Abstract: We present an approximate description of the giant vortex state in a thin mesoscopic superconducting disk within the phenomenological Ginzburg-Landau approach. Analytical asymptotic expressions for the energies of the states with fixed vorticity are obtained when a small magnetic flux is accumulated in the disk. The spectrum of the lowest Landau levels of such a disk is also discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

Abstract: A polycrystalline sample of Ba3Fe2TeO9 having the 6H perovskite structure has been prepared in a solid-state reaction and studied by a combination of electron microscopy, Mossbauer spectroscopy, magnetometry, X-ray diffraction and neutron diffraction. Partial ordering of Fe3+ and Te6+ cations occurs over the six-coordinate sites; the corner-sharing octahedra are predominantly occupied by the former and the face-sharing octahedra by a 1:1 mixture of the two. On cooling through the temperature range 18 < T/K < 295 an increasing number of spins join an antiferromagnetic backbone running through the structure while the remainder show complex relaxation effects. At 3 K an antiferromagnetic phase and a spin glass coexist.

Abstract: Both landfill taxes and Enhanced Waste Management (EWM) practices can mitigate the scarcity issue of landfill capacity by respectively reducing landfilled waste volumes and valorising future waste streams. However, high landfill taxes might erode incentives for EWM, even though EWM creates value by valorising waste. Concentrating on Flanders (Belgium), the paper applies dynamic optimisation modelling techniques to analyse how landfill taxation and EWM can reinforce each other and how taxation schemes can be adjusted in order to foster sustainable and welfare maximising ways of processing future waste streams. Based on the Flemish simulation results, insights are offered that are generally applicable in international waste and resource management policy. As shown, the optimal Flemish landfill tax that optimises welfare in the no EWM scenario is higher than the one in the EWM scenario (93 against (sic)50/ton). This difference should create incentives for applying EWM and is driven by the positive external effects that are generated by EWM practices. In Flanders, as the current landfill tax is slightly lower than these optimal levels, the choice that can be made is to further increase taxation levels or show complete commitment to EWM. A first generally applicable insight that was found points to the fact that it is not necessarily the case that the higher the landfill tax, the more effective waste management improvements can be realised. Other insights are about providing sufficient incentives for applying EMW practices and formulating appropriate pleas in support of technological development. By these insights, this paper should provide relevant information that can assist in triggering the transition towards a resource efficient, circular economy in Europe. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract: Titanium dioxide (TiO2) is a popular material as host matrix for enzymes. We now evidence that TiO2 can accumulate and retain reactive oxygen species after treatment by hydrogen peroxide (H2O2) and support redox cycling of a phenolic analyte between horseradish peroxidase (HRP) and an electrode. The proposed detection scheme is identical to that of second generation biosensors, but the measuring solution requires no dissolved H2O2. This significantly simplifies the analysis and overcomes issues related to H2O2 being present (or generated) in the solution. The modified electrodes showed rapid stabilization of the baseline, a low noise level, fast realization of a steady-state current response, and, in addition, improved sensitivity and limit of detection compared to the conventional approach, i.e. in the presence of H2O2 in the measuring solution. Hydroquinone, 4-aminophenol, and other phenolic compounds were successfully detected at sub-μM concentrations. Particularly, a linear response in the concentration range between 0.025 and 2 μM and LOD of 24 nM was demonstrated for 4-aminophenol. The proposed sensor design goes beyond the traditional concept with three sensors generations offering a new possibility for the development of enzymatic sensors based on peroxidases and the formation of ROS on titania after treatment with H2O2.

Abstract: High-rate activated sludge (HRAS) is an essential cornerstone of the pursuit towards energy positive sewage treatment through maximizing capture of organics. The capture efficiency heavily relies on the degree of solid separation achieved in the clarifiers. Limitations in the floc formation process commonly emerge in HRAS systems, with detrimental consequences for the capture of organics. This study pinpointed and overcame floc formation limitations present in full-scale HRAS reactors. Orthokinetic flocculation tests were performed with varying shear, sludge concentration, and coagulant or flocculant addition. These were analyzed with traditional and novel settling parameters and extracellular polymeric substances (EPS) measurements. HRAS was limited by insufficient collision efficiency and occurred because the solids retention time (SRT) was short and colloid loading was high. The limitation was predominantly caused by impaired flocculation rather than coagulation. In addition, the collision efficiency limitation was driven by EPS composition (low protein over polysaccharide ratio) instead of total EPS amount. Collision efficiency limitation was successfully overcome by bio-augmenting sludge from a biological nutrient removal reactor operating at long SRT which did not show any floc formation limitations. However, this action brought up a floc strength limitation. The latter was not correlated with EPS composition, but rather EPS amount and hindered settling parameters, which determined floc morphology. With this, an analysis toolkit was proposed that will enable design engineers and operators to tackle activated solid separation challenges found in HRAS systems and maximize the recovery potential of the process. (C) 2018 Elsevier Ltd. All rights reserved.