Transition metal oxides with perovskite and spinel structures for electrochemical energy production applications.

Transition metal oxide-based materials are an interesting alternative to substitute noble-metal based catalyst in energy conversion devices designed for oxygen reduction (ORR), oxygen evolution (OER) and hydrogen evolution reactions (HER). Perovskite (ABO3) and spinel (AB2O4) oxides stand out against other structures due to the possibility of tailoring their chemical composition and, consequently, their properties. Particularly, the electrocatalytic performance of these materials depends on features such as chemical composition, crystal structure, nanostructure, cation substitution level, eg orbital filling or oxygen vacancies. However, they suffer from low electrical conductivity and surface area, which affects the catalytic response. To mitigate these drawbacks, they have been combined with carbon materials (e.g. carbon black, carbon nanotubes, activated carbon, and graphene) that positively influence the overall catalytic activity. This review provides an overview on tunable perovskites (mainly lanthanum-based) and spinels featuring 3d metal cations such as Mn, Fe, Co, Ni and Cu on octahedral sites, which are known to be active for the electrochemical energy conversion.

Electrocatalytic activity of calcined manganese ferrite solid nanospheres in the oxygen reduction reaction.

In this study, we synthesized MnFe2O4 solid nanospheres (MSN) calcined at different temperatures (200-500 °C) and MSN-based materials mixed with carbon black, for their use as electrocatalysts in the oxygen reduction reaction (ORR) in alkaline medium (0.1 M KOH). It was demonstrated that the calcination temperature of MSN material determined its chemical surface composition and microstructure and it had an important effect on the electrocatalytic properties for ORR, which in turn was reflected in the performance of MSN/CB-based electrocatalysts. The study revealed that the presence of Mn species plays a key role in the ORR activity. Among tested, MSN200/CB and MSN350/CB exhibited the best electrochemical performances together with outstanding stability.

Exploring the synergistic effect of palladium nanoparticles and highly dispersed transition metals on carbon nitride/super-activated carbon composites for boosting electrocatalytic activity.

In the present work, multifunctional electrocatalysts formed by palladium nanoparticles (Pd NPs) loaded on Fe or Cu-containing composite supports, based on carbon nitride (C3N4) and super-activated carbon with a high porosity development (SBET 3180 m2/g, VDR 1.57 cm3/g, and VT 1.65 cm3/g), were synthesised. The presence of Fe or Cu sites favoured the formation of Pd NPs with small average particle size and a very narrow size distribution, which agreed with Density Functional Theory (DFT) calculations showing that the interaction of Pd clusters with C3N4 flakes is weaker than with Cu- or Fe-C3N4 sites. The electroactivity was also dependent on the composition and, as suggested by preliminary DFT calculations, the Pd-Cu catalyst showed lower overpotential for hydrogen evolution reaction (HER) while bifunctional oxygen reduction reaction/ oxygen evolution reaction (ORR/OER) behaviour was superior in Pd-Fe sample. The Pd-Fe electrocatalyst was studied in a zinc-air battery (ZAB) for 10 h, showing a performance similar to a commercial Pt/C + RuO2 catalyst with a high content of precious metal. This study demonstrates the synergistic effect between Pd species and transition metals and shows that transition metals anchored on C3N4-based composite materials promote the electroactivity of Pd NPs in HER, ORR and OER due to the interaction between both species.

CuH-ZSM-5 as hydrocarbon trap under cold start conditions.

Cold start tests are carried out to evaluate the performance of copper-exchanged zeolites as hydrocarbon traps under simulated gasoline car exhaust gases, paying special attention to the role of copper in the performance of these zeolites. It is concluded that the partial substitution of the protons in the parent H-ZSM-5 zeolite is highly beneficial for hydrocarbon trapping due to the formation of selective adsorption sites with specific affinity for the different exhaust components. However, it is also observed that uncontrolled exchanging process conditions could lead to the presence of CuO nanoparticles in the zeolite surface, which seem to block the pore structure of the zeolite, decreasing the hydrocarbon trap efficiency. Among all the zeolites studied, the results point out that a CuH-ZSM-5 with a partial substitution of extra-framework protons by copper cations and without any detectable surface CuO nanoparticles is the zeolite that showed the best performance under simulated cold start conditions due to both the high stability and the hydrocarbon retaining capacity of this sample during the consecutive cycles.

Metal oxide Perovskite-Carbon composites as electrocatalysts for zinc-air batteries. Optimization of ball-milling mixing parameters.

Zn-air batteries (ZABs) are promising electrochemical devices to store energy. Metal oxide perovskites mixed with carbon materials are highlighted as interesting materials for this application because of their appropriate bifunctional performance in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The interaction between both components of the electrocatalyst is important in the bifunctional electrocatalytic activity, and the mixing method plays an important role in this interaction. Then, different mixing methods have been studied in this work (ball-milling, mortar and manual shaking). The use of different physicochemical techniques such as temperature programmed desorption (TPD), temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) in the materials characterization, allows us to conclude that the mixing method strongly influences the particle size and the interaction between both components, which determine the final electrocatalytic activity. The materials prepared by ball-milling displayed the best performance. Herein, the experimental conditions were optimized to obtain electrocatalysts with enhanced electrocatalytic activity for ORR and OER. Low rotating speed, air atmosphere and low ball-milling time generate electrocatalysts with a small nanoparticle size, more homogeneous and with a higher interaction between both components, which enhances electron transfer, and consequently, the overall oxygen-involved reactions. The best electrocatalyst obtained was studied as air-electrode in a Zn-air battery and it was compared to a commercial Pt/C electrocatalyst, obtaining higher cyclability (55.2 vs 51.7 %) for 30 h, and higher energy density at 5 mA/cm2 (764 mAh/g vs 741 mAh/g).

Global fit and structure optimization of flexible and rigid macromolecules and nanoparticles from analytical ultracentrifugation and other dilute solution properties.

The calculation of hydrodynamic and other solution properties from structural information (size and shape or flexibility) of macromolecules and nanoparticles is feasible thanks to existing theories and computational tools. Here we review our recent advances in the inverse problem of extracting structural information from those properties. The concepts of equivalent radii and ratios of radii are particularly useful in global-fitting structural analysis, when one has to treat simultaneously with various properties, eventually for a series of samples. Based on the equivalent radii or their ratios, we define target functions that measure the adequacy of a given structure to fit a set of experimental properties. Structural determination is carried out by minimization of those target functions. We review a variety of examples. Some of them refer to the simple, yet important models like ellipsoids, cylinders and wormlike chains, whose structure is determined by optimization of the model parameters. In other, more complex cases, properties are calculated with computational tools like programs in the HYDRO suite. We have devised other tools to make the structure optimization from the results of those calculations in a quite direct, simple and systematic manner.

Prediction of hydrodynamic and other solution properties of rigid proteins from atomic- and residue-level models.

Here we extend the ability to predict hydrodynamic coefficients and other solution properties of rigid macromolecular structures from atomic-level structures, implemented in the computer program HYDROPRO, to models with lower, residue-level resolution. Whereas in the former case there is one bead per nonhydrogen atom, the latter contains one bead per amino acid (or nucleotide) residue, thus allowing calculations when atomic resolution is not available or coarse-grained models are preferred. We parameterized the effective hydrodynamic radius of the elements in the atomic- and residue-level models using a very large set of experimental data for translational and rotational coefficients (intrinsic viscosity and radius of gyration) for >50 proteins. We also extended the calculations to very large proteins and macromolecular complexes, such as the whole 70S ribosome. We show that with proper parameterization, the two levels of resolution yield similar and rather good agreement with experimental data. The new version of HYDROPRO, in addition to considering various computational and modeling schemes, is far more efficient computationally and can be handled with the use of a graphical interface.

Electrochemical regeneration of spent activated carbon from drinking water treatment plant at different scale reactors.

The electrochemical regeneration of real spent activated carbons (AC) used in drinking water treatment plants was studied at different reactor scales. The electrochemical regeneration was carried out in a 6 g filter-press cell and a 3.5 kg batch reactor, allowing the scaling-up of the process between the two electrolytic reactors. The effect of the electrolyte, the divided/undivided compartment configuration and the current density were studied in the filter-press cell. The effect of compartment configuration and the influence of the regeneration time were studied in the scaled-up reactor. A current density of 0.025 A cm-2 was used and the electrodes were Pt/Ti as anode and Pt/Ti and stainless-steel as cathode. The ACs were characterized by N2 adsorption isotherms to analyse the recovery of porosity and TPD-MS to analyse the AC surface after the electrochemical treatment. In filter-press cell, a recovery of the surface area of 96% was achieved after 8 h of treatment, by introducing the AC in the cathodic compartment using 0.05 M H2SO4 solution as electrolyte. In the 3.5 kg electrochemical reactor, 95% of the pristine AC surface area was recovered. Thus, electrochemical methods can provide a green alternative to the regeneration of spent AC.

[Effectiveness, adherence and usability of a teleneurorehabilitation programme to ensure continuity of care for patients with acquired brain injury during the COVID-19 pandemic]. / Efectividad, adhesión y usabilidad de un programa de teleneurorrehabilitación para garantizar la continuidad de cuidados en pacientes con daño cerebral adquirido durante la pandemia originada por la COVID-19.

INTRODUCTION: The health pandemic brought about by SARS-CoV-2 (COVID-19) has limited access to neurorehabilitation programmes for many patients who have suffered stroke, traumatic brain injury or acquired brain damage due to some other cause. As telerehabilitation allows for the provision of care in situations of social distancing, it may mitigate the negative effects of confinement. The aim of this study was to determine the efficacy, adherence and usability of a teleneurorehabilitation intervention for patients with acquired brain injury. PATIENTS AND METHODS: All patients included in a face-to-face neurorehabilitation programme at the time of the declaration of the state of alarm in Spain due to COVID-19 and who agreed to participate in the study were included in a teleneurorehabilitation programme. The effectiveness of the programme, understood as an improvement in independence, was quantified with the Barthel index. Adherence to the programme and usability of the tool were explored through questionnaires. RESULTS: Altogether, 46 patients, accounting for 70.6% of the total, participated in the study. Participants significantly improved their independence and showed an improvement in the Barthel index between the start (77.3 ± 28.6) and the end of the programme (82.3 ± 26). Adherence to the intervention was very high (8.1 ± 2.2 out of 10) and the online sessions were the most highly rated content. The tool used showed a high usability (50.1 ± 9.9 out of 60) and could be used without assistance by more than half the participants. CONCLUSION: The teleneurorehabilitation intervention was found to be effective in improving patients' independence, and promoted a high degree of adherence and usability.

TITLE: Efectividad, adhesión y usabilidad de un programa de teleneurorrehabilitación para garantizar la continuidad de cuidados en pacientes con daño cerebral adquirido durante la pandemia originada por la COVID-19.Introducción. La pandemia sanitaria originada por el SARS-CoV-2 (COVID-19) ha limitado el acceso a programas de neurorrehabilitación de muchos pacientes que han sufrido ictus, traumatismos craneoencefálicos o un daño cerebral adquirido por otra causa. Dado que la telerrehabilitación permite la provisión de cuidados en situaciones de distanciamiento social, podría atenuar los efectos negativos del confinamiento. El objetivo de este estudio fue determinar la eficacia, la adhesión y la usabilidad de una intervención de teleneurorrehabilitación dirigida a pacientes con daño cerebral adquirido. Pacientes y métodos. Todos los pacientes incluidos en un programa de neurorrehabilitación presencial en el momento de la declaración del estado de alarma en España con motivo de la COVID-19 y que aceptaron participar en el estudio fueron incluidos en un programa de teleneurorrehabilitación. La eficacia del programa, entendida como una mejora en la independencia, se cuantificó con el índice de Barthel. La adhesión al programa y la usabilidad de la herramienta se investigaron mediante cuestionarios. Resultados. Un total de 146 pacientes, el 70,6% del total, participó en el estudio. Los participantes mejoraron significativamente su independencia y mostraron una mejoría en el índice de Barthel entre el inicio (77,3 ± 28,6) y el fin del programa (82,3 ± 26). La intervención tuvo una gran adhesión (8,1 ± 2,2 sobre 10) y las sesiones en línea fueron el contenido mejor valorado. La herramienta utilizada mostró una elevada usabilidad (50,1 ± 9,9 sobre 60) y pudo ser utilizada sin ayuda por más de la mitad de los participantes. Conclusión. La intervención de teleneurorrehabilitación resultó ser eficaz para mejorar la independencia de los pacientes, y promovió una elevada adhesión y usabilidad.

Intrinsic viscosity of bead models for macromolecules and nanoparticles.

The calculation of the intrinsic viscosity by means of classical treatments of bead models, typically composed of a number of identical beads, presents some problems when applied to models where the beads are unequal and their number is not very large. A correction to this problem was proposed 10 years ago (García de la Torre and Carrasco in Eur Biophys J 27:549-557, 1998). This so-called volume correction, which consisted of adding a term proportional to the volume of the model, was proved to be rigorous in physico-mathematical terms, and produced improved results in some circumstances, but not always. Recently, the volume correction is being reconsidered so that with some deduced or empirical modifications, it can allow for safer predictions of the intrinsic viscosity. This paper contributes a discussion and further improvements of that correction for the intrinsic viscosity.

Multi-scale calculation and global-fit analysis of hydrodynamic properties of biological macromolecules: determination of the overall conformation of antibody IgG molecules.

We present a scheme, based on existing and newly developed computational tools, for the determination of the overall conformation of biological macromolecules composed by domains or subunits, using from such structural determination easily available solution properties. In a multi-scale approach, atomic-level structures are used to provide simple shapes for the subunits, which are put together in a coarse grained model, with a few parameters that determine the overall shape of the macromolecule. Computer programs, like those in the HYDRO suite that evaluate the properties of either atomic or coarse-grained models. In this paper we present a new scheme for a global fit of multiple properties, implemented in a new computer program, HYDROFIT, which interfaces with the programs of the HYDRO suite to find an optimum, best-fitting structure in a robust but simple way. The determination of the overall structure of the native antibody IgG3, bearing a long hinge, and that of the hingeless mutant m15 is presented to test and confirm the validity of this simple, systematic and efficient scheme.

Arsenic species interactions with a porous carbon electrode as determined with an electrochemical quartz crystal microbalance.

The interactions of arsenic species with platinum and porous carbon electrodes were investigated with an electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry in alkaline solutions. It is shown that the redox reactions in arsenic-containing solutions, due to arsenic reduction/deposition, oxidation/desorption, and electrocatalyzed oxidation by Pt can be readily distinguished with the EQCM. This approach was used to show that the arsenic redox reactions on the carbon electrode are mechanistically similar to that on the bare Pt electrode. This could not be concluded with just classical cyclic voltammetry alone due to the obfuscation of the faradaic features by the large capacitative effects of the carbon double layer.For the porous carbon electrode, a continual mass loss was always observed during potential cycling, with or without arsenic in the solution. This was attributed to electrogasification of the carbon. The apparent mass loss per cycle was observed to decrease with increasing arsenic concentration due to a net mass increase in adsorbed arsenic per cycle that increased with arsenic concentration, offsetting the carbon mass loss. Additional carbon adsorption sites involved in arsenic species interactions are created during electrogasification, thereby augmenting the net uptake of arsenic per cycle.It is demonstrated that EQCM, and in particular the information given by the behavior of the time derivative of the mass vs. potential, or massogram, is very useful for distinguishing arsenic species interactions with carbon electrodes. It may also prove to be effective for investigating redox/adsorption/desorption behavior of other species in solution with carbon materials as well.

Structural and morphological alterations induced by cobalt substitution in LaMnO3 perovskites.

The chemical composition of a LaMnO3 perovskite was modified sequentially by an improved sol-gel method to include cobalt centers in some B sites formerly occupied by Mn. In this way, a representative set of materials of general formula LaMn1-xCoxO3 was obtained whose composition extends from LaMnO3 to LaCoO3. These perovskites, as promising materials for oxygen reduction or oxygen evolution reactions, were characterized by several imaging (SEM), spectroscopic (XPS, EDX) and diffraction (XRD) techniques to elucidate their structure and to demonstrate the existence of composition differences between the catalytic surface and the bulk material. Specifically, it was found that lanthanum ions prevail at the surface of the catalyst but high cobalt-substitution levels stimulate the surface enrichment in B cations in their respective higher oxidation states (Mn4+ and Co3+ against Mn3+ and Co2+). This phenomenon opens the possibility of tuning their electrocatalytic properties and to synthesize suitable materials for electrochemical reactions involving molecular oxygen.

High sperm DNA fragmentation delays human embryo kinetics when oocytes from young and healthy donors are microinjected.

BACKGROUND: Time-lapse monitoring (TLM) technology has been implemented in the clinical setting for the culture and selection of human embryos. Many studies have assessed the association between sperm DNA fragmentation (sDNAf) and clinical outcomes after ART, but little is known about the influence of sDNA on embryo morphokinetics. OBJECTIVES: The objective of this retrospective study, which includes 971 embryos from 135 consecutive ICSI cycles (56 cases with own oocytes, 79 with oocytes from young and healthy donors), was to assess if sDNAf has an impact on embryo morphokinetics. MATERIALS AND METHODS: Samples used to perform ICSI were analyzed by the flow cytometry TUNEL assay, and embryo development was assessed through an EmbyoScope® system. The association between sDNAf and the timings of cell cleavage was analyzed by categorizing the first variable into quartiles: ≤6.50%; 6.51-10.70%; 10.71-20.15%; >20.15%. RESULTS: In cases where sDNAf was above 20.15% (the upper quartile), embryos derived from donated oocytes (n = 644) showed significantly slower divisions. Such association was not observed in embryos obtained from the patients' own oocytes (n = 327). The embryo cleavage pattern (either normal, direct from 1 to 3 blastomeres, direct from 1 to 4 blastomeres, incomplete, reversed or asynchronous) was independent of the sDNAf level. Blastocyst arrival rate was 63.0% and the rate of good quality embryos (transferred and frozen embryos divided by the number of zygotes) was 45.49%. Neither parameter was related to the levels of sDNAf. DISCUSSION: According to our results, the association between high sDNAf and donated oocytes led to delayed cell division. To our knowledge, this is the first study suggesting that sDNAf can delay human embryo cleavage timings when oocytes from donors are inseminated. CONCLUSIONS: This finding may indicate that, in the presence of increased DNA damage, time is needed before the first embryonic cell division for the activation of the optimal DNA repairing machinery in higher quality oocytes.

Spermatozoa with numerical chromosomal abnormalities are more prone to be retained by Annexin V-MACS columns.

Colloidal super-paramagnetic microbeads conjugated with annexin V are effective for separating apoptotic spermatozoa by MACS as a result of the high affinity of annexin V for externalized PS molecules. The effectiveness of the procedure in reducing the percentage of sperm with fragmented DNA and abnormal morphology has also been reported. However, it is still unknown if it could decrease the percentage of aneuploid spermatozoa. The objective of our prospective study, performed on 16 males with abnormal FISH on spermatozoa, was to assess if MACS columns were useful tools to retain spermatozoa carrying chromosomal abnormalities in semen samples processed after density gradient centrifugation (DGC). The pellet obtained after DGC was subjected to MACS, and sperm FISH analyses were performed both in the eluded fraction and in the fraction retained in the column. The observed frequencies of disomy and nullisomy 13, 18, and 21, X and Y, as well as the diploidy rates in the MACS eluded fraction and the fraction retained in the MACS column were recorded. We observed that the frequencies of aneuploidies in the eluded fraction were lower than in the fraction retained in the MACS column (0.59% vs. 0.75%; p = 0.010). DGC determined a significant reduction in sperm concentration (z-ratio = 2.83; p = 0.005) and a significant increase in sperm progressive motility (z-ratio = -3.5; p < 0.001). MACS also led to a significant reduction in sperm concentration (z-ratio = 3.14; p = 0.002) and a significant increase in progressive motility (z-ratio = -2.59; p = 0.01) when compared with the post-DGC sample. Sperm concentration was similar in the two fractions generated by MACS (z-ratio = 0.63; p = 0.52), while progressive motility was significantly higher in the MACS eluded fraction (z-ratio = 2.42; p = 0.02). According to our results, MACS columns are able to selectively retain spermatozoa carrying chromosomal abnormalities. Furthermore, the performance of DGC and MACS on semen samples leads to an enrichment of progressive motility.

Efectividad, adhesión y usabilidad de un programa de teleneurorrehabilitación para garantizar la continuidad de cuidados en pacientes con daño cerebral adquirido durante la pandemia originada por la COVID-19 / Effectiveness, adherence and usability of a teleneurorehabilitation programme to ensure continuity of care for patients with acquired brain injury during the COVID-19 pandemic

Introducción: La pandemia sanitaria originada por el SARS-CoV-2 (COVID-19) ha limitado el acceso a programas de neurorrehabilitación de muchos pacientes que han sufrido ictus, traumatismos craneoencefálicos o un daño cerebral adquirido por otra causa. Dado que la telerrehabilitación permite la provisión de cuidados en situaciones de distanciamiento social, podría atenuar los efectos negativos del confinamiento. El objetivo de este estudio fue determinar la eficacia, la adhesión y la usabilidad de una intervención de teleneurorrehabilitación dirigida a pacientes con daño cerebral adquirido. Pacientes y métodos: Todos los pacientes incluidos en un programa de neurorrehabilitación presencial en el momento de la declaración del estado de alarma en España con motivo de la COVID-19 y que aceptaron participar en el estudio fueron incluidos en un programa de teleneurorrehabilitación. La eficacia del programa, entendida como una mejora en la independencia, se cuantificó con el índice de Barthel. La adhesión al programa y la usabilidad de la herramienta se investigaron mediante cuestionarios. Resultados: Un total de 146 pacientes, el 70,6% del total, participó en el estudio. Los participantes mejoraron significativamente su independencia y mostraron una mejoría en el índice de Barthel entre el inicio (77,3 ± 28,6) y el fin del programa (82,3 ± 26). La intervención tuvo una gran adhesión (8,1 ± 2,2 sobre 10) y las sesiones en línea fueron el contenido mejor valorado. La herramienta utilizada mostró una elevada usabilidad (50,1 ± 9,9 sobre 60) y pudo ser utilizada sin ayuda por más de la mitad de los participantes. Conclusión: La intervención de teleneurorrehabilitación resultó ser eficaz para mejorar la independencia de los pacientes, y promovió una elevada adhesión y usabilidad.(AU)

Introduction: The health pandemic brought about by SARS-CoV-2 (COVID-19) has limited access to neurorehabilitation programmes for many patients who have suffered stroke, traumatic brain injury or acquired brain damage due to some other cause. As telerehabilitation allows for the provision of care in situations of social distancing, it may mitigate the negative effects of confinement. The aim of this study was to determine the efficacy, adherence and usability of a teleneurorehabilitation intervention for patients with acquired brain injury. Patients and methods: All patients included in a face-to-face neurorehabilitation programme at the time of the declaration of the state of alarm in Spain due to COVID-19 and who agreed to participate in the study were included in a teleneurorehabilitation programme. The effectiveness of the programme, understood as an improvement in independence, was quantified with the Barthel index. Adherence to the programme and usability of the tool were explored through questionnaires. Results: Altogether, 46 patients, accounting for 70.6% of the total, participated in the study. Participants significantly improved their independence and showed an improvement in the Barthel index between the start (77.3 ± 28.6) and the end of the programme (82.3 ± 26). Adherence to the intervention was very high (8.1 ± 2.2 out of 10) and the online sessions were the most highly rated content. The tool used showed a high usability (50.1 ± 9.9 out of 60) and could be used without assistance by more than half the participants. Conclusion: The teleneurorehabilitation intervention was found to be effective in improving patients’ independence, and promoted a high degree of adherence and usability.(AU)

Comparative characterization study of microporous carbons by HRTEM image analysis and gas adsorption.

The present work presents a useful comparison of micropore size distributions (MPSDs) obtained from gas adsorption and image analysis of high-resolution transmission electron micrographs. It is shown that the MPSD obtained for a chemical activated carbon is concordant with that obtained from CO2 adsorption. In addition, this technique has allowed us to obtain the MPSD of a carbon molecular sieve (CMS) prepared in our laboratory by a copyrolysis process, which could only be characterized by CO2 adsorption at 273 K (not by N2 adsorption at 77 K due to diffusional problems). The MPSD obtained by high-resolution transmission electron microscopy (HRTEM) for the CMS is wider than that obtained by CO2 adsorption, suggesting that HRTEM is detecting the closed porosity existing in this sample, which is not accessible to gas adsorption. The existence of closed porosity in the CMS is explained considering the preparation method used. Thus, HRTEM combined with image analysis seems to be useful for structural analysis of narrow micropores including closed porosity.

Synthesis of robust hierarchical silica monoliths by surface-mediated solution/precipitation reactions over different scales: designing capillary microreactors for environmental applications.

A synthetic procedure to prepare novel materials (surface-mediated fillings) based on robust hierarchical monoliths is reported. The methodology includes the deposition of a (micro- or mesoporous) silica thin film on the support followed by growth of a porous monolithic SiO2 structure. It has been demonstrated that this synthesis is viable for supports of different chemical nature with different inner diameters without shrinkage of the silica filling. The formation mechanism of the surface-mediated fillings is based on a solution/precipitation process and the anchoring of the silica filling to the deposited thin film. The interaction between the two SiO2 structures (monolith and thin film) depends on the porosity of the thin film and yields composite materials with different mechanical stability. By this procedure, capillary microreactors have been prepared and have been proved to be highly active and selective in the total and preferential oxidation of carbon monoxide (TOxCO and PrOxCO).

Optimizing the performance of catalytic traps for hydrocarbon abatement during the cold-start of a gasoline engine.

A key target to reduce current hydrocarbon emissions from vehicular exhaust is to improve their abatement under cold-start conditions. Herein, we demonstrate the potential of factorial analysis to design a highly efficient catalytic trap. The impact of the synthesis conditions on the preparation of copper-loaded ZSM-5 is clearly revealed by XRD, N2 sorption, FTIR, NH3-TPD, SEM and TEM. A high concentration of copper nitrate precursor in the synthesis improves the removal of hydrocarbons, providing both strong adsorption sites for hydrocarbon retention at low temperature and copper oxide nanoparticles for full hydrocarbon catalytic combustion at high temperature. The use of copper acetate precursor leads to a more homogeneous dispersion of copper oxide nanoparticles also providing enough catalytic sites for the total oxidation of hydrocarbons released from the adsorption sites, although lower copper loadings are achieved. Thus, synthesis conditions leading to high copper loadings jointly with highly dispersed copper oxide nanoparticles would result in an exceptional catalytic trap able to reach superior hydrocarbon abatement under highly demanding operational conditions.

On the origin of the high capacitance of nitrogen-containing carbon nanotubes in acidic and alkaline electrolytes.

The synthesis of nitrogenated carbon nanotubes (N-CNTs) with up to 6.1 wt% N, via the use of pyridine as the nitrogen containing carbon precursor, can provide a facile route to significantly enhance the low intrinsic specific capacitance of carbon nanotubes. The nitrogen functionalities determine this, at least, five-fold increase of the specific capacitance.