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

Effects of cutting parameters during turning 100C6 steel

The objective of the paper is to evaluate the effects of cutting parameters in terms of cutting speed, depth of cut and feed rate on the influence of the surface roughness, consumed power, cutting time and tool vibrations during turning process. The material chosen in this case was 100C6 steel in dry conditions. The effects of the selected process parameters have been investigated using full factorial design of experiments (33) and the multiple linear regression (MLR). Thus, first-order empirical models were established. Analysis of variance (ANOVA) was employed to check the validity of the developed models within the limits of the factors that were being investigated and to test the significance of the above parameters. Results indicate that the feed rate is the only significant factor affecting the surface roughness. The cutting speed and feed rate are the most influential factors on cutting time. Estimated tool vibrations are functions of cutting speed, feed rate and depth of cut in decreasing order. Finally, the models obtained can be used for determination of optimal settings of cuttings parameters and this methodology should help us to obtain the best process parameters for dry turning of 100C6 steel

Dynamic characterization of the cutting conditions in dry turning

International audienc

Multi-objective optimization of cutting parameters for turning AISI 52100 hardened steel

International audienc

Bi-objective robust optimization of machined surface quality and productivity under vibrations limitation

In this contribution, a bi-objective robust optimization of cutting parameters, with the taking into account uncertainties inherent in the tool wear and the tool deflection for a turning operation is presented. In a first step, we proceed to the construction of substitution models that connect the cutting parameters to the variables of interest based on design of experiments. Our two objectives are the best machined surface quality and the maximum productivity under consideration of limitations related to the vibrations and the range of the three cutting parameters. Then, using the developed genetic algorithm that based on a robust evaluation mechanism of chromosomes by Monte-Carlo simulations, the influence and interest of the uncertainties integration in the machining optimization is demonstrated. After comparing the classical and robust Pareto fronts, A surface quality less efficient but robust can be obtained with the consideration of uncontrollable factors or uncertainties unlike that provides the deterministic and classical optimization for the same values of productivity

Some physicochemical and morphological characterizations of three varieties of Algerian common dates

The date palm is a typical plant of the arid and semi arid areas. Unfortunately in fact they are not all the varieties that profits from an economic interest except for Deglet-Nour. Thus, it represents a danger to the genetic inheritance and the biodiversity. The three varieties studied in this work are: Mech-Degla, Degla-Beida and Frezza, which are common varieties cultivated in the south of Algeria. They are characterized by a good availability and an interesting aptitude for the conservation. In this work (included in our project consisting in the valorization of the common local dates) were presented only the obtained first results. The morphological characteristics (weight of whole date, pea of pulp (pulpit), weight of the seed, length and width of whole date and the seed, pulp/seed ratio, pulp/date ratio, seed/date ration) are given. The physicochemical parameters studied are: pH, ashes, flavonoid, minerals and antioxidant activity. All three varieties are particularly rich in minerals (K, Ca, Na, Zn, Fe, Cu and Mn), in flavonoïd. Concerning the antioxidant activity, different cultivars is endowed with an extraordinary capacity (61.82, 61.56 and 61.61% respectively for Mech-Degla, Degla-Beida and Frezza). © EuroJournals Publishing, Inc. 200