Search results for "Espectro"
showing 10 items of 142 documents
Evaluación del riesgo de la presencia de micotoxinas en piensos comercializados en España mediante métodos cromatográficos multidetección y alta reso…
2016
Las micotoxinas son metabolitos secundarios producidos por determinados hongos, y son contaminantes frecuentes de alimentos y piensos. Producen enfermedades, denominadas micotoxicosis, que pueden ser tanto agudas como crónicas en personas y animales. A nivel de salud humana afectan fundamentalmente al hígado, los riñones y el sistema inmune, mientras que sus efectos en salud animal son más variados, dependiendo de otros factores como la especie, la edad, etc. La Agencia Internacional de Investigación sobre el Cáncer (“International Agency for Research on Cancer”, IARC) ha clasificado las aflatoxinas como uno de los compuestos naturales con mayor potencial cancerígeno y teratógeno que existe…
Color study of historic silks
2022
The chemical characterization of silk textiles of historic value may be necessary to achieve a better understanding of the production processes applied, to evaluate their preservation, to detect manipulations or forgeries, and to value the combination of tradition and innovation in contemporary manufacturing techniques. The main objective of this work was to study four historical silks from the Garín collection, all of them from the 20th century, although with 19th century designs. To this end, non-invasive spectroscopic and microscopy techniques were applied in order to obtain information on the dyes used during their production and their link with those used in the silk industry in previo…
Multiple Decay Mechanisms and 2D-UV Spectroscopic Fingerprints of Singlet Excited Solvated Adenine-Uracil Monophosphate
2016
The decay channels of singlet excited adenine uracil monophosphate (ApU) in water are studied with CASPT2//CASSCF:MM potential energy calculations and simulation of the 2D-UV spectroscopic fingerprints with the aim of elucidating the role of the different electronic states of the stacked conformer in the excited state dynamics. The adenine 1La state can decay without a barrier to a conical intersection with the ground state. In contrast, the adenine 1Lb and uracil S(U) states have minima that are separated from the intersections by sizeable barriers. Depending on the backbone conformation, the CT state can undergo inter-base hydrogen transfer and decay to the ground state through a conical …
Multiparticle emission in the decay of Ar 31
2014
A multihit capacity setup was used to study the decay of the dripline nucleus 31Ar, produced at the ISOLDE facility at CERN. A spectroscopic analysis of the β-delayed three-proton decay of 31Ar is presented for the first time together with a quantitative analysis of the β-delayed 2pγ decay. A new method for determination of the spin of low-lying levels in the βp daughter 30S using proton-proton angular correlations is presented and used to determine that the spin of the 5.2-MeV level is most likely 3+ with 4+ also possible. The half-life of 31Ar is found to be 15.1(3) ms. An improved analysis of the Fermi β strength including the β3p-decay mode gives a total measured branching ratio of 3.60…
Phonons in single-layer and few-layer MoS2 and WS2
2011
We report ab initio calculations of the phonon dispersion relations of the single-layer and bulk dichalcogenides MoS2 and WS2. We explore in detail the behavior of the Raman-active modes A1g and E12g as a function of the number of layers. In agreement with recent Raman spectroscopy measurements [C. Lee et al., ACS Nano 4, 2695 (2010)], we find that the A1g mode increases in frequency with an increasing number of layers while the E12g mode decreases. We explain this decrease by an enhancement of the dielectric screening of the long-range Coulomb interaction between the effective charges with a growing number of layers. This decrease in the long-range part overcompensates for the increase of …
First glimpse of the $N=82$ shell closure below $Z=50$ from masses of neutron-rich cadmium isotopes and isomers
2020
We probe the $N=82$ nuclear shell closure by mass measurements of neutron-rich cadmium isotopes with the ISOLTRAP spectrometer at ISOLDE-CERN. The new mass of $^{132}$Cd offers the first value of the $N=82$, two-neutron shell gap below $Z=50$ and confirms the phenomenon of mutually enhanced magicity at $^{132}$Sn. Using the recently implemented phase-imaging ion-cyclotron-resonance method, the ordering of the low-lying isomers in $^{129}$Cd and their energies are determined. The new experimental findings are used to test large-scale shell-model, mean-field and beyond-mean-field calculations, as well as the ab initio valence-space in-medium similarity renormalization group.
Sizeable beta-strength in $^{31}$Ar (β3p) decay
2014
5 pags. ; 7 figs. ; Open Access funded by SCOAP3 - Sponsoring Consortium for Open Access Publishing in Particle Physics
High-pressure lattice-dynamics of NdVO4
2017
High-pressure Raman-scattering measurements and ab initio calculations on NdVO4 have been carried out up to 30 GPa. Our combined experimental and theoretical study confirms that beyond 5.9 GPa NdVO4 undergoes an irreversible zircon to monazite transition. The coexistence of zircon and monazite phases is experimentally observed up to ~8 GPa (which agrees with the theoretical transition pressure), stabilizing the monazite phase as a single phase around 10 GPa. Calculations additionally predict the existence of a second high-pressure phase transition at 12.4 GPa. This reversible phase transition has been experimentally observed beyond 18.1 GPa and remains stable up to 30 GPa. The post-monazite…
Optical phonon modes of wurtzite InP
2013
Optical vibration modes of InP nanowires in the wurtzite phase were investigated by Raman scattering spectroscopy. The wires were grown along the [0001] axis by the vapor-liquid-solid method. The A1(TO), E2h, and E1(TO) phonon modes of the wurtzite symmetry were identified by using light linearly polarized along different directions in backscattering configuration. Additionally, forbidden longitudinal optical modes have also been observed. Furthermore, by applying an extended 11-parameter rigid-ion model, the complete dispersion relations of InP in the wurtzite phase have been calculated, showing a good agreement with the Raman experimental data.
Parasitismo Intestinal en Población Infantil de las Regiones Atlánticas de Nicaragua
2018
La presente Tesis Doctoral tiene como objetivo establecer el espectro parasitario intestinal de la costa Atlántica de Nicaragua, concretamente de la Región Autónoma del Atlántico Norte (RAAN) y la Región Autónoma del Atlántico Sur (RAAS). Para ello, se ha estudiado un total de 1878 escolares (1009 niñas y 869 niños), con edades comprendidas entre <1 y 14 años de edad. Se ha detectado un espectro parasitario total de al menos 18 especies parásitas (10 protozoos y 8 helmintos), con una prevalencia de parasitación total de 93.7%, observándose mayor prevalencia de protozoos que de helmintos (85.3% vs 61%). Las especies más prevalentes detectadas fueron Blastocystis spp. (68.2%), seguido de T. t…