Pressurised liquid extraction and capillary electrophoresis–mass spectrometry for the analysis of pesticide residues in fruits from Valencian markets,Spain

A procedure based in capillary electrophoresis–mass spectrometry (CE–MS) for the analysis of seven pesticides (flutolanil, simazine, haloxyfop, acifluorfen, dinoseb, picloram, and ioxynil) in four Mediterranean summer fruits with high water content (peaches, melon, watermelon, and apricot) is developed. Several conditions were studied for the optimisation of both, the separation and the electrospray (ESI) connection. The best results were obtained using 35 mM ammonium formiate (pH 9.7) as separation buffer, 20 °C as capillary temperature and 23 kV as applied voltage in an uncoated fused-silica capillary with 50 cm total length, 25 cm thermostated length, 25 cm at room temperature length, connected to an MS detector by an ESI sprayer kit. The appropriate sheath liquid was ammonium formiate with 10% of formic acid at 5 μL min⁻¹. Separation time for all pesticides was achieved in 12 min. Extraction was carried out by pressurised liquid extraction (PLE) in an ASE® 200 system from Dionex using hot water at 60 °C and 1500 psi, followed by a solid-phase extraction (SPE) clean-up step using StrataX cartridges. Recoveries ranged from 58% to 88% and the relative standard deviations (RSDs) were 9–19%. The limits of detection (LODs) and quantification (LOQs) were in all cases lower than the MRLs, 0.01 and 0.05 mg kg⁻¹, respectively. The potential of the method was demonstrated by analysing summer fruits taken from agricultural Mediterranean zone cooperatives.     

Combustion of forest litters under slope conditions: Burning rate,heat release rate,convective and radiant fractions for different loads

A set of experiments at laboratory scale was conducted to study the combustion of forest fuel beds in order to quantify the contribution of radiant and convective heat transfer under slope condition. To proceed, a Large Scale Heat Release apparatus was used to measure the heat release rate and fire properties such as the mass loss rate, the geometry of the fire front and the heat transfer were assessed. Because of the slope and the size of the fuel bed, the mass loss rate and the heat release rate do not reach a quasi-steady state when the propagation takes place under slope condition. This is due to a V-shape distortion of the fire front, which leads to an increase of the burnt surface rate by the fire over time. The study of this quantity has shown that the heat release over time can be estimated with the fuel load and the time derivative of the burnt surface. The fractions of radiation and convection released by the fire in its environment were calculated. Under a slope of 20°, the convective fraction decreases from 74.9% to 61.1% whereas the overall radiant fraction ranges between 25.1% and 38.9% and increases with increasing fuel loads.     

The evolution of free fatty acids during the ripening of Idiazábal cheese: influence of rennet type

 The object of the present study was to determine the influence of the rennet type on the free fatty acid (FFA) content of Idiazábal cheese. Varying this parameter during cheese-making resulted in significant differences in FFA content in the cheeses during ripening. The main FFAs in both cheese batches were caproic acid (C6 : 0) and capric acid (C10 : 0). The differences between the extreme values for the lipolysis rate were around 45%, which emphasizes the importance of the cheese-making procedure employed on lipolysis in this type of cheese. The use of locally made rennet in the preparation of Idiazábal cheese increased the level of lipolysis in the cheese. Received: 4 December 1998 / Revised version: 18 March 1999     

Comparison of RAPDs, AFLPs and SSR markers for the genetic analysis of yeast strains of Saccharomyces cerevisiae

We evaluated the usefulness of different molecular techniques for the genetic analysis of Saccharomyces cerevisiae strains. Three commonly used PCR-derived genetic methods, random amplified polymorphic DNA (RAPDs), amplified fragment length polymorphism (AFLPs) and simple sequence repeats (SSRs; microsatellites), were used to characterize 27 wine yeast strains of S. cerevisiae from the “Denominación de Origen Vinos de Madrid” (Spain). Using these methods, we were able to overcome certain limitations associated with classical taxonomic methods. Based on the presence or absence of amplified fragments for each genotype, AFLPs and SSRs showed a similar discriminatory power superior to that of the RAPDs. Genetic relationships between strains were also estimated using the three methods. In general, very poor correlations were found, reflecting the different genomic regions for which the methods are screened. Results are discussed in terms of which molecular technique is most appropriate for use with a particular aspect of genetic evaluation.     

A Novel Noninvasive Ultrasonic Method to Assess Avocado Ripening

ABSTRACT: A novel method to assess the ripening state of Persea Americana Mill avocados was developed. The method was validated and its results compared with standard ones such as the penetrometer method. Also, comparison were made between the proposed method and the ultrasonic system reported by other authors. The correlation between the proposed method and both the standard and former ultrasonic method is quite good. The measurement system overcomes the problem of alignment between the emitter and receiver found in the resent execution development for the same purposes. Extension of proposed systems could allow the measurement with a single ultrasonic source and possibility the development of an online evaluation system for all the fruits.     

Relationship of solo status, academic rank, and perceived distinctiveness to job satisfaction of racial/ethnic minorities.

The relationships among solo status of racial/ethnic minorities in psychology departments, job satisfaction, and subjective feelings of distinctiveness were examined. Distinctiveness was defined as stigmatizing feelings associated with token status of racial/ethnic minorities in academia. It was hypothesized that minorities in positions of solo (relative to nonsolo) status within their departments, members of more stigmatized groups, and minorities occupying lower academic ranks would feel more distinctive and less satisfied with their jobs and that perceptions of distinctiveness would mediate job satisfaction. The data partially supported these hypotheses, most notably for African Americans. The implications of situational salience and the importance of recognizing differences among and between minority groups are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prebiotic potential of a refined product containing pectic oligosaccharides

Apple pomace samples were subjected to Simultaneous Saccharification and Fermentation (SSF) to yield a medium containing mainly lactic acid and oligosaccharides. After lactic acid removal by ion exchange, the SSF medium was refined by a two-step (diafiltration-concentration) membrane treatment. Limited losses of glucooligosaccharides, galactooligosaccharides, xylooligosaccharides and arabinooligosaccharides were noticed in permeates, whereas the concentrate from the second stage showed low concentrations of lactic acid, arabinose and NaCl, which were extensively removed in the refining process. About 60% other the non-saccharide compounds present in the solution fed to membranes were removed in permeates, whereas oligogalacturonides were quantitatively recovered in the final concentrate. The refined product was assayed for its prebiotic potential by means of in vitro fermentability assays performed with individual microbial strains or human fecal inocula. In this latter case, the dynamics of microbial populations was assessed by Fluorescent In Situ Hybridization (FISH). The experimental results proved the prebiotic effects caused by the refined product obtained in this work, which included the promotion of beneficial bacterial growth and the increase of short chain fatty acids (SCFA) concentrations.     

Revealing the proliferation of hydrogen scavengers in a single-chamber microbial electrolysis cell using electron balances

The bioelectrochemical generation of hydrogen in microbial electrolysis cells (MECs) is a promising technology with many bottlenecks to be solved. Among them, the proliferation of hydrogen scavengers drastically reduces the cell efficiency leading to unrealistic coulombic efficiencies (CE) and cathodic gas recoveries (r_CAT). This work provides a novel theoretical approach to understand, through electron equivalent balances, the fate of hydrogen in these systems. It was validated with a long term operated single-chamber membrane-less MEC. In the short term, H₂-recycling (i.e. hydrogen being derived to the anode) resulted in r_CAT of only 4% and in CE up to 463%. The 80.5% of the current intensity came from H₂-recycling and only the 19.5% from substrate oxidation. In the long term, methane was produced from hydrogen, thus decreasing r_CAT to 0 (r_CAT = 94.5% when considering methane production). CE was 74.5% suggesting that H₂-recycling only took place when methanogenic activity was marginal.     

Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

Abstract

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed.     

Ammonium Ion Adsorption and Settleability Improvement Achieved in a Synthetic Zeolite-Amended Activated Sludge

Municipal wastewater treatment plants typically exhibit two classic problems:high ammonium concen-tration in water after conventional biological treatment and, in some cases, poor activated sludge sedi...