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

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

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

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 SU(κ)SU(\kappa) fermionic mixtures in one-dimensional traps

A universal $k^{-4}$ 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 $SU(\kappa)$ 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 $\kappa$ components of the gas and the Young tableaux for the $S_N$ 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