排序方式: 共有80条查询结果,搜索用时 15 毫秒
61.
Butler F Fu X Kalbfleisch G Lambrecht M Ross WR Skubic P Snow J Wang PL Wood M Bortoletto D Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Schaffner SF Shibata EI Shipsey IP Wang PN Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH Wang CH Dominick J Sanghera S Skwarnicki T Stroynowski R Artuso M He D Goldberg M Horwitz N Kennett R Moneti GC Muheim F Mukhin Y Playfer S Rozen Y Stone S Thulasidas M Vasseur G Zhu G Bartelt J Csorna SE Egyed Z Jain V Sheldon P Akerib DS Barish B 《Physical review D: Particles and fields》1994,49(1):40-57
62.
Alam MS Kim IJ Nemati B O'Neill J Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Ross WR Skubic P Snow J Wang PL Wood M Bortoletto D Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Schaffner SF Shibata EI Shipsey IP Wang PN Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH Wang CH Dominick J Sanghera S 《Physical review letters》1993,71(9):1311-1315
63.
Kinoshita K Pipkin FM Procario M Wilson R Wolinski J Xiao D Zhu Y Ammar R Baringer P Coppage D Davis R Haas P Kelly M Kwak N Lam H Ro S Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Romero V Sun CR Wang P Zoeller MM Goldberg M 《Physical review D: Particles and fields》1991,43(9):2836-2842
64.
Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Lou XC Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Kennett R Mestayer MD Moneti GC Rozen Y Rubin P Skwarnicki T Stone S Thusalidas M Yao W Zhu G Barnes AV Bartelt J Csorna SE Letson T Alexander J 《Physical review D: Particles and fields》1992,45(3):752-770
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66.
D. A. Schwartz E. D. Walter S. J. McIlwain V. N. Krymov D. J. Singel 《Applied magnetic resonance》1999,16(2):223-236
Initial results are reported of an EPR study, conducted at 94.9 GHz, of a thermally annealed, neutron-irradiated white sapphire (α-Al2O3) single-crystal fiber. The optical centers produced in sapphire by neutron irradiation and thermal annealing are of interest for optical technologies involving the phenomenon of spectral hole-burning. While these centers have been modeled as consisting of electrons localized at anion vacancies, experimental tests of this model have been very limited. EPR spectroscopy — a choice technique for elucidating structural details of such color centers — reveals signals from numerous paramagnetic centers in this material. The predominant signals, with amplitudes a hundredfold greater than any other signals, derive from three closely related, highspin-multiplicity centers. These centers do not, however, derive from radiation-induced lattice defects: they are readily identified as Cr3+ (S = 3/2) and a pair of crystallographically equivalent Fe3+ (S=5/2) impurity ions. The advantages of high-frequency-EPR instrumentation in facilitating this identification are presented and discussed in detail. These advantages include enhanced sensitivity for this volume-limited, fiber sample. Moreover, the analysis of the spectra — entailing spectral assignments, evaluation of the spin-Hamiltonian parameters, and spin-counting — is greatly facilitated when the Zeeman interaction is dominant. 相似文献
67.
Sally M. Yacout Kelsey L. McIlwain Shama P. Mirza Elizabeth R. Gaillard 《Photochemistry and photobiology》2019,95(1):183-191
With increasing age, there is an observable loss of melanin in retinal pigment epithelial (RPE) cells. It is possible that degradation of the pigment contributes to the pathogenesis of retinal disease, as the cellular antioxidant material is depleted. Functionally, intact melanin maintains protective qualities, while oxidative degradation of melanin promotes reactive oxygen species (ROS) generation and formation of metabolic byproducts, such as melanolipofuscin. Understanding the structural and functional changes to RPE melanin with increasing age may contribute to a better understanding of disease progression and risk factors for conditions such as age‐related macular degeneration (AMD). In this study, human donor RPE melanin is characterized using MALDI mass spectrometry to follow melanin degradation trends. In vitro models using ARPE‐19 cells are used to assess photo‐reactivity in repigmented cells. Significant protection against intracellular ROS produced by blue light is observed in calf melanin‐pigmented cells versus unpigmented and black latex bead controls (P < 0.0001). UV‐B exposure to aged human melanin‐pigmented cells results in a significant increase in nitric oxide production versus control cells (P < 0.001). Peroxide‐treated synthetic melanin is characterized to elucidate degradation products that may contribute to RPE cell damage. 相似文献
68.
Gamma-ray spectrometry combined with acceptable knowledge (GSAK) is a technique for the characterization of certain remote-handled transuranic (RH-TRU) wastes. GSAK uses gamma-ray spectrometry to quantify a portion of the fission product inventory of RH-TRU wastes. These fission product results are then coupled with calculated inventories derived from acceptable process knowledge to characterize the radionuclide content of the assayed wastes. GSAK has been evaluated and tested through several test exercises. This paper describes the GSAK approach, while Part II presents the test results. 相似文献
69.
Gary S. Groenewold Dr. Michael J. Van Stipdonk Prof. Wibe A. de Jong Dr. Jos Oomens Dr. Garold L. Gresham Dr. Michael E. McIlwain Dr. Da Gao Dr. Bertrand Siboulet Dr. Lucas Visscher Prof. Michael Kullman Nick Polfer Prof. 《Chemphyschem》2008,9(9):1278-1285
UO2+–solvent complexes having the general formula [UO2(ROH)]+ (R=H, CH3, C2H5, and n‐C3H7) are formed using electrospray ionization and stored in a Fourier transform ion cyclotron resonance mass spectrometer, where they are isolated by mass‐to‐charge ratio, and then photofragmented using a free‐electron laser scanning through the 10 μm region of the infrared spectrum. Asymmetric O=U=O stretching frequencies (ν3) are measured over a very small range [from ~953 cm?1 for H2O to ~944 cm?1 for n‐propanol (n‐PrOH)] for all four complexes, indicating that the nature of the alkyl group does not greatly affect the metal centre. The ν3 values generally decrease with increasing nucleophilicity of the solvent, except for the methanol (MeOH)‐containing complex, which has a measured ν3 value equal to that of the n‐PrOH‐containing complex. The ν3 frequency values for these U(V) complexes are about 20 cm?1 lower than those measured for isoelectronic U(VI) ion‐pair species containing analogous alkoxides. ν3 values for the U(V) complexes are comparable to those for the anionic [UO2(NO3)3]? complex, and 40–70 cm?1 lower than previously reported values for ligated uranyl(VI) dication complexes. The lower frequency is attributed to weakening of the O?U?O bonds by repulsion related to reduction of the U metal centre, which increases electron density in the antibonding π* orbitals of the uranyl moiety. Computational modelling of the ν3 frequencies using the B3LYP and PBE functionals is in good agreement with the IRMPD measurements, in that the calculated values fall in a very small range and are within a few cm?1 of measurements. The values generated using the LDA functional are slightly higher and substantially overestimate the trends. Subtleties in the trend in ν3 frequencies for the H2O–MeOH–EtOH–n‐PrOH series are not reproduced by the calculations, specifically for the MeOH complex, which has a lower than expected value. 相似文献
70.
Bowcock T Kinoshita K Pipkin FM Procario M Wilson R Wolinski J Xiao D Jawahery A Park CH Poling R Fulton R Haas P Hempstead M Jensen T Johnson DR Kagan H Kass R Morrow F Whitmore J Baringer P McIlwain RL Miller DH Ng CR Shibata EI Yao WM Alam MS Chen D Katayama N Kim IJ Li WC Lou XC Sun CR Tanikella V Bortoletto D Goldberg M Horwitz N Lubrano P Mestayer MD Moneti GC Sharma V Shipsey IP Skwarnicki T Csorna SE Letson T Brock IC Ferguson T Artuso M Bebek C Berkelman K Blucher E Byrd J Cassel DG 《Physical review letters》1989,62(11):1240-1242