1,720,972 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
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
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
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
Separation and identification of sucrose monoesters for liquid chromatography
No full textLos productos derivados de sacarosa, como son los ésteres de sacarosa con ácidis grasos,han recibido creciente atención por su papel comol surfactantes conocirjos por ser no tóxicos y biodegradables. Estaparticularidad ha potenciado su empleo corno emulsificante en la industria alimentariariay farmacéuticp. farmacéutica. Por estas razones, la separaciónde ésteres de sacarosa es un desaflo permanente en las determinaciones anallticas. En este trabaio se presenta la separación de de sacarosa de sus mezclas con di y poliésieres en cromatografia en escala prepara(iva, empleando silice como adsorbente y una mezcla de acetato de etilo-metanol como solvente. La identificación de las fracciones correspondientes a los monoésteres fue realizada usando cromatografíen en placas placas delgadas delgadas con con la misma mezcla de solvente. Los resultados obtenidos muestran la potencialidad de Ia metodologia para ser.aplicada en la obtención de monoésteres puros imuestranSucrose derivatives, like esters of sucrose and fatty acids have received increasing attention for the irrmportant role as sudacfactants , wetl-known as non-ioxic and with an excellent biodegradability. These propeties have made their use as emulslfiers in food and pharmaceutical industries more important. That is why t\e separation of sucrose esters have a constant relevance in analytical determinations. In this paper, the separation oi sucrose monoesters from their mixtures with di and polyesters in a column liquid chromatography is presented, in the preparatory scale using silica as adsorbent and a mixture of methyl acetate and methanol as solvent.. The identification of the fractions corresponding to esters was done by thin layer chromatography , with the same mixture of so/vents. The results s/tow the posslbilities of this methodology in order to obtain pure monoesters.Fil: Juarez, Gabriela. No especifica;Fil: de Schaefer, Cecilia. No especifica;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; 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
Viscosities of mixtures of 2-alkanols with tetraethyleneglycol dimethyl ether at different temperatures
Full text linkKinematic viscosities and densities were measured over the entire range of composition and at atmospheric pressure for 2-propanol-tetraethyleneglycol dimethyl ether, 2-butanol-tetraethylene glycol dimethyl ether, and 2-pentanol-tetraethylene glycol dimethyl ether from 288.15 to 318.15 K employing pure species and solutions covering the whole range expressed by the condition 0 ≤ x ≤ 1. Starting from the experimental data, the dynamic viscosity, deviation of dynamic viscosity, and the excess Gibbs energies of activation for viscous flow have been calculated. The results were fitted by the Redlich-Kister equation. Free-volume type correlation with one parameter is compared with an extension of the generalized corresponding states principle for these systems.Fil: Aznarez, S.. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Química; ArgentinaFil: Ferreyra de Ruiz Holgado, Mercedes Marta Elsa. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Ingeniería en Procesos y Gestión Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arancibia, Eleuterio Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Ingeniería en Procesos y Gestión Industrial; Argentin
Thermodynamic functions of activation for viscous flow for solutions of polyethylene glycol methyl derivatives with n-alcohols at different temperatures
Full text linkViscosity of dilute solutions of mono and dimethyl ether of polyethylene glycol in n-propanol and n-butanol has been determined at different temperatures, between 278.15 and 318.15 K. Thermodynamic functions of activation for viscous flow (Gibbs free energy, enthalpy and entropy) and also partial molar properties were obtained and analyzed using Eyring's theory of rate process applied to viscous flow. From the relation between thermodynamic functions of activation with the mole fraction of the solute, empirical coefficients have been calculated. Contributions to Jones-Dole coefficient, B, were analyzed.Fil: Ferreyra de Ruiz Holgado, Mercedes Marta Elsa. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; ArgentinaFil: De Schaefer, C. R.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología; 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
Solubility parameters, hydrophile-lipophile balance, and solubility in sucrose derivative surfactants obtained by GLC
No full textSpecific retention volumes of different solvents were measured on coIumns containing two sucrose derivatives esters as stationary phase.Henry's constants were calculated and the solubility in the surfacnnts was obtaíned. The solubilíty parameters of the surfactants were obtained at different temperatures. The relation between solubility parameter and hydrophilíc - lipophilic balance was discussed and the results obtained in both surfactants are presented.Se midieron los volúmenes de retención espeeíficos de distintos solventes en columnas que contenídn derivados de esteres de sacürosa comofases estacionarias. Se calcularon las constantes de Henry y se ha obtenído la solubilidad de los sdventes en dos esferes de sacarosa. Se calcularon los parámetros de solubilidad de las sudactantes a díferentes temperaturas. Finalmente, se ha discutido la relacíón entre parámetro de solubilidad con el balanee hídrofiIico - Iipofílica y se analizaron los resultados obtentdos en ambos sttrfactantes.Fil: Schaefer, C. R.. Universidad Nacional de Tucumán; ArgentinaFil: de Ruiz Holgado, M. E. F.. 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; Argentin
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