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In this paper, the Weibel instability, driven by the plasma temperature anisotropy, in the corona of high intense laser fusion plasma is studied. The unperturbed electronic distribution function, f , of the anisotropic corona is supposed to be a bi-Maxwellian. That T = T ⊥ ± W O , where W O = 1 4 m e v 2 O is the averaged electron quiver energy in the laser electric field. The first and the second anisotropies of f projected on the Legendre polynomials are calculated as a function of the scaling parameter, W O T ⊥. The Weibel instability parameters are explicitly calculated as a function of the scaling parameter. For typical parameters of the laser pulse and the fusion plasma, it has been shown that very unstable Weibel modes, γ 10 11 s −1 , can be excited in the corona.

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Background: In humans, various diseases are associated with the accumulation of free radicals. The antioxidants can scavenge free radicals and reduce their impact; thus, the search for effective natural antioxidants of plant origin is indispensable. The present study aims to determine, for the first time, the flavonoid compounds profile and to investigate the free radical scavenging and antioxidant properties of the methanolic extract of Taxus baccata L. from Algeria. Methods:The determination of the flavonoid compound profile of the methanolic extract of Taxus baccata L. was established using high-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS). The total flavonoid content (TFC) was performed according to the aluminum chloride colorimetric method, while the free radical scavenging and antioxidant activities were carried out using three methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2'-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical assay and ferric reducing antioxidant power (FRAP) Assay.Results: A total of 26 compounds including flavon-3-ols, flavanonols, flavones, flavonols and bioflavonoids were characterized and identifiedusing HPLC-DAD-ESI-MS/MS analysis, five were reported for the first time such as taxifolin, apigenin, apigenin 7-O-glucoside, isorhamnetin 3-O-rutinoside and robustaflavone. The plant extract exhibited high total flavonoid content (TFC = 204.26 ± 6.02 mg RE/g dry extract) which corresponded to its strong radical scavenging activities [(DPPH IC 50 = 35.31 ± 0.29 µg/ml and ABTS IC 50 = 8.27 ± 0.52 µg/ml)] as compared to the synthetic antioxidant BHT [(DPPH IC 50 = 78.96 ± 5.70 µg/ml and ABTS IC 50 = 13.56 ± 0.06 µg/ml)]. However, the methanolic extract of T. baccata showed the lowest ferric reducing ability as compared to the positive controls (BHT, BHA, ascorbic acid, trolox and quercetin). Conclusion:Our results imply that the Taxus Baccata L. might be a potential source for the isolation of natural antioxidant compounds.

Natural regeneration of Taxus baccata L. is constrained due to the depth of seed dormancy requirements (often taking two or more years) and low seed germination. Further, the conventional method of vegetative propagation by cuttings is associated with difficulties in rooting. Hence, for the first time, this study describes an efficient and reproducible in vitro protocol for breaking the dormancy of seeds from the endangered forest tree T. baccata L. via zygotic embryo culture. Embryos isolated from 100% sterile seeds were cultured on DCR medium that contains sucrose (30 g/l), agar (8 g/l), and activated charcoal (5 g/l), fortified with different concentrations of Plant Growth Regulators (PGRs), and held at a temperature of 25 ± 2 ºC in a growth room. The results revealed that the in vitro embryo germination percentage was mostly affected by gibberellic acid (GA3) and thidiazuron (TDZ). Among the nine treatments, the treatments with 0.5 mg/l TDZ and 1 mg/l GA3 showed the highest germination (100%), while the other treatments all increased the germination percentages significantly compared to the control (37.5%). The 1/2 DCR medium with the addition of 0.1 mg/l indole-3-butyric acid (IBA) resulted in the highest rooting ratio (94%). However, the greatest root and hypocotyl elongation (59.37 ± 3.77 and 62.75 ± 4.43 mm, respectively) occurred when seedlings were cultured on 1/2 DCR medium containing 0.5 mg/l BA. Plantlets were transplanted into plastic pots containing an autoclaved garden soil, sand, and vermiculite mixture (1:1:1) and held at a temperature of 25 ± 2 ºC in a growth room for 4 weeks before being transplanted into the greenhouse. These results indicated that the protocol developed during the current study will be useful to overcome seed dormancy and for multiplication and conservation of the species T. baccata L.