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The effect of four essential oils and eleven selected components on the infective juveniles (IJ) of the entomopathogenic nematode Heterorhabditis amazonensis Andaló et al. strain HC1 was studied under laboratory conditions. Susceptibility of this strain to seven organic solvents and surfactants was determined. The lethal and sublethal toxic effects on IJ exposed directly to the essential oils and components were evaluated in 24 well plates for 24 h. Data of lethal toxic effects were subjected to ANOVA and the means compared by Duncan's multirange test at 0,05 %, whereas data of sublethal toxic effects were analyzed by the multiple comparison of proportions (Wald's Method, confidence level of 0,05). Toxicity of Triton X-100 at 0,5 % on H. amazonensis strain HC1 was low and could be used in bioassays of chemical product compatibility with this nematode strain. The essential oils of Melaleuca quinquenervia (Cav) S.T. Blake and Citrus sinensis (L.) Osbeck caused no significant lethal toxic effect on IJ of H. amazonensis (strain HC1), while those of Piper aduncum subsp. ossanum (C. DC.) Saralegui and Piper auritum Kunth produced moderate mortality. No sublethal effects were caused by these four oils on the infectivity of IJ of H. amazonensis strain HC1. The essential oil components camphene, p-cymene and piperitone did not affect IJ of H. amazonensis strain HC1; 1,8-cineole, limonene, camphor, and methyl chavicol showed moderate toxicity, and carvacrol, eugenol, linalool, and thymol were highly toxic. According to the parameters evaluated, the essential oils from M. quinquenervia and C. sinensis and the components camphene, p-cymene, and piperitone were compatible with H. amazonensis strain HC1. [ABSTRACT FROM AUTHOR]

The influence of aqueous dissolutions of sodium alginate and carboxymethylated derivatives on the absorption and micellar critical concentration (CAC and CMC*) of Triton X-100 and CTAB surfactants was studied by tensiometry (γ) and conductimetry (κ). An inflection at 0,1x10-4 mole/L in the curve of γ vs [Triton X-100] in the presence of solutions of 0,1, 0,5 and 1 g alginate/L was observed; suggesting weak polymer-surfactant interaction. The CMC* in the presence of alginate, decreases to 1.0x10-4 mole/L. CAC and CMC* of CTAB in the presence of alginate and the greatest substituted derived are similar by both methods, CAC tends to decrease with concentration, while CMC* increased with the concentration of polysaccharide and in a presence of a highest substitution degree, characteristic behavior of systems with opposite charges. These show three critical concentrations: CMC*, CAC and another originated by interactions attributed to the presence of non-cooperative associations about 0.045x10-3 mole/L. [ABSTRACT FROM AUTHOR]

Copyright of Revista Técnica Energía is the property of Centro Nacional de Control de Energia CENACE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this work was to study the effect of the concentration of a non-ionic surfactant in water on the interfacial tension of an alkane series. For this purpose Triton X-100 and the alkanes: hexane, heptane, octane, decane, undecane and dodecane were selected for analysis. The tests were done at concentrations of 10-3, 10-4 and 10-5 mol/L and the emergent drop model was employed for the calculation of the interfacial tension. In this work it was observed that the interfacial tension of the Triton X-100 solutions in water decreased as the concentration of the surfactant increase. It was concluded that the interfacial tension value is a function of the concentration, the exposure time of the interface with the dissolution and the initial volume of the drop at the moment when the measurement starts. [ABSTRACT FROM AUTHOR]