Search results for "Concentration."
showing 10 items of 1849 documents
Amusium cristatum shell beds in the lower Pliocene deposits of Almería-Níjar Basin (SE Spain)
2020
Densely packed monospecific-paucispecific Amusium cristatum-dominated shell beds are signifi cant features in the lower Pliocene deposits of the Almeria-Nijar Basin (SE Spain), embedded in distal prodelta fi ne-grained sand and silt. The shells in these concentrations are exceptionally well preserved: articulation is relatively high, fragmentation is low, abrasion is almost lacking, and many shells preserve the original colour pattern. These taphonomic signatures suggest in situ deposition forming autochthonous fossil assemblages, i.e. biological concentrations. Benthic foraminiferal assemblages found in the prodelta deposits indicate that they formed in mesotrophic mid-shelf settings.The A…
Identification and dose dependency of ibuprofen biliary metabolites in rainbow trout
2012
Abstract The biotransformation of the anti-inflammatory drug ibuprofen (IBF) was studied by exposing rainbow trout ( Oncorhynchus mykiss ) to IBF via intraperitoneal (i.p.) injection, and via water at four (0.17, 1.9, 13 and 145 μg L −1 ) exposure levels for 4 d. Following exposure, the bile was collected and analyzed by LC–MS/MS methods. The identification of the formed metabolites in i.p. injected fish bile was based on the exact mass determinations by a time-of-flight mass analyzer (Q–TOF–MS) and on the studies of fragments and fragmentation patterns of precursor ions by ion trap mass analyzer (IT-MS). In addition to unmetabolized IBF, several phase I and phase II metabolites were found …
Experimental Studies on the Influence of Surfactants on Intestinal Absorption of Drugs Cefadroxil as model drug and sodium taurocholate as natural mo…
2011
The influence of the natural bile acid surfactant sodium taurocholate (CAS 81-24-3) on colic and duodenal (i.e. the proximal third of the small intestine) absorption of cefadroxil (CAS 50370-12-2) was studied using the in situ rat gut technique, and compared with the effect of sodium lauryl sulfate (CAS 151-21-3), the most widely used synthetic anionic surfactant. Previously, the stability, compatibility, and micelle-solubilization characteristics of taurocholate were assessed in order to correct, when necessary, the absorption results. White the passive absorption rate constants (kf, h-1) determined in colon in the presence of increasing lauryl sulfate concentrations showed an asymptotic v…
Film blowing of silane-modified polyethylene
2009
The grafting of vinyltriethoxysilane (VTES) onto polyethylene (PE) with the help of small amounts of peroxides was investigated to film-blow these modified materials. The degree of crosslinking was kept very low to achieve good melt processability and improved mechanical properties. The possibility of obtaining modified PE films with improved properties and regularly distributed crosslinking with a single processing step demonstrates the uniqueness of this study. The additive concentration was established through preliminary studies; with a batch mixer, it was possible to process the modified PE in the film-blowing operation. Water treatment of the modified films after film blowing allowed …
Benchmarking of strength models for unidirectional composites under longitudinal tension
2018
© 2018 Elsevier Ltd Several modelling approaches are available in the literature to predict longitudinal tensile failure of fibre-reinforced polymers. However, a systematic, blind and unbiased comparison between the predictions from the different models and against experimental data has never been performed. This paper presents a benchmarking exercise performed for three different models from the literature: (i) an analytical hierarchical scaling law for composite fibre bundles, (ii) direct numerical simulations of composite fibre bundles, and (iii) a multiscale finite-element simulation method. The results show that there are significant discrepancies between the predictions of the differe…
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanopart…
2022
The advancement of analytical methods for nanoparticle measurements is critical both for the growing industrial exploitation of engineered nanoparticles and for developing robust strategies to understand and control the concentration of nanomaterials in humans and the environment. For high value nanoparticles, the measurement of nanoparticle number concentration in a liquid directly impacts the ability to assess the scale and reproducibility of the production process, it allows optimisation of efficiency and supports regulatory compliance. This measurement is also useful to monitor and control the intentional or accidental release of engineered nanoparticles into the environment at the produc…
Solution properties of polyelectrolytes—V. Viscometric study of mixed polyanions in pure water
1990
Abstract A viscometric study of sodium polystyrene sulphonate (NaPSS) and sodium poly( l -glutamate) (NaPLG) in salt-free water has been carried out as a function of the total concentration, cm, and the concentration of one polyelectrolyte at fixed concentration of the other. The influences of the molecular weight and concentration are considered in order to establish the degree of compatibility. For the first time, an equation is proposed to define the reduced viscosity of the NaPSS + NaPLG mixture in water. The viscometric interaction parameter, Bm, taking into account the electrostatic and thermodynamic interactions between both polyions, is defined as a geometrical mean of the contribut…
Standard partial molar volumes of alcohols in aqueous dodecyltrimethylammonium bromide solutions
1990
Density measurements of water-dodecyltrimethylammonium bromide (DTAB)-alcohol ternary systems as a function of alcohol and surfactant concentrations were carried out at 25°C. The alcohols were propanol (PrOH), 2-propanol (2-PrOH) and hexanol (HexOH). The apparent molar volume Vϕ,R of alcohols have been calculated and the standard (infinite dilution) partial molar volumes of alcohols V R at each surfactant concentration were obtained by means of a least squares fit of Vϕ,R vs. the alcohol concentration. The V R vs. surfactant concentration curves have been rationalized in terms of the partial molar volume of alcohol in the aqueous V f and the micellar V b phases and the distribution constant…
Heat capacities and volumes of suspensions in the presence of surfactants
2004
Abstract Density and heat capacity measurements of water–surfactant–silica ternary systems were carried out as functions of the silica and the surfactant concentrations at 298 K. From these properties, the apparent molar volume and heat capacity of the surfactant in a given water+silica mixture were evaluated. As well, the apparent specific volume and heat capacity of silica, at a given concentration, in the water+surfactant mixtures as functions of the surfactant concentration were calculated. Some surfactants (decyltrimethylammonium bromide, sodium octanoate, sodium decanoate, sodium dodecanoate, sodium decylsulfate, sodium perfluorooctanoate and N , N -dimethyldodecylamine- N -oxide) wer…
Primo Levi, a critic humanist
2015
La intención de este escrito es reflexionar sobre el pensamiento del italiano Primo Levi y defender como apropiado el referirnos a él como un ‘humanista crítico’. Para ello seguimos los criterios propuestos por T. Todorov para caracterizar la doctrina humanista en tres elementos: autonomía del yo, finalidad del tú y universalidad de los ellos, y los propios del humanismo crítico, único posible tras lo ocurrido en Auschwitz y Kolyma: el reconocimiento del horror del que somos capaces los seres humanos y la afirmación de la posibilidad del bien. Palabras-clave: Humanismo crítico, Campos de concentración, Sobreviviente,Testimonio, Memoria. The aim of this research is to reflect upon the though…