6,792 research outputs found
On the Balance of Intercalation and Conversion Reactions in Battery Cathodes
We present a thermodynamic analysis of the driving forces for intercalation
and conversion reactions in battery cathodes across a range of possible working
ion, transition metal, and anion chemistries. Using this body of results, we
analyze the importance of polymorph selection as well as chemical composition
on the ability of a host cathode to support intercalation reactions. We find
that the accessibility of high energy charged polymorphs in oxides generally
leads to larger intercalation voltages favoring intercalation reactions,
whereas sulfides and selenides tend to favor conversion reactions. Furthermore,
we observe that Cr-containing cathodes favor intercalation more strongly than
those with other transition metals. Finally, we conclude that two-electron
reduction of transition metals (as is possible with the intercalation of a
ion) will favor conversion reactions in the compositions we studied
Trends of influenza B during the 2010–2016 seasons in 2 regions of north and south Italy: The impact of the vaccine mismatch on influenza immunisation strategy
Influenza A and B viruses are responsible for respiratory infections, representing globally seasonal threats to human health. The 2 viral types often co-circulate and influenza B plays an important role in the spread of infection. A 6-year retrospective surveillance study was conducted between 2010 and 2016 in 2 large administrative regions of Italy, located in the north (Liguria) and in the south (Sicily) of the country, to describe the burden and epidemiology of both B/Victoria and B/Yamagata lineages in different healthcare settings. Influenza B viruses were detected in 5 of 6 seasonal outbreaks, exceeding influenza A during the season 2012–2013. Most of influenza B infections were found in children aged ≤ 14 y and significant differences were observed in the age-groups infected by the different lineages. B/Victoria strains prevailed in younger population than B/Yamagata, but also were more frequently found in the community setting. Conversely, B/Yamagata viruses were prevalent among hospitalized cases suggesting their potential role in the development of more severe disease. The relative proportions of viral lineages varied from year to year, resulting in different lineage-level mismatch for the B component of trivalent influenza vaccine. Our findings confirmed the need for continuous virological surveillance of seasonal epidemics and bring attention to the adoption of universal influenza immunization program in the childhood. The use of tetravalent vaccine formulations may be useful to improve the prevention and control of the influenza burden in general population
Comparison between the results of a new version of the AVACTA II atmospheric diffusion model and tracer experiments
A new version of the AVACTA II code (a code recommended by EPA) has been implemented and evaluated. AVACTA II is a code based on a mixed segmentpuff approach, which allows numerical simulations of both non-stationary and nonhomogeneous conditions. In our version, the wind field is calculated through the 3D mass-consistent code WINDS developed at the Department of Physics of the University
of Genoa, Italy. The model evaluation of this new version of the AVACTA II code has been performed using field experiment data on flat, but rough, terrain (Karlsruhe
Nuclear Research Center (KNRC) tracer experiments) and wind tunnel measurements(EPA Rushil experiments) both in flat and complex terrain. A comparison is made between
simulated and measured concentration distributions. The results of these evaluations are very encouraging
Surfactant-like Effect and Dissolution of Ultrathin Fe Films on Ag(001)
The phase immiscibility and the excellent matching between Ag(001) and
Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field
of low dimensionality magnetic systems. Intermixing could be drastically
limited at deposition temperatures as low as 140-150 K. The film structural
evolution induced by post-growth annealing presents many interesting aspects
involving activated atomic exchange processes and affecting magnetic
properties. Previous experiments, of He and low energy ion scattering on films
deposited at 150 K, indicated the formation of a segregated Ag layer upon
annealing at 550 K. Higher temperatures led to the embedding of Fe into the Ag
matrix. In those experiments, information on sub-surface layers was attained by
techniques mainly sensitive to the topmost layer. Here, systematic PED
measurements, providing chemical selectivity and structural information for a
depth of several layers, have been accompanied with a few XRD rod scans,
yielding a better sensitivity to the buried interface and to the film long
range order. The results of this paper allow a comparison with recent models
enlightening the dissolution paths of an ultra thin metal film into a different
metal, when both subsurface migration of the deposit and phase separation
between substrate and deposit are favoured. The occurrence of a surfactant-like
stage, in which a single layer of Ag covers the Fe film is demonstrated for
films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the
formation of two Ag capping layers is also reported. As the annealing
temperature was increased beyond 700 K, the surface layers closely resembled
the structure of bare Ag(001) with the residual presence of subsurface Fe
aggregates.Comment: 4 pages, 3 figure
On the curvature in logarithmic plots of rate coefficients for chemical reactions
In terms of the reduced potential energy barrier ζ = ΔuTS/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e-ζ. The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of Euler Q(a,ζ) = Γ(a,ζ)/Γ(a), with a being the number of modes coupled to the reaction coordinate. In this work, the experimental rate coefficients at various temperatures for several chemical reactions were fitted to the theoretical expression in terms of Q(a,ζ) to determine the extent of its validity and generality. The new expression affords lower deviations from the experimental points in 29 cases out of 38 and it accounts for the curvature in the logarithmic plots of rate coefficients versus inverse temperature. In the absence of tunneling, conventional theories predict the curvature of these plots to be identically zero
Unlocking the Inaccessible Energy Density of Sodium Vanadium Fluorophosphate Electrode Materials by Transition Metal Mixing
Sodium (Na) vanadium (V) fluorophosphate (NVPF)
is a highly attractive intercalation electrode material due to its high
operation voltage, large capacity, and long cycle life. However, several issues
limit the full utilization of NVPF's energy density: 1) the high voltage
plateau associated with extracting the "third" Na ion in the reaction NVPF
VPF (~4.9 V vs Na/Na) appears above the electrochemical
stability window of most practical electrolytes (~4.5 V); 2) a sudden drop in
Na-ion diffusivity is observed near composition .
Therefore, it is important to investigate the potential substitution of V by
other transition metals in NVPF derivatives, which can access the extraction of
the third Na-ion. In this work, we investigate the partial substitution of V
with molybdenum (Mo), niobium (Nb), or tungsten (W) in NVPF to improve its
energy density. We examine the structural and electrochemical behaviors of
, ,
and across the whole Na composition region of 0
x 4, and at various transition metal substitution levels, namely,
y=0.5, 1.0, 1.5, 2.0 for Mo, and y=1.0, 2.0 for Nb. We find that partial
substitution of 50% V by Mo in NVPF reduces the voltage plateau for extracting
the third Na ion by 0.6 Volts, which enables further Na extraction from
and increases the theoretical gravimetric
capacity from ~128 to ~174 mAh/g. Analysis of the migration barriers for
Na-ions in unveils improved kinetic properties
over NVPF. The proposed material provides an
optimal gravimetric energy density of ~577.3 Wh/kg versus ~507 Wh/kg for the
pristine NVPF, which amounts to an increase of ~13.9%
Level-3 Calorimetric Resolution available for the Level-1 and Level-2 CDF Triggers
As the Tevatron luminosity increases sophisticated selections are required to
be efficient in selecting rare events among a very huge background. To cope
with this problem, CDF has pushed the offline calorimeter algorithm
reconstruction resolution up to Level 2 and, when possible, even up to Level 1,
increasing efficiency and, at the same time, keeping under control the rates.
The CDF Run II Level 2 calorimeter trigger is implemented in hardware and is
based on a simple algorithm that was used in Run I. This system has worked well
for Run II at low luminosity. As the Tevatron instantaneous luminosity
increases, the limitation due to this simple algorithm starts to become clear:
some of the most important jet and MET (Missing ET) related triggers have large
growth terms in cross section at higher luminosity. In this paper, we present
an upgrade of the Level 2 Calorimeter system which makes the calorimeter
trigger tower information available directly to a CPU allowing more
sophisticated algorithms to be implemented in software. Both Level 2 jets and
MET can be made nearly equivalent to offline quality, thus significantly
improving the performance and flexibility of the jet and MET related triggers.
However in order to fully take advantage of the new L2 triggering capabilities
having at Level 1 the same L2 MET resolution is necessary. The new Level-1 MET
resolution is calculated by dedicated hardware. This paper describes the
design, the hardware and software implementation and the performance of the
upgraded calorimeter trigger system both at Level 2 and Level 1.Comment: 5 pages, 5 figures,34th International Conference on High Energy
Physics, Philadelphia, 200
Self-Organized Nanorod Arrays for Large-Area Surface-Enhanced Infrared Absorption
Capabilities of highly sensitive surface-enhanced infrared absorption (SEIRA) spectroscopy are demonstrated by exploiting large-area templates (cm2) based on self-organized (SO) nanorod antennas. We engineered highly dense arrays of gold nanorod antennas featuring polarization-sensitive localized plasmon resonances, tunable over a broadband near- and mid-infrared (IR) spectrum, in overlap with the so-called "functional group" window. We demonstrate polarization-sensitive SEIRA activity, homogeneous over macroscopic areas and stable in time, by exploiting prototype self-assembled monolayers of IR-active octadecanthiol (ODT) molecules. The strong coupling between the plasmonic excitation and molecular stretching modes gives rise to characteristic Fano resonances in SEIRA. The SO engineering of the active hotspots in the arrays allows us to achieve signal amplitude improved up to 5.7%. This figure is competitive to the response of lithographic nanoantennas and is stable when the optical excitation spot varies from the micro- to macroscale, thus enabling highly sensitive SEIRA spectroscopy with cost-effective nanosensor devices
Effects of environmental variables on the distribution of juvenile cubomedusae Carybdea marsupialis in the coastal Western Mediterranean
[EN] Relationships between environmental factors and oscillations in jellyfish abundance, especially in the early life stages, could help to interpret past increases and also predict scenarios in a changing future. For the first time, we present cubozoan spatial and temporal distributions in the earliest stages and their relationships with different factors. Abundances ofCarybdea marsupialismedusae showed high interannual variability from 2008 to 2014 along the Denia coast (SE Spain, W Mediterranean). During 2015, samples were collected from 11 beaches along 17 km of coastline, 8 times from January to November in order to determine the effects of environmental factors on the distribution of juvenileC.marsupialis. Juveniles (<= 15 mm diagonal bell width) were present from May to July, with more sampled near shore (0-15 m). Most of them occurred in June when their numbers were unequal among beaches (average 0.05 ind m(-3), maximum 6.71 ind m(-3)). We tested distributions of juveniles over time and space versus temperature, salinity, nutrients (N, P and Si), chlorophyll-a(Chl-a), and zooplankton abundance. Temperature and cladocerans (zooplankton group) were significantly positively correlated with juvenile distribution, whereas Chl-aconcentration was weakly negative. By contrast, in 2014, high productivity areas (Chl-aand zooplankton) overlapped the maximum adult abundance (5.2 ind m(-3)). The distribution of juveniles during 2015 did not spatially coincide with the areas where ripe adults were located the previous year, suggesting that juveniles drift with the currents upon release from the cubopolyps. Our results yield important insights into the complexity of cubozoan distributions.This study has received funding through European Commission's LIFE programme [LIFE08 NAT ES64 CUBOMED.eu to C.B. from the Alicante University and V.L.F. from the Institute of Marine Science, CSIC, Spain], and from the D.G Sostenibilidad de la Costa y el Mar from the Spanish Ministry of Agriculture, Food and the Environment, the Fundacion Biodiversidad, and the D.G. Agua -Generalitat Valenciana. It has also received support from Parques Nacionales and Ajuntament de Denia.
We are grateful for the collaboration of Fundació Baleària, Marina El Portet de Dénia and Marina de Dénia. This work is a contribution from the ¿Ramon Margalef¿ Environmental Research Institute (IMEM) from the University of Alicante, Spain. We are especially grateful for the sampling and laboratory support provided in the Montgó Research Station by NGO ACIF Marina Alta volunteers: Ángela Alba, Ainara Ballesteros, Miguel Escolano, Ángel Fernández, Marta Gil, Héctor Gutiérrez, Ainara Lacalle and Alba Pérez. We would also like to extend our thanks to Jordi Alventosa and Júlia Escrivá from IGIC-Polytechnic Valencia University for their contribution to nutrient analysis. Editing services were provided by Sea Pen Scientific Writing.Bordehore, C.; Fonfría, E.; Alonso, C.; Rubio-Tortosa, B.; Acevedo, M.; Canepa, A.; Falco, S.... (2020). Effects of environmental variables on the distribution of juvenile cubomedusae Carybdea marsupialis in the coastal Western Mediterranean. 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