Transport of small anionic and neutral solutes through chitosan membranes: Dependence on cross-linking and chelation of divalent cations

Chitosan membranes were prepared by solvent casting and cross-linked with glutaraldehyde at several ratios under homogeneous conditions. The cross-linking degree, varying from 0 to 20%, is defined as the ratio between the total aldehyde groups and the amine groups of chitosan. Permeability experiments were conducted using a side-by-side diffusion cell to determine the flux of small molecules of similar size but with different chemical moieties, either ionized (benzoic acid, salicylic acid, and phthalic acid) or neutral (2-phenylethanol) at physiological pH. The permeability of the different model molecules revealed to be dependent on the affinity of those structurally similar molecules to chitosan. The permeability of the salicylate anion was significantly enhanced by the presence of metal cations commonly present in biological fluids, such as calcium and magnesium, but remained unchanged for the neutral 2-phenylethanol. This effect could be explained by the chelation of metal cations on the amine groups of chitosan, which increased the partition coefficient. The cross-linking degree was also correlated with the permeability and partition coefficient. The change in the permeation properties of chitosan to anionic solutes in the presence of these metallic cations is an important result and should be taken into consideration when trying to make in vitro predictions of the drug release from chitosan-based controlled release systems

Defining the importance of landscape metrics for large branchiopod biodiversity and conservation: the case of the Iberian Peninsula and Balearic Islands

The deficiency in the distributional data of invertebrate taxa is one of the major impediments acting on the bias towards the low awareness of its conservation status. The present study sets a basic framework to understand the large branchiopods distribution in the Iberian Peninsula and Balearic Islands. Since the extensive surveys performed in the late 1980s, no more studies existed updating the information for the whole studied area. The present study fills the gap, gathering together all available information on large branchiopods distribution since 1995, and analysing the effect of human population density and several landscape characteristics on their distribution, taking into consideration different spatial scales (100 m, 1 km and 10 km). In overall, 28 large branchiopod taxa (17 anostracans, 7 notostracans and 4 spinicaudatans) are known to occur in the area. Approximately 30% of the sites hosted multiple species, with a maximum of 6 species. Significant positive co-occurring species pairs were found clustered together, forming 4 different associations of large branchiopod species. In general, species clustered in the same group showed similar responses to analysed landscape characteristics, usually showing a better fit at higher spatial scales.Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq [401045/2014-5]Spanish Ministry of Education, Culture and Sport [FPU014/06783]info:eu-repo/semantics/publishedVersio

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected

Experimental and numerical non-destructive study of defect in concrete

This paper verifies the reliability of the numerical methods in reflecting the experimentation in the field of non-destructive testing by infrared thermography. A non-reinforced concrete slab (1 m × 1 m × 0.25 m) containing four defects was used, two of which had the void type and two had honeycombs type. The defects were situated from 5 cm and 10 cm of the surface. The response of the slab to thermal excitation was investigated by determining the variation of temperature at the top surface of defects and at the slab surface by simulation and experimentation. A good correlation was noted between the numerical results and the experimentation for the three studied durations of thermal excitation (30 min, 60 min and 90 min)

The temporal dynamics of temporary pond macroinvertebrate communities over a 10-year period

Ponds support a rich biodiversity. This arises in part because of the number and heterogeneity of ponds spatially throughout the landscape. Studies of ponds suggest that distinct communities develop within individual ponds but most examples are based on shortterm 1- or 2-year surveys which cannot identify the effects of historic events upon contemporary communities. This study reports the development and turnover of the early summer macroinvertebrate communities in thirty small temporary ponds fromtheir creation in 1994 over 10 years to 2004. Distinct pioneer communities established in the first year of the ponds’ creation, the first 3 years dominated by a fauna associated with long summer dry phases. Then a sustained period of inundation lasting 27 months from summer 1997–1999 resulted in establishment of many taxa associated with permanent ponds and loss of some temporary pond species. The re-establishment of summer dry phases in 1999 was associated with the loss of some but not all of the permanent water taxa and re-colonisation by some temporary water species creating new communities combining these different elements. The communities were not a linear successional sequence; the communities that re-assembled following resumption of dry phases reflected the contingent history of each pond and the effects of historic events. The longer term nature of the study showed that the characteristic heterogeneity of pond invertebrate communities occurs through time as well as spatially and that the richness and variety of contemporary communities, which is often hard to explain fromsnap-shot studies, is partly the result of historic events