Symmetrical basis for Faddeev equations

It is shown that the Faddeev equations can be treated in the frame of a three-body basis that takes into account the proper symmetries of the three-nucleon states.Facultad de Ciencias Exacta

A vanadium/aspirin complex controlled release using a poly(ß-propiolactone) film : Effects on osteosarcoma cells

A delivery system for vanadium was developed using poly(ß-propiolactone)(PßPL) films. The release kinetics of a complex of vanadium (IV) with aspirin (VOAspi) was evaluated with lms prepared from polymers of different molecular weights, as well as with variable drug load. A sustained release of vanadium over 7 days was achieved. The drug release kinetics depends on contributions from two factors: (a) diffusion of the drug; and (b) erosion of the PßPL lm. The experimental data at an early stage of release were tted with a diffusion model, which allowed determination of the diffusion coef cient of the drug. VOAspi does not show strong interaction with the polymer, as demonstrated by the low apparent partition coef cient (approximately 10-2). UMR106 osteosarcoma cells were used as a model to evaluate the anticarcinogenic effects of the VOAspi released from the PßPL lm. VOAspi–PßPL lm inhibited cell proliferation in a dose-response manner and induced formation of approximately half of the thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, compared to that with free VOAspi in solution. The unloaded PßPL lm did not generate cytotoxicity, as evaluated by cell growth and TBARS. Thus, the polymer-embedded VOAspi retained the antiproliferative effects showing lower cytotoxicity than the free drug. Results with VOAspi–PßPL lms suggest that this delivery system may have promising biomedical and therapeutic applications.Facultad de Ciencias Exacta

A vanadium/aspirin complex controlled release using a poly(ß-propiolactone) film : Effects on osteosarcoma cells

A delivery system for vanadium was developed using poly(ß-propiolactone)(PßPL) films. The release kinetics of a complex of vanadium (IV) with aspirin (VOAspi) was evaluated with lms prepared from polymers of different molecular weights, as well as with variable drug load. A sustained release of vanadium over 7 days was achieved. The drug release kinetics depends on contributions from two factors: (a) diffusion of the drug; and (b) erosion of the PßPL lm. The experimental data at an early stage of release were tted with a diffusion model, which allowed determination of the diffusion coef cient of the drug. VOAspi does not show strong interaction with the polymer, as demonstrated by the low apparent partition coef cient (approximately 10-2). UMR106 osteosarcoma cells were used as a model to evaluate the anticarcinogenic effects of the VOAspi released from the PßPL lm. VOAspi–PßPL lm inhibited cell proliferation in a dose-response manner and induced formation of approximately half of the thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, compared to that with free VOAspi in solution. The unloaded PßPL lm did not generate cytotoxicity, as evaluated by cell growth and TBARS. Thus, the polymer-embedded VOAspi retained the antiproliferative effects showing lower cytotoxicity than the free drug. Results with VOAspi–PßPL lms suggest that this delivery system may have promising biomedical and therapeutic applications.Facultad de Ciencias Exacta

Análisis del efecto térmico en la reología de asfaltos modificados

Con la necesidad de lograr mejores prestaciones en las mezclas asfálticas, como consecuencia de las mayores exigencias que nuestros caminos han experimentado, se han diseñado asfaltos modificados por la incorporación de polímeros, los cuales evidencian una mejora en sus propiedades. La constitución de un asfalto, actualmente basada en el modelo microestructural, es descripta como una distribución continua de moléculas de diversos tamaños y funcionalidades que difieren en su polaridad. Este modelo permite explicar el comportamiento reológico de los asfaltos como un fluido viscoelástico. Dicho comportamiento depende fuertemente de la temperatura. Se observa que a muy altas temperaturas el sistema se comporta como un fluido Newtoniano, y la relación viscosidad-temperatura puede expresarse mediante una ecuación tipo Arrhenius, con una energía de activación característica del sistema. A temperaturas intermedias – por encima de la temperatura de referencia 60 ºC - el comportamiento del sistema es mejor descripto por la expresión de Williams-Landel-Ferry (WLF). A temperaturas inferiores a 60 ºC se estima que el efecto de la temperatura sobre la viscosidad sigue nuevamente una ley de Arrhenius, con una energía de activación a determinar. La evaluación de la misma, a partir de medidas viscosimétricas realizadas por encima de la temperatura de referencia, dará información relevante respecto al comportamiento reológico del sistema a bajas temperaturas.Facultad de Ciencias ExactasFacultad de Ingenierí

A vanadium/aspirin complex controlled release using a poly(ß-propiolactone) film : Effects on osteosarcoma cells

A delivery system for vanadium was developed using poly(ß-propiolactone)(PßPL) films. The release kinetics of a complex of vanadium (IV) with aspirin (VOAspi) was evaluated with lms prepared from polymers of different molecular weights, as well as with variable drug load. A sustained release of vanadium over 7 days was achieved. The drug release kinetics depends on contributions from two factors: (a) diffusion of the drug; and (b) erosion of the PßPL lm. The experimental data at an early stage of release were tted with a diffusion model, which allowed determination of the diffusion coef cient of the drug. VOAspi does not show strong interaction with the polymer, as demonstrated by the low apparent partition coef cient (approximately 10-2). UMR106 osteosarcoma cells were used as a model to evaluate the anticarcinogenic effects of the VOAspi released from the PßPL lm. VOAspi–PßPL lm inhibited cell proliferation in a dose-response manner and induced formation of approximately half of the thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, compared to that with free VOAspi in solution. The unloaded PßPL lm did not generate cytotoxicity, as evaluated by cell growth and TBARS. Thus, the polymer-embedded VOAspi retained the antiproliferative effects showing lower cytotoxicity than the free drug. Results with VOAspi–PßPL lms suggest that this delivery system may have promising biomedical and therapeutic applications.Facultad de Ciencias Exacta

Stability and relaxation mechanisms of citric acid coated magnetite nanoparticles for magnetic hyperthermia

Magnetite (Fe3O4) nanoparticles are proper materials for Magnetic Fluid Hyperthermia applications whenever these conjugate stability at physiological (neutral pH) medium and high specific dissipation power. Here, magnetite nanoparticles 9–12 nm in size, electrostatically stabilized by citric acid coating, with hydrodynamic sizes in the range 17–30 nm, and well dispersed in aqueous solution were prepared using a chemical route. The influence of media acidity during the adsorption of citric acid (CA) on the suspension’s long-term stability was systematically investigated. The highest content of nanoparticles in a stable suspension at neutral pH is obtained for coating performed at pH = 4.58, corresponding to the larger amount of CA molecules adsorbed by one carboxylate link. Specific absorption rates (SARs) of various magnetite colloids, determined calorimetrically at a radio frequency field of 265 kHz and field amplitude of 40.1 kA/m, are analyzed in terms of structural and magnetic colloid properties. Larger dipolar interactions lead to larger Néel relaxation times, in some cases larger than Brown relaxation times, which in the present case enhanced magnetic radio frequency heating. The improvement of suspension stability results in a decrease of SAR values, and this decrease is even large in comparison with uncoated magnetite nanoparticles. This fact is related to interactions between particles.Instituto de Física La Plat

Nuclear-matter calculation with a rank-one separable potential

It has been recently proposed a family of rank-one separable potentials (1) which fits the nucleon-nucleon scattering data up to 460 MeV (lab). These potentials were tested in different calculations of two- and three-nucleon parameters. In particular, we mention the fact they reproduce fairly well the off-shell behaviour of the two-nucleon system. As a consequence of these results, it appears interesting to go further with the study of this new set of potentials. It is for this reason that we have investigated their behaviour in connection with nuclear matter.Departamento de Físic

Thermal characterization of novel p-nitrobenzylacrylate–diisopropyl fumarate copolymer synthesized under microwave energy

Copolymers of p-nitrobenzyl acrylate and diisopropyl fumarate with different feed ratios were synthesized under microwave and thermal heating conditions, and then characterized by IR, ¹H-, and ¹³C-NMR spectroscopy. Average molecular weights were analyzed by size exclusion chromatography (SEC). Monomer reactivity ratios were obtained from an extended Kelen–Tüdös method. Differential scanning calorimetry and thermogravimetry were used to evaluate the thermal behavior of all copolymers synthesized under microwave energy. Based on the products analyzed by SEC and gas chromatography–mass spectrometry, a possible mechanism of degradation is postulated.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física La Plat

Thermal characterization of novel p-nitrobenzylacrylate-diisopropyl fumarate copolymer synthesized under microwave energy

Copolymers of p-nitrobenzyl acrylate and diisopropyl fumarate with different feed ratios were synthesized under microwave and thermal heating conditions, and then characterized by IR, 1H-, and 13C-NMR spectroscopy. Average molecular weights were analyzed by size exclusion chromatography (SEC). Monomer reactivity ratios were obtained from an extended Kelen-Tüdös method. Differential scanning calorimetry and thermogravimetry were used to evaluate the thermal behavior of all copolymers synthesized under microwave energy. Based on the products analyzed by SEC and gas chromatography-mass spectrometry, a possible mechanism of degradation is postulated.Fil: Oberti, Tamara Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Alessandrini, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Cortizo, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Novel Copolymer of Diisopropyl Fumarate and Benzyl Acrylate Synthesized Under Microwave Energy and Quasielastic Light Scattering Measurements

Microwave assisted free radical copolymerization of diisopropyl fumarate (DIPF) and benzyl acrylate (BzA) with different copolymer compositions was performed using benzoyl peroxide as initiator. The effect of the reaction conditions on the macromolecular characteristics, monomer reactivity ratio and copolymer properties were studied. The monomer conversion and average molecular weights increase with the content of BzA units in the copolymer. The copolymers were characterized by IR, ¹H and ¹³C-NMR spectroscopies and the molecular weights were analyzed with size exclusion chromatography (SEC). The reactivity ratios obtained from an extended Kelen-Tüdös method under microwave irradiations are a factor which is double than those obtained by thermal copolymerization. The product r₁r₂ = 0.152 suggests a preference of both propagating macroradicals toward consecutive homopolymerization. The hydrodynamic and polydispersity size were measured in ethylacetate, tetrahydrofuran and methylethylketone with a quasi-elastic light scattering (QELS) technique showing that the quality of the solvents increases in the order: EA < THF < MEK.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física La Plat