Behavioural Evidence and Chemical Identification of a Female Sex Pheromone in Anagrus atomus (Hymenoptera: Mymaridae)

Journal of Chemical Ecology - Anagrus atomus (L.) is an egg parasitoid involved in the biological control of Empoasca vitis (Göthe) in vineyards. Sex pheromones play a crucial role in mate...     

Risk factors for causing road crashes involving cyclists: An application of a quasi-induced exposure method

A quasi-induced exposure approach was applied to the Spanish Register of Traffic Crashes to identify driver- and vehicle-related factors associated with the risk of causing a road crash involving a cyclist in Spain from 1993 to 2009. We analyzed 19,007 collisions between a bicycle and another vehicle in which only one of the drivers committed an infraction, and 13,540 records that included the group of non-infractor cyclists in the above collisions plus cyclists involved in single-bicycle crashes. Adjusted odds ratios were calculated for being responsible for each type of crash for each factor considered. Age from 10 to 19 years, male sex, alcohol or drug consumption and non-helmet use were cyclist-related variables associated with a higher risk of crash, whereas cycling more than 1 h increased only the risk of single crashes. Bicycles with brake defects and ridden by two occupants were also at higher risk of involvement in a crash, whereas light defects were associated only with collisions with another vehicle. For drivers of the other vehicle, age more than 60 years, alcohol, not using safety devices and nonprofessional drivers were at higher risk. The risk of colliding with a bicycle was higher for mopeds than for passenger cars.     

Geometric models for measuring sediment wedge volume in retention check dams

Check dams play an important role worldwide in sediment retention, although their effectiveness is currently the subject of debate. In this study, 11 geometric models with their field methodology and equations are proposed to estimate the retained sediment quickly, easily and with a sufficient degree of approximation. The models were applied to a sample of check dams in the Saldaña badlands (Spain) in accordance with the shape of the valley to determine the volume of retained sediment and compare them with other widely used methods. Our geometric method gave lower volumes than topographic methods, but higher volumes than simple methods. This method is thus useful as a first approximation to estimate the sediment trapped by check dams and small silted dams, minimizing fieldwork, calculations and cost. Furthermore, it allows the selection of a better fit to the sediment wedge shape and higher accuracy than the simple methods used until now.     

Perturbation of an arctic soil microbial community by metal nanoparticles

Technological advances allowing routine nanoparticle (NP) manufacture have enabled their use in electronic equipment, foods, clothing and medical devices. Although some NPs have antibacterial activity, little is known about their environmental impact and there is no information on the influence of NPs on soil in the possibly vulnerable ecosystems of polar regions. The potential toxicity of 0.066% silver, copper or silica NPs on a high latitude (>78°N) soil was determined using community level physiological profiles (CLPP), fatty acid methyl ester (FAME) assays and DNA analysis, including sequencing and denaturing gradient gel electrophoresis (DGGE). The results of these different investigations were amalgamated in order to develop a community toxicity indicator, which revealed that of the three NPs examined, silver NPs could be classified as highly toxic to these arctic consortia. Subsequent culture-based studies confirmed that one of the community-identified plant-associating bacteria, Bradyrhizobium canariense, appeared to have a marked sensitivity to silver NPs. Thus, NP contamination of arctic soils particularly by silver NPs is a concern and procedures for mitigation and remediation of such pollution should be a priority for investigation.     

SiO2–K2O–MgO vitreous films doped with erbium and silver nanoparticles for optical applications

The search of new glass compositions for films produced with high optical transparency throughout the visible spectrum from 0.5 μm to the near infrared region is important for optical integrated applications. In this work, we present the preparation of SiO₂–K₂O–MgO vitreous sol–gel films on SiO₂ substrates co-doped with Er³⁺ and Ag nanoparticles. The silver quantum dots were synthesized in continuous media (ex situ) by chemical reduction and isolation from media by anchoring chemical solution-compatible modifiers (aminosilanes) on their surfaces; then, they were successfully integrated into the glass matrix. We present the study of the preparation process and characterization of sol–gel matrices doped with Ag⁰ nanoparticles and Er³⁺, analyzing the role of synthesis parameters and optical properties, and comparing them with other wave-guide compositions, such as PLZT and SiO₂–B₂O₃.     

Conditions that regulate the growth of moulds inoculated into bottled mineral water

The influence of different storage conditions (temperature, illumination, brand of mineral water and storage time) on growth of mould spores was studied. Alternaria alternata, Penicillium citrinum and Cladosporium cladosporioides spores were inoculated in bottles of mineral and mineralised water, packaged in polyethylene terephtalate (PET). The bottles were incubated under different storage conditions. The strains had been isolated from bottled mineral water in a previous study. Storage time was the parameter that had the most important influence in mould growth. The spores grew into visible colonies after 5 month of incubation in bottles just filled, and in a month in bottles that had been stored for 5 month. This could be due to the migration of compounds from PET packaging material into mineral water. This compounds could be used as nutrients (organic matter) for mould growth. The plasticizer additive di-n-butyl phthalate (DBP) concentration in recently bottled mineral water and in 5-month stored bottles was measured. An increase of 20% of DBP concentration was observed. A. alternata and P. citrinum strains were toxicological characterised. Both strains produced mycotoxins in vitro, and P. citrinum produced citrinin in mineral water, posing a potential health risk for consumers.     

Monte Carlo calculations applied to the parametrical studies in a whole body counter

The use of a Monte Carlo code for the analysis and interpretation of whole body counting measurements is described. The sources of error are analysed and commented to show how a counting geometry can be improved by improving accuracy and precision in a measurement. The effects of body size, contamination distribution and counting geometry are also parameters which can be easily used to improve the quality of a body burden assessment. The optimisation of the detector (position, shielding, shape and size) is also commented on the basis of calculations in the photon energy range usually encountered in routine measurements. The results obtained from these simulations are confirmed by experimental results.     

Growth of highly ordered colloidal photonic crystals using a modeling approach

Colloidal photonic crystals were grown using a vertical deposition method. The effect of colloidal concentration and deposition rate on crystalline quality and domain size was studied by means of response surface design. The crystalline quality was assessed using the optical reflectance. The results show that a strong negative correlation exists between the reflectance and the full width at half-maximum (FWHM), as illustrated by the close optimal region between maximizing reflectance and minimizing FWHM. For reflectance and FWHM, the quadratic effect of colloidal concentration is highly significant. For domain size, the colloidal concentration-lifting speed interaction effect was found to be significant. The observed colloidal concentration-lifting speed interaction effect explains the controversy that a low deposition rate is desirable at low colloidal concentrations, whereas a high deposition rate is favorable at high colloidal concentrations. Predictive models relating the important factors to the reflectance, FWHM, and domain size are proposed in the paper. The resulting optimal recipe shows a well-ordered structure with good optical reflectance, consistent with the prediction from modeling.     

Smart hydrogel particles: biomarker harvesting: one-step affinity purification, size exclusion, and protection against degradation

Disease-associated blood biomarkers exist in exceedingly low concentrations within complex mixtures of high-abundance proteins such as albumin. We have introduced an affinity bait molecule into N-isopropylacrylamide to produce a particle that will perform three independent functions within minutes, in one step, in solution: (a) molecular size sieving, (b) affinity capture of all solution-phase target molecules, and (c) complete protection of harvested proteins from enzymatic degradation. The captured analytes can be readily electroeluted for analysis.