Bibliometric analysis on the papers dedicated to microplastics in wastewater treatments

The presence of microplastics (MPs) in the environment is becoming a problem for soils and seas, as well as for the food chain of animals and humans. The scientific community has been called upon to contribute to solving the problem and several papers have been published, especially in the last decade. The aim of this work is to carry out a bibliometric analysis of the scientific literature dedicated to the problem of MPs, highlighting its course over the years, and to identify the sectors to which the research could be profitably addressed. The VOSviewer software has been used to perform the analysis of the data in which specific maps were used to represent the network of the relationships among countries, journals, organizations, authors, and keywords related to the investigated topic and subtopics. The results of the survey demonstrated that during the investigated range of time, most attention has been paid to the individuation of the MPs, and to marine pollution, while a gap seems to exist in the possible advanced oxidation processes specifically addressing the degradation of MPs and their derivates

Insider Trading Around Convertible Security Calls

This study examines the nature of insider trading of common stock around conversion-forcing calls of convertible securities.  Managers of call firms significantly increase their frequency of stock sales after call announcements.  Also after the call, substantially fewer call firms are classified as net buyers and a significantly greater number of call firms are classified as net sellers.  This evidence suggests that managers alter their trading behavior as though calls are associated with negative information about their firms' prospects

The Importance of Call Delays and Cash Flow Positions in Evaluating the Information Content of Convertible Preferred Stock Calls

We examine a sample of in-the-money convertible preferred stock calls and find that they are delayed. We find that the length of the call delay does not depend on the relation between the preferred stock dividends and the pro rata common dividends to be paid on conversion. Thus, our evidence suggests that preferred stock calls may be used for signaling purposes. In support of this, we find that only delayed calls (i.e., those with potential signaling elements) are viewed negatively by equity investors. We also show that, in responding to delayed call announcements, investors appear to react to two distinct information elements. First, price responses to delayed calls are increasingly negative the larger the cash flow disadvantage to calling. In other words, common investors respond more negatively to calls when the forced conversion results in convertible holders receiving larger dividends than were previously required. Second, both cash flow advantage and cash flow disadvantage firms experience significant downward shifts in earnings growth during post-call periods, suggesting that delayed calls are timely signals of decreasing profitability

Effect of potential and chlorides on photoelectrochemical removal of diethyl phthalate from water

Removal of persistent pollutants from water by photoelectrocatalysis has emerged as a promising powerful process. Applied potential plays a key role in the photocatalytic activity of the semi-conductor as well as the possible presence of chloride ions in the solution. This work aims to investigate these effects on the photoelectrocatalytic oxidation of diethyl phthalate (DEP) by using TiO2 nanotubular anodes under solar light irradiation. PEC tests were performed at constant potentials under different concentration of NaCl. The process is able to remove DEP following a pseudo-first order kinetics: values of kapp of 1.25 × 10−3 min−1 and 1.56 × 10−4 min−1 have been obtained at applied potentials of 1.8 and 0.2 V, respectively. Results showed that, depending on the applied potential, the presence of chloride ions in the solution affects the degradation rate resulting in a negative effect: the presence of 500 mM of Cl− reduces the value of kapp by 50 and 80% at 0.2 and 1.8 V respectively

Assessing an electrochemical process for the treatment of tar-containing wastewater with hydrogen recovery

Biomass gasification generates syngas with low carbon emissions but produces tar-contaminated wastewater that challenges environmental sustainability. This study explored using an alkaline electrolysis process with a DSA anode to remove organic pollutants from the effluent of a wet scrubber in a biomass gasification plant's syngas clean-up system. The effect of current density (16, 80, 160 mA cm−2), area-to-volume ratio (0.03 and 0.15 cm−1), and organic load on the process performances was assessed by monitoring total organic carbon, chemical oxygen demand and UV–Vis analyses; the phenolic fraction was also analysed with 4-aminoantipyrine colorimetric method. A kinetic analysis with zero-order and pseudo-first-order kinetic models was done for the relevant parameters, and the kinetic constants (kapp) were evaluated under all the explored conditions. Results showed lower organic loads (higher dilution), as well as increasing current densities, have a beneficial effect on the phenol removal and mineralisation, achieving up to 50 % mineralisation in 8 h with 1:100 wastewater at 160 mA cm−2 and 0.15 cm−1. Also, reducing the area-to-volume ratio leads to slower mineralisation processes. On the other hand, adopting low current densities with high organic loads lead to 100 % instantaneous current efficiency, in which the oxygen evolution reaction is fully suppressed, and pure hydrogen is produced. Insights into the economic aspects of the process in terms of energy per order and energy per mass were given: the energy consumption for the most favourable condition is 15.95 kWh kg−1, corresponding to 960 kWh m−3 and a total cost of 72 € m−3

Chemometric Models Applied to Raman Spectroscopy for Bioprocess Monitoring

This work investigates the development of a Raman spectroscopy-based sensor for the quantitative analysis of products obtained from the fermentation to ethanol of the hydrolyzed product of brewer’s spent grain. Partial least squares (PLS) and variable importance in projection (VIP) methods were applied in order to correlate the information contained in the Raman spectra to the concentration of the compounds investigated

Electrochemical synthesis of polyaniline/metal-based anodes and their use in microbial fuel cell

A limited number of metals may be suitable as bioanode material: noble metals, such as gold and platinum, could be the optimum choice being electrochemically inert in the operational potential window of the bioelectrochemical system. However, high costs limit their wide scale application. Even though its antimicrobial nature, copper is being considered as a promising alternative anode material, due to its high conductivity, that allows minimising the electrode material costs. Literature research indicated that high-performing electrochemically active biofilms may be grown on this metal. In the present work, gold and copper substrates have been coated by a conductive polymer (PANI), using a layer – by – layer procedure: surface grafting by reduction of 4-nitrobenzendiazonium salt was followed by reduction of nitro- to amino-groups; PANI was electrodeposited on this under-layer. The synthesized anodes were tested as working electrodes (WE) in a microbial fuel cell fed with anaerobic sludge and acetate; to assess the growth of the biofilm on the WE surface, the trend of the bioelectrocatalytic current of acetate oxidation was monitored over time. Cyclic voltammetries reveal the presence of typical redox couples related to the presence of electroactive microorganisms on the electrode surface. Preliminary data show bioelectrochemical activity on polyaniline-coated metal surfaces

Interferometric Studies of the extreme binary, ϵ\epsilon Aurigae: Pre-eclipse Observations

We report new and archival K-band interferometric uniform disk diameters obtained with the Palomar Testbed Interferometer for the eclipsing binary star $\epsilon$ Aurigae, in advance of the start of its eclipse in 2009. The observations were inteded to test whether low amplitude variations in the system are connected with the F supergiant star (primary), or with the intersystem material connecting the star with the enormous dark disk (secondary) inferred to cause the eclipses. Cepheid-like radial pulsations of the F star are not detected, nor do we find evidence for proposed 6% per decade shrinkage of the F star. The measured 2.27 +/- 0.11 milli-arcsecond K band diameter is consistent with a 300 times solar radius F supergiant star at the Hipparcos distance of 625 pc. These results provide an improved context for observations during the 2009-2011 eclipse.Comment: Accepted for Ap.J. Letters, Oct. 200

Choosing and evaluating randomisation methods in clinical trials: a qualitative study

Background: There exist many different methods of allocating participants to treatment groups during a randomised controlled trial. Although there is research that explores trial characteristics that are associated with the choice of method, there is still a lot of variety in practice not explained. This study used qualitative methods to explore more deeply the motivations behind researchers’ choice of randomisation, and which features of the method they use to evaluate the performance of these methods. Methods: Data was collected from online focus groups with various stakeholders involved in the randomisation process. Focus groups were recorded and then transcribed verbatim. A thematic analysis was used to analyse the transcripts. Results: Twenty-five participants from twenty clinical trials units across the UK were recruited to take part in one of four focus groups. Four main themes were identified: how randomisation methods are selected; researchers’ opinions of the different methods; which features of the method are desirable and ways to measure method features. Most researchers agree that the randomisation method should be selected based on key trial characteristics; however, for many, a unit standard is in place. Opinions of methods were varied with some participants favouring stratified blocks and others favouring minimisation. This was generally due to researchers’ perception of the effect these methods had on balance and predictability. Generally, predictability was considered more important than balance as adjustments cannot be made for it; however, most researchers felt that the importance of these two methods was dependent on the design of the study. Balance is usually evaluated by tabulating variables by treatment arm and looking for perceived imbalances, predictability was generally considered much harder to measure, partly due to differing definitions. Conclusion: There is a wide variety in practice on how randomisation methods are selected and researcher’s opinions on methods. The difference in practice observed when looking at randomisation method selection can be explained by a difference in unit practice, and also by a difference in researchers prioritisation of balance and predictability. The findings of this study show a need for more guidance on randomisation method selection

Magnetic phase diagram of cubic perovskites SrMn_1-xFe_xO_3

We combine the results of magnetic and transport measurements with Mossbauer spectroscopy and room-temperature diffraction data to construct the magnetic phase diagram of the new family of cubic perovskite manganites SrMn_1-xFe_xO_3. We have found antiferromagnetic ordering for lightly and heavily Fe-substituted material, while intermediate substitution leads to spin-glass behavior. Near the SrMn_0.5Fe_0.5O_3 composition these two types of ordering are found to coexist and affect one another. The spin glass behavior may be caused by competing ferro- and antiferromagnetic interactions among Mn^4+ and observed Fe^3+ and Fe^5+ ions.Comment: 8 pages, 10 figures, revtex, accepted to Phys. Rev.