| 1. |
- Bernhard, Jonte, 1953-, et al.
(author)
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Alternating currents first : Experiences from designing a novel approach to teaching electric circuit theory
- 2016
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In: 44th Annual Conference of the European Society for Engineering Education - Engineering Education on Top of the World. - : European Society for Engineering Education (SEFI). - 9782873520144
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Conference paper (peer-reviewed)abstract
- BACKGROUND: Commonly in electric circuit theory courses, circuit laws are first introduced in the context of direct current (DC) electricity and first thereafter are alternating currents (AC) introduced. The extension of DC-theory to AC is quite easily done mathematically but is conceptually difficult for students. Engineering students have difficulties in understanding phase relationships and phasor representations in AC-electricity. Indeed, it has been suggested that phase should be seen as a threshold concept.PURPOSE: The purpose of this study was to investigate if a re-designed introductory electric circuit course could improve students’ understanding of important concepts in AC-electricity.METHOD and COURSE DESIGN: The course was re-designed introducing AC and DC electricity simultaneously. DC was introduced as a special case of AC with requency equals zero. The re-designed course was taught for the first time during the spring semester 2014 and a new textbook was written. A conceptual test was developed and first administered in 2013 to serve as a baseline and in subsequent years to evaluate the revised course. In 2014 the students’ courses of action in selected lab-groups were video-recorded.RESULTS: In the first revision cycle many students had difficulties to complete the labs in time. Students revealed a mixed response towards the revised course and the results on the conceptual test showed neglible improvement. In the second cycle revisions the number tasks were reduced and focus was laid on tasks that were identified as most important for contributing to the development of student understanding. As a result the learning gain improved with an effect size (Cohen’s delta) of 0.56. Also the course and the textbook were very well appreciated. In the third cycle only small revisions are made.CONCLUSION: The results show that that AC-electricity can be taught concurrently with DC. However, two revisions cycles was needed which demonstrates that curriculum development needs a sustained effort over a considerable period of time with continuous revisions in light of gained experiences. In further revision we will continue to refine the labs and to develop appropriate interactive lecture demonstrations for the lectures and to develop the problems.
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| 2. |
- Bogo, Renata, et al.
(author)
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Prevalence, Incidence Proportion, and Heritability for Tinnitus : A Longitudinal Twin Study
- 2017
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In: Ear and Hearing. - 0196-0202 .- 1538-4667. ; 38:3, s. 292-300
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Journal article (peer-reviewed)abstract
- OBJECTIVES: The purpose of this longitudinal twin study was to explore the effect of tinnitus on hearing thresholds and threshold shifts over two decades and to investigate the genetic contribution to tinnitus in a male twin cohort (n = 1114 at baseline and 583 at follow-up). The hypothesis was that participants with faster hearing deterioration had a higher risk for developing tinnitus and there is an underlying role of genetic influences on tinnitus.DESIGN: Male mono- and dizygotic twin pairs, born between 1914 and 1958 were included. Mixed models were used for comparison of hearing threshold shifts, adjusted for age. A co-twin comparison was made within pairs discordant for tinnitus. The relative influence of genetic and environmental factors was estimated by genetic modeling.RESULTS: The overall prevalence of tinnitus was 13.5% at baseline (x age 50) and 34.4% at follow-up (x age 67). The overall incidence proportion was 27.8%. Participants who reported tinnitus at baseline or at both time points were older. At baseline, the hearing thresholds differed between tinnitus cases and controls at all frequencies. New tinnitus cases at follow-up had the greatest hearing threshold shift at the high-frequency area compared with the control group. Within pairs, the tinnitus twin had poorer hearing than his unaffected co-twin, more so for dizygotic than monozygotic twin pairs. The relative proportion of additive genetic factors was approximately 0.40 at both time points, and the influence of individual-specific environment was 0.56 to 0.61. The influence of genetic factors on tinnitus was largely independent of genetic factors for hearing thresholds.CONCLUSIONS: Our hypotheses were confirmed: The fastest hearing deterioration occurred for new tinnitus cases. A moderate genetic influence for tinnitus was confirmed.
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| 3. |
- Bogo, Renata, et al.
(author)
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The Role of Genetic Factors for Hearing Deterioration Across 20 Years : A Twin Study
- 2015
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In: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press (OUP). - 1079-5006 .- 1758-535X. ; 70:5, s. 647-653
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Journal article (peer-reviewed)abstract
- Background. Hearing deterioration at advanced ages is associated with environmental exposures (eg, to noise and solvents) and genetic influences may also be important. Little is known about the role of genetic influences on hearing when evaluated longitudinally. We sought to investigate longitudinal hearing loss in a cohort of adult male twins to evaluate the importance of genetic and environmental factors for hearing deterioration over time. Methods. Hearing using conventional clinical audiometry was assessed in 583 male twins (128 monozygotic twin pairs and 111 dizygotic twin pairs) aged 34-79 at baseline and again two decades later. The hearing thresholds at two time points were compared at each frequency and in two different frequency regions. Genetic analyses were based on structural equation models. Bivariate Cholesky decomposition was used for longitudinal analysis. Results. The prevalence of hearing loss increased over time in better and worse ear. The hearing threshold shift was more pronounced in the high-frequency region, especially at 8000 Hz. Genetic influences were moderate (heritability: 53%-65%) for pure-tone averages at both lower and higher frequencies, and were of equal magnitude at baseline and follow-up. In contrast, environmental influences were of substantial importance (55%-88%) for rate of change of the hearing threshold over the 18-year period. Conclusions. Genetic factors are of considerable importance for level of hearing acuity, but environmental factors are more important for rate of change over an 18-year period.
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| 4. |
- Granquist, Linda, et al.
(author)
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Optimization of peak area precision of a GC-MS drug screening method using a nonparametric sign test
- 2019
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In: Accreditation and Quality Assurance. - : SPRINGER. - 0949-1775 .- 1432-0517. ; 24:3, s. 215-226
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Journal article (peer-reviewed)abstract
- The optimization of a number ofgas chromatography-mass spectrometry (GC-MS) parameters in order to improve peak area precision through the application of a nonparametric statistical test (the sign test) is demonstrated. As an example, the drug screening method used at the Swedish National Forensic Centre (NFC) is optimized, but in principle, any GC-MS method could be optimized using this approach. The GC-MS parameters investigated were those often overlooked in the optimization process, namely injection volume, liner type, oven temperature program, final oven temperature, MS scan range and MS scan rate. The influence of these parameters on the precision of the peak area responses of 11 different compounds in a test mixture was evaluated using the sign test for pairwise comparison. This nonparametric test provides probability values which facilitate the ranking of parameters according to their influence on peak area variation as well as providing a measure of their statistical significance. This study presents the resulting optimized method and shows that the decreased total variation depended predominantly on liner type and MS scan rate settings. This work also shows that optimization of analytical methods can be achieved using simple and easily accessible statistical tools.
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| 5. |
- Harati, Ebrahim, 1986-, et al.
(author)
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Effect of HFMI treatment procedure on weld toe geometry and fatigue properties of high strength steel welds
- 2016
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In: Procedia Structural Integrity. - : Elsevier. - 2452-3216. ; 2, s. 3483-3490
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Journal article (peer-reviewed)abstract
- The effects of high frequency mechanical impact (HFMI) treatment procedure on the weld toe geometry and fatigue strength in 1300 MPa yield strength steel welds were investigated. In this regard first the effect of three or six run treatments on the weld toe geometry was evaluated. The fatigue strength and weld toe geometry of as-welded and HFMI treated samples was then compared. Fatigue testing was done under fully reversed, constant amplitude bending load. When increasing the number of treatment runs from three to six, the weld toe radius and width of treatment remained almost constant. However, a slightly smaller depth of treatment in the base metal and a somewhat larger depth of treatment in the weld metal was observed. HFMI treatment increased the fatigue strength by 26%. The treatment did not increase the weld toe radius significantly, but resulted in a more uniform weld toe geometry along the weld. A depth of treatment in the base metal in the range of 0.15-0.19 mm and a width of treatment in the range of 2.5-3 mm, were achieved. It is concluded that the three run treatment would be a more economical option than the six run treatment providing a similar or even more favourable geometry modification.
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| 6. |
- Hosseini, Vahid A., 1987-, et al.
(author)
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Influence of multiple thermal cycles on microstructure of heat-affected zone in TIG-welded super duplex stainless steel
- 2016
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In: Welding in the World. - : Springer Verlag. - 0043-2288 .- 1878-6669. ; 60:2, s. 233-245
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Journal article (peer-reviewed)abstract
- The influence of heat input and multiple welding cycles on the microstructure of the heat-affected zone in autogenously TIG-welded 6 mm 2507 type super duplex stainless steel plates was investigated. In order to produce multiple thermal cycles, one to four pass bead-on-plate welds were made with arc energies of 0.47 and 1.08 kJ/mm, corresponding to heat inputs of 0.37 and 0.87 kJ/mm. Several thermocouples were attached to record thermal cycles on the front and back sides of the plates. Finite element modelling was successfully done to map and correlate measured and calculated peak temperatures. Only minor changes were seen in the ferrite content at 1 and 2 mm from the fusion boundary. Nitrides formed in all passes of the low heat input samples in a region next to the fusion boundary, but only after the third and fourth passes of the high heat input samples. Sigma phase precipitated only in a zone heated to a peak temperature in the range of approximately 828 to 1028 °C. Multiple reheating was found to promote precipitation of sigma phase relatively more than slower cooling. A precipitation free zone was observed between the nitride and sigma phase bands. The precipitation behaviour could be understood from equilibrium phase diagrams, evaluation of local thermal cycles and by correlating results from the modelling and measurements of peak temperatures. It is suggested that the peak temperature, the accumulated time in the critical temperature range between approximately 828 and 1028 °C, and the number of thermal cycles are the most relevant criteria when evaluating the risk of sigma phase formation.
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| 7. |
- Hosseini, Vahid A., 1987-, et al.
(author)
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Nitrogen loss and effects on microstructure in multipass TIG welding of a super duplex stainless steel
- 2016
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In: Materials & design. - : Elsevier Ltd. - 0264-1275 .- 1873-4197. ; 98, s. 88-97
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Journal article (peer-reviewed)abstract
- Nitrogen loss is an important phenomenon in welding of super duplex stainless steels. In this study, a super duplex stainless steel was autogenously TIG-welded with one to four bead-on-plate passes with low or high heat inputs using pure argon shielding gas. The goal was to monitor nitrogen content and microstructure for each weld pass. Nitrogen content, measured by wavelength dispersive X-ray spectrometry, was after four passes reduced from 0.28 wt% in the base metal to 0.17 wt% and 0.10 wt% in low and high heat input samples, respectively. Nitrogen loss resulted in a more ferritic structure with larger grains and nitride precipitates. The ferrite grain width markedly increased with increasing number of passes and heat input. Ferrite content increased from 55% in base metal to 75% at low and 79% at high heat inputs after four passes. An increasing amount of nitrides were seen with increasing number of weld passes. An equation was suggested for calculation of the final nitrogen content of the weld metal as functions of initial nitrogen content and arc energy. Acceptable ferrite contents were seen for one or two passes. The recommendation is to use nitrogen in shielding gas and proper filler metals.
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| 8. |
- Hosseini, Vahid, 1987-, et al.
(author)
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A novel arc heat treatment technique for producing graded microstructures through controlled temperature gradients
- 2017
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In: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 121:May, s. 11-23
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Journal article (peer-reviewed)abstract
- This paper introduces a novel arc heat treatment technique to produce samples with graded microstructures through the application of controlled temperature gradients. Steady state temperature distributions within the sample can be achieved and maintained, for times ranging from a few seconds to several hours. The technique reduces the number of samples needed to characterize the response of a material to thermal treatments, and can consequently be used as a physical simulator for materials processing. The technique is suitable for conventional heat treatment analogues, welding simulations, multi-step heat treatments, and heat treatments with controlled heating and cooling rates. To demonstrate this technique, a super duplex stainless steel was treated with a stationary TIG arc, to confirm the relationship between generated steady-state temperature fields, microstructure development, hardness, and sensitization to corrosion. Metallographic imaging and hardness mapping provided information about graded microstructures, confirming the formation of secondary phases and microstructure sensitization in the temperature range 850–950 °C. Modelling of temperature distributions and thermodynamic calculations of phase stabilities were used to simulate microstructure development and associated welding cycles.
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| 9. |
- Hosseini, Vahid, et al.
(author)
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Effect of multipass TIG welding on the corrosion resistance and microstructure of a super duplex stainless steel
- 2017
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In: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 68:4, s. 405-415
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Journal article (peer-reviewed)abstract
- This is a study of the effect of repetitive TIG (tungsten inert gas) welding passes, melting and remelting the same material volume on microstructure and corrosion resistance of 2507 (EN 1.4410) super duplex stainless steel. One to four weld passes were autogenously (no filler added) applied on a plate using two different arc energies and with pure argon shielding gas. Sensitization testing showed that multipass remelting resulted in significant loss of corrosion resistance of the weld metal, in base material next to the fusion boundary, and in a zone 1 to 4 mm from the fusion boundary. Metallography revealed the main reasons for sensitization to be a ferrite-rich weld metal and precipitation of nitrides in the weld metal, and adjacent heat affected zone together with sigma phase formation at some distance from the fusion boundary. Corrosion properties cannot be significantly restored by a post weld heat treatment. Using filler metals with higher nickel contents and nitrogen containing shielding gases, are therefore, recommended. Welding with a higher heat input and fewer passes, in some cases, can also decrease the risk of formation of secondary phases and possible corrosion attack.
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| 10. |
- Hosseini, Vahid, 1987-, et al.
(author)
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Ferrite content measurement in super duplex stainless steel welds
- 2019
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In: Welding in the World. - : Springer Verlag. - 0043-2288 .- 1878-6669. ; 63:2, s. 551-563
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Journal article (peer-reviewed)abstract
- Approaches to determining ferrite fraction (%) and ferrite number (FN) were examined for super duplex stainless steel (SDSS) welds. A reference sample was produced by bead-on-plate gas–tungsten arc welding of a type-2507 SDSS plate. By comparing different etchants and measurement practices, it was realized that etching with modified Beraha followed by computerized image analysis (IA) was the most accurate and quickest technique to measure ferrite fraction, which determined the same ferrite fraction (68.0 ± 2.6%) as that measured by electron diffraction backscattered analysis (67.6 ± 2.3%). A Round Robin test was performed on a reference sample at University West, Swerea KIMAB, Outokumpu Stainless, and Sandvik Materials Technology to investigate the repeatability of the technique. The ferrite fraction measurements performed at different laboratories showed very small variations, which were in the range of those seen when changing microscope in the same laboratory. After verification of the technique, the relationship between ferrite fraction and ferrite number (measured with FERITSCOPE®) was determined using 14 single (root) pass welds, including butt, corner, and T-, V-, and double V-joint geometries. The best-fit equation found in this study was ferrite number (FN) = 1.1 × ferrite fraction (%). To conclude, the ferrite fraction technique suggested in the present paper was accurate and repeatable, which made it possible to determine a ferrite fraction–ferrite number formula for SDSS single-pass welds.
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| 11. |
- Hosseini, Vahid, et al.
(author)
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Multipass Autogenous TIG Welding of Super Duplex Stainless
- 2015
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In: 16th national conference of welding and inspection, Yazd, Iran. - Yazd. - 9786001363009
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Conference paper (peer-reviewed)abstract
- Multipass welding of super duplex stainless steels (SDSS) needs further characterization due to their growing applications inpetrochemical and offshore industries. This study, as a result, is aimed at investigating the effects of the number of passesand the arc energy on the microstructure and properties of 2507-type SDSS (UNS S32750). From one to four TIG weldpasses were autogenously applied on a plate using two different arc energies and with pure argon gas as the shielding gas.Chemical analysis showed increasing nitrogen loss with an increasing number of passes and increasing arc energy.Microstructural analyses revealed formation of nitrides in the weld metal and heat affected zone, and sigma phase at somedistance from the fusion boundary. Thermal cycle analysis in combination with Thermo-Calc calculations indicated thatexcessive reheating cause degradation of corrosion properties of multipass weldments, by reducing the pitting resistanceequivalent number of austenite to less than 40. Multipass welding resulted in a more ferritic weld metal microstructure and anincreased hardness.Recommendations, based on the present study, are as follows: 1) Corrosion attack can occur not only in the weld zone andnext to the fusion boundary, but also in a location at some distance from the fusion zone due to reheating in the sigma phaseformation temperature range. This should be considered in inspection procedures 2) Nitrogen loss degrades the mechanicaland corrosion properties of weldments even when welding with a low heat input. Using filler metals with higher nickelcontents and nitrogen containing shielding gases are therefore recommended. 3) It is often recommended to use a heat inputin the lower end of the recommended 0.3-1.5 kJ/mm range in multipass welding of super duplex stainless steels. However,welding with a higher heat input and fewer passes, in some cases, can decrease the risk of formation of secondary phases.
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| 12. |
- Hosseini, Vahid, 1987-, et al.
(author)
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Predicting ferrite fractions in single pass super duplex stainless steel welds : thermal cycle analysis and phase transformation modeling
- 2019
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In: ESSC and DUPLEX 2019. - Wien : Austrian Society for Metallurgy and Materials (ASMET). ; , s. 180-197
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Conference paper (peer-reviewed)abstract
- The relationship between welding process parameters, welding thermal cycle, and the final microstructure is of great importance for reliable fabrication of welded super duplex stainless steels (SDSS) structures. The present study was primarily aimed at investigating the relationship for root/single pass welding of type 2507 SDSS. Fourteen welds were produced using GMAW, GTAW, SAW, and SMAW with different joints geometries, plate thicknesses, and welding parameters. Thermal cycles were recorded using several thermocouples attached to the plates and thermocouples were also harpooned into the weld pool. Weld pool geometries and base metal dilution in the weld metal were determined for all welds. The general trend was that the ferrite fraction of the weld zone increased with increasing cooling rate and base metal dilution in the weld metal. The ferrite fraction was in the range 49-64% for all welds. Kinetics of austenite formation was modeled using computational thermodynamics (Thermo-Calc & DICTRA) to predict the ferrite fractions in the weld zone and calculated fractions were in good agreement with experimental results. Some conflicting results showed that in addition to dilution and cooling rate, the possible nitrogen loss must be taken into account when evaluating and predicting ferrite fraction. It was concluded that the above approach can be used for prediction of the ferrite fraction of super duplex stainless steel single pass welds. Â 2019 ESSC and DUPLEX 2019 - 10th European Stainless Steel Conference - Science and Market, 6th European Duplex Stainless Steel Conference and Exhibition. All rights reserved.
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| 13. |
- Hosseini, Vahid, 1987-, et al.
(author)
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Wire-arc additive manufacturing of a duplex stainless steel : thermal cycle analysis and microstructure characterization
- 2019
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In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 63:4, s. 975-987
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Journal article (peer-reviewed)abstract
- The evolution of microstructures with thermal cycles was studied for wire-arc additive manufacturing of duplex stainless steel blocks. To produce samples, arc energy of 0.5kJ/mm and interlayer temperature of 150 degrees C were used as low heat input-low interlayer temperature (LHLT) and arc energy of 0.8kJ/mm and interlayer temperature of 250 degrees C as high heat input-high interlayer temperature (HHHT). Thermal cycles were recorded with different thermocouples attached to the substrate as well as the built layers. The microstructure was analyzed using optical and scanning electron microscopy. The results showed that a similar geometry was produced with 14 layers4 beads in each layerfor LHLT and 15 layers3 beads in each layerfor HHHT. Although the number of reheating cycles was higher for LHLT, each layer was reheated for a shorter time at temperatures above 600 degrees C, compared with HHHT. A higher austenite fraction (+8%) was achieved for as-deposited LHLT beads, which experienced faster cooling between 1200 and 800 degrees C. The austenite fraction of the bulk of additively manufactured samples, reheated several times, was quite similar for LHLT and HHHT samples. A higher fraction of secondary phases was found in the HHHT sample due to longer reheating at a high temperature. In conclusion, an acceptable austenite fraction with a low fraction of secondary phases was obtained in the bulk of wire-arc additively manufactured duplex stainless steel samples (35-60%), where higher austenite fractions formed with a larger number of reheating cycles as well as longer reheating at high peak temperatures (800-1200 degrees C).
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| 14. |
- Johnson, Ann-Christin, et al.
(author)
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Influence of well-known risk factors for hearing loss in a longitudinal twin study
- 2017
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In: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 56, s. 63-73
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The aim was to investigate the influence of environmental exposures on hearing loss in a twin cohort.STUDY SAMPLE: Male twins born 1914-1958, representing an unscreened population, were tested for hearing loss at two occasions, 18 years apart.DESIGN: Clinical audiometry and a questionnaire were performed at both time points in this longitudinal study. Noise and solvent exposure were assessed using occupational work codes and a job exposure matrix. Hearing impairment was investigated using two different pure tone averages: PTA4 (0.5, 1, 2, and 4 kHz) and HPTA4 (3, 4, 6, and 8 kHz).RESULTS: Age affected all outcome measures. Noise exposure between time point one and two affected the threshold shifts of PTA4 and HPTA4 more in participants with a pre-existing hearing loss at time point one. Lifetime occupational noise exposure was a risk factor especially for the low-frequency hearing threshold PTA4. Firearm use was a statistically significant risk factor for all outcome measures.CONCLUSIONS: Pre-existing hearing loss can increase the risk of hearing impairment due to occupational noise exposure. An increased risk for NIHL was also seen in the group with exposures below 85 dB(A), a result that indicates awareness of NIHL should be raised even for those working in environments where sound levels are below 85 dB(A).
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Karlsson, Johanna, et al.
(author)
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Effects of replacing wheat starch with glycerol on methane emissions, milk production, and feed efficiency in dairy cows fed grass silage-based diets
- 2019
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 102, s. 7927-7935
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Journal article (peer-reviewed)abstract
- To lower the effect of climate change from cattle production, we should aim at decreasing their enteric methane emissions per kilogram of milk or meat. Glycerol may be absorbed through the rumen epithelium and would consequently be less available to microbes in the rumen. Glycerol could thus supply dairy cows with energy for milk production without contributing much to methane production. This study evaluated the effect of replacing wheat starch with glycerol on milk production, feed intake, and methane emissions. Twenty-two Swedish Red cows in mid lactation were used in a switch-back, change-over experiment with 3 periods of 21 d. The 2 dietary treatments consisted of a total mixed ration based on (g/kg of dry matter) grass silage (605), rapeseed meal (120), and barley (70) and either wheat starch or refined glycerol (200) fed ad libitum. The glycerol diet resulted in higher dry matter intake (21.6 vs. 20.1 kg/d) and methane emissions (482 vs. 423 g/d) compared with the diet containing wheat starch, whereas no difference was found in energy-corrected milk yield (28.4 vs. 29.7 kg/d). These results indicate that when glycerol is mixed with the feed, it is available to rumen microbes to a larger extent than initially assumed. Compared with wheat starch, adding refined glycerol (200 g/kg of dry matter) to the feed of dairy cows does not seem to have the potential to decrease enteric methane emissions.
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| 20. |
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| 21. |
- Karlsson, Johanna, et al.
(author)
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Ensilageintag och mjölkproduktion med lite kraftfoder i tidig laktation
- 2017
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In: Report from the Department of Crop Production Ecology (VPE). - 1653-5375. ; , s. 71-74
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Conference paper (peer-reviewed)abstract
- Efterfrågan på livsmedel förväntas öka globalt och idag utfodras mjölkkor med stora mängder produkter som lika gärna kunde ha konsumerats direkt av människor. Detta försök undersökte produktionseffekter när kor i tidig laktation fick en liten giva av kraftfoder baserat på fodermedel som inte kan nyttjas som humanföda. Tjugofyra mjölkkor ingick i försöket där hälften av korna erbjöds en liten kraftfodergiva (max 4–5 kg/dag) och den andra hälften en stor kraftfodergiva (max 14–15 kg/dag). De fick dessutom fri tillgång till vallensilage. Det var ingen skillnad i mjölkavkastning, mjölksammansättning eller totalt foderintag mellan grupperna, men nettoproduktionen av livsmedel samt mjölkintäkt minus foderkostnad var större med en låg andel kraftfoder i foderstaten.
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| 22. |
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| 23. |
- Karlsson, Johanna, et al.
(author)
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Replacing cereals and soybean meal with sugar beet pulp and rapeseed meal or distiller´s grain in grass silage diets to dairy cows
- 2016
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In: Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård. - 0347-9838. ; , s. 82-86
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Conference paper (peer-reviewed)abstract
- Introduction Large volumes of human-edible products as cereal grains and soya beans are fed to dairy cows in intensive production systems (Eisler et al., 2014). Given the predicted increase in demand for livestock products and competition of land for food and feed, human inedible feeds are becoming increasingly important. Ruminants have a unique ability to produce high quality food, as milk and meat, from fibrous feed and other products not suitable for human consumption. Substituting human edibles with by-products as feed for ruminants substantially increase the net food production (human edible output minus human edible input) (Ertl et al., 2016). The aim of this study was to investigate the effects on feed intake and milk production when human-edible feeds as cereal grain and soy beans was completely substituted with different blends of by-products as sugar beet pulp, rape seed meal and distillers grains in a high quality forage diet.
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| 24. |
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| 25. |
- Karlsson, Johanna, et al.
(author)
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Replacing human-edible feed ingredients with by-products increases net food production efficiency in dairy cows
- 2018
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In: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 101, s. 7146-7155
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Journal article (peer-reviewed)abstract
- Global demand for food is increasing, and use of large amounts of potentially human-edible feedstuffs for dairy cows is an important concern. The present study examined whether feeding a by-product-based concentrate combined with high-quality grass silage to high-producing dairy cows affected feed intake and milk production compared with a conventional diet, as well as the effect on efficiency of human food production. In a changeover experiment with four 21-d periods, 24 dairy cows in mid-lactation were offered 9.6 kg of dry matter per day with 1 of 4 concentrates and highquality grass silage ad libitum. The control concentrate was based on cereal grain (wheat, oat, and barley) and soybean meal, whereas the 3 by-product-based concentrates contained sugar beet pulp in combination with mainly heat-treated rapeseed meal, distillers grain, or a mixture of both. All diets were formulated to be isoenergetic and isonitrogenous. The cows had 10-fold higher starch intake when fed the control diet than when fed the by-product-based concentrates. Silage intake (13 kg of dry matter/d) and milk production (33 kg of energy-corrected milk/d) were not affected by the change in diet. Therefore, replacing cereals and soybean meal with human-inedible by-products in a high-quality forage diet to dairy cows increased net food protein production substantially without lowering milk production.
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| 26. |
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| 27. |
- Karlsson, Therese, 1987, et al.
(author)
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Undersökning av mikroskräp längs bohuslänska stränder och i sediment
- 2019
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Reports (other academic/artistic)abstract
- Mikroplast och andra mikroskräpspartiklar såsom paraffin hittas i miljöprover över hela världen. En stor del av provtagningarna sker i ytvatten och det har gett oss många insikter kring förekomst och transport. På grund av en snabb omsättning och ofta låga antal partiklar per prov är det dock svårt att använda ytvattenprov för analys av mikroskräpssammansättningen. Sammansättningen är dock en viktig komponent för att ge underlag till att utröna såväl källmönster som riskanalyser.Majoriteten av plasten förväntas sjunka eller hamna på stränder. Därför undersöker vi här prover från stränder och sediment på den svenska västkusten. I studien ingår prover från tre exponerade stränder; Tjällsö, Skaftö och Ramsvik, tre stadsnära stränder; Göteborg, Stenungssund och Uddevalla samt prover i sediment utanför Stenungssund.På stränderna provtogs två sorters prover. Ackumulationsprover; prover som togs där skräpet visuellt kunde konstateras ha samlats, och poolade prover; prover där mindre volymer togs över ett större område och lades ihop till ett prov. Ackumulationsproverna togs för att öka chansen att få tillräckligt högt partikelantal och de poolade proverna togs för att ge mer representativa prover för föroreningsnivån på de olika stränderna. Proverna storleksfraktionerades och analyser gjordes visuellt i ljusmikroskop av fraktionerna 1-5 mm, 0,5-1 mm och 0,3-0,5 mm. Vissa partikeltyper analyserades även i FTIR för att även ge materialtyp. Lågt partikelantal i vissa av proverna belyser vikten av att anpassa provvolymen, medan analys av större provvolymer emellertid kan kräva extraktionsmetoder för att analyserna sak bli kostnadseffektiva. På grund av källornas komplexitet ges en så fullständig bild som om miljöanalyser av mikro och makroskräp, geografiska föroreningsmönster samt massbalansberäkningar kombineras. Vid mer specifika frågeställningar om särskilda källor så bör provtagning och analysmetod anpassas specifikt, utifrån storleksfördelning, partikeldensitet och polymertyper. Extraktion av mikroskräp från sedimentproverna är relativt väl utvecklat för miljöövervakning men analysen på mindre storleksfördelningar behöver utvecklas för att bryta ner naturligt material för att underlätta analysen.Resultaten indikerar att strandprover kan vara lämpliga för analys av sammansättningen av flytande mikroskräp, medan sediment är lämpliga för sjunkande partiklar, framförallt de polymerer som har en högre densitet i polymeren men även material som initialt flyter men som sedan på grund av degradationsprocesser och biofilm sjunker.Resultaten från strandproverna visade på höga koncentrationer av mikroskräp; i de poolade proverna låg de mellan 4 000 och 100 000 partiklar över 300 μm per kg torrvikt och koncentrationerna i ackumulationsproverna var upp till 70 gånger högre. Vanligast i samtliga prover var olika typer av plastfragment. Bland dessa var transparanta och semitransparenta fragment de allra vanligaste. De är svåra att spåra till specifika källor, vissa ledtrådar kan dock ges genom att undersöka sammansättningen av större skräp och återkommande resultat av strandinventeringar visar att en stor mängd av skräpet som hittas på svenska stränder är förpackningsplast.På stränderna var expanderad cellplast också en viktig kategori bland fragmenten. Framförallt på de urbana stränderna där de utgjorde en stor del av den identifierade mikroplasten. Åtgärder mot användningen av expanderad polystyren (EPS) i vissa engångartiklar har redan diskuterats på EU-nivå. Merparten av den expanderade polystyrenen som används i Europa används dock till byggmaterial. Det kan därför vara meningsfullt att se över regler om emballage och hantering av EPS och rutiner vid byggnadsarbeten för att säkerhetsställa att minimalt spill sker vid transport, lagring och bearbetning.8Bland de mikroplaster på stränder som inte tycktes vara fragmenterade så var plasttyper kopplat till produktion av plast en betydande del. Antalskoncentrationerna var högre i mindre storleksfraktioner. Den sortens mindre partiklar kan antas vara svårare att undvika spill utav än pellets. Det visar på vikten av att inkludera implementeringen av goda rutiner, miljötillsyn och uppföljning vid produktion, transport och lagring av plastmaterial.En annan återkommande kategori var mikrosfärer. Flera partiklar identifierades som polymetylmetacrylat medan vissa gav liknande spektra som glas. Tidigare studier har även hittat mikrosfärer av polystyren. Mikrosfärer kan därför antas förekomma i olika material med olika sammansättningar. Flera sorter tycks dock hamna i miljön vilket innebär att en översyn av användningsområden kan ge utökad kunskap kring vilka preventiva åtgärder som kan tas för att begränsa spill under produktion, transport, lagring och även användning. Referens bör även ges till det regelverksrevision av primär mikroplast som ECHA arbetar med.Paraffin var också en viktig skräpkategori som utgjorde 21 % av mikroskräpspartiklarna. Det kan därför vara värt att överväga de risker som paraffin kan utgöra samt undersöka möjligheter till att begränsa läckaget av paraffin till miljön.Mikroskräpskategorierna i sediment som gav kompletterade bild av viktiga källor var däckslitagepartiklar, fibrer, industrispill av PVC, samt färgade partiklar som till viss del kan vara färgpartiklar. Men även i sedimenten var de semitransparenta fragmenten av huvudsakligen PP och PE betydande.En litteraturjämförelse mellan sedimentmätningar i denna studie med övriga globala mätningar, visar att dessa svenska, med närliggande urbana-industriella källor, är bland de högsta förekomster som rapporterats från marina sediment. En jämförelse med kunskapsläget kring preliminär riskbedömning är inkluderad.Således sammantaget var majoriteten av partiklarna i sedimentproverna och på stränderna plastfragment. Det innebär att åtgärdsprogram utformade för att minska mängden mikroskräp i miljön bör inkludera åtgärder mot makroskräp med fokus på i) minskning av viss användning, ii) minimering av hantering utomhus, iii) barriärer för läckage och spridning, iv) uppstädningsåtgärder, ej endast på stränder utan även mer nära källorna eller spridningspunkterna.
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| 28. |
- Larsson, Kjell, Professor, 1958-, et al.
(author)
-
Fartygstrafik i och nära skyddade och känsliga havsområden runt Gotland och Öland
- 2018
-
Reports (other academic/artistic)abstract
- Den internationella fartygstrafiken i Östersjön och inte minst i havsområdet runt Gotland och Öland är mycket intensiv och förväntas öka i omfattning under kommande år. Sjöfarten behöver tillgång till utrymme på havet i form av ändamålsenliga och säkra fartygsrutter. Intensiv fartygstrafik medför dock påverkan på havsmiljön på grund av driftsrelaterade utsläpp till luft och vatten. Intensiv trafik medför även risker för kollisioner, grundstötningar och andra fartygsolyckor som kan ge upphov till mycket stor miljöpåverkan. Sverige har liksom de flesta av världens länder i enlighet med internationella konventioner ett uppdrag att skydda minst 10 % av havet. Införandet av marina reservat och nationalparker innanför svensk territorialgräns, och av marina Natura 2000-områden innanför territorialgräns och i svensk ekonomisk zon enligt nationell lagstiftning och EU-direktiv, är ett led i uppdraget. Andra internationella konventioner reglerar vilka åtgärder som kan vidtas för att styra fartygstrafik eller för att rekommendera sjöfarten att undvika vissa havsområden. Havsplanering är ett verktyg för att styra det rumsliga nyttjandet av havet och för att reducera konflikter mellan olika samhällsintressen, t.ex. mellan behovet av sjöfart och behovet av att skydda havsmiljön och marin biologisk mångfald. För att på ett effektivt sätt kunna havsplanera och förbättra och utöka skyddet av värdefulla marina områden krävs kunskap om den påverkan som mänskliga aktiviteter, bland annat sjöfart, har på områdena. Ett första steg är att identifiera de havsområden där fartygstrafiken är mycket intensiv, där fartyg passerar genom eller nära särskilt känsliga områden, där fartyg med särskilt farlig last passerar eller där många fartyg ankrar under längre perioder. Syftet med rapporten är att sammanställa information om fartygstrafik i och nära skyddade och känsliga havsområden runt Gotland och Öland. I rapporten beskrivs först hur analyser av fartygstrafik kan genomföras med hjälp av lagrade AIS-data. Därefter beskrivs fartygstrafiken i centrala Östersjön och i särskilda fokusområden runt Gotland och Öland. Avslutningsvis diskuteras risker med fartygstrafik i känsliga havsområden och hur konflikter mellan sjöfartens behov och marint områdesskydd kan reduceras. Rapporten har producerats inom projektet ”Marina skyddsvärden runt Gotland och Öland ” som letts av Länsstyrelsen i Gotlands län.
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| 29. |
- Larsson, Kjell
(author)
-
Fartygstrafik i och nära skyddade och känsliga havsområden runt Gotland och Öland
- 2018
-
Reports (other academic/artistic)abstract
- Den internationella fartygstrafiken i Östersjön och inte minst i havsområdet runt Gotland ochÖland är mycket intensiv och förväntas öka i omfattning under kommande år. Sjöfartenbehöver tillgång till utrymme på havet i form av ändamålsenliga och säkra fartygsrutter.Intensiv fartygstrafik medför dock påverkan på havsmiljön på grund av driftsrelateradeutsläpp till luft och vatten. Intensiv trafik medför även risker för kollisioner, grundstötningaroch andra fartygsolyckor som kan ge upphov till mycket stor miljöpåverkan.Sverige har liksom de flesta av världens länder i enlighet med internationella konventioner ettuppdrag att skydda minst 10 % av havet. Införandet av marina reservat och nationalparkerinnanför svensk territorialgräns, och av marina Natura 2000-områden innanför territorialgränsoch i svensk ekonomisk zon enligt nationell lagstiftning och EU-direktiv, är ett led iuppdraget. Andra internationella konventioner reglerar vilka åtgärder som kan vidtas för attstyra fartygstrafik eller för att rekommendera sjöfarten att undvika vissa havsområden.Havsplanering är ett verktyg för att styra det rumsliga nyttjandet av havet och för att reducerakonflikter mellan olika samhällsintressen, t.ex. mellan behovet av sjöfart och behovet av attskydda havsmiljön och marin biologisk mångfald. För att på ett effektivt sätt kunnahavsplanera och förbättra och utöka skyddet av värdefulla marina områden krävs kunskap omden påverkan som mänskliga aktiviteter, bland annat sjöfart, har på områdena. Ett första stegär att identifiera de havsområden där fartygstrafiken är mycket intensiv, där fartyg passerargenom eller nära särskilt känsliga områden, där fartyg med särskilt farlig last passerar ellerdär många fartyg ankrar under längre perioder.Syftet med rapporten är att sammanställa information om fartygstrafik i och nära skyddadeoch känsliga havsområden runt Gotland och Öland. I rapporten beskrivs först hur analyser avfartygstrafik kan genomföras med hjälp av lagrade AIS-data. Därefter beskrivs fartygstrafikeni centrala Östersjön och i särskilda fokusområden runt Gotland och Öland. Avslutningsvisdiskuteras risker med fartygstrafik i känsliga havsområden och hur konflikter mellansjöfartens behov och marint områdesskydd kan reduceras. Rapporten har producerats inomprojektet ”Marina skyddsvärden runt Gotland och Öland ” som letts av Länsstyrelsen iGotlands län.
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| 30. |
- Larsson, Kjell, et al.
(author)
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Population trends and threats from ship traffic to long-tailed ducks in the Baltic Sea
- 2016
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In: Progress in Marine Conservation in Europe 2015. - : Bundesamt für Naturschutz (BfN). - 9783896241887 ; , s. 205-210
-
Conference paper (peer-reviewed)abstract
- The long-tailed duck Clangula hyemalis is a small sea duck that breeds in Arctic tundra regions and winter in marine and brackish waters. Surveys indicate substantial declines in numbers in recent decades and the species is now classified by IUCN as globally threatened in the category “vulnerable”. The largest of the four recognized long-tailed duck populations is the West Siberian / North European population. Birds belonging to the WS/NE population breed in northern Russia and northern Scandinavia and overwinter mainly in the Baltic Sea. An International Single Species Action Plan for the long-tailed duck has also recently been developed by specialists under the auspices of AEWA (Agreement on the Conservation of African-Eurasian Migratory Waterbirds) (HEARN et al. 2015)Two Baltic wide surveys have shown that the WS/NE population has decreased very rapidly from approx. 4.3 million birds in 1992-93 to approx. 1.5 million birds in 2007-2009 (DURINCK et al. 1994; SKOV et al. 2011). Although there is some uncertainty regarding the overall level of the population size estimates it is believed that the difference between the estimates accurately reflects the trend between the mid 1990s and late 2000s. A further decline also after 2009 can be assumed as the mean proportion of juveniles in the wintering population has been low since 2009. The recent decline of the WS/NE population can most likely be explained by a combination of factors affecting both the productivity at the Arctic breeding grounds and the adult mortality in the wintering areas in the Baltic Sea.Four important anthropogenic threats affecting the wintering birds have been recognised, namely,1. operational oil spills from ships at core wintering sites,2. by-catches in fishery,3. hunting and4. disturbance at and exploitation of offshore mussel banks.Mortality due to by-catches has decreased but is still high (BELLEBAUM et al. 2013). Hunting mortality is fairly well known and can be regulated if agreements are reached. Displacement of wintering long-tailed ducks from good feeding areas might be more important in future if planned large scale wind farms will be established at core wintering sites, i.e. at offshore banks.In this note one of the four recognised anthropogenic threats, i.e. the threat from intensive shipping activities is elucidated. More specifically, an analysis of ship traffic within and close to two marine Natura 2000 sites is presented. The analysed sites, the Hoburgs bank and the Northern Midsjö bank, are two of the most important wintering sites for long-tailed ducks in the Baltic Sea. Several hundred thousand long-tailed ducks, which is a significant part of the global population, have been observed wintering within these areas in recent years (SKOV et al. 2011, NILSSON 2012). Possible methods to reduce the threat from ship traffic are also discussed.
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| 31. |
- Martinez-Murillo, Paola, et al.
(author)
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CD138 and CD31 Double-Positive Cells Comprise the Functional Antibody-Secreting Plasma Cell Compartment in Primate Bone Marrow
- 2016
-
In: Frontiers in Immunology. - Lausanne, Switzerland : Frontiers Media S.A.. - 1664-3224. ; 7
-
Journal article (peer-reviewed)abstract
- Plasma cells (PCs) are defined as terminally differentiated B cells that secrete large amounts of immunoglobulin (Ig). PCs that reside in the bone marrow (BM) are responsible for maintaining long-term antibody (Ab) responses after infection and vaccination, while PCs present in the blood are generally short-lived. In rhesus macaques, a species frequently used for the evaluation of human vaccines, B cells resemble those found in humans. However, a detailed characterization of BM-resident rhesus PC phenotype and function is lacking. Here, we examined Ig secretion of distinct rhesus CD138+ populations by B cell ELISpot analysis to couple phenotype with function. We demonstrate that the CD20low/-CD138+CD31+ BM population was highly enriched for antibody-secreting cells with IgG being the predominant isotype (60%), followed by IgA (33%) and IgM (7%). Transmission electron microscopy analysis confirmed PC enrichment in the CD20low/-CD138+CD31+ population with cells containing nuclei with "spokes of a wheel" chromatin structure and prominent rough endoplasmic reticulum. This panel also stained human BM PCs and allowed a clear distinction between BM PCs and short-lived peripheral PCs, providing an improved strategy to isolate PCs from rhesus BM for further analysis.
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| 32. |
- McCarrick, Sarah, et al.
(author)
-
High variability in toxicity of welding fume nanoparticles from stainless steel in lung cells and reporter cell lines : the role of particle reactivity and solubility
- 2019
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In: Nanotoxicology. - : TAYLOR & FRANCIS LTD. - 1743-5390 .- 1743-5404.
-
Journal article (peer-reviewed)abstract
- Millions of people in the world perform welding as their primary occupation resulting in exposure to metal-containing nanoparticles in the fumes generated. Even though health effects including airway diseases are well-known, there is currently a lack of studies investigating how different welding set-ups and conditions affect the toxicity of generated nanoparticles of the welding fume. The aim of this study was to investigate the toxicity of nine types of welding fume particles generated via active gas shielded metal arc welding (GMAW) of chromium-containing stainless steel under different conditions and, furthermore, to correlate the toxicity to the particle characteristics. Toxicological endpoints investigated were generation of reactive oxygen species (ROS), cytotoxicity, genotoxicity and activation of ToxTracker reporter cell lines. The results clearly underline that the choice of filler material has a large influence on the toxic potential. Fume particles generated by welding with the tested flux-cored wire (FCW) were found to be more cytotoxic compared to particles generated by welding with solid wire or metal-cored wire (MCW). FCW fume particles were also the most potent in causing ROS and DNA damage and they furthermore activated reporters related to DNA double- strand breaks and p53 signaling. Interestingly, the FCW fume particles were the most soluble in PBS, releasing more chromium in the hexavalent form and manganese compared to the other fumes. These results emphasize the importance of solubility of different metal constituents of the fume particles, rather than the total metal content, for their acute toxic potential.
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| 33. |
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| 34. |
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| 35. |
- Olsson, Caroline, 1970, et al.
(author)
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Initial experience with introducing national guidelines for CT- and MRI-based delineation of organs at risk in radiotherapy
- 2019
-
In: Physics and Imaging in Radiation Oncology. - : Elsevier. - 2405-6316. ; 11, s. 88-91
-
Journal article (peer-reviewed)abstract
- A fundamental problem in radiotherapy is the variation of organ at risk (OAR) volumes. Here we present our initial experience in engaging a large Radiation Oncology (RO) community to agree on national guidelines for OAR delineations. Our project builds on associated standardization initiatives and invites professionals from all radiotherapy departments nationwide. Presently, one guideline (rectum) has successfully been agreed on by a majority vote. Reaching out to all relevant parties in a timely manner and motivating funding agencies to support the work represented early challenges. Population-based data and a scalable methodological approach are major strengths of the proposed strategy.
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| 36. |
- Rosner, Sabine, et al.
(author)
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Hydraulic and mechanical dysfunction of Norway spruce sapwood due to extreme summer drought in Scandinavia
- 2018
-
In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 409, s. 527-540
-
Journal article (peer-reviewed)abstract
- Projected climate change scenarios such as frequently occurring dry summer spells are an enormous threat to the health of boreal conifer forests. We identified visible features indicating wood with tracheids predisposed for hydraulic and mechanical dysfunction in Norway spruce, suggest why this is formed during severe summer drought and hypothesised on mechanism that would cause tracheid collapse and stem cracks. Trees from southern Sweden that showed signs of severe reaction to drought, i.e. stem cracks along the trunk, were compared to healthy, undamaged trees. Rings investigated included those formed in 2006, a year with an extremely dry summer season in the study region. In southern Norway, we investigated trees with and without drought-induced top dieback symptoms. We analysed anatomical features such as tracheid lumen diameter, thickness of cell wall and its various layers (S1, S2 and S3), applied Raman imaging in order to get information on the lignin distribution in the cell wall and the compound middle lamellae and performed hydraulic flow and shrinkage experiments. Although tracheids in annual rings with signs of collapse had higher tangential lumen diameters than those in “normal†annual rings, we conclude that collapse of tracheid walls depends mainly on wall thickness, which is genetically determined to a large extent. Spruce trees that produce earlywood with extremely thin cell walls can develop wall collapse and internal cracks under the impact of dry spells. We also present a new diagnostic tool for detecting individuals that are prone to cell wall collapse and stem cracks: Lucid bands, i.e. bands in the fresh sapwood with very thin cell walls and inhomogeneous lignin distribution in the S-layers and the compound middle lamellae that lost their hydraulic function due to periods of severe summer drought. The detection of genotypes with lucid bands could be useful for an early selection against individuals that are prone to stem cracks under the impact of severe summer drought, and also for early downgrading of logs prone to cracking during industrial kiln drying.
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| 37. |
- Rådegran, Göran, et al.
(author)
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Characteristics and survival of adult Swedish PAH and CTEPH patients 2000-2014
- 2016
-
In: Scandinavian Cardiovascular Journal. - : Taylor & Francis. - 1401-7431 .- 1651-2006. ; 50:4, s. 243-250
-
Journal article (peer-reviewed)abstract
- OBJECTIVES: The Swedish Pulmonary Arterial Hypertension Register (SPAHR) is an open continuous register, including pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) patients from 2000 and onwards. We hereby launch the first data from SPAHR, defining baseline characteristics and survival of Swedish PAH and CTEPH patients.DESIGN: Incident PAH and CTEPH patients 2008-2014 from all seven Swedish PAH-centres were specifically reviewed.RESULTS: There were 457 PAH (median age: 67 years, 64% female) and 183 CTEPH (median age: 70 years, 50% female) patients, whereof 77 and 81%, respectively, were in functional class III-IV at diagnosis. Systemic hypertension, diabetes, ischaemic heart disease and atrial fibrillation were common comorbidities, particularly in those >65 years. One-, 3- and 5-year survival was 85%, 71% and 59% for PAH patients. Corresponding numbers for CTEPH patients with versus without pulmonary endarterectomy were 96%, 89% and 86% versus 91%, 75% and 69%, respectively. In 2014, the incidence of IPAH/HPAH, associated PAH and CTEPH was 5, 3 and 2 per million inhabitants and year, and the prevalence was 25, 24 and 19 per million inhabitants.CONCLUSION: The majority of the PAH and CTEPH patients were diagnosed at age >65 years, in functional class III-IV, and exhibiting several comorbidities. PAH survival in SPAHR was similar to other registers.
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| 38. |
- Svensson, Lars-Erik, 1951-, et al.
(author)
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Strength and Impact Toughness of High Strength Steel Weld Metals : Influence of Welding Method, Dilution and Cooling Rate
- 2015
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In: Proceedings of IIW International Conference, High-Strength Materials. - Helsingfors. ; , s. 1-9
-
Conference paper (peer-reviewed)abstract
- Producing welds with properties matching those of the steel is a challenge at high strength levels. The present study has investigated how the choice of welding method affects weld metal mechanical properties through effects on dilution and cooling rate. Butt welds were produced in 12 mm plates in 777 MPa and 1193 MPa yield strength steels. Conventional arc welding methods including manual metal arc, gas metal arc welding, rapid arc welding and submerged arc welding were used as well as laser-gas metal arc hybrid welding. Filler materials with nominal yield strengths between 810 and 1000 MPa were used. Cooling times between 800 C and 500 C were varied between 5s and 15s and measured by insertion of thermocouples into the weld pool.High quality welds were produced efficiently with all welding methods even though dilution varied between 3%, for manual metal arc welding, to 73% for laser-hybrid welding. Low dilution, rapid cooling and single pass welding contributed to higher strength. Overmatching weld metal strength was achieved for the less strong steel and weld yield strengths of >1000 MPa were recorded for the stronger steel. Fracture in transverse tensile testing was always located in base material or HAZ. Impact toughness was higher for lower strength and low dilution. Results are discussed relating choice of welding method and cooling rate to weld metal properties for different steel strength levels.
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| 39. |
- Söder, Josefin, et al.
(author)
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Metabolic and Hormonal Response to a Feed-challenge Test in Lean and Overweight Dogs
- 2016
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In: Journal of Veterinary Internal Medicine. - : Wiley. - 0891-6640 .- 1939-1676. ; 30, s. 574-582
-
Journal article (peer-reviewed)abstract
- BackgroundObese dogs risk poor life quality, creating a need for increased knowledge of metabolism in overweight dogs.ObjectivesInvestigate postprandial metabolic and hormonal responses to a high-fat mixed-meal in dogs and responses of lean versus overweight dogs.AnimalsTwenty-eight healthy intact male Labrador Retrievers were included.MethodsProspective observational study. Twelve dogs were grouped as lean (body condition score (BCS 4-5), 10 as slightly overweight (BCS 6), and 6 as overweight (BCS 6.5-8) on a 9-point scale. After an overnight fast, urine and blood samples were collected. Dogs were then fed a high-fat mixed-meal, and blood was collected hourly for 4 hours and urine after 3 hours.ResultsPostprandial concentrations of insulin and glucagon were increased at 1 hour (both P < 0.0001), triglycerides at 2 hours (P < 0.0001), and glucose at 3 hours (P = 0.004); and all remained increased throughout the feed-challenge in all dogs. Postprandial urine cortisol/creatinine ratio was higher than fasting values (P = 0.001). Comparing between groups, there was an overall higher triglyceride response in overweight compared to lean (P = 0.001) and slightly overweight (P = 0.015) dogs. Overweight dogs also had higher fasting cortisol/creatinine ratio compared to lean dogs (P = 0.024).Conclusions and Clinical ImportancePostprandial responses of dogs to a high-fat mixed-meal were similar to those previously reported in people. The higher postprandial triglyceride response and fasting cortisol/creatinine ratio in the overweight dogs could be early signs of metabolic imbalance. Thus, although overweight dogs often appear healthy, metabolic alterations might be present.
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| 40. |
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| 41. |
- Tyler, Andreas, et al.
(author)
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Targeting glucosylceramide synthase induction of cell surface globotriaosylceramide (Gb3) in acquired cisplatin-resistance of lung cancer and malignant pleural mesothelioma cells
- 2015
-
In: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 336:1, s. 23-32
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Acquired resistance to cisplatin treatment is a caveat when treating patients with non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). Ceramide increases in response to chemotherapy, leading to proliferation arrest and apoptosis. However, a tumour stress activation of glucosylceramide synthase (GCS) follows to eliminate ceramide by formation of glycosphingolipids (GSLs) such as globotriaosylceramide (Gb3), the functional receptor of verotoxin-1. Ceramide elimination enhances cell proliferation and apoptosis blockade, thus stimulating tumor progression. GSLs transactivate multidrug resistance 1/P-glycoprotein (MDR1) and multidrug resistance-associated protein 1 (MRP1) expression which further prevents ceramide accumulation and stimulates drug efflux. We investigated the expression of Gb3, MDR1 and MRP1 in NSCLC and MPM cells with acquired cisplatin resistance, and if GCS activity or MDR1 pump inhibitors would reduce their expression and reverse cisplatin-resistance.METHODS: Cell surface expression of Gb3, MDR1 and MRP1 and intracellular expression of MDR1 and MRP1 was analysed by flow cytometry and confocal microscopy on P31 MPM and H1299 NSCLC cells and subline cells with acquired cisplatin resistance. The effect of GCS inhibitor PPMP and MDR1 pump inhibitor cyclosporin A for 72h on expression and cisplatin cytotoxicity was tested.RESULTS: The cisplatin-resistant cells expressed increased cell surface Gb3. Cell surface Gb3 expression of resistant cells was annihilated by PPMP whereas cyclosporin A decreased Gb3 and MDR1 expression in H1299 cells. No decrease of MDR1 by PPMP was noted in using flow cytometry, whereas a decrease of MDR1 in H1299 and H1299res was indicated with confocal microscopy. No certain co-localization of Gb3 and MDR1 was noted. PPMP, but not cyclosporin A, potentiated cisplatin cytotoxicity in all cells.CONCLUSIONS: Cell surface Gb3 expression is a likely tumour biomarker for acquired cisplatin resistance of NSCLC and MPM cells. Tumour cell resistance to MDR1 inhibitors of cell surface MDR1 and Gb3 could explain the aggressiveness of NSCLC and MPM. Therapy with GCS activity inhibitors or toxin targeting of the Gb3 receptor may substantially reduce acquired cisplatin drug resistance of NSCLC and MPM cells.
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| 42. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel
- 2019
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In: Applied Sciences. - : MDPI. - 2076-3417. ; 9:6
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Journal article (peer-reviewed)abstract
- Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW) processes. Recommended and higher arc energies and inter-pass temperatures were used. Thermal cycles were monitored using a recently developed procedure involving the successive instrumentation of the multi-pass welds, pass by pass, by addition of thermocouples in each weld pass. The repeatability of temperature measurements and survival rate of more than 90% of thermocouples confirmed the reliability of the procedure. Reheating by subsequent passes caused a progressive increase in the austenite content of the weld metal. The as-deposited GMAW passes with higher-than-recommended arc energy showed the lowest presence of nitrides. Therefore, the cooling rate—and not the time exposed at the critical temperature range—seems to be the key factor for nitride formation. The welding sequence layout also plays an important role in the distribution of secondary phases. A larger amount and concentration of secondary austenite and σ-phase was found for a larger number of subsequent passes in the immediate vicinity of a specific weld pass. The impact toughness exceeded requirements for all welds. Differences in absorbed energies were related to the amount of micro-inclusions found with the FCAW weld showing the lowest absorbed energies and highest amount of micro-inclusions. Pitting corrosion preferentially initiated in locations with secondary austenite and σ-phase. However, in the absence of these secondary phases, the HAZ containing nitrides was the weakest location where pitting initiated. The results of this work have implications on practical welding for superduplex stainless steels: the current recommendations on maximum arc energy should be revised for large thickness weldments, and the importance of the welding sequence layout on the formation of secondary phases should be considered.
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| 43. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds
- 2015
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In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 59:2, s. 239-249
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Journal article (peer-reviewed)abstract
- The influence of shielding gases on welding performanceand on properties of duplex and superduplex stainlesssteel welds was studied. Using argon as the reference gas,helium, nitrogen and carbon dioxide were added and fivemixtures evaluated. Bead-on-plate welds and circumferentialpipe welds were produced using mechanisedGMAwelding inthe downhand position. Welding performance, corrosion resistance,mechanical properties, microstructural features andweld imperfections were assessed and related to the shieldinggas. Shielding gases containing 30 % helium showed excellentresults; whilst pure argon showed unstable arc and poorweld pool fluidity and Ar+2 %CO2 resulted in underfill andporosity. Mixtures containing helium resulted in higher ductilitywelds and higher impact toughness values than weldsproduced with Ar+2 %CO2. Sound and balanced duplexmicrostructures free from intermetallics were found with suitableferrite contents for all the shielding gases studied. All theduplex pipe welds passed the corrosion test regardless of theshielding gas used, and the best results in the corrosion test forsuperduplex pipe welds were found when using Ar+30 %He+0.5 %CO2+1.8 %N2 as shielding gas.
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| 44. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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Effect of welding position on properties of duplex and superduplex stainless steel circumferential welds
- 2015
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In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 59:5, s. 693-703
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Journal article (peer-reviewed)abstract
- The influence of welding position on properties ofduplex and superduplex stainless steel welds was studied. Circumferential pipe welds were produced using mechanised gasmetal arc welding in flat position, vertical up position and overhead position. Dilution, corrosion resistance, mechanical properties, microstructural features and weld imperfections were assessed and related to the welding position. Welds produced in flat and vertical up positions were less likely to produce porosity than those welded in overhead position, whilst underfill was not observed in overhead position welds. All the duplex pipe welds passed the corrosion test regardless of the welding position and showed sound microstructures. Under fixed arc energy conditions, welds produced in vertical up position showed the lowest dilution values whilst welds in flat position showed the highest. Excellent impact toughness values and cross tensile values were found regardless of the welding positions. Whenever possible, flat position is recommended as welds showed less proneness to porosity. Vertical up position is recommended as the second best choice.
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| 45. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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Influenza del gas di protezione sul comportamento e le proprietà di giunti sa dati di acciai duplex e superduplex : Effect of shielding gas on welding performance and properties of duplex and superduplex stainless steel welds
- 2016
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In: Rivista Italiana della Saldatura. - : Istituto Italiano della Saldatura. - 0035-6794. ; 68:5, s. 635-650
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Journal article (other academic/artistic)abstract
- The influence of shielding gases on welding performance and on properties of duplex and superduplex stainless steel welds was studied. Using argon as the reference gas, helium, nitrogen and carbon dioxide were added and five mixtures evaluated. Bead-on-plate welds and circumferential pipe welds were produced using mechanised GMA welding in the downhand position. Welding performance, corrosion resistance, mechanical properties, microstructural features and weld imperfections were assessed and related to the shielding gas. Shielding gases containing 30% helium showed excellent results; whilst pure argon showed unstable arc and poor weld pool fluidity and Ar + 2% CO2resulted in underfill and porosity. Mixtures containing helium resulted in higher ductility welds and higher impact toughness values than welds produced with Ar + 2% CO2. Sound and balanced duplex microstructures free from intermetallics were found with suitable ferrite contents for all the shielding gases studied. All the duplex pipe welds passed the corrosion test regardless of the shielding gas used, and the best results in the corrosion test for superduplex pipe welds were found when using Ar + 30%He + 0.5% CO2+ 1.8% N2as shielding gas.
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| 46. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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Monitoring Thermal Cycles in Multi-pass Welding
- 2016
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In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - : Swedish Production Academy. ; , s. 1-5
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Conference paper (peer-reviewed)abstract
- Differently from any previous investigation in welding, this research work presents a novel development that allows temperature to be measured and recorded simultaneously with up to 32 thermocouples indifferent locations of a welding joint. Four experiments were designed to optimise the measurement technique by comparing the performance of three types of thermocouples (K, N, C) insulated with different materials and varying the insertion technique of the thermocouples in the joint. Results showed that type-K thermocouple had the best performance and proved that glass fibre insulation provided better protection than Inconel. The optimised measurement procedure developed in this work enables to monitor the thermal cycles in multi-pass welds. That information is essential in multi-pass welding of materials such as super duplex stainless steels, carbon steels or nickel alloys, as heating them repeatedly makes them susceptible to the formation of brittle phases and in turn it influences their mechanical and corrosion properties. This technique could be really important for future applications such as temperature modellingor prediction of mechanical properties and microstructure in relation to the thermal cycle experienced by alloys susceptible to the formation of undesirable phases.
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| 47. |
- Valiente Bermejo, María Asunción, 1972-, et al.
(author)
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Towards a Map of Solidification Cracking Risk in Laser Welding of Austenitic Stainless Steels
- 2015
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In: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 230-239
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Journal article (peer-reviewed)abstract
- In this work, two series of specimens with Hammar and Svensson's Cr- and Ni-equivalents (Creq+Nieq) = 35 and 45 wt% were used to cover a wide range of austenitic grades. These were laser welded with different energy inputs achieving cooling rates in the range of 103 °C/s to 104 °C/s. As high cooling rates and rapid solidification conditions could favour fully austenitic solidification and therefore raise susceptibility to solidification cracking, the solidification modes of the laser welded specimens were compared to the ones experienced by the same alloys under arc welding conditions. It was found that high cooling rates experienced in laser welding promoted fully austenitic solidification for a wider range of compositions, for example specimens with (Creq+Nieq) = 35% under arc welding cooling conditions at 10 °C/s showed fully austenitic solidification up to Creq/Nieq = 1.30, whilst the same specimens laser cooled at 103 °C/s showed fully austenitic solidification up to Creq/Nieq = 1.50 and those cooled at 104 °C/s showed it up to Creq/Nieq = 1.68. Therefore, high cooling rates extended the solidification cracking risk to a wider range of Creq/Nieq values. This work also compares the cooling rates experimentally determined by thermocouples to the computed cooling rates calculated by a highly-advanced computational model. The distance between the thermocouple's wires and the thermal resistance of thermocouples together with the small size of the weld pools proved to be practical limitations in the experimental determination of cooling rates. However, an excellent agreement was found between computed and experimental solidus isotherms at high energy input settings. For low energy input settings cooling rate was in the order of magnitude of 104 °C/s, whilst for high energy input settings cooling rate was found to be in the order of magnitude of 103 °C/s.
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| 48. |
- Ågerstam, Helena, et al.
(author)
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Antibodies targeting human IL1RAP (IL1R3) show therapeutic effects in xenograft models of acute myeloid leukemia.
- 2015
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In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 112:34, s. 10786-10791
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Journal article (peer-reviewed)abstract
- Acute myeloid leukemia (AML) is associated with a poor survival rate, and there is an urgent need for novel and more efficient therapies, ideally targeting AML stem cells that are essential for maintaining the disease. The interleukin 1 receptor accessory protein (IL1RAP; IL1R3) is expressed on candidate leukemic stem cells in the majority of AML patients, but not on normal hematopoietic stem cells. We show here that monoclonal antibodies targeting IL1RAP have strong antileukemic effects in xenograft models of human AML. We demonstrate that effector-cell-mediated killing is essential for the observed therapeutic effects and that natural killer cells constitute a critical human effector cell type. Because IL-1 signaling is important for the growth of AML cells, we generated an IL1RAP-targeting antibody capable of blocking IL-1 signaling and show that this antibody suppresses the proliferation of primary human AML cells. Hence, IL1RAP can be efficiently targeted with an anti-IL1RAP antibody capable of both achieving antibody-dependent cellular cytotoxicity and blocking of IL-1 signaling as modes of action. Collectively, these results provide important evidence in support of IL1RAP as a target for antibody-based treatment of AML.
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