Strong Double Layer Research Articles

PENERAPAN SUPER ENKRIPSI HILL CIPHER DAN RSA UNTUK PENGAMANAN DATA FILE AUDIO MP3

Digital data security, especially audio files, is a major issue in the modern era, especially with the increasing risk of hacking and file tapping. To protect audio files such as MP3 format, this study suggests a combination of Hill Cipher and RSA algorithms for the Super Encryption method. Hill Cipher uses a linear matrix to encrypt data at high speed, while RSA uses a symmetric key created by Hill cipher to encrypt. The combination of these two algorithms produces a strong double layer of security to protect audio files. The layered encryption process uses Hill Cipher as the initial stage before using RSA for additional security. This super encryption is very good for maintaining data confidentiality. This study helps develop a digital data security system based on cryptography with a focus on audio files. This method can be used for various things, such as maintaining sensitive voice communications, maintaining important recordings, and creating applications based on audio data. However, further development can be done to improve the scalability and efficiency of this method, especially for large audio data files or data in the form of.

COSMIC RAY SOURCE AND SOLAR ENERGETIC PARTICLES

The acceleration of particles to the high energy is one of the key issues of solar physics, cis-lunar irradiations, astrophysics, and astroparticle physics. With the development of space astronomy, people started to realize that plasma disturbances in solar flares, Earth’s magnetosphere, and interplanetary space can also produce a large population of non-thermal particles. Cosmic ray promotion i.e. selective energization of matter in the cosmos requires, as on earth, three distinct stages: ionization, injection and acceleration to high energy. Supernova remnants and stellar winds of massive stars grouped in associations appear to be excellent celestial accelerators or re-accelerators through the shock waves they induce in their superbubbles. The injection of ions seems devoted to stars, except the smaller ones. In cosmic several mechanisms lead charged particle acceleration. Electrons are accelerated in direction of Earth’s poles by long train of electric double layers of small amplitudes. Charged particles are accelerated by the pondermotive force of electromagnetic radiation. Also, in a nonequilibrium current plasma or a plasma with particle flows, a strong electric double layer can be formed, which accelerates charged particles to high energies. The reconnection of the magnetic field lines also leads to the acceleration of charged particles.

Mechanical properties and microstructure of engineered cementitious composites with high volume steel slag and GGBFS

Engineered cementitious composites (ECC) achieve exceptional ductility and durability, but the heavy reliance on cement has notable environmental impacts. In this work, the steel slag (SS) and ground granulated blast furnace slag (GGBFS) are introduced into ECC by largely substituting cement. The impact of SS and GGBFS content on ECC’s mechanical performance is analyzed at macro and micro scales in terms of fiber dispersion, mechanical properties, cracking patterns, cement hydration, and microstructure. The results demonstrate that SS can enhance fiber dispersion due to the low water demand and the strong electronic double layer formed on the surface of SS particles. While ECC with a high volume of SS alone (60 wt% SS) lacks the necessary strength for structural applications, the combination of GGBFS and SS exhibits favorable hydration properties and can effectively refine the pore structure. Thus, ECC with GGBFS and SS attains ideal toughness. ASTM C 1018 based toughness indices reveal that the Imax of ECC with 30 wt% GGBFS and 30 wt% SS is 2.30 times that of OPC based ECC. A sustainability analysis demonstrates that substituting 30 wt% SS and 30 wt% GGBFS for cement leads to a 33% reduction in energy consumption and a 53% decrease in CO2 emissions of ECC.

Surface interaction mechanisms of air bubbles, asphaltenes and oil drops in aqueous solutions with implications for interfacial engineering processes

HypothesisSurface interactions of bubbles and oil with interface-active species like asphaltenes influence many interfacial phenomena in various engineering processes. It holds both fundamental and practical significance to quantitatively characterize these interactions. ExperimentsThe surface forces of air bubbles, asphaltenes and asphaltenes-toluene droplets in various aqueous solutions have been quantified using an integrated thin film drainage apparatus and an atomic force microscope coupled with bubble probe. The effects of asphaltenes concentration, pH, salinity, Ca2+ ions and surfactants have been examined. FindingsHydrophobic interaction drives attachment of bubbles and asphaltenes surfaces or oil droplets under high salinity condition. Increasing asphaltenes concentration in oil droplets enhances their hydrophobic attraction with bubbles due to strengthened asphaltenes adsorption and aggregation at oil–water interface. Increasing pH weakens the hydrophobic interaction as oil surfaces become more negatively charged and less hydrophobic. Under low salinity condition, strong electrical double layer and van der Waals repulsion inhibits the bubble-oil droplet contact. Introducing Ca2+ ions and surfactants leads to strong steric repulsion, preventing bubble-oil contact. This research has advanced our mechanistic understanding of how bubbles and oil droplets interact in aqueous systems and offers useful insights to modulate such interactions in oil production, water treatment and other interfacial processes.

Physics and instabilities of low-temperature E × B plasmas for spacecraft propulsion and other applications

Low-temperature E×B plasmas are used in various applications, such as Hall thrusters for satellite propulsion, ion sources and magnetron discharges for plasma processing, and negative ion sources for neutral beam injection in fusion. The plasmas in these devices are partially magnetized, meaning that the electrons are strongly magnetized while the ions are not. They are subject to various micro- and macro-instabilities that differ significantly from instabilities in fusion plasmas. These instabilities are often triggered by the large difference in electron and ion drift velocities in the E×B direction. The possibility of maintaining a large electric field in the quasineutral plasma of Hall thrusters despite anomalous electron transport, or the presence of strong double layers associated with the azimuthal rotation of plasma structures (“rotating spokes”) in magnetron discharges and Hall thrusters are examples of the very challenging and exciting physics of E×B devices. The turbulence and instabilities present in E×B plasma devices constitute a major obstacle to the quantitative description of these devices and to the development of predictive codes and are the subject of intense research efforts. In this tutorial, we discuss the key aspects of the physics of low-temperature partially magnetized E×B plasmas, as well as recent advances made through simulations, theory, and experiments in our understanding of the various types of instabilities (such as gradient-drift/Simon-Hoh and lower hybrid instabilities, rotating ionization waves, electron cyclotron drift instability, modified two-stream instability, etc.) that occur in these plasmas.

Absorption of Phosphonium Cations and Dications into a Hydrated POPC Phospholipid Bilayer: A Computational Study.

Molecular dynamics (MD) based on an empirical force field is applied to investigate the effect of phosphonium cations ([P6,6,6,6]+) and geminal dications ([DxC10]2+) inserted at T = 300 K into the hydration layer separating planar POPC phospholipid bilayers. Up to high concentration, nearly every added cation and dication becomes absorbed into the lipid phase. Absorption takes place during several microseconds and is virtually irreversible. The neutralizing counterions ([Cl]−, in the present simulation) remain dissolved in water, giving origin to the charge separation and the strong electrostatic double layer at the water/lipid interface. Incorporation of cations and dications changes the properties of the lipid bilayer such as diffusion, viscosity, and the electrostatic pattern. At high ionic concentration, the bilayer acquires a long-wavelength standing undulation, corresponding to a change of phase from fluid planar to ripple. All these changes are potentially able to affect processes relevant in the context of cell biology. The major difference between cations and dications concerns the kinetics of absorption, which takes place nearly two times faster in the [P6,6,6,6]+ case, and for [DxC10]2+ dications displays a marked separation into two-stages, corresponding to the easy absorption of the first phosphonium head of the dication and the somewhat more activated absorption of the second phosphonium head of each dication.

Thermo-photodynamic perspective of the simultaneous S-Scheme ternary heterostructure through Ag3VO4 shuttle for the increased photo-redox ability

A binary heterostructure bearing Ag3VO4 and InVO4 is deposited over a 2D gC3N4 nano-bed through a multistep hydrothermal technique. Though the synthesis is non-directional, the formation of the junction is governed through Ag3VO4 acting as a shuttle for charge transfer between InVO4 and gC3N4. Vacant d-orbital in the Ag3VO4 accommodated the incoming ⊡ electrons from gC3N4 forming a covalent bond through Agostic interactions and was as exhibited through DFT calculation. The chosen materials possessed dielectric, absorption, and extinction coefficient in both the low to high energy domain. Hence their amalgamation inserted robust light-harvesting properties. A 3D-2D Vandarwall junction among the binary material and the gC3N4 nano-bed has created a hierarchical attachment that resulted in a strong interfacial double layer in each junction with an internal electric field and has prevented the exciton recombination. The holistic S-scheme configuration responsible for the charge transfer was revealed. A thermo-chemodynamical understanding of photocatalysis during the MB degradation has shown the superiority of the diffusion control during the removal. The enhanced reduction potential of the Ag3VO4 center and the catalytic center has imparted higher stabilization of the transition state that resulted in lower activation energy for MB removal.

Microstructure and Time-Dependent Behavior of STx-1b Calcium Montmorillonite Suspensions

CaMnt is much less important than NaMnt due to its limited commercial applications. The time-dependent property of NaMnt gel has been studied extensively as it is exploited in many applications such as drilling mud and viscosity-modifier applications. In contrast, the time-dependent property of CaMnt suspension and the factors affecting it are largely unknown. The speciation of Ca2+ ions is one such factor to be evaluated. In the current study, pH and solids concentration were examined and then used to validate a recent theory on clay gel time dependency. The results supported the theory that a strong electrostatic double layer (EDL) repulsion in the 3-D network is needed to reorganize the structure and drive it toward the state of minimum free energy. The 12 wt.% CaMnt (STx-1b) gel displayed time-dependent behavior at pH 5 but not at its natural pH of 8.4. At pH 5, the interlayer Ca2+ ions became fully hydrated and desorbed from the platelet surface. This enhanced the EDL repulsion between the platelets. At pH >6.5, the positively charged hydrolysis product Ca(OH)+ began to form and was adsorbed, partially neutralizing the permanent layer charge and weakening the repulsion. However, at 19.4 wt.% solids, the gel displayed pronounced time-dependent behavior despite the high natural pH of 8. The platelets were much closer together, allowing the EDL force to operate and effect structural reorganization. The microstructure of these CaMnt gels showed high platelet concentrations interacting to form a relatively open structure. The microstructure of a kaolin (KGa-2) suspension which showed no time-dependent behavior even after 1 day of ageing revealed the importance of particle morphology and layer charge on time dependency. Its 3-D structure was formed by relatively thick, layered platelets with a low layer charge.

Laterally Coupled 2D MoS2 Synaptic Transistor With Ion Gating

The dynamically active synaptic elements are the fundamental building blocks in neuromorphic systems towards artificial intelligence with computing and sensing capabilities. Here, a two-dimensional (2D) MoS2 synaptic transistor is fabricated by using poly(ethylene oxide) (PEO) and lithium perchlorate (LiClO4) as a laterally coupled ion-conducting electrolyte. Due to the strong electric double layer (EDL) effect, a low operating voltage of 1 V and a high current on/off ratio of 105 have been obtained. In addition, short-term and long-term plasticity of typical synaptic behaviors have been successfully simulated, such as excitatory postsynaptic current, paired pulse facilitation long-term potentiation, long-term depression, and dynamic filtering. These results can provide new opportunities and strategies in building hybrid and low-dimensional neuromorphic systems for future artificial intelligence applications.

Current-Free Electric Double Layer in a Small Collisional Plasma Thruster Nozzle Simulation

A computational fluid dynamics and plasma model of a collisional (∼ a few Torr) radiofrequency (at 13.56 MHz) argon plasma capacitively coupled in a converging-diverging nozzle (applied to the optimisa- tion of electrothermal plasma thrusters for space use) shows the formation of a strong stationary current-free double layer (CFDL) at the 1.5 mm diameter nozzle throat for a downstream pressure of ∼ 0.1 Torr. The cycle average magnitude of the double layer potential is ∆ΦDL = 77 V and the electron temperature at the high potential edge of the double layer is kBTe = 2.64eV, yielding a strength of ∆ΦDL/(kBTe) ∼ 30. The double layer is 1.2 mm wide which corresponds to ∼ 90 Debye lengths. The axial electric field of the double layer accelerates ions along the nozzle to a maximum drift velocity of 17 km s−1, about 3.3 times the ion sound speed, and their kinetic energy is transferred to neutrals by ion-neutral charge exchange col- lisions. The ion transit time τi through the potential structure spontaneously forming at the nozzle throat is about 5 times the radiofrequency excitation period τRF. These findings are discussed in the broader context of double layer physics and the dynamics of their formation as well as in the context of electrothermal thruster optimisation in which neutral propellant heating via ion-neutral charge exchange collisions is the main source of thrust.

Microscopic insights into the ion transport in graphene-based membranes with different interlayer spacing distributions

The ion transport in nanoscale pores/channels are totally different to that in the macroscopic level. Here, a combined method based on the Poisson-Nernst-Planck (PNP) and Navier–Stokes (NS) equations is applied to study the ion transport in graphene oxide membranes (GOMs) with different interlayer spacing distributions by controlling the offset angle of the middle nanosheet of the model. The layered membrane with suitable interlayer spacing distribution has strong electrical double layer (EDL) overlapping and relatively weak spatial confinement, which improves the ion selectivity and water permeation. This phenomenon can be further understood by analyzing microscopic properties including the local density and flux profiles with considering the effects of surface charge and bulk concentration. This work could provide macroscopic insights into the ionic flow in laminar GOMs at a different angle and possible improvement of the GOMs performances.

Effect of ion concentration and multivalence on methane-brine interfacial tension and phenomena from molecular perspectives

Gas-brine interfaces play an important role in natural gas recovery, which can be negatively affected by capillary pressure, induced by the interfacial tension (IFT) between gas and brine phases. Therefore, understanding about the gas-brine IFT is of great importance for natural gas production. While experiments can measure the IFT, the underlying mechanisms and interfacial phenomena remain less clear at molecular level. Previous molecular simulation works are limited to narrow salt concentrations and types. In this work, we use molecular dynamics (MD) simulations to study IFT between methane and brine containing various monovalent and divalent cations (Na+, K+, Mg2+, and Ca2+) over wide range of salt concentrations (∼0.05 to ∼4.53 M, i.e. between ∼3.0 and ∼23.6 wt% in terms of NaCl solution) under reservoir conditions. We find that methane accumulates at interfaces, resulting in the decrease of IFT as pressure increases, but becomes insignificant at high pressures. On the other hand, pressure has minor effects on water and ion distributions. Cation type has a negligible effect for given anion (Cl−) concentrations, indicating that the charge molarity is the dominant factor to determine the gas-brine IFT. In addition, while both cations and anions deplete from the gas-brine interfaces, divalent cations are more devoid from the interface than monovalent cations, showing strong electrical double layers. The electrostatic potentials on the gas and brine sides are positive and negative, respectively. Our study should provide fundamental understandings on the gas-brine interfacial properties, and important insights into natural gas production.

Bottom-up and top-down manipulations for multi-order photonic crystallinity in a graphene-oxide colloid

Dispersions of graphene oxide nanoflakes in water can be manipulated into photonic crystals that reflect the full spectrum of visible colour. Normally, dissolving nanometre-thin graphene oxide crystals in water produces brownish solutions. Jang-Kun Song from Sungkyunkwan University in South Korea and co-workers used extensive oxidation and cleaning procedures in combination with bottom-up and top-down control strategies to coax unexpected optical activity from the irregularly shaped nanoflakes. The team's synthetic procedure produced a strong electric double layer on graphene oxide surfaces that induced the particles to stack into periodic, light-reflecting structures similar to cholesteric liquid crystals. Adding salt ions to the watery dispersion allowed the photonic structures, and hence the colour reflections, to be adjusted at molecular scales. Alternatively, the researchers could ‘paint’ glass slides by using shear forces produced by stirring to direct colour output.

Double layer electric fields aiding the production of energetic flat-top distributions and superthermal electrons within magnetic reconnection exhausts

Using a kinetic simulation of magnetic reconnection, it was recently shown that magnetic-field-aligned electric fields (E∥) can be present over large spatial scales in reconnection exhausts. The largest values of E∥ are observed within double layers. The existence of double layers in the Earth's magnetosphere is well documented. In our simulation, their formation is triggered by large parallel streaming of electrons into the reconnection region. These parallel electron fluxes are required for maintaining quasi-neutrality of the reconnection region and increase with decreasing values of the normalized electron pressure upstream of the reconnection region, βe∞=2μ0ne∞Te∞/B∞2. A threshold (βe∞ < 0.02) is derived for strong double layers to develop. We also document how the electron confinement, provided in part by the structure in E∥, allows sustained energization by perpendicular electric fields (E⊥). The energization is a consequence of the confined electrons' chaotic orbital motion that includes drifts aligned with the reconnection electric field. The level of energization is proportional to the initial particle energy and therefore is enhanced by the initial energy boost of the acceleration potential, eΦ∥=e∫x∞E∥dl, acquired by electrons entering the region. The mechanism is effective in an extended region of the reconnection exhaust allowing for the generation of superthermal electrons in reconnection scenarios, including those with only a single x-line. An expression for the phase-space distribution of the superthermal electrons is derived, providing an accurate match to the kinetic simulation results. The numerical and analytical results agree with detailed spacecraft observations recorded during reconnection events in the Earth's magnetotail.

Novel Amphiphilic Comb-Like Polymers: Synthesis, Characterization, and Their Properties as Viscosifying and Filtration Additives for Drilling Fluids

Novel amphiphilic comb-like polymers (CPASA), used as viscosifying and filtration loss additives for low-solid water-based drilling fluids under high temperature and salinity conditions, were prepared from acrylamide, sodium 4-styrenesulfonate, and allyl polyethylene glycol ether with toluylene-end groups via inverse microemulsion polymerization. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (1H-NMR). The thermal stability, aqueous solution properties, and drilling fluid properties were evaluated. Results showed that the comb-like polymers exhibited dramatic enhancement in their thermal- and salt-resistant properties because of the steric hindrance and intermolecular associations of the side-chains. The rheological properties, filtration properties, and negative Zeta potentials of both fresh-water drilling fluid and saturated salt-water drilling fluid were greatly improved by the addition of CPASA before and after thermal aging tests, which were ascribed to the steric hindrance of its comb-like conformation, the strong electrical double layer force of clay particles, and the stable mud network formed by CPASA and clay particles in drilling fluid.

Instability limits for spontaneous double layer formation

We present time-resolved measurements that demonstrate that large amplitude electrostatic instabilities appear in pulsed, expanding helicon plasmas at the same time as particularly strong double layers appear in the expansion region. A significant cross-correlation between the electrostatic fluctuations and fluctuations in the number of ions accelerated by the double layer electric field is observed. No correlation is observed between the electrostatic fluctuations and ions that have not passed through the double layer. These measurements confirm that the simultaneous appearance of the electrostatic fluctuations and the double layer is not simple coincidence. In fact, the accelerated ion population is responsible for the growth of the instability. The double layer strength, and therefore, the velocity of the accelerated ions, is limited by the appearance of the electrostatic instability.

Observation of multiple current free helicon double layers

A combination of three strong current free double layers (CFDLs) characterized by strength (eΔΦ/Te) ∼ 10 and widths (Δz/λD) ∼ 7.6, 8, and 8.3 has been observed in argon helicon plasma. In contrast to other works report on the same subject, in the present investigations the DLs form in a mirror-like magnetic field topology and present in the plateau regions of magnetic field. Using the measurement of radio frequency compensated Langmuir Probe consistent with the B-dot probe diagnostic, a qualitative mechanism of DL formation has also been discussed.

Rotating Instability in Low-Temperature Magnetized Plasmas

The formation of a rotating instability associated with an ionization front ("rotating spoke") and driven by a cross-field current in a cylindrical magnetized plasma is shown and explained for the first time on the basis of a fully kinetic simulation. The rotating spoke is a strong double layer (electrostatic sheath) moving towards the higher potential region at a velocity close to the critical ionization velocity, a concept proposed by Alfvén in the context of the formation of the solar system. The mechanisms of cross-field electron transport induced by this instability are analyzed.

Preparation of a novel amphiphilic comb-like terpolymer as viscosifying additive in low-solid drilling fluid

Comb-like polymers have attracted a strong research interest due to their many attractive properties. Novel amphiphilic comb-like terpolymer (PASA), as viscosifying additive for low-solid drilling fluid under high temperature and salinity, was prepared and characterized by FTIR, 1H-NMR and TGA. PASA possessed excellent thermal stability. The rheological properties, filtration properties and negative Zeta potentials of both freshwater drilling fluid and saturated salt-water drilling fluid were greatly improved by adding PASA before and after thermal aging tests, due to comb-like conformation of PASA, strong electrical double layer force of bentonite particles and stable network structure formed by PASA and bentonite particles.

Dielectronic satellite lines and double layers in solar flares

Context. Particle acceleration during solar flares results in departures of the distribution of particle energies from the Maxwellian distribution. Apart from the high-energy tail, the bulk of the distribution was recently also found to be significantly affected, due, e.g., to the presence of double layers. Aims. We investigate the influence of several proposed non-Maxwellian distribution functions on the X-ray flare line spectra. The distribution functions considered are sharply peaked and include the n-distribution, the moving Maxwellian distribution, and the distribution formed in strong double layers in the flaring plasma. Methods. Synthetic Si xiid‐Si xiv spectra involving allowed and dielectronic transitions at 5−6 A are calculated numerically. The parameters chosen for the calculations correspond to the impulsive phase of solar flares, as inferred by previous authors. Results. The Si xiid λ5.56/Si xiii λ5.68 and Si xiid λ5.82/Si xiii λ5.68 ratios depend on the relative number of electrons at energies corresponding to the formation of the Si xiid lines. Therefore, these ratios increase with the increasing narrowness of the peak of the electron distribution function. The highest ratios are achieved for the distribution formed in double layers, while the moving Maxwellian distribution is less likely to reproduce the observed enhancement of Si xiid intensities. However, the ratio of the allowed Si xiv λ5.22/Si xiii λ5.68 transitions depends on the ionization equilibrium. This ratio is very small for the double-layer distribution. Combination of the double-layer distribution with a Maxwellian distribution with the same mean energy significantly enhances this ratio, while keeping the Si xiid intensities sufficiently increased to explain the characteristics of the observed spectra. Conclusions. These results support the presence of double layers in the plasma during impulsive phase of solar flares.