Antimicrobial activity of spices essential oils and its effectiveness on mature biofilms of human pathogens

Abstract

The antibacterial activity of Pimpinella anisum L., Cinnamomum zeylanicum, Syzygium aromaticum, and Cuminum cyminum L. essential oils (EOs) against some common pathogenic microorganisms (Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 14990, Enterococcus faecalis ATCC 29212, Streptococcus pyogenes ATCC 1915, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 27853, Aeromonas hydrophila ATCC 7966, Proteus mirabilis ATCC 10005, Klebsiella pneumoniae ATCC 13883, and Candida albicans ATCC 10231) and their biofilms was studied. The EOs inhibitory effects were evaluated by both Agar Well Diffusion assay and Minimum Inhibitory Concentration (MIC) determination. The most active EOs, cinnamon and cloves, were also tested on 18, 24, 48, 72?hours mature biofilms. Cinnamon and cloves exhibited the best results showing a significant activity against all the tested bacteria. Concerning biofilm, results suggest that Cinnamomum zeylanicum oil may be a useful approach to impair the biofilm produced by the tested Gram-negative bacteria.      

Prediction of period doubling bifurcations in harmonically forced memristor circuits

Nonlinear Dynamics - The paper studies bifurcations and complex dynamics in a class of nonautonomous oscillatory circuits with a flux-controlled memristor and harmonic forcing term. It is first...     

A Comparison of Preconditioners for the Steklov–Poincaré Formulation of the Fluid-Structure Coupling in Hemodynamics

A Fluid–Structure Interaction (FSI) problem can be reinterpreted as a heterogeneous problem with two subdomains. It is possible to describe the coupled problem at the interface between the fluid and the structure, yielding a nonlinear Steklov–Poincaré problem. The linear system can be linearized by Newton iterations on the interface and the resulting linear problem can be solved by the preconditioned GMRES method. In this work we investigate the behavior of preconditioners of Neumann–Neumann and Dirichlet–Neumann type. We find that, in the context of hemodynamics, the Dirichlet– Neumann, i.e., using Dirichlet boundary conditions on the fluid side and Neumann on the structure side, outperforms the Neumann–Neumann method, except when a weighting is used such that it basically reduces to the Dirichlet–Neumann method. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On a class of functions of the interval with zero topological entropy

We prove that functions defined on the Cantor set Q in such a way that each element of the transformed sequence depends only on the elements of the original one placed in the same or preceding positions, and extended by linearity on the whole unit interval I, have zero topological entropy.     

Network representation of dynamical systems: Connectivity patterns,information and predictability

The present work elaborates on predictability and information aspects of dynamical systems, in connection with the connectivity features of their network representation. The basic idea underlying this work is to map the set of coarse-grained states of a dynamical system onto a set of network nodes and transitions between them onto a set of network links. Based on the vertex centrality of these nodes, we define (a) a local indicator of predictability, (b) a measure of the information that is available about the state of the system after one transition occurring within an arbitrary long time window and (c) an upper bound for the time horizon of predictability. We address the cases of the tent and the cusp maps, as representative examples of Markov and non-Markov processes. An analytical exact result for the horizon of predictability is obtained for the tent map, as well as for its higher iterates, and its connection with the corresponding network diameters is discussed. Similarly, analytical expressions are derived for the bounds of the predictability horizon in the case of the cusp map.     

Paracyclic and quasi-cyclic groups

Summary For a finite group G put l_g= min {[G: ,]¦xG}and .Call G paracyclic iff l_GG It is proved that any metacyclic group is paracyclic and that l_G2_G whenever ¦G¦=p expG (p prime).Moreover all non-paracyclic groups satisfying the last condition are classified.Research partially supported by GNSAGA of CNR.     

1,4-benzothiazine derivatives from 2-aminobenzenethiol and hydrazonoyl halides

2-Aminobenzenethiol was condensed with alkyl α-chlorophenylhydrazonoglyoxylates yielding alkyl 2-(2-aminophenylthio)-2-arylhydrazonoglyoxylates which were cyclized to the corresponding 2-arylhydrazono-2,3-dihydro-4H-1,4-benzothiazin-3-ones. Starting from α-chloro-α-arylhydrazonoacetones the corresponding 2-arylhydrazono-3-methylbenzo-1,4-benzothiazines were formed.     

A system of functional equations related to plurality functions. A method for the construction of the solutions

Summary In the first part of the present paper we prove some necessary conditions satisfied by the solutions of a system of functional equations related to Plurality Functions. In the second part we describe a geometric-combinatorial procedure for the construction of the solutions of that system. This procedure yields all possible solutions.