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The most favorable gift of modern science is nanofluid. The nanofluid can able to move freely through micro channels with the spreading of nanoparticles. Due to improved convection between the base liquid surfaces and nanoparticles, the nano suspensions express high thermal conductivity. Also, the benefits of suspending nanoparticles in base fluids are increased heat capacity, surface area, effective thermal conductivity, collision, and interaction among particles. This research aim to study squeezing flow of carbon nanotubes based on water (H2O) in rotating channels. Entropy generation is evaluated and for this purpose, second law of thermodynamics is employed. The influences of thermal radiation, viscous dissipation, and applied magnetic field on nanofluid are taken into account. The flow of the nanofluid is considered in unsteady three dimensions. The transformed ordinary differential equations (ODEs) are solved by homotopy analysis method with the help of similarity variables. Results obtained for single and multi-wall carbon nanotubes are compared. Plots have been presented in order to examine how the velocities, temperature, and entropy profiles become affected by numerous physical parameters. Generally, the velocity profiles escalate when the upper plate of the channel moves toward the lower stretching one and reduces when the upper plate is moving away from the lower one. The velocity profile in y-direction escalates with the escalation in nanoparticle volume fraction and suction parameter while the rotation parameter bids dual behavior with the escalating values. The velocity profile in x-direction bids the oscillatory behavior with the enhancement in nanoparticle volume fraction, rotation parameter, and magnetic parameter. The physical properties of carbon nanotubes, thermo physical properties of carbon nanotubes and nanofluid of some base fluids, and thermal conductivity of carbon nanotubes with different volume fractions are shown through tables.

Due to a combination of optimal properties such as great strength, high hardness, good process ability, and good mechanical properties, AISI 4340 steel is widely used in many critical industrial applications such as nuclear, military, defense, and aerospace. It is also widely used in hydraulic forged machine tools, forged automotive crankshaft systems, shafts and gears, because of their improved characteristics, and its good tribological properties. The purpose regarding this work is to check the tribological characteristics of austempered AISI 4340 steel while dry and lubricated with machinery oil of SAE 30 grade as base oil. As received, AISI 4340 steel samples have been austempered to four definitely austenitic phase temperatures (850℃, 900℃, 1000℃, and 1050℃) for 90 minutes before being immersed in a mixture of potassium nitrite and sodium nitrite at 400℃ for 45 minutes. Friction and wear tests were then performed on austempered samples. Multi-walled carbon nanotube particles were blended at weight concentrations of 0.055, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and 0.45 with typical machinery oil of 30 grade as base lubricant oil. A pin on the disc wear configuration was used in the experimental investigation. The use of Multi-Walled Carbon Nanotube (MWCNTs) additives in the base oil resulted in a decrease in both friction coefficients and wear rates values when compared to typical base oil lubricant. The results also showed a reduction in both friction coefficients and wear rates as the sample's austempering temperatures were raised. Sliding surfaces were also photo micro graphed, and when the volume concentrations of Multi-Walled Carbon Nanotube particles in the normal base oil lubricant were increased, smoother surfaces with less damage were shown.

High-performance flexible strain sensors are playing an increasingly important role in wearable electronics, such as human motion detection and health monitoring, with broad application prospects. This study developed a flexible resistance strain sensor with a porous structure composed of carbon black and multi-walled carbon nanotubes. A simple and low-cost spraying method for the surface of a porous polydimethylsiloxane substrate was used to form a layer of synergized conductive networks built by carbon black and multi-walled carbon nanotubes. By combining the advantages of the synergetic effects of mixed carbon black and carbon nanotubes and their porous polydimethylsiloxane structure, the performance of the sensor was improved. The results show that the sensor has a high sensitivity (GF) (up to 61.82), a wide strain range (0%–130%), a good linearity, and a high stability. Based on the excellent performance of the sensor, the flexible strain designed sensor was installed successfully on different joints of the human body, allowing for the monitoring of human movement and human respiratory changes. These results indicate that the sensor has promising potential for applications in human motion monitoring and physiological activity monitoring.

This study aims to increase the specific surface area of multi-walled carbon nanotubes (MWCNTs) by forming and subsequently removing various metal oxide nanoparticles on them. We used facile methods, such as forming the particles without using a vacuum or gas and removing these particles through simple acid treatment. The shapes of the composite structures on which the metal oxide particles were formed and the formation of multi-vacancy-defect MWCNTs were confirmed via transmission electron microscopy and scanning electron microscopy. The crystallinity of the formed metal oxide particles was confirmed using X-ray diffraction analysis. Through specific surface area analysis and Raman spectroscopy, the number of defects formed and the degree and tendency of defect-formation in each metal were determined. In all the cases where the metal oxide particles were removed, the specific surface area increased, and the metal inducing the highest specific surface area was determined.

The expanding uses of carbon nanotubes (CNTs) in industry and medicine have raised concerns about their toxicity on human and animal health. CNTs, including multi-walled nanotubes (MWCNTs), have been reported to induce immunotoxic, inflammatory, and oxidative effects. Quercetin is a natural flavonoid present in many vegetables and fruits and has immunomodulatory, anti-inflammatory, and antioxidant properties. Herein, we investigated the protective effects of quercetin on pristine MWCNTs-induced immunotoxicity in mice. In comparison with two doses of MWCNTs, high doses [0.5 mg/kg body weight (BW), once intraperitoneally (IP)] caused higher immunotoxic, inflammatory, and oxidative effects than low doses (0.25 mg/kg BW, once IP). Administration of quercetin (30 mg/kg BW, IP for 2 weeks) relieved these deleterious effects as evidenced by (1) reduced spleen weight, (2) increased number of total leukocytes, lymphocytes, and neutrophils, (3) elevated serum levels of IgM, IgG, and IgA, (4) decreased lipid peroxide malondialdehyde levels and increased levels of antioxidant markers reduced glutathione, superoxide dismutase, and catalase in the spleen, (5) decreased concentrations and mRNA levels of inflammatory markers tumor necrosis factor-alpha (TNFα), interleukin 1 beta (IL1ß), and IL6 in the spleen, (6) downregulated expression of immunomodulatory genes transforming growth factor-beta (TGFß), cyclooxygenase2 (COX2), and IL10, and (7) regenerative histological changes as indicated by decreased mononuclear cell infiltration, minimized degenerative changes and restored lymphocytes depletion in the spleen. These results infer that quercetin can ameliorate MWCNTs-induced immunotoxic, inflammatory, and oxidative effects.

This investigation elucidates a novel methodology for augmenting the tribological and mechanical attributes of epoxy composites via selective functionalization of multi‐walled carbon nanotubes (MWCNTs). The study optimizes wear mechanisms and friction‐induced graphitization by incorporating pristine (P‐MWCNTs), carboxyl‐functionalized (COOH‐MWCNTs), amine‐functionalized (NH₂‐MWCNTs), and silane‐modified MWCNTs. Composites were characterized for tensile strength, compressive strength, surface hardness, coefficient of friction (COF), and specific wear rate (SWR). Incorporation of 0.3 wt.% COOH‐MWCNTs yielded optimal performance, reducing SWR by 82% (0.07 × 10⁻⁶ mm³ N⁻¹·m⁻¹ at 8 Hz) and COF by 32% (0.37 at 10 N) relative to neat epoxy (SWR: 0.50 × 10⁻⁶ mm³ N⁻¹·m⁻¹, COF: 0.66 at 15 N). Enhanced dispersion, interfacial adhesion, and tribofilm formation account for superior tensile strength (≈90 MPa) and hardness (≈88 Shore D). X‐ray diffraction and transmission electron microscopy validated friction‐induced graphitization and partial structural degradation above 10 N. Applications encompass self‐lubricating bushings, protective coatings, and wear‐resistant surfaces for automotive and industrial components. Future investigations should target enhanced compressive strength and load‐bearing capacity. Incorporating 0.3 wt.% COOH‐functionalized MWCNTs, well dispersed via ultrasonication, into epoxy significantly enhances tribological and mechanical performance, reducing wear by 82% and COF by 32%. During sliding, friction breaks down MWCNTs into graphitic fragments, which are slowly released, forming a protective tribofilm. These composites excel in automotive, aerospace, and industrial applications requiring strength and low friction.

Conductive polymer composites (CPCs) offer a unique combination of the lightweight and processable nature of polymers with the electrical conductivity of metals, making them suitable for a range of applications, including electromagnetic interference shielding and sensors. This study investigates the multifunctional properties of polyamide 6/polyamide 12 (PA6/PA12) (75/25) CPCs filled with multi‐walled carbon nanotubes (MWCNTs). The present research focuses on the morphological, rheological, thermal, and electrical properties of nanocomposites. The incorporation of MWCNTs into the PA6/PA12 blend is achieved using twin‐screw extrusion, and compression molding is used to obtain nanocomposites. Different MWCNT loadings are examined to optimize the dispersion and connectivity of the conductive filler network. Morphological analysis via scanning electron microscopy reveals significant structural changes with increasing MWCNT content, changing from a sea‐island morphology to a more interconnected network. Differential scanning calorimetry provides insights into the thermal behavior, showing changes in melting and crystallization behavior as well as crystallinity degree with filler loading. Rheological assessments demonstrated variations in complex viscosity, storage modulus, and loss modulus with different MWCNT contents. Electrical measurements using the Van der Pauw technique highlightes the improved conductivity of the nanocomposites. The findings underscore the potential of PA6/PA12/MWCNT nanocomposites for advanced applications such as interference shielding and sensors. This study explores the multifunctional properties of PA6/PA12 polymer nanocomposites filled with MWCNTs. It reveals how varying MWCNT concentrations influence the material's morphology, electrical conductivity, and thermal and rheological behavior. Particularly beyond 3.5 wt.% MWCNT, an interconnected conductive network is formed, significantly improving the electrical performance. These results highlight the potential of PA6/PA12/MWCNT nanocomposites for applications requiring tailored electrical conductivity, such as electromagnetic interference shielding and sensors.

A membrane composed of polyethylene terephthalate nanofiber and multi-walled carbon nanotubes (PET NF-MWCNTs) composite is used to adsorb methylene blue (MB) dye from an aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques are employed to study the surface properties of the adsorbent. Several parameters affecting dye adsorption (pH, MB dye initial concentration, PET NF-MWCNTs dose, and contact time) are optimized for optimal removal efficiency (R, %) by using the Taguchi L25 (54) Orthogonal Array approach. According to the ANOVA results, pH has the highest contributing percentage at 71.01%, suggesting it has the most significant impact on removal efficiency. The adsorbent dose is the second most affected (12.08%), followed by the MB dye initial concentration of 5.91%, and the least affected is the contact time (1.81%). In addition, experimental findings confirm that the Langmuir isotherm is well-fitted, suggesting a monolayer capping of MB dye on the PET-NF-MWCNT surface with a maximum adsorption capacity of 7.047 mg g−1. Also, the kinetic results are well-suited to the pseudo-second-order model. There is a good agreement between the calculated (qe) and experimental values for the pseudo-second-order kinetic model.

Functionalized multi‐walled carbon nanotubes have been extensively gained popularity in pancreatic cancer gene therapy. LyP‐1, a peptide, has been proved to specifically bind pancreatic cancer cells. The potential therapeutic effect of LyP‐1–conjugated functionalized multi‐walled carbon nanotubes in treating pancreatic cancer is still unknown. In this study, LyP‐1–conjugated functionalized multi‐walled carbon nanotubes were successfully synthesized, characterized and showed satisfactory size distribution and zeta potential. Compared with functionalized multi‐walled carbon nanotubes, cellular uptake of LyP‐1–functionalized multi‐walled carbon nanotubes was shown to be increased. Compound of LyP‐1–functionalized multi‐walled carbon nanotubes and MBD1siRNA showed superior gene transfection efficiency. Moreover, LyP‐1‐fMWNTs/MBD1siRNA complex could significantly decrease the viability and proliferation and promoted apoptosis of pancreatic cancer cells in vitro. Further xenograft assays revealed that the tumour burden in the nude mice injected with LyP‐1–functionalized multi‐walled carbon nanotubes/MBD1siRNA was significantly relieved. The study demonstrated that LyP‐1–functionalized multi‐walled carbon nanotubes/MBD1siRNA could be a promising candidate for tumour active targeting therapy in pancreatic cancer.

Physicochemical properties play a crucial role in determining the toxicity of multi-walled carbon nanotubes (MWCNTs). Recently we found that MWCNTs with longer length and smaller diameters could induce toxicity to human umbilical vein endothelial cells (HUVECs) through the activation of endoplasmic reticulum (ER) stress. In this study, we further investigated the possible contribution of hydroxylation and carboxylation to the cytotoxicity of MWCNTs. The HUVECs were exposed to pristine (code XFM19), hydroxylated (code XFM20; content of hydroxyl groups 1.76 wt%) and carboxylated (code XFM21; content of carboxyl groups 1.23 wt%) MWCNTs, respectively. Then, the internalization, cytotoxicity, oxidative stress and activation of apoptosis-ER stress pathway were measured. In consequence, all types of MWCNTs could be internalized into the HUVECs, and the cellular viability was significantly reduced to a similar level. Moreover, the MWCNTs increased intracellular reactive oxygen species (ROS) and decreased glutathione (GSH) to similar levels, indicating their capacity of inducing oxidative stress. The Western blot results showed that all types of MWCNTs reduced BCL-2 and increased caspase-3, caspase-8, cleaved caspase-3 and cleaved caspase-8. The expression of ER stress gene DNA damage-inducible transcript 3 ( ) and protein level of chop were only significantly induced by XFM20 and XFM21, whereas protein level of p-chop was promoted by XFM19 and XFM21. In addition, the pro-survival gene was significantly down-regulated by all types of MWCNTs. These results suggested that MWCNTs could induce cytotoxicity to HUVECs via the induction of oxidative stress and apoptosis-ER stress, whereas a low degree of hydroxylation or carboxylation did not affect the toxicity of MWCNTs to HUVECs.