Time-Resolved Photometry of the Optical Counterpart of Swift J2319.4+2619

Time-resolved CCD photometry is presented of the V~17 optical counterpart of the newly-discovered, hard-X-ray-emitting polar Swift J2619.4+2619. A total of ~20 hr of data obtained over five nights in various bandpasses (B, V, R, and I) reveals a strong quasi-sinusoidal modulation in the light curve at a best-fitting period of 0.1254 d (3.01 hr), which we associate with the orbital period of the system (one-day aliases of this period at 0.1114 d and 0.1435 d are considered, but appear to be ruled out by our analysis). The amplitude of the modulation increases with wavelength from ~0.8 mag in B to ~1.1 mag in R and I. The increase in amplitude with wavelength is typical of polar systems where the modulated radiation comes from cyclotron emission. The combination of the relatively long orbital period and the emission of hard X-rays suggest that Swift J2619.4+2619 may be a good candidate for an asynchronous polar system.Comment: 15 pages, 5 figures, Accepted for publication in the April 2008 PAS

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe

Prediction of micro-spun yarn lea CSP using artificial neural networks

372-377<span style="font-size: 14.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">A back-propagation artificial neural network has been used to develop a model relating to cotton fibre properties and micro-spun yarn lea CSP. Fibre properties such as span length , bundle strength, fineness, breaking elongation, uniformity ratio and percentage of mature fibres have been studied. It is observed that a neural network architecture having five hidden neurons in one hidden layer and an epoch size of 12 gives better prediction. The predictions are more accurate than those obtained from regression models. The mean absolute error of neural network model is found to be 60% lower than those of the regression models. </span