Validation of a method for the analysis of iron and manganese in table olives by flame atomic absorption spectrometry

There is no generally accepted method for determination of the amounts of iron and manganese in table olives. Application of flame atomic absorption spectrometry to the analysis of both elements has been examined to validate a method that may be used by the industry's quality control laboratory as well as by the laboratories of regulatory agencies. The method has detection limits of 0.106 and 0.022 mg/L and quantification limits of 0.271 and 0.057 mg/L, for Fe and Mn, respectively, referred to the solution to be measured. There was no significant effect due to the matrix, but a slight bias due to the presence of Ca has been detected. Recoveries were excellent, and the method was robust. Influence of operator, HCl and Mg salt compounds, calcination equipment, or dates on results was not found. Relative errors were, in general, below 4% for both cations, and repeatability was below 3.43 and 0.38 mg/kg of olive paste for Fe and Mn, respectively. The method is proposed for the analysis of Fe and Mn in ripe olives and table olives in general.     

Identifying areas of high-value vertebrate diversity for strengthening conservation

Identifying areas with relevant features of biodiversity is useful to rank priorities for strengthening the design of well-sited natural protected areas and to optimize resource investment in conservation. This study provides decision makers critical tools for highlighting pieces of land worthy of conservation in Spain. We studied four taxa—amphibians, reptiles, nesting birds and mammals—in a 50 × 50 km grid (n=259 cells). We used five criteria for identifying areas of high-value diversity: species richness, rarity, vulnerability, a combined index of biodiversity, and a Standardized Biodiversity Index that measured all four taxa together. As far as we know, the combined index of biodiversity and the Standardized Biodiversity Index are original. Areas of high-value diversity were defined as those cells within the 15% top segment of ranked values for the different criteria. Congruence of areas of high-value diversity for taxa pairs was moderate to low, and averaged 38.5% for areas of high-value diversity based on the combined index of biodiversity. The performance based on the average proportion of threatened species excluded from areas of high-value diversity followed the rank combined index of biodiversity=rarity (0.3%) > vulnerability (9.9%) > species richness (13.8%). The areas of high-value diversity identified according to the Standardized Biodiversity Index included all amphibian and mammal species, all but one reptile species (categorized as rare) and all but six bird species (three of which were categorized as threatened). About 70% of the areas of high-value diversity identified based on the Standardized Biodiversity Index included natural protected areas. However, they average only 274.6 km², thus occupying a small fraction of the areas of high-value diversity, and there is no guarantee that the species found in an area of high-value diversity site will be present in its protected fraction. Consequently, we urge managers of natural protected areas to conduct diversity surveys. We also urge that additional natural protected areas be established to include the gap of 30% of areas of high-value diversity not currently protected. We took an step for biodiversity conservation planning in the studied region, and discuss the usefulness of maps of areas of high-value diversity for conservation, ecological restoration, and environmental impact assessment and mitigation.     

Denitrification from an irrigated soil fertilized with pig slurry under Mediterranean conditions

Under a Mediterranean climate, denitrification losses were quantified for 2 years on a sandy loam soil with an irrigated maize crop. The effect of pig slurry application at two different rates (165 and 495 kg N ha^–1, respectively, for PS1 and PS3) was compared with that of urea (U) applied at 165 kg N ha^–1 and with a control treatment (P0) without fertilizer. After application, the denitrification rate (DR) increased in PS1 and PS3 respect to P0 and decreased to the levels of the control treatment after 5 days. In July and August (the irrigation period) the DR increased considerably in all treatments with maximum values for the PS3 treatment (0.134 g N m^–2 day^–1 in the first year and 0.147 g N m^–2 day^–1 in the second year). The differences in DRs between each treatment could be explained by the pattern of water filled pore space, NO₃^– concentration of the soil solution and the soil temperature during the maize growing season. In the first year denitrification losses in the 0–10 cm layer were 1.90, 2.49, 2.87 and 4.00 g N m^–2 for P0, U, PS1 and PS3, respectively, while in the second year the losses were 1.21, 2.28, 2.47 and 3.42 g N m^–2. Finally, a simple predictive model (SOILN) was evaluated and found to give acceptable results.     

Effect of soil properties on the degradation of isoxaflutole and the sorption-desorption of isoxaflutole and its diketonitrile degradate

The transformation of isoxaflutole (ISOX) to its herbicidally active diketonitrile degradate (DKN) was significantly enhanced in the presence of soil and occurred more rapidly in systems containing soil with a greater soil pH. Sorption-desorption of ISOX and DKN in five soils collected within a field revealed both ISOX and DKN were more readily sorbed to soils with greater organic matter, clay content, and lower soil pH. Sorption of ISOX residues occurred within 2 h, and extracts contained similar concentrations of ISOX and DKN at 24 h, suggesting the 24-h sorption coefficients for ISOX-treated systems were actually for mixed ISOX residues. Freundlich sorption coefficients were 3 and 4 times greater for ISOX than for DKN. On the basis of the Freundlich organic carbon sorption constants, ISOX and DKN can be categorized in the very high and high mobility classes, suggesting their potential to leach in the soils needs to be evaluated.     

Using linear-bilinear models for studying gene expression × treatment interaction in microarray experiments

In microarray experiments, the global and the specific gene expression in the two-way table of gene x treatments (or tissues) can be studied using linear-bilinear models that incorporate the main effects of genes (G), treatment (T), and gene x treatment interaction (G x T). The plot of the first two axes obtained from the singular value decomposition of the bilinear (multiplicative) term of these models (biplot) facilitates the interpretation of the gene expression patterns. In this study, two microarray datasets were used to illustrate how two linear-bilinear models, the additive main effect and multiplicative interaction (AMMI) and the treatment regression model (TREG) and their biplots can be used to determine the overall gene expression pattern across treatments (or tissues) and for specific treatments. Dataset 1 had 5,339 genes and the objective was to identify genes with modified expression during maize (Zea mays) seed development in response to different parental ploidy levels. In Dataset 2, the aim was to study gene expression in 15 tissue samples with different levels of development of breast cancer when compared with the expression of the genes in noninfected tissues. The results from the analyses of Dataset 1 showed that the biplots of the AMMI and TREG models allow identification of subsets of genes and treatments with noncrossover G x T interaction or with important levels of crossover G x T. Results from Dataset 2 showed that the TREG model and its biplot facilitates the identification of genes with high expression in all tumor cells. Also, the TREG biplots allowed identification of subsets of genes with a low level of gene x tissue crossover interaction.     

Population viability analysis and fire return intervals for an endemic Florida scrub mint

We use population viability analysis of an endangered Florida scrub mint, Dicerandra frutescens, to specify the optimal fire return intervals for its long-term persistence and for its specific habitat. We derived 83 population projection matrices from 13 years of demographic data from eight populations, 59 matrices from scrub populations and 24 from firelane or yard edges. Seed dormancy and germination transitions were inferred based on experimental data and verified by comparing modeled vs. observed population trajectories. Finite rates of increase in scrub sites were highest shortly after fire and declined steeply through 10 years postfire. The break-even value of λ = 1 was passed quickly, in about six years, suggesting that populations >6 years postfire were already facing decline. The decline is probably related to the rapid growth of competing shrubs in the habitat of D. frutescens. In long-unburned sites, finite rates of increase were nearly always <1 and declined the most in the long-unburned site with no foot trails or treefall gaps. Finite rates of increase in firelane populations also declined with years since fire or last disking. The yard edge population showed λ values both >1 and <1, with no temporal trend. Stochastic simulations in scrub sites suggested an optimal regular fire return interval of about 6-12 years. Regular fires at this interval were more favorable than stochastic fire regimes, but stochasticity reduced extinction percentages at longer fire return intervals. Stochastic fire return intervals implied a wider optimal fire return interval of 6-21 years. We suggest that prescribed fire in Florida scrub on yellow sand has occurred (and needs to occur) more frequently than previously recommended.     

Oxidation of resveratrol catalyzed by soybean lipoxygenase

In this work the oxidative degradation of resveratrol catalyzed by lipoxygenase-1 (LOX-1) has been studied. The process has been characterized by spectroscopic and polarographic measurements. The oxidation of resveratrol was dependent on the concentration of resveratrol and the enzyme. When resveratrol was incubated in the presence of lipoxygenase at pH 9.0, the reaction displayed a k(M) value of 18.6 x 10(-)(6) M and a catalytic efficiency (k(cat)/k(M)) of 4.3 x 10(4) s(-)(1) M(-)(1). These values are close to those shown by the enzyme when linoleic acid is used as the substrate. The effect of lipoxygenase inhibitors on the lipoxygenase-catalyzed resveratrol oxidation was also evaluated. The rate of resveratrol oxidation was markedly decreased by the presence of NDGA in the incubation mixture. From HPLC measurements, it can be deduced that resveratrol is oxidatively decomposed to a complex mixture of products similar to those obtained when the molecule is oxidized by hydrogen peroxide.     

Ultrasonic assessment of oil quality during frying

In this paper, changes in ultrasonic properties during thermoxidation of virgin olive oil were studied. Samples of virgin olive oil were heated over different periods of time from 2 to 16 h at 200 degrees C. Oil degradation was characterized by means of physical and chemical changes, i.e., viscosity, color, polar compounds, polymers, and polar fatty acids. Ultrasonic measurements were carried out while the oil sample was cooled from 35 to 25 degrees C. It was found that velocity and attenuation measurements were related to viscosity measurements through a classical equation for viscous liquids. The ultrasonic measurements were also related to the percentages of polar compounds and polymers, which shows the feasibility of using ultrasonic properties to monitor oil quality. Nevertheless, as long as the ultrasonic measurements are temperature dependent, this variable must be controlled in order to obtain repetitive and reliable measurements.     

Optimization and simulation of drying processes using diffusion models: application to wood drying using forced air at low temperature

This paper discusses the suitability of four diffusion models to describe the drying of wood. The first model refers to the analytical solution of an infinite slab with boundary condition of the first kind. In the last three models, the boundary condition is of the third kind and the analytical solutions refer to the following geometries: infinite slab, rectangle, and parallelepiped. The analytical solutions were coupled to an optimizer based on inverse method, which enables to calculate process parameters for an experimental data set. Once the process parameters were determined, the drying kinetics of wood was simulated through each model proposed. The obtained results lead to the conclusion that the first model does not represent the drying kinetics properly. The last three models adequately describe the drying kinetics, but statistical indicators enable to affirm that the best of them is the three-dimensional model.