271 research outputs found
Rotura bilateral y simultánea del tendón de Aquiles
La rotura bilateral y simultánea del tendón de Aquiles es un hecho excepcional. La producción de
esta lesión en una persona joven, sin antecedentes patológicos ni de administración de ciertos medicamentos es aún
más excepcional. El tratamiento quirúrgico y un adecuado proceso de seguimiento y rehabilitación contribuyen a una
buena recuperación y pronóstico en los individuos jóvenes y activos con roturas del tendón de Aquiles. Se presenta
un caso clínico de una mujer de 21 años tratada quirúrgicamente con buen resultado.The bilateral and simultaneous rupture of Achilles tendon is an excepcional situation. The production
of this injury in a young person, without history pathological or administration of certain drugs is even more
exceptional. The surgical treatment and a proper process of following-up and rehabilitation help to a good recovery
and prognosis in young and active people with Achilles tendon ruptures
Manufacture of Carbon Materials with High Nitrogen Content
Nowadays one of the biggest challenges for carbon materials is their use in CO2 capture and their use as electrocatalysts in the oxygen reduction reaction (ORR). In both cases, it is necessary to dope the carbon with nitrogen species. Conventional methods to prepare nitrogen doped carbons such as melamine carbonization or NH3 treatment generate nitrogen doped carbons with insufficient nitrogen content. In the present research, a series of activated carbons derived from MOFs (ZIF-8, ZIF-67) are presented. Activated carbons have been prepared in a single step, by pyrolysis of the MOF in an inert atmosphere, between 600 and 1000 °C. The carbons have a nitrogen content up to 20 at.% and a surface area up to 1000 m2/g. The presence of this nitrogen as pyridine or pyrrolic groups, and as quaternary nitrogen are responsible for the great adsorption capacity of CO2, especially the first two. The presence of Zn and Co generates very different carbonaceous structures. Zn generates a greater porosity development, which makes the doped carbons ideal for CO2 capture. Co generates more graphitized doped carbons, which make them suitable for their use in electrochemistry.Authors acknowledge financial support by MINECO (Spain) through the project MAT2017-86992-R and “Ministerio de Ciencia e Innovación” (PID2020-116998RB-I00)
The characterization of a LDPE affected by different levels of water tree degradation using absorption current measurements
U B V R I Photometry of Stellar Structures throughout the Disk of the Barred Galaxy NGC 3367
We report new detailed surface U, B, V, R, and I photometry of 81 stellar
structures in the disk of the barred galaxy NGC 3367. The images show many
different structures indicating that star formation is going on in the most
part of the disk. NGC 3367 is known to have a very high concentration of
molecular gas distribution in the central regions of the galaxy and bipolar
synchrotron emission from the nucleus with two lobes (at 6 kpc) forming a
triple structure similar to a radio galaxy. We have determined the U, B, V, R,
and I magnitudes and U - B, B - V, U - V, and V - I colors for the central
region (nucleus), a region which includes supernovae 2003 AA, and 79 star
associations throughout NGC 3367. Estimation of ages of star associations is
very difficult due to several factors, among them: filling factor, metallicity,
spatial distribution of each structure and the fact that we estimated the
magnitudes with a circular aperture of 16 pixels in diameter, equivalent to
kpc. However, if the colors derived for NGC 3367 were similar to
the colors expected of star clusters with theoretical evolutionary star tracks
developed for the LMC and had a similar metallicity, NGC 3367 show 51 percent
of the observed structures with age type SWB I (few tens of Myrs), with seven
sources outside the bright surface brightness visible disk of NGC 3367.Comment: Accepted for publication (abr 2007) in The Astronomical Journal (July
2007 issue
Aerogel-based metasurfaces for perfect acoustic energy absorption
[EN] The unusual viscoelastic properties of silica aerogel plates are efficiently used to design subwavelength perfect sound absorbers. We theoretically, numerically and experimentally report a perfect absorbing metamaterial panel made of periodically arranged resonant building blocks consisting of a slit loaded by a clamped aerogel plate backed by a closed cavity. The impedance matching condition is analyzed using the Argand diagram of the reflection coefficient, i.e., the trajectory of the reflection coefficient as a function of frequency in the complex plane. The lack or excess of losses in the system can be identified via this Argrand diagram in order to achieve the impedance matching condition. The universality of this tool can be further exploited to design more complex metasurfaces for perfect sound absorption, thus allowing the rapid design of novel and efficient absorbing metamaterials.This work was funded by the RFI Le Mans Acoustique, Region Pays de la Loire. This article is based upon work from COST Action DENORMS CA15125, supported by COST (European Cooperation in Science and Technology). N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD/2017/042. J.-P.G and V.R.G. gratefully acknowledge the ANR-RGC METARoom (No. ANR-18-CE08-0021) project and the HYPERMETA project funded under the program Etoiles Montantes of the Region Pays de la Loire. J.S-D. acknowledges the support of the Ministerio de Economia y Competitividad of the Spanish government and the European Union FEDER through Project No. TEC2014-53088-C3-1-RFernandez-Marin, AA.; Jimenez, N.; Groby, J.; Sánchez-Dehesa Moreno-Cid, J.; Romero García, V. (2019). Aerogel-based metasurfaces for perfect acoustic energy absorption. Applied Physics Letters. 115(6):061901-1-061901-5. https://doi.org/10.1063/1.5109084S061901-1061901-51156Gesser, H. D., & Goswami, P. C. (1989). Aerogels and related porous materials. 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