Search Results (68)

A technological approach to the formation of a 3D nanocomposition material based on hierarchical porous nickel oxide nanoparticles incorporated into porous silicon with a dendritic porous structure is proposed. Porous silicon was used as a 3D porous template, in the presence of which porous hierarchical nickel oxide nanoparticles were synthesized using a “green” synthesis method followed by annealing in an oxygen-containing atmosphere. The resulting materials were characterized using scanning electron microscopy, transmission electron microscopy, X-ray spectral microanalysis, X-ray diffraction, and the BET method. The potential of a developed composition based on porous hierarchical nickel and silicon oxide nanoparticles to enhance the sensitivity of adsorption gas sensors was assessed using impedance spectroscopy in the presence of a probe gas (isopropanol). Gas sensitivity measurements were conducted at room and elevated temperatures in the frequency range from 100 Hz to 500 kHz. Differences in the dependences of the real part of impedance on the imaginary part were revealed for the porNiO-porSi composition in Nyquist coordinates. The results are discussed in terms of percolation theory and fractal organization. Full article

There is a growing demand for extreme miniaturization and enhanced sensitivity in next-generation sensing systems, including wearable devices and bioelectronics. Such advanced platforms require highly conductive, biocompatible, and mechanically robust architectures capable of conforming to dynamic surfaces. Conventional metallic thin-film fabrication techniques have reached their fundamental physicochemical limits, often suffering from suboptimal mechanical strength, complex multi-step processing, and high costs. In contrast, additive manufacturing methodologies offer streamlined microfabrication, yet traditional printing methods frequently struggle with low-viscosity constraints, insufficient metal loading, and significant material losses. This paper covers the morphological fidelity, mechanical resilience, and electrical performance of rheologically tailored, high-concentration (above 90%) gold nanoparticle paste deposited via Ultra-Precise Dispensing (UPD) technology. The capability of the UPD system to print complex, high-density fractal geometries with linewidths down to 5 μm is evaluated on both rigid and flexible substrates, glass and polyimide, respectively. The mechanical structural integrity of these conductive traces is characterized under initial 360-degree bending tests. Finally, the electrical stability and thermal response of a printed proof-of-concept temperature sensor are evaluated. The printed fractal microstructures exhibit good resolution and the fabricated sensor demonstrates good stability, displaying a linear thermal response with a temperature coefficient of resistance of 1.98·10⁻³ °C⁻¹, validating this combined material-deposition approach for microelectronics. Full article

The temporal dynamics and statistical properties of air nanobubbles (NBs) in ultrapure water were investigated using nanoparticle tracking analysis (NTA). Statistical analysis of NB lifetimes reveals a strong correlation between bubble size and persistence. The mean bubble diameter increases rapidly from ~100 nm for short-lived detections to a characteristic size of about 500 nm for bubbles surviving longer than 40 frames, after which the size remains approximately constant. The population of detected NBs decreases monotonically with increasing lifetime, approximately following an exponential decay. Temporal analysis of the cumulative population yields a scaling exponent of ~0.6, indicating correlated fluctuations rather than independent stochastic events. Spatial observations confirm that NBs are separated by micrometer-scale distances, excluding direct bubble–bubble interactions. The combined statistical and imaging results support a picture in which NBs behave as dynamically coupled gas domains embedded within localized dissolved-gas microenvironments. The observed non-monotonic population dynamics cannot be explained by irreversible dissolution alone. Instead, the data indicate that NBs undergo continuous cycles of dissolution and replenishment. Within this framework, localized gas micro-domains, potentially exhibiting non-extensive behaviour, evolve dynamically and act as transient reservoirs. Upon bubble disappearance, these regions persist and diffuse, while their interaction may locally restore conditions for nucleation. This mechanism provides a physically consistent explanation for the observed cyclic behaviour and the apparent persistence of NBs beyond classical predictions. Full article

In this article, we present a new approximate solution for blood nanofluid having gold nanoparticles as it flows near a stretching porous cylinder in fractal space. A Casson non-Newtonian magneto-bio-nanofluid flowing through a porous medium is considered a potential application in chemotherapy for eradicating cancer cells. Without the need for the nonperturbative approach, the proposed solution uses an alternative approach to dealing with nonlinear problems. This approach transforms the nonlinear cubic jerk model resulting from the simplification of the governing fractional partial differential equations into an equivalent linear formula. This approach is known as highly efficient linear approximation (HELA) or non-perturbation technique (NPT), and this represents a significant advancement over traditional perturbation methods in the analysis of non-linear systems. As a robust mathematical approach, it excels at handling a wide range of coefficient values, particularly in cases of clear nonlinearity. This study also utilized the masking technique simultaneously with HELA, which played a crucial role, as they simplify the complex dynamics of the system, making it more amenable to analysis. The numerical solution by the Runge–Kutta fourth-order (RK-4) method integrated with a shooting technique compared favorably with graphs drawn for the analytical solution from the proposed strategy HELA. The current results show that an increase in the fractal factors enhances the resistance to fluid motion, leading to a suppression of the velocity field. Physically, this often relates to the complexity of the medium or the fractal nature of the transport process, where higher fractal dimensions or factors can lead to slower diffusion or flow rates, like the role of porous media. Therefore, the current study has significant implications in the promotion of nanotechnology fields in medicine, particularly the use of gold nanoparticles in chemotherapy for the eradication of cancerous cells. Full article

Nanoparticles based on gallium ferrite are explored as potential agents for magnetic fluid hyperthermia due to their magnetic performance and biocompatibility. In this study, Ga_xFe_3−xO₄ systems (0 ≤ x ≤ 1) were synthesized by co-precipitation of iron chlorides, with part of the series modified by a chitosan shell. Structural analysis confirmed single-phase formation across the studied range, while microscopy revealed irregular morphology, broad size distribution, and aggregation into mass-fractal-like assemblies. Chitosan was observed to coat groups of particles rather than single crystallites. Under an alternating magnetic field, all samples exhibited efficient heating, with specific absorption rate values generally increasing with gallium content. The composition Ga_0.73Fe_2.27O₄ showed the highest SAR—83.4 ± 2.2 W/g at 2.8 mg/mL, 532 kHz, 15.3 kA/m, and SAR values rose with decreasing concentration. Cytotoxicity assays without magnetic activation indicated no harmful effect, while chitosan-coated nanoparticles enhanced fibroblast viability and lowered metabolic activity of HeLa cells. Higher Ga content (x = 0.66) combined with chitosan modification was identified as optimal for hyperthermia. The results demonstrate the biomedical potential of these nanoparticles, while emphasizing the need to reduce shape heterogeneity, aggregation, and sedimentation for improved performance. Full article

The drying of nanofluid films on a surface can form various patterns and plays an important role in painting, surface patterning, and nano-fabrication processes. In this paper, a two-dimensional Kinetic Monte Carlo (KMC) model is developed based on the two-dimensional Ising model to investigate the drying patterns of nanofluids in an open domain. In the KMC model, the effective chemical potential is approximated by a linear function, in contrast to the constant value used in previous studies. This ensures that the dewetting front in the open domain consistently recedes from the edges toward the center. Simulation results show that nanoparticles, initially uniformly distributed, can assemble into branched structures that remain on the substrate after complete evaporation of the nanofluid. Furthermore, the structures observed in our study differ from the fractal cavities investigated in previous studies conducted in closed domains. A parametric study reveals that both the particle diffusion rate and the chemical potential distribution significantly influence the resulting patterns. Full article

This study presents a compact, wideband fractal antenna fabricated using silver nanoparticles (AgNPs) and screen-printing technology. The antenna consists of a decagonal monopole patch and a mesh ground plane, both printed on a transparent polyethylene terephthalate (PET) substrate. The proposed antenna has a compact size of 18 × 16 × 0.55 mm³, achieved by stacking two PET layers joined using double-sided tape. The antenna covers both C- and X-bands, with measured optical transmittance of 68.1% and radiation efficiency of 72%. The simulated −10 dB bandwidth (without bending) spans 4–10.8 GHz and 11.2–12.5 GHz, while the measured −10 dB bandwidth is 3.8–11.2 GHz without bending, 3–11.4 GHz at 30° bending, and 3–11.2 GHz at 45° bending, confirming that there was stable performance under flexure. The conductive patterns were formed using silver nanoparticle paste with a sheet resistance of 0.2 Ω/sq, followed by annealing in a vacuum oven at 140 °C for 20 min. The proposed antenna was tested under 30° and 45° bending, and the measured S₁₁ remained stable, confirming flexibility. The use of a flexible, optically transparent PET substrate enables installation on curved or see-through surfaces. Combining compact size, wideband performance, cost-effective fabrication, and optical transparency, the antenna demonstrates strong potential for application in X-band radar, C-band satellite communications, and S-band Wi-Fi. Full article

Background: Polymer-coated mesoporous silica nanoparticles have attracted immense research interest in stimuli-responsive drug delivery systems due to their drug-releasing ability on demand at specific sites in response to external or internal signals. However, the relationships between the coated-copolymer encapsulation and drug delivery performance in the hybrid nanocomposites was rarely reported. Therefore, the main objectives of the present work are to explore the cell uptake, cellular internalization, cytotoxicity, and hemolysis performance of the fluorescent hybrid materials with different polymer-encapsulated amounts. Methods: Using (2-(2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione)-doped poly[(N-isopropylacrylamide)-co-(acrylic acid)] (PAN) as a shell and bimodal mesoporous silicas (BMMs) as a core, the dual pH- and temperature-responsive mesoporous PAN@M-BMMs with the fluorescent performances were synthesized via a radical polymerization approach. The effects of the PAN-coated thicknesses on their physicochemical properties and structural features were demonstrated via XRD and SAXS patterns, SEM and TEM images, FT-IR spectra, and TG analysis. Their mass fractal (D_m) evolutions were elucidated on the basis of the SAXS patterns and fluorescence spectra. Results: The D_m values increased from 2.74 to 2.87 with an increase of the PAN-coated amount from 17 to 26.5% along with the particle size from 76.1 to 85.6 nm and blue-shifting of their fluorescent emission wavelength from 470 to 444 nm. Meanwhile, the PAN@M-BMMs exhibited a high ibuprofen (IBU) loading capacity (13.8%) and strong dual pH-/temperature-responsive drug-releasing performances (83.1%) at pH 7.4 and 25 °C, as comparison with that (17.9%) at pH 2.0 and 37 °C. The simulated results confirmed that the adsorption energy decreased from −67.18 kJ/mol for pure BMMs to −116.76 kJ/mol for PAN@M-BMMs, indicating the PAN-grafting on the surfaces of the BMMs core was beneficial to improve its IBU-adsorption capacity. Its uptake in the HeLa cell line was performed via microplate readers, confocal microscopy, flow cytometry, and ICP measurement, showing a low cytotoxicity at a concentration up to 100 µg/mL. Specially, P_0.2AN@M-BMMs had a superior cellular uptake and fluorescence properties via the time-dependent uptake experiments, and exhibited the highest silicon content via the cellular internalization analysis, as compared to other carriers. Hemolysis tests confirmed the hemolysis rates below 5%. Conclusions: These demonstrations verified that PAN@M-BMMs should be a promising biomedical application prospect. Full article

This study reported a one-spot preparation of magnetic composite carbon (MCC@Fe) from microcrystalline cellulose (MC). The pure cellulose was impregnated in iron (III) chloride solution and carbonized at 650 °C. The MCC@Fe composite adsorbent underwent various characterization techniques. XRD identified nanostructured Fe₃O₄ particles with an average crystallite size of 34.3 nm embedded in the core subunits of the material. FESEM images indicated a rough and irregular surface, with some cavities along its surface, incorporating Fe₃O₄ nanoparticles, while EDS analysis confirmed the presence of elements like Fe, C, and O. Notably, combining thermal and chemical treatments produces a composite with more pores and a high specific surface area (500.0 m² g⁻¹) compared to MC (1.5 m²/g). VSM analysis confirmed the magnetic properties (0.76 emu/g), while the Hydrophobic Index (HI) showed that MCC@Fe was hydrophobic (HI 1.395). The adsorption studies consisted of kinetic, mass transfer, equilibrium, and thermodynamics studies. Kinetic study of the adsorption of paracetamol on MCC@Fe composite proved to be rapid, and the time necessary for covering 95% of the surface (t_0.95) was lower than 27 min following the fractal-like pseudo-first-order model (FPFO). Liu’s isotherm proved to be the most appropriate for understanding the adsorption equilibrium. Remarkably, the maximum sorption capacity (Q_max) of paracetamol was 34.78 mg g⁻¹ at 45 °C. The ΔH° value (+27.00 kJ/mol) and the negative ΔG° values were consistent with the physisorption mechanism and favorable process. Furthermore, the mass transfer mechanism showed that the transfer is governed by the intraparticle diffusion model, with surface diffusion being the rate-limiting step when considering the Biot number greater than 100. This research displayed a single-route production of inexpensive magnetic nano adsorbents capable of efficiently eliminating paracetamol from aqueous environments. Full article

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The use of nanofluids in technology and industry is steadily increasing due to their effective implementation. The improved thermophysical properties of nanofluids have a significant impact on their effectiveness in convection phenomena. The technology is not yet complete at this point; binary and ternary nanofluids are currently being used to improve the performance of conventional fluids. Therefore, this work aims to theoretically investigate the ternary nanofluid flow of a couple stress fluid in a vertical channel. A homogeneous suspension of alumina, cuprous oxide, and titania nanoparticles is formed by dispersing trihybridized nanoparticles in a base fluid (water). The effects of pressure gradient and viscous dissipation are also considered in the analysis. The classical ternary nanofluid model with couple stress was generalized using the fractal–fractional derivative (FFD) operator. The Crank–Nicolson technique helped to discretize the generalized model, which was then solved using computer tools. To investigate the properties of the fluid flow and the distribution of thermal energy in the fluid, numerical methods were used to calculate the solution, which was then plotted as a function of various physical factors. The graphical results show that at a volume fraction of 0.04 (corresponding to 4% of the base fluid), the heat transfer rate of the ternary nanofluid flow increases significantly compared to the binary and unary nanofluid flows. Full article

In this research, the doping of SrTiO₃ with Mn⁴⁺ was performed in order to evaluate the potential application as a photocatalyst for the degradation of organic dye pollutants. Since photocatalytic activity depends on grain microstructure, fractal analysis was used to estimate the Hausdorff dimension to provide a more thorough investigation of Mn@SrTiO₃ morphology. Structural analysis by infrared spectroscopy indicated the incorporation of Mn⁴⁺ into the SrTiO₃ lattice, while by using x-ray diffraction, the crystallite size of 44 nm was determined. The photocatalytic activity test performed on complex ethyl violet organic dye revealed potential for Mn@SrTiO₃ application in water treatment. Based on fractal regression analysis, a good estimate was obtained for the reconstruction of grain shape, with a Hasudorff dimension of 1.13679, which was used to find the best kinetics model for the photodegradation reaction. The experimental data showed a nearly linear fit with fractal-like pseudo-zero order. These findings and applications of fractal dimensions could contribute to future characterizations of photocatalysts, providing a deeper understanding of surface properties and their influence on photocatalytic activity. Full article

The fractal characterization of supported nanoparticles is a useful tool for obtaining structural and morphological information that strongly impacts catalytic properties. We have synthesized and characterized Pt supported on TiO₂ nanostructures. Triblock copolymers with thermosensitive properties were used as templating agents during the synthesis process. In addition to the several techniques used for the characterization of the materials, we carried out fractal analysis. The prepared materials showed a reduction in the band gap of TiO₂ from 3.44 to 3.01 eV. The extended absorption in the 500–700 nm regions is mostly attributed to the presence of supported Pt nanoparticles. The ability of the nanostructured Pt/TiO₂ catalysts to generate H₂ in an aqueous solution was evaluated. The test reaction was carried out in the presence of methanol, as a hole scavenger, under simulated solar light. Pt/TiO₂-3TB shows the highest rate of H₂ (4.17 mmol h⁻¹ g_cat⁻¹) when compared to Pt/TiO₂-0TB (3.65 mmol h⁻¹ g_cat⁻¹) and Pt/TiO₂-6TB (2.29 mmol h⁻¹ g_cat⁻¹) during simulated solar light irradiation. Pt/TiO₂-3TB exhibits a more structured organization (fractal dimensions of 1.65–1.74 nm at short scales, 1.27–1.30 nm at long scales) and a distinct fractal behavior. The generation of hydrogen via photocatalysis can be linked to the fractal characteristics. Full article

Fluidization bed reactor is an attractive method to synthesize and process quantities of functional nanoparticles, due to the large gas–solid contact area and its potential scalability. Nanoparticles fluidize not individually but as a form of porous agglomerates with a typical porosity above 90%. The porous structure has a significant effect on the hydrodynamic behavior of a single nanoparticle agglomerate, but its influence on the flow behavior of nanoparticle agglomerates in a fluidized bed is currently unclear. In the present study, a drag model was developed to consider the porous structure effects of nanoparticle agglomerates by incorporating porous-structure-based drag laws in the Eulerian–Eulerian two-fluid model. Numerical simulations were performed from particulate to bubbling fluidization state to evaluate the applicability of porous-structure-based drag laws. Results obtained for the minimum fluidization and bubbling velocities, bed expansion ratio, and agglomerate dispersion coefficient show that, compared with the drag law of solid sphere, the porous-structure-based drag laws, especially the drag law of fractal porous spheres, provide a closer fit to the experimental data. This indicates that the pore structures have a great impact on gas–solid flow behavior of nanoparticle agglomerates, and the porous-structure-based drag laws are more suitable for describing flows in nanoparticle agglomerate fluidized beds. Full article

Fungal growth on construction materials in tropical climates can degrade aesthetics and manifestations on modern and historical sick buildings, affecting the health of their inhabitants. This study synthesized ZnO nanoparticles with enhanced antifungal properties using a precipitation method. Different concentrations (25%, 50%, and 100%) of Eichhornia crassipes aqueous extract were used with Zn(NO₃)₂·6H₂O as the precursor to evaluate their spectroscopic, morphological, textural, and antifungal properties. X-ray diffraction confirmed the hexagonal wurtzite phase of ZnO with crystallite sizes up to 20 nm. Fourier-transform infrared spectroscopy identified absorption bands at 426, 503, and 567 cm⁻¹ for ZnO-100, ZnO-50, and ZnO-25, respectively. Nitrogen physisorption indicated a type II isotherm with macropores and a fractal dimension coefficient near 2 across all concentrations. Polydispersity index analysis showed that ZnO-50 had a higher PDI, indicating a broader size distribution, while ZnO-25 and ZnO-100 exhibited lower PDI values, reflecting uniform and monodisperse particle sizes. FESEM observations revealed semi-spherical ZnO morphologies prone to agglomeration, particularly in ZnO-25. Antifungal tests highlighted ZnO-25 as the most effective, especially against Phoma sp. with an MFC/MIC ratio of 78 µg/mL. Poisoned plate assays demonstrated over 50% inhibition at 312 µg/mL for all tested fungi, outperforming commercial antifungals. The results indicate that ZnO NPs synthesized using E. crassipes extract effectively inhibit fungal growth on construction materials. This procedure offers a practical approach to improving the durability of building aesthetics and may contribute to reducing the health risks associated with exposure to fungal compounds. Full article

In stealth applications, there is a growing emphasis on the development of radar-absorbing structures that are efficient, flexible, and optically transparent. This study proposes a screen-printed metamaterial absorber (MMA) on polyethylene terephthalate (PET) substrates using indium tin oxide (ITO) as the grounding layer, which achieves both optical transparency and flexibility. These materials and methods enhance the overall flexibility and transparency of MMA. To address the limited transparency caused by the silver nanoparticle ink for the top pattern, a metal mesh was incorporated to reduce the area ratio of the printed patterns, thereby enhancing transparency. By incrementing the fractal order of the structure, we optimized the operating frequency to target the X-band, which is most commonly used in radar detection. The proposed MMA demonstrates remarkable performance, with a measured absorption of 91.99% at 8.85 GHz and an average optical transmittance of 46.70% across the visible light spectrum (450 to 700 nm), indicating its potential for applications in transparent windows or drone stealth. Full article