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Nature Communications May 2021Oxygen release and irreversible cation migration are the main causes of voltage fade in Li-rich transition metal oxide cathode. But their correlation is not very clear...
Oxygen release and irreversible cation migration are the main causes of voltage fade in Li-rich transition metal oxide cathode. But their correlation is not very clear and voltage decay is still a bottleneck. Herein, we modulate the oxygen anionic redox chemistry by constructing LiZrO slabs into LiMnO domain in LiNiMnO, which induces the lattice strain, tunes the chemical environment for redox-active oxygen and enlarges the gap between metallic and anionic bands. This modulation expands the region in which lattice oxygen contributes capacity by oxidation to oxygen holes and relieves the charge transfer from anionic band to antibonding metal-oxygen band under a deep delithiation. This restrains cation reduction, metal-oxygen bond fracture, and the formation of localized O molecule, which fundamentally inhibits lattice oxygen escape and cation migration. The modulated cathode demonstrates a low voltage decay rate (0.45 millivolt per cycle) and a long cyclic stability.
PubMed: 34031408
DOI: 10.1038/s41467-021-23365-9 -
International Journal of Surgery... Nov 2016Diabetes mellitus may cause degeneration in the myelin and/or axonal structures of peripheral nerves. The aim of this study was to investigate the effects of diabetic...
BACKGROUND
Diabetes mellitus may cause degeneration in the myelin and/or axonal structures of peripheral nerves. The aim of this study was to investigate the effects of diabetic neuropathy on intraoperative neuromonitoring findings such as latency and amplitude values of the recurrent laryngeal nerves during thyroidectomy. To our knowledge this is the first study to report comparison of the electrophysiologic features of diabetic and non-diabetic patients.
MATERIALS AND METHODS
One-hundred-and-eleven consecutive patients who received neuromonitoring during thyroidectomy between 2013 and 2015 were included to study. The patients were divided into two groups according to the presence of diabetes mellitus. Pre-thyroidectomy and post thyroidectomy motor response latency and amplitude values of recurrent laryngeal nerves were compared between groups. Neuromonitoring findings, demographic data and postoperative complications were evaluated.
RESULTS
The diabetic group consisted of 29 (26.1%) patients while 82 (73.9%) patients were in non-diabetic group. The mean post-thyroidectomy amplitude values (millivolts-mV) of the recurrent laryngeal nerve were significantly lower in diabetic group (0.51 ± 0.26 mV vs. 0,70 ± 0,46 mV, p < 0.05), whereas the latency values were significantly higher (2.50 ± 0.86 ms vs. 1.85 ± 0.59 ms, p < 0.01) compared to non-diabetic group. Additionally, post-thyroidectomy latency values were significantly increased compared to the pre-thyroidectomy latency values (2.50 ± 0.86 ms vs. 2.02 ± 0.43 ms) in diabetic group patients (p < 0.05). Although postoperative complication rates were higher in diabetic group (10.3% vs. 5.9%), there were no statistical significance differences.
CONCLUSIONS
Prolonged latency and decreased amplitude values in recurrent laryngeal nerves of diabetic patients show that diabetic neuropathy of the recurrent laryngeal nerves develop similarly to the peripheral nerves. Increased post-thyroidectomy latency values reveal that the recurrent laryngeal nerve is more susceptible to surgical trauma in diabetic patients.
Topics: Adult; Aged; Aged, 80 and over; Diabetic Neuropathies; Electrophysiological Phenomena; Female; Humans; Male; Middle Aged; Monitoring, Intraoperative; Prospective Studies; Recurrent Laryngeal Nerve; Recurrent Laryngeal Nerve Injuries; Thyroid Diseases; Thyroidectomy; Vocal Cord Paralysis; Young Adult
PubMed: 27720825
DOI: 10.1016/j.ijsu.2016.10.001 -
Proceedings of the National Academy of... Feb 2021Voltage sensing with genetically expressed optical probes is highly desirable for large-scale recordings of neuronal activity and detection of localized voltage signals...
Voltage sensing with genetically expressed optical probes is highly desirable for large-scale recordings of neuronal activity and detection of localized voltage signals in single neurons. Most genetically encodable voltage indicators (GEVI) have drawbacks including slow response, low fluorescence, or excessive bleaching. Here we present a dark quencher GEVI approach (dqGEVI) using a Förster resonance energy transfer pair between a fluorophore glycosylphosphatidylinositol-enhanced green fluorescent protein (GPI-eGFP) on the outer surface of the neuronal membrane and an azo-benzene dye quencher (D3) that rapidly moves in the membrane driven by voltage. In contrast to previous probes, the sensor has a single photon bleaching time constant of ∼40 min, has a high temporal resolution and fidelity for detecting action potential firing at 100 Hz, resolves membrane de- and hyperpolarizations of a few millivolts, and has negligible effects on passive membrane properties or synaptic events. The dqGEVI approach should be a valuable tool for optical recordings of subcellular or population membrane potential changes in nerve cells.
Topics: Action Potentials; Animals; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Green Fluorescent Proteins; HEK293 Cells; Humans; Membrane Potentials; Memory; Neurons
PubMed: 33531364
DOI: 10.1073/pnas.2020235118 -
Science Advances Jul 2023Large-scale deployment of proton exchange membrane (PEM) water electrolyzers has to overcome a cost barrier resulting from the exclusive adoption of platinum group metal...
Large-scale deployment of proton exchange membrane (PEM) water electrolyzers has to overcome a cost barrier resulting from the exclusive adoption of platinum group metal (PGM) catalysts. Ideally, carbon-supported platinum used at cathode should be replaced with PGM-free catalysts, but they often undergo insufficient activity and stability subjecting to corrosive acidic conditions. Inspired by marcasite existed under acidic environments in nature, we report a sulfur doping-driven structural transformation from pyrite-type cobalt diselenide to pure marcasite counterpart. The resultant catalyst drives hydrogen evolution reaction with low overpotential of 67 millivolts at 10 milliamperes per square centimeter and exhibits no degradation after 1000 hours of testing in acid. Moreover, a PEM electrolyzer with this catalyst as cathode runs stably over 410 hours at 1 ampere per square centimeter and 60°C. The marked properties arise from sulfur doping that not only triggers formation of acid-resistant marcasite structure but also tailors electronic states (e.g., work function) for improved hydrogen diffusion and electrocatalysis.
PubMed: 37406120
DOI: 10.1126/sciadv.adh2885 -
ACS Central Science Dec 2021Extreme fast charging (XFC), with a recharging time of 15 min, is the key to the mainstream adoption of battery electric vehicles. Lithium metal, in the meantime, has...
Extreme fast charging (XFC), with a recharging time of 15 min, is the key to the mainstream adoption of battery electric vehicles. Lithium metal, in the meantime, has re-emerged as the ultimate anode because of its ultrahigh specific capacity and low electrochemical potential. However, the low lithium-ion concentration near the lithium electrode surface can result in uncontrolled dendrite growth aggravated by high plating current densities. Here, we reveal the beneficial effects of an adaptively enhanced internal electric field in a constant voltage charging mode in XFC via a molecular understanding of the electrolyte-electrode interfaces. With the same charging time and capacity, the increased electric field stress in dozens of millivolts, compared with that in a constant current mode, can facilitate Li migrating toward the negatively charged lithium electrode, mitigating Li depletion at the interface and thereby suppressing dendrites. In addition, more NO ions are involved in the solvation sheath that is constructed on the lithium electrode surface, leading to the nitride-enriched solid electrolyte interphase and thus favoring lower barriers for Li transport. On the basis of these merits, the Li||LiTiO battery runs steadily for 550 cycles with charging current peaks up to 27 mA cm, and the Li||S full cells exhibit extended life-spans charged within 12 min.
PubMed: 34963895
DOI: 10.1021/acscentsci.1c01014 -
IEEE Journal of Translational... 2019The electrocardiogram (ECG) plays an important role in the diagnosis of heart diseases. However, most patterns of diseases are based on old datasets and stepwise...
INTRODUCTION
The electrocardiogram (ECG) plays an important role in the diagnosis of heart diseases. However, most patterns of diseases are based on old datasets and stepwise algorithms that provide limited accuracy. Improving diagnostic accuracy of the ECG can be done by applying machine learning algorithms. This requires taking existing scanned or printed ECGs of old cohorts and transforming the ECG signal to the raw digital (time (milliseconds), voltage (millivolts)) form.
OBJECTIVES
We present a MATLAB-based tool and algorithm that converts a printed or scanned format of the ECG into a digitized ECG signal.
METHODS
30 ECG scanned curves are utilized in our study. An image processing method is first implemented for detecting the ECG regions of interest and extracting the ECG signals. It is followed by serial steps that digitize and validate the results.
RESULTS
The validation demonstrates very high correlation values of several standard ECG parameters: PR interval 0.984 +/-0.021 (p-value < 0.001), QRS interval 1+/- SD (p-value < 0.001), QT interval 0.981 +/- 0.023 p-value < 0.001, and RR interval 1 +/- 0.001 p-value < 0.001.
CONCLUSION
Digitized ECG signals from existing paper or scanned ECGs can be obtained with more than 95% of precision. This makes it possible to utilize historic ECG signals in machine learning algorithms to identify patterns of heart diseases and aid in the diagnostic and prognostic evaluation of patients with cardiovascular disease.
PubMed: 32166049
DOI: 10.1109/JTEHM.2019.2949784 -
Cell Reports Jan 2023The endoplasmic reticulum (ER) is a tortuous organelle that spans throughout a cell with a continuous membrane containing ion channels, pumps, and transporters. It is...
The endoplasmic reticulum (ER) is a tortuous organelle that spans throughout a cell with a continuous membrane containing ion channels, pumps, and transporters. It is unclear if stimuli that gate ER ion channels trigger substantial membrane potential fluctuations and if those fluctuations spread beyond their site of origin. Here, we visualize ER membrane potential dynamics in HEK cells and cultured rat hippocampal neurons by targeting a genetically encoded voltage indicator specifically to the ER membrane. We report the existence of clear cell-type- and stimulus-specific ER membrane potential fluctuations. In neurons, direct stimulation of ER ryanodine receptors generates depolarizations that scale linearly with stimulus strength and reach tens of millivolts. However, ER potentials do not spread beyond the site of receptor activation, exhibiting steep attenuation that is exacerbated by intracellular large conductance K channels. Thus, segments of ER can generate large depolarizations that are actively restricted from impacting nearby, contiguous membrane.
Topics: Animals; Rats; Calcium; Endoplasmic Reticulum; Hippocampus; Membrane Potentials; Neurons; Ryanodine Receptor Calcium Release Channel; Humans; Cell Line
PubMed: 36640310
DOI: 10.1016/j.celrep.2022.111943 -
Translational Vision Science &... Oct 2020The epithelium lining the ocular surface, which includes corneal and conjunctival epithelia, expresses the prosecretory chloride channel cystic fibrosis transmembrane...
PURPOSE
The epithelium lining the ocular surface, which includes corneal and conjunctival epithelia, expresses the prosecretory chloride channel cystic fibrosis transmembrane conductance regulator (CFTR) and the proabsorptive epithelial sodium channel (ENaC). Here, methodology was established to measure the millivolt (mV) potential differences at the ocular surface, called ocular surface potential difference (OSPD), in human subjects produced by ion transport.
METHODS
OSPD was measured in human subjects in which a fluid-filled measuring electrode contacted a fluid pool created by eversion of the lateral lower eyelid, with a reference electrode placed subcutaneously in the forearm. Through the use of a high-impedance voltmeter, OSPD was measured continuously over 10 to 15 minutes in response to a series of perfusate fluid exchanges.
RESULTS
Baseline OSPD (± SEM) in six normal human subjects was -21.3 ± 3.6 mV. OSPD depolarized by 1.7 ± 0.6 mV following the addition of the ENaC inhibitor amiloride, hyperpolarized by 6.8 ± 1.5 mV with a zero chloride solution, and further hyperpolarized by 15.9 ± 1.6 mV following CFTR activation by isoproterenol. The isoproterenol-induced hyperpolarization was absent in two cystic fibrosis subjects lacking functional CFTR. OSPD measurement produced minimal epithelial injury.
CONCLUSIONS
Our results establish the feasibility and safety of OSPD measurement in humans and demonstrate robust CFTR activity, albeit minimal ENaC activity, at the ocular surface. OSPD measurement may be broadly applicable to investigate fluid transport mechanisms and test drug candidates to treat ocular surface disorders.
TRANSLATIONAL RELEVANCE
To the best of our knowledge, this is the first measurement of the electrical potential generated by the ocular surface epithelium in human subjects, offering a new approach to study ocular surface function and health.
Topics: Amiloride; Cystic Fibrosis; Epithelial Sodium Channels; Eye; Humans; Ion Transport; Ocular Physiological Phenomena; Research Subjects
PubMed: 33117611
DOI: 10.1167/tvst.9.11.20 -
PLoS Computational Biology Feb 2021Axonal connections are widely regarded as faithful transmitters of neuronal signals with fixed delays. The reasoning behind this is that extracellular potentials caused...
Axonal connections are widely regarded as faithful transmitters of neuronal signals with fixed delays. The reasoning behind this is that extracellular potentials caused by spikes travelling along axons are too small to have an effect on other axons. Here we devise a computational framework that allows us to study the effect of extracellular potentials generated by spike volleys in axonal fibre bundles on axonal transmission delays. We demonstrate that, although the extracellular potentials generated by single spikes are of the order of microvolts, the collective extracellular potential generated by spike volleys can reach several millivolts. As a consequence, the resulting depolarisation of the axonal membranes increases the velocity of spikes, and therefore reduces axonal delays between brain areas. Driving a neural mass model with such spike volleys, we further demonstrate that only ephaptic coupling can explain the reduction of stimulus latencies with increased stimulus intensities, as observed in many psychological experiments.
Topics: Action Potentials; Animals; Axons; Biophysical Phenomena; Computational Biology; Computer Simulation; Extracellular Space; Humans; Models, Neurological; Nerve Fibers, Myelinated; Synaptic Transmission; White Matter
PubMed: 33556058
DOI: 10.1371/journal.pcbi.1007858 -
Journal of the American Chemical Society Feb 2020We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new...
We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new catalytic system is able to productively engage aryl chlorides with reduction potentials hundreds of millivolts beyond the potential of Na in productive radical coupling reactions. The aryl radicals produced via this strategy can be leveraged for both carbon-carbon and carbon-heteroatom bond-forming reactions. Through direct comparison, we illustrate the reactivity and selectivity advantages of this approach relative to electrolysis and photoredox catalysis.
Topics: Catalysis; Chlorides; Electrons; Oxidation-Reduction; Photochemical Processes
PubMed: 31951393
DOI: 10.1021/jacs.9b12328