Raman spectra of multilayer graphene under high temperatures.

For graphitic materials, Raman technique is a common method for temperature measurements through analysis of phonon frequencies. Temperature (T) induced downshift of the bond-stretching G mode (ΔG) is well known, but experimentally obtained thermal coefficients ΔG/ΔT vary considerably between diverse works. Further, ΔG/ΔT coefficients usually were evaluated for relatively low temperatures and found to differ strongly for mono, a few and multilayer graphene. We studied G band behavior in freely suspended multilayer graphene flakes (or graphite nanoflakes) under localized heating by a laser beam. Analysis of Stokes and anti-Stokes signals showed that G band has a complex structure and can be deconvoluted into several peaks that demonstrate distinctly different behavior under heating. A plausible assumption is that these peaks correspond to several groups of graphitic layers (surface, near-surface and bulk) and then different thermal coefficients were determined for these groups. This behavior can be explained by decreasing interaction between surface layers and underlying material at high temperatures that affects especially vibrational properties of a few outermost layers. Estimates of temperatures using anti-Stokes/Stokes intensity ratio (I aS/I S) were also done to give results comparable with those obtained from G band downshift, T ΔG ≈ T aS/S, supporting the proposed model. The range of temperatures obtained by laser heating, as evaluated by both methods, was from 450 to 1200 K.

Angioedema hereditario, ponderación de evidencias. parte 2 - tratamiento / Hereditary angioedema, weighting of evidence. Part 2 - Treatment

Desde las observaciones de Quincke y Osler, que refirieron pacientes con una "tumefacción" diferente de las que provocaban habitualmente los mecanismos alérgicos hasta el descubrimiento de un nuevo mediador responsable de esos edemas dolorosos y deformantes, se han sucedido los aportes de los investigadores en el esclarecimiento de la patogenia y el tratamiento del AEH hasta la actualidad, en que el arsenal terapéutico se ve notablemente enriquecido por medicamentos altamente eficaces y específicos. Intentaremos describirlos. (AU)

From the observations of Quincke and Osler, who referred patients with a "swelling" different from those that usually provoked the allergic mechanisms until the discovery of a new mediator responsible for these painful and deforming edemas, have been the contributions of researchers in the Clarification of the pathogenesis and treatment of HAE to date, where the therapeutic arsenal is remarkably enriched by highly effective and specific drugs. We will try to describe them.(AU)

Atypical Exciton-Phonon Interactions in WS2 and WSe2 Monolayers Revealed by Resonance Raman Spectroscopy.

Resonant Raman spectroscopy is a powerful tool for providing information about excitons and exciton-phonon coupling in two-dimensional materials. We present here resonant Raman experiments of single-layered WS2 and WSe2 using more than 25 laser lines. The Raman excitation profiles of both materials show unexpected differences. All Raman features of WS2 monolayers are enhanced by the first-optical excitations (with an asymmetric response for the spin-orbit related XA and XB excitons), whereas Raman bands of WSe2 are not enhanced at XA/B energies. Such an intriguing phenomenon is addressed by DFT calculations and by solving the Bethe-Salpeter equation. These two materials are very similar. They prefer the same crystal arrangement, and their electronic structure is akin, with comparable spin-orbit coupling. However, we reveal that WS2 and WSe2 exhibit quite different exciton-phonon interactions. In this sense, we demonstrate that the interaction between XC and XA excitons with phonons explains the different Raman responses of WS2 and WSe2, and the absence of Raman enhancement for the WSe2 modes at XA/B energies. These results reveal unusual exciton-phonon interactions and open new avenues for understanding the two-dimensional materials physics, where weak interactions play a key role coupling different degrees of freedom (spin, optic, and electronic).

A new designed π conjugated molecule for stable single walled carbon nanotube dispersion in aqueous medium.

A molecule with a π conjugated backbone built from aromatic thiophene and dialkoxyphenylene units and substituted imidazolium groups (TPO) is designed to obtain ultra-stable single walled carbon nanotube (SWCNT) dispersion in aqueous medium. The proposed mechanism of non-covalent interaction is accompanied by individualization of SWCNT and comprises of dominant nondisruptive π-π and cation-π interaction between them and the TPO conjugated oligomer. The individualization of SWCNT and dispersibility and stability of the ultra-stable suspensions were estimated using high resolution transmission electron microscopy, UV-Visible-NIR absorption spectroscopy, Raman spectroscopy, photoluminescence and zeta potential measurement. Nuclear magnetic resonance data provides direct evidence toward possible cation-π interaction.

ANGIOEDEMA HEREDITARIO, PONDERACIÓN DE EVIDENCIAS. PARTE 1 / Hereditary angioedema, weighting of evidence. Part 1

A pesar de que el angioedema hereditario es un padecimiento raro, tiene una amplia bibliografía que ratifica que la fisiopatología de esta enfermedad es compleja. La constante investigación de la industria farmacéutica no solo ha aportado nuevos recursos terapéuticos sino que ha logrado despertar un inusitado interés en la comunidad médica, permitiendo que tengamos una mayor comprensión sobre los mecanismos que presiden la aparición de las crisis. El Comité de Angioedema Hereditario de la AAAeIC ha desarrollado una puesta al día sobre esta entidad, que, por las características de sus síntomas, es abordada principalmente por los especialistas en alergia e inmunología clínica(AU)

Although hereditary angioedema is a rare condition, it has a large number of references that confirm that the pathophysiology of this disease is complex. The constant research of the pharmaceutical industry has not only brought new therapeutic resources, but also aroused an unusual interest in the medical community, allowing us to have a better understanding of the mechanisms that perform the onset of crises. The AAA e IC Hereditary Angioedema Committee has developed an update on this entity, which, due to the characteristics of its symptoms, is mainly addressed by specialists in allergy and clinical immunology.(AU)

The influence of oxygen-containing functional groups on the dispersion of single-walled carbon nanotubes in amide solvents.

Surface composition plays an important role in carbon nanotube dispersibility in different environments. Indeed, it determines the choice of dispersion medium. In this paper the effect of oxidation on the dispersion of HiPCO single-walled carbon nanotubes (SWNTs) in N-methyl-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-dodecyl-pyrrolidinone (N12P) and cyclohexyl-pyrrolidinone (CHP) was systematically studied. During the oxidation process, similar amounts of carboxylic acid and phenolic groups were introduced to mostly already existing defects. For each solvent the dispersion limits and the absorption coefficients were estimated by optical absorption analysis over a range of SWNT concentrations. The presence of acid oxygenated groups increased SWNT dispersibility in NMP, DMF and DMA, but decreased in N12P and CHP. The absorption coefficients, however, decreased for all solvents after oxidation, reflecting the weakening of the effective transition dipole of the π-π transition with even limited extension functionalization and solvent interaction. The analysis of the results in terms of Hansen and Flory-Huggins solubility parameters evidenced the influence of dipolar interactions and hydrogen bonding on the dispersibility of oxidized SWNTs.

One-dimensional character of combination modes in the resonance Raman scattering of carbon nanotubes.

Resonance Raman spectroscopy with an energy tunable system is used to analyze the 600-1100 cm(-1) spectral region in single-wall carbon nanotubes. Sharp peaks are associated with the combination of zone folded optic and acoustic branches from 2D graphite. These combination modes exhibit a peculiar dependence on the excitation laser energy that is explained on the basis of a highly selective resonance process that considers phonons and electrons in low dimensional materials.