Search results for "Actant"
showing 10 items of 473 documents
Ultrastructure of posterior sternal glands of Macrotermes annandalei (Silvestri): new members of the sexual glandular set found in termites (Insecta)
2004
0362-2525 (Print) Comparative Study Journal Article; In female alates of Macrotermes annandalei, two types of abdominal glands are involved in the secretion of sex pheromone. Tergal glands are found at the anterior margin of tergites 6-10 and posterior sternal glands (PSGs) are located at the anterior margin of sternites 6-7. The cytological features of both types of glands are quite similar. The fine structural organization of PSGs is studied more precisely and described for the first time. The glandular cuticle is pitted with narrow apertures corresponding to the openings of numerous subcuticular pouches. Several Class 3 glandular units open in each pouch. One canal cell and one secretory…
Surfactant self-assembling in the gas phase: bis(2-ethylhexyl)- sulfosuccinate divalent metal ion anionic aggregates
2012
RATIONALE: Investigation of fundamental aspects driving surfactant self-assembling and of the capability of including guest molecules or ions in their micellar aggregates is an exciting research field for theoretical and technological reasons. In this light, assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ion chlorides have been investigated in the gas phase by electrospray ionization mass spectrometry in negative ion mode, tandem mass spectrometry and energy-resolved mass spectrometry. METHODS:Water/methanol solutions of AOTNa and chloride salts of nickel, magnesium, calcium and manganese, with different AOTNa/metal salt ratios, …
Gas Phase Charged Aggregates of Bis(2-ethylhexyl)sulfo-succinate (AOT) and Divalent Metal Ions. First evidence of AOT solvated aggregates
2011
Assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ions have been investigated in the gas phase by electrospray ionization mass spectrometry. A variety of positively charged monometallated and mixed metal aggregates are formed. Interestingly, several ions contain solvent (MeOH, H2O) molecules and constitute the most abundant AOT cationic aggregates not containing sodium. These species are the first example of solvated AOT-metal ion aggregates in the gas phase. By increasing the surfactant aggregation number, the abundance of solvated species becomes lower than that of unsolvated ones. Decompositions of ionic species have been studied…
Do electrospray mass spectra of surfactants mirror their aggregation state in solution?
2011
One important feature in the gas phase chemistry of surfactants is to ascertain whether their aggregates produced by electrospray ionization reflect those formed in the starting solution. With this aim, we have performed ESI-MS, ESI-MS/MS and ER-MS spectra of bis(2-ethylhexyl)sulfosuccinate (AOTNa) solutions in different solvents, i.e. water, water/methanol, methanol and n-hexane. The results clearly indicate that, notwithstanding the strongly different aggregation state in solution (direct micelles in water and in water/methanol, molecular dispersion in methanol and reverse micelles in n-hexane) and marked effects of the solvent polarity on the total ionic current, the surfactant aggregate…
Administración de Surfactante mediante técnica mínimamente invasiva en recién nacidos pretérmino: evaluación de la seguridad y la eficacia
2021
La terapia con surfactante forma parte de la práctica habitual en el manejo del distrés respiratorio en el recién nacido. Su administración ha sido tradicionalmente mediante intubación endotraqueal. Con el fin de minimizar el tiempo de intubación y ventilación mecánica se diseñó la estrategia INSURE (intubación, administración de surfactante y extubación), disminuyendo la posible exposición a la ventilación mecánica. En los últimos años se han investigado nuevas técnicas de administración de surfactante menos invasivas con el objetivo de minimizar los efectos de la intubación traqueal y evitar la aplicación de la ventilación mecánica. El método SONSURE consiste en la administración de surfa…
Demo 61. Tensión superficial. Ley de Tate
2013
Objetivo: Observar la diferencia de tensión superficial entre el agua y el alcohol. Comprobar el efecto de un surfactante como reductor de la tensión superficial.
Review: Mass spectrometry of surfactant aggregates
2011
In contrast with the enormous amount of literature produced during many decades in the field of surfactant aggregation in liquid, liquid crystalline and solid phases, only a few investigations concerning surfactant self-assembling in the gas phase as charged aggregates have been carried out until now. This lack of interest is disappointing in view of the remarkable theoretical and practical importance of the inherent knowledge. The absence of surfactant–solvent interactions makes it easier to study the role of surfactant–surfactant forces in determining their peculiar self-assembling features as well as the ability of these assemblies to incorporate selected solubilizate molecules. Thus, th…
Control of the Development of Swirling Airflow Dynamics and Its Impact on Biomass Combustion Characteristics
2017
Abstract The development of the swirling flame flow field and gasification/ combustion dynamics at thermo-chemical conversion of biomass pellets has experimentally been studied using a pilot device, which combines a biomass gasifier and combustor by varying the inlet conditions of the fuel-air mixture into the combustor. Experimental modelling of the formation of the cold nonreacting swirling airflow field above the inlet nozzle of the combustor and the upstream flow formation below the inlet nozzle has been carried out to assess the influence of the inlet nozzle diameter, as well primary and secondary air supply rates on the upstream flow formation and air swirl intensity, which is highly …
A route to simple nonionic surfactants
2016
AbstractA method for the synthesis of nonionic surfactants – N-alkyl-O-(2-hydroxyethyl) carbamates is proposed by acylation of fatty amines with ethylene carbonate without any solvent or catalyst. The surface tension of the prepared surfactants was measured, toxicity and biodegradability were determined for the surfactant with n-dodecyl as a hydrophobic group and N-monosubstituted amide and hydroxyl groups for their hydrophilic part.
Estudio multidisciplinar de la Muerte Súbita e Inesperada del Lactante en la Comunidad Valenciana. 2006-2017. Estrategia de análisis y prevención
2020
El síndrome de la muerte súbita del lactante (SMSL) define la muerte súbita de un niño menor de un año de edad, que ocurre aparentemente durante el sueño y que permanece sin explicación después de la realización de una minuciosa investigación postmortem, que incluye la autopsia completa, la investigación de las circunstancias de la muerte y la revisión de la historia clínica. La etiopatogenia del SMSL se ha entendido a través de la hipótesis del triple riesgo. Las tasas de incidencia del SMSL, han ido descendiendo drásticamente situándose en la actualidad en 0,2 -0,5 por mil nacimientos vivos, manteniéndose estable en los últimos años. Los factores de riesgo relacionados con el sueño del la…