Biphasic Epoxidation Reaction in the Absence of Surfactants - Integration of Reaction and Separation Steps in Microtubular Reactors

This paper presents a paradigm shift with respect to the current direction of biphasic reactions in surfactant-free emulsions. Herein, the contact area between both phases is simply sustained by the reactor design (i.e., diameter of the tubular reactor) compared to the current trend of using reversible/switchable emulsions where the addition of an external agent (e.g., bistable surfactant, magnetic particles, etc.) is required. In this way, temporally stable phase dispersions using microtubular reactors facilitate the integration of reaction and separation steps in biphasic systems without the need for energy-intensive downstream separation steps. In this study, we demonstrate this innovative tool in the epoxidation reaction of sunflower oil with hydrogen peroxide. Using a combination of mechanistic and kinetic studies, we demonstrate that the poor solubility of the catalytic species in the oil phase may be used advantageously, allowing ready recyclability of catalyst (and oxidant) in consecutive runs.The authors thank the UK Engineering and Physical Sciences Research Council for funding via the EPSRC Doctoral Training Centre in Sustainable Chemical Technologies, University of Bath (Grant No. EP/G03768X/1) and a L.T.-M.’s Fellowship award (Grant No. EP/L020432/2).This is the author accepted manuscript. The final version is available from the American Chemical Society via http://dx.doi.org/10.1021/acssuschemeng.6b0028

Effect of support of Co-Na-Mo catalysts on the direct conversion of CO<inf>2</inf> to hydrocarbons

This study of the effect of support of Co-Na-Mo based catalysts on the direct hydrogenation of CO$_2$ into hydrocarbons (HC) provides guidelines for the design of catalysts for CO$_2$ conversion. We demonstrate that the surface area of the support and the metal-support interaction have a key role determining the cobalt crystallite size and consequently the activity of the system. Cobalt particles with sizes <2 nm supported on MgO present low reverse water gas shift conversion with negligible Fischer-Tropsch activity. Increasing the cobalt particle size to ~15 nm supported on SiO$_2$ and ZSM-5 supports not only substantially increases the CO$_2$ conversion but it also provides high HC selectivities. Further increase of the cobalt particle size to 25–30 nm has a detrimental effect on the global CO$_2$ conversion with HC:CO ratios below 1, however, lower methane selectivity and enhanced formation of unsaturated HC products are achieved. Additionally, the metal-support interaction potentially also has a strong effect on the growth chain probability of the formed hydrocarbons, increasing as the metal-support interaction increases. These evidences demonstrate that CO$_2$ conversion and hydrocarbon distribution can be tuned towards desired products by controlled catalyst design.University of BathThis is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jcou.2016.06.00

Effect of nanostructured ceria as support for the iron catalysed hydrogenation of CO2 into hydrocarbons.

This paper demonstrates the key role of the property-structure relationship of the support on iron/ceria catalysts on the hydrocarbon selectivity and olefin-to-paraffin ratio for the direct hydrogenation of carbon dioxide into hydrocarbons. The effect is directly related to the reducibility of the different nanostructured ceria supports and their interaction with the iron particles. Herein, we demonstrate that the iron-based catalysts can be modified not only by the addition of promoters, commonly reported in the literature, but also by careful control of the morphology of the ceria support.The authors thanks the UK Engineering and Physical Science Research Council (EPSRC, grant numbers: EP/L020432/2 and EP/G03768X/1).This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5CP07788

N-Doped Fe@CNT for Combined RWGS/FT CO ₂ Hydrogenation

The conversion of CO₂ into chemical fuels represents an attractive route for greenhouse gas emission reductions and renewable energy storage. Iron nanoparticles supported on graphitic carbon materials (e.g., carbon nanotubes (CNTs)) have proven themselves to be effective catalysts for this process. This is due to their stability and ability to support simultaneous reverse water-gas shift (RWGS) and Fischer–Tropsch (FT) catalysis. Typically, these catalytic iron particles are postdoped onto an existing carbon support via wet impregnation. Nitrogen doping of the catalyst support enhances particle–support interactions by providing electron-rich anchoring sites for nanoparticles during wet impregnation. This is typically credited for improving CO₂ conversion and product selectivity in subsequent catalysis. However, the mechanism for RWGS/FT catalysis remains underexplored. Current research places significant emphasis on the importance of enhanced particle–support interactions due to N doping, which may mask further mechanistic effects arising from the presence or absence of nitrogen during CO₂ hydrogenation. Here we report a clear relationship between the presence of nitrogen in the CNT support of an RWGS/FT iron catalyst and significant shifts in the activity and product distribution of the reaction. Particle–support interactions are maximized (and discrepancies between N-doped and pristine support materials are minimized) by incorporating iron and nitrogen directly into the support during synthesis. Reactivity is thus rationalized in terms of the influence of C–N dipoles in the support upon the adsorption properties of CO₂ and CO on the surface rather than improved particle–support interactions. These results show that the direct hydrogenation of CO₂ to hydrocarbons is a potentially viable route to reduce carbon emissions from human activities

Post-Translational Modifications Modulate Ligand Recognition by the Third PDZ Domain of the MAGUK Protein PSD-95

The relative promiscuity of hub proteins such as postsynaptic density protein-95 (PSD-95) can be achieved by alternative splicing, allosteric regulation, and post-translational modifications, the latter of which is the most efficient method of accelerating cellular responses to environmental changes in vivo. Here, a mutational approach was used to determine the impact of phosphorylation and succinimidation post-translational modifications on the binding affinity of the postsynaptic density protein-95/discs large/zonula occludens-1 (PDZ3) domain of PSD-95. Molecular dynamics simulations revealed that the binding affinity of this domain is influenced by an interplay between salt-bridges linking the α3 helix, the β2–β3 loop and the positively charged Lys residues in its high-affinity hexapeptide ligand KKETAV. The α3 helix is an extra structural element that is not present in other PDZ domains, which links PDZ3 with the following SH3 domain in the PSD-95 protein. This regulatory mechanism was confirmed experimentally via thermodynamic and NMR chemical shift perturbation analyses, discarding intra-domain long-range effects. Taken together, the results presented here reveal the molecular basis of the regulatory role of the α3 extra-element and the effects of post-translational modifications of PDZ3 on its binding affinity, both energetically and dynamically.This research was supported by grants CVI-05915, from the Andalusian Regional Government (http://www.juntadeandalucia.es), BIO2009-13261-C02 and BIO2012-39922-C02, from the Spanish Ministry of Science and Innovation (http://www.idi.mineco.gob.es/portal/site​/MICINN/) and FEDER. JMC received a postdoctoral contract from the Spanish Ministry of Science and Innovation. CCV was a recipient of a Formación de Personal Investigador fellowship from the Spanish Ministry of Science and Innovation

Focus on cardiologic findings in 30 children with PANS/PANDAS. an italian single-center observational study

Objective: Cardiac involvement in PANS has not been clarified relying on the scientific literature available until today. It is known that streptococcal infections play a role in the etiology of a great number of diseases including Sydenham chorea and rheumatic fever, among others. Based on the suspected pathogenesis of PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) reported in the medical literature, we decided to investigate the cardiologic involvement in children with a recent PANS/PANDAS diagnosis. Methods: The study population satisfies PANS (1) and PANDAS (2) criteria of diagnoses. Cardiologic assessment was performed through clinical examination, electrocardiography, and echocardiography. Results: In the selected pediatric population, a significant number of children presented mitral valve involvement, systolic murmurs and electrocardiographic abnormalities. High ASLOT levels did not seem to be associated to a cardiac involvement. Conclusions: Often PANS is difficult to diagnose because it is little known by physicians and most of the cardiologic findings described in this study are common among the healthy pediatric population. Also, ASLOT levels seems not to be predictive of cardiac involvement. Furthermore, the existence of PANDAS as a clinical entity is associated with a group of anti-neuronal autoantibodies found in Sydenham chorea is still controversial. We recommend a complete cardiologic evaluation in those children who meet the PANS/PANDAS diagnostic criteria