Total Amount Of Charge Research Articles

Nanoparticle synthesis by high-density plasma sustained in liquid organosilicon precursors

A high-density plasma in a pin-to-pin configuration was sustained in liquid organosilicon precursors (hexamethyldisiloxane, tetraethyl orthosilicate, and tetramethylcyclotetrasiloxane) by the application of a high-voltage at a frequency of 1 kHz and a duty cycle of 30%. For all organosilicon precursors investigated, the current-voltage characteristics revealed a spark mode, with typical discharge duration of about 50 ns. Both the number of microdischarges and the total amount of charges per microdischarge increased with the amplitude of the applied voltage. The optical emission spectroscopy revealed strong emission from the C2 Swan system along with H I, Si I, and O I emission lines, indicating very high fragmentation levels of the organosilicon precursors upon discharge ignition. This was confirmed by Transmission Electron Microscopy and Energy-Dispersive X-ray spectroscopy indicating the formation of amorphous silicon oxycarbide nanoparticles. However, W I emission lines as well as W crystalline nanoparticles could also be seen; a feature ascribed to plasma-electrode interactions.

Ternary graphitic carbon nitride/red phosphorus/molybdenum disulfide heterostructure: An efficient and low cost photocatalyst for visible-light-driven H2 evolution from water

Graphitic carbon nitride (g-C3N4) is a low cost photocatalyst for visible-light-driven H2 evolution from water. However, it faces the issue of rapid charge recombination that significantly suppresses the photocatalytic activity. Herein, we report a novel strategy in which low cost red phosphorus (RP) photocatalyst and molybdenum disulfide (MoS2) cocatalyst are co-introduced to accelerate photogenerated charge separation and transfer of g-C3N4. The g-C3N4/RP/MoS2 ternary composites are prepared by a step-by-step deposition method on g-C3N4 surface. Under the irradiation of visible light, the peak H2 evolution rate of 257.9 μmol g−1 h−1 is obtained when the loaded amounts of RP and MoS2 are 3.18 and 0.52 wt% (g-C3N4/RP-3.18/MoS2-0.52), respectively. When compared with pure g-C3N4 and g-C3N4/RP-3.18 in terms of H2 evolution activity, g-C3N4/RP-3.18/MoS2-0.52 demonstrates approximately 859.7 and 4.4 times, respectively. The loading of RP inhibits charge recombination of g-C3N4 due to the matched energy band position, the photoexcitation of RP itself increases total charge amount, as well as the presence of MoS2 accelerates charge separation and transfer of g-C3N4/RP-3.18. These cooperative effects make g-C3N4/RP-3.18/MoS2-0.52 exhibit an enhanced activity. We believe that this study is meaningful for building novel efficient and low cost g-C3N4 based heterostructure photocatalysts.

Low-frequency dielectric response of charged oblate spheroidal particles immersed in an electrolyte.

We study the low-frequency polarization response of a surface-charged oblate spheroidal particle immersed in an electrolyte solution. Because the charged spheroid attracts counterions which form the electric double layer around the particle, using usual boundary conditions at the interface between the particle and electrolyte can be quite complicated and challenging. Hence, we generalize Fixman's boundary conditions, originally derived for spherical particles, to the case of the charged oblate spheroid. Given two different counterion distributions in the thin electric double-layer limit, we obtain analytic expressions for the polarization coefficients to the first nontrivial order in frequency. We find that the polarization response normal to the symmetry axis depends on the total amount of charge carried by the oblate spheroid while that parallel to the symmetry axis is suppressed when there is less charge on the edge of the spheroid. We further study the overall dielectric response for a dilute suspension of charged spheroids. We find that the dielectric enhancement at low frequency, which is driven by the presence of a large ζ potential (surface charge), is suppressed by high ion concentrations in the electrolyte and depends on the size of the suspended particles. In addition, spheroids with higher aspect ratios will also lead to a stronger dielectric enhancement due to the combination of the electric double layer and textural effects. The characteristic frequency associated with the dielectric enhancement scales inversely with the square of the particle size, the major radius of the spheroid, and it has a weak dependence on the shape of spheroids.

Simultaneous Determination of Electrochemical Impedance of Lithium-ion Rechargeable Batteries with Measurement of Charge-discharge Curves by Wavelet Transformation

A new analytical method was developed to determine the electrochemical impedance of lithium-ion rechargeable batteries (LIRB) at an arbitrary state of charge (SOC). Wavelet transformation (WT) is one of the waveform analysis methods, which allows the determination of frequency domain data as a function of time. The frequency domain data are obtained by convolution integral of a mother wavelet and original time domain data via the WT. A complex Morlet mother wavelet is used to obtain the complex number data in the frequency domain. The time series data of input current and output voltage signals are recorded by superimposing the double pulse current as an input signal to constant charge current for the charge of LIRB without stopping galvanostatic polarization. The double pulse current is composed of symmetrical positive and negative square waves. In this case, the SOC of LIRB is not affected by the input signal because the total amount of charge calculated from double pulse current is 0C. The impedance spectrum of LIRB at SOC 25% is determined in the frequency range from 0.1 to 100Hz during charge/discharge cycles without stopping galvanostatic polarization for the charge/discharge.

The effective stimulating pulse for restoration of blink function in unilateral facial nerve paralysis rabbits, verified by a simple FES system.

The trains of 200ms biphasic square pulses with the width of 9ms delivered at 50Hz were found to be the most suitable and effective mean as stimulation in FES system of restoring the blink function in unilateral facial nerve paralysis rabbit model. FES system is a reliable tool for these patients. Facial paralysis affects thousands of people every year. Many will have long term facial difficulties and the loss of the ability to blink the eye, which can lead to potential loss of the eye. Although many treatments exist, no one approach corrects all the deficits associated with the loss of orbicularis oculi function. FES is a means of providing movement in paralysed muscles to assist with practical activities and one possible way of restoring blink and other functions in these patients. Although some previous researches had investigated the effect of simple FES system on restoration of paralyzed facial muscles, there is still controversy about the appropriate details of the most effective stimulating pulses, such as the frequency, wave pattern and pulse width. Our aim is to find out the parameters of the most appropriate and effective stimulatin verify it by a simple FES system. 24 healthy adult male New Zealand white rabbits were accepted the surgery of right side facial nerve main trunk transaction under general anesthesia as the unilateral facial nerve paralysis models. The platinum tungsten alloy electrodes were implanted in orbicularis oculi muscle. The parameters of stimulus pulses were set to a 200ms biphasic pulse with different waveforms (square, sine and triangle), different frequencies (25, 50, 100Hz) and different widths from 1 to 9ms. Next, we set up a simple FES system to verify the previous results as the stimulus signal. We observed the movement of the both sides of eyelid when eye blink induced by different kinds of pulses. In all animals, the three kinds of waveforms pulse with frequency of 25Hz could not evoke the smooth blink movement. But the pulses with frequency of 50 and 100Hz can achieve this effect. The voltage threshold of the square pulse was lower than that of the sine pulse and triangle pulse. With the increase of pulse width from 1 to 9ms, the voltage threshold decreased gradually. The voltage threshold of the pulse with frequency of 100Hz was obviously lower than that of 50Hz. But the amount of total charge of the stimulation pulse of 100Hz was significantly more than that of 50Hz. In addition, when the FES system was turned on, the eye blink on the affected side with the stimulation pulses that were set by the previous step results was successfully aroused by the blink movement as a trigger on the contralateral.

Online-Analysis of Hits in the Belle-II Pixeldetector for Separation of Slow Pions from Background

The impending Upgrade of the Belle experiment is expected to increase the generated data set by a factor of 50. This means that for the planned pixel detector, which is the closest to the interaction point, the data rates are going to increase to up to 28 Gbit/s. Combined with data generated by the other detectors, this rate is too big to efficiently send out to offline processing. In order to reduce the data rates online data reduction schemes, in which background is detected and rejected, are going to be employed. In this paper, an approach for efficient online data reduction for the planned pixel detector of Belle-II is presented. Its central part is the NeuroBayes algorithm, which is based on multivariate analysis. It allows the identification of signal and background by analyzing clusters of hits in the pixel detector on FPGAs. The algorithm is leveraging the fact that hits of signal particles can have very different characteristics, compared to background, when passing through the pixel detector. The applicability and advantages in performance are shown through the D* decay. In Belle-II, these decays produce pions with such a small transversal momentum, that they barely escape the pixel detector itself. In a common approach like an extrapolation of tracks from outer detectors to RoIs, these pions are simply lost, since they do not reach all necessary layers of the detector. However, cluster analysis is able to identify and separate these pions from the background, thus keeping their data. For that characteristics of corresponding hits, like the total amount of charge deposited in the pixels, are used for separation. The capability for effective data reduction is underlined by a background reduction of at least 90% and signal efficiency of 95%, for slow pions. An implementation of the algorithm for usage on Virtex-6 FPGAs that are used at the pixel detector was performed. It is shown that the resulting implementation succeeds in replicating the efficiency of the algorithm, implemented in software while throughputs that suffice hard real-time constraints, set by the read-out system of Belle-II, are achieved and efficient use of the resources present on the FPGA is made.

Vertically Aligned Double-Walled Platinum Nanotubes Decorated with Inner Fibrils for Their Enhanced Electrocatalytic Properties

Vertically aligned double-walled platinum nanotubes (Pt DNTs) with inner fibrils have been synthesized by means of homogeneous coating of Pt onto a Pd thin-wall nanotube array template using electrochemical deposition, followed by chemical etching of the template. The resulting Pt DNTs with inner fibrils have advantageous morphological characteristics including high crystallinity of the coated Pt layers, high porosity of the inner nanotubes, the non-carbon-supported substrate, and a three-dimensional orientation, whereby the catalysts are directly and vertically connected with a conducting electrode. In addition, tube length can be controlled by tuning the total amount of charge injected during the electrochemical deposition. Electrochemical measurements have demonstrated that the resulting Pt DNTs have considerably greater electrochemically active surface area (ECSA) and higher electrocatalytic activity toward methanol oxidation and CO oxidation behavior compared to Pt single nanotube and Pt nanorod structures as well as other reported Pt-based catalysts under similar testing conditions. These results suggest that Pt DNTs are excellent nanocatalytic systems for low-temperature catalytic reactions and surface chemical processes.

Nucleation and Growth Behavior of Electrodeposited Lithium in Ionic Liquid

Metallic lithium is a promising anode candidate for rechargeable battery; however, the dendrite formation during charging should be suppressed to improve safety and cycleability. Many researches have been reported from the viewpoint of the control of the surface film on lithium metal1. Ionic liquids nowadays attract much attention from electrochemists, some of which have excellent stability at highly cathodic states (such as Li/Li+). Our group has focused on their unique features and utilized these ionic liquids as electrolyte with lithium metal anodes. In the present study, in order to determine the condition for the non-dendritic lithium deposition, we investigated the electrodeposition behavior during nucleation and growth state in ionic liquids based on overpotential and Li-ion diffusion. 10 wt.% of Li[Tf2N] was added to [C3mpip][Tf2N], [C4mpyr][Tf2N], and [N6,1,1,1][Tf2N] as the electrolytes. Lithium metal was electrodeposited on nickel substrates at current densities ranging from 5 to 200 μA cm-2 for total charge amount of 0.1 and 3 C cm-2. The morphology of electrodeposited lithium was observed by SEM. For the nucleation state, we focused on the case with charge amount of 0.1 C cm-2. The deposits were better distributed when the current density was increased (Figure 1). Additionally, the deposits were better distributed when the electrolyte viscosity was increased. In these conditions, an increased overpotential was confirmed. This is believed to lead to a wide distribution of nucleation sites due to decreased critical radii of the nuclei2. On the contrary, for the growth state, we focused on the case with the charge amount of 3 C cm-2. More deposits were more dendritic when the current density was increased (Figure 2) and also when the electrolyte viscosity was increased. This result can be rationalized by considering that the lithium ion concentration extremely decreased at the electrode surface, since Li-ion diffusion is slower than the decrement in the concentration of Li-ion at the electrode surface3. These tendency is common for noble-metal electrodeposition. The reason why these tendency is also observed for less noble metals such as lithium is considered to be that the ionic liquid used in this study is very stable at the highly cathodic state and therefore less effect of native film formation on the deposition. 1. D. Aurbach, E. Zinigrad, Y. Cohen, H. Teller , Solid State Ionics, 148, 405 (2002). 2. H. Sano, H. Sakaebe, H. Senoh, H. Matsumoto, J. Electrochem. Soc., Submitted. 3. H. Sano, H. Sakaebe, H. Senoh, H. Matsumoto, J. Electrochem. Soc., 161, A1236 (2014). Figure 1

A density functional study on interaction of first-row transition-metal dicarbides, C2X (X = Sc-Zn) with O2

We present our calculations based on density functional theory to explore the molecular adsorption of O2 on the first-row transition-metal dicarbides C2X (X=Sc-Zn). Degree of activation of O2 is observed to be less in C2XO2 (X=Sc-V) as compared with C2XO2 (X=Cr-Zn) except for X=Cu, and is marked by the amount of total charge on O2. Topological analysis shows that the interaction in the cases of C2XO2 (X=Sc-V) is prominent between X and O and mostly being intermediate type whereas in C2XO2 (X=Cr-Zn), both CO and XO bondings are observed with shared-kind and intermediate characteristics respectively.

Electrical characteristics of low‐Mg‐doped p‐AlGaN and p‐InGaN Schottky contacts

Electrical characteristics of low‐Mg‐doped p‐Al0.02–0.07Ga0.98–0.93N and p‐In0.02Ga0.98N Schottky contacts were investigated. A memory effect was revealed in the current–voltage (I–V) characteristics, which is found also in p‐GaN contacts and may be due to charge and discharge of holes to acceptor‐type interfacial defects. High‐temperature isothermal transient spectroscopy revealed that the defect densities in the Al0.02Ga0.98N and In0.02Ga0.98N samples were nearly half that in the GaN samples. A large reverse current with a memory effect was observed in the In0.02Ga0.98N contacts. It was suggested that current can flow via relatively shallow acceptor‐type interfacial defects. For the AlxGa1−xN with x = 0.04 and 0.07, I–V characteristics became leaky. The Schottky barrier heights estimated from the photoresponse experiment were higher than the values estimated from the bandgap by 0.19, 0.21, 0.20, and 0.21 eV for Al0.02Ga0.98N, Al0.04Ga0.96N, Al0.07Ga0.93N, and In0.02Ga0.98N samples, respectively. A probable explanation for such discrepancies may be due to the total charge amount of the interfacial states, which varied the electric field and the barrier lowering. It was found that even though the Al or In content was only as small as 2%, the electrical characteristics of the contacts changed significantly.

Duch ustawy o prawie autorskim i prawach pokrewnych – 20 lat ulatniania się

Autor wskazuje liczne przykłady oraz przyczyny erozji ustawy o prawie autorskim i prawach pokrewnych w minionym 20-leciu jej obowiązywania. Odwołując się do fundamentalnych zasad prawa autorskiego, wśród przyczyn ww. erozji wymienia: błędne nowelizacje, złe implementacje przepisów międzynarodowych, ułomną działalność doktryny i praktyki prawniczej, błędne orzecznictwo na wszystkich szczeblach sądownictwa, ale także ignorancję prawną twórców i użytkowników, przemożny wpływ na proces legislacyjny mediów i różnych grup interesów, pozaparlamentarne mieszanie się w stosowanie ustawy przez polityków. Autor wskazuje także na uhandlowienie ustawy i postrzeganie prawa autorskiego przez pryzmat potrzeb odbiorców i rynkowe motywacje użytkowników, spychanie na drugi plan praw osobistych autorów i unikatowości twórczości. Autor wskazuje także na konieczność kompleksowej regulacji sfery obrotu prawami autorskimi i pokrewnymi w jednym akcie i podaje przykład absurdu zastosowania przepisów wolnościowych konkurencji do zbiorowego zarządu prawami autorskimi. Erozję prawa autorskiego autor analizuje także na gruncie Uzasadnienia ustawy z 1994 r., będącego podstawą jej uchwalenia. W tym zakresie wskazuje na: odejście od prawidłowych regulacji droit de suite, utworu audiowizualnego i powiązanych z nim wynagrodzeń autorskich, przepisów regulujących zbiorowy zarząd, contra legem interpretacje domniemań prawnych (m.in. legitymacji organizacji zbiorowego zarządzania (OZZ), nabycia praw majątkowych do utworu audiowizualnego), naruszania bezwzględnie obowiązujących przepisów ustawy w zakresie zbywania autorskich praw majątkowych, błędne realizowanie przepisów o tzw. opłacie reprograficznej. Podając przykłady przepisów wprowadzanych w życie nowelizacjami ustawy, autor wskazuje na upadek techniki legislacyjnej i konieczność stosowania skomplikowanych metod interpretacyjnych, aby dotrzeć do sensu przepisu, np. art. 331 i następnych. Lekceważenie ustawy przejawia się także w niestosowaniu ustawowych terminów przez sądy polskie, np. art.80 pr.aut. Wieloma niekorzystnymi skutkami stosowania ustawy obarcza doktrynę prawną niepodejmującą interpretacji wielu pojęć i instytucji ustawowych np. „ogólnego obciążenia” z art. 11013 ust. 5 pkt 2; „inne środki publicznego udostępniania” z art. 70 ust. 21 pkt 3 pr.aut. Autor z niepokojem też wskazuje na projekty nowelizacji ustawy, będące ciągiem dalszym odchodzenia od jej ducha i zagrażające właściwemu zabezpieczaniu praw twórców, artystów wykonawców i innych podmiotów praw pokrewnych.

Numerical simulation of multi-combined effects of parameters on polymer charging characteristics due to electron irradiation

Charging characteristics of an insulator specimen due to non-penetrated electron irradiation have been attracting a great deal of attention in the fields such as scanning electron microscopy, electron probe analysis, and space irradiation. In this paper, we use a numerical simulation model based on Monte Carlo method for investigating the electron scattering. The elastic scattering is calculated with the Mott cross-section, and the inelastic scattering is simulated with Penn model and the fast secondary electron model according to the primary energy. The charge transport caused by the build-in electric field and charge density gradient is calculated with finite-difference time-domain method. Multi-combined effect of correlative parameters on charging characteristics is investigated by efficient multithreading parallel computing. During the irradiation, the landing energy of primary electrons decreases due to the negative surface potential, which makes the secondary electron yield increase. Variations of secondary electron current and sample current are presented to verify the validity of the simulation model by comparing with existing experimental results. Evolutions of leakage current, surface potential and internal space charge quantity are calculated under different conditions of incident electron current, primary energy and sample thickness. The results are presented in contour maps with different multi-parameter combinations, primary energy and sample mobility, primary energy and sample thickness, and primary energy and incident current. The balance state of charging will be determined by leakage current under conditions of a larger primary energy, sample mobility, incident current, or a less sample thickness, which is shown as the leakage current dominated mode. While in the cases of a lower primary energy, sample mobility, incident current, or a larger sample thickness, the balance state of charging is mainly dominated by secondary electron current, as the secondary electron current dominated mode. In other cases except the above two, the balance state will be determined by both leakage and secondary currents as the mixture mode. In the same mode, variations of charging characteristics with parameters are monotonic. When the change of a parameter makes the negative surface potential increase, the effect of this parameter on negative surface potential will be weakened, while the effects of other parameters on the negative potential will be enhanced. With the change of current dominated mode, the total charge quantity exhibits the local maximum with respect to the sample thickness, and the value of this maximum increases with primary energy. Moreover, the leakage current increases with incident current linearly. The presented results can be helpful for understanding regularities and mechanisms of charging due to electron irradiation, and estimating the charging intensity under different conditions of irradiation and sample material.

113. Short-term effect of different tdcs intensities on motor cortex excitability

To evaluate the on-line and short-term effects of different intensities of anodal and cathodal transcranial direct electric stimulation (tDCS) on the human motor cortex. 14 healthy subjects received anodal and cathodal tDCS in a random order on two separate sessions using a 35 cm 2 electrodes positioned over the left M1 and the contralateral supra-orbital region. During each session tDCS was randomly delivered at 0.5, 1, 1.5 and 2 mA with a wash out period of 25 min between intensities. The duration of stimulation was varied so that the total charge transferred was 4 mA.min for all intensities. Twelve motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) were recorded from the right first dorsal interosseous muscle before (baseline), at the beginning (on line 1), at the end (on line 2) and immediately after (post) each stimulation. Data were analysed with a repeated measures ANOVA using polarity (anodal/cathodal), intensities (0.5,1,1.5 and 2) and time (baseline, on line 1, on line2 and post) as within subject factors. Paired t tests were used for post hoc comparisons. the ANOVA showed only a significant effect of time on MEPs amplitude (F:8.7, p < 0.001). MEPs were significantly higher during (on line 1 p = 0.001, on line 2 p = 0.002) and immediately after either polarity of stimulation ( p = 0.02) compared with baseline. Short duration application of both anodal and cathodal tDCS facilitates corticospinal output during and immediately after application. The effects seem to be independent of the intensity and the duration of stimulation if the total amount of charge delivered is constant. Our findings could be, however, the result of an interaction between TMS and tDCS simultaneously delivered. Moreover we cannot exclude a sort of cumulative effect of several tDCS stimulations with a non effective wash-out period.

Effect of polyelectrolyte adsorption on lateral distribution and dynamics of anionic lipids: a Monte Carlo study of a coarse-grain model.

We employ Monte Carlo simulations to investigate the interaction between an adsorbing linear flexible cationic polyelectrolyte and a ternary mixed fluid membrane containing neutral (phosphatidylcholine, PC), monovalent (phosphatidylserine, PS), and multivalent (phosphatidylinositol, PIP2) anionic lipids. We systematically explore the influences of polyelectrolyte chain length, polyelectrolyte charge density, polyelectrolyte total charge amount, and salt solution ionic strength on the static and dynamic properties of different anionic lipid species. Our results show that the multivalent PIP2 lipids dominate the polyelectrolyte-membrane interaction and competitively inhibit polyelectrolyte-PS binding. When the total charge amount of the polyelectrolyte is less than that of the local oppositely charged PIP2 lipids, the polyelectrolyte can drag the bound multivalent lipids to diffuse on the membrane, but cannot interact with the PS lipids. Under this condition, the diffusion behaviors of the polyelectrolyte closely follow the prediction of the Rouse model, and the polyelectrolyte chain properties determine the adsorption amount, concentration gradients, and hierarchical mobility of the bound PIP2 lipids. However, when the total charge amount of the polyelectrolyte is larger than that of the local PIP2 lipids, the polyelectrolyte further binds the PS lipids around the polyelectrolyte-PIP2 complex to achieve local electrical neutrality. In this condition, parts of the polyelectrolyte desorb from the membrane and show faster mobility, and the bound PS presents much faster mobility than the segregated PIP2. This work provides an explanation for heterogeneity formation in different anionic lipids induced by polyelectrolyte adsorption.

P270: Short-term effect of different tDCS intensities on motor cortex excitability

To evaluate the on-line and short-term effects of different intensities of anodal and cathodal transcranial direct electric stimulation (tDCS) on the human motor cortex. 14 healthy subjects received anodal and cathodal tDCS in a random order on two separate sessions using a 35 cm 2 electrodes positioned over the left M1 and the contralateral supra-orbital region. During each session tDCS was randomly delivered at 0.5, 1, 1.5 and 2 mA with a wash out period of 25 min between intensities. The duration of stimulation was varied so that the total charge transferred was 4 mA.min for all intensities. Twelve motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) were recorded from the right first dorsal interosseous muscle before (baseline), at the beginning (on line 1), at the end (on line 2) and immediately after (post) each stimulation. Data were analysed with a repeated measures ANOVA using polarity (anodal/cathodal), intensities (0.5,1,1.5 and 2) and time (baseline, on line 1, on line2 and post) as within subject factors. Paired t tests were used for post hoc comparisons. the ANOVA showed only a significant effect of time on MEPs amplitude (F:8.7, p p = 0.001, on line 2 p = 0.002) and immediately after either polarity of stimulation ( p = 0.02) compared with baseline. Short duration application of both anodal and cathodal tDCS facilitates corticospinal output during and immediately after application. The effects seem to be independent of the intensity and the duration of stimulation if the total amount of charge delivered is constant. Our findings could be, however, the result of an interaction between TMS and tDCS simultaneously delivered. Moreover we cannot exclude a sort of cumulative effect of several tDCS stimulations with a non effective wash-out period.

Self-consistent field theory of adsorption of flexible polyelectrolytes onto an oppositely charged sphere

The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The power law scaling relationships between the boundary layer thickness and the surface charge density and the charge fraction of PE chains revealed in the study are in good agreement with the existing analytical result. The curvature effect on the degree of charge compensation of the total amount of charges on the adsorbed PE chains over the surface charges is examined, and a clear understanding of it based on the dependences of the degree of charge compensation on the surface charge density and the charge fraction of PE chains is established.

Numerical Study on the Charge Transport in a Space between Concentric Circular Cylinders

Electrification is one of the key factors to be considered in the design of power transformers utilizing dielectric liquid as a coolant. Compared with enormous quantity of experimental and analytical studies on electrification, numerical simulations are very few. This paper describes essential elements of numerical solution methods for the charge transport equations in a space between concentric cylinders. It is found that maintaining the conservation property of the convective terms in the governing equations is of the uttermost importance for numerical accuracy, in particular at low reaction rates. Parametric study on the charge transport on the axial plane of the annular space with a predetermined velocity shows that when the convection effect is weak the solutions tend to a one-dimensional nature, where diffusion is simply balanced by conduction. As the convection effect is increased the contours of charge distribution approach the fluid streamlines. Thus, when the conduction effect is weak, charge distribution tends to be uniform and the role of the convection effect becomes insignificant. At an increased conduction effect, on the other hand, the fluid motion transports the charge within the electric double layers toward the top and bottom boundaries leading to an increased amount of total charge in the domain.

The numerical study of the adsorption of flexible polyelectrolytes with the annealed charge distribution onto an oppositely charged sphere by the self-consistent field theory

The adsorption of flexible polyelectrolytes (PEs) with the annealed charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The numerical study reveals interesting scaling relationships between the boundary layer thickness and the surface charge density of the sphere as well as the degree of ionization of the monomers of the PE chains in the bulk solution. The dependences of the degree of charge compensation of the total amount of charges on adsorbed PE chains over the surface charges upon various system parameters are investigated. In particular, the effect of the radius of the charged sphere on the degree of charge compensation is carefully examined. The numerical study indicates that the curvature effect is closely related to the surface electric potential of the charged sphere. Moreover, in this study of the adsorption of PEs with the annealed charge distribution, a comparison with the corresponding case for PEs with the smeared charge distribution in terms of the boundary layer scaling law and the degree of charge compensation is also presented.

Thermite reaction of Al and α-Fe2O3 at the nanometer interface：ab initio molecular dynamics study

Based on the density function theory, thermite reaction between Al and α-Fe2O3 at temperature 2000 K in canonical ensemble is investigated by ab initio molecular dynamics. In the simulation, with the increasing of the time, the number of the Fe–O bond decreases, while the numbers of Al–O bonds and Fe–Fe bonds increase. At the same time, the total charge quantity of Fe ions decreases and the total charge quantity of Al ions increases as time increases. In the Al/Fe2O3 thermite reaction, the redox reaction is observed, Al atoms are oxidized and the Fe ions are reduced. And then the rupture of Fe–O bonds and the formation of Al–O bonds happen at the interface. Whole redox reaction is completed in about 3 ps.

Measurement of the surface charging of a plasma actuator using surface DBD

Abstract In order to quantify the surface charging of a plasma actuator using surface Dielectric Barrier Discharge, we propose a new equivalent circuit for this surface DBD and a new simple method allowing the measurement of the surface charging during the first half cycle and the discharging during the other half cycle. Using this method, we observed the temporal evolution of the total charge on the dielectric surface during an operation of a SDBD starting with positive cycle. We also observed the same phenomenon during an operation starting with a negative cycle. The comparison between these two observations suggests that the high electro-negativity of oxygen plays an important role in these discharges. Finally, we compare the total amount of charge transferred over a cycle under different experimental conditions and we find that the transfer is the lowest in oxygen and the highest in nitrogen.