Effective Charge Research Articles

Effect of NaClO4 Dopant on Chemical Bond and Electrochemical Characteristic of Benzoyl Kappa‐Carrageenan Gel Biopolymer Electrolyte

AbstractGel biopolymer electrolytes based on benzoyl kappa‐carrageenan (Bz‐κcar) as polymer host and sodium perchlorate (NaClO4) as dopants are successfully produced. The concentration of NaClO4 is varied from 0.5 to 3.0 wt% to investigate its effects on the chemical bonds and electrochemical characteristic of electrolytes. Characterizations are performed by Fourier‐transform infrared spectroscopy (FTIR) and electrochemical impedance analysis (EIS), linear sweep voltammetry, and transference number measurement. Significant changes in the FTIR spectra are detected, which indicate chemical interactions between Bz‐ƙcar and NaClO4. The ionic conductivity (σ) of the gel electrolytes increases with higher concentrations of NaClO4, suggesting that NaClO4 is an effective charge carrier in the system. The highest σ of the gel electrolyte attained at ambient temperature is 1.29 × 10−3 S cm−1. The temperature dependence of conductivity is Arrhenian in the studied temperature range and achieves an elevated σ of 7.90 × 10−3 S cm−1 at 373 K with small values in the activation energy (Ea) observed in all the prepared electrolytes. Electrochemical stability of 1.50 V achieves the highest conducting electrolyte by means of linear sweep voltammetry. Transference number measurement confirms that ions predominate the conduction of electrolyte with 0.85 ion transference number.

The effect of transport apertures on relay-imaged, sharp-edged laser profiles in photoinjectors and the impact on electron beam properties

In a photoinjector electron source, the initial transverse electron bunch properties are determined by the spatial properties of the laser beam on the photocathode. Spatial shaping of the laser is commonly achieved by relay imaging an illuminated circular mask onto the photocathode. However, the Gibbs phenomenon shows that recreating the sharp edge and discontinuity of the cut profile at the mask on the cathode is not possible with an optical relay of finite aperture. Furthermore, the practical injection of the laser into the photoinjector results in the beam passing through small or asymmetrically positioned apertures. This work uses wavefront propagation to show how the transport apertures cause ripple structures to appear in the transverse laser profile even when effectively the full laser power is transmitted. The impact of these structures on the propagated electron bunch has also been studied with electron bunches of high and low charge density. With high charge density, the ripples in the initial charge distribution rapidly wash-out through space charge effects. However, for bunches with low charge density, the ripples can persist through the bunch transport. Although statistical properties of the electron bunch in the cases studied are not greatly affected, there is the potential for the distorted electron bunch to negatively impact machine performance. Therefore, these effects should be considered in the design phase of accelerators using photoinjectors.

Coexistance of the Negative Photoconductance Effect and Analogue Switching Memory in the CuPc Organic Memristor for Neuromorphic Vision Computing.

A bioinspired in-sensing computing paradigm using emerging photoelectronic memristors pursues multifunctionality with low power consumption and high efficiency for processing large amounts of sensing information. An organic semiconductor memristor strategy based on the CuPc functional layer integrates a negative photoconductance (NPC) effect and an analogue switching memory (ASM) effect in the same pixel. The NPC effect, present in the pure capacitance state at low bias voltage, provides high-performance short/long-term synaptic plasticity modulable by light pulse parameters. The interface charge effect along with defeat site trapping and detrapping is responsible for the pure capacitance effect and the NPC effect, with electron tunneling and electric-field-driven band dynamics responsible for ASM. This work reveals an organic memristor approach for hardware implementation of a neuromorphic vision computing system, emulating retinal bipolar cells via light-dominated NPC and electrically induced ASM with stable, tunable conductance states.

Computational and experimental investigations on structural, electronic and optical properties of scheelite compounds

Oxide of tungstate has consistently been pursued for use in optoelectronic applications. This study details the synthesis of AWO4 (A = Ba, Sr and Ca) using a high-temperature solid-state method. Additionally, theoretical calculations highlight its electronic structure, density of states, photoelectric properties, and vibrational modes. The x-ray diffraction of AWO4 (A = Ba, Sr and Ca) was meticulously introduced by the utilization of Rietveld for refinement. The refined lattice parameters substantially verified AWO4 (A = Ba, Sr and Ca) as a tetragonal system of scheelite with the spatial group of I41/a, and demonstrated significant alteration with the discrepancy in the radius of alkaline earth metal (A-site) ions. The electronic configuration and optical attributes of AWO4 (A = Ba, Sr and Ca) possessing scheelite-like structure were explored using density functional theory (DFT) based computational techniques. The theoretical blueprint was derived by optimizing the structure based on defects. The postulated optical bandgap energy confirms the occurrence of direct electronic transitions at Brillouin region G points. Calculations suggested the direct band gaps of BaWO4, SrWO4, and CaWO4 at 4.385, 3.123 and 3.813 eV. This was attributed to the energy levels produced by O and A-site atoms in the valence band, and W and O atoms in the conduction band. An examination of the polarization effect and uneven electronic charge distribution between [CaO8]6− and [WO4]2− clusters brought about by structural defects in AWO4 (A = Ba, Sr and Ca) was performed. Moreover, advanced investigations have been conducted on the elastic constants and mechanical durability of AWO4 (A = Ba, Sr and Ca). This research extensively calculated the elastic moduli of various matrices utilizing DFT. The critical Pugh’s ratio value was found to be >1.75, it indicated that AWO4 (A = Ba, Sr and Ca) has significant potential as a resilient material.

Derivation of Morse potential

The Morse potential is widely used in chemistry, physics, and material science to describe interatomic interactions. We show that the Morse potential can be derived from a simple screened charge model accounting for the shielding of the nuclear charge by electron density. In this model, the parameter governing the width of the potential is related to the average shielding strength and the exponents of the atomic orbitals used in electronic structure calculations. The parameter representing the bond dissociation energy of a diatomic molecule is derived by combining the quantum mechanical covalent and classical electrostatic interactions. Moreover, the revealed connection between the parameters of the Morse potential and Pauling’s bond order and electronegativity provides insight into the relation between the classical and quantum mechanical descriptions of chemical bonds. This derivation of the Morse potential from the atomic quantities is expected to contribute to the development of the new basis sets incorporating Slater-type orbitals for electronic structure calculations and the transferable reactive force fields for molecular dynamics simulations. Furthermore, this interpretation of the Morse potential helps to understand the relationships between widely used chemical concepts, including effective atomic charge, bond dissociation energy, electronegativity, and bond order.

Observation of Positive Trap Charge by Electron Holography in PMOS Device

Abstract It has been hypothesized that trap charge plays an important role in PMOS (positive-channel metal oxide semiconductor) device reliability. By using electron holography, trap charge in a spacer oxide was observed to cause an inversion of junction in an un-stressed PMOS device prepared using a Ga+ focused ion beam (FIB). Through 400°C annealing for 10 min in vacuum, trap charge in the spacer oxide dispersed and the junction recovered. Technology computer-aided design (TCAD) simulation was used to confirm the positive trap charge effect on the junction. Furthermore, the simulation showed that a low concentration of positive trap charge at the Si/SiO2 interface under the spacer led to a higher tunneling current due to an abrupt junction near the Si surface through a very localized junction inversion.

Synergist enhancement of effective desilication of graphite ore by rotary triboelectric separation and surface modification

Desilication of graphite ores helps to ensure their high-value applications. Surface modification and triboelectric separation methods were used to improve the desilication of graphite ore. Effects of friction media and chemicals on the charge properties of graphite and quartz were investigated by charge-to-mass ratio tests and the adsorption mechanism was analyzed. Furthermore, effects of electrode voltage and rotational speed on the desilication of graphite ore were investigated. The results showed that polyvinyl chloride was the best friction medium for graphite and quartz, and the charging effect of kerosene-modified graphite and quartz was better than that of ethanol. Kerosene modification made graphite more positively charged and quartz more negatively charged, enlarging the charge-to-mass ratio gap. Desilication efficiencies of 0.25–0.5 mm, 0.125–0.25 mm, and 0.074–0.125 mm graphite ores after kerosene modification were 42.27% (20.20% increase), 48.92% (17.18% increase), and 57.26% (19.92% increase), respectively. Our study provides guidance for the purification of graphite.

Self-Assembling Peptide-Based High-Relaxivity Targeted MRI Contrast Agents.

Concentration-dependent increases in relaxivity (r1) were found to be induced by self-assembly when Fmoc is adjacent to tryptophan in peptide-based MRI contrast agents featuring Gd-DOTA. A series of di- and tri-peptides were synthesized to test the effect of ionic strength, N-terminal substituent, peptide length, net charge, and relative location of Fmoc and tryptophan on r1 and critical aggregation concentration (CAC) at 1.0 Tesla. Compared to nominal r1 values of 3.5-7.4 mM-1 s-1 per Gd(III), r1 values increased dramatically to 13.2-16.9 mM-1 s-1 per Gd(III) upon self-assembly, with CACs between 0.22 and 2.59 mM when tested in H2O or PBS. When tested in fetal bovine serum (FBS), the compounds maintained high r1 values of 11.2-13.0 mM-1 s-1, but had dramatically lower CAC values below 25 μM. These findings guided the synthesis of two targeted, high-relaxivity MRI contrast agents that contained PSMA-binding ligand, DCL. Their r1 values in H2O or PBS increased from 5.9-7.4 mM-1 s-1 to 13.5-14.8 mM-1 s-1 with CAC values of 1.65-2.70 mM. In FBS, their r1 values were found to be 11.2-11.9 mM-1 s-1, with CAC values below 25 μM. By the conjugation of targeting agents in the last step of synthesis, a broadly applicable route to targeted, high-relaxivity MRI contrast agents is offered.

Doping-control of excitons and magnetism in few-layer CrSBr

Magnetism in two-dimensional materials reveals phenomena distinct from bulk magnetic crystals, with sensitivity to charge doping and electric fields in monolayer and bilayer van der Waals magnet CrI3. Within the class of layered magnets, semiconducting CrSBr stands out by featuring stability under ambient conditions, correlating excitons with magnetic order and thus providing strong magnon-exciton coupling, and exhibiting peculiar magneto-optics of exciton-polaritons. Here, we demonstrate that both exciton and magnetic transitions in bilayer and trilayer CrSBr are sensitive to voltage-controlled field-effect charging, exhibiting bound exciton-charge complexes and doping-induced metamagnetic transitions. Moreover, we demonstrate how these unique properties enable optical probes of local magnetic order, visualizing magnetic domains of competing phases across metamagnetic transitions induced by magnetic field or electrostatic doping. Our work identifies few-layer CrSBr as a rich platform for exploring collaborative effects of charge, optical excitations, and magnetism.

IDSimF: An Open-Source Framework for the Simulation of Molecular Ion Dynamics in Mass Spectrometry and Ion Mobility Spectrometry.

The development of mass spectrometric and ion mobility devices heavily depends on a comprehensive understanding of the behavior of ions within such systems. Therefore, numerical modeling of ion paths helps to optimize and verify existing devices, and contributes to the development of innovative ion optical systems and multipole geometries. This Article introduces IDSimF (Ion Dynamics Simulation Framework), an open-source simulation tool tailored to the nonrelativistic dynamics of molecular ions in mass and ion mobility spectrometry applications. Addressing limitations in existing software packages, as for example SIMION, OpenFOAM, and COMSOL, IDSimF offers a specialized platform for simulating ion trajectories in electric fields. IDSimF efficiently accounts for space charge effects and considers various ion-neutral collision models while handling chemical kinetics. The framework is highly modular with reduced user input configuration complexity and aims to support simulation efforts in development and optimization of in mass spectrometers.

SDS and TX-100 performance in removing Cd ion from contaminated sand in flushing column

In this study, contaminated sand by cadmium (Cd2+) ion was cleansed by surfactant foam in a flushing column. The ability to remove Cd2+ ion on the sand surface influenced by the surfactant's properties. The Sodium dodecyl sulfate (SDS) as an anionic surfactant was compared with Triton X-100 (TX-100) non anionic surfactant in their ability to remove the metal ion on the sand surface in the flushing column. The loading time, surfactant concentration, and flow rate of the surfactant were then investigated to confirm the charging effect of surfactant in the ability to remove metal ions. The results show that SDS has a higher ability than TX-100 to remove the Cd2+ ion on the sand surface. The optimal removal efficiency by SDS was 52 %, and TX 100 was 47 %. The loading time impacted surfactant interaction with metal ions in the column, showing that a longer loading time will increase the removal efficiency. Increased concentration of surfactants and more prolonged initial flushing tend to remove higher metal ions, indicating that the residual metal ion was flushing out on the first four pore volume removals. Flushing in a column with foam by anionic surfactant shows a higher ability to remove metal ions on the sand surface.

Thermite-for-demise (T4D): Experiments and numerical modelling on ball-bearing unit mock-ups containing thermite in an arc-heated wind tunnel

The use of thermite to aid spacecraft demise during atmospheric re-entry has been investigated in the ESA-TRP SPADEXO project. An experimental campaign in DLR's L2K arc-heated wind tunnel facility was dedicated to explore the Thermite-for-Demise concept. Steel mock-ups of a ball bearing unit, partially filled with thermite, were placed in L2K. The breadboards were then exposed to an air flux simulating the typical conditions that characterize spacecraft re-entry. In this paper, the key results of the tests are presented. The dispersion of a mechanically activated fraction of thermite proved to be effective in controlling the overall charge ignition temperature. Thermite-induced demise was experimentally verified in the wind tunnel. The SCARAB software was extended and used to rebuild the retrieved thermal data. The results of the simulations were in good agreement in both predicting the ignition timing and the effects of the thermite charge on the sample.

Flux Ratios for Effects of Permanent Charges on Ionic Flows with Three Ion Species: Case Study (II)

Flux Ratios for Effects of Permanent Charges on Ionic Flows with Three Ion Species: Case Study (II)

Effect of Nature and Charge of Counterions and Co-Ions on Electrotransport Properties of Heterogeneous Anion Exchange Membranes

Effect of Nature and Charge of Counterions and Co-Ions on Electrotransport Properties of Heterogeneous Anion Exchange Membranes

Numerical simulation study of the effect of different factors on supercritical CO2 BLEVE

Abstract Global warming is harmful to the environment and CO2 is one of the major greenhouse gases. CCS-EOR technology can increase oil production and sequester CO2. During the storage and transportation of high-pressure CO2, BLEVE may occur. In this study, the dynamic pressure parameters in the supercritical CO2 BLEVE process were numerically simulated by using numerical simulation, and the effects of initial temperature and initial charge on the dynamic pressure parameters in the supercritical CO2 BLEVE process were mainly discussed. By thoroughly investigating the dynamic pressure of BLEVE of supercritical CO2, we can better understand and predict the conditions under which such accidents occur, and further improve the safety of industrial processes.

Theoretical interpretation of W soft X-ray spectra collected by the pulse height analysis system on Wendelstein 7-X stellarator

In many fusion devices, such as tokamaks or stellarators like Wendelstein 7-X (W7-X), soft x-ray pulse height analysis (PHA) system diagnostics are routinely used during the experiments. The PHA system is dedicated to providing information about the impurity content, and average along line-of-sight electron temperature in the plasma conditions. Moreover, it is also able to estimate impurity density and an average effective charge from the comparison of experimental spectra with the modeled ones. However, the experimental x-ray spectra can be interpreted in terms of interesting plasma parameters only when the theoretical radiation models first identify and then take into account all the relevant factors that affect the spectrum. Therefore, for this purpose, a theoretical model has been applied. Flexible Atomic Code, which allows for calculation of various atomic properties such as energy levels, cross sections for excitation and ionization by electron impact, transition probabilities for radiative transitions and autoionization, and any others as needed in the collisional–radiative approximation. The chosen spectra collected during the W7-X campaign (OP1.2b) were examined, trying to obtain an agreement between the observed and simulated spectra. The analysis carried out allowed for a reliable interpretation of experimental x-ray spectra, estimation of the electron temperature, and obtaining information on the content of tungsten impurities.

Structure and properties of electrochemical interfaces with grafting polyelectrolyte: A fluid density functional theory study

The structure of the electrode/electrolyte interface directly determines electrochemical performance. One effective method for controlling this interface structure is by grafting polyelectrolyte onto the electrode surface, which can significantly alter the double layer structure and enhance electrochemical performance. This study focuses on the graft modification of polyelectrolytes at the electrochemical interface and investigates the impact of the length and density of the grafted polyelectrolyte chain on the structure and capacitance of the electrode/ionic liquid interface using fluid density functional theory (FDFT). The findings indicate that the grafted polymerbrush disrupts the alternating layer of anions and cations at the conventional interface and exerts an additional adsorption effect on counter ions, thereby reducing the density of freely movable co-ions. Consequently, this process increases the effective charge and capacitance of the interface. The results of this investigation contribute to a deeper comprehension of polyelectrolyte solutions at solid–liquid interfaces and guide the regulation of electrochemical interface properties.

Azadirachta indica leaf extract-derived NiS@Functionalized biochar catalyst: Efficient acetalization and enhanced reusability in photodegradation of tinidazole

Growing biodiesel production creates a significant volume of glycerol (Gly), a by-product that must be transformed into valuable compounds by developing novel and sustainable technologies. Solketal is one of several valuable compounds derived from residual Gly released during biodiesel synthesis. A green synthetic process followed by the co-precipitation method was used to fabricate NiS@Functionalized Biochar (NBS) using Azadrichta indica leaf extract. The nanocatalyst was extremely active for microwave-assisted solketal synthesis from Gly and acetone. A 99.7 ± 0.3 % conversion of Gly with 100 % solketal selectivity occurred under the optimum reaction conditions (catalyst loading 4 wt%, Gly to acetone molar ratio 1: 5, reaction time 6 min, and temperature 65 °C). The suggested reaction mechanism demonstrates the selective synthesis of solketal. The NBS catalyst showed excellent reusability up to six cycles, and after that, it was used for the photodegradation of tinidazole, where 89.14 % degradation efficiency was obtained within 110 min of sunlight irradiation. A narrow energy band gap (1.99 eV) and effective charge separation favor the photocatalytic activity of the reused catalyst. The environmental friendliness of the catalyst for the solketal synthesis process was examined by studying green metrics.

P‐165: Method for Verifying Polyimide Charging Effect of Flexible Display

Flexible devices fabricated on polyimide (PI) substrates can be bended, rolled and folded and have a wide range of applications. However, the technical problems of the panel fabricated on the PI substrate include device instability and image sticking due to mobile charge. In this study, we introduce a method that can easily and quickly verify mobile charge in PI. Using the existing capacitance‐voltage (C‐V) measurement method, it is possible to extract the amount of mobile charges of PI existing at the bottom of the active layer. We found that the mobile charge in the PI represents the reliability and persistence of the panel. It is shown that capacitacne fluctuations of metal‐insulator‐metal semiconductor capacitors can predict image sticking of the panel. The PI charging evaluation method proposed in this study can initailly identify defects in the early stage when there is a change in the steps or procedurres of the manufacturing panel, and opens the way to accelerate research on multi‐purpose form factors in the future.

Efficient visible light-induced H2 production by g-C3N4/NiFe Prussian blue composites

Hydrogen (H2) produced via photocatalytic water splitting shows great potential as a renewable alternative to fossil fuels, as it uses clean and renewable resources (water and solar light). However, low efficiency remains a significant challenge for this technology. In this study, we synthesized novel graphitic carbon nitride (GCN)–Prussian blue analog (PBA) heterostructure composites using suitable PBAs for photocatalytic reactions, and explored their application in visible-light-induced H2 production. GCN-PBA heterostructure composites were synthesized using PBAs containing Ni, Co, and Fe, and their photocatalytic activities under visible light irradiation were compared. The visible-light absorption characteristics and H2 production efficiency of the GCN-PBA composites were characterized. The GCN-NiFe heterostructure composite showed excellent visible-light-induced H2 production efficiency, indicating effective charge separation and transfer characteristics that enhanced the photocatalytic activity of GCN. These findings contribute to the development of efficient photocatalytic materials for solar H2 production, thereby contributing to the advancement of renewable energy technologies.