Charge Movement Research Articles

Voltage sensor current, SR Ca2+ release, and Ca2+ channel current during trains of action potential-like depolarizations of skeletal muscle fibers.

In skeletal muscle, CaV 1.1 serves as the voltage sensor for both excitation-contraction coupling (ECC) and L-type Ca2+ channel activation. We have recently adapted the technique of action potential (AP) voltage clamp (APVC) to monitor the current generated by the movement of intramembrane voltage sensors (IQ ) during single imposed transverse tubular AP-like depolarization waveforms (IQAP ). We now extend this procedure to monitoring IQAP , and Ca2+ currents during trains of tubular AP-like waveforms in adult murine skeletal muscle fibers, and compare them with the trajectories of APs and AP-induced Ca2+ release measured in other fibers using field stimulation and optical probes. The AP waveform remains relatively constant during brief trains (<1 sec) for propagating APs in non-V clamped fibers. Trains of 10 AP-like depolarizations at 10 Hz (900 ms), 50 Hz (180 ms), or 100 Hz (90 ms) did not alter IQAP amplitude or kinetics, consistent with previous findings in isolated muscle fibers where negligible charge immobilization occurred during 100 ms step depolarizations. Using field stimulation, Ca2+ release did exhibit a considerable decline from pulse to pulse during the train, also consistent with previous findings, indicating that the decline of Ca2+ release during a short train of APs is not correlated to modification of charge movement. Ca2+ currents during single or 10 Hz trains of AP-like depolarizations were hardly detectable, were minimal during 50 Hz trains, and became more evident during 100 Hz trains in some fibers. Our results verify predictions on the behavior of the ECC machinery in response to AP-like depolarizations and provide a direct demonstration that Ca2+ currents elicited by single AP-like waveforms are negligible, but can become more prominent in some fibers during short high-frequency train stimulation that elicits maximal isometric force.

Biot-Savart Law for Determination of Speed of Particle Beyond the Speed of Light

This paper presents the modification of Biot-Savart law that thoroughly put to calculate magnetic field at any point in the space due to motion of charge in a complete circuit and further applies to determine velocity of particle faster than the speed of light. The modified Biot-Savart law provides complete mathematical result as given by ordinary Biot-Savart law, but most importantly, do not involve the need of derivative, integration of line element. In order to derive the relation ( among electric field ( magnetic field (( of electromagnetic wave, Biot-Savart law is given by formula B= , Where be angle between direction of velocity v of moving charge and position vector of given point where magnetic field has to be determined. This formula is applicable to address the question of how is it possible to achieve velocity of particle in excess of C and to open a discussion towards a new way of acquiring speed of particle beyond speed of light, namely C , Although, there is popular statement "nothing can move faster than speed of light". In this highly controversial statement, the specific purpose is not to comprises the merits of existing Biot-Savart law, but rather to introduce a concise and careful reasoned account of Biot-Savart law to propagate particle faster than speed of light.

Research on radiation field and driving based on super-low frequency mechanical antenna array

Mechanical antennas (MAs) directly use the mechanical motion of electric or magnetic charges to excite electromagnetic waves. The radiation distance of rotating magnetic dipole type mechanical antennas is related to the volume of the radiation source, so the volume of the radiation source is too large for long-distance communication. To solve the above problem, we first establish the magnetic field model and differential equations of motion of the antenna array. Then, we design the prototype of antenna array with operating frequency of 75-125Hz. Finally, we experimentally established the radiation intensity relationship between a single permanent magnet and an array of permanent magnets. The results indicate that our driving model reduces the tolerance of the signal by 47%. Through 2FSK communication experiments, this article verifies the feasibility of extending the communication distance in the form of an array, which provides an important reference for long-distance low-frequency communication.

Are Voltage Sensors Really Embedded in Muscarinic Receptors?

Unexpectedly, the affinity of the seven-transmembrane muscarinic acetylcholine receptors for their agonists is modulated by membrane depolarization. Recent reports attribute this characteristic to an embedded charge movement in the muscarinic receptor, acting as a voltage sensor. However, this explanation is inconsistent with the results of experiments measuring acetylcholine binding to muscarinic receptors in brain synaptoneurosomes. According to these results, the gating of the voltage-dependent sodium channel (VDSC) acts as the voltage sensor, generating activation of Go-proteins in response to membrane depolarization, and this modulates the affinity of muscarinic receptors for their cholinergic agonists.

Solid-state Synthesis, electronic Structure Studies, Solvent Interaction through Hydrogen Bonding, and Molecular Docking Studies of 2,2’-((1,2-Phenylenebis(Azaneylylidene))Bis (Methaneylylidene))Diphenol from o-Phenylenediamine and Salicylaldehyde

The compound was synthesized and characterized with Infrared, UV, and NMR studies. The present work is theoretically investigated using B3LYP/cc-pVDZ basis set. The LED has been performed using PBE0-D3/deft-TZVP basis set and DLPNO-CCSD(T). The DFT was used to define the structure and geometry of the compound. To identify the primary binding sites and weak interactions, the Multiwfn-3.8 was subjected to a topological analyses, including ELF, LOL, ALIE, and RDG. The UV-Visible spectrum was theoretically analyzed using the TD-SCF method. The B3LYP/cc-pVDZ was used to measure the HOMO-LUMO, MEP, NBO, and NLO. The NBO calculations investigate the intermolecular and intramolecular movement of charges, as well as the molecule stability. To determine whether the CS1 molecule has the potential to become a drug, a pharmacological investigation is performed using a Swiss-ADME. The docking study done against the 1NXU protein is performed using the Auto-dock.

Quantum vacuum fluctuations near a partially reflecting boundary: Brownian motion of a test charge as probe

The modified vacuum fluctuations of quantum fields in the presence of a perfectly reflecting mirror lead to divergent velocity dispersions of a charged test particle. Here, it is shown that when the mirror is modeled by a material medium described by a Drude-like susceptibility, these dispersions become regular, thus elucidating that the origin of the divergences that appear in the previous treatments is related to the assumption of idealized boundary conditions. As a consequence of implementing this more realistic description, the dispersion curves acquire an oscillatory behavior caused by the effective mass of the field modes inside the dispersive medium. Additionally, it is found that the effects over the particle are delayed when compared to the perfect mirror limit, a phenomenon attributed to the imperfect reflection of field modes on the mirror. Therefore, although idealized boundary conditions are simplifying hypotheses, their usage might hide or significantly modify relevant physical phenomena.

Combustion Chamber Development to Maximize the Performance of the Hydrogen Combustion Engine for the T1 Ultimate Category of the Dakar Rally Competition

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;As the world strives toward the common goal of carbon neutrality by 2050, motorsport cannot be allowed to stand alone as an exception. A gradual energy transition is clearly underway in the automotive industry but has already begun in motorsport as well. Among other initiatives, the Dakar Rally and the FIA have created the T1 ultimate category for prototypes powered by low-carbon fuels, including hydrogen. The Dakar is the pinnacle of off-road endurance rally competitions. It offers a great opportunity to ORECA Magny-Cours and FEV to expose their jointly developed internal combustion engine (ICE), fuelled with hydrogen only, to extreme conditions. In addition, the racing environment imposes a unique pace of development which can serve as a catalyst for spurring the H&lt;sub&gt;2&lt;/sub&gt;-ICE technology. Moreover, a hydrogen powered engine is an interesting fit for motorsports because it combines high power output, a relatively long driving range and driving pleasure with an excellent carbon footprint.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;This article outlines how ORECA Magny-Cours and FEV are currently converting a gasoline racing engine to hydrogen direct injection to meet the numerous challenges of the Dakar Rally. In several development steps, a combustion chamber was newly developed that is tailored to gaseous hydrogen combustion. A high level of charge motion and optimized mixture formation have ultimately been realized using FEV’s dedicated H&lt;sub&gt;2&lt;/sub&gt;-ICE simulation tool chain. Design changes resulting from the simulation results are incorporated into the engine. Further thermodynamic investigations on an engine test bench will be undertaken by ORECA Magny-Cours to maximize performance while ensuring knock free operation and best engine efficiency. Although there are still development hurdles to overcome, the combined ORECA/FEV experience will bring a viable carbon neutral powertrain solution to compete in the future Dakar Rally.&lt;/div&gt;&lt;/div&gt;

Numerical investigations on charge motion and combustion of natural gas-enhanced ammonia in marine pre-chamber lean-burn engine with dual-fuel combustion system

Ammonia, an efficient hydrogen carrier with the advantages of lower storage cost and higher stability comparing to hydrogen, is becoming a potential solution for carbon dioxide emission reduction from marine engine. In this paper, the CH4/NH3 mechanism applied to simulate the combustion process of elevated-pressure engine was experimentally verified. Then, simulations were conducted on a marine pre-chamber lean-burn engine to investigate the feasibility of dual-fuel combustion with natural gas and ammonia. The results show that the combustion of the rich mixture ignited by spark in the pre-chamber produces high-speed turbulent jet flames into the main chamber, which promotes the combustion of the lean gas mixture. Additionally, an anomalous pre-ignition pressure rise is observed at 50% natural gas addition. Finally, the performance evaluation of engine indicates that for the design of marine dual-fuel engine, the ammonia fraction range of 50%∼80% should be employed to achieve good engine thermal efficiency.

Analysis of depreciation charges as own source of investments of agrarian economic entities of Belarus

The article considers features of the movement of depreciation charges as an own source of investment regarding the specificity of the reproduction process in agriculture. It reveals and systematizes main advantages of depreciation charges as a source of formation of investments taking into account their specificity relative to other sources. Calculations have been made to determine the reserve increase in the amount of depreciation charges in agricultural organizations of Belarus when applying accelera- ted depreciation.

Ion-driven destabilization of a toroidal electron plasma—A 3D3V PIC simulation

Ion-driven destabilization of a toroidal electron plasma in a small aspect ratio axisymmetric toroidal device is reported for A r + ions of different initial density values using a high fidelity 3D3V PIC solver. Stability of a recently discovered quiescent quasi-steady state (QQS) of a toroidal electron plasma obtained from “seed” solution as a result of entropy extremization at zero inertia is addressed in the presence of a small ion population. An initial value (f0) of the ion fraction (f = n i / n e) and the corresponding secondary electrons are “preloaded” into the system after the electron plasma attains a QQS state. This procedure is regarded as a proxy to the conventional production of ions in the experimental devices via impact ionization. The resulting electron plasma exhibits destabilized “center of charge motion” (m = 1) along with higher order harmonics with dominant power in the second harmonic. Gradual loss of ions (and also electrons) is observed resulting in time varying f values. Beyond a certain value of f0 ( ≥ 0.005), growth in wall probe current is observed, which saturates at later simulation time due to the loss of particles. Trajectories of ion particles indicate ion trapping in the potential well, which is qualitatively similar to the ion resonance instability in pure electron plasmas.

Tuning the interface adhesion of Ag/ZnO composites by metallic dopants: A DFT study

Ag/ZnO composites have been widely applied in various fields, whilst their poor interface adhesion limits the integrative performance of these composites. Recently, metallic doping has been considered as a versatile strategy to tune the interface adhesion of metal/ceramic interfaces. However, the relationship between interface adhesion and electronic structure induced by doping at the Ag/ZnO interface needs to be further clarified. In this work, we investigated the work of separation (Wsep, value to estimate of interface adhesion), effective bond order and charge movement of Ag/ZnO interfaces with various dopants under four typical configurations by DFT calculations. It demonstrated that the dopants with lower electronegativity could enhance the interface adhesion of Ag/ZnO due to the interfacial Ag-O bonds with higher covalency level and shorter bond-lengths induced by larger charge transfer (Δq) and a higher degree of the p-d hybridization between the interfacial Ag and O atoms, while the dopants with higher electronegativity could weaken the interface adhesion. Moreover, we found that three atomic parameters (bond-lengths, <AEBO>-the average of effective bond order, Δq) were able to quantitatively rationalize the Wsep. This work advances the understanding of doping effect on the interface adhesion of Ag/ZnO interfaces that can be extended to other metal/ceramic interfaces.

Timing resolution in double-sided silicon photon-counting computed tomography detectors.

Our purpose is to investigate the timing resolution in edge-on silicon strip detectors for photon-counting spectral computed tomography. Today, the timing for detection of individual x-rays is not measured, but in the future, timing information can be valuable to accurately reconstruct the interactions caused by each primary photon. We assume a pixel size of and a detector with double-sided readout with low-noise CMOS electronics for pulse processing for every pixel on each side. Due to the electrode width in relation to the wafer thickness, the induced current signals are largely dominated by charge movement close to the collecting electrodes. By employing double-sided readout electrodes, at least two signals are generated for each interaction. By comparing the timing of the induced current pulses, the time of the interaction can be determined and used to identify interactions that originate from the same incident photon. Using a Monte Carlo simulation of photon interactions in combination with a charge transport model, we evaluate the performance of estimating the time of the interaction for different interaction positions. Our simulations indicate that a time resolution of 1ns can be achieved with a noise level of 0.5keV. In a detector with no electronic noise, the corresponding time resolution is . Time resolution in edge-on silicon strip CT detectors can potentially be used to increase the signal-to-noise-ratio and energy resolution by helping in identifying Compton scattered photons in the detector.

Megahertz Sampling of Prestin (SLC26a5) Voltage-Sensor Charge Movements in Outer Hair Cell Membranes Reveals Ultrasonic Activity that May Support Electromotility and Cochlear Amplification.

Charged moieties in the outer hair cell (OHC) membrane motor protein, prestin, are driven by transmembrane voltage to power OHC electromotility (eM) and cochlear amplification (CA), an enhancement of mammalian hearing. Consequently, the speed of prestin's conformational switching constrains its dynamic influence on micromechanics of the cell and the organ of Corti. Corresponding voltage-sensor charge movements in prestin, classically assessed as a voltage-dependent, nonlinear membrane capacitance (NLC), have been used to gauge its frequency response, but have been validly measured only out to 30 kHz. Thus, controversy exists concerning the effectiveness of eM in supporting CA at ultrasonic frequencies where some mammals can hear. Using megahertz sampling of guinea pig (either sex) prestin charge movements, we extend interrogations of NLC into the ultrasonic range (up to 120 kHz) and find an order of magnitude larger response at 80 kHz than previously predicted, indicating that an influence of eM at ultrasonic frequencies is likely, in line with recent in vivo results (Levic et al., 2022). Given wider bandwidth interrogations, we also validate kinetic model predictions of prestin by directly observing its characteristic cut-off frequency under voltage-clamp as the intersection frequency (Fis), near 19 kHz, of the real and imaginary components of complex NLC (cNLC). The frequency response of prestin displacement current noise determined from either the Nyquist relation or stationary measures aligns with this cut-off. We conclude that voltage stimulation accurately assesses the spectral limits of prestin activity, and that voltage-dependent conformational switching is physiologically significant in the ultrasonic range.SIGNIFICANCE STATEMENT The motor protein prestin powers outer hair cell (OHC) electromotility (eM) and cochlear amplification (CA), an enhancement of high-frequency mammalian hearing. The ability of prestin to work at very high frequencies depends on its membrane voltage-driven conformation switching. Using megahertz sampling, we extend measures of prestin charge movement into the ultrasonic range and find response magnitude at 80 kHz an order of magnitude larger than previously estimated, despite confirmation of previous low pass characteristic frequency cut-offs. The frequency response of prestin noise garnered by the admittance-based Nyquist relation or stationary noise measures confirms this characteristic cut-off frequency. Our data indicate that voltage perturbation provides accurate assessment of prestin performance indicating that it can support cochlear amplification into a higher frequency range than previously thought.

Distribution and evolution of surface charges in nanosecond pulsed dielectric barrier discharge under the quiescent air and airflow

The surface charges in nanosecond pulsed dielectric barrier discharge under quiescent air and airflow are detected based on the Pockels effect of electro-optical crystals. In quiescent air, it is found that the surface charge spot propagates and moves in a certain direction due to the combination of the transverse electric field and the thermal accumulation during dozens of consecutive discharge cycles. However, the position of the surface charge spot remains fixed throughout a single discharge cycle (0.83 ms). At the same time, the noticeable decay of surface charges emerges in the above time scales. Furthermore, when the airflow is introduced into the discharge gap, the propagation and movement of surface charges are accelerated. With the increase of airflow velocity, the discharge transforms from a filamentary mode to a diffuse mode, and the distribution of surface charges varies from discrete to uniform. The transition point of the discharge state and charge distribution corresponds to the airflow velocity of 10 m s−1. The airflow accelerates the decay of surface charges, resulting in the shrink and dispersion of surface charges, which is considered to be the fundamental reason for the airflow’s potential to improve discharge uniformity. The inherent mechanism for achieving uniform discharge is revealed in this study.

A coupled quantum-molecular mechanics approach for performance analysis of defective Silicon based photovoltaic solar cells

Although, molecular mechanics (MM) based approaches are capable of simulating the dynamic charge motion of atoms over time scales up to femto-seconds, the accuracy is an issue. As a result, quantum-mechanics (QM) based approaches are a choice to predict accurate dynamic motion of atomic charges. However, computational cost of QM simulations is significantly higher than that of MM simulations. In this study, a computationally efficient coupled QM/MM model is developed by combining the QM and MM approaches, enabling simulation of larger domains with accurate estimates. The proposed methodology is implemented with the help of QMMM package available in large-scale atomic/molecular massively parallel simulator (LAMMPS), to investigate the dynamic charge motion in the presence of cracks in Silicon. A Silicon domain of dimensions 48.87 Å × 48.87 Å × 5.43 Å is considered in the simulations. Furthermore, a small domain around the crack tip, with dimensions 4 Å × 4 Å is identified for carrying out QM analysis and denoted as embedded region (ER). Simulations are performed considering four different cases: (i) pristine Silicon, (ii) Silicon with an initial edge crack, (iii) pristine Silicon with Graphene deposition, and (iv) Graphene deposited Silicon containing an initial edge crack. In the coupled model, first, for the given load step, considering the minimum energy criteria molecular dynamics simulations are performed over the entire domain. This is followed by QM simulations over an identified ER based on first principle studies using the plane wave density functional theory. The latest atom positions from the QM simulations are updated in the MM domain before proceeding to the next load step. The electrical performance of Silicon solar cells is studied by estimating the effective Bader charge and total electric power. The effective Bader charge for atoms in QM domain is observed to be significantly higher indicating charge accumulation around the crack tip. This is further evidenced through the total electric power estimations, where pristine Silicon with Graphene deposition is observed to possess the highest power followed by cases iv, ii and i.

Tuning the temperature dependence of Shaker potassium channel with mutations at S4-S5 linker.

We investigated the effects of temperature on mutations that uncouple the voltage sensor (VSD) from the pore (PD) in the Shaker-IR potassium channel using temperature step (Tstep). We utilized a setup that achieves fast temperature changes (millisecond) and allows the recording of the cell membrane temperature with sub-millisecond resolution (https://doi.org/10.1101/2022.07.11.499616). We used the mutants V369I, I372L, S376T (ILT), in the N-terminus of the S4-S5, that produces a split in the components of the gating charge movement, and I384N, near the S4-S5 C-terminus, that uncouples the VSD charge movement from the PD. From a bath temperature of 17 ºC, we used a Tstep of around ∼9 ºC with rising phase of 1.5 ms. In ILT, applying a Tstep, after the gating currents have subsided, promotes a right shift in the first component of gating charge and a left shift of the second component (the last concerted step associated with PD opening). Consistently, Tstep applied after the onset of a depolarizing voltage pulse produces a ∼5 mV left shift in the conductance-voltage curve (G-V). The entropy, calculated from G-V, changes from 24 for WT to −42 J/K for ILT. In I384N, applying a Tstep reduces the ionic current indicating the closure of the pore. We hypothesize that the temperature dependence of the ILT G-V arises from the changes in the last step of the charge movement. On the other hand, since the VSD and PD are loosely coupled in I384N, the increase in temperature is likely to further decrease the VSD-PD coupling, thus decreasing the measured conductance. (Support: NIH: GM030376, Fondecyt: 1190203)

Structural basis for severe pain caused by mutations in voltage gated sodium channels Nav1.7.

Gain-of-function mutations in voltage-gated sodium channel NaV1.7 cause severe inherited pain syndromes, including Inherited Erythromelalgia (IEM). We introduced IEM mutations into the bacterial sodium channel NaVAb and confirmed the negative shift in the voltage dependence of activation that recapitulates the gain-of-function of these mutants. Unexpectedly, our structures of NaVAb IEM mutations reveal two complementary pathogenic mechanisms at the atomic level. Mutations in the voltage sensor domain facilitate the outward movement of S4 gating charges by widening the pathway for gating charge movement and modifying hydrophobic interactions with surrounding amino acid side chains or membrane phospholipids. In contrast, IEM mutations in the S4-S5 linker stabilize the activated state by forming new hydrogen bonds with residues in the pore domain, including a conserved asparagine near the activation gate. These results provide key structural insights into the dual mechanisms by which these IEM mutations cause hyperexcitability and severe pain in this debilitating disease.

Defect self-propulsion in active nematic films with spatially varying activity.

We study the dynamics of topological defects in active nematic films with spatially varying activity and consider two set-ups: (i) a constant activity gradient and (ii) a sharp jump in activity. A constant gradient of extensile (contractile) activity endows the comet-like +1/2 defect with a finite vorticity that drives the defect to align its nose in the direction of decreasing (increasing) gradient. A constant gradient does not, however, affect the known self-propulsion of the +1/2 defect and has no effect on the -1/2 that remains a non-motile particle. A sharp jump in activity acts like a wall that traps the defects, affecting the translational and rotational motion of both charges. The +1/2 defect slows down as it approaches the interface and the net vorticity tends to reorient the defect polarization so that it becomes perpendicular to the interface. The -1/2 defect acquires a self-propulsion towards the activity interface, while the vorticity-induced active torque tends to align the defect to a preferred orientation. This effective attraction of the negative defects to the wall is consistent with the observation of an accumulation of negative topological charge at both active/passive interfaces and physical boundaries.

Folding stability at the anion-binding site distinguishes prestin from other SLC26 transporters as revealed by HDX-MS.

The outer hair cell protein prestin (SLC26A5) responds to transmembrane voltage fluctuations by changing its cross-sectional area. This process, known as electromotility, is fundamental to mammalian cochlear amplification. Though prestin belongs to the SLC26 family of membrane transporters, it is the only member capable of displaying electromotility. Prestin's associated charge movement is driven by the helical dipole between TM3 and TM10, the charged residue R399, and the bound anion, but the relative roles remain to be determined. Here, we investigated these issues by interrogating the dynamics of prestin and SLC26A9, a typical SLC26 anion transporter, using hydrogen-deuterium exchange mass spectrometry (HDX-MS). We show that the folding stability of the anion-binding site of prestin is at least 2.8 kcal/mol weaker than SLC26A9 while the remaining regions have similar stability. Anion binding to prestin reversibly folds the binding site by joining the TM3 and TM10 helices, ensuing allosteric modulation of the TMD dynamics. In contrast, anion binding minimally affects the stability of SLC26A9, including the TM3-TM10 dielectric gap. We find helix fraying at the binding site but cooperative unfolding for multiple peripheral helices, with potential structural and functional relevance. Our HDX-MS data not only validate recent cryo-EM structures, but also highlight the unique role of the bound anion driving the folding of prestin's anion-binding site. This phenomenon may have implications to prestin's voltage-sensing mechanism in the outer hair cells.

Structural and Energy Storage Properties of Hydrothermally Synthesized Y2MnCoO6 Double Perovskite

Herein, structural, morphological, and energy‐storage properties of Y2MnCoO6 double perovskite synthesized by hydrothermal process are reported. The electrochemical investigation of Y2MnCoO6 is a novel aspect of the work, and this composition is being synthesized for the first time employing the hydrothermal technique. The powder X‐ray diffraction analysis shows formation of cubic crystal phase with Ia(206) symmetry and lattice parameters as a = b = c = 10.60 Å. It is indicated in the microstructure study that the morphology of the sample material is almost homogenous in the form of microspheres. The microsphere shape allows superior charge movement at the nanoscale, enabling more area available for electrochemical reactions to take place. The high‐resolution transmission electron microscopy (HRTEM) reveals the grain size in the range of 50–100 nm. The X‐ray photoelectron spectroscopy reveals the occurrence of Y3+, Mn3+, and Co2+/3+, ions on the surface of Y2MnCoO6. The energy‐storage behavior of nanostructured Y2MnCoO6 electrodes studied via cyclic voltammetry and chronopotentiometry displays the redox nature of the Y2MnCoO6. The calculated value of specific capacitance is found to be ≈148.0 Fg−1 at current density of 0.5 Ag−1; with ≈85% specific capacitance retention, after 10 000 cycles.