Comparison of gas chromatography-based approaches after fast miniaturised sample preparation for the monitoring of selected pesticide classes in fruits

The feasibility of a miniaturised generic sample preparation method based on matrix solid-phase dispersion for the determination of three relevant classes of pesticides (organophosphorus pesticides, triazines and pyrethroids) in selected fruits, i.e. orange, apple, pear and grape, have been demonstrated. Satisfactory results were obtained with gas chromatography coupled to mass spectrometry with recoveries of 78–113% in orange, 62–102% in grape, 71–116% in apple and 91–110% in pear, and reproducibilities in general below 20%. The feasibility of simultaneous separation of the three families of pesticides by comprehensive two-dimensional gas chromatography with micro-electro-capture detector was also evaluated. Columns with different polarity and selectivity, including ZB-5, HT-8 and DB-17, were assayed as first dimension and combined with columns of increasing polarity in the second dimension, i.e. HT-8, BPX-50 and Supelcowax-10. The best results for real-life samples after treatment by the proposed miniaturised method were achieved with ZB-5 × BPX-50 column combination. The low limits of detection achieved with this technique (in general, below 0.56 μg/kg) proved its suitability for accurate monitoring of the pesticides classes included in the study at the maximum residue levels set in the European Union.     

Erratum to: “Multiple critical points of perturbed symmetric strongly indefinite functionals” [http://dx.doi.org/10.1016/j.anihpc.2008.06.002]

We correct the statement and the proof of Proposition 9 in [D. Bonheure, M. Ramos, Multiple critical points of perturbed symmetric strongly indefinite functionals, http://dx.doi.org/10.1016/j.anihpc.2008.06.002].     

Gas‐phase fragmentation of protonated C60‐pyrimidine derivatives

Electrospray ionization mass spectrometry/mass spectrometry (ESI/MS/MS) and multiple stage mass spectrometry (MSⁿ, n > 2) were used in the positive ion mode, with two different types of mass spectrometers, a quadrupole time‐of‐flight and an ion trap, to characterize two sets of different types of C₆₀‐aminopyrimidine exohedral derivatives. In one set, the pyrimidine moiety bears an amino acid methyl ester residue, and in the other the pyrimidine ring is part of a nucleoside‐type moiety, the latter existing as two separated diastereoisomers. We have found that retro‐cycloaddition processes occur for the closed shell protonated species formed by electrospraying C₆₀ derivatives synthesized by Diels–Alder reactions, whereas for the C₆₀ derivatives synthesized via 1,3‐dipolar cycloadditions, these processes did not occur. Formation of diagnostic ions allowed the differentiation between the two groups of fullerene derivatives, and between the diastereoisomers of C₆₀ derivatives with a nucleoside‐type moiety. In general, the fragmentation processes are strongly dependent on the protonation sites and on the structure of the exohedral moieties. Copyright © 2009 John Wiley & Sons, Ltd.     

Micro‐Raman spectroscopy of decorated pottery from the Iberian archaeological site of Puente Tablas (Jaén,Spain, 7th–4th century B.C.)

In this paper, Raman spectroscopy is used for the first time to identify the pigments on decorated antique Iberian pottery. Ceramic fragments of type Real and others from the archaeological excavation in the oppidum Puente Tablas were examined. Different types of iron oxide pigments (hematite and goethite) were identified, along with amorphous carbon. In some samples, the presence of chalk or gypsum could be demonstrated. Some unattributed Raman bands are believed to be associated either with post‐burial organic deposition or with silicate materials that are present in red ochre. It was possible to relate the findings with geological data from the region and to make assumptions on a local production. Copyright © 2009 John Wiley & Sons, Ltd.     

Geodesic length spectrum on compact Riemann surfaces

In this paper we use techniques linking combinatorial structures (symbolic dynamics) and algebraic–geometric structures to study the variation of the geodesic length spectrum, with the Fenchel–Nielsen coordinates, which parametrize the surface of genus τ=2$\tau =2$. We explicitly compute length spectra, for all closed orientable hyperbolic genus two surfaces, identifying the exponential growth rate and the first terms of a growth series.     

Charmed hadrons in nuclear medium

We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner.We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions.We discuss the implications of the in-medium properties of open-charm mesons on the D s0 （2317） and the predicted X（3700） scalar resonances.     

Charmed hadrons in nuclear medium

We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the DsO(2317) and the predicted X(3700) scalar resonances.     

Invariant classification and the generalised invariant formalism: conformally flat pure radiation metrics

Metrics obtained by integrating within the generalised invariant formalism are structured around their intrinsic coordinates, and this considerably simplifies their invariant classification and symmetry analysis. We illustrate this by presenting a simple and transparent complete invariant classification of the conformally flat pure radiation metrics (except plane waves) in such intrinsic coordinates; in particular we confirm that the three apparently non-redundant functions of one variable are genuinely non-redundant, and easily identify the subclasses which admit a Killing and/or a homothetic Killing vector. Most of our results agree with the earlier classification carried out by Skea in the different Koutras–McIntosh coordinates, which required much more involved calculations; but there are some subtle differences. Therefore, we also rework the classification in the Koutras–McIntosh coordinates, and by paying attention to some of the subtleties involving arbitrary functions, we obtain complete agreement with the results obtained in intrinsic coordinates. We have corrected and completed statements and results by Edgar and Vickers, and by Skea, about the orders of Cartan invariants at which particular information becomes available.