Hierarchical Nanocomposites Electrospun Carbon NanoFibers/Carbon Nanotubes as a Structural Element of Potentiometric Sensors

This work proposes new carbon materials for intermediate layers in solid-contact electrodes sensitive for potassium ions. The group of tested materials includes electrospun carbon nanofibers, electrospun carbon nanofibers with incorporated cobalt nanoparticles and hierarchical nanocomposites composed of carbon nanotubes deposited on nanofibers with different metal nanoparticles (cobalt or nickel) and nanotube density (high or low). Materials were characterized using scanning electron microscopy and contact angle microscopy. Electrical parameters of ready-to-use electrodes were characterized using chronopotentiometry and electrochemical impedance spectroscopy. The best results were obtained for potassium electrodes with carbon nanofibers with nickel-cobalt nanoparticles and high density of nanotubes layer: the highest capacity value (330 µF), the lowest detection limit (10^−6.3 M), the widest linear range (10⁻⁶–10⁻¹) and the best reproducibility of normal potential (0.9 mV). On the other hand the best potential reversibility, the lowest potential drift (20 μV·h⁻¹) in the long-term test and the best hydrophobicity (contact angle 168°) were obtained for electrode with carbon nanofibers with cobalt nanoparticles and high density of carbon nanotubes. The proposed electrodes can be used successfully in potassium analysis of real samples as shown in the example of tomato juices.     

Effect of melatonin on sleep, behavior, and cognition in ADHD and chronic sleep-onset insomnia

OBJECTIVE: To investigate the effect of melatonin treatment on sleep, behavior, cognition, and quality of life in children with attention-deficit/hyperactivity disorder (ADHD) and chronic sleep onset insomnia. METHOD: A total of 105 medication-free children, ages 6 to 12 years, with rigorously diagnosed ADHD and chronic sleep onset insomnia participated in a randomized, double-blind, placebo-controlled trial using 3 or 6 mg melatonin (depending on body weight), or placebo for 4 weeks. Primary outcome parameters were actigraphy-derived sleep onset, total time asleep, and salivary dim light melatonin onset. RESULTS: Sleep onset advanced by 26.9 +/- 47.8 minutes with melatonin and delayed by 10.5 +/- 37.4 minutes with placebo (p < .0001). There was an advance in dim light melatonin onset of 44.4 +/- 67.9 minutes in melatonin and a delay of 12.8 +/- 60.0 minutes in placebo (p < .0001). Total time asleep increased with melatonin (19.8 +/- 61.9 minutes) as compared to placebo (-13.6 +/- 50.6 minutes; p = .01). There was no significant effect on behavior, cognition, and quality of life, and significant adverse events did not occur. CONCLUSION: Melatonin advanced circadian rhythms of sleep-wake and endogenous melatonin and enhanced total time asleep in children with ADHD and chronic sleep onset insomnia; however, no effect was found on problem behavior, cognitive performance, or quality of life.     

Selecting features for BCI control based on a covert spatial attention paradigm

Covert attention to spatial locations in the visual field is a relatively new control signal for brain–computer interfaces. Previous EEG research has shown that trials can be classified by thresholding based on left and right hemisphere alpha power in covert spatial attention paradigms. We reexamine the covert attention paradigm based on MEG measurements for fifteen subjects. It is shown that classification performance can be improved by applying sparse logistic regression in order to select a subset of the sensors specific to each subject as the basis for classification. Furthermore, insight is gained into how classification performance changes as a function of the length of the attention period and as a function of the number of trials. Classification performance steadily increases as the length of the attention period over which is averaged is increased, although this does not necessarily translate into higher bit rates. Good classification performance using early components of the attention period may be related to evoked response. With regard to the number of used trials, classification performance became maximal after 150 samples had been obtained, requiring a training time of approximately eleven minutes under the current experimental paradigm.     

Epidemiologic and Genomic Analysis of SARS-CoV-2 Delta Variant Superspreading Event in Nightclub,the Netherlands,June 2021

We report a severe acute respiratory syndrome coronavirus 2 superspreading event in the Netherlands after distancing rules were lifted in nightclubs, despite requiring a negative test or vaccination. This occurrence illustrates the potential for rapid dissemination of variants in largely unvaccinated populations under such conditions. We detected subsequent community transmission of this strain.