COMPARISON OF TWO ANALYTICAL METHODS FOR THE DETERMINATION OF AZAARENES IN ATMOSPHERIC PARTICULATE MATTER

In this paper, the development of an analytical method for the separation and quantification of 20 azaarenes is described. Two methods are compared: high performance liquid chromatography with fluorescence detection (HPLC-fluorescence) and gas chromatography with mass spectrometry detection (GC-MS).

Although HPLC-fluorescence was proven to be the most sensitive method, GC-MS was selected in particular for the efficiency of the separation of the 20 azaarenes. The detection limits of the HPLC-fluorescence and GC-MS methods varied between 0.04 μ g.L^?1 (dibenz[a,c]acridine) and 1.30 μ g.L ^?1 (acridine) and between 1.50 μ g.L ^?1 (benz[c]acridine) and 2.56 μ g.L ^?1 (dibenz[a,c]acridine) respectively.

The GC-MS method was applied to particulate matter (PM ₁₀ ) samples collected over 48–72 h periods between April 2006 and February 2007 in Strasbourg (East of France). Before analysis aerosol samples were Soxhlet extracted and concentrated to a final volume of about 1 mL of hexane.

The seasonally mean concentrations of all azaarenes for this urban site have shown a seasonal variation in which the maximum concentration occurred in the winter (6.0 ng.m ³ ) and the minimum in the summer (0.90 ng.m³). For all the seasons the 2 rings species were the predominant azaarenes while the > 4 rings species were the less abundant.     

The distribution of lithium intercalated in V2O5 thin films studied by XPS and ToF-SIMS

The distribution of lithium in V₂O₅/V lower oxide duplex thin films prepared by thermal oxidation of V metal was analysed by XPS and ToF-SIMS after intercalation at 2.8 V versus Li/Li⁺ and de-intercalation at 3.8 V following cycling between 3.8 and 2.8 V in 1 M LiClO₄-PC. XPS analysis of the intercalated thin film evidenced a partial reduction (43 at.% V⁴⁺) of the V₂O₅ surface, the modification of its electronic structure and the presence of Li, consistent with the formation of the δ-Li_xV₂O₅ (0.9 ≤ x ≤ 1) phase. The Li in-depth distribution measured by ToF-SIMS shows a maximum in the outer layer of V₂O₅, but Li is also found at the oxide film/metal substrate interface indicating its diffusion across the inner layer of V lower oxides. The analyses performed after de-intercalation on the samples cycled 12, 120 and 300 times reveal the effect of aging on the trapping of lithium. A significant reduction (17-22 at.% V⁴⁺) of the V₂O₅ surface was measured after 300 cycles. The Li in-depth distribution shows a maximum at the interface between the outer layer of V₂O₅ and the inner layer of lower oxides. Aging favours the accumulation of lithium at this interface with a resulting enlarged distribution enriching the sub-surface of the outer layer of V₂O₅ and the inner layer of lower oxides after 300 cycles. Lithium is also found, but in smaller quantities, at the oxide film/metal substrate interface. Measurements performed in the non-electrochemically treated surface areas of the de-intercalated samples revealed the same type of modifications, evidencing the diffusion of lithium along the interfaces where it is trapped.     

Functionalization of Polymer Surfaces Using Excimer VUV Systems and Silent Discharges. Application to Electroless Metallization

New approaches for electroless plating of nonconductive polymers or polymer-based materials are described. In this work, polyimide substrates were surface-functionalized (i) in nitrogenated (ammonia at reduced pressure) and oxygenated (air at atmospheric pressure) atmospheres under assistance of vacuum-ultraviolet (VUV) irradiation (use of a xenon silent discharge excimer source) or (ii) directly in air at atmospheric pressure using a dielectric-barrier discharge (DBD) device. After functionalization, the substrates were “activated” by dipping in a dilute acidic PdCl₂ solution or by spin-coating of a thin metal-organic film (from a solution of palladium acetate (PdAc) in chloroform). The catalytic activity of the so-deposited palladium species toward the electroless deposition of nickel was studied before and after a VUV post-irradiation (in air at atmospheric or reduced pressure) with a view to understanding better the role of the reducer (sodium hypophosphite) within the electroless bath.

This work confirms the specific interest of grafting nitrogenated functionalities onto polymer surfaces for attaching covalently the palladium-based catalyst (in particular in the case of the PdCl₂ route), forming thus strong Pd - N - C bonds at the metal/polymer interface. This results from the strong chemical affinity of palladium toward nitrogen. On the other hand, when oxygenated functionalities are surface-grafted, the conventional two-step procedure using SnCl₂ and PdCl₂ solutions can be proposed due to the strong chemical affinity of tin toward oxygen. The Ni deposits obtained under these different conditions pass the standard Scotch^®-tape test and, therefore, exhibit a good practical adhesion. For this same purpose, it is interesting to note that the DBD treatment operating in air at atmospheric pressure causes an increase of the surface roughness and, therefore, an improvement in adhesion of metallic films when their initiation is catalyzed through the PdAc route. In addition, this work demonstrates that extensive research still has to be performed to understand and improve the Ni/polymer adhesion when the PdAc route associated with a VUV irradiation is considered.     

Awareness of coeliac disease and the gluten status of ‘gluten‐free’ food obtained on request in catering outlets in Ireland

The only current effective treatment for coeliac disease (CD) is a lifelong diet that is as free from gluten as possible. This study provides baseline evidence to inform future interventions of benefit to CD sufferers by examining awareness of CD issues by food servers and preparation staff, assessing their claims to provide gluten‐free foods by analysis of a meal concurrently sampled. While the majority of attempts to purchase a ‘gluten‐free’ meal on request in restaurants were successful, some 10% of all samples contained gluten, 2.7% between 21 and 100 mg kg^?1, and 7.7% >100 mg kg^?1 and two unsatisfactory samples were purchased from so‐called coeliac‐friendly restaurants. These findings were consistent with those obtained previously by Collin et al. [Alimentary Pharmacology & Therapeutics 19 (2004) 1277], Størsrud et al. [European Food Research & Technology 217 (2003) 481], Gélinas et al. [International Journal of Food Science & Technology 43 (2008) 1245] for cross contamination with gluten. Staff confidence, ‘gluten‐free’ notices, signs and menu choices were no guarantee of risk‐free dining for CD sufferers. Based on our findings we suggest the need for further training, specifically for chefs and managers.     

Learning directed probabilistic logical models: ordering-search versus structure-search

We discuss how to learn non-recursive directed probabilistic logical models from relational data. This problem has been tackled before by upgrading the structure-search algorithm initially proposed for Bayesian networks. In this paper we show how to upgrade another algorithm for learning Bayesian networks, namely ordering-search. For Bayesian networks, ordering-search was found to work better than structure-search. It is non-obvious that these results carry over to the relational case, however, since there ordering-search needs to be implemented quite differently. Hence, we perform an experimental comparison of these upgraded algorithms on four relational domains. We conclude that also in the relational case ordering-search is competitive with structure-search in terms of quality of the learned models, while ordering-search is significantly faster.     

Chemotaxis Disruption in Pratylenchus Scribneri by Tall Fescue Root Extracts and Alkaloids

Tall fescue (Festuca arundinacea) forms a symbiotic relationship with the clavicipitalean fungal endophyte Neotyphodium coenophialum. Endophyte-infected grass is tolerant to nematode, but the factors responsible are unknown. One objective of this work was to determine if root extracts of tall fescue effected chemoreceptor activity of Pratylenchus scribneri by using an in vitro chemoreception bioassay. Another objective was to determine if specific ergot alkaloids (ergovaline, ergotamine, a-ergocryptine, ergonovine), and loline alkaloids, all produced by the fungal endophyte, altered chemotaxis with this bioassay. Methanolic extract from roots altered chemotaxis activities in this nematode but only from roots of plants cultured 45 ≥ d, which repelled nematodes. Extracts prepared from noninfected grasses were attractants. This assay indicated that the alkaloids were either repellents or attractants. N-formylloline was an attractant at concentrations of 20 μg/ml and lower, while at higher concentrations it was a repellent. Ergovaline, the major ergot alkaloid produced by the endophyte, was repellent at both high and low concentrations and caused complete death of the nematodes.     

Effect of lactobacilli inoculation on cassava (Manihot esculenta) silage: Fermentation pattern and kinetic analysis

The major effect of Lactobacillus inoculation on laboratory cassava (Manihot esculenta Crantz) silage was a change from a heterofermentative pattern observed in natural silage to a homofermentation. Small amounts of starter culture (1% v/w) were required to produce a high level of lactic acid (> 28 g kg^?1 DM) and to reach a pH of at least 4. The Gompertz model was used to evaluate the effect of inoculation level on the lactic formation based on kinetic criteria. Also an empirical pH lactic acid correlation was proposed to monitor the progress of ensiling, based solely on pH measurements. The simulation model may be used to improve guidelines for silo safety and to evaluate the effect of lactobacilli inoculants.     

Evaluation of FFT-Based and Moder Parametrc Methods for the Spectral Analysis of Bioprosthetic Valve Sounds

The objective of this paper is to compare the performance of conventional FFT-based (basic periodogram and Welch's method) and modern parametric (all-pole and pole-zero modeling) methods in estimating the spectral distribution of cardiac bioprosthetic valve sounds, and for the extraction of the two most dominant frequency peaks (DFP). These methods were tested for stability by adding random noise and truncating the bioprosthetic valve closing sounds, and for reproducibility by measuring the variance of the spectra obtained from three consecutive recordings of each patient. Results from a group of 11 patients show that the basic periodogram and Steiglitz-McBride's method with maximum entropy (pole-zero modeling) provide the most consistent (minimal variance) estimates of the DFP's of the closing sounds. However, for estimating spectral distributions, the most stable methods appear to be the basic periodogram and Steiglitz-McBride's method with extrapolation to zero. The basic periodogram appears to be the best compromise to estimate both the spectral distribution and the DFP's of the bioprosthetic closing sounds.     

Oxygen Vacancy Relaxation and Domain Wall Hysteresis Motion in Cobalt-Doped Barium Titanate Ceramics

Mechanical and dielectric loss measurements were carried out in the BaTiO₃ ceramics doped with Co at frequencies between 0.01 Hz and 1 MHz as a function of temperature from −150° to 150°C. The relaxation peak observed in the ferroelectric phase with an activation energy of 0.27 eV is assumed to be related to the motion of oxygen vacancies. This peak could be because of the reorientation of an electrical dipole made of oxygen vacancies and Co³⁺ ions in the lattice. Furthermore, another loss peak located just below the Curie temperature T _c could be interpreted as hysteretic motion of the domain walls in a regime where the domain wall density is changing.