One-loop N-point equivalence among negative-dimensional, Mellin-Barnes and Feynman parametrization approaches to Feynman integrals

We show that at one-loop order, negative-dimensional, Mellin-Barnes' (MB) and Feynman parametrization (FP) approaches to Feynman loop integrals calculations are equivalent. Starting with a generating functional, for two and then for $N$-point scalar integrals we show how to reobtain MB results, using negative-dimensional and FP techniques. The $N-$point result is valid for different masses, arbitrary exponents of propagators and dimension.Comment: 11 pages, LaTeX. To be published in J.Phys.

Correlações entre caracteres físico-químicos avaliados em acerolas de diferentes estádios de maturação.

O presente trabalho objetivou estimar e analisar as correlações entre caracteres físico-químicos de frutos aceroleira

Hydrothermal liquefaction versus catalytic hydrodeoxygenation of a bioethanol production stillage residue to platform chemicals:A comparative study

Biobased chemicals like phenols and aromatics are preferably produced from cheap biomass waste streams. In this work, we have explored the potential of a eucalyptus-derived second generation bioethanol production stillage (BPS) residue for this purpose. A comparative study between a hydrothermal liquefaction (HTL) and a catalytic hydrodeoxygenation (HDO) step, as well as a 2-step HTL-HDO approach is reported, targeting at value-added low molecular weight platform chemicals (mainly alkylphenols and aromatics). HDO was observed to be a more suitable strategy than HTL for the production of organic oils enriched in valuable monomers. The direct HDO of the BPS using a commercial Ru/C catalyst at 450 degrees C and 100 bar H-2 pressure led to an organic product oil (30.7 wt%) with a total monomer yield of 25.2 wt% (13.2 wt% of alkylphenolic+aromatics), compared to a 53.2 wt% of a product oil with 10.0 wt% monomers for the HTL step (305 degrees C). A 2-step HTL-HDO strategy was compared with the direct HDO approach. Comparable alkylphenolic+aromatic yields were obtained through this approach based on initial BPS intake (13.2 wt% vs 12.3 wt% for the direct HDO and HTL-HDO approach, respectively). Lower HTL temperatures (305 degrees C) for the first step are preferred to prevent over hydrogenation in the subsequent HDO step. As such, HTL appears a suitable pre-treatment for BPS and can (i) solve the issues related to the feeding of solids in pressurized continuous reactors for HDO and (ii) prevent coke formation during the HDO step, thus improving catalyst stability and durability

Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier

Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2\AA . The crossover in the conductance, the dependence of the tunnelling magnetoresistance with the bias voltage and the noise below 80K correspond to 1 monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunnelling through a single impurity layer generalized to 3D and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8\AA, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms.Comment: 10 pages, 13 figure

Quebra de dormência de macieira (Malus domestica) Eva cultivada no Vale do São Francisco.

O objetivo deste estudo foi avaliar o efeito de doses de cianamida hidrogenada (CH), nitrato 23 de cálcio (NC) e nitrato de potássio (NK) na quebra da dormência de macieiras, cultivar Eva no Vale do São Francisco, em Petrolina-PE