| 1. |
- Gad, Helge, et al.
(författare)
-
MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
- 2014
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 508:7495, s. 215-221
-
Tidskriftsartikel (refereegranskat)abstract
- Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bindin the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.
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| 2. |
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| 3. |
- Palmborg, Cecilia, et al.
(författare)
-
Odling av rörflen - Sortförsök, odlingsåtgärder och klimatpåverkan : Projekt Bioenergigårdar i ett nytt landskap - Slutrapport 1 Delprojekt FoU
- 2011
-
Rapport (populärvet., debatt m.m.)abstract
- Projekt Bioenergigårdar i ett nytt landskap var ett utvecklingsprojekt som drevs av länsstyrelsen Västerbotten 2008-2011. Ett delprojekt, delprojekt FoU, drevs av institutionen för norrländsk jordbruksvetenskap och enheten för biomassateknologi och kemi på SLU Umeå. Delprojektet har i huvudsak finansierats av Kempestiftelserna, men också av SLU och EU. Forskning kring rörflen som energigröda har bedrivits vid SLU Umeå sedan senare delen av 1980-talet. Det är dock först genom projektet "Ökad produktion av biobränsleråvara - minskat oljeberoende" 2006-2007 och Bioenergigårdar som odling i länet kommit igång i kommersiell skala. Tidigare forskningsinsatser vid SLU och erfarenheter och önskemål från pågående verksamhet med rörflensodling har lett fram till fem aktivitetsområden och huvudinriktningar. Alla delrapporter från undersökningar och experiment har sammanställts till två slutrapporter. Rapport 1 publiceras av institutionen för norrländsk jordbruksvetenskap, SLU Umeå: 1. Sortprövning av rörflen- Provning av kommersiella sorter och lovande nummersorter på fler platser än förut. 2. Produktion av åkerbränsle- Hur kan man minska gödslingskostnaderna och varför drabbas produktionen ibland av svackor? 3. Åkerbränsle miljöaspekter- Hur mycket kol lagrar rörflen i rötter och jord och hur påverkar rörflensodling koldioxidavgången från dikad torvmark? Rapport 2 publiceras av enheten för biomassateknologi och kemi, SLU Umeå: 4. Skörd och transportsystem- Vilka skördesystem och transportsystem är effektivast och billigast för att få fram dels lös hackad rörflen, dels balad rörflen som kan lagras? 5. Bränsleförädling och förbränning- Studier av brikettering, tillsatser, bränslemixar och pannor.
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| 4. |
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| 5. |
- Al-Adili, Ali, et al.
(författare)
-
Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234
- 2016
-
Ingår i: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics. - : EDP Sciences.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of U-235(n,f). The second, on the fission fragment properties in the thermal fission of U-234(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on U-235(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called saw-tooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of U-234(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of U-235(nth, f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.
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| 6. |
- Al-Adili, Ali, et al.
(författare)
-
Fission Activities of the Nuclear Reactions Group in Uppsala
- 2015
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Ingår i: Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, THEORY-3. - : Elsevier BV. ; , s. 145-149
-
Konferensbidrag (refereegranskat)abstract
- This paper highlights some of the main activities related to fission of the nuclear reactions group at Uppsala University. The group is involved for instance in fission yield experiments at the IGISOL facility, cross-section measurements at the NFS facility, as well as fission dynamics studies at the IRMM JRC-EC. Moreover, work is ongoing on the Total Monte Carlo (TMC) methodology and on including the GEF fission code into the TALYS nuclear reaction code. Selected results from these projects are discussed.
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| 7. |
- Al-Adili, Ali, et al.
(författare)
-
Ion counting efficiencies at the IGISOL facility
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high precision. Fission fragments from a U target are passing through a Ni foil and entering a gas filled chamber. The collected fragments are guided through a mass separator to a Penning trap where their masses are identified. This simulation work focuses on how different fission fragment properties (mass, charge and energy) affect the stopping efficiency in the gas cell. In addition, different experimental parameters are varied (e. g. U and Ni thickness and He gas pressure) to study their impact on the stopping efficiency. The simulations were performed using the Geant4 package and the SRIM code. The main results suggest a small variation in the stopping efficiency as a function of mass, charge and kinetic energy. It is predicted that heavy fragments are stopped about 9% less efficiently than the light fragments. However it was found that the properties of the U, Ni and the He gas influences this behavior. Hence it could be possible to optimize the efficiency.
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| 8. |
- Al-Adili, Ali, et al.
(författare)
-
Neutron-multiplicity experiments for enhanced fission modelling
- 2017
-
Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 9782759890200
-
Konferensbidrag (refereegranskat)abstract
- The nuclear de-excitation process of fission fragments (FF) provides fundamental information for the understanding of nuclear fission and nuclear structure in neutron-rich isotopes. The variation of the prompt-neutron multiplicity, ν(A), as a function of the incident neutron energy (En) is one of many open questions. It leads to significantly different treatments in various fission models and implies that experimental data are analyzed based on contradicting assumptions. One critical question is whether the additional excitation energy (Eexc) is manifested through an increase of ν(A) for all fragments or for the heavy ones only. A systematic investigation of ν(A) as a function of En has been initiated. Correlations between prompt-fission neutrons and fission fragments are obtained by using liquid scintillators in conjunction with a Frisch-grid ionization chamber. The proof-of-principle has been achieved on the reaction 235U(nth,f) at the Van De Graff (VdG) accelerator of the JRC-Geel using a fully digital data acquisition system. Neutrons from 252Cf(sf) were measured separately to quantify the neutron-scattering component due to surrounding shielding material and to determine the intrinsic detector efficiency. Prelimenary results on ν(A) and spectrum in correlation with FF properties are presented.
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| 9. |
- Al-Adili, Ali, et al.
(författare)
-
Simulations of the fission-product stopping efficiency in IGISOL
- 2015
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:59, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- At the Jyväskylä Ion Guide Isotope Separator On-Line (IGISOL) facility, independent fission yields are measured employing the Penning-trap technique. Fission products are produced, e.g. by impinging protons on a uranium target, and are stopped in a gas-filled chamber. The products are collected by a flow of He gas and guided through a mass separator to a Penning trap, where their masses are identified. This work investigates how fission-product properties, such as mass and energy, affect the ion stopping efficiency in the gas cell. The study was performed using the Geant4 toolkit and the SRIM code. The main results show a nearly mass-independent ion stopping with regard to the wide spread of ion masses and energies, with a proper choice of uranium target thickness. Although small variations were observed, in the order of 5%, the results are within the systematic uncertainties of the simulations. To optimize the stopping efficiency while reducing the systematic errors, different experimental parameters were varied; for instance material thicknesses and He gas pressure. Different parameters influence the mass dependence and could alter the mass dependencies in the ion stopping efficiency.
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| 10. |
- Al-Adili, Ali, et al.
(författare)
-
Studying fission neutrons with 2E-2v and 2E
- 2018
-
Ingår i: SCIENTIFIC WORKSHOP ON NUCLEAR FISSION DYNAMICS AND THE EMISSION OF PROMPT NEUTRONS AND GAMMA RAYS (THEORY-4). - : EDP Sciences. - 9782759890316
-
Konferensbidrag (refereegranskat)abstract
- This work aims at measuring prompt-fission neutrons at different excitation energies of the nucleus. Two independent techniques, the 2E-2v and the 2E techniques, are used to map the characteristics of the mass-dependent prompt fission neutron multiplicity, 7(A), when the excitation energy is increased. The VERDI 2E-2v spectrometer is being developed at JRC-GEEL. The Fission Fragment (FF) energies are measured using two arrays of 16 silicon (Si) detectors each. The FFs velocities are obtained by time-of-flight, measured between micro-channel plates (MCP) and Si detectors. With MCPs placed on both sides of the fission source, VERDI allows for independent timing measurements for both fragments. Cf-252(sf) was measured and the present results revealed particular features of the 2E-2v technique. Dedicated simulations were also performed using the GEF code to study important aspects of the 2E-2v technique. Our simulations show that prompt neutron emission has a non-negligible impact on the deduced fragment data and affects also the shape of 17(A). Geometrical constraints lead to a total-kinetic energy-dependent detection efficiency. The 2E technique utilizes an ionization chamber together with two liquid scintillator detectors. Two measurements have been performed, one of Cf-252(sf) and another one of thermal-neutron induced fission in U-235(n,f). Results from Cf-252(sf) are reported here.
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| 11. |
- Alferov, Sergey, et al.
(författare)
-
Electrical communication of cytochrome enriched Escherichia coli JM109 cells with graphite electrodes
- 2009
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 54:22, s. 4979-4984
-
Konferensbidrag (refereegranskat)abstract
- In the present study three different strains of Escherichia coli (JM 109 - a native "wild type" strain, JM 109/pBSD 1300 - a strain overproducing the membrane anchor domain of Bacillus subtilis succinate-quinone reductase, SQR, a protein that contains two transmembraneously arranged heme groups and JM109/pLUV 1900 - a strain overproducing cytochrome c(550) from B. subtilis, a protein where the cytochrome domain is anchored to the membrane with a transmembrane helix) were immobilised on the surface of a spectrographic graphite electrode and tested for electrical communication using mediators. Such compounds as ferricyanide, 2,6-dichlorophenolindophenol (DCPIP) and ubiquinone (Q(0)) were used as soluble mediators and two flexible osmium redox polymers; poly(1-vinylimidazole)(12)-[Os-(4,4'-dimethyl-2,2'-di'pyridyl)(2)Cl-2](2 +/+) (osmium redox polymer I) and poly(vinylpyridine)-[Os-(N,N'-methylated-2,2'-biimidazole)(3)](2+/3+) (osmium redox polymer II) were co-immobilised with the bacterial cells onto the electrode surface. The effects of applied potential, buffer pH and different substrates were compared for the different combinations bacterial strains - mediators. Through the introduction of the cytochromes in the bacterial membrane it was established that it had great effect on the ability of the bacterial cells to effectively communicate with artificial mediators. The introduction of the transmembraneously arranged heme groups of B. subtilis made it possible for this strain to communicate with the Os-polymers, whereas the introduction of the cytochrome c(550) had an effect especially increasing ability of Q(0) to act as an efficient e(-) acceptor. (C) 2009 Elsevier Ltd. All rights reserved.
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| 12. |
- Alhassan, Erwin, et al.
(författare)
-
Combining Total Monte Carlo and Benchmarks for Nuclear Data Uncertainty Propagation on a Lead Fast Reactor's Safety Parameters
- 2014
-
Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 118, s. 542-544
-
Tidskriftsartikel (refereegranskat)abstract
- Analyses are carried out to assess the impact of nuclear data uncertainties on some reactor safety parameters for the European Lead Cooled Training Reactor (ELECTRA) using the Total Monte Carlo method. A large number of Pu-239 random ENDF-format libraries, generated using the TALYS based system were processed into ACE format with NJOY99.336 code and used as input into the Serpent Monte Carlo code to obtain distribution in reactor safety parameters. The distribution in keff obtained was compared with the latest major nuclear data libraries – JEFF-3.1.2, ENDF/B-VII.1 and JENDL-4.0. A method is proposed for the selection of benchmarks for specific applications using the Total Monte Carlo approach based on a correlation observed between the keff of a given system and the benchmark. Finally, an accept/reject criteria was investigated based on chi squared values obtained using the Pu-239 Jezebel criticality benchmark. It was observed that nuclear data uncertainties were reduced considerably from 748 to 443 pcm.
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| 13. |
- Alhassan, Erwin, et al.
(författare)
-
Uncertainty analysis of Lead cross sections on reactor safety for ELECTRA
- 2016
-
Ingår i: SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo. - Les Ulis, France : EDP Sciences.
-
Konferensbidrag (refereegranskat)abstract
- The Total Monte Carlo (TMC) method was used in this study to assess the impact of Pb-206, 207 and 208 nucleardata uncertainties on k-eff , beta-eff, coolant temperature coefficient, the coolant void worth for the ELECTRA reactor. Relatively large uncertainties were observed in the k-eff and the coolant void worth for all the isotopes with significant contribution coming from Pb-208 nuclear data. The large Pb-208 nuclear data uncertainty observed was further investigated by studying the impact of partial channels on the k-eff and beta-eff. Various sections of ENDF file: elasticscattering (n,el), inelastic scattering (n,inl), neutron capture (n,gamma), (n,2n), resonance parameters and the angular distribution were varied randomly and distributions in k-eff and beta-eff obtained. The dominant contributions to the uncertainty in the k-eff from Pb-208 came from uncertainties in the resonance parameters; however, elastic scattering cross section and the angular distribution also had significant impact. The impact of nuclear data uncertainties on the beta-eff was observed to be small.
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| 14. |
- Ameur, Adam, et al.
(författare)
-
Comprehensive profiling of the vaginal microbiome in HIV positive women using massive parallel semiconductor sequencing
- 2014
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 4398-
-
Tidskriftsartikel (refereegranskat)abstract
- Infections by HIV increase the risk of acquiring secondary viral and bacterial infections and methods are needed to determine the spectrum of co-infections for proper treatment. We used rolling circle amplification (RCA) and Ion Proton sequencing to investigate the vaginal microbiome of 20 HIV positive women from South Africa. A total of 46 different human papillomavirus (HPV) types were found, many of which are not detected by existing genotyping assays. Moreover, the complete genomes of two novel HPV types were determined. Abundance of HPV infections was highly correlated with real-time PCR estimates, indicating that the RCA-Proton method can be used for quantification of individual pathogens. We also identified a large number of other viral, bacterial and parasitic co-infections and the spectrum of these co-infections varied widely between individuals. Our method provides rapid detection of a broad range of pathogens and the ability to reconstruct complete genomes of novel infectious agents.
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| 15. |
- Andersson, Pernilla, et al.
(författare)
-
An upgrade of the SCANDAL facility for neutron scattering measurements at 175 MeV
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The experimental setup SCANDAL (SCAttered Nucleon Detection AssembLy) at the The Svedberg Laboratory (TSL), previously used for measurements of the differential cross section of elastic and inelastic neutron scattering in the 50 – 130 MeV range, has recently been upgraded with new Na doped CsI scintillating detectors for measurements at 175 MeV. The performance of the new setup is described and illustrated by the early steps in the analysis of the first experimental campaign, carried out in January and February 2009.
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| 16. |
- Andersson, P., et al.
(författare)
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An upgrade of the SCANDAL setup for measurements of elastic neutron scattering at 175 MeV
- 2010
-
Ingår i: RADIATION MEASUREMENTS. - : Elsevier BV. ; 45:10, s. 1142-1144
-
Konferensbidrag (refereegranskat)abstract
- The experimental setup SCANDAL used for measurements of the differential cross section for elastic and inelastic neutron scattering, has recently been upgraded with larger CsI scintillating detectors to enable measurements at energies up to 175 MeV. Measurements on Fe. Bi and Si have been carried out using the quasi mono-energetic neutron beam at the The Svedberg Laboratory, and data is under analysis. The experimental setup can be used for measurements on a wide range of target nuclei, including C and O, which are important for dosimetry applications. SCANDAL can also run in proton mode, for measurements of the (n,p) reaction. This paper describes the new experimental setup, and reports on its properties, such as energy resolution.
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| 17. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Coincidence spectroscopy for increased sensitivity in radionuclide monitoring
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The majority of the energy in a nuclear explosion is released in the immediate blast and the initial radiation accounts. The remaining fraction is released through radioactive decay of the explosion's fission products and neutron activation products over a longer time span. This allows for the detection of a nuclear explosion by detecting the presence of residual decay. Radionuclide monitoring stations for detection of radioactive emissions to the atmosphere is thereby an important tool in the verification of compliance with nuclear disarmament treaties. In particular, the globally spanning radionuclide station network of the International Monitoring System (IMS) has been implemented for verification of the Comprehensive Nuclear-Test-Ban Treaty.High Purity Germanium (HPGe) detectors are workhorses in radionuclide monitoring. The detection of characteristic gamma rays can be used to disclose the presence of signature nuclides produced innuclear weapon tests. A particular development that has potential to improve the sensitivity of radionuclide monitoring is the coincidence technique where decaying nuclides that emit several coincident gamma rays can be detected at much smaller activity concentrations than with conventional gamma spectroscopy.In this project, dedicated gamma-gamma coincidence detectors are being developed, utilizing electronically segmented HPGe detectors. These detectors are expected to be highly sensitive to low-activity samples of nuclides that present coincident emissions of gamma rays. In this paper we present the concept, define performance parameters, and explore the performance of such detectors to a subset of radionuclides of particular CTBT relevance. In addition, we discuss the path forward in developing a next generation gamma-gamma coincidence spectroscopy system of segmented HPGe.
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| 18. |
- Andersson Sundén, Erik, et al.
(författare)
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Citizen Science and Radioactivity
- 2019
-
Ingår i: Nuclear Physics News. - : Informa UK Limited. - 1050-6896 .- 1061-9127 .- 1931-7336. ; 29:2, s. 25-28
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 19. |
- Beckmann, Cecilia, 1964-
(författare)
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Diversification and strategic, long-distance partnerships : Bofors' struggle through times of crisis and uncertainty
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This is a case study that aims to explain how the company Bofors in Karlskoga, Sweden, struggled through three periods of crisis or uncertainty, while remaining innovative. It begins in the late 19th century and ends in the early 21st century after Bofors had been divested. The investigation takes a constructivist approach and focuses on the experiences of individuals. The data consists of archived letters, interviews and secondary sources. The concept of diversification is applied to explain how Bofors, originally an ironworks acquired new technologies and skills over the years, which were combined in a number of ways, resulting in an innovative local knowledge infrastructure. This development took place while the company sought to adapt to a changing institutional environment – societal norms, rules and practices – following two world wars, disarmament and deindustrialisation. The results also show that, during each of the three periods, Bofors was dependent on long-distance partnerships with external actors to gain new knowledge or financial resources, or both. Different dimensions of proximity are applied, revealing that cognitive proximity was most important for the success of the partnerships. Partners collaborating on innovations had to share a knowledge base. And, preferably, partners’ knowledge should be complementary. But if no proximities were high during the early phase of a partnership, if partners were too far apart from cognitive, geographical, social, institutional and organisational perspectives, then geographical proximity was crucial for increasing the other proximities. To meet face-to-face was necessary in order to learn from each other and to bridge gaps in the relationship caused by partners not knowing each other and belonging to different organisations and cultures with different languages and traditions.
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| 20. |
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| 21. |
- Bevilacqua, Riccardo, et al.
(författare)
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Light-ion Production from O, Si, Fe and Bi Induced by 175 MeV Quasi-monoenergetic Neutrons
- 2014
-
Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. 190-193
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured double-differential cross sections in the interaction of 175 MeV quasimonoenergetic neutrons with O, Si, Fe and Bi. We have compared these results with model calculations with INCL4.5-Abla07, MCNP6 and TALYS-1.2. We have also compared our data with PHITS calculations, where the pre-equilibrium stage of the reaction was accounted respectively using the JENDL/HE-2007 evaluated data library, the quantum molecular dynamics model (QMD) and a modified version of QMD (MQMD) to include a surface coalescence model. The most crucial aspect is the formation and emission of composite particles in the pre-equilibrium stage.
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| 22. |
- Bodin, Theo, et al.
(författare)
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Trends in Precarious Employment in Sweden 1992–2017 : A Social Determinant of Health
- 2022
-
Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 19:19
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify trends in precarious employment in the Swedish workforce from 1992 to 2017. This is a repeated cross-sectional study, analyzing the total working population aged 16–75 in Sweden at five-year intervals. We used version 2.0 of the Swedish Register-based Operationalization of Precarious Employment, covering the following dimensions: employment insecurity, income inadequacy, lack of rights and protection. The proportion in precarious employment increased from 9.7 to 12% between 1992 and 2017, a relative increase of 24%. The prevalence was higher among those of lower age, of low education, and immigrants. Differences between sexes converged, and there were slightly more precarious men than women in 2017. The relative increase was most pronounced among men, especially those with low educational attainment and of European origin. The increasing proportion of precarious employees is a clear challenge to the tripartite Nordic model, which requires sufficient trade-union bargaining power.
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| 23. |
- Branger, Erik, 1988-, et al.
(författare)
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Plutonium Production under Uranium Constraint
- 2023
-
Ingår i: Science and Global Security. - : Routledge. - 0892-9882 .- 1547-7800. ; 31:3, s. 115-136
-
Tidskriftsartikel (refereegranskat)abstract
- Production rates of fissile materials are often used to independently assess the number of nuclear warheads a state may possess. One key constraint of a plutonium-based nuclear weapons program is the availability of natural uranium, where a shortage of uranium will constrain plutonium production in the fuel cycle. Recycling of the reprocessed uranium can be used to mitigate such a shortage. Furthermore, since military reactors operate in short cycles to ensure that the plutonium is weapon-grade, it may be possible to operate them using slightly depleted uranium, provided that there are sufficient reactivity margins. Using slightly depleted or recycled uranium, the plutonium production can increase by a factor 2–5 as compared to a once-through scenario, for the same input of natural uranium. For future assessments of a state’s plutonium production, a uranium constraint should only be considered if there is clear evidence that no nuclear fuel cycle involving uranium recycling is implemented, or if evidence exists that the recycling is insufficient to mitigate the constraint.
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| 24. |
- Burzio, Cecilia, 1991, et al.
(författare)
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Removal of organic micropollutants from municipal wastewater by aerobic granular sludge and conventional activated sludge
- 2022
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 438
-
Tidskriftsartikel (refereegranskat)abstract
- Removal performances of organic micropollutants by conventional activated sludge (CAS) and aerobic granular sludge (AGS) were investigated at a full-scale wastewater treatment plant. Lab-scale kinetic experiments were performed to assess the micropollutant transformation rates under oxic and anoxic conditions. Transformation rates were used to model the micropollutant removal in the full-scale processes. Metagenomic sequencing was used to compare the microbial communities and antimicrobial resistance genes of the CAS and AGS systems. Higher transformation ability was observed for CAS compared to AGS for most compounds, both at the full-scale plant and in the complementary batch experiments. Oxic conditions supported the transformation of several micropollutants with faster and/or comparable rates compared to anoxic conditions. The estimated transformation rates from batch experiments adequately predicted the removal for most micropollutants in the full-scale processes. While the compositions in microbial communities differed between AGS and CAS, the full-scale biological reactors shared similar resistome profiles. Even though granular biomass showed lower potential for micropollutant transformation, AGS systems had somewhat higher gene cluster diversity compared to CAS, which could be related to a higher functional diversity. Micropollutant exposure to biomass or mass transfer limitations, therefore played more important roles in the observed differences in OMP removal.
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| 25. |
- Christenson, Andreas, et al.
(författare)
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Direct and mediated electron transfer between intact succinate:quinone oxidoreductase from Bacillus subtilis and a surface modified gold electrode reveals redox state-dependent conformational changes.
- 2008
-
Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728. ; 1777:9, s. 1203-1210
-
Tidskriftsartikel (refereegranskat)abstract
- Succinate:quinone oxidoreductase (SQR) from Bacillus subtilis consists of two hydrophilic protein subunits comprising succinate dehydrogenase, and a di-heme membrane anchor protein harboring two putative quinone binding sites, Q(p) and Q(d). In this work we have used spectroelectrochemistry to study the electronic communication between purified SQR and a surface modified gold capillary electrode. In the presence of two soluble quinone mediators the midpoint potentials of both hemes were revealed essentially as previously determined by conventional redox titration (heme b(H), E(m)=+65 mV, heme b(L), E(m)=-95 mV). In the absence of mediators the enzyme still communicated with the electrode, albeit with a reproducible hysteresis, resulting in the reduction of both hemes occurring approximately at the midpoint potential of heme b(L), and with a pronounced delay of reoxidation. When the specific inhibitor 2-n-heptyl-4 hydroxyquinoline N-oxide (HQNO), which binds to Q(d) in B. subtilis SQR, was added together with the two quinone mediators, rapid reductive titration was still possible which can be envisioned as an electron transfer occurring via the HQNO insensitive Q(p) site. In contrast, the subsequent oxidative titration was severely hampered in the presence of HQNO, in fact it completely resembled the unmediated reaction. If mediators communicate with Q(p) or Q(d), either event is followed by very rapid electron redistribution within the enzyme. Taken together, this strongly suggests that the accessibility of Q(p) depended on the redox state of the hemes. When both hemes were reduced, and Q(d) was blocked by HQNO, quinone-mediated communication via the Q(p) site was no longer possible, revealing a redox-dependent conformational change in the membrane anchor domain.
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| 26. |
- Coman, Vasile, et al.
(författare)
-
Electrical wiring of live, metabolically enhanced Bacillus subtilis cells with flexible osmium-redox polymers.
- 2009
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 131:44, s. 16171-16176
-
Tidskriftsartikel (refereegranskat)abstract
- The present study explores genetic engineering of the respiratory chain and the application of two different flexible osmium redox polymers to achieve efficient electric communication between the gram-positive organism Bacillus subtilis and an electrode. Poly(1-vinylimidazole)(12)-[Os-(4,4'-dimethyl-2,2'-bipyridyl)(2)Cl(2)](+/2+) (osmium redox polymer I) and poly(vinylpyridine)-[Os-(N,N'-methylated-2,2'-biimidazole)(3)](2+/3+) (osmium redox polymer II) were investigated for efficient electrical "wiring" of viable gram-positive bacterial cells to electrodes. Using a B. subtilis strain that overproduces succinate/quinone oxidoreductase (respiratory complex II), we were able to improve the current response several fold using succinate as substrate, in both batch and flow analysis modes, and using gold and graphite electrodes. The efficiency of the osmium redox polymer, working as electron transfer mediator between the cells and the electrode, was compared with that of a soluble mediator (hexacyanoferrate). The results demonstrated that mediators did not have to pass the cytosolic membrane to bring about an efficient electronic communication between bacterial cells with a thick cell wall and electrodes.
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| 27. |
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| 28. |
- Devarakonda, Sravani, et al.
(författare)
-
Low-grade intestinal inflammation two decades after pelvic radiotherapy.
- 2023
-
Ingår i: EBioMedicine. - 2352-3964. ; 94
-
Tidskriftsartikel (refereegranskat)abstract
- Radiotherapy is effective in the treatment of cancer but also causes damage to non-cancerous tissue. Pelvic radiotherapy may produce chronic and debilitating bowel symptoms, yet the underlying pathophysiology is still undefined. Most notably, although pelvic radiotherapy causes an acute intestinal inflammation there is no consensus on whether the late-phase pathophysiology contains an inflammatory component or not. To address this knowledge gap, we examined the potential presence of a chronic inflammation in mucosal biopsies from irradiated pelvic cancer survivors.We biopsied 24 cancer survivors two to 20 years after pelvic radiotherapy, and four non-irradiated controls. Using tandem mass tag (TMT) mass spectrometry and mRNA sequencing (mRNA-seq), we charted proteomic and transcriptomic profiles of the mucosal tissue previously exposed to a high or a low/no dose of radiation. Changes in the immune cell populations were determined with flow cytometry. The integrity of the protective mucus layers were determined by permeability analysis and 16S rRNA bacterial detection.942 proteins were differentially expressed in mucosa previously exposed to a high radiation dose compared to a low radiation dose. The data suggested a chronic low-grade inflammation with neutrophil activity, which was confirmed by mRNA-seq and flow cytometry and further supported by findings of a weakened mucus barrier with bacterial infiltration.Our results challenge the idea that pelvic radiotherapy causes an acute intestinal inflammation that either heals or turns fibrotic without progression to chronic inflammation. This provides a rationale for exploring novel strategies to mitigate chronic bowel symptoms in pelvic cancer survivors.This study was supported by the King Gustav V Jubilee Clinic Cancer Foundation (CB), The Adlerbertska Research Foundation (CB), The Swedish Cancer Society (GS), The Swedish State under the ALF agreement (GS and CB), Mary von Sydow's foundation (MA and VP).
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| 29. |
- Eilers, Gerriet, et al.
(författare)
-
The Radiocarbon Intracavity Optogalvanic Spectroscopy Setup at Uppsala
- 2013
-
Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222 .- 1945-5755. ; 55:3-4, s. 237-250
-
Tidskriftsartikel (refereegranskat)abstract
- Accelerator mass spectrometry (AMS) is by far the predominant technology deployed for radiocarbon tracer studies. Applications are widespread from archaeology to biological, environmental, and pharmaceutical sciences. In spite of its excellent performance, AMS is expensive and complicated to operate. Consequently, alternative detection techniques for 14C are of great interest, with the vision of a compact, user-friendly, and inexpensive analytical method. Here, we report on the use of intracavity optogalvanic spectroscopy (ICOGS) for measurements of the 14C/12C ratio. This new detection technique was developed by Murnick et al. (2008). In the infrared (IR) region, CO2 molecules have strong absorption coefficients. The IR-absorption lines are narrow in line width and shifted for different carbon isotopes. These properties can potentially be exploited to detect 14CO2, 13CO2, or 12CO2 molecules unambiguously. In ICOGS, the sample is in the form of CO2 gas, eliminating the graphitization step that h is required in most AMS labs. The status of the ICOGS setup in Uppsala is presented. The system is operational but not yet fully developed. Data are presented for initial results that illustrate the dependence of the optogalvanic signal on various parameters, such as background and plasma-induced changes in the sample gas composition.
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| 30. |
- Ekholm, Jennifer, 1992, et al.
(författare)
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Influence of decreasing temperature on aerobic granular sludge - microbial community dynamics and treatment performance
- 2024
-
Ingår i: Bioresource Technology Reports. - 2589-014X. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater in temperate climates is characterized by seasonal temperature changes. Temperature is a determining factor for biological processes, but the impact of gradually decreasing temperature on aerobic granular sludge (AGS) has been largely unexplored. In this study, the influence of decreasing temperature from 20 °C to 6 °C on AGS was investigated at rates of 0.5 and 1 °C per week. Temperature was a major driver for microbial community change, where the community response could be divided into three main subclusters. Strains within the guilds of ammonium- and nitrite-oxidising bacteria (AOB and NOB) as well as polyphosphate- and glycogen-accumulating organisms (PAOs and GAOs) grouped in different subclusters, indicating variable responses among and between the guilds. The phosphorous removal rate was sufficient for complete removal at all temperatures, presumably due to functional redundancy within the PAOs. The nitrification rate was, however, seriously impaired below 13 °C, despite diversity within AOB and NOB.
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| 31. |
- Ekqvist, Susanne, et al.
(författare)
-
High frequency of contact allergy to gold in patients with endovascular coronary stents
- 2007
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Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963. ; 157:4, s. 730-738
-
Tidskriftsartikel (refereegranskat)abstract
- Background Stent implantation is an effective method for treatment of atherosclerotic disease. Factors predisposing to in-stent restenosis are still largely unknown. Contact allergy to metal ions eluted from the stent has been suggested to be a risk factor. Objectives To explore whether there is a possible induction of contact allergy to metals used in stents among patients with a stainless steel stent containing nickel (Ni stent) and patients with a gold-plated stent (Au stent). Methods Adults (n = 484) treated with coronary stent implantation participated in the study with patch testing. The study design was retrospective and cross-sectional with no assessment of contact allergy before stenting. Age- and sex-matched patch-tested patients with dermatitis (n = 447) served as controls. Results Of Au-stented patients, 54 of 146 (37%) were allergic to gold compared with 85 of 447 (19%) controls (P < 0.001). Within the stented population there were no statistically significant differences in contact allergy to gold or nickel between Ni-stented and Au-stented patients. In multivariate models where other risk factors for contact allergy to gold were considered, the Au stent showed a trend towards statistical significance (odds ratio 1.43, 95% confidence interval 0.95-2.16; P = 0.09). Conclusions As the frequency of contact allergy to gold is higher in stented patients independent of stent type it suggests a previous sensitization. However, several pieces of circumstantial evidence as well as statistical analysis indicate the possibility of sensitization in the coronary vessel by the Au stent. Ni stents and Au stents should not be ruled out as risk factors for induction of contact allergy to these metals.
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| 32. |
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| 33. |
- Grape, Sophie, 1982-, et al.
(författare)
-
Development of a PhD course in verification of nuclear test explosions under AMC
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Under the AMC, a range of activities covering education, research and outreach are foreseen. One of them concerns education and the build-up of competence related to disarmament, and for that reason collaborative efforts have been ongoing during 2021 and 2022 to develop a PhD-level course in verification of nuclear test explosions, and to offer it during September-October 2022. The course has developed by Uppsala University and the Swedish Defence Reserach Agency (FOI) and corresponds to 7.5 credits. It is a cross-disciplinary course that spans over several disciplines. It introduces the participants to treaties and verification regimes governing nuclear weapons and it explains identification, calculation and analysis of signatures from nuclear weapon explosions. Furthermore, effort has been made to let the participants actively work with data collection, aggregation, analysis and with the interpretation and evaluation of data. The course includes also both a laboratory exercise on detection of radionuclides, and a project work in which the participants analyze a test explosion scenario and summarize their findings and conclusions in a manner very similar to how this is done in reality.This poster will describe the details of the course and its content. Since the course is planned to be offered just before this conference, we also hope to provide some information on its execution, as well as feedback from the participants.
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| 34. |
- Grape, Sophie, 1982-, et al.
(författare)
-
Non-proliferation and safeguards activities within the Alva Myrdal Centre for nuclear disarmament
- 2022
-
Ingår i: Proceedings of the Symposium on International Safeguards: Reflecting on the Past and Anticipating the Future.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In 2020, the Swedish government announced the intent to start up a national competence centre on nuclear disarmament in Sweden. The goal was to highlight the importance of nuclear disarmament issues, and to promote research, teaching and policy support on topics relevant to nuclear disarmament. During the spring semester 2021, the Alva Myrdal Centre (AMC) on nuclear disarmament was established at Uppsala University. The AMC combines competences from different disciplines such as peace and conflict research, applied nuclear physics, and international law, and organises the work into six different working groups. One of the working groups is focusing on technical aspects, while the remaining five working groups are focusing on policy aspects. The technical working group is led by the Division of Applied Nuclear Physics at Uppsala University, where research on nuclear safeguards has been performed for over 30 years, and where competence in addition exists on a number of applied physics applications ranging from nuclear reactions, nuclear power and detection of radionuclides.
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| 35. |
- Grape, Sophie, 1982-, et al.
(författare)
-
Retrieving information about the Ågesta reactor in Sweden
- 2023
-
Ingår i: AMC Annual conference 2023, 14-15 June, 2023.
-
Konferensbidrag (populärvet., debatt m.m.)abstract
- The “Swedish line” was an ambitious program in the 1950s-1960s aiming to make Sweden self-sufficient with respect to nuclear technology. The plan was to combine civil power production with military plutonium production, should Sweden decide to develop nuclear weapons. The program included, among other things, domestic uranium mining, domestic uranium fuel production, operation of heavy-water reactors and a plutonium laboratory. The Ågesta nuclear power plant just outside Stockholm was part of the program. The reactor, also known as R3/Adam, was in operation in 1964-1974. The reactor was an underground, heavy-water cooled and heavy-water moderated pressurized reactor, providing district heat and a modest amount of electricity to the near-by suburb Farsta. After being closed down, the heavy water was sold to Canada while the fuel and some other equipment were removed. Large parts of the facility were preserved for several decades, but is now undergoing decommissioning, a process which is planned to be finalised in 2025. Within this project we are investigating how to locate and reconstruct historic information on the operation of the Ågesta reactor. Of particular interest is the nuclear fuel and its irradiation history in the reactor. There are many reasons for this: i) information and knowledge management about the operation of a nuclear facility under the “Swedish line”, ii) for assessments regarding to the produced plutonium qualities and quantities and iii) for nuclear safeguards verification of Ågesta fuel before encapsulation and final storage. For operating reactors, information about the fuel and its irradiation in the reactor is typically kept with the operator and follows the fuel as it undergoes transport and spent fuel management. In this case, the information is not straightforward to access, as the information has been distributed among multiple actors, and because custody of various parts of the information has changed over time. In this poster we will describe efforts to retrieve the detailed technical information, results thereof, and the plans for using it to support research related to the topics mentioned above.
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| 36. |
- Grape, Sophie, 1982-
(författare)
-
Simulating submarine reactor fuel in light of the AUKUS deal
- 2023
-
Ingår i: ESARDA Bulletin - The International Journal of Nuclear Safeguards and Non-proliferation. - Ispra, Italy. - 1977-5296. ; 65, s. 34-43
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigates fuel properties of submarine reactor fuel from a non-proliferation and safeguards perspective in light of the deal involving Australia, the United Kingdom and United States known as AUKUS. This study investigates the isotopic composition of the spent fuel at the end of intended reactor life. The fuel in the proposed AUKUS submarine is modelled after a Virginia Class fast attack submarine, discussed as an option for Australia.The vast majority of civil experience with plutonium production is with fuel starting at low enrichments for shorter burnups. The AUKUS fuel at the start of irradiation campaign is assumed to contain uranium enriched to between 93% and 97,3%. It is burned at high power for about 33 years before retirement. Because the fuel is mostly uranium-235 initially, there are very few thermal captures leading to production of plutonium-239. In the submarine, the majority of non-fissile captures lead to the production of uranium-236 with other capture chains that do not lead to the production of weapons grade plutonium or weapons usable uranium.This study concludes that the final isotopic composition of the AUKUS spent fuel is no longer VHEU, but a low grade of HEU diluted largely by uranium-236 instead of uranium-238. Several kilograms of plutonium are produced but it is composed of several different plutonium isotopes with a large fraction of plutonium-238. There is little likelihood that spent AUKUS fuel will be reprocessed by any of the countries involved. But if it were reprocessed, the resulting uranium and plutonium will have very unusual isotope compositions. Resulting materials would be subject to safeguards but would not, in fact, be well-suited as fissile material for weapons purposes.
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| 37. |
- Grape, Sophie, 1982-, et al.
(författare)
-
State-of-the-Art Report : Prepared by Working Group 4: Technical nuclear non-proliferation and safeguards under the Alva Myrdal Centre for nuclear disarmament
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Alva Myrdal Centre for nuclear disarmament (AMC) was established in 2021. AMC consists of six working Groups, and one of them - Working Group 4 - is called Technical nuclear non-proliferation and safeguards. This is the State-of-the-Art Report of that working group. The objective with the report is to provide an overview of the technical fields relevant to the working group and to highlight where research and activities within the working group may contribute to global nuclear disarmament. The report gives a brief explanation of actors in the field, introduces nuclear materials and assay techniques, and then continues to elaborate on challenges and needs associated with nuclear measurements and assessments in the fields of non-proliferation, nuclear safeguards and nuclear disarmament. A section is also devoted to the management of nuclear weapons materials after disarmament. Lastly, the report contains a section on interdisciplinary research and development in nuclear disarmament, and information about technical education and training in the non-proliferation and disarmament field.
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| 38. |
- Grape, Sophie, 1982-, et al.
(författare)
-
Studies of naval reactor core properties in light of recent AUKUS developments
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As a result of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the International Atomic Energy Agency conducts nuclear safeguards verification to ensure accurate accounting for and control of nuclear materials in states. Experts have highlighted a loophole in the NPT, whereby safeguarded nuclear material could be removed and used for military applications such as naval propulsion purposes. The loophole is exemplified by the announcement by the AUKUS security pact that the United Kingdom and United States will help Australia acquire nuclear-powered submarines. Naval reactors have so-far only been operated by nuclear-weapon states and non-signatories to the NPT. This situation puts various nuclear non-proliferation issues in the spotlight. The main concern is that Australia, a non-nuclear weapon state, may set a precedent to remove nuclear material from its civil nuclear fuel cycle; an act that could inspire non-nuclear weapon states to use naval propulsion programs as a cover to develop nuclear weapons.As a first step in addressing these concerns, we have been studying naval reactor cores and their properties and that work will be presented here. Openly available information has been used to create a model of a naval reactor core and its fuel. The model has been implemented in the Monte Carlo code Serpent2, in which also the operation of the reactor has been modelled. The objective is to study the evolution of the fuel material composition over time and to make an assessment of how useful the material is for nuclear weapon production.
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| 39. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(författare)
-
A technical view on Pakistan's nuclear weapons programme
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Pakistan performed at least two nuclear weapons tests in 1998 as a direct response to the Indian nuclear tests earlier the same year. With this act, Pakistan became the seventh country to successfully complete a nuclear weapons programme. The Pakistani nuclear weapons arsenal consists of both uranium and plutonium weapons and the country has an extensive nuclear industry with all facilities necessary for enrichment of uranium, production of plutonium and reprocessing of spent reactor fuel.Pakistan acquired a Canadian civil heavy water nuclear reactor in 1971; KANUPP-1. In 1976 however, the cooperation with Canada ended as Canada stopped supplying fuel for the reactor. At this point, Pakistan had acquired know-how and experience to manufacture its own fuel and also started building an independent nuclear industry with several unsafeguarded reactors at the Khushab site. With French assistance, a reprocessing plant was constructed and consequently, Pakistan is today in possession of all components necessary for developing and employing both uranium and plutonium nuclear devices. In this presentation, we will explore technical challenges associated with bringing a country such as Pakistan under the existing or proposed treaty verification following treaties such as the NPT, TPNW and FMCT. Using a simulation framework and estimates based on known physical quantities and derived abilities, we will discuss what conclusions can be drawn with regards to uranium and plutonium stockpiles.
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| 40. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(författare)
-
Assessments of design and operational parameter sensitivity towards plutonium production in heavy water reactors
- 2023
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A majority of the nuclear reactors in the world use low-enriched uranium as fuel, and will produce plutonium during operation. This will happen when neutrons undergo capture in U238 instead of causing fission of U235, which is a likely reaction as low-enriched uranium is composed of >95% U238. While the plutonium can be used as fuel in the reactor, it is also a material highly desired by states producing nuclear weapons. Not all reactors produce plutonium of the same grade, which significantly impacts its usability in a nuclear weapon. For this reason, certain reactor technologies have been favored for military plutonium production. Heavy-water moderated reactors is one such family, that has been used in current or defunct nuclear weapons programmes by states such as India, Pakistan, Sweden, Switzerland and the United States.A number of factors impact the rate and grade of plutonium production in a reactor. These include(but are not limited to) fuel design specifications (pellet radius, fuel density), operational temperature of the fuel as well as the coolant and moderator, and numerous other operational parameters such as specific power, cycle lengths and downtimes et cetera. The present study will look into investigating the relative sensitivity of plutonium production rate and grade towards these design and operational parameters. Based on the results from this evaluation, it is expected that we can better understand which parameters impact plutonium production quantity and quality the most. This will also help us understand the role and impact of uncertainties in these parameters and connect them to the plutonium content in the spent fuel produced by these reactors
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| 41. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(författare)
-
Citizen science in radiation research
- 2020
-
Ingår i: ND 2019. - : EDP Sciences. - 9782759891061
-
Konferensbidrag (refereegranskat)abstract
- A growing trend in science is that research institutions reach out to members of the public for participating in research. The reasons for outreach are many, spanning from the desire to collect and/or analyse large sets of data efficiently, to the idea of including the general public on a very fundamental level in science-making and ultimately decision-making. The presented project is curriculum-based and carried out in 240 lower secondary school classes (pupils of age 13-16). The task, as designed by the participating universities, is to collect mushrooms, soil and animal droppings from different parts of Sweden, do preliminary sample preparation and analyses and send the samples to the university institutions for radioactivity measurement. Behind the project is a desire to compare today’s levels of 137Cs with those deposited right after the Chernobyl accident in 1986, but also to study the exchange of caesium between organisms as well as the impacts of biological and geological processes on uptake and retention. The scientific outcome is a geodatabase with the 137Cs activity (Bq/m2) present in the Swedish environment, where radioactivity data can be linked to the species (fungi, competing species, animals foraging), forest type, land type, land use and other environmental factors. The science question is of interest to the general public as foraging for mushrooms, as well as spending recreational time in forests is widely popular in Sweden. In this article, we will discuss the current status of the project and the observations we have made about how well the public can participate in scientific research. Focus will be on organization of the project, such as logistics, preparation of supportive material, feedback and communication between researchers and schools. We will present observations about the impact the project has had on the participants, based on quantitative and qualitative evaluations.
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| 42. |
- Gustavsson, Cecilia, 1973-, et al.
(författare)
-
Comparison of the physical and operational parameters of the CANDU reactor and the NRX reactor
- 2023
-
Ingår i: AMC Annual conference 2023, 14-15 June, 2023, 2023. - Uppsala.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several historic and current nuclear weapons programs are based on heavy-water moderated reactors for plutonium production. While details about the military reactors is scarce, much more information exist on civilian heavy-water moderated reactors. The CANDU reactor is the most developed one, and there is much openly available design and operation data that can be used to simulate it. The CANDU design uses heavy water for moderation and cooling together with low-enriched uranium fuel which is frequently refueled. This reactor type is not optimized for military plutonium production, but is on the contrary extensively used in civil energy production.It has never been unambiguously proven that a CANDU reactor has been used for producing plutonium for nuclear weapons. In the case of both India and Pakistan, another type of reactor is believed to have been used to manufacture plutonium. This type is based on the NRX (National Research Experimental) reactor at Chalk River Laboratories in Canada, a predecessor of the CANDU reactor. The NRX was moderated by heavy water but cooled by light water. It used natural metal uranium as fuel and was for a time the most powerful research reactor in the world. NRX was in operation between 1947 to 1993, and suffered a partial meltdown accident in 1952, which led to a substantial development in reactor safety. In this poster we are comparing the CANDU and NRX designs and discuss how the fuel handling and operation differ. The results of our simulations allow comparison of parameters such as plutonium production, the plutonium vector, throughput, and can be used for further work to assess the production at military reactors of an unknown design. The objective of this work is to gain a better estimate of the plutonium production at the reactors at Khushab in Pakistan.
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| 43. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(författare)
-
CTBT and SAUNA : Presentation for the Division for Applied Nuclear Physics
- 2021
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Comprehensive Test Ban Treaty (CTBT) bans all kinds of nuclear weapons tests; in the atmosphere, on land, in the oceans and underground. It was opened for signature in 1996 and even though it has not yet entered into force, it is an important international tool for preventing proliferation of nuclear weapons. In this talk, we will give a background to the treaty as well as on the monitoring system that upholds compliance with it. We will especially focus on the system for detecting Xenon developed in Sweden - SAUNA - and describe its place in the monitoring network as well as its function and development.
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| 44. |
- Gustavsson, Cecilia, et al.
(författare)
-
Engineering physics students' conceptions of entropy
- 2013
-
Ingår i: 4:e UTVECKLINGSKONFERENSEN FÖR SVERIGES INGENJÖRSUTBILDNINGAR. - Umeå : Tekniska högskolan, Umeå universitet. ; , s. 57-59
-
Konferensbidrag (refereegranskat)
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| 45. |
- Gustavsson, Cecilia, et al.
(författare)
-
Inelastic neutron scattering from carbon, iron, yttrium and lead
- 2012
-
Ingår i: CNR*11. - : EDP Sciences. ; , s. 03004-
-
Konferensbidrag (refereegranskat)abstract
- Double-differential cross sections and angular distributions of inelastic neutron scattering on C-12, Fe-56, Y-89 and Pb-208 have been measured at 96 MeV at The Svedberg Laboratory, Uppsala, Sweden. Results on elastic neutron scattering at 96 MeV from these nuclei have been reported previously [1-3]. To obtain the inelastic cross sections, a forward-folding technique has been applied. A physically reasonable trial spectrum has been folded with the response function of the detector system and the output has been compared with the experimental data. To create the trial spectrum, a Gaussian has been used for the elastic part and the PRECO code [4-7] for the inelastic part. Other models were tested for the pre-equilibrium contribution and the method was found to be model independent. The response function of the detector setup has been obtained experimentally at the smallest possible angle, in this case at 9 deg. The resulting preliminary inelastic scattering data cover an excitation energy range up to 45 MeV and the angular intervals 28 to 58 degrees for C-12, 26 to 65 degrees for Fe-56 and 26 to 52 degrees for Y-89 and Pb-208. The preliminary results are discussed and compared to several model codes as well as existing experimental data for (n,n'x), (n,p'x) and (p,p'x). Possible improvements of the analysis are also discussed.
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| 46. |
- Gustavsson, Cecilia, et al.
(författare)
-
Nuclear data measurements at the new NFS facility at GANIL
- 2012
-
Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; 2012:T150, s. 014017-
-
Tidskriftsartikel (refereegranskat)abstract
- The NFS (Neutrons For Science) facility is part of the SPRIAL 2 project at GANIL, Caen, France. The facility is currently under construction and the first beam is expected in early 2013. NFS will have a white neutron source covering the 1–40 MeV energy range with a neutron flux higher than comparable facilities. A quasi-mono-energetic neutron beam will also be available. In these energy ranges, especially above 14 MeV, there is a large demand for neutron-induced data for a wide range of applications involving dosimetry, medical therapy, single-event upsets in electronics and nuclear energy. Today, there are a few or no cross section data on reactions such as (n, fission), (n, xn), (n, p), (n, d) and (n, α ). We propose to install experimental equipment for measuring neutron-induced light-charged particle production and fission relative to the H(n, p) cross section. Both the H(n, p) cross section and the fission cross section for 238 U are important reference cross sections used as standards for many other experiments. Nuclear data for certain key elements, such as closed shell nuclei, are also of relevance for the development of nuclear reaction models. Our primary intention is to measure charged particle production (protons, deuterons and alphas) from 12 C, 16 O, 28 Si and 56 Fe and neutron-induced fission cross sections from 238 U and 232 Th.
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| 47. |
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| 48. |
- Gustavsson, Cecilia, et al.
(författare)
-
Status Report on the Analysis of Inelastic Neutron Scattering from Carbon, Iron, Yttrium and Lead at 96 MeV
- 2014
-
Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 0090-3752 .- 1095-9904. ; 119, s. 183-185
-
Tidskriftsartikel (refereegranskat)abstract
- This work is part of an effort to provide more experimental data for the (n,n'x) reaction. The experiments were carried out at The Svedberg Laboratory in Uppsala, Sweden, at the quasi-monoenergetic neutron beam of 96 MeV, before the facility was upgraded in 2004. Using an extended data analysis of data primarily intended for measuring elastic neutron scattering only, it was found to be possible to extract information on the inelastic scattering from several nuclei. In the preliminary data analysis, an iterative forward-folding technique was applied, in which a physically reasonable trial spectrum was folded with the response function of the detector system and the output was compared to the experimental data. As a result, double-differential cross sections and angular distributions of inelastic neutron scattering from C-12, Fe-56, Y-89 and Pb-208 could be obtained. In this paper, a status update on the efforts to improve the description of the detector response function is given.
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| 49. |
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| 50. |
- Gustavsson, Emil, 1987, et al.
(författare)
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Modulation of Structural Heterogeneity Controls Phytochrome Photoswitching
- 2020
-
Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 118:2, s. 415-421
-
Tidskriftsartikel (refereegranskat)abstract
- Phytochromes sense red/far-red light and control many biological processes in plants, fungi, and bacteria. Although the crystal structures of dark- and light-adapted states have been determined, the molecular mechanisms underlying photoactivation remain elusive. Here, we demonstrate that the conserved tongue region of the PHY domain of a 57-kDa photosensory module of Deinococcus radiodurans phytochrome changes from a structurally heterogeneous dark state to an ordered, light-activated state. The results were obtained in solution by utilizing a laser-triggered activation approach detected on the atomic level with high-resolution protein NMR spectroscopy. The data suggest that photosignaling of phytochromes relies on careful modulation of structural heterogeneity of the PHY tongue.
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