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This study investigates the antibacterial properties of the natural oil from Copaifera multijuga which was embedded in bio-based materials, to be used in active packaging applications. For this purpose, the naturally extracted copaiba oil was first characterized by gas chromatography and thermogravimetry. Its antibacterial properties were evaluated and confirmed against gram-positive bacteria ( Bacillus subtilis ). The copaiba oil was incorporated into two bio-based materials: (i) paper and (ii) poly(lactic acid), PLA, films. This incorporation was made following two strategies: either at the surface, thanks to a coating process, or in the bulk, through impregnation (paper samples) or by film casting (PLA films). The antibacterial tests confirmed activity against B. subtilis in paper with a copaiba oil content of approximately 20 wt%. For the PLA films, the same amount showed satisfactory results against the same bacteria. To the best of our knowledge, it is the first time that copaiba oil has been incorporated on paper sheets and plastic films, with the confirmation of the maintenance of the effective antibacterial properties. The materials developed in this work through simple procedures have great perspective to be used as biodegradable packaging with bactericide effect, to improve the shelf life of food products. [ABSTRACT FROM AUTHOR]

In this paper we study the well-posedness of different models of population of leaky integrate-and-fire neurons with a population density approach. The synaptic interaction between neurons is modeled by a potential jump at the reception of a spike. We study populations that are self excitatory or self inhibitory. We distinguish the cases where this interaction is instantaneous from the one where there is a repartition of conduction delays. In the case of a bounded density of delays both excitatory and inhibitory population models are shown to be well-posed. But without conduction delay the solution of the model of self excitatory neurons may blow up. We analyze the different behaviours of the model with jumps compared to its diffusion approximation. [ABSTRACT FROM AUTHOR]

Abstract: A new two-dimensional network model is proposed as a micromechanics model to simulate paper’s failure process due to sequentially breakages of fibers and/or bonds. Paper is approximated as a network composed of fibers any two of which link to each other by their intersecting point, namely so-called bond. Fibers distribute along three particular directions, leading to network’s macro-level isotropy. In the framework of finite element method, nodes correspond to fiber-to-fiber bonds, while elements are fiber segments between every two neighboring nodes and described by Timoshenko beam theory. Element breaks when its equivalent internal tensile stress reaches the tensile strength of fiber. Strength of nodes, i.e. fiber-to-fiber bonds is assumed to be dependant on shearing interaction between fibers, considering the dominant interaction is shearing in a plane problem. Numerical examples show the model’s capacity of reflecting basic failure characteristic in paper. Influences of fiber length and the ratio of fiber strength to bond strength are analyzed in detail. [ABSTRACT FROM AUTHOR]

In this paper, a vector-form factor graph representation is derived for intersymbol interference (ISI) channels. The resultant graphs have a tree-structure that avoids the short cycle problem in existing graph approaches. Based on a joint Gaussian approximation, we establish a connection between the LLR (log-likelihood ratio) estimator for a linear system driven by binary inputs and the LMMSE (linear minimum mean-square error) estimator for a linear system driven by Gaussian inputs. This connection facilitates the application of the recently proposed Gaussian message passing technique to the cycle-free graphs for ISI channels. We also show the equivalence between the proposed approach and the Wang-Poor approach based on the LMMSE principle. An attractive advantage of the proposed approach is its intrinsic parallel structure. Simulation results are provided to demonstrate this property. [ABSTRACT FROM AUTHOR]