| 1. |
- Guieysse, Benoit, et al.
(author)
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Sequential UV-biological degradation of polycyclic aromatic hydrocarbons in two-phases partitioning bioreactors
- 2005
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In: Chemosphere. - : Elsevier BV. - 1879-1298 .- 0045-6535. ; 59:3, s. 369-376
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Journal article (peer-reviewed)abstract
- A method based on U-V-irradiation in organic solvent followed by transfer of the remaining pollutants into silicone oil for subsequent biodegradation in a biphasic system inoculated with a phenanthrene degrading Pseudomonas sp. was tested for the treatment of various mixtures of PAHs. Acetone was first selected as the most suitable solvent compared to methanol, acetonitrile and silicone oil for the removal of pyrene and phenanthrene. The sequential treatment was then applied to the treatment of a mixture of fluorene, phenanthrene, anthracene, fluoranthrene, pyrene, benzo(a)anthracene and benzo(a)pyrene in acetone. These compounds were photodegraded in the following order of initial removal rates (mg l(-1) d(-1)): benzo(a)pyrene (7.8) > anthracene (5.0) > benzo(a)anthracene (2.5) > fluoranthrene (1.8) > pyrene (1.5) > phenanthrene (1.2) > fluorene (0.2). U-V-treatment allowed complete removal of, anthracene, benzo(a)anthracene and benzo(a)pyrene and removals of 63% of pyrene and 37% of fluorene after 434h or irradiation. The subsequent biological treatment removed the remaining phenanthrene and fluorene by 100% and 90%, respectively, after 790h of cultivation. Although less efficient due to the presence of interfering compounds, the UV-biological treatment of a soil extract allowed a 63% removal of the seven PAHs named above. Microbial growth did not occur when the pollutants were directly supplied to the microorganism showing that biphasic systems reduced the toxicity effects cause by mixtures of PAHs at high concentrations. This study demonstrates the potential of selective UV treatment of high molecular weight PAHs followed by biological treatment of the low molecular weight species in biphasic systems. (c) 2004 Elsevier Ltd. All rights reserved.
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| 2. |
- Benzoni, G., et al.
(author)
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First Measurement of Beta Decay Half-lives in Neutron-rich Tl and Bi Isotopes
- 2012
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 715:4-5, s. 293-297
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Journal article (peer-reviewed)abstract
- Neutron-rich isotopes around lead, beyond N = 126, have been studied exploiting the fragmentation of an uranium primary beam at the FRS-RISING setup at GSI. For the first time beta-decay half-lives of Bi-219 and Tl-211,Tl-212,Tl-213 isotopes have been derived. The half-lives have been extracted using a numerical simulation developed for experiments in high-background conditions. Comparison with state of the art models used in r-process calculations is given, showing a systematic underestimation of the experimental values, at variance from close-lying nuclei. (c) 2012 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Lange, Oliver F., et al.
(author)
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Scrutinizing Molecular Mechanics Force Fields on the Submicrosecond Timescale with NMR Data
- 2010
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In: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 99:2, s. 647-655
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Journal article (peer-reviewed)abstract
- Protein dynamics on the atomic level and on the microsecond timescale has recently become accessible from both computation and experiment. To validate molecular dynamics (MD) at the submicrosecond timescale against experiment we present microsecond MD simulations in 10 different force-field configurations for two globular proteins, ubiquitin and the gb3 domain of protein G, for which extensive NMR data is available. We find that the reproduction of the measured NMR data strongly depends on the chosen force field and electrostatics treatment. Generally, particle-mesh Ewald outperforms cut-off and reaction-field approaches. A comparison to measured J-couplings across hydrogen bonds suggests that there is room for improvement in the force-field description of hydrogen bonds in most modern force fields. Our results show that with current force fields, simulations beyond hundreds of nanoseconds run an increased risk of undergoing transitions to nonnative conformational states or will persist within states of high free energy for too long, thus skewing the obtained population frequencies. Only for the AMBER99sb force field have such transitions not been observed. Thus, our results have significance for the interpretation of data obtained with long MD simulations, for the selection of force fields for MD studies and for force-field development. We hope that this comprehensive benchmark based on NMR data applied to many popular MD force fields will serve as a useful resource to the MD community. Finally, we find that for gb3, the force-field AMBER99sb reaches comparable accuracy in back-calculated residual dipolar couplings and J-couplings across hydrogen bonds to ensembles obtained by refinement against NMR data.
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| 5. |
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| 6. |
- Beuerle, Bernhard, 1983-, et al.
(author)
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A CPW Probe to Rectangular Waveguide Transition for On-wafer Micromachined Waveguide Characterization
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Other publication (other academic/artistic)abstract
- A new transition from coplanar waveguide probe to micromachined rectangular waveguide for on-wafer device characterization is presented in this article. The transition is fabricated in the same double H-plane split silicon micromachined waveguide technology as the devices under test, requiring no additional post-processing or assembly steps. We outline the design and fabrication process of the transition for the frequency band of 220 – 330 GHz. A coplanar waveguide structure acts as the probing interface, with an E-field probe protruding in the waveguide cavity exciting the fundamental waveguide mode. Guard structures around the E-field probe increase the aspect ratio during deep reactive ion etching and secure its geometry. A full equivalent circuit model is provided by analyzing its working principle. RF characterization of fabricated devices is performed for both single-ended and back-to-back configurations. Measured S-parameters of the single-ended transition are obtained by applying a two-tiered calibration and are analyzed using the equivalent circuit model. The insertion loss of the single-ended transition lies between 0.3 dB and 1.5 dB over the whole band, with the return loss in excess of 8 dB. In addition to previously reported characterization of a range of devices under test the viability of the transition for on-wafer device calibration is demonstrated by characterizing a straight waveguide line, achieving an insertion loss per unit length of 0.02 – 0.08 dB/mm in the frequency band of 220 – 330 GHz.
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| 7. |
- García, A., et al.
(author)
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Uniformity and mechanical properties of dense asphalt concrete with steel wool fibers
- 2013
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In: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 43, s. 107-117
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Journal article (peer-reviewed)abstract
- Fibers in asphalt concrete are known for enhancing its strength and fatigue characteristics while increasing ductility. Additionally, fibers may increase the dynamic modulus, moisture resistance, creep compliance, rutting and freeze-thaw resistance of asphalt concrete, preventing the formation and propagation of cracks. The addition of fibers may influence the properties of the material, but it is not clear how is this influence, and which are the optimum amount, length and diameter of fibers needed for not having a negative impact on the mixture. For this reason, fibers (steel wool) distribution and their effect on the porosity and electrical conductivity of dense asphalt concrete have been studied. With that purpose, 25 different mixtures, with the same aggregates gradation and amount of bitumen, but with two different lengths of fibers, four different percentages, and four different diameters of steel wool have been built. Results show that long and thin fibers produce many clusters and a poor distribution, while short and thick fibers disperse very well in the mixture. It was also observed that fibers can be seriously damaged during the mixing and compaction processes. Finally, it has been found that steel wool fibers do not have a relevant influence on the particle loss resistance and flexural strength of dense asphalt concrete.
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| 8. |
- Rolfe, Victoria, 1987
(author)
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Exploring socioeconomic inequality in educational opportunity and outcomes in Sweden and beyond
- 2021
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Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis aims to explore Sweden’s achievement gap in international assessment and how this may have developed in the context of a network of educational inequalities. Theoretically grounded in the Model of Potential Educational Experiences (Schmidt, Raizen, Britton, Bianchi, & Wolfe, 1997), the thesis investigates how the relationship between the intended and attained curriculum is moderated by actions at the classroom level. Teacher implementation of the curriculum provides opportunities for students to learn yet is a source of inequity in the school system. Student socioeconomic background and the amount of subject content (or Opportunity to Learn – OTL) they are exposed to are judged to significantly influence student outcomes. Socioeconomic inequality of outcomes has been perennially observed in educational assessment and has been a topic of investigation since the mid-twentieth century, while a body of literature suggests that there is an equality gap in OTL, with more advantaged students offered more content coverage through their mathematics lessons. This compilation thesis features an integrative essay and three empirical studies, which apply statistical analysis to data from two international large-scale assessments, PISA and TIMSS. Study I investigated the measurement of socioeconomic status over time in Sweden. After establishing which questionnaire items consistently appeared in PISA, a measurement model bespoke to Sweden was constructed from 2000 data. The model was found to be replicable and trustworthy over time, establishing an alternative measure of SES applicable to 15 years of Swedish PISA data. In Study II socioeconomic inequalities in opportunity and outcomes in mathematics and science, and the question as to whether unequal opportunities perpetuate unequal outcomes were investigated in 78 countries using 4 cycles of TIMSS data. Achievement gaps were observed near universally. These achievement gaps were strong and increased across the cycles of TIMSS. Opportunity gaps were less frequently observed, and evidence that schooling exacerbates socioeconomic inequalities in outcomes was confined to a select group of countries including England, Malta, Scotland, and Singapore. Sweden’s achievement gap was consistent across the time points, and an opportunity gap was only observed in half the cycles. Finally, schooling mediated the effects of SES on achievement in only the 2003 cycle for Sweden, suggesting equitable mathematics provision in Sweden. Teachers are essential to the implementation of the curriculum, and their actions affect the experiences of students. Multiple inequalities in Swedish classrooms were explored in Study III. The 2015 TIMSS cycle was grouped by whether or not teachers were mathematics specialists. Overall, Swedish mathematics students experienced substantial gaps in achievement, opportunity and teacher quality. However, differing patterns of inequalities emerged in the grouped model. Among classes with specialist teachers there was a moderate opportunity gap, while those with non-specialists had a teacher quality gap. In both groups there was a socioeconomic gap in teacher perception of school ethos towards academics. The findings of this study underscore the importance of having high-quality teachers in mathematics classrooms as a temper of outcome inequity. Collectively, the findings of the constituent studies confirm the persistence of the achievement gap in Sweden and globally, contextualize the opportunity gap in Sweden, and underline the importance of item choice and construct measurement when modelling inequality using international data. Suggestions are made for further research integrating the thesis’s contribution to construction measurement into trend analyses of opportunity gaps, and combining register and international data to parse how changes in teacher education may affect equality in Swedish classrooms.
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| 9. |
- Berndt, Jaqueline, 1963-
(author)
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Exhibiting Manga, Representing “Japan”
- 2024. - 1
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In: <em>Japanese Art: Transcultural Perspectives</em>. - Leiden : Brill Academic Publishers. - 9789004704176 ; , s. 543-565
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Book chapter (peer-reviewed)
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| 10. |
- Kettisen, Karin
(author)
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Engineering of Human Fetal Hemoglobin
- 2021
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Doctoral thesis (other academic/artistic)abstract
- In blood, the oxygen-transporting protein hemoglobin (Hb) governs the oxygenation of cells and tissues. Naturally, this protein has claimed a place in the center of the research field of artificial oxygen therapeutics. Such Hb-based products have used cell-free Hb purified from human, bovine, invertebrate, or recombinant sources to create hemoglobin-based oxygen carriers (HBOCs). However, administration of these cell-free Hb products into the bloodstream initiates several unwanted adverse events. The inherent toxic reactivity of Hb related to heme-mediated oxidation, nitric oxide scavenging, and heme release give rise to serious side effects. These issues have persisted despite attempts at finding a formulation strategy to tame native Hb outside the red blood cell. This dissertation describes work regarding the engineering of human fetal Hb (HbF) for screening of beneficial protein design strategies on the protein itself, both in terms of retaining oxidative stability and from a production perspective. Oxidative side effects are central to the extracellular toxicity exhibited by Hb. We examined the effect of modifying redox active cysteine residues in HbF by removing and/or adding cysteine at the conserved hotspot γCys93 and a surface-located site on the α-subunit. The conserved cysteine was important for the oxidative stability of the protein and removal produced a more unstable Hb molecule. In contrast, the addition of cysteine on the surface of the α-subunit alleviated damaging reactions during oxidative conditions by providing an alternative oxidation hotspot. As the surface of the α-subunit appeared to be promising as a target area for mutagenesis, we explored a set of mutants where alanine residues were substituted into negatively charged aspartic acid. This lowered the pI of HbF and reduced the DNA cleavage rate without affecting the overall structural integrity. We also observed an extended half-life in vivo as well as unchanged oxidation and heme loss rates, indicating that improved functions could be attained with modification of the net surface charge without adversely affecting key functions and stability.We continued to focus on the surface of HbF and created mutants with more dramatically changed net surface charge by replacing positive surface residues with negatively charged residues. We improved Hb yields in the crude extracts during recombinant expression in E. coli with this strategy, but non-target Hb fractions were present in significant quantities in two of the three mutant samples. This indicated an unbalanced assembly of subunits in the HbF variants carrying the γ-subunit mutations, leading to the formation of homotetramers. In addition, the chosen γ-subunit mutations contributed to a more oxidatively unstable Hb molecule, as seen by increased autoxidation rates. The best-performing negatively charged mutant was subjected to a more in-depth characterization study. The crystal structure of this mutant was solved and thus confirmed the surface-exposed locations of the mutations. The mutant showed no significant differences in oxidation rate reactions but differed in reduction and heme loss rates from wild-type HbF in reactions governed by the α-subunit. In contrast to a previously studied HbF mutant, this mutant did not show any increased effect on retention time in vivo. However, a dramatic decrease in DNA cleavage rate was seen, indicating a much less damaging behavior towards important cellular components.We conclude that there are strategies for modifying HbF itself for the improvement of protein properties towards a better, and more easily produced Hb for HBOC development. The suggested modifications to the HbF protein presented in this work could be used in combination with other protein engineering strategies for Hb development.
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