1,742 research outputs found
Reaction-diffusion equations: a chemical application
Obtenemos soluciones exactas para un sistema de reacción-difusión asociado a una reacción cubica autocatalítica entre dos sustancias químicas según la regla con tasa . Para obtener dichas soluciones empleamos una transformación de onda
Temperature-Sensitive Gels for Intratumoral Delivery of β-Lapachone: Effect of Cyclodextrins and Ethanol
This work evaluated the potential of Pluronics (varieties F127 and P123) in combination with solubilizing agents to be used as syringeable in situ gelling depots of intratumoral β-lapachone (βLAP). Pluronic dispersions prepared at various concentrations in the absence and the presence of ethanol and randomly methylated β-cyclodextrin (RMβCD) were characterized regarding their rheological properties, drug solubilization capacity, and in vitro release. Pluronic F127 (18–23%) formulations combined high ability to solubilize βLAP (enhancement solubility factor up to 50), adequate gel temperature range (over 25°C), and gel strength at 37°C enough to guarantee the permanence of the formulation in the administration site for a period of time. βLAP release rate was finely tuned by the concentration of the polymer and the addition of RMβCD (diffusion coefficient ranging between 9 and 69 μg·cm−2). The ethanol increases βLAP release rate but simultaneously led to weak gels. This paper shows that βLAP formulations involving temperature-reversible Pluronic gels may be suitable for intratumoral drug delivery purposes
Quantum Zeno and anti-Zeno effects in surface diffusion of interacting adsorbates
Surface diffusion of interacting adsorbates is here analyzed within the
context of two fundamental phenomena of quantum dynamics, namely the quantum
Zeno effect and the anti-Zeno effect. The physical implications of these
effects are introduced here in a rather simple and general manner within the
framework of non-selective measurements and for two (surface) temperature
regimes: high and very low (including zero temperature). The quantum
intermediate scattering function describing the adsorbate diffusion process is
then evaluated for flat surfaces, since it is fully analytical in this case.
Finally, a generalization to corrugated surfaces is also discussed. In this
regard, it is found that, considering a Markovian framework and high surface
temperatures, the anti-Zeno effect has already been observed, though not
recognized as such.Comment: 17 pages, 1 figur
Cross-species infectivity of H3N8 influenza virus in an experimental infection in swine
Avian influenza A viruses have gained increasing attention due to their ability to cross the species barrier and cause severe disease
in humans and other mammal species as pigs. H3 and particularly H3N8 viruses, are highly adaptive since they are found in
multiple avian and mammal hosts. H3N8 viruses have not been isolated yet from humans; however, a recent report showed that
equine influenza A viruses (IAVs) can be isolated from pigs, although an established infection has not been observed thus far in
this host. To gain insight into the possibility of H3N8 avian IAVs to cross the species barrier into pigs, in vitro experiments and
an experimental infection in pigs with four H3N8 viruses from different origins (equine, canine, avian, and seal) were performed.
As a positive control, an H3N2 swine influenza virus A was used. Although equine and canine viruses hardly replicated
in the respiratory systems of pigs, avian and seal viruses replicated substantially and caused detectable lesions in inoculated pigs
without previous adaptation. Interestingly, antibodies against hemagglutinin could not be detected after infection by hemagglutination
inhibition (HAI) test with avian and seal viruses. This phenomenon was observed not only in pigs but also in mice immunized
with the same virus strains. Our data indicated that H3N8 IAVs from wild aquatic birds have the potential to cross the
species barrier and establish successful infections in pigs that might spread unnoticed using the HAI test as diagnostic tool.We thank Jaime Maldonado and HIPRA (Spain) for the A/Swine/Spain/
54008/2004 (H3N2) strain, Edward J. Dubovi and Cornell University for
the A/Canine/NY/105447/08 (H3N8) IAV strain, T. M. Chambers and the
University of Kentucky for the A/Equine/OH/1/03 (H3N8) IAV strain,
and Hon Ip and the U.S. Geological Survey National Wildlife Health
Center for the A/American black duck/Maine/44411-532/2008 (H3N8)
and the A/Harbor Seal/New Hampshire/179629/2011 (H3N8) IAV
strains. We thank Sergio López, David Solanes, Francisco X. Abad, Jordi
Alberola, Jaume Martorell, and Eduard J. Cunilleras for help in providing
different samples and during the experimental infections, as well as the
personnel in Cat3 laboratories and the animal house. We thank Adolfo
García-Sastre for providing materials and for support as the principal
investigator of the NIAID-funded Center for Research in Influenza Pathogenesis
(HHSN266200700010C).
The research leading to these results received funding from the European
Community’s Seventh Framework Programme (FP7, 2007-2013),
the Research Infrastructures Action under grant FP7-228393 (a NADIR
project), and projects AGL2010-22200-C02-01 and AGL2007-60274 of
the Spanish Ministry of Science and Innovation
The complex structure of HH 110 as revealed from Integral Field Spectroscopy
HH 110 is a rather peculiar Herbig-Haro object in Orion that originates due
to the deflection of another jet (HH 270) by a dense molecular clump, instead
of being directly ejected from a young stellar object. Here we present new
results on the kinematics and physical conditions of HH 110 based on Integral
Field Spectroscopy. The 3D spectral data cover the whole outflow extent (~4.5
arcmin, ~0.6 pc at a distance of 460 pc) in the spectral range 6500-7000 \AA.
We built emission-line intensity maps of H, [NII] and [SII] and of
their radial velocity channels. Furthermore, we analysed the spatial
distribution of the excitation and electron density from [NII]/H,
[SII]/H, and [SII] 6716/6731 integrated line-ratio maps, as well as
their behaviour as a function of velocity, from line-ratio channel maps. Our
results fully reproduce the morphology and kinematics obtained from previous
imaging and long-slit data. In addition, the IFS data revealed, for the first
time, the complex spatial distribution of the physical conditions (excitation
and density) in the whole jet, and their behaviour as a function of the
kinematics. The results here derived give further support to the more recent
model simulations that involve deflection of a pulsed jet propagating in an
inhomogeneous ambient medium. The IFS data give richer information than that
provided by current model simulations or laboratory jet experiments. Hence,
they could provide valuable clues to constrain the space parameters in future
theoretical works.Comment: 12 pages, 15 figures Accepted in MNRA
Two-bath model for activated surface diffusion of interacting adsorbates
The diffusion and low vibrational motions of adsorbates on surfaces can be
well described by a purely stochastic model, the so-called interacting single
adsorbate model, for low-moderate coverages (\theta \lesssim 0.12). Within this
model, the effects of thermal surface phonons and adsorbate-adsorbate
collisions are accounted for by two uncorrelated noise functions which arise in
a natural way from a two-bath model based on a generalization of the one-bath
Caldeira-Leggett Hamiltonian. As an illustration, the model is applied to the
diffusion of Na atoms on a Cu(001) surface with different coverages.Comment: 7 pages, 3 figure
Coeficientes polinomiales para funciones límite de series de potencias, una analogía con el triangulo de pascal.
En este trabajo se muestra un resultado sobre los coeficientes de las funciones poli nómicas hacia las cuales convergen cierto tipo de series infinitas. Dicho resultado está relacionado con una forma encontrada para hallar estos coeficientes y la demostración de su validez. La analogía que se pretende mostrar tiene que ver con la forma como estos coeficientes se distribuyen en un triángulo numérico, a la manera como los coeficientes binomiales lo hacen en el triángulo de Pascal
Suma n-ésima de los coeficientes polinomiales en una función generatriz
En este trabajo se muestra un resultado sobre los coeficientes de las funciones polinómicas hacia las cuales convergen cierto tipo de series infinitas. Dicho resultado está relacionado con una expresión para obtener la suma n-ésima de dichos coeficientes y la demostración de su validez
Suma n-ésima de los coeficientes polinomiales en una función generatriz
En este trabajo se muestra un resultado sobre los coeficientes de las funciones polinómicas hacia las cuales convergen cierto tipo de series infinitas. Dicho resultado está relacionado con una expresión para obtener la suma n-ésima de dichos coeficientes y la demostración de su validez
Suma n-ésima de los coeficientes polinomiales en una función generatriz
En este trabajo se muestra un resultado sobre los coeficientes de las funciones polinómicas hacia las cuales convergen cierto tipo de series infinitas. Dicho resultado está relacionado con una expresión para obtener la suma n-ésima de dichos coeficientes y la demostración de su validez
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