نتایج جستجو برای: walled tubes
تعداد نتایج: 41061 فیلتر نتایج به سال:
The chemical vapor deposition growth of unusual arrangements of single-walled carbon nanotubes (SWNTs) by the combined of use patterned catalysts and quartz substrates is reported. Nearly perfectly aligned, high-coverage arrays of SWNTs can be generated in this manner. High-coverage random networks of SWNTs can also be created in the same growth step, with good spatial alignment and electrical ...
The electron transport properties of well-contacted individual single-walled carbon nanotubes are investigated in the ballistic regime. Phase coherent transport and electron interference manifest as conductance fluctuations as a function of Fermi energy. Resonance with standing waves in finite-length tubes and localized states due to imperfections are observed for various Fermi energies. Two un...
The interaction of the glycine radical on the side walls of both armchair and zigzag single walled carbon nanotubes is investigated by density functional theory. It is found that the interaction potential of the N-centered glycine radical with the tubes has a minimum of 16.9 (armchair) and 20.2 (zigzag) kcal/mol with respect to the dissociation products. In contrast, the C-centered radical, whi...
Ventilator-associated pneumonia (VAP) is a common and serious complication of mechanical ventilation via an artificial airway. As with all nosocomial infections, VAP increases costs, morbidity, and mortality in the intensive care unit (ICU). VAP prevention is a multifaceted priority of the intensive care team, and can include the use of specialized artificial airways and heat-and-moisture excha...
Carbon nanotubes are chiral molecular objects and therefore exist in two forms that are each other’s mirror image. Many aspects of these fascinating new materials have recently been explored but their chirality has hardly been addressed. We have investigated the charge transport through individual single-walled carbon nanotubes in the presence of a magnetic field parallel to the tube axis. For ...
The size-fractionation of multi-walled carbon nanotube (MWNT) in the dimethylformamide (DMF) solution of poly(vinylidene fluoride) (PVDF) has been achieved by controlled sonication–centrifugation cycles. The Z-scan experiments and fluence-dependent transmission measurements with nanosecond laser pulses of 532 nm wavelength show that the optical limiting behavior of MWNTs in PVDF/DMF solution is...
In vivo measurement of the mechanical properties of thin-walled soft tissues (e.g., mitral valve, artery and bladder) and in situ mechanical characterization of thinwalled artificial soft biomaterials in service are of great challenge and difficult to address via commonly used testing methods. Here we investigate the properties of guided waves in immersed pre-stressed plates and tubes, and show...
The fluid-structure interaction simulation of shockand detonation-loaded thin-walled structures requires numerical methods that can cope with large deformations as well as local topology changes. We present a robust level-set-based approach that integrates a Lagrangian thin-shell finite element solver with fracture and fragmentation capabilities and an Eulerian Cartesian fluid solver with optio...
The dynamics of excitons in individual semiconducting single-walled carbon nanotubes was studied using time-resolved photoluminescence (PL) spectroscopy. The PL decay from tubes of the same (n,m) type was found to be monoexponential, however, with lifetimes varying between less than 20 and 200 ps from tube to tube. Competition of nonradiative decay of excitons is facilitated by a thermally acti...
A convenient process for generating large-scale, horizontally aligned arrays of pristine, single-walled carbon nanotubes (SWNTs) is described. The approach uses guided growth, by chemical vapor deposition (CVD), of SWNTs on miscut single-crystal quartz substrates. Studies of the growth reveal important relationships between the density and alignment of the tubes, the CVD conditions, and the mor...
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