Search results for "methods"
showing 10 items of 4526 documents
ON THE UNIT CELL BOUNDARY VALUE PROBLEM WITH MESHLESS FORMULATION FOR MASONRY STRUCTURES
2017
In a generic multi-scale computational homogenization (CH) procedure, the crucial point is the definition and the solution of the Unit Cell (UC) Boundary Value Problem (BVP). The main aspects to be chosen for the formulation of the UC BVP are: (i) geometry; (ii) bound- ary conditions (BCs); (iii) material models; (iv) numerical approximation techniques. All these components play a key-role in the efficiency of the multi-scale procedure. In the present study, the UC BVP is formulated for running bond masonry according to a dis- placement based variational formulation, where the material of the blocks is considered indefi- nitely elastic and the mortar joints are simulated by zero-thickness e…
Free vibrations of anisotropic panels
2004
A meshfree approach, called Displacement Boundary Method, for the analysis of in-plane and out-of-plane free vibrations of anisotropic plates is presented. The discretization process is based on the use of a modified variational principle and the static fundamental solutions of the problem operators. The stiffness and mass matrices are frequencyindependent, symmetric and positive definite and their computation requires boundary integrations of regular kernels only. Thus, the final resolving system can be solved with classical approaches by using standard numerical procedures. Numerical results are presented to show the accuracy and effectiveness of the method.
Evidence of thin-film precursors formation in hydrokinetic and atomistic simulations of nano-channel capillary filling
2008
We present hydrokinetic Lattice Boltzmann and Molecular Dynamics simulations of capillary filling of high-wetting fluids in nano-channels, which provide clear evidence of the formation of thin precursor films, moving ahead of the main capillary front. The dynamics of the precursor films is found to obey the Lucas-Washburn law as the main capillary front, z2(t) proportional to t, although with a larger prefactor, which we find to take the same value for both geometries under inspection. Both hydrokinetic and Molecular Dynamics approaches indicate a precursor film thickness of the order of one tenth of the capillary diameter. The quantitative agreement between the hydrokinetic and atomistic m…
Semiempirical pseudopotential approach for nitride-based nanostructures and {\it ab initio} based passivation of free surfaces
2013
We present a semiempirical pseudopotential method based on screened atomic pseudopotentials and derived from \textit{ab initio} calculations. This approach is motivated by the demand for pseudopotentials able to address nanostructures, where \textit{ab initio} methods are both too costly and insufficiently accurate at the level of the local-density approximation, while mesoscopic effective-mass approaches are inapplicable due to the small size of the structures along, at least, one dimension. In this work we improve the traditional pseudopotential method by a two-step process: First, we invert a set of self-consistently determined screened {\it ab initio} potentials in wurtzite GaN for a ra…
The Low Energy-Coupling Respiration in Zymomonas mobilis Accelerates Flux in the Entner-Doudoroff Pathway.
2015
Performing oxidative phosphorylation is the primary role of respiratory chain both in bacteria and eukaryotes. Yet, the branched respiratory chains of prokaryotes contain alternative, low energy-coupling electron pathways, which serve for functions other than oxidative ATP generation (like those of respiratory protection, adaptation to low-oxygen media, redox balancing, etc.), some of which are still poorly understood. We here demonstrate that withdrawal of reducing equivalents by the energetically uncoupled respiratory chain of the bacterium Zymomonas mobilis accelerates its fermentative catabolism, increasing the glucose consumption rate. This is in contrast to what has been observed in o…
Impact of Gluten-Friendly Bread on the Metabolism and Function of In Vitro Gut Microbiota in Healthy Human and Coeliac Subjects
2016
The main aim of this paper was to assess the in vitro response of healthy and coeliac human faecal microbiota to gluten-friendly bread (GFB). Thus, GFB and control bread (CB) were fermented with faecal microbiota in pH-controlled batch cultures. The effects on the major groups of microbiota were monitored over 48 h incubations by fluorescence in situ hybridisation. Short-chain fatty acids (SCFAs) were measured by high-performance liquid chromatography (HPLC). Furthermore, the death kinetics of Lactobacillus acidophilus, Bifidobacterium animalis subsp. lactis, Staphylococcus aureus, and Salmonella Typhimurium in a saline solution supplemented with GFB or CB were also assessed. The experiment…
Convergent adaptation of Saccharomyces uvarum to sulfite, an antimicrobial preservative widely used in human-driven fermentations
2021
Different species can find convergent solutions to adapt their genome to the same evolutionary constraints, although functional convergence promoted by chromosomal rearrangements in different species has not previously been found. In this work, we discovered that two domesticated yeast species, Saccharomyces cerevisiae, and Saccharomyces uvarum, acquired chromosomal rearrangements to convergently adapt to the presence of sulfite in fermentation environments. We found two new heterologous chromosomal translocations in fermentative strains of S. uvarum at the SSU1 locus, involved in sulfite resistance, an antimicrobial additive widely used in food production. These are convergent events that …
Potential pitfalls of FISH microscopy as assessment method for anaerobic digesters
2016
AbstractIn the present work we investigated how the state of a biogas reactor impacts the enumeration of prokaryotic cells by fluorescencein situhybridisation (FISH). Therefore, the correlation between gas production and FISH hybridisation rates was analysed in different anaerobic digester sludges. High gasification activity coincided with high hybridisation rates. Low hybridisation rates were especially achieved with reactor samples subjected to long starvation periods showing low biogas production.Based on our findings we conclude that samples for FISH analysis should be fixed as soon as possible to prevent a loss of microbial activity resulting in lower FISH signals. Furthermore, the loc…
Comparative First-Principles Calculations of SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (001), (011) and (111) Surfaces
2015
I present the results of my ab initio calculations for SrTiO3, BaTiO3, PbTiO3 and CaTiO3 neutral (001), as well as for polar (011) and (111) surfaces using the hybrid description of exchange and correlation. AO and BO2-terminations for the nonpolar (001) surface and A, BO, and O terminations of the polar (011) surface, as well as B and AO3-terminations of the polar (111) surface were calculated. In the case of the neutral AO-terminated (001) surface for SrTiO3, BaTiO3, PbTiO3 and CaTiO3 perovskites, all upper-layer A atoms relax inward towards the bulk, while all second layer atoms relax outwards. For the BO2-terminated (001) surface, in most cases, the largest relaxations are on the second…
Componimenti misti di storia dell’arte e d’invenzione: gli antichi maestri nella pittura e nella novellistica italiana dell’Ottocento
2008
This article investigates the popular imagery of art-historical matters in Italian Romantic art and literature.