1,720,973 research outputs found
Effects of size and surface functionalization of zinc oxide (ZnO) particles on interactions with bovine serum albumin (BSA)
Full text linkIn this work, the behaviour of bovine serum albumin (BSA) interacting with zinc oxide (ZnO) particles functionalized with 3-mercaptopropionic acid (3-MPA) and without any coating has been investigated. Two kinds of ZnO particles of different size and morphology were obtained: microwires (MW) and nanoparticles (NP). The effect of surface modification on the fluorescence properties of ZnO was studied. Typical ZnO green emission due to defects was not observed in the functionalized NP spectrum. Structure alterations of the protein interacting with ZnO particles were evaluated by fluorescence spectroscopy and circular dichroism (CD). Though BSA structure was not significantly perturbed in any case, some conformational changes were observed for BSA interacting with not functionalized MW.Fil: Simonelli, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Sólido; ArgentinaFil: Arancibia, Eleuterio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Ingeniería en Procesos y Gestión Industrial; Argentin
Solubility parameter determination of cationic surfactants by inverse GC
No full textThe solubility parameters of cationic surfactants were obtained using the inverse gas chromatographic technique. The surfactants didodecyl dimethyl ammonium bromide, dioctadecyl dimethyl ammonium bromide and dodecyl pyridinium chloride were used as stationary phase and retention data of different probe solutes were measured at different temperatures. The results were analysed by the combination of Flory-Huggins and Hildebrand theories, and the solubility parameters of the surfactants were obtained in a range of temperatures between 80–120°C.Fil: Bardavid, Sofia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; ArgentinaFil: Schulz, Pablo Carlos. Universidad Nacional del Sur; ArgentinaFil: Arancibia, Eleuterio Luis. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Cátedra de Fisicoquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin
Interaction Parameters of Surfactant Mixtures by Inverse Gas Chromatography
Full text linkThe Inverse Gas Chromatography (IGC) has been used in the measurement of surfactant-surfactant interaction parameters at different percentages and temperatures in cationic surfactant mixtures. Specific retention volume values obtained with different probe solutes in surfactant mixtures could be qualitative tests of the miscibility as those obtained in polymeric materials. The results for systems constitute by cationic surfactant mixtures have been compared. Two phenomenological methodology, Farooque-Deshpande and Huang, for calculate of the interaction parameter have been employed and the results compared with those obtained in polymer mixtures. The results obtained in surfactant mixtures are similar to obtained in polymeric material when both methodologies are compared. We found that the difference between interception calculated values are greater when the slope obtained by Huang methodology to withdraw of the unity.Fil: Arancibia, Eleuterio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Schulz, Pablo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Bardavid, Susana M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin
On a Rational Performance Evaluation for the Development of Inorganic Membrane Technology in Gas Separation and Membrane Reactors
Full text linkInorganic membranes can be made of different materials. However, there have been only few reports on membrane evaluation to convert lab-scale membranes into a prototype for industrial applications. In order to fill this significant gap, new approaches for the development and optimization of membrane products are required. This work focuses on the different aspects related to the performance assessment of membranes used for gas separation and membrane reactors. This approach can be visualized as an algorithm consisting of three specific loops involving different aspects of the overall membrane evaluation. Several factors that have an impact on membrane performance are discussed. These factors are divided into two categories: directly affecting the measurements (setup leakage, concentration polarization, repeatability, pressure gradient) and related to the intrinsic characteristics of permeation flux across the membrane (single and mixture permeation, transport modeling, defect flux, microstructure flexibility). This evaluation protocol includes a literature review with the most recent breakthroughs in this research area.Fil: Avila, Adolfo María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; ArgentinaFil: Arancibia, Eleuterio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin
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
Excess molar volumes and excess viscosities of the 2,2,4-trimethylpentane (1) + 3-methyl-1-butanol (2) and propan-2-ol (3) ternary system at 298.15 K
Full text linkThis paper reports experimental densities and viscosities of the ternary system 2-2-4-trimethylpentane + 3-methyl-1-butanol + propan-2-ol and the binary systems 2-2-4-trimethylpentane (isooctane) + 3-methyl-1-butanol (isoamyl alcohol), 2-2-4-trimethylpentane (isooctane) + propan-2-ol (isopropyl alcohol), and 3-methyl-1-butanol + propan-2-ol, over the entire range of composition at 298.15 K. Excess molar volume, excess viscosity and the excess energy of activation for viscous flow were evaluated from the experimental data obtained. These derived properties for binary and ternary systems were fitted to Redlich-Kister's and Cibulka's equations, respectively. Flory's statistical theory has been applied to predict excess molar volumes for ternary system. For viscosities we applied Grunberg and Nissan, Katti and Chaudhri, Bloomfield and Dewan and Wu equations and finally the GC-UNIMOD model. © 2005 Elsevier B.V. All rights reserved.Fil: Salas, J.A.. Universidad Nacional de Tucumán; ArgentinaFil: Pedrosa, G.C.. Universidad Nacional de Tucumán; ArgentinaFil: Acevedo, I.L.. Universidad Nacional de Tucumán; ArgentinaFil: Arancibia, Eleuterio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentina. Universidad Nacional de Tucumán; Argentin
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
IGC studies of binary cationic surfactant mixtures
Full text linkInverse gas chromatography (IGC) has been used to measure the interaction parameter between two twin-tailed cationic surfactants. Didodecyldimethylammonium (DDAB) and dioctadecyldimethylammonium (DODAB) bromides and their mixtures were used as stationary phases. IGC and DSC techniques have been used for the determination of the temperature zone of working. The activity coefficients at infinite dilution (on a mole fraction basis) were calculated for eleven probe solutes on each pure surfactant column. Values of interaction parameter between surfactants obtained at four weight fractions of the mixtures and at five temperatures are positive and suggested that the interactions is more unfavourable with the increment of DODAB concentration in the mixture. The results are interpreted on the basis of partial miscibility between DDAB and DODAB. © 2007 Elsevier Inc. All rights reserved.Fil: Bardavid, S.M.. Universidad Nacional de Tucumán; ArgentinaFil: Schulz, Pablo Carlos. Universidad Nacional del Sur; ArgentinaFil: Arancibia, Eleuterio Luis. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Química del Noroeste. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química del Noroeste; Argentin
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
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