OMW spillage control tool based on tracking p-Coumaric acid degradation by HPLC.

Olive mill wastewater (OMW) is a major watercourse pollutant agent with a high concentration of phenolic compounds. It is estimated that 30 million OMW m3 are released into rivers every year. Protecting the health of these courses against the uncontrolled discharges implies establishing an adequate legislation, where spillage control tools play a fundamental role. In this paper, a new tool for OMW spillage control is discussed. It is based on the use of a RP-HPLC-UV protocol to track p-Coumaric acid (pCA), a characteristic OMW phenolic compound, and its derivative compounds through their chemical oxidation and biological anaerobic degradation. Laboratory assays and real-life experiences allowed to determine degradation routes and apparition times for every pCA derivative, making it possible to detect an OMW spill and assess its age. Moreover, this RP-HPLC-UV introduces solid advantages over previous detection procedures, namely, quicker response times and smaller costs than HPLC methods and superior specificity than colorimetric methods. Finally, this tool was put to test in an actual OMW-polluted watercourse. In all scenarios, the tool demonstrated solid reliability.

Order/disorder phenomena in Zn1-xMnxGa2Se4 ordered vacancy compounds: high temperature neutron powder diffraction experiments.

We present a study of order-disorder phenomena in the series of tetrahedral ordered vacancy compounds Zn1-xMnxGa2Se4 by means of time-of-flight neutron diffraction at high temperature together with dc magnetic susceptibility, Raman spectroscopy, differential thermal analysis and optical absorption experiments. Samples of nominal composition x = 0, 0.24, 0.5, 0.77 and 1 have been studied. An order-disorder phase transition has been detected, with Tc ranging from 472 to 610 ° C, which involves a structural change from a defect chalcopyrite phase, with I4 space group (s.g.) and three different cation sites, to a partially disordered defect stannite, in which Zn, Mn and half of the Ga ions share the 4d site in I42m s.g. Neither the vacancies nor the Ga ions occupying site 2a are involved in the phase transition. An additional ordering process is observed on approaching the phase transition from below, which is attributed to several factors: the activation of cation diffusion at ∼300 ° C, the partially disordered cation distribution exhibited by the as-grown single crystals and the preference of Mn atoms for the 2d crystallographic site in the I4 structure. The reversibility of the phase transition is analysed with the aid of magnetic, optical and Raman experiments.

Captación pulmonar de 99mTc-pertecnetato al realizar gammagrafía tiroidea / Lung accumulation of 99mTc-pertechnetate in thyroid scintigraphy

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