Use Of Carbon Nanotubes Research Articles

Influence of carbon nanotube on the mechanical and electrical characteristics of concrete – A review

Conventional concrete, which is composed of cement, coarse aggregate, fine aggregate, water, and superplasticizer, has the disadvantages of low maximum split tensile strength and low ductility, which can lead to sudden failure. However, the use of carbon nanotubes (CNT) can improve the binding to detect cracks in the structure before it collapses, as well as increase the maximum split tensile strength and ductility. The CNT is utilized to improve the mechanical characteristics of concrete, including its compressive strength, split tensile strength, and flexural strength. In addition to self-sensing, researchers examined the impact of carbon fiber and CNT particles on the mechanical characteristics of beam specimens with the suggested reinforcement arrangement. In this review, mechanical tests such as compressive strength, split tensile strength, and flexural strength are examined to determine the impact percentage of CNT that is beneficial for enhancing the strength of concrete. The study also further reviewed the resistivity of self-sensing CNT concrete. The review explored that CNT also improves electrical properties, such as resistivity and conductivity, and thermal conductivity of cement composites. To increase the electrical conductivity of beams, CNT and chopped carbon fibers (CF) were utilized. As a Nano-material, CNT may be widely distributed in the concrete through a proper mixing strategy. Due to their high modulus of elasticity, tensile strength, and yield strain, CNTs are an appealing material for concrete reinforcement. Using ultrasonication and a superplasticizer, a solution of dispersed CNTs with exceptional workability in concrete was made because the accumulation of CNTs significantly decreased the electrical resistance. The purpose of adding CNT to concrete for the Structure Health Monitoring technique is to detect building fractures using self-sensing concrete (SHM). The research finally concludes that CNT is highly beneficial to enhance compressive strength, flexure strength, and split tensile strength.

Carbon-Based Nanomaterials as Drug Delivery Agents for Colorectal Cancer: Clinical Preface to Colorectal Cancer Citing Their Markers and Existing Theranostic Approaches.

Colorectal cancer (CRC) is one of the universally established cancers with a higher incidence rate. Novel progression toward cancer prevention and cancer care among countries in transition should be considered seriously for controlling CRC. Hence, several cutting edge technologies are ongoing for high performance cancer therapeutics over the past few decades. Several drug-delivery systems of the nanoregime are relatively new in this arena compared to the previous treatment modes such as chemo- or radiotherapy to mitigate cancer. Based on this background, the epidemiology, pathophysiology, clinical presentation, treatment possibilities, and theragnostic markers for CRC were revealed. Since the use of carbon nanotubes (CNTs) for the management of CRC has been less studied, the present review analyzes the preclinical studies on the application of carbon nanotubes for drug delivery and CRC therapy owing to their inherent properties. It also investigates the toxicity of CNTs on normal cells for safety testing and the clinical use of carbon nanoparticles (CNPs) for tumor localization. To conclude, this review recommends the clinical application of carbon-based nanomaterials further for the management of CRC in diagnosis and as carriers or therapeutic adjuvants.

Effect of a New Multi-Walled CNT (MWCNT) Type on the Strength and Elastic Properties of Cement-Based Mortar

Creating new construction materials with improved strength, elasticity, and durability properties represent the focus of many research works. Significant research effort has been invested in investigating the use of carbon nanotubes (CNTs) in cementitious materials, especially multi-walled carbon nanotubes (MWCNTs) which consist of a series of concentric graphite tubes. The use of MWCNTs is closely related to the use of surfactants and ultra-sonication procedures which may alter their properties and the properties of cement-based materials. The paper presents the preliminary results of an experimental investigation on the suitability of using a new, modified, MWCNT type aimed at eliminating the need of using surfactants and ultrasonication. The modified MWCNTs have a much lower surface energy compared to “classical” ones which would result in a decreased tendency of self-aggregation. A comparison was carried out from the point of view of density, flexural and compressive strength as well as dynamic modulus of elasticity of the obtained mortars. The mortar mix incorporating the modified MWCNTs showed improved mechanical properties even for a low percentage of CNT addition (0.025% by mass of cement). The results are discussed based on the material structure determined from a series of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses.

Numerical Study of a Phase Change Material Energy Storage Tank Working with Carbon Nanotube–Water Nanofluid under Ha’il City Climatic Conditions

A numerical investigation of a phase change material (PCM) energy storage tank working with carbon nanotube (CNT)–water nanofluid is performed. The study was conducted under actual climatic conditions of the Ha’il region (Saudi Arabia). Two configurations related to the absence or presence of conductive baffles are studied. The tank is filled by encapsulated paraffin wax as the PCM, and CNT–water nanofluid flows through the capsules. The main goal is to increase the temperature of the PCM to 70 °C in order to store the thermal energy, which can then be used during the night and cloudy weather. Numerical computations are made using the finite element method (FEM) based on actual measured weather conditions. Climate conditions were collected from a weather station located on the roof of the engineering college’s building at the University of Ha’il. The collected data served as input to the numerical model, and the simulations were performed for three months (December, March, and July). The solid CNT volume fraction range was (0 ≤ ϕ ≤ 0.05) and the nanofluid volume flow rate ranged was (0.5 L/min ≤ V ≤ 3 L/min). For both considered cases (with and without baffles), it was found that the use of CNT–nanofluid led to a reduction in the charging time and enhanced its performance. An increase in the volumetric flow rate was found to accelerate the melting process. The best performances of the storage tank occurred during July due to the highest solar irradiation. Furthermore, it was found that the use of baffles had no beneficial effects on the melting process.

Carbon nanotubes as a suitable material for electrochemical sensor used in voltammetric determinations of titanium

AbstractWe report the use of carbon nanotubes as a material for the preparation of an electrochemical sensor that acts as a substrate for film metal electrodes used in stripping voltammetry. The sensor is based on a mixture of multiwall carbon nanotubes, glassy carbon spherical powder, and epoxy resin. The properly selected composition of the sensor made it possible to obtain a new substrate, competitive in relation to glassy carbon, for creating film metal electrodes. In this work, the proposed new sensor was used to determine the trace amounts of Ti(IV) on the lead film electrode. Measurements were carried out with in situ mode in an acetate buffer by adsorption stripping voltammetry with the use of cupferron as a complexing agent. Linear response to Ti(IV) ions in the concentration range of 7 × 10–10–7 × 10–8 mol L−1 and the limit of detection (LODs) 2.4 × 10–10 were obtained, respectively. These promising results revealed that a mixture of carbon nanotubes, epoxy resin, and spherical glassy carbon powder used for the determination of titanium ions on PbFE might represent an important addition to existing electrochemical sensor technologies. The proposed procedure was successfully used as a new and powerful analytical tool for determination of Ti(IV) in horsetail extracts.

Hydrogen molecule adsorption and sensing on lanthanide (La) doped/decorated carbon nanotube and graphene structures

The use of carbon nanotube (CNT) and graphene structures as doped and decorated with La atom as an adsorbent and a sensor material for hydrogen molecules was investigated by the density functional theory method. It is seen that the hydrogen interaction increased significantly after the La modification on the CNT and graphene. The fact that the adsorption enthalpy values are smaller than the liquefaction enthalpy value of hydrogen indicates that they can be used as adsorbent materials for hydrogen adsorption. While the adsorption energy values are better in the modification with La doping in the CNT structure, the results in the graphene structure are better in the decoration with the La atom. Charge transfer has occurred between the structures modified with La and the hydrogen molecule. After the hydrogen interaction, HOMO–LUMO gap values decreased in La-modified CNT structures and increased in graphene structures. This signifies that the La-modified CNT structures could be electronic sensors for hydrogen molecules. Consequently, the CNT and graphene structures doped and decorated with La can be used as adsorbents for hydrogen molecules. In addition, La-modified structures have electronic sensor properties.

The combined use of carbon nanotubes with synthetic ceramics enhances posterolateral fusion: an experimental study in a rat spinal fusion model.

The aim of the present study was to evaluate the effectiveness of carbon nanotubes (CNTs)/ HA-tricalcium phosphate (TCP) composite in a posterolateral spinal fusion model. At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Sprague Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later, all animals were killed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro-computed tomography (mCT). In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3) (p < 0.001). Although in Group 2, in which only CNTs were used, the ratio was found to be statistically significantly higher than group 1(p < 0.001), the difference was not considered as significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e., no bone formation was observed. The CNTs/HA-TCP composite is a promising synthetic bone graft substitute for spinal fusion. Although CNTs are inadequate in producing spinal fusion when they are used alone, due to their high biocompatibility due to their high biocompatibility, and multiple effect on bone regeneration, they seem to increase fusion rates significantly when they are used in combination with ceramic-based synthetic grafts.

Evaluation of the impact of industrial single-walled and multi-walled carbon nanotubes on human respiratory tract epithelial cells

Introduction. In the present study, a comparative assessment of the toxic effects of industrial single-walled and multi-walled carbon nanotubes (SWCNT and MWCNT) at doses corresponding to industrial exposures on BEAS-2B and A549 cells was carried out. Materials and methods. The size distribution of SWCNT and MWCNT agglomerates in dispersions was estimated by dynamic light scattering and transmission electron microscopy. Cytotoxicity was assessed using a MTS test and LDH assay. The interaction of CNTs with cells was visualized using dark-field and transmission electron microscopy. Results. Cytotoxic effects of pristine SWCNT and MWCNT in concentrations of 50-200 μg/ml and purified SWCNT in the range of 25-200 μg/ml were found in BEAS-2B cells. SWCNT and MWCNT were found to penetrate into the cytoplasm of both BEAS-2B and A549 cells, while MWCNT are more often revealed in the intracellular content as vacuolized clusters, and single SWCNT and agglomerates are visualized in the cytoplasm without a tendency to vacuolization. Limitations. CNT were introduced into cells in the form of dispersions, where both single nanotubes and their agglomerates were found. The calculation of CNT concentrations for introduction into cells was based on computer simulation. Conclusion. Further study of the mechanisms of cytotoxic and genotoxic effects of different types of carbon nanotubes (CNT) may contribute to the identification of MWCNT and SWCNT specific effects on the cells of the respiratory system to develop methodological approaches to the safe use of CNT.

Mechanical Homogenization of Transversely Isotropic CNT/GNP Reinforced Biocomposite for Wind Turbine Blades: Numerical and Analytical Study

One of the biggest problems facing the use of carbon nanotubes in reinforced composites is agglomeration within the matrix phase. This phenomenon—caused by Van der Waals forces—leads to dispersion problems and weakens the properties of the composites. This research presents a multi-stage homogenization approach used to investigate the influence of the aspect ratio, volume fraction, and agglomeration of the nanofillers on the effective mechanical properties of a polymer biocomposite containing randomly dispersed carbon nanotubes and graphene nanoplatelets. The first stage consisted in evaluating the properties of the reinforced polymers by the CNT/GNP. The second step consisted in combining the reinforced polymers with different natural and synthetic unidirectionally oriented fibers. It was found that agglomeration has a huge influence on the mechanical properties of the composite. The novelty of this work consisted of the consideration of the parameters influencing the elastic properties using different micromechanics approaches and numerical techniques.

Evaluation of the use of carbon nanotubes recovered from a biodegradation process in the production of new biodegradable polymer nanocomposites

Evaluation of the use of carbon nanotubes recovered from a biodegradation process in the production of new biodegradable polymer nanocomposites

A multifunctional integrated carbon nanotubes/polyphenylene sulfide composite: preparation, properties and applications.

Although great progress has been achieved in polyphenylene sulfide (PPS) composites by the use of carbon nanotubes (CNTs), the development of cost-efficient, well dispersive and multifunctional integrated PPS composites has yet to be achieved because of the strong solvent resistance of PPS. In this work, a CNTs-PPS/PVA composite material has been prepared by mucus dispersion-annealing, which employed polyvinyl alcohol (PVA) to disperse PPS particles and CNTs at room temperature. Dispersion and scanning electron microscopy observations revealed that PVA mucus can uniformly suspend and disperse micron-sized PPS particles, promoting the interpenetration of the micro-nano scale between PPS and CNTs. During the annealing process, PPS particles deformed and then crosslinked with CNTs and PVA to form a CNTs-PPS/PVA composite. The as-prepared CNTs-PPS/PVA composite possesses outstanding versatility, including excellent heat stability with resistant temperatures up to 350 °C, corrosion resistance against strong acids and alkalis for up to 30 days, and distinguished electrical conductivity with 2941 S m-1. Besides, a well-dispersed CNTs-PPS/PVA suspension could be used to 3D print microcircuits. Hence, such multifunctional integrated composites will be highly promising in the future of new materials. This research also develops a simple and meaningful method to construct composites for solvent resistant polymers.

Utilization of Steel Micro-fiber and Carbon Nanotubes in Self-compacting Lightweight Concrete

In this research, the engineering characteristics of self-compacting lightweight concrete (SCLWC) containing carbon nanotubes and steel micro-fiber were evaluated. The variables included the amount of carbon nanotubes (0, 0.02, 0.04, and 0.06% by weight of cement) and steel micro-fiber (0, 0.5, and 1% by volume). Lightweight expanded clay aggregate was used as lightweight aggregates. The experimental tests were self-compacting tests, compressive, splitting tensile, and flexural strengths, ultrasonic pulse velocity, electrical resistivity, water penetration depth, and scanning electron microscope. Adding 0.02 to 0.06 percent of carbon nanotubes to SCLWC reinforced with steel micro-fiber increases the compressive strength by about 33 to 64 percent. The use of 0.06% carbon nanotubes and 1% steel micro-fiber increased the splitting tensile strength by 36%. The use of carbon nanotubes and steel micro-fiber has the effect of influencing the filling of empty spaces and reducing concrete porosity. This can be attributed to the growing process of cement paste hydration and the filling of pores and capillary pores with the products of cement reactions, resulting in concrete compaction. Adding 0.02% carbon nanotubes to SCLWC samples containing 0.5% and 1% steel micro fibers increased the 28-day compressive strength by 36%, 34% and 33% respectively.

Carbon nanotubes: revolutionizing construction materials for a sustainable future: A review

This review article explores the use of carbon nanotubes (CNTs) as material enhancers in construction and their advantages. It emphasizes ongoing research to gather accurate data on CNT-enhanced material properties and their role in creating more efficient and stronger building materials. The various methods of obtaining and incorporating CNTs into building materials, including chemical vapor deposition and electric arc synthesis, are discussed. A comparative analysis of building materials with and without CNTs is presented to examine their characteristics. The article also discusses future prospects for CNTs in various industries. The study aims to investigate experimental methods for obtaining CNTs, their properties, and their introduction into building materials. The research methodology involves studying literature sources, analyzing experimental results, and examining the structural, mechanical, and electronic properties of CNTs. Analytical methods based on scientific articles and publications related to CNTs in construction were used to ensure the article's reliability, validity, completeness, and objectivity. The research highlights CNTs' potential as material enhancers in construction, owing to their unique mechanical properties, such as high strength, stiffness, and corrosion resistance. Specific studies demonstrating the use of CNTs to increase the strength of concrete and other construction materials are provided, indicating the promising application of CNTs in future construction projects. However, technical challenges must be addressed, and appropriate standards and regulations should be developed before practical implementation.

Carbon Nanotubes as Carriers in Drug Delivery for Non-Small Cell Lung Cancer, Mechanistic Analysis of Their Carcinogenic Potential, Safety Profiling and Identification of Biomarkers.

Non-small cell lung cancer (NSCLC) is a global burden leading to millions of deaths worldwide every year. Nanomedicine refers to the use of materials at the nanoscale for drug delivery and subsequent therapeutic approaches in cancer. Carbon nanotubes (CNTs) are widely used as nanocarriers for therapeutic molecules such as plasmids, siRNAs, antisense agents, aptamers and molecules related to the immunotherapy for several cancers. They are usually functionalized and loaded with standard drug molecules to improve their therapeutic efficiency. Functionalization and drug loading possibly decrease the genotoxic and carcinogenic potential of CNTs. In addition, the targeted cytotoxic properties of the drug improve and undesired toxicity decreases after drug loading and/or conjugation with proteins, including antibodies. For intended drug delivery, a lysosomal pH of 5.5 is more suitable and effective for the slow and extended release of cytotoxic drugs than a physiological of pH 7.4. Remarkably, CNTs possess intrinsic antitumor properties and are usually internalized by endocytosis. After being internalized, several mechanisms are involved in the therapeutic and carcinogenic effects of CNTs. They are generally safe for therapy, and their toxicity profile remains dependent on their physicochemical properties. Moreover, the dose, route, duration of exposure, surface properties and degradative potential determine the toxicity outcomes of CNTs locally or systemically. In summary, the use of CNTs in drug delivery and NSCLC therapy, as well as their genotoxic and carcinogenic potential and the possible mechanisms, has been discussed in this review. The therapeutic index is generally high for NSCLC cells treated with drug-loaded CNTs; therefore, they are effective carriers in implementing targeted therapy for NSCLC.

Slamming impact induced hydrodynamic response in wave-piercing catamaran beam elements with controller

When subjected to a slamming load, wave-piercing catamarans may be vulnerable to damage and deck diving. Aluminum beams are one of the key components of catamaran vessels and improving their stiffness and dynamic smart management is crucial to reducing the impact of waves at sea. The numerical analysis and mathematical modeling of the wave-piercing catamaran beam elements are fresh topics that largely depend on smart control issues. Based on a 2D Wanger type impact force model, this work presents a numerical benchmark study for the hydrodynamic analysis and smart control of wave-piercing catamaran beam elements. The Rankine panel approach also takes into account the impact of the wave-piercing catamaran's forward speed. The wave-piercing catamaran's smart control system consists of a proportional-differential (PD) controller with two piezoelectric layers acting as an actuator and a sensor on the top and bottom surfaces of the beams, respectively. Carbon nanotubes (CNTs) are employed as reinforcement to increase the stiffness of porous beams while assuming their agglomeration effects based on the Mori-Tanaka model. Refined zigzag shear deformation beam theory (RZSDBT) is used to mathematically represent the smart structure, and the related motion equations are generated using the energy technique. The differential quadrature method (DQM) and the Newmark method are used to solve the framework in order to capture the dynamic deflection and flexural moment and describe the Gibbs phenomenon. The effects of the controller, externally applied voltage, CNTs as reinforcement, forward speed, modification of shape and pressure distribution, porosity, deadrise angle, and external loads caused by demi-hulls and the cross-deck are all investigated using numerical studies. These studies look at how these factors affect dynamic deflection, flexural moment and Gibbs phenomenon. Regarding the primary goal of this work, the findings showed that the harmful effects can be greatly controlled with a PD controller. In other words, we can state unequivocally that the controller's assistance reduces the pressure distribution's discontinuity or spike while enhancing the beam's dry area. Additionally, the dynamic deflection and flexural moment are decreased by 49% and 37%, respectively, by employing the controller. The use of CNTs as beam reinforcement, which can reduce dynamic deflection and flexural moment by around 50% and 33%, respectively, is another goal of this work.

Optimal Selection of Parameters for Production of Multiwall Carbon Nanotubes (MWCNTs) by Electrolysis in Molten Salts using Machine Learning

The production and use of carbon nanotubes (CNTs) have become extremely wide within the last decade. Hence, the high interest in producing non-expensive and quality CNTs has motivated many research projects. This research considers the design and development of new technology for producing MWCNTs by electrolysis in molten salts using non-stationary and stationary current regimes. The electrolysis is simple, ecological, economical, and flexible, and it offers possibilities for accurate control of various parameters, such as applied voltage, current density, or temperature. We infer the underlying relationship between the parameters and the quality of the experimentally produced MWCNTs by using explainable tree-based Machine Learning (ML) models. We train several models in a supervised manner, whereas in model covariates, we use the parameters of the MCWNTs, and as a target variable, the quality of the produced MWCNT. Domain experts label all the experimental examples in our data set. Controlling these parameters enables high-yield production and, particularly important, obtaining MWCNTs, which are up to ten times cheaper than other existing technologies.

Hybrid effect of carbon nanotubes and basalt fibers on mechanical, durability, and microstructure properties of lightweight geopolymer concretes

In this research, a combination of basalt fibers (BFs) and carbon nanotubes (CNTs) were used to improve the engineering attributes of lightweight geopolymer concrete (LWGC). A combination of ground granulated blast furnace slag (GGBFS) and CNTs was utilized as the binder. The experiments consisted of slump, equilibrium density, compressive and splitting tensile strengths, ultrasonic pulse velocity, water absorption, water penetration depth, electrical resistivity, fourier-transform infrared spectroscopy, energy dispersive X-ray microanalysis, and scanning electron microscope. Also, reinforced LWGC beams containing different percentages of BFs and CNTs were fabricated and subjected to four-point loading. The experimental outcomes demonstrated that CNTs could be used as a replacement for a part of GGBFS to obtain structural LWGC with suitable mechanical and durability attributes. The combined use of CNTs and BFs increases the compressive and splitting tensile strength by 32.2% and 43.7%, respectively. Due to greater participation in the geopolymerization process and the formation of hydrated gels, mixes containing CNTs fill the voids and form a dense and cohesive structure. Moreover, the presence of BFs in the binder texture of LWGC strengthens the bond between the binder and the aggregates and prevents the development of capillary cracks. It was observed that the reinforced LWGC beam containing BFs and CNTs had higher flexural strength and better ductile performance than the control specimen.

Bonding of Steel Bars in Concrete with the Addition of Carbon Nanotubes: A Systematic Review of the Literature

Advances and innovations in science and engineering have been increasingly supported by nanotechnology, and the modification of cementitious materials by nanoengineering is an expanding field. With this perspective, this paper aims to elucidate the behavior of steel bars in concrete with the addition of carbon nanotubes (CNTs) as a function of the characteristics of the cement-based material, the dispersion techniques and dosage of CNTs, the bond tests and specimen geometry, and the rebar characteristics. To reach this proposed goal, the ProKnow-C methodology was applied to select the most relevant publications from the last ten years, and then seven articles were fully analyzed. The results of the present systematic review of the literature revealed both consolidated knowledge and gaps to be filled in future research, as the need to study the chemical effect of adding these nanomaterials for improving steel–concrete adhesion, the bonding of thin bars in concrete, and the real influence of anchorage length on the steel–concrete bond, regardless of the use of CNTs, is vital.

Origin of Capillary-Force-Induced Welding in Ag Nanowires and Ag Nanowire/Carbon Nanotube Conductive Networks.

Capillary-force-induced welding can effectively reduce the contact resistance between two silver nanowires (AgNWs) by merging the NW-NW junctions. Herein, we report a model for quantifying the capillary force between two nano-objects. The model can be used to calculate the capillary force generated between AgNWs and carbon nanotubes (CNTs) during water evaporation. The results indicate that the radius of one-dimensional nano-objects is crucial for capillary-force-induced welding. AgNWs with larger radii can generate a greater capillary force (FAgNW-AgNW) at NW-NW junctions. In addition, for AgNW/CNT hybrid films, the use of CNTs with a radius close to that of AgNWs can result in a larger capillary force (FAgNW-CNT) at NW-CNT junctions. The reliability of the model is verified by measuring the change in sheet resistance before and after capillary-force-induced welding of a series of AgNW and AgNW/CNT conductive films with varying radii.

A Short Review on: Recent Advances in the Use of Carbon Nanotubes in Additive Manufacturing of Polymer Matrix Composites

AbstractThe multi‐functionality of polymer matrix composites, proposes remarkable merits over metals including more stiffness and strength, lower weight, higher resistance to corrosion, and fatigue, etc. Furthermore, the next generation of production undergoes a revolution by increasingly progresses in additive manufacturing. There have been a large group of materials that can be exploited for this fashionable fabrication technique, although, polymer matrix composites are a significant class of material that have recently been used in additive manufacturing. The mixture of these polymers with nanofillers such as carbon nanotube improves mechanical, thermal, and electrical conductivity properties. This short review summarizes relevant production techniques, carbon nanotube polymer matrix composites, and performed research on its application for additive manufacturing.