249 research outputs found
Development and validation of a capillary electrophoresis method for direct measurement of isocitric, citric, tartaric and malic acids as adulteration markers in orange juice
Abstract Fruit juices each have very distinct organic acids profiles that can be used as fingerprints for establishing authenticity. A method has been developed, optimised and validated for measuring by capillary electrophoresis citric, isocitric, malic and tartaric acids as authenticity markers in orange juices, without any sample treatment other than dilution and filtration. Final conditions were phosphate buffer 200 mM, pH 7.50, 214 kV as applied potential, and 57 cm length neutral capillary. Detection was direct UV at 200 nm. Different kinds and marks of orange juice, chosen from the great variety existent in the market, were analysed and clear differences could be found between them and just pressed orange juice
Role of Upwelling on Larval Dispersal and Productivity of Gooseneck Barnacle Populations in the Cantabrian Sea: Management Implications
The effect of coastal upwelling on the recruitment and connectivity of
coastal marine populations has rarely been characterized to a level of detail
to be included into sound fishery management strategies. The gooseneck barnacle
(Pollicipes pollicipes) fishery at the Cantabrian Coast (Northern Spain) is
located at the fringes of the NW Spanish Upwelling system. This fishery is
being co-managed through a fine-scale, interspersed set of protected rocks
where each rock receives a distinct level of protection. Such interspersion is
potentially beneficial, but the extent to which such spacing is consistent with
mean larval dispersal distances is as yet unknown. We have simulated the spread
of gooseneck barnacle larvae in the Central Cantabrian Coast using a
high-resolution time-series of current profiles measured at a nearshore
location. During a year of high upwelling activity (2009), theoretical
recruitment success was 94% with peak recruitment predicted 56 km west of the
emission point. However, for a year of low upwelling activity (2011)
theoretical recruitment success dropped to 15.4% and peak recruitment was
expected 13 km east of the emission point. This is consistent with a positive
correlation between catch rates and the Integrated Upwelling Index, using a
4-year lag to allow recruits to reach commercial size. Furthermore, a net
long-term westward larval transport was estimated by means of mitochondrial
cytochrome c oxidase subunit I (COI) sequences for five populations in the
Cantabrian Sea. Our results call into question the role of long distance
dispersal, driven by the mesoscale processes in the area, in gooseneck barnacle
populations and point to the prevalent role of small-scale, asymmetric
connectivity more consistent with the typical scale of the co-management
process in this fishery
Tailoring nanostructured surfaces with plasmonic/magnetic multifunctional response
IIn this work, we present an innovative way to functionalize large surfaces combining both plasmonic and magnetic nanoparticles on a substrate, by the growth of bilayers and a subsequent single annealing. In particular, we show here the formation of Au and gamma- FeâOâ nanoparticles using this route. Thermal treatments promote the nanostructuration of the film plus a partial oxidation of Fe to form ferrimagnetic oxides. For this purpose, annealing conditions and the structure of the bilayer must be selected to achieve an optimal nanostructuration, avoiding the full oxidation of Fe to form antiferromagnetic hematite. Published by AIP Publishing
Universal Scaling of Ballistic Magnetoresistance in Magnetic Nanocontacts
We show that ballistic magnetoresistance exhibits universal scaling in atomic or nanometer scale
contacts. Plotting the data as conductance, we find that, if the maximum magnetoconductance is
normalized to unity and the conductance is scaled with the conductivity of the bulk material, the data
fall in a narrow region, independent of the nanocontact materials, for our four data sets and four from
the literature. The results agree with a theory that takes into account spin-scattering within a magneticdomain
wall
GaAs:Mn nanowires grown by molecular beam epitaxy of (Ga,Mn)As at MnAs segregation conditions
GaAs:Mn nanowires were obtained on GaAs(001) and GaAs(111)B substrates by
molecular beam epitaxial growth of (Ga,Mn)As at conditions leading to MnAs
phase separation. Their density is proportional to the density of catalyzing
MnAs nanoislands, which can be controlled by the Mn flux and/or the substrate
temperature. Being rooted in the ferromagnetic semiconductor (Ga,Mn)As, the
nanowires combine one-dimensional properties with the magnetic properties of
(Ga,Mn)As and provide natural, self assembled structures for nanospintronics.Comment: 13 pages, 6 figure
Shell model half-lives for r-process N=82 nuclei
We have performed shell-model calculations of the half-lives and
neutron-branching probabilities of the r-process waiting point nuclei at the
magic neutron number N=82. These new calculations use a larger model space than
previous shell model studies and an improved residual interaction which is
adjusted to recent spectroscopic data around A=130. Our shell-model results
give a good account of all experimentally known half-lives and -values
for the N=82 r-process waiting point nuclei. Our half-life predictions for the
N=82 nuclei with Z=42--46 agree well with recent estimates based in the
energy-density functional method
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory
The advent of the Auger Engineering Radio Array (AERA) necessitates the
development of a powerful framework for the analysis of radio measurements of
cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air
shower radio emission in coincidence with the surface particle detectors and
fluorescence telescopes of the Pierre Auger Observatory, the radio analysis
functionality had to be incorporated in the existing hybrid analysis solutions
for fluoresence and surface detector data. This goal has been achieved in a
natural way by extending the existing Auger Offline software framework with
radio functionality. In this article, we lay out the design, highlights and
features of the radio extension implemented in the Auger Offline framework. Its
functionality has achieved a high degree of sophistication and offers advanced
features such as vectorial reconstruction of the electric field, advanced
signal processing algorithms, a transparent and efficient handling of FFTs, a
very detailed simulation of detector effects, and the read-in of multiple data
formats including data from various radio simulation codes. The source code of
this radio functionality can be made available to interested parties on
request.Comment: accepted for publication in NIM A, 13 pages, minor corrections to
author list and references in v
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