279 resultados para matrix inversion


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Search for low-spin signature inversion in the pi i(13/2) circle times nu i(13/2) bands in odd-odd Au-182,Au-184,Au-186 has been conducted through the standard in-beam gamma-spectroscopy techniques. The experiments for Au-182 and 186Au have been performed in the Japan Atomic Energy Agency (JAEA) via the Sm-152(Cl-35,5n)Au-182 and Yb-172(F-19,5n)Au-186 reactions, respectively. A study of Au-184 has been made using a multi-detector array GASP in LNL, Italy, via the Tb-159(Si-29,4n)Au-184 reaction. The pi i(13/2) circle times nu i(13/2) bands in these three nuclei have been identified and extended up to high-spin states. In particular, the inter-band connection between the pi i(13/2) nu i(13/2) band and the ground-state band in 184 Au has been established, leading to a firm spin-and-parity assignment for the pi i(13/2) circle times nu i(13/2) band. The low-spin signature inversion is found in the pi i(13/2) circle times nu i(13/2) bands in Au-182,Au-184,Au-186 according to our spin-assignment and the signature crossing observed at high-spin states.

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We calculate the in-medium nucleon-nucleon scattering cross sections from the G-matrix using the Dirac-Brueckner-Hartree-Fock (DBHF) approach. And we investigate the influence of the different representations of the G-matrix to the cross sections, the difference of which is mainly from the different effective masses.

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High spin states in Re-174 are investigated via the Sm-152(Al-27, 5n gamma)Re-174 reaction and gamma-gamma coincidence relationships are analysed carefully. A new band is identified due to its spectroscopic connection with the known pi 1/2(-)[541] circle times nu 1/2(-)[521] band. This band is proposed to be the ground-state band built on the pi 1/2(-)[541] circle times nu 5/2(-)[512] configuration in view of the low-lying intrinsic states in the neighbouring odd-mass nuclei. It is of particular interesting that the new band exhibits a phenomenon of low-spin signature inversion, providing a new situation for theoretical investigations.

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Search for low-spin signature inversion in the pi i(13/2) circle times nu i(13/2) bands in odd-odd Au-182,Au-184,Au-186 has been conducted through the standard in-beam gamma-spectroscopy techniques via the Sm-152(Cl-35,5n) Au-182, Yb-172(F-19,5n) (186)An, and Tb-159(Si-29,4n) (184)An reactions, respectively. The pi i(13/2) circle times nu i(13/2) bands in these three nuclei have been identified and extended up to high-spin states. In particular, the inter-band connection between the pi i(13/2) circle times nu i(13/2) band and the ground-state band in Au-184 has been established, leading to a firm spin-and-parity assignment for the pi i(13/2) circle times nu i(13/2) band. The low-spin signature inversion is found in the pi i(13/2) circle times nu i(13/2) bands according to our spin-assignment and-the signature crossing observed at high-spin states.

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Excited states in Tl-188,Tl-190 have been studied experimentally by means of in-beam gamma spectroscopy techniques, and resulted in the identification of a strongly coupled band based on the pi h(9/2) circle times nu i(13/2) configuration with oblate deformation. The oblate band in doubly odd Tl nuclei shows low-spin signature inversion. It is the first experimental observation of low-spin signature inversion for a band associated with the oblate pi h(9/2) circle times nu i(13/2) configuration.

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High-spin Level structure of Tl-188 has been studied via Gd-157 (Cl-35,4n) fusion-evaporation reaction at beam energy of 170MeV. A rotational band built on the pi h(9/2) circle times nu i(13/2) configuration with oblate deformation has been established. Spin values have been proposed to the pi h(9/2) circle times nu i(13/2) oblate band based on the similarities between the oblate band of Tl-188 and those in odd-odd Tl190-200. With the spin assignments, the low-spin signature inversion has been revealed for the pi h(9/2) circle times nu i(13/2) oblate band of Tl-188. The low-spin signature inversion can be interpreted qualitatively in the framework of the quasi-particles plus rotor model including a J dependent p-n residual interaction.

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A modified microfiltration membrane has been prepared by blending a matrix polymer with a functional polymer. Cellulose acetate (CA) was blended with polyethyleneimine (PEI), which was then crosslinked by polyisocyanate, in a mixture of solvents. In the membrane, PEI can supply coupling sites for ligands in affinity separation or be used as ligands for metal chelating, removal of endotoxin or ion exchange. The effects of the time of phase inversion induced by water vapor, blended amount of PEI and amount of crosslinking agent on membrane performance were investigated. The prepared blend membranes have specific surface area of 12.04-24.11 m(2)/g and pure water flux (PWF) of 10-50 ml/cm(2) min with porosity of 63-75%. The membranes, made of 0.15 50 wt.% PEI/CA ratio and 0.5 crosslinking agent/PEI ratio, were applied to adsorbing Cu2+ and bovine serum albumin (BSA) individually. The maximum adsorption capacity of Cu2+ ion on the blend membrane is 7.42 mg/g dry membrane. The maximum adsorption capacities of BSA on the membranes with and without chelating Cu2+ ion are 86.6 and 43.8 mg/g dry membrane, respectively. (C) 2004 Elsevier B.V. All rights reserved.

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The isoflavonoids in Radix astragali were determined and identified by HPLC-photodiode array detection-MS after extraction employing matrix solid-phase dispersion (MSPD). As a new sample preparation method for R. astragali, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and Soxhlet extraction. The amounts of two major components in this herb, formononetin (6) and ononin (2), were determined based on their authentic standards. Four major isoflavonoids, formononetin (6), ononin (2), calycosin (5) and its glycoside (1), and three minor isoflavonoids, (6aR,11aR)-3-hydroxy-9, 10-dimethoxypterocarpan (7), its glycoside (3), and (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavone-7-O-beta-D-glycoside (4), were identified based on their characteristic two-band UV spectra and [M + H](+), [aglycone + H](+) and [A1 + H](+) ions, etc. The combined MSPD and HPLC-DAD-MS method was suitable for quantitative and qualitative determination of the isoflavonoids in R. astragali. (C) 2003 Elsevier B.V. All rights reserved.