Optimization of pressurized liquid extraction using a multivariate chemometric approach and comparison of solid phase extraction cleanup steps for the determination of polycyclic aromatic hydrocarbons in mosses

A factorial design was used to optimize the extraction of polycyclic aromatic hydrocarbons (PAHs) from mosses, plants used as biomonitors of air pollution. The analytical procedure consists of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) cleanup, in association with analysis by high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD). For method development, homogeneous samples were prepared with large quantities of the mosses Isothecium myosuroides Brid. and Hypnum cupressiforme Hedw., collected from a Spanish Nature Reserve. A factorial design was used to identify the optimal PLE operational conditions: 2 static cycles of 5 min at 80°C. The analytical procedure performed with PLE showed similar recoveries (∼70%) and total PAH concentrations (∼200 ng g-1) as found using Soxtec extraction, with the advantage of reducing solvent consumption by 3 (30 mL against 100 mL per sample), and taking a fifth of the time (24 samples extracted automatically in 8 h against 2 samples in 3.5 h). The performance of SPE normal phases (NH2, Florisil®, silica and activated aluminium) generally used for organic matrix cleanup was also compared. Florisil® appeared to be the most selective phase and ensured the highest PAH recoveries. The optimal analytical procedure was validated with a reference material and applied to moss samples from a remote Spanish site in order to determine spatial and inter-species variability

Panel of resonators with variable resonance frequency for noise control

The article focuses on acoustic resonators made of perforated sheets bonded onto honeycomb cavities. This kind of resonators can be used in adverse conditions such as high temperature, dirt and mechanical constraints. For all these reasons, they are, for example, widely used in aeronautic applications. The acoustic properties are directly linked to the size, shape and porosity of holes and to the thickness of air gaps. Unfortunately, the acoustic absorption of these resonators is selective in frequency and conventional acoustic resonators are only well adapted to tonal noises. In case of variable tonal noise, the efficiency is limited if the resonators are not tunable. One common solution is to control the depth of cavities based on the noise to be attenuated. This article proposes another technology of tunable resonators with only a very small mass and size increase. It consists of two superposed and identically perforated plates associated with cavities. One plate is fixed and bonded to the cavities and the other plate is mobile. The present concept enables to change the internal shapes of the holes of the perforated layers. The article describes this system and gives a theoretical model of the normal incidence acoustic impedance that allows to predict the acoustic behavior, in particular the resonance frequency. The model shows that the resonance frequency varies with hole profiles and that the absorption peak moves towards the lower frequencies. The proposed model is validated by measurements on various configurations of resonators tested in an impedance tube. The perspectives of this work are to adapt the hole profiles using an actuator in order to perform active control of impedance

The impact of reduction in the benzene limit value in gasoline on airborne benzene, toluene and xylenes levels

Background benzene, toluene, xylenes (BTX) average concentrations have been measured over the urban agglomeration of Toulouse, France, during both springtime and summer periods of 1999 and 2001. The benzene average amount over the two Toulouse campaigns in 1999 is equal to 2.2 Ag/m³, very close to the French air quality standard and well under the average value of 5 Ag/m³ recommended by European Economic Community countries, recognising that those regulations are given for a whole year. BTX pollution over Toulouse has, in particular, been produced by motor vehicle exhaust gases. For the study conducted during the same periods of 2001, benzene concentrations were within the French quality value in the whole area. This is because the benzene limit value contained in gasoline went from 5% to 1% since 2000 January 1. It will be important to measure benzene over annual periods in order to know its exact values over such a period and to observe its potential seasonal variations

Referentiality and normativity in trainee teachers’ activity when viewing videos of teaching: trends in video-enhanced education and professional development

International audienceAs shown by Gaudin and Chaliès (2015), researches conducted in recent years in the field of video-enhanced teacher education and professional development mainly focus on identifying (i) the effects of different types of video (e.g. "best practices" vs “typical practices”), (ii) the identity or status of the teacher videoed and of the teacher viewing (self vs others, peers vs experts) and (iii) the influence of video viewing on teachers' ability to notice and interpret relevant features to analyze classroom situations, in order to develop knowledge-based reasoning and/or a "professional vision". On one hand, these researches produced a strong evidence basis about the links and relations between different instructional settings and different learning outcomes. On the other hand, their theoretical and empirical variety seems to be an obstacle for a compelling scientific advance (Flandin, 2015). Therefore we think that the field needs to investigate more generic issues, such as (i) the nature of teachers experience and cognitive activity in video-enhanced educational situations, (ii) the conceptual and methodological means and tools to describe and analyze the instructional potential of such experiences, and (iii) the principles and criteria that can be derived to design evidence-based learning environments and instructional programs. Therefore this symposium aims to gather empirical studies conducted in this promising and under-rated research areas in order to share and discuss new evidence, to try to derive robust instructional proposals, nay to draw some innovative research perspectives

Mobilizing heads and hearts for wildlife conservation

Highlighting the shared evolutionary relationships between humans and animals — and recognizing that all species, including humans, are unique in their own way — may facilitate caring for and conserving animals by tapping into a human emotion: empathy

Mobilizing heads and hearts for wildlife conservation

Highlighting the shared evolutionary relationships between humans and animals — and recognizing that all species, including humans, are unique in their own way — may facilitate caring for and conserving animals by tapping into a human emotion: empathy

Reconstructing historical trends of polycyclic aromatic hydrocarbon deposition in a remote area of Spain using herbarium moss material

Herbarium mosses from 1879-1881, 1973-1975 and 2006-2007 were used to investigate the historical changes of atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) at a remote site located in Northern Spain. Natural abundance of nitrogen and carbon isotopes was also measured in order to assess the evolution of emissions from anthropogenic sources. Nitrogen concentrations, 13C, 13N and PAH levels were significantly higher in 19th century samples with respect to the present century samples. Moreover, PAH distribution varied over the centuries, following a tendency of light PAH enrichment. The carbon, nitrogen and PAH levels measured in the mosses tally with the historic evolution of anthropogenic emissions in the area, mainly influenced by changes of economic activities, domestic heating and road traffic density. Mosses provided by herbaria seem to offer the possibility to study long-term temporal evolution of atmospheric PAH deposition

Dynamic Filtering of Useless Data in an Adaptive Multi-Agent System : Evaluation in the Ambient Domain

National audienceAmadeus is an Adaptive Multi-Agent System whose goal is to observe and to learn users’ behaviour in an ambient system in order to perform their recurrent actions on their behalf. Considering the large number of devices (data sources) that generally compose ambient systems, performing an efficient learning in such a domain requires filtering useless data. This paper focuses on an extended version of Amadeus taking account this requirement and proposes a solution based on cooperative interactions between the different agents composing Amadeus. An evaluation of the performances of our system as well as the encouraging obtained results are then shown

Sonic interaction with a virtual orchestra of factory machinery

This paper presents an immersive application where users receive sound and visual feedbacks on their interactions with a virtual environment. In this application, the users play the part of conductors of an orchestra of factory machines since each of their actions on interaction devices triggers a pair of visual and audio responses. Audio stimuli were spatialized around the listener. The application was exhibited during the 2013 Science and Music day and designed to be used in a large immersive system with head tracking, shutter glasses and a 10.2 loudspeaker configuration.Comment: Sonic Interaction for Virtual Environments, Minneapolis : United States (2014

Matrix-Matching as an Improvement Strategy for the Detection of Pesticide Residues

More than 90% of the pesticides residues in apples are located in the peel. We developed a gas chromatography/ion trap tandem mass spectrometry method for investigating all detectable residues in the peel of 3 apple varieties. Sample preparation is based on the use of the Quick Easy Cheap Effective Rugged and Safe method on the whole fruit, the flesh, and the peel. Pesticide residues were quantified with solvent‐matched and matrix‐matched standards, by spiking apple sample extracts. Matrix effects dependent on the type of extract (fruit, flesh, or peel) and the apple variety were detected. The best data processing methods involved normalizing matrix effect rates by matrix‐matched internal/external calibration. Boscalid, captan, chlorpyrifos, fludioxonil, and pyraclostrobin were the most frequently detected pesticides. However, their concentrations in the whole fruit were below European maximum residue levels. Despite negative matrix effects, the residues in peel were detected at concentrations up to 10 times higher than those in whole fruits. Consequently, other pesticide residues present at concentrations below the limit of quantification in the whole fruit were detected in the peel