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Binding energy spectra of the valence electrons of the open shell molecule NO have been obtained up to 55 eV at azimuthal angles of 0° and 7° using binary (e, 2e) spectroscopy at an impact energy of 1200 eV. The momentum distribution has been obtained for the least tightly bound (unpaired) electron, removal of which leads to formation of the X 1Σ+ ground state of NO+. Momentum distributions have also been measured at 21.0 and 40.5 eV. The measured momentum distributions are compared with several literature wavefunctions of varying complexity. They are found to be in excellent agreement with those calculated using the natural spin orbital wavefunctions of Kouba and Ohrn.  相似文献   
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Previous studies using dideuterium as a solute have demonstrated the importance for orientation of the interaction between the solute molecular quadrupole moment and the average electric field gradient present in liquid crystals. With the aim of learning about additional orientational mechanisms, we have studied the temperature dependence of the 2H-NMR spectra of the liquid crystal 5CB-d19 as the solute in three liquid crystal mixtures: 55 wt % 1132/EBBA, 56·5 wt % 1132/EBBA and 70 wt % 5CB/EBBA. In these mixtures, the contribution from the environment to the average electric field gradient at the 2H nucleus of dideuterium is zero. The spectra of 5CB-d19 in the mixtures 55 wt % 1132/EBBA and 56·5 wt % 1132/EBBA are equivalent, but are different from those in 70 wt % 5CB/EBBA. The spectra of 5CB in 55 wt % 1132/EBBA and 70 wt % 5CB/EBBA are analysed using two different models for the short range potential, and param eters of the models are used to compare the potentials in the different mixtures. For a given spectral splitting of the chain C1 deuteron, the reduced short range potential is the same in all three mixtures studied. The spectral differences observed are a consequence of different nematic-isotropic phase transition temperatures combined with the effect of trans/gauche-isomerization in the hydrocarbon chain.  相似文献   
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Isospectral problem of both 2D and 3D Euler equations of inviscid fluids, is investigated. Connections with the Clay problem are described. Spectral theorem of the Lax pair is studied.  相似文献   
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Scheduling a sequence of tasks––in the acceptation of finding the execution times––is not a trivial problem when the optimization criterion is irregular as for instance in earliness–tardiness problems. This paper presents an efficient dynamic programming algorithm to solve the problem with general cost functions depending on the end time of the tasks, idle time costs and variable durations also depending on the execution time of the tasks. The algorithm is also valid when the precedence graph is a tree and it can be adapted to determine the possible execution windows for each task not exceeding a maximum fixed cost.  相似文献   
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We show that for every n there are two simple curves on the torus intersecting at least n times without the two curves folding or spiralling with respect to each other.  相似文献   
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A non-empirical molecular orbital method, particularly suitable for calculations on cage-like molecules, is described. The method uses as basis functions the set of free-electron functions which are the solutions of Schrödinger's equation for an electron confined between two concentric, spherical potential energy barriers. Application of the theory to the SCF calculation of the energies of the delocalized electrons in benzene and tetrasulphur tetranitride shows that the model is capable of interpreting the properties of such systems. However, it does highlight a difficulty in the calculation of excited state energies with one-centre models which appears to be largely unrecognized.Extension of the method to a consideration of all the valence electrons, using P4 as an example, reveals problems the origin of which is an inadequate treatment of the core electrons. It is suggested that these problems may best be dealt with by use of a suitable pseudo potential.  相似文献   
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《Tetrahedron: Asymmetry》2005,16(5):1035-1046
The synthesis of new glycosidase inhibitors, namely, the glycosylamines of 5-thioglucose and 5-thiomannose and their corresponding amidinium salts are described. We report also the crystal structures of 5-thio-d-mannopyranosyl amine 1 and 5-thio-d-mannopyranosylamidinium bromide 2 bound in the enzyme active site of Golgi α-mannosidase II (GM II). Compounds 1 and 2 have been found to be inhibitors with IC50 values of 0.07 and 0.9 mM, respectively. We also report the docked structures of 5-thio-d-glucopyranosylamine 3 and 5-thio-d-glucopyranosylamidinium bromide 4 in the active site of glucoamylase G2, derived by molecular modeling. Compounds 3 and 4 were found to be inhibitors with Ki values of 0.015 and 0.098 mM, respectively. The results led to conclusions about the nature of the transition state and strategy for the inhibition of glycosyl hydrolases in general.  相似文献   
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