Nano-structured zinc oxide–cotton fibers: synthesis, characterization and applications

Zinc oxide nanoparticles were prepared and subsequently deposited onto the surface of the cotton fiber by ultrasonic irradiation. The optical, structure and morphology of the coated and un-coated cotton were examined by UV, fourier transform infrared spectroscopy, X-ray diffraction analysis (XRD) and scanning electron microscope (SEM)/Energy Dispersive X-ray analysis. XRD analysis revealed the presence of the crystalline metal oxide of hexagonal phase with an average crystallite size of 12 nm. These nanoparticles are probably physically adsorbed onto the cotton fiber surface. SEM analysis showed a distribution of ZnO nanorod assemblies of various diameters and lengths physically adsorbed onto the cotton fiber surface may take place. The ZnO-cotton fiber nano-composite were tested against Escherichia coli (gram negative) and Staphylococcus aureus (gram positive) cultures, and showed a significant antimicrobial activity.     

Synthesis and properties of amphoteric surfactants

Carboxylic amphoteric surfactants containing ether tertiary amino and carboxylic groups were prepared. Specifically, 2-(2-dimethyl-aminoethoxy)octadecanoic, hexadecanoic and dodecanoic acid hydrochloride were synthesized. Surface and interfacial tension, emulsifying action, corrosion inhibition effect and after-treatment of direct dyed cotton fabrics were determined for these surfactants. Antibacterial activities were also examined. Chem. Eng. Dept., Faculty of Engineering.     

Characterization of apodized fiber Bragg gratings for rejection filter applications

Apodized fiber Bragg gratings with >/=30-dB sidelobe suppression +/-1 nm from the Bragg center wavelength are spatially characterized with side-scatter and side-diffraction techniques. Resonant side scatter is suppressed, indicating that little dispersion arises from reflections off the grating boundaries.     

Uniformly thinned optical fibers produced via HF etching with spectral and microscopic verification

A method for producing uniformly thinned (etched) optical fibers is described, which can also be employed to etch optical fibers containing a Bragg grating (FBG) uniformly for evanescent-field-based sensing and other applications. Through a simple modification of this method, the fabrication of phase-shifted FBGs based on uneven etching is also shown. The critical role of how a fiber is secured is shown, and the success of the method is illustrated, by differential interference contrast microscopy images of uniformly etched FBGs. An etched FBG sensor for the monitoring of the refractive index of different glycerin solutions is demonstrated.     

Occurrence of Features of Fiber Bragg Grating Spectra Having a Wavelength Corresponding to the Phase Mask Periodicity

The use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, twice the Bragg wavelength, associated with the phase mask periodicity were observed. However, when phase mask orders other than ＋1 were absent during fabrication the features at 1552 nm were not evident.