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This paper explores an ontological version of 'abstraction' as it manifests in the commonalities and differences across social scientific research events. Drawing on a range of writings that focus on the potentiality of the event, on Whitehead's concept of the 'eternal object', and on the notion of attractor as discussed by DeLanda, the notion of abstractor' is tentatively proposed. The aim is to show how abstractors introduce particular potentialities, or 'lineages of becoming'. However, in the specific context of the research event, these abstractors are subject to modes of care (with their own linages of becoming) that inform how analysts might engage with the potentialities of a research event (understood as an inventive problem space). This broad schema is initially illustrated through a particular abstractor, that of the 'blackest black' as partially actualized in the nanotechnology VANTAblack. Subsequently, the case of VANTAblack is used to prompt a number of heuristic questions with regard to how we might practically and carefully explore the commonalities and differences across research events. The paper closes with reflections on the broader status of the approach sketched here. [ABSTRACT FROM AUTHOR]

Abstract In this work, a carbon nanotube junctionless tunnel field-effect transistor has been proposed and investigated. The presented structure uses two isolated gates with the same work function (main gate (MG) and P-gate (PG)) which are separated by a 3 nm SiO 2 spacer. PG has a constant voltage and a constant length of 0.4 V and 12 nm, respectively which has been used for electrically activation of the source region to behave like a tunnel FET. Simulations show that in comparison with the conventional carbon nanotube tunnel field-effect transistor (CNT-TFET) and carbon nanotube tunnel field-effect transistor with hetero-gate dielectric (HGD-CNT-TFET) suggested structure has significant higher ON current and improvement in ambipolar behavior. Furthermore, analog characteristics like unity gain frequency ( f t ) and transconductance ( g m ) have been improved considerably. [ABSTRACT FROM AUTHOR]

This paper presents two new 4:2 compressors based on capacitive multi-threshold threshold logic (MTTG), and Carbon Nanotube Field Effect Transistors (CNFETs). The entire capacitor network is divided into two groups in one of the proposed designs. As a result, the number of voltage levels is reduced and the entire structure becomes less sensitive to Process, Voltage, and Temperature variations in comparison with other similar capacitive Threshold Logic (TL) circuits. All designs are simulated by Synopsys HSPICE and 32 nm CNFET technology in different situations and conditions. Simulation results demonstrate the superiority of the second proposed design. It operates 55.9% faster and consumes about 7.2% less power than the second best TL structure (CSTFA). It also operates 16.2% faster and consumes 13.6% less energy in comparison with a traditional design (BLG). Moreover, estimations show that the first proposed design occupies the least area among the capacitive TL circuits. [ABSTRACT FROM AUTHOR]

Flexural and axial wave propagation in double walled carbon nanotubes embedded in an elastic medium and axial wave propagation in single walled carbon nanotubes are investigated. A length scale dependent theory which is called doublet mechanics is used in the analysis. Governing equations are obtained by using Hamilton principle. Doublet mechanics results are compared with classical elasticity and other size dependent continuum theories such as strain gradient theory, nonlocal theory and lattice dynamics. In addition, experimental wave frequencies of graphite are compared with the doublet mechanics theory. It is obtained that doublet mechanics gives accurate results for flexural and axial wave propagation in nanotubes. Thus, doublet mechanics can be used for the design of electro-mechanical nano-devices such as nanomotors, nanosensors and oscillators. [ABSTRACT FROM AUTHOR]

This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs) as sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT) strands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor is demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by suspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of silver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive TCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current was applied between the two prongs. This sensor can evidently respond to flow rate, and requires only several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor has better sensitivity than the Pt-coated DWCNT sensor. [ABSTRACT FROM AUTHOR]

The article discusses the features of carbon nanotube (CNT) and rubber composites and their uses. It cites the techniques by which CNT can be used as a rubber filler, which include the use of rubber emulsion polymerisate to recover the rubber and the dispersion of CNT in an organic solvent. It cites the electroconductivity features of CNT.

The degradation of polyurethane by diethylenetriamine was studied. IR spectroscopy and gas-liquid chromatography coupled with mass spectrometry were used to establish the structure of the degradation products of polyurethane. [ABSTRACT FROM AUTHOR]

Aim of the work: this study evaluated the efficacy of bone marrow (BM) transplantation to protect male rats from dangerous effect of multi-walled carbon nanotubes (MWCNTs) or/and γ-irradiation on the hematopoietic and lung tissues. Materials and methods: experimental animals were divided into 8 groups each consist of 6 male albino rats. Control group, BM-injected group, MWCNTs-injected group, 5Gy γ-irradiated group, 5Gy γ-irradiated+ MWCNTs-injected group, MWCNTs-injected+ BM-injected group, 5Gy γ-irradiated+ BM-injected group and 5Gy of γ-irradiated+ MWCNTs-injected + BM-injected group. All the treated animal groups were sacrificed after 28 days of the treatments. Blood components, MDA and GSH levels in the lung tissue were analyzed. The histopathological study in the lung tissue was also recorded. Results: exposure to MWCNTs or/and γ-radiation induced a significant decrease in certain blood components (WBCs, RBCs, Hb content, HCT value and PLT count). Furthermore, a significant elevation in MDA level and a significant decrease in GSH content were detected in the lung tissue. The histopathological changes after exposure of rats to MWCNTs recorded perivasculitis, atelectasis and interstitial pneumonia. Also, γ-radiation represented more collapsed and thickened walls in the alveoli, thickened bronchiolar walls with partial epithelial lining and foci of pulmonary hemorrhage in the lung tissue. The effect of BM transplantation after MWCNTs or/and γ-radiation ameliorated the values of blood components, MDA and GSH levels in the lung tissue. The improvement occurred by BM transplantation in rats treated with MWCNTs or/and exposed to γ-radiation were also recorded. The lung tissue showed numerous alveoli with thin interalveolar septa, alveolar sacs and terminal bronchioles with highly folded mucosa. Conclusion: treatment with BM transplantation improved the most deleterious parameters obtained in the blood and lung tissue of MWCNTs exposed or/and γ-irradiated rats. [ABSTRACT FROM AUTHOR]

A flexible enzymatic acetylcholinesterase biosensor based on an electrolyte-gated carbon nanotube field effect transistor is demonstrated. The enzyme immobilization is done on a planar gold gate electrode using 3-mercapto propionic acid as the linker molecule. The sensor showed good sensing capability as a sensor for the neurotransmitter acetylcholine, with a sensitivity of 5.7 μA/decade, and demonstrated excellent specificity when tested against interfering analytes present in the body. As the flexible sensor is supposed to suffer mechanical deformations, the endurance of the sensor was measured by putting it under extensive mechanical stress. The enzymatic activity was inhibited by more than 70% when the phosphate-buffered saline (PBS) buffer was spiked with 5 mg/mL malathion (an organophosphate) solution. The biosensor was successfully challenged with tap water and strawberry juice, demonstrating its usefulness as an analytical tool for organophosphate detection. [ABSTRACT FROM AUTHOR]

A novel method was used to synthesize a nanosilver-doped multiwall carbon nanotube (MWCNT-Ag), and subsequently, the novel poly(lactic acid) (PLA)- and MWCNT-Ag-based biocompatible and antimicrobial nanocomposites were prepared by melt blending. Based on energy dispersive X-ray spectrometry images, an MWCNT-Ag was successfully synthesized. The effect of the MWCNT-Ag on the PLA bionanocomposites was investigated by evaluating their thermal and mechanical properties, antifungal activity, and cytotoxicity. The nanocomposites exhibited a high degree of biocompatibility with the MWCNT-Ag content, which was less than 0.3 phr. Furthermore, tensile strength testing, thermogravimetric analysis, differential scanning calorimetry, and antibacterial evaluation revealed that the tensile strength, thermostability, glass transition temperature, and antibacterial properties were enhanced by increasing the MWCNT-Ag content. Finally, hydrolysis analysis indicated that the low MWCNT-Ag content could increase the packing density of PLA. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a fibrous assembly of carbon nanotubes (CNTs) induced by a gas discharge breakdown that bridge the distance between two planar electrodes. To achieve this, we placed the two planar electrodes, one of which was covered with a CNT film, in a chamber; a vacuum pump was used to evacuate the air from the chamber and replace it with inert gas. By then applying a voltage between the electrodes, we induced a discharge breakdown between them. This caused the CNTs coated on the electrode surface to detach and form fibrous assemblies. The assemblies elongated and reached the opposite electrode, thereby creating bridges between the electrodes. These bridges formed when the gas pressure was greater than ca. 1.0×103Pa and in combination with the occurrence of a spark discharge. At lower pressures, a glow discharge occurred, and no bridge formation was observed, indicating that the discharge mode is critical for the bridge formation. [ABSTRACT FROM AUTHOR]

Since its introduction in 1990s, solid-phase microextraction (SPME) has grown increasingly popular due to its simplicity, environmental benignity and adaptability to a wide variety of sample types and analytes. The application of carbon nanotubes (CNTs) in SPME is receiving great attention since their introduction would bring an enhancement of partition coefficient, an increasement of diffusion coefficients and better selectivity to the target analytes. CNTs have been feasibly applied in almost all of the developed configurations of SPME technique such as fiber SPME, thin-film SPME, in-tube SPME, stir-bar microextraction, in-needle SPME and in-tip SPME. The objective of this literature review is to elucidate the advances of the configurations of CNTs based SPME techniques and their applications in the environmental analysis. [ABSTRACT FROM AUTHOR]

The colloidal stability of carbon nanotube (CNT) in water is an important property for several applications. Three different functionalization approaches defined as nondestructive techniques have been carried out to modify the CNT surface and the product CNT compared. First, admicellar polymerization is used to form a water-soluble polymer on CNT with two different polymers, polyacrylic acid and polyvinyl acetate (PVAc). Second, coatings of soluble biopolymers are applied using dextran and chitosan. Third, mild acid oxidation conditions from the literature are employed with hydrogen peroxide (H2O2) and with potassium permanganate (KMnO4) as oxidizing agents. The colloidal stability of modified CNT is examined by sedimentation and by turbidity measurements along with laser particle size analysis. Thermogravimetric Analysis, energy dispersive X-ray analysis, scanning electron microscope, and transmission electron microscopy are used to confirm that modification of the CNT is successfully implemented with each technique. Lastly, FT-Raman is used to assess damage to the CNT structure after modification. A focus of the turbidity measurements is quantitative analysis using numerical integration of variability to evaluate colloidal stability. All modified CNT samples clearly yield improved aqueous dispersions. For each of the three approaches, the better option is KMnO4 for mild acid oxidation, PVAc for admicellar polymerization, and chitosan for biopolymer deposition. [ABSTRACT FROM AUTHOR]

Multi wall carbon nanotube (MWNT) sponges were synthesized with a domestic microwave oven. The procedure involves a mixture of graphite and cobalt acetate powders enclosed in an evacuated quartz ampoule exposed to microwave irradiation. Maximum yield of MWNT sponges of about 2.2 cm is obtained within 12 min of microwave exposure with individual MWNTs having diameters in the 20-50 nm range. Employing MWNT obtained from synthesized sponges we construct two types of organic transistors: a field effect OFET device in which the channel material is a MEH-PPV semiconducting polymer blended with the synthesized MWNT, and a light emitting transistor OLET device in which electrodes are prepared with MWNT, the channel material being the MEH-PPV polymer alone. These devices are characterized with I-V measurements. For the OFET device the I/I figure is considerably improved by using the polymer/MWNT blend as channel. In the OLET device, I-V characteristics with MWNT electrodes are comparable to those obtained when ITO electrodes are used. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are newly developed materials with unique properties and a range of industrial and commercial applications. A rapid expansion in the production of CNT materials may increase the risk of human exposure to CNTs. Studies in rodents have shown that certain forms of CNTs are potent fibrogenic inducers in the lungs to cause interstitial, bronchial, and pleural fibrosis characterized by the excessive deposition of collagen fibers and the scarring of involved tissues. The cellular and molecular basis underlying the fibrotic response to CNT exposure remains poorly understood. Myofibroblasts are a major type of effector cells in organ fibrosis that secrete copious amounts of extracellular matrix proteins and signaling molecules to drive fibrosis. Myofibroblasts also mediate the mechano-regulation of fibrotic matrix remodeling via contraction of their stress fibers. Recent studies reveal that exposure to CNTs induces the differentiation of myofibroblasts from fibroblasts in vitro and stimulates pulmonary accumulation and activation of myofibroblasts in vivo. Moreover, mechanistic analyses provide insights into the molecular underpinnings of myofibroblast differentiation and function induced by CNTs in the lungs. In view of the apparent fibrogenic activity of CNTs and the emerging role of myofibroblasts in the development of organ fibrosis, we discuss recent findings on CNT-induced lung fibrosis with emphasis on the role of myofibroblasts in the pathologic development of lung fibrosis. Particular attention is given to the formation and activation of myofibroblasts upon CNT exposure and the possible mechanisms by which CNTs regulate the function and dynamics of myofibroblasts in the lungs. It is evident that a fundamental understanding of the myofibroblast and its function and regulation in lung fibrosis will have a major influence on the future research on the pulmonary response to nano exposure, particle and fiber-induced pneumoconiosis, and other human lung fibrosing diseases. [ABSTRACT FROM AUTHOR]

This work shows evidence of conventional liquid and polymer molecules doping macroscopic yarns made up of carbon nanotubes (CNT), an effect that is exploited to monitor polymer flow and thermoset curing during fabrication of a structural composite by vacuum infusion. The sensing mechanism is based on adsorption of liquid/polymer molecules after infiltration into the porous fibers. These molecules act as dopants that produce large changes in longitudinal fiber resistance, closely related to the low density of carriers near the Fermi level of bulk samples of CNT fibers, reminiscent of their low-dimensional constituents. A 25% decrease in fiber resistance upon exposure to electron-donor radicals formed during epoxy vinyl ester polymerization is shown as an example. At later stages of curing the matrix undergoes shrinkage and applies a compressive stress to the fibers. The resulting sharp increase in electrical resistance provides a mechanism for detection of the matrix gel point. The kinetics of resistance change during polymer ingress are related to established models for macromolecular adsorption, thus also enabling prediction of polymer flow. This is demonstrated for vacuum infusion of a 150 cm2 glass fiber laminate composite, with the CNT fiber yarns giving accurate prediction of macroscopic resin flow according to Darcy's law. [ABSTRACT FROM AUTHOR]

We briefly review our recent works on addressing the dispersion obstacle of carbon nanotubes (CNTs) in a ceramic material and on the in situ characterization of the direct reinforcing mechanism and properties of multi-walled CNTs when intimately embedded in a ceramic matrix. In particular, we discuss the new reinforcing mechanism at the nanoscale responsible for unprecedented, simultaneous mechanical improvements, and highlight the scalable processing method enabling fabrication of defect-free CNT-concentered and CNT-graded composites with unprecedented properties. [ABSTRACT FROM AUTHOR]

Broadband dielectric/electric properties of multiwalled carbon nanotubes (MWCNT) polymethylmetacrylate composites were studied in a wide temperature range (25-400 K). It was established that the percolation threshold is lower in composites with the shortest MWCNT, due to the better distribution of the MWCNT in the polymer matrix. The value of the dielectric permittivity and the electrical conductivity below the percolation threshold is also higher in composites with the shortest MWCNT. Below the percolation threshold the dielectric dispersion in composites is mainly related with the β relaxation in the polymer matrix. The length of the MWCNT and its concentration have also the huge influence on polymer matrix molecular dynamics, the relaxation time is shortest in composites with the higher MWCNT concentration and in composites with the shortest MWCNT. At low temperatures the conductivity of composites above the percolation threshold is governed by an electron tunneling between MWCNT clusters. At higher temperatures the electrical transport occurs also due to the finite electrical conductivity of the polymer matrix. [ABSTRACT FROM AUTHOR]

A facile strategy has been developed to fabricate silver nanoparticles (Ag NPs) through an electrochemical method with the assistance of metformin functionalized MWCNT (Ag@MH/MWCNT nanocomposite). Investigations by field emission scanning electron microscopy (FESEM) confirmed that the prepared nanocomposite have a porous structure that is constructed by interconnecting functionalized MWCNT framework. Electrochemical studies show that the nanocomposite exhibits high stability and excellent activity for electrocatalytic oxidation of glucose in alkaline solutions, which allows the Ag@MH/MWCNT to be used in enzyme-free amperometric sensors for glucose determination. It was confirmed that the Ag@MH/MWCNT based glucose biosensor presents wide response window for glucose concentrations of 1.0 nM–350 μM, short amperometric response time (4 s), low detection limit of 0.0003 μM (S/N = 3), high sensitivity as well as good selectivity. [ABSTRACT FROM AUTHOR]

This work reports the non-covalent functionalization (dispersion) of multi-walled carbon nanotubes (MWCNTs) with cytochrome c (Cyt c), the direct electron transfer (DET) after drop-coating deposition of MWCNTs-Cyt c dispersion on glassy carbon electrodes (GCE), and the analytical applications for the highly sensitive quantification of hydrogen peroxide. The dispersion and the resulting modified electrodes were studied by UV–visible spectroscopy, scanning electron microscopy, and electrochemical techniques. The drastic treatment for dispersing the MWCNTs (5.0 min sonication in water with ultrasonic tip) produces a partial denaturation that facilitates the interaction of Cyt c with the CNTs and makes possible an efficient electron transfer between the heme group and the electrode. A critical analysis of the influence of different experimental conditions on the efficiency of the dispersion and on the performance of GCE modified with MWCNTs-Cyt c dispersion is also reported. The analytical parameters obtained with GCE/MWCNTs-Cyt c for the amperometric quantification of hydrogen peroxide at −0.100 V were: sensitivity of (43 ± 1) mA M −1 cm −2 , linear range between 1.0 × 10 −6 and 1.6 × 10 −4 M, detection limit of 1.5 × 10 −7 M, reproducibility of 3.1% and repeatability of 3.4%. The biosensor was successfully used for the quantification of hydrogen peroxide in mouthwash and spiked milk samples. [ABSTRACT FROM AUTHOR]

This work mainly reports on the effects of the aspect ratio and waviness index of carbon nanotubes (CNTs) on the free vibration and stress wave propagation of functionally graded (FG) nanocomposite cylinders that are reinforced by wavy single-walled carbon nanotubes based on a mesh-free method. In this simulation, an axisymmetric model is used, three linear types of FG distributions of wavy CNTs along the radial direction of the cylinder are considered and their results are compared with the results of a uniform distribution. The material properties are estimated by a micromechanical model. In the mesh-free analysis, moving least squares shape functions are used for approximation of the displacement field in the weak form of motion equation and the transformation method was used for the imposition of essential boundary conditions. Also, the effects of volume fraction and distribution pattern of wavy CNTs and cylinder thickness are investigated on the natural frequency and stress wave propagation of carbon nanotube reinforced composite (CNTRC) cylinders subjected to an impact load. It is observed that waviness has a significant effect on the dynamic behavior of the CNTRC cylinders. [ABSTRACT FROM AUTHOR]

The nanohybrids TiO 2 /CNTs materials were synthesized by hydrolysis method. The results show that, compared to pure TiO 2 or CNTs nanoparticles, nanohybrids TiO 2 /CNTs materials exhibit higher catalytic activities in degradation of methylene blue (MB), or methylene orange (MO). The highest degradation percentages, observed in samples with [TiO 2 ]/[CNTs] ratio of 5/1, are around 33% for MO and 38% for MB, respectively. This can be attributed to the significantly enhanced visible light absorption of nanohybrids TiO 2 /CNTs due to the attachment of the TiO 2 nanoparticles on the sidewall of CNTs. The density functional-theory (DFT) calculations indicate that the stability of nanohybrids TiO 2 /CNTs is due to the favored bonding state between nanocrytal TiO 2 and CNTs at the interface. Hopefully, this work can help promote better understanding of the role of semiconductor-CNTs interface in increasing the efficiency of using the solar energy, by enhancing the photocatalytic performance in the visible region. [ABSTRACT FROM AUTHOR]

Polycarbonate (PC)/multiwall carbon nanotube (MWCNT)/composites were prepared by melt mixing and subsequently melt spun to monofilament fibers. Electrical, mechanical and piezoresistive (strain sensing) properties of the fibers were evaluated as a function of the MWCNT weight concentration, which was varied up to 6 wt%. After the incorporation of MWCNTs, a decrease in electrical resistivity of the fibers was found for MWCNT concentrations as low as 2 wt%. Furthermore, an important effect of the draw down ratio (DDR) on the electrical properties of the fibers was observed. While the electrical percolation threshold (φ c ) for the bulk material was <1 wt% and ∼1 wt% for the undrawn-extruded rods, for the melt-spun fibers φ c was found to be highly dependent on the DDR. Stiffness and offset yield stress of the MWCNT/PC fibers were increased starting with the addition of 1 wt% of MWCNTs. However, decreased spinnability was observed for fibers with MWCNT concentrations above 4 wt%. The coefficient that relates the electrical resistance changes to the mechanical strain (strain gage factor S GF ) was estimated for fibers with MWCNTs amounts that range from 3.5 to 6 wt%. The highest S GF ∼16 was found at 3.5 wt% and the lowest S GF ∼2.5 at 6 wt% MWCNT. Smart multifunctional textiles, made from such conductive fibers, have wide applications such as structural health monitoring, detection of gases and liquids, sensor arrays and flexible sensors. [ABSTRACT FROM AUTHOR]

This study demonstrates the preparation of well aligned-carbon nanotube (WA-CNT) arrays onto a carbon paper substrate with a conductive carbon-black layer by the catalyst seed-impregnated chemical vapor deposition method. The prepared WA-CNT arrays were then characterized by scanning electron microscopy for different growth temperatures, standard linear velocities of feed vapors, and ferrocene-to-xylene ratios in the feed vapors. Results indicate that the optimal WA-CNT arrays of length 40–50 μm and diameter 30–40 nm were obtained at the growth temperature range of 750–800 °C, standard linear velocity of 1.40 cm s −1 , and ferrocene-to-xylene molar ratio of 1:50–1:30. These results provide new insights into the growth mechanism of CNT arrays, which involves cross-coupling of chemical reaction and mass transfer based on reaction engineering theory. The samples prepared in the study can be used as catalyst supports in air electrodes considering their three-dimensional porous structure, approximately linear channel, controllable length and diameter distribution, and excellent CNT conductivity. Electrochemical measurement indicated that the WA-CNT arrays/carbon-black layer/carbon paper substrate composites achieved relatively high discharge capacity of 2930 mAh g −1 (CNTs) at a current density of 0.05 mA cm −2 in Li–air batteries, which far exceeded other carbonaceous materials in Li–air batteries. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have attracted considerable interest due to their unique physical, chemical, optical and electrical properties opening avenues for a large number of industrial applications. They have shown potential as fire retardant additives in polymers, reducing heat release rate and increasing time to ignition in a number of polymers. Relevant work on the types, properties and applications has been reviewed particularly considering their application in fire situations. There are concerns over the health risks associated with CNTs and many papers have likened CNTs to the health problems associated with asbestos. There are contradictions relating to the toxicity of CNTs with some papers reporting that they are toxic while others state the opposite. Directly comparing various studies is difficult because CNTs come in many combinations of size, type, purity levels and source. CNTs can potentially be released from polymers during the combustion process where human exposure may occur. While this review has shed some light regarding issues relating to toxicity under different fire scenarios much more thorough work is needed to investigate toxicity of CNTs and their evolution from CNT–polymer nanocomposites in order to reach firm conclusions. [ABSTRACT FROM AUTHOR]

In the present paper free vibrations of embedded single-walled carbon nanotubes based on local Euler–Bernoulli beam theory are investigated. The surrounding elastic medium is described as the Winkler and Pasternak models, defined by the k w and k p coefficients. The Hamilton principle is applied to derive the governing equations and boundary conditions, which are solved by using the well-known Differential Quadrature Method (DQM). The influence of the elastic medium coefficients, nonlocal parameter and end supports on the free vibrations characteristics of the single-walled carbon nanotube (SWCNT) is described. Numerical examples are performed to show the accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

The impact of two types of multi-walled carbon nanotubes (MWCNTs) (12–14 nm) with different content of metallic impurities (purified and unpurified nanotubes) on peroxidation processes, the status of immune cells in healthy volunteers and gene expression combined to pathway analysis was studied in vitro . From the study it was shown that the main mechanism of action for both types of MWCNTs is induction of oxidative stress, the intensity of which is directly related to the amount of metallic impurities. Unpurified MWCNTs produced twice as high levels of oxidation than the purified CNTs inducing thus more intense mitochondrial dysfunction. All the above were also verified by gene expression analysis of 2 different human cellular cultures (lung epithelium and keratinoma cells) and the respective pathway analysis; modulation of genes activating the NFkB pathway is associated to inflammatory responses. This may cause a perturbation in the IL-6 signaling pathway in order to regulate inflammatory processes and compensate for apoptotic changes. A plausible hypothesis for the immunological effects observed in vivo , are considered as the result of the synergistic effect of systemic (mediated by cells of the routes of exposure) and local inflammation (blood cells). [ABSTRACT FROM AUTHOR]

Novel molecularly imprinted polymers (MIPs) on the surface of magnetic multi-walled carbon nanotubes (MMWCNTs) were prepared using dibenzothiophene (DBT) as template, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent and ammonium persulfate (APS) as initiator. The synthetic product was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). Batch mode adsorption studies were performed to evaluate the adsorption kinetics, adsorption isotherms, and selective recognition of MMWCNTs-MIP. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order equation. The pseudo-second-order exhibited the best fit for the kinetic studies ( R 2 = 0.9985), which indicates that chemisorption process limits adsorption of DBT. The adsorption equilibrium of DBT using MMWCNTs-MIP could be well-defined with the Langmuir isotherm model instead of the Freundlich isotherm model, and the maximum adsorption capacity was calculated as 47.8 mg g –1 . Compared with magnetic non-imprinted polymer (MNIP), magnetic MIP (MMIP) possessed a better adsorption property toward DBT, showing its potential for deep desulfurization. [ABSTRACT FROM AUTHOR]

As commercial interest in flexible power-conversion devices increases, the demand is growing for high-performance alternatives to brittle inorganic thermoelectric materials. As an alternative, we propose a flexible single-walled carbon nanotube (SWCNT)–doped tellurium nanowire (TeNW) hybrid film and, for the first time, rationally engineer the work function of the SWCNTs to effectively filter charge carriers in an energy-dependent manner at the interfaces between the carbon and the inorganic semiconductor. The acid treatment used to control the SWCNT work function allows the interfacial barrier between the SWCNT and the TeNW to be raised and lowered. While the hybrid film with a large barrier of 0.82 eV has a low power factor due to poor carrier transfer, the power factor (3.40 μW m −1 K −2 ) in the film with a lower barrier of 0.23 eV is several times higher than that of either pure TeNW or hybrid film with 0.82 eV due to effective energy filtering effect. The transport characteristics of the hybrid film are explored to quantitatively elucidate the carrier filtering at the SWCNT–TeNW interfaces. These demonstrate the effectiveness of optimizing SWCNT work functions to improve the thermoelectric properties of SWCNT/TeNW hybrid films, thus indicating that this strategy can be applied to flexible/or wearable thermoelectrics. [ABSTRACT FROM AUTHOR]

Monotonic and cyclic tensile loading experiments were conducted for analyzing elastoplastic deformation and failure of carbon nanotube (CNT) fibers. The deformation stages of the CNT fibers under tensile loads consist of a short elastic stage and a long-lasting plastic stage, while the elastic stage of the CNT fibers can be generally divided into two parts: a perfect-elastic stage and an elastic-like stage. Microstructural evolution for each deformation stage was interpreted by means of scanning electron microscope photos. An elastic limit and an offset yield point were discovered through the cyclic loading experiments. The elastic strain limit of the CNT fibers was determined at about 0.35% and the offset yield strain at about 1.2% for quasi-static loading. The effect of strain rates on the deformation and failure mode of CNT fibers was investigated as well. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are a promising material for the fabrication of biomimetic dry adhesives. The dimensions of single CNTs are in the range of those of terminal elements of biological dry hairy adhesion systems, such as the setal branches on the toe of the gecko. Here, the tribological properties of densely packed arrays of vertically aligned and up to 1.1 mm long multi-walled CNTs (VACNTs) synthesized by chemical vapor deposition are examined. The coefficient of friction μ is as high as 5–6 at the first sliding cycle, and decreases down to stable values between 2 and 3 at the fourth to fifth sliding cycles. Such high values of μ can only be explained by the strong contribution of adhesion induced by applied shear force. After the tests, wear-induced deformations of the VACNT surface are observed, which strongly depend on the amount of normal force applied during the friction experiments. Interestingly, the plastic deformation of the VACNTs does not significantly affect μ after a preconditioning by a few sliding cycles. However, a strong decrease of μ during the initial wear cycles has to be taken into account for the development of applications, such as non-slip surfaces and pick-and-place techniques for manufacturing. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymers (CFRP) have been increasingly used in aircraft structures. However, their relatively low electrical conductivity leads to the vulnerability to lightning strike. Herein, the carbon nanotube buckypaper-based coatings composed of conductive buckypaper and insulating adhesives were developed to protect the CFRP laminates. Their influence on the lightning strike protection (LSP) effectiveness was systematically studied and the possible mechanisms were discussed. It was demonstrated that the conductive layer of buckypaper could facilitate the lightning current to the ground and dissipate the energy. Moreover, a relatively thick insulating adhesive could hinder the transfer of the lightning current through the thickness direction to CFRP laminates, thus further enhance the LSP effectiveness. An optimized LSP coating developed in this work was composed of a ∼70 μm thick buckypaper and a ∼200 μm thick boron nitride modified epoxy insulating adhesive, which resulted in a weight reduction up to 30% compared to the commercial Cu LSP coating, and could sustain the simulated lightning strike with peak current up to 100 kA. [ABSTRACT FROM AUTHOR]

In the present work, forced convective heat transfer of water/functionalized multi-walled carbon nanotube (FMWCNT) nanofluid in a two-dimensional microchannel is investigated. To solve the governing Navier–Stokes equations and discritization of the solution domain, the numerical method of finite volume and SIMPLE algorithm have been employed. Walls of the microchannel are under a periodic heat flux, and slip boundary conditions along the walls have been considered. Effect of different values of shear forces, solid nanoparticles concentration, slip coefficient, and periodic heat flux on the flow and temperature fields as well as heat transfer rate has been evaluated. In this study, changes of the variables considered to be from 1 to 100 for Reynolds number, 0–25% for weight percentage of solid nanoparticles, and 0.001–0.1 for velocity slip coefficient. Results of the current work showed good agreement with the numerical and experimental studies of other researchers. Data are presented in the form of velocity and temperature profiles, streamlines, and temperature contours as well as amounts of slip velocity and Nusselt number. Results show that local Nusselt number along the length of microchannel changes in a periodic manner and increases with the increase in Reynold number. It is also noted that rise in slip coefficient and weight percentage of nanoparticles leads to increase in Nusselt number, which is greater in higher Reynolds numbers. [ABSTRACT FROM AUTHOR]

The carbon K-edge NEXAFS spectra of initial and fluorinated and hydrogenated single-wall carbon nanotubes (SWCNTs) are analyzed theoretically with regard to the polarization dependence. Differences in the polarized theoretical spectra of SWCNTs with zigzag and chair chiralities are shown. As a result of the comparison of experimental and theoretical carbon K-edge NEXAFS spectra of hydrogenated and fluorinated SWCNTs it is found that it is most probable that hydrogen atoms attach to the outer surface of the tube wall and fluorine atoms to the outer and inner surfaces of the SWCNT wall. Based on the analysis of polarized theoretical spectra of fluorinated and hydrogenated SWCNTs differences in the symmetry of the final states of C-H and C-F bonds are shown. [ABSTRACT FROM AUTHOR]

Over the past two decades, extensive research on single-walled carbon nanotubes (SWCNTs) has elucidated their many extraordinary properties, making them one of the most promising candidates for solution-processable, high-performance integrated circuits. In particular, advances in the enrichment of high-purity semiconducting SWCNTs have enabled recent circuit demonstrations including synchronous digital logic, flexible electronics and high-frequency applications. However, due to the stringent requirements of the transistors used in complementary metal-oxide-semiconductor (CMOS) logic as well as the absence of sufficiently stable and spatially homogeneous SWCNT thin-film transistors, the development of large-scale SWCNT CMOS integrated circuits has been limited in both complexity and functionality. Here, we demonstrate the stable and uniform electronic performance of complementary p-type and n-type SWCNT thin-film transistors by controlling adsorbed atmospheric dopants and incorporating robust encapsulation layers. Based on these complementary SWCNT thin-film transistors, we simulate, design and fabricate arrays of low-power static random access memory circuits, achieving large-scale integration for the first time based on solution-processed semiconductors. [ABSTRACT FROM AUTHOR]

Sulfonated carbon nanotubes (sCNTs) were prepared by reacting concentrated sulfuric acid with carbon nanotubes (CNTs) on the defect sites. Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) were used to characterize the morphology and structure of sCNTs, respectively. Subsequently, polyaniline (PANI)/nickel hexacyanoferrate (NiHCF)/sCNT interconnected composite films were electrodeposited on the platinum electrode by the one-step co-polymerization using cyclic voltammetry in an aqueous dispersion containing sCNTs. The effect of concentration of NiSO and KFe(CN) in the prepared solution on the morphology and structure of PANI/NiHCF/sCNTs composite films was studied by scanning electron microscopy (SEM), FTIR spectroscopy, and X-ray diffraction (XRD), respectively. The effect of concentration of NiSO and KFe(CN) in the prepared solution on polymerization and electrochemical performance was investigated by cyclic voltammetry (CV), galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy (EIS). One-step electrodeposition mechanism was discussed deeply. It was found that sulfonic acid groups had been attached to surface of CNTs, and sCNTs had higher dispersibility than CNTs in an aqueous dispersion. The morphology of PANI/NiHCF/sCNTs interconnected composite films was remarkably influenced by the concentration of NiSO and KFe(CN). The tubular packing structure appeared with the low concentration of NiSO and KFe(CN) in prepared solution, while the beautiful coral-like interconnected structure exhibited with 0.04 mol L NiSO and 0.04 mol L KFe(CN), which was mainly attributed to the π-π* electron stacking effect among sCNTs, NiHCF, and PANI. The specific capacitance and electroactivity of PANI/NiHCF/sCNTs composite films increased markedly with the increase of concentration of NiSO and KFe(CN) in prepared solution. The specific capacitance of PANI/NiHCF/sCNTs composite film was 430.77 F g with 0.04 mol L NiSO and 0.04 mol L KFe(CN) due to self-doping effect of sCNT in composite films. The cycle stability of PANI/NiHCF/sCNTs composite films was enhanced with the increase of NiSO and KFe(CN) in prepared solution. [ABSTRACT FROM AUTHOR]

A novel strategy for surface modification of multi-walled carbon nanotubes (MWCNT) was developed via combination of mussel inspired chemistry and Michael addition reaction. In this procedure, pristine MWCNT were first coated with polydopamine (PDA) through self polymerization of dopamine. The PDA functionalized CNT (CNT-PDA) were further functionalized with amino-terminated polymers (polyPEGMA), which were synthesized via free radical polymerization using cysteamine hydrochloride as the chain transfer agent and poly(ethylene glycol) monomethyl ether methacylate as the monomer. The successful modification of CNT was ascertained by a series of characterization techniques including transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis and X-ray photoelectron spectrometry. The polymer modified CNT showed enhanced dispersibility in aqueous and organic solution. Cytotoxicity evaluation of polymers modified CNT showed that these modified CNT are biocompatible with cells. Finally, due to the universal adhesive of PDA and chain transfer free radical polymerization, this strategy developed in this work can also be extended for surface modification of many other nanomaterials with different functional polymers. [ABSTRACT FROM AUTHOR]

There are various potential applications in which carbon nanotubes (CNTs) may be subjected to bending in a cantilevered configuration leading to buckling which in turn may affect their electrical, electronic as well as load bearing properties. Using atomistic simulations, we study buckling and post-buckling behavior of six single-walled CNTs subjected to bending in cantilever loading (i.e., flexure in addition to shear and axial compression). Starting with small kinks on the compression side corresponding to locations of high strain energy density, ripples form on the tube wall as bending progresses, until the tube flattens maximally at a critical location giving rise to a stable hinge that rotates under continued bending. The critical buckling curvature, locations of initial and stable hinges and rotational properties of the hinge are determined. Beyond the linear elastic region, the rotational stiffness depends on the hinge angle dropping close to zero (at the same angle for each tube) before beginning to rise again, reminiscent of snap-through buckling of shells, a property that can be exploited for sensing and signal amplification applications. [ABSTRACT FROM AUTHOR]

A new series of multi-walled carbon nanotube reinforced polybenzoxazine (MWCNT/PBZ) nanocomposites was successfully designed and developed. Three different maleimido terminal benzoxazine monomers (MI-BZs) were synthesized using N-(4-hydroxyphenyl) maleimide (HPM) and formaldehyde solution through Mannich condensation reaction and were characterized by FT-IR and NMR spectroscopy. Varying weight percentages (0 wt.%, 0.5 wt.%, 1.0 wt.% and 1.5 wt.%) of glycidyl-MWCNT were then incorporated into benzoxazine matrices to prepare MWCNT/PBZ nanocomposites. The nanocomposites having higher weight percentage of MWCNT were found to possess excellent thermal properties than those of neat PBZs. The developed nanocomposites exhibited better flame retardancy and higher dielectric constant. The optical properties ascertained from the UV-Vis absorption bands at the region of 300-350 nm and strong fluorescent emissions were observed in the wavelength range of 300-550 nm from Photoluminescence analysis. The intensity of characteristic diffraction peaks corresponding to g-MWCNT confirmed the reinforcement of MWCNT in the benzoxazine matrices, which indicated the successful formation of nanocomposites. The morphological studies ascertain the compatibility and uniform dispersion of MWCNT in the PBZ network. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes have been dispersed by novel phthalimide containing donor-acceptor type copolymers in organic media. Brominated phthalimide comonomer has been copolymerized with several electron rich structures using Suzuki and Stille coupling reactions. Carbon nanotube dispersion capability of the resultant polymers has been assessed by exploiting the non-covalent interaction of nanotube surface with the π-system of conjugated backbone of polymers. Four polymers have been found to be good candidates for individually dispersing nanotubes in solution. In order to identify the dispersed nanotube species, 2D excitation-emission map and Raman spectroscopy have been performed. Molecular dynamics modelling has been utilized to reveal the binding energies of dispersants with the nanotube surface and the simulation results have been compared with the experimental findings. Both experimental and theoretical results imply the presence of a complex mechanism that governs the extent of dispersion capacity and selectivity of each conjugated polymeric dispersant in solubilizing carbon nanotubes. [ABSTRACT FROM AUTHOR]

In this study, the surface of polyethylene terephthalate (PET) substrates was modified via corona treatment before the deposition of carbon nanotubes (CNTs), and the effects of such surface modification on the properties of the CNTs for flexible transparent electrodes were investigated. The changes in the surface roughness, contact angle, and surface energy of the PET substrates due to the corona treatment were characterized in terms of the applied corona energies, PET feeding directions, and treatment times. The higher corona energies, the more frequent treatment times, and the bi-directional treatment produced the larger surface roughness of the PET substrates. The results of the contact angles and the surface energies indicated that the surfaces of the PET substrates became hydrophilic from hydrophobic after the corona treatment. The analysis using X-ray photoelectron spectroscopy confirmed that oxygen polar groups appeared when the PET substrates were corona-treated. In addition, the increase in the CNTs' sheet resistance values due to their repeated outer and inner bending (up to 16,000 times) was found to have been significantly alleviated when the CNTs were deposited on the corona-treated PET substrates. This confirmed that the adhesion of the CNTs was improved after the corona pretreatment of the PET substrates. [ABSTRACT FROM AUTHOR]

In the present work, the effects of nanoscale parameter and Coriolis force together are investigated on vibrating eigenvalues of fluid-conveying carbon nanotube (CNT). A nonlocal Timoshenko beam and a plug flow model are implemented to derive fluid-structure interaction (FSI) governing equations of motion. These equations solved by Galerkin to obtain instability pattern, critical fluid velocities (CFVs), frequency and damping at different nanoscale parameter, boundary conditions, and aspect ratios. The results demonstrate existence of multiple types of instabilities and bifurcations, which are deviated from classic FSI buckling and flutters' instabilities, and caused by damping from coalition of nanoscale effect and fluid's Coriolis force, this phenomena are more noticeable in the CNTs with asymmetrical boundary conditions and smaller size. [ABSTRACT FROM AUTHOR]

We describe an ultrasensitive electrochemical nucleic acid assay amplified by carbon nanotubes (CNTs)-based labels for the detection of human acute lymphocytic leukemia (ALL)-related p185 BCR-ABL fusion transcript. The carboxylated CNTs were functionalized with horseradish peroxidase (HRP) molecules and target-specific detection probes (DP) via diimide-activated amidation and used to label and amplify the target hybridization signal. The activity of captured HRP was monitored by square-wave voltammetry measuring the electroactive enzymatic product in the presence of 2-aminophenol and hydrogen peroxide substrate solution. The signal-amplified assay achieved a detection limit of 83 fM (5 × 10−18 mol in 60 μL) targets oligonucleotides and has a 4-order-wide dynamic range of target concentration. The resulting assay allowed robust discrimination between the perfect match and a three-base mismatch sequence. When exposed to the full-length (491 bp) DNA oncogene, the approach demonstrated a detection limit of 1 × 10−16 mol in 60 μL, corresponding to approximately 33 pg of the target gene. The high sensitivity and specificity of the assay enabled a PCR-free detection of target transcripts in as little as 65 ng of mRNA extracted from positive ALL cell lines SUP-B15 in comparison to those obtained from negative cell line HL-60. The approach enables a simple, low-cost and ultrasensitive electrochemical nucleic acid detection in portable devices, point-of-care and early disease diagnostic applications. [ABSTRACT FROM AUTHOR]

In Iraq, a large quantity of basic orange and methyl violet dyes contaminated wastewater from textile industries is discharged into Tigris River. So the aim of this work is to found an efficient and fast technique that can be applied directly for removal of such dyes from the wastewater before discharging into river. Accordingly, CNTs as a new approach prepared by CCVD technique were purified, functionalized, and used as adsorption material to remove dyes from wastewater. The effect of pH, contact time, CNTs dosage, and dyes concentration on removal of pollutants was studied. The removal percentage of both dyes was proportional to the contact time, CNTs dosage, and pH and inversely proportional to the dyes concentration. The results show that the equilibrium time was 20 and 30 min for basic orange and methyl violet dyes, respectively, and the maximum removal percentage for all dyes concentrations was at pH = 8.5 and CNTs dosage of 0.25 g/L and 0.3 g/L for methyl violet and basic orange dye, respectively. The adsorption isotherm shows that the correlation coefficient of Freundlich model was higher than Langmuir model for both dyes, indicating that the Freundlich model is more appropriate to describe the adsorption characteristics of organic pollutants. [ABSTRACT FROM AUTHOR]