Surface Conductivity Research Articles

Aggregation, Not Micellization: Perfluorooctanoic Acid, Perfluorobutanesulfonic Acid, and Potassium Perfluorooctanesulfonate Behavior in Aqueous Solution.

Surface tension, conductivity, and dynamic light scattering (DLS) measurements were used to examine the surface and bulk solution behaviors of three members of the PFAS family, perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and the potassium salt of perfluorooctanesulfonic acid (PFOS). Measurements were carried out in solutions having variable (acidic) pH and in solutions buffered to pH = 8.0. Surface tension data show traditional soluble surfactant behavior, and results illustrate that PFOA, PFBS, and PFOS surface activity depends sensitively on solution phase pH. The tightly packed monolayers formed by PFOA in mildly acidic solutions imply that the surface pH of PFOA solutions is several units lower than bulk. Results from conductivity experiments generally show increasing conductivity with increasing bulk solution surfactant concentration. In pH = 8.0 solutions, changes in conductivity slope with surfactant concentration suggest the onset of micelle formation at concentrations <1 mM, markedly lower than reported in literature. In general, apparent critical micelle concentrations (CMCs) determined from conductivity data agree with similar predictions made from surface tension results. DLS measurements show that at concentrations close to the predicted PFAS CMCs, objects with diameters ≤10 nm start to form. However, unlike micelles, these objects continue to grow with increasing bulk solute concentration. These aggregates form structures having diameters of 50-150 nm. Aggregate size shrinks modestly as solution phase temperature increases, and this behavior is reversible. Cryo-EM images of PFOA solutions confirm a broad distribution of particles, supporting the DLS measurements. Findings reported in this work represent the first evidence that these three EPA-regulated PFAS surfactants form aggregates rather than micelles in solution. Findings also begin to reconcile differences in reported surface behaviors that have led to CMC predictions in the literature varying by more than an order of magnitude.

Rapid In Situ Preparation of Conductive Graphite-like Films on Polymer Surfaces via Hydrogen Plasma Technology.

Many special polymer materials with high strength, low density, and high processability have been developed for the substitution of metal products in recent years; however, their electrical insulation properties sometimes limit their application in medicine, electronics, and aerospace fields. Constructing a conductive layer on polymers may be a promising strategy for conquering these problems, but simply obtaining a high-quality conductive layer remains a challenge. Here, we develop a universal strategy to in situ fabricate a conductive graphite-like film on various polymer surfaces based on a simple one-step gas plasma ion implantation method. Theoretical and experimental results confirm that the reducibility of free radicals and the electrophilicity of cations in plasma are critical for the formation of graphite-like films on polymer surfaces. Compared with argon and oxygen plasma, hydrogen plasma with strong reducing hydrogen radicals and weak electrophilic hydrogen cations can produce the highest degree of graphitization of graphite-like films. The as-prepared polymers treated by hydrogen plasma ion implantation presented good surface conductivity and reduced friction coefficient, which has great potential for application in medicine, electronics, and aerospace fields.

Mn-Fe Dual-Metal Assemblages on Carbon-Coated Al2O3 Spheres for Catalytic Ozonation Oxidation: Structure, Performance, and Reaction Mechanism.

Catalysts with high catalytic activity and low production cost are important for industrial application of heterogeneous catalytic ozonation (HCO). In this study, we designed a carbon-coated aluminum oxide carrier (C-Al2O3) and reinforced it with Mn-Fe bimetal assemblages to prepare a high-performance catalyst Mn-Fe/C-Al2O3. The results showed that the carbon embedding significantly improved the abundance of surface oxygen functional groups, conductivity, and adsorption capacity of γ-Al2O3, while preserving its exceptional mechanical strength as a carrier. The prepared Mn-Fe/C-Al2O3 catalyst exhibited satisfactory catalytic ozonation activity and stability in the degradation of p-nitrophenol (PNP). Electron paramagnetic resonance (EPR) and quenching experiments reveal that radical ( ⋅ OH and ⋅ O2 ⋅ ) and nonradical oxidation (1O2) dominated the PNP degradation process. Theoretical calculations corroborated that the anchored atomic Fe and Mn sites regulated the local electronic structure of the catalyst. This modulation effectively promoted the activation of O3 molecules, resulting in the generation of atomic oxygen species (AOS) and reactive oxygen species (ROS). The economic analysis on Mn-Fe/C-Al2O3 revealed that it was a cost-competitive catalyst for HCO. This study not only deepens the understanding on the reaction mechanism of HCO with transition metal/carbon composite catalysts, also provides a high-performance and cost-competitive ozone catalyst for prospective application.

On the Reliability of Constraining Surface Conductivity using Induced Polarization Measurements in Sedimentary Rocks

Summary Recent advances in understanding the induced polarization (IP) method have led to improvements in interpreting hydraulic properties from electrical measurements. Distinguishing the effect of surface conduction from conduction through the electrolyte filling the interconnected pore spaces has been an ongoing challenge in interpreting field-scale electrical resistivity datasets. Previously proposed mechanistic models have suggested that this limitation can be overcome by utilizing the coefficient that describes the ratio between IP measurements and surface conductivity. In this study, we examine this proportionality coefficient ($\mathcal{l}$) through the relationship between IP parameters (imaginary conductivity and normalized chargeability) and surface conductivity for a sample group of 98 sedimentary rocks, composed of sandstones, carbonates, and mudstones. A strong linear relationship is observed between the IP parameters and surface conductivity. However, values of $\mathcal{l}$ vary significantly across each sample group such that low-salinity estimates of formation factor (F) using the single universal estimate of $\mathcal{l}$ are poor. Estimates of F for a single rock type (sandstone, carbonate, or mudstone) are improved using $\mathcal{l}$ values unique to that rock type, although F estimates for mudstones show high sensitivity to changes in $\mathcal{l}$. Using $\mathcal{l}$ coefficients calibrated on a sample group with similar lithological properties to the investigated group moderately improves the estimation of F. Consistent with theory, no relationship is observed between the proportionality coefficient and the measured petrophysical parameters of the porous medium. Our results suggest that, although IP measurements provide a valuable field-scale proxy for surface conductivity, improving petrophysical predictions (i.e. in this case, estimating F) remains a challenge.

Germanium surface segregation in highly doped Ge:β-Ga2O3 grown by molecular beam epitaxy observed by synchrotron radiation hard x-ray photoelectron spectroscopy

We present a study of Ge segregation at the surface of highly germanium-doped gallium oxide (2.5 × 1020 cm−3 nominal doping level) grown by molecular beam epitaxy. We probed the dopant concentration as a function of depth by hard x-ray photoelectron spectroscopy and standard laboratory photoemission spectroscopy. We notably found that there is germanium segregation within the top 2 nm where its concentration is 3 times the nominal doping level. This increased dopant concentration leads to a threefold enhancement of surface conductivity. The results suggest a reliable method for delta doping for power electronics applications.

Induced polarization of clay-rich materials. 4. Water content and temperature effects in bentonites

Deep geological disposals (DGDs) are widely seen to be the best solution to contain high-level radioactive wastes safely. Compacted bentonite and bentonite-sand mixtures are considered the most appropriate buffers or sealing materials for access drifts, ramps, and shafts due to their favorable physicochemical and hydro-mechanical properties. Bentonite-sand mixtures are expected to swell and seal all voids when in contact with water, forming an impermeable barrier to radioactive elements. The parameters that will most affect the hydraulic performance of these seals are their water content, dry density, water salinity, and temperature. Monitoring and assessing these parameters are, therefore, crucial to confirm that the seals’ safety functions are fulfilled during the life of a DGD. Induced polarization (IP) is a nonintrusive geophysical method able to perform this task. However, the underlying physics of bentonite sand mixtures has not been checked. The complex conductivity spectra of 42 compacted bentonite-sand mixtures were measured in the frequency range of 1 Hz–45 kHz in order to develop workable relationships between in-phase and quadrature conductivities versus water content and saturation, pore water conductivity, bentonite-sand ratio (10% to 100%), temperature (10°C–60°C), and dry density (0.97 to 1.64 g cm−3). We observe that conductivity is mostly dominated by surface conductivity associated with the Stern layer (SL) coating the surface of smectite, the main component of bentonite. At a given salinity and temperature, the in-phase and quadrature conductivities obey the power law relationships with water content and saturation. The in-phase and quadrature conductivities depend on the temperature according to a classical linear relationship with the same temperature coefficient. An SL-based model is used to explain the dependence of the complex conductivity with water content, dry density, water salinity, and temperature. It could be used to interpret the IP field data to monitor the efficiency of the seal of DGD facilities.

Interface-Engineered MoSe2-Co9S8 Nanoheterostructures with Enhanced Charge Storage Performance for Supercapacitor Application.

Cobalt-based chalcogenides have emerged as fascinating materials for supercapacitor applications owing to the presence of various mixed valance oxidation states in their structure along with rich electrochemical properties. However, their limited stability and cyclic performance hinder their viability for practical use in supercapacitors. Herein, a facile hot injection colloidal route is demonstrated to design MoSe2-Co9S8 nanoheterostructures (NHSs), which entails the epitaxial growth of Co9S8 nanoparticles (NPs) over the basal planes of ultrathin MoSe2 nanosheets (NSs). The interfacial engineering of the basal planes of MoSe2 NSs with Co9S8 NPs regulates the electronic properties and defects at the interfaces and increases the overall specific surface area and conductivity. As a result, MoSe2-Co9S8 NHSs electrode unveils a substantially higher specific capacitance of 910.5 F g-1 at 1 A g-1current density surpassing their individual counterparts. In addition, it demonstrates worthy solidity, retaining ≈90% of its capacitance and coulombic efficiency of 93.3% after 10,000 charge-discharge cycles at a high charge-discharge current density of 15 A g-1. As a proof-of-concept, coin cells are fabricated using MoSe2-Co9S8 NHSs which show 93% Coulomb efficiency and 86% capacitance retention. This study would pave the way for designing transition metal dichalcogenides (TMDs) - derived NHSs with superior capacitive properties.

Load-bearing characteristics of surface conductor in deepwater gas hydrate formations

The surface conductor is the first structural casing in deepwater natural gas hydrate (NGH) development, bearing the top load while suspending the casings of various layers. NGH decomposition leads to formation settlement, changing the mechanical properties of the formation and reducing the bearing capacity of the surface conductor, threatening the safety and stability of the wellhead. Understanding the bearing characteristics of the surface conductor in the hydrate formation can guide the safe drilling operation in the field. By introducing the negative skin friction theory of pile foundations and based on conventional bearing capacity models, a method for calculating the bearing capacity of surface conductors in NGH formations was developed. Using an NGH drilling simulation apparatus, the accuracy of the bearing capacity theoretical model was verified, empirical coefficients under different conditions were obtained, and the influence of soil parameters, hydrate saturation, and decomposition temperature on the bearing capacity of surface conductors was quantified. The results indicated that compared to clay, sandy soils have higher porosity and significantly weakened strength after the decomposition of NGH; when the hydrate saturation in the formation is 20%, the reduction in bearing capacity of the surface conductor in sand exceeds 30%, and in clay soils, it decreases by 25% after complete decomposition of NGH; as the hydrate saturation increases, the reduction in the bearing capacity of surface conductors after decomposition becomes more significant. Verified through Experimentation, the error of the hydrate-bearing strata-bearing capacity model is around 10%. For short-term test production operations of NGH in water, the design depth for surface conductors is around 100 meters. These research results can provide a scientific theoretical basis for the design of conductor depth below the mud， and reduce operational risks.

Alkali and alkaline earth metals induced n-type surface transfer doping of diamond: A first-principles calculation

The advancement of diamond-based electronic devices is hindered by the n-type doping in diamond, which is a major challenge for diamond. Surface transfer doping is an effective way for modulating the surface conductivity. In this study, we propose and select eight kinds of alkali and alkaline earth metals with low electronegativities as n-type surface dopants on F-terminated diamond using first-principles calculations. Our results reveal n-type doping is realized on diamond surface, and a negative correlation between the electronegativity of metal dopants and areal electron density. High areal electron densities of 2.975 × 1013 and 3.102 × 1013cm-2 and room-temperature electron mobilities of 1102 and 1152 cm2 V-1 s-1 are obtained on Rb and Cs doped diamond surfaces, respectively. Our findings provide a way for designing of n-type diamond, and it is helpful for the understanding of the surface doping mechanism for semiconductors.

Solving an internal problem for finite regular two-dimensional lattice spiral elements, excitable plate electromagnetic wave

Background. The work is aimed at developing and researching rigorous methods for solving internal problem of electrodynamics for multi-element structures (metastructures) consisting from the final number of elements, as well as to study the physical processes occurring in them. A special case of such structures are two-dimensional lattices with a fixed interelement distance, consisting of identical elements having the same spatial orientation (regular lattices). Aim. In this work, based on an iterative approach, the internal solution is solved. problems of electrodynamics for a finite regular two-dimensional lattice of spiral elements. In order to obtain a priori information about the electrodynamic characteristics of elements lattice and justification for the choice of projection function systems are analyzed spectral characteristics of the integral operator of the internal problem for a single spiral element. Then the currents on the structure elements are calculated, their spectral characteristics are determined. The results of spectral analysis allow increase the efficiency of solving an internal problem. Methods. The research is based on a strict electrodynamic approach, within the framework of which, for the specified structure in the thin-wire approximation, an integral representation of the electromagnetic field is formed, which, when considered on the surface of conductors together with boundary conditions, is reduced to a system of Fredholm integral equations of the second kind, written relative to unknown current distributions on conductors (internal task). The solution of the internal problem within the framework of the method of moments is reduced to solving a SLAE with a block matrix. Results. A mathematical model of a finite two-dimensional lattice of spiral elements is proposed radiating structure. For the specified structure, in the case of its excitation by a flat electromagnetic wave, based on the iterative approach, the internal problem of electrodynamics was solved. The following were carried out in a wide frequency range: analysis of the convergence of the iterative process, spectral analysis of the integral operator of the internal problem for a single spiral element, as well as spectral analysis of external field and current functions functions on lattice elements. Conclusion. The feasibility of determining the spectral characteristics of integral operators is shown internal task for the elements forming the metastructure. A relationship has been identified between the frequency dependence eigenvalues of the integral operator of the internal problem of single elements, forming a metastructure, with resonance phenomena arising in the metastructure, the influence of resonances on the convergence of the iterative process was confirmed. The feasibility of considering averaged amplitude current spectra is shown. It was revealed that the averaged spectrum of current functions is close to degenerate, especially near resonant frequencies. This allows for use as projection functions a compact set of eigenfunctions that have significant amplitudes in the vicinity of the frequency under study, which significantly simplifies the solution of the internal problem.

Electrodynamic analysis of a sinusoidal antenna for small wave sizes

Background. The work is aimed at developing and researching rigorous methods for calculating thin-wire structures with a complex generatrix shape, having small wave sizes, as well as studying the physical processes occurring in them. A special case of such structures is a sinusoidal antenna operating in a standing current wave mode. Aim. In progress the solution of internal and external problems of electrodynamics is carried out for a sinusoidal antenna of small wave sizes located above an infinitely extended ideal reflector. The currents on the elements of the structure are calculated, its input resistance and radiation characteristics are determined. Methods. The research is based on a strict electrodynamic approach, within the framework of which, for the specified structure in the thin-wire approximation, an integral representation of the electromagnetic field is formed, which, when considered on the surface of conductors together with boundary conditions, is reduced to a system of Fredholm integral equations of the second kind, written relative to unknown current distributions on conductors (internal task). Results. A mathematical model of the radiating structure is proposed, determined: the input resistance of the structure and the basic characteristics of its radiation. It is shown that the operating range of a sinusoidal antenna in the standing wave mode is determined by the quality factor of the input impedance resonances; An increase in the width of the sinusoidal conductor leads to a decrease in the resonant frequencies of the input resistance with a simultaneous increase in the quality factor of the resonances. Conclusion. From a practical point of view, the use of the considered structure allows significantly reduce the dimensions in comparison with a thin electric vibrator, however in this case, the operating range will be correspondingly narrowed, which is determined, due to the weak dependence of the radiation characteristics on frequency, by the quality factor of the resonances. The current distribution on the generatrix of the structure can be considered as a «projection» standing surface wave localized in the plane of a sinusoidal conductor, and resulting from the superposition of forward and backward surface (slow) waves propagating at a speed significantly lower than the speed of light. To further clarify the physics of the processes occurring in the structure, one should use spectral analysis of current functions and study the distributions of the electromagnetic field in the near zone of the structure.

Spectroscopic Evidence of Ultrafast Topological Phase Transition by Light-Driven Strain.

Enabling reversible control over the topological invariants, transitioning them from nontrivial to trivial states, has fundamental implications for quantum information processing and spintronics. It offers a promising avenue for establishing an efficient on/off switch mechanism for robust and dissipationless spin-currents. While mechanical strain has traditionally been advantageous for such manipulation of topological invariants, it often comes with the drawback of in-plane fractures, rendering it unsuitable for high-speed, time-dependent operations. This study employs ultrafast optical and THz spectroscopy to explore topological phase transitions induced by light-driven strain in Bi2Se3. Bi2Se3 requires substantial strain for Z2 switching. Our observations provide experimental evidence of ultrafast switching behavior, demonstrating a transition from a topological insulator with spin-momentum-locked surfaces to hybridized states and normal insulating phases under ambient conditions. Notably, applying light-induced strong out-of-plane strain effectively suppresses surface-bulk coupling, facilitating the differentiation of surface and bulk conductance even at room temperature─significantly surpassing the Debye temperature. We expect various time-dependent sequences of transient hybridization and manipulation of topological invariant through photoexcitation intensity adjustments. The sudden surface and bulk transport alterations near the transition point enable coherent conductance modulation at hypersound frequencies. Our findings on the potential of light-triggered ultrafast switching of topological invariants hold promise for high-speed topological switching and its related applications.

CoFe2O4 nanoparticle embedded carbon nanofibers: A promising non-noble metal catalyst for oxygen evolution reaction

There is a strong demand for noble metal-free durable catalysts to facilitate the advancement of clean, sustainable energy technologies and to replace energy equipment reliant on fossil fuels. In this study, metal-organic framework (MOF)-derived CoFe2O4 (CFO) nanoparticle-embedded electrospun carbon nanofibers (CNFs) were synthesized. Nanofibers were calcined at three different temperatures to obtain optimum electrocatalytic performance in oxygen evolution reaction (OER). Nanofibers annealed at 800 °C (CFO@CNFs 800) displayed a reduced overpotential of 300 mV while maintaining a steady current density of 10 mA cm−2. CFO@CNFs 800 demonstrated Tafel slope 42 mV dec−1 with excellent long-term stability up to 48 h. The synergistic effect of the redox activity of CFO coupled with the high surface area and conductivity of carbon nanofibers is responsible for enhanced OER performance.

Stable Zinc Metal Battery Development: Using Fibrous Zirconia for Rapid Surface Conduction of Zinc Ions With Modified Water Solvation Structure.

The two most critical technical issues in Zn-based batteries, dendrite formation, and hydrogen evolution reaction, can be simultaneously addressed by introducing negatively charged fibrous ZrO2 as a separator. Electron redistribution between ZrO2 and Zn2+ ions renders the ZrO2 surface a preferred adsorption site for Zn2+ ions, making surface conduction the primary ion-transport mode. Surface conduction enables fibrous ZrO2 to exhibit a 6.54 times higher single-Zn-ion conductivity than that of conventional glass fiber, minimizing the concentration gradient of Zn2+ and suppressing dendrite formation. Additionally, strong Zr─O─Zn bonding stabilizes the Zn2+ ions with fewer solvated H2O molecules (≈2), preventing water molecules from approaching the electrode surface, as evidenced by a 58.8% decrease in the hydrogen evolution rate. Consequently, the cycling stability of a fibrous-ZrO2-based Zn/Zn symmetric cell (3000h at 1mAhcm-2 and 5mAcm-2) is approximately ten times greater than that of the conventional variant. Furthermore, a fibrous-ZrO2-based Zn-I2 full cell exhibits a notably high energy density (271.4Whkg-1) as well as a long lifespan (≈5000 cycles) at an ultrahigh current density (4Ag-1).

Satellite remote sensing reveals the footprint of biodiversity on multiple ecosystem functions across the NEON eddy covariance network

Abstract Biodiversity relates to ecosystem functioning by modulating biogeochemical cycles of carbon, water, energy, and nutrients within and between multiple biotic and abiotic components of the ecosystems. However, large-scale, systematic measurements of plant biodiversity are still lacking, and the effects of biodiversity on measured biogeochemical processes are understudied. Here, we combined alpha (α) and beta (β) taxonomic measurements, spectral diversity from satellite observations, structural properties of the vegetation, and climatic drivers to assess the effect of biodiversity on ecosystem functional properties. Ecosystem functional properties were computed from eddy-covariance fluxes at 44 sites of the National Ecological Observatory Network. Based on the spectral variation hypothesis, we used the near-infrared reflectance of vegetation (NIRv) derived from Sentinel-2 satellite imagery to compute Rao’s quadratic entropy (Rao Q), a distance metric related to spatial heterogeneity. Using an automatic model averaging technique, we found that biodiversity proxies hold substantial explanatory power when predicting several ecosystem functions related to carbon and water exchange. In particular, NIRv-based Rao Q (RaoQNIRv) reflected positive biodiversity effects on productivity, as expected from the literature. In contrast, traditional taxonomic α-diversity indices were generally not selected as relevant predictors of the ecosystem functional properties. Yet, β-diversity strongly contributed to the prediction of carbon use efficiency, surface conductance, and water use efficiency. We also found that the RaoQNIRv is less affected by issues of saturation and bare soil contribution compared to RaoQNDVI. We show that spectral heterogeneity based on remotely sensed NIRv holds the potential for globally characterizing the biodiversity-ecosystem functioning relationship (BEF). While systematic measurements of taxonomic diversity co-located at biogeochemical measurement stations could reduce the uncertainty surrounding the BEF relationship at whole-ecosystem scale, remotely- sensed metrics characterizing important functional and structural diversity aspects of the landscape will be crucial for continuous spatiotemporal monitoring of biodiversity with relevant implications for ecosystem services to humankind.

Emerging 2D MXene quantum dots for catalytic conversion of CO2

MXene is an emerging material for converting carbon dioxide (CO2) into valuable products because of its robust physical and chemical properties. The high specific surface area (SSA), conductivity, and stability of the MXene make it an attractive material for the catalytic conversion of CO2. The pristine MXene possessed poor catalytic properties as compared to their composites. This study briefly discussed the magical properties and advanced synthesizing routes of MXene and MXene quantum dots (MQDs). In addition, the oxidation of the MXene is responsible for altering its chemical composition, and the factors used to oxidize the MXene were discussed in detail. Furthermore, the mechanism of hydrogenation, chemical, electrocatalytic, and photocatalytic reduction of CO2 has been discussed. Finally, the MXene quantum dots (MQDs) for photocatalytic conversion of CO2 for the first time also present the future challenges and prospectus associated with MXene.

Effect of Methyl Red on the surface properties of DTAB in CH3OH–H2O

The purpose of this study is to investigate the effect of Methyl Red (MR) on the micellization and surface properties of a cationic surfactant, dodecyl trimethylammonium bromide (DTAB), in CH3OH–H2O mixed solvent systems at varying CH3OH parts by volumes (0.1, 0.2, 0.3, and 0.4) and temperatures (298.15 K, 308.15 K and 318.15 K). Surface tension and conductivity measurements were conducted to obtain the critical micelle concentration (CMC) and various surface properties such as premicellar slope (dγdlogC), maximum surface concentration (Γmax), minimum surface area occupied (πCMC), free energy of adsorption (ΔGadso), adsorption efficiency (pC20), packing parameter (P), and aggregation number (Nagg). The results indicate that the presence of MR significantly influences the behavior of DTAB in the mixed solvent system. In the absence of MR, the CMC increased with higher CH3OH content, while MR reduced the CMC, promoting micelle formation through dye-surfactant-ion-pair (DSIP) formation. Surface properties were enhanced in the presence of MR leading to higher surface pressure. Additionally, the free energy of adsorption (ΔGadso) became more negative with MR, indicating a more favorable adsorption process. Correlations of (dγdlogC), Γmax,γ0/γcmc, pC20, Nagg, CMC/C20 with the parts by volume of CH3OH at 298.15 K, 308.15 K, and 318.15 K are discussed with and without MR. The obtained results were used to examine the effect of MR on the surface properties of DTAB in the CH3OH–H2O medium. The change in properties can be explained in terms of the change in polarity of the medium and dye-surfactant ion pair (DSIP) formation.

Research on the mechanism of impact of vibrational loads on the bearing capacity of drilling surface conductor

The surface conductor is the first structural pipe in the development of deep-water oil and gas resources, bearing the top load and suspending various casing layers. Vibrational loads can cause soil structural damage and increase pore pressure, reducing the bearing capacity of the surface conductor and threatening the safety and stability of the subsea wellhead. Based on the vertical force analysis of the surface conductor and considering the impact of vibrational loads on soil strength, a model for the vertical bearing capacity of the surface conductor was established. Utilizing the dynamic Winkler model for pile foundation horizontal dynamic response, the surface conductor was simplified as a bending beam subjected to harmonic vibration, and a control equation for lateral deformation of the surface conductor was established. The effects of vibration load amplitude and frequency on the vertical bearing capacity of surface conductors were analyzed through simulation experiments, resulting in an equivalent bearing capacity coefficient for surface conductors ranging from 0.88 to 0.97. Combining the engineering data from a deep-water block in the South China Sea, the reliability of the theoretical calculation model was validated. The analysis indicates that the maximum bending moment of the surface conductor is approximately 6m below the mudline; low-frequency(0.05Hz–0.2Hz) vibrational loads can reduce the ultimate bearing capacity of the surface conductor by 3%–11%, with the effect gradually diminishing over time. This research provides a theoretical basis for the design of surface conductor in deep-water oil and gas wells.

Progress in aluminum-ion battery technology: innovations in cathode materials, electrolyte chemistry, and performance enhancement

The review explores recent advancements in aluminum-ion battery technology, focusing on innovations in cathode materials, electrolyte chemistry, and performance enhancement. Notable developments include new cathode materials like activated carbon and graphene composites, which improve surface area, conductivity, and overall battery performance. Advances in electrolyte formulations, particularly AlCl3-based ionic liquids, have optimized ion transport and stabilized electrochemical processes, extending cycle life and reliability. Studies on ion intercalation mechanisms using density functional theory and molecular dynamics have provided insights into electrode transformations during charge-discharge cycles, aiding in the design of cathode materials with higher ion storage capacities and improved cyclability. These advancements highlight AIBs' potential as a promising alternative for large-scale energy storage applications.

Mechanism exploration of ion-implanted epoxy on surface trap distribution: An approach to augment the vacuum flashover voltages

Abstract The augmentation of the epoxy (EP) resin surface to advance flashover performance has become a pivotal point of global interest. This research introduces a novel surface modification method and its mechanism for insulation materials. The research follows an electron cyclotron resonance ion implantation system to subject the surface of EP insulation to ion beams with diverse energies, i.e., 6, 10, 20, 40, 50, and 60 keV for a consistent time of 300 s at an angle of 90°. The experimental phase includes the DC flashover examination under negative polarity. Besides, the simulation phase includes the Monte Carlo model constructed using SRIM software to examine the range and distribution of bombarded ions in the targeted insulation. Results reveal that the flashover properties are affected by the surface potential, surface conductivity, trap distribution, water contact angle, and elemental composition. Likewise, based on the outcomes and theoretical point of view, it is revealed that the bombardment of energetic ions enhances the trap depth, assisting in a reduction in surface conductivity, confining the surface charge movements, and extensively suppressing the secondary electron emission yield. Also, the enhanced trap depth induces homo-charge formation near triple junctions. Synergistically, the factors contribute to high flashover voltages.