Fontes e modos de aplicação de fósforo na produção e nutrição mineral do milho.

Com o objetivo de avaliar o efeito de fontes de P, em diferentes modos de aplicação, sobre a produção e nutrição mineral do milho, um experimento foi conduzido em condições de campo, num Argissolo Vermelho típico, textura argilosa, sob vegetação de cerrado. Os tratamentos constituíram-se das fontes de P: superfosfato triplo (ST), termofosfato magnesiano (TM), fosfato reativo de Arad (FR) e fosfato de Araxá (FA), aplicadas em área total ou no sulco de plantio, na dose 180 kg ha-1 de P2O5, considerando-se o teor total de P2O5 das fontes. Utilizou-se, ainda, um tratamento adicional sem aplicação de P. Foram analisados os teores de nutrientes nas folhas do milho no florescimento e em diferentes partes da planta na colheita. Determinaram-se, também, a produção de matéria seca da parte aérea e de grãos e o acúmulo de nutrientes. Maiores produções foram obtidas com as fontes mais solúveis (ST e TM) aplicadas em área total e com o fosfato reativo (FR) no sulco de plantio. O uso localizado de ST no sulco de plantio comprometeu a produtividade da cultura, provocando desordens metabólicas devido à interação P x Zn. A análise foliar no florescimento mostrou-se adequada para avaliação do equilíbrio P/Zn no milho

Yang-Lee zeros for a nonequilibrium phase transition

Equilibrium systems which exhibit a phase transition can be studied by investigating the complex zeros of the partition function. This method, pioneered by Yang and Lee, has been widely used in equilibrium statistical physics. We show that an analogous treatment is possible for a nonequilibrium phase transition into an absorbing state. By investigating the complex zeros of the survival probability of directed percolation processes we demonstrate that the zeros provide information about universal properties. Moreover we identify certain non-trivial points where the survival probability for bond percolation can be computed exactly.Comment: LaTeX, IOP-style, 13 pages, 10 eps figure

Photodynamic inactivation of Lasiodiplodia theobromae: lighting the way towards an environmentally friendly phytosanitary treatment

The fungus Lasiodiplodia theobromae is one of the main causal agents of trunk canker and dieback of grapevine. The objective of this work was to evaluate the efficiency of photodynamic inactivation (PDI) of L. theobromae with synthetic and natural photosensitizers and irradiation with either sunlight or artificial photosynthetically active radiation. Although the growth of the mycelium could not be completely prevented with natural sunlight irradiation, phenothiazine dyes (methylene blue, MB; toluidine blue O, TBO), riboflavin and a cationic porphyrin (Tetra-Py+-Me) caused complete inhibition under continuous irradiation with artificial light. Free radicals were the main cytotoxic agents in the PDI with MB, indicating the predominance of the type I mechanism. PDI with MB or Tetra-Py+-Me may represent a promising approach for the sanitation of vine material in greenhouse nurseries, in order to reduce the risk of infection upon grafting.publishe

Dirac-Surface-State-Dominated Spin to Charge Current Conversion in the Topological Insulator (Bi0.22Sb0.78)2Te3(Bi_{0.22}Sb_{0.78})_2Te_3 Films at Room Temperature

We report the spin to charge current conversation in an intrinsic topological insulator (TI) $(Bi_{0.22}Sb_{0.78})_2Te_3$ film at room temperature. The spin currents are generated in a thin layer of permalloy (Py) by two different processes, spin pumping (SPE) and spin Seebeck effects (SSE). In the first we use microwave-driven ferromagnetic resonance of the Py film to generate a SPE spin current that is injected into the TI $(Bi_{0.22}Sb_{0.78})_2Te_3$ layer in direct contact with Py. In the second we use the SSE in the longitudinal configuration in Py without contamination by the Nernst effect made possible with a thin NiO layer between the Py and $(Bi_{0.22}Sb_{0.78})_2Te_3$ layers. The spin-to-charge current conversion is attributed to the inverse Edelstein effect (IEE) made possible by the spin-momentum locking in the electron Fermi contours due to the Rashba field. The measurements by the two techniques yield very similar values for the IEE parameter, which are larger than the reported values in the previous studies on topological insulators.Comment: 18 pages and 7 figure

Effect of bio-functional MAO layers on the electrochemical behaviour of highly porous Ti

Ti foams are attractive for orthopaedic applications due to reduced Young's modulus and ability of bone ingrowth. However, poor corrosion behaviour and lack of bioactivity are yet to be overcome. In the present work, highly porous Ti samples were processed by powder metallurgy with space holder technique and bio-functionalized by micro-arc oxidation, resulting in nano/micro structured TiO2 surfaces containing bioactive elements. The electrochemical behaviour of these bio-functionalized highly porous Ti surfaces was evaluated through potentiodynamic polarization and EIS in physiological solution at body temperature. Results showed that bio-functionalization improved the corrosion behaviour of highly porous Ti. However, increased macro-porosity led to an increased corrosion rate.This work is supported by FCT with the reference project UID/EEA/04436/2019, M-ERA NET/0001/2015 project, and Programa de Accoes Universitarias Integradas Luso-Francesas' (PAUILF TC-12_14). CQE is financed by FCT under Pluriannual contract 2020-2023. The authors also gratefully acknowledge the "Investissements d'avenir" programs (nos. ANR-11-IDEX-0003-02 and ANR-10-EQPX-37 MATMECA Grant) for financial support on Micro-CT analysis

A thick shell Casimir effect

We consider the Casimir energy of a thick dielectric-diamagnetic shell under a uniform velocity light condition, as a function of the radii and the permeabilities. We show that there is a range of parameters in which the stress on the outer shell is inward, and a range where the stress on the outer shell is outward. We examine the possibility of obtaining an energetically stable configuration of a thick shell made of a material with a fixed volume

Quark-Gluon String Model Description of Baryon Production in K^{\pm}N Interactions

The process of baryon production in K p collisions at high energies is considered in the framework of the Quark-Gluon String Model. The contribution of the string-junction mechanism to the strange baryon production is analysed. The results of numerical calculations are in reasonable agreement with the data on inclusive spectra of p, Lambda, bar{Lambda}, and on the bar{Lambda}/Lambda asymmetry. The predictions for Xi and Omega baryons are presented.Comment: 19 pages, 7 figure