Abstract: Sustainable development is driving a rapid focus shift in the wastewater and organic waste treatment sectors, from a “removal and disposal” approach towards the recovery and reuse of water, energy and materials (e.g. carbon or nutrients). Purple phototrophic bacteria (PPB) are receiving increasing attention due to their capability of growing photoheterotrophically under anaerobic conditions. Using light as energy source, PPB can simultaneously assimilate carbon and nutrients at high efficiencies (with biomass yields close to unity (1 g CODbiomass·g CODremoved−1)), facilitating the maximum recovery of these resources as different value-added products. The effective use of infrared light enables selective PPB enrichment in non-sterile conditions, without competition with other phototrophs such as microalgae if ultraviolet-visible wavelengths are filtered. This review reunites results systematically gathered from over 177 scientific articles, aiming at producing generalized conclusions. The most critical aspects of PPB-based production and valorisation processes are addressed, including: (i) the identification of the main challenges and potentials of different growth strategies, (ii) a critical analysis of the production of value-added compounds, (iii) a comparison of the different value-added products, (iv) insights into the general challenges and opportunities and (v) recommendations for future research and development towards practical implementation. To date, most of the work has not been executed under real-life conditions, relevant for full-scale application. With the savings in wastewater discharge due to removal of organics, nitrogen and phosphorus as an important economic driver, priorities must go to using PPB-enriched cultures and real waste matrices. The costs associated with artificial illumination, followed by centrifugal harvesting/dewatering and drying, are estimated to be 1.9, 0.3–2.2 and 0.1–0.3 $·kgdry biomass−1. At present, these costs are likely to exceed revenues. Future research efforts must be carried out outdoors, using sunlight as energy source. The growth of bulk biomass on relatively clean wastewater streams (e.g. from food processing) and its utilization as a protein-rich feed (e.g. to replace fishmeal, 1.5–2.0 $·kg−1) appears as a promising valorisation route.

Abstract: This work investigates the compatibility of Zr2AlC MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local Zr2AlC/LBE interaction. The ceramics were exposed to oxygen-poor (C-O <= 2.2 x 10(-10) mass%), static liquid LBE at 500 degrees C for 1000 h. A new Zr-2(Al,Bi,Pb)C MAX phase solid solution formed in-situ in the LBE-affected Zr2AlC grains. Out-of-plane ordering was favorable in the new solid solution, whereby A-layers with high and low-Bi/Pb contents alternated in the crystal structure, in agreement with first-principles calculations. Bulk Zr-2(Al,Bi,Pb)C was synthesized by reactive hot pressing to study the crystal structure of the solid solution by neutron diffraction.

Abstract: Global environmental problems have urged the need for developing sustainable technologies. However, new technologies that enter the market have often higher economic costs and potentially higher environmental impacts than conventional technologies. This can be explained by learning effects: a production process that is performed for the first time runs less smooth than a production process that has been in operation for years. To obtain a fair estimation of the potential of a new technology, learning effects need to be included. A review on the current literature on learning effects was conducted in order to provide guidelines on how to include learning effects in prospective technology assessment. Based on the results of this review, five recommendations have been formulated and an integration of learning effects in the structure of prospective technology assessment has been proposed. These five recommendations include the combined use of learning effects on the component level and on the end product level; the combined use of learning effects on the technical, economic and environmental level; the combined use of extrapolated values and expert estimates; the combined use of learning-by-doing and learning-by-searching effects and; a tier-based method, including quality criteria, to calculate the learning effect. These five complementary strategies could lead to a clearer perspective on the environmental impact and cost structure of the new technology and a fairer comparison base with conventional technologies, potentially resulting in a faster adoption and a shorter time-to-market for sustainable technologies.

Abstract: The demand of a full solid-state cooling technology based on magnetocaloric and thermoelectric effects has led to a growing interest in screening candidate materials with high-efficiency cooling performance, which also stimulates the exploration of magnetocaloric/thermoelectric hybrid cooling materials. A series of Gd/Bi0.5Sb1.5Te3 composites was fabricated in order to develop the hybrid cooling technology. The chemical composition, phase structure and diffusion kinetics across the reaction layers in Gd/Bi0.5Sb1.5Te3 composites were analyzed at different reaction temperatures. Micro-area elemental analysis indicates that the formation of interfacial phases is dominated by the diffusion of Gd and Te while the diffusion of Bi and Sb is impeded. The interfacial phases, including GdTe2, GdTe3, and intermediate phases GdTex, are identified by atomic-resolution electron microscopy. The concentration modulation of Gd and Te is adapted by altering the stacking of the Te square-net sheets and the corrugated GdTe sheets. Boltzmann-Marano analysis was applied to reveal the diffusion kinetics of Gd and Te in the interfacial layers. The diffusion coefficients of Te in GdTe2 and GdTe3 are much higher than that of Gd while in GdTe the situation is reversed. This study provides a clear picture to understand the interfacial phase structures down to an atomic scale as well as the interfacial diffusion kinetics in Gd/Bi0.5Sb1.5Te3 hybrid cooling materials.

Abstract: The three-dimensional (3D) nanostructure of Ni4Ti3 precipitates in a porous Ni50.8Ti49.2 alloy has been re-constructed by “Slice-and-View” in a Focused Ion Beam/Scanning Electron Microscope (FIB/SEM). The 3D configuration of these precipitates forming a network structure in the B2 austenite matrix has been characterized via 3D visualization and quantitative analysis including volume fraction, skeleton, degree of anisotropy and local thickness. It is found that dense Ni4Ti3 precipitates occupy 54% of the volume in the B2 austenite matrix. Parallel Ni4Ti3 precipitates grow alongside the surface of a micro-pore, yielding an asymmetric structure, while nano voids do not seem to affect the growth of Ni4Ti3 precipitates. The small average local thickness of the precipitates around 60 nm allows their coherency with the matrix, and further induces the R-phase transformation in the matrix. On the other hand, the B2 matrix exhibits a winding and narrow structure with a skeleton of 18.20 mm and a thickness similar to the precipitates. This discontinuous matrix segmented by the Ni4Ti3 network and pores is responsible for the gradual transformation by stalling the martensite propagation.

Abstract: Winter peaks in Belgian electricity demand are significantly higher than the summer peaks, creating a greater potential for imbalances between demand and supply. This potential is exacerbated because of the risk of outages in its ageing nuclear power plants, which are being phased out in the medium term. This paper conducts a choice experiment to investigate the acceptability of a load control-based demand response program in the winter months. It surveys 186 respondents on their willingness to accept limits on the use of home appliances in return for a compensation. Results indicate that respondents are most affected by the days of the week that their appliance usage would be curtailed, and by the compensation they would receive. The willingness to enroll in a program increases with age, environmental consciousness, home ownership, and lower privacy concerns. The analysis predicts that 95% of the sample surveyed could enroll in a daily load control program for a compen- sation of €41 per household per year. Thus while an initial rollout among older and more pro-environment homeowners could be successful, a wider implementation would require an explanation of its environmental and financial benefits to the population, and a greater consideration of their data privacy concerns.

Abstract: The growing demand for tools to generate chemical information in decentralized settings is creating a vast range of opportunities for potentiometric sensors, since their combination of robustness, simplicity of operation and cost can hardly be rivalled by any other technique. In previous works, we have shown that the mixed potential of a Pt electrode can be controlled with analytical purposes using a coating of Nafion, thus providing a way to develop a potentiometric biosensor for glucose. Unfortunately, the linear range of this device did not match the relevant clinical range for glucose in blood. This work presents a novel strategy to control the mixed potential that allows the development of a potentiometric biosensor for the direct detection of glucose in whole, undiluted blood without any sample pretreatment. By changing the ionomer, the analytical response can be tuned, shifting the linear range while keeping the sensitivity. Aquivion, a polyelectrolyte from the same family as Nafion, is used to stabilize the mixed potential of a platinized paper-based electrode, to entrap the enzyme and to reduce the interference from negatively charged species. Factors affecting the generation of the signal and the principle of detection are discussed. Optimization of the biosensor composition was achieved with particular focus on the characterization of the linear range and sensitivity. The accurate measurement of blood sugar levels in a single drop of whole blood with excellent recovery is presented.

Abstract: In electron microscopy, the maximum a posteriori (MAP) probability rule has been introduced as a tool to determine the most probable atomic structure from high-resolution annular dark-field (ADF) scanning transmission electron microscopy (STEM) images exhibiting low contrast-to-noise ratio (CNR). Besides ADF imaging, STEM can also be applied in the annular bright-field (ABF) regime. The ABF STEM mode allows to directly visualize light-element atomic columns in the presence of heavy columns. Typically, light-element nanomaterials are sensitive to the electron beam, limiting the incoming electron dose in order to avoid beam damage and leading to images exhibiting low CNR. Therefore, it is of interest to apply the MAP probability rule not only to ADF STEM images, but to ABF STEM images as well. In this work, the methodology of the MAP rule, which combines statistical parameter estimation theory and model-order selection, is extended to be applied to simultaneously acquired ABF and ADF STEM images. For this, an extension of the commonly used parametric models in STEM is proposed. Hereby, the effect of specimen tilt has been taken into account, since small tilts from the crystal zone axis affect, especially, ABF STEM intensities. Using simulations as well as experimental data, it is shown that the proposed methodology can be successfully used to detect light elements in the presence of heavy elements.

Abstract: Lattice strain measurement of nanoscale semiconductor devices is crucial for the semiconductor industry as strain substantially improves the electrical performance of transistors. High resolution scanning transmission electron microscopy (HR-STEM) imaging is an excellent tool that provides spatial resolution at the atomic scale and strain information by applying Geometric Phase Analysis or image fitting procedures. However, HR-STEM images regularly suffer from scanning distortions and sample drift during image acquisition. In this paper, we propose a new scanning strategy that drastically reduces artefacts due to drift and scanning distortion, along with extending the field of view. It consists of the acquisition of a series of independent small subimages containing an atomic resolution image of the local lattice. All subimages are then analysed individually for strain by fitting a nonlinear model to the lattice images. The method allows flexible tuning of spatial resolution and the field of view within the limits of the dynamic range of the scan engine while maintaining atomic resolution sampling within the subimages. The obtained experimental strain maps are quantitatively benchmarked against the Bessel diffraction technique. We demonstrate that the proposed scanning strategy approaches the performance of the diffraction technique while having the advantage that it does not require specialized diffraction cameras.

Abstract: By using density functional theory-based first-principles calculations, we investigate the structural, electronic, optical, and transport properties of pristine single-layer BC6N. Under different external actions and functionalization. Increasing the thickness of the structure results in a decrease of the band gap. Applying a perpendicular electric field decreases the band gap and a semiconductor-to-topological insulator transition is revealed. Uniaxial and biaxial strains of +8% result in a semiconductor-to-metal transition. Nanoribbons of BC6N having zigzag edge with even (odd) values of widths, become metal (semiconductor), while the armchair edge nanoribbons exhibit robust semiconducting behavior. In addition, we systematically investigate the effect of surface adatom and molecule, substitutional impurity and defect engineering on the electronic properties of single-layer BC6N and found transitions from metal to half-metal, to ferromagnetic metal, to dilute magnetic semiconductor, and even to spin-glass semiconductor. Furthermore we found that, topological defects including vacancies and Stone–Wales type, induce magnetism in single-layer BC6N.

Abstract: Human activities related to urbanization and industrialization have established a vast territory of urban soil worldwide. On traditional soil maps, urban and industrial areas usually appear as blind spots as they were beyond the interest of national soil survey campaigns. Furthermore, these soil maps are likely already outdated with respect to urban soil due to rapid urban expansion in recent decades. This research aims to evaluate the use of land cover data to estimate the urban soil information gap considering the highly urbanized region of Flanders, Belgium, as a case study. The current extent and spatial distribution of anthropogenic urban soil (1) was estimated through reclassification of recently acquired (2012) exhaustive land cover data, discriminating three qualitative likelihood levels (high-intermediate-low) of anthropogenic influence by urbanization, and (2) compared with its occurrence as represented by the 'Technosols/Not Surveyed area' in the legacy soil map of Belgium, as this map unit best matches with the likelihood for anthropogenic urban soil at the time of the National Soil Survey conducted between end 1940s and mid 1970s. The proposed reclassification of the land cover map resulted in 16.3% and 16.7% of Flanders' total area that corresponds with a high and intermediate likelihood for anthropogenic urban soil, which highlights the underestimation of the anthropogenic urban soil extent as represented by the 'Technosol/Not Surveyed' unit in the legacy soil map (only 13.7%). Moreover, a more realistic spatial pattern of anthropogenic urban soil occurrence was obtained, providing an improved basis for urban soil spatial analysis studies. The produced anthropogenic urban soil likelihood map therefore presents a useful supporting tool for coordinating future soil surveys in urban environments.

Abstract: The discovery of a two-dimensional electron system (2DES) at the interfaces of perovskite oxides such as LaAlO3 and SrTiO3 has motivated enormous efforts in engineering interfacial functionalities with this type of oxide heterostructures. However, the fundamental origins of the 2DES are still not understood, e.g., the microscopic mechanisms of coexisting interface conductivity and magnetism. Here we report a comprehensive spectroscopic investigation on the depth profile of 2DES-relevant Ti 3d interface carriers using depthand element-specific techniques like standing-wave excited photoemission and resonant inelastic scattering. We found that one type of Ti 3d interface carriers, which give rise to the 2DES are located within three unit cells from the n-type interface in the SrTiO3 layer. Unexpectedly, another type of interface carriers, which are polarity-induced Ti-on-Al antisite defects, reside in the first three unit cells of the opposing LaAlO3 layer (similar to 10 angstrom). Our findings provide a microscopic picture of how the localized and mobile Ti 3d interface carriers distribute across the interface and suggest that the 2DES and 2D magnetism at the LaAlO3/SrTiO3 interface have disparate explanations as originating from different types of interface carriers.

Abstract: Anammox, the oxidation of ammonium with nitrite, is a key microbial process in the nitrogen cycle. Under mesophilic conditions (below 40 °C), it is widely implemented to remove nitrogen from wastewaters lacking organic carbon. Despite evidence of the presence of anammox bacteria in high-temperature environments, reports on the cultivation of thermophilic anammox bacteria are limited to a short-term experiment of 2 weeks. This study showcases the adaptation of a mesophilic inoculum to thermophilic conditions, and its characterization. First, an attached growth technology was chosen to obtain the process. In an anoxic fixed-bed biofilm bioreactor (FBBR), a slow linear temperature increase from 38 to over 48 °C (0.05–0.07 °C d−1) was imposed to the community over 220 days, after which the reactor was operated at 48 °C for over 200 days. Maximum total nitrogen removal rates reached up to 0.62 g N L−1 d−1. Given this promising performance, a suspended growth system was tested. The obtained enrichment culture served as inoculum for membrane bioreactors (MBR) operated at 50 °C, reaching a maximum total nitrogen removal rate of 1.7 g N L−1 d−1 after 35 days. The biomass in the MBR had a maximum specific anammox activity of 1.1 ± 0.1 g NH4+-N g−1 VSS d−1, and the growth rate was estimated at 0.075–0.19 d−1. The thermophilic cultures displayed nitrogen stoichiometry ratios typical for mesophilic anammox: 0.93–1.42 g NO2--Nremoved g−1 NH4+-Nremoved and 0.16–0.35 g NO3--Nproduced g−1 NH4+-Nremoved. Amplicon and Sanger sequencing of the 16S rRNA genes revealed a disappearance of the original “Ca. Brocadia” and “Ca. Jettenia” taxa, yielding Planctomycetes members with only 94–95% similarity to “Ca. Brocadia anammoxidans” and “Ca. B. caroliniensis”, accounting for 45% of the bacterial FBBR community. The long-term operation of thermophilic anammox reactors and snapshot views on the nitrogen stoichiometry, kinetics and microbial community open up the development path of thermophilic partial nitritation/anammox. A first economic assessment highlighted that treatment of sludge reject water from thermophilic anaerobic digestion of sewage sludge may become attractive.

Abstract: Resource recovery from source-separated urine can shorten nutrient cycles on Earth and is essential in regenerative life support systems for deep-space exploration. In this study, a robust two-stage, energy-efficient, gravity-independent urine treatment system was developed to transform fresh real human urine into a stable nutrient solution. In the first stage, up to 85% of the COD was removed in a microbial electrolysis cell (MEC), converting part of the energy in organic compounds (27-46%) into hydrogen gas and enabling full nitrogen recovery by preventing nitrogen losses through denitrification in the second stage. Besides COD removal, all urea was hydrolysed in the MEC, resulting in a stream rich in ammoniacal nitrogen and alkalinity, and low in COD. This stream was fed into a membrane-aerated biofilm reactor (MABR) in order to convert the volatile and toxic ammoniacal nitrogen to non-volatile nitrate by nitrification. Bio-electrochemical pre-treatment allowed to recover all nitrogen as nitrate in the MABR at a bulk-phase dissolved oxygen level below 0.1 mg O2 L-1. In contrast, feeding the MABR directly with raw urine (omitting the first stage), at the same nitrogen loading rate, resulted in nitrogen loss (18%) due to denitrification. The MEC and MABR were characterised by very distinct and diverse microbial communities. While (strictly) anaerobic genera, such as Geobacter (electroactive bacteria), Thiopseudomonas, a Lentimicrobiaceae member, Alcaligenes and Proteiniphilum prevailed in the MEC, the MABR was dominated by aerobic genera, including Nitrosomonas (a known ammonium oxidiser), Moheibacter and Gordonia. The two-stage approach yielded a stable nitrate-rich, COD-low nutrient solution, suitable for plant and microalgae cultivation.

Abstract: In this work, the effects of N-doping into the Co-doped single vacancy (Co-SV-G) and di-vacancy graphene flake (Co-dV-G) are investigated and compared toward direct oxidation of methane to methanol (DOMM) employing two different oxidants (N2O and O-2) using density functional theory (DFT) calculation. We found that DOMM on CoN3-G utilizing the N2O molecule as oxygen-donor proceeds via a two-step reaction with low activation energies. In addition, we found that although CoN3-G might be a good catalyst for methane conversion, it can also catalyze the oxidation of methanol to CO2 and H2O due to the required low activation barriers. Moreover, the adsorption behaviors of CHx (x = 0-4) species and dehydrogenation of CHx (x = 1-4) species on CoN3-G are investigated. We concluded that CoN3-G can be used as an efficient catalyst for DOMM and N-2O reduction at ambient conditions which may serve as a guide for fabricating effective C/N catalysts in energy-related devices.