Virtual flux (VF)-oriented control (VFOC) and VF-based direct power control (DPC) (VF-DPC) have been developed to improve voltage-oriented control and DPC of three-phase active rectifiers. The VF ...space vector is utilized in transformations between stationary and rotating coordinates in VFOC and in obtaining instantaneous power in VF-DPC. The VF space vector is calculated by integrating the grid voltage space vector. This integration is usually performed using a first-order low-pass (LP) (FOLP) filter, which counteracts the saturation and dc-drift problems associated with pure integrators. However, the dynamics of FOLP filters can be enhanced to a great extent. This paper presents a new, simple, and fast integration algorithm for VF-based control methods. Simulations and experimental tests on a VF-DPC-based system showed that the proposed algorithm leads to rapid recoveries after grid voltage sags occur. Moreover, the performance of VF-DPC under nonideal grids is discussed.
Biosphere-atmosphere interactions were investigated on a sandy dune Mediterranean ecosystem in a field campaign held in 2007 within the frame of the European Projects ACCENT and VOCBAS. The campaign ...was carried out in the Presidential estate of Castelporziano, a peri-urban park close to Rome. Former campaigns (e.g. BEMA) performed in Castelporziano investigated the emission of biogenic volatile organic compounds (BVOC). These campaigns focused on pseudosteppe and evergreen oak groves whereas the contribution of the largely biodiverse dune vegetation, a prominent component of the Mediterranean ecosystem, was overlooked. While specific aspects of the campaign will be discussed in companion papers, the general climatic and physiological aspects are presented here, together with information regarding BVOC emission from the most common plant species of the dune ecosystem. During the campaign regular air movements were observed, dominated by moderate nocturnal land breeze and diurnal sea breeze. A regular daily increase of ozone concentration in the air was also observed, but daily peaks of ozone were lower than those measured in summer on the same site. The site was ideal as a natural photochemical reactor to observe reaction, transport and deposition processes occurring in the Mediterranean basin, since the sea-land breeze circulation allowed a strong mixing between biogenic and anthropogenic emissions and secondary pollutants. Measurements were run in May, when plant physiological conditions were optimal, in absence of severe drought and heat stress. Foliar rates of photosynthesis and transpiration were as high as generally recorded in unstressed Mediterranean sclerophyllous plants. Most of the plant species emitted high level of monoterpenes, despite measurements being made in a period in which emissions of volatile isoprenoids could be restrained by developmental and environmental factors, such as leaf age and relatively low air temperature. Emission of isoprene was generally low. Accounting for the high monoterpene spring emission of the dune ecosystem may be important to correct algorithms at regional and ecosystem levels, and to interpret measurements of fluxes of volatile isoprenoids and secondary pollutants.
Laser Doppler anemometery and laser-induced fluorescence techniques were used to explore the spatial structure of the flow within and above finite cavities created within porous and solid media. The ...cavities within these two configurations were identical in size and were intended to mimic flow disturbances created by finite gaps and forest clearing. Because flows over permeable boundaries differ from their solid counterparts, the study here addresses how these differences in boundary conditions produce differences in, (i) bulk flow properties including the mean vorticity within and adjacent to the gaps, (ii) second-order statistics such as the standard deviations and turbulent stresses, (iii) the relative importance of advective to turbulent stress terms across various regions within and above the gaps, and (iv) the local imbalance between ejections and sweeps and momentum transport efficiencies of updrafts and downdrafts. Both configurations exhibited a primary recirculation zone of comparable dimensions inside the gap. The mean vorticity spawned at the upstream corner of the gap was more intense for the solid configuration when compared to its porous counterpart. The free-shear layer spawned from the upstream corner-edge deeper into the gap for the porous configuration. The momentum flux at the interface within and above the gap was enhanced by a factor of 1.5–2.0 over its upstream value, and this enhancement zone was much broader in size for the porous configuration. For the turbulent transport terms in the longitudinal and vertical mean momentum balances, these transport terms were significant inside the gap for both boundary configurations when compared to their upstream counterpart. The effectiveness of using incomplete cumulant expansion methods to describe the momentum transport efficiencies, and the relative contributions of ejections and sweeps to turbulent stresses, especially in this zone, were also demonstrated. The flatness factor for both velocity components, often used as a measure of intermittency, was highest in the vicinity of the upstream corner in both configurations. However, immediately following the downstream corner, the flatness factor remained large for the porous configuration, in contrast to its solid configuration counterpart.
•First study of probiotics influence on some bioactives’ stability in gastrointestinal digestion.•Influence of several soluble and insoluble prebiotics on BEA bioaccessibility.•Influence of different ...probiotic strains on BEA bioaccessibility.•LC–MS-LIT determination of possible bacteria-produced BEA degradation by-products.
Beauvericin (BEA) is a bioactive compound produced by the secondary metabolism of several Fusarium strains and known to have various biological activities. This study investigates the influence of several dietary fibers (galactomanan, glucomannan, citrus fiber, bamboo fiber, carrot fiber, pie fiber, β-glucan, xilan, and cellulose) and probiotic strains (Lactobacillus animalis, Lb. casei, Lb. casei, Lb. plantarum, Lb. rhuminis, Lb. casei casei, Bifidobacterium breve, Bf. Adolescents, Bf. bifidum, Corynebacterium vitaeruminis, Streptococcus faecalis, Eubacterium crispatus, and Saccharomyces cerevisiae) on the minor Fusarium mycotoxin BEA bioaccessibility employing a model solution. The bioaccessibility was determined using a simulated gastrointestinal digestion that mimics the physiological conditions of the digestive tract until the colonic compartment. The determination of BEA in the intestinal fluids was carried out by liquid chromatography–mass spectrometry detection (LC–MS). The reduction of BEA bioaccessibility in the experiments carried out using the prebiotic compounds ranged from 60 to 80%, whereas in the trials carried out using the probiotic strains the bioaccessibility observed ranged from 30 to 85%. A BEA degradation product produced by colonic fermentation was identified using the technique of LC–MS-LIT.
Temperature evolution in supercapacitors (SCs) when they are charged or discharged at a constant current is a well-known process. However, it does not exist any mathematical equation for the ...calculation of the instantaneous temperature of the SC when it is charged or discharged at constant power. In this work, a new mathematical formulation is presented, which allows for the analytical calculation of temperature as a function of time (or alternatively, as a function of the current or the internal or the external voltage), considering the electrical and thermal properties provided by the manufacturer of the SC or obtained through laboratory tests. Highly accurate equations for the calculation of instantaneous current, power losses and other significant variables are also obtained. The validity of the proposal is demonstrated by comparing the results obtained with the new method with those yielded from the classical iterative, numerical resolution of the differential equations. The high accuracy of the proposed approach makes it useful to be used in the task of sizing the cooling systems of SC applications.
•Constant-power operation of SCs has been studied.•Novel formulae to estimate current, power and energy losses have been developed.•New equations to assess SCs temperature have been proposed.•Temperature as a function of time and various electrical variables can be obtained.•Proposed formulae are simple and remarkably accurate.
The bodies of mammals are hosts to vast microbial communities composed of trillions of bacteria from thousands of species, whose effects on health and development have begun to be appreciated only ...recently. In this investigation, an integrated analysis combining proteomics and transcriptomics was used to quantitatively compare the terminal ilia from conventional and germfree mice. Female and male mice responded similarly to the microbiota, but C57BL/10A mice responded more strongly than BALB/c mice at both the transcriptome and proteome levels. The microbiota primarily caused upregulation of immunological pathways and downregulation of metabolic pathways in the conventional mice. Many of the affected pathways were altered only at either the transcriptome or proteome level. Of the pathways that were affected at both levels, most were affected concordantly. The discordant pathways were not principally involved in the immune system but instead were related to metabolism, oxidative phosphorylation, protein translation, transport, and turnover. To broaden the discovery of affected host pathways, a meta-analysis was performed using intestinal transcriptomics data from previously published studies of germfree versus conventional mice with diverse microbiota populations. Similar transcript-level responses to the microbiota were found, and many additional affected host pathways were discovered.
Multiple host pathways were affected by its adaptation to the microbiota. We have found significant transcriptome-proteome discordance caused by the microbiota. This discovery leads to the definite conclusion that transcript-level analysis is not sufficient to predict protein levels and their influence on the function of many specific cellular pathways, so only analysis of combinations of the quantitative data determined at different levels will lead to a complete understanding of the complex relationships between the host and the microbiota. Therefore, our results demonstrate the importance of using an integrative approach to study host-microbiota interaction at the molecular level.
The objective of this study was to evaluate a water‐soluble extract from sourdoughs fermented with the lactic acid bacteria (LAB) for antifungal reflect on loaf bread. The extracts produced by ...Lactobacillus plantarum CECT 749 and L. bulgaricus CECT 4005 were effective against strains of Fusarium spp., Penicillium spp., and Aspergillus spp., with minimum inhibitory concentration ranging from 1.6 to 200 mg/ml and minimum fungicidal concentration from 1.6 to 400 mg/ml. LC‐ESI‐MS‐TOF was used to analyze the antimicrobial compounds. Several antimicrobial phenolic acids were found. Fermented sourdoughs used for the production of loaf bread produced a reduction of fungal growth in relation on the sourdough control and improved to the shelf life of 1 to 2 days compared to control bread with 0.2% calcium propionate. Therefore, LAB are an alternative to synthetic compounds for decreasing fungal contaminants and prolonging the shelf life of food.
Practical applications
This study presents the importance of sourdough fermented by Lactobacillus plantarum spp. and the production during the fermentation of bioactive metabolites with antifungal activity. When applied in the preparation of bread, it is able to increase the useful life of the bread and its efficiency can be compared to that of calcium propionate. It is thus an alternative to synthetic compounds for decreasing fungal contaminants and prolonging the shelf life of food.
To obtain the bioactive compound beauvericin (BEA),
Fusarium proliferatum CECT 20569 was grown on a solid medium of wheat, utilizing the technique of the solid state fermentation (SSF), being this ...mycotoxin purified by high performance liquid chromatography (HPLC) with a reverse phase semi-preparative column using as the mobile phase acetonitrile/water in gradient condition. The purity of the BEA was verified by analytical HPLC and liquid chromatography tandem mass spectrometry (LC/MS-MS). The pure fractions of BEA were utilized to determinate the antibiotic effects on several bacterial strains that are considered normally pathogens of the intestinal tract as:
Escherichia coli, Enterococcus faecium, Salmonella enterica, Shigella dysenteriae, Listeria monocytogenes, Yersinia enterocolitica, Clostridium perfringens, Pseudomonas aeruginosa and
Staphylococcus aureus.
The aim of this study was to investigate the bioaccessibility of beauvericin (BEA) and enniatins (ENs) present in wheat crispy breads. A microbial fermentation was performed by a BEA- and ...ENs-producer Fusarium strain, adding inulin and fructooligosaccharides (FOS) at two concentrations (1% and 5%). The bioaccessibility of mycotoxins was determined by static and dynamic simulated gastrointestinal digestion systems, imitating the digestive physiological conditions until the colonic compartment. BEA and ENs were determined in the intestinal fluids by liquid chromatography-tandem mass spectrometry (LC-MS/MS). BEA and ENs bioaccessibilities in the static model (46.7–61.1% and 6.2–44.9%, respectively) were lower than those found in the dynamic one (76.2–91.0% and 23.0–68.9%, respectively). Addition of inulin and FOS decreased the bioaccessibility of BEA and ENs, with a concentration-dependent behavior, thus being a potential strategy to reduce human exposure to these minor mycotoxins.
•BEA and ENs bioaccessibilities were lower in the static digestion model.•Addition of inulin and FOS decreased the bioaccessibility of BEA and ENs.•Inulin and FOS had a concentration-dependent effect on BEA and ENs bioaccessibility.•Dietary fiber is a potential strategy to reduce human exposure to minor mycotoxins.
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