Walled Carbon Nanotubes Research Articles

Partial dehydration-mediated selective ion-permeation through subnanometer-scale windows in highly crystalline single walled carbon nanotube walls

We propose single-atom catalytic oxidation method for production of subnanometer-scale windows on the graphene layer of single walled carbon nanotubes (SWCNTs) in this study. We used the free-standing SWCNT films which had merits for reliable measurements and applicability to electrochemical measurements for determination of the nanowindow size. Copper(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (CuPc) was adsorbed on SWCNT bundles using liquid-phase adsorption at surface coverage of 0.9. Then, nanowindows were produced by oxidation above 550 K being higher than the decomposition temperature of the bulk CuPc. The oxidation of CuPc-adsorbed SWCNT film markedly increased the surface area from N2 adsorption at 77 K due to access of N2 to the internal tube space through the nanowindows. The nanowindow size was estimated to be the molecular size of N2 through the evident low-pressure adsorption hysteresis of the N2 adsorption isotherm and TEM observation. The selective ion permeability through the nanowindows for H3O+, Li+, Na+, K+, Mg2+, Ca2+, and Ba2+ ions was determined by the inside-capacitance being the capacitance difference of SWCNT between with and without nanowindows. The selective permeation of the hydrated ions depended on the oxidation conditions for production of nanowindows, showing less than 1 nm of the nanowindow size. The relationship between the inside-capacitance and hydrated ion diameter for the selective permeation of hydrated ions indicated partial dehydration of the hydrated ions just only on their permeation through the nanowindows under the accelerated conditions.

14 Carcinogenicity Risk Assessment of Various Carbon Nanotubes by Intra-Tracheal Intra-Pulmonary Spray (TIPS) Dosing Followed by 2-Year Observation

Abstract Multi-walled carbon nanotubes (MWCNTs) are composed of multiple coaxially arranged graphene cylinders. MWCNTs range in diameter from 1 to over 100 nm depending on the number of constituting graphene cylinders. MWCNTs can be divided into two general subtypes, straight and tangled: increasing the number of constituent graphene cylinders increases the number of layers that compose the carbon nanotube wall, and as the number of wall layers increase, the wall thickness increases and the MWCNT becomes more rigid and straight. MWCNTs with a low number of wall layers are flexible and can assemble into tangled agglomerates. We initially showed MWCNT-N, a straight-type MWCNT with 30-40 walls, induced lung tumors and mesotheliomas after administration by intra-tracheal intra-pulmonary spraying (TIPS): rats were administered a total dose of 1mg/rat during the initial 2 weeks of the study, and animals were observed for 2 years without any further treatments. Using this short-term dosing and 2-year observation method we conducted carcinogenicity tests for other MWCNTs with different cylinder wall layers. We found that both straight type MWCNTs, MWCNT-7 (40 layers), MWCNT-A (150 layers), and tangled type MWCNTs, MWCNT-B (15 layers) and double-walled CNT (DWCNT) (2 layers) induced lung tumors and/or pleural mesotheliomas. In contrast to these results, we found carbon nanohorns, carbon nanostructures composed of single-walled carbon nanotubes (SWCNT), and carbon nanobrushes, a fibrous aggregate of carbon nanohorns, were not carcinogenic. Data on foreign body radical production, microarray and mutational signature analyses, and gene alterations will be presented.

Sensitive detection of chromium (VI) using Au-NPs/MWCNT/chitosan composite via electrochemical approach

A glassy carbon electrode (GCE) was nanostructurally modified with a scaffold of gold nanoparticles (AuNPs), multiwalled carbon nanotubes (MWCNTs) and chitosan (Chit) for a sensitive detection of hexavalent chromium Cr(VI) in aqueous solutions. Each step of modification was analyzed and characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Strong interfacial adhesion between gold nanoparticles and porous nanostructure of MWCNTs-Chit was depicted. This scaffold uniformly distributed hydroxyl and carboxylate groups, as well as amine group throughout the surface of glassy carbon electrode, and gold nanoparticles adhered to carbon nanotubes wall inside the polymeric matrix. This scaffold selectively coordinated and preconcentrated the chromate ions for ulterior Cr(VI) detection. Under the optimized conditions (deposition potential: + 0.8 V vs. SCE, deposition time: 120 s), differential pulse voltammetry (DPV) electroanalysis results indicated the linear increment of electrochemical signals with an increase in the concentration of Cr(VI). Fabrication of a calibration curve was performed in a concentration range of 0.003–0.1 μg L−1 and limit of detection (LOD, 3σ/m) was calculated as 0.007 μg L−1. This nanostructured electrochemical sensor coupled with differential pulsed voltammetry, constitutes a very effective prospective capable of high sensitivity, selectivity, precision, accuracy, and rapid trace determination of hexavalent chromium ion in aqueous medium.

Ag/CdO/Fe3O4@MWCNTs Promoted Green Synthesis of Novel Triazinopyrrolothiazepine: Investigation of Antioxidant and Antimicrobial Activity

In this study a new, economical and green method was reported for the synthesis of Ag/CdO/Fe3O4@multi-walled carbon nanotubes (MWCNTs) MNCs as a new heterogeneous catalyst. For confirming the structure of synthesized nanocatalyst, XRD, FESEM, Energy-dispersive X-ray Spectroscopy (EDX), and TEM analyses were utilized. The Ag/CdO/Fe3O4@MWCNTs MNCs as a high-performance catalyst was employed for the preparation of a new family of substituted triazinopyrrolothiazepine using the one-pot condensation reactions of isatoic anhydride, ammonium acetate, α-haloketones, ethyl bromopyruvate, isothiocyanates, and hydrazoyl chloride in water at room temperature. Another work in this research is investigation of antioxidant property of some synthesized compounds by diphenyl-picrylhydrazine (DPPH) radical trapping experiment. Presently, bacteria that are not destroyed with drug have generated many problems in the performance of many transferable diseases. For this reason, discovering appropriate and new procedures for the dealing with these pathogens are important and recent study has focused on the investigation of the antibacterial effects on the prepared compounds.

Composite capillary carbon tube Nb18W16O93 as advanced anode material for aqueous ion capacitors

Niobium-tungsten bimetal oxides have received wide attention due to their excellent lattice properties. In this work, Nb18W16O93 (NbWO) with a tetragonal tungsten bronze structure was synthesized by simple hydrothermal method. NbWO was modified to provide high specific surface area via combining with hollow carbon nanotubes. Meanwhile, NbWO grows along the tube wall of carbon nanotubes, thus buffering the volume effect of NbWO particles. Also, the migration distance of Li-ion is effectively shortened, as well as the improved ion transfer efficiency and the reaction kinetics. In addition, carbon tube can enhance conductivity of NbWO, contributing to outstanding charge storage capacity and rate energy. Precisely, NbWO@C as electrode possesses large specific capacity (249.6 F g−1 at 0.5 A g−1) and good rate performance (55.9% capacity retention from 0.5 to 2 A g−1). The aqueous Li-ion capacitor presents the advantages of high safety, low cost and good environmental friendliness. An asymmetric aqueous capacitor AC//NbWO@C, based on ‘water-in-salt’ electrolyte with high concentration lithium acetate, exhibits a large energy density of 43.2 Wh kg−1 and a power density of 9 kW kg−1. Generally, NbWO@C as anode materials shows superior application perspective.

Synthesis and application of polyethyleneimine and polyethylene glycol grafted on CoFe2O4/single‐walled carbon nanotubes as a delivery platform for silibinin: Loading experiments, modeling, and in‐vitro release studies

AbstractThe aim of this study was to prepare and characterize a nanohybrid, CoFe2O4/single‐walled carbon nanotubes (SWCNTs) grafted with polyethyleneimine and polyethylene glycol (CoFe2O4/SWCNT–PEI–PEG), for loading silibinin (SB) as an anti‐cancer natural agent to form a drug delivery platform with magnetic targeting capability and pH‐responsive release. The characteristics of the prepared nanocomposite were analyzed by different characterization techniques, confirming a well‐magnetic porous structure consisting of rich amine and hydroxyl functional groups of PEI and PEG, respectively, and CoFe2O4 aggregates on the wire‐like SWCNT wrapped by the polymer. Through the adsorption process, the SB loading was accomplished. The highest adsorption capacity of CoFe2O4/SWCNT–PEI–PEG for SBN was 74.8 mg g−1 with 10 mg of the nanocomposite attained at pH 7 and a solution temperature of 328 K. The experimental data were accurately predicted by the Langmuir isotherm and pseudo‐first‐order kinetic models. The release rate from SB loaded CoFe2O4/SWCNT–PEI–PEG was enhanced to 76% at pH 5.6 compared to pH 7.4 which was 45%, demonstrating that the acidic medium may relatively improve drug release. The SB release kinetic data obeyed the Peppas–Sahlin model. Our results demonstrated the potential of the hybrid nanocarrier as a vehicle for solubilizing and delivering SB to specific sites.

Encapsulation of testosterone and dihydrotestosterone into chiral carbon nanotubes: A molecular dynamics study

Testosterone and Dihydrotestosterone play a pivotal role in maintaining sexual health in the human body, however, excess amount of these biomolecules inside the human body may lead to serious health disorders such as PCOS in females, and elevated cholesterol levels, insulin resistance, Hirsutism, etc. In this work, we explore if carbon nanotube (CNT) can be used to capture testosterone and dihydrotestosterone. Both in vacuo and water-mediated molecular dynamics simulation, we observe that Testosterone and Dihydrotestosterone prefer to be adsorbed inside the wall of CNT (5,10) and CNT (10,5) CNT via strong van der Waals interactions between them. Hydrogen-bond analysis shows that the molecules are less solvated inside the CNT, reinforcing the encapsulating process. Free energy profiles are evaluated for the biomolecules to enter inside the nanotubes using well-tempered metadynamics. It is also observed that chirality plays a role in stabilizing the two molecules inside the CNT. This study might be helpful in the future for the further development of advanced nanodevices to remove selectively toxic or excess biomolecules from the human body.

Biomimetic Material for Quantification of Methotrexate Using Sensor Based on Molecularly Imprinted Polypyrrole Film and MWCNT/GCE

This study investigates biomimetic sensors for the detection of methotrexate contaminants in environmental samples. Sensors inspired by biological systems are the focus of this biomimetic strategy. Methotrexate is an antimetabolite that is widely used for the treatment of cancer and autoimmune diseases. Due to the widespread use of methotrexate and its rampant disposal into the environment, the residues of this drug are regarded as an emerging contaminant of huge concern, considering that exposure to the contaminant has been found to lead to the inhibition of some essential metabolic processes, posing serious risks to humans and other living beings. In this context, this work aims to quantify methotrexate through the application of a highly efficient biomimetic electrochemical sensor constructed using polypyrrole-based molecularly imprinted polymer (MIP) electrodeposited by cyclic voltammetry on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNT). The electrodeposited polymeric films were characterized by infrared spectrometry (FTIR), scanning electron microscopy (SEM), and cyclic voltammetry (CV). The analyses conducted using differential pulse voltammetry (DPV) yielded a detection limit of 2.7 × 10-9 mol L-1 for methotrexate, a linear range of 0.01-125 μmol L-1, and a sensitivity of 0.152 μA L mol-1. The results obtained from the analysis of the selectivity of the proposed sensor through the incorporation of interferents in the standard solution pointed to an electrochemical signal decay of only 15.4%. The findings of this study show that the proposed sensor is highly promising and suitable for use in the quantification of methotrexate in environmental samples.

Analyzing the Bolometric Performance of Vanadium Oxide Thin Films Modified by Carbon Nanotube Dispersions

The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of VOx films is investigated. For a critical range of the CNT dispersion density on VOx films, the intrinsic properties of the VOx films are modified by the CNTs. The CNT concentrations reported in this work are about 0.3 μg/cm2 and 1.6 μg/cm2, allowing for low density and high density dispersions on the VOx film surface to be investigated. These values are higher than the percolation threshold of about 0.12 μg/cm2 for these films. The composite film exhibits a significant reduction in the temperature coefficient of resistance (TCR) (from ≈3.8% K-1 to ≈0.3% K-1) for high density dispersions. In contrast, while VOx-CNT composites with low density single wall CNT dispersions exhibit no significant change in TCR values, an approximate two orders of magnitude reduction in the low frequency 1/f noise is measured. The noise signal amplitude measured at 0.1 V and at 1.0 Hz reduces from 6 × 10-5V/(Hz) for VOx films to 5 × 10-7V/(Hz) for the low density SWCNT dispersion on VOx film and to 3 × 10-6V/(Hz) for the low density MWCNT dispersion on VOx film. The CNT concentration is the critical factor for yielding the observed changes in conductivity and low frequency noise. The results presented in this work provide a better understanding of VOx-based composites, thereby enabling the development of new, versatile and functional materials for device applications.

A novel preparation and characterization of electroless NiP/MWCNT composite coated UHMWPE fabric in terms of wettability, electrical conductivity, thermal stability and breaking load resistance

Poor wettability results in fragile bonding between the ultra-high molecular weight polyethylene (UHMWPE) fabric and matrix of the composites. To overcome this issue, the present study proposes a novel approach for the deposition of electroless nickel-phosphorus (NiP) and nickel-phosphorus/multi walled carbon nanotube (NiP/MWCNT) coating on the surface of UHMWPE. The influence of coatings on the morphology, phase structure, crystal size, functional groups, surface roughness, wettability, water absorption property, electrical conductivity, thermal stability, peeling load and breaking load of UHMWPE fabric are detailed. After MWCNT was reinforced, the cauliflower structure reported for NiP coated UHMWPE (NiP-UHMWPE) was altered for NiP/MWCNT-coated UHMWPE (NiP/MWCNT-UHMWPE). The crystal size of NiP has slightly increased to 1.307 nm for NiP/MWCNT-UHMWPE from 1.22 nm of NiP-UHMWP. The contact angle of NiP-UHMWPE (84.36°) was relatively lower than the NiP/MWCNT-UHMWPE (92.46°) and UHMWPE (102°), due to the formation of more nickel globules in the surface of NiP-UHMWPE. Though the wettability was high for the NiP and NiP/MWCNT coating, the water absorption percentage has not increased for NiP-UHMWPE and NiP/MWCNT-UHMWPE. The electrical conductivity was improved for NiP/MWCNT-UHMWPE after the reinforcement of MWCNT. The breaking load of the NiP and NiP/MWCNT coated UHMWPE fabric improved by 6.24% and 12.11% respectively. The more detailed study in terms of functional group, crystal structure, compounds, electrical conductivity, thermal stability, peeling load, and tensile failure analysis of coated UHMWPE fabric are reported in this article.

Effect of different concentration of Single and Multi -Walled Carbon Nanotubes in liver texture and hepatic enzymes in the New Zealand white rabbit

The aim of the present study was to investigate the effect of variable doses of single and multiwalled carbon nanotubes (SWCNTs and MWCNTs) instilled intratracheally on texture of liver and hepatic enzymes ,alanine amino transferase (ALT) and aspartate amino transferase (AST) in New Zealand white rabbits. In this study was used 70 males New Zealand white rabbits, their ages range between (12-18 months) divided into seven groups, ten for each group which instilled with Nanoparticles, At days 7 and 90 post exposure, The blood and tissue samples were collected for each group.
 Instillation of SWCNTs ( 1 or 5 mg/ml/kg (b.w) or MWCNTs (1,3or 5 mg/ml/kg b.w) in the trachea of rabbits induced a significant increase in activity of ALT and AST.
 Translocation of carbon nanotubes was seen from the lungs to the liver. It was concluded that: SWCNTs and MWCNTs induced hepatic injuries through its effect in activity of hepatic enzyme and the nanotubes translocated from the lung to the liver and pleura.
 

Computational molecular design to assist modification of single – walled carbon nanotubes with B, N, Al, Si, P, and S dopant atoms for Cl2 gas sensor application

Chlorine (Cl2) gas is toxic to humans. Exposure to this gas can cause skin and eye irritation, suffocation, and even death if a person is continuously exposed to Cl2 gas at high concentrations. Therefore, it is necessary to develop a detection sensor to minimize its impact. In this study, pristine Single-Walled Carbon Nanotubes (SWCNT) and SWCNT doped with Boron (B), Nitrogen (N), Aluminum (Al), Silicon (Si), Phosphorus (P), and Sulfur (S) dopant atoms were tested as sensors for Cl2 gas detection. The results show that the reaction between SWCNT and Cl2 gas is exothermic and occurs spontaneously. The bond distance formed between the Cl and B atoms in B-doped SWCNT is the shortest compared to other systems. The addition of B dopant atoms can also improve the electronic properties of the SWCNT. Furthermore, the addition of Al and Si atoms as dopants to the SWCNT also resulted in a high adsorption activity. From these results, it was concluded that B, Al, and Si dopants were the most effective dopants used to enhance the sensitivity of SWCNT to chlorine gas.

A green and novel strategy based on CO2 -responsive surfactant-functionalized multi- walled carbon nanotubes with microwave- ultrasound assistant to improve extraction and enrichment of phytochemicals from plant waste

In this study, a noval method was developed based on CO2 -responsive surfactant-functionalized multi-walled carbon nanotubes with microwave -ultrasound assistance extraction (CRS-MWN-MUAE) for obtain value-added compounds from plant waste. The single-factor experiments were applied to obtain the best experiment conditions: ultrasound power of 600 W, ultrasound time of 25 min, microwave time of 20 min, microwave power of 500 W, solid-to-liquid ratio of 20 mg/mL, and multi-walled carbon nanotubes (MWN) concentration of 4 g/L. The representative flavonoid and stilbene from pigeon pea leaves were orientin and cajaninstilbenes acid (CSA). The representative triterpenoid from cili fruits was roxburic acid. The representative flavonoid from cili leaves was quercetin. The representative anthocyanin from blackcurrant fruits was cyanidin 3-O-glucoside (C3G). The representative organic acid from blackcurrant leaves was chlorogenic acid. The orientin, CSA, roxburic acid, quercetin, C3G, chlorogenic acid extraction yields were: 4.42 mg/g, 9.43 mg/g, 1.56 mg/g, 0.15 mg/g, 2.24 mg/g, and 1.07 mg/g. Under these conditions, the solvent system possessed higher efficiencies from various plant wastes compared with other extraction method. The contents of target compounds have increased 1.1–20 folds. Meanwhile, the green surfactants could be recycled and achieved no significant loss in six operation cycles. Moreover, density functional theory and molecular dynamics simulation investigated the surfactant could be well compatible with target compounds because of the weak interactions among moleculars. Thus, the method was a green, efficient, novel, and ecofriendly extraction method for extracting and enriching high value-added compounds from cili, pigeon pea, and blackcurrant wastes.

Water filling in carbon nanotubes with different wettability and implications on nanotube/water heat transfer via atomistic simulations

The peculiar heat and mass transfer properties of Carbon Nanotubes (CNTs) envision promising applications in nanoengineering and nanofluidic devices, such as heat sinks and desalination membranes. However, a comprehensive understanding of the intertwined effects of mass transfer (entrance and exit of liquid molecules inside CNTs) and heat transfer mechanisms (thermal exchange at the CNT/solvent interface) as a function of the properties of CNT surface is currently incomplete. In this work, we use molecular dynamics simulations to study heat and mass transfer in single wall CNTs with (5,5) and (10,10) chirality immersed in water. We present a sensitivity analysis where, starting from different choices of interaction potentials between CNTs and water molecules, we deduce the corresponding CNT/water wetting parameters, we model fill-in and fill-out water dynamics and arrangement of water molecules at the equilibrium. Spontaneous water entrance into CNTs is examined and a single energy parameter to model water filling is introduced. Secondly, we compute the CNT/water thermal boundary resistance for the different wetting properties. In perspective, this work supports a more rational design of CNT-based devices operating in nanothermal and nanobiological environments.

Regulation binary electromagnetic filler networks in segregated poly(vinylidenefluoride) composite for absorption‐dominated electromagnetic interference shielding

AbstractExcellent conductivity and optimized impedance matching are vital for superior absorption‐dominated electromagnetic interference (EMI) shielding. An efficient binary electromagnetic filler network regulation method has been proposed. Poly‐ (vinylidenefluoride)‐ferroferric oxide‐reduced graphene oxide/single‐wall carbon nanotube (PVDF‐Fe3O4‐RGC) composite has been synthesized as a layered segregated polymer composite structure by using an electrostatic assembly and hot compression strategy. Binary electromagnetic filler networks have surpassed the obstacles of magnetic materials in conductive networks, and are thereby beneficial for outstanding conductivity and impedance matching. Therefore, a superior conductivity of 1.28 S cm−1 and an outstanding electromagnetic shielding interference and effectiveness of 44.5 dB have been obtained for loading of 2.02 vol.% single‐wall carbon nanotubes (SWCNTs), with an absorption rate larger than 85.0% in the X‐band. The enhanced EMI shielding performance is attributed to the regulation of the binary electromagnetic filler network.

Pressure-driven flow behavior of small molecules through a carbon nanotube

In this research, the flow behavior of ring and chain molecules through a carbon nanotube (CNT) driven by pressure has been investigated using molecular dynamics (MD) simulations. We have examined the distribution of fluid molecules and the flow process confined in the CNT. We also calculated the radial count profiles, the axial density distributions, molecular conformation and fluid flux. Our results revealed that a sudden pressure applied on fluid molecules will lead to inrush of fluid inside nanoscale channels. The fluid molecules confined in the CNT formed an interfacial layer near the CNT inner surface. That of toluene system is closer to the CNT wall than heptane system. The results also indicated that plane of toluene molecules in interfacial layer is parallel to the CNT wall. The distributions of the others are disordered. The heptane molecules formed four cylindrical layers inside the CNT. The molecules in interfacial layer are parallel to the CNT wall.

Hydrogen Bond Dynamics and Phase Transitions of Water inside Carbon Nanotubes.

Water dynamics in nanochannels are altered by confinement, particularly in small carbon nanotubes (CNTs). However, the mechanisms behind these effects remain unclear. To address these issues, we carried out extensive molecular dynamics (MD) simulations to investigate the structure and dynamics of water inside CNTs of different sizes (length of 20 nm and diameters vary from 0.8 nm to 5.0 nm) at different temperatures (from 200 K to 420 K). The radial density profile of water inside CNTs shows a single peak near the CNT walls for small nanotubes. For CNTs with larger sizes, water molecules are arranged into coaxial tubular sheets, the number of which increases with the CNT size. Subdiffusive behavior is observed for ultranarrow CNTs with diameters of 0.8 nm and 1 nm. As the size of CNTs increases, Fickian diffusion becomes evident. The hydrogen bond correlation function of water inside CNT decays slower than in bulk water, and the decay rate decreases as we increase the diameter of the CNTs. In large CNTs, the hydrogen bond lifetime of the innermost layer is shorter than the other layers and depends on temperature. Additional analysis of our results reveals that water molecules along the CNT axis show a non-Arrhenius to Arrhenius diffusion crossover. In general, the diffusion transition temperature is higher than that of bulk water, but it depends on the size of the CNT.

Enhancing thermoelectric performance of single-walled carbon nanotube/reduced graphene oxide composites with small organic molecules as a novel additive

Intercalating 1 into a composite of single-walled carbon nanotubes (SWCNTs) and reduced graphene oxides achieved a ZT over 6.8 × 10−3, 2.3 times higher than SWCNTs (2.9 × 10−3), by improving Seebeck coefficient and reducing thermal conductivity.

Sequential exposures of single walled carbon nanotubes and heavy metal ions to macrophages induce different cytotoxicity

The probability of occupational exposure rises with the increasing production and biomedical application of carbon nanotubes (CNTs). Thus, the risk of co-exposure of nanomaterials with environmental pollutants is also increasing. Although many studies have focused on the combined toxicity of nanomaterials and pollutants, more attention has been paid to the toxicity of nanomaterials after adsorbing pollutants or the toxicity of nanomaterials and pollutants exposed simultaneously. Few studies have been conducted on the toxicity and toxicity mechanisms of nanomaterials and environmental pollutants following sequential exposure. In this study, we employed THP-1 cells to investigate how pristine single walled CNTs (p-SWCNTs) and oxidized single walled CNTs (SWCNT-COOHs) pretreatments at a non-lethal dose of 10 μg/mL affect cell responses to metal ions (i. e., Pb2+, Cu2+, and Cr(VI)). We found that p-SWCNTs caused more significant damage to cell membrane integrity than SWCNT-COOHs, which led to higher metallothionein (MT) levels and increased transport of metal ions into cells. Pretreatment of p-SWCNTs in cells significantly increased the cytotoxicity of Pb2+, Cu2+, and Cr(VI) by 2–4-fold, whereas SWCNT-COOHs pretreated cells showed no noteworthy changes in response to heavy metals, which were further confirmed by the cellular reactive oxygen species (ROS) assays. These findings indicate that understanding the effects of the exposure sequence of engineered nanomaterials and environmental pollutants on their toxicity provides an excellent complement to combined toxicity evaluation.

Melting heat transport in a mixed convective squeeze flow of a hybrid nanofluid with interfacial nanolayer effects

AbstractThe interfacial nanolayer effect on a mixed convection flow of single wall CNT (carbon nanotube) and CuO (cupric oxide) water based hybrid nanofluid inside a squeezed channel is studied. To maintain the flow, hybrid nanofluid under consideration is either squeezed or dilated in the parallel plate channel. Melting heat condition on one side of the channel is taken. Generalized thermophysical models which include the interfacial nanolayer effects are proposed for the hybrid nanofluid. Governing equations for the flow are tackled via similarity mappings and bvp4c technique. Statistical analysis revealed a strong significance of the interfacial ratio parameters with Nusselt numbers and skin friction coefficients at both ends of the channel. In case of squeezing flow, it is interestingly noted that the melting parameter uplifted the heat transfer rate, however reverse trend prevailed for dilating flow regime. Mixed convection parameter declined the rate of heat transfer in the squeezing channel, but elevated the coefficient of skin friction.