYA a a Nuclear Science and Engineering Directorate , Japan Atomic Energy Agency , Tokaimura, Naka-gun, Ibaraki , 319-1195 , Japan b Research Laboratory for Nuclear Reactors , Tokyo Institute of Technology , O-okayama, Meguro-ku, Tokyo , 152-8550 , Japan c Faculty of Engineering , Hokkaido University , Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido , 060-8628 , Japan d Research Reactor Institute , Kyoto University , Asashiro Nishi, Kumatori-cho, Sennangun, Osaka , 590-0494 , Japan Published online: 05 Jan 2012.

The physical basis of an artificial neuron is studied using a model that is based on the stochastic transition between two states in a double well potential. It is shown that the stochastic transition model generates an energy-defined sigmoid function acting as an activation (or transfer) function in neurons. The model is also applied to circuit neurons using superconducting quantum interference devices in artificial neural networks., PACS numbers: 87.19.ll, 85.25.Dq, 07.05.Mh., This work is supported in part by MEXT (17K05579).

An artificial neuron using superconducting devices, so-called rf SQUID, working at the quantum-mechanical domain is studied. It is shown that quantum rf SQUID regarded as flux qubit can act as an artificial neuron with sigmoid function generated by coherent quantum-mechanical transitions between wells in double well potential representing rf SQUID.

An artificial neuron using superconducting devices, so-called double SQUID, applicable to the extended backpropagation learning algorism is studied. It is shown that the tunable slope of the sigmoid function required in the algorism can be achieved under the fixed temperature by externally applied magnetic fields threading the ring with two Josephson junctions in the double SQUID.

The shape evolution of fcc Co–Fe precipitate particles during coarsening in Cu-1.37 at.% Co-0.83 at.% Fe alloy single crystals has been examined by the transmission electron microscopy observation. Co–Fe particles change from sphere to cuboid and eventually flatten into a plate-like one with increasing particle size. The size-dependent equilibrium shapes of Co–Fe particles were discussed by considering the elastic strain energy of particles together with the interface energy between the particles and the matrix. To evaluate the elastic strain energy, elastically homogeneous but anisotropic particles with purely dilatational misfit strains are taken into account. The experimentally observed shape transition can be satisfactorily explained by the simple energy analysis.

Cu-2.2wt%Ni-0.5wt%Si alloy single crystals were grown by the Bridgman method and aged at 723 K for 10 h to form Ni2Si precipitates. Fully reversed tension-compression fatigue tests were conducted on the aged single crystals with a single slip orientation under constant plastic-strain amplitudes at room temperature. Cyclic softening occurred at plastic-strain amplitudes between 2.5x10-4 and 2.5x10-2. Using the maximum stress amplitude in each cyclic hardening/softening curve, a pseudo cyclic stress-strain curve (CSSC) was obtained. The CSSC was found to exhibit a plateau region with a stress level of about 167 MPa. Transmission electron microscopic observation revealed the formation of persistent slip bands (PSBs) in the plateau regime. It was found that the Ni2Si precipitate particles were intensively sheared by glide dislocations within the PSBs and were eventually re-dissolved into the Cu matrix. The macroscopic cyclic softening can be attributed to the local softening induced by the re-dissolution of the Ni2Si particles in the PSBs.

We investigated optical gain and lasing characteristics of a polymer thin film co-doped with Rhodamine 6G and 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye molecules. By the co-doping of these dyes, the optical gain coefficient and its spectral range were enhanced and widened, respectively. These results cannot be accounted for by the linear combination of the optical gain properties of single-doped films. Owing to this high-gain and wide-band optical amplification property, a distributed feedback lasing with a low threshold of 70 μJ/cm2 as well as a widely tunable wavelength range of 587–613 nm was achieved. We attribute this amplification property of the co-doped film, which cannot be achieved with the single-doped films, to the appearance of a coupled excited state between the two molecules.

We compared 2 archaeological relics of different preservation environments, white substances adhering to a vessel from the Matsusaki site and to earthenware from Hirohata, by measuring their environmental radioactivity, 14C, 228Ra/226Ra, 234U/238U, and 87Sr/86Sr, and major element contents (Ca, Sr, Mg, Fe, and Mn). The results showed that the 2 materials were somewhat different and also reflected differences in their preservation environments. The chemical elements that were more abundant in the Matsusaki sample than in the Hirohata sample, Fe, Mn, 238U, and 232Th (parent of 228Ra), are also abundant in seaweed or seagrass. Contamination by 14C derived from rainwater after atmospheric nuclear tests was clearly observed in the white substance from Hirohata.