Nonlinear Dynamics of Magnetic Islands Imbedded in Small-Scale Turbulence

International audienceThe nonlinear dynamics of magnetic tearing islands imbedded in a pressure gradient driven turbulence is investigated numerically in a reduced magnetohydrodynamic model. The study reveals regimes where the linear and nonlinear phases of the tearing instability are controlled by the properties of the pressure gradient. In these regimes, the interplay between the pressure and the magnetic flux determines the dynamics of the saturated state. A secondary instability can occur and strongly modify the magnetic island dynamics by triggering a poloidal rotation. It is shown that the complex nonlinear interaction between the islands and turbulence is nonlocal and involves small scales

Effect of the curvature and the {\beta} parameter on the nonlinear dynamics of a drift tearing magnetic island

We present numerical simulation studies of 2D reduced MHD equations investigating the impact of the electronic \beta parameter and of curvature effects on the nonlinear evolution of drift tearing islands. We observe a bifurcation phenomenon that leads to an amplification of the pressure energy, the generation of E \times B poloidal flow and a nonlinear diamagnetic drift that affects the rotation of the magnetic island. These dynamical modifications arise due to quasilinear effects that generate a zonal flow at the onset point of the bifurcation. Our simulations show that the transition point is influenced by the \beta parameter such that the pressure gradient through a curvature effect strongly stabilizes the transition. Regarding the modified rotation of the island, a model for the frequency is derived in order to study its origin and the effect of the \beta parameter. It appears that after the transition, an E \times B poloidal flow as well as a nonlinear diamagnetic drift are generated due to an amplification of the stresses by pressure effects

The main phenolic compounds responsible for the antioxidant capacity of sweet cherry (Prunus avium L.) pulp

The antioxidant capacity of sweet cherry (Prunus avium L.) pulp extracts is strictly related to the phenolic content, starting from the fact that the higher content of phenolic compounds corresponds to the higher antioxidant indexes. This work aims to assess which compounds characterized three cultivars, namely Ferrovia, Sweetheart, and Lapins grown in Southern Italy and mainly influenced the antioxidant capacity of their extracts. HPLC–MS/MS analyses were conducted to identify and quantify 17 flavonoids and 25 hydroxicinnamates derivatives. A significant influence of cultivar was revealed from one-way MANOVA (p < 0.05). Furthermore, the extracts were tested for their radical scavenging activity (DPPH and ABTS assays) and reducing power using the Folin–Ciocalteau method. Lapins and Sweetheart extracts, richer in phenolic compounds, returned the highest reducing power and radical scavenging capacity. Finally, a Factorial Analysis was applied to the collected data allowing reliable correlations between phenolics and antioxidant indexes

A Modified Rabbit Ulna Defect Model for Evaluating Periosteal Substitutes in Bone Engineering: A Pilot Study

The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm) were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane) scaffold soaked in PBS and left as such (group Ia) or wrapped with a tissue-engineered periosteal substitute (group Ib). For group II, an expanded-polytetrafluoroethylene (e-PTFE) (GORE-TEX\uae) membrane was inserted around the radius then the defects received either scaffold alone (group IIa) or scaffold wrapped with periosteal substitute (group IIb). Animals were euthanized after 12\u201316 weeks, and bone regeneration was evaluated by radiography, computed microtomography (\ub5CT), and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORETEX\uae) membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitut

Olive tree in circular economy as a source of secondary metabolites active for human and animal health beyond oxidative stress and inflammation

none10noExtra-virgin olive oil (EVOO) contains many bioactive compounds with multiple biological activities that make it one of the most important functional foods. Both the constituents of the lipid fraction and that of the unsaponifiable fraction show a clear action in reducing oxidative stress by acting on various body components, at concentrations established by the European Food Safety Authority’s claims. In addition to the main product obtained by the mechanical pressing of the fruit, i.e., the EVOO, the residual by-products of the process also contain significant amounts of antioxidant molecules, thus potentially making the Olea europea L. an excellent example of the circular economy. In fact, the olive mill wastewaters, the leaves, the pomace, and the pits discharged from the EVOO production process are partially recycled in the nutraceutical and cosmeceutical fields also because of their antioxidant effect. This work presents an overview of the biological activities of these by-products, as shown by in vitro and in vivo assays, and also from clinical trials, as well as their main formulations currently available on the market.openMallamaci R.; Budriesi R.; Clodoveo M.L.; Biotti G.; Micucci M.; Ragusa A.; Curci F.; Muraglia M.; Corbo F.; Franchini C.Mallamaci, R.; Budriesi, R.; Clodoveo, M. L.; Biotti, G.; Micucci, M.; Ragusa, A.; Curci, F.; Muraglia, M.; Corbo, F.; Franchini, C

Olive Tree in Circular Economy as a Source of Secondary Metabolites Active for Human and Animal Health Beyond Oxidative Stress and Inflammation

Abstract Extra-virgin olive oil (EVOO) contains many bioactive compounds with multiple biological activities that make it one of the most important functional foods. Both the constituents of the lipid fraction and that of the unsaponifiable fraction show a clear action in reducing oxidative stress by acting on various body components, at concentrations established by the European Food Safety Authority’s claims. In addition to the main product obtained by the mechanical pressing of the fruit, i.e., the EVOO, the residual by-products of the process also contain significant amounts of antioxidant molecules, thus potentially making the Olea europea L. an excellent example of the circular economy. In fact, the olive mill wastewaters, the leaves, the pomace, and the pits discharged from the EVOO production process are partially recycled in the nutraceutical and cosmeceutical fields also because of their antioxidant effect. This work presents an overview of the biological activities of these by-products, as shown by in vitro and in vivo assays, and also from clinical trials, as well as their main formulations currently available on the market

2-(1,3-Dioxoisoindolin-2-yl)acetonitrile

The asymmetric unit of the title compound, C10H6N2O2, contains two independent mol­ecules. The dihedral angles between the acetonitrile and the 1H-isoindole-1,3(2H)-dione units are 69.0 (7)° and 77.0 (5)° in the two mol­ecules. One of the two terminal N atoms is disordered over two positions in a 0.66 (8):0,34 (8) ratio. In the crystal structure, the mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonds

A Tara Gum/Olive Mill Wastewaters Phytochemicals Conjugate as a New Ingredient for the Formulation of an Antioxidant-Enriched Pudding

Olive mill wastewater, a high polyphenols agro-food by-product, was successfully ex-ploited in an eco-friendly radical process to synthesize an antioxidant macromolecule, usefully engaged as a functional ingredient to prepare functional puddings. The chemical composition of lyophilized olive mill wastewaters (LOMW) was investigated by HPLC-MS/MS and1H-NMR analyses, while antioxidant profile was in vitro evaluated by colorimetric assays. Oleuropein aglycone (5.8 μg mL−1) appeared as the main compound, although relevant amounts of an isomer of the 3-hydroxytyrosol glucoside (4.3 μg mL−1) and quinic acid (4.1 μg mL−1) were also detected. LOMW was able to greatly inhibit ABTS radical (IC50 equal to 0.019 mg mL−1), displaying, in the aqueous medium, an increase in its scavenger properties by almost one order of magnitude compared to the organic one. LOMW reactive species and tara gum chains were involved in an eco-friendly grafting reaction to synthesize a polymeric conjugate that was characterized by spec-troscopic, calorimetric and toxicity studies. In vitro acute oral toxicity was tested against 3T3 fibro-blasts and Caco-2 cells, confirming that the polymers do not have any effect on cell viability at the dietary use concentrations. Antioxidant properties of the polymeric conjugate were also evaluated, suggesting its employment as a thickening agent, in the preparation of pear puree-based pudding. High performance of consistency and relevant antioxidants features over time (28 days) were detected in the milk-based foodstuff, in comparison with its non-functional counterparts, confirming LOWM as an attractive source to achieve high performing functional foods