“Model-based assessment of estrogen removal by nitrifying activated sludge”. Peng L, Dai X, Liu Y, Sun J, Song S, Ni B-J, Chemosphere 197, 430 (2018). http://doi.org/10.1016/J.CHEMOSPHERE.2018.01.035
Abstract: Complete removal of estrogens such as estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2) in wastewater treatment is essential since their release and accumulation in natural water bodies are giving rise to environment and health issues. To improve our understanding towards the estrogen bioremediation process, a mathematical model was proposed for describing estrogen removal by nitrifying activated sludge. Four pathways were involved in the developed model: i) biosorption by activated sludge flocs; ii) cometabolic biodegradation linked to ammonia oxidizing bacteria (AOB) growth; iii) non growth biodegradation by AOB; and iv) biodegradation by heterotrophic bacteria (HB). The degradation kinetics was implemented into activated sludge model (ASM) framework with consideration of interactions between substrate update and microorganism growth as well as endogenous respiration. The model was calibrated and validated by fitting model predictions against two sets of batch experimental data under different conditions. The model could satisfactorily capture all the dynamics of nitrogen, organic matters (COD), and estrogens. Modeling results suggest that for El, E2 and EE2, AOB-linked biodegradation is dominant over biodegradation by HB at all investigated COD dosing levels. However, for E3, the increase of COD dosage triggers a shift of dominant pathway from AOB biodegradation to HB biodegradation. Adsorption becomes the main contributor to estrogen removal at high biomass concentrations. (C) 2018 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CHEMOSPHERE.2018.01.035
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“Modeling electron competition among nitrogen oxides reduction and N2Oaccumulation in hydrogenotrophic denitrification”. Liu Y, Ngo HH, Guo W, Peng L, Chen X, Wang D, Pan Y, Ni B-J, Biotechnology and bioengineering 115, 978 (2018). http://doi.org/10.1002/BIT.26512
Abstract: Hydrogenotrophic denitrification is a novel and sustainable process for nitrogen removal, which utilizes hydrogen as electron donor, and carbon dioxide as carbon source. Recent studies have shown that nitrous oxide (N2O), a highly undesirable intermediate and potent greenhouse gas, can accumulate during this process. In this work, a new mathematical model is developed to describe nitrogen oxides dynamics, especially N2O, during hydrogenotrophic denitrification for the first time. The model describes electron competition among the four steps of hydrogenotrophic denitrification through decoupling hydrogen oxidation and nitrogen reduction processes using electron carriers, in contrast to the existing models that couple these two processes and also do not consider N2O accumulation. The developed model satisfactorily describes experimental data on nitrogen oxides dynamics obtained from two independent hydrogenotrophic denitrifying cultures under various hydrogen and nitrogen oxides supplying conditions, suggesting the validity and applicability of the model. The results indicated that N2O accumulation would not be intensified under hydrogen limiting conditions, due to the higher electron competition capacity of N2O reduction in comparison to nitrate and nitrite reduction during hydrogenotrophic denitrification. The model is expected to enhance our understanding of the process during hydrogenotrophic denitrification and the ability to predict N2O accumulation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1002/BIT.26512
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“Modeling of electroporation induced by pulsed electric fields in irregularly shaped cells”. Mescia L, Chiapperino MA, Bia P, Gielis J, Caratelli D, IEEE transactions on biomedical engineering 65, 414 (2018). http://doi.org/10.1109/TBME.2017.2771943
Abstract: During the past decades, the poration of cell membrane induced by pulsed electric fields has been widely investigated. Since the basic mechanisms of this process have not yet been fully clarified, many research activities are focused on the development of suitable theoretical and numerical models. To this end, a nonlinear, nonlocal, dispersive, and space-time numerical algorithm has been developed and adopted to evaluate the transmembrane voltage and pore density along the perimeter of realistic irregularly shaped cells. The presented model is based on the Maxwell's equations and the asymptotic Smoluchowski's equation describing the pore dynamics. The dielectric dispersion of the media forming the cell has been modeled by using a general multirelaxation Debye-based formulation. The irregular shape of the cell is described by using the Gielis' superformula. Different test cases pertaining to red blood cells, muscular cells, cell in mitosis phase, and cancer-like cell have been investigated. For each type of cell, the influence of the relevant shape, the dielectric properties, and the external electric pulse characteristics on the electroporation process has been analyzed. The numerical results demonstrate that the proposed model is an efficient numerical tool to study the electroporation problem in arbitrary-shaped cells.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1109/TBME.2017.2771943
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“New generation monitoring devices for heritage guardians to detect multiple events and hazards”. Schalm O, Anaf W, Callier J, Leyva Pernia D, IOP conference series : materials science and engineering 364, Unsp 012056 (2018). http://doi.org/10.1088/1757-899X/364/1/012056
Abstract: Environmental parameters such as temperature, relative humidity, visible light, UV radiation and pollution influence the deterioration rate of heritage items. To judge on the environmental appropriateness for heritage conservation, it is therefore important to monitor the environment. Often, an incomplete set of environmental parameters is measured, or sporadic or time-averaged measurements are performed. As a result, a wide range of undesirable situations and hazards remain unnoticed. This might lead to an underestimation of environmental dangers (i.e., inaccurate judgement) or to inappropriate mitigation measures (i.e., inaccurate decision making). We present an innovative and user-friendly monitoring device that simultaneously and continuously measures (1) environmental parameters and (2) material behavior. An extended combination of off-the-shelf sensors for temperature, relative humidity, air speed, CO2, NO2, O-3 and particulate matter are connected to a multipurpose datalogger. In-house developed sensors for the shrinkage and expansion behavior of wood, as well as sensors for metal corrosion rates are connected to the same datalogger. Such extended monitoring shows the identification of a wider range of undesirable situations, and it facilitates the search for correlations between such situations and the sources that cause them, i.e., the hazards.
Keywords: P1 Proceeding; Engineering sciences. Technology; Art; History; Antwerp Systems and software Modelling (AnSyMo); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.1088/1757-899X/364/1/012056
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“Nitrogen cycle microorganisms can be reactivated after Space exposure”. Lindeboom REF, Ilgrande C, Carvajal-Arroyo JM, Coninx I, Van Hoey O, Roume H, Morozova J, Udert KM, Sas B, Paille C, Lasseur C, Ilyin V, Clauwaert P, Leys N, Vlaeminck SE, Scientific reports 8, 13783 (2018). http://doi.org/10.1038/S41598-018-32055-4
Abstract: Long-term human Space missions depend on regenerative life support systems (RLSS) to produce food, water and oxygen from waste and metabolic products. Microbial biotechnology is efficient for nitrogen conversion, with nitrate or nitrogen gas as desirable products. A prerequisite to bioreactor operation in Space is the feasibility to reactivate cells exposed to microgravity and radiation. In this study, microorganisms capable of essential nitrogen cycle conversions were sent on a 44-days FOTON-M4 flight to Low Earth Orbit (LEO) and exposed to 10(-3)-10(-4) g (gravitational constant) and 687 +/- 170 mu Gy (Gray) d(-1) (20 +/- 4 degrees C), about the double of the radiation prevailing in the International Space Station (ISS). After return to Earth, axenic cultures, defined and reactor communities of ureolytic bacteria, ammonia oxidizing archaea and bacteria, nitrite oxidizing bacteria, denitrifiers and anammox bacteria could all be reactivated. Space exposure generally yielded similar or even higher nitrogen conversion rates as terrestrial preservation at a similar temperature, while terrestrial storage at 4 degrees C mostly resulted in the highest rates. Refrigerated Space exposure is proposed as a strategy to maximize the reactivation potential. For the first time, the combined potential of ureolysis, nitritation, nitratation, denitrification (nitrate reducing activity) and anammox is demonstrated as key enabler for resource recovery in human Space exploration.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1038/S41598-018-32055-4
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“Nontarget biomolecules alter macromolecular changes induced by bactericidal low-temperature plasma”. Privat-Maldonado A, Gorbanev Y, O'Connell D, Vann R, Chechik V, van der Woude MW, IEEE transactions on radiation and plasma medical sciences 2, 121 (2018). http://doi.org/10.1109/TRPMS.2017.2761405
Abstract: Low-temperature plasmas (LTPs) have a proven bactericidal activity governed by the generated reactive oxygen and nitrogen species (RONS) that target microbial cell components. However, RONS also interact with biomolecules in the environment. Here we assess the impact of these interactions upon exposure of liquid suspensions with variable organic content to an atmospheric-pressure dielectric barrier discharge plasma jet. Salmonella enterica serovar Typhimurium viability in the suspension was reduced in the absence [e. g., phosphate buffered saline (PBS)], but not in the presence of (high) organic content [Dulbecco's Modified Eagle's Medium (DMEM), DMEM supplemented with foetal calf serum, and Lysogeny Broth]. The reduced viability of LTP-treated bacteria in PBS correlated to a loss of membrane integrity, whereas double-strand DNA breaks could not be detected in treated single cells. The lack of bactericidal activity in solutions with high organic content correlated with a relative decrease of center dot OH and O-3/O-2(a(1)Delta g)/O, and an increase of H2O2 and NO2- in the plasma-treated solutions. These results indicate that the redox reactions of LTP-generated RONS with nontarget biomolecules resulted in a RONS composition with reduced bactericidal activity. Therefore, the chemical composition of the bacterial environment should be considered in the development of LTP for antimicrobial treatment, and may affect other biomedical applications as well.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1109/TRPMS.2017.2761405
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Stosic D (2018) Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films. 153 p
Abstract: Moore’s Law has driven the electronics industry for the past half century. However, the doubling of transistors about every two years is beginning to break down, owing to fundamental limits that arise as they approach the atomic length. As a result, the search for new pathways for electronics has become crucial. Among potential candidates, the discovery of magnetic textures known as skyrmions has attracted considerable interest and attention in spintronic technology, which relies on both the electron charge and its spin. The unusual topological and particle-like behavior launched skyrmions into the spotlight of scientific research. Topological protected stability, nanoscale size, and low driving currents needed to move them make skyrmions promising candidates for future consumer nanoelectronics. Recent advances in the field have provided all of the basic functions needed for carrying and processing information. In this thesis, we procure to advance the current understanding of skyrmion physics, and explore their potential to replace conventional electronics technology. First, the fundamental properties and lifetimes of racetrack skyrmions at room temperature are investigated. We discover that skyrmions can easily collapse at the boundary in laterally finite systems, and propose ways to improve their stability for constrained geometries. Then, pinning of single skyrmions on atomic defects of distinct origins are studied. We reveal that the preferred pinning positions depend on the skyrmion size and type of defect being considered, and discuss applications where control of skyrmions by defects is of particular interest. Next, we explore other magnetic configurations that can compete with skyrmions when considering new materials, and describe a previously unseen mechanism for collapse of skyrmions into cycloidal spin backgrounds. Finally, switching and interactions between skyrmions with distinct topologies are reported. We find that skyrmions transition to higher or lower topologies by absorbing a unit spin texture. The interactions between skyrmions of different topological charges can be attractive or repulsive, leading to the formation of arranged clusters. We conclude with a numerical library for simulating magnetic skyrmions in various scenarios.
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Photosynthetic oxygenation for urine nitrification”. Muys M, Coppens J, Boon N, Vlaeminck SE, Water science and technology 78, 183 (2018). http://doi.org/10.2166/WST.2018.200
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.2166/WST.2018.200
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“Pinpointing wastewater and process parameters controlling the AOB to NOB activity ratio in sewage treatment plants”. Seuntjens D, Han M, Kerckhof F-M, Boon N, Al-Omari A, Takacs I, Meerburg F, De Mulder C, Wett B, Bott C, Murthy S, Carvajal Arroyo JM, De Clippeleir H, Vlaeminck SE, Water research 138, 37 (2018). http://doi.org/10.1016/J.WATRES.2017.11.044
Abstract: Even though nitrification/denitrification is a robust technology to remove nitrogen from sewage, economic incentives drive its future replacement by shortcut nitrogen removal processes. The latter necessitates high potential activity ratios of ammonia oxidizing to nitrite oxidizing bacteria (rAOB/rNOB). The goal of this study was to identify which wastewater and process parameters can govern this in reality. Two sewage treatment plants (STP) were chosen based on their inverse rAOB/rNOB values (at 20 °C): 0.6 for Blue Plains (BP, Washington DC, US) and 1.6 for Nieuwveer (NV, Breda, NL). Disproportional and dissimilar relationships between AOB or NOB relative abundances and respective activities pointed towards differences in community and growth/activity limiting parameters. The AOB communities showed to be particularly different. Temperature had no discriminatory effect on the nitrifiers' activities, with similar Arrhenius temperature dependences (ΘAOB = 1.10, ΘNOB = 1.061.07). To uncouple the temperature effect from potential limitations like inorganic carbon, phosphorus and nitrogen, an add-on mechanistic methodology based on kinetic modelling was developed. Results suggest that BP's AOB activity was limited by the concentration of inorganic carbon (not by residual N and P), while NOB experienced less limitation from this. For NV, the sludge-specific nitrogen loading rate seemed to be the most prevalent factor limiting AOB and NOB activities. Altogether, this study shows that bottom-up mechanistic modelling can identify parameters that influence the nitrification performance. Increasing inorganic carbon in BP could invert its rAOB/rNOB value, facilitating its transition to shortcut nitrogen removal.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.WATRES.2017.11.044
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“The process of cutting GMLmn bodies with dm-knives”. Tavkhelidze I, Gielis J, Sn –, 1512-0066 32, 67 (2018)
Keywords: A3 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
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“Progress toward catalytic micro- and nanomotors for biomedical and environmental applications”. Safdar M, Khan SU, Jänis J, Advanced Materials 30, 1703660 (2018). http://doi.org/10.1002/ADMA.201703660
Abstract: Synthetic micro‐ and nanomotors (MNMs) are tiny objects that can autonomously move under the influence of an appropriate source of energy, such as a chemical fuel, magnetic field, ultrasound, or light. Chemically driven MNMs are composed of or contain certain reactive material(s) that convert chemical energy of a fuel into kinetic energy (motion) of the particles. Several different materials have been explored over the last decade for the preparation of a wide variety of MNMs. Here, the discovery of materials and approaches to enhance the efficiency of chemically driven MNMs are reviewed. Several prominent applications of the MNMs, especially in the fields of biomedicine and environmental science, are also discussed, as well as the limitations of existing materials and future research directions.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/ADMA.201703660
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“Refinery and concentration of nutrients from urine with electrodialysis enabled by upstream precipitation and nitrification”. De Paepe J, Lindeboom REF, Vanoppen M, De Paepe K, Demey D, Coessens W, Lamaze B, Verliefde ARD, Clauwaert P, Vlaeminck SE, Water research 144, 76 (2018). http://doi.org/10.1016/J.WATRES.2018.07.016
Abstract: Human urine is a valuable resource for nutrient recovery, given its high levels of nitrogen, phosphorus and potassium, but the compositional complexity of urine presents a challenge for an energy-efficient concentration and refinery of nutrients. In this study, a pilot installation combining precipitation, nitrification and electrodialysis (ED), designed for one person equivalent (1.2 L-urine d(-l)), was continuously operated for similar to 7 months. First, NaOH addition yielded calcium and magnesium precipitation, preventing scaling in ED. Second, a moving bed biofilm reactor oxidized organics, preventing downstream biofouling, and yielded complete nitrification on diluted urine (20-40%, i.e. dilution factors 5 and 2.5) at an average loading rate of 215 mg N L-1 d(-1). Batch tests demonstrated the halotolerance of the nitrifying community, with nitrification rates not affected up to an electrical conductivity of 40 mS cm(-1) and gradually decreasing, yet ongoing, activity up to 96 mS cm(-1) at 18% of the maximum rate. Next-generation 16S rRNA gene amplicon sequencing revealed that switching from a synthetic influent to real urine induced a profound shift in microbial community and that the AOB community was dominated by halophilic species closely related to Nitrosomonas aestuarii and Nitrosomonas marina. Third, nitrate, phosphate and potassium in the filtered (0.1 mu m) bioreactor effluent were concentrated by factors 43, 2.6 and 4.6, respectively, with ED. Doubling the urine concentration from 20% to 40% further increased the ED recovery efficiency by similar to 10%. Batch experiments at pH 6, 7 and 8 indicated a more efficient phosphate transport to the concentrate at pH 7. The newly proposed three-stage strategy opens up opportunities for energy- and chemical-efficient nutrient recovery from urine. Precipitation and nitrification enabled the long-term continuous operation of ED on fresh urine requiring minimal maintenance, which has, to the best of our knowledge, never been achieved before. (C) 2018 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.WATRES.2018.07.016
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“Role of the carbon support on the oxygen reduction and evolution activities in LaNiO3 composite electrodes in alkaline solution”. Alexander CT, Abakumov AM, Forslund RP, Johnston KP, Stevenson KJ, ACS applied energy materials 1, 1549 (2018). http://doi.org/10.1021/ACSAEM.7B00339
Abstract: Metal-air batteries and fuel cells show a great deal of promise in advancing low-cost, high-energy-density charge storage solutions for sustainable energy applications. To improve the activities and stabilities of electrocatalysts for the critical oxygen reduction and evolution reactions (ORR and OER, respectively), a greater understanding is needed of the catalyst/carbon interactions and carbon stability. Herein, we report how LaNiO3 (LNO) supported on nitrogen-doped carbon nanotubes (N-CNT) made from a high-yield synthesis lowers the overpotential for both the OER and ORR markedly to enable a low bifunctional window of 0.81 V at only a 51 mu g cm(-2) mass loading. Furthermore, the addition of LNO to the N-CNTs improves the galvanostatic stability for the OER by almost 2 orders of magnitude. The nanoscale geometries of the perovskites and the CNTs enhance the number of metal-support and charge transfer interactions and thus the activity. We use rotating ring disk electrodes (RRDEs) combined with Tafel slope analysis and ICP-OES to quantitatively separate current contributions from the OER, carbon oxidation, and even anodic iron leaching from carbon nanotubes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1021/ACSAEM.7B00339
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“Sensitivity of nanocrystalline tungsten oxide to CO and ammonia gas determined by surface catalysts”. Marikutsa A, Yang L, Rumyantseva M, Batuk M, Hadermann J, Gaskov A, Sensors and actuators : B : chemical 277, 336 (2018). http://doi.org/10.1016/J.SNB.2018.09.004
Abstract: Nanocrystalline tungsten oxide with variable particle size and surface area was synthesized by aqueous deposition and heat treatment for use in resistive gas sensors. Surface modification with 1 wt.% Pd and Ru was performed by impregnation to improve the sensitivity to CO and ammonia. Acid and oxidation surface sites were evaluated by temperature-programmed techniques using probe molecules. The surface acidity dropped with increasing particle size, and was weakly affected by additives. Lower crystallinity of WO3 and the presence of Ru species favoured temperature-programmed reduction of the materials. Modifying WO3 increased its sensitivity, to CO at ambient condition for modification by Pd and to NH3 at elevated temperature for Ru modification. An in situ infrared study of the gas – solid interaction showed that the catalytic additives change the interaction route of tungsten oxide with the target gases and make the reception of detected molecules independent of the semiconductor oxide matrix.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/J.SNB.2018.09.004
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“Space-time information analysis for resource-conscious urban planning and design : a stakeholder based identification of urban metabolism data gaps”. Voskamp IM, Spiller M, Stremke S, Bregt AK, Vreugdenhil C, Rijnaarts HHM, Resources, conservation and recycling 128, 516 (2018). http://doi.org/10.1016/J.RESCONREC.2016.08.026
Abstract: The research presented here examined at which spatial and temporal resolution urban metabolism should be analysed to generate results that are useful for implementation of urban planning and design interventions aiming at optimization of resource flows. Moreover, it was researched whether a lack of data currently hampers analysing resource flows at this desired level of detail. To facilitate a stakeholder based research approach, the SIRUP tool Space-time Information analysis for Resource-conscious Urban Planning was developed. The tool was applied in a case study of Amsterdam, focused on the investigation of energy and water flows. Results show that most urban planning and design interventions envisioned in Amsterdam require information on a higher spatiotemporal resolution than the resolution of current urban metabolism analyses, i.e., more detailed than the city level and at time steps smaller than a year. Energy-related interventions generally require information on a higher resolution than water-related interventions. Moreover, for the majority of interventions information is needed on a higher resolution than currently available. For energy, the temporal resolution of existing data proved inadequate, for water, data with both a higher spatial and temporal resolution is required. Modelling and monitoring techniques are advancing for both water and energy and these advancements are likely to contribute to closing these data gaps in the future. These advancements can also prove useful in developing new sorts of urban metabolism analyses that can provide a systemic understanding of urban resource flows and that are tailored to urban planning and design.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.RESCONREC.2016.08.026
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“Standardized indoor air quality assessments as a tool to prepare heritage guardians for changing preservation conditions due to climate change”. Anaf W, Leyva Pernia D, Schalm O, Geosciences 8, Unsp 276 (2018). http://doi.org/10.3390/GEOSCIENCES8080276
Abstract: Climate change will affect the preservation conditions of our cultural heritage. Therefore, well-considered mitigation actions should be implemented to safeguard our heritage for future generations. Environmental monitoring is essential to follow up the change in preservation conditions and to evaluate the effectiveness of performed mitigation actions. To support heritage guardians in the processing and evaluation of monitored data, an indoor air quality (IAQ) index for heritage applications is introduced. The index is calculated for each measured point in time and is visualized in a user-friendly and intuitive way. The current paper describes the backbone of the IAQ-calculating algorithm. The algorithm is subsequently applied on a case study in which a mitigation action is implemented in a church.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Systems and software Modelling (AnSyMo); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
DOI: 10.3390/GEOSCIENCES8080276
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Asapu R (2018) A study of plasmonic systems using Layer-by-Layer synthesized core-shell nanoparticles. 142 p
Keywords: Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Success of mainstream partial nitritation/anammox demands integration of engineering, microbiome and modeling insights”. Agrawal S, Seuntjens D, De Cocker P, Lackner S, Vlaeminck SE, Current opinion in biotechnology 50, 214 (2018). http://doi.org/10.1016/J.COPBIO.2018.01.013
Abstract: Twenty years ago, mainstream partial nitritation/anammox (PN/A) was conceptually proposed as pivotal for a more sustainable treatment of municipal wastewater. Its economic potential spurred research, yet practice awaits a comprehensive recipe for microbial resource management. Implementing mainstream PN/A requires transferable and operable ways to steer microbial competition as to meet discharge requirements on a year-round basis at satisfactory conversion rates. In essence, the competition for nitrogen, organic carbon and oxygen is grouped into ON/OFF (suppression/promotion) and IN/OUT (wash-out/retention and seeding) strategies, selecting for desirable conversions and microbes. Some insights need mechanistic understanding, while empirical observations suffice elsewhere. The provided methodological R&D framework integrates insights in engineering, microbiome and modeling. Such synergism should catalyze the implementation of energy-positive sewage treatment.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.COPBIO.2018.01.013
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“Sulfur-based denitrification treating regeneration water from ion exchange at high performance and low cost”. Vandekerckhove TGL, Kobayashi K, Janda J, Van Nevel S, Vlaeminck SE, Bioresource technology 257, 266 (2018). http://doi.org/10.1016/J.BIORTECH.2018.02.047
Abstract: Autotrophic denitrification with sulfur is an underexplored alternative to heterotrophic denitrification to remove nitrate from wastewater poor in organics. The application on ion exchange regeneration water (19.432.1 mS cm−1) is novel. Three fixed bed reactors were tested at 15 °C for >4 months, inoculated with activated sludge from sewage treatment. All were fast in start-up (<10 days) with high performance (94 ± 2% removal efficiency). pH control with NaOH rendered higher nitrate removal rates than limestone addition to the bed (211 ± 13 vs. 102 ± 13 mg N L−1 d−1), related to higher pH (6.64 vs. 6.24) and sulfur surface area. Bacterial communities were strongly enriched in Sulfurimonas (6367%) and Thiobacillus (2426%). In an economic comparison, sulfur-based denitrification (5.3 kg−1 N) was 15% cheaper than methanol-based denitrification (6.22 kg−1 N) and both treatments were opex dominated (85.9 vs. 86.5%). Overall, the technological and economic feasibility should boost further implementation of sulfurotrophic denitrification.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2018.02.047
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“Supernatant organics from anaerobic digestion after thermal hydrolysis cause direct and/or diffusional activity loss for nitritation and anammox”. Zhang Q, Vlaeminck SE, DeBarbadillo C, Su C, Al-Omari A, Wett B, Pümpel T, Shaw A, Chandran K, Murthy S, De Clippeleir H, Water research 143, 270 (2018). http://doi.org/10.1016/J.WATRES.2018.06.037
Abstract: Treatment of sewage sludge with a thermal hydrolysis process (THP) followed by anaerobic digestion (AD) enables to boost biogas production and minimize residual sludge volumes. However, the reject water can cause inhibition to aerobic and anoxic ammonium-oxidizing bacteria (AerAOB & AnAOB), the two key microbial groups involved in the deammonification process. Firstly, a detailed investigation elucidated the impact of different organic fractions present in THP-AD return liquor on AerAOB and AnAOB activity. For AnAOB, soluble compounds linked to THP conditions and AD performance caused the main inhibition. Direct inhibition by dissolved organics was also observed for AerAOB, but could be overcome by treating the filtrate with extended aerobic or anaerobic incubation or with activated carbon. AerAOB additionally suffered from particulate and colloidal organics limiting the diffusion of substrates. This was resolved by improving the dewatering process through an optimized flocculant polymer dose and/or addition of coagulant polymer to better capture the large colloidal fraction, especially in case of unstable AD performance. Secondly, a new inhibition model for AerAOB included diffusion-limiting compounds based on the porter-equation, and achieved the best fit with the experimental data, highlighting that AerAOB were highly sensitive to large colloids. Overall, this paper for the first time provides separate identification of organic fractions within THP-AD filtrate causing differential types of inhibition. Moreover, it highlights the combined effect of the performance of THP, AD and dewatering on the downstream autotrophic nitrogen removal kinetics. (C) 2018 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.WATRES.2018.06.037
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“Synergistic exposure of return-sludge to anaerobic starvation, sulfide and free ammonia to suppress nitrite oxidizing bacteria”. Seuntjens D, Van Tendeloo M, Chatzigiannidou I, Carvajal-Arroyo JM, Vandendriessche S, Vlaeminck SE, Boon N, Environmental science and technology 52, 8725 (2018). http://doi.org/10.1021/ACS.EST.7B06591
Abstract: A key step toward energy-positive sewage treatment is the development of mainstream partial nitritation/anammox, a nitrogen removal technology where aerobic ammonium-oxidizing bacteria (AerAOB) are desired, while nitrite-oxidizing bacteria (NOB) are not. To suppress NOB, a novel return-sludge treatment was investigated. Single and combined effects of sulfide (0-600 mg S L-1), anaerobic starvation (0-8 days), and a free ammonia (FA) shock (30 mg FA-N L-1 for 1 h) were tested for immediate effects and long-term recovery. AerAOB and NOB were inhibited immediately and proportionally by sulfide, with AerAOB better coping with the inhibition, while the short FA shock and anaerobic starvation had minor effects. Combinatory effects inhibited AerAOB and NOB more strongly. A combined treatment of sulfide (150 mg S L-1), 2 days of anaerobic starvation, and FA shock (30 mg FA-N L-1) inhibited AerAOB 14% more strongly compared to sulfide addition alone, while the AerAOB/NOB activity ratio remained constant. Despite no positive change being observed in the immediate-stress response, AerAOB recovered much faster than NOB, with a nitrite accumulation ratio (effluent nitrite on nitrite + nitrate) peak of 50% after 12 days. Studying long-term recovery is therefore crucial for design of an optimal NOB-suppression treatment, while applying combined stressors regularly may lead toward practical implementation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1021/ACS.EST.7B06591
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“Temperature impact on sludge yield, settleability and kinetics of three heterotrophic conversions corroborates the prospect of thermophilic biological nitrogen removal”. Vandekerckhove TGL, De Mulder C, Boon N, Vlaeminck SE, Bioresource technology 269, 104 (2018). http://doi.org/10.1016/J.BIORTECH.2018.08.012
Abstract: In specific municipal and industrial cases, thermophilic wastewater treatment (>45 °C) might bring cost advantages over commonly applied mesophilic processes (1035 °C). To develop such a novel process, one needs sound parameters on kinetics, sludge yield and sludge settleability of three heterotrophic conversions: aerobic carbon removal, denitritation and denitrification. These features were evaluated in acetate-fed sequencing batch reactors (30, 40, 50 and 60 °C). Higher temperatures were accompanied by lower sludge production and maximum specific removal rates, resulting mainly from lower maximum growth rates. Thermophilic denitritation was demonstrated for the first time, with lower sludge production (1826%), higher nitrogen removal rates (2492%) and lower carbon requirement (40%) compared to denitrification. Acceptable settling of thermophilic aerobic (60 °C) and anoxic biomass (50 and 60 °C) was obtained. Overall, this parameter set may catalyze the establishment of thermophilic nitrogen removal, once nitritation and nitratation are characterized. Furthermore, waters with low COD/N ratio might benefit from thermophilic nitritation/denitritation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2018.08.012
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“The influence of surface functionalization on thermal transport and thermoelectric properties of MXene monolayers”. Sarikurt S, Çakir D, Keceli M, Sevik C, Nanoscale 10, 8859 (2018). http://doi.org/10.1039/C7NR09144C
Abstract: The newest members of a two-dimensional material family, involving transition metal carbides and nitrides (called MXenes), have garnered increasing attention due to their tunable electronic and thermal properties depending on the chemical composition and functionalization. This flexibility can be exploited to fabricate efficient electrochemical energy storage (batteries) and energy conversion (thermoelectric) devices. In this study, we calculated the Seebeck coefficients and lattice thermal conductivity values of oxygen terminated M2CO2 (where M = Ti, Zr, Hf, Sc) monolayer MXene crystals in two different functionalization configurations (model-II (MD-II) and model-III (MD-III)), using density functional theory and Boltzmann transport theory. We estimated the thermoelectric figure-of-merit, zT, of these materials by two different approaches, as well. First of all, we found that the structural model (i.e. adsorption site of oxygen atom on the surface of MXene) has a paramount impact on the electronic and thermoelectric properties of MXene crystals, which can be exploited to engineer the thermoelectric properties of these materials. The lattice thermal conductivity kappa(l), Seebeck coefficient and zT values may vary by 40% depending on the structural model. The MD-III configuration always has the larger band gap, Seebeck coefficient and zT, and smaller kappa(l) as compared to the MD-II structure due to a larger band gap, highly flat valence band and reduced crystal symmetry in the former. The MD-III configuration of Ti2CO2 and Zr2CO2 has the lowest kappa(l) as compared to the same configuration of Hf2CO2 and Sc2CO2. Among all the considered structures, the MD-II configuration of Hf2CO2 has the highest kappa(l), and Ti2CO2 and Zr2CO2 in the MD-III configuration have the lowest kappa(l). For instance, while the band gap of the MD-II configuration of Ti2CO2 is 0.26 eV, it becomes 0.69 eV in MD-III. The zT(max) value may reach up to 1.1 depending on the structural model of MXene.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.1039/C7NR09144C
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“The patron of Hieronymus Bosch's 'Last Judgment' triptych in Vienna”. Koldeweij J, Hoogstede L, Ilsink M, Janssens K, De Keyser N, Gotink RK, Legrand S, Nauhaus JM, van der Snickt G, Spronk R, The Burlington magazine 160, 106 (2018)
Abstract: A technical examination of the Last Judgment triptych by Hieronymus Bosch in the Paintings Gallery of the Academy of Fine Arts, Vienna, has revealed a painted escutcheon with the coat of arms of the Burgundian court official Hippolyte de Berthoz underneath the current surface of the right outer wing. This allows him to be firmly identified as the painting's patron.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Titanium (germano-)silicides featuring 10-9 Ω.cm2 contact resistivity and improved compatibility to advanced CMOS technology”. Yu H, Schaekers M, Chew SA, Eyeraert J-L, Dabral A, Pourtois G, Horiguchi N, Mocuta D, Collaert N, De Meyer K, 2018 18th International Workshop On Junction Technology (iwjt) , 80 (2018)
Abstract: uIn this work, we discuss three novel Ti (germano-)silicidation techniques featuring respectively the pre-contact amorphization implantation (PCAI), the TiSi co-deposition, and Ti atomic layer deposition (ALD). All three techniques form TiSix(Ge-y) contacts with ultralow contact resistivity (rho(c)) of (1-3)x10(-9) Omega.cm(2) on both highly doped n-Si and p-SiGe substrates: these techniques meet rho(c) requirement of 5-14 nm CMOS technology and feature unified CMOS contact solutions. We further discuss the compatibility of these techniques to the realistic CMOS transistor fabrication.
Keywords: P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Toxicity of iron oxide nanoparticles : size and coating effects”. Abakumov MA, Semkina AS, Skorikov AS, Vishnevskiy DA, Ivanova AV, Mironova E, Davydova GA, Majouga AG, Chekhonin VP, Journal of biochemical and molecular toxicology 32, e22225 (2018). http://doi.org/10.1002/JBT.22225
Abstract: Toxicological research of novel nanomaterials is a major developmental step of their clinical approval. Since iron oxide magnetic nanoparticles have a great potential in cancer treatment and diagnostics, the investigation of their toxic properties is very topical. In this paper we synthesized bovine serum albumin-coated iron oxide nanoparticles with different sizes and their polyethylene glycol derivative. To prove high biocompatibility of obtained nanoparticles the number of in vitro toxicological tests on human fibroblasts and U251 glioblastoma cells was performed. It was shown that albumin nanoparticles' coating provides a stable and biocompatible shell and prevents cytotoxicity of magnetite core. On long exposure times (48 hours), cytotoxicity of iron oxide nanoparticles takes place due to free radical production, but this toxic effect may be neutralized by using polyethylene glycol modification.
Keywords: A1 Journal article; Pharmacology. Therapy; Electron microscopy for materials research (EMAT)
DOI: 10.1002/JBT.22225
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“Understanding the mechanisms of how poly aluminium chloride inhibits short-chain fatty acids production from anaerobic fermentation of waste activated sludge”. Chen Y, Wu Y, Wang D, Li H, Wang Q, Liu Y, Peng L, Yang Q, Li X, Zeng G, Chen Y, Chemical engineering journal 334, 1351 (2018). http://doi.org/10.1016/J.CEJ.2017.11.064
Abstract: Poly aluminum chloride (PAC) is accumulated in waste activated sludge at high levels. However, details of how PAC affects short-chain fatty acids (SCFA) production from anaerobic sludge fermentation has not been documented. This work therefore aims to fill this knowledge gap by analyzing the impact of PAC on the aggregate of sludge flocs, disruption of extracellular polymeric substances (EPS), and the bio-processes of hydrolysis, acid-ogenesis, and methanogenesis. The relationship between SCFA production and different aluminum species (i.e., Ala, Alb, and Alc) was also identified by controlling different OH/Al ratio and pH in different fermentation systems. Experimental results showed that with the increase of PAC addition from 0 to 40 mg Al per gram of total suspended solids, SCFA yield decreased from 212.2 to 138.4 mg COD/g volatile suspended solids. Mechanism exploration revealed that PAC benefited the aggregates of sludge flocs and caused more loosely-and tightly-bound extracellular polymeric substances remained in sludge cells. Besides, it was found that the hydrolysis, acidiogenesis, and methanogenesis processes were all inhibited by PAC. Although three types of Al species, i.e., Ala (Al monomers, dimer, and trimer), Alb (Al-13(AlO4Al12(OH)(24)(H2O) 7+ 12), and Alc (Al polymer molecular weight normally larger than 3000 Da), were co-existed in fermentation systems, their impacts on SCFA production were different. No correlation was found between SCFA and Ala, whereas SCFA production decreased with the contents of Alb and Alc. Compared with Alb, Alc was the major contributor to the decreased SCFA production ( R-2 = 0.5132 vs R-2 = 0.98). This is the first report revealing the underlying mechanism of how PAC affects SCFA production and identifying the contribution of different Al species to SCFA inhibition.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.CEJ.2017.11.064
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“Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties”. Mobaraki A, Kandemir A, Yapicioglu H, Gulseren O, Sevik C, Computational materials science 144, 92 (2018). http://doi.org/10.1016/J.COMMATSCI.2017.12.005
Abstract: In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1016/J.COMMATSCI.2017.12.005
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“Wet etching of TiN in 1-D and 2-D confined nano-spaces of FinFET transistors”. Vereecke G, De Coster H, Van Alphen S, Carolan P, Bender H, Willems K, Ragnarsson L-A, Van Dorpe P, Horiguchi N, Holsteyns F, Microelectronic engineering 200, 56 (2018). http://doi.org/10.1016/J.MEE.2018.09.004
Abstract: In the manufacturing of multi-Vt FinFET transistors, the gate material deposited in the nano-spaces left by the removed dummy gate must be etched back in mask-defined wafer areas. Etch conformality is a necessary condition for the control of under-etch at the boundary between areas defined by masking. We studied the feasibility of TiN etching by APM (ammonia peroxide mixture, also known as SC1) in nano-confined volumes representative of FinFET transistors of the 7 nm node and below, namely nanotrenches with 1-D confinement and nanoholes with 2-D confinement. TiN etching was characterized for rate and conformality using different electron microscopy techniques. Etching in closed nanotrenches was conformal, starting and progressing all along the 2-D seam, with a rate that was 38% higher compared to a planar film. Etching in closed nanoholes proved also to be conformal and faster than planar films, but with a delay to open the 1-D seam that seemed to depend strongly on small variations in the hole diameter. However, holes between the fins at the bottom of the removed dummy gate, are not circular and do present 2-D seams that should lend themselves for an easier start of conformal etching as compared to the circular nanoholes used in this study. Finally, to explain the higher etch rate observed in nano-confined features, concentrations of ions in nanoholes were calculated taking the overlap of electrostatic double layers (EDL) into account. With negatively charged TiN walls, as measured by streaming potential on planar films, ammonium was the dominant ion in nanoholes. As no chemical reaction proposed in the literature for TiN etching matched with this finding, we proposed that the formation of ammine complexes, dissolving the formed Ti oxide, was the rate-determining step.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1016/J.MEE.2018.09.004
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“Why does not the leaf weight-area allometry of bamboos follow the 3/2-power law?”.Lin S, Shao L, Hui C, Song Y, Reddy GVP, Gielis J, Li F, Ding Y, Wei Q, Shi P, Reddy GVP, Frontiers in plant science 9, 583 (2018). http://doi.org/10.3389/FPLS.2018.00583
Abstract: The principle of similarity (Thompson, 1917) states that the weight of an organism follows the 3/2-power law of its surface area and is proportional to its volume on the condition that the density is constant. However, the allometric relationship between leaf weight and leaf area has been reported to greatly deviate from the 3/2-power law, with the irregularity of leaf density largely ignored for explaining this deviation. Here, we choose 11 bamboo species to explore the allometric relationships among leaf area (A), density (ρ), length (L), thickness (T), and weight (W). Because the edge of a bamboo leaf follows a simplified two-parameter Gielis equation, we could show that A ∝ L2 and that A ∝ T2. This then allowed us to derive the density-thickness allometry ρ ∝ Tb and the weight-area allometry W ∝ A(b+3)/2 ≈ A9/8, where b approximates −3/4. Leaf density is strikingly negatively associated with leaf thickness, and it is this inverse relationship that results in the weight-area allometry to deviate from the 3/2-power law. In conclusion, although plants are prone to invest less dry mass and thus produce thinner leaves when the leaf area is sufficient for photosynthesis, such leaf thinning needs to be accompanied with elevated density to ensure structural stability. The findings provide the insights on the evolutionary clue about the biomass investment and output of photosynthetic organs of plants. Because of the importance of leaves, plants could have enhanced the ratio of dry material per unit area of leaf in order to increase the efficiency of photosynthesis, relative the other parts of plants. Although the conclusion is drawn only based on 11 bamboo species, it should also be applicable to the other plants, especially considering previous works on the exponent of the weight-area relationship being less than 3/2 in plants.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.3389/FPLS.2018.00583
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