TRACE ORGANIC COMPOUNDS AND PHOTOSENSITIZING ACTIVITY IN SALVADORAN SURFACE AND TAP WATER SOURCES: A FIRST LOOK.

Despite their potential risks to human health and the environment at ng/L to μg/L concentrations, there has been relatively little effort to measure trace organic compounds (TOrCs) in surface waters of Central America. The concentrations of eighteen TOrCs detected at eleven surface water sites in the Lempa River basin of El Salvador and four sources of drinking water for the cities of San Salvador, Antiguo Cuscatlán, Soyapango, and Santa Tecla are reported here. All samples were analyzed via liquid chromatography with tandem mass spectrometry (LC-MS/MS).

Shear-induced structural and thermodynamic phase transitions in micellar systems.

In this contribution a methodology to compute and classify shear-induced structural and phase transitions in surfactant/water mixtures from rheological measurements is presented. Non-linear rheological experiments, considering variations in surfactant concentration and temperature, are analyzed. In particular, the parameters of the BMP (Bautista-Manero-Puig) model, obtained from the fitting of the shear stress versus shear rate data, which are functions of surfactant concentration and temperature, allow classifying structural and phase transition boundaries.

Low-grade oils and fats: effect of several impurities on biodiesel production over sulfonic acid heterogeneous catalysts.

Different lipidic wastes and low-grade oils and fats have been characterized and evaluated as feedstocks for the acid-catalyzed production of FAME. The characterization of these materials has revealed significant contents of free fatty acids, Na, K, Ca, Mg, P, unsaponifiable matter and humidity. Arenesulfonic acid-functionalized SBA-15 silica catalyst has provided yields to FAME close to 80% in the simultaneous esterification-transesterification of the different feedstocks, regardless of their nature and properties, using methanol under the following reaction conditions: 160 °C, 2 h, methanol to oil molar ratio of 30, 8 wt.

Immobilization strategies for laccase from Trametes versicolor on mesostructured silica materials and the application to the degradation of naphthalene.

The oxidation of naphthalene by immobilized laccase from Trametes versicolor has been performed using diverse immobilization strategies on mesostructured silica materials. Laccase was immobilized by physical adsorption on several SBA-15 with different textural properties and by covalent attachment on functionalized SBA-15 prepared by co-condensation method (direct synthesis). The adsorption of laccase was partially reversible and showed some degree of lixiviation.

Critical phenomenon analysis of shear-banding flow in polymer-like micellar solutions. 1. Theoretical approach.

The shear-banding flow in polymer-like micellar solutions is examined here with the generalized Bautista-Manero-Puig model. The coupling between flow and diffusion naturally arises in this model, which is derived from the extended irreversible thermodynamic formalism. The limit of an abrupt interface is treated here.

Isolation and genetic identification of PAH degrading bacteria from a microbial consortium.

Polycyclic aromatic hydrocarbons (PAH; naphthalene, anthracene and phenanthrene) degrading microbial consortium C2PL05 was obtained from a sandy soil chronically exposed to petroleum products, collected from a petrochemical complex in Puertollano (Ciudad Real, Spain). The consortium C2PL05 was highly efficient degrading completely naphthalene, phenanthrene and anthracene in around 18 days of cultivation. The toxicity (Microtox method) generated by the PAH and by the intermediate metabolites was reduced to levels close to non-toxic in almost 40 days of cultivation.

Compliance with a fetal movement chart by high-risk obstetric patients in a Peruvian hospital.

We sought to determine the degree of compliance with a novel fetal movement chart (FMC) by high-risk patients versus the standard so-called count-to-10 method. This prospective trial included 1400 high-risk patients. Women with singleton gestations were randomly assigned to use either the count-to-10 chart or a FMC proposed by the Latin American Center for Perinatology (CLAP).

Use of a diffusion model for mono- and bicomponent anion-exchange of two isoenzymes of glucoamylase from Aspergillus niger in a fixed bed.

The adsorption of glucoamylases I and II (GA I and GA II, respectively) from Aspergillus niger on the anion exchanger DEAE-Toyopearl 650 was studied in fixed-bed experiments, and the effect of temperature, flowrate, inlet concentration, bed length, and particle size on the process was characterized. The anion exchanger showed a higher adsorption capacity for the more active isoenzyme GA I in all experimental conditions studied. A mathematical model accounting for external and pore diffusion and nonlinear equilibrium isotherm (for GA I) was used to fit the experimental breakthrough curves, showing very accurate fittings in all of the operating conditions.