A methodology for applying Taxonomic Sufficiency and benthic biotic indices in two Mediterranean areas

Biotic indices have been developed to summarise information provided by benthic macroinvertebrates, but their use can require specialized taxonomic expertise as well as a time-consuming operation. Using high taxonomic level in biotic indices reduces sampling processing time but should be considered with caution, since assigning tolerance level to high taxonomic levels may cause uncertainty. A methodology for family level tolerance categorization based on the affinity of each family with disturbed or undisturbed conditions was employed. This family tolerance classification approach was tested in two different areas from Mediterranean Sea affected by sewage discharges. Biotic indices employed at family level responded correctly to sewage presence. However, in areas with different communities among stations and high diversity of species within each family, assigning the same tolerance level to a whole family could imply mistakes. Thus, use of high taxonomic level in biotic indices should be only restricted to areas where homogeneous community is presented and families across sites have similar species composition.

Spin degree of freedom in two dimensional exciton condensates

We present a theoretical analysis of a spin-dependent multicomponent condensate in two dimensions. The case of a condensate of resonantly photoexcited excitons having two different spin orientations is studied in detail. The energy and the chemical potentials of this system depend strongly on the spin polarization. When electrons and holes are located in two different planes, the condensate can be either totally spin polarized or spin unpolarized, a property that is measurable. The phase diagram in terms of the total density and electron-hole separation is discussed.

SERS Active Surface in Two Steps, Patterning and Metallization

Robust and reproducible metallized nano/microstructured surfaces of polymeric surfaces have been successfully prepared by direct laser interference patterning (DLIP) of commercial polymeric films followed by sputtering of metallic thin films. The SERS spectra for 2-thioaniline adsorbed on a structured polycarbonate surfaces covered with a gold or platinum film showed a ca. three order of magnitude enhancement over a flat surface with the same metal film. The method here reported is suitable for mass production of substrates for SERS since large areas (several cm2) can be structured in ca. 1–5 s.

Evolution of extracellular polymeric substances produced in two submerged membrane bioreactors working at high sludge age

This research paper deals with the evolution of the extracellular polymeric substances (EPS) produced in the mixed liquor of two 25 L bench-scale membrane bioreactors (MBRs), with micro (MF-MBR) and ultrafiltration (UF-MBR) submerged membranes. The conclusion focuses on the relationship between the operation and how EPS respond, demonstrating that significant changes in EPS concentration were commonly observed when abrupt changes in the operational conditions took place. Bound EPS (EPSb) showed moderate positive statistical correlations with sludge age and MLSS for the two MBRs. Soluble EPS (EPSs), on the other hand, showed a moderate negative statistical correlation between EPSs with the two parameters analyzed for MF-MBR and no correlation with the UF-MBR was found. With respect to the composition of EPS, EPSb were mostly made up of proteins (44–46%) whereas in EPSs, the three components (proteins, carbohydrates, and humic substances) appeared in approximately the same proportion. The statistical analysis exhibited strong positive correlations between EPSb and their constituents, however for EPSs, the correlation was strong only with carbohydrates and moderate with humic substances.

Chemical diversity and potential biological functions of the pygidial gland secretions in two species of Neotropical dung roller beetles

Dung roller beetles of the genus Canthon (Coleoptera: Scarabaeinae) emit an odorous secretion from a pair of pygidial glands. To investigate the chemical composition of these secretions, we used stir bar sorptive extraction (SBSE), coupled with gas chromatography–mass spectrometry (GC–MS) for analysis of extracts of pygidial gland secretions secreted by the dung roller beetles Canthon femoralis femoralis and Canthon cyanellus cyanellus. Chemical analyses of volatiles collected from pygidial gland secretions comprise a great diversity of the functional groups. Chemical profile comparisons showed high intra- and interspecific variability. The pygidial gland secretion of Canthon f. femoralis was dominated by sesquiterpene hydrocarbons, whereas the profile of Canthon c. cyanellus was dominated by carboxylic acids. The different pygidial secretions have a high diversity of chemical compounds suggesting a multifunctional nature involving some key functions in the biology. We discuss the biological potential of these compounds found in the pygidial glands of each species with respect to their ecological and behavioral relevance.