496 research outputs found
Estudio geológico del Eoceno prepirenaico del Ripollés oriental
The main results of the geological study of folded Pre-pyrenean Eocene (Ripollés Oriental area, Gerona and Barcelona piovinces) are presented in this paper. An interpretative section of the sedimentary basin as well as the age and genesis of the different litliological units are given. It is also discussed the origin of the tectonic structures
Piezo-generated charge mapping revealed through Direct Piezoelectric Force Microscopy
While piezoelectrics and ferroelectrics are playing a key role in many
everyday applications, there are still a number of open questions related to
the physics of those materials. In order to foster the understanding of
piezoelectrics and ferroelectric and pave the way to future applications, the
nanoscale characterization of these materials is essential. In this light, we
have developed a novel AFM based mode that obtains a direct quantitative
analysis of the piezoelectric coefficient d33. This nanoscale tool is capable
of detecting and reveal piezo-charge generation through the direct
piezoelectric effect at the surface of the piezoelectric and ferroelectric
materials. We report the first nanoscale images of the charge generated in a
thick single crystal of Periodically Poled Lithium Niobate (PPLN) and a Bismuth
Ferrite (BiFO3) thin film by applying a force and recording the current
produced by the materials. The quantification of both d33 coefficients for PPLN
and BFO are 13 +- 2 pC/N and 46 +- 7 pC/N respectively, in agreement with the
values reported in the literature. This new mode can operate simultaneously
with PFM mode providing a powerful tool for the electromechanical and
piezo-charge generation characterization of ferroelectric and piezoelectric
materials
Phylogenetic characterization and quantification of ammonia-oxidizing archaea and bacteria from Lake Kivu in a long-term microcosm incubation
A microcosm cultivation-based method was set up to investigate the growth of ammonia-oxidizing archaea (AOA), isolated from a water sample acquired at a depth of 50 m from the northern basin of Lake Kivu. For this purpose, both CARD-FISH and qPCR targeting of archaeal 16S rRNA and amoA genes were used. Archaeal cell growth at the end of the 246-day microcosm experiment accounted for 35 % of the SybrGold-stained cells, which corresponded to 6.61 × 106 cells/ml and 1.76 ± 0.09 × 106 archaeal 16S rRNA gene copies/ml. Clone libraries and DGGE fingerprinting confirmed the dominance of AOA phylotypes in the archaeal community microcosm. The majority of the identified archaeal 16S rRNA gene sequences in the clone libraries were affiliated with Thaumarchaeota Marine Group 1.1a. Subsequent cultivation of the AOA community on deep-well microtiter plates in medium containing different carbon sources to stimulate archaeal growth failed to show significant differences in archaeal abundance (ANOVA t14 = –1.058, P = 0.308 and ANOVA t14 = 1.584, P = 0.135 for yeast extract and simple organic acids, respectively). The lack of growth stimulation by organic compounds is in concordance with the oligotrophic status of Lake Kivu. Finally, the addition of antibiotics to the growth medium resulted in archaeal cell counts that were significantly lower than those obtained from cultures in antibiotic-free medium (ANOVA t14 = 12.12, P < 0.001). [Int Microbiol 2013; 16(3):177-189]Keywords: ammonia-oxidizing archaea and bacteria · ammonia monooxygenase alpha subunit (amoA) · Lake Kivu ·microcosm · multi-color CARD-FIS
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