1,720,956 research outputs found
Langmuir-Blodgett films doped with SMF
No full textUltrathin films have become an important advancement in modern society with many diverse applications, including solar cell parts, computer chips, and anti-reflective coatings on glasses. The Langmuir-Blodgett (LB) technique was employed to deposit ultrathin films on substrates. Intermolecular forces strongly influence the formation or these films, and our studies of the formation and properties of such films help us understand these forces. The method exploits the hydrophilic and hydrophobic properties of an amphiphilic molecule to develop film at the air-water interface. Pressure vs area isotherms were taken to characterize the gas-like, liquid-like, and solid-like phases and to determine the zero-pressure molecular area for optimal film deposition. A substrate is dipped into the water to deposit a single molecule layer film. Multiple layered films are deposited by passing the substrate through the air-water interlace multiple times. Small molecule fluorophores (SMF's) are small molecules that emit light from an excited state. They ere added as dopants to the LB film. Trapping the fluorophores into the LB film reduces the degrees of motion available to the molecule. This is likely to influence the fluorescence time, which ls measured by time-resolved fluorescence
Solvatochromism involving Rhodamine-6G
No full textThe solvatochromic shift of a molecular fluorophore is the change in the absorption and emission spectra and is caused by the dipole interactions that take place between it and the solvent. Rhodamine-6G (R6G) was used because it is a good example of a molecular fluorophore that exhibits this phenomena. In most organic solutions, Rhodamine-6G becomes aqueous and acts similar to a salt. forming an organic ionic molecule and an ionized Chlorine atom. This ionic molecule is affected by the polarity of the solution into which it is dissolved.
To better understand the solvatochromic shifting of Rhodamine-6G, the dipole interactions must be further researched. This can be done by measuring R6G spectra of different solutions and calculating the Stokes Shift. The Stokes Shift is the difference between the peak absorption wavelength and peak emission wavelength. These peaks allow for the calculation of the dipole moments in each solution. There are several methods to determine dipole moments and change in dipole moments. The most commonly used methods were developed by Lippert-Malaga,
Bakhs.h..ie. v, Catalan, Kamlet-Taft, Reichardt, and Bilot-Kawski
Solvatochromism Of NNDAP-O-CH3
No full textThe solvatochromic properties of a novel fluorophore, 4-[2-[2-(dimethylamino)-3-pyridyl]ethynyl]anisole (NNDAP-O-CH3), developed by Dr. Tanay Kesharwani of The University of West Florida was studied. The absorption and emission spectra of the fluorophore in various solvents were measured. The ground state and singlet excited state dipole moments were determined using the Bilot-Kawski, Lippert-Mataga, Bakhshiev, and Reichardt correlation methods. The magnitude to which a certain solvent property contributes to the observed solvatochromic shifts was investigated using both Kamlet-Taft and Catalan models. The experimental system and environment are being computationally modeled in Gaussian16. Predictions of the software will be compared to experimental evidence to propose structural and dynamic factors contributing to the phenomenon as well as to predict other properties of the molecule
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
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