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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
Spectrophotometric determination of cloud point of Brij 35 nonionic surfactant
No full textThe cloud point of nonionic surfactant polyoxyethylene (23) lauryl ether (Brij-35) was determined in the presence of various inorganic electrolytes. The measurements of cloud point (CP) were carried out with UV-vis spectrophotometer instead of visual observation. CP of Brij-35 could not be measured directly because its CP is more than 100 degrees C. Therefore, CP values of Brij-35 were lowered by the addition of electrolytes. In this study, NaF, NaCl, NaBr, KNO3, K2CO3, K-3 PO4, Li2SO4, Na2SO4, K2SO4,(NH4)(2)SO4, CuSO4, ZnSO4, CoSO4 were used as electrolytes. Linear lines which were drawn with CP values were extrapolated to zero electrolyte concentration. The real CP value of Brij-35 which is merely listed as > 100 degrees C in the literature was found as 118.5 +/- 0.5 degrees C for all samples. Furthermore, the effects of the nature of the cation and the anion and the valencies of the cations on CP were reported and the rate of decrease in CP with concentration is discussed. (C) 2011 Elsevier B.V. All rights reserved.Trakya University [TUBAP-783]The authors wish to thank the financial support of the Trakya University Research Fund (TUBAP-783)
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
Spectrophotometric studies of anionic dye-cationic surfactant interactions in mixture of cationic and nonionic surfactants (vol 61, pg 961, 2005)
No full text[Abstract Not Available
Spectroscopic studies of interactions between CI Reactive Orange 16 with alkyltrimethylammonium bromide surfactants
No full textIn the present study, the influence of surfactants on spectral properties of an azo dye in aqueous solutions has been investigated by means of UV-vis spectroscopy in submicellar and micellar concentration range. The spectral signature of the polarity of the azo dye C.I. Reactive Orange 16 (RO16) exhibits sensitivity to the polarity of the dye's environment. This dependence of absorption on microenvironment was used to investigate the ion pair complex formed from electrostatic interaction of a series of alkyltrimethylammonium bromide surfactants (C(m) TAB, m = 12, 14, 16 and 18) with the anionic azo dye R016. It was observed that the aggregation of surfactant and dye takes place at surfactant concentration far below the critical micelle concentration of the individual surfactant. Aggregation is reflected by the appearance of a new absorption band in the spectrum of the dye. Spectral behavior of dye-surfactant solution with varying concentration of surfactant confirms that electrostatic interaction between dye and surfactant occurs up to a certain level. Beyond this concentration, with addition of surfactant, micelles occur and all dye molecules are accommodated into a normal micelle as monomeric molecules. The short-range hydro phobic interactions are very important factors as the long-range electrostatic forces on the dye-surfactant aggregation in aqueous solution. The effect of the length of the alkyl chain of the surfactant on the complex formation between cationic surfactant and reactive dye was that the hydrophobicity of alkyl chains plays an important role in complex formation. Going from less hydrophobic solution to the more hydrophobic micellar environment, the occurrence of complex is found at lower surfactant concentration. Because the CIVIC values of dye-surfactant solution are decreased with increasing alkyl chain length. (C) 2009 Elsevier B.V. All rights reserved
CI Reactive Orange 16-dodecylpyridinium chloride interactions in electrolytic solutions
No full textThe effect of electrolytes on the interaction between an anionic dye and a cationic surfactant was investigated spectrophotometrically in submicellar concentration range at certain temperature. The spectral change of the azo dye C.I. Reactive Orange 16 (RO16) exhibits a high sensitivity to the polarity of dye's environment. Dodecylpyridiniurn chloride (DPC) affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results formation of complex and therefore a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte cations cause an increase of the absorbance of DPC-RO16 ion-pair complex in the following order: Ca2+ > Na+ > NH4+ > K+ > Mg2+, also for electrolyte anions Br- > Cl- > SO42-. Furthermore, this order can be changeable with increasing electrolyte concentration. The increase on absorbance value with increasing electrolyte concentration is explained as charge screening. The increase or decrease on absorption spectra of RO16-DPC solution depends on concentration range of the electrolyte added. As an increase on absorbance value with increasing electrolyte concentration is explained as charge screening, a decrease in this value for higher concentration of electrolyte is attributed as the charge of micelle shape. (c) 2005 Elsevier B.V. All rights reserved
Thermodynamic and Interfacial Properties of Cationic Gemini Surfactant in the Presence of Alcohols
No full textThe micellar properties of the cationic Gemini surfactant ethanediyl-1,2-bis(dimethyldodecyl ammonium bromide), C12H25 center dot(CH3)(2)N+-(CH2)(2)-N+(CH3)(2)C(12)H(25 center dot)2Br(-) (12-2-12), with short chain alcohols have been studied by conductivity and surface tension measurements within the temperature range 293.15 K-313.15 K and alcohol percentage. The critical micelle concentration (CMC) of 12-2-12 solution, degree of ionization (alpha) and standard Gibbs free energy of micellization (Delta G(m)degrees), standard enthalpy of micellization (Delta H-m degrees) were calculated from conductivity and surface tension data. The experimental data show that the CMC values of cationic Gemini surfactants increased with addition of methanol, ethanol and n-propanol. The thermodynamic parameters (Delta G(m)degrees), (Delta H-m degrees) and (Delta S-m degrees) of micellization of 12-2-12 in alcohol were also calculated from the temperature dependence of the CMC values. CMC, (alpha), (Delta H-m degrees) and (Delta S-m degrees) increased linearly with increasing temperature. In the mixture of dimeric cationic surfactant (12-2-12) and alcohol solutions, the CMC values showed a slight increase with increasing alcohol concentration. CMC, maximum surface excess concentration at the solution/air interface, Gamma(max), minimum area per surfactant molecule, A(min), and the surface pressure at CMC, IICMC, values calculated from the surface tension measurements and thermodynamic parameters have been evaluated at same temperatures
The investigation of thermodynamic parameters of kinetic reaction between o-phenylenediamine and gold (III)
No full textA visible spectrophotometric method has been developed for the reaction kinetics of o-phenylenediamine in the presence of gold (III). The method is based on the measurement of the absorbance of the reaction o-phenylenediamine and gold (III). Optimum conditions for the reaction were established as pH 6 at lambda=466 nm. When the reaction kinetic of o-phenylenediamine by gold (III) was investigated, it was observed that the following rate formula was found as In (A/A(0)) = -kt, according to absorbance measurements. The activation energy E-a and Arrhenius constant A were calculated from the Arrhenius equation as 1.009 kJ center dot mol(-1) and 3.46 center dot 10(-2) s(-1), respectively. Other activation thermodynamic parameters, entropy, Delta S (J center dot mol(-1) center dot K-1), enthalpy, Delta H (kJ center dot mol(-1)), Gibbs free energy, Delta G (kJ center dot mol(-1)) and equilibrium constant, K-e were calculated at T = (283.2, 303.2, 323.2, and 343.2) K. The study was exothermic due to the decrease of entropy and was a non-spontaneous process during activation. (c) 2007 Published by Elsevier Ltd
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