12,261 research outputs found

    Mechanism of magnetostructural transformation in multifunctional Mn3_3GaC

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    Mn3_3GaC undergoes a ferromagnetic to antiferromagnetic, volume discontinuous cubic-cubic phase transition as a function of temperature, pressure and magnetic field. Through a series of temperature dependent x-ray absorption fine structure spectroscopy experiments at the Mn K and Ga K edge, it is shown that the first order magnetic transformation in Mn3_3GaC is entirely due to distortions in Mn sub-lattice and with a very little role for Mn-C interactions. The distortion in Mn sub-lattice results in long and short Mn-Mn bonds with the longer Mn-Mn bonds favoring ferromagnetic interactions and the shorter Mn-Mn bonds favoring antiferromagnetic interactions. At the first order transition, the shorter Mn-Mn bonds exhibit an abrupt decrease in their length resulting in an antiferromagnetic ground state and a strained lattice.Comment: Accepted in J. Appl. Phys. Please contact authors for supplementary informatio

    China inward FDI and Chinese exports to High-Income Countries (HICs): a historical perspective based on bibliometric method

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    PR China is capturing FDI mainly from the overseas Chinese territories and from High-Income Countries (HICs); this last group is also the most important Chinese export-market. Adopting an inductive methodology, based on the bibliometric method, our purpose is the understanding of which were the determinants that led to attract inward FDI and, later, to increase exports from PR China to HICs. Taking into account the time frame 1980–2010, 367 different publications were collected. Using the ISI Web of Science and the HistCite Software 10 research papers were the basis for a bibliometric diagram (LCS > or equal to 5). From this diagram was possible to extract two main streams: economic reforms toward an inward FDI attraction and world exports leadership; and inward FDI—mainly from HICs—led to an increasing value of the exports basket. A third issue emerged also, not as a stream, but as an important conclusion based on the Gilboy (2004) paper, published on Foreign Affairs: foreign companies dominate high-tech industries and a lion’s part of Chinese industrial exports. PR China has reached the world exporting ranking leadership based on economic reforms, focused on the attraction of FDI export driven, which had on companies from HICs a major contribution

    Micropropagation of a recalcitrant pine (Pinus pinea L.): An overview of the effects of ectomycorrhizal inoculation

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    Stone pine (Pinus pinea L.) is an economically important forest species in some regions of Iberian Peninsula. Portugal and Spain have nearly 500,000 ha of stone pine stands, representing 85% of worldwide distribution. The main use of this species is for the production of seeds (pinion) for food industry. In addition to its enormous profitability as a producer of seeds, it has beneficial impact on soil protection, dunes fixation and is a pioneer species particularly for cork and holm oaks degraded ecosystems. Stone pine plantations are today a major source of income for forestry holdings. Investments have targeted breeding, reforestation, forest management and harvesting. The maternal inheritance of desirable characteristics such as cone weight, number of seeds per cone and seed length is considerably high in this species thus encouraging the selection of seeds from “plus” trees. The selected trees have been propagated by grafting and micropropagation. However, grafting generates high variability due to scion-rootstock interaction that varies production levels. The production of clonal plants from selected seeds by micropropagation techniques has advanced very slowly due to the recalcitrance of this species in tissue culture and particularly to adventitious rooting of microshoots. Due to the tremendous importance of developing a reproducible tissue culture method for clonal propagation, a study has been carried out for over a decade to enhance rooting and acclimation. During this period of time, continuous increments in the multiplication rate and rooting frequency were achieved by introducing variations in culture media composition and conditions. Auxins, carbohydrates, light quality and duration, temperature at different concentrations and levels as well as compounds such as coumarin; salicylic acid, polyamines, etc. were tested for induction and expression phases of adventitious rooting. Despite these efforts, microshoots regenerated through organogenesis from mature embryo cotyledons failed to root or to have sustained root growth. At this point, an in vitro co-culture technique of stone pine microshoots with ectomycorrhizal-fungi was introduced to overcome the adventitious root growth cessation in vitro and improve root development during acclimation phase. An overview of the results showing the positive effect of fungal inoculation in promoting root growth in vitro and on plantlet survival during acclimation will be presented. Preliminary results of biochemical signals between Pinus pinea/Pisolithus arhizus during early steps of in vitro culture detected by liquid chromatography-mass spectrometry that might be responsible for the positive effect on root growth will be also presented
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