University of Avignon

About: University of Avignon is a education organization based out in Avignon, Provence-Alpes-Côte-d'Azur, France. It is known for research contribution in the topics: Population & Speaker recognition. The organization has 1526 authors who have published 3766 publications receiving 88928 citations.

Are old Mediterranean grasslands resilient to human disturbances

Abstract: Many dry herbaceous ecosystems suffer damage and are characterized by low resilience after disturbance. Among these forms of disturbance, soil excavation due to the construction of underground pipelines affects vegetation at plant community and landscape scales. Synchronic studies are the best approach for more rapid study of plant succession on ecosystems with low resilience. In order to better understand plant succession in a Mediterranean dry grassland, we compared the effect of a recent disturbance caused by the digging of a pipeline in 2006 with that of a pipeline created in 1972 in the same area. Surveys of floristic composition and richness were carried out along both pipelines in order to understand the succession after this single disturbance, one that does not drastically change soil chemical properties unlike former agricultural practices. Nevertheless, this type of disturbance still changes the floristic composition in the long term (>30 years). The first stage begins just after disturbance with the occurrence of many weed species. Another level between the first and the mature stage was characterized in our study, 30 years after the disturbance, by an assemblage of annual and perennial species but still lacking species typical of the reference steppe. The reference steppe is described as the mature level of the succession with an assemblage of typical grasses, forbs and a few small chamaephytes and, in particular, by the presence of Brachypodium retusum. This community corresponds to a very old Mediterranean grassland that has evolved under the Mediterranean climate and traditional sheep grazing management systems since the Neolithic Age. This study confirms the low resilience of this steppe community and shows the importance of pursuing research on this steppe and in particular on the biotic and abiotic processes involved in community assembly.

UV-visible spectroscopic investigation of the 8,8-methylmethine catechin-malvidin 3-glucoside pigments in aqueous solution: structural transformations and molecular complexation with chlorogenic acid.

Abstract: The physicochemical properties of 8,8-methylmethine catechin-malvidin 3-O-glucoside isomers, commonly referred to as catechin-ethyl-malvidin 3-O-glucoside, have been studied in aqueous solutions and compared with those of the parent anthocyanin (malvidin 3-O-glucoside). The hydration and acidity constants (pKh and pKa) of the catechin-ethyl-malvidin 3-O-glucoside pigments and malvidin 3-O-glucoside were determined by UV−visible spectroscopic measurements. The ethyl-linked catechin-malvidin 3-O-glucoside pigments present higher stability toward hydration than the parent anthocyanin. The high resistance of these ethyl-linked pigments toward the hydration is related to the self-association that offers optimal protection from the nucleophilic attack of water. Moreover, the ethyl link may confer to the molecule enough flexibility to undergo intramolecular interaction, further protecting it from hydration and bisulfite discoloration. In the wine pH range (3.2−4.0), due to the low pKa and high pKh values, the et...

Use of Total Organic Carbon (TOC) as tracer of diffuse infiltration in a dolomitic karstic system: The Nerja Cave (Andalusia, southern Spain)

Abstract: [1] Recent studies in several karstic systems in France have highlighted that Total Organic Carbon (TOC) was a relevant parameter in order to characterise the behaviour of aquifers, to differentiate the water types that participate in karstic flow (fast infiltration, unsaturated zone, saturated zone) and to evaluate their vulnerability. This study on TOC dynamics at the experimental site of the Nerja Cave has been performed to test the potential of this tracer in a particular climatic (Mediterranean climate), lithologic (dolomitic marbles) and hydrodynamic (diffuse flow behaviour) context. TOC evolution, compared to those of classical tracers used in hydrogeology, permits the understanding of the hydrodynamical behaviour of the unsaturated zone of this dolomitic aquifer, whose response to precipitation is slower than that commonly obtained in karstic aquifers of calcareous nature.

Deodorization by instant controlled pressure drop autovaporization of rosemary leaves prior to solvent extraction of antioxidants

Abstract: During the extraction of antioxidants from a natural product, volatile compounds are also extracted and consequently the final extract quality is decreased. Therefore, a deodorization step is necessary. The present study introduces thermo-mechanical treatment of rosemary leaves using the instantaneous controlled pressure drop (DIC) method as both deodorization and expansion process. In addition, DIC-deodorization treatment was compared with the hydrodistillation-deodorization (HD). The extraction of essential oils was achieved on dried rosemary leaves within an optimized time of 3 min by DIC and 4 h by HD. Deodorized leaves were recovered and antioxidants were extracted using solvent extraction (ethanol:water 80:20). With standard protocol extraction, rosmarinic acid of DIC-treated rosemary leaves (12.76 mg/g) was twice as much as untreated leaves (6.74 mg/g). Scanning electron microscopy (SEM) and light microscopy showed that DIC treatment resulted in profound alterations at cytohistological levels which explain the observed effectiveness of DIC process. The specific surface area calculations showed that DIC treatment allows the material to obtain a higher specific surface area. This explains the behaviour of the product towards the extraction. Overall, the results clearly revealed that DIC is an efficient method of deodorization that improved solvent extraction of rosemary antioxidants.