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991.
Robert Sauer 《Archiv der Mathematik》1955,6(3):180-184
Ohne ZusammenfassungHerrn Wilhelm SÜss zum 60. Geburtstag am 7. 3. 1955 gewidmet 相似文献
992.
Excitation energy transfer in C-phycocyanin is modeled using the Forster inductive resonance mechanism. Detailed calculations are carried out using coordinates and orientations of the chromophores derived from X-ray crystallographic studies of C-phycocyanin from two different species (Schirmer et al, J. Mol. Biol. 184 , 257–277 (1985) and ibid. , 188 , 651-677 (1986)). Spectral overlap integrals are estimated from absorption and fluorescence spectra of C-phycocyanin of Mastigocladus laminosus and its separated subunits. Calculations are carried out for the β-subunit, αβ-monomer, (αβ)3 -trimer and (αβ)0 -hexamer species with the following chromophore assignments: β155 = 's'(sensitizer), β84 ='f (fluorescer) and α84 ='m'(intermediate):]:. The calculations show that excitation transfer relaxation occurs to 3=98% within 200 ps in nearly every case; however, the rates increase as much as 10-fold for the higher aggregates. Comparison with experimental data on fluorescence decay and depolarization kinetics from the literature shows qualitative agreement with these calculations. We conclude that Forster transfer is sufficient to account for all of the observed fluorescence properties of C-phycocyanin in aggregation states up to the hexamer and in the absence of linker polypeptides. 相似文献
993.
Detlev Joachimi Peter R. Ashton Christiane Sauer Neil Spencer Carsten Tschierske Kerstin Zab 《Liquid crystals》1996,20(3):337-348
Various paracyclophane derivatives incorporating 4,4'-biphenyl, 2,5-diphenyl-1,3,4-thiadiazole, phenyl benzoate and 2,6-disubstituted naphthyl rigid cores were synthesized and their mesomorphic behaviour was studied using polarizing microscopy, DSC and X-ray diffraction. Most of these macrocyclic compounds possess liquid crystalline properties with unexpectedly high clearing temperatures compared to those of conventional calamitic mesogens. In this way, the coupling of two appropriate rigid units using flexible chains to form a macrocycle constitutes a new and powerful approach towards mesophase induction and stabilization. The types of mesophase formed by these macrocycles do not depend only on the nature of the bridging chains, but also strongly on the structure of the rigid aromatic system. The smectic A phase and the E phase are formed by polyetherbiphenylophanes. Poly-ethercyclophanes incorporating the 2,5-diphenylthiadiazole rigid core form nematic and smectic C phases. The nematic phase is the only mesophase when the rigid core is the phenyl benzoate unit. No mesomorphic properties could be detected for macrocycles which featured either the benzyl phenyl ether moiety or the 2,6-disubstituted naphthalene unit in their constitution. 相似文献
994.
J.-L. Lu S. Kaya T.K. Todorova J. Sauer S. Shaikhutdinov H.-J. Freund 《Surface science》2006,600(13):L164
We have observed formation of one-dimensional silica structures of 0.5 nm in width on Mo(1 1 2) single crystal surface. Combination of high-resolution scanning tunneling microscopy, photoelectron and infrared spectroscopy, and density functional theory provides strong evidence for formation of paired rows of corner sharing [SiO4] tetrahedra chemisorbed on a metal substrate. 相似文献
995.
Tarek S. El-Bawab Chintan H. Vaishnav Anura P. Jayasumana Henryk Temkin Jon R. Sauer Heinz A. Willebrand 《Fiber and Integrated Optics》1997,16(3):237-260
The wavelength division multiplexing (WDM) network architectures, in general, are based on transmitters and/or receivers that can be precisely and speedily tuned to predetermined, fixed wavelengths. These requirements are not easy to meet in practice. Robust WDM, the subject of this paper, has been introduced as a technique to implement WDM in the local area. The strength of this novel approach is that it does not rely on wavelength-sensitive devices that are required to perform with extreme stability. This paper describes the basis of this approach and presents two types of medium access control (MAC) protocols that are suitable for Robust WDM local area networks (LANs). The performance of networks based on these protocols is discussed in detail. It is shown that the new approach has considerable promise for WDM networks in the local area. 相似文献
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The bond lengths and angels obtained by means of a 4–31G basis agree with electron diffraction data. The calculated SiOSi bending potential, showing a minimum for the linear arrangement, is discussed with regard to available experimental information. Calculated dipole moments and ionization potentials are also in reasonable agreement with experimental data. Comparison is made with STO-3G and INDO results which both overestimate the stability of cyclic structures. 相似文献
1000.
R. Sauer 《Solid State Communications》1974,14(6):481-483
The well known excitonic and condensed electron—hole state emission spectra of silicon are substantially modified in a narrow typical range of higher doping levels. The new spectra and their dependence on excitation level can be interpreted partially by the existence of bound multiple-exciton complexes of predominantly higher order. Some features are not yet understood. 相似文献