S. Ohya

Measurements of the interaction cross sections for Ar and Cl isotopes

We have measured the interaction cross sections (σI) of 31–40Ar and 31–37Cl on carbon targets at energies of around 950 A MeV. The effective matter radii for these nuclei were deduced by a Glauber-model analysis. Combining our matter radii with measured charge radii for Ar isotopes, we could deduce the proton-skin thicknesses for the 32–40Ar isotopes, which were found to increase monotonically with decreasing neutron number. The larger radius of the proton drip-line nucleus 31Ar suggests an anomalous structure for this nucleus. In addition, using NaI(Tl) arrays surrounding the carbon target, we measured γ-rays emitted from excited states in these isotopes. In this way we could deduce the upper limits for the inelastic cross sections (σinela) on carbon targets at energies of around 950 A MeV.

Study of high-spin states in odd sn isotopes

Abstract Level schemes of odd Sn isotopes (A = 109–117) have been studied by an in-beam spectroscopy method through (α, xn) reactions. High-spin states above the vh11/2 states were systematically observed. The level sequences show characteristics quite similar to those of adjacent even Sn isotopes. The level schemes are divided into two regions at about 2 MeV excitation from the vh11/2 states. The lower-energy region can be understood by particle-core coupling schemes, while the higher-energy region is interpreted by three-quasiparticle configurations of s1/2, d3/2, d5/2, g7/2 and h11/2 neutrons. Particle-core coupling schemes are discussed based on the neutron number dependence of the energy ratio (E15/2−−E11/2−)E2+.

Killing mechanism of Listeria monocytogenes in activated macrophages as determined by an improved assay system

Exposure of Listeria monocytogenes to gentamicin 5 mg/L for 4 h resulted in the killing of most extracellular bacteria, but had no effect on the survival of bacteria inside macrophages. Higher concentrations of gentamicin caused a reduction in the number of intracellular bacteria. This effect was associated with cellular uptake of gentamicin, but was unaffected by activation of macrophages by interferon-gamma and lipopolysaccharide. In experiments in which exposure to gentamicin 5 mg/L for 4 h was used to kill extracellular bacteria, killing by activated macrophages was impaired when O2- production was inhibited by superoxide dismutase, but not when nitric oxide production was blocked by NG-monomethyl-L-arginine. These data suggest that the reactive oxygen intermediates are more important than nitric oxide in the killing of L. monocytogenes, at least in macrophages activated in vitro.

Nuclear Data Sheets for A = 124

Abstract The experimental results from various decays and reactions for the A-124 mass chain have been complied and evaluated. Adopted values for the level and decay properties are tabulated. Inconsistencies and discrepancies are noted.

Administration of killed bacteria together with listeriolysin O induces protective immunity against Listeria monocytogenes in mice.

It is known that only listeriolysin O (LLO)‐producing Listeria monocytogenes strains are able to induce protective imm_unity, but the underlining relationship between LLO produced by virulent strains and generation of protective imm_unity in the infected host remains poorly understood. In the present study, it was found that LLO gene expression was only detected in the mice infected with virulent strain which was able to induce protective imm_unity, while non‐virulent strains or killed bacteria were not able to generate protective imm_unity. When mice were imm_unized with LLO plus killed bacteria in the presence of incomplete Freund’s adjuvant, the protective imm_unity was partially generated, and adoptive transfer experiment confirmed that this protection was antigen specific. Reverse‐transcription polymerase chain reaction revealed that LLO plus killed bacteria induced the expression of interferon‐γ (IFN‐γ) and interleukin‐12 (IL‐12). Our results also showed CD4+ T cells were the principal cells constituting protective imm_unity. Taken together, it may be concluded that LLO produced from virulent strains of L. monocytogenes was essential for the generation of protective imm_unity, and that LLO plus killed bacteria induced IFN‐γ and IL‐12 expression which resulted in the generation of protective imm_unity.

Nuclear data sheets for A = 126

Abstract The experimental results from various decays and reactions for the A=126 mass chain have been compiled and evaluated. Adopted values for the level and decay properties are tabulated. Inconsistencies and discrepancies are noted.

Persistent production of interferon-gamma (IFN-γ) and IL-12 is essential for the generation of protective immunity against Listeria monocytogenes

IFN‐γ and IL‐12 are believed to be important in the host defence against Listeria infection in mice. However, the relationship between these two cytokines and generation of protective immunity remains poorly understood. In the present study, it was found that at least 4 days of immunizing infection were required for the generation of protective immunity against L. monocytogenes. Protective immunity was generated only by immunizing infection with virulent strain. Even repeated injections of avirulent strain failed to induce protective immunity. When the immunizing infection was terminated with antibiotics, generation of protective immunity and IFN‐γ‐producing ability was impaired, while expression of IFN‐γ and IL‐12 was also impaired. The mutual relationship between IFN‐γ and IL‐12 in L. monocytogenes infection was analysed in vitro. After neutralization of IL‐12, IFN‐γ production was completely blocked and IFN‐γ expression was also inhibited. In contrast, there was no change of IL‐12 expression after neutralization of IFN‐γ. Taking all facts into consideration, it may be concluded that persistent production of IFN‐γ induced by persistent production of IL‐12 during immunizing infection is essential for the generation of protective immunity against L. monocytogenes.

Shape transition in light Pt isotopes: Magnetic moments and electric quadrupole moment ratios for185,187,189Pt

Nuclear orientation and nuclear magnetic resonance experiments were performed on185, 187, 189Pt isotopes oriented in Fe and single crystal Zn at temperatures down to about 6 mK. The hyperfine splitting frequencies of185Pt and187Pt in iron were determined to be 164.9(2) and 261.1(2) MHz, respectively. With the hyperfine field of −126.1(2.5) T, the g-factors are deduced to be |g(185Pt)|=0.172(3) and |g(187Pt)|=0.272(5).The spectroscopic quadrupole moment of187Pt was found to be negative with magnitude similar to that of189Pt, indicating a predominantly oblate ground state deformation for both isotopes. The spectroscopic quadrupole moment of185Pt was found to be positive, with the ratio Q(185Pt)/Q(189Pt)=−3.6(9), clearly indicating a change to prolate ground state deformation.

The half-life of 207Bi and decays of 211At and 211Po

Abstract The half-life of 207 Bi was obtained from the genetic relation between 207 Po and 207 Bi, and between 211 At and 207 Bi. The half-life was found to be 33.4 ± 0.8 y. The half-life of 207 Po was determined to be 5.81 ± 0.04 h by following the decay of the characteristic γ-rays from 207 Po. The half-life of 211 At was determined tobe 7.23 ± 0.02 h by following the decay of γ-rays and α-particles from 211 At and 211 Po. The half-lives determined in the present work for 207 Po and 211 At agree with the literature although the half-life of 207 Bi differs considerably from the currently accepted value of 38 y. The branching ratio of 211 At decaying through EC and α-decay modes was determined together with the branching ratios of the three α-particles emitted from 211 Po.

Double resonance NMR-on study on oriented188Ir in iron

The quadrupole splitting of oriented188Ir in iron was studied at 8.6 mK using a double resonance NMR-ON method. With r.f. power applied at the strongest resonance frequency, a second frequency was used to simultaneously investigate the second resonance component, where the splitting is caused by an electric quadrupole interaction. The electric hyperfine splitting frequency νQ=e2qQ/h was measured to be 3.37(11) MHz. With the known electric field gradient of −0.283(6)×1017 V/cm2 at Ir in iron, the spectroscopic quadrupole moment of188Ir was deduced to be 0.492(26)b. The present results show that the double resonance method is a powerful tool in establishing the quadrupole splitting, if it leads to well-resolved NMR-ON resonance components.