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Antimony (Sb) pollution has raised increasing public concerns and its rapid on-site screening is central for the risk assessment. Herein, we proposed two gel-based methods based on colorimetric diffusive equilibrium in thin films (DET) and surface-enhanced Raman scattering (SERS), for two-dimensional imaging and sensitive detection of Sb(III) by revisiting the phenylfluorone (PhF) complexation reaction. PhF was well dispersed in the polyvinyl alcohol (PVA) hydrogel and reacted with Sb(III) in the DET gel to form a strong PhF-Sb(III) complex. The distribution of Sb(III) was easily visualized at a submillimeter resolution using computer imaging densitometry, with a detection limit (LOD) of ∼100 nmol L−1. Field application in the Sb mine area reveals limited dissolved Sb(III) penetrating the redox barrier below the sediment-water interface by 20 mm in rivers and tailing pond sediments. To improve the detection sensitivity and apply the principle to trace Sb quantification, a SERS platform was established by anchoring PhF on the hydrogel-stabilized Ag nanoparticles via C–O–Ag bonding to specifically detect Raman-inactive Sb(III). Benefiting from the high SERS activity of PhF and enrichment ability of hydrogel, Sb(III) was quantified with a LOD of 1.2–10.7 nmol L−1 depending on the sample volume. The coexisting ions at a 100-fold higher concentration than Sb(III) resulted in only 3.3–10.4 % variation in SERS intensity, indicating a negligible interference on the SERS platform. The platform exhibited a RSD of 6.6–13.1 % and acceptable recoveries for various environmental matrices, highlighting its promise in on-site application. [Display omitted] • Two polyvinyl alcohol gel methods for Sb(III) detection were developed. • Colorimetric DET gel provides submillimeter 2D imaging at a 100 nM detection limit. • Enrichment-type SERS gel achieves detection limits as low as 1.2 nM. • Field study shows limited Sb(III) penetration beyond the sediment-water interface. [ABSTRACT FROM AUTHOR]

To progress towards as quick as possible feasible pre-design of space missions, spacecraft early design today is organized gathering together experts from different spacecraft subsystems that share information (and results). This Concurrent Design (CD) approach needs accurate but quick solutions from all subsystems involved in each phase of that mission early design. At IDR/UPM Institute researchers have been working in simplified models for the spacecraft power distribution subsystem. In the present paper three models, for solar panels, the battery and DC-DC converters are described and tested with experimental data. The models were designed to be coupled within the simulation of a spacecraft mission. The model regarding the solar panels is focused on accurately estimate the power production from the panels, whereas the model of the batteries is based on the discharged energy rate as the main/control parameter instead of the discharged/charged ampere·hour rate. Finally, the solar-panels/battery coupled design is described in this paper, the UPMSat-2 mission being used as case study. • The testing results related DC-DC spacecraft converters are used to model these parts. • Spacecraft solar panels are modeled with simplified approaches based on information from the manufacturer. • A simple model for Li-ion battery performance is proposed. • The power system of the UPMSat-2 spacecraft mission is simulated. • DET and MPPT are compared, DET being more efficient for the UPMSat-2 mission. [ABSTRACT FROM AUTHOR]

Abstract The use of grasses as cover crops in the off-season of cash crops under no-till has been largely adopted. However, soil phosphorus (P) uptake was previously shown to be reduced when ruzigrass is introduced in the rotation, affecting the viability and sustainability of this cropping system. The objective of this study was to assess the effect of ruzigrass on soil P availability and desorption kinetics under different P fertilizer application rates. A long-term field experiment where soybean (Glycine max) has been grown in rotation with ruzigrass (Urochloa ruziziensis) or fallow for 10 years, with the application of 0, 13, and 26 kg ha−1 of P, was evaluated for two consecutive years. Soil P desorption kinetics was assessed using diffusive equilibrium (DET) and gradient in thin films (DGT) techniques, as well as the DGT-induced fluxes in soils model (DIFS). Microbial biomass P (MBP) was assessed to verify if soil solution P (P DET) was reduced due to immobilization by microorganisms. Ruzigrass reduced MBP and P DET especially when P fertilizer was applied. The concentration of labile P (P DGT) was also lower after ruzigrass than in fallow. The soil ability to resupply P to soil solution was lower after ruzigrass regardless of P rates due to a slower desorption in response to the perturbation imposed by DGT. Growing ruzigrass as cover crop in the soybean off-season decreases soil P availability regardless of P fertilizer application rates by fundamentally reducing P mobility and P resupply from soil solid phase into soil solution. Highlights • The use of ruzigrass as cover crop affect soil P availability in the long-term. • Soil P desorption kinetics was assessed using diffusive gradient in thin films (DGT). • The use of DGT provided new insights into P availability, by considering the P diffusion and resupply process. • Ruzigrass decreases P availability by reducing P mobility and resupply from soil solid phase into soil solution. [ABSTRACT FROM AUTHOR]

Abstract The tanning industry uses large quantities of Cr whose contribution to the contaminant burden of aquatic organisms is not yet fully understood. The present study investigated Cr bioaccumulation by indigenous chironomids in a freshwater ecosystem impacted by tannery effluents. Total Cr content in sediments and in chironomids was determined on several occasions. Chromium distribution among sediments and pore waters, and Cr speciation in overlying and pore waters were studied in detail to understand possible factors controlling Cr bioavailability to chironomids. Total chromium concentration ranged from 69 to over 3000 μg g−1 dry weight in sediments and from negligible to over 300 μg g−1 dry weight in chironomids (values corrected for sediment gut content). Filterable (<0.45 μm) Cr concentration in overlying waters and pore waters from the surface sediment layers (upper 2 cm) ranged from 3 to 120 μg L−1, with Cr(VI) representing 0.5–28% of the total filterable Cr. Chromium profiles in pore waters as determined by diffusive equilibration in thin films (DET) and diffusive gradient in thin films (DGT) were comparable. DGT-labile Cr accounted for <2% of the total Cr measured by DET. Although Cr concentrations in sedimentary and aqueous matrices were not directly proportional to Cr levels measured in chironomids, the available findings suggested that Cr inputs from tanneries were bioavailable to resident chironomids. These observations are of particular importance considering that Cr(III), putatively of limited bioavailability and ecotoxicological concern, is the predominant redox form of Cr in bed sediments impacted by tannery discharges. The companion paper provides further insight into Cr bioavailability and effects in tannery impacted ecosystems using a combination of in situ and laboratory approaches. Graphical abstract Unlabelled Image Highlights • Leather tanning uses large quantities of Cr(III) that mostly accumulates in sediments. • Bioavailability of chromium at tannery-contaminated sites is not fully understood. • Indigenous chironomids show Cr accumulation in zones impacted by tannery discharges. • Cr accumulation in chironomids is not proportional to Cr concentration in sediments. • Chironomid Cr burden exceeds reported tolerance levels for more sensitive organisms. [ABSTRACT FROM AUTHOR]

Abstract Lipidic cubic phase systems (LCPs) are excellent carriers for immobilized enzymes due to their biocompatibility and well-defined nanoporous structure. Lipidic cubic phases act as a convenient matrix to incorporate enzymes and hold them in the vicinity of electrode surfaces in their fully active forms. Corynascus thermophilus cellobiose dehydrogenase (Ct CDH) was trapped in a monoolein cubic phase, which increased not only its stability, but also its catalytic performance with both enhanced mediated and direct electron transfer with electrodes. For studies of mediated electron transfer, three mediators with different formal potentials (E°′) were employed: horse-heart cytochrome c (cyt c), electron acceptor active with the cytochrome domain of Ct CDH, and 2,6-dichlorophenolindophenol (DCPIP) as well as hexaammineruthenium(II) chloride [Ru(NH 3)Cl 2 ] both electron acceptors with the dehydrogenase domain. Ru(NH 3)Cl 2 , having the most negative E°′ of − 0.138 V vs. Ag | AgCl at pH 7.5, gave a catalytic current for lactose oxidation of 32.10 μA cm− 2 in MOPS buffer at pH 7.5. The process carried out in the same solution but under direct electron conditions transfer resulted in a catalytic current of 9.22 μA cm− 2. Electrodes covered with Ct CDH in a LCP film retained their catalytic activity after 28 days showing a slightly increased current density after 6 days. Graphical abstract Image 2 Highlights • Lipidic cubic phase enhances enzyme catalytic activity. • Electrodes with CtCDH in cubic phase are more stable than with adsorbed enzyme. • Both DET and MET mechanism of Ct CDH can be observed in cubic phase. [ABSTRACT FROM AUTHOR]

• A DET analysis has been applied to a BWR during a hot shutdown phase. • RAVEN acts as a logic driver while MELCOR simulates the thermal–hydraulic response. • Cyberattack alters plant state variable processed by I&C disabling coolant injection systems. • DET focuses on cyberattack and recovery time that would compromise core integrity. Over the last decade, probabilistic risk assessment (PRA) for nuclear power plants shifted its focus toward simulation-based methods of evaluating safety and risk aspects. Classical reliability modeling based on static Boolean structures does not capture the dynamic nature of plants experiencing accident sequences. Dynamic PRA extends conventional reliability modeling, adding a higher degree of variability to events occuring during accident sequences. This paper demonstrates the capability of a new dynamic event tree (DET) analysis tool applicable to severe accident sequences. A cyberattack was assumed to penetrate the instrumentation system of a boiling water reactor during its hot shutdown phase, altering the thermal–hydraulic variables being processed. The analysis focused on scenarios that lead to the core being uncovered, in which the peak cladding temperature is reached due to the disabling of the cooling systems. A limiting surface is defined, associating the cyberattack timing to the recovery time limit that would compromise the core integrity. [ABSTRACT FROM AUTHOR]

In this study, polythiophene copolymers have been used as modifier for electrode surfaces in order to allow the immobilization of active pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH) and to simultaneously improve the direct electrical connection of the enzyme with the electrode. Polymer films are electrosynthesized in aqueous solution without the need of surfactants onto carbon nanotubes modified gold electrodes from mixtures of 3-thiopheneacetic acid (ThCH 2 CO 2 H) and 3-methoxythiophene (ThOCH 3 ) using a potentiostatic pulse method. Polythiophene deposition significantly improves the bioelectrocatalysis of PQQ-GDH: the process starts at − 200 mV vs. Ag/AgCl and allows well-defined glucose detection at 0 V vs. Ag/AgCl with high current density. Several parameters of the electro-polymerization method have been evaluated to maximize the anodic current output after enzyme coupling. The polymer deposited by this new procedure has been morphologically and chemically characterized by different methods (SEM, EDX, FT-IR, UV–Vis, XPS and Raman spectroscopy). The bioelectrocatalytic response towards increasing glucose concentrations exhibits a dynamic range extending from 1 μM to 2 mM. The low applied potential allows to avoid interferences from easily oxidizable substances such as uric acid and ascorbic acid. Short and long-term stability has been evaluated. Finally, the PQQ-GDH electrode has been coupled to a bilirubin oxidase (BOD)- and carbon nanotube-based cathode in order to test its performance as anode of a biofuel cell. The promising results suggest a further investigation of this kind of polymers and, in particular, the study of the interaction with other enzymes in order to employ them in building up biosensors and biofuel cells. [ABSTRACT FROM AUTHOR]

The consequences of a transient in an advanced sodium-cooled fast reactor are difficult to capture with the traditional approach to probabilistic risk assessment (PRA). Numerous safety-relevant systems are passive and may have operational states that cannot be represented by binary success or failure. In addition, the specific order and timing of events may be crucial which necessitates the use of dynamic PRA tools such as ADAPT. The modifications to the SAS4A/SASSYS-1 sodium-cooled fast reactor safety analysis code for linking it to ADAPT to perform a dynamic PRA are described. A test case is used to demonstrate the linking process and to illustrate the type of insights that may be gained with this process. Newly-developed dynamic importance measures are used to assess the significance of reactor parameters/constituents on calculated consequences of initiating events. [ABSTRACT FROM AUTHOR]

Arsenic concentration in the pore water of paddy fields (C soln ) irrigated with arsenic-rich groundwater is a key parameter in arsenic uptake by rice. Pore water extracts from cores and in situ deployment of DET and DGT probes were used to measure the arsenic concentration in the pore water. Ferrihydrite (Fe) and titanium dioxide (Ti) were used as DGT binding agents. Six sampling events during different growing stages of the rice, inducing different biogeochemical conditions, were performed in one rice field. A time series of DGT experiments allow the determination of an in situ arsenic diffusion coefficient in the diffusive gel (3.34 × 10 − 6 cm 2 s − 1 ) needed to calculate the so-called C DGT (Fe) and C DGT (Ti) concentrations. Over 3 days of a given sampling event and for cores sampled at intervals smaller than 50 cm, great variability in arsenic C soln concentrations between vertical profiles was observed, with maxima of concentrations varying from 690 to 2800 μg L − 1 . Comparisons between arsenic measured C sol and C DET and calculated C DGT (Fe) and C DGT (Ti) concentrations show either, in a few cases, roughly similar vertical profiles, or in other cases, significantly different profiles. An established iron oxyhydroxide precipitation in the DET gel may explain why measured arsenic C DET concentrations occasionally exceeded C soln . The large spread in results suggests limitations to the use of DET and type of DGT probes used here for similarly representing the spatio-temporal variations of arsenic content in soil pore water in specific environmental such as paddy soils. [ABSTRACT FROM AUTHOR]

Novel label-free impedimetric platform based on a three-dimensional interdigitated electrode array (3D-IDEA) sensor and new conductive polymer as a transducer for oxidoreductases is introduced. This platform is cost-effective, simple to construct and miniaturize. Monomer of conductive polymer N-(N’,N’-diethyldithiocarbamoylethylamidoethyl) aniline (AnD) was deposited onto 3D-IDEA by chemical polymerisation. It was found that the polymer film resistance depends on the redox-potential of the solution. For the first time polyAnD was used as enzyme immobilisation matrix. Pyrroloquinolinequinone (PQQ) dependent alcohol and glucose dehydrogenases were immobilized on 3D-IDEA covered with polyAnD by two different methods. 3D-IDEA sensors with enzymes, which were immobilised by physisorption on polyAnD layer, showed specific response in the presence of 1 μM of the corresponding substrates. Obtained results revealed that PQQ dependent dehydrogenases can re-oxidize on polyAnD via direct electron transfer (DET) from enzyme active site to the polymer surface. This process can be monitored by methods of electrochemical impedance spectroscopy (EIS) and chronoamperometry. Presented study shows that EIS method gives a useful tool for research of re-oxidation process and interaction of electroactive enzymes with conducting materials giving information required to construct and develop analytical devices. [ABSTRACT FROM AUTHOR]

Measurements of porewater alkalinity are fundamental to the study of organic matter mineralization in sediments, which plays an essential role in the global cycles of carbon and nutrients. A new colorimetric diffusive equilibration in thin film (DET) technique is described for measuring two-dimensional total alkalinity distributions in sediment porewaters at high resolution (1–2 mm 2 ). Thin polyacrylamide hydrogel layers (0.8 mm) equilibrate with the porewater and, after removal, are immediately laid onto another hydrogel containing formic acid, which reacts with alkalinity-generating species, and the pH-indicator bromophenol blue. The resultant color change is quantified using computer-imaging densitometry. The lower limit of detection is 0.2 meq L −1 and the upper measurement limit is 8 meq L −1 . Deployment in seagrass colonized sediment revealed high levels of spatial heterogeneity in the porewater alkalinity distribution, with concentrations ranging from 2.28 meq L −1 in the overlying water to 5.13 meq L −1 in some parts of the sediment. This is the first time that two-dimensional, high-resolution distributions of porewater alkalinity have been measured. [ABSTRACT FROM AUTHOR]

Abstract: We introduce diffracted electron tracking (DET), which combines two electron microscopy techniques, electron backscatter diffraction and the use of an environmental cell in a scanning electron microscope to measure changes in nanocrystal-orientation. The accuracy of DET was verified by measuring the motion of a flat gold crystal caused by the rotation or tilting of the specimen stage. DET was applied to measure the motion of semi-fixed gold nanocrystals in various environments. In addition to large motions induced in water environment, DET could detect small differences in the three-dimensional (3D) motion amplitude between vacuum environment and an Ar gas environment. DET promises to be a useful method for measuring the motion of single nanocrystals in various environments. This measuring technique may be used in a wide range of scientific fields; for example, DET may be a prospective method to track the single molecule dynamics of molecules labeled with gold nanocrystals. [Copyright &y& Elsevier]

Abstract: Constrained DET (Diffusive Equilibration in Thin films) probes equipped with 75 sampling layers of agarose gel (DGT Research©) were used to sample bottom and pore waters in marine sediment with a 2 mm vertical resolution. After retrieval, each piece of hydrogel, corresponding to 25 μL, was introduced into 1 mL of colorimetric reagent (CR) solution consisting of formic acid and bromophenol blue. After the elution/reaction time, absorbance of the latter mixture was read at 590 nm and compared to a calibration curve obtained with the same protocol applied to mini DET probes soaked in sodium hydrogen carbonate standard solutions. This method allows rapid alkalinity determinations for the small volumes of anoxic pore water entrapped into the gel. The method was assessed on organic-rich coastal marine sediments from Thau lagoon (France). Alkalinity values in the overlying waters were in agreement with data obtained by classical sampling techniques. Pore water data showed a progressive increase of alkalinity in the sediment from 2 to 10 mmol kg−1, corresponding to anaerobic respiration in organic-rich sediments. Moreover, replicates of high-resolution DET profiles showed important lateral heterogeneity at a decimeter scale. This underlines the importance of high-resolution spatial methods for alkalinity profiling in coastal marine systems. [Copyright &y& Elsevier]

Abstract: Here we evaluate a new field methodology for the deployment of Diffusive Equilibrium in Thin Films (DET, protected in stainless steel holders) in coarse riverbed sediments based on that originally developed for fine-grained sediments and soils. Concentration gradients of NO3 −, NH4 + and dissolved Mn were measured at cm resolution. We observed fine scale changes in NO3 −, NH4 +, and Mn concentrations in the river bed (0–30cm) that were only evident at high resolution and compared them to profiles of NO3 − and NH4 + obtained with low resolution multilevel piezometers. The range in concentrations of NO3 − and NH4 + measured through DET was larger than those measured at coarse resolution through pore water sampling from multilevel piezometer in the riverbed over the 30cm depth. According to the results, high resolution profiles of redox sensitive chemical species in riverbeds could help in identifying and resolving hotspots of biogeochemical activity. Measurements of NH4 + using DET were higher than measurements in pore water collected from the multilevel samplers. Further studies are needed to establish whether there is a systematic bias associated with either procedure for the measurement of NH4 +. [Copyright &y& Elsevier]

Abstract: The recently developed colorimetric diffusive equilibration in thin films (DET) technique for the in situ, high-resolution measurement of iron(II) in marine sediments is optimized to allow measurement of the higher iron concentrations typical of freshwater sediment porewaters. Computer imaging densitometry (CID) is used to analyze the retrieved samplers following exposure to ferrozine, a colorimetric reagent selective for iron(II). The effect of ferrozine concentration, image processing parameters and ionic strength are investigated to improve the applicability of this technique to a wider range of aquatic systems than reported in the first publications of this approach. The technique was optimized to allow detection of up to 2000μmolL−1 iron(II), a four-fold increase on the previous upper detection limit of 500μmolL−1. The CID processing of the scanned color image was also optimized to adjust the sensitivity of the assay as required; by processing the image with different color channel filters, the sensitivity of the assay can be optimized for lower concentrations (up to 100μmolL−1) or higher concentrations (up to 2000μmolL−1) of iron(II), depending on the specific site characteristics. This process does not require separate sampling probes or even separate scans of the DET gels as the color filter and grayscale conversion is done post-image capture. The optimized technique is very simple to use and provides highly representative, high-resolution (1mm) two-dimensional distributions of iron(II) in sediment porewaters. The detection limit of the optimized technique was 4.1±0.3μmolL−1 iron(II) and relative standard deviations were less than 6%. [Copyright &y& Elsevier]

Abstract: Wetlands are capable of reducing nutrient loadings to receiving water bodies, and hence many artificial wetlands have been constructed for wastewater nutrient removal. In this study, diffusive equilibrium in thin films (DETs) and equilibrium phosphorus concentration (EPC0) analysis were used to examine the role of sediment as a nutrient source or sink in a constructed treatment wetland in summer. The effect of dredging on sediment-water nutrient exchange was also studied. Soluble reactive phosphorus (SRP), ammonium (NH4 +) and sulphate (SO4 2−) concentration profiles were measured by DET across the sediment-water interface (SWI) in both a settling pond and iris reed bed within the wetland. The SRP concentrations in the sediment pore-waters of the settling pond were extremely high (up to 29,500μg l−1) near the SWI. This is over an order of magnitude higher than the levels found in the water column, which in turn are over an order of magnitude higher than environmental levels proposed to limit eutrophication in rivers. The profiles demonstrated an average net release of SRP and NH4 + from the settling pond sediment to the overlying water of 58mgm−2 d−1 (±32mgm−2 d−1 (1sd)) and 16mgm−2 d−1 (±25mgm−2 d−1 (1sd)), respectively. The DET SO4 2− concentration profiles revealed that the sediment was anoxic within 2cm of the SWI. Dredging of the reed bed made no significant difference to the P release characteristics across the SWI. The EPC0s were much lower than the SRP concentration of the overlying water, indicating that the sediment had the potential to act as a phosphate sink. The apparent contradiction of the DET and EPC0 results is attributed to the fact that DET measurements are made in situ, where as EPC0 measurements are ex situ. These results show that substantial releases of P can occur from wetland sediments, and also highlight the need for caution when interpreting ex situ EPC0 analytical results. [Copyright &y& Elsevier]

Abstract: Sedimentation ponds are widely believed to act as a primary removal process for phosphorus (P) in nutrient treatment wetlands. High frequency in-situ P, ammonium (NH4 +) and dissolved oxygen measurements, alongside occasional water quality measurements, assessed changes in nutrient concentrations and productivity in the sedimentation pond of a treatment wetland between March and June. Diffusive equilibrium in thin films (DET) probes were used to measure in-situ nutrient and chemistry pore-water profiles. Diffusive fluxes across the sediment–water interface were calculated from the pore-water profiles, and dissolved oxygen was used to calculate rates of primary productivity and respiration. The sedimentation pond was a net sink for total P (TP), soluble reactive P (SRP) and NH4 + in March, but became subject to a net internal loading of TP, SRP and NH4 + in May, with SRP concentrations increasing by up to 41μM (1300μl−1). Reductions in chlorophyll a and dissolved oxygen concentrations also occurred at this time. The sediment changed from a small net sink of SRP in March (average diffusive flux: −8.2μmolm−2 day−1) to a net source of SRP in June (average diffusive flux: +1324μmolm−2 day−1). A diurnal pattern in water column P concentrations, with maxima in the early hours of the morning, and minima in the afternoon, occurred during May. The diurnal pattern and release of SRP from the sediment were attributed to microbial degradation of diatom biomass, causing reduction of the dissolved oxygen concentration and leading to redox-dependent release of P from the sediment. In June, 2.7mol-Pday−1 were removed by photosynthesis and 23mol-Pday−1 were supplied by respiration in the lake volume. SRP was also released through microbial respiration within the water column, including the decomposition of algal matter. It is imperative that consideration to internal recycling is given when maintaining sedimentation ponds, and before the installation of new ponds designed to treat nutrient waste. [Copyright &y& Elsevier]

Abstract: The hypothesis that reducing conditions exist in localized zones of high organic matter, termed microniches, was first suggested over a century ago, but only relatively recently have high-resolution techniques been available to investigate them. In any sediment containing benthic fauna, bioturbation affects the distribution of a number of redox-sensitive components. Direct faecal deposition and the death of fauna may be expected to cause particles of labile organic matter (microniches) to be distributed heterogeneously within the sediment. This review discusses the significance and future direction of microniche studies by considering, exclusively, data obtained on a sub-mm scale that provide significant evidence for the existence and properties of microniches. Microelectrodes and planar optodes have shown the significant effect of burrowing organisms on localized O2 distributions and revealed distinct depletions in O2 due to microniches. Localized increases in pCO2 and decreases in pH measured by optodes were attributed to elevated activity at microniches. Diffusive gradients in thin-films have shown isolated supersaturation of metals and sulphide, providing evidence for possible simultaneous oxidation of organic matter by sulphate and iron oxides. The stochastic nature of these data and the lack of information for the same precise location hinders interpretation in terms of sediment diagenesis. If microniches are known to account for a significant proportion of organic matter degradation, re-examination of the current understanding of sedimentary diagenesis may be needed. Further investigation on the distribution and frequency of microniches is required, including a wider range of analytes, in order to estimate their cumulative effect on element diagenesis, immobilisation/remobilisation processes and ultimately pollutant fate. [Copyright &y& Elsevier]

Summary: DET (diffusive equilibrium in thin films) gel probes were used for sampling river-bed sediment porewaters, to characterise in situ soluble reactive phosphorus (SRP) concentration profiles and fluxes. DET probes were deployed in three contrasting rural streams: (1) a headwater ‘pristine’ stream, with minimal P inputs from low intensity grassland and no point sources, (2) an intensively cultivated arable catchment, and (3) a stream subject to high P loadings from sewage effluent and intensive arable farming. The DET results showed highly enriched porewater SRP concentrations of between ca. 400 and 5000μg-Pl−1 in the sewage-impacted stream. In contrast, the arable and pristine streams had porewater SRP concentrations <70μg-Pl−1 and <20μg-Pl−1, respectively. Porewater SRP concentration profiles in both the sewage-impacted and arable-impacted streams showed well-defined vertical structure, indicating internal sources and sinks of SRP within the sediment. However, there was little variability in porewater SRP concentrations in the pristine stream. The DET porewater profiles indicated net diffusion of SRP (a) from the overlying river water into the surface sediment and (b) from subsurface sediment upwards towards the sediment–water interface. A mass balance for the sewage-impacted site showed that the influx of SRP into the surface sediments from the overlying river water was small (ca. 1% of the daily river SRP load). The DET results indicated that, in the arable and sewage-impacted streams, the surface ‘cap’ of fine sediment may play an important role in inhibiting upward movement of SRP from subsurface porewaters into the overlying river water, under steady-state, low-flow conditions. [Copyright &y& Elsevier]

Abstract: Contaminated sediment from a marine harbour was maintained for 16 months in two flumes that continuously re-circulated the overlying water, sustaining a smooth flow at the sediment surface. The sediment was placed in one flume intact, while for the other it was pre-homogenised. The concentrations of trace metals in the porewaters were measured at a vertical resolution of 2 mm using the technique of diffusive equilibration in thin-films (DET) and microelectrodes were used to measure concentration profiles of oxygen and pH. Separate experiments showed good agreement between metals measured by DET and those measured in porewaters extracted by centrifugation and filtration. Local mobilisation of metals was measured in 2-dimensional arrays by deploying DGT (diffusive gradients in thin-films) probes. There were high concentrations of Fe in the porewaters, which limited the concentration of sulphide to less than 0.3 μM. With both DET and DGT measurements, there were sharply defined maxima of Cu and Cd within 2 mm of the sediment water interface, consistent with their release from organic material as it is oxidised. There was a Co maximum about 5–8 mm lower than the Cu and Cd maxima, apparently coincidental with Mn mobilisation. While there were clear Ni maxima, their location appeared to vary from being coincident with Co to a few mm above the Co maxima. The remobilisation of metals could not be explained by the pH gradients in the near-surface sediments. As sulphate reduction rates were appreciable, the apparent lack of metal mobilisation at depth was attributed to the formation of metal sulphides. The DGT measurements in the same probe were well replicated horizontally. This, the replication of the same features between flumes and the reasonable correspondence between DGT and DET, showed that the localised mobilisation of metals was associated with recent diagenetic processes, rather than the depositional history. There were substantial fluxes of Cu and Cd to the overlying water. Even though there were steep gradients of Fe, Mn, Ni and Co within 1 cm of the sediment–water interface, there was no clear evidence for any substantial metal fluxes across the interface. Adsorption of Mn to Fe oxides, rather than oxidation, may be responsible for its removal from solution at the same depth as Fe. [Copyright &y& Elsevier]

Abstract: High resolution profiles of Mn, Tl and Fe concentrations have been assessed in the pore waters of river Leie sediments at Warneton and Menen (at the border of Belgium and France) by DET (Diffusive Equilibrium in Thin Films) and DGT (Diffusive Gradients in Thin Films) techniques. The oxidized, solid Mn (IV), Tl (III) and Fe (III) compounds were reduced in the suboxic (+255 to −20 mV versus Standard Hydrogen Electrode (SHE)) riverine sediments and since these reduced species are much more soluble also they are released into the pore waters. The highest DET (total dissolved) concentrations of Fe (76 mg l−1), Mn (2 mg l−1) were observed at the station of Menen, while Tl maxima differed only slightly between the 3 surveys (21 to 27 μg l−1). The average ratios of Fe/Mn/Tl in the pore waters at the 3 sampling stations are fairly constant for both the DET and DGT samplings. However, the results indicate that compared to Fe and Tl a greater proportion of the Mn measured by DET is accumulated by DGT, reflecting the ready supply of Mn from solid phase to solution. [Copyright &y& Elsevier]

Abstract: Glucose biosensors based on direct electron transfer (DET) between two types of PQQ dependent glucose dehydrogenases: soluble (s-PQQ-GDH) and membrane-bound (m-PQQ-GDH) and modified carbon black electrodes were created. The behaviour of both enzymes on carbon paste electrodes was investigated and some differences were elucidated. It was demonstrated that for the achievement of DET between the adsorbed s-PQQ-GDH or m-PQQ-GDH and the carbon paste electrodes particular orientation of the enzymes is required. The stability and the selectivity of the biosensors were studied as well. The calculated inactivation constants for s-PQQ-GDH and m-PQQ-GDH-based biosensors were 0.001 and 0.0001min−1, respectively. Furthermore, the possibility to detect lactose concentration in dairy products was shown. [Copyright &y& Elsevier]

Abstract: The techniques of DET (diffusive equilibrium in thin films) and DGT (diffusive gradients in thin films) were applied to obtain high-resolution vertical profiles of trace metals in freshwater sediments. In the framework of the EU-Interreg project Stardust (http://www.vliz.be/projects/stardust/) between France and Belgium, in which the mobility of sediment bound metals is investigated, sediment samples were collected from the Upper Scheldt River (at Helkijn, Belgium) and the Leie River (at Warneton, located at the Belgian–French border). Intra- and inter-laboratory comparisons of the gel techniques were carried out between the two laboratories involved. In general, a good agreement was observed, taking sediment heterogeneity into account. At both stations, metal pore water profiles show more or less similar tendencies although the sediment at Warneton was more anoxic than at Helkijn. A strong correlation between Fe and Co was found at Helkijn as well as at Warneton. The metal gradients at the water/sediment interface were calculated from the high resolution profiles and the conventional, low resolution profiles. Significant differences were observed. [Copyright &y& Elsevier]

Abstract: The surface modification of Li powder was attempted in order to enhance the electrochemical properties of the electrodes used in rechargeable batteries. To create a “native” LiF film on Li powder, Li powder was manufactured using a droplet emulsion technique (DET) process by introducing fluoride as a surfactant. The surface modification of the Li powder was confirmed by means of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX). Two-electrode cells (Li symmetric cells) were prepared for the purpose of impedance analysis and scanning electron microscope (SEM) observation. From the impedance analysis, the modified surface film was found to have a smaller resistance than the bare Li powder surface. SEM images showed that dendritic formations were more highly suppressed when the compacted Li powder and surface-modified Li powder electrodes were used than when the Li foil electrode was used. Moreover, the surface-modified Li powder electrodes suppressed dendritic formations more effectively than regular Li powder electrodes. [Copyright &y& Elsevier]

: ObjectivesThe purpose of this study was to assess the long-term value of pharmacologic stress echocardiography with either dipyridamole or dobutamine (DET) for prediction of cardiac death in patients with proven or suspected coronary artery disease (CAD).: BackgroundStress echocardiography is an established, cost-effective technique for the detection of CAD.: MethodsFrom the Echo Persantine International Cooperative–Echo Dobutamine International Cooperative data bank, 7,333 patients (5,452 males; 59 ± 10 years) underwent pharmacologic stress echocardiography with either high-dose dipyridamole (0.84 mg/kg over 10 min) (n = 4,984) or high-dose dobutamine (up to 40 μg/kg/3 min) (n = 2,349) for diagnostic purposes. Patients were followed up for a mean of 2.6 years (range 1 to 206 months).: ResultsThe DET was positive for myocardial ischemia in 2,854 (35%) patients and negative in 4,479 (61%) patients. During the follow-up there were 161 cardiac deaths (sudden death and fatal myocardial infarction) (2.1% of the total population). Kaplan-Meier survival estimates showed a significantly better outcome for those patients with a negative pharmacologic stress echocardiography test compared with those with a positive test (92 vs. 71.2%, p = 0.0000).: ConclusionsPharmacologic stress echocardiography with either dipyridamole or dobutamine is effective in predicting cardiac death during a long-term follow-up. A negative stress echocardiography test result is related to a favorable outcome. [Copyright &y& Elsevier]

Acidic mining lakes (pH<3) represent a big environmental issue in former lignite mining areas. The acidity status of such lakes is mainly governed by the fluxes and the turnover of iron. No data are known about the iron cycling at the sediment–water boundary in the littoral of acidic mining lakes. In order to study the microstratification of iron cycling at the sediment–water interface, existing microsensor and gel-probe techniques (diffusive equilibration in thin-films, DET) were adapted to the extreme conditions of a mining lake. Microprofiles of O2 and pH measured in situ by a profiler were compared with profiles measured in sediment cores immediately after sampling. The results indicate that microprofile measurements in cores from the littoral underestimate oxygen penetration into the sediment. Both advective pore water movement and pore water displacement during coring did influence concentration profiles. Measurement of sulfate and both ferric and ferrous iron was possible on a millimetre scale using DET. Based on different test measurements, a protocol for the application of gel probes for the analysis of iron and sulfate in acidic mining lakes was developed.The combination of microsensor and DET data allowed the characterisation and localisation of iron turnover on a millimetre scale. As an example, results from the littoral of Mining Lake 111 (Lusatia, Germany) are presented. Pore water gradients indicated a flux of ferric iron and sulfate from the water into the sediment. There were no indications of iron reduction or oxidation in the uppermost 6 cm of the sediment. A relative comparison of the fluxes revealed that the iron and sulfur fluxes were probably driven by the formation of jarosite directly in the sediment. [Copyright &y& Elsevier]

An in situ methodology combining DET and DGT probes was applied in a wetland soil, downstream of a former uranium mine (Rophin), to evaluate metal resupply by calculating the R ratio (R = [U] DGT /[U] pore water) from a high resolution and large (75 cm) soil profile. Our study confirms its applicability in soil layers with varying properties; only soil layers with low water content or coarse texture appear to be limiting factors. For soil profiles, DET provides new insights of the distribution of Uranium as soluble species (free ions, small inorganic complexes, ...) along the pore water profile, whereas DGT highlights the presence of other "DGT labile" species. The pairing of DET and DGT, plus the calculation of the R, highlights two U behaviors in combining results from red-ox sensitive elements (Mn, Fe). First, in the organic topsoil layer, an increase in [U] DET and [U] DGT at 3–4 cm reflects the desorption of U probably trapped onto Fe- and Mn-oxohydroxides in a DGT-labile form. However, the resupply from soil to pore water is close to a diffusion only case (R < 0.2) meaning that a portion of U is certainly tightly bound by OM in soil as non-labile species. Second, a peak in [U] DGT perfectly corresponding to the former mine deposit layer signifies the presence of U under DGT-labile species. Moreover, a maximum R value of 0.87 demonstrates the near complete resupply of U from a labile fraction in this layer, as opposed to other elements like Pb. • A combination of 5 DET and DGT was deployed in the Rophin wetland soil layers. • The metal resupply was assessed by calculating the R ratio (R = [U] DGT /[U] pore water). • A R value of 0.87 demonstrates the resupply of U from a mine deposit layer. • Up to 1750 mg kg−1 U are retained in wetland topsoil by organic complexation. • A change in red-ox sensitive elements occurs below the soil-water interface. [ABSTRACT FROM AUTHOR]

Growing worldwide concern over uranium contamination of groundwater resources has placed an emphasis on understanding uranium transport dynamics and potential toxicity in groundwater-surface water systems. In this study, we utilized novel in-situ sampling methods to establish the location and magnitude of contaminated groundwater entry into a receiving surface water environment, and to investigate the speciation and potential bioavailability of uranium in groundwater and surface water. Streambed temperature mapping successfully identified the location of groundwater entry to the Little Wind River, downgradient from the former Riverton uranium mill site, Wyoming, USA. Diffusive equilibrium in thin-film (DET) samplers further constrained the groundwater plume and established sediment pore water solute concentrations and patterns. In this system, evidence is presented for attenuation of uranium-rich groundwater in the shallow sediments where surface water and groundwater interaction occurs. Surface water grab and DET sampling successfully detected an increase in river uranium concentrations where the groundwater plume enters the Little Wind River; however, concentrations remained below environmental guideline levels. Uranium speciation was investigated using diffusive gradients in thin-film (DGT) samplers and geochemical speciation modelling. Together, these investigations indicate uranium may have limited bioavailability to organisms in the Little Wind River and, possibly, in other similar sites in the western U.S.A. This could be due to ion competition effects or the presence of non- or partially labile uranium complexes. Development of methods to establish the location of contaminated (uranium) groundwater entry to surface water environments, and the potential effects on ecosystems, is crucial to develop both site-specific and general conceptual models of uranium behavior and potential toxicity in affected ground and surface water environments. Unlabelled Image • Growing concern over contamination of groundwater resources with uranium. • What is the impact of uranium in groundwater-surface water systems? • In-situ sampling methodology including streambed temperature survey, DET and DGT. • Uranium attenuated in riverbed sediments but impact detected in surface waters. • Uranium bioavailability limited due to competing ions and complexes. [ABSTRACT FROM AUTHOR]

Smart grids studies focus on improving their reliability and reducing the cost of energy, particularly when they are operated offshore. Smart grids Supervisory Control and Data Acquisition (SCADA) systems contain alarm signals providing significant important information. Pattern recognition embodies a set of promising techniques for intelligently processing smart grid SCADA alarms. This paper presents the feasibility study of SCADA alarm processing and description of the functional and operational control-command applications method SA-RT (Structured Analysis Real Time) is presented. The purpose of this article is to propose a general methodology of analysis and supervision of control-command applications based on the SA-RT method as well as the SCADA system [ABSTRACT FROM AUTHOR]

Background: Direct enteral feeding tube (DET) placement for dysphagia after stroke is associated with poor outcomes. However, the relationship between timing of DET placement and poststroke mortality and disability is unknown. We sought to determine the risk of mortality and severe disability in patients who receive DET at different times after stroke.Methods: We used the Ontario Stroke Registry and linked administrative databases to identify patients with acute ischemic stroke or intracerebral hemorrhage between 2003 and 2013 who received DET (gastrostomy or jejunostomy) during their hospital admission. We grouped patients by week of DET placement and evaluated mortality at 30 days and 6 months after DET insertion, and disability at discharge. We used Cox proportional hazard models and multiple logistic regression to determine the association between time from admission to DET placement and outcomes, adjusting for patient and hospital factors.Results: In the study sample of 1367 patients, the median time from admission to DET placement was 17 days. After adjustment, each week of delay to DET placement was associated with lower mortality at 30 days (adjusted hazard ratio [aHR] .88, 95% confidence interval [CI] .79-.98), but not at 6 months (aHR .98, 95% CI .91- 1.05), and a higher likelihood of severe disability at discharge (adjusted odds ratio 1.35, 95% CI 1.13- 1.60).Conclusions: Later DET placement after stroke was associated with lower 30-day mortality but higher severe disability at discharge. Further research is needed to understand the reasons for these observations and to optimize patient selection and timing of DET. [ABSTRACT FROM AUTHOR]

Graphical abstract The quantum size effect of CdS QD, hot electron transfer of Au and suitable band alignment are mainly responsible for enhanced photocatalytic activity of TiO 2 /Au/CdS QDs nanocomposite Highlights • TiO 2 nanowire is synthesized and modified with Au nanoparticles and CdS QDs. • UV-Vis DRS confirms the plasmonic direct hot electron transfer (DET) mechanism. • Longer life time of electrons is found 97.4 μs from Bode phase plot for TiO 2 /1%Au/3%CdS QDs nanocomposite. • Photocatalytic conversion of 2-NP and 4-NP to respective amino phenols shows a conversion rate of 99% and 67.68% respectively. • Degradation rate of 99.4% is observed for ciprofloxacin. Abstract Solar light harvesting science is ascertained to be the topmost effective green technique in alleviating environmental pollutants. In this respect, we report a visible light active TiO 2 /Au/CdS QDs nanocomposite which manifested upgraded photocatalytic activity towards the transformation of 2-nitrophenol, 4-nitrophenol, and degradation of ciprofloxacin. Here, TiO 2 nanowire is synthesized by a molten flux method with high product yield and crystallinity with organized dimensions. Au nanoparticles are successfully integrated in between TiO 2 -CdS composite by Reverse Turkevich method. The prepared composites are meticulously characterized by different physical and optoelectronic techniques to inspect the crystal structure, phase purity, optical properties, nanostructured morphology and electrochemical properties. The plasmonic direct hot electron transfer (DET) mechanism is confirmed from UV-Vis DRS spectra. The prepared composite produces 2.98 mA/cm2 of current density under light irradiation. A Longer lifetime of electrons is found from Bode phase plot i.e. 97.4 μs for TiO 2 /1%Au/3%CdS QDs owing to the integrative cooperation effect of high aspect ratio of TiO 2 nanowire, quantum size effect of CdS and the direct hot electron transfer by Au nanoparticle. [ABSTRACT FROM AUTHOR]