Revaluation of a Soy Protein By-product in Eco-friendly Bioplastics by Extrusion

Journal of Polymers and the Environment - Agri-food waste and by-products are being increasingly revalued, exploiting their potential. One of the attractive alternatives is their use as raw...     

Corona ion induced atmospheric potential gradient perturbations near high voltage power lines

High voltage power lines are known to produce corona ions that can be carried from the line by the wind, progressively attaching to ambient aerosol particles and causing fluctuations in the Earth’s atmospheric potential gradient. A fixed site monitoring station was installed near two power lines, which recorded the potential gradient at 1 s intervals and the ambient weather conditions every 10 min. The station ran continuously from January 2007 to December 2008, accumulating long-term data. Results from 2008 show an increase in potential gradient variability when a wind is blowing across the power lines towards the station, indicating that corona ions may be present in this environment.     

Detection of airborne Legionella while showering using liquid impingement and fluorescent in situ hybridization (FISH)

Aerosols of water contaminated with Legionella bacteria constitute the only mode of exposure for humans. However, the prevention strategy against this pathogenic bacteria risk is managed through the survey of water contamination. No relationship linked the Legionella bacteria water concentration and their airborne abundance. Therefore, new approaches in the field of the metrological aspects of Legionella bioaerosols are required. This study was aimed at testing the main principles for bioaerosol collection (solid impaction, liquid impingement and filtration) and the in situ hybridization (FISH) method, both in laboratory and field assays, with the intention of applying such methodologies for airborne Legionella bacteria detection while showering. An aerosolization chamber was developed to generate controlled and reproducible L. pneumophila aerosols. This tool allowed the identification of the liquid impingement method as the most appropriate one for collecting airborne Legionella bacteria. The culturable fraction of airborne L. pneumophila recovered with the liquid impingement principle was 4 and 700 times higher compared to the impaction and filtration techniques, respectively. Moreover, the concentrations of airborne L. pneumophila in the impinger fluid were on average 7.0 x 10(5) FISH-cells m(-3) air with the fluorescent in situ hybridization (FISH) method versus 9.0 x 10(4) CFU m(-3) air with the culture method. These results, recorded under well-controlled conditions, were confirmed during the field experiments performed on aerosols generated by hot water showers in health institutions. This new approach may provide a more accurate characterization of aerobiocontamination by Legionella bacteria.     

Modifications of the transition flow reactor theory for the more accurate measurement of nitric acid and nitrate and ammonium ions

Sixty five samples were taken with a Transition Flow Reactor (TFR) for the measurement of nitric acid (HNO₃) and nitrate particulates (NO ₃ ⁻ ), in a central Athens street having a heavy traffic density, between February 1989 and February 1990. It was established that the TFR theory overestimated HNO₃ and underestimated NO ₃ ⁻ . This is caused by the retention of a fraction of the NO₂ and a fraction of the HNO₂ as NO ₂ ⁻ on the sampler's nylon linear. NO ₂ ⁻ is in turn oxidized to NO ₃ ⁻ and this is determined as HNO₃. Two modifications of the TFR theory are proposed for a better estimation of the HNO₃ and NO ₃ ⁻ . With the first modification HNO₃ is estimated as being equal to the smaller of two values: HNO_{3 TFR} and the value calculated if it is considered that 91% of HNO₃ is retained by the nylon filter. The second modification was based on the quantification of the effect of NO₂ on the concentrations of HNO₃ and NO ₃ ⁻ . This modification is an improvement on the first one and enables the calculation of a lower limit for the concentration of HNO₂. Both modifications improve the accuracy of the TFR sampler in measuring HNO₃ and NO ₃ ⁻ , without altering it structurally. It was also found that the nylon filter partially retains some NH₃, causing a negative error in the measurement of NH ₄ ⁺ with the TFR. The extent of NH₃ retention on the nylon filter is proportional to the HNO₃ concentration. This error must be taken into account whenever NH ₄ ⁺ is being determined.     

Prospects for repellent in pest control: current developments and future challenges

The overall interest in environmentally safe pest control methods and the rise of insecticide resistance in pest populations have prompted medical and agricultural entomology research on insect repellents in recent years. However, conducting research on repellent is challenging for several reasons: (1) the different repellent phenomena are not well defined; (2) it is difficult to test for and quantify repellent; (3) the physiological mechanisms are poorly known; (4) the field efficacy appears to be highly variable. Here, we identified five different types of repellent: expellency, irritancy, deterrency, odor masking and visual masking, and described behavioral bioassays to differentiate between them. Although these categories are currently defined by their behavioral response to different stimuli, we suggest new definitions based on their mechanism of action. We put forward three main hypotheses on the physiological mechanism: (1) a dose effect that modifies the behavior, (2) a repellent mechanism with specific receptors, or (3) inhibition of the transduction of neural information.     

Fixism and conservation science

The field of biodiversity conservation has recently been criticized as relying on a fixist view of the living world in which existing species constitute at the same time targets of conservation efforts and static states of reference, which is in apparent disagreement with evolutionary dynamics. We reviewed the prominent role of species as conservation units and the common benchmark approach to conservation that aims to use past biodiversity as a reference to conserve current biodiversity. We found that the species approach is justified by the discrepancy between the time scales of macroevolution and human influence and that biodiversity benchmarks are based on reference processes rather than fixed reference states. Overall, we argue that the ethical and theoretical frameworks underlying conservation research are based on macroevolutionary processes, such as extinction dynamics. Current species, phylogenetic, community, and functional conservation approaches constitute short‐term responses to short‐term human effects on these reference processes, and these approaches are consistent with evolutionary principles.