Morphology controls the thermoelectric power factor of a doped semiconducting polymer.

The electrical performance of doped semiconducting polymers is strongly governed by processing methods and underlying thin-film microstructure. We report on the influence of different doping methods (solution versus vapor) on the thermoelectric power factor (PF) of PBTTT molecularly p-doped with F n TCNQ (n = 2 or 4). The vapor-doped films have more than two orders of magnitude higher electronic conductivity (σ) relative to solution-doped films. On the basis of resonant soft x-ray scattering, vapor-doped samples are shown to have a large orientational correlation length (OCL) (that is, length scale of aligned backbones) that correlates to a high apparent charge carrier mobility (µ). The Seebeck coefficient (α) is largely independent of OCL. This reveals that, unlike σ, leveraging strategies to improve µ have a smaller impact on α. Our best-performing sample with the largest OCL, vapor-doped PBTTT:F4TCNQ thin film, has a σ of 670 S/cm and an α of 42 µV/K, which translates to a large PF of 120 µW m-1 K-2. In addition, despite the unfavorable offset for charge transfer, doping by F2TCNQ also leads to a large PF of 70 µW m-1 K-2, which reveals the potential utility of weak molecular dopants. Overall, our work introduces important general processing guidelines for the continued development of doped semiconducting polymers for thermoelectrics.

Role of Crystallization in the Morphology of Polymer:Non-fullerene Acceptor Bulk Heterojunctions.

Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages (VOC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing. The kinetics of the phase transformation process of HPI-BT during thermal annealing were investigated through in situ grazing incidence wide-angle X-ray scattering studies, atomic force microscopy, and transmission electron microscopy. The HPI-BT acceptor crystallizes during film formation to form micron-sized domains embedded within the film center and a donor rich capping layer at the cathode interface reducing efficient charge extraction. Thermal annealing changes the surface composition and improves charge extraction. This study reveals the need for complementary methods to investigate the morphology of BHJs.

First aid for seizures: the importance of education and appropriate response.

In most circumstances, first aid for seizures aims to protect the individual from harm during a seizure. Many people harbor misconceptions about or simply do not know how to respond to a seizure. Guidelines for seizure first aid from the Epilepsy Foundation are readily available and widely distributed, yet data from surveys and studies illustrate a deep unmet need in seizure first aid education. Lack of knowledge increases the potential for inappropriate or inadequate responses by parents, teachers, coworkers, and the public at large to repetitive or prolonged seizures, and the associated discomfort about how to provide first aid also can contribute to the general stigma associated with epilepsy. Clinicians play a key role in educating patients, parents, caregivers, and the community about how to respond to an individual who is having a seizure. This article reviews the data regarding seizure first aid knowledge among the various groups that may be called on to respond to a repetitive or prolonged seizure, highlights important goals of seizure first aid (including the prevention of status epilepticus) that should be relayed to these groups, and discusses the positive impact of seizure first aid education.

Safety of rapid intravenous valproate infusion in pediatric patients.

In order to investigate the safety of rapidly infused intravenous valproate in children with seizures, the drug was administered to 18 patients (age range, 1-16 years) at doses ranging from 7.5 to 41.5 mg/kg and rates of 1.5 to 11 mg/kg per minute. Forty-eight intravenous valproate doses were administered during 19 hospital admissions (range, 1-16 doses per admission). Only one adverse event was reported; a 9-year-old male experienced burning at the infusion site while receiving 660 mg intravenous valproate at 6 mg/kg per minute. The patient tolerated three subsequent infusions (one of 330 mg and two of 165 mg) at the same rate with no further discomfort. Electrocardiogram results, available for 18 admissions, revealed no arrhythmias, bradycardias, or hypotensive episodes. No abnormal laboratory results were reported. Rapid intravenous valproate infusion appears to be safe in pediatric patients.

Extended-release divalproex in child and adolescent outpatients with epilepsy.

PURPOSE: To determine whether valproic acid [divalproex (DVP)] extended-release, administered at a higher proportionate once-daily dosage, can be safely substituted for delayed-release or sprinkle in pediatric patients with epilepsy. METHODS: Patients between ages 6 and 17 years with stable epilepsy taking DVP were randomized to 7 days of either DVP delayed-release/sprinkle (at the usual daily dose taken before study entry) or extended-release DVP (daily dose, 8% to 25% higher than their usual dose), and then (crossed over to) 7 days of the comparator formulation. Patient's clinical status was evaluated at a screening visit and on days 8 and 15, and with telephone follow-up 1 month after study completion. RESULTS: No statistically significant difference in mean plasma VPA levels measured at the end of treatment was observed: 99, 92, and 103 mug/ml with the delayed-release tablets (n = 4), the sprinkle formulation (n = 11), and the extended-release tablets (n = 16), respectively. Seizure-control rates were stable during patients' use of the extended-release formulation. None of the study patients experienced a treatment-related adverse event. CONCLUSIONS: The total daily dose for patients taking the delayed-formulation may need to be increased by < or = 20% when they are switched to the extended-release formulation. When switching from sprinkles to the extended-release formulation, individual variability must be considered. In patients who have VPA levels near the very high end of the therapeutic range (>100 microg/ml), it may be more prudent to make only minor modifications to the total daily dose during conversion and then to individualize the DVP extended-release dose based on plasma levels.