| 1. |
- Ritscher, Amélie, et al.
(författare)
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Zurich Statement on Future Actions on Per - and Polyfluoroalkyl Substances (PFASs)
- 2018
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 126:8
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Tidskriftsartikel (refereegranskat)abstract
- Per - and polyfluoroalkyl substances (PFASs) are man-made chemicals that contain at least one perfluoroalkyl moiety, -CnF2n-. To date, over 4,000 unique PFASs have been used in technical applications and consumer products, and some of them have been detected globally in human and wildlife biomonitoring studies. Because of their extraordinary persistence, human and environmental exposure to PFASs will be a long-term source of concern. Some PFASs such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) have been investigated extensively and thus regulated, but for many other PFASs, knowledge about their current uses and hazards is still very limited or missing entirely. To address this problem and prepare an action plan for the assessment and management of PFASs in the coming years, a group of more than 50 international scientists and regulators held a two-day workshop in November, 2017. The group identified both the respective needs of and common goals shared by the scientific and the policy communities, made recommendations for cooperative actions, and outlined how the science-policy interface regarding PFASs can be strengthened using new approaches for assessing and managing highly persistent chemicals such as PFASs.
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| 2. |
- Rodrigues, Diogo, et al.
(författare)
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Production of recombinant human aldehyde oxidase in Escherichia coli and optimization of its application for the preparative synthesis of oxidized drug metabolites
- 2014
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Ingår i: ChemCatChem. - : Blackwell Publishing Ltd. - 1867-3880 .- 1867-3899. ; 6:4, s. 1028-1042
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant human aldehyde oxidase (AO) was expressed in Escherichia coli. Different cell disruption methods and conditions of cell culture in shake flasks and bioreactors and of biotransformation on an analytical scale were tested to optimize the synthesis of oxidized AO drug metabolites. The volumetric productivity was increased 24-fold by optimizing the cell culture conditions. The highest yield was achieved in a 25 L stirred tank bioreactor under non-oxygen-limited conditions and high lactose feed rate. Suspensions of highly concentrated and well-aerated whole cells at neutral pH and relatively low temperatures led to the best conversion. The solvent for the substrate and the buffering agent for the biotransformation had an important effect. In a biotransformation with AO, 210 mg of famciclovir was converted to diacetyl penciclovir a yield of 82 %. The optimized protocol represents a viable method for the preparative synthesis of oxidized AO metabolites of drugs. Drug metabolites: Recombinant human aldehyde oxidase is expressed in Escherichia coli. The highest volumetric productivity is achieved in a 25 L stirred tank bioreactor under non-oxygen-limited conditions and high lactose feed rate. In a biotransformation with concentrated whole cells at pH 7.4 and 30 °C, 210 mg of famciclovir is converted to diacetyl penciclovir in a yield of 82 %. The optimized protocol enables the preparative synthesis of oxidized aldehyde oxidase metabolites of drugs.
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| 3. |
- Zhang, Wen, et al.
(författare)
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Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater
- 2019
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Ingår i: Journal of Environmental Management. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0301-4797 .- 1095-8630. ; 246, s. 920-928
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Tidskriftsartikel (refereegranskat)abstract
- A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite (R) and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency > 90% by GAC with an average removal of 97 +/- 6%. Xylit and lignite were less efficient with an average removal of 80 +/- 28% and 68 +/- 29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (K-ow) >= 3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 +/- 27% and 14 +/- 2%, respectively), while the calcium-silicate material Polonite (R) precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.
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| 4. |
- Mussabek, Dauren, et al.
(författare)
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PFAS in the Drinking Water Source: Analysis of the Contamination Levels, Origin and Emission Rates
- 2023
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater contamination caused by the use of the aqueous film-forming foam (AFFF) containing per- and polyfluoroalkyl substances (PFAS) was investigated in southern Sweden. ΣPFAS concentrations in groundwater ranged between 20 and 20,000 ng L−1; PFAS composition was primarily represented by PFOS and PFHxS. The PFAS chain length was suggested to have an impact on the contaminant distribution and transport in the groundwater. PFAS profiling showed that the use of PFSAs- and PFCAs/FTSAs-based PFAS-AFFF can be a contributor to PFAS contamination of the drinking water source (groundwater). PFAS emission was connected to PFAS-AFFF use during the fire-training and fire-fighting equipment tests at the studied location. PFAS emission per individual fire training was (semi-quantitatively) estimated as [1.4 < 11.5 ± 5.7 < 43.7 kg] (n = 20,000). The annual emission estimates varied as [11 < 401 ± 233 < 1125 kg yr−1] (n = 1005) considering possible [2 < 35 ± 20 < 96] individual fire-training sessions per year.
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| 5. |
- Liebi, Marianne, 1984, et al.
(författare)
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3D nanoscale analysis of bone healing around degrading Mg implants evaluated by X-ray scattering tensor tomography
- 2021
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 134, s. 804-817
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Tidskriftsartikel (refereegranskat)abstract
- The nanostructural adaptation of bone is crucial for its biocompatibility with orthopedic implants. The bone nanostructure also determines its mechanical properties and performance. However, the bone's temporal and spatial nanoadaptation around degrading implants remains largely unknown. Here, we present insights into this important bone adaptation by applying scanning electron microscopy, elemental analysis, and small-angle X-ray scattering tensor tomography (SASTT). We extend the novel SASTT reconstruction method and provide a 3D scattering reciprocal space map per voxel of the sample's volume. From this reconstruction, parameters such as the thickness of the bone mineral particles are quantified, which provide additional information on nanostructural adaptation of bone during healing. We selected a rat femoral bone and a degrading ZX10 magnesium implant as model system, and investigated it over the course of 18 months, using a sham as control. We observe that the bone's nanostructural adaptation starts with an initially fast interfacial bone growth close to the implant, which spreads by a re-orientation of the nanostructure in the bone volume around the implant, and is consolidated in the later degradation stages. These observations reveal the complex bulk bone-implant interactions and enable future research on the related biomechanical bone responses. Statement of significance: Traumatic bone injuries are among the most frequent causes of surgical treatment, and often require the placement of an implant. The ideal implant supports and induces bone formation, while being mechanically and chemically adapted to the bone structure, ensuring a gradual load transfer. While magnesium implants fulfill these requirements, the nanostructural changes during bone healing and implant degradation remain not completely elucidated. Here, we unveil these processes in rat femoral bones with ZX10 magnesium implants and show different stages of bone healing in such a model system.
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| 6. |
- Zhang, Wen, et al.
(författare)
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Removal of micropollutants and nutrients in household wastewater using organic and inorganic sorbents
- 2018
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Ingår i: Desalination and Water Treatment. - : Desalination Publications. - 1944-3994 .- 1944-3986. ; 120, s. 88-108
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of five organic and five inorganic sorbents in removing 19 organic micropollutants (MPs), phosphorus, nitrogen, and dissolved organic carbon (DOC) was tested in a two-week column experiment using household wastewater spiked with pharmaceuticals (n = 6), biocides/pesticides (n = 4), organophosphates (n = 3), a fragrance, a UV-stablizer, a food additive, a rubber additive, a plasticizer and a surfactant. Two types of granular activated carbon (GAC), two types of lignite, a pine bark product, and five mineral-based sorbents were tested. All the organic sorbents except pine bark achieved better removal efficiencies of DOC (on average, 70 +/- 27%) and MPs (93 +/- 11%) than the inorganic materials (DOC: 44 +/- 7% and MPs: 66 +/- 38%). However, the organic sorbents (i.e. GAC and xyloid lignite) removed less phosphorus (46 +/- 18%), while sorbents with a high calcium or iron content (i.e. Polonite (R) and lignite) generally removed phosphorus more efficiently (93 +/- 3%). Ammonium- nitrogen was well removed by sorbents with a pH between 7 and 9, with an average removal of 87%, whereas lignite (pH 4) showed the lowest removal efficiency (50%). Some MPs were well removed by all sorbents (>= 97%) including biocides (hexachlorobenzene, triclosan and terbutryn), organophosphates (tributylphosphate, tris-(1,3-dichloro-2-propyl) phosphate and triphenylphosphate) and one fragrance (galaxolide). The pesticide 2,6-dichlorobenzamide and the pharmaceutical diclofenac were poorly removed by the pine bark and inorganic sorbents (on average, 4%), while organic sorbents achieved high removal of these chemicals (87%).
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| 7. |
- Chen, M., et al.
(författare)
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A novel diode structure with controlled injection of backside holes (CIBH)
- 2006
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a novel 3.3kV diode structure with controlled injection of backside holes, i.e. CIBH diode. This new diode structure features buried floating p layers at the cathode side. These p doped areas prevent the formation of high electric field strength at the nn+ junction and accordingly avoid the avalanche generation at the nn+ junction. The CIBH diode concept provides, compared to diodes without p layers and the same design, significantly improved dynamic ruggedness and improved sott reverse recovery at low current densities. Simulations and results of the first fabricated diodes show the readability of this new promising diode concept.
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| 8. |
- Bock, Alexander, 1985-, et al.
(författare)
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VCMass: A Framework for Verification of Coronal Mass Ejection Ensemble Simulations
- 2014
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Konferensbidrag (refereegranskat)abstract
- Supporting the growing field of space weather forecasting, we propose a framework to analyze ensemble simulations of coronal mass ejections. As the current simulation technique requires manual input, uncertainty is introduced into the simulation pipeline which leads to inaccurate predictions. Using our system, the analyst can compare ensemble members against ground truth data (arrival time and geo-effectivity) as well as information derived from satellite imagery. The simulations can be compared on a global basis, based on time-resolved quality measures, and as a 3D volumetric rendering with embedded satellite imagery in a multi-view setup. This flexible framework provides the expert with the tools to increase the knowledge about the, as of yet not fully understood, principles behind the formation of coronal mass ejections.
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| 9. |
- Mussabek, Dauren, et al.
(författare)
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Temporal trends and sediment–water partitioning of per- and polyfluoroalkyl substances (PFAS)in lake sediment
- 2019
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 227, s. 624-629
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Tidskriftsartikel (refereegranskat)abstract
- The use of per- and polyfluoroalkyl substances (PFAS)containing aqueous film forming foams (AFFF)at fire training facilities can have an adverse impact on the surrounding environment. The aim of the present study was to study the distribution and temporal trend of 26 PFAS in water and sediment cores for a lake and a pond affected by AFFF release from a fire training facility in Luleå, northern Sweden. In the aqueous phase, maximum ΣPFAS concentration was 1.700 ± 90 ng L −1 . Dominant PFAS groups were perfluoroalkane sulfonates (PFSAs)with 70% of the ΣPFAS, followed by perfluoroalkyl carboxylates (PFCAs, 29%), whereas the contribution of 6:2 fluorotelomer carboxylate (FTSAs)was low (<1%). In the sediment core samples, ΣPFAS concentrations ranged between <1 μg kg −1 dry weight (dw)and 76 μg kg −1 dw, where perfluorooctane sulfonate (PFOS)and perfluorohexane sulfonate (PFHxS)had an average contribution of ∼71% and ∼23% of the ΣPFAS. The sediment core analysis indicated that the PFAS contamination began about 1994 and the highest accumulation rate was observed for the period 2003–2009. The PFAS flux increased from 2.3 μg m −2 yr −1 dw in 1994 to 12 μg m −2 yr −1 dw by 2009. Over the accumulation period 1994–2009, the lake sediment surface received 213 μg m −2 dw for ƩPFAS, where PFOS contributed with 125 μg m −2 yr −1 dw and PFHxS with 65 μg m −2 dw. Results point to that sediment cores collected near PFAS hotspot areas can be used as a contamination record to reconstruct release history.
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| 10. |
- Oettershagen, Lutz, et al.
(författare)
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A Higher-Order Temporal H-Index for Evolving Networks
- 2023
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Ingår i: KDD 2023. - : Association for Computing Machinery (ACM). ; , s. 1770-1782
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Konferensbidrag (refereegranskat)abstract
- The H-index of a node in a static network is the maximum value h such that at least h of its neighbors have a degree of at least h. Recently, a generalized version, the n-th order H-index, was introduced, allowing to relate degree centrality, H-index, and the k-core of a node. We extend the n-th order H-index to temporal networks and define corresponding temporal centrality measures and temporal core decompositions. Our n-th order temporal H-index respects the reachability in temporal networks leading to node rankings, which reflect the importance of nodes in spreading processes. We derive natural decompositions of temporal networks into subgraphs with strong temporal coherence. We analyze a recursive computation scheme and develop a highly scalable streaming algorithm. Our experimental evaluation demonstrates the efficiency of our algorithms and the conceptional validity of our approach. Specifically, we show that the n-th order temporal H-index is a strong heuristic for identifying possible super-spreaders in evolving social networks and detects temporally well-connected components.
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