The mechanism of the two-phase Brust-Schiffrin synthesis of alkane thiol protected metal nanoparticles is known to be highly sensitive to the precursor species and reactant conditions. In this work X-ray absorption spectroscopy is used in conjunction with liquid/liquid electrochemistry to highlight the significance of Br- in the reaction mechanism. The species [AuBr4]- is shown to be a preferable precursor in the Brust-Schiffrin method as it is more resistant to the formation of Au(i) thiolate species than [AuCl4]-. Previous literature has demonstrated that avoidance of the Au(i) thiolate is critical to achieving a good yield of nanoparticles, as [Au(i)X2]- species are more readily reduced by NaBH4. We propose that the observed behavior of [AuBr4]- species described herein explains the discrepancies in reported behavior present in the literature to date. This new mechanistic understanding should enable nanoparticle synthesis with a higher yield and reduce particle size polydispersity.

The modification of electrochemistry and electronic absorption spectra of neodymium in various molten chlorides depending on additional fluoride in the melt bath has been investigated. Disproportionation reaction is restricted by fluoride addtion and absorption spectra is highly modified in molten NaCl-2CsCl as compared with that in molten LiCl-KCl. These facts would be explained by modification of local structure around neodymium cation depending on fluoride addition.

The interfacial reduction of aqueous [PdCl4]2− at the interface with an organic solution of ferrocene has been characterised by X-ray absorption fine structure (XAFS) spectroscopy.

Energy dispersive extended X-ray absorption fine structure (EDE) has been applied to Pd nanoparticle nucleation at a liquid/liquid interface under control over the interfacial potential and thereby the driving force for nucleation. Preliminary analysis focusing on Pd K edge-step height determination shows that under supersaturated conditions the concentration of Pd near the interface fluctuate over a period of several hours, likely due to the continuous formation and dissolution of sub-critical nuclei. Open circuit potential measurements conducted ex-situ in a liquid/liquid electrochemical cell support this view, showing that the fluctuations in Pd concentration are also visible as variations in potential across the liquid/liquid interface. By decreasing the interfacial potential through inclusion of a common ion (tetraethylammonium, TEA+) the Pd nanoparticle growth rate could be slowed down, resulting in a smooth nucleation process. Eventually, when the TEA+ ions reached an equilibrium potential, Pd nucleation and particle growth were inhibited.

With the advent of high-throughput and imaging core level spectroscopies (including X-ray absorption spectroscopy, XAS, as well as electron energy loss spectroscopy, EELS), automated data processing, visualisation and analytics will become a necessity. As a first step towards these objectives we examined the possibilities and limitations of a simple automated XANES peak fitting procedure written in MATLAB, for the parametrisation of XANES features, including ionisation potentials as well as the energies and intensities of electronic transitions. Using a series of Au L3-edge XANES reference spectra we show that most of the relevant information can be captured through a small number of rules applied to constrain the fits. Uncertainty in this strategy arises mostly when the ionisation potential (IP) overlaps with weak electronic transitions or features in the continuum beyond the IP, which can result in ambiguity through multiple equally good fits.

A carborne survey system, named as KURAMA (Kyoto University RAdiation MApping system), was developed as a response to the nuclear accident at TEPCO Fukushima Daiichi Nuclear Power Plant in 2011. Now the system has evolved into KURAMA-II, characterized by its compactness, autonomous operation, and acquisition of pulse-height spectrum data. A two-year field test of radiation monitoring by KURAMA-II on local buses, performed by Kyoto University, has successfully proceeded to the phase of official operation by the Fukushima prefectural government, supported by Kyoto University and JAEA (Japan Atomic Energy Agency). An outline and the current status of KURAMA-II, including some results of the continuous monitoring by KURAMA-II on local buses in Fukushima, are introduced.

The chemical properties and coordination circumstances of uranium complexes in NaCl-CsCl eutectic melts containing fluoride ion were investigated by both electrochemical and absorption spectrum measurements. Energy shifts in absorption peaks, which were caused by the formation of U4+ fluoride complex were observed when NaF was present in the melt. The formation of the fluoride complex of U3+ was not observed. When a cyclic voltammogram was measured after the addition of F−, the reduction potential of U4+ shifted negatively since the fluoride complex of U4+ was more stable than that of U3+ complex in the melt.

Abstract 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.

In order to separate neodymium (Nd) from lanthanides in chloride melts, the electrochemical characteristics Nd ions in molten LiCl–CaCl2 eutectic were studied. The formal redox potentials of the Nd3+|Nd2+ and Nd2+|Nd couples in molten LiCl–CaCl2 eutectic at 823K were determined to be −2.745±0.005 and −3.081±0.005V vs. Cl2|Cl−. Under the controlled potential electrolysis by applying negative potential to form Nd2+, Nd2+ was disproportionated to Nd3+ and metallic Nd fog according to the reaction; 3Nd2+ ⇄ 2Nd3+ +Nd. When a quartz glass was immersed in the melt during the electrolysis, Nd was coated on the quartz surface. The chemical composition of the recovered Nd was analyzed to be Nd metal and Nd2O3 by scanning electron microscopy, X-ray diffractometry, and electron probe microanalysis. The same electrolytic method was carried out under the coexistence of Nd3+ and lanthanum ion (La3+). Nd3+ was separated from La3+ and recovered to be Nd2O3.

INTRODUCTION:Helicobacter pylori infection is a major cause of gastric ulcers, and Helicobacter pylori eradication drastically reduces ulcer recurrence. It has been reported, however, that severe physical stress is closely associated with gastric ulceration even in Helicobacter pylori -negative patients.CASE PRESENTATION:We report the cases of a 47-year-old Japanese man and a 69-year-old Japanese man who developed psychological stress-induced hemorrhagic gastric ulcers, in both of whom Helicobacter pylori had been successfully eradicated.CONCLUSION:Our cases strongly suggest that not only physical but also psychological stress is still an important pathogenic factor for peptic ulceration and accordingly that physicians should pay attention to the possible presence of psychological stress in the management of patients with peptic ulcers.

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°′(U3+|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°′(U3+|U). The electronic absorption spectra of U3+ 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.

Abstract 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.

Extraction behavior of neptunium (Np) by tri-n-butyl phosphate from calcium nitrate hydrate melt was investigated. Distribution ratio of Np was found to increase with the decrease of water content. Adding nitric acid into the system resulted in an increase of the distribution ratio. In order to understand the extraction trends, Np species in the hydrate melt were analyzed by Raman spectrometry and UV/Vis/NIR spectrometry. Major fraction was assigned to be NpO22+ of Np(VI) and small fraction to be NpO2+ of Np(V). A shift of the v1 symmetric vibrational frequency of NpO22+ in nitrate media was found in Raman spectra. This suggests a coordination circumstance change of NpO22+.

Extraction of Am(III) and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO3)(2)center dot RH2O was investigated radiochemically. In the range of water content R = 3.5-8.0, the distribution ratio was found to increase with the decrease of water activity. The dependence of the distribution ratios on the water activity in the hydrate melt changes at around log (H2O)-H-a = -0.4, which corresponds to R = 5.0. The extraction behavior of Am(III) and Cm(III) was systematically discussed with the reported data of trivalent lanthanides.

Redox reactions of tetravalent uranium ion in calcium chloride hexahydrate CaCl2·6H2O melt ([CaCl2] = 6.9 M) were studied electrochemically and spectrophotometrically. Cyclic voltammograms in CaCl2·6H2O melt containing UCl4 were measured with a pyro-graphite carbon working electrode. A cathodic peak corresponding to the reduction of U4+ to U3+ was observed, and it was found to be controlled by the diffusion of U4+ in the melt. Although the concentration of H+ in the melt was negligible, the redox reaction of U4+ was observed without the disturbance of hydrolysis. The formal potential of the U4+|U3+ couple was determined to be -0.483 ± 0.005 V vs. NHE. The diffusion coefficient of U4+ in CaCl2·6H2O melt was determined to be 1.5 × 10−7 cm2 s−1 at 300 K. The anodic peak in the voltammogram was attributable to the oxidation of U4+ to UO22+, which was identified by using a technique based on the combination of electrolysis and spectrophotometry. Influences of the water content on chemical status of uranium ions in CaCl2 hydrate melts were studied.

Basic research in actinide chemistry and physics is indispensable to maintain sustainable development of innovative nuclear technology. Actinides, especially minor actinides of americium and curium, need to be handled in special facilities with containment and radiation shields. To promote and facilitate actinide research, close cooperation with the facilities and sharing of technical and scientific information must be very important and effective. A three-year-program "Basic actinide chemistry and physics research in close cooperation with hot laboratories", ACTILAB, was started to form the basis of sustainable development of innovative nuclear technology. In this program, research on actinide solid-state physics, solution chemistry and solid-liquid interface chemistry is made using four main facilities in Japan in close cooperation with each other, where basic experiments with transuranium elements can be made. The O-17-NMR measurements were performed on (Pu0.91Am0.09)O-2 to study the electronic state and the chemical behaviour of Am and Cm ions in electrolyte solutions was studied by distribution experiments.

In the non-aqueous reprocessing process of spent nuclear fuels by the pyro-electrochemical method, a spent fuel is dissolved into molten LiCl-KCl and NaCl-CsCl eutectics and dissolved uranium and plutonium are collected as either metal or oxide. However, the binary alkali chloride mixture with the lowest melting point is the LiCl-RbCl eutectic. In this study, electronic absorption spectra of U3+ and U4+ in molten LiCl-RbCl eutectic at various temperatures between 673 and 973 K were measured by the UV/Vis/NIR spectrophotometry. We confirmed that these spectra were similar to those in molten LiCl-KCl and NaCl-CsCl eutectics. The sensitive absorption bands of U4+ in LiCl-RbCl eutectic were found at 22000, 16500, 14900, 8600, and 4950 cm−1. The large absorption bands of U4+ over 25000 cm−1 increased with increasing melt temperature, while absorption peaks at 15500-4000 cm−1 decreased. The large absorption bands of U3+ in LiCl-RbCl eutectic were observed over 14000 cm−1. The sensitive absorption bands of U3+ at Vis/NIR region were found at 13300, 11500-11200, 9800-9400, and 8250 cm−1, and these peaks decreased with increasing temperature.

In order to enhance the understanding of redox reactions of plutonium ions in molten NaCl-CsCl eutectic, absorption spectrophotometry was performed for Pu3+, Pu4+, and PuO22+ in molten NaCl-CsCl at 923 K by controlling the flow-rate ratio of Cl-2 and Ar or O-2 in the ventilating mixture gas. Based upon the relations of the measured rest potentials to the concentration ratios of [Pu4+]/[Pu3+] and [PuO22+]/[Pu4+], the redox potentials of Pu4+/Pu3+ and PuO22+/Pu4+ couples in molten NaCl-CsCl eutectic at 923 K were estimated.

Basic electrochemical and spectroscopic properties of Cr3+, Cr2+, Fe3+, and Fe2+ were studied to analyze the cyclic redox reactions of Cr and Fe, which may decrease the current efficiency of the electro-winning method using NaCl–2CsCl melts. The formal redox potentials of the \( {\text{Cr}}^{3 + } |{\text{Cr}}^{2 + } \) and \( {\text{Fe}}^{3 + } |{\text{Fe}}^{2 + } \) couples, \( E_{{{\text{Cr}}^{{ 3 + }} | {\text{Cr}}^{{ 2 + }} }}^{\circ \prime } \) and \( E_{{{\text{Fe}}^{ 3+ } | {\text{Fe}}^{ 2+ } }}^{\circ \prime } \), in NaCl–2CsCl melts at 923 K were spectroelectrochemically determined to be −0.648 ± 0.005 V and \(-0.140 \pm 0.010\,{\text{V}}\,{\text{vs}} .\,{\text{Cl}}_{2}|{\text{Cl}}^{-} \), respectively. These values were determined by measuring electromotive force and UV–VIS absorption spectra at varying concentration ratios of trivalent and divalent ions. Cyclic voltammetry was also carried out to examine the characteristics of the voltammograms for the \( {\text{Cr}}^{3 + } |{\text{Cr}}^{2 + } \) and \( {\text{Fe}}^{3 + } |{\text{Fe}}^{2 + } \) couples in NaCl–2CsCl melts. The \( E_{{{\text{Cr}}^{3 + } |{\text{Cr}}^{2 + } }}^{\circ \prime } \) determined by the spectroelectrochemical method was close to that determined by cyclic voltammetry \( ( - 0.651 \pm 0.006\,{\text{V}}\,{\text{vs}} .\,{\text{Cl}}_{2} |{\text{Cl}}^{-} ) \). The effect of temperature on the \( E_{{{\text{Cr}}^{3 + } |{\text{Cr}}^{2 + } }}^{\circ \prime } \) in NaCl–2CsCl melts was studied by cyclic voltammetry in the range from 823 to 1,023 K \( (E_{{{\text{Cr}}^{3 + } |{\text{Cr}}^{2 + } }}^{\circ \prime } = 0.00143T-1.971 \pm 0.005\,{\text{V}}\,{\text{vs}} .\,{\text{Cl}}_{2} |{\text{Cl}}^{-} ) \). Diffusion coefficients of Cr3+ and Cr2+, \( D_{{{\text{Cr}}^{ 3+ } }}^{{}} \)and \( D_{{{\text{Cr}}^{ 2+ } }}^{{}} \), were determined between 823 and 1,023 K to be \( D_{{{\text{Cr}}^{3 + } }} = 2.23 \times 10^{ - 3} \,{ \exp }( - 4,\!135/T) \) and \( D_{{{\text{Cr}}^{2 + } }} = 3.34 \times 10^{ - 3} \,{ \exp }( - 4,\!106/T) \), respectively. Molar absorptivities of Cr3+ and Cr2+ in NaCl–2CsCl melts at 923 K were determined to be 77.8 ± 2.4 M−1 cm−1 at 17,670 cm−1 and 48.0 ± 1.4 M−1 cm−1 at 9,170 cm−1, respectively. In addition, the effects of these ions on the cyclic redox reaction of the pyro-reprocessing process were discussed.