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Magnetic uniaxial alignment of the columnar superstructure of discotic metallomesogens over the centimetre length scale
No full textThe uniaxial alignments of the columnar superstructure of discotic metallomesogens, cobalt octa( n-dodecylthio) porphyrazine (CoS12), over the centimetre length scale have been achieved by spinning samples under a static magnetic field. The orientations of the columnar superstructures were investigated by small angle neutron scattering ( SANS) and cryogenic transmission electron microscopy (cryo-TEM). Upon cooling from the isotropic phase to the columnar mesophase in the presence of a static magnetic field (0.4 - 1.1 T), CoS12 formed oriented columnar superstructures with the columnar directors being isotropically distributed in the plane normal to the external magnetic field. When the samples were continuously spun during cooling in a static applied magnetic field of 1.0 T, CoS12 was observed to form uniaxially aligned columnar superstructures with the columnar domain directors being parallel to the rotation axis which was normal to the external field. The optimal rotation speed for the alignment was found to be as low as 5 - 10 rpm, where the full width at half maximum of the domain director distribution is minimized. The uniaxial alignments were achieved over a macroscopic length scale (ca. 1 cm). Cryo-TEM measurements revealed that the persistence length of the uniaxially aligned columns was at least 1 mu m.This work was supported by the program of the Basic Atomic
Energy Research Institute (BAERI) which is a part of the
Nuclear R&D Programs funded by the Ministry of Science &
Technology (MOST) of Korea and the HANARO Utilization
Program (M2-0363-00-0063). We thank the HANARO at
KAERI and NCNR at NIST for SANS beamtime supports.
The work utilized NIST facilities supported in part by the
National Science Foundation under DMR-9986442. We also
thank J.-K. Kim, S.-M. Kim and J.-Y. Lee at Korea Basic
Science Institute (KBSI) for technical assistance during
cryo-TEM measurements and J.-S. Lee for DSC and POM
measurements
Structure and magnetic alignment of metalloporphyrazine columnar aggregates in their mesophases and crystalline phases
No full textThe response of a series of metalloporphyrazine liquid crystals to external magnetic fields has been investigated. Small-angle neutron scattering (SANS) data of the octa(n-decylthio)-porphyrazine complexes of the diamagnetic late first-row transition elements (Ni, Zn) reveal a perpendicular orientation of the columnar directors with respect to applied magnetic fields as low as 0.50 T when the samples are cooled from their isotropic phases. The threshold aligning field for the analogous cobalt derivative is half that of the diamagnetic complexes, while the copper porphyrazine exhibits no preferred alignment at fields as high as 1.02 T. We account for these observations on the basis of the competing diamagnetic and paramagnetic moments of the complexes. Correlated solid state and mesophase C-13 NMR studies on the nickel and zinc complexes indicate time-averaged disk tilt angles of 27degrees with respect to the columnar directors in the liquid-crystalline phase
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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