Search Results (1,215)

Background and Objectives: Currently, the development of local drug delivery systems for the treatment of cancer patients is a pressing issue. Such systems allow for the targeted delivery of anticancer drugs directly to the tumor site, ensuring prolonged drug release or reducing the risk of recurrence after tumor removal, minimizing the impact on healthy tissues and thereby reducing the overall toxic load on the body. This work is devoted to evaluating the prospects of using scaffolds based on low-modulus titanium Ti-15Mo alloy with a biomimetic coating as a platform for the local administration of the cytostatic drug cisplatin into the patient’s body. Methods: Porous coatings were obtained by plasma electrolytic oxidation in an aqueous solution of sodium phosphate and calcium acetate with the addition of various components. The influence of coating parameters on the corrosion resistance of samples and on the antiproliferative effect of cisplatin-loaded scaffolds was evaluated. Human K562 hemoblastosis, HT116 intestinal cancer, and SKOV3 ovarian cancer cell lines were used as cell models. Results: It was shown that the addition of sodium phosphate (the PS type electrolyte) provides the formation of a coating with a developed system of interconnected pores characterized by an attractive combination of parameters: high porosity (17%), high pore size (3.9 μm), and considerable thickness (17.4 μm). This coating demonstrated the best corrosion resistance in a Ringer solution as compared to the other tested states. In addition, the PS coating loaded with cisplatin exhibited a pronounced cytotoxic effect on cancer cells. This effect was attributed to its ability to fix cisplatin on the surface, which slows down its release into the extracellular environment, increasing the time of its action, thereby contributing to a more effective (by more than 3 times) suppression of tumor cell proliferation compared to the action of the standard form of the drug in the form of a solution when changing the growth medium and subsequent incubation for 48 h. Conclusions: PS scaffolds made of low-modulus titanium alloy Ti-15Mo with a biomimetic surface in an electrolyte based on an aqueous solution of sodium phosphate and calcium acetate with the addition of sodium silicate can be used as an advanced platform for the local delivery of the cytostatic drug cisplatin, which makes them promising for application in orthopedic oncology. Full article

This study investigates the hydrodynamic characteristics and pollutant transport in vegetated seepage channels, with a particular focus on the impacts of seepage and vegetation density on flow velocity and pollutant dispersion. The primary innovation of this research lies in the novel integration of the Lattice Boltzmann Method (LBM) and the Random Displacement Method (RDM) to establish a numerical model for simulating vertical flow velocity and pollutant transport in such channels. To enhance simulation accuracy, the sediment bed was treated as a porous medium. The findings reveal that higher seepage rates significantly increase pollutant infiltration, and denser vegetation further amplifies this effect by enhancing turbulent diffusion and mechanical dispersion within the vegetated zone. These insights are critical for sustainable groundwater protection and the design of vegetated buffer zones in river management. Furthermore, treating the sediment layer as a porous medium yielded more accurate flow velocity predictions. These results provide new insights into the complex interactions between seepage, vegetation, and pollutant transport, and offer a valuable theoretical basis for optimizing sustainable vegetation planting schemes and management practices in vegetated seepage rivers to protect groundwater quality. Full article

This research investigates the impact of wood-based biochar on the engineering properties of medium plasticity clay obtained from Perryville, Maryland. The clay was amended with biochar at volumetric contents of 3%, 6%, 9%, 12%, and 15% and subjected to a comprehensive suite of index and classification, compression, and shear strength laboratory tests. Results indicate that increasing biochar content leads to higher liquid limits and plasticity indices, a decrease in dry unit weight, and a higher optimum moisture content. Compression tests revealed increased compressibility and final void ratio with higher biochar content, likely due to biochar’s porous structure. Direct shear tests showed consistent improvements in shear strength parameters, including increases in both the internal friction angle and cohesion. Unconfined compression tests also demonstrated higher strength and ductility in biochar-amended samples. These findings support the potential of wood-based biochar as a sustainable and effective soil amendment for improving the geotechnical performance of clayey soils. Full article

Yttria-stabilized zirconia (YSZ) has attracted attention as a ceramic implant material owing to its excellent mechanical strength, biocompatibility, and aesthetic properties. However, YSZ is bioinert and lacks the ability to directly bond with bone. This study aims to enhance the bioactivity of 3D-printed porous YSZ through modified simulated body fluid (m-SBF) pretreatments. The porous YSZ substrates fabricated by fused deposition modeling were first etched with hydrofluoric acid (HF) to increase the surface roughness, followed by immersion in CO₃²⁻, Mg²⁺, and/or Zn²⁺ ion-incorporated m-SBFs. Among the tested solutions, the apatite coating formed in Mg²⁺- and Zn²⁺-containing m-SBF within one day, exhibiting uniform precipitation and a reduced tetragonal-to-monoclinic (t→m) transition. The incorporated Mg²⁺ and Zn²⁺ ions were successfully detected on the apatite coating, with Mg/Ca and Zn/Ca ratios of approximately 4.82% and 3.33%, respectively. Mg²⁺ is known to stimulate osteogenesis, while Zn²⁺ exhibits antibacterial activity. Furthermore, compared with standard SBF under high-temperature and high-pH conditions, the m-SBF induced markedly less t→m phase transition on YSZ substrates, suggesting that m-SBF, as a biomimetic medium for imparting bioactivity, provides a more suitable environment for YSZ substrates. This study demonstrates that HF surface treatment combined with Mg²⁺- and Zn²⁺-containing m-SBF pretreatment effectively imparts bioactivity to 3D-printed YSZ, offering a promising approach for next-generation osteoconductive ceramic implants. Full article

The purpose of this study is to develop a multiphysical model of agglomeration of low-grade phosphorites with the addition of phosphate-siliceous shales and oil sludge. To achieve these tasks, a numerical approach was used in the COMSOL Multiphysics environment, based on solving the related problems of heat transfer and hydrodynamics during heat treatment of the material. A laboratory vertical tubular furnace made of heat-resistant quartz glass with electric heating was used to study the effect of the temperature field and the velocity of gases on the degree of sintering and the dynamics of phosphorous agglomerate formation under various technological conditions. It has been established that the optimal temperature for the agglomeration process is a layer temperature of 950–1000 °C at a gas flow rate of 1.5–2 m/s, which ensures the formation of durable granules and minimizes sintering heterogeneity. The maximum sintering layer height of the test charge reaches 210–230 mm at pressures of 0.015–0.027 MPa. A comparison of the numerical simulation results with experimental data showed a good agreement, which confirms the practical significance of the proposed model for the design and optimization of industrial processes of agglomeration of phosphorous raw materials. Modern physical and chemical analyses have established the phase, microstructural, and element-by-element characteristics of the studied phosphate-siliceous shale and the product of agglomeration firing. The results of modeling the hydrodynamics of the charge agglomeration process can be recommended to increase the efficiency of processing phosphate-containing waste and reduce energy consumption. Full article

Titanium alloys are widely used in orthopedic and dental implants, yet their limited bioactivity and bacterial resistance remain critical challenges. This study aimed to enhance the surface performance of a Ti-13Zr-13Nb alloy through the formation of a porous oxide layer and the application of a bioactive, drug-loaded coating. Porous oxide layers composed of Ti, Zr, and Nb oxides with fluoride incorporation were fabricated using a novel anodizing process. The fluoride-assisted electrochemical mechanism controlling oxide growth was elucidated through SEM and EDS analyses. The anodized surface exhibited reduced microhardness, beneficial for minimizing stress-shielding effects. Subsequently, chitosan–tetracycline composite coatings were produced via EPD and compared with dip-coating method. Characterization by ATR-FTIR, optical microscopy, SEM, and UV-VIS spectroscopy confirmed the formation of uniform, adherent, and moderately porous coatings with sustained drug release when produced by EPD, while dip-coated layers were less homogeneous and released the drug faster. Microhardness testing revealed improved mechanical integrity of EPD coatings. The developed chitosan–tetracycline–oxide layer system provides tunable nano/microgram-scale drug release and enhanced surface functionality, offering promising perspectives for acute and medium-term regenerative and antibacterial biomedical applications. Full article

This study examines the stability and instability of a Casson fluid in a horizontal porous medium with magnetic effect using linear and global theories. Both linear and nonlinear analyses are conducted using the normal modes. The study proves that the linear and nonlinear stability thresholds coincide. Two different methodologies were used to solve the system of equations. The eigenvalue problem for linear and global theories were solved using a Galerkin scheme and bvp4c routine in MATLAB. The results show that the Casson parameter destabilizes the flow, while the solutal Rayleigh number and Darcy number stabilize it. Full article

At present, most oilfields in China have entered the late, high-water-cut stage, commonly facing declining single-well productivity and increasingly pronounced reservoir heterogeneity. Prolonged waterflooding has further exacerbated permeability contrast, yielding complex, hard-to-produce residual-oil distributions. Accordingly, the development of efficient enhanced oil recovery (EOR) technologies has become a strategic priority and an urgent research focus in oil and gas field development. Weak gels, typical non-Newtonian fluids, exhibit both viscous and elastic responses, and their distinctive rheology shows broad application potential for crude oil extraction in porous media. Targeting medium–high-permeability reservoirs with high water cut, this study optimized and evaluated a weak gel system. Experimental results demonstrate that the optimized weak gel system achieves remarkable oil displacement performance. The one-dimensional dual-sandpack flooding tests yielded a total recovery of 72.26%, with the weak gel flooding stage contributing an incremental recovery of 14.52%. In the physical three-dimensional model experiments, the total recovery reached 46.12%, of which the weak gel flooding phase accounted for 16.36%. Through one-dimensional sandpack flow experiments and three-dimensional physical model simulations, the oil displacement mechanisms and synergistic effects of the optimized system in heterogeneous reservoirs were systematically elucidated from macro to micro scales. The optimized system demonstrates integrated synergistic performance during flooding, effectively combining mobility control, displacement, and oil-washing mechanisms. Macroscopically, it effectively strips residual oil in high-permeability zones via viscosity enhancement and viscoelastic effects, efficiently blocks high-permeability channels, diverts flow to medium-permeability regions, and enhances macroscopic sweep efficiency. Microscopically, it mobilizes residual oil via normal stress action and a filamentous transport mechanism, improving oil-washing efficiency and increasing ultimate oil recovery. This study demonstrates the technical feasibility and practical effectiveness of the optimized weak gel system for enhancing oil recovery in heterogeneous reservoirs, providing critical technical support for the efficient development of medium–high-permeability reservoirs with high water cut. Full article

This scientific research examines the intricate dynamics of Maxwell nanofluid flow across a stretching surface with Stefan blowing impacts, with a particular focus on maritime thermal management applications. The analysis integrates multiple physical phenomena including magnetohydrodynamic forces, the energy dissipation phenomenon, and thermal density variations within Darcy porous media. Special attention is given to Stefan blowing’s role in modifying thermal and mass transfer boundary layers. We derive an enhanced mathematical formulation that couples Maxwell fluid properties with nanoparticle transport under combined magnetic and density-gradient conditions. Computational results demonstrate the crucial influence of viscous heating and blowing intensity on thermal performance, with direct implications for naval cooling applications. The reduced governing equations form a nonlinear system that requires robust numerical treatment. We implemented the shooting technique to solve this system, verifying its precision through systematic comparison with established benchmark solutions. The close correspondence between results confirms both the method’s reliability and our implementation’s accuracy. The primary results of this study indicate that raising the Stefan blowing and density parameters causes notable changes in the temperature and concentration fields. The Stefan blowing parameter enhances both temperature and concentration near the wall by affecting thermal diffusion and nanoparticle distribution. In contrast, the density parameter reduces these values because of increased fluid resistance. Full article

This study presents the development of a robust numerical model for simulating underground hydrogen storage (UHS) in salt caverns, with a particular focus on the interactions between original gas-methane (CH₄) and injected gas represented by hydrogen (H₂). Using the Schlumberger Eclipse 300 compositional reservoir simulator, the cavern was modelled as a highly permeable porous medium to accurately represent gas flow dynamics. Two principal mixing mechanisms were investigated: physical dispersion, modelled by numerical dispersion, and molecular diffusion. Multiple cavern configurations and a range of dispersion–diffusion coefficients were assessed. The results indicate that physical dispersion is the primary factor affecting hydrogen purity during storage cycles, while molecular diffusion becomes more significant during long-term gas storage. Gas mixing was shown to directly impact the calorific value and quality of withdrawn hydrogen. This work demonstrates the effectiveness of commercial reservoir simulators for UHS analysis and proposes a methodological framework for evaluating hydrogen purity in salt cavern storage operations. Full article

Manufactured nanoparticles are used in many consumer products and industries, and are known to enter our waste streams. Transport of nanoparticles in porous media has been studied extensively; however, the forces governing the interactions between nanoparticles and naturally porous media surfaces are still not fully understood. To examine the retention mechanisms and forces involved in nanoparticle transport, miscible–miscible transport experiments were performed and followed by force profile measurements by Atomic Force Microscopy (AFM). TiO₂ nanoparticles were used as the model nanoparticle, with silica sand as the model natural porous medium. Solution chemistries were varied from pH 4.5 (favorable attachment) to 8 (unfavorable attachment), and at 0.0015–30 mM ionic strength. Detachment transport experiments were performed for the unfavorable attachment conditions to determine if secondary minima attachment was present. DLVO calculations were performed to evaluate their predictive ability for force profiles under the experimental conditions. Mass recoveries for the transport experiments ranged from 28% to 80%, indicating significant attachment. Detachment was observed, indicating the presence of secondary minima. The magnitudes of attachment measured for the transport experiments were generally consistent with the results of the AFM measurements. In addition, the detachment observed at the highest pH was also consistent with the predictions, indicating the presence of secondary minima. DLVO theory underestimated the magnitudes of the attractive and repulsive forces measured by AFM but was able to qualitatively represent behavior observed at the lower two pHs. In contrast, it provided a poor representation of behavior at the highest pH. The integrated AFM measurements and miscible–displacement experiments employed in this study have provided insight into the retention of TiO₂, with implications for other nanoparticles during transport in porous media. Full article

This study examined the impact of fluid type and grain diameter on the interfacial area between different pairs of non-wetting and wetting fluids in natural porous media. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of multi-phase porous media systems. Multiple porous media, comprising a range of physical and geochemical properties, were used in this study. The four pairs of non-wetting/wetting fluids used were dense OIL/water, light OIL/water, air/dense OIL, and air/water. Images were obtained over a broad range of wetting phase saturation and for both wetting phase drainage and imbibition conditions. The results showed that for each fluid pair, the total (capillary + film) interfacial area increased with decreasing wetting fluid saturation. Interfacial areas were similar among all fluid pairs for a given porous medium. They were also similar for drainage and imbibition conditions. The maximum specific interfacial area (A_m) was shown to correlate well with inverse median grain diameter. The physical properties of the porous medium appear to have a greater influence on the magnitude of specific total interfacial area for a given saturation than fluid properties or wetting phase history. Full article

In order to guarantee energy sustainability, effective thermal energy storage (TES) systems are required due to the volatile nature of renewable energy sources. In order to optimize energy storage capacity and reduce thermal losses, this study addresses a hybrid TES system that combines basalt rocks and silica sand. Using ANSYS, a computational transient thermal analysis was conducted to compare conduction and convection heat transfer modes, revealing convection as the more effective mechanism. Six sand–rock mixtures were tested experimentally; the 70% sand and 30% rock combination produced the highest temperature increase (52.38 °C), the highest heat storage capacity (3.21 ± 0.19 MJ), alongside an efficiency of 80.5%. This hybrid system had a very low discharge rate (0.24 ± 0.036 MJ lost in one hour), outlining its potential for integration with renewable energy. The results show that hybrid sand–rock TES systems are a cheap and green alternative to solutions that rely on fossil fuels. They can be used for large-scale energy storage. Full article

This study examined the diffusion of nutrients (NH₄⁺, NO₃⁻, and PO₄³⁻) in the pore water of intertidal sediments in Lake Komuke (located in the northeastern part of Hokkaido on the coast of Okhotsk Sea) across nine stations, at 0 cm to 40 cm depths, from 19 May to 23 August 2015. A comparison was made between the traditional version of Fick’s first law and a modified version to understand nutrient diffusion in the intertidal flat. The novelty of this study lies in establishing a flux correction factor as a function of the activity coefficient in intertidal sediments. The outcomes of the standard and modified versions of Fick’s law exhibited observable physical differences between stations for all nutrients. However, the statistical analysis demonstrated significant differences only for NO₃⁻ and PO₄³⁻ at stations D, E, and F, suggesting that there is no statistically meaningful difference in NH₄⁺ flux. A statistical comparison of 27 pairs of fluxes obtained by the classical and modified versions of Fick’s first law indicated that 88.9% of the differences were not statistically significant between the two methods, and 11.1% were statistically significant. This shows the consistency of the modified method, firstly in reproducing the classical version of Fick’s law, and secondly in improving upon it, in a porous medium. These findings indicate that the modified version of Fick’s first law is an accurate methodology for evaluating nutrient diffusion dynamics in intertidal environments, and is potentially applicable to coastal salt marshes, with practical implications for environmental management and conservation efforts. Full article

Magnetohydrodynamic (MHD) flow and heat transfer in porous media are central to many engineering applications, including heat exchangers, MHD generators, and polymer processing. This study examines the boundary layer flow and thermal behavior of an electrically conducting viscous fluid over a porous stretching tube. The model accounts for nonlinear thermal radiation, internal heat generation/absorption, and Darcy–Forchheimer drag to capture porous medium resistance. Similarity transformations reduce the governing equations to a system of coupled nonlinear ordinary differential equations, which are solved numerically using the BVP4C technique with Response Surface Methodology (RSM) and sensitivity analysis. The effects of dimensionless parameters magnetic field strength (M), Reynolds number (Re), Darcy–Forchheimer parameter (Df), Brinkman number (Br), Prandtl number (Pr), nonlinear radiation parameter (Rd), wall-to-ambient temperature ratio (rw), and heat source/sink parameter (Q) are investigated. Results show that increasing M, Df, and Q suppresses velocity and enhances temperature due to Lorentz and porous drag effects. Higher Re raises pressure but reduces near-wall velocity, while rw, Rd, and internal heating intensify thermal layers. The entropy generation analysis highlights the competing roles of viscous, magnetic, and thermal irreversibility, while the Bejan number trends distinctly indicate which mechanism dominates under different parameter conditions. The RSM findings highlight that rw and Rd consistently reduce the Nusselt number (Nu), lowering thermal efficiency. These results provide practical guidance for optimizing energy efficiency and thermal management in MHD and porous media-based systems.: Full article