168 research outputs found

    On the Dynamical Ferromagnetic, Quantum Hall, and Relativistic Effects on the Carbon Nanotubes Nucleation and Growth Mechanism

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    The mechanism of carbon nanotube (CNT) nucleation and growth has been a mystery for over 15 years. Prior models have attempted the extension of older classical transport mechanisms. In July 2000, a more detailed and accurate nonclassical, relativistic mechanism was formulated considering the detailed dynamics of the electronics of spin and orbital rehybridization between the carbon and catalyst via novel mesoscopic phenomena and quantum dynamics. Ferromagnetic carbon was demonstrated. Here, quantum (Hall) effects and relativistic effects of intense many body spin-orbital interactions for novel orbital rehybridization dynamics (Little Effect) are proposed in this new dynamical magnetic mechanism. This dynamic ferromagnetic mechanism is proven by imposing dynamic and static magnetic fields during CNT syntheses and observing the different influence of these external magnetic environments on the catalyzing spin currents and spin waves and the resulting CNT formation

    Synthesis of Multiwall Carbon Nanotubes by Inductive Heating CCVD

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    The CCVD syntheses of MWCNTs from acetylene on Fe:Co:CaCO 3 and Fe:Co:CaO were performed using two different methods of heating: outer furnace and inductive heating. The comparative analysis of the MWCNTs obtained by the two methods show that the tubes grown in inductive heating have smaller diameters (5-25 nm), with fewer walls and aspect ratio of the order of hundreds. The ratio of outer to inner diameter (od/id) is ranging between 2 and 2.5. Inductively assisted CCVD is a very attractive method because of the major advantages that it presents, like low energetic consumption, thinner, well crystallized and more uniform tubes

    Strain Sensors, Methods of Making Same, and Applications of Same

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    In one aspect, the present invention relates to a layered structure usable in a strain sensor. In one embodiment, the layered structure has a substrate with a first surface and an opposite, second surface defining a body portion therebetween; and a film of carbon nanotubes deposited on the first surface of the substrate, wherein the film of carbon nanotubes is conductive and characterized with an electrical resistance. In one embodiment, the carbon nanotubes are aligned in a preferential direction. In one embodiment, the carbon nanotubes are formed in a yarn such that any mechanical stress increases their electrical response. In one embodiment, the carbon nanotubes are incorporated into a polymeric scaffold that is attached to the surface of the substrate. In one embodiment, the surfaces of the carbon nanotubes are functionalized such that its electrical conductivity is increased

    Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

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    In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes

    Electrodynamic Arrays Having Nanomaterial Electrodes

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    An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures

    CONSIDERATIONS ON EQUIPMENT USED FOR MORE EFFICIENT USE OF WATER IN PRECIPITATION

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    Soil is the element that underlies the development of agricultural activities but also of other human activities.It is the source of water supply and nutrients necessary for the growth and development of crops. the entire period of vegetation. The present work presents some of the most used equipment used in the technologies of crops of fodder plants and of grain crops. located on muddy or sloping grounds for the most efficient use of rainwater, preventing erosion and leakage. [8

    Study of Velocity and Materials on Tribocharging of Polymer Powders for Powder Coating Applications

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    Electrostatic powder deposition is widely used in a plethora of industrial-applications ranging from the pharmaceutical and food.industries, to farm equipment and automotive applications. The disadvantages of this technique are possible back corona (pin-like formations) onset and the Faraday penetration limitation (when the powder does not penetrate in some recessed areas). A possible solution to overcome these problems is to use tribochargers to electrostatically charge the powder. Tribocharging, or contact charging while two materials are in contact, is related to the work function difference between the contacting materials and generates bipolarly charged particles. The generation of an ion-free powder cloud by tribocharging with high bipolar charge and an overall charge density of almost zero, provides a better coverage of the recessed areas. In this study, acrylic and epoxy powders were fluidized and charged by passing through stainless steel, copper, aluminum, and polycarbonate static mixers, respectively. The particle velocity was varied to determine its effect on the net charge-to-mass ratio (QIM) acquired by the powders. In general, the Q/M increases rapidly when the velocity was increased from 1.5 to 2.5 m/s, remaining almost constant for higher velocities. Charge separation experiments showed bipolar charging for all chargers

    Fano resonance resulting from a tunable interaction between molecular vibrational modes and a double-continuum of a plasmonic metamolecule

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    Coupling between tuneable broadband modes of an array of plasmonic metamolecules and a vibrational mode of carbonyl bond of poly(methyl methacrylate) is shown experimentally to produce a Fano resonance, which can be tuned in situ by varying the polarization of incident light. The interaction between the plasmon modes and the molecular resonance is investigated using both rigorous electromagnetic calculations and a quantum mechanical model describing the quantum interference between a discrete state and two continua. The predictions of the quantum mechanical model are in good agreement with the experimental data and provide an intuitive interpretation, at the quantum level, of the plasmon-molecule coupling

    Carbon Nanotube Coatings as Used in Strain Sensors for Composite Tanks

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    The next generation of cryogenic fuel tanks, crew habitats and other components for future spacecraft will focus on the usc of lightweight carbon fiber composite materials. A critical issue in the design and optimization of such tanks and structures will bc in structural health monitoring, however, current strain sensors have limitations. In this study, a novel carbon nanotube thin film was applied to carbon fiber composites for structural monitoring. Applying a load using a 3-point bend test to simulate bowing of a tank wall, induced significant increases in the film's electrical resistance at small deflections. Upon release of the load, the resistance returned to its approximate start value and was reproducible over multiple tests. The results show that a carbon nanotube thin film has great potential for the health monitoring of composite structures

    CONSIDERATIONS REGARDING THE USE OF EQUIPMENT FOR THE ESTABLISHMENT OF WATER COLLECTION BASINS FROM PRECIPITATION AND FROM THE USE OF SPRAY IRRIGATION SYSTEMS

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    Global warming has been growing rapidly lately, which implies an increasing need for water for the good development of agricultural crops. To allow the recovery of a significant amount of water from rainfall or irrigation, reducing the amount of energy necessary for irrigation but also for soil losses caused by the phenomenon of erosion or puddling, works are introduced in crop technologies with the help of which this recovery can be achieved. This paper presents equipment used for the execution of rainwater catchment basins and the use of sprinkler irrigation systems
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