Platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) with atomically dispersed FeN4 sites have emerged as a potential replacement for low-PGM catalysts in acidic polymer electrolyte fuel cells (PEFCs).
The
durability of alkaline anion exchange membrane (AEM) electrolyzers
is a critical requirement for implementing this technology in cost-effective
hydrogen production. Here, we report that the electrochemical oxidation
of the adsorbed phenyl group (found in the ionomer) on oxygen evolution
catalysts produces phenol, which may cause performance deterioration
in AEM electrolyzers. In-line 1H NMR kinetic analyses of
phenyl oxidation in a model organic cation electrolyte shows that
catalyst type significantly impacts the phenyl oxidation rate at an
oxygen evolution potential. Density functional theory calculations
show that the phenyl adsorption is a critical factor determining the
phenyl oxidation. This research provides a path for the development
of more durable AEM electrolyzers with components that can minimize
the adverse impact induced by the phenyl group oxidation, such as
the development of novel ionomers with fewer phenyl moieties or catalysts
with less phenyl-adsorbing character.
Over the last decade, several stable anion exchange polymer electrolytes have been developed for electrochemical devices. Herein, we investigate how the chemical structure and physical properties of polymer electrolytes affect...
Photodynamic therapy (PDT) uses the combination of nontoxic dyes and harmless visible light to produce reactive oxygen species that can kill cancer cells and infectious microorganisms. Due to the tendency of most photosensitizers (PS) to be poorly soluble and to form nonphotoactive aggregates, drug-delivery vehicles have become of high importance. The nanotechnology revolution has provided many examples of nanoscale drug-delivery platforms that have been applied to PDT. These include liposomes, lipoplexes, nanoemulsions, micelles, polymer nanoparticles (degradable and nondegradable), and silica nanoparticles. In some cases (fullerenes and quantum dots), the actual nanoparticle itself is the PS. Targeting ligands such as antibodies and peptides can be used to increase specifi city. Gold and silver nanoparticles can provide plasmonic enhancement of PDT. Two-photon excitation or optical upconversion can be used instead of one-photon excitation to increase tissue penetration at longer wavelengths. Finally, after sections on in vivo studies and nanotoxicology, we attempt to answer the title question, " can nanotechnology potentiate PDT ? "
Twenty-eight of 45 patients (62.2%) revealed subjective improvement in tinnitus with TENS. TENS was more effective in patients with low-frequency tinnitus or with mild hearing loss. Symptomatic improvement in the electrical stimulation group was achieved for 1 month in most patients.
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