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All superheavy elements (SHEs), with atomic numbers (Z) ≥104, have been artificially synthesized one atom at a time and their chemical properties are largely unknown. Because these heavy nuclei have short lifetimes as well as extremely low production rates, chemical experiments need to be carried out on single atoms and have mostly been limited to adsorption and extraction. We have now investigated the precipitation properties of the SHE Rf (Z = 104). A co-precipitation method with samarium hydroxide had previously established that the co-precipitation behaviour of a range of elements reflected these elements’ tendency to form hydroxide precipitates and/or ammine complex ions. Here we investigated co-precipitation of Rf in basic solutions containing NH3 or NaOH. Comparisons between the behaviour of Rf with that of Zr and Hf (lighter homologues of Rf) and actinide Th (a pseudo-homologue of Rf) showed that Rf does not coordinate strongly with NH3, but forms a hydroxide (co)precipitate that is expected to be Rf(OH)4. It is difficult to investigate the chemical properties of superheavy elements, which are only available an atom at a time and rapidly decay. A co-precipitation method with samarium has now been developed that suggests rutherfordium would form hydroxide precipitates—but not ammine ones—if it were possible to perform these experiments on macroscopic quantities.

To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.

Chemical studies of transactinide elements (atomic number Z ≥ 104) are of great importance to understand the relativistic effects; however, the experimental methodology is limited owing to the sing...

The deposition of insoluble radiocesium bearing microparticles (CsMPs), which were released from the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident in March 2011, has resulted in the widespread contamination of eastern Japan. Obviously, these deposited insoluble CsMPs may become the secondary contamination sources by atmospheric migration or other environmental transferring process, however, the understanding of the transport mechanism remains non-elucidation, and the relevant evidence has not been directly provided. This study, for the first time, provides the direct evidence for the resuspension of these insoluble CsMPs to the atmosphere from 1) proximity of 137Cs radioactivity and resemblance of the morphology and the elemental compositions of CsMPs in the samples of soil and aerosol derived from the same sampling site, 2) the special characteristics of the resuspended CsMPs of which the ratios of Na/Si, K/Si and/or Cs/Si were smaller than those from the initially released CsMPs collected at either long distance or near F1NPP, which can be ascribed to the slowly natural corrosion of CsMPs by the loss of the small amount of soluble contents in CsMPs and 3) high CsMPs concentration of 10 granules/gram in the surface soil of our sampling site and the observed resuspension of surface soil dust at wind gust speed higher than 4 m s-1. Specifically, fifteen single CsMPs were successfully isolated from the aerosol filters collected by unmanned high-volume air samplers at a severely polluted area in Fukushima Prefecture, about 25 km away from F1NPP, from January 2015 to September 2019. The mean diameter of these CsMPs was 1.8 ± 0.5 μm, and the average 137Cs radioactivity was 0.35 ± 0.23 Bq/granule. The contribution rate of the resuspended CsMPs to the atmospheric radiocesium was estimated from the ratio of 137Cs radioactivity of a single CsMP to that of the aerosol filter to be of 23.9 ± 15.3%. There has been no considerable decreasing trend in the annual CsMP resuspension frequency.

We have developed a new method for producing 191Pt from an iridium target. Alkali fusion of iridium was successfully performed using a vertical beam irradiation method and a mixed target of Ir and Na2O2, which resulted in easy dissolution of the irradiated iridium target. A trace amount of PtⅣCl62- was isolated from bulk IrⅣCl62- by solvent extraction and anion exchange chromatography. The production yield of 191Pt was 7.1 ± 0.4 (MBq/μA h, EOB) by proton irradiation at 30 MeV. The radioplatinum product (n.c.a.) was prepared at a radiochemical purity of 97% for PtⅣCl62-, and 95% for PtⅡCl42-, respectively.

金沢大学疾患モデル総合研究センター, Alpha particle-emitting radionuclides have gained considerable attention for radionuclide therapy. Astatine-211 ( 211 At) is a promising alpha particle-emitting radionuclide. 211 At is a halogen that has similar chemical properties to iodine and exhibits a half-life of 7.2 h. However, direct labeling of proteins or peptides into the tyrosine residue with 211 At was shown to be impractical. Herein, we demonstrate a novel 211 At-labeling method using the RGD peptide as a model peptide. An 211 At-labeled RGD peptide, [ 211 At]c[RGDf(4-At)K], was prepared from a precursor with a tributylstannyl group on the phenylalanine residue in c(RGDfK) with a radiochemical yield of 63% and a radiochemical purity of >96%, and its potential for targeted radionuclide therapy was evaluated. Based on the results of biodistribution experiments, [ 125 I]c[RGDf(4-I)K] and [ 211 At]c[RGDf(4-At)K] showed high accumulation in the tumor and similar biodistribution. This study provides useful information for radiotheranostics between an 211 At-labeled peptide and the corresponding radioiodine-labeled peptide. © 2019 American Chemical Society., This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

211At is an α-emitter that has similar chemical properties to iodine and is used in targeted α-therapy. In the present study, we added ascorbic acid (AA) to 211At solution to increase the radiochemical purity of astatide and evaluated its efficacy against differentiated thyroid cancer, which is characterized by the expression of sodium/iodide symporter (NIS). Methods: Crude 211At solution (AA(−)) and 211At solution treated with AA (AA(+)) were prepared. Uptake by the thyroid was compared between the 2 solutions in normal male Wistar rats (n = 6). Cellular uptake in K1-NIS cells was analyzed under the AA(+) and AA(−) conditions. AA(+) was injected at 3 doses into K1-NIS xenograft mice: 1 MBq (n = 6), 0.4 MBq (n = 6), and 0.1 MBq (n = 6), and vehicle was injected into control mice (n = 6). The treatment effects were compared among the 4 groups. Results: Uptake by the thyroid was significantly enhanced in rats injected with the AA(+) as compared with those injected with AA(−). Cellular uptake analysis showed significantly increased uptake of 211At by the K1-NIS cells under the AA(+) condition as compared with the AA(−) condition. In the mouse xenograft model, the K1-NIS tumors showed significant accumulation of 211At at 3 and 24 h after administration (22.5 ± 10.4 and 12.9 ± 6.8 percentage injected dose, respectively). Tumor growth was immediately inhibited in a dose-dependent manner after administration of 211At. In the survival analysis, the 211At groups (0.1, 0.4, and 1 MBq) showed significantly better survival than the control group. Conclusion: Uptake of 211At was enhanced in differentiated thyroid cancer cells as well as the normal thyroid using 211At solution treated with AA. The method also showed dose-dependent efficacy against the K1-NIS xenografts, suggesting its potential applicability to targeted α-therapy.

The first thiohalide μ3-capped octahedral hexanuclear technetium clusters with 24 valence electrons, [Tc6(μ3-S)8−n(μ3-Br)nBr6]n−4 [n = 1 ([Tc-S7Br]3−) and n = 2 ([Tc-S6Br2]2−)] and [Tc6(μ3-S)7(μ3-Cl)Cl6]3− ([Tc-S7Cl]3−), were synthesized and characterized. The structures of [Tc-S7Br]3−, [Tc-S6Br2]2−, and [Tc-S7Cl]3− were determined by single-crystal X-ray analysis. The Tc–Tc bond distances in [Tc-S7Br]3−, [Tc-S6Br2]2−, and [Tc-S7Cl]3− are 2.5842(6)–2.6029(6) A (avg. 2.593(2) A), 2.5835(10)–2.6049(10) A (avg. 2.596(1) A), and 2.5829(4)–2.5940(4) A (avg. 2.587(3) A), respectively. The capping halide and sulfide ligands in [Tc-S7Br]3−, [Tc-S6Br2]2−, and [Tc-S7Cl]3− were disordered in the crystals. The bond distances of Tc–S/Br as a function of the occupancies of the capping bromides for [Tc-S6Br2]2−, [Tc-S7Br]3−, and [Tc6(μ3-S)8Br6]4− ([Tc-S8]4−) showed a linear correlation. The one-electron reduction waves assignable to the TcIII6/TcIITcIII5 [Tc6(24e/25e)] process were observed for the novel complexes. Density functional theory (DFT) calculations of the hexanuclear technetium complexes showed a smaller energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the hexanuclear technetium complexes compared to those of the rhenium analogues. The electronic transitions of the new technetium complexes shifted to lower energy compared to the isotypic rhenium complexes.

Recently, high efficiency permanent magnet synchronous motors (PMSMs) have been used in various fields as the performance of permanent magnets improves. The authors have investigated PMSM position sensorless control based on high frequency (HF) voltage injection. In the research, HF voltage is injected into fundamental voltage. And HF current response, which includes information of the rotor position, is utilized for position estimation. There have been two problems that control becomes unstable as the speed increases and that estimated position error occurs under load condition. In this paper, impact of speed and load on position estimation is investigated and an estimated position error compensation method, which is taking impact of speed and load into account, is proposed. Further, experimental results for interior permanent magnet synchronous motor (IPMSM) demonstrate the validity of the proposed method.

For new chemical studies on heavy elements, we previously investigated the coprecipitation behaviors with samarium hydroxide for various elements. Herein, we report the coprecipitation experiment using multitracer produced by neutron-induced fission of 235U. The coprecipitation behaviors of 10 elements were investigated: new data were obtained for Sr, Ru, I, Pm, and Np. The present results support the previously obtained conclusion that the hydroxide precipitation properties of various elements can be qualitatively investigated through their coprecipitation behaviors.

We successfully observed the equilibrium state of the chemical reactions for superheavy elements on a one-atom-at-a-time scale; we investigated the time dependence of the extraction behaviour of element 104, Rf. The distribution coefficient of Rf in 9 M HCl was found to be higher than those of its homologous elements, probably due to differences in the chloride complexation of Rf.

The production cross sections of 10Be and 26Al were measured by accelerator mass spectrometry using 89Y, 159Tb, and natCu targets bombarded by protons with energies Ep of 120 GeV and 392 MeV. The production cross sections obtained for 10Be and 26Al were compared with those previously reported using Ep = 50 MeV–24 GeV and various targets. It was found that the production cross sections of 10Be monotonically increased with increasing target mass number when the proton energy was greater than a few GeV. On the other hand, it was also found that the production cross sections of 10Be decreased as the target mass number increased from that of carbon to those near the mass numbers of nickel and zinc when the proton energy was below approximately 1 GeV. They also increased as the target mass number increased from near those of nickel and zinc to that of bismuth, in the same proton energy range. Similar results were observed in the production cross sections of 26Al, though the absolute values were quite different between 10Be and 26Al. The difference between these production cross sections may depend on the impact parameter (nuclear radius) and/or the target nucleus stiffness.

When a negatively charged muon is stopped in a substance, it is captured by an atom of the substance, and the muonic atom is formed. The muon capture process is significantly affected by the chemical environment of the atom and factors such as molecular structure (chemical effect). In this study, we performed muon irradiation for low-pressure CO, CO2, and COS molecules and measured the muonic X-rays emitted immediately after muon capture by an atom. In this paper, we quantitatively discuss the muon capture probability of each type of atom using the LMM model.

We studied solid–liquid extraction behavior of carrier-free Mo and W radiotracers onto an Aliquat 336-loaded resin from HCl solutions toward extraction chromatography experiments of element 106, seaborgium (Sg). Distribution coefficients (K d) of Mo and W on the resin were determined as a function of HCl concentration by a batch method. On-line extraction chromatography of Mo and W was also carried out in 2–8 M HCl solutions with an automated rapid chemistry apparatus. The order of extraction probability from 2 to 8 M HCl was Mo > W, which reflected the order of the K d values in the batch experiment.

Solvent extraction behaviors of Am(III) and Eu(III) using 2-hydroxy-2-methyloctanoic acid (Hhmo) and 2-hydroxy-2-trifluoromethyloctanoic acid (Hhfo) were investigated in aqueous acetic acid/1-octanol at 20 °C. In both cases, distribution ratios (D) of the organic/aqueous phases increased with increasing pH of the aqueous solution. The D Am(Hhfo) and D Eu(Hhfo) values were found to be much higher than those for D Am(Hhmo) and D Eu(Hhmo), respectively, under similar pH conditions. The maximum separation factor of D Eu(Hhfo)/D Am(Hhfo) was 2.31 ± 0.70 0.80 at pH 4.29. The differences between D Am(Hhmo) and D Eu(Hhmo) values were relatively small in the pH region under consideration.

A new technique for continuous dissolution of nuclear reaction products transported by a gas-jet system was developed for superheavy element (SHE) chemistry. In this technique, a hydrophobic membrane is utilized to separate an aqueous phase from the gas phase. With this technique, the dissolution efficiencies of short-lived radionuclides of 91m,93mMo and 176W were measured. Yields of more than 80 % were observed for short-lived radionuclides at aqueous-phase flow rates of 0.1–0.4 mL/s. The gas flow-rate had no influence on the dissolution efficiency within the studied flow range of 1.0–2.0 L/min. These results show that this technique is applicable for on-line chemical studies of SHEs in the liquid phase.

The extraction and reduction behavior of Mo and W, lighter homologs of Sg, was studied in continuous on-line experiments at the JAEA tandem accelerator to develop a new chemistry assembly consisting of a membrane degasser (MDG), a flow electrolytic column (FEC), and the continuous liquid–liquid extraction apparatus (SISAK). Extraction yields of Mo and W from 0.1 M HCl/0.9 M LiCl into 4-isopropyltropolone (hinokitiol, HT) in toluene were investigated. In the reduction experiment, Mo(VI) was successfully reduced to a lower oxidation state while W(VI) showed no reduction under the given conditions.

Reaction cross sections for Cr and Y induced by neutrons at 197 MeV were measured by using 7 Li(p,n) reaction at N0 beam line in the Research Center for Nuclear Physics (RCNP), Osaka University. To estimate quasi-monoenergetic neutron cross sections, Cr and Y samples were irradiated on the two angles of 0 ∘ and 25 ∘ relative to the axis of the primary proton beam. The measured cross section data in the nat Cr(n,x) and 89 Y(n,x) reactions are compared to the JENDL high-energy file and the literature proton values, respectively. The results obtained are also compared to the cross section data for the same target materials with 287 and 386 MeV neutrons in our previous work.

SummaryFor the solvent extraction experiment on element 104 (Rf), solvent extraction of Zr and Hf as its homologues was performed in tributylphosphate (TBP)/hydrochloric acid (HCl) system using the carrier-free radiotracers88Zr and175Hf. Time dependences of the distribution ratios of Zr and Hf were investigated using 6.1 and 10.0M HCl and 0.5 and 2.0M TBP benzene solutions. The distribution ratios in equilibrium were determined for these elements as a function of HCl concentrations in the range of 4.1-10.2M. We found that the neutral chloride complexes of Zr and Hf were formed and extracted into the organic phase within 20 min in HCl with a concentration higher than 6 M. From the results, we propose that solvent extraction of Rf from 4-8M HCl into 2.0M TBP benzene is suitable for investigating the chloride complexation properties of Rf. In addition, for the development of the rapid liquid-liquid extraction apparatus, three types of microchannel devices, namely, a micro reactor, capillary tube and micro-chemical chip, were tested as a mixing-solution part in the apparatus. The chemical reactions of Zr and Hf in the extraction were found to be fast only when using the microchemical chip, which is important for investigations with the 68-s261Rf.

Six-coordinate distorted octahedral tetracyanidonitridorhenium(V) and -technetium(V) complexes with a volatile organic compound (VOC) coordinating at the trans position of a nitrido ligand, (PPh4)2[MN(CN)4L] (M = Re, L = MeOH, EtOH, acetone, or MeCN; M = Tc, L = MeOH), and five-coordinate square-pyramidal tetracyanidonitrido complexes without an axial ligand, (PPh4)2[MN(CN)4] (M = Re or Tc), were synthesized and characterized. Single-crystal X-ray structural analysis was carried out for (PPh4)2[MN(CN)4L] (M = Re, L = MeOH, EtOH, or acetone; M = Tc, L = MeOH) and (PPh4)2[ReN(CN)4]. All complexes studied showed photoluminescence in the solid state at room temperature. Reversible luminescence switching between six- and five-coordinate rhenium(V) complexes and between the relevant six-coordinate rhenium(V) complexes except that between the MeCN and acetone complexes was achieved by exposing them to VOC vapor in the solid state at room temperature. Luminescence changes were observed from the five-coordinate technetium(V) complexes in a MeOH vapor atmosphere in the solid state. In contrast, no vapochromic luminescence was observed from the five- and six-coordinate complexes in an acetone vapor atmosphere.

We have investigated the cation-exchange behavior of element 104, rutherfordium (Rf), together with its lighter group-4 homologs Zr and Hf, and the tetravalent pseudo-homolog Th in HF/HNO3 mixed so...

Trivalent actinides Am(III), Cm(III), and Cf(III) were successfully separated for the first time using capillary electrophoresis in 2-hydroxyisobutyric acid/acetic acid. It was found that the ionic radius was primarily important for separation of trivalent actinides as well as lanthanides in this condition. The stability constants of the Am(III) complexes with 2-hydroxyisobutyrate were estimated using the correlations between the molar fraction ratio of lanthanides and their ionic radii.

Altitude distributions of radioactive cesium (134Cs and 137Cs) fallout at Mt. Fuji due to Fukushima Daiichi Nuclear Power Station accident have been investigated. Radioactive cesium from Fukushima Daiichi Nuclear Power Station is found to reach the height of 2,700 m. It is inferred that some amounts of radioactive cesium are attributable to the global fallout due to the nuclear weapons tests in the atmosphere.

It is of great interest to study chemical properties of the transactinide elements with atomic numbers (Z) ≥ 104. One of the most important subjects is to establish the position of the elements at the extreme end of the periodic table. To this end we perform studies of chemical properties of these transactinides and compare them with those of their lighter homologues and with the ones expected from extrapolations in the periodic table. So far, chromatographic studies of the transactinides have provided experimental proof of placing rutherfordium (Rf, Z = 104) through hassium (Hs, Z = 108) into groups 4 to 8, respectively. 1-10 Quite recently, copernicium (Cn, Z = 112) has been shown to be a member of group 12. 11 To gain a better understanding, it is even more interesting to study chemical properties of the transactinide elements in greater detail and to compare those with the ones of their lighter homologues. Theoretical calculations predict that the ground state electronic structure of the heaviest elements varies due to strong relativistic effects. Accordingly, chemical properties of these elements may deviate from those expected from linear extrapolations based on lighter homologues. 12-14 Systematically, detailed chemical investigations are, therefore, required to characterize properties of the transactinide elements influenced by relativistic effects.

The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.

To establish a new methodology for superheavy element chemistry, the coprecipitation behaviors of 34 elements with samarium hydroxide were investigated using multitracer produced by a spallation of Ta. The chemical reactions were rapidly equilibrated within 10 s for many elements. In addition, these elements exhibited individual coprecipitation behaviors, and the behaviors were qualitatively related to their hydroxide precipitation behaviors. It was demonstrated that the ammine and hydroxide complex formations of superheavy elements could be investigated using the established method.

Summary The electronic K X-ray energies of pionic atoms were precisely measured on elements ranging from zinc to lead with a low-energy photon detection system. Some differences between pionic and muonic atoms were found in the atomic-number (Z) dependence of the energy shift. In the pionic atoms, the energy shift gradually decreases with an increase in atomic number, which is opposite to the trend for muonic atoms. In the low-Z region investigated elements, the energy shifts of K β X-rays were obviously larger than those of K α X-rays.

Summary We produced 229Th in the nuclear reaction 232Th(γ, p2n) 229Ac, followed by disintegration to 229m,gTh. The 229mTh α-decay was searched for. Alpha-particle events of energy between 4.93 MeV and 5.05 MeV were observed in the separated thorium sample of β-decay products from an actinium source highly purified from the 232Th + γ reaction products. The energies of the α-particles coincide with those expected for 229mTh.

The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By application of the appropriate potentials on the chromatography column, the more stable Md(3+) is reduced to Md(2+). The reduction potential of the Md(3+) + e(-) → Md(2+) couple was determined to be -0.16 ± 0.05 V versus a normal hydrogen electrode.

Fluoride complexation of element 104, rutherfordium (Rf), produced in the 248Cm(18O,5n)261Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchange chromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the 18O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effects on the fluoride complexation of Rf.

Using an ion implantation method, we introduced cerium nuclei in highly oriented pyrolytic graphite (HOPG), and have studied their behavior by means of the time-differential perturbed angular correlation technique. The timevariant directional anisotropy for the present pseudo-single crystalline sample is little different from that for polycrystalline graphite. Temperature dependence has been observed on the electric quadrupole interaction between the probe nuclei and the extranuclear charge distribution: the anisotropy shows gradual attenuation at room temperature, whereas the effect of an electrostatic perturbation is implied in the spectrum at 10 K. For the chemical state of the probe atom in HOPG, the trivalent state is suggested from the large magnitude of the electric field gradient at the probe nucleus.

The alpha-decay of a low energy isomer of 229Th at about 3.5 eV was sought by producing it through the (g,n) reaction on a 230Th target. Thorium isotopes in the reaction products were isolated and purified by anion exchange chromatography in a concentrated nitric acid medium to remove lanthanides fission products. The thorium fraction was further purified by samarium fluoride coprecipitation and the precipitate was mounted as a source for a-spectroscopy. Decaying a-signals were observed in the energy region that was expected for 229mTh, i.e., between 4.83 and 5.08 MeV. The half-life of the decaying component was determined from repeated experiments to be 13.9±3 hours.

Solvent extraction behavior of carrier-free Mo and W from 0.1–11 M HCl into 0.05 M Aliquat 336-chloroform solution was investigated and compared with that of macro amounts of Mo and W. The distribution ratios of carrier-free Mo and W were in good agreement with those of macro amounts of Mo and W in 6–11 M HCl, while the extraction efficiencies of carrier-free Mo and W were different from those of macro amounts of Mo and W in

The pion capture process in gas mixtures containing hydrogen was studied by measuring pionic X rays and π0 decays. A little difference in pion transfer process was found between the H2+D2 and H2O+D2O systems. Pressure-dependence of the transfer rates was also revealed in the CH4+Ar system by the measurements at several gas pressures. The mechanism of the pion transfer process was discussed based on a comparison between transfer parameters in the gas and liquid phases.

Pionic X-rays and π0 decays were measured for gas mixtures of H2/D2/CH4+SF6/Ar and the individual pure gases. Chemical effects on the pion transfer process from pionic hydrogen to other atoms were revealed by the pionic X-ray spectrum. The changes of the intensity patterns of pionic X-rays were compared with the predictions by a cascade calculation taking the transfer process into account. The mechanism of pion transfer process was discussed based on the results for gas phase and the previous ones for liquid phase.

Target-like products, that is,191–200Au,185–200Pt, and183–195Ir, from197Au target bombarded with12C ions at the energies of 180, 230, and 400 MeV/u were measured by using off-line gamma-ray spectrometry combined with chemical separation procedures. Spallation systematics by Rudstam reproduces well the measured cross sections for formation of platinum and iridium isotopes. It was found that the cross sections of gold nuclides increase with increase of the incident energy in the range studied and they are enhanced if compared with the reported proton-induced reaction of gold at a similar incident energy. It is suggested that the electromagnetic dissociation process plays a role for production of such gold nuclides.

Annihilation γ-rays of π0 and pionic X-rays were measured in the gas mixtures of H2+Z and CH4+Z systems (Z=He, Ne, Ar and Kr). Pion capture probability of hydrogen atom was obtained from the annihilation γ-ray counts and the capture probability of Z atom was obtained from the pionic X-ray intensities. Transfer rates were determined from the data based on a combined large mesomolecular model. The transfer rates obtained were smaller than the systematics of the Russian group. Difference in the transfer rate between the gas and the liquid phases was found by a comparison of the present results with our previous ones.

The 1:1 reaction of [Ru(bpy)2(solvent)2]2+ (bpy = 2,2'-bipyridine) with [Ni(aet)2] (aet = 2-aminoethanethiolate) gave a S-bridged Ru II 2 Ni II 2 tetranuclear complex with an eight-membered Ru 2 Ni 2 S 4 metallacycle, [{Ru(bpy) 2 } 2 -{Ni(aet) 2 } 2 ] 4+ , while a S-bridged Ru II Ni II dinuclear complex with a four-membered RuNiS2 metallacycle, [Ru(bpy) 2 -{Ni(aet) 2 }] 2+ , was obtained by the corresponding 1:2 reaction between [Ru(bpy)2(solvent)2]2+ and [Ni(aet)2].

Negative pion transfer from pionic hydrogen to other heavier atoms was studied in some liquid organic compounds. The pion capture probability on hydrogen at a particular site in the molecules was obtained using deuterated compounds for alcohols and carboxylic acids. The transfer process to carbon atoms in different chemical states was also studied in the mixtures of C6 H12 or C6 H6+ CCl4. These methods revealed that the pionic hydrogen atoms originating from hydrogen in different chemical environments showed different behavior. The transfer process was discussed using a large mesomolecular model combined with an external transfer process.