OTDR in single-mode fibre at 1.5 ?m using homodyne detection

The letter reports on the first application of homodyne detection to optical time-domain reflectometry (OTDR) in single-mode fibres at a wavelength of 1.52 ?m. A number of important differences to heterodyne detection are discussed, and the integration of the discrete optical components considered.     

Generalized mosaicing: polarization panorama

We present an approach to image the polarization state of object points in a wide field of view, while enhancing the radiometric dynamic range of imaging systems by generalizing image mosaicing. The approach is biologically inspired, as it emulates spatially varying polarization sensitivity of some animals. In our method, a spatially varying polarization and attenuation filter is rigidly attached to a camera. As the system moves, it senses each scene point multiple times, each time filtering it through a different filter polarizing angle, polarizance, and transmittance. Polarization is an additional dimension of the generalized mosaicing paradigm, which has recently yielded high dynamic range images and multispectral images in a wide field of view using other kinds of filters. The image acquisition is as easy as in traditional image mosaics. The computational algorithm can easily handle nonideal polarization filters (partial polarizers), variable exposures, and saturation in a single framework. The resulting mosaic represents the polarization state at each scene point. Using data acquired by this method, we demonstrate attenuation and enhancement of specular reflections and semi reflection separation in an image mosaic.     

Improving the photocatalytic performance of TiO2 via hybridizing with graphene

In this paper an improvement in the photocatalytic performance of TiO₂ was carried out via hybridizing with graphene. Graphene-TiO₂ (GR-TiO₂)nanocomposites with different weight addition ratios of graphene oxide (GO) have been prepared via a facile microwave irradiation of GO and tetrabutyl titanate in isopropyl alcohol. Raman spectroscopy (RS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy (UV-vis), Fourier transform infrared spectra (FTIR), energy dispersive X-ray spectroscopy (EDX) and photoluminescence spectra (PL) are employed to determine the properties of the samples. Microwave irradiation can heat the reactant to a higher temperature in a short time, simultaneously GO is reduced to graphene and TiO₂ nanoparticles grown on the surface of GR. GR-TiO₂ nanocomposites synthesized via this approach have efficient electron conductivity in GR, resulting in a reduced electron-hole recombination rate. Among the synthesized nanocomposites, GT-8wt% exhibited the best photocatalytic activity toward photocatalytic degradation of MB. Our current work provides a new insight for the fabrication of GR-TiO₂ nanocomposites within a short reaction time and also explains the mechanism of photocatalysis employing radical and hole scavengers.     

Influence of cyclic tensile straining parameters on the tensile characteristics of compact yarn

It would seem that previous tensile fatigue studies in yarns using the cyclic loading and extension principles were carried out with limited sets of variables and levels. To get a clear understanding of the tensile fatigue behaviour of yarns and in order to study the yarn damage under the influence of cyclic tensile straining, an investigation on the influence of various cyclic tensile straining parameters, extension level, extension rate and straining cycles at five different levels, on the tensile breaking load and breaking extension characteristics of compact yarn of count 14.75 Tex has been carried out. The extension level of 8 mm, the extension rate of 400 mm/min and the number of straining cycles of 2500 have resulted in the maximum drop in the breaking load and extension values of the yarn which are 30.4 and 40.25% lower than the average breaking load and extension values of the unstrained yarn.     

Nucleotide sequence of porcine circovirus associated with postweaning multisystemic wasting syndrome in pigs

This article describes the nucleotide sequence of a porcine circovirus (PCV) which possesses a high degree of association with postweaning multisystemic wasting syndrome (PMWS), a newly described disease of young pigs. The DNA sequence of this PMWS-associated PCV (pmws PCV) has 68% homology with that of a previously published nonpathogenic strain of PCV. The strains appear to be closely related yet distinct from one another.     

Experimental investigation of all-optical switching in fibre loop mirror device

Nonlinear optical switching has been experimentally demonstrated in a monomode fibre loop mirror (Sagnac) interferometer using both Q-switched and CW-mode locked pulses of a Nd:YAG laser at 1.32 mu m. The switching crossover for a 25 m loop occurs at 22 W. It has been shown that incomplete switching occurs due to pulse shape effects. The presence of Raman scattering results in a step-like, rather than periodic, response.<>     

Characterization of porcine sclera using instrumented nanoindentation

Sclera tissue is the outermost protective layer of the eye and often involved in mechanical interactions during ocular medical procedures. In this study, instrumented nanoindentation is evaluated as a methodology for characterizing porcine sclera submerged in phosphate-buffered saline (PBS). Variances within a single sample and between samples are compared. Reduced modulus measurements are used to determine the effects of hydration, mounting conditions, and maximum applied load. Extended in vitro exposure beyond four hours to PBS is determined to decrease sample integrity. The use of glue to secure samples improved data consistency and had no negative effects on measurements. The data suggest that nanoindentation is a high precision method for measuring the reduced modulus of ultra low modulus soft tissue such as sclera (E_r ~ 30 kPa) and illustrates the importance of environmental factors upon material properties.     

Microwave-Assisted Synthesis of Titania Nanocubes, Nanospheres and Nanorods for Photocatalytic Dye Degradation

TiO₂ nanostructures with fascinating morphologies like cubes, spheres, and rods were synthesized by a simple microwave irradiation technique. Tuning of different morphologies was achieved by changing the pH and the nature of the medium or the precipitating agent. As-synthesized titania nanostructures were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, infrared spectroscopy (IR), BET surface area, photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques. Photocatalytic dye degradation studies were conducted using methylene blue under ultraviolet light irradiation. Dye degradation ability for nanocubes was found to be superior to the spheres and the rods and can be attributed to the observed high surface area of nanocubes. As-synthesized titania nanostructures have shown higher photocatalytic activity than the commercial photocatalyst Degussa P25 TiO₂.