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51.
Tao Song Corey N. W. Lam Dominic C. M. Ng Galina Orlova Julia Laskin De-Cai Fang Ivan K. Chu 《Journal of the American Society for Mass Spectrometry》2009,20(6):972-984
The dissociation of [CuII(L)His]•2+ complexes [L=diethylenetriamine (dien) or 1,4,7-triazacyclononane (9-aneN3)] bears a strong resemblance to the previously reported behavior of [CuII(L)GGH]•2+ complexes. We have used low-energy collision-induced dissociation experiments and density functional theory (DFT) calculations
at the B3LYP/6-31+G(d) level to study the macrocyclic effect of the auxiliary ligands on the formation of His•+ from prototypical [CuII(L)His]•2+ systems. DFT revealed that the relative energy barriers of the same electron-transfer (ET) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ are very similar, with the ET reactions of [CuII(9-aneN3)His]•2+ leading to the generation of two distinct His•+ species; in contrast, the proton transfer (PT) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ differ considerably. The PT reactions of [CuII(9-aneN3)His]•2+ are associated with substantially higher barriers (>13 kcal/mol) than those of [CuII(dien)His]•2+. Thus, the sterically encumbered auxiliary 9-aneN3 ligand facilitates ET reactions while moderating PT reactions, allowing the formation of hitherto nonobservable histidine
radical cations. 相似文献
52.
Dominic G. B. Edelen 《International Journal of Theoretical Physics》1989,28(6):633-649
Realization of the Poincaré groupP
10 as a subgroup ofGL(5,R) that maps a 4-dimensional affine set into itself has been shown to lead to a direct Yang-Mills gauging process. This paper discusses the differences between direct gauge theory forP
10 and previously published works. These differences are fundamental, both physically and mathematically, and lead to marked departures from previous concepts and interpretations. The translation subgroup is correctly gauged; the metric structure and metric compatibility are derived from the gauging process rather than assumed; spin structures are automatically incorporated in a consistent manner; the local holonomy group is shown to be the component of the Lorentz group connected to the identity; the geometric analog of Yang-Mills minimal coupling precludes dependence of the free gauge field Lagranian on torsion; and the theory reduces exactly to general relativity when the momentumenergy complex is symmetric and all matter fields are spin-free. Gravitational effects on neutral test particles are shown to arise from the compensating 1-forms for local action of Lorentz boosts. The compensating 1-forms for local action of the translation subgroup may be interpreted as space-time dislocations, while the compensating 1-forms for the rotation subgroup can be viewed as space-time disclinations. Unfortunately, there are no clear physical meanings that can be ascribed to space-time dislocations or disclinations. 相似文献
53.
Jean-Pierre Dussault 《Computational Optimization and Applications》2009,44(3):373-383
We refine the speed of convergence analysis for the quadratic augmented penalty algorithm. We improve the convergence order
from 4/3 to 3/2 for the first order multiplier iteration. For the second order iteration, we generalize the analysis, and
consider a primal–dual variant which asymptotically reduces to a Newton step for the optimality conditions. 相似文献
54.
55.
B(C(6)F(5))(3) promotes regio- and stereoselective cyclizations of unsaturated alkoxysilanes to generate oxasilinanes and oxasilepanes. The same products are available directly from alkenols via tandem silylation and hydrosilylation. 相似文献
56.
Wai Yi Kelly Chan T. W. Dominic Chan Peter B. O’Connor 《Journal of the American Society for Mass Spectrometry》2010,21(6):1012-1015
Electron-transfer dissociation (ETD) with supplemental activation of the doubly charged deamidated tryptic digested peptide
ions allows differentiation of isoaspartic acid and aspartic acid residues using the c + 57 or z • − 57 peaks. The diagnostic peak clearly localizes and characterizes the isoaspartic acid residue. Supplemental activation
in ETD of the doubly charged peptide ions involves resonant excitation of the charge reduced precursor radical cations and
leads to further dissociation, including extra backbone cleavages and secondary fragmentation. Supplemental activation is
essential to obtain a high quality ETD spectrum (especially for doubly charged peptide ions) with sequence information. Unfortunately,
the low-resolution of the ion trap mass spectrometer makes detection of the diagnostic peak, [M-60], for the aspartic acid
residue difficult due to interference with side-chain loss from arginine and glutamic acid residues. 相似文献
57.
Siriani DF 《Optics letters》2011,36(5):701-703
Coupled waveguides, such as those used as optical filters, switches, or couplers, are investigated in the context of coherence theory. A stochastic source is introduced to the standard coupled-mode model. Decay in the power transferred between the waveguides as a function of distance is predicted. Application of this result in the form of an interferometric spectrometer is explored. 相似文献
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