A π-Extended Donor-Acceptor-Donor Triphenylene Twin linked via a Pyrazine-bridge

Beta-amino triphenylenes can be accessed via palladium catalyzed amination of the corresponding triflate using benzophe-none imine. Transformation of amine 6 to benzoyl amide 18 is also straightforward and its wide mesophase range demon-strates that the new linkage supports columnar liquid crystal formation. Amine 6 also undergoes clean aerobic oxidation to give a new twinned structure linked through an electron-poor pyrazine ring. The new discotic liquid crystal motif contains donor and acceptor fragments, and is more oval in shape rather than disk-like. It forms a wide range columnar mesophase. Absorption spectra are strong and broad; emission is also broad and occurs with a Stokes shift of ca. 0.7 eV, indicative of charge-transfer characte

XXVI Congreso Nacional y II Congreso Internacional de SEDEM

Organizan: Sociedad Española de Educación Médica y Facultad de Medicina y Enfermería, Universidad del País Vasco (UPV/EHU)Comunicaciones aceptadas en el XXVI Congreso de la Sociedad Española de Educación Médica, celebrado en Bilbao del 28 al 30 de noviembre de 2024

Resonant spin tunneling in small antiferromagnetic particles

The paper reports a detailed experimental study on magnetic relaxation of natural horse-spleen ferritin. ac susceptibility measurements performed on three samples of different concentration show that dipole-dipole interactions between uncompensated moments play no significant role. Furthermore, the distribution of relaxation times in these samples has been obtained from a scaling of experimental X" data, obtained at different frequencies. The average uncompensated magnetic moment per protein is compatible with a disordered arrangement of atomic spins throughout the core, rather than with surface disorder. The observed field dependence of the blocking temperature suggests that magnetic relaxation is faster at zero field than at intermediate field values. This is confirmed by the fact that the magnetic viscosity peaks at zero field, too. Using the distribution of relaxation times obtained independently, we show that these results cannot be explained in terms of classical relaxation theory. The most plausible explanation of these results is the existence, near zero field, of resonant magnetic tunneling between magnetic states of opposite orientation, which are thermally populated

High-Purity Green Hydrogen Production by Bio-oil/Ethanol Mixtures Steam Reforming in Pd-Based Membrane Reactors

The use of a membrane reactor (MR) for the reforming of biomass derived oxygenates is a promising approach to produce pure hydrogen from renewable sources. In this study, a Pd membrane supported on a porous stainless-steel (PSS) tube was fabricated by Electroless Pore Plating (ELP- PP) and tested in the steam reforming (SR) of bio-oil stabilized with 25 wt.% ethanol. All reaction tests were conducted in a reaction setup with two consecutive steps: (i) the thermal treatment for the vaporization of the bio-oil/ethanol mixture and the controlled deposition of pyrolytic lignin, and (ii) the SR reaction in an upwards-flow bed reactor with a Ni-based catalyst obtained upon reduction of a NiAl2O4 spinel. The Pd membrane was allocated in the middle of the SR reactor for its use as a MR. The reaction conditions were maintained at 580 °C with steam/carbon ratio of 2.5, space time of 0.15 h, feed pressure in the range of 1-3.3 bar, 0.1 bar in the permeate side, and time on stream of 4 h. The results reveal the enhancement of the hydrogen yield when using the MR at 3.3 bar and with the lowest gas velocity, allowing a hydrogen recovery of 57.74% with 99.8% purity. Consequently, the total hydrogen production in the MR operating at 3.3 bar and 0.6 cm s-1 increased from 0.309 to 0.367 g H2 (g C)-1 if compared to the conventional reactor at 1 bar and 0.9 cm·s-1

Steam reforming of bio-oil stabilized with ethanol over a Ni/MgAl2O4 catalyst in a Pd-membrane reactor

A new membrane reactor (MR) has been used in the steam reforming (SR) of a feed of raw bio-oil stabilized with 25 wt% ethanol over a Ni/MgAl2O4 catalyst, comparing the results (yield of H2 and byproduct gases) to those reached in a conventional reactor (CR). The reaction setup involves two steps in series: a down-flow tube (at 500 ºC) for the vaporization of the feed and controlled removal of pyrolytic lignin (PL) from the oxygenates in the biooil, followed by an up-flow reactor provided with a composite Pd membrane supported on a porous stainless steel (PSS) tube containing a CeO2 intermediate layer (Pd/CeO2/PSS). In the MR configuration (with permeate pressure of 0.2 bar absolute), a H2 yield of 82 % was achieved at 550 ºC, space time of 2.8 h, S/C ratio of 1.55 and 3 bar in the retentate (reactor). This result significantly improves those reached in CR, even at 1 bar and 600 ºC. The S/C ratio in the feed must be limited in the MR configuration to avoid restrictions in H2 flux through the Pdmembrane caused by a higher gas dilution and concentration-polarization effect, as observed when the S/C ratio is increased up to 2.2. Similarly, a higher retentate pressure has a negative effect on the H2 yield due to its negative impact on the equilibrium of methane SR, that overcomes its benefits on the H2 permeation through the membrane. A promising performance of the membrane and catalyst has been obtained, thus demonstrating good prospects for their use in the sustainable production of H2 from lignocellulosic biomas

Aplicación de la Imagen de Resonancia Magnética (IRM) al análisis morfológico no destructivo de piezas cárnicas. Una aproximación a la selección de perniles.

Para determinar el potencial de aplicación de la imagen de resonancia magnética (IRM) en la evaluación de la aptitud tecnológica de perniles frescos a nivel industrial se han obtenido imágenes de resonancia magnética potenciadas en T1, T2, T2* y densidad protónica (DP). Con este objetivo, se analizaron perniles frescos de cerdo blanco clasificados en cuatro categorías en función de su contenido graso. En cada pieza se determinó, utilizando imágenes en el plano axial potenciadas en DP, el espesor de la grasa subcutánea (GS) sobre los músculos rectus femoris (RF), vastus lateralis, biceps femoris y semitendinosus (ST) a nivel de la longitud media del fémur. Además, se estimó el valor promedio del espesor de la GS en zonas seleccionadas (SL) entre los músculos RF y ST. Se ha establecido una correlación lineal (R2 = 0,85; p < 0,05) entre el espesor promedio de la GS en las zonas SL y el contenido graso total del pernil. El análisis mediante IRM del interior de las piezas permitió la detección de defectos internos como hemorragias y acúmulos de sangre, lesiones articulares y óseas, anomalías del ganglio poplíteo y desgarros musculares, que posteriormente fueron contrastadas mediante la disección de las piezas. Muchas de estas lesiones tienen una importante repercusión en la aparición de defectos en jamón curado. Se concluye que la IRM, como técnica no destructiva, es una herramienta adecuada para la detección de defectos internos en piezas íntegras, así como para la estimación del contenido total de grasa del pernil.Depto. de Farmacia Galénica y Tecnología AlimentariaFac. de VeterinariaTRUEinpres

Separação de fases induzida por meio de reação química no sistema éter diglicidílico do bisfenol A e piperidina com poli(metacrilato de metila) Phase separation induced by chemical reaction in the system of diglycidyl ether of bisphenol A and piperidine with poly(methyl methacrylate)

O comportamento da separação de fases e da gelificação do sistema epoxídico, constituído pelo éter diglicidílico do bisfenol A (DGEBA) e a piperidina, modificado com poli(metacrilato de metila) (PMMA), foi estudado na faixa de temperatura de 60 °C - 120 °C. A concentração de PMMA e a temperatura de cura causam mudanças significativas na morfologia gerada. A massa molecular de PMMA provoca ligeiras mudanças para a observação da separação de fases e não afeta a velocidade da reação. O sistema modificado com PMMA mostra o efeito de retardação cinético e a velocidade de separação de fases é maior que a velocidade de polimerização.<br>The phase separation and gelification behavior of epoxy system based on diglycidyl ether of bisphenol-A (DGEBA) and piperidine modified with poly(methyl methacrylate) (PMMA) were studied in the range between 60 °C and 120 °C. The morphology is influenced by the PMMA content in the blend and also by the cure temperature. The molecular weight of PMMA provokes slight changes on cloud point and does not affect the reaction rate. The systems modified by PMMA exhibited kinetic retardation effect but the cloud point rate was higher than the polymerization rate