Conductimetric and viscometric study of the macromolecular complex between poly(acrylic acid) and poly(vinyl pyrrolidone)

cited By 7International audienceThe intermacromolecular complex between poly(acrylic acid) (PAA) and poly(vinyl pyrrolidone) (PVP) was studied by means of conductimetry and viscometry. Conductimetry is shown to be a useful tool in the investigation of this kind of complex because the polyacid dissociation is suppressed in the presence of PVP. Near to stoichiometry there is a minimum in the viscosity-composition curves due to the formation of aggregates. When varying the degree of neutralization of the polyacid to values lower than 0.1 a different pattern of behavior is seen with respect to the composition of the complex, depending on which polymer has a higher degree of polymerization (PAA or PVP). On the basis of quantitative analysis of the conductimetric titration data, a relationship is proposed to evaluate the degree of complexation between both macromolecules. This parameter diminishes with increasing charge density in the PAA chain, falling to zero for values of degree of neutralization close to 0.1. © 1998 Elsevier Science Ltd. All rights reserved

Interplay of Interfacial and Rheological Properties on Drainage Reduction in CO2 Foam Stabilised by Surfactant/Nanoparticle Mixtures in Brine

Although nanoparticles (NPs) are known to increase foam stability, foam stabilisation is not observed in all surfactant/NP combinations. The present study evaluates the stability of CO2 foams containing surfactant/NP mixtures with attractive or repulsive electrostatic interactions at the low pH imposed by CO2 in the presence of a high-salinity brine. Three ionic surfactants and two oxide NPs (SiO2 and Al2O3) were used in combinations of similar or opposite charges. Surface tension, viscosity, ζ-potential and hydrodynamic size experiments allowed the analysis of CO2 foam stability based on the impact of surfactant–NP interactions on bulk and interfacial properties. All oppositely charged systems improved the foam half-life; however, a higher NP concentration was required to observe a significant effect when more efficient surfactants were present. Both bulk viscosity and rigidity of the interfacial films drastically increased in these systems, reducing foam drainage. The mixture of SiO2 with a zwitterionic surfactant showed the greatest increase in CO2 foam stability owing to the synergy of these effects, mediated by attractive interactions. This study showed that the use of NPs should be tailored to the surfactant of choice to achieve an interplay of interfacial and rheological properties able to reduce foam drainage in applications involving CO2 foam in brine

Structure and dynamics of micelle-based fluorescent sensor for transition metals.

A structural model of the fluorescent supramolecular sensor Triton X-100:pyrene:dodecyl-dioxo-2,3,2 is proposed, based on a micellar approach. Under the experimental conditions, phase behavior of the micellar solution restricts ligand:surfactant ratio to 1:10. Thermodynamic and kinetic data indicate that the quenching mechanism involved in the ON-OFF response is intramicellar, and selective compartmentalization of fluorophore and quencher inside micelles can affect effective collisions. An oblate ellipsoid is proposed as the most suitable structure for this micellar-based sensor. Main structural properties of surfactant aggregates and the complex itself are not affected by this assembling, suggesting that the micelle acts as a dynamic substrat

Identificación de riesgos ambientales en el laboratorio de radioquímica de la facultad de ciencias y tecnologías nucleares

Organizations of all kinds are more and more interested in reaching and demonstrating a sustainable environmental performance by means of the control of the risks of their activities, products and services on the environment. The main purpose of the present investigation is to identify the environmental risks in the Radiochemistry Laboratory of the Faculty of Science and Nuclear Technologies (FCTN), allowing the organization to evaluate, to control, to minimize and/or to eliminate the environmental associated risks at the laboratory. In order to achieve such purpose, it was carried out an environmental diagnosis of the current situation of the laboratory and afterwards, it was made the evaluation of the environmental risks detected by means of the Managerial Procedure of Integrated Risks. There were also set out measures to diminish significant environmental risksOrganizaciones de todo tipo están cada vez más interesadas en alcanzar y demostrar un sostenido desempeño ambiental mediante el control de los riesgos de sus actividades, productos y servicios sobre el ambiente. La presente investigación tiene como objetivo identificar los riesgos ambientales en el Laboratorio de Radioquímica de la Facultad de Ciencias y Tecnologías Nucleares (FCTN), permitiéndole a la organización evaluar, controlar, minimizar y/o eliminar dichos riesgos asociados al ambiente en el laboratorio. Para ello se realizó un diagnóstico ambiental de la situación actual del laboratorio y seguidamente se realizó la evaluación de los riesgos ambientales detectados mediante el Procedimiento de Gestión de Riesgos Integrados. Finalmente se proponen medidas para minimizar los riesgos ambientales significativos

Electrochemical Characterization a New Epoxy Graphite Composite Electrode as Transducer for Biosensor

A new graphite epoxy composite composition was developed by the manufacturer of transducer for DNA biosensor, which were characterized by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy field emission (FESEM). The dependence of peak potential, the anode current relationship, and cathodic current with scan rate was evaluated by voltammetry for the redox system Fe(CN)63-/4- Well-defined voltammograms were obtained using the graphite-epoxy composite 3.3/2.5/1 m/m/v graphite/araldite/hardener (GEC II). The electrochemical characterization showed a quasi-reversible electrochemical behavior under the control of the linear diffusion system for Fe(CN)63-/4-. The GEC III was also successfully used in the detection of the signal oxidation guanine monophosphate (GMF) and adenine (AMF) by square wave voltammetry. These results demonstrate the potential of GEC II in the electrochemical detection of DNA

Efecto in vitro del Ateromixol sobre los linfocitos y neutrófilos humanos Effect in vitro of Ateromixol on the human lymphocytes and neutrophiles

El Ateromixol es un producto desarrollado por el Centro Nacional de Investigaciones Científicas y comercializado por los Laboratorios Delmer de Ciudad de La Habana. Tiene como principio activo al policosanol, constituido por una mezcla de alcoholes primarios alifáticos superiores obtenido de la cera de Saccharum officinarum L. Se estudió el efecto in vitro del Ateromixol, conocido como PPG, sobre los linfocitos y neutrófilos de 15 donantes voluntarios de sangre y de 15 enfermos con diagnóstico de inmunodeficiencia celular mediante la prueba de transformación linfoblástica, con el empleo de timidina tritiada, la técnica de roseta activa y la prueba de función fagocítica. No se observaron diferencias significativas en el análisis estadístico de las condiciones experimentales sin Ateromixol y con diluciones desde 500 m g/mL hasta 3,90 m g/mLAteromixol is a product developed by the National Center of Scientific Research and commercialized by Delmer Laboratories of Havana City . Its active principle is polycosanol, which is composed of a mixture of primary aliphatic higher alcohols obtained from the wax of Saccharum officinarum L. The effect in vitro of Ateromixol, known as PPG, on the lymphocytes and neutrophiles of 15 voluntary blood donors with diagnosis of cellular immunodeficiency was studied by the lymphoblastic transformation test, with the use of tritiated timidine, the active rosette technique and the phagocytic function test. No significant differences were observed in the statistical analysis of the experimental conditions without Ateromixol and with dilutions from 500 m g/mL to 3.90 m g/m

Dataset for "Core-shell spheroidal hydrogels produced via charge-driven interfacial complexation"

The dataset for "Core-Shell spheroidal Hydrogels produced via charge-driven interfacial complexation" contains data, in the form of excel and txt files, for the figures shown in the main manuscript and the electronic supplementary information (ESI). The study focuses on the structure of the spheroidal hydrogels (SH) and their resilience in aqueous media. Furthermore, SH are used as microreactors for biocatalysis, providing a proof-of-concept for this material. The dataset contains data regarding the structural information of the spheroidal hydrogels (SH) (e.g. shell thickness, small angle X-rays scattering, Z-potential and oscillatory rheology) their stability in solvents with different osmotic pressure and ionic strength (e.g. swelling kinetic, swelling ratio) and the enzymatic activity to support a proof-of-concept of the SH. Specification of the materials and methods employed throughout the data collection are available in the main manuscript. Each excel sheet is specific for a set of data acquired utilising the same protocol.Methodology, experimental conditions and data treatment is described in the main manuscript.In the Excel file named "Data_Core_Shell_Hydrogels“, the data are presented in separate sheets, each of which is labelled as for the figure presented in the manuscript. The spreadsheet named: Fig. 2b shows the data regarding the thickness of the spheroidal hydrogel (SH) shell. Fig. 2c contains data regarding the Leakage and retention of surface active molecules Fig. 3 contains the data of the swelling dynamic of the SH in different conditions (Di_water, 1000 mM NaCl and 0.1 wt% PAA) Fig. 4a contains data for the Swelling Ratio (SR) as function of the osmotic pressure. Fig. 4b-Top contains data for the Z-potential measurements of a CCNF dispersion as function of the NaCl concentration. Fig. 4b-Bottom contains data for the oscillatory rheology measurements of a 2 wt% CCNF dispersion as function of the NaCl concentration. Fig. 6 contains the data of the enzymatic activity measurements. The txt files contains small angle X-rays scattering (SAXS) data presented in Fig. 5a. Each txt file is named as for sample name used in Fig. 5a

Identification of organic compounds in Cajío Peloid (Cuba)

"Thennal muds ("peloids") are a typical example of natural sediments used in the treatment of different pathologies. Nowadays, because of their use in therapeutics, relax and cosmetic issues, a proper management of peloids is of increasing importance. Peloid characterization and monitoring for quality control purposes are therefore the main aspects of peloid management. Organic chemical quality is directly related with the biological active compounds and the therapeutic properties of peloidsto he used in human health and with the determination suitable contamination. This study was performed to characterize the organic fraction of Cajio peloid (Cuba) in order to identify the organic components with possible biological effects and establish its natural or anthropogenic origin. For this purpose, a procedure with chromatographic analysis and mass spectrometry detection has been performed. More than 40 compounds were identified, in Cajio peloid, mainly of natural origin. Among them were found alkanes, steroids, fatty acids, alcohols and other heteroatoms compounds, some of them with reported biological activity in their isolated form as antioxidant, analgesic, anti-inflammatory, and others. The results provide evidence for medical interpretation of the therapeutic action of Cajio peloid in the treatment of inflammatory and dermatological diseases and contribute to the understanding of pelotherapy, giving some scientific basis for its future development.