The Experts below are selected from a list of 21 Experts worldwide ranked by ideXlab platform
Kimiaki Saito - One of the best experts on this subject based on the ideXlab platform.
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Spectrum-dose conversion operator of NaI(Tl) and CsI(Tl) scintillation detectors for air dose rate measurement in contaminated environments
Journal of environmental radioactivity, 2016Co-Authors: Shuichi Tsuda, Kimiaki SaitoAbstract:Spectrum-dose conversion operators, the G(E) functions, for common NaI(Tl) scintillation survey meters and CsI(Tl) detectors are obtained for measurements in a semi-infinite plane of contaminated ground field by photon-emitting radionuclides (ground source). The calculated doses at a height of 100 cm from the ground in 137Cs-contaminated environments by the Monte Carlo simulation technique are compared with those obtained using the G(E) functions by assuming idealized irradiation geometries such as anterior-posterior or isotropic. The simulation reveals that one could overestimate air dose rates in the environment by a maximum of 20-30% for NaI(Tl) detectors and 40-50% for CsI(Tl) detectors depending on photon energy when using the G(E) functions assuming idealized irradiation geometries for ground source measurements. Measurements obtained after the nuclear accident in Fukushima reveal that the doses calculated using a G(E) function for a unidirectional irradiation geometry are 1.17 times higher than those calculated using a G(E) function for the ground source in the case of a CsI(Tl) scintillation detector, which has a rectangular Parallelepiped Crystal (13 × 13 × 20 mm3). However, if a G(E) function is used assuming irradiation to a surface of the detector, the doses agree with those of the ground source within 2%. These results indicate that in contaminated environments, the commonly used scintillation-based detectors overestimate doses within the acceptable limit. In addition, the degree of overestimation depends on the irradiation direction of each detector assumed for developing the G(E) function. With regard to directional dependence of the detectors, reliable air dose rates in the environment can be obtained using the G(E) function determined in unidirectional irradiation geometry, provided that the irradiation surface of the Crystal is determined properly.
Shuichi Tsuda - One of the best experts on this subject based on the ideXlab platform.
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Spectrum-dose conversion operator of NaI(Tl) and CsI(Tl) scintillation detectors for air dose rate measurement in contaminated environments
Journal of environmental radioactivity, 2016Co-Authors: Shuichi Tsuda, Kimiaki SaitoAbstract:Spectrum-dose conversion operators, the G(E) functions, for common NaI(Tl) scintillation survey meters and CsI(Tl) detectors are obtained for measurements in a semi-infinite plane of contaminated ground field by photon-emitting radionuclides (ground source). The calculated doses at a height of 100 cm from the ground in 137Cs-contaminated environments by the Monte Carlo simulation technique are compared with those obtained using the G(E) functions by assuming idealized irradiation geometries such as anterior-posterior or isotropic. The simulation reveals that one could overestimate air dose rates in the environment by a maximum of 20-30% for NaI(Tl) detectors and 40-50% for CsI(Tl) detectors depending on photon energy when using the G(E) functions assuming idealized irradiation geometries for ground source measurements. Measurements obtained after the nuclear accident in Fukushima reveal that the doses calculated using a G(E) function for a unidirectional irradiation geometry are 1.17 times higher than those calculated using a G(E) function for the ground source in the case of a CsI(Tl) scintillation detector, which has a rectangular Parallelepiped Crystal (13 × 13 × 20 mm3). However, if a G(E) function is used assuming irradiation to a surface of the detector, the doses agree with those of the ground source within 2%. These results indicate that in contaminated environments, the commonly used scintillation-based detectors overestimate doses within the acceptable limit. In addition, the degree of overestimation depends on the irradiation direction of each detector assumed for developing the G(E) function. With regard to directional dependence of the detectors, reliable air dose rates in the environment can be obtained using the G(E) function determined in unidirectional irradiation geometry, provided that the irradiation surface of the Crystal is determined properly.
Robin D. Rogers - One of the best experts on this subject based on the ideXlab platform.
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X-Ray Structure and Crystal Lattice Interactions of the Taxol Side-Chain Methyl Ester
Pharmaceutical Research, 1991Co-Authors: John R. Peterson, Robin D. RogersAbstract:A colorless, Parallelepiped Crystal of methyl (2 R ,3 S )- N -benzoyl-3-phenylisoserinate belonging to the space group P2_l with a = 5.414(4), b = 7.813(1), c = 17.802(7) Å, β = 90.87(4)°, Z = 2, V = 752.9 Å^3, D _calc = 1.32 g cm^−3, and µ_calc = 1.02 cm^−1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [ F _o ≥ 5σ(F_o)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the Crystal lattice of this compound.
Kayako Hori - One of the best experts on this subject based on the ideXlab platform.
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Crystalline polymorphs of higher homologues of 4-alkoxy-4-cyanobiphenyl, nOCB (n=8,9,10 and 12)
Liquid Crystals, 1999Co-Authors: Kayako HoriAbstract:Phase transition behaviour was studied for the Crystalline polymorphs of 4-alkoxy-4-cyanobiphenyl, n OCB (n=8,9,10 and 12), by means of differential scanning calorimetry (DSC). The square-plate Crystal form, which is composed of distinct smectic-like bilayers with infinite networks of closely arranged CN groups, appears generally for n>7. It is a metastable phase for n=7 and 8. In addition to the square-plate Crystal, 8OCB has needle and Parallelepiped Crystal forms, which are metastable, and the most stable Crystalline phase found in a commercially available powder specimen. The Parallelepiped Crystal shows three competitive processes depending on heating rate: (1) gradual stabilization to the most stable Crystalline phase, even at room temperature, (2) transformation to the needle Crystal, and (3) direct transformation to the smectic A phase. On the other hand, the square-plate Crystal is stable at room temperature and transforms to another Crystalline phase, which is supercooled in the commercially ava...
John R. Peterson - One of the best experts on this subject based on the ideXlab platform.
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X-Ray Structure and Crystal Lattice Interactions of the Taxol Side-Chain Methyl Ester
Pharmaceutical Research, 1991Co-Authors: John R. Peterson, Robin D. RogersAbstract:A colorless, Parallelepiped Crystal of methyl (2 R ,3 S )- N -benzoyl-3-phenylisoserinate belonging to the space group P2_l with a = 5.414(4), b = 7.813(1), c = 17.802(7) Å, β = 90.87(4)°, Z = 2, V = 752.9 Å^3, D _calc = 1.32 g cm^−3, and µ_calc = 1.02 cm^−1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [ F _o ≥ 5σ(F_o)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the Crystal lattice of this compound.
