High intensity tapping regime in a frustrated lattice gas model of granular compaction

In the frame of a well established lattice gas model for granular compaction, we investigate the high intensity tapping regime where a pile expands significantly during external excitation. We find that this model shows the same general trends as more sophisticated models based on molecular dynamic type simulations. In particular, a minimum in packing fraction as a function of tapping strength is observed in the reversible branch of an annealed tapping protocol.Comment: 5 pages, 4 figure

An architectural framework for heterogeneous networking.

The growth over the last decade in the use of wireless networking devices has been explosive. Soon many devices will have multiple network interfaces, each with very different characteristics. We believe that a framework that encapsulates the key challenges of heterogeneous networking is required. Like a map clearly helps one to plan a journey, a framework is needed to help us move forward in this unexplored area. The approach taken here is similar to the OSImodel in which tightly defined layers are used to specify functionality, allowing a modular approach to the extension of systems and the interchange of their components, whilst providing a model that is more oriented to heterogeneity and mobility

Espuestas a la fertilización fosforada y evaluación de cuatro métodos extractivos de fosforo en suelos de la región semiárida pampeana central con cultivo de alfalfa (Ensayo en macetas)

La información referida a fertilidad fosforada, incluyendo la utilización del método Bray Kurtz 1 como diagnóstico, es escasa y contradictoria para los suelos de la región semiárida pampeana central. Por este motivo se estudiaron los rendimientos y respuestas a la fertilización fosforada de alfalfa, así como los contenidos de nutrientes en dos cortes sucesivos por medio de un ensayo en macetas. Se utilizaron diez Haplustoles énticos de planicie con propiedades físicas (granulometría) y químicas (contenidos de materia orgánica, Alo, Feo y carbonato de calcio) variables. Se realizaron cuatro tratamientos (Testigo, Fertilización completa, Fertilización completa sin sorgo, Fertilización con fósforo) y se evaluaron cuatro métodos de extracción de fósforo disponible (Bray Kurtz 1, Olsen, Kelowna y Resinas de intercambio anióníco). Se observó que ninguno de los métodos probados predice ni los rendimientos ni las respuestas a la fertilización en la totalidad de los suelos de la región. En parte esto se explica porque otros nutrientes posiblemente se encuentren en cantidades limitantes (azufre, magnesio, zinc), aparentemente la materia orgánica es un "pool" de fósforo para la planta, no detectable por los métodos de extracción utilizados.Director: Ing. Agr. Daniel Buschiazzo. Profesor Asociado Cátedra de Edafología, manejo y conservación de suelos

The shape of invasion perclation clusters in random and correlated media

The shape of two-dimensional invasion percolation clusters are studied numerically for both non-trapping (NTIP) and trapping (TIP) invasion percolation processes. Two different anisotropy quantifiers, the anisotropy parameter and the asphericity are used for probing the degree of anisotropy of clusters. We observe that in spite of the difference in scaling properties of NTIP and TIP, there is no difference in the values of anisotropy quantifiers of these processes. Furthermore, we find that in completely random media, the invasion percolation clusters are on average slightly less isotropic than standard percolation clusters. Introducing isotropic long-range correlations into the media reduces the isotropy of the invasion percolation clusters. The effect is more pronounced for the case of persisting long-range correlations. The implication of boundary conditions on the shape of clusters is another subject of interest. Compared to the case of free boundary conditions, IP clusters of conventional rectangular geometry turn out to be more isotropic. Moreover, we see that in conventional rectangular geometry the NTIP clusters are more isotropic than TIP clusters

Enraizamiento de internodios de Zea diploperennis Iltis, Doebley Guzman

Internodios de Zea diploperennis fueron inducidos a enraizar en posición horizontal o vertical en presencia de Ácido Indol Acético (AlA) en concentración de 5ppm. aplicado en pasta de lanolina en la región apical. La respuesta al enraizamiento fue observada en el lugar de aplicación en presencia o ausencia de AlA. cuando los internodios fueron colocados en posición horizontal. En internodios verticales el AlA inhibió la respuesta al enraizamiento

Rifabutin-Loaded Nanostructured Lipid Carriers as a Tool in Oral Anti-Mycobacterial Treatment of Crohn s Disease

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Oral anti-mycobacterial treatment of Crohn’s disease (CD) is limited by the low aqueous solubility of drugs, along with the altered gut conditions of patients, making uncommon their clinical use. Hence, the aim of the present work is focused on the in vitro evaluation of rifabutin (RFB)-loaded Nanostructured lipid carriers (NLC), in order to solve limitations associated to this therapeutic approach. RFB-loaded NLC were prepared by hot homogenization and characterized in terms of size, polydispersity, surface charge, morphology, thermal stability, and drug payload and release. Permeability across Caco-2 cell monolayers and cytotoxicity and uptake in human macrophages was also determined. NLC obtained were nano-sized, monodisperse, negatively charged, and spheroidal-shaped, showing a suitable drug payload and thermal stability. Furthermore, the permeability profile, macrophage uptake and selective intracellular release of RFB-loaded NLC, guarantee an effective drug dose administration to cells. Outcomes suggest that rifabutin-loaded NLC constitute a promising strategy to improve oral anti-mycobacterial therapy in Crohn’s disease.This research was funded by V-A POCTEP Program (0245_IBEROS_1_E) of EU (FEDER), Xunta de Galicia (Competitive Reference Groups, ED431C 2016/008 and ED431C2017/09-FEDER), as well as by Fundação para a Ciência e Tecnologia, Portugal (under iMED.ULisboa project Pest-UID/DTP/04138/2019).info:eu-repo/semantics/publishedVersio

Rifabutin-Loaded Nanostructured Lipid Carriers as a Tool in Oral Anti-Mycobacterial Treatment of Crohn’s Disease

Oral anti-mycobacterial treatment of Crohn’s disease (CD) is limited by the low aqueous solubility of drugs, along with the altered gut conditions of patients, making uncommon their clinical use. Hence, the aim of the present work is focused on the in vitro evaluation of rifabutin (RFB)-loaded Nanostructured lipid carriers (NLC), in order to solve limitations associated to this therapeutic approach. RFB-loaded NLC were prepared by hot homogenization and characterized in terms of size, polydispersity, surface charge, morphology, thermal stability, and drug payload and release. Permeability across Caco-2 cell monolayers and cytotoxicity and uptake in human macrophages was also determined. NLC obtained were nano-sized, monodisperse, negatively charged, and spheroidal-shaped, showing a suitable drug payload and thermal stability. Furthermore, the permeability profile, macrophage uptake and selective intracellular release of RFB-loaded NLC, guarantee an effective drug dose administration to cells. Outcomes suggest that rifabutin-loaded NLC constitute a promising strategy to improve oral anti-mycobacterial therapy in Crohn’s diseaseThis research was funded by V-A POCTEP Program (0245_IBEROS_1_E) of EU (FEDER), Xunta de Galicia (Competitive Reference Groups, ED431C 2016/008 and ED431C2017/09-FEDER), as well as by Fundação para a Ciência e Tecnologia, Portugal (under iMED.ULisboa project Pest-UID/DTP/04138/2019)S

Cation distribution in manganese cobaltite spinels Co3−xMnxO4 (0 ≤ x ≤ 1) determined by thermal analysis

Thermogravimetric analysis was used in order to study the reduction in air of submicronic powders of Co3−x Mn x O4 spinels, with 0 ≤ x ≤ 1. For x = 0 (i.e. Co3O4), cation reduction occurred in a single step. It involved the CoIII ions at the octahedral sites, which were reduced to Co2+ on producing CoO. For 0 < x ≤ 1, the reduction occurred in two stages at increasing temperature with increasing amounts of manganese. The first step corresponded to the reduction of octahedral CoIII ions and the second was attributed to the reduction of octahedral Mn4+ ions to Mn3+. From the individual weight losses and the electrical neutrality of the lattice, the CoIII and Mn4+ ion concentrations were calculated. The distribution of cobalt and manganese ions present on each crystallographic site of the spinel was determined. In contrast to most previous studies that took into account either CoIII and Mn3+ or Co2+, CoIII and Mn4+ only, our thermal analysis study showed that Co2+/CoIII and Mn3+/Mn4+ pairs occupy the octahedral sites. These results were used to explain the resistivity measurements carried out on dense ceramics prepared from our powders sintered at low temperature (700–750 °C) in a Spark Plasma Sintering apparatus

Uptake of gases in bundles of carbon nanotubes

Model calculations are presented which predict whether or not an arbitrary gas experiences significant absorption within carbon nanotubes and/or bundles of nanotubes. The potentials used in these calculations assume a conventional form, based on a sum of two-body interactions with individual carbon atoms; the latter employ energy and distance parameters which are derived from empirical combining rules. The results confirm intuitive expectation that small atoms and molecules are absorbed within both the interstitial channels and the tubes, while large atoms and molecules are absorbed almost exclusively within the tubes.Comment: 9 pages, 12 figures, submitted to PRB Newer version (8MAR2K). There was an error in the old one (23JAN2K). Please download thi

The Role of Power-Law Correlated Disorder in the Anderson Metal-Insulator Transition

We study the influence of scale-free correlated disorder on the metal-insulator transition in the Anderson model of localization. We use standard transfer matrix calculations and perform finite-size scaling of the largest inverse Lyapunov exponent to obtain the localization length for respective 3D tight-binding systems. The density of states is obtained from the full spectrum of eigenenergies of the Anderson Hamiltonian. We discuss the phase diagram of the metal-insulator transition and the influence of the correlated disorder on the critical exponents.Comment: 6 pages, 3 figure