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En los pacientes con gonalgia por gonartrosis, disponemos de tratamientos no exentos de efectos secundarios. Objetivo: evaluar la eficacia analgésica de la radiofrecuencia (pulsada y convencional) sobre el nervio safeno a nivel subsartorial y los nervios geniculares de la rodilla, mediante la localización por ultrasonografía.

Liquid holdup and dispersion are reported for a column of 2 mm internal diameter, filled with 0.1 mm spherical particles, for multiphase flows with hydrocarbon liquid flow rates of 10–100 μL/min and nitrogen gas flow rates of 50–1000 μL/min using different tracers with varying diffusion coefficients and vapor pressures. It was found that the liquid holdup (liquid volume/external void volume) was between 0.65 and 0.85, with variations between different experiments and limited impact of flow rate on the holdup. The dispersion characteristics were very similar to single‐phase dispersion. The particle Peclet number for dispersion was close to 0.2. This value was of the same order of magnitude – just a factor of two to three lower – as the value that was obtained without gas flow. Tracer volatility did cause the tracer to elude earlier, but did not cause significant additional dispersion. The results suggest that the fluid mechanical interaction between the gas and the liquid was very limited.

Abstract: The phase behavior of different fatty acids (FA) in pseudo-ternary mixtures [(water)/(FA) + (alcohol)/(oil)] was studied. The Winsor I-III-II transitions of ionized compounds were attained by varying the FA composition through the formulation scan. The middle-phase volume, the pH of the optimum system, and the partition coefficient increased with the chain length of FA. Conversely, the acid partition coefficient allows calculation of the Gibbs free energy of transfer of a CH2 group from oil to water, which is found to be +0.87 J/mol.

The phase behavior of different fatty acids (FA) in pseudo-ternary mixtures [(water)/(FA) + (alcohol)/(oil)] was studied. The Winsor I-III-II transitions of ionized compounds were attained by varying the FA composition through the formulation scan. The middle-phase volume, the pH of the optimum system, and the partition coefficient increased with the chain length of FA. Conversely, the acid partition coefficient allows calculation of the Gibbs free energy of transfer of a CH2group from oil to water, which is found to be +0.87 J/mol.

Cadmium increases or decreases prolactin secretion depending on the dose and duration of the exposure to the metal. However, whether there are cadmium effects on the episodic prolactin secretion is less well known. This study was undertaken to address whether chronic alternating exposure to two different doses of cadmium affects the episodic pattern of prolactin and to what extent the effects of cadmium are age-dependent. Male rats were treated s.c. with cadmium chloride (0.5 or 1.0 mg/kg) from day 30 to 60, or from day 60 to 90 of age, with alteration of the doses every 4 days, starting with the smaller dose. Controls received vehicle every 4 days. The last dose of cadmium was given 48 h prior to the pulsatility study. Prolactin secretion in the 4 experimental groups studied was episodic and changed significantly after cadmium exposure. Cadmium administration from day 30 to 60 of life significantly decreased the mean half-life of prolactin. On the other hand, when administered from day 60 to 90 cadmium significantly decreased the mean as well as serum prolactin levels and the absolute amplitude of the prolactin pulses, their duration, the relative amplitude or the mean half-life of the hormone. The frequency of prolactin peaks was not changed by cadmium administration. The results indicate that low intermittent doses of cadmium chronically administered change the episodic secretion pattern of prolactin in rats. The effects of cadmium on prolactin secretion were age dependent.

Abstract: This work was undertaken to assess if exposure to cadmium related to puberty may affect the episodic pattern of prolactin. Male rats were submitted to cadmium exposure, from day 30 to 60 or from day 60 to 90 of life respectively, at a dose of 50 ppm in the drinking water. Control age-matched rats received cadmium-free water. Prepubertal cadmium administration decreased mean serum prolactin levels and the absolute amplitude of the prolactin pulses. Subchronic exposure to cadmium of adult rats decreased mean serum prolactin levels, the absolute amplitude of the prolactin pulses and their duration, and the mean half-life of the hormone. These results suggest that subchronic cadmium exposure changes the secretory pattern of prolactin in adult male rats in a puberty-dependent way.

Commercial ethoxylated alkylphenol surfactants are always a mixture of oligomers with different ethylene oxide number (EON). The different oligomers can be separated by various HPLC techniques. Isocratic mode with mixed solvent on silica column allows to separate oligomers up to EON = 10; gradient programming moves the limit up to EON = 15. For higher EON values (up to 25) a NH2 column has to be used, either with isocratic or gradient mode. Applications to the analysis of microemulsion systems and to the separation of tributyl phenol ethoxylates are discussed. Extreme separation of wide range EON distribution is attained with two columns (Si and NH2) in series, and a solvent programming.

The different oligomers of ethoxylated nonylphenols present in commercial surfactants can be separated by HPLC. While low ethylene oxide number (EON) species may be separated by isocratic HPLC on silica, intermediate EONs require gradient elution HPLC. The separation of higher oligomers can be carried out with an intermediate polarity column of the NH2 type and a solvent gradient. The suggested experimental conditions allow a satisfactory single run separation of a complex mixture with EONs ranging from 1 to 25 by using a linear gradient from 100% less polar solvent (n-heptane - chloroform - methanol 90/5/5) to its mixture with up to 20% of a more polar solvent made of chloroform - methanol (50/50). This method is used to analyze the EON distribution resulting from the mixing of different commercial surfactants. When two surfactants with very different EON distributions are mixed to produce a formulation scan, the occurrence of three-phase behavior at the optimum formulation of the surfactant - oil - water system is found to correlate with the absence of a gap in the overall EON distribution. Both the fractionation of low EON species into the oil phase and the fractionation of high EON oligomers into the water phase result in a depletion of the microemulsion phase.

Different petroleum fractions were sulfonated with fuming sulfuric acid. The fractions were isolated from Boscan crude oil by Soxhlet extraction. This method allows for the separation of four fractions which were extracted with acetonitrile, methanol, n-heptane and benzene, respectively. The separation was monitored by UV/VIS spectrophotometry AAS. After sulfonation, the oil layer was neutralized with caustic soda. The sulfonated sodium salts of each fraction were extracted with ethanol–water. UV/VIS spectra of the diluted aqueous phases of each fraction showed a characteristic band of sulfonate. In all cases, Fraction 3 showed the greatest concentration of sulfonates. Finally, the molecular mass distribution was examined by using an Ultrastyragel column. Fraction 3 exhibited a widespread molecular mass and symmetrical distribution.