Called Carbon Nanotubes Research Articles

The Entire Zagreb index is based on H – Naphtalenic nanotubes

A topological index is a mathematical formula that can be used to model any molecular structure on any graph. Topological indices are used to predict the physical, and bioactivity of corresponding chemical compounds. The symmetry of molecular structures is captured in topological indices, which give the structures a scientific terms to determine features like boiling temperatures, viscosity, and gyrating radius. Carbon allotropes in the form of nanostructures called carbon nanotubes have a cylindrical shape. An example of a fullerene is the carbon nanotube, which has uses in nanotechnology, electronics, optics, materials science, and architecture. We compute the First and Second Zagreb index, Hyper index, Zagreb Polynomial, and Augmented Zagreb index of H - Naphtalenic nanotubes.

A Novel Dual Output Comparator Based on Carbon Nanotube Field Effect Transistors Second Generation Current Controlled Conveyor

Background: Current comparators are useful in many analog circuits and communication systems. With the increasing demand to integrate wearable health monitoring systems in telemedicine and biomedical applications that help in early detection of abnormal conditions in patients, comparator is one of its cores. Objective: Wearable and implantable medical devices work primarily on the signal acquisition and wireless transmission. In the signal acquisition, Analog to Digital Converter (ADC) is the prime module. Conversion is done using the sampling process and samples are generated by comparing the input signal with the threshold level. For this purpose, comparator circuits are more preferable. This manuscript presents a novel dual output comparator design by using carbon nanotube field effect transistor second generation current controlled conveyor (CNCCCII). This CNCCCII is realized with the present- day technology called Carbon Nanotube Field Effect Transistors (CNFETs). Methods: The proposed comparator topology is designed with 32 nm CNFET technology files with a supply voltage of ±0.9 V using the Cadence Virtuoso simulator tool. The performance of the proposed design is tested using transient analysis, Montecarlo analysis, temperature sweep, and finally compared with the existing models. Results: The proposed comparator has the advantage of requiring a single CNCCCII with only one resistor and is preferable for monolithic IC fabrication. Conclusion: The proposed circuit implemented using CNFETs gives a substantial improvement in supply voltage requirement and less variation in output voltage levels over the existing technologies.

Dakshayani Indices on Carbon and Boron Nitride Nanotubes

Chemical graph theory is a discipline of graph theory deals with the study of chemical compounds using simple connected graphs. In computational chemistry, the properties of chemical compounds are determined using a numerical value called the topological index. Topological indices are widely applicable in QSAR and QSPR modeling. In this proposed work, we have used topological index like Neighborhood Dakshayani index on nanostructures called Carbon nanotube and Boron nitride nanotubes. Carbon nanotube has its various applications in air and water filtration, field emission, and biomedical applications. Boron nitride nanotubes are used in aerospace to automotive and defense to biomedical.

Fullerene and its applications: A review

Fullerene molecules are composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Fullerenes in the cylindrical form are called carbon nanotubes (CNTs) or buckytubes and fullerenes in the spherical form are referred to as buckyballs. The CNT represents one of the unique inventions in nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world for their great potential in different fields. Fullerenes have attracted considerable attention in different fields of science since their discovery in 1985. Their unique carbon cage structure coupled with immense scope for derivatization makes them a potential therapeutic agent. The fullerenes can be utilized in organic photovoltaic (OPV), portable power, medical purpose, antioxidants, and biopharmaceuticals and dentistry.

Carbon Nanotube Effect on the Ductility, Flexural Strength, and Permeability of Concrete

Recently, remarkable types of carbon nanofilaments called carbon nanotubes (CNTs) have raised the interest of many concrete and cementitious composite researchers due to their significant mechanical, electrical, thermal, kinetic, and chemical properties. These nanofilaments are considered promising applicants to use in producing high-performance cement-based composite materials. In this research, the effect of CNT use on the flexural strength, strain capacity, permeability, and microstructure of concrete was investigated. Concrete batches of 0, 0.03, 0.08, 0.15, and 0.25 wt.% CNTs were prepared using a mixing method that consisted of a 30-minute solution sonication and a 60-minute batch mixing. On the 28th day, the mechanical properties were determined. The results indicated that concrete prepared using high CNT contents of 0.15 and 0.25 wt.% increased the flexural strength by more than 100% in comparison with 0% CNT concrete. Furthermore, the results showed that CNTs would increase the ductility of concrete beams by about 150%. The permeability test results showed the benefits of CNT inclusion in reducing the permeability of concrete. The permeability coefficient (kT) decreased by at least 45% when CNTs were added to concrete. A qualitative microstructural analysis illustrated the uniform dispersion of CNT filaments within the concrete hydration products in all batches.

NMR Theoretical Studies of Trapped Cations inside Fullerenes

A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs and they resemble the balls used in association football. Cylindrical ones are called carbon nanotubes or buckytubes. Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings; but they may also contain pentagonal (or sometimes heptagonal) rings [1].

Synthesis of Single-Walled Carbon Nanotubes Coated with Thiol-Reactive Gel via Emulsion Polymerization.

Single-walled carbon nanotubes (SWNTs) have unique near-infrared absorption and photoemission properties that are attractive for in vivo biological applications such as photothermal cancer treatment and bioimaging. Therefore, a smart functionalization strategy for SWNTs to create biocompatible surfaces and introduce various ligands to target active cancer cells without losing the unique optical properties of the SWNTs is strongly desired. This paper reports the design and synthesis of a SWNT/gel hybrid containing maleimide groups, which react with various thiol compounds through Michael addition reactions. In this hybrid, the method called carbon nanotube micelle polymerization was used to noncovalently modify the surface of SWNTs with a cross-linked polymer gel layer. This method can form an extremely stable gel layer on SWNTs; such stability is essential for in vivo biological applications. The monomer used to form the gel layer contained a maleimide group, which was protected with furan in endo-form. The resulting hybrid was treated in water to induce deprotection via a retro-Diels-Alder reaction and then functionalized with thiol compounds through Michael addition. The functionalization of the hybrid was explored using a thiol-containing fluorescent dye as a model thiol, and the formation of the SWNT-dye conjugate was confirmed by energy transfer from the dye to SWNTs. Our strategy offers a promising SWNT-based platform for biological functionalization for cancer targeting, imaging, and treatment.

Highly conductive and high-strength carbon nanotube film reinforced silicon carbide composites

Abstract Film formed by carbon nanotubes is usually called carbon nanotube film (CNTf). In the present study, CNTf fabricated by floating catalyst method was used to prepare CNTf/SiC ceramic matrix composites by chemical vapor infiltration (CVI). Mechanical and electrical properties of the resulting CNTf/SiC composites with different CVI cycles were investigated and discussed, and the results revealed that the CNTf has a good adaptability to CVI method. Tensile test demonstrated an excellent mechanical performance of the composites with highest tensile strength of 646 MPa after 2 CVI cycles, and the strength has a decline after 3 CVI cycles for an excessively dense matrix. While, the elastic modulus of the composite increased with the CVI cycles and reached 301 GPa after 3 CVI cycles. Tensile fracture morphologies of the composites were analyzed by scanning electron microscope to study the performance change laws with the CVI cycles. With SiC ceramic matrix infiltrated into the CNTf, enhanced electrical conductivity of the CNTf/SiC composite compared to pure CNTf was also obtained, from 368 S/cm to 588 S/cm. Conductivity of the SiC matrix with free carbon forming in the CVI process was considered as the reason.

Simultaneous determination of copper, cobalt, and mercury ions in water samples by solid-phase extraction using carbon nanotube sponges as adsorbent after chelating with sodium diethyldithiocarbamate prior to high performance liquid chromatography.

Recently, a sponge-like material called carbon nanotube sponges (CNT sponges) has drawn considerable attention because it can remove large-area oil, nanoparticles, and organic dyes from water. In this paper, the feasibility of CNT sponges as a novel solid-phase extraction (SPE) adsorbent for the enrichment and determination of heavy metal ions (Co(2+), Cu(2+), and Hg(2+)) was investigated for the first time. Sodium diethyldithiocarbamate (DDTC) was used as the chelating agent and high performance liquid chromatography (HPLC) for the final analysis. Important factors which may influence extraction efficiency of SPE were optimized, such as the kind and volume of eluent, volume of DDTC, sample pH, flow rate, etc. Under the optimized conditions, wide range of linearity (0.5-400μgL(-1)), low limits of detection (0.089~0.690μgL(-1); 0.018~0.138μg), and good repeatability (1.27~3.60%, n = 5) were obtained. The developed method was applied for the analysis of the three metal ions in real water samples, and satisfactory results were achieved. All of these findings demonstrated that CNT sponges will be a good choice for the enrichment and determination of target ions at trace levels in the future.

Shrinkage deformation of cement foam concrete

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

SU-GG-J-44: Carbon Nanotube Field Emission Technology Enables Novel Imaging and Irradiation System Development for Cancer Research and Clinical Application

Purpose:Carbon nanotubefield emission is an emerging nanotechnology for novel x‐ray imaging and radiation delivery systems development for cancer research and clinical application. In this presentation we will give a general review of the nanotechnology and its applications in the development of novel devices including CT imaging,tomosynthesis, and cancer research radiation delivery systems. Method and Materials:Carbon nanotubefield emission is a based on the unique properties of a nanomaterial called carbon nanotubes(CNT).CNT is the newest carbon allotrope discovered in 1991 and it is comprised of either a single graphene shell, called the single‐wall carbon nanotube, or multiple concentric graphene shells termed a multi‐wall carbon nanotube. The signature feature is a very large aspect ratio (ratio of diameter to length) that is typically is on the order 103. The high aspect ratio makes CNTs a practical and excellent field emitter that can produce high current density with intrinsically small divergence and extremely high temporal resolution. More importantly, its unprecedented flexibility in cathode design has launched new creativity in imaging and therapy system development. Results: We will show examples of our research development on CNTfield emission based imaging and irradiation systems that include 4D micro‐RT, stationary tomosynthesis, multi‐pixel electron microbeam cellular irradiator under real time microscope observation, and multi‐pixel x‐ray micro‐CT‐RT image‐guided and intensity‐modulated radiation for small animal tumor models. The technical challenges of the CNTfield emissiontechnology will also be discussed. Conclusion:Carbon nanotubefield emissiontechnology has shown great promise in developing novel imaging and radiation systems that can potentially advance cancer research and improve the quality and efficiency of cancer diagnosis and treatment.

Two-Dimensional Carbon Nanotube Networks: A Transparent Electronic Material

AbstractThe random, two-dimensional network formed of electrically conducting nanoscale wires, called carbon nanotubes, is a transparent electronic material that can be fabricated using room-temperature printing or spraying technologies. Depending on the network density, networks with both metallic- and semiconducting-like attributes can be fabricated. Both display high conductivity, high carrier mobility and optical transparency. The networks also have high mechanical flexibility, robustness and environmental resistance. Application opportunities range from lightweight, transparent conducting films, to electrically conducting fabrics, to active electronic devices and sensors.

Quantum conductance of a helically coiled carbon nanotube

Using π-orbital tight-binding model, we investigate the transport properties of a coiled carbon nanotube (also called carbon nanotube spring), which we construct by connecting carbon nanotubes periodically in three-dimensional (3D) space. Theconductance is quantized due to the translational symmetry in the coiled direction. However, the conductance behaviors differ greatly from those of pristine metallic carbon nanotubes but similar to those of carbon nanotube superlattices. We explain that conductance behaviors of the coiled carbon nanotube.

Nondissipative Orbital Currents in Finite Quantum Systems: A Comparative Study

The idea of nondissipative, persistent currents in mesoscopic metallic or semiconducting rings and cyclinders appears counterintuitive, because it contradicts our experience with currents in macroscopic metals. On the other hand such orbital currents are well known properties of atoms. A comparative study of nondissipative ring currents in different finite quantum systems is therefore of interest. In this paper the properties of atoms, mesoscopic metallic or semiconducting rings and cylinders and elongated molecules called carbon nanotubes are discussed and compared.

Taking technology to the molecular level

Fifty years ago (1950), nanotechnology could only merit serious consideration in dreams and science fiction. The author now believes nanotechnology's existence to be a certainty. The only question now is when. The application areas for a mature nanotechnology industry are astounding. The author predicts nanotechnology will virtually eliminate pollution from the earth's air and water, as well as produce clean manufacturing processes for the future. Also, she foresees the creation of a space elevator stretching from Earth's surface to a geosynchronous orbit along which cargo and people could move, built with an extremely hard material called carbon nanotubes. And she predicts extremely small machines that destroy viruses, remove arterial plaque, and get rid of cancer cells. The author explains the research activities, some in the form of industry startups taking place across a variety of disciplines: chemistry, physics, mechanical engineering, materials science, molecular biology, and computer science. She also explains some of the issues surrounding this extremely powerful and potentially dangerous technology.

Growth behavior and structures of carbon nanotubes

Recent discovery of the novel hollow graphitic tubules of nanometer dimensions, so called carbon nanotubes, has greatly stimulated the studies in the field of carbon fiber growth. Their potential applications in electronic and materials industries have been suggested. In the present study, carbon nanotubes were fabricated by an arc-discharge method. The microstructures of nanotubes thus obtained were examined with a JEM-2000FX high-resolution transmission electron microscopy (HRTEM) and with an electron nanodiffraction technique in a VG HB-5 scanning transmission electron microscopy (STEM).HRTEM images show that nanotubes, consisting of 3 to 30 carbon sheets, have a length up to 1 μm and a diameter of 6 to 26 nm. Some nanotubes have a symmetric uniform sheet spacing of 0.34 nm. Others show non-symmetric uneven fringes (Fig. 1), indicating that they may have a polyhedral cross section. Most nanotubes are closed by cone-like or polyhedral shaped caps (Figs. 2 and 3). The closure angle varies from 17 to 40° and the internal sheets have a tendency to be closed in pairs. Fig. 4 shows the image of a growing tubes.