| 1. |
- Baskaran, Sathishkumar, et al.
(författare)
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Primary glioblastoma cells for precision medicine : a quantitative portrait of genomic (in)stability during the first 30 passages
- 2018
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Ingår i: Neuro-Oncology. - : OXFORD UNIV PRESS INC. - 1522-8517 .- 1523-5866. ; 20:8, s. 1080-1091
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Tidskriftsartikel (refereegranskat)abstract
- Background: Primary glioblastoma cell (GC) cultures have emerged as a key model in brain tumor research, with the potential to uncover patient-specific differences in therapy response. However, there is limited quantitative information about the stability of such cells during the initial 20-30 passages of culture.Methods: We interrogated 3 patient-derived GC cultures at dense time intervals during the first 30 passages of culture. Combining state-of-the-art signal processing methods with a mathematical model of growth, we estimated clonal composition, rates of change, affected pathways, and correlations between altered gene dosage and transcription.Results: We demonstrate that GC cultures undergo sequential clonal takeovers, observed through variable proportions of specific subchromosomal lesions, variations in aneuploid cell content, and variations in subpopulation cell cycling times. The GC cultures also show significant transcriptional drift in several metabolic and signaling pathways, including ribosomal synthesis, telomere packaging and signaling via the mammalian target of rapamycin, Wnt, and interferon pathways, to a high degree explained by changes in gene dosage. In addition to these adaptations, the cultured GCs showed signs of shifting transcriptional subtype. Compared with chromosomal aberrations and gene expression, DNA methylations remained comparatively stable during passaging, and may be favorable as a biomarker.Conclusion: Taken together, GC cultures undergo significant genomic and transcriptional changes that need to be considered in functional experiments and biomarker studies that involve primary glioblastoma cells.
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| 2. |
- Bergfeldt, Lennart, 1950, et al.
(författare)
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Spatial peak and mean QRS-T angles: A comparison of similar but different emerging risk factors for cardiac death.
- 2020
-
Ingår i: Journal of electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 61, s. 112-120
-
Tidskriftsartikel (refereegranskat)abstract
- The spatial peak and mean QRS-T angles are scientifically but not clinically established risk factors for cardiovascular events including cardiac death. The study aims were to compare these angles, assess their association with hypertension (HT) and diabetes mellitus (DM), and explore the relation between the mean QRS-T angle and the ventricular gradient (VG; reflecting electrical heterogeneity), which both are derived from the QRSarea and Tarea vectors.Altogether 1094 participants (aged 50-65years, 550 women) from the pilot of the population-based Swedish CArdioPulmonary bioImage Study with Frank vectorcardiographic recordings were included and divided into 5 subgroups: apparently healthy n=320; HT n=311; DM n=33; DM+HT n=53; miscellaneous conditions n=377. Abnormal peak and mean QRS-T angles were defined as >95th percentile.Peak QRS-T angles were generally narrower than the mean QRS-T angles; both were narrower in women than in men. Abnormal peak (>124°) and/or mean (>119°) QRS-T angles were found in 73 participants (6.7%). The concordance regarding abnormal versus normal-borderline QRS-T angles was good (Cohen's kappa 0.61). The prevalence of abnormal angles varied from 2.5% in healthy to 21.2% in DM. There was an inverse logarithmical relation between the mean QRS-T angle and the VG.The peak and mean QRS-T angles are not interchangeable but complementary. DM, HT, sex and absence of disease are important determinants of both QRS-T angles. The mean QRS-T angle and the VG relationship is complex. All three VCG derived measures reflect related but differing electrophysiological properties and have potential prognostic value vis-à-vis cardiovascular events.
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| 3. |
- Bergström, Christel, 1973-, et al.
(författare)
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Computational absorption prediction
- 2008. - 2., completely revised edition
-
Ingår i: Drug bioavailability. - Wernheim : Wiley-VCH. - 9783527320516 ; , s. 409-432
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Bergström, Markus
(författare)
-
Assessment of existing concrete bridges : bending stiffness as a performance indicator
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optimizing the use of existing civil reinforced concrete (RC) structures could be interpreted in such a way as to say that the capacity should be used and taken care of in an effective manner, both from a technical and economical point of view, keeping the safety in mind. Achieving this requires thorough understanding of the structure and also of the tools used for assessing current and future capacity and needs. Monitoring together with finite element modelling could give relevant and important information about a structure's capacity. In a case where monitoring alone is used, it is beneficial if a quantity is monitored which is interpretable on material and geometrical level. It is further important that the measure is practically possible to capture, and that it reflects the behaviour in a theoretically well-known mode. One example of a quantity which fulfils these requirements is the bending stiffness. In the Serviceability Limit State (SLS), in particular, a high bending stiffness is beneficial as this reduces deflections, vibration amplitudes and crack widths.It is shown within the thesis that four phases are distinguished during loading of an RC member; Un-cracked phase (I), Crack forming phase (II), Crack stabilised phase (III) and Failure phase (IV). It is also shown that corrosion and flexural strengthening are possible to capture through the bending stiffness by monitoring the curvature. Linear elastic theory has in addition been concluded to give satisfactory results in terms of good agreement between measured and theoretical results. It is shown that it is possible to determine the highest load which the structure has been previously exposed to, presuming that the structural element has not reached phase (III). The stiffness is almost constant in phase (III) which implies that it is the same for a certain load interval. One limitation coupled to the stiffness plateau formed in phase (III) is that it is difficult to predict a possible failure by monitoring the bending stiffness, caused by the limited forewarning prior to the beginning of phase (IV). Other tools, such as reliability-based assessment, become especially important here since active degradation, for example, is difficul to verify by curvature measurements in phase (III). Estimating the safety, and also finding the probable failure mode is important since curvature measurement is not effective in the Ultimate Limit States (ULS) and only captures the behaviour in bending. In the reliability-based assessment, the agreement between analytical results and actual capacity of the particular failure mode must be treated with special attention, since it has been shown that the model uncertainty can affect both the safety level and also probable failure mode. If it can be shown from monitoring that the structure is located within phase (I) the load effect during the past time has not affected the integrity of the structure in terms of bending cracks.It is preferrable to use the global curvature when evaluating the bending stiffness, since this property gives a more robust average curvature and also additional information about the structural member. Especially changing bond properties, during e.g. corrosion, is more likely to be detected if the global curvature is monitored. Another important conclusion is that the local and global stiffness development is very similar. This implies that a crack at a certain location is not allowed to increase without redistribution of stresses, which affects the global stiffness in an comparable extent. Two criteria are suggested for the least distance over which the global curvature should be measured, LG. The first one concerns the fact that at least four macro cracks is suggested to be covered and is based on the maximum crack spacing recommended by Eurocode (2004). The other requirement is that the distance should not be that small that the estimated deflection become less than one hundred times the in-built measurement error in the displacement gauge. A measurement error above one percent is hence not allowed.Curvature assessment could be useful from three different aspects * Condition assessment. The monitored quantity is back-calculated to input data, such as material property or geometry. That is, solving the inverse bridge management problem. Decisions about the use of the structure are then based on the outcome of this assessment.* Refined calculations in serviceability and ultimate limit states. Use the results to refine the models used for SLS and ULS performance. For example, it might be possible to treat the structure in its actual condition. * Optimized LCC. Time until a major repair and/or strengthening procedure is estimated using the bending stiffness development captured by curvature measurement.The approach using bending stiffness as a performance indicator is applied in two case studies in Sweden, the Panken road bridge located east of Karlstad and the railway bridge located in Örnsköldsvik. The Panken Bridge was located within phase (III) (crack stabilised phase), while the Örnsköldsviks Bridge was located within phase (I) (un-cracked phase). It is shown in these case studies that monitoring of the bending stiffness through curvature measurements can give valuable information regarding how the structure is affected by loads and/or degradation. One challenge when evaluating the bending stiffness from curvature measurements is that time dependent mechanisms, e.g. creep, could affect the curvature but not necessarily the bending stiffness. Time dependent mechanisms will thus give rise to what is here defined as a "fictitious stiffness change". Any movement or deformation which produces a fictitious stiffness change must be given extra attention to avoid misleading results. Another challenge is that monitoring is commonly performed for additional loading, which means that the curvature caused by the dead weight of the structure itself is in most cases not captured. Further research is suggested to address the effects of these phenomena for curvature assessment applications.
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| 5. |
- Bergström, Markus
(författare)
-
Bro över Järpströmmen : mätning av påkänningar före och efter förstärkning
- 2004
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En trespannsbro över Järpströmmen förstärktes med avseende på tvärkraftskapacitet med kolfiberväv. Förstärkningen genomfördes under sommaren 2004. För att utröna effekten av förstärkning har mätning utförts såväl före som efter ingreppet. Föreliggande rapport redovisar mätprogram samt sammanställande mätresultat. Resultatet från mätningen visar att påkänningarna är mycket små och att det är svårt, med den belastningsnivå som valdes, att påvisa någon säkerställd skillnad före och efter förstärkning. Det är dock fastställt att förstärkningen är aktiv och tar last, och kan därför förutsättas bidra till en ökad kapacitet i brottgränstillstånd trots att effekterna är svåra att bestyrka i brukgränstillstånd och utförd mätning.
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| 6. |
- Bergström, Markus, et al.
(författare)
-
Bro över Järpströmmen : kompletterande mätning av påkänningar vid tung överfart
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Kompletterande mätning på bron över Järpströmmen genomfördes då lasten vid föregående mätning ansågs för liten. Vid aktuell mätning bestod lasten av ett transportekipage med en totalvikt på cirka 400 ton fördelat på 20 hjulaxlar och en bit över 100 däck. Mycket låg påkänning i kolfibermaterial och stålarmering, i storleksordningen omkring 5 m/m. Den låga påkänningen härleds inte till en för låg last, då ekipagets tyngd är stor. Däremot kan mätresultaten förklaras i att tvärkraftsarmeringen och förstärkningen inte tar last förrän uppsprickning av brobetongen inträffar. Betongbrons spricklast förutsätts inte vara uppnådd vid aktuell lastnivå, vilket förklarar de små töjningarna på armering och kolfiber. Detta resonemang baseras på genomförda försök (Carolin, 2003). Erfarenhetsmässigt är tvärkraftsförstärkning med kolfiberlaminat en fungerande och effektiv metod för att uppgradera en konstruktion. Kolfiberförstärkningen har konsekvent en töjning omkring 5 με vid överfart, vilket visar att förstärkningen tar last och därmed fungerar. Ingen tendens av vidhäftningsproblem finns vid aktuell lastnivå, vilket stöds av att armeringen och kolfibermaterialet töjs lika mycket. Detta betyder att förstärkningen fortsätter ta mer last vid ökad belastning. Förstärkningen kan därför förutsättas bidra till en ökad kapacitet i brottgränstillstånd, då uppsprickning av betong inträffar, trots att effekterna är svåra att bestyrka i bruksgränstillstånd och utförd mätning.
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| 7. |
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| 8. |
- Bergström, Markus
(författare)
-
Chair with three legs
- 2017
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Ingår i: Etage Projects gallery, Copenhagen.
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
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| 9. |
- Bergström, Markus, et al.
(författare)
-
Degradation of structural performance : Experiment introduction and expected results
- 2006
-
Ingår i: Bridge maintenance, safety, management, life-cycle performance and cost. - London : Taylor & Francis Group. - 0415403154 - 9780415403153 ; , s. 251-252
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Much effort has been put on investigating degradation of concrete structures, repair and upgrading separately, as can be read in numerous publications, i.e., Green et. al. (2003), Morgan (1995) and Täljsten (2004). However, an overall view has not been taken where the whole life cycle of a concrete structure is considered. In particular, no laboratory tests have been presented in the literature to the author's knowledge. A structure passes several stages during its life. Normally two major stages are discerned, the service limit state (SLS) and the ultimate limit state (ULS). Concrete structures are designed for both these stages. In the SLS normally the deformation and crack widths are controlled. Deformation due to comfort demands and crack widths due to durability demands. In the ULS the structure is designed for its ultimate capacity - which for civil and building structures almost never is reached. From a safety aspect the ULS is most important; however, for the client the SLS with regard to maintenance, repair and upgrading are most costly. If the SLS was better understood, in particular from a rehabilitation point of view, more robust and cost effective repair and upgrading system could be developed. (Figure Presented). This paper is also a part of "Sustainable bridges". "Sustainable bridges" is a European project which focus is to preserve bridges throughout Europe and create unanimous codes for all participating countries. The project presented in this paper, Degradation of Structural Performance (DOSP), will investigate the behaviour of concrete beams which will endure a simulated life cycle procedure. The test program will direct the beams from full strength of the intact beam through degradation, repair and upgrading with FRP plate bonding to its original strength again or near. The cross-sectional strain distribution will be monitored during the test using Fibre Bragg Grating (FBG) Strain Sensors as well as traditional strain gauges. This gives the possibility of comparing results in between the two monitoring techniques over proportionately long time span. An accelerated corrosion procedure is used to corrode the flexural tensile reinforcement. The cycle may be divided into seven stages, a to g, presented shortly in Figure 1, Horrigmoe (1998) and Sand 2001. This life cycle is possible in the real case scenario for bridges or other concrete structures which are subjected to chlorides, i.e. de-icing salt or sea water
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| 10. |
- Bergström, Markus
(författare)
-
Degradation of structural performance of concrete structures : literature survey
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This literature survey is the start of a project with the title Degradation of structural performance of concrete structures. The project will be carried out at the Division of Structural Engineering, the Department of Civil and Environmental Engineering at Luleå University of Technology (LTU) within the research group "Innovative materials and structures".
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| 11. |
- Bergström, Markus, et al.
(författare)
-
Failure load test of a CFRP strengthened railway bridge in Örnsköldsvik, Sweden
- 2009
-
Ingår i: Journal of Bridge Engineering. - 1084-0702 .- 1943-5592. ; 14:5, s. 300-308
-
Tidskriftsartikel (refereegranskat)abstract
- The results obtained when performing a load test to failure of an existing structure are valuable when assessing calculation models, updating finite element models, and investigating the true structural behavior. In this paper a destructive testing and monitoring of a railway bridge in Örnsköldsvik, Sweden is presented. In this particular test the shear capacity of the concrete girders was of primary interest. However, for any reasonable placement of the load (a line load placed transverse to the track direction) a bending failure would occur. This problem was solved by strengthening for flexure using carbon fiber reinforced polymer (CFRP) rectangular rods epoxy bonded in sawed up slots, e.g., near surface mounted reinforcement. The strengthening was very successful and resulted in a desired shear failure when the bridge was loaded to failure. The load-carrying capacity in bending for the unstrengthened and strengthened bridge as well as the shear capacity was predicted with Monte Carlo simulations. The particular calculation presented showed that there was a 25% probability of a bending failure instead of a shear failure. Monitoring showed that the strengthening reduced the strain in the tensile steel reinforcement by approximately 10%, and increased the height of the compressed zone by 100 mm. When the shear failure occurred, the utilization of the compression concrete and CFRP rods were 100 and 87.5%, respectively. This indicates that a bending failure indeed was about to occur, even though the final failure was in shear.
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| 12. |
- Bergström, Markus
(författare)
-
Life cycle behaviour of concrete bridges : laboratory test and probabilistic evaluation
- 2006
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The structural life for a concrete structure located in an environment where corrosion is promoted by humidity or chlorides from sea or de-icing salt could in general be described in the following manner. The structure is manufactured and is at that point considered to be intact. Corrosion is assumed to attack the steel reinforcement, and at a certain corrosion level the structure has to be repaired. The cover concrete is removed and the corroded steel reinforcement is cleaned from corrosion products. A repair system consisting of primer and repair mortar is used to refill the cavity left after the removed concrete. The structure is now considered repaired in the sense that the degradation rate is decreased and the signs of corrosion are taken away. The corrosion attack and repair procedure could affect the load carrying capacity of the repaired beam in terms of decreased steel content and changed interface conditions between the steel and repair mortar. Strengthening could be applied to fulfil a possible lack of load carrying capacity. The life cycle described above has been simulated in a laboratory environment. The test program and the results provided from the monitoring of beam specimens are presented in the thesis. A probabilistic approach is employed in this thesis to calculate the change in probability of failure for the different stages of the life cycle. First, all relevant parameters were considered as stochastic and given appropriate statistical properties. With this information the increase in probability of failure is estimated for the corroded, repaired and strengthened beams compared to the intact beam. It has been found that the accelerated corrosion setup provided a steel mass content loss of 12% in the corroded region, corresponding to an average decrease in steel bar diameter by 6%. This corrosion damage was obtained after 75 days of accelerated corrosion at a corrosion current density of 0,10 mA/cm2. Both evenly distributed corrosion as well as pitting corrosion attack was observed. The concrete beam stiffness was recorded to 2980 kNm2 before the corrosion process and decreased by 15% to 2530 kNm2 after corrosion of tensile steel reinforcement. This is verified both by measuring stiffness globally using displacement gauges and locally using strain sensors. The result indicates that there is a strong relation between the deterioration process and the change in curvature and stiffness, suggesting that this is a method to measure the status of the structure. The status could for instance be defined by a performance factor, which equals 1 for the intact structure and then decrease to represent the relation between the stiffness of the deteriorated and the intact structure. If the structure is strengthened, the performance factor could be larger than 1. The ductility of the corroded steel reinforcing bars decreased with 55% due to corrosion compared to the undamaged steel reinforcing bars. The ultimate strain for the corroded bars was recorded to 10%, while the ultimate strain for the undamaged bars was 22%. This reduction is caused by pitting corrosion, which produces local stress concentrations along the bar. The failure occurs when the ultimate strain capacity is exceeded in one cross section, leading to an early failure of the steel bar specimen. The global extension of the steel specimen remains small as the failure strain acts on a small region of the total length. For the structural element this will lead to a failure at a particular corrosion level, since the local pits will dramatically decrease the load carrying capacity in one section. A failure of a structural member which is attacked by pitting corrosion could be unnoticed in terms of visual evidence, since the elongation of the steel reinforcement is be kept at a moderate level at failure of steel reinforcement because of the local damages that pitting may create. The strain at yielding is recorded to 0,39% for the intact steel bar and 0,43% for the corroded. Failure was defined as yielding of steel reinforcement for unstrengthened beams, and as debonding of CFRP plate for the strengthened beam. The load carrying capacity for the intact beam was 79,8 kN. The load carrying capacity was decreased by 15% after corrosion of steel reinforcement to 69 kN. For the beam where the cover concrete was removed the load carrying capacity was decreased another 18% down to 60 kN in comparison to the intact beam. Yielding of steel reinforcement for the repaired beam occurred at 64,8 kN, and debonding of CFRP plate for the repaired & strengthened beam occurred at 82,7 kN. These results show that a 12% reduction of steel content in the cross section occurred during the corrosion phase, at the same time as the stiffness was reduced by 15%. An analytical model indicates that the 12% reduction of steel content should decrease the stiffness by 9%. The remaining stiffness decrease may be coupled to creep. Another important fact is that the particular strengthening design upgraded the repaired & strengthened beam to reach a load carrying capacity which exceeds the intact beam. The life cycle behaviour for the concrete beams used in the study shows the same general results in comparison to an FE-analysis. It should be mentioned that the FE-analysis performed has not been done on the tested beams in this study. An analysis of these will however be conducted at a later stage. The probabilistic approach of the studied life cycle shows that the probability of failure increased two times for the corroded beam compared to the intact beam, and further up to seven times for the repaired beam. The increase in probability of failure for the corroded beam is related to steel mass loss. The repaired beam has an even higher probability of failure than the corroded beam since the effective height is reduced during removal of cover concrete of the loaded beam. By strengthening the repaired beam by bonding a CFRP plate, the probability of failure is decreased beyond the intact beam for the particular strengthening operation performed in the study.
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| 13. |
- Bergström, Markus
(författare)
-
Mätning på järnvägsbro över Fröviån
- 2004
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En bågbro för järnvägstrafik över Fröviån förstärktes under sommaren 2004 med NSMR (Near Surface Mounted Reinforcement). För att utröna effekten av förstärkning har mätning utförts såväl före som efter. Föreliggande rapport redovisar sammanställande mätresultat. Utvärdering efter liknande projekt har tidigare genomförts vid Avdelningen för Byggkonstruktion, se Täljsten & Carolin (1999) och Danielsson et al (2002). Stor spridning mellan axellaster, mellan och i tågseten, innebar att en jämförbar faktor för tågöverfarterna identifierades för utvärdering. Genom att studera lokets påverkan på bron tas ingen hänsyn till vagnarnas vikt, varvid relevant jämförelse är utförd. Förstärkning med NSMR har i uppgift att förbättra en konstruktions momentkapacitet. Vissa konstruktioners utformning ger upphov till litet moment, däribland bågkonstruktioner. Denna typ utvecklar i huvudsak tryckspänningar. Vid förstärkning av en bågkonstruktion med NSMR kan en procentuell förbättring förväntas, men förbättringens absolutvärde är relativt liten pga. liten momentbelastning i konstruktionen. Mätningar visade på låg belastning i kolfibermaterialet, med töjningar omkring 10 microstrain. Armeringstöjning vid loköverfart minskade med 20 procent i mittspann, från i snitt 12 till 10 microstrain. Mätning av en böjsprickas maximala öppnande vid loköverfart visade att den minskade från 0,0078 mm till 0,0053 mm, dvs. en minskning med 30%. Här relateras öppnandet ifrån ett jämviktsläge som motsvarar att bron endast är belastad med egentyngd, dvs. då givaren monterades. Sprickans totala vidd är inte uppmätt. I brons fjärdedelspunkt ökade armeringstöjningen från 7 till 8 microstrain. Detta beror på omfördelning av betongsprickor pga. förstärkningen, men det kan också bero på mätfel eftersom skillnaden var liten.
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| 14. |
- Bergström, Markus, et al.
(författare)
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Reparation och förstärkning av betongkonstruktioner
- 2007
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Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; 99:7, s. 48-50
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Att utnyttja moderna metoder och material för att återställa befintliga och åldrande betongkonstruktioner till ett funktionellt skick är viktigt. Studier kring möjligheter att öka såväl den ekonomiska som fysiska livslängden är ett omfattande forskningsområde. Även de praktiska tillämpningarna ökar i antal. Trots att erfarenheten och kunskapen att bygga långsiktigt hållbara betongkonstruktioner hela tiden ökar finns det relativt nya konstruktioner som inte uppfyller ställda krav på säkerhet och funktion. Det finns dessutom otaliga betongkonstruktioner som har brukats under flera årtionden som börjar visa tecken på omfattande brister.
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| 15. |
- Bergström, Markus, et al.
(författare)
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Structural health monitoring of degrading concrete beams in a laboratory environment
- 2006
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Ingår i: Composites in Civil Engineering. - : International Institute for FRP in Construction (IIFC). ; , s. 335-338
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Much effort has been invested separately on degradation, repair and upgrading of concrete structures. However, few holistic studies including laboratory testing have been performed on the entire cycle during a structures life. Reinforced concrete is the most widely used building material in the world. Normally the life of concrete structures is very long. However, concrete structures possess one drawback; at least in severe environments, the steel reinforcement may corrode. The effects can clearly be seen when the steel reinforcement is attacked by chlorides. The reduced steel cross-section area and loss of bond strength between steel and concrete will lead to increased deformations, cracking and premature ultimate load, thus affecting both the serviceability limit state (SLS) and the ultimate limit state (ULS). Procedures to repair and upgrade the damaged structure are used to increase the structural performance. They follow the structural member of time, a SHM (Structural Health Monitoring) approach is adapted to this project. By applying SHM to a degrading structure it assures that it will keep up to current standards by continuous monitoring, analysing, evaluation and eventually also retrofitting.
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| 16. |
- Bergström, Markus, et al.
(författare)
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The Settlement
- 2019
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Ingår i: Verksmidjan art space in Hjalteyri, Iceland (Permanent installation) N4 regional television.
-
Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- A one week workshop and performance leading up to a permanent installation of a prototyped, functional living space within a former fish factory. Initiated by french artist Sonia Levy, director of Verksmidjan Gustav Geir Bollason and myself. Carried out in all by 13 participants (stated above).
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| 17. |
- Bergström, Sofia
(författare)
-
Multiplexed antibody-based protein profiling in the pursuit of CSF biomarkers for neurodegenerative diseases
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a desire for a transition from generic treatments designed for the average patient, towards more individual-based precision medicine. An increased knowledge about disease pathophysiology on a molecular level would be beneficial for this transition. The study of proteins can contribute with valuable insights into etiology and pathogenesis of different diseases and thereby aid the clinical assessment of patients and guide future treatments.Neurodegenerative disorders, such as Alzheimer’s disease, Parkinson’s disease, and frontotemporal dementia, are characterized by a progressive loss of function, and eventually death of neurons. Neurons allow the brain to communicate with the rest of the body, and a deteriorated function of neurons can result in problems with mobility or mental functions. Neurodegenerative diseases progress slowly over many years, with a long silent asymptomatic phase before symptom onset. It is hard to rebuild what is already lost, but disease-modifying treatments might be able to slow down or halt the deterioration of the brain. Therefore, there is a major research focus on investigating the early stages of disease pathogenesis in order to elucidate this critical phase in disease progression.The four papers included in this thesis focus on identifying altered protein profiles in cerebrospinal fluid from patients with neurodegenerative diseases. For this purpose, multiplexed antibody-based suspension bead arrays have been used. This method allows for hundreds of proteins to be analyzed in hundreds of samples in the same assay. Paper I focuses on Alzheimer’s disease and investigates the profiles of 200 proteins when comparing patients with controls. Six proteins were identified at altered levels and were further investigated in relation to the progression from mild cognitive impairment to Alzheimer’s disease. Paper II explores 100 protein profiles in relation to the core Alzheimer’s disease biomarkers in asymptomatic 70-year-olds to elucidate patterns preceding potential disease onset. Paper III investigates the transition to cognitive impairment in patients with Parkinson’s disease and explores potential associations between protein profiles and cognitive assessment tests. Finally, Paper IV explores panels of proteins in the context of frontotemporal dementia. Panels of proteins, instead of single biomarkers, have an increased potential to capture the range of biological processes within these types of complex and multifactorial diseases.Neurodegenerative diseases are often heterogeneous which puts high demands on the study design including an appropriate selection of study population. However, significant similarities are also present which makes it advantageous to have a broad perspective and work with several neurodegenerative disorders. This thesis presents the results from multiplexed antibody-based protein profiling as a contribution to a better understanding of neurodegenerative diseases.
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| 18. |
- Ekman, Simon, et al.
(författare)
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A novel oral insulin-like growth factor-1 receptor pathway modulator and its implications for patients with non-small cell lung carcinoma : A phase I clinical trial
- 2016
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 55:2, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A phase Ia/b dose-escalation study was performed to characterize the safety, efficacy and pharmacokinetic properties of the oral small molecule insulin-like growth factor-1-receptor pathway modulator AXL1717 in patients with advanced solid tumors.MATERIAL AND METHODS: This was a prospective, single-armed, open label, dose-finding phase Ia/b study with the aim of single day dosing (phase Ia) to define the starting dose for multi-day dosing (phase Ib), and phase Ib to define and confirm recommended phase II dose (RP2D) and if possible maximum tolerated dose (MTD) for repeated dosing.RESULTS AND CONCLUSION: Phase Ia enrolled 16 patients and dose escalations up to 2900 mg BID were successfully performed without any dose limiting toxicity (DLT). A total of 39 patients were treated in phase Ib. AXL1717 was well tolerated with neutropenia as the only dose-related, reversible, DLT. RP2D dose was found to be 390 mg BID for four weeks. Some patients, mainly with NSCLC, demonstrated signs of clinical benefit, including four partial tumor responses (one according to RECIST and three according to PET). The 15 patients with NSCLC with treatment duration longer than two weeks with single agent AXL1717 in third or fourth line of therapy showed a median progression-free survival of 31 weeks and overall survival of 60 weeks. Down-regulation of IGF-1R on granulocytes and increases of free serum levels of IGF-1 were seen in patients treated with AXL1717. AXL1717 had an acceptable safety profile and demonstrated promising efficacy in this heavily pretreated patient cohort, especially in patients with NSCLC. RP2D was concluded to be 390 mg BID for four weeks. Trial number is NCT01062620.
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| 19. |
- Fridén, Markus, et al.
(författare)
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Measurement of Unbound Drug Exposure in Brain : Modelling of pH Partitioning Explains Diverging Results between the Brain Slice and Brain Homogenate Methods
- 2011
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 39:3, s. 353-362
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Tidskriftsartikel (refereegranskat)abstract
- Currently used methodology for determining unbound drug exposure in brain combines measurement of the total drug concentration in the whole brain in vivo with estimation of brain tissue binding from one of two available in vitro methods: equilibrium dialysis of brain homogenate and the brain slice uptake method. This study of 56 compounds compares the fraction of unbound drug in brain (f(u,brain)), determined using the brain homogenate method, with the unbound volume of distribution in brain (V(u,brain)), determined using the brain slice method. Discrepancies were frequent and primarily related to drug pH partitioning, due to the preservation of cellular structures in the slice that are absent in the homogenate. A mathematical model for pH partitioning into acidic intracellular compartments was derived to predict the slice V(u,brain) from measurements of f(u,brain) and drug pKa. This model allowed prediction of V(u,brain) from f(u,brain) within a 2.2-fold error range for 95% of the drugs, as compared to a 4.5-fold error range using the brain homogenate f(u,brain) method alone. The greatest discrepancies between the methods occurred with compounds that are actively transported into brain cells, including gabapentin, metformin and prototypic organic cation transporter substrates. It is concluded that intra-brain drug distribution is governed by several diverse mechanisms in addition to non-specific binding and that the slice method is therefore more reliable than the homogenate method. Alternatively, predictions of V(u,brain) can be made from homogenate f(u,brain) using the presented pH partition model, although this model does not take into consideration possible active brain cell uptake.
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| 20. |
- Fritioff, Tomas, et al.
(författare)
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Precise measurements of ionic masses for QED tests
- 2006
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Ingår i: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806 .- 1873-2798. ; 251:2-3, s. 281-285
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Tidskriftsartikel (refereegranskat)abstract
- The Penning trap mass spectrometer SMILETRAP is designed for precision mass measurements using the merits of highly charged ions. In this paper we describe the feature of SMILETRAP and give examples of mass measurements involving , , and ions. These emphasize the importance of accurate masses of hydrogen-like and lithium-like ions that are required in the evaluation of g-factor measurements of electrons bound to even–even nuclei and test of QED effects. Highly precise mass measurements can also be used for testing atomic structure calculations and determining atomic binding energies. Relevance of such measurements throughout the periodic system is discussed.
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| 21. |
- Grygiel, Konrad, et al.
(författare)
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Omnidispersible poly(ionic liquid)-functionalized cellulose nanofibrils : surface grafting and polymer membrane reinforcement
- 2014
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 50:83, s. 12486-12489
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Tidskriftsartikel (refereegranskat)abstract
- We report a facile one-step route to graft poly(ionic liquid)s (PILs) onto cellulose nanofibrils (CNFs). The dispersibility of the PIL-functionalized CNFs in water and various organic solvents could be tuned by the choice of the PIL-binding anion. We demonstrate that such omnidispersible PIL@CNF hybrids can be used to reinforce porous poly(ionic liquid) membranes.
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| 22. |
- Hansson, Sture, et al.
(författare)
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Competition for the fish - fish extraction from the Baltic Sea by humans, aquatic mammals, and birds
- 2018
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 75:3, s. 999-1008
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Tidskriftsartikel (refereegranskat)abstract
- Seals and fish-eating birds have increased in the Baltic Sea and there is concern that they compete with fisheries. Using data from around year 2010, we compare consumption of different fish species by seals and birds to the catch in the commercial and recreational fishery. When applicable this is done at the geographical resolution of ICES subdivisions. Predation by birds and mammals likely has limited impact on the populations of the commercially most important species (herring, sprat, and cod). In the central and southern Baltic, seals and birds consume about as much flatfish as is caught by the fishery and competition is possible. Birds and seals consume 2-3 times as much coastal fish as is caught in the fishery. Many of these species are important to the fishery (e. g. perch and whitefish) and competition between wildlife and the fishery is likely, at least locally. Estimated wildlife consumption of pike, sea trout and pikeperch varies among ICES subdivisions and the degree of competition for these species may differ among areas. Competition between wildlife and fisheries need to be addressed in basic ecosystem research, management and conservation. This requires improved quantitative data on wildlife diets, abundances and fish production.
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| 23. |
- Hansson, Sture, 1953-, et al.
(författare)
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Response to comments by Heikinheimo et al. (in press) on Hansson et al. (2018): competition for the fish—fish extraction from the Baltic Sea by humans, aquatic mammals, and birds
- 2018
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 75:5, s. 1837-1839
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Tidskriftsartikel (refereegranskat)abstract
- As discussions and debates are crucial to science, we appreciate the comments by Heikinheimo et al. (in press) on our article on competition for Baltic Sea fish resources between fishery and wildlife. We cannot see that the comments by Heikinheimo et al. changes the general conclusion derived in our original article—that there are cases of competition between wildlife and fisheries in the Baltic Sea, although not for all species and not to the same extent everywhere. Our responses are structured in the same order as the comments by Heikinheimo et al.
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| 24. |
- Hedfalk, Kristina, 1969, et al.
(författare)
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A Regulatory Domain in the C-terminal Extension of the Yeast Glycerol Channel Fps1p
- 2004
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Ingår i: Journal of biological chemistry. ; 279:15, s. 14954-14960
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Tidskriftsartikel (refereegranskat)abstract
- The Saccharomyces cerevisiae gene FPS1 encodes an aquaglyceroporin of the major intrinsic protein (MIP) family. The main function of Fps1p seems to be the efflux of glycerol in the adaptation of the yeast cell to lower external osmolarity. Fps1p is an atypical member of the family, because the protein is much larger (669 amino acids) than most MIPs due to long hydrophilic extensions in both termini. We have shown previously that a short domain in the N-terminal extension of the protein is required for restricting glycerol transport through the channel (Tamás, M. J., Karlgren, S., Bill, R. M., Hedfalk, K., Allegri, L., Ferreira, M., Thevelein, J. M., Rydström, J., Mullins, J. G. L., and Hohmann, S. (2003) J. Biol. Chem. 278, 63376345). Deletion of the N-terminal domain results in an unregulated channel, loss of glycerol, and osmosensitivity. In this work we have investigated the role of the Fps1p C terminus (139 amino acids). A set of eight truncations has been constructed and tested in vivo in a yeast fps1 strain. We have performed growth tests, membrane localization following cell fractionation, and glycerol accumulation measurements as well as an investigation of the osmotic stress response. Our results show that the C-terminal extension is also involved in restricting transport through Fps1p. We have identified a sequence of 12 amino acids, residues 535546, close to the sixth transmembrane domain. This element seems to be important for controlling Fps1p function. Similar to the N-terminal domain, the C-terminal domain is amphiphilic and has a potential to dip into the membrane
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| 25. |
- Holgersson, Georg, et al.
(författare)
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A phase I pilot study of the insulin-like growth factor 1 receptor pathway modulator AXL1717 in combination with gemcitabine HCl and carboplatin in previously untreated, locally advanced, or metastatic non-small cell lung cancer
- 2015
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Ingår i: Medical Oncology. - : Springer Science and Business Media LLC. - 1357-0560 .- 1559-131X. ; 32:4
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Tidskriftsartikel (refereegranskat)abstract
- AXL1717 is an orally bioavailable IGF-1R pathway modulator that has been shown to have anti-tumoral effects. The objectives of the present study were to define maximum tolerated dose and the recommended phase II dose (RPTD) of AXL1717 in combination with gemcitabine HCl and carboplatin in non-small cell lung cancer (NSCLC). Patients with previously untreated, locally advanced, or metastatic NSCLC (squamous cell cancer or adenocarcinoma) in good performance status and with preserved major organ functions were enrolled in the study. The study was an open-label phase I study with planned cohorts of three patients per dose level of AXL1717 (215, 290, and 390 mg BID). In total, 12 patients were enrolled in the study, and of these, two were prematurely excluded. AXL1717 was administered at one dose level, 215 mg BID. A total number of 81 unique adverse events were reported. Bone marrow toxicity was reported in 10 out of 12 patients, and this organ class showed the largest number of related events. AXL1717 in combination with gemcitabine HCl and carboplatin is a possible treatment approach in previously untreated, locally advanced, or metastatic non-small cell lung cancer. However, due to the bone marrow toxicity profile shown in the present study, further dose increases of AXL1717 above 215 mg BID will probably not be feasible. Therefore, 215 mg BID constitutes maximum tolerated dose and RPTD.
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| 26. |
- Jernberg, Tomas, et al.
(författare)
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Long-Term Effects of Oxygen Therapy on Death or Hospitalization for Heart Failure in Patients With Suspected Acute Myocardial Infarction
- 2018
-
Ingår i: Circulation. - : LIPPINCOTT WILLIAMS & WILKINS. - 0009-7322 .- 1524-4539. ; 138:24, s. 2754-2762
-
Tidskriftsartikel (refereegranskat)abstract
- Background: In the DETO2X-AMI trial (Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction), we compared supplemental oxygen with ambient air in normoxemic patients presenting with suspected myocardial infarction and found no significant survival benefit at 1 year. However, important secondary end points were not yet available. We now report the prespecified secondary end points cardiovascular death and the composite of all-cause death and hospitalization for heart failure.Methods: In this pragmatic, registry-based randomized clinical trial, we used a nationwide quality registry for coronary care for trial procedures and evaluated end points through the Swedish population registry (mortality), the Swedish inpatient registry (heart failure), and cause of death registry (cardiovascular death). Patients with suspected acute myocardial infarction and oxygen saturation of ≥90% were randomly assigned to receive either supplemental oxygen at 6 L/min for 6 to 12 hours delivered by open face mask or ambient air.Results: A total of 6629 patients were enrolled. Acute heart failure treatment, left ventricular systolic function assessed by echocardiography, and infarct size measured by high-sensitive cardiac troponin T were similar in the 2 groups during the hospitalization period. All-cause death or hospitalization for heart failure within 1 year after randomization occurred in 8.0% of patients assigned to oxygen and in 7.9% of patients assigned to ambient air (hazard ratio, 0.99; 95% CI, 0.84–1.18; P=0.92). During long-term follow-up (median [range], 2.1 [1.0–3.7] years), the composite end point occurred in 11.2% of patients assigned to oxygen and in 10.8% of patients assigned to ambient air (hazard ratio, 1.02; 95% CI, 0.88–1.17; P=0.84), and cardiovascular death occurred in 5.2% of patients assigned to oxygen and in 4.8% assigned to ambient air (hazard ratio, 1.07; 95% CI, 0.87–1.33; P=0.52). The results were consistent across all predefined subgroups.Conclusions: Routine use of supplemental oxygen in normoxemic patients with suspected myocardial infarction was not found to reduce the composite of all-cause mortality and hospitalization for heart failure, or cardiovascular death within 1 year or during long-term follow-up.Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01787110.
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| 27. |
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| 28. |
- Jons, Daniel, 1974, et al.
(författare)
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Follow-up after infectious mononucleosis in search of serological similarities with presymptomatic multiple sclerosis
- 2021
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Ingår i: Multiple Sclerosis and Related Disorders. - : Elsevier BV. - 2211-0348 .- 2211-0356. ; 56
-
Tidskriftsartikel (refereegranskat)abstract
- Background: : A two- to three-fold increase in the risk of multiple sclerosis (MS) after infectious mononucleosis (IM) has been observed in cohort and case control studies. However, this association has not been investigated prospectively from IM. It remains to be determined whether long-term immunospecific sequelae with features consistent with presymptomatic MS occur after IM. Methods: : Sera were obtained from individuals with acute IM from 2003-2007 (n = 42) and from the same individuals at a follow-up (FU) study approximately 10 years after IM. These were assayed for antibodies against a variety of Epstein-Barr virus (EBV) antigens, including gp350, a novel recombinant glycoprotein from the EBV envelope. Similarly, single-protein antigens were used to assess measles and varicella-zoster reactivity (Ncore and varicella-zoster glycoprotein E [VZVgE]). The FU study also included cerebrospinal fluid (CSF) samples from 21 of these individuals to test for IgG antibodies against the same viral antigens. As controls, CSF and serum samples were obtained from 15 EBV-seropositive volunteers who denied a history of IM, and serum samples were obtained from 24 EBV-seropositive blood donors. Anti-gp350, anti-Ncore and anti-VZVgE IgG levels were also analysed in sera and CSF samples from 22 persons with MS. Results: : The FU assays showed higher anti-gp350 IgG (p = 0.007, univariate) than among healthy controls, with no difference in serum anti-VCA or anti-EBNA1 IgG levels and no difference in anti-gp350 in the CSF samples. Anti-Ncore IgG and anti-VZVgE were higher in acute IM samples (p < 0.001 and p < 0.0001, respectively) than at FU, although anti-Ncore remained heightened in an age-adjusted analysis at FU (p = 0.014) compared to the control group. In the MS group, the serum anti-gp350 and anti-Ncore IgG levels were significantly higher than among the control group, but the anti-VZVgE levels were not. The CSF anti-gp350 and VZVgE levels were slightly higher among persons with MS than among the control group, whereas anti-Ncore IgG was markedly higher in persons with MS than in the control group. Conclusion: : In the present study IM showed certain similarities with MS. Increased anti-gp350 reactivity persisted more than a decade after IM, reminiscent of the established increased anti-EBV reactivity in presymptomatic MS. Acute IM was associated with increased anti-measles and anti-VZV immunoreactivity, similar to the MRZ reaction in MS, with some evidence suggesting that this measles reactivity persisted after a decade.
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| 29. |
- Jons, Daniel, 1974, et al.
(författare)
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Intrathecal immunoreactivity in people with or without previous infectious mononucleosis
- 2020
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Ingår i: Acta Neurologica Scandinavica. - : John Wiley & Sons. - 0001-6314 .- 1600-0404. ; 142:2, s. 161-168
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: The risk of developing multiple sclerosis (MS) increases (OR: 3.1) after infectious mononucleosis (IM). However, the nature of this link is obscure. We tested the hypothesis that IM might incur long-term sequelae, including low-key inflammatory activity, with characteristics of an MS endophenotype (or presymptomatic trait) and that assays of MS-relevant cyto-/chemokines in the cerebrospinal fluid (CSF) post-IM may show a trend in this direction.Materials and methods: We selected seven CSF cytokines (IL-1b, IL-6, YKL-40, TNF-alpha) or chemokines (IL-8, CCL2, IP-10), representing pro-inflammatory factors previously associated with MS. We assayed the CSF levels of these seven cyto-/chemokines in healthy individuals with a median follow-up time of 10 years after serologically confirmed IM (post-IM group, n = 22), and in healthy controls without a history of IM (n = 19). A group of MS patients (n = 23) were included as reference.Results: The CSF levels of IP-10, YKL-40, and CCL-2 were higher in the post-IM group than in our IM unexposed controls (P = .021, .049, .028). Seven of seven cyto-/chemokine assays showed a trend in the predicted direction (Pof binomial ratio = .008). However, this trend was non-significant in a multivariate test (P = .22). A power analysis indicated that similar studies including a larger cohort would be numerically realistic.Conclusions: These results do not reject the hypothesis that the established epidemiological association between IM and MS results from a stepwise inflammatory propagation from IM sequelae to an MS endophenotype (or presymptomatic trait) in a proportion of IM patients, pending confirmation with adequate power.
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| 30. |
- Jonsson, Anders, et al.
(författare)
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Whole-lake mineralization of allochthonous and autochthonous organic carbon in a large humic lake (Örträsket, N. Sweden)
- 2001
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 46:7, s. 1691-1700
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Tidskriftsartikel (refereegranskat)abstract
- Organic carbon mineralization was studied. in a large humic lake (Lake Örträsket) in northern Sweden during a well-defined summer stratification period following high water flow during snowmelt. Several independent methods including plankton counts, measurements of bacterioplankton and phytoplankton production, stable isotope monitoring, sediment trapping, and mass balance calculations were used. Total organic carbon mineralization showed a summer mean of 0.3 g C m(-2) d(-1) and was partitioned about equally between water and sediment. In the water column, organic matter was mineralized by bacteria (60%) and protozoan and metazoan zooplankton (30%), as well as by photooxidation (10%). Most of the mineralized organic carbon was of allochthonous origin. Primary production in the lake contributed at most 5% of the total organic carbon input and about 20% of the total organic carbon mineralization. Total carbon mineralization in. the epilimnion and metalimnion agreed well with an estimate of CO2 evasion from the stratified lake, while CO2 accumulation in the hypolimnion matched the O-2 consumption and resulted in a very negative delta C-13 of DIC before autumn overturn (-23 parts per thousand). Isotopic compositions of DIC and POC confirmed the dominant influence of terrestrial organic input on the cycling of both organic and inorganic carbon in the lake.
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| 31. |
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| 32. |
- Lindqvist, Markus, et al.
(författare)
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Plasma glycosylphosphatidylinositol phospholipase D (GPI-PLD) and abdominal aortic aneurysm.
- 2012
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Ingår i: International Journal of Clinical and Experimental Medicine. - 1940-5901. ; 5:4, s. 306-9
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Tidskriftsartikel (refereegranskat)abstract
- Recent reviews state that a circulating biomarker predicting aortic rupture risk would be a powerful tool to stratify patients with small screen-detected abdominal aortic aneurysm (AAA). In a current proteomic pilot-study elevated levels of the enzyme Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) was shown in patients with small AAA compared with controls without aneurysm. In the present study we investigated the impact of plasma GPI-PLD as a biomarker in patients with AAA in relation to aneurysm size, and rupture. Plasma GPI-PLD was measured in patients with AAA (nonruptured, n=78 and ruptured, n=55) and controls without aneurysm (n=41) matched by age, sex and smoking habit. The plasma GPI-PLD levels were significantly lower in patients with ruptured compared nonruptured AAA which we interpreted as a result of hemodilution due to hemorrhage in patients with ruptured AAA. The plasma GPI-PLD levels were similar in patients with nonruptured AAA compared to the controls without aneurysm. Furthermore, there was no correlation between plasma GPI-PLD and aneurysm size in the group of patients with nonruptured AAA. In conclusion, the present study fails to show a connection between GPI-PLD and AAA. However, the definite role of GPI-PLD as a predictive marker needs to be further clarified in a follow-up cohort study.
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| 33. |
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| 34. |
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| 35. |
- Schuch, Reinhold, et al.
(författare)
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Q value related mass determinations using a Penning trap
- 2007
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Ingår i: Hyperfine Interactions. - Nederländerna : Springer. - 0304-3843 .- 1572-9540. ; 173:1-3, s. 73-83
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Tidskriftsartikel (refereegranskat)abstract
- We report here about measurements of reaction and decay Q values by precise determination of pairs of atomic masses. These were performed with the Penning trap mass spectrometer SMILETRAP. Measurements with Penning traps give reliable and accurate masses, in particular Q values, due to the fact that certain systematic errors to a great deal cancel in the mass difference between the two atoms defining the Q value. Some Q values that are of fundamental interest will be discussed here, for example, a new Q value for the 6Li (n,γ) 7Li reaction, for the β-decay of tritium, related to properties of the electron neutrino mass, and for the neutrino-less double β-decay of 76Ge, related to the question of whether the neutrino is a Majorana particle or not. In case of the latter two we report the most accurate Q values, namely 18,589.8(12) eV for the tritium decay and 2,038.997(46) keV for the neutrino-less double β-decay of 76Ge.
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| 36. |
- Solders, Andreas, et al.
(författare)
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Determination of the proton mass from a measurement of the cyclotron frequencies of D+ and H2+ in a Penning trap
- 2008
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - Maryland, USA : American Physical Society. - 1050-2947 .- 1094-1622. ; 78:1, s. 2514-2520
-
Tidskriftsartikel (refereegranskat)abstract
- We determine the cyclotron frequency ratio of H2+ and D+, applying the two-pulse Ramsey-excitation technique in the Penning-trap mass spectrometer SMILETRAP. The final result, based on probing more than 100 000 ions, is a frequency ratio of 0.999 231 659 33(17). Using a value of the D+ mass recently measured by the Seattle group, we obtain so far the most precise experimental H2+ mass value of 2.015 101 497 16(34) u. From this value a proton mass value of 1.007 276 466 95(18) u (0.18 ppb relative uncertainty) could be derived, in good agreement with the value of 1.007 276 466 89(14) u published by Van Dyck et al.
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| 37. |
- Suhonen, Markus, 1972-, et al.
(författare)
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High-frequency Ramsey excitation in a Penning trap
- 2007
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Ingår i: Journal of Instrumentation. - England/Italien : IOP, SISSA. - 1748-0221. ; 2:P06003, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- The Ramsey excitation method for high-precision mass-measurements of highly-charged ions has been investigated and benchmarked using H2+ ions in the Penning-trap mass-spectrometer SMILETRAP. The reason for using H2+ ions are their high cyclotron frequency which is typical for the highly-charged ions usually used at SMILETRAP. Two-, three- and four-pulse Ramsey excitation data are analyzed with the help of recent theoretical work and are compared with the previously used single-pulse excitation data. An improvement factor of 2.9 in the statistical uncertainty is achieved. Furthermore the mass of 76Se, included in the previous Q-value measurement of the 76Ge neutrinoless double beta decay, is checked using 76Se25+ ions and a three-pulse Ramsey excitation. The results show a convincing agreement with the measurement when using single-pulse excitation and therefore our Q-value of 2039.006(50) keV, performed with single-pulse excitation, is confirmed.
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| 38. |
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| 39. |
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| 40. |
- Wetterskog, Erik, 1983-
(författare)
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Building crystals out of crystals : Synthesis, structure and magnetic properties of iron oxide nanoparticles and self-assembled mesocrystals
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on the fabrication and characterization of self-assembled arrays of magnetic iron oxide (Fe3O4, γ-Fe2O3 and Fe1-xO) nanoparticles. The synthesis of spherical and cubic iron oxide nanocrystals, with sizes between 5 and 30 nm and narrow size distributions, is demonstrated, along with a rigorous morphological characterization of the cubic nanoparticles. The transformation of core|shell Fe1-xO|Fe3-δO4 particles into single-phase Fe3-δO4 particles is studied in detail. It is found that anti-phase boundaries in the particles result in the emergence of anomalous magnetic properties i.e. exchange bias, and a reduced saturation magnetization compared to that of bulk Fe3O4. Cubic nanocrystals are assembled into arrays possessing an exceptionally high degree of translational ordering and a high degree of crystallographic alignment. A combination of electron microscopy and small-angle X-ray scattering is used in the characterization of the 3D nanostructures. The directional (anisotropic) interactions in the 3D structures are modeled in an attempt to find a link between the nanocrystal morphology and the corresponding mesostructure. Here, the cohesive van der Waals energy is estimated for a system of nanocubes with a variable truncation. The assembly of nanocubes in magnetic fields of various strengths is systematically investigated. A perturbed mesocrystal growth habit is observed at intermediate fields, whereas at high field strengths, the assembly is dominated by ferrohydrodynamic instabilities. Last, magnetometry is used to study the collective magnetic properties of self-assembled nanocrystals. The magnetic susceptibility in a weak magnetic field is studied as a function of film thickness and particle size. An increase in the tendency to form ferromagnetic couplings with decreasing film thickness can be established. This 2D to 3D crossover of the magnetic properties of the nanoparticle arrays can be related to a change in the magnetic vortex states.
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| 41. |
- Wicklein, Bernd, et al.
(författare)
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Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide
- 2015
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Ingår i: Nature Nanotechnology. - 1748-3387 .- 1748-3395. ; 10:3, s. 277-283
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Tidskriftsartikel (refereegranskat)abstract
- High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m(-1) K-1, which is about half that of expanded polystyrene. At 30 degrees C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.
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| 42. |
- Yu, Zhi-Long, et al.
(författare)
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Fire-Retardant and Thermally Insulating Phenolic-Silica Aerogels
- 2018
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 57:17, s. 4538-4542
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Tidskriftsartikel (refereegranskat)abstract
- Energy efficient buildings require materials with a low thermal conductivity and a high fire resistance. Traditional organic insulation materials are limited by their poor fire resistance and inorganic insulation materials are either brittle or display a high thermal conductivity. Herein we report a mechanically resilient organic/inorganic composite aerogel with a thermal conductivity significantly lower than expanded polystyrene and excellent fire resistance. Co-polymerization and nanoscale phase separation of the phenol-formaldehyde-resin (PFR) and silica generate a binary network with domain sizes below 20 nm. The PFR/SiO2 aerogel can resist a high-temperature flame without disintegration and prevents the temperature on the non-exposed side from increasing above the temperature critical for the collapse of reinforced concrete structures.
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