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We report the synthesis and characterization of nanocrystalline LiZnP. The reaction proceeds through a zinc metal intermediate followed by rapid incorporation of lithium and phosphorus. We demonstrate flexibility in the selection of Li, Zn, and P precursors, as well as extension of this method to other half-Heusler phases.
RESUMO
Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.
RESUMO
BACKGROUND: Because of a high risk of recurrence of ischemic events, some patients may be candidates for readministration of intravenous (IV) alteplase. METHODS: We performed a single-center review and performed a search on PubMed from January 1966 to April 2014 for cases of readministration of alteplase. Favorable outcome was defined by a modified Rankin scale of 0 to 2 at discharge or at 1 to 3 months, improvement of greater than or equal to 4 points within 24 hours in the National Institutes of Health Stroke Scale score, or as a major improvement in the 72-hour National Institutes of Health Stroke Scale score. RESULTS: Four ischemic stroke patients underwent readministration of IV alteplase in our single-center review. None of the patients had symptomatic or asymptomatic intracerebral hemorrhage.In 2 patients, IV alteplase had been administered for a previous acute ischemic stroke, 6 and 49 days before the index ischemic stroke.At discharge, both patients had a favorable outcome. A total of 22 cases of readministration of alteplase for ischemic stroke have been reported in literature. The mean interval between the 2 administrations of alteplase was 428 days (range, 3 hours to 2280 days).Asymptomatic post thrombolytic intracerebral hemorrhages were seen in 2 patients. Favorable outcome was seen in 16 patients. A total of 9 underwent readministration of IV alteplase within 3 months for recurrent ischemic stroke. Favorable outcome was seen in 5 of these 9 patients. CONCLUSIONS: We observed a relatively high rate of favorable outcomes and a small rate of adverse events after readministration of IV alteplase in ischemic stroke patients.
