8,412 research outputs found
Immobilization of Bacteriocins from Lactic Acid Bacteria and Possibilities for Application in Food Biopreservation
Bacteriocins are biologically active compounds produced by a large number of bacteria, including lactic acid bacteria (LAB), which exhibit antimicrobial activity against various saprophytic and pathogenic microorganisms. In recent decades, bacteriocins are increasingly becoming more important in different branches of the industry due to their broad antibacterial and antifungal spectrum - in the food industry for natural food preservation and expiry date extension; in the health sector for preparation of probiotic foods and beverages; in the clinical practice as alternatives of conventional antibiotics; in the agriculture as biocontrol agents of plant pathogens and alternatives of chemical pesticides for plant protection. The broad antimicrobial spectrum of bacteriocins has stimulated the research attention on their application mainly in the food industry as natural preservatives. Most scientific achievements concerning the application food biopreservation are related to bacteriocins produced by LAB. The lactic acid bacteria bacteriocins can be produced in the food substrate during its natural fermentation or can be added in the food products after obtaining by in vitro fermentations under optimal physical and chemical conditions. Moreover, the immobilization of LAB bacteriocins on different matrices of organic and inorganic origin has been proposed as an advanced approach in the natural food preservation for their specific antimicrobial activity, anti-biofilm properties and potential use as tools for pathogen detection
Theoretical Study of Comb-Polymers Adsorption on Solid Surfaces
We propose a theoretical investigation of the physical adsorption of neutral
comb-polymers with an adsorbing skeleton and non-adsorbing side-chains on a
flat surface. Such polymers are particularly interesting as "dynamic coating"
matrices for bio-separations, especially for DNA sequencing, capillary
electrophoresis and lab-on-chips. Separation performances are increased by
coating the inner surface of the capillaries with neutral polymers. This method
allows to screen the surface charges, thus to prevent electro-osmosis flow and
adhesion of charged macromolecules (e.g. proteins) on the capillary walls. We
identify three adsorption regimes: a "mushroom" regime, in which the coating is
formed by strongly adsorbed skeleton loops and the side-chains anchored on the
skeleton are in a swollen state, a "brush" regime, characterized by a uniform
multi-chains coating with an extended layer of non-adsorbing side-chains and a
non-adsorbed regime. By using a combination of mean field and scaling
approaches, we explicitly derive asymptotic forms for the monomer concentration
profiles, for the adsorption free energy and for the thickness of the adsorbed
layer as a function of the skeleton and side-chains sizes and of the adsorption
parameters. Moreover, we obtain the scaling laws for the transitions between
the different regimes. These predictions can be checked by performing
experiments aimed at investigating polymer adsorption, such as Neutron or X-ray
Reflectometry, Ellipsometry, Quartz Microbalance, or Surface Force Apparatus.Comment: 30 pages, 7 figures, to be published in Macromolecule
A choice of the optimum cutting ranges for cutting nozzles a-sd for selection of metallurgical material.
On the market there are plenty of machines for cutting of steel via a mixture of oxygen and flammable gases. Various manufacturers provide several types of torches, cutting nozzles and other equipment in their product range. Cutting nozzles are a component that significantly affects quality of cutting based in set parameters. However, data from catalogues and manuals by manufacturers on cutting parameters of nozzles are rarely in use in real conditions. That is why optimum cutting conditions for cutting via nozzles A-SD made by RHONA were tested and the final results were compared with those in the catalogue for a proper use in practice.Web of Science12311310
Polyphenols as Suitable control for Obesity and Diabetes
Modern life is characterized by physical inactivity and poor food choices, which is often a prerequisite for unhealthy weight gain and overweight/obesity. These factors unlock the emergence of a number of diseases including diabetes, cardiovascular problems, different types of cancer, etc. The pursuit of scientists to seek strategies to prevent, relieve and cure the patient leads to the usage of natural compounds of potential beneficial effect. Polyphenols are a large group of naturally occurring secondary metabolites mainly found in plants and beverages. The presence of these secondary metabolites seems to decrease the manifestation of miscellaneous disease-causing symptoms. The purpose of this review is to synthesize information about polyphenols and their potential in controlling obesity and diabetes. Polyphenols are considered as health-beneficial sources and thus could be involved in novel strategies for preventing diabetes and obesity complications
Creation of Procedural Materials in Substance Designer and their Application in Unity
Treball final de Grau en Disseny i Desenvolupament de Videojocs. Codi: VJ1241. Curs acadèmic: 2018/2019This project was born to show the potential of the software Substance Designer and its
uses in Unity. For this purpose, I created a collection of different materials using the
software and implemented them in Unity.
In this document I will explain the characteristics of Substance Designer, the workflow I followed using the software, how a material can be converted into a procedural one,
how to set up a Unity project to adapt well to the procedural materials and the demo
I’ve done to show the adaptability of the materials, first with an static environment and
later, in another scene, how the procedural materials work and change in runtime.
I hope that, with this project, I can show the importance of materials and all the
features they have to offer, as they can replace a lot of geometry and lessen the load of
polygons in a game environment
Strongly correlated one-dimensional Bose-Fermi quantum mixtures: symmetry and correlations
We consider multi-component quantum mixtures (bosonic, fermionic, or mixed)
with strongly repulsive contact interactions in a one-dimensional harmonic
trap. In the limit of infinitely strong repulsion and zero temperature, using
the class-sum method, we study the symmetries of the spatial wave function of
the mixture. We find that the ground state of the system has the most symmetric
spatial wave function allowed by the type of mixture. This provides an example
of the generalized Lieb-Mattis theorem. Furthermore, we show that the symmetry
properties of the mixture are embedded in the large-momentum tails of the
momentum distribution, which we evaluate both at infinite repulsion by an exact
solution and at finite interactions using a numerical DMRG approach. This
implies that an experimental measurement of the Tan's contact would allow to
unambiguously determine the symmetry of any kind of multi-component mixture.Comment: 19 pages, 6 figure
High-momentum tails as magnetic structure probes for strongly-correlated fermionic mixtures in one-dimensional traps
A universal decay of the large-momentum tails of the momentum
distribution, fixed by Tan's contact coefficients, constitutes a direct
signature of strong correlations in a short-range interacting quantum gas. Here
we consider a repulsive multicomponent Fermi gas under harmonic confinement, as
in the experiment of Pagano et al. [Nat. Phys. {\bf 10}, 198 (2014)], realizing
a gas with tunable symmetry. We exploit an exact solution at
infinite repulsion to show a direct correspondence between the value of the
Tan's contact for each of the components of the gas and the Young
tableaux for the permutation symmetry group identifying the magnetic
structure of the ground-state. This opens a route for the experimental
determination of magnetic configurations in cold atomic gases, employing only
standard (spin-resolved) time-of-flight techniques. Combining the exact result
with matrix-product-states simulations, we obtain the Tan's contact at all
values of repulsive interactions. We show that a local density approximation
(LDA) on the Bethe-Ansatz equation of state for the homogeneous mixture is in
excellent agreement with the results for the harmonically confined gas. At
strong interactions, the LDA predicts a scaling behavior of the Tan's contact.
This provides a useful analytical expression for the dependence on the number
of fermions, number of components and on interaction strength. Moreover, using
a virial approach in the limit of infinite interactions, we show that the
contact increases with the temperature and the number of components. At zero
temperature, we predict that the weight of the momentum distribution tails
increases with interaction strength and the number of components if the
population per component is kept constant. This latter property was
experimentally observed in Ref.~[Nat. Phys. {\bf 10}, 198 (2014)].Comment: 13 pages, 6 figure
Exact density profiles and symmetry classification for strongly interacting multi-component Fermi gases in tight waveguides
We consider a mixture of one-dimensional strongly interacting Fermi gases up
to six components, subjected to a longitudinal harmonic confinement. In the
limit of infinitely strong repulsions we provide an exact solution which
generalizes the one for the two-component mixture. We show that an imbalanced
mixture under harmonic confinement displays partial spatial separation among
the components, with a structure which depends on the relative population of
the various components. Furthermore, we provide a symmetry characterization of
the ground and excited states of the mixture introducing and evaluating a
suitable operator, namely the conjugacy class sum. We show that, even under
external confinement, the gas has a definite symmetry which corresponds to the
most symmetric one compatible with the imbalance among the components. This
generalizes the predictions of the Lieb-Mattis theorem for a fermionic mixture
with more than two components.Comment: 14 pages, 2 figures, invited contribution to special issue in NJP in
memory of Marvin Girardeau. New Journal of Physics 201
A mechanistic model (BCC-PSSICO) to predict changes in the hydraulic properties for bio-amended variably saturated soils
This is the peer reviewed version of the following article: [Carles Brangarí, A., X. Sanchez-Vila, A. Freixa, A. M. Romaní, S. Rubol, and D. Fernàndez-Garcia (2017), A mechanistic model (BCC-PSSICO) to predict changes in the hydraulic properties for bio-amended variably saturated soils, Water Resour. Res., 53, 93–109, doi:10.1002/2015WR018517], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/2015WR018517/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The accumulation of biofilms in porous media is likely to influence the overall hydraulic properties and, consequently, a sound understanding of the process is required for the proper design and management of many technological applications. In order to bring some light into this phenomenon we present a mechanistic model to study the variably saturated hydraulic properties of bio-amended soils. Special emphasis is laid on the distribution of phases at pore-scale and the mechanisms to retain and let water flow through, providing valuable insights into phenomena behind bioclogging. Our approach consists in modeling the porous media as an ensemble of capillary tubes, obtained from the biofilm-free water retention curve. This methodology is extended by the incorporation of a biofilm composed of bacterial cells and extracellular polymeric substances (EPS). Moreover, such a microbial consortium displays a channeled geometry that shrinks/swells with suction. Analytical equations for the volumetric water content and the relative permeability can then be derived by assuming that biomass reshapes the pore space following specific geometrical patterns. The model is discussed by using data from laboratory studies and other approaches already existing in the literature. It can reproduce (i) displacements of the retention curve toward higher saturations and (ii) permeability reductions of distinct orders of magnitude. Our findings also illustrate how even very small amounts of biofilm may lead to significant changes in the hydraulic properties. We, therefore, state the importance of accounting for the hydraulic characteristics of biofilms and for a complex/more realistic geometry of colonies at the pore-scale.Peer ReviewedPostprint (author's final draft
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