Search

P2-type Na 0.67 Ni 0.33 Mn 0.67 O 2 has attracted considerable attraction as a cathode material for sodium-ion batteries owing to its high operating voltage and theoretical specific capacity. However, when the charging voltage is higher than 4.2 V, the Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode undergoes a detrimental irreversible phase transition of P2-O2, leading to a drastic decrease in specific capacity. To address this challenge, we implemented a Cu-doping strategy (Na 0.67 Ni 0.23 Cu 0.1 Mn 0.67 O 2 ) in this work to stabilize the structure of the transition metal layer. The stabilization strategy involved reinforcing the transition metal-oxygen (TMO) bonds, particularly the MnO bond and inhibiting interlayer slip during deep desodiation. As a result, the irreversible phase transition voltage is delayed, with the threshold voltage increasing from 4.2 to 4.4 V. Ex-situ X-ray diffraction measurements revealed that the Na 0.67 Ni 0.23 Cu 0.1 Mn 0.67 O 2 cathode maintains the P2 phase within the voltage window of 2.5-4.3 V, whereas the P2-Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode transforms entirely into O2-type Na 0.67 Ni 0.33 Mn 0.67 O 2 when the voltage exceeds 4.3 V. Furthermore, absolute P2-O2 phase transition of the Na 0.67 Ni 0.23 Cu 0.1 Mn 0.67 O 2 cathode occurred at 4.6 V, indicating that Cu 2+ doping enhances the stability of the layer structure and increases the threshold voltage. The resulting Na 0.67 Ni 0.23 Cu 0.1 Mn 0.67 O 2 cathode exhibited superior electrochemical properties, demonstrating an initial reversible specific capacity of 89.1 mAh/g at a rate of 2C (360 mA g -1 ) and retaining more than 78 % of its capacity after 500 cycles., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The membranes of auditory and vestibular afferent neurons each contain diverse groups of ion channels that lead to heterogeneity in their intrinsic biophysical properties. Pioneering work in both auditory- and vestibular-ganglion physiology have individually examined this remarkable diversity, but there are few direct comparisons between the two ganglia. Here the firing patterns recorded by whole-cell patch-clamping in neonatal vestibular- and spiral ganglion neurons are compared. Indicative of an overall heterogeneity in ion channel composition, both ganglia exhibit qualitatively similar firing patterns ranging from sustained-spiking to transient-spiking in response to current injection. The range of resting potentials, voltage thresholds, current thresholds, input-resistances, and first-spike latencies are similarly broad in both ganglion groups. The covariance between several biophysical properties (e.g., resting potential to voltage threshold and their dependence on postnatal age) was similar between the two ganglia. Cell sizes were on average larger and more variable in VGN than in SGN. One sub-group of VGN stood out as having extra-large somata with transient-firing patterns, very low-input resistance, fast first-spike latencies, and required large current amplitudes to induce spiking. Despite these differences, the input resistance per unit area of the large-bodied transient neurons was like that of smaller-bodied transient-firing neurons in both VGN and SGN, thus appearing to be size-scaled versions of other transient-firing neurons. Our analysis reveals that although auditory and vestibular afferents serve very different functions in distinct sensory modalities, their biophysical properties are more closely related by firing pattern and cell size than by sensory modality., Competing Interests: The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Kalluri.)

Background: Voltage criteria for ventricular mapping have been obtained from small series of patients and prioritizing high specificity., Objective: The purpose of this study was to analyse the potential influence of contact force (CF) on voltage mapping and to define voltage cutoff values for right ventricular (RV) scar using the tetralogy of Fallot as a model of transmural RV scar and magnetic resonance imaging (MRI) as reference., Methods: Fourteen patients (age 32.6 ± 14.3 years; 5 female) with repaired tetralogy of Fallot underwent high-resolution cardiac MRI (1.25 × 1.25 × 2.5 mm). Scar, defined as pixels with intensity >50% maximum, was mapped over the RV geometry and merged within the CARTO system to RV endocardial voltage maps acquired using a 3.5-mm ablation catheter with CF technology (SmartTouch, Biosense Webster)., Results: In total, 2446 points were analyzed, 915 within scars and 1531 in healthy tissue according to MRI. CF correlated to unipolar (ρ = 0.186; P <.001) and bipolar voltage in healthy tissue (ρ = 0.245; P <.001) and in scar tissue. Receiver operating characteristic curve analysis excluding points with very low CF (<5g) identified optimal voltage cutoffs of 5.19 mV for unipolar voltage and 1.76 mV for bipolar voltage, yielding sensitivity/specificity of 0.89/0.85 and 0.9/0.9, respectively., Conclusion: CF is an important factor to be taken into account for voltage mapping. If good CF is applied, unipolar and bipolar voltage cutoffs of 5.19 mV and 1.76 mV are optimal for identifying RV scar on endocardial mapping with the SmartTouch catheter. Data on the diagnostic accuracy of different voltage cutoff values are provided., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

KCNQ/K v 7 channels form a slow noninactivating K + current, also known as the M current. They activate in the subthreshold range of membrane potentials and regulate different aspects of excitability in neurons of the central nervous system. In spinal motoneurons (MNs), KCNQ/K v 7 channels have been identified in the somata, axonal initial segment, and nodes of Ranvier, where they generate a slow, noninactivating, K + current sensitive to both muscarinic receptor-mediated inhibition and KCNQ/K v 7 channel blockers. In this study, we thoroughly reevaluated the function of up- and downregulation of KCNQ/K v 7 channels in mouse immature spinal MNs. Using electrophysiological techniques together with specific pharmacological modulators of the activity of KCNQ/K v 7 channels, we show that enhancement of the activity of these channels decreases the excitability of spinal MNs in mouse neonates. This action on MNs results from a combination of hyperpolarization of the resting membrane potential, a decrease in the input resistance, and depolarization of the voltage threshold. On the other hand, the effect of inhibition of KCNQ/K v 7 channels suggested that these channels play a limited role in regulating basal excitability. Computer simulations confirmed that pharmacological enhancement of KCNQ/K v 7 channel activity decreases excitability and also suggested that the effects of inhibition of KCNQ/K v 7 channels on the excitability of spinal MNs do not depend on a direct effect in these neurons but likely on spinal cord synaptic partners. These results indicate that KCNQ/K v 7 channels have a fundamental role in the modulation of the excitability of spinal MNs acting both in these neurons and in their local presynaptic partners., (Copyright © 2016 the American Physiological Society.)

Background: Studies analyzing optimal voltage thresholds for scar detection with electroanatomic mapping frequently lack a gold standard for comparison., Objective: The purpose of this study was to use a porcine infarct model with ex vivo magnetic resonance imaging (MRI) integration to characterize the relationship between interelectrode spacing and bipolar voltage thresholds and examine the influence of 3-dimensional scar on unipolar voltages., Methods: Thirty-two combined endocardial-epicardial electroanatomic maps were created in 8 postinfarct porcine subjects (bipolar 2-mm, 5-mm, and 8-mm interelectrode spacing and unipolar) for comparison with ex vivo MRI. Two thresholds were compared: (1) 95% normal distribution and (2) best fit to MRI. Direct electrogram analysis was performed in regions across from MRI-defined scar and adjacent to scar border zone., Results: A linear increase in optimal thresholds was observed with wider bipole spacing. The 95% thresholds for scar were lower than MRI-matched thresholds with moderate sensitivity for nontransmural scar (54% endo, 63% epi). Unipolar endocardial scar area exceeded MRI-defined scar, resulting in mismatched false scar in 5 of 8 (63%). Endocardial and epicardial unipolar voltages were lower than normal in regions adjacent and across from scar., Conclusion: Variations in interelectrode spacing necessitate tailored bipolar voltage thresholds to optimize scar detection. Statistical 95% thresholds appear to be conservative and not fully sensitive for the detection of scar defined by high-resolution ex vivo MRI. In the presence of endocardial scar, unipolar mapping to quantitatively characterize epicardial scar may be overly sensitive due to 3-dimensional spatial averaging., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The spiral ganglion conveys afferent auditory information predominantly through a single class of type I neurons that receive signals from inner hair cell sensory receptors. These auditory primary afferents, like in other systems (Puopolo and Belluzzi, 1998; Gascon and Moqrich, 2010; Leao et al., 2012) possess a marked diversity in their electrophysiological features (Taberner and Liberman, 2005). Consistent with these observations, when the auditory primary afferents were assessed in neuronal explants separated from their peripheral and central targets it was found that individual neurons were markedly heterogeneous in their endogenous electrophysiological features. One aspect of this heterogeneity, obvious throughout the ganglion, was their wide range of excitability as assessed by voltage threshold measurements (Liu and Davis, 2007). Thus, while neurons in the base differed significantly from apical and middle neurons in their voltage thresholds, each region showed distinctly wide ranges of values. To determine whether the resting membrane potentials (RMPs) of these neurons correlate with the threshold distribution and to identify the ion channel regulatory elements underlying heterogeneous neuronal excitability in the ganglion, patch-clamp recordings were made from postnatal day (P5-8) murine spiral ganglion neurons in vitro. We found that RMP mirrored the tonotopic threshold distribution, and contributed an additional level of heterogeneity in each cochlear location. Pharmacological experiments further indicated that threshold and RMP was coupled through the Kv1 current, which had a dual impact on both electrophysiological parameters. Whereas, hyperpolarization-activated cationic channels decoupled these two processes by primarily affecting RMP without altering threshold level. Thus, beyond mechanical and synaptic specializations, ion channel regulation of intrinsic membrane properties imbues spiral ganglion neurons with different excitability levels, a feature that contributes to primary auditory afferent diversity., (Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.)

An earlier study demonstrated changes in synaptic efficacy and seizure susceptibility in adult rat brain slices following extremely low-frequency magnetic field (ELF-MF) exposure. The developing embryonic and early postnatal brain may be even more sensitive to MF exposure. The aim of the present study was to determine the effects of a long-term ELF-MF (0.5 and 3 mT, 50 Hz) exposure on synaptic functions in the developing brain. Rats were treated with chronic exposure to MF during two critical periods of brain development, i.e. in utero during the second gestation week or as newborns for 7 days starting 3 days after birth, respectively. Excitability and plasticity of neocortical and hippocampal areas were tested on brain slices by analyzing extracellular evoked field potentials. We demonstrated that the basic excitability of hippocampal slices (measured as amplitude of population spikes) was increased by both types of treatment (fetal 0.5 mT, newborn 3 mT). Neocortical slices seemed to be responsive mostly to the newborn treatment, the amplitude of excitatory postsynaptic potentials was increased. Fetal ELF-MF exposure significantly inhibited the paired-pulse depression (PPD) and there was a significant decrease in the efficacy of LTP (long-term potentiation induction) in neocortex, but not in hippocampus. On the other hand, neonatal treatment had no significant effect on plasticity phenomena. Results demonstrated that ELF-MF has significant effects on basic neuronal functions and synaptic plasticity in brain slice preparations originating from rats exposed either in fetal or in newborn period., (Copyright © 2013 ISDN. Published by Elsevier Ltd. All rights reserved.)

Electrophysiological properties of lumbar α-motoneurons change after chronic increases and decreases in hindlimb neuromuscular activity. Although modeling of these changes suggests that motoneurons probably alter gene expression in these situations, there is no evidence that this is the case. In this study, we measured the content of several mRNAs in lumbar motoneurons, harvested using laser capture microdissection, from rats previously subjected to normal cage activity, voluntary wheel exercise for 16weeks, and forced treadmill training for 7days and 16weeks. As a result of the prolonged daily treadmill training, but not the voluntary wheel training, significant increases occurred in muscle peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1α) mRNA, and in muscle PGC-1α and cytochrome oxidase proteins, in soleus and plantaris muscles. Significant changes in mRNA contents (decreases) were evident for the receptors 5-hydroxytryptamine (serotonin) receptor 1A (5HT1a), GABA A receptor, subunit alpha 2 (GABAAα2), and for the potassium conductance calcium-activated channel protein (SK2) in the motoneurons from 16-week-trained rats, and for glutamate receptor, metabotropic 1 (mGluR1) in the voluntary wheel-trained rats. Motoneurons from 16-week treadmill-trained rats also did not demonstrate the decreases in several mRNAs that were evident after 7days of treadmill exercise, suggesting an adaptation of motoneurons to acute stress. The mRNA changes following prolonged daily treadmill training are consistent with a reduction in inhibitory influences onto motoneurons, and a transition toward motoneurons that innervate slower contracting muscle fibers. These results demonstrate that the previously reported physiological changes in motoneurons with altered activity are accompanied by changes in gene expression., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)