1,720,973 research outputs found
Luminescent lanthanide complexes with phosphoramide and arylphosphonic diamide ligands
No full textThe sensitization of Eu(III) luminescence by the phosphoramide and arylphosphonic diamide ligands OP(NMe2)2Ind, OP(NMe2)2Cbz, OP(NMe2)2Ph, OP(NMe2)2(1-Naph) and OP(NMe2)2(2-Naph) (Ind = indol-1-yl; Ph = phenyl; Cbz = carbazol- 9-yl; 1-Naph = naphtalen-1-yl; 2-Naph = naphtalen-2-yl) was verified by coordination to the [Eu(NO3)3] metal fragment. The emission spectra of the corresponding complexes showed only the 5D0 → 7FJ transitions of the metal centre, with the exception of the carbazolyl derivative. Some of the ligands were also able to sensitize Tb(III) luminescence, in agreement with the triplet state energies estimated from the phosphorescence spectra of the analogous Gd(III) nitrates. On the basis of the photoluminescence results achieved using nitrate as ancillary ligand, heptacoordinate Eu(III) complexes having general formula [Eu(β-dike)3L] (β-dike = dibenzoylmethanate, tenoyltrifluoroacetonate; L = phosphoramide or arylphosphomic diamide ligand) were prepared and characterized. All the complexes exhibited bright red emission upon excitation with near-UV and violet-blue light, with intrinsic quantum yields ranging between 18 and 36%
Enhanced DNA damage and anti-proliferative activity of a novel ruthenium complex with a chlorambucil-decorated ligand
No full textTriphenylphosphine substitution reactions of [RuCl(PPh3)2(tpm)]Cl, 3 ) 2 (tpm)]Cl, 1 , featuring tris(pyrazolyl)methane (tpm) as ligand, with the chlorambucil-decorated pyridine ligand PyCA, CA , 3-aminopyridine ( Py NH2 ) and 4-pyridinemethanol ( Py OH ) afforded the corresponding pyridine complexes 2-4 in high yields. PyCA CA was preliminarily obtained via esterification of 4-pyridinemethanol with chlorambucil. The new compounds PyCA CA and 2-3 were characterized by IR and multinuclear NMR spectroscopy. Additionally, the structure of 3 was ascertained by single crystal X-ray diffraction. The in vitro anti-proliferative activity of 2-4 and PyCA CA was determined against a panel of cancer cell lines, outlining 2 as the most performing compound. Targeted studies were subsequently undertaken using 2 to elucidate mechanistic aspects, including the assessment of ruthenium cellular uptake, cell cycle arrest, production of reactive oxygen species (ROS), western blotting and DNA damage (comet test). Overall, data highlight that the anticancer activity provided by 2 primarily affects the mitochondria pathway with a potential additional contribution from DNA damage
Seeded growth of gold nanorods: the effect of sulfur-containing quenching agents
No full textHerein we present a study on the efficacy of\ud
selected sulfur-containing species as growth quenchers\ud
andmetal ion scavengers in the framework of gold nanorod\ud
(GNR) synthesis. The here utilized seeded growth method\ud
is the referenceGNRsynthesis approach.However,GNRs\ud
synthesized according to it are prone to morphological\ud
changesuponaging,promotedbythepresenceofunreacted\ud
metal ions in the stock suspension. This, in turn, leads to\ud
optical property changes. Sodium sulfide is an efficient\ud
GNR growth quencher and metal ion scavenger, because\ud
sulfide ion has a strong affinity towards noble metals used\ud
for the GNRs’ synthesis. Moving from these considerations,\ud
different sulfur-containing moleculeswere selected\ud
and their interaction with GNR surface was investigated:\ud
sulfate, sulfite, thiourea, and dodecyl sulfate were chosen\ud
for their difference in terms of net charge, size, and hydrophobicity.\ud
We initially assessed the best synthesis\ud
conditions in terms of reaction time, seed amount, silver\ud
concentration, and quencher amount. Consequently, the\ud
quencher/scavenger was varied. Thiourea, sulfite, and sulfate\ud
ions all showeda feeble, yet non-negligible, interaction\ud
with metals. Although sodium sulfide turned out to be the\ud
most efficient quencher/scavenger, also dodecyl sulfate\ud
showed evidences of adsorption on theGNRsurface, probablypromptedbyhydrophobic\ud
interactions.These findings\ud
are expected to contribute as a background for further\ud
advancements in the perfection of GNR synthetic approaches\ud
specifically in terms of post-synthesis treatments
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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