1,721,314 research outputs found
Infrared spectroscopy of endohedral HD and D2 in C60
No full textWe report on the dynamics of two hydrogen isotopomers, D2 and HD, trapped in the molecular cages of a fullerene C60 molecule. We measured the infrared spectra and analyzed them using a spherical potential for a vibrating rotor. The potential, vibration-rotation Hamiltonian, and dipole moment parameters are compared with previously studied H2@C 60 parameters [M. Ge, U. Nagel, D. Hvonen, T. Rm, S. Mamone, M. H. Levitt, M. Carravetta, Y. Murata, K. Komatsu, J. Y.-C. Chen, and N. J. Turro, J. Chem. Phys. 134, 054507 (2011)10.1063/1.3535598]. The isotropic part of the potential is similar for all three isotopomers. In HD@C60, we observe mixing of the rotational states and an interference effect of the dipole moment terms due to the displacement of the HD rotation center from the fullerene cage center. © 2011 American Institute of Physics
Steady-state in magnetic resonance pulse experiments
No full textRelaxation during multiple-pulse magnetic resonance experiments is treated by an average Liouvillian technique. The finite lattice temperature is taken into account by means of phenomenological correction terms. Both the transient and long-term response of the spin system are readily treated. We predict and verify a novel steady state of correlated spin polarizations in a spin-pair system under a periodic sequence of strong pi pulses
An optimised scalable synthesis of H2O@C60and a new synthesis of H2@C60
No full textNew high-yielding synthetic routes to the small-molecule endofullerenes H2O@C60, D2O@C60 and H2@C60 are described. The use of high temperatures and pressures for the endohedral molecule incorporation are avoided. A new partial closure step using PPh3, and final suturing using a novel Diels–Alder/retro-Diels–Alder sequence are amongst the advances reported
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Orientational Sampling Schemes Based on Four Dimensional Polytopes
No full textThe vertices of regular four-dimensional polytopes are used to generate sets of uniformly distributed three-dimensional rotations, which are provided as tables of Euler angles. The spherical moments of these orientational sampling schemes are treated using group theory. The orientational sampling sets may be used in the numerical computation of solid-state nuclear magnetic resonance spectra, and in spherical tensor analysis procedures
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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