Decomposition of nitrous oxide on pillared clays

Alumina-pillared smectites have been found to abate nitrous oxide in the presence of methane. The results indicate that the yield of the reaction (N20 --> N2 + (1/2)O2) increases when pillared clays are exchanged with transition metals, single-pass conversion rates of >70% being attainable. In particular, when double exchanged (calcium and subsequently copper) alumina pillared montmorillonite/beidellite is used as a catalyst, de-N2O activity reaches a maximum, which is maintained even after 4 h of work at a space velocity of 5.5 h(-1). A mechanism for the reaction is suggested, which implies that N2O is first adsorbed by the catalyst and then decomposes through two different paths: catalyst oxidation and catalyst reduction. Such a redox process explains the kinetic data.     

Carbon monoxide concentration forecasting in Santiago, Chile

In the city of Santiago, Chile, air quality is defined in terms of particulate matter with an aerodynamic diameter < or = 10 microm (PM10) concentrations. An air quality forecasting model based on past concentrations of PM10 and meteorological conditions currently is used by the metropolitan agency for the environment, which allows restrictions to emissions to be imposed in advance. This model, however, fails to forecast between 40 and 50% of the days considered to be harmful for the inhabitants every year. Given that a high correlation between particulate matter and carbon monoxide (CO) concentrations is observed at monitoring stations in the city, a model for CO concentration forecasting would be a useful tool to complement information about expected air quality in the city. Here, the results of a neural network-based model aimed to forecast maximum values of the 8-hr moving average of CO concentrations for the next day are presented. Forecasts from the neural network model are compared with those produced with linear regressions. The neural network model seems to leave more room to adjust free parameters with 1-yr data to predict the following year's values. We have worked with 3 yr of data measured at the monitoring station located in the zone with the worst air quality in the city of Santiago, Chile.     

The effect of seasonality on oxidative metabolism in the sea urchin Loxechinus albus

The objective of the present study was to investigate seasonal variations in the oxidative metabolism of the sea urchin Loxechinus albus gonads. The reported spawning period for this species is from September to November. Lipid radical content showed non-significant changes upon the seasons. Ascorbyl radical content and the content of α-tocopherol were lower in samples collected in spring and summer as compared to the values in winter-collected animals. Ascorbate content decreased in samples collected in fall as compared to those collected in winter. For the lipophilic compartment, the lipid radical content/α-tocopherol content ratio is an indicator of oxidative stress. This index increased significantly in tissues during spawning as compared to the values in samples collected during winter. The ascorbyl content/ascorbate content ratio is an indicator of oxidative stress for the hydrophilic milieu. A significant decrease by 66% was determined in tissues from gonads of animals collected in summer as compared to values in animals collected in winter. The data reported here suggest a different profile of response against oxidative stress at the lipophilic and hydrophilic milieus in L. albus gonads.     

Characterization of bacteria with phenol-oxidase activity from soil in the La Laguna area (Spain)

A total of 168 bacterial strains isolated from soil of the La Laguna area (Tenerife Island, Spain) were characterized and assayed for phenol-oxidase enzymes (as an indicator of lignolytic capability).     

Waterproof and translucent wings at the same time: problems and solutions in butterflies

Although the colour of butterflies attracts the most attention, the waterproofing properties of their wings are also extremely interesting. Most butterfly wings are considered “super-hydrophobic” because the contact angle (CA) with a water drop exceeds 150°. Usually, butterfly wings are covered with strongly overlapping scales; however, in the case of transparent or translucent wings, scale cover is reduced; thus, the hydrophobicity could be affected. Here, we present a comparative analysis of wing hydrophobicity and its dependence on morphology for two species with translucent wings Parantica sita (Nymphalidae) and Parnassius glacialis (Papilionidae). These species have very different life histories: P. sita lives for up to 6 months as an adult and migrates over long distance, whereas P. glacialis lives for less than 1 month and does not migrate. We measured the water CA and analysed wing morphology with scanning electron microscopy and atomic force microscopy. P. sita has super-hydrophobic wing surfaces, with CA > 160°, whereas P. glacialis did not (CA = 100–135°). Specialised scales were found on the translucent portions of P. sita wings. These scales were ovoid and much thinner than common scales, erect at about 30°, and leaving up to 80% of the wing surface uncovered. The underlying bare wing surface had a remarkable pattern of ridges and knobs. P. glacialis also had over 80% of the wing surface uncovered, but the scales were either setae-like or spade-like. The bare surface of the wing had an irregular wavy smooth pattern. We suggest a mode of action that allows this super-hydrophobic effect with an incompletely covered wing surface. The scales bend, but do not collapse, under the pressure of a water droplet, and the elastic recovery of the structure at the borders of the droplet allows a high apparent CA. Thus, P. sita can be translucent without losing its waterproof properties. This characteristic is likely necessary for the long life and migration of this species. This is the first study of some of the effects on the hydrophobicity of translucency through scales’ cover reduction in butterfly wings and on the morphology associated with improved waterproofing. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.