Publications (31)48.79 Total impact
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ABSTRACT: A recent development in analytical chemistry has enabled us to monitor systemic organophosphorus insecticide (OP) exposure at individual levels. At present, however, limited data are currently available on urinary OP metabolite levels worldwide. The purpose of this study was to assess urinary dialkylphosphate (DAP) concentrations in Japanese workers. Urine samples were collected in both summer and winter from 339 Japanese adults who worked as food distributors (FDs, n=164), apple farmers (AFs, n=147) and pest control operators (PCOs, n=28). DAPs were measured by gas chromatographymass spectrometry after derivatization with pentafluorobenzylbromide. Dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP) were detected in the urine of over 87% of the studied populations in both seasons. The geometric mean values of total DAPs (nmol g(1) creatinine), DMP, DMTP, DEP and DETP (μg g(1) creatinine) in summer and winter were 106.7 and 98.3, 7.0 and 3.8, 3.4 and 4.5, 0.8 and 1.5, and 0.3 and 0.2 for the FDs, 440.8 and 197.7, 33.1 and 10.8, 10.1 and 5.8, 4.2 and 4.7 and 1.6 and 0.8 for the AFs, and 473.4 and 284.6, 28.9 and 22.2, 17.6 and 4.6, 3.5 and 4.4, and 0.5 and 0.6 for the PCOs, respectively, thereby revealing significantly higher concentrations in AFs and PCOs groups than in the FDs in both seasons except for winter DMTP. These DAP concentrations were approximately the same or at lower levels compared with those reported in the previous literature. This is one of the first studies to demonstrate urinary DAP concentrations in Japanese adults.  [Show abstract] [Hide abstract]
ABSTRACT: Among urinary organophosphorus pesticide (OP) metabolites, dialkyl phosphates (DAPs) have been most often measured as a sensitive biomarker in nonoccupational and occupational OP exposure risk assessment. In our conventional method, we have employed a procedure including simple liquidliquid extraction (diethyl ether/acetonitrile), derivatization (pentafluorobenzylbromide, PFBBr) and cleanup (multilayer column) for gas chromatographymass spectrometry (GCMS) analysis starting from 5mL urine samples. In this study, we introduce a revised analytical method for urinary DAPs; its main modification was aimed at improving the prederivatization dehydration procedure. The limits of detection were approximately 0.15 microg/L for dimethylphosphate (DMP), 0.07 microg/L for diethylphosphate (DEP), and 0.05 microg/L for both dimethylthiophosphate (DMTP) and diethylthiophosphate (DETP) in 2.5mL human urine samples. Withinrun precision (percent of relative standard deviation, %RSD) at the DAP levels varying in the range of 0.550 microg/L was 6.019.1% for DMP, 3.618.3% for DEP, 8.025.6% for DMTP and 9.627.8% for DETP. Betweenrun precision at 5 microg/L was below 15.7% for all DAPs. The revised method proved to be feasible to routine biological monitoring not only for occupational OP exposure but also for environmental background levels in the general population. Compared to our previous method, the revised method underscores the importance of adding prederivatization anhydration for higher sensitivity and precision.  [Show abstract] [Hide abstract]
ABSTRACT: Decay particles from the shole states in 11B and 15N have been measured in coincidence with the quasifree 12C(p, 2p) and 16O(p, 2p) reactions at E p =392 MeV. Triton decay is found to be dominant for the 11B(shole) state and also found to be larger than α decay for the 15N(shole) state despite its smaller Q value compared to α decay. Measured decay branching ratios are discussed in comparison with the results of statisticalmodel, SU(3)model, and shellmodel calculations. The energy spectra around the shole states in both 11B and 15N exhibit some bumplike structures, which can be qualitatively explained by recent shellmodel calculations for both nuclei.  [Show abstract] [Hide abstract]
ABSTRACT: Decay particles from the shole states in B11, N15 and He6 have been measured in coincidence with the quasifree C12 (p, 2p), O16 (p, 2p) and Li7(p,2p) reactions at 392 MeV incident energy. Tritondecay is found to be larger than adecay for both 8hole states in B11 and N15 despite its smaller Qvalue than that of adecay. This supports the selection rule predicted by the microscopic SU(3)model calculations. The relation between the He6(shole) state and the ditriton cluster structure recently found from the charge exchange reaction is briefly discussed.  [Show abstract] [Hide abstract]
ABSTRACT: Backgroundfree inelastic scattering spectra have been obtained for144,148,150,152,154Sm with 386 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the densitydependent singlefolding model. The effects of deformation are found to be different for the low and highexcitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoreticallypredicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.  [Show abstract] [Hide abstract]
ABSTRACT: Backgroundfree inelastic scattering spectra have been obtained for 144,148,150,152,154Sm with 386 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the densitydependent singlefolding model. The effects of deformation are found to be different for the low and highexcitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoreticallypredicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance. 
Article: Structures and decay of deephole states in light nuclei populated by the (p, 2p 2p) reactions
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ABSTRACT: Decay particles from the shole states in 11 B and 15 N have been measured in coincidence with the quasifree 12 C(p, 2p) and 16 O(p, 2p) reactions at E p = 392 MeV. Triton decay is found to be dominant for the 11 B(shole) state and also found to be larger than α decay for the 15 N(shole) state despite its smaller Q value compared to α decay. Measured decay branching ratios are discussed in comparison with the results of statisticalmodel, SU (3)model, and shellmodel calculations. The energy spectra around the shole states in both 11 B and 15 N exhibit some bumplike structures, which can be qualitatively explained by recent shellmodel calculations for both nuclei. c 2004 MAIK "Nauka/Interperiodica". 
Article: Systematic study of L⩽ 3 giant resonances in Sm isotopes via multipole decomposition analysis
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ABSTRACT: Backgroundfree inelastic scattering spectra have been obtained for five Sm isotopes with 386MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the compressionalmode giant resonances. The strength distributions for the L⩽3 isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the densitydependent singlefolding model. We observed a splitting of the giant monopole resonance because of its mixing with the giant quadrupole resonance. For the isoscalar giant dipole resonance, the observed effects of deformation are different for the low and highexcitationenergy components. Evidence has been obtained for the theoretically predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance. 
Article: Extraction of Neutron Density Distributions from Proton Elastic Scattering at Intermediate Energies
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ABSTRACT: Cross sections, analyzing powers and spin rotation parameters of proton elastic scattering from 58 Ni and 120Sn have been measured at intermediate energies. Obtained data have been analyzed in the framework of relativistic impulse approximations. In order to explain the 58 Ni data, it was necessary to modify NN interactions in the nuclear medium by changing coupling constants and masses of σ and ω mesons. For 120Sn, by assuming the same modification of NN interactions and by using proton densities deduced from charge densities, the neutron density distribution was searched so as to reproduce 120Sn data at 300 MeV.  [Show abstract] [Hide abstract]
ABSTRACT: The isoscalar giant dipole resonance (ISGDR) in 208Pb has been studied via inelastic alphascattering of 400 MeV at extremely forward angles, including 0°. Energy spectra virtually free from instrumental background have been obtained with a raytracing technique, and the ISGDR strength distribution has been extracted using a multipoledecomposition analysis. These results lead to a value for nuclear incompressibility that is consistent for both the isoscalar dipole and monopole modes.  [Show abstract] [Hide abstract]
ABSTRACT: The isoscalar giant dipole resonance (ISGDR) in has been investigated with inelastic αscattering of 400 MeV at extremely forward angles, including 0°. Energy spectra, virtually free from instrumental background, have been obtained and the ISGDR strength distribution has been extracted using a multipoledecomposition analysis (MDA). A differenceofspectra approach yields the same ISGDR centroid energy as with MDA. These results lead to a value for nuclear incompressibility that is consistent for both the isoscalar dipole and monopole modes.  [Show abstract] [Hide abstract]
ABSTRACT: Charged particle decay of the shole state in 11B was measured in coincidence with the quasifree 12C(p,2p) reaction at 392 MeV incident energy. Tritondecay was found to be dominant despite its smaller Qvalue than that of αdecay. The measured decay pattern is compared to the results of statistical model and microscopic SU(3)cluster model calculations. The energy spectrum around the shole state exhibits three bumplike structures, which can be qualitatively explained by a recent shellmodel calculation. 
Conference Paper: COMPRESSIONALMODE GIANT RESONANCES IN DEFORMED NUCLEI
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ABSTRACT: Backgroundfree inelastic scattering spectra have been obtained for the Sm isotopes with 400 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the compressionalmode giant resonances. The strength distributions for the isoscalar giant resonances (L⩽3) have been extracted for the spherical nucleus 144Sm and the deformed nucleus 154Sm. We have observed that the effects of deformation are different for the low and highexcitationenergy components of the isoscalar giant dipole resonance in 154Sm. Evidence for the theoretically predicted coupling between the isoscalar dipole resonance and the highenergy octupole resonance is reported.  [Show abstract] [Hide abstract]
ABSTRACT: Spin observables have been measured for (p, 2p) reactions aiming at studying medium effects on NN interactions in nuclear field. Observed strong densitydependent reduction of the analyzing power is consistent with a model calculation where reduction of nucleon and meson masses are taken into account. The spintransfer coefficients, which data are not reproduced by the model calculation, are found to be sensitive to reduction rate of each meson mass and have a possibility to test scaling lows in mass reductions.  [Show abstract] [Hide abstract]
ABSTRACT: We have carried out investigation on the strength distribution of ISGDR excitations in ^90Zr nuclei via inelastic scattering of 400 MeV α particles obtained from the ringcyclotron facility at RCNP, Japan. Measurements have been carried out over several angles between 0^circ and 12.5^circ. The instrumental background is completly eliminated by using the optics of the GRAND RAIDEN spectrometer. The exitation energy spectrum obtained at each angle is divided in to 1 MeV energy bins. The angular distributions obtained for each of these bins are then compared to the distorted wave Born approximation(DWBA) calculations to obtain the strength distribution of isoscalar E0, E1, E2, E3, E4 and E5 modes via multipoledecomposition technique. Detailed results of the analysis will be presented.  [Show abstract] [Hide abstract]
ABSTRACT: Cross sections and polarization transfer observables in the $^{16}$O$(p,p')$ reactions at 392 MeV were measured at several angles between $\theta_{lab}=$ 0$^\circ$ and 14$^\circ$. The nonspinflip (${\Delta}S=0$) and spinflip (${\Delta}S=1$) strengths in transitions to several discrete states and broad resonances in $^{16}$O were extracted using a modelindependent method. The giant resonances in the energy region of $E_x=19$27 MeV were found to be predominantly excited by ${\Delta}L=1$ transitions. The strength distribution of spindipole transitions with ${\Delta}S=1$ and ${\Delta}L=1$ were deduced. The obtained distribution was compared with a recent shell model calculation. Experimental results are reasonably explained by distortedwave impulse approximation calculations with the shell model wave functions. Comment: 28 pages RevTex, including 9 figures, to be published in Phys. Rev. C.; a typo in Eq. (3b) was corrected  [Show abstract] [Hide abstract]
ABSTRACT: The isoscalar giant dipole resonance (ISGDR) has been investigated in 208Pb using inelastic scattering of 400 MeV alpha particles at forward angles, including 0deg. Using the superior capabilities of the Grand Raiden spectrometer, it has been possible to obtain spectra devoid of any "instrumental" background. The ISGDR strength distribution has been extracted from a multipolecomposition of the observed spectra. The implication of these results on the experimental value of nuclear incompressibility are discussed. Comment: 5 pages total. 3 figures. Invited talk at INPC2001,Berkeley, July 30Aug. 3, 2001  [Show abstract] [Hide abstract]
ABSTRACT: Demand for nearzerodegree measurements using a magnetic spectrometer is increasing with the growing interest in the study of L=0 nuclear excitation modes. For the precise determination of scattering angles near 0°, both horizontal and vertical scattering angle components have to be measured with good accuracy. It is, however, not easy to realize a good vertical angle resolution using modern highresolution magnetic spectrometers with small vertical angle magnifications, like “Grand Raiden” at RCNP or “K600” at IUCF.A new ionoptical mode which enables the precise determination of vertical components of scattering angles from vertical position measurements in the focal plane has been developed for these spectrometers. For the wide range of spatial as well as momentum acceptances, vertical angle resolution better than is realized for Grand Raiden at RCNP.  [Show abstract] [Hide abstract]
ABSTRACT: Clean spectra of inelasic (α,α′) scattering at Eα = 400 MeV and at forward angles (0° ∼ 7.5°) have been measured to study the giant resonances in 144Sm, 148 Sm, 150Sm, 152Sm, and 154Sm. For 144Sm and 154Sm, excitation strengths of the giant monopole resonance were extracted by means of the multipole decomposition analysis. The bump around Ex ∼ 15 MeV in 0° spectrum for the deformed nucleus 154Sm consists of two peaks. The result of the multipole decomposition analysis showed that the width of the GMR in 154Sm was a factor of 1.7 wider than that in the spherical nucleus 144Sm and that the L = 0 strength in 154Sm was fitted well using two Lorentzian functions.
Publication Stats
296  Citations  
48.79  Total Impact Points  
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Institutions

2012

Hatano Research Institute, Food and Drug Safety Center
Hatano, Kanagawa, Japan


19992004

Kyoto University
 Department of Physics II
Kioto, Kyōto, Japan
