Search results for "Essential"

Composition and in vitro antifungal activity of essential oils of Erigeron canadensis and Myrtus communis from France. CHEMISTRY OF NATURAL COMPOUNDS…

2003

Defining Life as a Non-Essentialist Natural Kind

2019

Abstract: The increasing number of proposals to define the concept of life in biology has led some authors to consider this task useless and without sense. All sceptics base their argument on the idea that life is a natural kind with a strong metaphysical commitment. Considering this, the aim of this paper is to explore the concept of life as a non-essentialist natural kind. It is intended to highlight that complex scientific concepts are better understood from points of view that are not constrained by the rigid frameworks of essentialism and the realism/conventionalism dichotomy.  Keywords: natural kind, definition of life, essentialism, operational definitions.

Sanitizing food contact surfaces by the use of essential oils

2018

Chemical sanitizers continue to be widely used by the food industry to disinfect food contact surfaces. However, as some chemical disinfectants have been reported to produce unhealthy by-products, alternative and natural compounds need to be investigated. To this end, nine essential oils (EOs) were screened to develop a natural sanitizing solution (SAN) for disinfecting food contact surfaces. Once extracted, their antimicrobial activity and chemical composition were determined. An exploratory multivariate approach was used to investigate the relationships between the chemical and microbiological data sets. Among the tested EOs, Thymbra capitata EO, containing up to 93.31% oxygenated monoter…

Antibacterial and antioxidant activities in Sideritis italica (Miller) Greuter et Burdet essential oils

2006

Sideritis italica (Miller) Greuter et Burdet is a widespread Lamiacea in the Mediterranean region used in traditional medicine. Essential oils were antibacterial against nine ATCC and as many clinically isolated Gram-positive and Gram-negative bacterial strains. Antibacterial activity was also found against Helicobacter pylori: a dose-dependant inhibition was shown between 5 and 25 microg/ml. The antibacterial activity of the oils was expressed as MICs (minimum inhibitory concentrations) and MBCs (minimum bactericidal concentrations). At a concentration between 3.9 and 250 microg/ml the oils showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In …

Oligopeptide assimilation and transport by Oenococcus oeni

2008

International audience; Aims: Oenococcus oeni is a slow-growing wine bacterium with a low growth yield. It thrives better on complex nitrogen sources than on free amino-acid medium. We aimed to characterize the oligopeptide use of this micro-organism. Methods and Results: Several peptides of two to eight amino-acid residues were able to provide essential amino acids. The disappearance of various peptides from extracellular medium was assessed with whole cells. Initial rates of utilization varied with the peptide, and free amino acids were released into the medium. Conclusions: Oenococcus oeni was able to transport the oligopeptides with two to five amino-acid residues tested and to hydrolys…

A review on some discrete variational techniques for the approximation of essential boundary conditions

2022

We review different techniques to enforce essential boundary conditions, such as the (nonhomogeneous) Dirichlet boundary condition, within a discrete variational framework, and especially techniques that allow to account for them in a weak sense. Those are of special interest for discretizations such as geometrically unfitted finite elements or high order methods, for instance. Some of them remain primal, and add extra terms in the discrete weak form without adding a new unknown: this is the case of the boundary penalty and Nitsche techniques. Others are mixed, and involve a Lagrange multiplier with or without stabilization terms. For a simple setting, we detail the different associated for…

Lacunary bifurcation for operator equations and nonlinear boundary value problems on ℝN

1991

SynopsisWe consider nonlinear eigenvalue problems of the form Lu + F(u) = λu in a real Hilbert space, where L is a positive self-adjoint linear operator and F is a nonlinearity vanishing to higher order at u = 0. We suppose that there are gaps in the essential spectrum of L and use critical point theory for strongly indefinite functionals to derive conditions for the existence of non-zero solutions for λ belonging to such a gap, and for the bifurcation of such solutions from the line of trivial solutions at the boundary points of a gap. The abstract results are applied to the L2-theory of semilinear elliptic partial differential equations on ℝN. We obtain existence results for the general c…

Citrus cybrid leaf essential oil

2000

The essential oil from the leaves of a Citrus cybrid plant, obtained by somatic hybridization between ‘Valencia’ sweet orange (Citrus sinensis L. Osbeck), embryogenic parent, and ‘Femminello’ lemon (C. limon L. Burm f.), leaf parent, has been studied by steam distillation and GC–MS analysis and compared with the correspondent oils from the parent plants. Although the overall composition of the cybrid essential oil appears much closer to that of ‘Femminello’, the relatively higher percentage of β-caryophyllene, as well as the qualitative and quantitative modifications of the esteric fraction, are characteristic of the new hybrid. Since cybrid cells possess the nuclear genome of the mesophyll…

On the reconstruction of discontinuous functions using multiquadric RBF–WENO local interpolation techniques

2020

Abstract We discuss several approaches involving the reconstruction of discontinuous one-dimensional functions using parameter-dependent multiquadric radial basis function (MQ-RBF) local interpolants combined with weighted essentially non-oscillatory (WENO) techniques, both in the computation of the locally optimized shape parameter and in the combination of RBF interpolants. We examine the accuracy of the proposed reconstruction techniques in smooth regions and their ability to avoid Gibbs phenomena close to discontinuities. In this paper, we propose a true MQ-RBF–WENO method that does not revert to the classical polynomial WENO approximation near discontinuities, as opposed to what was pr…

Importancia de la integración e implementación de un Modelo de Gestión de Medicamentos en programas de Cooperación Internacional

2020

La gestión de los medicamentoscontinúa siendo un reto en la mayoría de los paísesen vías de desarrollo, dónde no existen sistemasde gestión que garanticen la calidad/disponibilidadde los medicamentos, lo cual implica un grave impacto en la salud de la población atendida.Es por ello muy importantedisponer de unModelo de Gestión de Medicamentos. Este modelo esundocumento que sirve como referencia para organizar el trabajo en torno a los medicamentos y cubre todos los pasos involucrados en la gestión de los mismos; desde su compra hasta la utilización por parte del pacientey en su caso,suposterior eliminación regulada.Los documentos,protocolos y guíasque serán parte de este modelo estarán siem…