103 research outputs found
Fast method for the determination of short-chain-length polyhydroxyalkanoates (scl-PHAs) in bacterial samples by In Vial-Thermolysis (IVT)
none8siA new method based on the GCâMS analysis of thermolysis products obtained by treating bacterial
samples at a high temperature (above 270 C) has been developed. This method, here named âIn-Vial-
Thermolysisâ (IVT), allowed for the simultaneous determination of short-chain-length polyhydrox-
yalkanoates (scl-PHA) content and composition. The method was applied to both single strains and
microbial mixed cultures (MMC) fed with different carbon sources.
The IVT procedure provided similar analytical performances compared to previous Py-GCâMS and Py-
GC-FID methods, suggesting a similar application for PHA quantitation in bacterial cells. Results from the
IVT procedure and the traditional methanolysis method were compared; the correlation between the
two datasets was
fit for the purpose, giving a R2 of 0.975. In search of further simplification, the rationale
of IVT was exploited for the development of a âfield methodâ based on the titration of thermolyzed
samples with sodium hydrogen carbonate to quantify PHA inside bacterial cells. The accuracy of the IVT
method was
fit for the purpose.
These results lead to the possibility for the on-line measurement of PHA productivity. Moreover, they
allow for the fast and inexpensive quantification/characterization of PHA for biotechnological process
control, as well as investigation over various bacterial communities and/or feeding strategies.mixedF. Abbondanzi; G. Biscaro; G. Carvalho; L. Favaro; P. Lemos; M. Paglione; C. SamorĂŹ; C. TorriF. Abbondanzi; G. Biscaro; G. Carvalho; L. Favaro; P. Lemos; M. Paglione; C. SamorĂŹ; C. Torr
New results in 3D-mesomechanical coupled analysis of external sulphate attack in concrete
External Sulphate Attack (ESA) is one of the main degradation processes affecting concrete structures. It takes place when the concrete is in an environment rich in sulphate ions and with a high humidity index. Once it has penetrated the concrete, sulphate undergoes chemical reactions that lead to the precipitation of expansive ettringite crystals that cause volumetric expansions of the cement paste/mortar, eventually leading to cracking and damage. The FE analysis is undertaken by representing concrete as composed by aggregate pieces inserted in a cement/mortar matrix. Zero-thickness interface elements are pre-inserted to represent potential fractures along all aggregate-matrix as well as along some selected matrix-matrix element contacts. An existing fracture-based non-linear constitutive law is used for the interface elements. Concerning the reactive transport problem, the model follows previous work in the same research group, which combined an older approach from the literature for the continuum medium, with interface elements in the context of meso-mechanical analysis of concrete specimens in 2D, as well as initial work in 3D (but no coupling). In the present paper, the effects of the coupling between mechanical and diffusion/reaction in 3D are introduced and demonstrated. The new results obtained confirm that, also in 3D, penetration of ions, expansive reactions as well as subsequent cracking and degradation, all take place much faster when the coupling effect due to the open interfaces is introduced.This research is supported by grants BIA2016-76543-R from MEC (Madrid), which includes FEDER funds, and 2017SGR-1153 from AGAUR (Generalitat de Catalunya, Barcelona).Postprint (published version
Interactions Between the Amazonian Rainforest and Cumuli Clouds: A LargeâEddy Simulation, HighâResolution ECMWF, and Observational Intercomparison Study
The explicit coupling at meter and second scales of vegetation's responses to the atmosphericâboundary layer dynamics drives a dynamic heterogeneity that influences canopyâtop fluxes and cloud formation. Focusing on a representative day during the Amazonian dry season, we investigate the diurnal cycle of energy, moisture and carbon dioxide at the canopy top, and the transition from clear to cloudy conditions. To this end, we compare results from a largeâeddy simulation technique, a highâresolution global weather model, and a complete observational data set collected during the GoAmazon14/15 campaign. The overall modelâobservation comparisons of radiation and canopyâtop fluxes, turbulence, and cloud dynamics are very satisfactory, with all the modeled variables lying within the standard deviation of the monthly aggregated observations. Our analysis indicates that the timing of the change in the daylight carbon exchange, from a sink to a source, remains uncertain and is probably related to the stomata closure caused by the increase in vapor pressure deficit during the afternoon. We demonstrate quantitatively that heat and moisture transport from the subcloud layer into the cloud layer are misrepresented by the global model, yielding low values of specific humidity and thermal instability above the cloud base. Finally, the numerical simulations and observational data are adequate settings for benchmarking more comprehensive studies of plant responses, microphysics, and radiation
THE GREEN OCEAN AMAZON EXPERIMENT (GOAMAZON2014/5) OBSERVES POLLUTION AFFECTING GASES, AEROSOLS, CLOUDS, AND RAINFALL OVER THE RAIN FOREST
The susceptibility of air quality, weather, terrestrial ecosystems, and climate to human activities was investigated in a tropical environment.Peer reviewe
Substratos e tempo de renovação da ågua residuåria no crescimento do girassol ornamental em sistema semi-hidroponia
Stability of the pigmentation of egg yolks enriched with omega-3 and carophyll stored at room temperature and under refrigeration
Dust in Supernovae and Supernova Remnants I : Formation Scenarios
Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe
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