Nano-scale insights regarding coke formation in zeolite SSZ-13 subject to the methanol-to-hydrocarbons reaction.

The methanol-to-hydrocarbons (MTH) process, commonly catalyzed by zeolites, is of great commercial interest and therefore widely studied both in industry and academia. However, zeolite-based catalyst materials are notoriously hard to study at the nano-scale. Atom probe tomography (APT) is uniquely positioned among the suite of characterization techniques, as it can provide 3D chemical information with sub-nm resolution. In this work, we have used APT to study the nano-scale coking behavior of zeolite SSZ-13 and its relation to bulk coke formation on the macro-/micro-scale studied with operando and in situ UV-vis spectroscopy and microscopy. Radial distribution function analysis (RDF) of the APT data revealed short carbon-carbon length scale affinities, consistent with the formation of larger aromatic molecules (coke species). Using nearest neighbor distribution (NND) analysis, an increase in the homogeneity of carbon was found with increasing time-on-stream. However, carbon clusters could not be isolated due to spatial noise and limited clustering. Therefore, it was found that the coke formation in zeolite SSZ-13 (CHA) is reasonably homogeneous on the nano-scale, and is rather similar to the silicoaluminophosphate analogue SAPO-34 (CHA) but different in nano-scale coking behavior compared to previously studied zeolite ZSM-5 (MFI).

Highly efficient hydrogen production through ethanol photoreforming by a carbon nanocone/Pd@TiO2 hybrid catalyst.

Production of molecular hydrogen (H2) is becoming an increasingly prominent process, due to high expectations as a new green energy carrier and key reagent for many industrial processes. Herein we report the high efficiency of H2 production via photoreforming of ethanol using a catalyst based on hierarchical carbon nanocones hybridised with an inorganic layer of nanocrystalline TiO2 containing Pd nanoparticles.

Dye-sensitized photocatalytic hydrogen production: distinct activity in a glucose derivative of a phenothiazine dye.

A thiophene-based donor-acceptor phenothiazine dye has been functionalized with a peripheral glucose unit (PTZ-GLU) to bust its affinity to water and enhance dye-sensitized photogeneration of hydrogen. Compared to the corresponding alkyl derivative (PTZ-ALK), as well as the common hydrophilic triethylene glycol substitution (PTZ-TEG), the sugar derivative shows a lower contact angle; PTZ-GLU performed twice more efficient than PTZ-TEG in the photogeneration of hydrogen in terms of evolved gas and turnover number.

Thunderstorm asthma: a critical appraisal based on clinical practice

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The treatment of internal anal sphincter achalasia with botulinum toxin.

Internal anal sphincter (IAS) achalasia is a disorder of defecation in which the IAS fails to relax. Botulinum toxin (BT), which has been successfully used to relax the anal and lower esophageal sphincters, was injected twice into the IAS of one adolescent and three infants with manometric, radiologic, and in 2 cases histochemical diagnosis of anal achalasia: in the adolescent a third injection was necessary. Spontaneous defecation was achieved in all patients following the second injection. In one case a diagnosis of short-segment Hirschsprung's disease was obtained after the second injection. Local infiltration of BT into the IAS proved effective in the treatment of IAS achalasia. Double-blind studies and longer follow-up periods are needed to better evaluate these preliminary results and define the limits of this promising therapy.