Determination of isoquinoline alkaloids contents in two Algerian species of Fumaria (Fumaria capreolata and Fumaria bastardi)

This paper describes a fast and efficient procedure to separate and identify isoquinoline alkaloids from methalonic extract of two Algerian Fumaria (Fumariacea) species (Fumaria capreolata L. and Fumariabastardi L.) used in traditional medicine in cases of hepatobiliary disfunction and diarrhoea. Total quinolizidine alkaloid contents were 426 mg/100 g (F. capreolata) and 521 mg/100 g (F. bastardi). Theisoquinoline alkaloids, stylopine, protopine, fumaritine, fumaricine, fumarophycine, fumariline and fumarofine were determined by gas chromatography – mass spectrometry (GC-MS) in aerial parts ofboth Fumaria capreolata and Fumaria bastardi. In the first species, an ester of phtalic acid was identified, and in the second species a peak seems to be a benzophenanthridine, probably a dehydro derivative and three other peaks which were identified as phtalidisoquinoline, one of them seems to bedihydrofumariline. The chemotaxonomic significance of the results is discussed

Vortex phase transition and superconducting properties of organic quasi-two-dimensional k-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br

International audienceWe report investigations of the low temperature dc susceptibility and the magnetization on the layered organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br near 80K and the effect of disorder on the superconducting transition temperature Tc. The shielding effect (S) and the critical current density Jc were studied (with H parallel to the c axis of the crystal). Jc can be estimated by analysis of magnetic hysteresis measurement using the Bean model. For each temperature value, we observed two regimes in the critical current density Jc(H). This result implies that there exists a first-order phase transition in the vortex system in this organic superconductor. Our results show that the magnetic properties of these compounds depend strongly on the cooling rate. The structural transformation which occurs at the vicinity of 80K very strongly influences the physics of vortex lattice and the associated magnetic behavior

The vortex motion and the magnetization study in YBa2Cu3O7-d single crystal

We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail".We have investigated the vortex motion and the magnetization of high critical temperature superconductors YBa2Cu3O7-d Measurements were made using a vibrating sample magnetometer technique. Several magnetization hysteresis cycles have been obtained for different angles, θ, between the applied magnetic field, H, and the crystallographic c-axis. For T = 30 K we observed a central peak and for T = 80 K we observed a second peak or "fishtail"

The critical current density and the vortex pinning in high quality YBa2Cu3O7-d thin films

We have measured the critical current density Jc of high quality c-axis oriented YBa2Cu3O7-d thin films. Measurements were performed for various magnetic field and temperature values, and as a function of the angle q between the c-axis and the applied magnetic field direction. A maximum of the critical current density was obtained when the flux lines are aligned along the CuO planes (q = 90°); another maximum in Jc was also observed when the magnetic field is adjusted parallel to the c-axis. We attribute these effects to different, intrinsic and extrinsic, pinning mechanisms of vortices in the sample.We have measured the critical current density Jc of high quality c-axis oriented YBa2Cu3O7-d thin films. Measurements were performed for various magnetic field and temperature values, and as a function of the angle q between the c-axis and the applied magnetic field direction. A maximum of the critical current density was obtained when the flux lines are aligned along the CuO planes (q = 90°); another maximum in Jc was also observed when the magnetic field is adjusted parallel to the c-axis. We attribute these effects to different, intrinsic and extrinsic, pinning mechanisms of vortices in the sample

LEÓN, JOSÉ CLAUDIO DE Y SRA. [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Comparative study on the antioxidant effect of aqueous and ethanolic extracts of Mentha pulegium L. grown at two different locations

Aqueous and ethanolic extracts of Mentha pulegium L. (Lamiaceae) from two different locations Tizi-Ouzou and Bejaia in Algeria were examined in vitro. Phenolic compounds and antioxidant activity were analyzed. Measurement of total phenolic and total flavonoids contents of the extracts of M. pulegium were achieved by using Folin-Ciocalteu and chloride aluminium methods, respectively. The total phenolic content of water extract from Tizi-Ouzou location was found significantly higher (55.78  2.78 mg GAE/g DW). The flavonoids content was also higher in the extracts from this location for both ethanolic and water extracts (2.17  0.12; 2.04  0.03 mg QE/g DW, respectively). Antioxidant activities were assessed by five in vitro antioxidant assays. Results showed that the two M. pulegium provenances were significantly different according to their antioxidant activity. Indeed, aqueous extract issued from Bejaia plant exhibited stronger antioxidant activity. For instance, Bejaia provenance shoots showed lower IC50 value of 20.35 μg/ mL for H2O2 test