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Structural health monitoring (SHM) seeks to provide ongoing monitoring of a structure’s integrity. Current SHM approaches include embedding some type of sensor within the composite or applying a sensor to the outside surface of the structure. These sensors react to strain or other changes in order to detect damage. In this study, a novel, multi-modal, nanomaterial based sensor technology that can provide wide area detection of damage was used. The efforts presented here serve as a feasibility study into the incorporation of carbon nanomaterials into structural composites as sensors. The carbon nanotube (CNT) covered fiber (fuzzy fiber) sensors exhibit similar sensitivity to conventional strain gages and are more easily integrated into composite structures as the sensor itself is a composite. The fuzzy fiber strain gages can be used to sense strain within composite structures and can be readily integrated into the structural laminate to provide sensing over large sections and in previously inaccessible locations. The unique properties of the fuzzy fiber lends itself to application in a wide range of sensing tasks within a structural composite including strain, temperature, degradation, etc. The fuzzy fiber may be tailored so that the same basic sensor can be used for a multitude of sensing applications.

MicroRNAs (miRNAs) are directly involved in cancer initiation, progression and metastasis. Alterations of miRNAs expression in cancer tissue may be reflected in circulation.We attempted to investigate the expression and clinical significance of plasma miR-20a, miR-31 and miR-375 in patients with non-small cell lung cancer (NSCLC). The plasma levels of miR-20a, miR-31 and miR-375 in 164 NSCLC patients and 164 healthy controls (discovery cohort)were evaluated and compared among various clinicopathological characteristics. The relationship between miRNA expression and clinical outcome of NSCLC patients was examined in an independent cohort (53 cases and 53 controls). The expression level of miR-375 in tissue was also examined. Plasma miR-375 levels in NSCLC patients were significantly decreased in both patient cohorts (P b 0.05). In addition, patients with metastatic NSCLC had lower plasma miR-375 expression than those with non-metastatic NSCLC (P b 0.05). Survival analysis showed that patients with low miR-375 expression had worse overall survival rates than those with high miR-375 expression (hazard ratios (HR)=1.537 (1.046–2.258), P=0.029). This association was independently validated in a separate cohort of 53 NSCLC patients (HR=2.406, 95% CI 1.170–4.945, P=0.017). The expression level of miR-375 was also found to be significantly down-regulated in NSCLC tissues compared with paracancerous tissues (P b 0.001). These findings indicate that miR-375 has an important role in NSCLC initiation and progression, and may be an independent poor prognostic factor in NSCLC patients.

The use of a high-energy electron beam was explored in this study as an alternative technique for oxidizing vapor grown carbon nanofiber surfaces. The radiation exposures were carried out at three different electron beam facilities with beam energies of 1.5, 3.0 and 4.5 MeV and radiation doses ranging from 1000 to 3500 kGy. XPS analysis showed that oxygen was readily incorporated on the surface: the ratio O1s/C1s increased approximately by a factor of 4 when the carbon nanofibers were irradiated at 3500 kGy. The oxidized nanofibers exhibited better dispersion in a water/methanol solution (50% v/v) than as-received nanofibers. Raman spectroscopy revealed that the ID/IG ratios for most of the samples were statistically unchanged because the damage on the nanofiber surface was highly localized and did not lead to modifications on the bulk carbon nanofiber structure. The samples irradiated at higher dose rate exhibited significantly higher ID/IG ratios. The radiation process introduced defects on the graphene layers leading to a decrease of the decomposition onset temperatures up to 56 °C lower than the non-irradiated samples. Overall the results were repeatable across all facilities, illustrating the robustness of the process.

In order to more effectively monitor the health of composite structures, a fuzzy fiber sensor has been developed. The fuzzy fiber is a bundle of glass fibers with carbon nanotubes or nanofibers (CNTs or CNFs) grown on the surface. The nanotube coating makes the fiber bundle conductive while the small conductive path increases sensitivity. The fuzzy fiber sensor can replace conventional metal foil strain gauges in composite applications. The electrical response of the sensor is monitored in real time to measure strain, vibration, cracking and delamination. Continuous monitoring provides instant notification of any problems. Implementation of this sensor network in a composite can increase service life, decrease maintenance costs and greatly reduce inspection downtime.

Manganese oxide/carbon nanotube (CNT) composite films on graphite were prepared by growing CNTs on the substrate using chemical vapor deposition (CVD), followed by immersion in an aqueous solution of potassium permanganate. The CVD growth created favorable conditions for deposition of the oxide on the electrode, and an aligned porous structure of the composite films, which originated from the CNT growth, could be managed. Electrochemical behaviors of the CNT and the composite films for supercapacitors were studied in 1 M Na2SO4 solution. While the oxide deposition in the CNT films was identified as contributing to capacitance enhancement, it was also found that a mild heat treatment could improve performance of the composite films.

Carbon nanofibers were oxidized in air at 350 °C under the influence of a 3 MeV electron beam at doses of 1000 and 3500 kGy. XPS analysis showed that oxygen was readily incorporated on the surface: the ratio O 1s/C 1s increased approximately by a factor of three when the carbon nanofibers were irradiated at 3500 kGy. The oxidized nanofibers exhibited better dispersion than as-received nanofibers when mixed with water/methanol (50% v/v). Raman spectroscopy revealed that the ID/IG ratios were statistically unchanged for all samples because the damage on the nanofiber surface was highly localized and did not lead to modifications on the bulk carbon nanofiber structure. On the other hand, SEM, TEM, and AFM images illustrated that cutting, welding, and collapse may occur on the structure of irradiated nanofibers. BET analysis showed that the surface area of irradiated samples did not significantly increase, probably because the radiation process may lead to micro-porosity formation. The temperature during irradiation had no effect on the nanofibers’ surface and the thermal stability of the irradiated samples was determined to be lower.

Nickel modified carbon nanotubes on graphite substrate were investigated for constant-potential amperometric detection of l -asparagine. Both entangled and aligned carbon nanotubes directly grown on graphite by thermal chemical vapor deposition were used for making the electrodes. Nickel was applied on the carbon nanotubes by electrodeposition. The electrodeposited nickel on the entangled carbon nanotube electrodes dramatically enhanced the analytical response, while on the aligned carbon nanotube electrodes and on the graphite electrodes without the carbon nanotubes it was considerably less effective. The entangled carbon nanotube film formed from Co catalyst was concluded as a promising underlayer for electrodepositing nickel nanoparticles for detecting l -asparagine and also possibly other chemicals and biochemicals.

The thermal conductivity of vertically aligned CNT film arrays prepared using carbon vapor deposition (CVD) on a glass substrate was examined. A modern light flash device was first used to measure the effective thermal conductivity of the combined sample consisting of a sandwiched CNT film array thermal interface material between two glass plates. The results were used in an effective thermal resistance model to estimate the thermal conductivity of the CNT film. The value obtained was higher than that found in the literature and clearly demonstrated the advantage of using aligned CNTs and thus utilizing their maximum axial thermal conductivity. It was concluded that the quality of the CNT array produced using CVD directly contributed to the high thermal conductivity value obtained for the CNT film.

Field tests on mercury speciation and emission while burning Kentucky and Illinois coals with different chlorine contents were performed in a 100-MWe pulverized-coal boiler with low-NOx burners. Seven coals were used during the tests and were grouped into two sets for comparison, with the baseline coal being shared between the two sets. The first set of four coals was used to investigate the effect of chlorine in coal on mercury emission and its speciation by selecting coals with similar mercury contents and different chlorine contents. The four coals in the second set were selected to investigate the effect of mercury contents in coal on mercury emission and its speciation by choosing coals with similar chlorine contents and different mercury contents. The mercury concentration and speciation in the flue gas were determined using the American Society for Testing and Materials (ASTM) standard Ontario Hydro Method (OHM) and a PS Analytical Semi-continuous Emissions Monitoring (SCEM) system. Flue gas sampli...

A previous way of electrodepositing Ni-P alloy containing about 6-8 at.% phosphorus, which has a high catalytic activity for hydrogen evolution reaction (HER), is not capable of growing a thick coating having good physical stability. In this study, ammonium chloride was added increasingly between 0.5 and 4 M to the electrolyte containing 0.2 M NiCl2 and 0.1 M NaH2PO2 to examine its effect on the Ni-P electrodeposition. It was found that phosphorus content in the alloy increased almost linearly with only the addition of ammonium chloride. This result showed that the catalyst Ni-P alloy could be prepared using a low concentration of the phosphorus-offering reagent and a high concentration of ammonium, instead of using a conventional bath containing a relatively high phosphorus-offering reagent. Such a way made it feasible to grow the thick Ni-P coating containing the proper phosphorus for HER. (C) 2003 Elsevier Science B.V. All rights reserved.

Commercial grade aluminum was anodized to form porous anodic films using alternating current at a voltage of 15 V and a temperature of 25 degrees C. The AC anodization was implemented in phosphoric acid and in an electrolyte modified by dissolving 1.1g/1 iron powder. The presence of iron species in the modified electrolyte did not make iron to be incorporated in the film and appeared not to change the pore diameter, but doubled the film thickness. Electrodeposition of nickel was carried out to pigment the films. Pores of the films produced in the modified electrolyte were also found more accessible for nickel pigmentation. Reflectance spectrum of a nickel-pigmented film produced in the modified electrolyte was measured, and its solar absorptance and thermal emittance were calculated. It has been shown that AC anodization of aluminum in phosphoric acid modified by a small number of intentionally added species such as iron species, followed by electrodeposition of nickel, has potential in developing a method for cheaply preparing selective solar absorbing surface of nickel-pigmented anodic films of aluminum. (C) 2000 Elsevier Science B.V. All rights reserved.

The stability of composite material stiffened conical shells under uniform axial compression and with classical clamped boundary conditions is investigated. The effects of stiffeners are uniformly distributed over the whole surface of the shell, and the shell is treated as an equivalent orthotropic shell. A method of solution is developed by using energy principles and Rayleigh-Rize approximations. It is shown that the approach proposed in this paper is practical, effective and satisfactory.

We have demonstrated that multicomponent carbon nanotube micropatterns, in which different nanotubes are interposed in an intimate fashion, can be prepared by pyrolytic growth of carbon nanotubes on interposed micropatterns of different metal nanoparticles generated by template-free pulsed electrodeposition of metal-containing salts onto a photolithographically prepatterned conductive surface at different peak potentials. The resultant multicomponent interposed carbon nanotube micropatterns should have important implications for the construction of multicomponent and multifunctional nanomaterials and nanodevices based on carbon nanotubes for a wide range of potential applications.

We have previously developed a simple pyrolytic method for large-scale production of aligned multi-wall carbon nanotube arrays perpendicular to the substrate. These aligned carbon nanotube arrays can be transferred onto various substrates of particular interest (e.g. polymer films for organic optoelectronic devices) in either a patterned or non-patterned fashion. The well-aligned structure provides additional advantages for not only an efficient device construction but also for surface functionalization. The surface functionalization of aligned carbon nanotubes is particularly attractive, as it allows surface characteristics of the aligned carbon nanotubes to be tuned to meet specific requirements for particular applications while their alignment structure can be largely retained. These aligned carbon nanotubes with tunable surface characteristics are of great significance to various practical applications ranging from sensors to electronics. Single-strand DNA chains could be covalently immobilized onto plasma-activated aligned carbon nanotubes for sensing complementary DNA and/or target DNA chains of specific sequences with a high sensitivity and selectivity. Furthermore, glucose oxidase (GOX) could also be immobilized onto the aligned carbon nanoutbe arrays by electropolymerization of pyrrole in the presence of GOX. The resultant GOX-containing polypyrrole-carbon nanotube coaxial nanowires were shown to be promising new sensing active materials for making advanced glucose sensors with a high sensitivity.

The reduction method based on symmetry group or the so-called group theoretic approach (GTA) of Healey and associates for bifurcation analysis and free vibration analysis of geometrically nonlinear systems with symmetries is applied in the investigation reported here to the computations of responses of geometrically nonlinear systems under intensive transient excitations. A digital computer program written in Fortran language has also been developed for the work. Two space trusses discretized by the finite element method are chosen to illustrate the use of the GTA for cases undergoing large deflections. In the response computations for both the full space and reduced space or subspace problems the central difference method is employed. Numerical results are obtained. Comparisons of results for full space problems to subspace problems are made. It is concluded that the GTA is mathematically very elegant and rigorous. Computationally, the solution is exact and it is very efficient for geometrically nonlinear systems undergoing large deformation. The GTA is currently being developed for the response analysis of geometrically nonlinear systems with partial symmetries.