A simple ZVI-Fenton pre-oxidation using steel-nails for NOM degradation in water treatment

The feasibility of a heterogeneous Fenton Process (ZVI/H2O2) using commercial low-carbon-steel nails as the Zero-Valent Iron (ZVI) source was evaluated for the first time for the removal of natural organic matter (NOM) from natural surface waters with distinct physico-chemical characteristics. The synergistic effect of ZVI nails and H2O2 on the process was confirmed. Results showed similar removal efficiencies of NOM in water samples from Thames river and Regent's Park lake (both in London, UK) (under initial pH 3.5 and 100% excess of H2O2 dosage), reaching dissolved organic carbon (DOC) removals of 61.6% ± 3.0 and 59.6% ± 4.7, and UV254 removals of 79.9% ± 0.6 and 77.3 ± 6.2, respectively with 60 min of batch reaction time. ZVI nail surface characterization by scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and X-ray photoemission spectroscopy (XPS) revealed the formation of a passivating oxide-hydroxide layer on the nail during the reaction, which reduces its surface activity with 20% in continuous use. Results indicate that ZVI/H2O2 process using commercial iron nails is a promising pre-oxidation step for drinking water treatment. The low cost of commercial nails together with the facility of separating them from the water are the main advantages for the application of this process in remote regions with limitations in infrastructure and/or finance

Denoising swallowing sound to improve the evaluator's qualitative analysis

Swallowing dynamics involves the coordination and interaction of several muscles and nerves which allow correct food transport from mouth to stomach without laryngotracheal penetration or aspiration. Clinical swallowing assessment depends on the evaluator's knowledge of anatomic structures and of neurophysiological processes involved in swallowing. Any alteration in those steps is denominated oropharyngeal dysphagia, which may have many causes, such as neurological or mechanical disorders. Videofluoroscopy of swallowing is presently considered to be the best exam to objectively assess the dynamics of swallowing, but the exam needs to be conducted under certain restrictions, due to patient's exposure to radiation, which limits periodical repetition for monitoring swallowing therapy. Another method, called cervical auscultation, is a promising new diagnostic tool for the assessment of swallowing disorders. The potential to diagnose dysphagia in a noninvasive manner by assessing the sounds of swallowing is a highly attractive option for the dysphagia clinician. Even so, the captured sound has an amount of noise, which can hamper the evaluator's decision. In that way, the present paper proposes the use of a filter to improve the quality of audible sound and facilitate the perception of examination. The wavelet denoising approach is used to decompose the noisy signal. The signal to noise ratio was evaluated to demonstrate the quantitative results of the proposed methodology. (C) 2007 Elsevier Ltd. All rights reserved.34214815