Sources and sinks of hydroxyl radicals upon irradiation of natural water samples

Hydroxyl radical formation rates, steady-state concentration, and overall scavenging rate constant were measured by irradiation of surface lake water samples from Piedmont (NW Italy) and nitrate-rich groundwater samples from Moldova (NE Romania). Dissolved organic matter (DOM) was the main source and sink of *OH upon lake water irradiation, with [*OH] being independent of DOM amount. Water oxidation by photoexcited DOM is a likely *OH source in the presence of very low levels of nitrate and dissolved iron. Under different circumstances it is not possible to exclude other processes, e.g., DOM-enhanced photo-Fenton reactions. Under the hypotheses of no interaction and absence of mutual screening of radiation, nitrate would prevail over DOM as *OH source for a NO3-/DOM ratio higher than 3.3 x 10(-5) (mol NO3-) (mg C)(-1), DOM prevailing for lower values. Substantial DOM photolability was observed upon irradiation of nitrate-rich groundwater, mainly due to the elevated *OH generation rate. For the first time to our knowledge, evidence was also obtained of the photoformation of potentially toxic and/or mutagenic nitroaromatic compounds upon irradiation of natural lake water and groundwater samples, proportionally to the nitrate levels.     

Guidelines for the Integration of Autonomous UAS into the Global ATM

The growing social and economic interest in new unmanned aircraft systems (UASs) applications demands that UASs operate beyond the segregated airspace they are currently able to fly. However, UAS operations in non-segregated airspace should be regulated by aeronautical authorities before UASs can share airspace with manned aircraft. It has been a challenge for regulatory authorities to define these regulations because they do not understand the topic well. In addition, there is no consensus in the academic community regarding UAS concepts, such as taxonomy and features. This study proposes guidelines that could support UAS regulations for the future integration of autonomous UASs into the Global Air Traffic Management System (GATM). These guidelines are based on three viewpoints: the aircraft, the piloting autonomous system (PAS) and the integration of autonomous UASs into non-segregated airspace. We recommend that the UAS concept should be based on genuine aeronautical precepts, which would be directly applied, without terminology or conceptual adaptations, for the integration of these aircraft into airspace according to the GATM paradigm.     

Clustering Web pages based on their structure

Several techniques have been recently proposed to automatically generate Web wrappers, i.e., programs that extract data from HTML pages, and transform them into a more structured format, typically in XML. These techniques automatically induce a wrapper from a set of sample pages that share a common HTML template. An open issue, however, is how to collect suitable classes of sample pages to feed the wrapper inducer. Presently, the pages are chosen manually. In this paper, we tackle the problem of automatically discovering the main classes of pages offered by a site by exploring only a small yet representative portion of it. We propose a model to describe abstract structural features of HTML pages. Based on this model, we have developed an algorithm that accepts the URL of an entry point to a target Web site, visits a limited yet representative number of pages, and produces an accurate clustering of pages based on their structure. We have developed a prototype, which has been used to perform experiments on real-life Web sites.     

Active video game head movement inputs

Virtual reality has been extensively studied for applications in rehabilitation. With the development of active video games, these commercial products can also be considered for inclusion in a patient’s rehabilitation program. In this study, the Sony EyeToy ^® and PlayStation 2 ^® were used with the AntiGrav? game to evaluate the user’s head movement actions. The game required lateral head, body, and arm movements. Over the course of 9 sessions of game play, average and maximum head excursions remained constant. However, the frequency of head movement increased over the sessions. The results suggest that the video game could be used for postural balance rehabilitation through head movements, and their effect on the vestibular system. Future work will evaluate how such vestibular exercise, and an increase in head movement frequency over training sessions can support postural balance improvements.     

Dechlorinating ability of TCE-fed microcosms with different electron donors

The main objective of the work presented herein is to assess the effect of different electron donors (butyric acid and methanol) on the dechlorinating activity of two microbial cultures where active methanogenic populations are present, in an effort to evaluate the importance of the electron donor selection process. The ability of each anaerobic culture to dechlorinate TCE, when enriched with either butyric acid or methanol, was verified based on the results of gas chromatography. In addition, the fluorescent in situ hybridization (FISH) and the polymerase chain reaction (PCR) methods gave positive results for the presence of Dehalococcoides spp. According to results of the batch tests conducted in this study, it appears that the selection of the electron donor for stimulating TCE dechlorination depends on microbial culture composition; therefore, the decision on the appropriate electron donor should be based on site-specific microcosm studies.     

Process data reconciliation in the presence of non-uniform measurement errors

The goal of flow rates reconciliation was to adjust measured values and estimate unmeasured streams so as to balance both measured and unmeasured values, identify gross errors and detect leaks and losses. Thus, data reconciliation plays a key role in the monitoring of industrial plants for the early detection of critical events which might cause environmental and economic damages, and it is,therefore, an essential component of any clean technology process. Consequently, any method that improves the accuracy of the reconstructed data by considering more realistic assumptions on the statistical nature of the data can add considerably to the overall reliability of the process. The reconciliation procedure is statistical in nature and requires adequate information on the structure of the random errors of the flow rates measured. A frequent assumption is the homoscedasticity and the independence of the errors affecting different streams. This assumption leads to efficient algorithms based on advanced linear algebra decompositions, such as QR or Singular Value Decomposition, but it frequently leads to biased estimates, especially when the values of flow rates vary over two or more orders of magnitude. The goal of this article was to show the importance of considering general heteroscedasticity when reconciling flow rates. Errors are supposed to be normally distributed according to \(\varepsilon_{\text{i}} \cong N(0,\,\sigma_{0} L_{\text{i}}^{ 2\eta } )\) , where \(L_{\text{i}}\) is the measurement of the ith flow rate and \(\theta\)  =  \(\left\{ {\theta |\sigma_{0} ,\eta } \right\}\) is a set of two parameters to be estimated along with the adjustments to the measured flow rates. Therefore, the overall variance–covariance is characterised by 3 parameters \(\sigma_{0} ,\eta\) and the correlation factor among measurement errors ρ. The algorithm here proposed is based on conditional optimality, and it carries out the whole optimisation in terms of the parameters \(\theta\) only, the unknown adjustments being expressed at each iteration as functions of \(\theta\) .     

Nanometer sized polymer based Schottky junctions

The aim of this work was to realize and characterize rectifying junctions with nanometer thickness based on conducting polymers. Various monolayer films were deposited onto different flat graphite electrodes in order to obtain the Schottky interfaces. The second electrical contact was realized by approaching the monolayer film with sharp tip electrode at nanometric distances, in order to create tunneling barriers. A couple of hundred of junctions were realized following this procedure. The investigated junctions have shown rectifying behavior on the current/voltage characteristics in the 96% of the cases. The analysis of the current/voltage characteristics revealed the typical behavior of Schottky barriers. The ideality factor and the Schottky barrier of the junctions were calculated. Moreover, a linear relationship between the threshold voltage and the tunneling barrier width was revealed. In our knowledge, this is the first report of a Schottky junction realized with a monolayer of polymer film.