Catalytic gasification of glycerol in supercritical water

The conversion of glycerol in supercritical water (SCW) was studied at 510-550 °C and a pressure of 350 bars using both a bed of inert and non-porous ZrO2 particles (hydrothermal experiments), and a bed of a 1% Ru/ZrO2 catalyst. Experiments were conducted with a glycerol concentration of 5 wt% in a continuous isothermal fixed-bed reactor at a residence time between 2 and 10 s. Hydrothermolysis of glycerol formed water-soluble products such as acetaldehyde, acetic acid, hydroxyacetone and acrolein, and gases like H2, CO and CO2. The catalyst enhanced the formation of acetic acid, inhibited the formation of acrolein, and promoted gasification of the glycerol decomposition products. Hydrogen and carbon oxides were the main gases produced in the catalytic experiments, with minor amounts of methane and ethylene. Complete glycerol conversion was achieved at a residence time of 8.5 s at 510 °C, and at around 5 s at 550 °C with the 1 wt% Ru/ZrO2 catalyst. The catalyst was not active enough to achieve complete gasification since high yields of primary products like acetic acid and acetaldehyde were still present. Carbon balances were between 80 and 60% in the catalytic experiments, decreasing continuously as the residence time was increased. This was attributed partially to the formation of methanol and acetaldehyde, which were not recovered and analyzed efficiently in our set-up, but also to the formation of carbon deposits. Carbon deposition was not observed on the catalyst particles but on the surface of the inert zirconia particles, especially at high residence time. This was related to the higher concentration of acetic acid and other acidic species in the catalytic experiments, which may polymerize to form tar-like carbon precursors. Because of carbon deposition, hydrogen yields were significantly lower than expected; for instance at 550 °C the hydrogen yield potential was only 50% of the stoichiometric value

Characterization of Carbon Molecular Sieve Membranes Supported on Ceramic Tubes

Carbon molecular sieve membranes have been analyzed in supported and unsupported configurations in this experimental study. The membranes were used to adsorb CO2, N2 and CH4, and their adsorption data were analyzed to establish differences in rate and capacity of adsorption between the two types of samples (supported and unsupported). Experimental results show an important effect of the support, which can be considered as an additional parameter to tailor pore size on these carbon membranes. Immersion calorimetry values were measured by immersing the membranes into liquids of different molecular dimensions (dichloromethane, benzene, n-hexane, 2,2-dimethylbutane). Similarities were found between adsorption and calorimetric analysis. The pore volume of the samples analyzed ranged from 0.016 to 0.263 cm3/g. The effect of the pyrolysis temperature, either 550 or 700 °C, under N2 atmosphere was also analyzed. Quantification of the pore-size distribution of the support was done by liquid-liquid displacement porosimetry. The composite membrane was used for CO2/CH4 separation before and after pore plugging was done. The ideal selectivity factors value (4.47) was over the Knudsen theoretical factor (0.60) for membrane pyrolyzed at 600 °C, which indicates the potential application of these membranes for the separation of low-molecular weight gases.The authors are indebted to the Spanish Government for financial support (Project CTQ2008-02491, partially funded by the FEDER program of the European Union) and to the commission of European Communities Specific OpenTok Project MTKD-LT-2005-030040

Phenolic Compounds Content and Genetic Diversityat Population Level across the Natural Distribution Range of Bearberry (Arctostaphylos uva-ursi, Ericaceae) in the Iberian Peninsula

Bearberry (Arctostaphylos uva-ursi) is a medicinal plant traditionally employed for the treatment of urinary tract infections due to high contents of arbutin (hydroquinone β-D-glucoside), which is now mainly used as a natural skin-whitening agent in cosmetics. Bearberry has also been proposed as a natural antioxidant additive due to the high contents of phenolic compounds in leaves. We studied the variation on phenolic compounds in 42 wild populations of bearberry, aiming to elucidate if intrinsic biological, climatic, and/or geographic factors affect phenolic contents across its natural distribution in the Iberian Peninsula. Bearberry leaves were collected during autumn over a three-year period (2014-2016) in populations across a latitude and altitude gradient. Methanolic extracts showed a wide range of variation in total phenols content, and different phenolic profiles regarding arbutin (levels of this major constituent varied from 87 to 232 mg/g dr wt), but also catechin and myricetin contents, which were affected by geographic and climatic factors. Moderate levels of variation on genome size-assessed by flow cytometry-and on two plastid DNA regions were also detected among populations. Genetic and cytogenetic differentiation of populations was weakly but significantly associated to phytochemical diversity. Elite bearberry genotypes with higher antioxidant capacity were subsequently identified

Preparation, Characterization and Gas Permeation Investigation of Resorcinol-Formaldehyde Polymer or Carbon Xerogels/Tubular Ceramic Composites

New very stable composites prepared by deposition of resorcinol-formaldehyde polymer (RF-) or carbon (C-) xerogels into walls of commercial porous tubular ceramics (TiO2-ZrO2 and αAl2O3-γAl2O3) were obtained by a sol-gel process followed by a drying and a pyrolytic (only for C-xerogel/ceramic composites) step. They were characterized by nitrogen adsorption-desorption, SEM and XRD, and tested for gas (H2, CH4, CO2 and CO) separation applications. Additional morpho-structural information about the open-interconnected ultramicropore structure of composites was found by gas permeation investigation. Interesting results for H2 permeance was obtained especially for RF-polymer/ceramic composites respecting Knudsen diffusion mechanism of gas permeance: H2 > CH4 > CO > CO2. The coexistence of Knudsen and surface diffusion mechanisms were confirmed.Postprint (published version

The construction of infant and primary school teachers’ identity during their initial professional development and first years of work (Identidoc). Summary, main results and contributions

Podeu consultar el simposi sencer a: http://hdl.handle.net/2445/50680Podeu consultar la versió en català de la comunicació a: http://hdl.handle.net/2445/50728Educators who are currently beginning their professional career at any level of the educational system and who will likely have to work during the next thirty to forty years will be taking part in the education of individuals who, with the permission of prophets and doomsayers, will live part of their lives in the 22nd century. That long but simple statement causes a bit of vertigo as well as a good amount of reflection on the part of we educators who were trained in the 20th century, are working in the 21st century, and are responsible for preparing people to build a tomorrow that is already today (Millán and Sancho, 1995). This is the starting point of our research groups’ interest in exploring how men and women who have graduated from teacher education programs with specializations in infant and primary education learn to be teachers, and how they establish and position themselves as teachers during their university studies and the first years of their professional life..

Sex differences in cerebral venous sinus thrombosis after adenoviral vaccination against COVID-19

Introduction: Cerebral venous sinus thrombosis associated with vaccine-induced immune thrombotic thrombocytopenia (CVST-VITT) is a severe disease with high mortality. There are few data on sex differences in CVST-VITT. The aim of our study was to investigate the differences in presentation, treatment, clinical course, complications, and outcome of CVST-VITT between women and men. Patients and methods: We used data from an ongoing international registry on CVST-VITT. VITT was diagnosed according to the Pavord criteria. We compared the characteristics of CVST-VITT in women and men. Results: Of 133 patients with possible, probable, or definite CVST-VITT, 102 (77%) were women. Women were slightly younger [median age 42 (IQR 28–54) vs 45 (28–56)], presented more often with coma (26% vs 10%) and had a lower platelet count at presentation [median (IQR) 50x109/L (28–79) vs 68 (30–125)] than men. The nadir platelet count was lower in women [median (IQR) 34 (19–62) vs 53 (20–92)]. More women received endovascular treatment than men (15% vs 6%). Rates of treatment with intravenous immunoglobulins were similar (63% vs 66%), as were new venous thromboembolic events (14% vs 14%) and major bleeding complications (30% vs 20%). Rates of good functional outcome (modified Rankin Scale 0-2, 42% vs 45%) and in-hospital death (39% vs 41%) did not differ. Discussion and conclusions: Three quarters of CVST-VITT patients in this study were women. Women were more severely affected at presentation, but clinical course and outcome did not differ between women and men. VITT-specific treatments were overall similar, but more women received endovascular treatment.</p

Sex differences in cerebral venous sinus thrombosis after adenoviral vaccination against COVID-19

Introduction: Cerebral venous sinus thrombosis associated with vaccine-induced immune thrombotic thrombocytopenia (CVST-VITT) is a severe disease with high mortality. There are few data on sex differences in CVST-VITT. The aim of our study was to investigate the differences in presentation, treatment, clinical course, complications, and outcome of CVST-VITT between women and men. Patients and methods: We used data from an ongoing international registry on CVST-VITT. VITT was diagnosed according to the Pavord criteria. We compared the characteristics of CVST-VITT in women and men. Results: Of 133 patients with possible, probable, or definite CVST-VITT, 102 (77%) were women. Women were slightly younger [median age 42 (IQR 28–54) vs 45 (28–56)], presented more often with coma (26% vs 10%) and had a lower platelet count at presentation [median (IQR) 50x109/L (28–79) vs 68 (30–125)] than men. The nadir platelet count was lower in women [median (IQR) 34 (19–62) vs 53 (20–92)]. More women received endovascular treatment than men (15% vs 6%). Rates of treatment with intravenous immunoglobulins were similar (63% vs 66%), as were new venous thromboembolic events (14% vs 14%) and major bleeding complications (30% vs 20%). Rates of good functional outcome (modified Rankin Scale 0-2, 42% vs 45%) and in-hospital death (39% vs 41%) did not differ. Discussion and conclusions: Three quarters of CVST-VITT patients in this study were women. Women were more severely affected at presentation, but clinical course and outcome did not differ between women and men. VITT-specific treatments were overall similar, but more women received endovascular treatment.</p

Una aproximación a la alfabetización lectora de los estudiantes peruanos de 15 años : resultados del Perú en la evaluación internacional PISA

Eel objetivo de este documento es presentar los resultados de los estudiantes peruanos, desde una perspectiva regional y nacional, en las pruebas de comprensión de textos de PISA 2000. Para ello, se analiza el desempeño de nuestro sistema educativo en relación con el de los cuatro países de la región latinoamericana que participaron en el proyecto PISA (Argentina, Chile, Brasil y México). Se presentan también los resultados al interior de los centros educativos estatales y no estatales de los países de la región latinoamericana, dándose un énfasis particular al análisis de los resultados del Perú. Adicionalmente, se presenta un análisis detallado sobre la relación que existe entre el desempeño de los estudiantes peruanos y las características de sus familias y escuelas