Particle Contact Research Articles

Experimental study and model prediction of the influence of different factors on the mechanical properties of saline clay

Water conveyance channels in cold and arid regions pass through several saline-alkali soil areas. Canal water leakage exacerbates the salt expansion traits of such soil, damaging canal slope lining structures. To investigate the mechanical properties of saline clay, this study conducted indoor tests, including direct shear, compression, and permeation tests, and scanning electron microscopy (SEM) analysis of soil samples from typical sites. This study aims to elucidate the impact of various factors on the mechanical properties of saline clay from a macro–micro perspective and reveal its physical mechanisms. A prediction model is formulated and validated. The findings indicate the following: (1) Cohesion in direct shear tests has a linear negative correlation with water content and a positive correlation with dry density and initially decreases with increasing salt content until 2%, after which it increases. The internal friction angle initially increases and then decreases with increasing water content, reaching a peak at the optimal water content, and then gradually increases with dry density while initially decreasing, followed by an increase in salt content, stabilizing thereafter. Water content, dry density, or salt content chiefly affect cohesion by influencing electrostatic attraction, van der Waals forces, particle cementation, and valence bonds at particle contact points. (2) Compression tests reveal a linear positive correlation between the compression coefficient and water content, a negative correlation with dry density, and a stepwise linear correlation with salt content, peaking at 2%. The compression index decreases with increasing water content and dry density, following a trend similar to that of the compression coefficient with increasing salt content. The rebound index shows a linear negative correlation with water content and dry density, transitioning from a negative to a positive correlation at 2% salt content. Scanning electron microscopy analysis revealed particle flattening and increased aggregation with increasing consolidation pressure, reducing compressibility. Large pores and three-dimensional porosity have the greatest influence on soil compressibility. (3) Permeability tests reveal an exponential negative correlation between the permeability coefficient and dry density. As the dry density increases, the particle arrangement becomes denser, decreasing the pore quantity, with micropores disproportionately impacting the permeability coefficient. An increase in salinity initially increases the permeability coefficient before it decreases. The boundary point of the 2% salt content divides the effect of salt ions from promoting free water flow to blocking seepage channels, with the proportion of micropores being the primary influencing factor. (4) Employing statistical theory and machine learning algorithms, dry density, water content, and salinity are used to predict mechanical index values. The improved particle swarm optimization-support vector regression (PSO-SVR) model has high accuracy and general applicability. These findings offer insights for the construction and upkeep of open channel projects in arid regions.

Effect of different addition orders of petrochemical by-product-based mixed collectors on coal flotation

ABSTRACT An effective collector is crucial for enhancing coal flotation efficiency. The effect of a mixed collector based on petrochemical by-products on coal flotation was investigated. The investigation included various addition orders and was conducted using flotation tests, particle size distribution analysis, GC-MS, FTIR and contact angle measurements. The Mixed addition order exhibited superior performance in flotation compared to the K+Y and Y+K orders at all tested dosages. Particle size distribution analyses revealed that the mixed collector offered better dispersion in water than individual the Y-oil and K-oil, with droplet sizes below 100 µm. FTIR and contact angle measurements indicated that coal treated with the Mixed addition order demonstrated optimal reagent adsorption and the highest level of surface hydrophobicity. Aromatic compounds in the collector interacted with the hydrophobic areas of the coal surface, while partially covering some of the hydrophilic regions between these hydrophobic sites. Conversely, heteropolar components engaged with the hydrophilic regions on the coal surface to enhance adsorption. Despite these improvements, some hydrophilic sites remained after treatments with the Y+K and K+Y orders, which continued to affect the coal flotation properties.

Bayesian approach for probabilistic-based characterization of the shear stiffness–deflection curves of adhesive particle contacts

Bayesian approach for probabilistic-based characterization of the shear stiffness–deflection curves of adhesive particle contacts

Electrochemical-thermal-mechanical overcharge model on a scale of particle for lithium-ion batteries

During overcharging of lithium-ion batteries, lithium plating can occur on the anode surface when the maximum lithium intercalation concentration is exceeded, while the cathode is in a lithium-poor state, which can result in shortened battery lifespan and safety. In this work, the geometric structure of the positive electrode particles is designed based on the tomography data, while the negative electrode particles are represented by spheres with different sizes. The homogenization method is used, with the carbon filler, binder and electrolyte regarded as a single porous conductive adhesive domain. Based on the main mechanism of lithium-ion battery overcharge, a coupled three-dimensional electrochemical-mechanical-thermal overcharge model on a particle scale is developed for NCM cathode and graphite anode. The coupled mathematical model consists of four parts, namely the electrochemical model, the lithium plating model, the thermal model and the stress-strain model. In terms of lithium precipitation, the particle radius parameter and charging rates are investigated. The results show that the lithium plating concentration of the particles near the separator is higher, following the “principle of proximity” , namely the sequence of lithium deintercalation is related to the migration path. The surface of anode particles with small particle size is more prone to lithium precipitation due to the high maximum lithium ion concentration on the surface of the particles, the low surface lithium precipitation overpotential, and the high average Von Mises stress. At high charging rate, fast charge transfer rate and ion diffusion rate result in a low voltage at the anode, triggering off lithium precipitation. At a low rate, polarization and low temperature can lead to the precipitation of more lithium on the surface of the anode particles. In terms of stress, the spatial distribution between particles and thermal effects are investigated. The ratio of the distance from the contact surface to the center of the particle to the particle radius is calculated and defined as the contact depth (<inline-formula><tex-math id="M2">\begin{document}$Jr$\end{document}</tex-math></inline-formula>), in order to better describe the law of particle contact stress. It is shown that the contact depth between particles is inversely proportional to the stress on the contact area. When the heat generation effect is considered, the temperature of the battery rises faster with the increase of the charging rate. The electrochemical parameters related to temperature and the lithium concentration diffusion gradient increase significantly, and the influence of temperature on the particle stress is also more significant. The relevant results can provide theoretical basis and guidance for designing battery and optimizing charge strategies.

Optimización de los Procesos de Lixiviación para Maximizar la Adsorción de Oro en el Carbón Activado y Minimizar su Pérdida en los Relaves

Gold mining is a key economic activity worldwide, but its efficiency faces significant technical and environmental challenges. One of the key methods to improve gold recovery is adsorption by activated carbon, whose effectiveness can be influenced by factors such as particle size, contact time, ore grade and accumulation of unwanted compounds. This article compiles literature information on leaching and adsorption methods, highlighting the advantages and limitations of heap and tank processes. Heap leaching, although inexpensive and simple, has low recovery rates and environmental risks, while tank leaching offers greater control and efficiency, but involves higher costs. The methodology included the review of scientific articles published between 2019 and 2024, selecting relevant studies to optimize these processes and contribute to the development of more sustainable mining practices.

Quasi-conformal versus Hertz superposition: a comparison for two-dimensional contact

Hertz contact theory results in a relation between the normal contact force and the rigid indentation of the contact surfaces, the force is proportional to the indentation to the power of 3/2, and a semi-ellipsoidal traction distribution. It is a valid theory for non-conformal contact between smooth surfaces (curves in 2D) of elastic bodies. This force model can be derived by considering the Taylor polynomials of degree 2 at the contact point as approximations for the surfaces/curves. In the 2D case, it depends only on the curvature radii of the curves and is undefined when they are equal, the equality of radii violates the non-conformality.The Hertzian force is usually applied to the contact of solid particles as a model compensating for the small local deformations that occur in the contact region. We consider the 2D contact of a rigid convex particle with a rigid concavity enforcing the contact constraint with a barrier method, an approach that prevents overlapping of the bodies, resulting in a force that acts on the contact point. The geometries and the motion are specially designed to show the coalescence of two contact points into one. It illustrates two possible issues with convex-concave contact, the non-uniqueness of contact points and the conformality. We compare the results with a deformable finite element model for equivalent bodies and motion showing that there is a transition between a Hertzian and a non-Hertzian behavior. We conclude that a criterion for the conformality of curves must include the ever-present gap when a barrier method is used to enforce the constraint and the Hertzian force is not suitable for the coalescence of contact points.

Optimizing Backfill Materials for Ground Heat Exchangers: A Study on Recycled Concrete Aggregate and Fly Ash for Enhanced Thermal Conductivity.

This study investigates the potential use of recycled concrete aggregate (RCA), fly ash (FA), and their mixture (RCA+FA) as backfill materials for shallow vertical ground heat exchangers (GHEs). Granulometric, aerometric, and Proctor compaction tests were conducted to determine soil gradation, the void ratio, and the optimal moisture content (OMC) for maximum dry density. RCA demonstrated efficient compaction at lower moisture levels, while FA required higher moisture to reach maximum density. A 10% FA addition was optimized to fill voids in the RCA soil skeleton without compromising structural stability. Thermal conductivity tests were performed using a TP08 probe in both dry and wet states. The results showed that the RCA+FA mix exhibited a notable increase in thermal conductivity at around 6% moisture content due to the formation of water bridges between particle contacts. FA, in contrast, displayed a more linear relationship between conductivity and moisture. The RCA+FA mix achieved higher thermal conductivity than either material alone, particularly near full saturation, making it a promising option for efficient heat exchange. Thermal conductivity modeling, based on the Woodside and Messmer model, confirmed the RCA+FA mix's high conductivity and estimated full saturation conductivity values with a small error. The Kersten number (Ke) was employed to predict conductivity across varying moisture levels, with results showing a strong correlation with saturation ratio (Sr).

Effect of recycled concrete powder on the rheological properties of cement paste: New findings

Recycled concrete powder (RCP) influences cement paste's rheology, but the mechanisms remain unclear. This paper intends to fill this gap by employing a new method for measuring water absorption, the minimum water requirement method, an organic carbon analyser, and a laser particle size analyser. The cementitious material's water absorption (W), packing density (φm), water reducer adsorption (Qad), and particle size distribution are determined. Results show that, as the RCP's content increases from 0 % to 25 %, the cementitious material's W, φm, Qad, volume fraction, and average particle size increase by 21.7 %, 0.9 %, 26.2 %, 1.4 %, and 30.6 %, respectively. Consequently, the particle's surface covered by the water reducer (θ) and distance (H) decrease by 26.5 % and 32.6 %, respectively, resulting in an increase in the paste's yield stress (τ0) and plastic viscosity (ηpl) by 1946.6 % and 45.3 %, respectively. Based on an existing yield stress model, RCP affecting τ0 can be attributed to changes in the particle system's colloidal and contact interactions. A decrease in H increases colloidal interactions. Conversely, an increase in φm and a decrease in fine particle content reduce contact interactions. Colloidal interactions are more significant, thus τ0 increases. Based on the functional expression for the ηpl developed here, RCP affecting ηpl can be attributed to changes in hydrodynamic interactions and contact interactions. A decrease in H increases hydrodynamic interactions. An increase in φm combined with a decrease in fine particle content decrease contact interactions. Additionally, an increase in Qad reduces pore solution's viscosity. Hydrodynamic interactions are more significant, thus increasing ηpl.

Coatings Based on Single-Ion and Intrinsically Conducting Polymers for High-Voltage Cathode Materials

One of the main challenges presented by cathodic materials for lithium batteries is to ensure that capacity is maintained during cycling. The Ni-rich cathode LiNi0.8Mn0.1Co0.1O2 (NMC811) is considered a promising material due to its high energy density. However, this material presents a rapid decay in its capacity during the first charging and discharging cycles due to the direct contact of the NMC811 particles with the electrolyte. In this work, we have investigated the development and the effects on the electrochemical properties of a polymer coating based on a lithium single-ion conductor together with a conjugated polymer that prevents direct contact between the NMC811 particles and the electrolyte. These materials are used to create a homogeneous coating that acts as a channel for the transport of lithium only between the two interphases. It also serves as an electronic conductor that promotes good contact between the NMC811 particles, the carbon black, and the current collector. Furthermore, there are no reports on the use of single-ion conducting polymers as coatings for NMC materials, only reports on intrinsically conducting polymers to improve the electronic conductivity between cathodic components and capacity retention. In addition, these coatings act as an artificial cathode-electrolyte interphase to prevent unwanted reactions. X-ray photoelectron spectroscopy (XPS) was carried out to investigate the presence and evolution of these coating compounds during cycling. In addition, SEM and TEM were performed to observe the surface morphology of the particles and determine the thickness of the coating. Finally, electrochemical impedance spectroscopy (EIS) was used to evaluate the effects of the coating compounds on the charging and discharging processes as well as their stability during cycling. This study shows that the development of modulated coatings can provide an innovative approach to obtaining Ni-rich cathode materials with a longer lifespan for lithium batteries.L.M. Guerrero Mejía et al. manuscript in preparation.

(Invited) Overview of the Project Solid-Next “Evaluation of All-Solid-State Battery Materials and Foundational Technology Development for Next Generation”

Background: The rapid expansion of the electric vehicle (EV) market is anticipated due to the increasing adoption of EVs to achieve carbon neutrality by 2050. To gain the initiative in this market, it is crucial to realize and commercialize next-generation all-solid-state lithium-ion batteries (LIBs) that surpass the performance of conventional liquid LIBs. Project Objectives: The SOLiD-Next project aims to improve the performance of all-solid-state LIBs and promote the development of battery materials required for their realization. Specifically, we will focus on strengthening the fundamental research and development capability by further advancing material evaluation technologies and expanding evaluation guidelines. Development of Material Evaluation Platform Technologies We will develop evaluation platform technologies for next-generation all-solid-state LIB materials, including a standard battery model as a benchmark. By applying this platform, we can accurately evaluate the advantages and disadvantages of new materials and provide detailed feedback to the development process. This will accelerate material development and shorten the time to application. Elucidation of Phenomena and Mechanisms Unique to All-Solid-State LIBs We will focus on elucidating the mechanisms unique to all-solid-state LIBs, including particle contact, interfaces, and degradation, especially solid-solid interfaces. Based on the obtained knowledge, we will provide guidelines for electrode, cell, and element technologies and develop advanced analysis and characterization techniques for this purpose. Development of Electrode and Cell Element Technologies We will propose next-generation materials and develop electrode and cell element technologies that lead to performance improvements in all-solid-state LIBs by fully utilizing material properties and solving solid-solid interface challenges. The developed technologies will be applied to the development of the standard battery model. Acknowledgement: This work is based on the project of ‘Evaluation of All-Solid-State Battery Materials and Foundational Technology Development for Next Generation (SOLiD-Next, JPNP23005)’, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). Figure 1

Exploring the dynamic mechanical response and mesoscopic characteristics of typical frozen rock in Yulong Copper Mine

Dynamic mechanical characteristic testing at low temperatures was conducted for the typical porphyry and sandstone specimens of Yulong Copper Mine in Tibet, China. The stress and strain characteristics of the specimens at different temperatures were analyzed. A dynamic constitutive model was developed by considering the initial damage. Furthermore, microscopic damage characteristics during the water-saturated rock freezing process were investigated using the PFC3D software, revealing the mechanisms of frost heave damage to rocks. The results indicated that the water-ice phase transition either enhanced or deteriorated the specimen strength at low temperatures. Specifically, freezing at −10°C and −20°C enhanced the strength of sandstone. However, freezing at −10°C enhanced the porphyry specimens, and freezing at −20°C caused significant frost swelling injury. The new constitutive equation effectively fitted the dynamic stress and strain curves for both specimens, highlighting their differences. The maximum contact force and particle contact in the frozen rock PFC3D model were affected by rock and water particle deformations. The frost swelling deformation of water particles had a more pronounced impact on specimen damage and was related to the temperature. A specific freezing temperature existed at which the increase in saturated rock strength corresponded to the maximum specimen strength at that temperature.

Numerical Study of Cone Penetration Tests in Lunar Regolith for Strength Index

The cohesive properties of lunar regolith, combined with a low-gravity environment, result in it having a distinct mechanical behavior from sandy soil on Earth. Consequently, empirical formulas derived from cone penetration tests (CPTs) for calculating the shear strength parameters of Earth’s sand cannot be directly applied to lunar regolith. This study utilized the three-dimensional discrete element method (DEM) to numerically simulate triaxial shear tests and cone penetration tests in a lunar environment. The particle contact model for lunar regolith in the discrete element method (DEM) simulation incorporated the hysteresis effect of van der Waals forces, thereby simulating the cohesive properties of lunar regolith in a lunar environment. We proposed a relationship for calculating the shear strength index of lunar regolith based on normalized cone tip resistance using the results from triaxial and CPT simulations and referencing empirical formulas derived from ground-based CPT data. The results of this study provide a valuable reference for future lunar CPTs.

Modeling and Parameter Selection of the Corn Straw–Soil Composite Model Based on the DEM

During corn harvesting operations, machine–straw–soil contact often occurs, but there is a lack of research related to the role of straw–soil contact. Therefore, in this study, a composite contact model of corn straw‒soil particles was established based on the discrete element method (DEM). First, the discrete element Hertz‒Mindlin method with bonding particle contact was used to establish a numerical model of the double-bonded bimodal distribution of corn straw, and bonding particle models of the outer skin‒outer skin, inner pulp‒inner pulp, and outer skin‒inner pulp were developed. The nonhomogeneous and deformable material properties were accurately expressed. The straw compression test combined with simulation calibration was used to determine some of the bonding contact parameters by means of the PB (Plackett–Burman) test, the steepest ascent test, and the BB (Box–Behnken) test. Additionally, Additionally, the Hertz-Mindlin with JKR (Johnson-Kendall-Roberts) + bonding key model was used to establish the numerical model of the soil particles, which was used to describe the irregularity and adhesion properties of the soil particles. The geometric model of the soil particles was established using the multisphere filling method. Finally, a composite contact model of corn straw‒soil particles was established, the contact parameters between straw and soil were calibrated via collision tests, inclined tests and inclined rolling tests, and the established composite contact model was further verified through direct shear tests between straw and soil. A theoretical foundation for the optimal design of equipment linked to maize harvesting is provided by this work.

Suppression of Metal Particles by Coating for a ±550 kV DC GIS

Coating the inner surface of grounded enclosures has been used to inhibit metal particle motion inside AC GIS for many years. However, for DC GIS, only fundamental research has been performed, while very few attempts have been made on real DC GIS. This paper reviews the basic research into the inhibition of metal particles by coating at DC. On this basis, based on a ±550 kV DC GIS busbar, an inhibition test of metal particle motion using coating was performed. Four types of metal particles were used as samples to verify the inhibitory effect of the grounded enclosure coating. The results showed that the coating has a very good inhibitory effect on block and powder metal particles on real GIS, and there are rarely any metal particles moving again under the rated DC voltage. However, for wire and flake metal particles, the effectiveness of the coating depends on the way the particle contacts the ground electrode when they are still, and ~30% of wire and flake metal particles can be inhibited. The conclusion of this paper is of guiding significance for the research and development of stable and reliable DC gas-insulated equipment.

Compaction behavior of coarse-grained soil under various vibration frequencies: a DEM study

PurposeThis paper investigates the vibration compaction mechanism and evaluates the impact of vibration frequencies on the stability of coarse-grained soil, aiming to optimize the subgrade filling process.Design/methodology/approachThis study examines the vibratory compaction behavior of coarse-grained soils through indoor vibration tests and discrete element simulations. Focusing on angular gravel (breccias) of varying sizes, the simulations were calibrated using parameters such as Young’s modulus, restitution and friction coefficients. The analysis highlights how particle shape influences compaction, revealing mesoscopic mechanisms that drive macroscopic compaction outcomes.FindingsThis study investigates the influence of vibration frequency on the compaction behavior of coarse-grained soils using discrete element simulation. By analyzing particle contact and motion, the mesoscopic mechanisms driving compaction are explored. The study establishes a positive linear correlation between contact force anisotropy (Cv) and deformation, demonstrating that higher anisotropy leads to greater structural disruption. Additionally, the increase in sliding contact percentage (SCP) at higher frequencies indicates instability in the skeletal structure, driven by uneven contact force distribution. These findings reveal how frequency-induced stress concentration affects the stability and deformation of the soil skeleton.Originality/valueThis research explores the effect of various vibration frequencies on the compaction behavior of coarse-grained soils, examining microscopic interactions to reveal their impact on soil stability and deformation.

Analytical generalized thermal resistance model for conductive heat transfer in pebble beds based on heat flux weighted temperature difference

A novel model for inter-particle contact thermal resistance based on analytical solutions is proposed. By applying the concept of heat flux weighted temperature difference in thermal resistance modeling for the first time, this model offers greater physical significance than traditional thermal resistance models. It effectively describes the dissipation in the heat transfer process and the influence of particle radius on thermal resistance, making it a generalized thermal resistance model suitable for multi-dimensional systems. The impact of applying different levels of uniform heat flux boundary conditions on thermal resistance is analyzed from the perspective of energy dissipation, revealing that a more uniform heat flux input results in lower thermal resistance. The effects of contact radius and particle size on the dimensionless generalized thermal resistance of inter-particle contact were studied, showing that the dimensionless resistance increases with larger particle contact radius and smaller particle size. Using the thermal discrete element method, the thermal resistance model with uniform heat flux density boundary conditions was applied to calculate the effective thermal conductivity of the pebble bed. Considering the distribution of contact radius, differences in effective thermal conductivity at various heights of the pebble bed due to different contact radii were examined and compared with the traditional fixed-coefficient contact resistance model. It was found that the difference between the two models decreases as the contact radius decreases. Finally, multiple sets of fixed contact radii were established under three different particle sizes, revealing that as the contact radius increases, the deviation between the new generalized resistance model and the traditional fixed-coefficient model rises from 8.18 % to 14.64 % for different particle radii.

Research on adhesion properties of tidal flat soil on metal surface and discrete element simulation

The adhesion property of soil on the metal surface was tested by the orthogonal experiment with 4 factors and 3 levels based on piston pull out method. A regression model of adhesion stress and the factors including moisture content(X1), pressing time(X2), settling time(X3) and separation velocity (X4) was established. The experiment results show that the influence of each factor on adhesion stress is ranked as X1≈X2≈X3>X4>X3X4, and the adhesion stress shows an ‘S’ curve with the increase of separation velocity. The DEM parameters of the soil were calibrated based on the test results, and the contact and disturbance state of soil particles during the test were studied by discrete element method (DEM) using JKR model. The simulation tests show that the maximum adhesion stress occurs when the particles are about to separate from the probe surface, and the soil disturbance state is hierarchical.

Research on coal rock parameter calibration based on discrete element method

To ensure that the discrete element model of the coal wall accurately reflects the actual cutting process of coal and rock during virtual prototype simulation of mining equipment, this study aims to expedite the development of intelligent mining machinery. Using coal samples from the 4602 working face of Yangcun Coal Mine, operated by Yanzhou Coal Mining Group, we conducted coal rock packing experiments and uniaxial compression tests to obtain the packing angle and compressive strength of the coal samples. Based on the experimental results, we designed Plackett–Burman experiments (PB experiments), steepest ascent experiments, and Box-Behnken experiments to study the influence of particle contact mechanics parameters and bonding mechanics parameters on the packing angle and compressive strength, using the packing angle and compressive strength as response variables. Our objective is to minimize the relative error between the simulated packing angle and the measured packing angle. We solved and optimized the parameter calibration model and conducted simulation calibration experiments based on the optimization results. A comparative analysis with the actual test results revealed that the maximum relative errors between the simulated and measured values for the packing angle and compressive strength were only 2.9% and 5.0%, respectively. Additionally, a discrete element model of a typical working face coal wall was established based on the parameters obtained from this calibration method. A bidirectional coupling model of the cutting process between the coal and rock was created using EDEM-RecurDyn to simulate the rigid-flexible coupling of the coal cutter. An experimental coal wall model was constructed based on similarity theory, and both simulation and physical experiments were conducted. The evaluation metrics for comparison were the time-domain and frequency-domain characteristics of the drum’s vibration signals. The maximum relative error for the time-domain signal characteristics between the two experimental setups was only 4.19%, while the maximum relative error for the frequency-domain signal characteristics was 3.75%. This validates the feasibility of the proposed calibration method for the discrete element coal wall model and the accuracy of the calibration results. Furthermore, it demonstrates that the constructed discrete element coal wall accurately represents the actual coal and rock properties. The virtual simulation based on this model effectively replicates the interaction process between mining machinery and coal, providing a safe, efficient, and low-cost technological approach for performance analysis of mining equipment and intelligent control of supporting devices.

Hypothesizing the Oleic Acid-Mediated Enhanced and Sustained Transdermal Codelivery of Pregabalin and Diclofenac Adhesive Nanogel: A Proof of Concept.

Pregabalin (PG) and diclofenac diethylamine (DEE) are anti-inflammatory molecules that are effective in relieving inflammation and pain associated with musculoskeletal disorders, arthritis, and post-traumatic pain, among others. Intravenous and oral delivery of these two molecules has their limitations. However, the transdermal route is believed to be an alternate viable option for the delivery of therapeutic molecules with desired physicochemical properties. To this end, it is vital to understand the physicochemical properties of these drugs, dosage, and strategies to enhance permeation, thereby surmounting the associated constraints and concurrently attaining a sustained release of these therapeutic molecules when administered in combination. The present work hypothesizes the enhanced permeation and sustained release of pregabalin and diclofenac diethylamine across the skin, entrapped in the adhesive nano-organogel formulation, including permeation enhancers. The solubility studies of pregabalin and diclofenac diethylamine in combination were performed in different permeation enhancers. Oleic acid was optimized as the best permeation enhancer based on in vitro studies. Pluronic organogel containing pregabalin and diclofenac diethylamine with oleic acid was fabricated. Duro-Tak® (87-2196) was added to the organogel formulation as a pressure-sensitive adhesive to sustain the release profile of these two therapeutic molecules. The adhesive organogel was characterized for particle size, scanning electron microscopy, and contact angle measurement. The HPLC method developed for the quantification of the dual drug showed a retention time of 3.84 minutes and 9.69 minutes for pregabalin and diclofenac, respectively. The fabricated nanogel adhesive formulation showed the desired results with particle size and contact angle of 282 ± 57 nm and ≥120⁰, respectively. In vitro studies showed the percentage cumulative release of 24.90 ± 4.65% and 33.29 ± 4.81% for pregabalin and diclofenac, respectively. In order to accomplish transdermal permeation, the suggested hypothesis of fabricating PG and DEE nano-organogel in combination with permeation enhancers will be a viable drug delivery method. In comparison to a traditional gel formulation, oleic acid as a permeation enhancer increased the penetration of both PG and DEE from the organogel formulation. Notably, the studies showed that the use of pressure-sensitive adhesives enabled the sustained release of both PG and DEE.Therefore, the results anticipated the hypothesis that the transdermal delivery of adhesive PG and DEEbased nanogel across the human skin can be achieved to inhibit inflammation and pain.

Study on offshore sandstone reservoir classification method based on cuttings digitization technology

Abstract Reservoir classification research is of great significance for improving the accuracy of oil and gas exploration and development, reducing risks, and enhancing economic benefits. Traditional reservoir classification methods are primarily based on macroscopic geology and core analysis, lacking descriptions of reservoir pore structure characteristics and microscopic geological features, with very limited data dimensions obtained. This study uses sandstone cuttings samples from a well in an offshore sandstone reservoir as an example and employs digital core technology to conduct reservoir classification research. First, high-resolution micro-CT scanning was performed, and the microscopic lithological characteristics of different blocks were observed based on the scanned images. The diagenesis and particle contact relationships were qualitatively analyzed. Next, digital methods were used to quantitatively analyze pore structure characteristic parameters such as porosity, permeability, and connectivity. Then, the qualitative analysis results of the images were combined with the quantitative analysis results of the digital cuttings to form a set of classification evaluation standards for a certain sandstone reservoir in the eastern South China Sea. Finally, based on the characteristic parameters obtained from the digital quantitative analysis of the cuttings and the on-site pressure-flow data, a big data analysis method was used to screen out the reservoir characteristic parameters with high correlation, providing data support for the rapid evaluation of reservoir mobility. The reservoir classification evaluation standards and flow prediction models formed in this study can provide technical support for accurately formulating reservoir development plans in oil fields in the eastern South China Sea and have significant reference value for the fine evaluation of similar reservoirs. In addition, reservoir classification methods based on digital core analysis exhibit efficiency and multidimensionality, which are crucial for well placement selection, wellbore design, stability assessment of well walls during drilling, interpretation of logging data, and accurate prediction of production capacity.