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Enzyme-Linked Immuno-Sorbent Assay (ELISA), and other methods based on the same principle, are sensitive and specific, but they suffer from several disadvantages, such as their inherent complexity and requirement for multiple reagents, incubation and washing steps and require a relatively large sample size. We have adapted a new carbon nanotube field effect transistors (CNT-FET) based platform to capture Escherichia coli antigens using only the capture anti-body showing good correlation with an established ELISA assay contrived positive and negative specimens were used to test the new CNT-FET platform and results were obtained within three minutes per each sample. The test is easy to perform, rapid, and cost efficient making it a valuable screening tool for E. coli. In this study, we looked at the applicability of using CNT field effect transistor based biosensor as a rapid diagnostic platform for Escherichia coli O157:H7. The CNT-FETs platform detected positive E. coli samples in three minutes using only 2.5 μL of sample volume. This low sample volume required by the CNT-FET platform can be especially advantageous for diagnostic tests constricted by limited amount of samples.
We have synthesized dilute magnetic semiconductor (DMS) thin films of CdMnTe and ZnMnSe using the ion beam technique. High doses of Mn ions (∼2–5×1016/cm 2) were implanted into single crystal CdTe and into ZnSe epilayers on GaAs, forming subsurface layers of Cdl.xMnxTe and Znl-xMnxSe alloys, respectively, with x∼0.15–0.22. Fluorescence extended x-ray absorption fine structure (EXAFS) measurements on these materials reveal that the Mn atoms in the CdMnTe and ZnMnSe layers, both as-implanted and annealed, have local environments similar to their corresponding bulk-grown DMS alloys. While the anion-cation distances (Ra-c) in the annealed samples are equivalent to those in the corresponding bulk-grown DMS, the Ra-c in the asimplanted samples are slightly larger (∼0.01Å) than those in the bulk-grown DMS. This is most likely due to the implantation damage in the as-implanted materials. Our results on the Ra-c of the ion beam synthesized layers deviate significantly from Vegard's law, but are consistent with the bimodal distribution model. The EXAFS results are corroborated with results from ion beam analysis and Raman spectroscopy.
Laser surface modification of brass (Cu-38Zn-1.5Pb) using AISiFe and NiCrSiB alloy was achieved by using a 2kW continuous wave Nd-YAG laser with the aim of improving the cavitation erosion resistance and corrosion resistance. The alloying powder was preplaced on the brass substrate by thermal spraying to a thickness of 350µm, followed by laser beam scanning to effect melting, mixing and alloying. A modified surface was achieved by overlapping of adjacent tracks. The cavitation erosion resistance and the anodic polarization characteristics of the laser surface modified specimens in 3.5% NaCI solution at 23°C were studied by means of a 20kHz ultrasonic vibrator at a peak to peak amplitude of 60µm and a potentiostat respectively. The cavitation erosion resistance of the specimens modified with AlSiFe and NiCrSiB was improved by a factor of 3 and 7 respectively, compared with that of the brass substrate. Potentiodynamic test, however, indicated that the corrosion resistance of specimens modified with AlSiFe deteriorated, as reflected by a shift of the polarization curve towards higher current densities. On the other hand, the corrosion resistance of specimens modified with NiCrSiB was significantly improved, as evidenced by the presence of a passive region (from −175 mV to −112 mV) and a reduction in the anodic current density by at least an order of magnitude compared with the substrate at the same anodic potential. The hardness profile and the compositional profile were measured using a Vickers hardness tester and EDX respectively. The microstructure and the surface morphology of the specimens were investigated with the aid of SEM and optical microscopy.
Kinetic limitations related to the Schwoebel-Ehrlich (SE) diffusion barrier are examined in two-(2D) and three-dimensional (3D) growth. It is shown that the realization of step instabilities in 2D growth, possibly caused by the SE barrier, may be hindered by other factors such as step permeability and the relative importance of diffusion and step attachment. Growth shapes of Ag crystallites are also determined that reveal the impact of kinetic limitations. Dramatic changes of growth shape caused by In codeposition suggest that surfactants can modify the 3D SE barrier.
High-energy particle irradiation has been used to control the free electron concentration and electron mobility in InN by introducing native point defects that act as donors. A direct comparison between theoretical calculations and the experimental electron mobility suggests that scattering by triply-charged donor defects limits the mobility in irradiated samples across the entire range of electron concentrations studied. Thermal annealing of irradiated films in the temperature range 425°C to 475°C results in large increases in the electron mobility that approach the values predicted for singly-ionized donor defect scattering. It is suggested that the radiation-induced donor defects are stable, singly-charged nitrogen vacancies, and triply-charged, relaxed indium vacancy complexes that are removed by the annealing.
ZnO thin films have been deposited on Si(111) substrates at different
positions of the focusing lens by pulsed laser deposition (PLD) of a ZnO
target in an oxygen atmosphere. The strong influence of the position of the
focusing lens on the deposition rate, crystallinity, surface morphology and
optical properties of the deposited ZnO thin films are studied. The results
show that the ZnO thin films deposited at lens-target distance
cm (the focal length is 70 cm) have the highest deposition rate and
crystalline quality. The photoluminescence (PL) spectrum with the strongest
ultraviolet (UV) peak and blue peak is observed in this condition. Moreover,
the results of scanning electron microscopy (SEM) and selected area electron
diffraction (SEAD) indicate that the films deposited at this lens position
show the transition from monocrystalline to polycrystalline. Perfect
monocrystalline ZnO films are obtained only when Dl-t is changed in the
range from 63 cm to the focus position.
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