| 1. |
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| 2. |
- Akos, Dennis, et al.
(author)
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Receiver measured time in the VDL mode 4 system
- 2000
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In: IEEE 2000 Position Location and Navigation Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780358724 ; , s. 309-316
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Conference paper (peer-reviewed)abstract
- This paper details an investigation into the receiver measured time (RMT) concept of VDL Mode 4, basically the ability to derive estimates of time from the transmission of the VDL Mode 4 signals themselves. The RMT concept is based on determining the accurate time of transmission by measuring the time of arrival (TOA) of a received signal. The reverse aspect, or that of user position, can also be computed in the same manner and all computed simulations hold for errors in position. If synchronized time is available, or can be derived, then the user position can be computed based on signals from known transmitter locations. A complete, end-to-end RMT simulation model for the Gaussian filtered frequency shift keying (GFSK) and differential 8-phase shift keying (D8PSK) modulation techniques has been developed in which various transmitters, channels and receiver models as well as an RMT measurement system have been included. The timing results, which are included, are described in terms of two-sigma errors as a function of signal-to-noise ratios (SNRs). The performance varies for the different receiver structures over the typical operation region and for a 1-bit differential GFSK detector the two-sigma error is as low as 0.40 microseconds, corresponding to a ranging error of approximately 120 meters. When incorporating co-channel interference (CCI), multipath and Doppler frequency shifts the RMT performance has been shown to decrease in terms of higher two-sigma errors
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| 3. |
- Andersson, Eva, 1955, et al.
(author)
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Incidence of asthma among workers exposed to sulfur dioxide and other irritant gases
- 2006
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In: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 27:4, s. 720-5.
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Journal article (peer-reviewed)abstract
- The aim of the present study was to investigate whether repeated peak exposure (gassings) to sulphur dioxide (SO2) and other irritant gases increases the risk of new-onset asthma. A questionnaire was sent to 4,112 sulphite workers, of whom 1,919 completed the questionnaire and 396 completed the short-form questionnaire, which was sent out as a last reminder. A sample of 130 nonrespondents completed a telephone interview using the short-form questionnaire. The incidence of adult-onset, physician-diagnosed asthma during employment duration was analysed in relation to exposure to SO2 and gassings giving rise to respiratory symptoms. Incidence rates, as well as incidence rate ratios with 95% confidence interval (CI), were calculated. Further Cox regression models were used allowing assessment of hazard ratios (HR) stratified for sex and adjusted for atopy, smoking habits and age. The incidence rate for asthma among sulphite mill workers reporting gassings of SO2 was 6.2 out of 1,000 person-yrs, compared with 1.9 out of 1,000 person-yrs among subjects unexposed to SO2 and any gassings (HR (95% CI) 4.0 (2.1-7.7)). Among males reporting gassings to SO2, the HR (95% CI) for asthma was 5.8 (2.6-13) compared with unexposed males. In conclusion, repeated peak exposure to sulphur dioxide increased the incidence of asthma during work in sulphite pulp mills, which supports the hypothesis of irritant-induced asthma.
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| 4. |
- Andersson, Eva, 1955, et al.
(author)
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Incidence of chronic bronchitis in a cohort of pulp mill workers with repeated gassings to sulphur dioxide and other irritant gases
- 2013
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In: Environmental Health. - : BioMed Central (BMC). - 1476-069X. ; 12
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Occupational exposure to irritants is associated with chronic bronchitis. The aim of this study was to elucidate whether repeated peak exposures with respiratory symptoms, gassings, to sulphur dioxide (SO2) and other irritant gases could increase the risk of chronic bronchitis.METHODS: The study population comprised 3,060 Swedish pulp mill workers (84% males) from a cohort study, who completed a comprehensive questionnaire with items on chronic bronchitis symptoms, smoking habit, occupational history, and specific exposures, including gassings. 2,037 have worked in sulphite mills. Incidence rates and hazard ratios (HRs) for the observation period, 1970-2000, in relation to exposure and the frequency of repeated gassings to SO2 and other irritant gases were calculated.RESULTS: The incidence rate for chronic bronchitis among workers with repeated gassings was 3.5/1,000 person-years compared with 1.5/1,000 person-years among unexposed workers (HR 2.1, 95% confidence interval (CI) 1.4-3.1). The risk was even higher in the subgroup with frequent gassings (HR 3.2, 95% CI 2.0-5.2), particularly among never-smokers (HR 8.7, 95% CI 3.5-22).CONCLUSIONS: Repeated gassings to irritant gases increased the incidence of chronic bronchitis in our study population during and after work in pulp mills, supporting the hypothesis that occupational exposures to irritants negatively affect the airways. These results underscore the importance of preventive actions in this work environment.
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| 5. |
- Baghdadchi, Amir, 1994-, et al.
(author)
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Promoting austenite formation in laser welding of duplex stainless steel-impact of shielding gas and laser reheating
- 2021
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In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 65, s. 499-511
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Journal article (peer-reviewed)abstract
- Avoiding low austenite fractions and nitride formation are major challenges in laser welding of duplex stainless steels (DSS). The present research aims at investigating efficient means of promoting austenite formation during autogenous laser welding of DSS without sacrificing productivity. In this study, effects of shielding gas and laser reheating were investigated in welding of 1.5-mm-thick FDX 27 (UNS S82031) DSS. Four conditions were investigated: Ar-shielded welding, N2-shielded welding, Ar-shielded welding followed by Ar-shielded laser reheating, and N2-shielded welding followed by N2-shielded laser reheating. Optical microscopy, thermodynamic calculations, and Gleeble heat treatment were performed to study the evolution of microstructure and chemical composition. The austenite fraction was 22% for Ar-shielded and 39% for N2-shielded as-welded conditions. Interestingly, laser reheating did not significantly affect the austenite fraction for Ar shielding, while the austenite fraction increased to 57% for N2-shielding. The amount of nitrides was lower in N2-shielded samples compared to in Ar-shielded samples. The same trends were also observed in the heat-affected zone. The nitrogen content of weld metals, evaluated from calculated equilibrium phase diagrams and austenite fractions after Gleeble equilibrating heat treatments at 1100 °C, was 0.16% for N2-shielded and 0.11% for Ar-shielded welds, confirming the importance of nitrogen for promoting the austenite formation during welding and especially reheating. Finally, it is recommended that combining welding with pure nitrogen as shielding gas and a laser reheating pass can significantly improve austenite formation and reduce nitride formation in DSS laser welds. © 2020, The Author(s).
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| 6. |
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| 7. |
- 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
-
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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| 8. |
- Björk, Magnus, 1977, et al.
(author)
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Exposed Datapath for Efficient Computing
- 2006
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Reports (other academic/artistic)abstract
- We introduce FlexCore, which is the first exemplar of a processor based on the FlexSoC processor paradigm. TheFlexCore utilizes an exposed datapath for increased performance. Microbenchmarks yield a performance boost of a factor of two over a traditional five-stage pipeline with the same functional units as the FlexCore.We describe our approach to compiling for the FlexCore.A flexible interconnect allows the FlexCore datapath to bedynamically reconfigured as a consequence of code generation. Additionally, specialized functional units may be introduced and utilized within the same architecture and compilation framework. The exposed datapath requires a wide control word. The conducted evaluation of two micro benchmarks confirms that this increases the instruction bandwidth and memory footprint. This calls for an efficient instruction decoding as proposed in the FlexSoC paradigm.
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| 9. |
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| 10. |
- Björner Brauer, Hanna, et al.
(author)
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Pain Relieving Light - (How) Is it Possible?
- 2024. - 1
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In: IOP Science home Accessibility Help Journals Books Publishing Support Login IOP Conference Series: Earth and Environmental Science. - 1755-1307. ; 1320
-
Conference paper (peer-reviewed)abstract
- About 15% of the population suffer from migraines and it is estimated that about 40% of all people with migraines would benefit from preventive treatment, but only 3-13% use it. Migraine is a huge burden for society and individuals. Migraines can be intensified by light, and some patients need to stay in a dark room until the attack is over. People with this type of photosensitivity show a clear preference for light color, specifically green, which has been shown to be more comfortable and even pain relieving in some cases. We will present a feasibility study with the aim of preparing a series of experiments to investigate if regular short-term green-light-exposure can prevent migraines. We will present findings from the literature, developed light equipment, and plans for future testing of migraine friendly light solutions.
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| 11. |
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| 12. |
- 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
-
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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| 13. |
- Bogo, Renata, et al.
(author)
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The Role of Genetic Factors for Hearing Deterioration Across 20 Years : A Twin Study
- 2015
-
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
-
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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| 14. |
- Churakov, Mikhail, et al.
(author)
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Milk fatty acids as indicators of negative energy balance of dairy cows in early lactation
- 2021
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In: Animal. - : Elsevier BV. - 1751-7311 .- 1751-732X. ; 15
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Journal article (peer-reviewed)abstract
- Most dairy cows experience negative energy balance (NEB) in early lactation because energy demand for milk synthesis is not met by energy intake. Excessive NEB may lead to metabolic disorders and impaired fertility. To optimize herd management, it is useful to detect cows in NEB in early lactation, but direct calculation of NEB is not feasible in commercial herds. Alternative methods rely on fat-to-protein ratio in milk or on concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) in blood. Here, we considered methods to assess energy balance (EB) of dairy cows based on the fatty acid (FA) composition in milk. Short- and medium-chain FAs (primarily, C14:0) are typically synthesized de novo in the mammary gland and their proportions in milk fat decrease during NEB. Long-chain FAs C18:0 and C18:1 cis-9 are typically released from body fat depots during NEB, and their proportions increase. In this study, these FAs were routinely determined by Fourier-transform infrared spectroscopy (FTIR) of individual milk samples. We performed an experiment on 85 dairy cows in early lactation, fed the same concentrate ration of up to 5 kg per day and forage ad libitum. Daily milk yield and feed intake were automatically recorded. During lactation weeks 2, 4, and 6 after calving, two milk samples were collected for FTIR spectroscopy, Tuesday evening and Wednesday morning, blood plasma samples were collected Thursday morning. Net energy content in feed and net energy required for maintenance and lactation were estimated to derive EB, which was used to compare alternative indicators of severe NEB. Linear univariate models for EB based on NEFA concentration (deviance explained = 0.13) and other metabolites in blood plasma were outperformed by models based on concentrations of metabolites in milk: fat (0.27), fat-to-protein ratio (0.18), BHB (0.20), and especially C18:0 (0.28) and C18:1 cis-9 (0.39). Analysis of generalized additive models (GAM) revealed that models based on milk variables performed better than those based on blood plasma (deviance explained 0.46 vs. 0.21). C18:0 and C18:1 cis-9 also performed better in severe NEB prediction for EB cut-off values ranging from −50 to 0 MJ NEL/d. Overall, concentrations of C18:0 and C18:1 cis-9 in milk, milk fat, and milk BHB were the best variables for early detection of cows in severe NEB. Thus, milk FA concentrations in whole milk can be useful to identify NEB in early-lactation cows.
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| 15. |
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| 16. |
- 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
-
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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| 17. |
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| 18. |
- Haraldsson, Kjell, et al.
(author)
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Koll på Europa
- 2008
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Book (pop. science, debate, etc.)
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| 19. |
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| 20. |
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| 21. |
- Haraldsson, Kjell, et al.
(author)
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Koll på Sverige
- 2007
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Book (pop. science, debate, etc.)
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Haraldsson, Kjell, 1950-, et al.
(author)
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Världen.
- 2009
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Book (pop. science, debate, etc.)
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| 28. |
- 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
-
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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| 29. |
- Hedin, Lage, et al.
(author)
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N1s and O1s double ionization of the NO and N2O molecules
- 2014
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In: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 140:4, s. 044309-
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Journal article (peer-reviewed)abstract
- Single-site N1s and O1s double core ionisation of the NO and N2O molecules has been studied using a magnetic bottle many-electron coincidence time-of-flight spectrometer at photon energies of 1100 eV and 1300 eV. The double core hole energies obtained for NO are 904.8 eV (N1s(-2)) and 1179.4 eV (O1s(-2)). The corresponding energies obtained for N2O are 896.9 eV (terminal N1s(-2)), 906.5 eV (central N1s(-2)), and 1174.1 eV (O1s(-2)). The ratio between the double and single ionisation energies are in all cases close or equal to 2.20. Large chemical shifts are observed in some cases which suggest that reorganisation of the electrons upon the double ionization is significant. Delta-self-consistent field and complete active space self-consistent field (CASSCF) calculations were performed for both molecules and they are in good agreement with these results. Auger spectra of N2O, associated with the decay of the terminal and central N1s(-2) as well as with the O1s(-2) dicationic states, were extracted showing the two electrons emitted as a result of filling the double core holes. The spectra, which are interpreted using CASSCF and complete active space configuration interaction calculations, show atomic-like character. The cross section ratio between double and single core hole creation was estimated as 1.6 x 10(-3) for nitrogen at 1100 eV and as 1.3 x 10(-3) for oxygen at 1300 eV.
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| 30. |
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| 31. |
- Hellgren, Johan, 1965, et al.
(author)
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Population-based study of non-infectious rhinitis in relation to occupational exposure, age, sex, and smoking
- 2002
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In: Am J Ind Med. ; 42:1
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Journal article (peer-reviewed)abstract
- BackgroundMany types of occupational exposure are associated with the risk of non-infectious rhinitis. We investigate the risk factors for this association.MethodsA random population of 2,044 subjects (aged 21-51) answered a questionnaire that was comprised of detailed questions on occupational exposure, nasal complaints, and smoking. NIR was defined as the sensation of nasal blockage and/or attacks of sneezing without having a cold. The incidence rates for NIR among exposed and unexposed were calculated. In the different exposed groups, only NIR with onset after the start of exposure was regarded as exposed. If a subject reported NIR before the relevant exposure started, he/she was excluded from that analysis. Relative risks (RR) were calculated as incidence rate ratios. Odds ratios controlling for smoking, age, and atopy were also calculated.ResultsThe incidence rate for NIR was 13.5/1,000 person-years. Males exposed to fire fumes (RR 2.5, 95% confidence interval (CI) 1.5-4.1), women exposed to paper dust (RR 2.0, 95% CI 1.5-2.9), and male cleaners (RR 3.1, 95% CI 1.9-5.1) displayed an increased risk of developing NIR. Smoking was associated with an increased risk of NIR for both sexes.ConclusionExposure to several occupational irritants is associated with a higher risk of developing NIR. Am. J. Ind. Med. 42:23-28, 2002.
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| 32. |
- Hellgren, Johan, 1965, et al.
(author)
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Quality of life in non-infectious rhinitis and asthma
- 2004
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In: Rhinology. ; 42:4
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Journal article (peer-reviewed)abstract
- In this study we evaluated how the quality of life in subjects with asthma was affected by a history of non-infectious rhinitis. The study comprised 180 persons with asthma and 156 controls, who answered the Short Form 36 quality of life questionnaire. Both the asthma subjects and the controls were stratified according to a history of non-infectious rhinitis (NIR). The global physical quality of life score (PCS) was significantly lower for all the asthma subjects regardless of their previous history of NIR compared to controls (NIR positive asthma, -8, p=O,001, NIR negative asthma, -9, p=0, 001). The subjects with asthma and a positive history of NIR obtained significantly lower scores for their global mental quality of life (MCS) than the controls (46 vs 51, p=0.004). The subjects with asthma and a negative history of NIR obtained MCS scores that were similar to those of the controls (50 and 51, p=0.9). In this population based study, the physical Qol of the subjects with asthma was lower regardless of a previous history of NIR compared to controls. A positive history of NIR in asthma was however associated with a poorer mental Qol.
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| 33. |
- Hellgren, Johan, 1965, et al.
(author)
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The dilemma of occupational rhinitis: management options
- 2003
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In: Am J Respir Med. ; 2:4, s. 333-41
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Journal article (peer-reviewed)abstract
- Occupational rhinitis is a common heterogeneous group of inflammatory conditions in the nose, caused by exposure to airborne irritants and sensitizers in the occupational environment. The mechanism can be allergic, neurogenic or toxic.Data from several epidemiologic studies indicate that animal dander, organic dusts, latex and chemicals can cause occupational rhinitis, but because of methodological problems as well as weaknesses in the definition of occupational rhinitis, occupational exposure is probably an underestimated cause of rhinitis. The effect of rhinitis on the mental aspects of quality of life and substantial costs due to loss of productivity make it important to diagnose and treat occupational rhinitis. Diagnosis relies on a history of exposure, skin prick testing and, if possible, nasal provoacation. Avoidance of exposure, protective measures at the workplace and medical treatment, with agents such as second generation antihistamines and nasal corticosteroids, can make it possible to avoid progress of the disease from rhinitis to asthma. The efficacies of montelukast, a leukotrienne receptor antagonist, and omalizumab, an anti-immunoglobulin E monoclonal antibody in the treatment of occupational rhinitis are yet to be evaluated
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| 34. |
- Holtstam, Dan, 1963-, et al.
(author)
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Garpenbergite, Mn6□As5+Sb5+O10(OH)2, a new mineral related to manganostibite, from the Garpenberg Zn–Pb–Ag deposit, Sweden
- 2022
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In: Mineralogical magazine. - : Mineralogical Society. - 0026-461X .- 1471-8022. ; 86:1, s. 1-8
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Journal article (peer-reviewed)abstract
- Garpenbergite is a new mineral (IMA2020-099) from the Garpenberg Norra mine, Hedemora, Dalarna, Sweden. It occurs with carlfrancisite and minor stibarsen, paradocrasite and filipstadite in a fractured skarn matrix of granular jacobsite, alleghanyite, kutnohorite and dolomite. Crystals are short-prismatic, up to 1.5 mm in length. They have a blackish to greyish brown colour, and are lustrous semi-opaque, with brown streak. Garpenbergite is brittle, with an uneven to subconchoidal fracture. Cleavage is distinct on {010}. Hardness ≈ 5 (Mohs) and VHN100 = 650(40). Dcalc = 4.47(1) g⋅cm−3 , overall ncalc = 1.85. Maximum specular reflectance values (%) obtained are 9.2 (470 nm), 9.1 (546 nm), 9.0 (589 nm) and 8.9 (650 nm). The empirical chemical formula of garpenbergite, based on electron microprobe data, is (Mn2+3.97Mg1.48Mn3+0.26Zn0.29)Σ6.00(As0.89Fe3+0.04Mn3+0.06Si0.01)Σ1.00(Sb0.98Fe0.02)Σ1.00O10[(OH)1.99Cl0.01]Σ2.00. The five strongest Bragg peaks in the powder X-ray diffraction pattern [d, Å(I, %) (hkl)] are 3.05 (30) (002), 2.665 (100) (161), 2.616 (40) (301), 2.586 (25) (251) and 1.545 (45) (462). The orthorhombic unit-cell dimensions (in Å) are a = 8.6790(9), b = 18.9057(19) and c = 6.1066(6), with V = 1001.99(18) Å3 for Z = 4. The crystal structure was refined from single-crystal X-ray diffraction data in the space-group Ibmm to R1 = 3.7% for 957 reflections. Garpenbergite, ideally Mn6As5+Sb5+O10(OH)2, is isostructural with manganostibite, Mn7AsSbO12, but possesses a cation vacancy (□) at an octahedrally coordinated structural site; the two minerals are thus related by the exchange Mn2+ + 2O2– → □ + 2(OH)– . The presence of hydroxyl groups is supported by vibration bands at 3647 and 3622 cm−1 in the Raman spectrum of garpenbergite, and by bond-valence considerations.
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| 35. |
- 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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| 36. |
- 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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| 37. |
- 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
-
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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| 38. |
- Hosseini, Vahid, 1987-, et al.
(author)
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A physical simulation technique for cleaner and more sustainable research in additive manufacturing
- 2021
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 285
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Journal article (peer-reviewed)abstract
- Additive manufacturing (AM) introduces a new domain for zero waste and cleaner production. Research for verification of materials in AM and effects of the process on the material behavior, however, demands a significant amount of materials, energy, and man-hours. The design of suitable physical simulation techniques that can duplicate complex AM thermal cycles without performing AM is therefore crucial for cleaner and more sustainable AM research. This paper aims at introducing a novel technique to reproduce AM thermal cycles in a controlled way on a small sample, thereby supporting sustainable alloy verification and cleaner research. In this technique, a stationary arc is applied to a disc-shaped sample mounted on a water-cooled chamber, where the arc and water provide rapid heating and cooling, respectively. In the present study, a super duplex stainless steel (SDSS) was used as the experimental alloy to simulate the evolution of microstructure and properties during wire-arc additive manufacturing. The experiment was performed using the stationary arc with the holding time of 5 s, applied 1, 5, or 15 times. The total processing time was only 450 s (7.5 min) for the 15 a.m. thermal cycles experiment. The SDSS showed a progressive increase in the austenite fraction at 600–1200 °C and the formation of detrimental sigma phase at 700–1000 °C, but a reduction of austenite fraction above 1300 °C. The results were in good agreement with the literature, verifying the applicability of the physical simulation technique for AM research. Calculations showed that using arc heat treatment as the initial step is 6–20 times more efficient in different respects (materials, energy, and man-hours) compared to wire arc additive manufacturing. Therefore, this methodology can be implemented to gain an understanding of materials in AM applications thereby eliminating the need for investments in additive manufacturing of a specific component. © 2020
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| 39. |
- Hosseini, Vahid, 1987-, et al.
(author)
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Bead by bead study of a multipass shielded metal arc-welded super-duplex stainless steel
- 2020
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In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 64:2, s. 283-299
-
Journal article (peer-reviewed)abstract
- The present study aims at investigating bead geometry and the evolution of microstructure with thermal cycles in multipass shielded metal arc welding of a V-groove 13-mm type-2507 super-duplex stainless steel (SDSS) plate. The weld consisted of 4 beads produced with arc energies of 0.81-1.06 kJ/mm. The upper beads showed lower base metal (BM) dilution than the first bead. Thermal cycles were recorded with thermocouples, indicating that the cooling rate decreased in the as-deposited weld zone when adding a new bead. Ferrite fraction in the as-welded condition was lower for the upper beads. The austenite grain morphology in reheated passes varied depending on the local peak temperatures and the number of reheating passes. Sigma phase precipitated in a location reheated by the third and fourth passes that was subjected to a critical peak temperature for sigma precipitation. Ferrite content, measured using image analysis and Fisher FERITSCOPE technique, showed that the ferrite fraction moved toward 50/50% in the weld metal with an increasing number of reheating cycles. Finally, a schematic map showing an overview of the microstructure in the multipass SDSS weld was introduced.
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| 40. |
- 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
-
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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| 41. |
- Hosseini, Vahid, 1987-, et al.
(author)
-
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
-
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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| 42. |
- Hosseini, Vahid, et al.
(author)
-
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
-
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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| 43. |
- Hosseini, Vahid, 1987-, et al.
(author)
-
Precipitation kinetics of Cu-rich particles in super duplex stainless steels
- 2021
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In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 15, s. 3951-3964
-
Journal article (peer-reviewed)abstract
- Complex precipitation behavior of Cu-rich particles (CRPs) was investigated and simulated in continuously cooled and quench-aged super duplex stainless steel. Atom probe tomography (APT) and scanning electron microscopy showed that slow cooling resulted in nonuniform multimodal CRP precipitation and spinodal decomposition, while in the fast cooled and quench-aged conditions, more uniform precipitation of CRPs with no visible spinodal decomposition was found. Depletion of Cu, Ni, and Mn was observed in the ferrite next to the CRPs during growth, but not during dissolution. Some evidence of Ostwald ripening was seen after slow cooling, but in the quench-aged condition, particle coalescence was observed. Large CRPs disappeared next to a ferrite–austenite phase boundary after slow cooling when Cu was depleted due to the diffusion to austenite as also predicted by moving boundary Dictra simulation. Comparing Cu depleted areas next to CRPs analyzed by APT and moving boundary Dictra simulation of CRP–ferrite showed that the effective Cu diffusion coefficient during the early-stage precipitation was about 300 times higher than the Cu diffusion coefficient in ferrite at 475 °C. Using the effective diffusion coefficient and a size-dependent interfacial energy equation, CRP size distribution was successfully predicted by the Langer–Schwartz model implemented in Thermo-Calc Prisma. Applying a short aging time and continuous cooling increased the hardness and decreased the toughness values compared to the solution annealed condition. A nonuniform distribution of Cu in ferrite, the duplex structure, and partitioning of alloying elements among different phases are factors making CRP precipitation in duplex stainless steels complex.
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| 44. |
- 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
-
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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| 45. |
- Hosseini, Vahid, 1987-, et al.
(author)
-
Wire-arc additive manufacturing of a duplex stainless steel : thermal cycle analysis and microstructure characterization
- 2019
-
In: Welding in the World. - : Springer Science and Business Media LLC. - 0043-2288 .- 1878-6669. ; 63:4, s. 975-987
-
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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| 46. |
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| 47. |
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| 48. |
- Jansson, Kjell, 1956-, et al.
(author)
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The value of repeated echocardiographic evaluation in patients with idiopathic dilated cardiomyopathy during treatment with metoprolol or captopril
- 2000
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In: Scandinavian Cardiovascular Journal. - 1401-7431 .- 1651-2006. ; 34:3, s. 293-300
-
Journal article (peer-reviewed)abstract
- Serial echocardiographic investigations were carried out on patients with idiopathic dilated cardiomyopathy, to evaluate treatment effects on left ventricular (LV) performance during therapy with either metoprolol or captopril. Thirty-two patients (23 males and 9 females) with mild to moderate symptoms of heart failure (NYHA II-III) and a mean age of 49 years were included in the investigation. The patients were investigated with Doppler echocardiography before treatment, after 3 and 6 months of treatment (either metoprolol or captopril) and 1 month after withdrawal of treatment. Intra- and inter-investigator reproducibility was acceptable, with a coefficient of variation of less than 5% for LV dimensions. A reduction in LV dimensions was seen in both treatment groups. In the metoprolol group there was also an increase in LV stroke volume and fractional shortening. The non-invasive data were in accordance with invasive measurements of stroke volume and LV filling pressure. In patients with idiopathic dilated cardiomyopathy and mild to moderate symptoms of heart failure, echocardiography seemed to be sufficiently reproducible to be used for determination of treatment effects in a longitudinal heart failure study. Both metoprolol and captopril were well tolerated and had favourable effects on LV performance.
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| 49. |
- 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
-
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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| 50. |
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